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PREVENTIVE  MEDICINE 
AND  HYGIENE 


PREVENTIVE    MEDICINE 
AND   HYGIENE 

BY  « 

MILTON   J.   ROSENAU 

PROFESSOR   OF    I'REVK  NTIVF.    .'MKniCINF,   AND   lIYCilKNE,    IIAUVAIil);    DIKECTOlt    OF   TIIK    SCHOOL 

OF    PUBLIC    HEALTH     OF  HARVARD   UNIVERSITY  AND  THE   MASSACHUSETl'S   INSTITUTE 

OF     TECHNOLOGY;      FORMERLY     DIRECTOR     OF     THE      HYGIENIC     LABORATORY, 

U.    S.    PUBLIC    HEALTH    SERVICE,    ETC. 

WITH    CHAPTERS   UPON 

SEWAGE    AND    GARBAGE,    BY    GEORGE     C.    WHIPPLE,    PROFESSOR     OF    SANITARY^    ENGINEERING, 

HARVARD 

VITAL  STATISTICS,  BY  JOHN  W.  TRASK,  ASSISTANT  SURGEON-GENERAL,  U.  S.   PUBLIC   HEALTH 

SERVICE 

MENTAL    HY'GIENE,    BY'    THOMAS    W.    SALMON,    MEDICAL    DIRECTOR,    NATIONAL    COMMITTEE 
FOR    MENTAL    HYGIENE,    ETC. 


FOURTH  EDITION 


NEW     YORK     AND     LONDON 
D.    APPLETON    AND      COMPANY 

1921 


Q^_ 


COPYRIGHT,  1913,  1916,  1917,  1921,  by 
D.  APPLETON  AND  COMPANY 


PltlXTED   IN    THE    rXlTED   STAT1!S   or   AMERICA 


TO 
MY    WIFE 


Digitized  by  tine  Internet  Arciiive 

in  2010  witii  funding  from 

Open  Knowledge  Commons 


http://www.archive.org/details/preventivemediciOOrose 


PREFACE  TO  THE  EIKJST  EDITION 

This  l)0()k  has  been  written  in  response  to  a  demand  for  a  treatise 
based  upon  in(i(h>ni  i)rogress  in  hygiene  and  sanitation.  Tlie  work  is 
pbiiiiii'd  to  iiicliide  those  fiehls  of  the  medical  and  related  seienees 
which  form  the  fomidation  of  public  health  work.  So  far  as  1  know, 
no  other  book  on  the  subject  covers  the  broad  field  considered  in  this 
volume.  The  prog-ress  in  hygiene  and  sanitation  has  been  so  rapid  that 
the  subject  of  preventive  medicine  has  become  a  specialty,  and  its  scope 
has  become  so  broad  that  the  question  throughout  the  making  of  this 
book  has  been  rather  what  to  leave  out  than  what  to  include.  The  facts 
here  brought  together  are  widely  scattered  in  the  literature  and  many  of 
them  are  difficult  of  access :  they  have  been  collected  for  the  convenience 
of  the  student  of  medicine  and  the  physician,  as  well  as  those  engaged 
in  sanitary  engineering  or  public  health  work. 

During  twenty-three  years  of  varied  experience  in  public  health 
work  it  has  been  my  good  fortime  to  have  served  as  quarantine  officer, 
in  epidemic  campaigns,  in  epidemiological  investigations,  and  in  public 
health  laboratories,  at  home,  on  the  Continent,  and  in  the  tropics.  The 
fruits  of  these  experiences  are  reflected  in  this  book,  which  may  be  taken 
as  representing  my  personal  views  gained  in  the  field,  in  the  laboratory, 
in  the  classroom,  and  in  administrative  offices. 

It  is  Mell-nigh  impossible  to  prevent  or  suppress  a  communicable 
disease  without  a  knowledge  of  its  mode  of  transmission.  This  is 
the  most  important  single  fact  for  successful  personal  prophylaxis,  as 
well  as  in  the  general  warfare  against  infection;  therefore  the  com- 
municable diseases  have  been  grouped  in  accordance  with  their  modes  of 
transference'.  Each  one  of  the  important  communicable  diseases  is  dis- 
cussed separately  in  order  to  bring  out  the  salient  points  upon  which 
prevention  is  based.  The  classification  adopted  is  believed  to  be  unique 
and  should  prove  helpful  to  tJiose  who  are  especially  concerned  in  the 
prevention  of  infection. 

The  book  may  be  considered  in  two  parts,  namely,  that  which  deals 
with  the  person  (hygiene)  and  that  which  deals  with  the  environment 
(sanitation).  The  first  part  includes  the  prevention  of  the  communicable 
diseases,  A'enereal  prophylaxis,  heredity,  immunity,  eugenics,  and  similar 
subjects.  The  second  part  deals  with  our  environment  in  its  relation 
to  health  and  disease  and  includes  a  discussion  of  food,  water,  air,  soil, 
disposal  of   wastes,   vital  statistics,   diseases   of  occupation,   industrial 

vii 


viii  PREFACE   TO   THE   FIRST   EDITION 

hygiene,  school  hygiene,  disinfection,  quarantine,  isolation,  and  other 
topics  of  sanitary  importance,  as  well  as  subjects  of  interest  to  health 
officers.  All  the  important  methods  used  in  public  health  laboratories 
are  described. 

To  have  made  this  book  in  monographic  style  with  references  to 
authorities  for  every  statement  would  have  resulted  in  an  un^^^eldy 
work  of  impractical  size  and  form.  The  textbook  style  has  therefore  been 
adopted  and  citation  of  authorities  for  facts  that  are  now  well  estab- 
lished has  been  regarded  as  unnecessary.  In  this  respect  it  may  seem 
that  I  have  given  scant  credit  to  many  workers  from  whose  writings 
I  have  borrowed  results,  thoughts,  and  sometimes  words  or  even  sen- 
tences. At  the  end  of  each  chapter  will  be  found  a  list  of  references 
to  articles  or  books  that  I  have  especially  drawn  upon,  and  I  desire  to 
acknowledge  my  obligations  to  these  sources  as  well  as  to  refer  the  reader 
to  them  for  further  study  of  particular  subjects.  I  have  also  draAvn 
freely  upon  my  own  previous  writings  and  those  of  my  co-workers  in 
coriipiling  this  book.  The  chapter  on  "Disinfection"'  is  based  upon  my 
book  entitled :  "Disinfection  and  Disinfections."  published  by  P.  Blaki- 
ston's  Sons  &  Co.,  Philadelphia,  1902. 

I  have  received  generous  help  from  a  number  of  friends  and  it  is  a 
pleasure  here  to  acknowledge  especially  my  obligation  to  Dr,  David  L. 
Edsall  for  reading  and  correcting  the  chapter  on  Diseases  of  Occupa- 
tions, to  Dr.  John  F.  Anderson  and  Dr.  Joseph  Goldberger  for  re- 
vising the  chapters  upon  Measles  and  Typhus  Fever,  to  Prof.  George 
C.  Whipple  for  reading  and  improving  the  chapter  upon  "Water,  to 
Charles  T.  Brues  for  many  suggestions  in  the  section  upon  insect-borne 
diseases,  and  to  Prof.  W.  E.  Castle  for  a  similar  service  with  the  section 
on  Heredity.  Dr.  Charles  Wardell  Stiles  has  kindly  furnished  infor- 
mation concerning  the  relation  of  parasites  to  soil.  I  also  desire  to 
express  my  obligations  to  Prof.  Arthur  I.  Kendall,  Dr.  Harold  L.  Amoss, 
Dr.  Lewis  W.  Hackett,  Prof.  William  D.  Frost,  and  Miss  Emily  G. 
Philpotts. 

It  has  "been  my  object  to  give  in  this  volume  the  scientific  basis 
upon  which  the  prevention  of  disease  and  the  maintenance  of  health 
must  rest.  Exact  knowledge  has  taken  the  place  of  fads  and  fancies 
in  hygiene  and  sanitation;  the  capable  health  officer  now  possesses  facts 
concerning  infections  which  permit  their  prevention  and  even  their 
suppression  in  some  instances.  Many  of  these  problems  are  complicated 
with  economic  and  social  difficulties,  which  are  given  due  consideration, 
for  preventive  medicine  has  become  a  basic  factor  in  sociology. 

M.    J.    ROSEXAU 
BoSTOjST 


PREFACE  TO  THE  FOURTH  EDITION 

This  edition  has  been  largely  rewritten  and  entirely  reset.  The  fol- 
lowing new  snbjects  have  been  added :  Public  Health  Methods  and 
Measures;  Relative  Values  in  Public  Health  Work;  A  Public  Health 
Program;  Organization  of  Health  Departments;  Median  Endemic 
Index;  Housing;  Rural  Sanitation;  Public  Health  Education;  Public 
Health  .Xursing:  Drug  Addiction,  Alcoholism;  Undernutrition;  Sani- 
tary Surveys;  Infant  Mortality;  Koch's  Laws;  Intelligence  Quotient; 
Vitamins :  Oral  Hygiene ;  Ocular  Hygiene ;  Personal  Hygiene ;  and  a 
Laboratory  Course  in  Preventive  Medicine  and  Hygiene. 

The  following  diseases  are  discussed  in  this  book  for  the  first  time: 
Vincent's  Angina;  Deer-Fly  Fever;  Leishmaniasis;  Epidemic  Encepha- 
litis; Yaws;  Psychoneuroses ;  War  Edema. 

The  following  subjects  have  been  rewritten :  Venereal  Diseases  and 
Hygiene  of  Sex ;  Dysentery ;  Influenza ;  Trench  Fever ;  Mental  Defec- 
tives; Food  Poisoning;  Botulism;  Deficiency  Diseases  and  Goiter. 
More  or  less  extensive  changes  have  been  made  throughout  the  rest 
of  the  volume. 

I  have  received  letters  from  many  parts  of  the  world  calling  my 
attention  to  errors  of  commission  or  omission.  I  am  grateful  for  these 
suggestions  and  will  appreciate  others  that  may  help  improve  the  book 
and  keep  it  up  to  date.  Acknowledgment  of  special  help  is  stated  on 
page  xi. 

M.    J.    ROSENAU 

Hakvabd  Medical  School 
Boston 


ACKNOWLEDGMENTS 

In  making  this  l.o(.l^  1  liavo  enjoyed  assistance  from  many  friends. 
J  am  especially  indebted  to  the  i■ollo^vino•  fur  heli)  in  the  subjects 
named : 

1)K.  J.   1*.   Lkake,  Smallpox  and   \aecination 

Dk.  a.  i\I.  Stimson,  Rabies 

Di{.  W.  A.  HiNTOX,  Glanders,  The  Wasscrmanii  Eeaction 

Dk.  F.  n.  Yekiioeff,  Preventable  Blindness,  Ocular  Hygiene 

Dr.  a.  W.  Sellards,  Dysentery 

Dr.  E.   K.  Tyzzei!,  Leishmaniasis 

Dr.  a.  K.  Krause,  Tuberculosis 

Dr.  E.  H.  Place,  Diphtheria,  Scarlet  Fever,  Measles,  Whooping 
Cough 

Dr.  Eufus  Cole,  Pneumonia 

Dr.  C.  W.  Stiles,  Hookworm  Disease 

Dr.  B.  H.  Eansom,  Intestinal  Parasites 

Dr.  H.  E.  Carter,  Mosquitoes,  Malaria 

Dr.  L.  0.  Howard,  Flies 

Dr.  FJarry  Plotz,  Lice,  Typhus  Fever 

Dr.  G.  W.  McCoy,  Leprosy,  Anthrax 

Dr.  E.  H.'  Creel^  Maritime  Quarantine 

Dr.  J.  Broxfexbrenner,  Immunity 

Dr.  J.  E.  Mohler,  Meat  Inspection 

Dr.  J.  GoLDBERGER,  Pellagra 

Dr.  C.-E.  a.  WmsLOW,  Ventilation 

Dr.  Alice  Hamilton,  Industrial  Hygiene 

Dr.  G.  C.  Whipple,  Sewage,  Garbage  and  Eefuse 

Dr.  J.  W.  Trask,  Vital  Statistics 

Dr.  T.  W.  Salmon,  Mental  Hygiene 

Lieutenant  Colonel  C.  F.  Foster,  Major  J.  E.  Bayliss,  Major  E.  E. 
Hume  and  Major  G.  F,  Lull  read  and  corrected  the  chapter  on  Military 
Hygiene.  My  colleagues,  Dr.  M.  J.  Schlesinger,  Dr.  Harry  Weiss,  Dr. 
D.  L.  Sisco,  Dr.  Benjamin  White,  Mr.  E.  W.  Lamson,  and  Mr.  A.  P. 
Pratt,  helped  me  see  the  book  through  the  press.  My  efficient  secretary, 
Miss  Mae  C.  Moran,  made  the  index. 

D.  Appleton  and  Company  have  met  with  unusual  difficulties  in 
publishing  a  book  of  this  size  at  this  time,  and  I  am  indebted  for  their 
cooperation,  especially  that  of  Dr.  J,  E,  Broome, 

HARVAKD  Medical  School  ^'  ^-  ^^^^NAU 

Boston 


CONTENTS 

SECTION  I 
PREVENTION  OF  THE  COMMUNICABLE  DISEASES 

CHAPTEn  '"-*'' l^- 

I.  DISEASES  HAVING  SPECIFIC  OR   SPECIAL   PROPHYLACTIC 

MEASURES       1 

Smallpox  and  Vaccination 

Historical  Note,  1;  Vaccination,  3;  Vaccine  Virus,  4;  Methods  of 
Vaccination,  9;  Indices  of  a  Successful  Vaccination,  12;  The 
Immunity,  14;  Revaccination,  18;  Claims  for  Vaccination,  20; 
Vaccination  of  Exposed  Persons,  20;  Dangers  and  Complications, 
21;  Tlie  Government  Control  of  Vaccine  Virus,  24:  The  Unity 
of  Cowpox  a'nd  Smallpox,  25;  Compulsory  Vaccination,  25; 
Inoculation  or  Variola  Inoculata,  26;  Prevalence  of  Smallpox,  28; 
Epidemiology,  29;  Modes  of  Infection,  30;  Resistance  of  the 
Virus,  31;  Smallpox  in  the  Vaccinated  and  Unvaccinated;  31; 
Isolation  and  Disinfection,  35. 

Rabies  : 

General  considerations,  38;  Period  of  Incubation,  39;  Entrance 
and  Exit  of  the  Virus,  40;  The  Relative  Danger  of  Bites,  41; 
Viability,  41;  Prophylaxis,  42;  The  Local  Treatment  of  the 
Wound,  43;  The  Pasteur  Prophylactic  Treatment,  44;  Diagnosis 
of   Rabies   in   Dogs,   51. 

Vexebeal  Diseases: 

Syphilis,  55;  Gonorrhea,  67;  Chancroid,  72. 

Venereal  Prophylaxis  and  Hygiene  of  Sex: 

Prevalence,  73;  Attitude,  75;  Education,  76;  Notification,  78; 
Continence,  79;  Personal  Hygiene,  79;  Alcohol,  80;  Prostitu- 
tion, 80;  Segregation,  81;  Medical  Prophylaxis,  81;  Hospitals 
and  Clinics,  85. 

Pkevextable  Blixdxess: 

,  Ophthalmia  Neonatorum,   87;    Trachoma.   92:    Toxic   Amblyopia, 
94;   Accidents,  94. 

Tetanus  : 

Etiology,  95 ;  Occurrence.  97 ;  Trismus  Neonatorum,  99 ;  Incuba- 
tion, 100;  Resistance,  100;  Prophylaxis,  102. 

II.  DISEASES   SPREAD  LARGELY  THROUGH  THE  ALVINE   DIS- 

CHARGES  105 

Typhoid  Fever 

General  Considerations,  105;  Historical  Landmarks,  106; 
Prevalence.  107:  Channels  of  Entrance  and  Exit,  110;  Diagnosis, 
110;  Bacillus  Carriers,  113;  Resistance  of  the  Virus,  116;  Ty- 
ph<)id  Bacillus  in  Nature,  117;  Modes  of  Spread,  118;  Typhoid 
Vaccines,  128;  Management  of  Case,  133;  Personal  Prophylaxis, 
135. 

Paratyphoid  Fever 

General  Considerations,  136;  Paratyphoid  Fever  and  Food 
Poisoning,  138. 


xiv  CONTENTS 

CHAPTER  PAGE 

Choleba 

General  Considerations,  139;  The  Cause  and  Contributing  Causes, 
139;  Diagnosis,  141;  Modes  of  Transmission,  142;  Bacillus  Car- 
riers, 144 ;  Immunity  and  Prophylactic  Inoculations,  145 ;  Quaran- 
tine, 146;  Personal  Prophylaxis,  147. 

Dysenteky 

Bacillary  Dysentery,  148;  Amebic  Dysentery,  150;  Contrast  be- 
tween Bacillary  and  Amebic  Dysentery,  151. 

Hookworm  Disease 

Distribution,  153;  Species  of  Hookworm,  154;  Modes  of  Trans- 
mission, 154;  The  Parasite,  154;  Immunity,  157;  Resistance  of 
the  Parasite,  157;   Prevention,  158;   Plan  of  Campaign,   160. 

III.     DISEASES  SPREAD  LARGELY  THROUGH  DISCHARGES  FROM 

THE  MOUTH  AXD  NOSE 163 

TUBEECtXOSIS 

General  Considerations,  163 :  The  Difference  between  Human  and 
Bovine  Tubercle  Bacilli,  165:  Bovine  Tuberculosis  in  Man..  166; 
Modes  of  Infection,  170;  Immunity,  177;  Resistance  of  the 
Virus,  180;  Prevention,  181;  Segregation — Sanatoria,  182:  Per- 
'  ^sonal   Prophylaxis,    184;    Tuberculosis    in    Children.    187:    Bovine 

Tuberculosis,  188;  Directions  for  Testing  Cattle  with  Tuberculin, 
188;  The  Bang  Method  of  Suppressing  Bovine  Tuberculosis,  189; 
Organization  of  a  Local  Tuberculosis  Campaign,  190;  Outlook, 
191. 

DlPHTHEEIA 

General  Considerations,  191;  Modes  of  Transmission,  193; 
Bacillus  Carriers,  195:  Diagnosis,  198:  Resistance.  198;  Im- 
munity, 199;  The  Schick  Reaction,  201;  The  Control  of  Out- 
breaks, 202;  Responsibility  of  the  Medical  Profession,  206;  Pre- 
vention of  Post-diphtheritic  Paralysis,  207 ;  Prevention  of  Serum 
Sickness    and    Anaphylactic    Shock,    208;    Historical   Note,    209. 

Vincent's  Angina 210 

Measles 

General  Considerations,  212;  Immunity,  213;  Resistance  of  the 
Virus,  214;  Modes  of  Transmission,  215;   Prevention,  217. 

German  Measles 219 

Scarlet  Fever 

General  Considerations,  219;  Modes  of  Transmission,  220;  Im- 
munity, 223;   Prophylaxis,  223. 

Whoopixg-Cough 

General  Considerations,  224 :  Modes  of  Transmission,  225 ;  Im- 
munity, 226;   Prevention,  226;  Mortality,  228. 

Mumps         228 

Lobar  Pneumonia 

General  Considerations,  230;  Types  of  Pneumococci,  231;  Resist- 
ance of  the  Virus,  232;  Modes  of  Transmission,  232;  Carriers, 
233;  Immunity,  2.34;  Prevention,  236;  Preventive  Measures,  237. 

Influenza 

General  Considerations,  239;  Etiology,  241;  Mode  of  Infection, 
241;  Epidemiology,  241;  Vaccines,  244;  Administrative  Meas- 
ures, 245. 

Common  Colds  ' 

General  Considerations,  246;  Prevention,  247;  Drafts  and  Chill- 
ins,  248. 


CONTENTS  XV 

CHAPTER  PAGE 

Cerebrospinal  Fever 

tk-nenil  Considerations,  250;  Epidemiology,  251;  Modes  of 
Transmission,  '252;   Carriers,  254;   Prevention,  257. 

IV.     INSECT-BOKNE  DISEASES 259 

General  Coxsiderations 259 

Insecticides  .      ' 

General  Considerations,  266;  Preparation  of  the  Room  for 
Funii<jatii)n,  266:  The  Relative  EHieiency  of  Insecticides,  267; 
Sulphur,  2(i!):  Forinaldehyd.  270:  Pyrethruni,  271:  Phenol- 
Camphor,  272:  Hydrocyanic  Acid  Gas,  273;  Bisulphid  of  Car- 
bon, 274;  Petroleum,  275;  Arsenic,  276. 

Mosquitoes 

General  Considerations,  279:  Life  History  and  Habits,  280;  The 
Destruction  of  ilosquitoes,  281;  Malaria,  286;  Yellow  Fever, 
295;   Dengue,  303;   Filariasis,  305. 

Flies 

General  Considerations,  307 ;  Life  History  of  the  Musca  Do- 
mestica,  309:  Life  History  of  Stomoxys  Calcitrans,  310;  Flies 
as  Mechanical  Carriers  of  Infection,  311;  Suppression,  315; 
Sleeping  Sickness,  317;  Deer-Fly  Fever,  321;  Pappataci  Fever,  322. 

Fleas 

General  Considerations,  322;  Pulicides,  325;  Relation  of  Plague 
to  Rats  and  Fleas,  325. 

Rats  a:sd  Other  Rodents 

General  Considerations,  328 :  Breeding  and  Prevalence,  329 ; 
Migration,  330:  On  Vessels,  331;  Food,  331;  Habits,  332;  Rat- 
Bite  Fever.  332 ;  Plague  in  Rats,  333 ;  Acute  Infectious  Jaundice, 
335;  Rat  Leprosy,  337;  Trichinosis,  337;  Food  Infection.  337; 
Other  Parasites,  337 :  Economic  Importance,  338 :  Suppression  of 
Rats,  338;  Squirrels  and  Plague,  344;  Plague,  345. 

Ticks 

General  Considerations,  354;  Texas  Fever.  356;  Rocky  Moun- 
tain Spotted  Fever,  356;  Japanese  River  Fever,  361;  Relapsing 
Fevers,  361. 

Lice 

General  Considerations,  362;  Lice  Bites  and  the  Transmission  of 
Disease,  365;   Delousing,  366:   Lice  as  a  ^Military  Problem,  369; 
-Typhus  Fever,  370;   Trench  Fever,  376. 

Bedbugs 

General  Considerations,  378;    Suppression,  379. 

Leisioianiasis 380 

Roaches 383 

V.     MISCELLANEOUS  DISEASES 386 

Infantile  Paralysis 

General  Considerations,  386;  Resistance  of  the  Virus,  389;  Im- 
munity, 390;    Modes  of  Transmission,  390;   Prevention,   392. 

Epidemic   Encephalitis 394 

Chickenpox 395 

Glanders 

General   Considerations,    396;    Diagnosis,    397;    Prevention,    400, 

Anthrax 

General   Considerations,   401;    Resistance,   402;    Prevention,   402. 

FOOT-AXD-MOUTH    DISEASE 405 


xvi  CONTENTS 

CHAPTER  PAGE 

Malta  Fever 

General  Considerations,  407 ;  Modes  of  Transmission,  407 ;  Goats' 
Milk  and  Malta  Fever,  409;  Prevention,  410. 

Yaws 410 

Leprosy 

General  Considerations,  411;  Immunity,  413;   Rat  Leprosy,  414; 

Modes  of  Transmission,  415;  Prevention,  418. 


SECTION  II 

MENTAL  HYGIENE 
By  Thomas  W.  Salmon 

General  Considerations 421 

The  Problems  of  Mental  Hygiene,  422;  Heredity,  424;  Alcohol, 
429;  Other  Exogenous  Poisons,  433;  Endogenous  Poisons,  434; 
Syphilis,  434;  Other  Infections,  437;  Head  Injuries,  438;  Men- 
tal Causes,  439;  Experience  of  the  World  War,  442;  Economic 
Factors,  449;  Immigration,  450. 

Agencies  Available  for  the  Application  of  Preventive  Medicine 
Hospitals  for  Mental  Disease,  451 ;  Public  Health  Authorities, 
452;  Educational  Authorities,  452;  National  and  Local  Societies 
for  Mental  Hygiene,  452. 

Conclusion 454 

SECTION  III 
PUBLIC  HEALTH  MEASURES  AND  METHODS 

SOME  GENERAL  CONSIDERATIONS 459 

Sources  of  Infection,  459;  Modes  of  Transference,  460;  Carriers, 
462 ;  Missed  Cases,  463 ;  Channels  of  Infection,  463 ;  "Contagious" 
and  "Infectious,"  463;  Epidemic,  Endemic,  Pandemic,  and 
Prosodemic,  464;    Fomites,   465. 

Relative  Values  of  Public  Health  Work 466 

A  Score  for  Health  Activities 468 

A  Public  Health  Program 469 

Organization  of  Health  Departments 470 

The  Median  Endemic  Index 472 

Health  Centers .  473 

Housing 473 

Rural  Sanitation 475 

Public  Health  Education 476 

Infant  Mortality 477 

Public  Health  Nursing    • 483 

Nuisances .  483 

Face  Masks 485 

Drug  Addiction 486 

Alcohol 487 

Sanitary  Surveys      . 493 

Management  of  an  Epidemic  Campaign 495 

Quarantine 498 

General  Considerations,  498;  Maritime  Quarantine,  502;  Quaran- 
.  tine  Procedures,  509 ;  The  Bill  of  Health,  509 ;  The  Equipment  of 

a  Quarantine  Station,  510;  Qualifications  of  Quarantine  Officers, 


CONTENTS  xvii 

PAGE 

511;  Disinfection  of  Ships,  511;  Fumigation  of  Sliipp,  ol.l; 
Cargo,  518;  Foreign  Inspection  Service,  518;  National  versus 
State  Quarantine,  51i>;   Interstate  Quarantine,  519. 


SKCTION^  IV 

IMMUNITY,  HEKEDITY,  AND  EUGENICS 

I.  IMMUNITY 523 

General  Considerations 523 

Mecluinisni    of    Immunity,    527;     Theories    of    Immunity,    528; 

Natural   Immunity,  530;    Acquired   Inununity,  532;    Non-Specific 

Immunity,   532;    iMixed   Immunity,   533;    How   Active    Imnuinity 

May  Be  Acquired,  533;  Bacterial  Vaccines,  535;  Specificity,  537; 

Local    and    General    Immunity,    53!);     Bacillus    Carriers,    540; 

Latency,  542;    Lowered  Resistance,  542;    Relation   between   Host 

and   Parasite,    546;    Ehrlich's    Side-Chain    Theory    of   Immunity, 

647 ;   Antitoxic  Immunity,  553. 

Toxins         553 

Antitoxins 

General    Considerations,    558;    Preparation    of    Antitoxin,    561; 

Method   of   Concentrating   Diphtheria    Antitoxin,    562;    Mode   of 

Action,  563.  , 

Endotoxins 565 

Standardization  of  Antitoxic  Sera 

Standardization   of   Diphtheria  Antitoxin,  566;    Standardization 

of  Tetanus  Antitoxin,  568. 

Phagocytosis         570 

Opsonins 574 

Lysins 575 

Hemolysis 578 

Cytotoxins       .....      579 

The  Bordet-Gengou  Phenomenon — Fixation  of  Complement 
The  Wassermann  Reaction,   581. 

The  Neisser-Wechsberg  Phenomenon  or  Deviation  of  the  Com- 
plement               ;      .     583 

Precipitins 

General  Considerations,  585;   Tests  for  Blood,  587. 

Agglutinins 589 

Anaphylaxis 

General  Considerations,  593;  Examples  of  Anaphylaxis,  594; 
Experimental  Anaphylaxis,  594;  Specificity,  596;  Sensitization 
by  Feeding,  598;  Maternal  Transmission,  598;  Serum  Anaphy- 
laxis in  Man,  598;  Hypersusceptibility  and  Immunity  Produced 
by  Bacterial  Proteins,  601;  Relation  of  Anaphylaxis  to  Protein 
Metabolism,  602;  Relation  of  Anaphylaxis  to  Endotoxins,  602; 
Relation  of  Anaphylaxis  to  Tuberculosis,  602;  Relation  of 
Anaphylaxis  to  Vaccination,  603;  Relation  of  Anaphylaxis  to 
Food  "Idiosyncrasies,"  604;  Eczema,  604;  Relation  of  Anaphy- 
laxis to  Hay  Fever,  605;  Relation  of  Anaphylaxis  to  Drugs. 
Anaphylactoid  Reactions,  605;  Other  Practical  Relations  of 
Anaphylaxis,  605. 

II.  HEREDITY  AND   EUGENICS 607 

General  Considerations 607 

Defectives,  608;  Recognition,  608;  Mongolianism,  608;  Feeble- 
minded— Idiots,  Imbeciles  and  Morons,  609 ;  Prevention  of  Propa- 


xviii  CONTENTS 

CHAPTER  P\GE 

gation  of  Defectives,  611;  Statistics  of  Defectives,  613;  De- 
generate Families,  615. 

Eugenics ; 619 

Pbixciples  of  Heredity 

Variation,  621;  Darwin's  Theory — the  Survival  of  the  Fittest, 
621;  Mutation,  622;  DeVries — Discontinuous  Evolution,  622; 
Weissmann's  Views,  623 ;  Mendel's  Law,  624 ;  Atavism  and  Rever- 
sion, 628;   Galton's  Law  of  Filial  Regression,  629. 

The  Cell  in  Heredity 629 

Statistical  Methods 631 

Heredity  versus  Environment 638 

Immunity  Gained  through  Inheritance 639 

III.     THE  HEREDITARY  TRANSMISSION  OF  DISEASE      .      .      .     '.     640 

General  Considerations 640 

Inbreeding,  642;  The  Microbic  Diseases,  643;  Congenital  Trans- 
mission, 644;  Hereditary  Transmission  of  a  Tendency  to  a  Dis- 
ease, 644 ;  Tuberculosis,  645 ;  Syphilis,  645 ;  Cancer,  646 ; 
Leprosy,  648;  Deaf -Mutism,  648;  Albinism,  649;  Color-Blind- 
ness,  or  Daltonism,  650;  Hemophilia,  651;  Gout,  651;  Brachy- 
dactylism,  652;  Polj'dactylism,  653;  Fragilitas  Ossium,  653; 
Myopia,  653;  Cataract,  653;  Retinitis  Pigmentosa,  653;  Diabetes 
Mellitus,  654;  Orthostatic  Albuminuria,  654;  Alcoholism,  654; 
Migraine,  654;  Anaphylaxis  or  Food  Idiosyncrasies,  655;  Hay 
Fever,  655;  Epilepsy,  655;  Huntington's  Chorea,  655;  Fried- 
reich's Disease — Hereditary  Ataxia,  656;  Mental  Deficiency,  658; 
Insanity,  658. 

SECTION  V 
FOOD 

I.     GENERAL  CONSIDERATIONS 661 

The  Uses  of  Food 

General  Considerations,  663;  Caloric  Value  of  Food,  664. 
Classification  of  Foods 

Physical  Properties,   666;    Sources,   666;    Chemical   Composition, 

666;   Composition  and  Function,  667. 

Vitamins 669 

The  Amount  of  Food 

Excessive  Amounts,  673;  Insufficient  Food,  674;  Famine  and 
Pestilence,  675 ;  War  Edema,  675 ;  Underfeeding  and  Growth,  676. 

Unbalanced  Diets 676 

The  Deficiency  Diseases 

General  Considerations,  677;  Beriberi,  678;  Scurvy,  683; 
Rickets,  685;   Pellagra,  686. 

Food  Poisoning 

General  Considerations,  692. 

Food  Infections 

Incubation  Period,  696 ;  Symptoms,  696 ;  Taste,  Odor  and  Ap- 
pearance, 698;  Kind  of  Food  Responsible,  698;  Diagnosis,  698; 
The  Colon-Typhoid  Group,  699;  The  Gaertner  Group,  701. 

Botulism 

General  Considerations,  706;  Prevalence,  706;  Symptoms,  708; 
Pathology,  710;  The  Bacillus,  710;  Toxin,  712;  Antitoxin,  715; 
Prevention,  716. 


CONTENTS  xix 

CHAPTER  PAOE 

Decomposed  Foods 

Geiu'ial  Consiclerations,  717;  Fermontation  and  Putrefaction, 
718;  I'utrefac'tive  Changes  in  Proteins,  719;  "Ptomain"  Poison- 
ing, 721. 

Adulteration  of  Food 725 

Preservation  of  Foods 

General  Considerations,  728:  Cold,  730;  Drying,  733;  Salting 
and  Pickling,  735;  Jellies  and  Preserves,  730;  Smoking,  737; 
Canning,  737;  Chemical  Preservatives,  741. 

The  Preparation  of  Food 

Cooking,  749;  Methods  of  Cooking,  751. 

II.     ANIMAL  FOODS:  MILK 753 

Milk 

General  Considerations,  753;  Composition,  754;  Ferments  or 
"Life"  in  Milk,  760;  Thermal  Death  Point  of  Milk  Enzymes,  761; 
"Leukocytes"  in  Milk,  762;  The  Excretion  of  Drugs  in  MUk, 
763;  The  Differences  between  Cow's  Milk  and  Woman's  Milk, 
763;  Milk  Standards,  764:  Grades  of  Milk,  765;  Certified  Milk, 
767;  "Standardized"  or  Adjusted  Milk,  768;  Pveconstructed  Milk, 
768;  The  Decomposition  of  Milk,  768;  Sour  Milk  and  Intestinal 
Flora,  769;  Putrid  Milk,  770;  Slimy  or  R6py  Milk,  771;  Alco- 
holic Fermentation  of  Milk,  771;  Bitter  Milk,  771;  Colored 
Milk,  772;  Adulterations  of  Milk.  772;  Dirtv  Milk— The  Dirt 
Test,  772;  Clarification,  773;  Bacteria  in "  Milk,  774;  The 
Germicidal  Propertv  of  Milk,  776;  Diseases  Spread  by  Milk,  777: 
The  Character  of  Milk-Borne  Epidemics,  783;  Dried  Milk,  784; 
Fresh  Milk  Products,  785;  Butter,  785;  Inspection,  788; 
Pasteurization,  788;  The  Effect  of  Heat  upon  Milk,  792;  The 
Essential  Requirements  for  a  Safe  and  Satisfactory  Milk  Supply, 
793. 

The  Bacteriological  Examination  of  Milk 

Number  of  Bacteria,  794;  Kinds  of  Bacteria,  796. 

The  Microscopic  Examination  of  Milk 

The  Stewart-Slack  Method.  797;  The  Doane-Buckley  Method, 
798;   The  Prescott-Breed  Method,  798. 

Chemical  Analysis  of  Milk  t 

Total  Solids,  798;  Determination  of  Total  Solids,  799;  Deter- 
-  mination  of  Fats,  800;  Determination  of  Milk  Sugar,  802;  Deter- 
mination of  Proteins,  804 ;  Water,  805 ;  Reaction,  806 ;  Specific 
Gravity,  807;  Field  Tests,  808;  Heated  Milk,  808;  Tests  for 
Enzymes,  and  Their  Significance,  808;  Tests  for  the  Adultera- 
tion of  Milk,  810. 

III.     ANIMAL  FOODS:   MEAT,  FISH,  EGGS,  ETC .814 

Meat 

Structure  and  Composition,  814;  Nutritive  Value,  815;  Sources, 
816;  Recognition  of  Spoiled  Meat,  817;  Prevention,  818;  Meat 
Preservatives,  818. 

Meat  Inspection 

General  Considerations,  818;  The  Abattoir,  820;  Qualifications 
of  a  Meat  Inspector,  822;  The  Freibank  or  Three-Class  Meat 
System,  822;  Emergency  Slaughter,  823;  Methods  of  Slaughter, 
824;  The  United  States  jNIeat  Inspection  Law,  825;  Ante- 
Mortem  Inspection,  825;   Post-Mortem  Inspection,  826. 

Animal  Parasites 

Trichinosis,  830;  The  Pork  or  Measly  Tapeworm,  834;  Taenia 
Saginata,  835;    Echlnococcus  Disease,   836. 


XX  CONTENTS 


CHAPTER 

Fish 


Physiological  Fish  Poisoning,  837;  Bacterial  Poisons,  838;  The 
Fish  Tapeworm,  839. 

Shellfish 

General  Considerations,  840;  Oysters,  842:  Mussel  Poisoning, 
843. 

Bob-Veal 846 

Eggs 

Nutritive  Value,  847;  Classification,  848;  Bacteria  in  Eggs,  849; 
Eggs  and  Disease,  849. 

Plant  Foods 

Tubers,  851;  Roots,  8.51;  Fruits,  851;  Carbohydrate  Food 
Preparations,  851;  How  Plants  May  Injure  Health,  851;  The 
Nutritive  Value  of  Plants,  850;  Poisoning  from  Plant  Foods, 
856. 


SECTION  VI 
AIE 

I.     COMPOSITION  OF  THE  AIR      : 865 

General  Consideeations 865 

Oxygen,  867:  Nitrogen,  869;  Argon,  869;  Ozone,  869;  Hydrogen 
Peroxid,  871;  Ammonia,  872;  Mineral  Acids,  872;  Carbon 
Dioxid,  872. 

II.     PRESSURE,   TEMPERATURE,   AND   HUMIDITY 887 

Peessuee 

Normal  Atmospheric  Pressure,  887 ;  Diminished  Atmospheric 
Pressure,  887 ;   Increased  Atmospheric  Pressure,  890. 

Movements  of  the  Atjiospheee 891 

Tempebature  of  the  Aib 

General  Considerations,  893;  Methods  of  Recording  Tempera- 
ture, 895. 

Humidity 

Aqueous  Vapor,  896 ;  Methods  of  Determining  Humidity  in  the 
Air,  900;  Relation  of  Humiditv  and  Temperature  to  Health,  904; 
The  Kata-Thermometer,  907;  "^Effects  of  Warm  Moist  Air,  910; 
Effects  of  Cold  Damp  Air,  911;   Effects  of  ^Yarm  Dry  Air,  912. 

III.     MISCELLANEOUS 914. 

Odobs 914 

Light — Ocular  Hygiene 916 

Electricity 925 

Radio-Activity 925 

Smoke 926 

Fog 929 

Dust 929 

IV.     BACTERIA  AND  POISONOUS  GASES  IN  THE  AIR     ....     936 

Bacteria  in  the  Aie 

General  Considerations,  936 ;  Method  for  Determining  Bacteria 
in  the  Air,  938;  Air  and  Infection,  939. 


CONTENTS  xxi 

rllAPTEII  VAOt 

Poisonous  Gases  in  tiik  Aik 

Carbon  Monoxid,  941;  Illuiiiinatiiiy  (Jas,  1)44;  Utlier  Gases  in 
the  Air,  94(5. 

Sewer  Gas 

General  Considerations.  949;  Bacteria  in  Sewer  Air,  9.10;  Ac- 
cidents in  Sewers,  951;  Illustrative  Cases  of  Deatli  by  Sewer 
Gas,  952;  Prevention  of  Accidents  in  Sewers,  954;  Ventilation  of 
Sewers,  954. 

V.     FRESH  AND  VITIATED  AIR 955 

The  Benefits  of  Fresh  Air 955 

The  Effects  of  Vitiated  Air 

General  Considerations,  955;  The  Effects  of  Increased  Carbon 
Dioxid  and  Diminished  Oxygen,  957;  Poisons  in  tlic  Expired 
Breath,  958;  Physical  Changes  in  the  Air,  960;  Reinspiration 
of   Expired  Air,  '963. 

Summary 964 

VI.     VENTILATION  AND  HEATING 966 

Vextilatiox 

General  Considerations,  966;  Air  Washing,  968;  Recirculation, 
968 ;  Vitiation  by  Respiration,  969 ;  Vital  Capacity  of  the  Lungs, 
969;  Dead-space' Air,  970;  Factor  of  Safety,  971;  The  Amount 
of  Air  Required,  971;  Standards  of  Purity — Efficiency  of  Venti- 
lation. 973;  The  Size  and  Shape  of  the  Room,  975;  Inlets  and 
Outlets.  977;  External  Ventilation,  979;  Natural  Ventilation, 
979;   Mechanical  Ventilation,   984. 

Heatin^g 

General  Considerations,  984;  Open  Fires,  986;  Franklin  Stoves, 
986;  Open  Gas  and  Oil  Heaters,  986;  Hot-air  Furnaces,  986; 
Hot-water  and  Steam  Pipes,  987;  Electric  Heating,  988;  The 
Cooling  of  Rooms,  988. 


SECTION  YII 
SOIL 

L     GENERAL  CONSIDERATIONS 991 

Classification  of  Soils,  992;  Surface  Configuration,  993;  Com- 
position of  the  Soil.  993:  Physical  Properties,  994;  Soil  Air, 
996:  Soil  Water,  996;  The  Nitrogen  Cvcle,  998:  The  Carbon 
Cycle,   1002. 

II.     SOIL  AND  ITS  RELATION  TO  DISEASE 1003 

Bacteria  in  Soil,  1003;  Pollution  of  the  Soil.  1004;  Dirt,  1005; 
Cleanliness,  1006;  Influence  of  Soil  upon  Health,  1007;  Diseases 
Associated  with  Soil,   1007. 


SECTION  YIII 
WATEK 

GENERAL  CONSIDERATIONS 1015 

Composition,  1015;  Classification.  1016;  Properties,  1017;  Uses 
in  the  Body,  1017;.  Amount  Used  and  Wasted,  lOlS;  Dual  Water 
Supply,  1021. 


xxii  CONTENTS 


SOUECES   OF   WATEK 

Eain  Water,  1022;   Surface  Waters,  1020;   Ground  Water,   1032. 

SOUKCES    AND    NaTUKE   OF    WaTEE   PoLLUTLON   AND    INFECTION 

General  Considerations,  10-13;  Simple  Tests  to  Determine  Sources 
of  Pollution,  1043;  Interstate  Pollution  of  Streams.  1044:  Pollu- 
tion of  International  Boundary  Waters,  1045;  The  Care  of  Catch- 
ment Areas,   104G. 

II.     SANITARY  ANALYSIS   OF  WATER 1048 

Standard  Methods     .     .' 1048 

Odoks  and  Taste 

General  Considerations,  1050;  Method  of  Determining  Odor,  1051; 
Prevention  and  Removal  of  Tastes  and  Odors,  1054. 

COLOB 

General  Considerations,  1055 ;  Method  for  Estimating  Color, 
1056;  Platinum-Cobalt  Standard,  1056. 

Tuebidity 

General  Considerations,  1057;  Methods  for  Estimating  Turbidity, 
1058. 

Reaction" 1059 

Total  Solids ^ 1060 

Haedness 

General   Considerations,    1061;    Methods,    1063. 

Oeganic  Matter 

Free  Ammonia,  1066;  Albuminoid  Ammonia,  1069;  Nitrites, 
1071;  Nitrates,  1072. 

Chlorids 1074 

Chlorin , 1075 

Oxygen 

Oxygen  Consumed,  1077 ;   Dissolved  Oxygen,  1079. 
Iron 

General  Considerations,  1080;  Iron  Pipes,  1081. 
Lead 

Tests,  1082. 

III.      MICROSCOPICAL  EXAMINATION  OF  WATER 1084 

The  Sedgwick-Rafter  Method,  1084;  Significance  of  Ihe  Examina- 
tion, 1086. 

Bacteriological  Examination 

The  Number  of  Bacteria  in  Water,  1087 ;  Method  for  Determin- 
ing the  Number  of  Bacteria  in  Water,  1089;  Kinds  of  Bacteria 
in  Water,  1090. 

IV.     INTERPRETATION  OF  SANITARY  WATER  ANALYSIS     .      .      .    lOHG 

General  Considerations 1096 

Allowable  Limits,  1097 ;   Illustrative  Analyses  Interpreted,   1099. 

V.     THE  PURIFICATION  OF  WATER     .      .      . 1108 

Nature's  Methods  of  Purifying  Water 

General  Considerations,  -1108;  Evaporation  and  Condensation, 
1109;  Self-purification  of  Streams,  1109;  Storage  in  Lakes  and 
Ponds,  1111. 


CONTENTS  xxiii 

CHAPTEU  PAGE 

Distilled  Water 1112 

Boiled  Water 1112 

Filters 

Slow  Rand  Filters,  1113;  INk'oIianieal  Filtora.  1122;  Household 
Filters.  1127;  Scrubbing  or  Roughing  Filters,  1128;  Screening, 
112S. 

Storage ■ 1128 

Sedimentation 1129 

Chemical  ]\Ietiiods  of  Purifying  Water 

Ozone,  1129;  Clilorinated  Lime — Bleaciiing  Powder  or  "Ciilorid 
of  Lime,"  1132;  Chlorin,  1131);  Permanganate  of  Potash,  1140; 
Alum  or  Sulphate  of  Aluminium,  1141;  Sulphate  of  Iron  and 
Lime,  1142:  Metallic  Iron:  The  Anderson  Process,  1143;  Cop- 
per Sulphate,  1143. 

Ultraviolet  Rats 1144 

VI.     WATER  AND  ITS  RELATION  TO  DISEASE 1147 

General  Considerations 1147 

The  Mills-Reincke  Phenomenon 1148 

Non-Specific  Diseases  Due  to  Water 

General  Considerations,  1149;  Goiter,  1150;  Lead  Poisoning, 
1155. 

Specific  Diseases  Due  to  Water 

General  Considerations,  1159;  Cholera.  1161;  Typhoid  Fever, 
1167;   Dysentery,  1179;  Diarrhea.   1180;  Animal  Parasites,  1181. 

Sanitation  of  Swimming  Pools 1182 

Drinking  Fountain 1184 

Ice 

General  Considerations,  1184;  Natural  Ice,  1186;  Manufactured 
Ice,  1187;  Ice  and  Disease,  1188. 


SECTION  IX 

SEWAGE  DISPOSAL 
By  George  C.  Whipple 

General  Considerations 1191 

Importance  of  Speedy  Removal  of  Fecal  Matter,  1191;  Dry 
Earth  System,  1192;  Water  Carriage  System,  1192;  Separate 
and  Combined  Systems,  1193;  Quantity  of  Sewage,  1194;  Com- 
position of  Sewage,  1194;  Ventilation  and  Flushing  of  Sewers, 
1196. 

Stream  Pollution 

Sewage  Disposal  by  Dilution,  1196;  Hygienic  Aspects  of  Stream 
Pollution,  1198;  Protection  against  Pollution,  1199;  Funda- 
mental Principles  of  Sewage  Treatment.  1200:  Preparatory 
Processes.  1200;  Purification  Processes.  1204:  Finishing  Proc- 
esses, 1209;  Choice  of  Methods,  1209;  Relative  Bacterial  Effi- 
ciency of  Different  Processes,  1210;  Management  of  Sewage 
Treatment  Works,  1211;  Treatment  Plants  as  Nuisances,  1211; 
Nuisances  Caused  by  Trade  Wastes,  1212. 

Cooperative  Sanitation 1212 

The  Rural  Problem  of  Sewage  Disposal 1213 


xxiv  CONTENTS 

SECTION  X 

EEFUSE  DISPOSAL       - 
By  George  C.  Whipple 

PAGK 

Genebal  Considerations 1219 

Incineration  Plants,  1221;  Reduction  Plants,  1223;  Feeding 
Garbage  to  Hogs,  1224;  Collection  of  Garbage,  1224. 

SECTION   XI 

VITAL  STATISTICS 
By  John  W.  Trask 

General  Considerations 1225 

Vital  Statistics 

Definition,  1227;  Development,  1227;  Based  upon  Population, 
1228. 

Population  Statistics 

Source  of  Data,  1228;  Nature  of  Census  Information,  1229; 
Sources  of  Error  in  Census  Enumerations,  1229 ;  Fluctuation  in 
Population,  1230;   Estimates  of  Population,  1230. 

Marriage  Statistics 

Marriage  Rates,  1234;  Factors  Influencing  Marriage  Rates,  1234; 
Uses  of  Marriage  Registration,   1234. 

Birth  Statistics 

Registration  in  the  United  States,  1235;  Birth  Rates,  1238; 
Sources  of  Error  in  Birth  Statistics,  1239 ;  Uses  of  Birth  Regis- 
tration and  Statistics,  1240;  Factors  Influencing  Birth  Rates, 
1241. 

Morbidity  Statistics 

General  Considerations,  1242;  Morbidity  Statistics  in  the  United 
States,  1243;  The  Model  Law  for  Morbidity  Reports,  1245;  Re- 
sults of  Notification  in  Certain  States  and  Cities,  1246 ;  Source 
of  Statistical  Data,  1247 ;  Nature  of  Information  Secured  by 
Morbidity  Notification,  1251;  Standard  Notification  Blank,  1251; 
Sources  of  Error  in  Morbidity  Statistics,  1252;  Uses  of  Mor- 
bidity Reports  and  Statistics,  1253;  Morbidity  Rates,  1254; 
Hospital  Statistics  and  Sickness  Insurance  Records,  1255 ;  Fac- 
tors Influencing  Morbidity  Rates,  1255 ;  Notification  of  Occupa- 
tional Diseases,  1255;  Morbidity  Statistics  of  Military  Popula- 
tions,  1257. 

Mortality  Statistics 

General  Considerations,  1259;  Registration  of  Deaths  in  the 
United  States,  1260;  United  States  Registration  Area  for  Deaths, 
1260;  Source  of  Data,  1261;  The  Standard  Death  Certificate, 
1262;  Sources  of  Error,  1262;  Uses  of  Death  Registration,  1266 ; 
Death  Rates,  1267;  Factors  Affecting  Death  Rates,  1270;  Inter- 
national List  of  Causes  of  Death,  1272. 

Infant  Mortality 1275 

Life  Tables 1276 

SECTION  XII 

INDUSTEIAL  HYGIENE  AND  DISEASES  OF 
OCCUPATION 
General  Considerations 1279 

Some  Fundamental  Considerations  in  Prevention 

General  Considerations,  1283;  Hours  of  Work,  1284;  Fatigue, 
1284;  Minors,  1286;  Women,  1287;  Factory  Inspection,  1289; 
Preventable  Accidents,  1290;  Sedentary  Occupations,  1291. 


CONTENTS  XXV 

CHAPTER  PAGE 

Diseases  of  Occupation 

Glassifk-ution  of  llie  Oiriipatioiial  Disoaaes,  121>2;  Lead,  1203; 
Phosplioriis,  i;{();};  Arsoiiic,  l.Jd.");  Mercury,  i:U)7;  Carbon 
Monoxid,  l.SOH;  llydroj^'cn  Snlphid,  i:{<)!):  Other  Industrial 
Poisons,  l.UO;  Dustv  Trades,  l;{i;{;  Tlie  Textile  industries,  ^•^\^)■. 
Wood  Dust.  1319;  Mininfr,  l;n!»;  Effects  of  Heat,  1321;  Com- 
municable Infections,  1322;   Caisson  Disease,   1324. 

SECTION  Xlll 
SCHOOL  SANITATION  AND  PERSONAL  HYGIENE 

General  Considekations 1325 

Healtli  Education.  1328;  School  Building,  1328;  Tiie  School- 
room, 1329;  The  School  Furniture,  1330;  Posture,  1334;  Recess, 
1334;  Lighting,  1335;  Ventilation  and  Heating,  1336;  Open  Air 
Schools,  1337;  Water-closets  and  Urinals,  1337;  Cleanliness, 
1338;  Medical  Inspection,  1338;  The  Communicable  Diseases  of 
Childhood,  1341;  Closing  Schools  on  Account  of  Epidemics,  1342; 
The  Eyes,  1342;  The  Ears,  1343;  Oral  Prophylaxis,  1343;  Nose 
and  Throat,  1346;  Diseases  of  the  Skin,  1347;  Nervous  Diseases 
and  Mental  Defects,  1348;  Chorea,  1348;  Vaccination,  1350. 

SECTION  XIV 
DISINFECTION 

I.     GENERAL  CONSIDERATIONS 1351 

Disinfection,  1351;  Nature's  Disinfecting  Agencies,  1353;  Cleanli- 
ness, 1353;  Antibiosis  and  Symbiosis,  1354;  When  and  Where  to 
Disinfect,  1355;  Qualifications  of  the  Disinfector,  1355;  Con- 
trols, 1356;  Disinfection  Must  Be  in  Excess  of  Requirements, 
1356;  Specificity  of  Germicides,  1356;  Chemotherapy,  1357;  The 
Ideal  Disinfectant,  1357;  Concurrent  Disinfection,  1357;  Ter- 
minal Disinfection,  1357;  Penetration,  1358;  Organic  Matter, 
1359;  Time,  1359;  Speed  of  Disinfection  and  Stability  of  Dis- 
infectants, 1360;  Temperature,  1360;  Emulsions  and  Solutions, 
1361;  Dilution,  1362;  Reaction,  1362;  The  Mechanism  of 
Bactericidal  Action,  1362;  The  Choice  of  Germicide,  1364. 

The  Staxdakdization  of  Disixfectaxts 

,  General    Considerations,    1364;    Methods,    1365;    Carbolic    Coeffi- 
cient,  1366. 

II.     PHYSICAL  AGENTS   OF  DISINFECTION 1375 

Sunlight,  1375;   Ultraviolet  Rays,  1375;   Electricity,  1377;   Pres- 
•  sure,    1377;    Burning,    1377;    Dry    Heat,    1378;    I3oiling,    1378; 
Steam,   1379. 

III.     CHEMICAL  AGENTS   OF  DISINFECTION 1390 

Gaseous  Disinfectants — Fumigation 

Preparation  of  the  Room,  1390;  Formaldehyd  Gas,  1391;  Sul- 
phur Dioxid,  1396;  Hydrocyanic  Acid  Gas,  1402;  Chlorin,  1403; 
Oxygen,  1404;  Ozone,  1404. 

Liquid  Disinfectants 

General  Considerations,  1404;  Methods  of  Using  Chemical  Solu- 
tions, 1405;  Metallic  Salts,  1406;  Bichlorid  of  Mercury,  1406; 
Silver  Salts,  1407;  Zinc  Salts,  1408;  Ferrous  Sulphate,  1408; 
Sulphate  of  Copper,  1408;  Coal  Tar  Creosote,  1408;  Carbolic 
Acid,  1409;  Phenol,  1410;  The  Cresols,  1411;  Liquor  Cresolis 
Compositus.  1412;  Lvsol,  1412;  Creolin,  1412;  Aseptol,  1412; 
Asaprol,  1413;  Sanatol,  1413;  Solveol  and  Solutol,  1413;  Naph- 


xxvi  CONTENTS 

CHAPTER  PAGE 

thols,  1413;  Ambrine,  1413;  Naphthalene,  1413;  Formalin,  1414; 
Potassium  Permanganate,  1415;  Hydrogen  Peroxid  and  Other 
Peroxids,  1415;  Lime,  1416;  Bromin  and  lodin,  1417;  Anti- 
formin,  1421;  Dyestuffs,  1422;  Acids,  1422;  Alcohol,  1423;  Soaps, 
142'4. 

Convenient  Formula  fob  Disinfecting  Solutions 

Bichlorid  of  Mercury — Corrosive  Sublimate,  1425;  Formalin, 
1425;  Milk  of  Lime,  1426;  Carbolic  Acid,  1426;  Chlorinated 
Lime,  1426. 

IV.     METHODS  OF  DISINFECTIOIST 1439 

Air,  1427;  Stables,  1428;  Railroad  Cars,  1430;  Feces,  14.32; 
Sputum,  1434;  Bed  and  Body  Linen,  1435;  Books,  1435; 
Cadavers,  1436;   Thermometers,  1437;   Wells  and  Cisterns,  1437. 

SECTION  XV 
MILITAKY  HYGIENE 

Genebal  Considebations 

Comparative  Loss  in  Campaign  from  Sickness  and  Wounds, 
1441. 

Recbuits  and  Recbuiting 

General  Considerations,  1442;  The  Physical  Examination,  1444; 
Age,  1444;  Character  and  Mental  Condition,  1445;  Height, 
Weight  and  Chest  Measurements,  1446;  Vision,  1447;  Teeth, 
1448;  Vaccination,  1448;   General,  1448;   Training,  1449, 

Duties  of  the  Medical  Offices 1450 

Equipment  . 

General  Considerations,  1451';  The  First-aid  Packet,  1453; 
Clothing,  1454. 

Diseases  of  the  Soldier 

General  Considerations,  1458;   War  Gases,  1459. 

Sanitation  in  Camp  and  on  the  March 

Personal  Hygiene  of  the  Soldier,  1459;  The  March,  1459; 
Forced  Marches,  1461;  Discipline  and  Sanitation,  1462;  Sani- 
tary Police,  1463;   Transportation,  1464. 

Camp  Sites 

General     Considerations,     1465;     Topography,     1465;     Tentage, 

1467;   Care  of  Tents,  1468. 
Sanitation  of  Babbacks  and  Camps 

General  Considerations,  1469;  Water,  1470;  Disposal  of  Excreta, 

1473;   Disposal  of  Garbage,   1475. 

Sanitation  of  Teenches 1478 

Hygiene  in  the  Tropics 1479 

Cold  Climates 1481 

SECTION  XVI 

A  LABORATOEY  COURSE  IN  PREVENTIVE  MEDICINE 
AND  HYGIENE 

Schedule 1483 

Vaccination,  1484;  Standardization  of  Disinfectants,  1485; 
Water,  1486;  Milk,  1489;  Bacterial  Vaccine,  1492;  Vital 
Statistics,  1493;  Diphtheria  Diagnosis,  1496;  Classification  of 
Pneumococci,  1498;  Meningococcus  Isolation  and  Carrier  Detec- 
tion, 1499;  Sanitary  Survey  of  a  City  or  Town,  1501. 

Index l^Oo 


LIST  OF  ILLUSTRATIONS 


FicrKB 


PAGE 

1.  Vaccination  scars 10 

2.  The  course  of  the  eruption 13 

3.  Vaccinia:  course  of  the  eruption 14 

4.  Vaccinia:  course  of  the  eruption  (continued) 15 

5.  Course  of  vaccination  and  revaccination 19 

6.  Smallpox  mortality  per  100,000  population  in  Breslau   ...  32 

7.  Smallpox  mortality  per  100,000  population  in  Vienna     ...  33 

8.  Smallpox  mortality  per  100,000  population  in  Prussia   ...  36 

9.  Smallpox  mortality  per  100,000  population  in  Austria     ...  37 

10.  Chart   showing   relation    of    enforcement    of    muzzling   law    to 

prevalence  of  rabies  in  Great  Britain 43 

11.  Influence  of  public  water  supplies  on  the  typhoid  fever  death 

rate 119 

12.  Immediate   and   striking  effect  of  purifying   a   badly   infected 

water  supply  upon  the  typhoid  situation 121 

13.  Abrupt  reduction  in  death  rates  from  typhoid  fever  incident  to 

water  purification  in  four  American  cities 122 

14.  Hookworms,  natural  size 155 

15.  Hookworm  embryo         155 

16.  Chart  showing  the  decline  in  the  death  rate  from  tuberculosis     .  182 

17.  Curve  of  the  influenza  epidemic  in  the  naval  training  camp  at 

Pelham  Park,  New  York,  September  and  October,  1918      .  243 

18.  "West  swab  tube 256 

19.  Diagram  illustrating  the  method  of  taking  material  from  the 

nasopharynx  by  means  of  a  special  swab 256 

20.  A    South   African    blood-sucking   fly    (Pangonia),    illustrating 

long  proboscis  to  pierce  heavy  fur  of  certain  animals    .      .      .  261 

21.  Example  of  sealing  door  for  purpose  of  fumigation     ....  267 

22.  Anopheles   punctipennis 288 

23.  Stegomyia  calopus  (female) 297 

24.  Head  of  Stegomyia  calopus  (male) 298 

25.  Eggs  of  Stegomyia  calopus 299 

26.  Larva  of  Stegomyia  calopus,     Eespiratory  siphon  of  culex  to 

the  right 300 

27.  Pupa  of  Stegomyia  calopus 301 

28.  House  fly  showing  proboscis  in  the  act  of  eating  sugar    .      .      .  307 

29.  Eggs  of  house  fly  as  laid  in  a  mass 308 

'30,    Eggs  of  house  fly 308 

31.     Larvae  of  house  fly 309 

xxvii 


xxviii  LIST  OF  ILLUSTRATIONS 

FIGURE  pj^ej. 

32.  Puparium  of  house  fly .- 309 

33.  Stable  fly        310 

34.  Head  showing  proboscis 310 

35.  Wing  of  stable  fly 311 

36.  The  "little  house  fly" 312 

37.  Wing  of  house  fly,  showing  how  it  carries  dust  particles     .     .  313 

38.  The  Hodge  fly  trap  on  a  garbage  can 315 

39.  Tsetse  fly 318 

40.  The  Indian  rat  flea 323 

41.  The  common  rat  flea  of  Europe  and  North  America      .      .      .  324 

42.  The  human  flea 324 

43.  A  squirrel  flea 327 

44.  A  general  scheme  for  testing  plague  rat  infection,  city  of  Manila  352 

45.  Isolated  plague-infested  center,  Manila,  P.  1 353 

46.  The  Texas  fever  tick 357 

47.  Rocky  Mountain  spotted  fever  tick 358 

48.  Serbian  barrel 367 

49.  Delousing  plant 371 

50.  The  bedbug ,     ....  379 

51.  Diagrammatic  representation  of  complement  fixation     .      .      .  400 

52.  The  cell  with  its  various  combining  groups  or  side  chains  known 

as  receptors 549 

53.  The  toxin  molecule:  showing  the  haptophore  (combining)  group, 

and  the  toxophore   (poison)   group 549 

54.  The  first  stage  of  antitoxin  formation:   a  toxin  molecule  an- 

chored to  a  receptor 549 

65.     The  second  stage:  continued  stimulation  causes  a  reproduction 

of  receptors 550 

56.  Third  stage:  The  receptors  beginning  to  leave  the  cell    .      .      .  550 

57.  Fourth  stage:  the  receptors  have  left  the  cell  and  float  free  in 

the   blood — antitoxin 551 

58.  The  neutralization  of  a  toxin  by  antitoxin;  the  free  receptors 

in  the  blood  have  united  with  the  toxin — antitoxic  immunity  551 

59.  Showing  complement  and  immune  body 551 

60.  Showing  an  immune  body  having  two  affinities 552 

61.  Diagram  illustrating  deviation  of  complement 584 

62.  History  of  the  family  Zero 616 

63.  History    (condensed   and   incomplete)    of  three  markedly    able 

families 6l8 

64.  Wilson's  theory  of  inheritance  modified  by  Lock 623 

65.  Diagram  showing  the  course  of  color  heredity  in  the  Andalusian 

fowl,  in  which  one  color  does  not  completely  dominate  another  626 

66.  Diagram  showing  the  course  of  color  heredity  in  the  guinea-pig 

in   which   one   color    (black)    completely   dominates   another 

(white) 626 

67.  Model  to  illustrate  the  law  of  probability  or  chance    ....  632 


LIST  OF  ILLUSTllATIONS  xxix 

FIQl'RR                                                                ■  PA«r. 

68.  Normal   curve .     .     .-     .     .     .  633 

69.  Curve  made  up  of  variates 636 

70.  Family  history  showing  deaf-mutism 649 

71.  Family  history  showingr  polydactylism 652 

72.  Family  history  showing  Huntington's  chorea 656 

73.  Family  history  showing  feeble-mindedness 657 

74.  Sections  through  seeds  of  rice,  wheat  and  corn 681 

75.  Curve  showing  thermal  death  point  of  Bacillus  botulinus      .  712 

76.  Curve  showing  rate  of  destruction  of  botulinus  toxin     .      .      .  714 

77.  Unsanitary   surroundings   of  a    cowbarn 765 

78.  Conditions  under  which  it  is  difficult  to  cleanse  and  disinfect 

milk  bottles  and  milk  pails 773 

79.  A  dark,  poorly  ventilated  cow  shed,  difficult  to  keep  clean     .      .  775 

80.  Automatic  temperature  recorder  for  pasteurizers 790 

81.  Strauss  home  pasteurizer 792 

82.  Trichinella  spiralis.     Entire  life  cycle  in  each  host     ....  831 

83.  Taenia  solium,  the  pork  or  measly  tapeworm 834 

84.  Beef  tapeworm 836 

85.  Dibothriocephalus  latus,  the  fish  tapeworm 839 

86.  Portable   Haldane   apparatus   for   small   percentages   of   carbon 

dioxid 879 

87.  Petterson-Palmquist  apparatus 881 

88.  Wolpert  air  tester     . .  884 

89.  Fitz  air  tester 885 

90.  Diagram  showing  absolute  humidity  in  grains  at  different  tem- 

peratures       897 

91.  Sling  psychrometer 901 

92.  Eelative  humidity  table 902 

93.  Dew-point  apparatus 903 

94.  The  Kata-thermometer 908 

95.  Table  showing  the  density  of  smoke,   in   accordance  with   the 

Eingelmann  chart,  which  may  be  emitted  from  the  various 
classes    of   stacks    in   Boston,   Mass.,    and   duration    of   such 

emission 928 

96.  Palmer  water-spray  apparatus  for  the  collection  of  aerial  dust  .  934 

97.  Magnus  aspirator 938 

98.  The  double  aspirator 938 

99.  The  position  of  inlets  and  outlets  and  their  relation  to  the  air 

currents  in  a  room 978 

100.  "Window  ventilator 979 

101.  Diagrammatic  sketch  of  various  provisions  for  ventilation     .  980 

102.  Fairfield   system  of  window  ventilation 983 

103.  The  nitrogen  cycle 999 

104.  The  nitrogen  cycle  in  diagrammatic  vertical  section    ....  1000 

105.  Ground  water 1032 


xxx  LIST  OF  ILLUSTKATIONS 

KlfitB!!                                                                                                                                                           .  PAGE 

106.  Usual  method  of  pollution  and  even  infection  of- wells     .      .      .  1037 

107.  Proper  construction  of  a  well 1038 

108.  Popular    idea    of    how    wells    become    infected    from    surface 

pollution * 1039 

109.  Depression  of  the  ground  water  level  by  pumping  and  tendency 

to  draw  near-by  pollution  from  the  soil  or  cesspool   .      .      .  1040 

110.  In  a  limestone  formation  it  is  difficult  to  tell  anything  about 

the  source  of  water  obtained  from  a  well 1041 

111.  Algae  commonly  found  in  water 1052 

112.  Algae  commonly  found  in  water  (continued) 1053 

113.  Oil  droplets  in  a  diatom 1054 

114.  Graduated    cylindrical    funnel    and    concentrating    attachment 

used  in  the  Sedgwick-Rafter  method 1085 

115.  Diagram  illustrating  the  character  of  the  ground  water  in  rela- 

tion to   soil  pollution,   to   assist   in  the  interpretation  of  a 

sanitary    analysis *     .  1098 

116.'   Diagram  showing  location  of  samples 1106 

117.  Section  of  an  English  filter  bed 1114 

118.  The  arrangement  of  a  slow  sand  filter 1115 

119.  Diagram  illustrating   "loss  of  head" 1118 

120.  An  ozonizer 1130 

121.  An  installation  for  treating  water  with  ozone    .......  1131 

122.  Asiatic  cholera  and  the  Broad  Street  pump 1163 

123.  Asiatic  cholera  and  the  Broad  Street  well .  1164 

124.  Water  supply  of  Hamburg      . 1166 

125.  Change  in  water  supply 1169 

126.  Mean  death  rates  from  typhoid  fever,  1902-1906,  in  66  American 

cities  and  7  foreign  cities 1170 

127.  Map  of  Plymouth,  Penn.,  in  1885 1173 

128.  Map  showing  water  supply  of  Ashland,  Wisconsin     ....  1175 

129.  Inclined  screen  operated  by  water  wheel 1201 

130.  Reinsch-Wurl  screen .  1202 

131.  Cross  section  of  septic  tank 1202 

132.  Typical  section  of  an  Imhoff  tank 1203 

133.  Chemical  precipitation  plant  at  Worcester,  Mass.,  outlet     .      .  1204 

134.  Triple  contact  beds  at  Hampton,  England 1205 

135.  Cross  section  of  intermittent  sand  filter 1206 

136.  Cross  section  of  contact  bed .      .  1206 

137.  Typical  section  of  sprinkling  filter 1207 

138.  Trickling  filter  at  Birmingham,  England     . 1208 

139.  Septic    tank    and    chemical    precipitation    tanks    at    Rochdale, 

England 1209 

140.  Intermittent  sand  filtration  bed  at  Brockton,  Mass 1214 

141.  Filter  bed  with  sand  ridged  for  winter  operation  at  Brockton, 

Mass 1215 


LIST  OF   ILLUSTRATIONS  xxxi 

KUn  1!E  PAGE 

142.  Discharge  of  sewage  upon  a  filter  bed  at  Brockton,  Mass,     .      .1216 

143.  Digestion  process  of  garbage  reduction 1220 

144.  A  simple  type  of  garbage  incinerator 1222 

145.  Cobwell  process  of  garbage  reduction,  New  Bedford,  Mass.     .   1223 

146.  Births    (including    stillbirths),    persons    married,    and    deaths 

(excluding   stillbirths)    registered    per   1,000   population   per 
annum,  Michigan,  1871-1915 1238 

147.  Diphtheria — number  of  cases  notified  per  annum  for  each  death 

registered  in  Michigan,  1884-1912 1247 

148.  Smallpox — number  of  cases   notified   per   annum   in   Michigan, 

1883-1915 1248 

149.  Smallpox — number  of  cases  notified  per  annum  for  each  death 

registered,  Michigan,  1883-1915 1248 

150.  Scarlet  fever — number  of  cases   notified   per    annum   for  each 

death  registered,  Michigan,  1884-1915 1249 

151.  Measles — number  of  cases  notified  per  annum  for  each  death 

registered,  Michigan,  1890-1917 1249 

152.  Births  and  deaths  (exclusive  of  stillbirths)  per  1,000  population 

per  annum  registered  in  Mass.,  1871-1911 1266 

153.  State  statistics  of  original  registration 1276 

154.  System  of  hoods  and  ventilators  to  carry  off  the  fumes  from 

the  furnaces  in  a  foundry 1281 

155.  Red  oxid  of  lead  and  litharge  being  mixed  in  the  manufacture 

of  storage  batteries 1295 

156.  A  worker  with  lead  oxid,  showing  respirator  to  protect  himself 

against  the  poisonous  dust 1298 

157.  Workmen  exposed  to  zinc  fumes  in  brass  casting,  causing  a  con- 

dition known   as   "brass-founders'   ague" 1312 

158.  An    effective    dust-removing    system    in    the    boot-and-shoe  in- 

dustry.    Edge  trimming 1315 

159.  A  very   dusty    trade — drum    with   nails   which   combs    out   the 

small  pieces  of  broom  corn 1316 

160.  The  stone  industry    .      .      .      ^ 1820 

161.  Faulty  posture     .      .      .      .    ' 1332 

162.  The  Heusinger  desk 1333 

163.  Boston  school  desk  and  chair 1334 

164.  Device  for  determining  carbolic  coeflScients 1368 

165.  Arrangement  of  tubes  in  water-bath  and  their  contents    .      .      .  1370 

166.  Section  through  Arnold  steam  sterilizer 1381 

167.  Section  through  autoclave 1382 

168.  Bramhall-Deane  steam  sterilizer 1382 

169.  Cross  section  through  steam  disinfecting  chamber     ....  1383 

170.  Longitudinal  section  through  steam  disinfecting  chamber     .      .  1384 

171.  Kinyoun-Francis   steam   disinfecting   chamber 1385 

172.  Automatic  thermometer 1387 

173.  Plan  showing  the  method  of  installing  the  double-ended  steam 

chamber  at  a  national  quarantine  station 1388 


xxxii  LIST  OF  ILLUSTRATIONS 

FIGUBE  PAGE 

174.  Flaring-  top  tin  bucket  for  generating  formaldeliyd  by  the  per- 

manganate method 1394 

175.  The  pot  method  of  burning  sulphur 1398 

176.  Large  stack  burner  for  sulphur,  with  15  of  the  18  pans  removed 

to   show  construction 1399 

177.  Liquefied  sulphur  dioxid  in  tin  can 1400 

178.  Section  through  double  sulphur  furnace 1402 

179.  Steam  sterilizer  for  bedpans 1434 

180.  Proper  and  improper  methods  of  distributing  the  equipment     .  1452 

181.  The  normal  foot 1457 

182.  Shape  of  the  U.  S.  military  shoe 1457 

183.  Camp  of  a  regiment  of  infantry,  war  strength 1466 

184.  Ishiji  filter   (Japanese  model) 1470 

185.  Darnall  siphon  filter 1471 

186.  Construction  of  pit  latrine 1473 

187.  Straddle-pit  cover !     .      .     .  1474 

188.  Pit  crematory 1474 

189.  Pit  for  kitchen  refuse 1475 

190.  Urine  soakage  pit 1476 

191.  A  rock  pile  crematory 1477 

192.  U.  S.  Army  grease  trap 1477 

193.  Improvised  ice-box         1479 

194.  Water  bag  to  cool  water  in  hot  countries 1480 


PREVENTIVE  MEDICINE 
AND   HYGIENE 

SECTION  I 
PREVENTION  OF  THE  COMMUNICABLE  DISEASES 

CHAPTER  I 

DISEASES  HAVING   SPECIFIC   OR   SPECIAL   PROPHYLACTIC 

MEASURES 

SMALLPOX  AND  VACCINATION 

The  prevention  of  smallpox  depends  primarily  upon  vaccination,  sec- 
ondarily upon  isolation  and  disinfection.  Vaccination  was  the  first 
specific  prophylactic  measure  given  to  man ;  it  produces  an  active  im- 
munity to  smallpox.  On  account  of  its  importance  and  great  practical 
value  this  subject  will  be  considered  in  some  detail,  for  much  of  the 
antivaccination  sentiment  is  due  to  ignorance  or  misconstruction  of  the 
facts. 

Smallpox  was  once  the  most  prevalent  and  dreaded  disease  in  the 
world.  Before  the  days  of  vaccination  only  five  persons  out  of  a  hundred 
escaped  it,  and  about  a  quarter  of  those  who  took  it  died.  Many  of 
those  who  recovered  were  mutilated  or  maimed  for  life. 

Historical  Note. — The  credit  of  giving  vaccination  to  the  world  is 
due  to  Jenner,  who  proved  through  carefully  planned  experiments  that 
cowpox  protects  against  smallpox.  This  fact  had  been  familiar  to  the 
farmers  and  folk  of  England  as  a  vague  tradition  for  a  long  time.  A 
young  girl  who  sought  medical  advice  of  Jenner,  when  a  student  at 
Sudbury,  said,  "I  cannot  take  smallpox  because  I  have  had  cowpox" ;  this 
remark  made  a  strong  impression  upon  the  young  medical  student. 

Benjamin  Jesty,  a  Dorchestershire  farmer,  in  177-i  successfully  vac- 
cinated his  wife  and  two  sons.  Plett,  in  Holstein,  in  1791  also  success- 
fully vaccinated  three  children.  It  was  Jenner,  however,  who  through 
logical  and  scientific  methods  proved  that  a  person  who  has  had  the 
mild  disease,  cowpox,  enjoys  protection  against  the  serious  and  often 

1 


2  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

fatal  disease,  smallpox.  Waterhouse  and  others  soon  repeated  and  cor- 
roborated Jenner^s  experiments  and  helped  to  establish  the  soundness 
of  his  conclusions. 

Jenner  made  his  crucial  experiments  in  179G,  when  he  transferred 
the  vaccine  matter  from  the  hand  of  a  dairy  maid  (Sarah  Nelms)  to 
the  arm  of  James  Phipps,  a  boy  about  8  years  old.  Sarah  jSTelms 
scratched  her  hand  with  a  thorn  and  "was  infected  with  the  cowpox 
from  her  master's  cows,  in  May,  1796."  Jenner  transferred  the  vaccine 
virus  from  the  eruption  upon  the  hand  of  Sarah  Nelms  to  the  arm  of 
James  Phipps  on  May  14,  1796.  A  typical  take  followed.  "In  order 
to  ascertain  whether  the  boy,  after  feeling  so  slight  an  affection  of  the 
system  from  the  cowpox  virus,  was  secure  from  the  contagion  of  the 
smallpox,  he  was  inoculated  the  first  of  July  following  with  variolous 
matter,  immediately  taken  from  a  pustule.  Several  slight  punctures 
and  incisions  were  made  on  both  arms,  and  the  matter  was  carefully  in- 
serted, but  no  disease  followed.  The  same  appearances  were  observable 
on  the  arm  as  we  commonly  see  when  a  patient  has  had  variolous  mat- 
ter applied,  after  having  either  the  cowpox  or  the  smallpox.^  Several 
months  afterward  he  was  again  inoculated  with  variolous  matter,  but  no 
sensible  effect  was  produced  on  the  constitution." 

In  addition  to  such  direct  experimental  proof,  Jenner  inoculated 
smallpox  matter  into  ten  persons  who  had  at  some  previous  time  con- 
tracted cowpox. 


Date   of  Inoculation 
with  Smallpox 

1.  1778 

2.  1791 

3.  1792 


9. 
10. 


1795 


6.-) 

7.  [■  1797 

8.  J 


After  1782 
Not  stated 


Name 


Mrs.  H. 


Mary  Barge 
Sarah  Portlock 
r  Joseph  Merret 
I  William  Smith 
Elizabeth  Wynne 
Sarah  Wynne 
William  Rodway 
Simon  Nichols 
John  Phillips 


Ascertained  to 
have  had  Cowpox 

When  very  young 
31  years  previously 
27  years  previously 
25  years  previously 
1,  5,  15  years  previously 
10  months  previously 
9  months  previously 
38  years  previously 
Some  years  previously 
53  years  previously 


In  justification  of  such  human  experimentation  it  should  be  re- 
membered that  at  that  time  the  inoculation  of  smallpox  matter  into 
healthy  individuals  was  an  acknowledged  method  of  preventing  that 
disease.  Jenner  himself  was  inoculated  when  a  boy.  The  question  of 
"inoculation"  (with  smallpox)  as  contrasted  with  "vaccination"  (with 
cowpox)  will  be  discussed  presently. 

With  such  proof  as  this  Jenner  put  a  popular  belief  upon  a  scien- 
tific basis.     He  demonstrated  that  cowpox  is  a  local  and  mild  disease 

*  This  keen  observation  shows  that  Jenner  was  familiar  with  the  modified 
take,  recently  rediscovered  and  now  known  as  the  immediate  reaction. 


SMALLPOX  AND  VACCINATION  3 

in  man,  that  it  may  be  readily  transferred  from  man  to  man,  and  that 
it  protects  against  smallpox.  The  chain  of  evidence  was  complete,  but 
he  first  proved  his  thesis  to  his  own  satisfaction  before  he  gave  it  to 
the  world.  He  said  himself:  "I  placed  it  on  a  rock  where  I  knew  it 
would  be  immovable  Ijeforc  I  invited  the  public  to  take  a  look  at  it." 
Jenner  presented  the  results  of  his  observations  to  the  Royal  Society,  of 
which  he  was  a  Fellow,  but  the  paper  was  refused.  He  then  published 
it  in  1798  as  a  book,  modestly  entitled,  "An  Inquiry  Into  the  Causes  and 
Eifects  of  the  Yariolae  Vaccinae,  a  Disease  Discovered  in  Some  of  the 
Western  Counties  of  England,  Particularly  Gloucestershire,  and  Known 
by  the  Name  of  the  Cowpox."  Every  student  of  preventive  medicine 
should  read  this  brief  "inquiry''  in  the  original.  It  may  be  taken  as  a 
model  of  careful  observation  and  logical  presentation,  showing  great 
self-restraint  and  moderation  of  an  observant,  imaginative,  and  judicial 
mind. 

Dr.  Benjamin  Waterhouse,  the  first  professor  of  Theory  and  Prac- 
tice of  Physic  in  the  Harvard  Medical  School,  early  became  convinced 
of  the  value  of  Jenner's  demonstration  and  obtained  some  vaccine  virus 
on  threads  from  abroad.  On  July  8,  1800,  he  vaccinated  his  son,  Daniel 
Oliver  Waterhouse,  then  five  years  old.  This  was  the  first  person  vac- 
cinated in  America,  so  far  as  existing  records  show.  After  successful 
vaccination  with  cowpox  his  two  sons  and  other  members  of  his  house- 
hold were  inoculated  with  smallpox  at  the  Smallpox  Hospital  by  Dr. 
Zabdiel  Boylston,  with  negative  results. 

In  Boston  on  August  16,  1802,  nineteen  boys  were  vaccinated  with 
the  cowpox.  On  November  9th  twelve  of  them  were  inoculated  with 
smallpox;  nothing  followed.  A  control  experiment  was  made  by  inocu- 
lating two  unvaccinated  boys  with  the  same  smallpox  virus;  both  took 
the  disease.  The  nineteen  children  of  August  16th  were  again  unsuc- 
cessfully inoculated  with  fresh  virus  from  these  two  boys.  This  is  one 
of  the  most  crucial  experiments  in  the  history  of  vaccination,  and  fully 
justified  the  conclusion  of  the  Board  of  Health — "cowpox  is  a  complete 
security  against  the  smallpox." 

Thomas  Jefferson  helped  materially  to  spread  the  new  doctrine  in 
this  country,  and,  in  1806,  in  writing  to  Jenner,  said :  "Future  nations 
will  know  by  history  only  that  the  loathsome  smallpox  has  existed  and 
by  you  has  been  extirpated.'"  This  prophecy  has  by  no  means  been  ful- 
filled— though  eminently  possible. 

YACCINATION 

Vaccination  may  be  defined  as  the  transference  of  the  virus  from 
the  skin  eruption  of  an  animal  having  vaccinia  or  cowpox  into  the  skin 
of  another  animal.    Vaccination,  then,  consists  in  introducing  the  active 


4  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

principle  of  cowpox  into  the  skin  of  a  susceptible  animal.  For  over 
one  hundred  years  vaccination  (from  vacca — a  cow)  was  a  specific  term 
limited  to  the  introduction  of  the  virus  of  cowpox  into  the  skin,  in  order 
to  induce  vaccinia  and  prevent  variola.  In  recent  years,  however,  the 
term  has  been  used  in  a  generic  sense  to  include  the  introduction  of 
many  different  substances  in  many  different  ways  and  for  many  different 
purposes.  Thus  we  speak  of  attenuated  or  killed  bacterial  cultures  as 
bacterial  vaccines;  and  the  subcutaneous  inoculation  of  organic  sub- 
stances of  diverse  origin  and  nature  is  often  spoken  of  as  vaccination. 
We  hear  of  typhoid  vaccines,  anthrax  vaccines,  staphylococcus  vaccines, 
and  we  read  in  the  literature  of  animals  "vaccinated"  with  extracts  of 
cancer  and  other  organic  substances.  For  distinction  between  a  vaccine 
and  a  virus,  see  page  534. 

VACCINE  VIEUS 

^,  Vaccine  virus  is  the  living  specific  principle  in  the  matter  obtained 
from  the  skin  eruption  of  animals  having  a  disease  known  as  "vaccinia" 
or  "cowpox."  A^accine  virus  is  obtained  from  calves,  but  may  also  be 
obtained  from  older  cattle,  from  man,  rabbits,  buffalo,  camels,  and  other 
mammals. 

Cowpox,  or  vaccinia,  is  an  acute  specific  disease  to  which  many 
animals  are  susceptible,  namely,  man,  cattle,  camels,  rabbits,  monkeys, 
guinea-pigs,  rats,  etc.  The  disease  runs  practically  the  same  clinical 
course  in  all  susceptible  species.  The  eruption  is  always  local  and 
confined  to  the  site  of  the  vaccinated  area ;  the  constitutional  symptoms 
are  always  benign  and  usually  slight.  Vaccinia  or  cowpox  is  a  benign 
disease;  when  uncomplicated,  it  has  never  been  known  to  cause  death  or 
leave  any  unpleasant  sequelae. 

After  an  incubation  period  of  from  three  to  four  days  the  local 
eruption  begins  as  a  papule  which  soon  develops  into  a  vesicle,  and 
later  into  an  umbilicated  pustule.  Surrounding  the  vesicle  is  a  red- 
dened, inflamed,  and  tender  areola.  The  neighboring  lymph  glands 
are  swollen  and  tender,  and  there  may  be  slight  fever  lasting  several 
days.  The  pustule  dries,  leaving  a  crust  or  scab,  which  comes  away,-  dis- 
closing a  typical  foveated  or  pitted  scar. 

Human  and  Bovine  Vaccine  Virus. — Vaccine  virus  is  usually  ob- 
tained from  (1)  bovine  or  (2)  human  sources. 

Human  virus  is  now  seldom  used,  for  the  reason  that  the  supply 
would  not  be  sufficient.  Upon  the  appearance  of  a  smallpox  outbreak 
it  is  sometimes  necessary  to  have  enough  virus  to  vaccinate  one  hundred 
thousand  or  more  people.  Such  large  quantities  evidently  could  not  be 
obtained  from  man  at  any  desired  time.  Another  objection  to  the  use 
of  human  virus  is  the  possibility  of  transmitting  syphilis,  and  perhaps 


SMALLPOX  AND  VACCTNATIOX  5 

other  dit^oasos  peculiar  to  iiiaii.  It  i^  not  always  jjractical  to  select  donors 
so  as  to  avoid  such  transmission. 

When  human  seed  is  used  the  virus  may  be  transferred  directly  from 
arm  to  arm;  or  the  virus  may  be  preserved  dry  in  the  scab;  or  the  con- 
tents of  the  vesicle  may  be  kept  in  either  a  dried  or  moist  state,  as  de- 
scribed below  for  bovine  virus.  Arm-to-arm  vaccination  is  still  practiced 
in  several  parts  of  the  world,  particularly  in  Mexico,  where  it  is  claimed 
that  it  has  the  advantage  of  producing  a  better  take;  that  the  results  are 
surer  in  that  there  are  fewer  unsuccessful  vaccinations;  and,  finally,  it 
is  stated  that  the  human  virus  affords  a  better  immunity,  but  as  to  this 
there  is  no  proof  and  some  doubt. 

Bovine  virus  has  been  used  more  or  less  since  the  time  of  Jenner, 
but  especially  since  1866  when  the  Beaugency  strain  was  discovered,  and 
more  since  1891  when  Copeman  showed  how  to  purify  it  with  glycerin. 
It  has  the  great  advantage  of  being  readily  obtained  in  any  amount  and 
when  desired.  It  may  be  purified,  and  it  further  totally  eliminates  the 
danger  of  conveying  syphilis  and  other  diseases  peculiar  to  man. 

Forms  of  Vaccine  Vims. — Vaccine  virus  may  be  used  in  one  of 
three  forms:  (1)  fresh,  (2)  dry,  (3)  glycerinated. 

The  fresh  virus  may  be  taken  from  the  eruption  of  the  calf  or  man 
and  transferred  directly.  Thus  the  Institut  Tacc-inale  at  Paris  still 
prefers  to  use  the  fresh  virus.  The  vesicle  is  squeezed  at  its  base  be- 
tween the  blades  of  forceps,  and  some  of  the  content  is  transferred 
from  the  calf  directly  to  the  skin  of  the  arm  by  means  of  a  thumb  lancet 
or  any  similar  instrument. 

The  vaccinal  matter  may  be  dried,  and  the  virus  remains  potent  in 
this  state  a  very  long  time,  especially  if  kept  cold  and  protected  from 
light.  The  virus  may  be  dried  upon  a  splinter  of  ivory,  bone,  or  other 
substance.  Formerly  physicians  preserved  the  dried  crust  from  a 
typical  take.  When  needed,  small  portions  of  this  crust  were  ground, 
moistened,  and  inserted  into  the  skin. 

Glycerinated  virus  consists  of  vaccine  pulp  treated  with  50  per  cent, 
glycerin.     This  purifies  it  and  hence  is  preferable. 

Vaccine  Pulp  and  Vaccine  Lymph. — A  distinction  is  drawn  between 
the  pulp  and  the  hinph.  The  pulp  consists  of  the  entire  vesicle  with 
its  contents,  which  is  scraped  from  the  skin,  and  is  composed  of  epi- 
thelium, leukocytes,  bacteria,  products  of  inflammatory  reaction,  the 
fluid  content  of  the  vesicle,  debris,  etc.  The  lymph  is  the  serous  fluid 
contained  in  the  vesicle  or  which  often  exudes  from  the  broken  vesicle. 
When  the  eruption  is  produced  on  the  skin  of  a  calf  in  a  large  con- 
fluent area,  the  surface  of  the  eruption  is  scraped  away  and  the  exuding 
"lymph"  is  placed  upon  points  by  dipping  or  brushing. 

!Most  of  the  active  principle  of  vaccine  virus  is  contained  in  the  epi- 
thelial cells,  and  this  portion  is  largely  lost  when  only  the  lymph  is 


6  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

used.  The  pulp,  which  includes  the  lymph,  therefore  contains  the 
virus  in  greater  concentration,  and  is  almost  exclusively  used  in  this 
country  at  the  present  time. 

Dry  Points  versus  Glycerinated  Vaccine  Vims. — The  old-fashioned 
dry  points  were  prepared  by  applying  the  vaccine  lymph  to  splinters 
of  ivory.  Bone  or  glass  were  later  substituted  for  ivory.  Bone  is  un- 
desirable because  it  is  difficult  to  sterilize  and  may  contain  tetanus 
spores.  The  only  advantage  of  the  dry  point  is  its  convenience  in 
vaccinating.  One  disadvantage  is  that  the  virus  dried  upon  such 
points  cannot  easily  be  purified  as  is  the  case  with  glycerinated  pulp. 
Further,  the  points  are  used  as  scarifiers  and  the  method  of  scarification 
favors  irritation  and  infection  of  the  wound.  Dry  points  practically 
always  contain  more  bacteria  than  the  glycerinated  virus.  For  these 
reasons  points  are  no  longer  permitted  in  interstate  traffic  in  accordance 
with  the  federal  regulations. 

The  best  container  for  single  doses  of  vaccine  virus  is  a  capillary 
tube.  These  are  easily  sterilized,  filled  and  hermetically  sealed.  They 
should  be  wiped  with  alcohol  and  broken  with  sterile  gauze,  and  the 
contents  can  then  safely  be  emptied  by  means  of  a  small  rubber  bulb. 
"When  many  vaccinations  are  to  be  done,  it  is  preferable  to  have  the 
virus  in  bulk. 

The  Process  of  Ripening  or  Aging. — When  the  vaccine  virus  is  fresh 
it  is  said  to  be  "green."  Glycerin  is  added  to  the  green  pulp,  and  after  it 
has  acted  a  certain  period  of  time  the  virus  is  said  to  be  "aged"  or  "ripe." 
The  use  of  glycerin  for  this  purpose  was  introduced  by  ]\Ioncton  Cope- 
man  ^  in  1891  for  the  purpose  of  preserving  ^  and  purifying  the  virus. 
The  glycerin  acts  as  a  differential  germicide,  that  is,  it  is  comparatively 
harmless  to  the  active  principle  in  the  vaccine  virus,  but  destroys  the 
frail  non-spore-bearing  bacteria.  In  time  the  virus  itself  succumbs. 
Vaccine  virus  must,  therefore,  not  be  used  while  green  nor  when  too  old. 
Manufacturers  date  their  products  as  "not  reliable  after"  2  months  in 
the  summer  time,  and  3  months  during  the  cold  season. 

Fifty  per. cent,  glycerin  of  the  best  quality  is  used.  I  have  shown 
that  no  growth  of  bacteria,  yeasts,  or  molds  takes  place  in  60  per  cent.* 
glycerin.  Two  to  four  parts  of  50  per  cent,  glycerin  are  added  to  1  part 
of  the  pulp  by  weight.  The  mixture  is  then  thoroughly  ground  with  a 
mortar  and  pestle  by  hand,  or  between  glass  rollers  in  a  special  mill 
driven  by  machinery.  The  pulp  should  be  thoroughly  broken  up  and  a 
uniform  suspension  obtained.  The  amount  of  glycerin  added  depends 
upon  the  consistency  and  character  of  the  pulp.     The  only  objection 

'Transactions  of  the  International  Congress  of  Hygiene,  1891. 
^Glycerin  also  serves  as  a  preservative  for  other " filterable  viruses,  as  foot- 
and-mouth  disease,  infantile  paralvsis,  rabies,  etc. 

^Hyg.  Lab.  Bull.  No.  16,  U.  S.'P.  H.  &  M.  H.  S.,  1903. 


SMALLPOX  AND  VACCINATION  7 

to  adding  more  glycerin  Avoukl  bo  the  greater  dilution  of  the  virus,  and, 
therefore,  a  larger  proportion  of  negative  takes.  A  higher  percentage 
than  50  per  cent,  of  glycerin  soon  renders  the  virus  inert.  The  time 
required  for  the  virns  to  ripen  depends  upon  the  temperature.  Most 
of  the  non-spore-bearing  bacteria  perish  in  30  days  at  15°  to  20°  C. 
Approximately  the  same  effect  may  be  obtained  at  37°  C.  in  a  few  hours. 
At  low  temperatures  the  glycerin  has  practically  no  bactericidal  effect. 
The  process  must  always  be  controlled  bacteriologically. 

Vaccine  virus  should  always  be  kept  cold  until  used.  The  warmth 
of  the  doctor's  pocket  may  be  enough  to  destroy  its  potency  in  a  few 
hours.  The  heat  of  the  railroad  car  or  post  oflficc  may  soon  render  it 
impotent.  This  explains  the  difficulty  sometimes  encountered  in  obtain- 
ing potent  virus  during  the  summer  months. 

Substances  other  than  glycerin  are  used  for  the  purpose  of  purifying 
vaccine  virus.  Carbolic  acid  (0.5  to  1.0  per  cent.),  in  addition  to 
glycerin,  is  used  with  success  in  Japan,  and  to  a  large  extent  in  this  coun- 
try. Potassium  cyanid,  brilliant  green,  chloroform,  chlorobutanol,  etc., 
have  been  tried,  with  less  success  in  practice. 

Bacteria  in  Vaccine  Virus. — Vaccine  virus  obtained  from  the  skin 
always  contains  bacteria.  However,  these  bacteria  are,  for  the  most  part, 
harmless  to  man.  They  are  commonly  those  that  are  found  on  and  in 
the  skin  of  the  calf.  The  non-spore-bearing  varieties  are  largely  elimi- 
nated by  the  process  of  ripening.  There  are  fewer  bacteria  in  the  typical 
unbroken  vesicle  than  in  the  pustule  or  in  a  broken,  crusty,  inflamed 
eruption.  Green  virus  may  contain  from  a  few  thousand  to  over  a  million 
bacteria  per  cubic  centimeter.  The  ripened,  glycerinated  virus  con- 
tains much  fewer,  and  these  mostly  harmless  saprophytes.  The  number 
of  such  bacteria  in  the  ripened  virus  may  be  taken  as  an  indication  of 
the  care  and  cleanliness  with  which  the  virus  has  been  prepared.  In 
the  LTnited  States  vaccine  virus  is  required  to  have  fewer  than  50 
bacteria  per  dose. 

Noguchi  ^  by  painstaking  methods  obtained  a  bacteria-free  vaccine 
virus,  which  may  be  propagated  in  the  testicles  of  bulls  or  rabbits. 
Human  beings  react  to'  the  testicular  strain  in  an  entirely  typical  manner, 
but  this  method  has  not  been  found  practical  for  propagation  on  a  large 
scale. 

Seed  Vaccine. — The  seed  virus  may  be  obtained  (1)  from  cowpox, 
(2)  from  smallpox,  (3)  by  retro  vaccination. 

"Spontaneous"  or  casual  cowpox  occasionally  occurs;  that  is  to  say, 
the  disease  appears  to  arise  spontaneously  because  its  origin  cannot  be 
traced.  Casual  cowpox  comes  either  from  another  case  of  cowpox  or 
from  a  case  of  smallpox.  Cattle  are  not  subject  to  smallpox,  but,  when 
smallpox  virus  is  introduced  into  the  skin  of  a  calf,  it  produces  cowpox. 

Wour.  of  Exp.  Med.,  June  1,  19L5,  XXI,  6,  p.  339. 


8  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

When  smallpox  is  thus  converted  into  cowpox,  it  remains  fixed  as  such, 
and  never  reverts  to  smallpox.*'  Twenty-nine  separate  records  of  success- 
ful modification  of  smallpox  virus  into  cowpox  are  found  in  the  litera- 
ture; also  a  number  of  negative  attempts.  Some  of  the  strains  obtained 
in  this  way  were  used  to  vaccinate  children  with  typical  takes  and 
adequate  protection, 

Retrovaccination  consists  in  carrying  the  vaccine  virus  back  from 
child  to  calf;  better  still,  the  virus  may  be  passed  from  man  through 
rabbit,  monkey^  or  other  susceptible  animal,  and  then  again  to  the  calf. 
Changing  the  species  helps  to  maintain  the  activity  of  the  vaccine 
virus  for  an  indefinite  time;  furthermore,  the  change  leaves  behind  cer- 
tain associated  bacteria  which  may  gather  increased  virulence  by  suc- 
cessive passage  from  animal  to  animal  of  the  same  species. 

Propagation. — In  the  propagation  of  bovine  virus  young  calves  are 
preferred,  because  they  are  more  manageable,  the  skin  is  more  tender, 
and  the  eruption  is  therefore  more  abundant  and  typical.  With  young 
animals  a  milk  diet  may  be  used,  which  simplifies  the  problem  of  dust 
contamination  from  dry  feed.  If  hay  or  fodder  is  used,  it  should  first 
be  autoclaved.  Either  heifers  or  bull  calves  are  suitable,  although  the 
former  are  preferred. 

The  animals  are  held  in  quarantine  for  seven  days,  under  observa- 
tion, to  determine  the  absence  of  infections  such  as  tuberculosis,  glan- 
ders, foot-and-mouth  disease,  tetanus,  fever,  diarrhea  or  skin  eruptions 
of  any  kind. 

Before  vaccinating  the  calf  it  is  carefully  cleaned,  and  the  site 
of  the  inoculation  is  shaved  and  prepared  surgically,^  but  without  the 
use  of  strong  germicidal  solutions,  for  the  reason  that  they  are  apt  to 
destroy  the  action  of  the  vaccine  virus.  Cleanliness  and  asepsis  are  the 
watchwords.  The  area  selected  is  usually  the  abdominal  wall  between  the 
tip  of  the  sternum  and  the  groin,  sometimes  including  the  inner  side  of 
the  thigh.  The  usual  method  is  to  make  long,  superficial  incisions  in  the 
skin  about  one  centimeter  apart,  and  the  seed  virus  is  gently  rubbed 
into  these  incisions.  The  calves  must  then  be  kept  rigidly  isolated  in  a 
special  room,  moderately  lighted,  free  from  dust,  and  screened  to  keep 
out  insects.  The  temperature  of  the  animal  is  taken  several  times 
daily  and  the  eruption  at  each  stage  of  the  disease  is  closely  watched 
and  recorded. 

The  virus  is  usually  taken  from  the  animal  about  the  fifth  day.  It 
is  an  advantage  to  take  the  virus  early,  in  order  to  avoid  contaminating 
infections  which  may  occur  when  the  vesicles  maturate.     Vaccine  virus 

*  It  is  liighly  significant  that  casual  cowpox  was  formerly  much  more  com- 
mon when  smallpox  was  much  more  prevalent. 

''  I  used  3  scrubbings  with  soap  and  3  tloodings  with  alcohol,  at  the  Antitoxin 
and  Vaccine  Laboratory,  Mass.  State  Dept.  of  Health. 


SMALLPOX  AND  VACCINATION  9 

taken  after  the  eighth  day  is  unreliable.  Jeuner's  golden  rule  was  to 
take  the  virus  before  the  areola  appeared.  Virus  taken  after  the  eighth 
day  is  apt  to  produce  unduly  inflamed  or  abortive  vesicles,  called  spurious 
takes  by  the  early  vaccinators.  Only  typical  and  entirely  characteristic 
vesicles  should  be  removed.  Before  the  virus  is  removed,  the  animal  is 
chloroformed  to  avoid  pain,  and  an  autopsy  is  done  as  soon  after  the  virus 
is  removed  as  practicable.  If  the  autopsy  shows  any  lesions  indicating 
infections  other  than  vaccinia,  the  virus  is  discarded. 

It  is  not  wise  in  propagating  vaccine  virus  to  vaccinate  too  large 
an  area.  This  favors  infections  by  lowering  resistance ;  furthermore,  less 
t^-pical  eruptions  are  obtained  than  when  the  area  vaccinated  is  moderate 
in  extent.  A  yield  of  from  30  to  50  grams  of  pulp  from  one  calf  should 
satisfy  the  propagator. 

Before  the  virus  is  taken  the  animal  is  placed  upon  a  special  table, 
the  site  of  the  vaccination  exposed  and  given  a  very  thorough  washing 
and  prolonged  scrubbing  with  soap,  and  an  abundant  flushing  with 
sterile  water.  The  pulp  is  obtained  by  scraping  the  vesicles  with  a 
sharp  spoon  curette. 

Glycerin  (50  per  cent.)  in  the  proportion  1  to  4  is  added  at  once  to 
the  pulp,  and  this  is  ground  to  a  state  of  fine  and  uniform  subdivision  in 
a  Csokar  lymph  mill,  or  simply  by  hand  with  a  mortar  and  pestle.  This 
glycerinated  pulp  is  then  allowed  to  age,  and  when  purified  by  the  action 
of  the  glycerin  it  is  hermetically  sealed  in  capillary  tubes,  or  placed  in 
small  vials  for  the  market. 


METHODS  OF  VACCINATION" 

Vaccination  consists  in  transferring  the  virus  of  cowpox  from  one 
animal  to  the  skin  of  another  animal.  The  operation  of  vaccination  con- 
sists of  introducing  vaccine  virus  into  the  skin.  Under  no  circumstances 
must  the  vaccine  virus  be  placed  under  the  skin  or  subcutaneously.  The 
operation  may  be  compared  to  the  transfer  of  a  culture  in  a  bacteriologic 
laboratory.  Precisely  similar  precautions  to  prevent  contamination  must 
be  used  in  both  cases.  Vaccination  must  be  regarded  as  a  surgical  opera- 
tion. No  person  unfamiliar  with  surgical  cleanliness  should  be  per- 
mitted to  perform  this  "little"  operation. 

The  vaccine  virus  may  be  introduced  in  one  of  three  ways:  (1)  by 
puncture,  (2)  by  incision,  or  (3)  by  scarification. 

Jenner  used  punctures  or  short  incisions.  Later  blisters  were  raised 
upon  the  skin  and  the  virus  placed  upon  the  abraded  surface.  The 
incisions  w^ere  then  increased  in  number,  and  finally  cross  scratchings 
or  scarifications  were  made. 


10 


DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 


Puncture.— The  simplest  method  is  shallow  ohliqiie  pricking  of  the 
skin  with  a  needle  moistened  with  the  vaccine  virus;  this  gives  little 
chance  of  contamination  and  the  eruption  is  typical.  The  disadvantage 
is  that  the  virus  now  used  is  diluted  with  glycerin,  and  therefore  some- 
what attenuated,  so  that  a  few  punctures  may  not  give  an  adequate 
take. 

Incision  or  Scratch. — The  method  advised  and  recommended  is  that 
of  incision.  Incision  is  the  only  method  of  vaccination  permitted  by 
the  laws  of  Germany,  and  recommended  by  the  Local  Government  Board 
of  England.  Incision,  if  not  too  deep,  consists  really  of  a  series  of 
punctures,  and  serves  the  same  purpose.  Incisions  may  be  made  with 
the  point  of  a  scalpel.  I  prefer  to  use  a  sterile  needle.  The  incision 
or  scratch  should  not  be  deep  enough  to  draw  blood,  but  a  few  drops  do 

no  harm.  It  is  rather 
difficult  to  control  the 
depth  of  the  incision 
with  a  scalpel,  espe- 
cially if  it  is  sharp. 
Scratching  with  a 
needle  is  much  more 
easily  controlled.  Two. 
incisions  should  be 
made  about  one  inch 
long  and  about  an  inch 
apart.  The  vaccine 
virus  is  first  placed 
upon  the  skin  in  two 
small  droplets  about  an  inch  apart.  The  point  of  the  needle  is  now 
moistened  in  the  droplet  and  as  the  scratch  is  made  the  needle  carries  the 
virus  along  with  it  into  the  little  wound.  With  the  flat  of  the  needle 
the  virus  should  be  gently  rubbed  (not  ground)  into  the  scratch.  It  is 
important  not  to  cause  any  unnecessary  irritation  so  as  to  avoid  attract- 
ing infections. 

Scarification. — Scarification  or  cross-scratching  should  be  prohibited 
by  law.  It  is  forbidden  in  Germany.  The  objection  to  scarification  is  that 
this  method  produces  a  relatively  large  abraded  surface  which  is  soon 
covered  by  a  dry,  hard  crust  of  serum  and  blood,  through  which  the  erup- 
tion cannot  pierce.  The  vesicles  form  a  ring  around  the  scarified  area, 
leaving  a  central  irritated  wound  inviting  infection.  Most  of  the  cases 
of  tetanus  complicating  vaccination  occur  in  cases  in  which  scarification 
was  used.  In  this  method  favorable  anaerobic  conditions  are  produced 
under  the  crust  or  scab  which  forms  over  the  abraded  surface.  The 
scarified  area  also  leaves  an  unnecessary  and  unsightly  scar  (Fig,  1), 


Fig.    1. 


-Vaccknatiu.n    ,Slai;.s   Produced  by   ^Ietho;) 
OF  Scarification. 
Note  unnecessarv  central  scar. 


SMALLPOX  AND  VACCTNATIOX  11 

The  Point  of  Election. — The  outer  surface  of  ihe  left  arm  at  about 
the  insertion  of  the  deltoid  is  the  most  convenient  for  tlie  operator  and 
the  patient.  This  is  the  original  site  selected  by  Jcnner,  and  is  less 
liable  to  severe  glandular  complications  than  other  points.  The  skin 
here  is  easily  made  taut  during  the  operation  by  grasping  the  under  side 
of  the  arm.     Inspection  of  the  course  of  the  eruption  is  also  facilitated. 

Flachs  recommends  the  side  of  the  chest  at  about  the  level  of  the 
sixth  rib.  in  the  axilla.  Here  the  scar  is  not  visible;  but  tiiis  site  is  more 
objectionable  than  that  recommended  by  I.  IL  Goldberger,*  who  uses 
the  inner  and  back  side  of  the  arm. 

The  leg  is  sometimes  selected  to  avoid  disfigurement.  The  vaccina- 
tion scar  should  not  be  regarded  as  a  deformity.  To  the  sanitarian  a 
typical  vaccine  scar  is  a  sanitary  dimple.  The  leg  is  more  exposed 
than  the  arm  to  traumatism^,  and,  therefore,  to  complications.  Dock 
refuses  to  vaccinate  on  the  leg  unless  the  patient  will  stay  in  bed  until 
the  vesicle  heals.  With  babies  in  diapers  and  with  young  children  it  is 
exceedingly  difficult  to  keep  these  parts  clean.  If  the  leg  is  selected,  the 
vaccination  should  be  done  on  the  calf  below  the  head  of  the  fibula, 
and  not  on  the  outer  surface  of  the  thigh. 

Number  of  Incisions. — This  has  an  important  bearing  upon  the 
probability  of  the  take,  as  well  as  the  protection.  It  is  not  wise  to  de- 
pend upon  one.  There  is  a  definite  relation  between  the  number  of 
vesicles  and  the  degree  and  length  of  the  immunity.  See  page  IT.  The 
German  regulations  of  1899  require  at  least  four  incisions,  each  one  cen- 
timeter long  and  two  centimeters  apart.  The  Local  Government  Board 
of  England  directs  that  four  vesicles  should  be  produced,  and  that  the 
total  area  of  the  vesicle  formation  shall  not  be  less  than  one-half  a  square 
inch.  ]\Iy  own  practice  follows  that  of  Dock,  who  makes  not  less  than 
two  incisions  about  an  inch  long  and  an  inch  apart;  but  in  case  of  ex- 
posure to  smallpox  three  or  four  such  incisions  are  advisable. 

The  Operation. — The  skin  at  the  site  of  the  operation  must  be  sur- 
gically clean,  but  need  not  necessarily  be  treated  with  germicides.  If 
such  are  used,  they  must  be  carefully  washed  away  in  order  not  to 
destroy  the  activity  of  the  virus.  A  thorough  preliminary  scrubbing 
with  soap  and  water  is  necessary  for  a  dirty  skin.  "Washing  with  warm 
water  followed  by  alcohol  is  usually  enough.  The  alcohol  should  be  per- 
mitted to  evaporate  before  the  vaccine  is  applied  and  the  incision  is  made. 
In  general,  the  less  the  skin  is  irritated  the  less  the  danger  of  complica- 
tions. Xeedles  are  particularly  handy,  as  they  may  be  flamed  just  before 
the  operation,  and  are  convenient  in  saving  time  when  many  people  are 
to  be  vaccinated.  The  vaccine  virus  is  gently  rubbed  into  the  incision, 
not  ground  in,  and  then  allowed  to  dry.  No  dressing  is  necessary  as 
long  as  the  vesicle  remains  unbroken,  but  several  layers  of  dry  sterile 

*y.  r.  Med.  Jour.,  Dec.  25.  1020,  112,  No.  6..  p.  10.35. 


13  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

gauze  held  in  place  by  adhesive  plaster  do  no  special  harm,  provided 
they  are  removed  before  pustulation.  Pads,  plasters,  and  shields  of 
any  sort  are  unwise,  because  by  retaining  heat  and  moisture  they  cause 
softening  and  breaking  down;  in  other  words,  they  act  like  a  poultice. 

The  best  dressing,  is  the  unbroken  skin,  and  then  the  crust  (scab) 
which  naturally  forms.  This  permits  frequent  inspection  and  avoids 
undue  heat  and  softening.  If  the  pustule  breaks  or  the  crust  comes 
off,  or  the  take  shows  indications  of  secondary  infection,  frequent  dress- 
ing with  an  active  germicide  is  indicated.  It  is  not  good  surgical  technic 
to  bind  up  any  actively  suppurating  area  for  more  than  24  hours. 

Painting  the  vesicle  with  tincture  of  iodin,  cauterizing  the  base 
with  silver  nitrate,  or  the  application  of  carbolic  acid,  picric  acid,  and 
other  active  germicides  does  not  diminish  redness  or  shorten  the  course 
of  the  vaccinal  eruption. 

Bathing  need  not  be  omitted,  nor  any  of  the  ordinary  occupations, 
but  ca-re  should  be  taken  not  to  soften  the  crust  by  water  or  sweat. 
Unnecessary  use  of  the  arm  must  be  guarded  against,  as  this  increases 
the  congestion,  inflammation,  and  the  chances  of  infection. 

INDICES  OF  A  SUCCESSFUL  VACCINATION 

The  take  must  be  typical  and  the  clinical  course  characteristic,  other- 
wise we  have  no  assurance  that  the  individual  is  protected  against  small- 
pox. The  best  indices  of  a  successful  take  are:  (1)  the  course  of  the 
eruption,  (2)  the  general  symptoms,  and  (3)  the  scar. 

The  importance  of  knowing  the  skin  lesions  of  vaccinia  were  in- 
sisted upon  by  Jenner.  Every  vesicle,  scab,  ulcer,  or  irritated  wound  is 
not  vaccinia.  Xo  confidence  should  be  placed  in  doubtful  or  atypical 
takes.  The  characteristic  features  of  vaccination  are  singularly  alike. 
The  clinical  course  of  a  primary  vaccination  is  as  follows : 

Course  of  the  Eruption. — The  primary  wound  soon  heals.  Appar- 
ently nothing  occurs  for  3  to  4  days,  which  is  the  period  of  incubation. 
Then  one  or  more  small  papules  appear  upon  the  skin  where  the  vac- 
cine virus  was  introduced.  The  papule  is  small,  round,  flat,  bright 
red,  hard,  but  superficial.  About  the  fifth  day  the  summit  of  the  papule 
becomes  vesicular.  The  vesicle  is  at  first  clear  and  pearl-like.  Umbilica- 
tion  soon  develops  as  the  vesicle  enlarges.  A  deep,  red,  and  swollen 
areola  surrounds  the  vesicle  and  grows  wider  as  the  lesion  advances. 
This  gives  the  picture  of  the  "pearl  upon  the  rose  leaf"  which  consti- 
tutes the  true  Jennerian  vesicle.  By  the  seventh  day  the  vesicle  is  full 
size,  round  or  oval,  flat  on  top,  umbilicated,  and  contents  clear.  It  is 
multilocular ;  if  pricked  with  a  pin  or  accidentally  opened  only  that 
portion  of  the  lymph  contained  in  the  compartment  opened  will  exude. 
By  the  eighth  day  it  turns  yellowish,  the  middle  is  fuller,  following 
which  the  so-called  second  umbilication  develops.    Meanwhile  the  areola 


SMALLPOX  AND  VACCINATION 


13 


deepens,  widens,  and  may  be  swollen.  The  skin  feels  hot,  is  painful,  and 
the  axillary  glands  become  enlarged  and  tender.  About  the  tenth  day 
the  areola  begins  to  fade  and  the  swelling  subsides.  By  tlie  eleventh  or 
twelfth  day  the  pustule  rapidly  dries,  leaving  a  brown,  wrinkled  scab, 
which  finally  drops  off  about  the  twentieth  day.  It  should  never  be 
removed,  as  it  forms  the  best  dressing. 


PUNCTURE 


PUSTULE  9TH  DAY 


PAPULE -4"^"  DAY 


DESICCATION  12TH0AY 


VESICLE  5'^**DAy 


CRUST    IBT"OAY 


UMBILICATION7TMDAY  FOVEATED  SCAR 

Fig.  2. — The  Cotjrse  of  the  Eruption   (Diagrammatic). 

The  scar  is  at  first  red,  finally  turns  white,  with  the  pits  or  fovea- 
•tions  so  characteristic  of  true  cowpox. 

General  Symptoms. —  These  vary.  Malaise,  loss  of  appetite,  some- 
times nausea  and  vomiting,  headache,  pain  in  the  muscles  of  the  back, 
and  other  indications  of  a  mild  febrile  reaction  appear  about  the  seventh 
day,  and  soon  cease.  The  temperature  may  go  to  38°  or  38.5°  C.  as  the 
vesicle  ripens.  The  febrile  reaction  bears  no  special  relation  to  the  size 
and  number  of  the  vesicles  or  to  the  areola.  The  regional  lymph  nodes 
become  enlarged  and  tender  about  the  time  the  pustule  forms.  The  nitro- 
gen elimination  increases  about  the  tenth  day  for  a  short  time.  The 
blood  changes  resemble  those  of  smallpox,  an  early  leukopenia  and  sec- 
ondary leukocytosis. 


14 


DISEASES  HAVING  SPECIAL  rEOPHYLAXIS 


Secondary  vaccinations  often  run  an  accelerated^  milder,  or  modified 
course  with  shortened  periods  of  incubation  (see  revaccination). 

Vaccination  certificates  should  be  based  upon  observation  of  the 
course  of  the  take.  Modified  reactions  in  revaccinations  are  to  be  inter- 
preted as  successful  takes,  but  their  nature  should  be  recorded — as  im- 
mediate, or  accelerated  reactions,  page  18. 


THE  IMIklUNITY 


The  immunity  appears  about  the  eighth   day  of  the  vaccination. 
Layet  puts  the  point  of  safety  at  the  ninth  day,  Burckhard  at  the  elev- 


Fi(,.   3. — VacciIv'IA.     Course  of  the  Eruption. 

enth.  These  data  are  based  upon  the  early  work  with  variolation,  when 
persons  were  inoculated  witli  smallpox  at  various  periods  following  vac- 
cination. Sacco  got  only  a  local  eruption  by  inoculating  smallpox  on  the 
eightli  to  the  eleventh  days,  and  none  after  that. 


Fig.  4. — Vaccinia.     Course  of  the  Eniption. 


15 


16  DISEASES  HAYIXG  SPECIAL  PEOPHYLAXIS 

Taccinia  protects  not  only  against  smallpox,  but  also  against  vac- 
cinia. Curiously  enough^  the  degree  and  length  of  immunity  appear  to 
be  greater  against  smallpox  than  against  itself.  Persons  who  have  had 
smallpox  may  often  be  vaccinated  successfully.  It  is  irrational  to  at- 
tempt to  fix  a  definite  time  for  the  duration  of  the  immunity.  This 
varies  as  in  other  infectious  processes.  It  is  known  through  experiment 
and  experience  that  the  immunity  gradually  wears  off.  The  degree  of 
protection  is  usually  absolute  for  some  years,  and  then  gradually  fades. 
Judged  by  successful  revaccinations,  it  begins  to  disappear  in  2  years 
and  in  10  years  is  almost  completely  gone.  In  this,  as  in  other  diseases, 
immunity  is  a  relative  term.  Smallpox  itself  does  not  always  protect 
against  smallpox.  Some  people  have  two  and  even  three  attacks  of 
smallpox.^  Such  cases,  however,  are  exceptional,  and  it  is  also  ex- 
ceptional to  have  smallpox  occur  in  an  individual  who  has  been  properly 
vaccinated. 

Careful  statistics  collected  in  Japan  since  1879  show  quite  definitely 
the  gradual  diminution  of  the  immunit}',  beginning  with  the  second  year 
after  vaccination.    Kitasato's  table,^°  based  on  951  cases,  is  as  follows: 

SUCCESSFUL   REVACCINATIOX   AFTER 

1  year 13.6  per  cent. 

2  years 32.9     "       " 

3  years 46.6     ^J       |J 

4  years 57.3 

5  years 51.1 

6  years 63.8 

Weil,  in  1899,  reported  72.5  per  cent,  of  successful  revaccinations 
after  seven  years,  80  per  cent,  after  eight  years,  85  per  cent,  after  nine 
years,  and  88.6  per  cent,  after  ten  years.  German  Government  reports 
show  90  to  93  per  cent,  successful  revaccinations  after  10  years. 

It  is  commonly  asserted  that,  if  a  revaccination  takes,  the  subject  was 
therefore  susceptible  to  smallpox.  While  this  is  usually  true,  it  does  not 
necessarily  follow.  It  is  a  still  greater  fallacy  to  state  that,  if  a  vaccina- 
tion fails,  the  subject  is  therefore  immune.  This  view,  may  result  in  real 
harm.  Vaccination  may  fail  for  many  reasons — the  operation  may  not 
have  been  properly  done,  or  the  virus  may  have  been  inert.  Sometimes 
persons  are  unsuccessfully  vaccinated  three,  four,  or  more  times  before 
a  typical  take  is  obtained.^^ 

A  modified  reaction  must  be  regarded  as  evidence  of  immunity. 
Thus,  the  immediate  reaction  is  a  clear  indication  of  immunity,  the 
accelerated  reaction  of  partial  immunity. 

» Jenner  mentions  "the  lady  of  Mr.  Gwinnett,  who  has  had  the  smallpox  five 
times." — Baron's  "Life  of  Jenner,"  Vol.  II,  p.  265. 

^"Jour.  A.  M.  A.,  March  25,  1911,  p.  889. 

"One  of  my  cases  gave  a  history  of  having  been  unsuccessfully  vaccinated 
five  times.     The' sixth  attempt  produced  a  typical  primary  take  ^yith  21  vesicles. 


SMALLPOX  AND  VACCINATION 


17 


There  appears  to  be  a  (lofinite  relation  between  the  immunity  con- 
ferred and  the  number  of  vaccination  scars.  There  is  also  some  evi- 
dence that  the  protection  is  directly  proportional  to  the  area  of  the  local 
eruption.  This  question  has  not  been  carefully  studied  since  the  data 
contained  in  the  final  Report  of  the  Royal  Commission  on  Vaccination, 
which  is  summarized  in  the  following  table: 


MORTALITY 


OF    POSTVACCINAL    SMALLPOX     IX 
OF  SCARS 


RELATION     TO     THE     NUMBER 


Number 
Scars 

of 

3,094  cases* 
(1836-51) 

10.661  cases* 
(1852-67) 

6,839 
casest 

None 

'           21.7% 

39.4% 

1 

7.6 

13.8 

6.2% 

2 

4.3 

7.7 

5.8 

3 

1.8 

3.0 

3.7 

4 

0.7 

0.9  , 

2.2 

*  Final  Report  of  the  Royal  Commission   on  Vaccination,   1896,  paragraph  291.     Dr. 
Thome,  from  data  collected  by  Mr.  Marson. 

t  Same  Report,  paragraph  293.     Summary  of  cases  apart  from  those  of  Mr.  Marson. 


One  point  needs  emphasis :  The  degree  and  duration  of  the  im- 
munity are  directly  proportional  to  the  typical  nature  of  the  take.  No 
reliance  should  be  placed  upon  atypical  reactions. 

The  immunity  may  be  renewed ;  two  vaccinations  are  usually  sufficient 
to  protect  for  life. 

The  nature  of  the  changes  in  the  body  which  produce  the  immunity 
are  not  understood.  In  this  sense  vaccination  is  still  an  empiric  pro- 
cedure. We  now  know  of  many  analogous  instances,  however,  where 
an  active  acquired  immunity  is  induced  by  means  of  an  attenuated  virus. 
The  immunity  produced  by  vaccine  virus  does  not  depend  upon  an  anti- 
toxin. The  blood,  however,  contains  specific  antibodies,  shown  by  the 
fact  that  the  activity  of  vaccine  virus  is  destroyed  when  mixed  with 
equal  parts  of  blood  serum  from  a  calf  two  weeks  after  successful  vacci- 
nation. 

WHEX  TO  VACCIXATE 

The  fact  that  the  immunit}'  wears  off  after  a  number  of  years  makes 
it  necessary  to  practice  revaccination  in  order  to  afford  a  continuous 
protection.  There  is  some  difference  of  opinion  as  to  just  when  it  is 
best  to  vaccinate  the  second  time.  Ten  years  is  too  long  a  period,  prob- 
ably, to  depend  upon  in  individual  cases.  One  vear — advised  by  some — 
is  shorter  than  necessary  in  most  cases.     The  five-year  interval  of  Japan 


18  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

is  good  in  many  respects,  but  probably  not  better  than  revaccination  in 
the  twelfth  year  obligatory  in  Germany. 

The  best  time  to  vaccinate  is  in  the  first  year,  at  least  before  the 
second  summer,  and  again  at  from  ten  to  thirteen  years.  After  this  it  is 
usually  unnecessary  to  vaccinate  again,  unless  there  is  particular  danger 
of  exposure  to  smallpox. 

All  persons  exposed  directly  or  indirectly  to  smallpox  should  at  once 
be  vaccinated  and  revaccinated  until  only  an  immediate  reaction  is 
obtained — unless  they  have  had  smallpox.  There  are  no  contraindica- 
tions to  vaccinating  babies  immediately  after  birth,  but  takes  are  some- 
what less  likely  than  at  six  months.  Vaccination  is  accompanied  by 
less  reaction  in  young  infants  than  in  children,  and  less  in  children  than 
in  adults. 

EEVACCINATION 

The  clinical  picture  of  secondary  vaccinations  may  be  quite  different 
from  the  typical  take  following  a  primary  vaccination.  These  altered 
reactions  were  known  in  the  time  of  Jenner,  but  were  lost  sight  of  until 
recently  rediscovered,  and  their  significance  realized  from  studies  in 
anaphylaxis. 

Revaccinations  may  be  divided  into  three  groups:  (1)  they  may  run 
an  unaltered  course  resembling  primary  takes  in  all  respects,  showing 
that  immunity  to  cowpox  had  disappeared;  (2)  they  may  run  a  somewhat 
more  rapid  course  in  which  the  period  of  incubation  is  shortened  and 
in  which  the  height  of  the  eruption  occurs  about  the  sixth  day,  this 
is  known  as  the  accelerated  reaction;  or  (3)  they  may  run  a  very  much 
shortened,  milder,  and  rapid  course.  The  eruption  may  be  only  a  small 
papule  which  does  not  develop  into  a  vesicle  and  slowly  disappears; 
the  period  of  incubation  is  about  24  hours.  This  is  known  as  the 
immediate  reaction  and  resembles  a  cutaneous  tuberculin  reaction  in 
many  respects.  Every  gradation  occurs  between  an  immediate  reaction 
and  a  primary  take.  These  altered  reactions  are  significant  and  have 
been  studied  especially  by  von  Pirquet  and  are  shown  graphically  in 
Fig.  5.  _  _ 

Both  the  immediate  and  the  accelerated  reaction  are  indications  of 
immunity  and  therefore  should  be  considered  as  successful  takes.  The 
immediate  reaction  may  be  put  to  practical  use  in  order  to  distinguish 
smallpox  from  chickenpox.^^  Thus,  Tieche  has  shown  that  smallpox 
virus  introduced  into  the  skin  of  a  person  immunized  by  vaccination 
will  show  the  typical  immediate  reaction ;  whereas  the  virus  of  chicken- 
pox  is  invariably  negative.  This  test  can  be  freed  of  all  possible  danger 
by  heating  the  virus  to  60°  C.  for  30  minutes,  which  does  not  seem  to 
affect  the  reaction. 
"  See  also  page  395. 


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20  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

CLAIMS  FOR  VACCINATION 

1.  "Duly  and  efficiently  performed  it  will  protect  the  constitution 
from  subsequent  attacks  of  smallpox  as  much  as  that  disease  itself 
will."  " 

2.  It  protects  the  individual  against  smallpox  for  a  period  which 
has  not  been  determined  mathematically  for  the  individual,  but  which 
averages  about  seven  years. 

3.  The  protection  may  be  renewed  by  a  second  vaccination. 

4.  Persons  successfully  vaccinated  on  two  occasions  are  usually 
immune  against  smallpox  for  life. 

5.  Vaccination  and  revaccination  systematically  and  generally  car- 
ried out  confer  complete  protection  to  a  community  or  a  nation.  In 
other  words,  while  the  individual  protection  is  not  always  lasting,  the 
communal  protection  is  absolute. 

6.  A  person  vaccinated  once  and  at  a  later  time  contracting  small- 
pox as  a  rule  has  the  disease  in  a  less  serious  form  than  unvaccinated 
persons  (varioloid).^*  The  degree  of  favorable  modification  of  smallpox 
is  in  inverse  proportion  to  the  period  of  time  elapsing  between  the  vac- 
cination and  the  attack  of  smallpox. 

7.  The  beneficial  effects  of  vaccination  are  most  pronounced  in  those 
in  whom  the  vaccine  affection  has  run  its  most  typical  and  perfect 
course. 

■     ,        VACCINATION  OF  EXPOSED  PERSONS 

The  question  frequently  arises  whether  persons  exposed  to  smallpox 
should  be  vaccinate'd.  The  effect  of  vaccination  during  the  period  of 
incubation  of  smallpox  is  very  interesting,  and  may  be  summed  up  as 
follows : 

1.  Vaccination  just  before  or  during  the  primary  fever  of  smallpox 
does  not  influence  the  disease. 

2.  If  the  vaccination  is  done  during  the  last  stage  (9th  to  14th 
day)  of  the  period  of  incubation  of  smallpox,  the  two  infections  run 
their  course  side  by  side  without  influencing  each  other. 

3.  If  it  is  done  about  the  sixth  or  eighth  day  of  the  period  of  in- 
cubation the  vaccination  takes  and  may  modify  the  severity  of  the 
smallpox. 

4.  Vaccination  done  at  the  beginning  of  the  incubation  period,  in 

"  "I  never  expected  that  it  would  do  more,  and  it  will  not,  I  believe,  do 
less." — Jenner.     Baron's  Life,  Vol,  II,  p.  135. 

"The  term  varioloid  was  introduced  by  Thompson  in  1820  to  describe  the 
mild  and  modified  form  of  smallpox  occurring  after  vaccination.  The  eruption 
in  varioloid  does  not  mature  and  disappears  more  rapidly  than  in  variola. 

Yolfert,  Dornbleuth,  and  Harden  showed  that  one  vaccination  was  not  always 
sufficient  protection  against  smallpox  for  a  lifetime,  that  revaccination  was 
necessary  and  that  the  clinical  manifestations  of  this  vaccination  are  as  different 
from  those  of  the  first  vaccination  as  varioloid  is  from  variola. 


SMALLPOX  AND  VACCINATION  21 

time  to  have  the  vaccine  eruption  reach  maturity  before  the  smallpox 
begins,  will  prevent  or  abort  the  disease. 

As  we  can  never  be  quite  sure  just  what  stage  in  the  period  of  in- 
cubation a  given  case  may  be  in,  it  is  always  advisable  to  vaccinate 
exposed  persons.  Furthermore,  little  harm  will  be  done  if  it  is  too 
late  and  the  vaccine  eruption  is  added  to  the  smallpox.  Indeed,  Hanna  ^'^ 
presents  claims  to  the  effect  that  there  is  evidence  of  mitigation  of  the 
severity  of  smallpox  when  vaccination  is  performed  at  any  time  after 
infection  up  to  the  day  of  onset  and  even  afterward. 

DANGERS  AND  COIklPLICATIONS 

The  alleged  danger  from  vaccination  has  been  greatly  magnified  by 
the  antivaccinationists.  However,  vaccination  is  not  always  a  harmless 
procedure;  it  must  be  looked  upon  as  the  production  of  an  acut^e  infec- 
tious disease,  and,  although  the  disease  is  always  mild  and  benign,  it 
must  not  be  treated  as  trifling.  The  chief  danger  lies  in  the  fact  that 
we  have  produced  an  open  wound,  which  is  subject  to  the  complications 
of  any  wound.  Even  a  pin  prick  or  a  razor  scratch  may  result  in  death. 
While  the  aggregate  number  of  deaths  resulting  from  the  complications 
of  vaccination  were  considerable,  the  Individual  risk  is  now  so  small  as  to 
be  disregarded,  especially  when  proper  precautions  are  taken.  Many 
of  the  infections  after  vaccination  occur  in  those  in  whom  the  regard 
for  cleanliness  is  slight,  and  who  neglect  the  care  of  the  wound.  In 
recent  years,  owing  to  the  improved  quality  of  the  vaccine  virus  and 
the  introduction  of  aseptic  methods,  a  bad  sore  arm  is  a  rare  occurrence, 
and  serious  complications  still  rarer.  The  danger  connected  with  vacci- 
nation is  infinitesimal  when  compared  with  the  benefit  conferred. 

The  following  complications  need  consideration : 

Auto  Vaccination. — This  is  usually  due  to  scratching  the  virus  with 
the  finger  into  the  nose,  the  mouth,  the  mucous  membranes,  or  any  part 
of  the  skin.  When  carried  into  the  eye  it  may  cause  blindness.  Physi- 
cians sometimes  vaccinate  their  lips  by  blowing  into  vaccine  tubes.  In 
vaccine  establishments  accidental  vaccination  of  the  hand  is  common. 

Generalized  Vaccination. — This  is  sometimes  reported,  but  is  in  my 
experience  a  mistaken  diagnosis.  A  generalized  eruption  of  cowpox  is 
exceedingly  rare,  if  it  ever  occurs.  I  have  seen  it  once  in  the  calf  after 
intravenous  injection  of  a  large  amount  of  the  virus,  in  which  case  there 
was  a  prolonged  period  of  incubation. 

The  eruption  is  strictly  confined  to  the  point  of  vaccination.  Satellite 
vesicles  sometimes  develop  in  the  immediate  neighborhood,  owing  to  the 
spread  of  the  virus  into  minute  nicks  in  the  epithelium. 

^'Public  Health,  July,  1910,  XXIII,  No.  10,  p.  351. 


23  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

Wound  Infections,  such  as  ulcers,  gangrene,  erysipelas,  abscesses, 
lymphangitis,  suppuration  of  the  axillary  glands,  and  other  septic  infec- 
tions are  now  exceedingly  rare,  and  demand  the  usual  surgical  measures 
to  prevent  their  occurrence. 

Impetigo  contagiosa  occasionally  occurs  and  may  be  a  serious  com- 
plication of  vaccination^  trspecially  the  rare  bullous  impetigo  or 
pemphigus  which  is  attributed  to  special  susceptibility  or  chance  infec- 
tion and  not  to  the  vaccine  virus. 

(Syphilis,  tuberculosis,  and  leprosy  were  formerly  thought  of  as 
possibilities  when  human  virus  was  used,  but  these  are  not  to  be  feared 
with  the  use  of  bovine  virus.) 

Tetanus. — Tetanus  deserves  a  special  word.  This  serious  infection 
sometimes  complicates  a  vaccination  wound  just  as  it  may  any  wound. 
When  we  consider  the  many  millions  of  vaccination,  wounds,  many  of 
which  are  neglected  surgically,  it  is  no  surprise  to  learn  that  tetanus 
occasionally  occurs  as  a  postvaccinal  complication.  Acland  is  acquainted 
with  only  one  instance  in  more  than  five  million  consecutive  vaccinations 
in  England,  and  even  in  this  one  there  was  no  evidence  that  the  tetanus 
was  in  the  vaccine  virus.  Over  31,000,000  doses  of  vaccine  were  used 
in  the  United  States  from  1904  to  1913  inclusive,  yet  only  41  authen- 
ticated cases  of  tetanus  occurred  subsequent  to  vaccination.^^  A  study 
of  these  cases  makes  it  clear  that  the  infective  principle  was  not  in  the 
vaccine  virus,  but  was  received  ten  days  or  more  after  vaccination, 
owing  to  the  prolonged  period  of  incubation  (20.7  days)  and  the  high 
mortality  (75.2  per  cent.).  The  pernicious  method  of  vaccination  by 
scarification  was  used  in  almost  all  cases  of  tetanus  following  vaccination. 
Many  of  the  cases  give  a  history  of  having  the  vaccination  scab  or  crust 
removed  in  some  way,  thus  permitting  infection  of  the  wound  with  a 
re-formation  of  the  crust  and  the  establishment  of  an  anaerobic  condi- 
tion. The  fact  that  lack  of  care  is  an  important  factor  in  postvaccinal 
tetanus  is  indicated  in  the  figures  from  the  United  States  Army  and 
Navy  with  a  record  of  millions  of  vaccinations  without  a  single  case  of 
tetanus.  At  the  Hygienic  Laboratory  at  Washington  vaccine  virus 
representing  over  two  million  vaccinations  has  been  examined  without 
finding  tetanus.  Special  tests  for  tetanus  are  required  by  Federal  regula- 
tions of  every  lot  of  vaccine  virus  before  it  is  placed  upon  the  market. 
In  the  Vaccine  Laboratory  of  the  State  Department  of  Health  of  Mas- 
sachusetts, these  tests  are  conducted  in  accordance  with  the  Eegulations  ^'^ 
of  the  U.  S.  Public  Health  Service  of  October  1,  1919,  as  follows: 

Samples  of  the  virus  from  each  calf  are  tested  separately.     Only 

*'J.  F.  Anderson:  United  States  Public  Health  Keport,  Reprint  289,  July 
16,  1915. 

"Edward  Francis,  "Laboratory  Studies  on  Tetanus,"  Hvgienic  Laboratory 
Bull.,  No.  95,  August,  1914,  U.  S.  Public  Health  Service.  Also  G.  W.  McCoy  and 
Ida  A.  Bengston,  Hyg.  Lab.  Bull.  No.  115,  Oct.,  1918. 


SMALLPOX  AND  VACCINATION  23 

ground  glycerinated  piil[)  ki'{)i  without  preservative  for  at  least  7  days 
at  a  temperature  of  10°  C.  or  higher  is  used  for  the  tetanus  test.  This 
is  to  permit  tiie  destruetion  l)y  the  glycerin  of  the  most  of  the  frail 
hat'teria.  Tlie  test  virus  must  not  contain  pliciiol  or  preservative  other 
than  glvicrin.  Two  euhie  centimeters  of  the  virus  is  planted  in  each 
of  four  Smith  fermentation  tuhes,  each  containing  at  least  25  cubic 
centimeters  of  meat  infusion  hrotli.  The::e  tubes  are  heated  to  100°  C. 
for  thirty  minutes  just  before  planting  in  order  to  expel  the  oxygen  of 
the  air.  The  tubes  are  incubated  at  .'>7°  C.  and  inspected  daily;  those 
showing  gas  or  growth  in  the  closed  arm  are  used  to  inoculate  mice  or 
guinea  pigs  with  one  cubic  centimeter  of  the  unfiltered  broth,  not  less 
than  tvi'enty-four  hours  after  growth  in  the  closed  arm  and  also  nine 
days  after  planting.  If  the  animals  show  symptoms  of  tetanus,  the 
entire  batch  of  vaccine  is  discarded.     Or: 

(a)  Plant  0.25  c.  c,  virus  in  plain  broth  fermentation  tube.  In- 
cubate at  37°  C  and  inject  0.25  c.  c.  of  the  growth  at  the  end  of  9  days 
subcutaneously  into  a  mouse. 

(b)  Plant  0.25  c.  c.  virus  into  fermentation  tubes  of  glucose  bouillon 
and  incubate  immediately.  Inject  0.25  c.  c.  of  the  growth  at  the  end  of 
9  days  subcutaneously  into  mice. 

(c)  Plant  0.25  c.  c.  vaccine  virus  into  fermentation  tubes  of  glucose 
bouillon,  heat  at  60°  C.  for  one  hour  and  then  incubate.  Inject  0.25  c.  c. 
of  the  growth  into  mice  at  the  end  of  9  days. 

(d)  Plant  0.25  c.  c.  vaccine  virus  into  fermentation  tubes  of  ordi- 
nary bouillon,  containing  a  bit  of  sterile  tissue,  and  inject  0.25  c.  c.  of 
the  growth  at  the  end  cf  9  days  into  mice. 

(e)  Inject  0.25  of  the  vaccine  virus  subcutaneously  into  guinea-pigs. 
If  tetanus  spores  are  present  in  the  virus,  one  of  these  four  methods 

is  almost  sure  to  detect  them.  The  tests  are  made  in  duplicate  so  that  a 
total  of  2.5  c.  c.  of  the  virus  is  thus  tested. 

The  occurrence  of  occasional  stray  tetanus  spores  in  vaccine  virus 
was  demonstrated  by  Carini.^^  Such  vaccine,  however,  had  proved  en- 
tirely harmless  in  thousands  of  cases.  Francis  also  showed  that  vaccine 
virus  purposely  contaminated  with  tetanus  spores  will  not  produce 
tetanus  in  monkeys,  although  it  will  produce  typical  "takes." 

Glycerin  does  not  destroy  the  tetanus  spore.  While  the  occa- 
sional danger  cannot  be  denied,  it  is  plain  that  postvaccinal  tetanus 
can  usually  be  laid  to  improper  methods  of  vaccination  and  to  lack  of 
care  of  the  vaccination  wound. 

To  prevent  tetanus  complications  it  is  important  to  avoid  scarifica- 
tion and  irritation,  to  avoid  the  use  of  shields  and  bandages  which  favor 
anaerobic  conditions,  to  require  the  patient  to  use  strict  cleanliness,  and 
to  use  vaccine  virus  that  has  been  properly  prepared  and  tested. 

"^Centralhl.  f.  BaJct.,  Orig.  1904,  XXXVII,  p.  1147. 


24  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

Foot-and-Mouth.  Disease. — The  infection  of  foot-and-mouth  disease 
has  in  one  instance  been  demonstrated  as  a  contamination  of  vac- 
cine virus.^^  It  is,  however,  impossible  to  convey  foot-and-mouth  dis- 
ease to  man  through  cutaneous  inoculation.  While  no  harm  has  been 
done  to  man,  the  contamination  is  undesirable,  and  vaccine  virus  is 
tested  from  time  to  time  to  assure  its  freedom  from  this  infec- 
tion (page  406). 

As  an  illustration  of  how  seldom  complications  are  caused  by  vac- 
cination we  have  the  results  of  Germany,  where  in  thirteen  years  (1885- 
1898)  32,166,619  children  were  vaccinated.  Of  these  115  died  within 
a  few  weeks  or  months  after  the  Operation,  presumably  of  injuries  in- 
cidental thereto.  Of  these  at  least  48  probably  did  not  die  as  a  direct 
result  of  the  vaccination. 

The  figures  of  recent  years  are  still  better,  for  it  is  now  exceedingly 
rare  for  a  death  to  be  recorded  as  directly  due  to  vaccination. 

Ten  million  vaccinations  in  the  Philippine  Islands  were  done  under 
the  direction  of  American  health  authorities  without  the  loss  of  life  or 
limb.  Of  the  millions  of  vaccinations  done  in  the  army  and  navy  during 
the  World  War,  there  is  not  a  single  record  of  serious  result.  This 
clearly  indicates  that  with  the  use  of  a  carefully  tested  virus  and  efficient 
technic,  the  danger  is  nil. 

THE  GOVEENMENT  CONTROL  OF  VACCINE  VIRUS 

By  the  law  of  July  1,  1902,  the  vaccine  virus  sold  in  interstate  traf- 
fic in  the  United  States  must  come  from  a  licensed  manufacturer. 
These  licenses  are  issued  by  the  Secretary  of  the  Treasury  only  after  a 
careful  inspection  of  the  plant,  personnel,  and  product  by  a  competent 
government  officer.  The  licenses  are  good  for  one  year  only,  and  are 
reissued  only  after  reinspection.  The  government  regulations  require 
each  lot  of  vaccine  virus  to  be  examined  carefully  by  modern  bacterio- 
logical methods  to  determine  the  number  of  bacteria,  and  special  tests 
must  be  made  to  determine  the  absence  of  pathogenic  microorganisms. 
These  tests  include  animal  inoculations,  as  well  as  cultural  methods. 
Special  tests  for  each  lot  of  vaccine  must  be  made  to  determine  the 
presence  or  absence  of  streptococci,  tetanus  spores,  the  gas  bacillus,  and 
other  pathogenic  microorganisms,  etc.  The  government  does  not  guaran- 
tee the  purity  and  potency  of  each  package  of  vaccine  virus,  but  through 
its  inspections  and  frequent  examinations  of  the  virus  on  the  market 
every  confidence  may  now  be  had  in  the  vaccine  virus  propagated  by 
licensed  manufacturers  in  this  country. 

"Mohler  and  Rosenau,  U.  S.  Dept.  of  Agriculture,  B.  A.  I.  Circular  147, 
June  16,  1909. 


SMALLPOX  AND  VACCINATION  25 

THE  UNITY  OF  COWPOX  AND  SMALLPOX 

The  unity  or  duality  of  these  two  diseases  has  been  the  subject  of 
much  contention.  Jenner  originally  considered  cowpox  to  be  a  modified 
smallpox.20  The  successful  experiments  in  Germany,  England,  and  this 
country,  in  which  smallpox  has  actually  been  modified  by  passing  vario- 
lous matter  through  calves  has  proved  positively  that  we  are  dealing  with 
two  forms  of  one  disease.  Much  of  the  vaccine  virus  used  during  the 
past  hundred  years  was  originally  obtained  from  cases  of  casual  cow- 
pox.  This  virus  has  been  shown  by  experience  and  experiments  to  pro- 
tect against  smallpox,  which  again  makes  it  highly  probable  that  we  are 
dealing  with  one  disease.     See  also  page  8. 

It  seems  plain  that  the  so-called  casual  cowpox  has  its  origin  from 
smallpox  through  accidental  inoculation  in  milking  cows  by  persons 
having  or  recovering  from  smallpox.  Once  started,  the  propagation  of 
the  modified  virus  from  cow  to  cow  would  be  comparatively  simple. 

COMPULSORY  VACCINATION 

Vaccination  affords  a  high  degree  of  immunity  to  the  individual,  and 
a  well-nigh  perfect  protection  to  the  community.  To  remain  unvac- 
cinated  is  selfish  in  that  by  so  doing  a  person  steals  a  certain  measure 
of  protection  from  the  community  on  account  of  the  barrier  of  vac- 
cinated persons  around  him. 

The  laws  ^^  and  regulations  relating  to  vaccination  in  the  several 
states  of  the  United  States  show  marked  lack  of  uniformity.  Compul- 
sory general  vaccination  can  be  said  to  exist  by  law  only  in  Kentucky, 
Philippine  Islands,  and  Porto  Kico.^^  Arizona,  Hawaii,  Maryland,  New 
Mexico,  and  North  Dakota  have  laws  requiring  vaccination  of  children. 
Most  states  or  cities  have  laws  requiring  vaccination  before  admission 
to  the  public  schools. 

Decisions  in  the  various  courts  in  the  United  States  have  held  com- 
pulsory vaccination  to  be  legal.  A  decision  of  the  Supreme  Court  of 
the  United  States  (Henning  Jacobson  vs.  The  Commonwealth  of  Massa- 

^"  Smallpox  is  a  disease  subject  to  mutations.  Since  1898  a  mild  form  of 
smallpox  has  existed  in  this  country  with  a  death-rate  of  about  0.5  per  cent. 
This  mild  form  shows  little  tendency  at  present  to  increase  in  virulence. 
Chickenpox  itself  may  belong  to  the  smallpox  family.  The  two  diseases  are 
sometimes  indistinguishable  at  the  bedside.  Jenner  always  considered  cowpox 
and  smallpox  as  modifications  of  the  same  "distemper,"  and  that  in  using 
vaccine  lyjuph  he  was  impregnating  the  constitution  with  the  disease  in  ita 
mildest  form  instead  of  propagating  it  in  its  virulent  and  contagious  form. 
Alastrim,  kaffirpox,  milkpox,  etc.,  are  aberrant  forms  of  smallpox  occurring  in 
the  tropics,  and  for  public  health  purposes  should  be  regarded  as  variola  vera. 
These  irregular  forms  of  the  disease  need  further  study. 

^'Kerr,  J.  W.,  "Vaccination,  and  Analysis  of  the  Laws  and  Regulations 
Relating  Thereto  in  Force  in  the  United  States."  Public  Healtlv  Bull.  52. 

-^Massachusetts,  in  1809,  was  the  first  state  to  enact -legislation  relative  to 
vaccination. 


26  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

chusetts,  April  1,  1905)  upheld  in  every  respect  the  statute,  the  validity 
of  which  was  questioned  under  the  Constitution : 

"The  liberty  secured  by  the  Constitution  of  the  United  States  .  .  . 
does  not  impart  an  absolute  right  in  each  person  to  be,  at  all  times,  and 
in  all  circumstances,  wholly  freed  from  restraint.  Pieal  liberty  for  all  could 
not  exist  under  the  operation  of  a  principle  which  recognizes  the  right  of 
each  individual  person  to  use  his  own,  whether  in  respect  to  his  person 
or  his  property,  regardless  of  the  injury  that  may  be  done  to  others." 

Theoretically  it  would  be  ideal  if  all  persons  submitted  to  vaccina- 
tion and  revaccination  voluntarily.  But  experience  has  shown  that  this 
is  impractical,  and,  wherever  tried,  has  failed.  The  best  results  have 
always  been  obtained  where  vaccination  has  been  compulsory,  and,  in 
my  judgment,  this  is  the  only  present  means  by  which  smallpox  may  be 
eliminated. 

The  world  may  learn  a  valuable  lesson  from  the  splendid  results  ob- 
tained in  Germany  through  compulsory  vaccination  and  revaccination. 
In  England  the  "conscience  clause"  allows  many  persons  to  remain  un- 
vaccinated  and  thereby  seriously  diminishes  the  effects  of  the  vacci- 
nation laws  of  that  land.  In  Minnesota  the  state  health  authorities  be- 
came weary  of  the  clamor  against  compulsory  vaccination  and  assisted 
in  having  the  law  repealed.  They  said,  in  substance,  to  the  people  of 
the  state:  "Take  your  choice.  Be  vaccinated  and  protect  yourself,  or 
run  the  risk  of  contracting  smallpox;  if  you  get  it,  it  is  your  own  fault." 

There  is  now  much  smallpox  widely  distributed  in  the  United  States, 
among  a  large  non-vacinnated  portion  of  the  population. 

INOCULATION  OR  VARIOLA  INOCULATA 

[Variolation] 

The  practice  of  inoculation  or  variolation  must  be  carefully  distin- 
guished from  that  of  vaccination.  By  inoculation  we  mean  the  introduc- 
tion of  smallpox  virus  into  the  skin  of  man.  The  disease  thus  pro- 
duced is  usually  mild,  but  is  nevertheless  true  smallpox,  and  just  as  con- 
tagious as  smallpox. 

This  phase  of  the  subject  may  be  made  clearer  by  considering  small- 
pox as  existing  in  three  forms:  (1)  variola  vera  or  true  smallpox;  (2) 
variola  inoculata  or  inoculated  smallpox;  (3)  vaccinia,  cowpox,  or  modi- 
fied smallpox.  The  differences  between  these  affections  are  shown  in  the 
table  on  the  following  page. 

Emphasis  must  be  placed  on  the  fact  that  variola  inoculata,  while 
usually  a  mild  disease,  is  just  as  communicable  as  true  smallpox,  and 
those  who  contract  the  disease  in  this  way  get  true  smallpox,  sometimes 
in  serious  or  fatal  form.  Inoculation,  therefore,  protects  the  individual 
but  endangers  the  community. 


SMALLPOX  AND  VACCINATION 


27 


Variola  Vera 

Variola  Znocnlata 

Vaccinia  or  Cowpox 

True  smallpox. 

Inoculated  smallpox. 

Modified  and  attenuated  small- 
pox. 

Occurs   only   in   man. 

Occurs  in  man  and  monkeys. 

Man,  nionlceys,  cattle,  puineu- 
piKs,  raljtjits,  rats,  camels, 
and   many  other  mammals. 

High  mortality. 

Milder;    rarely    fatal;    about   1 
in  500. 

Very  mild  ;   never  fatal. 

A  general  eruption,  often 
confluent  or  liemor- 
rhagic. 


Highly  contagious. 


A  local  and  a  general  eruption, 
fewer  .p,ustules  (rarely  over: 
200);  seldom  confluent  or 
hemorrhagic. 


Equally  highly  contagious. 


Period    of    incubation    12-8   days. 
14  days.  I 


Always    local    and    conflned    to 
the  site  of  the  vaccination. 


Not  contagious — contracted  only 
by  mechanical  transfer  of 
vaccine  virus. 


3-4   days. 


Inoculation  is  a  very  old  custom.  It  was  practiced  by  the  Chinese 
from  time  immemorial.  The  method  was  introduced  into  western  civili- 
zation through  Lady  Mary  Wortley  Montagu,  who  learned  of  the  method 
at  Constantinople  and  had  her  own  boy  "engrafted"  with  successful  re- 
sult. In  1717  Lady  Montagu  wrote  her  now  famous  letter  to  her  friend 
Sarah  Chiswell,  and  the  practice  soon  became  popular  in  England 
(1721)  and  spread  to  America  and  the  Continent.^^  It  was  introduced 
into  this  country  by  Dr.  Zabdiel  Boylston  at  Boston.  But  the  dangers 
were  early  realized  and  inoculation  was  soon  replaced  by  vaccination. 
According  to  Plehn,  inoculation  is  still  practiced  in  central  Africa. 

The  method  of  inoculation  is  precisely  similar  to  that  of  vaccina- 
tion. The  matter  is  obtained  from  the  vesicle  or  pustule  of  a  case  of 
smallpox.  This  material  is  then  introduced  into  the  skin  by  means  of 
a  puncture,  an  incision,  or  through  an  abraded  surface.  The  Chinese 
inoculate  usually  by  plugging  the  nostrils  with  cotton  previously  sat- 
urated with  a  mixture  of  water  and  pustular-crustaceous  matter  taken 
from  the  eruption  of  a  smallpox  patient;  less  commonly  by  blowing  the 
crushed  fresh  crusts  into  the  nostrils  through  a  bamboo  pipe. 

Following  the  inoculation  of  smallpox  virus  a  local  eruption  appears 
on  the  fourth  day  at  the  site  of  the  inoculation.  This  local  eruption 
resembles  vaccinia  but  develops  more  rapidly.  Constitutional  symptoms 
appear  on  the  evening  of  the  seventh  or  the  morning  of  the  eighth  day 
following  the  inoculation.  These  symptoms  resemble  the  onset  of  true 
smallpox  and  are  rigor,  headache,  vomiting,  and  fever.     The  local  erup- 

"  The  practice  of  inoculation  had  been  published  in  England  as  early  as 
1714  by  Dr.  Timoni  of  Constantinople;  at  Venice  in  1715  by  Pylarini,  and  in  the 
same  year  in  London  by  ilr.  Kennedy,  a  surgeon  who  had  been  in  Turkey. 
Its  adoption  and  subsequent  ditfusion,  however,  were  due  to  Lady  Mary  Wortley 
Montagu. 


28  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

tion  subsides  on  the  appearance  of  the  febrile  symptoms  but  at  the  same 
time  the  general  eruption  breaks  out.  The  crop  is  usually  discrete,  mod- 
erate in  number,  but  runs  the  usual  course  through  papule,  vesicle  and 
pustule  formation. 

Inoculation  has  fallen  into  disuse  only  because  we  have  vaccination. 
There  are  conceivable  emergencies  in  which  the  practice  would  be  justi- 
fied. For  example,  on  board  ship  or  on  an  island  or  isolated  place,  in 
the  absence  of  vaccine  virus.  Under  such  circumstances  it  would  be 
essential  to  inoculate  ever3^body  at  the  same  time. 

The  inoculation  of  smallpox  will  always  remain  for  the  student  of 
hygiene  one  of  the  most  interesting  episodes  in  the  develop- 
ment of  preventive  medicine.  It  illustrates  in  the  clearest  manner 
some  of  the  fundamental  phenomena  of  infection,  susceptibility,  and 
immunity.  It  was  animal  experimentation  on  a  huge  scale,  the  like  of 
which  we  shall  never  see  repeated  on  man  as  the  subject.  It  is  now  a 
matter  of  regret  that  for  the  sake  of  science  better  advantage  was  not 
taken  of  the  data. 

PREVALENCE  OF  SMALLPOX 

It  is  very  difficult  for  us  now  to  realize  that  smallpox  was  once  much 
more  common  than  measles  and  much  more  fatal.  Many  of  those  who 
recovered  were  disfigured  for  life,  left  blind,  or  with  some  other  serious 
consequence  of  the  disease.  For  centuries  smallpox  was  one  of  the 
greatest  scourges.  It  depopulated  cities  and  exterminated  nations.  In 
Europe  alone,  where  its  ravages  were  comparatively  slight,  it  killed 
hundreds  of  thousands  yearly.  In  the  18th  century,  of  which  we  have 
the  best  records,  almost  everybody  had  it  before  he  grew  up.  Parents 
often  exposed  their  children  to  the  disease  in  order  to  be  through  with 
it,  just  as  they  now  sometimes  do  with  the  minor  contagious  dis- 
eases. 

Smallpox  was  formerly  a  disease  of  children.  It  was  called  Kinder- 
hldttern.  Since  vaccination  protects  the  child,  smallpox  has  now  be- 
come more  prevalent  among  adults. 

The  distinguished  mathematician,  Bernouille,  estimated  that  15,000,- 
000  people  died  of  smallpox  in  25  years  in  the  18th  century.  It  has 
been  estimated  that  60,000,000  people  died  of  smallpox  during  that 
century.  Haygarth  gives  an  account  of  a  smallpox  epidemic  in  Chester, 
England,  population  14,713.  At  the  termination  of  the  epidemic  there 
were  but  1,060  persons,  or  7  per  cent,  of  the  population,  who  had  never 
had  smallpox.  Many  similar  instances  are  cited  in  the  literature.  The 
French  physician  de  la  Condamine  (1754)  said  that  "every  tenth  death 
was  due  to  smallpox  and  that  one-fourth  of  mankind  was  either  killed 
by  it  or  crippled  or  disfigured  for  life."     Sarcone  (1782)  estimated  the 


SMALLPOX  AND  VACCTNATTOX  29 

number  of  persons  in  Italy  who  tJufTered  from  smallpox  as  90  j)or  cent, 
of  the  population. 

Smallpox  was  introduced  into  the  western  hemisphere  by  the  Span- 
iards about  fifteen  years  after  the  discovery  of  America.  In  Mexico 
within  a  short  period  3,500,000  persons  are  said  to  have  died  of 
the  disease  (Chapman).  Catlin  (1S41)  states  thai  of  1-^,000,000 
American  Indians  6,000,000  fell  victims  to  smallpox.  In  Iceland,  in 
1707,  18,000  perished  out  of  a  population  of  50,000,  that  is,  smallpox 
iilfled  36  per  cent,  of  the  total  population  in  one  year. 

A  good  example  is  that  of  Boston  in  1752,  population  at  that  time 
15,684.  Of  this  number  5,998  had  previously  had  smallpox.  During 
the  epidemic  5,545  persons  contracted  the  disease  in  the  usual  manner, 
and  2,124  took  it  by  inoculation.  One  thousand  eight  hundred  and  forty- 
three  persons  escaped  from  the  town  to  avoid  infection.  There  were, 
therefore,  left  in  the  city  but  174  persons  who  had  never  had  smallpox. 

Smallpox  is  still  as  serious  as  it  was  in  former  times.  Thus,  in  five 
years,  from  1893-1897,  346,520  persons  died  of  smallpox  in  sixteen 
countries.  Of  this  number  Russia  alone  lost  275,502.  These  figures  are 
the  more  terrible  when  it  is  realized  that  these  lives  might  have  been 
saved  by  the  use  of  a  simple  prophylactic  measure  within  reach  of  all. 

EPIDEMIOLOGY 

Few  of  the  acute  infectious  diseases  show  such  a  complete  indepen- 
dence of  conditions  such  as  race,  climate,  soil,  age,  sex,  and  occupation, 
sanitary  surroundings,  etc.,  as  does  smallpox.  It  thrives  wherever  the 
contagion  is  carried,  and  wherever  it  finds  susceptible  people.  Prob- 
ably no  one  is  naturally  immune.  The  susceptibility  of  an  unvaccinated 
population  varies,  because  a  smallpox  outbreak  leaves  so  many  immune. 
This  is  one  reason  why  the  disease  recurs  in  waves.  The  mortality 
varies  greatly  in  difEerent  epidemics.  At  times  it  is  less  than  one  per 
cent.;  it  frequently  reaches  thirty  per  cent,  and  over. 

From  1897-1912  the  mortality  in  the  United  States  varied  from  0.34 
per  cent,  to  6.2  per  cent.;  in  1895  it  was  20.84  per  cent.,  and  following 
that  0.5  per  cent.  These  differences  occurred  in  the  prevaccination  era 
as  well  as  now.  There  seem  to  be  two  distinct  strains  in  the  United 
States,  one  the  classic  smallpox  of  the  text  books,  the  other  a  very  mild 
form. 

The  epidemiology  of  smallpox  bears  no  relation  to  improved  sanita- 
tion, which  has  diminished  the  prevalence  of  plague,  typhoid,  cholera, 
and  has  practically  subdued  typhus  and  relapsing  fever.  It  is  evident 
that  general  sanitation  could  not  affect  contagious  diseases  like  small- 
pox and  measles.  Smallpox  spares  neither  the  high  nor  the  low,  the  rich 
Dor  the  poor,  the  clean  nor  the  dirty;  before  the  days  of  vaccination  it 


30  DISEASES  HAYIXG  SPECIAL  PEOPHYLAXIS 

counted  many  kings,  queens,  and  princes  among  its  victims.     George 
"Washington  contracted  smallpox  in  the  West  Indies. 

MODES  OF  INFECTION 

We  are  still  ignorant  of  the  precise  mode  by  which  smallpox  is  con- 
veyed. The  view  generally  held  is  that  the  infection  is  air-borne  and 
enters  the  system  through  the  respiratory  mucous  membranes.  It  has 
been  surmised  that  a  local  lesion  may  be  produced  in  this  favorable  soil, 
the  so-called  "propustule,"  from  which  general  infection  through  the 
blood  takes  place.  The  blood  infection  is  marked  by  a  sharp  onset  (the 
initial  symptoms),  and  the  skin  eruption  is  embolic  in  character.  The 
objection  to  this  view  is  that  a  careful  search  at  54  autopsies  in  Boston 
by  Councilman  and  his  colleagues  failed  to  find  such  a  propustule. 

The  Chinese  inoculate  the  disease  by  placing  variolous  matter  in 
the  nostrils,  but  the  disease  so  produced  is  said  to  resemble  variola 
inoculata. 

The  virus  of  smallpox  is  contained  in  the  skin  lesions.  Of  this  we 
have  experimental  evidence.  It  is  also  supposed  to  be  in  the  expired 
air.  This,  however,  has  never  been  experimentally  proved  and  is  doubt- 
ful. The  disease  is  contagious  before  the  eruption  appears.  It  is  even 
believed  to  be  communicable  during  the  period  of  incubation.  Small- 
pox has  always  been  taken  as  the  type  of  the  contagious  diseases;  the 
contagion  appears  to  be  the  most  "volatile"  of  any  of  the  diseases  of 
man  with  the  possible  exception  of  measles  and  influenza.  This  volatil- 
ity, however,  has  been  over  estimated,  and,  while  probably  an  air-borne 
infection,  the  radius  of  danger  is  contracted.  English  observers  have 
long  taken  the  vicAv  that  smallpox  may  be  blown  for  great  distances, 
and  they  attribute  the  prevalence  of  smallpox  to  the  windward  of  hos- 
pitals as  an  indication  that  the  virus  may  be  carried  down  the  wind. 
My  experience  with  the  disease  teaches  me  that  the  danger  from  such 
a  source  is  practically  nil.  One  may  safely  live  next  door  to  a  small- 
pox hospital  that  is  well  screened  and  properly  managed.  The  influence 
of  flies  and  other  insects,  or  surreptitious  visiting,  may  account  for  the 
spread  of  this  disease  outside  of  hospital  walls. 

In  addition  to  more  or  less  direction  contact,  smallpox  may  be  spread 
indirectly  in  a  great  variety  of  ways.  The  secretions  from  the  mouth 
and  nose  doubtless  contain  the  infection,  and,  while  suspicion  has  not 
particularly  fallen  upon  the  feces  and  urine,  it  is  probable  that  all  the 
secretions  and  excretions  from  the  body  may  be  infective  at  some  time 
throughout  the  disease,  or  during  convalescence.  Toys,  pencils,  spoons, 
cups,  towels,  handkerchiefs,  bedding,  and  objects  of  the  greatest  variety 
that  have  in  any  way  come  in  contact  with  the  patient  may  carry  the 
infection.    Under  favorable  circumstances  the  active  principle  may  prob- 


SMALLPOX  AND  VACCINATION  31 

ably  live  for  a  considerable  time  upon   I'omites,  altlu)ii;^di  tbc  praetieal 
danger  from  this  source  is  not  very  great. 

Smallpox  is  not  usually  considered  an  insect-borne  disease,  but  it  is 
highly  probable  that  a  fly  lighting  upon  a  smallpox  patient  and  getting 
its  proboscis,  feet,  and  other  portions  of  its  body  smeared  with  the 
variolous  matter,  and  then  flying  to  a  susceptible  person,  could  thus 
readily  transmit  the  infection.  Other  insects  may  by  such  mechanical 
transfer  play  a  similar  rule. 

RESISTANCE  OF  THE  VIRUS 

It  is  generally,  and  doubtless  correctly,  assumed  that  the  active  prin- 
ciple of  variola  has  approximately  the  same  resistance  to  external  con- 
ditions as  vaccine  virus.  This  assumption  is  confirmed  by  experimental 
evidence,  which  shows  that  the  virus  of  smallpox  is  somewhat  more 
readily  destroyed  than  the  virus  of  cowpox.  Scientific  data  concerning 
the  viability  of  variolous  matter  is  meager,  owing  to  the  fact  that  this 
question  can  only  be  settled  by  prolonged  and  repeated  experiments  upon 
monkeys.  Brinckerhoff  and  Tyzzer  ^^  found  that  variolous  virus  is  less 
resistant  to  desiccation  than  vaccine  virus;  that  variolous  virus  does  not 
pass  a  Berkefeld  filter  and  is  attenuated  by  long  exposure  to  60  per  cent, 
glycerin. 

In  general  it  may  be  said  that  variolous  virus  is  killed  by  exposure 
to  ordinary  germicidal  substances,  both  liquid  and  gaseous,  in  the 
strengths  and  time  commonly  employed.  It  succumbs  in  fact  before 
the  average  non-spore-bearing  bacteria. 

There  is  an  exception  to  this  statement  in  the  case  of  carbolic  acid 
and  the  coal-tar  disinfectants.  McClintock  and  Ferry  -^  have  shown 
that  such  germicides  as  carbolic  acid,  cresols,  and  the  like  do  not  destroy 
the  virulence  of  vaccine' virus  in  0.5  per  cent,  solutions  in  five  hours'  ex- 
posure.-® Noguchi  found  that  1  per  cent,  phenol  has  no  injurious  ef- 
fect upon  emulsions  of  the  testicular  strain  of  vaccine  virus.  The  in- 
ference is  allowable  that  this  class  of  disinfectants  cannot  be  relied  upon 
to  prevent  the  spread  of  smallpox. 

Glycerinated  virus  is  very  susceptible  to  heat. 

SMALLPOX  IN  TEE  VACCINATED  AND  UNVACCINATED 

The  experience  of  over  one  hundred  years  offers  convincing  proof 
of  the  pronounced  difference  in  the  mortality  and  morbidity  from  small- 
pox in  the  vaccinated  and  the  unvaccinated. 

""Studies  upon  Experimental  Variola  and  Vaccinia  in  Quadrumana,"  Jour. 
Med.  Research,  Vol.  XIV,  No.  2,  Jan..  1906,  pp.  223-3.59. 

^Jour.  of  the  Amer.  Public  Health  Assn.,  June,  1911  (Vol.  I,  No.  6), 
p.  418. 

^  Jo«r.  Exp.  Med.,  March  1,  1918. 


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34 


DISEASES  HAVING  SPECIAL  PROPHYLAXIS 


In  countries  like  Germany.  Sweden,  Ireland,  Scotland,  the  Philip- 
pine Islands,  Porto  Eico,  and  England,  where  vaccination  is  more  or 
less  compulsory,  there  is  comparatively  little  smallpox.  In  countries, 
like  Belgium,  Russia,  Austria,  and  Spain,  which  have  no  compulsory 
vaccination  laws,  smallpox  yearly  claims  many  victims.  See  the  follow- 
incf  table : 


TABLE 


1. — DEATHS    FROM    SMALLPOX    IN   COUNTRIES   WITH   COMPULSORY  VAC- 
CINATION  AND   THOSE   WITHOUT   COMPULSORY   VACCINATION 


Population 


Sweden*     4,746.465 

Ireland*     4,808,728 

Scotland*     4.013,029 

Germany*    47,923,735 

England*    28,247,151 

Switzerland    2,922,430 

Belgium    5,940,365 

Russia     92,822,470 

Austria    23,000,000 

Italy     29,717,982 

Spain    11,864,000 


Smallpox  Deaths 

Average 

of 
Deaths 

Average 
per 

1886 

1887 

1888 

1889 

Million 
of  Pop. 

1 

5 

9 

2 

4 

1 

2 

14 

3 

0 

5 

1 

24 

17 

0 

6 

12 

3 

197 

168 

112 

200 

i69 

3.5 

275 

505 

1,026 

23 

458 

16 

182 

14 

17 

3 

54 

18.5 

1,213 

610 

865 

1,212 

i         975 

164 

16,938 

25,884 

9 

9 

21,411 

231 

8,794 

9,591 

14,138 

12,358 

11,220 

510 

■? 

16.249 

18,110 

13,416 

15,925 

536 

•> 

■> 

14,378 

8,472 

11,425 

963 

*  Compulsory  vaccination. 

April  8th,  1874,  Germany  passed  a  general  compulsory  vaccination 
and  revaccination  law.  The  law  requires  the  vaccination  of  all  infants 
before  the  expiration  of  the  first  year  of  life,  and  a  second  vaccination 
at  the  age  of  twelve.  Since  this  law  went  into  effect  there  have  been 
no  epidemics  of  smallpox  in  Germany,  despite  the  fact  that  the  disease 
has  been  frequently  introduced  from  without.  In  1897  there  were  but 
8  deaths  from  smallpox  in  the  entire  German  empire — population  54,- 
000,000.  Since  then  long  periods  have  passed  without  a  single  death 
from  smallpox.  From  1901  to  1910  there  were  only  380  deaths  from 
smallpox  in  Germany;  during  the  same  period  there  were  4,286  deaths 
from  smallpox  in  England  and  Wales,  with  only  about  half  the  popula- 
tion of  Germany;  furthermore,  many  of  the  deaths  in  Germany  were 
in  foreigners.  Thus  in  1909,  out  of  26  deaths  from  smallpox,  13  were 
foreigners,  11  of  whom  were  Russians.  In  1911,  there  were  288  cases 
of  smallpox  in  the  German  Empire.  Of  these,  119  were  of  foreigners. 
In  1912,  there  were  340  cases,  of  which  153  were  foreigners.  In  1913, 
there  were  only  90  cases,  of  which  39  were  in  foreigners.  During  the 
World  War,  the  large  number  of  Russian  prisoners  in  Germany  caused 
a  marked  increase  of  smallpox  in  the  civil  population.  In  the  huge 
German  army  there  were  only  two  deaths  from  smallpox  from  1874  to 
1914.  One  of  these  was  a  reservist  who  had  not  been  successfully  vacci- 
nated. Germany  has  demonstrated  how  to  utilize  Jenner's  great  dis- 
covery. 


SMALLPOX  AND  VACCINATION  35 


ISOLATION  AND  DISINFECTION 

Isolation  and  disinfection  are  only  secondary  measures  in  prevent- 
ing smallpox.     They  cannot  be  regarded  as  substitutes  for  vaccination. 

Isolation  should  be  carried  out  vrith  strictness  for  the  reason  that 
smallpox  is  one  of  the  most  contagious  of  the  communicable  infections. 
While  the  patient  should  be  isolated,  it  is  not  necessary  to  isolate  the 
hospital  by  banishing  it  to  an  inconvenient  or  undesirable  location. 
There  is,  in  fact,  no  good  reason  why  a  smallpox  hospital  should  not  be 
one  of  the  units  of  the  general  hospital  for  communicable  diseases.  In 
any  event,  there  is  no  danger  from  a  smallpox  hospital  situated  upon  a 
highroad  or  near  other  habitations,  provided  always  proper  precautions 
are  taken  to  prevent  the  spread  of  the  disease. 

The  smallpox  hospital  should  not  be  a  pesthouse,  but  should  be  as 
inviting  and  attractive  as  economic  conditions  Justify.  Smallpox  should 
not  be  treated  in  the  home.  From  the  standpoint  of  prophylaxis  the 
hospital  is  the  logical  and  best  place  to  care  for  this  and  other  communi- 
cable infections.  If  smallpox  is  treated  in  the  home,  this  should  only  be 
permitted  if  skilled  nursing  and  trained  attendants  can  be  provided. 

The  room  in  which  the  smallpox  patient  is  isolated  should  be  simply 
furnished  to  facilitate  cleanliness  and  to  permit  purification.  It  must 
be  well  screened  and  free  from  insects  and  vermin  of  all  kinds.  The 
room  should  be  well  ventilated.  This  may  be  accomplished  by  an  open 
fireplace,  in  which  case  the  contagium,  if  contained  in  the  outgoing  air, 
is  burned  in  exit. 

The  nurse  attending  a  case  of  smallpox  should  also  be  segregated, 
and  all  visiting  should  be  strictly  interdicted.  A  separate  kitchen  should 
be  provided  and  care  should  be  taken  that  the  dishes  be  scalded  and 
remnants  of  food  burned. 

Bedding,  underwear,  towels,  and  other  objects  should  not  leave  the 
sick  room  unless  they  are  first  boiled,  steamed,  or  immersed  in  a  suitable 
germicidal  solution,  such. as  bichlorid  of  mercury,  1-1,000,  or  formalin, 
10  per  cent.    Carbolic  acid  should  not  be  trusted. 

For  terminal  disinfection  cleansing  of  surfaces  with  a  germicidal 
solution  is  much  surer  than  gaseous  fumigation.  Objects  particularly 
contaminated  or  soon  to  be  used  by  others  should  be  given  a  separate  and 
special  disinfection.  Finally,  the  room  should  be  thoroughly  cleansed, 
aired,  and  sunned. 

The  patient  must  be  regarded  as  the  source  and  fountainhead  of  the 
infection,  and  measures  should  be  used  at  the  bedside  to  prevent  the 
surroundings  from  becoming  contaminated.  Cloths,  cotton,  and  other 
dressings  that  become  soiled  with  the  contents  of  the  vesicles  and 
pustules  after  they  break  should  be  burned.     The  urine  and  feces  may 


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38  DISEASES  HAVING'  SPECIAL  PEOPHYLAXIS 

be  disinfected  with  chlorinated  lime.  The  sputum  and  discharges  from 
abscesses  should  be  collected  on  cheap  cloths  and  burned.  As  a  rule, 
smallpox  patients  are  not  dismissed  from  quarantine  until  desquama- 
tion has  ceased.  This  may  be  favored  by  the  use  of  warm  baths  and  a 
generous  use  of  glycerin  soap,  also  by  anointing  the  skin  with  vaselin  or 
a  bland  oil.  Special  attention  should  be  given  to  the  hair,  which  should 
be  well  shampooed;  to  the  interdigital  spaces,  and  the  fingernails,  as  well 
as  to  all  folds  of  the  skin,  before  the  patient  is  released. 

The  management  of  a  smallpox  epidemic  is  discussed  on  page  495, 

EEFEBENCES 

Jenner^  Edward  :  "An  Inquiry  into  the  Causes  and  Effects  of  the  Yariolae 
Vaccinae,  a  Disease  Discovered  in  Some  of  the  Western  Counties  of 
England,  Particularly  Gloucestershire,  and  Known  by  the  ISTame  of 
the  Cowpox."     London,  1798, 

Brit.  Med.  Jour.,  May  23,  1896  (Jenner  Centenary  Number). 

Brit.  Med.  Jour.,  July  5,  1902  (Special  Vaccination  Number). 

Report  of  the  Royal  Commission  on  Vaccination.     1897. 

AcLAND,  T.  D. :  "Vaccinia  in  Man."  Allbutt  and  Rolleston's  "System  of 
Medicine,"  Vol.  IL  Part  I,  p.  665.     1912. 

CoPEMAN,  MoNCKTON :  "Pathology  of  Vaccinia."  Allbutt  and  Rolleston's 
"System  of  Medicine,"  Vol.  II,  Part  1,  p.  746. 

Baron,  John  :  "The  Life  of  Edward  Jenner,  with  Illustrations  of  His  Doc- 
trines and  Selections  from  His  Correspondence."  Vols.  I  and  II,  Henry 
Colburn,  London,  1838. 

Vaccination  Law  of  April  8,  1874.  German  Empire.  Published  in  English. 
P.  Paul,  Berlin,  1904. 

ScHAMBERG,  J.  E. :  "Vaccination  and  Its  Relation  to  Animal  Experimenta- 
tion."    Defense  of  Research  Pamphlet,  No.  1.     Am.  Med.  Ass'n. 

McVail,  J.  C:     "Half  a  Century  of  Smallpox  and  Vaccination."     Edin- 


burgh, 1919, 


RABIES 


Synonyms. — Hydrophobia;  Wasserscheu,  Wvt,  Tollwut  (Germ.an) ; 
Ijyssa  (Greek) ;  La  Rage  (French). 

Rabies  is  an  acute,  specific,  rapidly  fatal  paralytic  infection  com- 
municated from  a  rabid  animal  to  a  susceptible  animal,  through  a  wound 
usually  produced  by  biting.  Man  always  contracts  the  disease  from 
some  lower  animal,  usually  the  dog.  The  infective  agent  must  be  in- 
oculated into  the  tissues;  the  virus  is  harmless  when  ingested,  provided 
the  mucosa  is  intact.  The  gastric  juice  has  a  pronounced  deleterious  ef- 
fect upon  the  virus.  Rabies  may  be  regarded  as  a  wound  infection.  The 
specific  principle  is  contained  in  the  saliva  of  animals  suffering  with 
the  disease.     The  infection,  therefore,  may  be  conveyed  by  licking,  etc., 


EABTES  39 

provided  there  are  fissures  or  open  wounds  in  the  skin.  It  is  also  possible 
to  introduce  the  virus  through  autopsy  accidents  and  other  unusual  ways, 
but  commonly  it  is  introduced  tlirough  wounds  produced  by  the  teeth 
of  a  rabid  animal. 

Every  mammalian  animal  is  susceptible.  Even  birds  may  contract 
the  disease.  It  is  most  common  in  dogs,  but  it  also  occurs  frequently 
in  wolves,  jackals,  foxes,  and  hyenas,  liabies  in  cats  is  comparatively 
rare.  Cattle,  sheep,  and  goats  are  infected  relatively  in  about  the  same 
degree.  It  is  less  common  in  horses.  Swine  contract  the  disease  less 
frequently  than  other  domestic  animals.  Skunks  may  contract  the  dis- 
ease and  sometimes  transmit  it  to  man. 

Althougli  all  mammals  are  susceptible  to  rabies,  it  is  perpetuated  in 
civilized  communities  almost  exclusively  by  the  domestic  dog,  only  to  a 
small  extent  by  wild  animals  of  the  dog  family,  and  occasionally  by 
skunks,  cats,  etc. 

Eabies  exists  practically  all  over  the  world.  It  has  never  been  in 
Australia,  and  has  not  been  known  in  Denmark,  Norway  and  Sweden 
for  more  than  fifty  years.  Rabies  had  been  eradicated  from  England, 
but  was  reintroduced  during  the  World  War  by  dogs  carried  in  flying 
machines.  It  is  most  common  in  France,  Belgium,  and  Russia, 
In  France,  rabies  of  a  virulent  type  with  a  short  incubation  period  has 
spread  since  the  first  of  the  World  War.  In  the  United  States  111  hu- 
man deaths  were  reported  in  1908.  In  the  same  year  there  wer«  535 
localities  in  which  rabid  animals  were  reported;  in  1911  there  were 
1,381  localities,  and  98  deaths  in  man.  In  1890  the  United  States 
census  reported  143  deaths  in  30  states,  and  in  1900  but  23  deaths.  In 
1916,  21  deaths  were  reported  from  11  states.  In  1919,  45  deaths  were 
reported  in  the  United  States. 

Eabies  is  remarkable  on  account  of  its  high  mortality — practically 
100"  per  cent.  After  symptoms  are  pronounced  recovery  rarely,  if  ever, 
takes  place.  Joseph  Koch  (1910),  however,  describes  an  abortive  rabies. 
The  disease  is  peculiar  in  several  other  particulars,  especially  the  period 
of  incubation,  which  is  more  variable  and  more  prolonged  than  that  of 
any  other  acute  infection. 

Eabies  is  commonly  supposed  to  prevail  only  during  the  hot  months, 
but  it  is  in  fact  more  prevalent  in  cold  weather.  Exposure  to  cold  seems 
to  increase  its  virulence.  More  dog  bites  occur  from  April  to  September 
than  from  October  to  March  in  this  climate,  because  dogs  run  abroad 
more  freely  at  this  season  of  the  year. 

Period  of  Incubation. — From  the  standpoint  of  prevention  it  is  for- 
tunate that  the  period  of  incubation  of  this  disease  is  prolonged.  This 
period  varies  from  14  days  to  a  year  or  more.  Such  prolonged  periods 
of  incubation  indicate  latency.  The  average  period  is  as  follows:  Man, 
40  days  (apt  to  be  shorter  in  children) ;  dogs,  21-40  days;  horses,  28-56 


40  DISEASES  HAVIXG  SPECIAL  PEOPHYLAXIS 

days;  cows,  28-56  days;  pigs,  14-21  days;  goats  and  sheep,  21-28  days; 
birds,  14-40  days. 

The  period  of  incubation  depends  largely  upon  the  site  of  the  wound, 
the  relation  to  the  nerve,  the  amount  and  virulence  of  the  virus.  It 
requires  about  15  days,  counting  from  the  last  injection,  to  induce  an 
active  immunity  to  the  disease  by  means  of  the  Pasteur  preventive  treat- 
ment. There  is,  therefore,  usually  sufficient  time,  if  the  case  is  seen 
early,  to  prevent  the  development  of  symptoms. 

It  is  probable  that  the  prolonged  period  of  incubation  is  due  in  part 
to  the  fact  that  it  takes  time  for  the  virus  to  travel  along  the  nerves  to 
the  central  nervous  system,  and  also  to  the  fact  that  after  the  virus 
reaches  the  central  nervous  system,  it  may  remain  dormant  (latent) 
until  favorable  conditions  permit  multiplication  and  the  production  of 
toxic  effects. 

Entrance  and  Exit  of  the  Vims. — The  active  principle'  of  rabies 
occurs  principally  in  the  saliva  and  in  the  central  nervous  system.  It 
may  be  in  the  saliva  at  least  three  days  (possibly  eight)  before  the  ani- 
mal shows  symptoms  (Eoux  and  Xocard).  It  is,  therefore,  sufficient  to 
watch  a  dog  that  has  bitten  a  person  or  another  animal  for  ten  days. 
If  no  symptoms  of  rabies  appear  during  this  time  there  is  no  danger  of 
convej'ing  the  disease,  and  the  Pasteur  prophylactic  treatment  is  unneces- 
sary. 

The  virus  has  been  found  in  the  adrenals,  the  tear  glands,  the  pan- 
creas, the  vitreous  humor,  the  spermatic  fluid,  the  urine,  the  lymph,  the 
milk,  as  well  as  all  parts  of  the  central  nervous  system  and  the  peripheral 
nerves.  It  is  also  found  in  the  spinal  and  ventricular  fluids.  It  has  not 
been  demonstrated  in  the  liver,  spleen,  blood,  or  muscles. 

The  virus  enters  the  system  through  the  broken  skin  and  follows  the 
nerve  trunks  from  the  seat  of  injury  to  the  spinal  cord,  thence  to  the 
medulla  and  brain.  The  route  corresponds  to  that  of  tetanus  toxin. 
The  mode  of  invasion  of  the  virus  may  explc^in  why  pain,  throbbing, 
tingling,  numbness  and  other  nervous  disturbances  are  the  first  symp- 
toms to  occur  in  parts  of  the  body  that  have  received  the  virus.  It  also 
partly  explains  the  variable  period  of  incubation,  which  is  shorter  in 
wounds  of  the  face  than  wounds  of  the  extremities.  It  also  explains 
why  the  disease  is  more  liable  to  occur  when  the  wounds  are  in  parts 
of  the  body  with  a  rich  nerve  supply.  I  have  experimental  evidence  (un- 
published) that  indicates  that  the  virus  readily  enters  the  nerve  endings 
in  the  skin. 

iS^oguchi  -^  announces  that  he  has  succeeded  in  growing  the  virus, 
which  appears  in  cultures  as  granular  and  pleomorphic  chromatcid  bod- 
ies, some  of  which  are  surroimded  with  membranes.     Williams  -®  and 

=^Xoguchi,  Jour.  Exp.  Med..   1913,  XVII,  29. 

^Williams,  Anna  Wessel;  Jour.  A.  M.  A.,  1913,  LXI,  17,  p.  1509. 


RABIES  41 

Moon  ^^  believe  they  have  evidence  of  growtli  in  Ijrain  tissue,  having  pro- 
duced rabies  in  animals  in  the  fiftli  gont'ration  or  transfer  of  such  ''cul- 
tures.*' 

The  Relative  Danger  of  Bites. — Wolf  bites  are  most  dangerous  on 
account  of  the  savage  character  of  the  wound,  and  the  virulence  of  the 
virus.  Cat  bites  come  next,  and  then  dog  bites.  The  relative  danger  of 
bites  of  other  animals  is  as  follows:  foxes,  jackals,  horses,  asses,  cattle, 
sheep,  pig?.  There  is  no  authentic  instance  of  the  transmission  of  the 
disease  by  the  bite  of  man,  though  this  may  be  possible.  The  bites  of 
horses  and  other  herbivora  are  less  dangerous  because  their  blunt  teeth 
usually  cause  contused  wounds  without  breaking  the  skin. 

Bites  on  exposed  surfaces  are  more  dangerous  than  through  the  cloth- 
ing, because  the  saliva  is  wiped  from  the  teeth  and  little  or  none  enters 
the  wound.  Long-haired  dogs  and  sheep  often  escape  infection  for 
the  same  reason.  Bites  upon  the  face  are  most  apt  to  be  followed 
by  rabies. 

Not  every  person  bitten  by  a  mad  animal  develops  rabies.  Leblanc's 
figures  are  16.6  per  cent.  The  statistics  are  difficult  to  analyze,  and  it 
is  almost  impossible  now  to  collect'  sufficient  data.  According  to  the 
most  reliable  figures,  it  would  seem  that  rabies  develops  in  not  less  than 
one  person  in  ten  bitten  by  mad  dogs,  and  not  receiving  the  Pasteur 
treatment.  Paltauf  places  the  figures  at  6  to  9  per  cent.  From  15  to 
20  per  cent,  is  a  moderate  estimate  of  the  death  rate  for  all  persons  bit- 
ten by  rabid  animals.     8ee  also  page  49. 

Viability. — The  virus  of  rabies  in  the  spinal  cord  of  rabbits  dies  in 
about  li  days  when  dried  at  20°-22°  C.  if  protected  from  putrefaction 
and  light.  Spread  in  thin  layers,  it  dies  in  -1  or  5  days,  and  exposed  to 
the  sunlight  in  40  hours.  It  is  quite  resistant  to  putrefaction.  In  a 
decomposed  carcass  it  may  be  recovered  by  placing  some  of  the  central 
nervous  system  in  glycerin.  The  glycerin  destroys  most  of  the  con- 
taminating bacteria,  but  preserves  the  virus.  Rabic  virus  is  completely 
destroyed  at  50°  C.  in  one  hour,  and  at  60°  C.  in  30  minutes.  It  is  not 
injured  by  extreme  cold. 

Harris  found  the  virus  to  be  very  resistant  to  dryness  at  low  tem- 
peratures. Rabic  virus  in  central  nervous  tissue  is  very  resistant  to 
ordinary  germicides.  Sawtschence ^°  found  that.it  requires  from  five  to 
seven  days  to  destroy  the  fixed  virus  in  5  per  cent,  phenol,  and  that  it 
is  not  destroyed  by  0.5  per  cent,  phenol  in  20  days.  Other  filterable 
viruses,  notably  variola  and  vaccinia,  also  show  unusual  resistance  to 
phenols  and  cresols.  Semple  ^'^  found  that  the  emulsion  of  fixed  virus 
which  resists  the  action  of  1  per  cent,  phenol  at  room  temperature  for 

=»Moon,  Jour.  Infect.  Dis.,  1913.  XIII.  232. 
»>  Sawtschence,  W.,  Ann.  de  VInst.  Pasteur,  1911.  XXI,  p.  492. 
'^  Semple,  "Sci.  Mem.  by  OflBcers  of  Med.  and  San.  Depts.,"  Gov.  Ind.,  X.  S., 
No.  44. 


43  DISEASES  HAVING  SPECIAL  PKOPHYLAXIS 

several  da3^Sj  succumbs  at  24  hours  at  37°  C.  x\ccording  to  Gumming  ^^ 
1  per  cent,  phenol  does  not  destroy  the  virus  in  6  hours,  while  2  per  cent. 
solution  kills  it  in  less  than  24  hours.  On  the  other  hand,  most  of  the 
aldehj'd  compounds  are  very  active  in  destroying  the  infectivity  of  the 
fixed  virus.  A  0.5  per  cent,  solution  of  salicylaldehyd,  benzaldehyd,  or 
furfurol  destroys  the  virus  in  less  than  3  hours.  The  specific  disinfect- 
ing action  of  formaldehyd  is  shown  by  the  fact  that  the  virus  is  destroyed 
when  exposed  for  two  hours  to  0.08  per  cent,  solution.  This  indicates 
that  formalin  may  be  a  useful  substance  to  treat  dog  bites,  although 
experiments  have  shown  that  it  is  not  as  dependable  as  nitric  acid. 
Bichlorid  of  mercury,  1-1,000,  for  1  hour,  or  a .  saturated  solution  of 
iodin  in  water,  completely  destroys  the  virulence,  and  Wyrsykowski  has 
shown  that  gastric  juice  has  a  pronounced  deleterious  effect  upon  the 
virus. 

PROPHYLAXIS 

The  prevention  of  rabies  is  considered  under  three  heads:  (1) 
Treatment  of  the  wounds;  (2)  the  Pasteur  prophylactic  treatment,  and 
(3)  the  control  of  the  disease  in  dogs  by  muzzling  and  quarantine. 

The  cauterization  of  the  wound  and  the  Pasteur  prophylactic  treat- 
ment are  efficient  preventive  measures  for  the  individual,  but  they  are 
not  the  true  and  best  methods  of  controlling  and  preventing  rabies. 
The  disease  may  be  avoided,  even  exterminated,  by  an  intelligent 
system  of  muzzling  and  quarantining  of  dogs.  A  high  tax  on  dogs  and 
leashing  are  only  restrictive  measures.  In  England,  when  the  dogs  were 
muzzled,  rabies  diminished.  The  law  was  repealed,  owing  to  misplaced 
sympathy  for  the  dog,  and  rabies  promptly  increased.  The  law  was 
again  enforced,  and  in  about  two  years  the  disease  disappeared  (see  Fig. 
10).  A  strict  quarantine  of  six  months  was  maintained  against  dogs  en- 
tering England,  but  this  was  broken  by  the  war  and  rabies  reappeared 
in  England  in  1918.^^  Consistent  muzzling  of  all  dogs  for  two  years 
will  practically  exterminate  rabies.  In  Australia  there  are  few  carniv- 
orous animals,  mostly  marsupials;  there  rabies  does  not  exist,  for  it 
has  been  kept  out  owing  to  early  and  effective  quarantine  measures. 
]S[orway,  Sweden,  and  Denmark  also  obtained  good  results  and  the  same 
can  be  done  in  other  peninsular  regions. 

Prophylactic  measures  necessary  to  control  the  dog  question  are: 
the  destruction  of  ownerless  dogs ;  license  fee  and  tag  for  all  dogs ;  own- 
ers to  be  legally  responsible  for  damage  infiicted  by  their  dogs;  educa- 
tion of  the  dog-owning  public  concerning  the  spread  of  communicable 
diseases,  especially  rabies ;  compulsory  reporting  of  all  cases  or  suspected 
cases  of  rabies.     Further  special  measures   advocated   are:   muzzling; 

^^Jour.  Infect.  Dis.,  XIV,  1,  January,  1914,  p.  33. 
^Br.  Med.  Jour.,  March  22.  1919,  350,  1. 


RABIES 


43 


restraint  ^vitIl  chains,  leash,  etc.;  observation   in  quarantine,  or  killing 
of  all  animals  hitton  by  dogs;  disinfection,  etc.  ^* 

THE  LOCAL  TREATMENT  OF  THE  WOUND 

Wounds  produced  by  the  bite  of  an  animal  in  which  there  is  any 
suspicion  of  rabies  should  at  once  be  cauterized  with  "fuming"  or  strong 
nitric  acid.^'^     The  acid  is  best  applied  with  a  glass  rod  very  thoroughly 


Fig.  10. — Chart  Showing  Relation  of  Enforcement  of  Muzzling  Law  to 
Prevalence  of  Rabies  in  Great  Britain  (the  figures  in  the  cross-hatching 
indicate  the  number  of  persons  who  died  of  rabies  in  England  and  Wales. 
The  ordinates  represent  cases  in  dogs).      (Straus  and  Frothingham. ) 

to  all  the  parts  of  the  wound,  care  being  taken  that  pockets  and  recesses 
do  not  escape.  Thorough  cauterization  at  once  reduces  the  danger  of 
wound  complications,  and  experience  demonstrates  that  wounds  so 
treated  at  once  are  pu'actically  never  followed  by  rabies.  Marie  obtained 
conflicting  results  with  local  treatment  in  experimental  rabies ;  Cabot  ^^ 
obtained  the  best  results  with  nitric  acid,  and  was  able  to  save  the  lives 


**  In  addition  to  rabies,  dogs  are  responsible  for  other  infections  in  man, 
such  as  hydatids,  tapeworms  (especially  in  children),  round  worms,  tongue 
worms,  and  also  fleas  and  ticks  which  transfer  from  the  dog  to  man  and  which 
may  in  this  way  transmit  diseases  and  parasites.  In  animals,  dogs  are  re- 
sponsible for  gid  in  live  stock  and  cysticerci  in  sheep,  reindeer   and  live  stock. 

^'  Sp.  gr.  over  1.48. 

^' Medical  News,  March,  1899. 


44  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

of  91  per  cent,  of  guinea-pigs  by  cauterization  with  nitric  acid  at  the 
end  of  34  hours;  Poor  ^^  saved  45  per  cent.,  at  the  "end  of  32  hours.  In 
the  absence  of  nitric  acid,  formalin  or  the  actual  cautery  may  be  used, 
but  they  have  inferior  prophylactic  value.  Strong  germicides,  such  as 
carbolic  acid,  are  not  reliable.  Nitrate  of  silver  is  valueless.  In  any 
wound  produced  by  the  bite  of  an  animal  cauterize  with  nitric  acid  unless 
sure  that  the  animal  is  not  mad. 

Experiments  made  in  my  laboratory  indicate  that  no  substance  takes 
the  place  of  nitric  acid,  and  further  emphasizes  the  importance  of, 
cauterizing  all  portions  of  the  wound,  especially  the  edges  of  the 
skin. 

It  has  been  shown  that  the  virus  may  remain  alive  and  virulent  in 
the  scar  for  a  long  time,  and  it  has  become  a  question  whether  patients 
seen  after  the  wound  has  healed  should  not  have  the  scar  excised  and 
the  wound  cauterized  with  nitric  acid ;  this,  however,  is  not  the  practice. 

THE   PASTEUR   PROPHYLACTIC   TREATMENT 

This  method  of  prophylaxis  was  announced  December  6,  1883,  by 
Pasteur,  at  the  International  Congress  at  Copenhagen,  and  on  February 
24,  1884,  he  laid  before  the  French  Academy  the  details  of  his  experi- 
ments and  results.  The  next  year  Pasteur,  with  the  help  of  Eoux  and 
Chamberland,  worked  out  the  details  of  the  method  now  in  general  use. 

The  principle  of  the  treatment  consists  in  producing  an  active  im- 
munity by  means  of  an  attenuated  virus.  The  virus  is  attenuated  by 
drying.  The  fixed  virus  contained  in  the  spinal  cord  of  rabbits  dead 
of  hydrophobia  is  the  material  used,  for  subcutaneous  injection. 

Street  Virus  and  Fixed  Virus. — The  distinction  between  fixed  and 
street  virus  is  of  fundamental  importance  in  reference  to  the  question 
of  immunity.  Street  virus  is  obtained  from  mad  dogs  naturally  in- 
fected. When  this  virus  is  inoculated  into  a  rabbit,  it  reproduces  the 
disease  after  a  period  of  incubation  of  from  14  to  21  days  or  more. 
This  street  virus  may  then  be  conveyed  from  rabbit  to  rabbit  through  a 
number  of  transfers.  In  the  passage  from  rabbit  to  rabbit  the  virus 
becomes  more  virulent  for  rabbits.  The  period  of  incubation  is  pro- 
gressively shortened,  until  finally  the  rabbits  invariably  sicken  on  the 
sixth  or  seventh  day  and  die  on  the  ninth  or  tenth.  When  the  virus 
has  reached  this  degree  of  virulence  for  rabbits,  it  is  said  to  be  "fixed," 
for  the  reason  that  its  potency  remains  constant.  In  its  passage 
through  rabbits  the  modification  from  street  virus  to  fixed  virus  is 
gradual.  It  is  important  to  note  that  fixed  virus,  which  has  attained  a 
high  degree  of  virulence  for  rabbits,  has  lost  much  of  its  virulence  for 

^'Collected   Studies,  Research   Lab.,    Dept.    of    Health,    City   of   N.    Y.,    VI, 
1911,  p.  25. 


T^ABTES  45 

dogs,  and  seems  to  bo  aviruli'iit  fur  man  when  introduced  into  the  sub- 
cutaneous t  issue. •''^^ 

Ferran  in  1888  treated  85  persons  for  dog  bites  by  injecting  the 
fresh  fixed  virus  subcutaneously,  without  ill  effects.  Wysokowiez  in 
1902  injected  70  persons  intravenously  without  an  accident.  In  in- 
stitutes using  the  method  of  Hoyges,  many  persons  have  received  dilu- 
tions of  an  emulsion  of  the  fresh  pons  and  medulla.  Xitsch.  Proescher 
and  others  injected  large  amounts  of  fresh  fixed  virus  subcutaneously 
without  producing  symptoms.  Proescher,  in  fact,  injected  himself  with 
the  entire  brain  and  medulla  of  a  rabbit;  and  another  entire  brain  into 
a  volunteer.  Xo  ill  eifects  of  any  kind  were  noted.  The  virus  used 
was  shown  to  be  virulent  when  a  small  amount  of  it  was  introduced 
under  the  dura  of  a  rabbit.  It  is  indeed  quite  difficult  to  give  rabies 
to  animals  experimentally  by  subcutaneous  injection.  Marx  tested  the 
fresh  fixed  virus  upon  monkeys  in  large  doses,  with  negative  results. 
The  evidence  points  clearly  to  the  fact  that  the  fixed  virus  of  rabbits 
does  not  produce  rabies  in  man  when  introduced  into  the  subcutaneous 
tissue. 

Preparation  of  the  Virus. — Eabbits  are  injected  under  the  dura 
mater  with  a  few  drops  of  an  emulsion  of  fresh  fixed  virus  obtained 
from  the  pons  or  medulla  of  another  rabbit  dead  of  hydrophobia.  Strict 
aseptic  precautions  are  necessary  in  order  to  keep  out  other  infections. 
The  rabbit  should  begin  to  show  symptoms  on  the  six:th  or  seventh  day, 
and  die  on  the  ninth  or  tenth.  Usually  the  rabbit  is  not  allowed  to  die, 
but  is  chloroformed  on  the  last  day  in  order  to  avoid  terminal  infections 
and  unnecessary  suffering.  The  spinal  cord  is  removed  and  hung  in  a 
bottle  containing  potassium  hydroxid.  These  bottles  are  kept  in  the 
dark  at  a  temperature  of  23°  C.  Under  these  conditions  the  cord  grad- 
ually desiccates,  and  at  the  same  time  the  virulence  of  the  virus  di- 
minishes, until  the  fourteenth  day,  when  it  is  no  longer  infective.  This 
is  why  Pasteur  started  the  treatment  with  a  cord  fourteen  days  old. 
In  fact,  the  virus  dies  long  before  the  fourteenth  day — five-day  old  cord 
usually  fails  to  infect. 

About  one-half  a  centimeter  of  the  cord  constitutes  a  dose.     This  is 

ground  in  about  2.5  c.  c.  of  sterile  salt  solution  so  as  to  produce  a 

uniform  emulsion,  which  is  injected  into  the  subcutaneous  tissue  of  the 

abdominal  wall.     In  many  institutes  the  small  segments  cut  each  day 

from  the  drying  cord  are  placed  in  pure  glycerin.     The  virulence  of  the 

cord  in  glycerin  is  not  altered  for  at  least  30  days,  if  kept  in  the  dark 

and  at  15°  C.     This  method,  introduced  by  Calmette^^  in  1891,  based 

upon  observation  made  by  Roux  in  1887,^°  is  very  convenient,  especially 

=^N.  Y.  Med.  Jour.,  Oct.  9,  1909,  also  Arch,  of  Int.  Med.,  Sept.,  1911, 
VIII,  3,  p.  353. 

^Ann.  de  VInsi.  Pasteur,  Paris,  1801,  Vol.  V,  p.  633. 
*^  Ann.  de  VInst.  Pasteur,  Paris,  1887,  Vol.  I,  p.  87. 


46 


DISEASES  HAVING  SPECIAL  PROPHYLAXIS 


where  comparatively  few  patients  are  treated.  Glycerin  has  the  added 
advantage  of  destroying  infections  due  to  non-spore-hearing  hacteria 
that  may  be  present. 

As  a  further  precaution,  bacteriologic  examinations  are  made  of  parts 
of  the  spinal  cord  in  order  to  insure  the  absence  of  bacteria,  and  the 
rabbit  is  carefully  autopsied  as  a  guarantee  that  no  other  disease  is 
present. 

The  Scheme  of  Treatment. — The  scheme  of  treatment  advocated  by 
Pasteur  and  still  used  at  I'lnstitut  Pasteur  in  Paris  and  many  other 
places  is  shown  in  the  following  table: 

PASTEUR  PROPHYLACTIC  TREATMENT — RECOMMENDED  BY  PASTEUR 


Mild  Treatment 

Intensive  Treatment 

Amount  of  In- 

Amount of  In- 

Day 

Age  of 

jected   Emulsion 

Day 

Age  of 

jected   Emulsion 

of 

the  Dried 

1-cm.  of  Cord  to 

of 

the  Dried 

1  cm.  of  Cord  to 

Treatment 

Cord 

5  c.  c.  Salt  Solu- 
tion 

Treatment 

Cord 

5  c.  c.  Salt  Solu- 
tion 

ri4  Days 

3  c.  c. 

1 

f 14  Days 
113 

3  c.   c. 

1 

J  13 

3 

3 

1  12 

3 

111 

3 

flO 

3 

2 

ill 

3 
3 

2 

{f 

3 
3 
3 

3 

{'I 

3 
3 

3 

f     6 
\     6 

2 
2 

4 

i' 

3 
3 

4 

5 

2 

5 

it 

2 
2 

5 

5 

2 

6 

5 

2 

6 

4 

2 

7 

5 

2 

7 

3 

1 

8 

4 

2 

8 

4 

2 

9 

3 

1 

9 

3 

1 

10 

5 

2 

10 

5 

2 

11 

5 

2 

11 

5 

2 

12 

4 

2 

12 

4 

2 

13 

4 

2 

13 

4 

2 

14 

3 

2 

14 

3 

2 

15 

3 

2 

15 

3 

2 

16 

5 

2 

16 

5 

2 

17 

4 

2 

17 

4 

2 

18 

3 

2 

18 

3 

2 

19 

5 

2 

20 

4 

2 

21 

3 

2 

Some  Pasteur  institutes  now  use  a  modified  treatment,  starting  with 
an  8-day  instead  of  a  14-day-old  cord,  which  is  exemplified  in  the  scheme 
used  at  the  Hygienic  Laboratory,  Public  Health  Service.  See  table  on 
the  following  page. 

The  tendency  is  to  hasten  the  immunity  by  using  only  the  intensive 
treatment  for  all  cases,  also  to  start  with  fresher  cord,  some  using  4- 
day-old  cord  for  the  initial  injection.  Intensive  treatment  should  al- 
ways be  given  for  wounds  of  the  face,  head,  hand  and  other  exposed 
parts  of  the  body ;  for  multiple  wounds ;  severe  wounds ;  or  for  wolf,  fox, 
cat  and  skunk  bites. 


RABIES 

PASTEUR    PROPHYLACTIC   TREATMENT— HYGIENIC   LABORATORY 
WASHINGTON,  D.    C. 


47 


Amount  of  Emulsion   1   c.  c.  of  Cord  to  5  c.  c.  Salt 

Day 

Age  of  the  Dried 
Cord 

Solution 

Adult 

5    to    10    Years 

1    to    5   Years 

1 

6—6* 

2.5  c.  c. 

2.5  c.   c. 

2.5  c.   c. 

2 

5 — 5* 

2.5 

2.5 

2.5 

3 

4 — 4* 

2.5 

2.5 

2.5 

4 

3 

2.5 

2.5 

2.0 

5 

3 

2.5 

2.5 

2.0 

fi 

2 

2.5 

2.0 

1.5 

7 

2 

2.5 

2.5 

2.0 

8' 

1 

2.5 

1.5 

1.0 

9 

5 

2.5 

2.5 

2.5 

10 

4 

2.5 

2.5 

2.5 

11 

4 

2.5 

2.5 

2.5 

12 

3 

2.5 

2.5 

2.0 

13 

3 

2.5 

2.5 

2.0 

14 

2 

2.5 

2.5 

2.0 

15 

2 

2.5 

2.5 

2.0 

16 

4 

2.5 

2.5 

2.5 

17 

3 

2.5 

2.5 

2.5 

18 

2 

2.5 

2.5 

2.0 

19 

3 

2.5 

2.5 

2.5 

20 

2 

2.5 

2.5 

2.5 

21 

X 

2.5 

2.5 

2.5 

*  Double  dose. 

The  scheme  of  Pasteur  has  been  further  modified  in  various  ways, 
depending  upon  the  method  used  to  attenuate  the  virus.  Thus  Pasteur 
attenuated  the  virus  by  drying;  Babes  by  heating;  Frantzer  by  tlie  use 
of  bile;  Tizzoni  and  Cattani  attenuated  the  virus  in  gastric  juice.  Hog- 
yes  used  fresh  material  in  a  diluted  suspension;  Ferran  fresh  material 
and  in  increasing  doses.  Gumming  altered  the  virus  by  dialysis.  Har- 
ris dried  the  fresh  virus  at  low  temperature,  which  is  used  in  diluted  sus- 
pension. Other  methods  have  been  used  to  attenuate  the  virus,  such  as 
glycerin,  carbolic  acid,  mechanical  disintegration,  and,  lastly,  antirabic 
serum.  Ferran  in  Barcelona,  Proescher  in  Pittsburgh,  and  others  in- 
ject patients  with  the  unaltered,  fresh,  fixed  virus.  The  advantages  of 
using  the  virus  as  fresh  and  strong  as  possible  are  that  an  active  im- 
munity is  produced  more  quickly,  and  this  is  of  considerable  importance 
in  wounds  of  the  face;  also  in  wolf  and  cat  bites,  which  frequently  have 
a  short  period  of  incubation.  Further,  fewer  injections  of  the  fresh 
virus  are  necessary  to  produce  an  immunity,  and  this  shortens  and  sim- 
plifies the  treatment. 

Harris  *^  has  shown  that  rabic  material  may  be  completely  desiccated 
without  destruction  of  virulence,  provided  the  dehydration  takes  place 
at  a  low  temperature.  The  lower  the  temperature  the  greater  will  be  the 
amount  of  virulence  preserved.  Virus  so  desiccated  contains  per  weight 
as  much  infectivity  as  the  fresh  virus.  The  virus  thus  dried  is  so  stable 
that  it  may  be  standardized,  permitting  an  accuracy  of  dosage  hitherto 
impossible.  The  unit  is  the  smallest  amount  which,  Avhen  injected  in- 
tracerebrally   into    a   full-grown   rabbit,   will   produce   paresis   on   the 

*^Jour.  of  Infect.  Dis.,  May,  1912,  X,  3,  pp.  369-377. 


48  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

seventh  day.     For  slight  wounds  Harris  gives  seven  injections,  but  for 
severe  injuries  he  gives  two  injections  a  day  for  twelve  to  fourteen  days. 

Treatment  at  a  distance  from  a  Pasteur  institute  is  now  practical  by 
sending  a  piece  of  cord  in  glycerin;  or  the  emulsion  in  glycerin,  in  a 
thermos  bottle;  or  the  dry  material  in  accordance  with  Harris'  method. 

Care  During  the  Treatment. — During  the  treatment  the  patient 
may  go  about  his  usual  business.  It  is  not  necessary  to  stay  in  bed. 
The  patient  should,  however,  avoid  fatigue,  cold,  emotional  stress, 
trauma,  and  alcohol.  It  has  been  shown  that  these  are  important  pre- 
disposing factors  to  the  disease.  It  was  found  that  customs'  officers  re- 
turning to  the  Siberian  borders  after  prophylactic  treatment  for  wolf 
bites  showed  an  unusual  mortality,  which  seemed  to  de  due  to  exposure 
to  cold.  The  disease  has  been  observed  to  be  brought  on  after  a  cold 
bath,  falling  into  the  water,  and  similar  depressing  influences. 

Complications  of  the  Treatment. — The  Pasteur  prophylactic  treat- 
ment may  be  complicated,  by  (1)  local  reactions  or  (2).  paralysis. 

Local  reactions  at  the  site  of  the  wound  are)  usually  trivial.  Abscesses 
almost  never  occur.  The  local  reactions  consist  of  redness  and  indura- 
tion. It  is  not  necessarily  the  last  injection,  but  rather  the  site  of  some 
previous  injection  that  flares  up,  but  soon  subsides  without  further 
trouble.  This  occurrence  increases  with  the  progress  of  the  treatment; 
it  is  most  frequent  in  the  second  week.  As  the  treatment  involves  the 
introduction  of  a  large  quantity  of  foreign  proteins  into  the  body,  it  is 
probable  that  these  reactions  represent  a  phase  of  hypersusceptibility. 
See  Anaphylaxis. 

Paralysis. — Paralysis  occurs  occasionally  and  may  be  fatal.  This 
complication  seems  to  be  a  mild  or  modified  type  of  rabies,  but  there 
is  doubt  concerning  its  cause.  There  is  evidence  that  it  may  be  due  to 
infection  with  the  fixed  virus  or  possibly  to  toxin — or  both.  Serious 
paralysis  is  a  rare  complication;  it  doubtless  occurs  in  mild  form  more 
often  than  is  known.  It  affects  adults  chiefly,  young  children  almost 
never.  Simon  collected  data  up  to  and  including  1911,  showing  the 
occurrences  of  100  instances  of  paralysis  among  317,774  persons  treated. 
In  this  series  there  were  19  deaths.  The  incidence  of  paralysis  seems 
to  vary  with  different  methods  of  antirabic  treatment.*^ 

In  a  case  treated  at  the  Hygienic  Laboratory  the  paralysis  came  on 
18  days  after  treatment,  and  was  transient.  H.  E.  Hasseltine  *^  reports 
two  cases  of  paralysis  following  antirabic  treatment,  with  one  death.  The 
New  York  Pasteur  Institute  reports  a  death  from  "ascending  paralysis," 
which  came  on  four  days  after  the  treatment.  W.  A.  Jones  **  reported 
two  cases  with  recovery.     In  1905  Eemlinger,  head  of  the  Constanti- 

**The  subject  is  brought  up  to  date  in  Fiedler's  article  in  the  Journal  of 
the  Amerioan  Medical  Assooiation,  June  3,  1916,  LXVI,  p.  23. 

«  Public  Health  Report,  July  30,  1915,  Vol.  XXX,  No.  31,  p.  2227. 
'*Jour.  A.  M,  A.,  Nov.  13,  1909,  p.  1626. 


KABIES  49 

nople  Institute  for  Eabies,  reported  40  cases  of  paralysis;  Babes  had  8 
cases  of  paralysis  (all  mild)  in  (),5"i5  treatments;  Miiller  found  16  cases 
in  the  literature,  and  had  two  of  his  own ;  Panpoukis,  three  cases ;  Jones, 
2.  Mejio  *''  reported  19,800  cases  treated  in  the  Pasteur  institute,  Buenos 
Aires,  of  whom  24  developed  paralysis,  with  4  deaths.  One  instance  was 
a  child  of  six,  apparently  healthy  a  month  after  the  Pasteur  treatment. 
He  then  had  a  fall  from  a  hammock;  the  next  day  his  legs  were  para- 
lyzed; the  paralysis  proved  of  the  ascending  type,  fatal  in  two  weeks. 

The  Immunity. — Duration. — The  immunity  appears  two  weeks  after 
the  treatment  and  lasts  a  varying  period  of  time,  depending  upon  the 
individual — at  least  for  several  years.  In  this  respect  it  does  not  differ 
from  other  instances  of  acquired  immunity.  The  Pasteur  prophylactic 
may  be  repeated  in  persons  bitten  a  second  time.  The  lower  animals 
may  also  be  protected.  The  fact  that  the  immunity  appears  on  the 
fifteenth  day  after  the  last  treatment  was  discovered  by  Pasteur  as  a  re- 
sult of  animal  experimentation.  The  statistics  of  the  Pasteur  Institute, 
giving  the  mortality  from  rabies  in  persons  following  the  prophylactic 
treatment,  exclude  instances  in  which  the  disease  develops  within  fifteen 
days  after  the  last  prophylactic  injection. 

Nature. — The  nature  of  the  immunity  is  not  clear.  It  certainly 
is  not  due  to  an  antitoxin.  Immune  bodies  are  demonstrable  in  the 
blood  twenty  days  after  the  last  injection.  The  activity  of  the  virus 
can  be  neutralized  by  mixing  it  in  vitro  with  the  blood  serum  of  an  im- 
munized animal.  This  neutralization  is  generally  considered  to  be  mi- 
crobicidal or  lytic  in  nature. 

Degree. — The  degree  of  the  immunity  also  varies,  as  is  evidenced 
by  the  fact  that  a  certain  small  percentage  of  the  persons  treated  die 
of  rabies. 

The  Results  of  the  Treatment. — Statistics  giving  the  results  of  the 
treatment  are  somewhat  difficult  to  analyze,  as  many  factors  are  unob- 
tainable. Patients  should  be  kept  under  observation  at  least  a  year. 
Exceptional  cases  occur  one  year  following  exposure.  Cases  that  occur 
within  fifteen  days  after  the  treatment  are  excluded  from  the  French 
statistics,  for  reasons  that  have  already  been  stated.  The  figures  on 
this  basis  show  a  mortality  of  less  than  0.5  per  cent.  Better  results 
are  being  obtained  from  year  to  year. 

The  table  on  the  following  page  gives  the  general  results  at  ITnstitut 
Pasteur,  Paris,  since  beginning  the  treatment. 

When  we  compare  these  figures  with  the  fact  that  from  6  to  10  per 
cent,  and  sometimes  16.6  per  cent,  of  all  persons  bitten  by  rabid  dogs 
die  of  rabies,  the  prophylactic  value  of  the  Pasteur  treatment  is  evident. 

Faber  found  27  deaths  out  of  339  persons  bitten  by  mad  dogs;  Kur- 
rimoto,  17  per  cent,  in  Nagasaki;  Babes,  15  per  cent,  of  995  in  Hun- 

"  Semana  Medica,  Buenos  Aires^  XXIV,  No.  I,  p.  10. 


50 


DISEASES  HAVING  SPECIAL  PROPHYLAXIS 


RESULTS   OF   TREATMENT  AT    L'INSTITUT   PASTEUR,    PARIS 


Year 

Persons 
treated 

Deaths 

Mortality 

Year 

Persons 
treated 

Deaths 

Mortality 

1886 

2,671 

25 

0.94% 

1903 

628 

2 

0.32% 

1887 

1,770 

14 

0.79 

1904 

755 

3 

0.39 

1888 

1,622 

9 

0.55 

1905 

727 

3 

0.41 

1889 

1,830 

7 

0.38 

1906 

772 

1 

0.13 

1890 

1,540 

5 

0.32 

1907 

786 

3 

0.38. 

1891 

1,559 

4 

0.25 

1908 

524 

1 

0.19 

1892 

1,790 

4 

0.22 

1909 

467 

1 

0.21 

1893 

1,648 

6 

0.36 

1910 

401 

0 

0.00 

1894 

1,387 

7 

0.50 

1911 

341 

1 

0.29 

1895 

1,520 

5 

0.38 

1912 

395 

0 

0.00 

1896 

1,308 

4 

0.30 

1913 

330 

0 

0.00 

1897 

1,521 

6 

0.39 

1914 

373 

0 

0.00 

1898 

1,465 

3 

0.20 

1915 

654 

1 

0.15 

1899 

1,614 

4 

0.25 

1916" 

1,388 

3 

0.21 

1900 

1,420 

4 

0.28 

1917 

1.543 

4 

0.26 

1901 

1,321 

5 

0.38' 

1918 

1,803 

3 

0.16 

1902 

1,005 

2 

0.18 

1919 

1,813 

" 

0.16 

gary;  Horsley's  figures  are  15  per  cent.  Some  series  of  cases  give  a 
much  higher  mortality.  Thus,  of  855  persons  bitten  by  mad  dogs,  col- 
lected by  Tardieu,  Thamehayn,  and  Bouley,  399  ended  in  death,  or  46.6 
per  cent.  In  another  series  of  cases  given  by  Bouley,  out  of  266  per- 
sons bitten  by  mad  dogs,  152  died  of  hydrophobia.  But  of  these  120 
were  bitten  on  the  face  and  hands,  the  greater  danger  of  which  has 
been  mentioned.  The  mortality  resulting  from  bites  of  wolves  is  placed 
by  Babes  at  from  60  to  80  per  cent. 

Contraindications, — There  are  no  known  contraindications  to  the 
treatment.  All  ages  and  conditions  should  be  treated  if  exposed.  Ap- 
parently no  harm  is  done  pregnant  women.  I  have  injected  patients 
having  malaria  without  trouble  following.  The  treatment  may  be  con- 
tinued in  patients  having  colds,  fevers,  and  other  ailments  without  no- 
ticeable harm. 

When  to  Give  the  Pasteur  Prophylactic. — It  is  sometimes  difficult  to 
decide  whether  the  Pasteur  prophylactic  treatment  should  or  should  not 
be  given.  Treatment  causes  sufficient  personal  inconvenience,  not  to 
speak  of  the  danger  (however  slight)  of  paralysis,  to  avoid  advising  it 
if  unnecessary.  In  many  cases  it  is  impossible  to  discover  whether  the 
dog  that  inflicted  the  bite  is  mad  or  not.  The  rule  in  cases  of  doubtful 
exposure  is  to  advise  the  treatment. 

Persons  who  apply  for  treatment  of  dogbites  fall  into  one  of  the  five 
following  categories  with  reference  to  the  Pasteur  prophylactic : 

( 1 )  The  dog  is  mad  or  shows  suspicious  symptoms :  In  this  case, 
begin  treatment  at  once. 

(2)  The  dog  is  not  mad:  Observe  it  carefully  for  ten  days,  and  if 
no  symptoms  develop,  there  is  no  danger  of  rabies  in  the  person  bitten. 
The  treatment  is  therefore  unnecessary.  (The  dog  may  nevertheless 
develop  rabies  after  ten  days  and  if  it  has  been  bitten  by  another  dog 
should  be  kept  in  quarantine  for  six  months.) 


EABIES  51 

(3)  The  dog  is  not  identified:  This  is  a  common  occurrence,  es- 
pecially with  children.  The  rule  in  such  cases  is  to  advise  the  Pasteur 
prophylactic  treatment,  except  in  places  known  to  be  free  of  rabies. 

(4)  Exposure  to  saliva:  Persons  not  infrequently  apply  for  ad- 
vice giving  the  following  history :  They  have  not  been  bitten,  but  they 
have  been  licked  on  the  hands  and  face  by  a  dog  that  subsequently  was 
discovered  to  have  the  disease.  Persons  are  sometimes  similarly  exposed 
by  washing  the  mouth  of  a  rabid  horse.  In  tliese  cases  the  important 
question  is  whether  there  were  fissures  or  abrasions  in  the  skin  at  the 
time.  There  may  be  little  wounds  in  the  skin  not  evident  to  the  naked 
eye.  It  is  possible  to  infect  animals  by  rubbing  the  virus  on  the  shaved 
skin.  The  rule  is  therefore  to  advise  the  protection  which  the  treat- 
ment affords  in  persons  thus  exposed. 

(5)  In  psychoneurotic  patients  with  a  distressing  phobia  of  rabies, 
it  may  atford  comfort  to  give  a  mild  course  of  treatment  as  much  for  its 
psychotherapeutic  effect  as  for  specific  immunity. 

The  Dog. — In  all  cases  it  is  important  to  know  whether  the  dog  is 
mad  or  not.  If  the  dog  can  be  found  and  kept  under  observation  for  10 
days  and  no  symptoms  appear,  the  Pasteur  treatment  is  not  necessary. 
Animals  killed  early  in  the  course  of  rahies  may  fail  to  show  the  mi- 
croscopic evidence  of  the  disease,  thus  causing  an  indefinite  delay  in 
diagnosis  awaiting  inoculation  tests.  Dogs  that  have  bitten  persons 
should  not  be  summarily  killed,  but  should  be  apprehended  and  turned 
over  to  the  proper  authority;  if  killed,  the  head  should  be  sent  to  the 
nearest  diagnostic  laboratory.  Should  the  dog  develop  symptoms,  the 
question  of  diagnosis  is  all-important. 

Diagnosis  of  Rabies  in  Dogs. — The  diagnosis  of  rabies  in  dogs  may  be 
made  in  four  ways:  (1)  from  the  symptoms;  (2)  from  the  presence 
of  Negri  bodies  in  the  central  nervous  system;  (3)  from  the  lesions  in 
the- peripheral  ganglia,  and  (4)  by  animal  inoculations. 

1.  The  symptoms  may  be  very  suggestive,  but  a  diagnosis  must  al- 
ways rest  upon  the  pathological  lesions  and  the  inoculation  tests.  The 
course  of  the  disease  may  be  divided  into  three  stages:  (a)  a  premoni- 
tory stage,  (b)  a  stage  of  excitement,  and  (c)  a  paralytic  stage.  The 
first  two  stages  may  be  absent  or  transient.  All  rabid  animals  invariably 
become  paralyzed  before  they  die.  In  dogs  the  first  symptom  consists 
solely  in  a  change  in  the  disposition  of  the  animal.  He  is  easily  excited, 
but  does  not  show  a  tendency  to  bite.  Soon  the  restlessness  becomes 
more  marked,  and  the  animal  may  become  furious  and  even  show  signs 
of  delirium.  The  dog  does  not  fear  water,  as  is  commonly  supposed, 
but  rushes  about  attacking  every  object  in  his  way.  Dogs  suffering  from 
furious  rabies  have  a  tendency  to  run  long  distances  (25  miles  or  more), 
often  biting  and  inoculating  large  numbers-  of  other  animals  and  persons 
en  route.    Very  soon  paralysis  sets  in,  commencing  in  the  hind  legs,  and 


52  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

finally  becomes  general.  The  course  of  the  disease  is  always  rapid, 
averaging  from  4  to  5  days,  rarely  exceeding  10  days.  When  the  stage 
of  excitement  is  brief  or  absent,  the  disease  is  known  as  dumb  rabies. 

2.  There  is  a  difiEerence  of  opinion  concerning  the  significance  of 
the  Negri  bodies  {Neurorrhydes  hydrophobiae) ,  which,  however,  are  very 
constant  in  rabies  and  peculiar  to  it.  If  Negri  bodies  are  found  in  the 
dog,  the  Pasteur  treatment  should  be  started  at  once.  The  absence  of 
Negri  bodies,  however,  does  not  necessarily  mean  the  absence  of  rabies. 
These  bodies  are  sometimes  difficult  to  find,  or  may  not  be  present  in  the 
parts  of  the  central  nervous  system  which  are  examined.  Negri  bodies 
are  found  especially  in  the  horn  of  Ammon  and  the  cerebellum;  they 
are  1  to  23  micra  in  diameter;  usually  round  or  oval;  strongly  eosino- 
philic; occur  within  and  without  the  nerve  cells;  and  sometimes  con- 
tain a  nucleus  (?).  Owing  to  their  resemblance  to  red  blood  cells,  the 
finding  of  Negri  bodies  iHthin  the  cells  is  the  safest  criterion.  The 
diagnosis  may  thus  be  established  in  about  90  per  cent,  of  cases. 

Negri  bodies  for  diagnostic  purposes  are  best  demonstrated  by  im- 
pression preparations  of  Amnion's  horn  and  cerebellum,  stained  accord- 
ing to  Van  Giesen  as  recommended  by  Frothingham  or  stained  by 
Bond's  modification  of  the  Mann  stain.  Impression  preparations  are 
made  by  gently  pressing  a  microscopic  slide  upon  the  cut  surface  of 
Ammon's  horn  and  the  cerebellum  and  lifting  with  a  quick  movement. 
Care  should  be  taken  to  obtain  thin  uniform  impressions  because  thick 
impressions  do  not  show  differential  staining  for  Negri  bodies.  Pieces 
of  the  Ammon's  horn  and  the  cerebellum  selected  for  impressions  should 
be  from  four  to  six  millimeters  thick.  Three  or  four  impressions  to  a 
single  slide  should  be  made  from  each  piece  of  the  Ammon's  horn  and 
ccreljellum.  Four  or  five  pieces  of  each  Ammon's  horn  and  the  same 
number  from  the  cerebellum  are  sufficient.  The  impression  preparations 
obtained  in  this  way  show  the  characteristic  arrangement  of  the  cells  of 
the  hippocampus  and  of  the  cerebellum  and  rarely  fail  to  contain  the 
Negri  bodies  in  infected  material.  When  the  brain  is  badly  mutilated  or 
decomposed,  impressions  taken  from  any  of  the  available  material 
containing  gray  matter  will  frequently  show  the  Negri  bodies  if 
infected. 

To  stain  impression  preparations  as  recommended  by  Frothingham 
the  following  slightly  modified  procedure  is  given:  (1)  Fix  before  the 
impression  dries  in  methyl  alcohol  for  five  minutes;  (2)  stain  at  room 
temperature  with  Van  Giesen,  while  still  moist  with  alcohol,  for  eight 
to  ten  minutes;  (3)  wash  thirty  seconds  with  running  tap  water;  (4) 
blot  with  filter  paper.  The  Van  Giesen  stain  is  made  as  follows: 
Tap  water  20  c.  c.  to  50  c.  c;  saturated  alcoholic  fuchsin  (f.  Bac. 
Grubler)  1  drop;  saturated  aqueous  solution  methylene  blue  (f.  Bac. 
Koch  Grubler)   one  to  ten  drops.     The  amount  of  tap  water  and  the 


RABIES  53 

amount  of  methylene  bine  required  for  irood  differentiation  vary  with 
different  stock  solutions  of  the  stains.  This  stain  changes  little  in  three 
to  four  days. 

To  stain  by  Bond's  mudilication  of  the  Mann  stain  proceed  as  fol- 
lows: (1)  Fix  before  the  impression  dries  in  methyl  alcohol  five  to  six 
minutes;  (2)  wash  thirty  seconds  with  running  tap  water;  (3)  stain 
for  four  to  five  minutes  Avith  a  mixture  consisting  of  1.0  c.  c.  of  1  per 
cent,  aqueous  eosin  (Eosin  W.  gelbl.  Grubler),  0.7  c.  c.  to  1.0  e.  c.  of  1 
per  cent,  aqueous  methyl  blue  (Grubler)  and  6.0  c.  c.  of  distilled  water; 
(4)  wash  with  running  tap  water  for  thirty  seconds;  (5)  blot  with 
filter  paper;  (6)  dehydrate  with  absolute  alcohol;  (7)  clear  with  a 
mixture  consisting  of  one  part  of  xylol  and  two  parts  of  aniline  oil;  (8) 
Avash  with  xylol:  (9)  mount  in  balsam.  The  ^lann  stain  should  be 
freshly  prepared  each  time  it  is  used.  In  practice  it  is  better  to  stain 
by  both  methods  because  each  has  its  advantages  and  disadvantages.  The 
Mann's  stain  gives  definite  Xegri  bodies  but  the  differential  staining  be- 
tween the  red  blood  corpuscles  and  ]Sregri  bodies  is  not  always  clear.  "With 
the  Frothingham  method  Xegri  bodies  can  hardly  be  mistaken  for 
anything  else  but  the  stain  itself  may  be  capricious  in  action  and  shows 
relatively  fewer  Xegri  bodies. 

3.  The  lesions  of  Van  Gehuchten  and  Xelis,  described  in  1900,  are 
the  most  characteristic  anatomical  changes.  These  lesions  are  found 
late  in  the  disease  in  the  peripheral  ganglia  of  the  cerebrospinal  and 
SA'mpathetic  systems,  especially  in  the  plexiform  ganglia  of  the  pneumo- 
gastric  nerve,  and  the  Gasserian  ganglia.  The  normal  nerve  cells  of 
these  ganglia  lie  in  a  capsule  lined  with  a  single  layer  of  endothelial 
cells.  In  rabies  these  endothelial  cells  proliferate  and  the  nerve  cells 
may  be  partly  or  entirely  destroyed  and  replaced  by  diverse  cells  as- 
sociated with  chronic  inflammatory  processes.  In  addition,  lymphatic 
infiltration  also  occurs  about  the  sheaths  surrounding  the  individual 
nerve  cells.  Either  the  proliferative  or  infiltrative  changes  may  pre- 
dominate. In  order  to  find  these  lesions,  it  is  necessary  to  fix  the  ganglia 
in  Zenker's  fluid  and  to  stain  the  sections  by  the  eosin-methylene  blue 
method.  This  method  of  diagnosis  is  available  in  only  a  small  per- 
centage of  cases. 

4.  The  final  diagnosis  of  rabies  rests  upon  animal  experimentation. 
A  small  quantity  of  an  emulsion  of  the  medulla  or  pons  of  the  suspected 
animal  is  placed  under  the  dura  mater  of  a  rabbit  or  guinea-pig.  The 
diagnosis  by  this  method,  however,  requires  so  much  time  (on  account 
of  the  long  period  of  incubation  of  the  disease)  that  it  is  of  no  practical 
value  in  deciding  whether  or  not  the  Pasteur  prophylactic  treatment 
should  be  given,  but  in  any  critical  case  the  positive  evidence  furnished 
by  animal  experimentation  is  incontrovertible. 

If  the  inoculated  rabbit  shows  no  symptoms  in  one  month,  and  Xegri 


54  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

bodies  were  not  seen  in  the  specimen,  then  a  negative  diagnosis  may  be 
given,  although  it  is  customary  to  observe  the  animal  for  six  months. 

REFERHNCES 

Pasteur,  Chamberland,  Koux  and  Thuillier:  "Sur  la  Rage,"  Compi. 
rend,  de  I'Acad.  de  Sci.,  1881,  92,  p.  1555. 

Pasteur,  Chamberland  and  Roux:  "iSTouvelle  Communication  sur  la 
Rage,"  Compt  rend,  de  VAcad.  de  Sci.,  1884,  98,  p.  457;  "Sur  la  Rage," 
Compt.  rend,  de  VAcad.  de  Sci.,  1884,  98,  p.  1229. 

Pasteur:  "Methode  pour  Prevenir  la  Rage  apres  Morsure,"  Compt.  rend, 
de  I'Acad.  de  Sci.,  1885,  101,  p.  765;  "Resultats  de  TApplication  de  la 
Methode  pour  Prevenir  la  Rage  apres  Morsure,"  Compt.  rend,  de  I'Acad. 
de  Sci.,  1886,  102,  p.  459;  "Note  Complementaire  sur  les  Resultats  de 
I'Application  de  la  Methode  de  Prophylaxie  de  la  Rage  apres  Morsure," 
Compt.  rend,  de  I'Acad.  de  Sci.,  1886,  102,  p.  835;  "Xouvelle  Communi- 
cation sur  la  Rage,"  Compt.  rend,  de  I'Acad.  de  Sci.,  1886,  103,  p.  777; 
"Lettre  sur  la  Rage,"  Ann.  de  I'Inst.  Pasteur,  1887,  1,  p.  1;  "Sur  la 
Methode  de  Prophylaxie  de  la  Rage  apres  Morsure,"  Compt.  rend,  de 
I'Acad.  de  Sci.,  1889,  108,  p.  1228. 

Babes,  Victor:  "Traite  de  la  Rage."  Paris,  Bailliere  et  Fils,  1912.  A 
comprehensive  monograph.  Contains  a  good  historical  account  of  the 
story  of  Pasteur's  discovery,  with  original  references. 

Stimsox,  a.  M.  :  "Facts  and  Problems  of  Rabies."  Hygienic  Laboratory 
Bulletin  No.  65,  June,  1910.  Contains  a  selected  bibliography.  More 
comprehensive  bibliographies  will  be  found  in : 

Heller:    Schutzimpfung  gegen  Lyssa,  1906. 

Hogyes:     "Lyssa"  in  Nothnagels  Spez.  Path.  u.  Therap.,  Wien,  1897. 

Marie  :    L' etude  experimentale  de  la  rage.    Encyclop.  scient.,  1909. 

Marx,  E.  :  Kolle  u.  Wassermanns  Handh.  d.  path.  Mikroorg.,  1904,  4,  Bd.,  2. 
TL,  1264. 

VENEREAL  DISEASES*^ 

As  a  danger  to  the  public  health,  as  a  peril  to  the  family,  and  as  a 
menace  to  the  vitality,  health,  and  physical  progress  of  the  race,  the 
venereal  diseases  are  justly  regarded  as  the  greatest  of  modern  plagues, 
and  their  prophylaxis  the  most  pressing  problem  of  preventive  medicine 
that  confronts  us  at  the  present  day. 

Xo  serious  attempt  was  made  by  the  sanitary  authorities  of  any 
of  our  great  cities  to  deal  with  this  problem  until  Xew  York  City  in 

*'  Objection  has  been  made  to  the  stigma  implied  in  the  term  venereal  dis- 
eases, for  these  infections  are  not  always  transmitted  in  venery  and  are  often 
contracted  innocently.  Syphilis  and  gonorrhea,  however,  are  unlike  other  com- 
municable diseases  in  that  they  do  involve  a  moral  principle.  Gonorrhea  or 
syphilis  contracted  innocently  is  usually  only  one  remove  from  promiscuity. 

Only  one  venereal  disease  among  the  lower  animals  is  known, — dourine,  a 
syphilis  of  horses  caused  by  a  trypanosome. 


VENEREAL  DISEASES  55 

1012  *''  determined  to  treat  the  venereal  diseases  as  any  other  higlily 
communieablo  and  prevcntabU^  infection,  dealin<i  purely  with  tiie  sani- 
tary features  of  the  problem  from  a  public  health  standpoint,  ignoring 
the  social  and  moral  phases.  The  opposition  to  such  activity  is  slowly 
being  broken  down.  Progress  against  the  venereal  diseases  is  a  repeti- 
tion of  the  warfare  along  other  lines  of  sanitation  and  hygiene.  It  is 
the  history  of  a  continuous  struggle  carried  on  in  the  name  of  law, 
religion,  personal  rights,  or  expediency.  Although  the  dilliculties  in 
this  case  are  much  greater  thrn  in  any  other  group  of  diseases,  an 
intelligent  and  persistent  campaign  must  end  in  a  long-delayed  success. 

Biggs  states  that  in  1912  at  least  800,000  people,  or  more  than  one- 
fifth  of  the  adult  population  of  New  York  City,  have,  or  have  had,  some 
venereal  disease,  and  that  in  a  large  percentage  of  these  persons  the 
disease  is  still  active.  The  number  of  new  infections  occurring  each 
year  probably  exceeds  that  of  all  other  notifiable  diseases  combined. 
In  view  of  such  figures  the  magnitude  and  the  importance  of  the  problem 
of  administrative  control,  as  applied  to  these  diseases,  become  clearly 
apparent. 

The  venereal  diseases  are  a  constant  menace  to  the  clean  living  public 
as  well  as  to  the  licentious.  The  history  of  preventive  medicine  can 
present  no  greater  tragedy  than  the  home  invaded  by  syphilis  or 
gonorrhea. 

There  are  three  venereal  diseases :  syphilis,  gonorrhea,  and  chancroid. 
In  order  to  have  a  clear  understanding  of  the  problems  of  venereal 
prophylaxis  it  is  necessary  to  have  a  knowledge  of  the  essential  features 
of  these  preventable  infections.  Two  of  them,  syphilis  and  gonorrhea, 
are  of  great  importance,  because  they  are  very  prevalent  and  because 
they  are  very  serious  infections  with  grave  consequences.  Gonorrhea 
is  the  great  preventer,  syphilis  the  great  destroyer  of  life. 

SYPHILIS 

Syphilis  is  a  specific  infection  caused  by  the  Spirochcefa  pallida.^ 
It  is  acquired  by  direct  contact  with  infected  persons,  by  inoculation 
with  infected  things,  and  by  congenital  transmission.  Syphilis  runs  a 
chronic  course  with  lesions  and  symptoms  of  extraordinary  diversity. 
The  initial  lesion  or  chancre  forms  on  the  skin  or  mucous  membrane 
at  the  site  of  entrance  of  the  spirochetes.  The  period  of  incubation  is 
never  less  than  10  days,  with  a  maximum  of  90  days.  In  the  majority 
of  cases,  the  chancre  appears  between  the  14th  and  40th  days. 

There  are  many  striking  things  about  syphilis,  but  nothing  so  strik- 
ing as  its  persistence  in  spite  of  knowledge  complete  enough  to  stamp 

"  Resolutions  adopted  by  the  Board  of  Health.  February  20th. 
"°.4itn  known  as  Treponema  pallidum. 


56  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

it  out  and  in  view  of  the  popular  dread  in  which  the  disease  is  held. 
It  is  preventable,  even  curable — yet  scarcely  another  disease  equals  it 
in  the  extent  and  intensity  of  its  ravages.  It  is  the  great  canker  of 
humanity. 

Syphilis  is  a  good  illustration  of  the  fact  that  it  is  much  more  diffi- 
cult to  control  a  disease  transmitted  directly  from  man  to  man  than  a 
disease  transmitted  by  an  intermediate  host,  or  one  in  which  the  virus 
is  transferred  through  our  environment.  We  have  a  certain  amount  of 
control  over  our  surroundings,  and  we  have  dominion  over  the  lower 
animals,  but  the  control  of  man  requires  the  consent  of  the  governed. 

Civilization  and  syphilization  have  been  close  companions,  but  syph- 
ilis is  now  less  prevalent  among  civilized  than  uncivilized  peoples — this 
is  promising.  Civilization,  however,  should  not  be  content  until  it  has 
controlled  syphilis  as  effectively  as  it  has  some  other  preventable  infec- 
tions.   The  effort  to  do  so,  at  least,  must  be  persistent  and  sincere. 

From  the  economic  side  syphilis  is  not  a  serious  disease  in  its  pri- 
mary and  secondary  stages;  that  is,  persons  with  syphilis  during  the 
early  stages  are  usually  not  ill  enough  to  cease  work.*^  Acutely  fatal 
cases,  such  as  frequently  occurred  in  the  sixteenth  century,  are  now 
rare;  in  other  words,  the  disease  has  lost  much  of  its  early  virulence. 
It  is  the  late  manifestations,  or  the  so-called  parasyphilitic  lesions,  as 
well  as  the  inherited  consequences  of  the  disease,  that  play  havoc.  About 
one-fifth  of  all  the  insane  in  our  asylums  are  cases  of  general  paresis; 
90  per  cent,  of  these  give  the  Wassermann  reaction.  Syphilis,  alcohol, 
and  heredity  fill  our  insane  asylums,  jails  and  almshouses. 

The  consequences  of  syphilis  are  often  more  severe  upon  the  off- 
spring than  upon  the  syphilitic  parent.  The  infection  itself,  or  various 
defects,  especially  of  the  nervous  system,  resulting  from  the  conse- 
quences of  syphilis,  may  be  transmitted  from  parent  to  child,  often  with 
fatal  results.  When  death  does  not  ensue  the  results  may  be  still  more 
tragic. 

The  health  officer  should  regard  syphilis  just  as  he  does  the  acute 
febrile  exanthematous  diseases.  Because  syphilis  runs  a  slow  and  often 
chronic  course  with  mild  constitutional  symptoms  during  its  early  stages, 
it  is  often  placed  in  a  class  by  itself.  This  is  a  mistake.  Syphilis  has 
its  period  of  incubation,  eruption,  and  decline,  just  as  measles  and 
smallpox  have. 

Historical. — There  is  an  accurate  historical  record  of  the  startling 
spread  of  syphilis  over  the  known  world  in  a  few  years  after  1495,  and 
from  that  time  it  has  everywhere  been  endemic.  No  similar  record  exists 
of  the  sudden  establishment  of  any  other  great  disease  among  the  larger 
part  of  the  earth's  inhabitants.  Evidence,  however,  points  to  the  severe 
character  of  the  disease  during  this  early  epidemic,  the  cases  often  run- 

*9  But  it  is  most  communicable  during  this  time. 


VENEREAL  DISEASES  57 

ning  an  acute,  febrile  course,  accompanied  by  symptoms  of  such  severitv 
as  are  now  seen  only  occasionally.  Syphilis  was  unknown  before  the 
year  1493.  It  is  said  to  have  been  brought  by  the  crew  of  Columbus, 
on  his  first  voyage  from  Espanola,  or  Hayti.'^"  Some  of  the  returning 
(Tcw  acconiitanied  Charles  YIII  of  France  in  the  autumn  of  1  }!>1  with 
the  army,  35,000  strong,  which  invaded  Italy  for  the  conquest  of  Xaples. 
The  epidemic  began  in  Italy  at  this  time,  and  the  disease  spread  quickly 
over  Europe  with  the  scattering  of  the  troops.  At  first  the  French  called 
it  the  Xcajjolitan  disease,  and  the  Italians  called  it  the  French  pox,  or 
Morbus  Gallicus.  The  name  of  the  disease  was  taken  from  a  popular 
poem  written  by  Fracastor  in  1530  entitled,  "Syphilis  sive  Morbus  Gal- 
licus," in  Avhich  the  symptoms  are  clearly  described  in  the  principal 
pastoral  character — Syphilis. 

In  1903,  Metclmikoff  and  Eoux  ^^  transmitted  the  disease  to  lower 
animals  and  demonstrated  the  prophylactic  value  of  calomel  inunctions, 
and  also  opened  up  a  rich  field  of  animal  experimentation.  In  1905, 
Schaudinn  ^-  discovered  the  cause  and  thus  made  diagnosis  certain.  In 
190G,  Wassermann,  Xeisser  and  Bruck  ^^  introduced  the  indirect  method 
of  diagnosis  by  serum  reaction.  In  1910,  Ehrlich,^*  after  many  years  of 
experiment,  gave  to  the  world  salvarsan,  a  specific,  synthetic  spirocheti- 
cide.  In  1911,  Xoguchi  °^  cultivated  Spirochceia  pallida  outside  of  the 
body  and  prepared  luetin.  In  1913,  Xoguchi  ^^  demonstrated  the 
spirochetes  in  the  brain  of  paretics  and  in  the  cord  of  a  tabetic.  This  un- 
paralleled group  of  achievements,  all  the  result  of  scientific  work  in 
laboratories,  in  10  short  years  threw  light  upon  the  cause,  mode  of  trans- 
mission, patholog}%  treatment  and  prevention  of  the  disease. 

Prevalence. — The  percentage  of  syphilitics  in  the  population  at 
large  is  difficult  to  determine.  It  is  commonly  estimated  at  about  8 
per  cent.  The  amount  of  infection  in  certain  groups  is  given  by  Tedder 
as  follows :  Prostitutes,  50  to  100  per  cent. ;  tuberculous  in  institutions, 
20  to  30  per  cent. ;  ^^  sick  children  in  hospitals,  2  to  10  per  cent. ;  men- 
tally backward  and  idiots,  20  to  40  per  cent.;  criminals,  20  to  40  per 
cent.;  presumabh'  healthy  men  of  the  class  that  enlist  in  the  regular 
army,  20  per  cent. :  this  group  represents  unskilled  labor  and  a  certain 
percentage  of  the  tradesmen.     Among  men  of  better  families  the  per- 

»/.  A.  M.  A.,  June  12,  1915,  LXVI.  24.  p.  1962. 

^^Ann.  de  VInst.  Pasteur,  1903,  p.  809. 

".Ir6.  a.  d.  k.  iJsndhtsamte,  1905,  XXII.  p.  527. 

"Deutsch.  med.   ^ychnschr.,    1906,  XXXII,  p.   745. 

^  Dw  experimentelle  Chemotherapie  der  ,^pirillosen,  1910,  Julius  Springer, 
Berlin. 

''''Jour.  Exp.  Med.,  1911,  99,  p.  557. 

"Jour.  Exp.  Med.,  1913,  XVII,  p.  232. 

"  The  prevalence  of  syphilis  among  the  tuberculous  in  this  country  has 
been  variously  placed  by  different  investigators  on  the  basis  of  a  clinical 
examination  or  a  positive  Wassermann,  or  both.  Some  of  these  are  as  follows: 
Vedder,  23.2  per  cent.;  Snow  and  Cooper,  20  per  cent.;  Petroff,  21. S  per  cent.; 
Lyons,  9.2  per  cent.j  Jones,  29  per  cent. 


58  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

centage  varies  from  2  to  10  per  cent.,  depending  upon  age,  marital  con- 
dition and  other  factors.  Among  young  women  in  the  community,  the 
percentage  of  syphilitic  infections  fluctuates  between  3  and  20  per  cent., 
depending  upon  age,  marital  condition,  education  and  social  status.  As 
among  men,  the  proportion  of  infections  increases  as  we  descend  in  the 
social  scale.  It  is  estimated  that  the  rates  for  the  colored  race  are  at 
least  double  those  for  the  white  race.     See  also  page  73. 

Stages  of  the  Disease. — Syphilis  is  divided  into  four  stages  which 
are  not  always  well  defined  in  time  or  sequence. 

The  chancre. — The  primary  stage  consists  of  the  chancre  which 
forms  at  the  site  of  the  initial  infection.  The  regional  lymph  node 
becomes  enlarged  and  hard.  The  typical  Hunterian  chancre  is  an 
indurated  and  undulated  ulcer  in  the  skin  or  mucous  membrane,  and  ap- 
pears about  three  weeks  (not  less  than  ten  days)  after  the  receipt  of  the 
infection.  It  is  usually  single  and  painless,  but  frequently  is  atypical, 
and  may  be  but  a  trifling  lesion.  In  the  absence  of  a  careful  daily  in- 
spection, it  may  exist  many  days  before  it  is  detected,  or  even  escape 
notice  altogether. 

The  chancre  contains  many  spirochetes  which  may  readily  be  seen 
with  the  dark  field  illumination.  This  is  the  best  method  of  early 
diagnosis..  The  Wassermann  reaction  usually  does  not  become  positive 
until  from  two  to  six  weeks  after  the  appearance  of  the  chancre.  It  is 
important  to  examine  every  sore  on  the  genitalia  for  spirochetes,  for  the 
initial  lesion  of  syphilis  often  resembles  a  chancroid,  sometimes  only  a 
gimple  abrasion.    Mixed  infections  are  frequent. 

The  secondary  stage  is  determined  by  a  general  invasion  of  spirochetes 
throughout  the  system,  and  is  characterized  by  involvement  of  the 
lymph  nodes,  eruptions  upon  the  skin  and  mucous  membranes,  fever, 
anemia,  and  other  indications  of  a  generalized  infection. 

The  third  stage  is  characterized  by  a  localized  granulomatous  growth 
known  as  a  gumma.  Gummata  may  appear  in  almost  any  tissue  or 
organ  of  the  body. 

A  fourth  stage,  consisting  of  inflammatory  and  degenerative  lesions 
of  the  heart,  blood  vessels  and  central  nervous  system,  is  often  added 
to  the  picture,  and  occurs  long  years  after  the  primary  sore.  This  stage, 
formerly  regarded  as  sequelae  or  parasyphilitic  phenomena,  is  now 
known  to  be  associated  with  spirochetes,  and  should  be  classed  as  a  stage 
of  the  disease.  This  is  the  most  serious  and  disabling  stage  of  the 
disease  and  is  a  frequent  cause  of  insanity  or  premature  death.  Examples 
of  the  chief  manifestations  of  the  late  stage  of  syphilis  are  locomotor 
ataxia  and  dementia  paralytica,  also  arteriosclerosis,  aneurism,  cere- 
brospinal syphilis,  etc.  The  prevention  of  these  serious  conditions  de- 
pends upon  early  recognition  of  the  chancre,  followed  by  prompt  and 
thorough  treatment. 


VENEBEAL  DISEASES  69 

Fatality. — Syphilis  is  the  chief  cause  of  dcatli  in  early  ailult  life 
in  persons  otlicrwise  hale  and  hearty. 

If  it  be  remembered  that  syphilis  is  the  real  cause  of  dealli  in  all 
cases  of  general  paresis,  locomotor  ataxia,  and  aortic  aneurysm,  in  many 
cases  of  apoplexy,  and  is  a  contributory  cause  of  death  in  a  host  of 
other  conditions,  including  many  cases  of  pulmonary  tuberculosis,  the 
real  influence  of  syphilis  on  the  mortality  rate  begins  to  be  suspected. 
Osier  some  time  ago  made  the  statement  that  "of  the  killing  diseases, 
syphilis  comes  third  or  fourth."  But  recently  from  an  analysis  of  the 
TJegistrar  General's  statistics  for  1915,  he  estimates  the  actual  deaths 
from  syphilis  in  England  and  Wales  at  about  60,000,  thus  moving  syphilis 
to  the  top  of  the  list.  Leredde  estimates  that  s}'philis  probably  kills 
25,000  persons  each  year  in  France. 

According  to  Lenz,^'^  in  the  large  cities,  25  per  cent,  of  syphilitics  die 
as  the  result  of  endarteritis  (angina  pectoris,  aortic  insufficiency, 
aneurysm),  while  3  or  4  per  cent,  of  syphilitics  die  from  general  paraly- 
sis, 1  or  2  per  cent,  from  tabes  and  at  least  10  per  cent,  more  as  the  result 
of  syphilitic  lesions  of  the  brain,  liver  and  kidneys.  Almost  half  of  all 
syphilitics  eventually  succumb  as  the  result  of  their  infection.  Syphilis 
is  therefore  the  greatest  cause  of  premature  death  of  men  in  large 
cities. 

Mattanschek  and  Pilcz  ^^  found  that  of  413-i  officers  of  the  Austrian 
Army  who  contracted  syphilis  between  the  years  1800-1900,  on  January 
1,  1912:  198  had  general  paralysis;  113  had  locomotor  ataxia;  132  had 
cerebrospinal  syphilis;  80  suffered  from  different  psychoses;  17  died  of 
aneurj'sm;  147  died  of  tuberculosis;  20  died  with  syphilis  designated 
as  the  cause;  101  developed  myocarditis  and  arteriosclerosis,  86  of 
whom  died  from  this  condition. 

Diag'nosis. — Early  diagnosis  and  prompt  treatment  are  the  most 
practical  and  promising  measures  to  control  syphilis  (page  85).  The 
clinical  symptoms  are  often  atypical  and  elusive;  reliance  on  laboratory 
tests  is  therefore  imperative. 

Darlc  field  illumination  should  be  applied  as  a  routine  to  every  genital 
sore,  by  an  expert.  A  single  negative  finding  is  not  conclusive,  and. 
should  be  repeated  daily  for  several  days.  No  local  antiseptic  should  be 
applied  until  the  diagnosis  is  established.  One  application  of  a  spiroche- 
ticide,  such  as  silver  nitrate,  mercury,  copper  sulphate,  iodin  or  iodoform, 
is  often  sufficient  to  cause  the  disappearance  of  the  spirochetes  from 
the  surface  of  the  sore. 

The  Wassermann  reaction  becomes  positive  only  after  a  general  in- 
vasion of  the  spirochetes  takes  place.     At  the  time  of  the  first  appear- 

"  Ueher  die  Haufigkeit  der  syphilitischen  Sklerose  der  Aorta  relatw  zur 
geicehnlichen  Athero-sklerose  und  zur  Syphilis  iiberhaupt,  Med.  Klinik,  1013, 
IX,  955. 

''Med.  Klinik,  1913,  IX,  1544;  also  Berl.  Klin.  Wchnschr..  1908,  XLV,  1213. 


60  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

ance  of  the  chancre  this  reaction  is  invariably  negative.  It  appears  by 
the  tenth  day  in  about  30  per  cent,  of  cases,  and  is  positive  in  96  per 
cent,  of  all  cases  by  the  40th  day.  The  Wassermann  reaction  therefore 
cannot  be  depended  upon  for  early  diagnosis^  but  soon  becomes  the  most 
reliable  laboratory  test.  It  (see  also  p.  65)  should  be  remembered,  how- 
ever, that  in  a  small  percentage  of  syphilitics,  the  Wassermann  reaction 
remains  negative,  while  on  the  other  hand  it  may  become  positive  in 
other  infections,  such  as  yaws,  and  sometimes  in  tuberculosis,  malaria, 
pneumonia,  scarlet  fever,  and  especially  in  diseases  associated  with  de- 
ranged metabolism  of  the  liver.  We  must  be  cautious  in  drawing  con- 
clusions from  positive  Wassermanns  in  other  diseases,  for  it  is  often 
difficult  to  rule  out  syphilis. 

The  hietin  test  is  an  anaphylactic  reaction  depending  upon  sensitiza- 
tion of  the  skin.  It  does  not  always  appear,  and  then  late  in  the 
disease.  It  is  more  useful  in  prognosis  and  as  a  guide  to  treatment  than 
in  diagnosis. 

Methods  of  Transmission. — Syphilis  is  transmitted  directly,  in- 
directly, and  congenitally. 

In  a  large  majority  of  all  cases  of  syphilis,  the  infection  is  trans- 
mitted during  sexual  approach  and  usually  as  a  consequence  of  adulter- 
ous relations.  It  is,  therefore,  spoken  of  as  a  venereal  disease;  many 
cases,  however,  are  contracted  out  of  venery.  These  innocent  infections 
are  more  common  than  is  ordinarily  supposed.  The  spirochete  is  an 
animated  corkscrew  and  can  probably  penetrate  the  unbroken  mucous 
membrane  and  perhaps  the  skin,  although  a  fissure  or  slight  abrasion  is 
the  site  of  most  chancres. 

Marital  Syphilis. — The  subject  is  of  great  interest  and  importance 
because  marital  syphilis  is  so  frequent,  and  because  the  individual  so 
infected  is  an  innocent  victim  of  the  disease,  and  usually  remains  ignorant 
of  the  infection,  and  therefore  receives  little  or  no  treatment.  The 
transmission  of  syphilis  from  wife  to  husband  is  comparatively  rare. 
On  the  other  hand,  the  transmission  of  disease  from  husband  to  wife  is 
comparatively  common.  M.  Dechambre  says,  "Syphilis  is  divided  among 
husband  and  wife  like  the  daily  bread." 

Extragenital  Chancres. — Extragenital  chancres  constitute  from  5  to 
10  per  cent,  of  the  total  infections  with  syphilis.  Metchnikoff  reports 
that  a  great  number  of  cases  of  non-venereal  syphilis  occurs  among  chil- 
dren in  Eussia,  where  peasants  live  huddled  together  and  in  ignorance. 
Genital  syphilis  is  not  necessarily  due  to  immorality,  since  it  frequently 
results  from  marital  relations,  and  has  occasionally  followed  the  rite 
of  circumcision.  Extragenital  chancres  are  usually  acquired  innocently 
but  may  be  the  result  of  improper  practices.  It  is  particularly  desirable 
to  make  this  distinction  from  the  public  health  standpoint,  as  the 
measures  taken  to  prevent  syphilis  resulting  from  immorality  and  syphilis 


VENEREAL  DISEASES  61 

acquired  accidentally  are  naturally  quite  different.  Innocent  syphilis, 
however,  is  generally  the  result  i)y  one  or  two  removes  of  syphilis  ac- 
quired by  promiscuity. 

Buikley,*"'"  Munchheimer,  and  Eournicr  "^^  have  coHocteil  from  the 
literature  20,000  cases  of  extragenital  chancre ;  Scheuer  ^-  has  analyzed 
14,590  of  these  in  regard  to  location :  3880  occurred  on  the  lips,  con- 
tracted mainly  by  kissing;  ::^14-i  on  the  arm,  caused  by  the  old- 
fashioned  arm-to-arm  vaccination;  1569  occurred  on  the  breast,  mainly 
of  healthy  wet  nurses  from  syphilitic  infants;  1104  on  the  tonsils;  897 
on  fingers  and  hands,  chiefly  of  physicians,  nurses  and  midwives;  753 
were  caused  by  circumcision,  181  by  cupping,  and  109  by  tattooing. 

Kissing. — It  is  difficult  to  treat  this  subject  seriously,  and  yet  it  must 
be  considered  as  the  most  important  single  method  by  which  accidental 
syphilitic  infection  is  transmitted.  When  the  public  understands  that 
not  only  syphilis,  but  also  pneumonia,  influenza,  common  colds,  sore 
throats,  measles,  scarlet  fever,  whooping  cough,  diphtheria,  and  many 
other  infections  may  be  transmitted  through  kissing,  the  practice  will 
become  automatically  reduced  to  normal  and  proper  limits.  The  danger 
from  kissing  is  great  when  there  are  mucous  patches  or  other  open, 
lesions  upon  the  mucous  membrane  of  the  mouth.  The  kissing  party 
reported  by  Schamberg  ®^  has  become  classic :  Eight  individuals  acquired 
chancres  of  the  lip  from  kissing  a  young  man  who  also  had  a  chancre  of 
the  lip.  The  percentage  of  infection  was  very  high — eight  were  infected, 
only  five  or  six  escaped. 

Indirect  Transmission. — The  list  of  articles  that  have  conveyed  the 
contagium  by  indirect  transmission  is  comprehensive  and  includes  towels, 
clothing,  razors,  handkerchiefs,  surgical  and  dental  instruments,  pipes, 
et  cetera ;  a  considerable  number  of  infections  have  been  traced  to  barber 
shops,  drinking  glasses,  and  minor  operations. 
'    Congenital  and  hereditary  transmission  of  syphilis,  see  p.  645. 

Infectiousness  of  Lesions  and  Tissues. — The  chancre  is  highly  in- 
fectious from  its  first  appearance  until  it  is  completely  healed.  Hence 
the  importance  of  early  diagnosis  and  prompt  treatment. 

All  secondary  lesions  are  potentially  infectious  because  spirochetes 
have  been  demonstrated  in  all  of  them.  The  mucous  patch  is  the  sec- 
ondary lesion  most  commonly  responsible  for  the  transmission  of  the 
disease.  Like  the  chancre,  it  fairly  teems  with  spirochetes,  it  is  com- 
paratively painless,  and  occurring  on  the  mouth  or  genitalia  it  occupies 
the  two  regions  of  the  body  most  commonly  brought  into  close  and 
intimate  contact  with  persons  of  the  opposite  sex.     The  vast  majority  of 

^Syphilis  in   the  Innocent.     Bailey  and  Fairchild,  Xew  York,   1894,  p.   197. 
'^  Les  Chancres  Extragenitaux.  Paris,  1897. 

^  Die  i<yphilis  der  Unschuldigen,  Berlin,  1910,  Urban  and  Schwarzen- 
berg. 

'^J.  A.  M.  A.,  1911,  LVII,  p.  783. 


62  DISEASES  HAYING  SPECIAL  PROPHYLAXIS 

infections  are  acquired  from  syphilitics  in  the  primary  or  early  secondary 
stages  of  the  disease.  Nevertheless,  we  must  regard  any  uncured 
syphilitic  as  a  possible  source  of  infection.  The  secondary  stage  with 
its  endless  lesions  may  last  for  29  years. 

Tertiary  lesions  are  infectious,  although  it  was  thought  for  many 
years  that  they  were  not.  Practically,  cases  of  infection  from  tertiary 
lesions  are  comparatively  rare  and  only  occur  from  late  eruptions  of 
the  skin  and  superficial  gummatous  ulcerations. 

The  infectiousness  of  the  hlood  has  been  demonstrated  in  all  stages 
of  syphilis,  but  the  danger  from  this  source  is  slight.  An  exception  to 
this  statement  is  to  be  noted  in  the  case  of  surgeons,  physicians,  nurses, 
dentists  and  midwives,  among  whom  syphilis  is  the  great  occupational 
disease. 

The  milh  of  a  syphilitic  woman  must  be  regarded  as  infectious,  since 
it  is  well  known  that  a  syphilitic  wet  nurse  without  lesions  will  almost 
surely  infect  a  healthy  child ;  the  spirochetes  therefore  appear  to  be  trans- 
mitted in  the  milk. 

Spermatic  fluid. — Warthin's  findings  *^*  demonstrate  that  the  seminal 
fluid  from  many  secondary  cases  is  infectious,  and  we  may  assume  that 
the  seminal  fluid  from  tertiary  cases  may  be  infectious  in  the  presence 
of  a  suitable  lesion  in  the  testicles,  and  this  is  confirmed  by  clinical 
experience,  which  indicates  that  some  cases  of  syphilis  appear  to  be 
transmitted  in  this  way. 

Spinal  fluid  is  infectious  in  many  cases  in  which  the  central  nervous 
system  is  involved.  The  sputum,  sweat  and  urine  are  generally  believed 
not  to  be  infectious,  except  in  the  presence  of  discharging  lesions. 

For  public  health  purposes,  a  person  suffering  from  syphilis  is  con- 
sidered to  be  in  an  infective  stage  so  long  as  he  shows  any  symptom 
or  lesion  of  primary  or  secondary  syphilis,  or  any  discharging  lesion  of 
the  tertiary  stage.  „,,,.      v,  ,' 

Viability. — The  spirochete  of  syphilis  is  a  frail  organism,  yet  it 
may  live  long  enough  on  towels,  glasses,  razors,  dental  instruments, 
pipes,  and  other  objects  to  command  hygienic  respect.  Thus,  Zinsser 
and  Hopkins  ^^  found  that  pure  cultures  lived  IIV2  hours  on  a  moist 
towel.  Dried  on  covered  slips,  the  spirochete  failed  to  grow  after  one 
hour.  Bronfenbrenner  and  Noguchi  ^"  found  that  the  viability  of  the 
spirochete  is  markedly  diminished  by  lack  of  nutritive  substances,  pres- 
ence of  oxygen,  effect  of  light,  and  the  toxic  effect  of  sodium  chlorid. 
Gastou  and  Comandon  ^''  recovered  living  and  active  spirochetes  from 
drinking  glasses  up  to  half  an  hour  after  they  were  deposited  on  the 
glass. 

«Aw.  Journ.  Med.  Bci.,  1916,  CLII,  p.  508. 

^J.  A.  M.  A.,  LXII,  23,  June  6,  1914. 

"'Jour.  Phar.  and  Exp.  Therap.,  March,  IV,  4,  pp.  251-362. 

"'Bull,  de  la  80c.  Franc,  de  Dermat.  et  Syph.,  1908,  XIX,  292. 


VENEREAL  DISEASES  63 

Hertmanni  ***  found  that  the  si)iro('hete  lost  its  motility  as  soon  as 
(l^^•ing  occurred.  Ncisscr '''■'  also  dctcrniiiuMl  tliat  Ihc  virus  Troni  syphilit- 
ics  that  produced  syi)hilis  when  inoculated  iido  monkeys  al)solutely  lost 
its  power  to  transmit  infection  as  soon  as  the  fluid  which  contained  the 
organism  was  dried.  We  may  therefore  regard  it  as  demonstrated  that 
any  material  that  has  dried  has  lost  its  power  to  transmit  the  infection. 
These  facts  are  in  accordance  with  clinical  experience,  which  indicates 
that  infection  by  indirect  contact  is  tli rough  a  hricf  jx-riod  of  time 
or  a  short  interval  of  space.  Any  object  recently  soiled  or  still  moist 
with  infectious  secretions  from  a  syphilitic  must  be  regarded  as  a  possible 
source  of  infection. 

The  Spiroeha'ta  jKiUida  may  retain  its  life  and  infectious  properties 
for  long  periods  in  tissues  that  are  excised  from  the  body  and  in  various 
bodily  fluids  when  kept  in  the  laboratory  under  suitable  conditions  or  in 
cultures. 

Immunity. — There  is  no  natural  immunity  to  syphilis  and  probably 
no  true  cure  wdthout  specific  treatment.  The  disease  is  much  milder 
now  than  it  w^as  in  the  16th  century.  This  indicates  that  either  the 
spirochete  has  lost  some  of  its  earlier  malignancy,  or  the  human  race 
has  become  more  resistant  through  syphilization.  A  similar  phenomenon 
is  seen  in  malaria  and  some  other  infections  caused  by  animal  parasites. 
Syphilis  confers  no  definite  immunity.  Second  infections  may  take 
place  after  cure.  Chancres  are  not  auto-inoculable,  but  it  is  now  known 
that  a  second  chancre  can  be  produced  if  the  inoculation  from  the  first 
chancre  is  made  soon  after  its  appearance.  In  other  words,  super-infec- 
tion cannot  take  place  when  the  disease  is  once  established.  This  in- 
dicates a  kind  of  "immunity"  while  the  living  spirochetes  are  in  the 
body.  The  same  sort  of  resistance  is  found  in  leishmaniasis  and  other 
parasites  belonging  to  the  animal  kingdom.  Inability  to  produce  super- 
infections is  also  seen  in  active  tuberculosis  and  some  other  diseases. 

The  Wassermann  reaction  is  not  an  index  of  immunity.  If  the 
luetin  test  becomes  negative  after  having  been  positive,  it  is  an  indication 
that  resistance  has  disappeared  and  such  persons  are  susceptible  to 
reinfection. 

The  hereditary  and  congenital  transmission  of  syphilis  is  discussed 
on  page  645 

Syphilis  and  Life  Insurance. — Syphilis  lowers  the  standard  of  health 
and  paves  the  way  for  other  diseases.  Whatever  the  etiological  relation- 
ship may  be,  it  is  definitely  known  that  syphilitics  are  prone  to  die  early 
from  affections  of  the  heart  and  vessels,  general  paresis,  diseases  of  the 
central  nervous  system  (locomotor  ataxia),  chronic  nephritis,  arterio- 
sclerosis, aneurysm,  apoplexy,  etc.     The  actuaries  of  all  life  insurance 

'^Ztschr.,  1909,  XVI,  633. 

"Ar6.  a.  d.  k.  Gsndhtsamte,  1911,  XXXVII. 


64  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

companies  know  that  the  morbidity  and  mortality  rates  among  syphi- 
litics  are  very  much  higher  than  those  of  any  other  class  of  individuals 
of  the  community  who  enjoy  apparent  good  health  at  the  time 
of  examination.  The  actuaries  of  a  German  life  insurance  company 
estimate  that  the  mortality  of  luetics  is  130  to  100  for  normal  in- 
dividuals, and  in  the  36-  to  50-year  period  the  average  mortality  in 
syphilitics  is  doubled. 

Most  insurance  companies  refuse  to  accept  syphilitics  at  all.  Some 
companies  require  extra  premiums  to  compensate  for  the  extra  risks. 
A  few  companies  will  accept  exceptionally  favorable  cases  who  have 
had  a  thorough  course  of  treatment  and  who  have  shown  no  symptoms 
for  from  3  to  5  years,  but  under  these  circumstances  only  special  policies 
are  issued  which  do  not  keep  the  applicant  on  the  companies'  books  after 
55  years  of  age. 

Marriage  and  Syphilis. — Fournier  thought  that,  with  fe^^  exceptions, 
syphilis  constitutes  only  a  temporary  bar  to  marriage.  As  a  result  of 
his  experience,  he  concluded,  in  1880,  that  marriage  should  be  pro- 
hibited to  every  man  having  syphilis  which  was  transmissible,  and 
that  it  ought  to  be  permitted  in  men  in  whom  the  disease  was  in  such 
a  condition  as  not  to  be  transmissible.  It  is  impossible,  however,  to  in- 
sure any  guarantee  of  safety  whatever  except  in  the  presence  of  a 
definitely  established  cure. 

Finger's  rules  as  modified  by  Vedder  ""^  are  as  follows : 

1.  A  mild  normal  course  of  the  disease. 

2.  An  efficient  course  of  treatment  with  both  salvarsan  and  mercury 
in  accordance  with  the  best  practice  in  the  treatment  of  syphilis. 

3.  An  interval  of  at  least  four  full  years  between  infection  and 
marriage. 

4.  An  interval  of  three  years  from  the  last  syphilitic  manifestation 
to  marriage  with  careful  observation  to  determine  the  existence  of 
symptoms. 

5.  A  negative  Wassermann  reaction  just  before  marriage,  best  con- 
firmed by  a  test  at  a  second  laboratory  to  insure  accuracy. 

Osier  states  that  the  family  physician  should  insist  upon  the  necessity 
of  two  full  years  elapsing  between  the  date  of  infection  and  the  con- 
tracHng  of  marriage.  This,  it  should  be  borne  in  mind,  is  the  earliest 
possible  limit,  and  marriage  should  be  allowed  only  if  the  treatment 
has  been  thorough  and  if  at  least  a  year  has  passed  without  any  mani- 
festation of  the  disease. 

It  is  clear  that  the  great  burden  of  responsibility  must  be  borne 
by  the  family  physician.  It  is  his  duty  to  warn  the  patient  that  mar- 
riage may  not  be  absolutely  safe,  that  he  must  watch  for  small  erosions 
on  the   genitalia   or  in  the  mouth,   that  may   affect  his   wife.      The 

'"Vedder's  "Syphilis  and  Public  Health,"  p.  209. 


VENEREAL  DISEASES  65 

family  physician  should  know  tho  facts  so  that  he  can  watch  huth  wife 
and  children,  and  alford  })roni))t  treatment  shuuhl  it  Ijecunie  necessary. 

It  is  not  practical  to  prevent  the  marriage  of  many  syphilities  by 
law,  although  legislation  making  syphilis  a  bar  to  marriage  has  been 
enacted  by  several  states.'^  Such  laws  in  practice  enable  the  state  to 
step  in  after  the  fact,  and  while  of  interest  in  divorce  proceedings,  must 
be  regarded  as  of  limited  public  healtli  usefulness. 

The  family,  is  the  sanitary  unit,  and  it  is  of  fundamental  importance 
to  public  and  private  health  to  protect  the  sanctity  of  the  home.  There 
is  also  truth  in  Hutchinson's "'-  contention  "that  counsels  of  perfection 
are  often  not  trustworthy  in  practice." 

The  Wassermann  Reaction  and  Marriage. — Assent  to  matrimony 
should  be  withheld  from  individuals  with  a  positive  "Wassermann  test. 
On  the  other  hand  Keyes  '^^  concludes  that  a  negative  Wassermann  is  not 
sufficient  evidence  of  the  cure  or  absence  of  syphilis.  Again,  a  positive 
Wassermann,  unsupported  by  clinical  evidence,  may  not  be  sufficient 
evidence  of  the  presence  of  syphilis,  and  therefore  in  itself  does  not 
prohibit  matrimony.  A  fixed,  positive  Wassermann  in  the  later  years  of 
the  disease  does  not  inevitably  point  to  the  prospect  of  grave  lesions.  A 
negative  Wassermann  after  salvarsan,  in  the  first  year  of  the  disease,  does 
not  mean  that  the  patient  is  cured,  or  that  lesions  will  not  reappear, 
because  the  reaction  may  again  become  positive.  The  return  of  chancre, 
glands,  eruption  and  positive  Wassermann  reaction,  a  few  months  after 
control  of  the  disease  by  salvarsan  in  its  first  few  weeks,  does  not  prove 
reinfection. 

Standard  of  Cure. — A  person  is  not  cured  until  all  syphilitic 
spirochetes  disappear  from  the  body.  This  disinfection  may  be  accom- 
plished easiest  during  the  early  stage  of  the  chancre.  Hence,  the  im- 
portance of  early  diagnosis  by  dark  field  illumination,  and  the  prompt 
and  intensive  use  of  salvarsan,  followed  by  mercury.  The  standard  of 
cure  may  be  set  as  follows:  One  year  without  treatment,  without  any 
suspicious  clinical  signs,  with  several  negative  Wassermann  •  reactions 
and  no  positive  ones,  and  with  a  spinal  fluid  examination  negative  for 
syphilis. 

Calomel  Ointment  as  a  Prophylactic. — Syphilis  was  regarded  as  an 
infection  peculiar  to  man  until  MetchnikofE  and  Eoux  in  1903  trans- 
mitted the  disease  to  the  higher  apes.  Later  it  was  found  that  monkeys 
and  rabbits  are  susceptible.  As  a  result  of  these  experiments,  certain 
important  facts  in  reference  to  prophylaxis  were  discovered.     Of  all  the 

"  Thirteen  states,  namely,  Alabama.  Indiana,  Michigan,  Xew  Jersey,  Xew 
York,  North  Dakota,  Oregon,  Pennsylvania.  Utah,  Vermont,  Virginia,  Washing- 
ton and  Wisconsin,  have  laws  enforced  relating  to  venereal  disease  in  connection 
with  marriage.  The  laws  vary  in  wording,  but  the  purport  of  all  is  to  prevent 
the  marriage  of  all  infected  with  acute  syphilis  or  gonorrhea. 

"  Syphilis,  1909,  Cassell  &  Co.,  p.  553. 

"JoMr.  A.  M.  A.,  March  6,  1915,  LXIV,  10,  p.  804. 


66  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

various  germicidal  substances  tried,  Metchnikoff  and  Eoux  found  that 
mercurial  inunctions  are  most  successful  in  preventing  the  development 
of  the  chancre.     Calomel  ointment  has  proved  itself  best. 

In  a  communication  published  in  1906,  Metchnikoff  and  Eoux  ^* 
state  that  having  tried  12  experiments  on  monkeys  with  uniformly  satis- 
factory results,  they  next  performed  the  experiment  on  a  man.  A  stu- 
dent of  medicine  offered  himself,  and  they  assured  themselves  that  he 
had  never  had  syphilis^  either  acquired  or  hereditary.  The  man  did  not 
develop  syphilis,  although  watched  for  more  than  three  months.  Seven- 
teen days  after  the  inoculation  the  two  control  monkeys  that  were  not 
treated  with  the  ointment  developed  primary  lesions,  while  the  monkey, 
treated  after  a  twenty-hour  interval,  developed  a  chancre  after  thirty- 
nine  days'  incubation.  It  is  interesting  to  note  that  the  subject  of  this 
experiment  was  Maisonneuve,^^  who  published  this  experiment  on  him- 
self as  part  of  his  thesis  for  the  doctorate. 

Calomel  ointment- to  be  effective  must  contain  33  per  cent,  of  calomel, 
should  be  incorporated  in  lanolin  ^*'  as  a  base,  and  great  care  should  be 
taken  in  its  preparation  to  ensure  thorough  mixing.  No  doubt  many 
failures  in  actual  practice  and  even  in  some  experiments  may  be  at- 
tributed to  ignorance  or  negligence  on  the  part  of  the  pharmacist  in 
not  following  these  directions. 

With  rare  exceptions,  those  who  have  watched  the  use  of  the  prophy- 
lactic among  troops  or  other  large  bodies  of  men  are  enthusiastic  in 
regard  to  the  results  obtained,  but  the  figures  and  statements  they  present 
would  hardly  serve  to  convince  the  critical.  In  practice  it  cannot  be 
expected  that  the  use  of  the  prophylactic  will  be  invariably  successful, 
but  it  seems  reasonable  'to  believe  that  if  properly  applied  during  the 
first  hour  after  exposure  it  will  prevent  the  great  majority  of  syphilitic 
infections.  The  efficacy  of  the  prophylactic  diminishes  rapidly  as  the  time 
between  its  use  and  the  exposure  increases.  In  addition  to  this  time 
factor,  there  will  be  variations  in  efficacy  in  practice,  depending  upon 
the  care  with  which  the  calomel  ointment  is  compounded  and  upon  the 
intelligence  and  thoroughness  with  which  the  prophylactic  is  applied. 

Colonel  Edwin  P.  Wolfe,'^^  who  conducted  work  at  Fort  McKinley, 
P.  I.,  found  that  only  two  cases  of  primary  syphilis  occurred  among 
19,465  men  who  were  given  prophylactic  treatment,  whereas  99  cases 
developed  among  men  who  did  not  receive  the  treatment.  Acevodo  ''^ 
in  1908  reported  1435  prophylactic  treatments  in  the  Chilean  Navy 
following  exposures  in  ports  all  over  the  world:  only  3  cases  developed 
syphilis.     See  also  page  81. 

■'*Bull  de  I'Aoad.  de  Med.,  1906,  LV,  554. 

"  These  de  Paris,  1906,  Steinheill. 

"  Adeps  lanse  hydrosus,  containing  not  more  than  30  per  cent,  water. 

"Vedder's  "Syphilis  and  Public  Health,"  p.  190. 

"  Mai  Cutan.  et  SyphiUtiques,  1908,  XIX,  868. 


VENEREAL  DISEASES  67 

Excision,  or  destruction  of  the  chancre  with  the  actual  cautery  or 
with  corrosive  antiseptics  does  not  iniiuence  tlie  development  of  the 
disease. 

Further  measures  for  the  prevention  of  syphilis  are  considered  with 
Venereal  Prophylaxis  and  Hygiene  of  Sex,  pages  73  to  86. 

Summary. — Syphilis  affects  about  8  per  cent,  of  the  total  population, 
occurs  at  all  ai^es  and  in  all  class^vs  of  society,  is  the  cause  of  from  U)  to 
35  per  cent,  of  all  insanity,  and  is  one  of  the  causes  of  mentally  and 
physically  deficient  children.  It  is  the  cause  of  locomotor  ataxia,  paresis, 
and  the  chief  cause  of  apoplectic  strokes  in  early  life,  and  is  responsible 
for  a  large  proportion  of  diseases  of  the  heart  and  blood  vessels;  is  the 
cause  of  nearly  half  of  abortion  and  miscarriages.  Syphilis  decreases 
the  length  of  life  about  one-third;  it  also  lowers  the  standard  of  health 
and  paves  the  way  for  other  diseases;  it  greatly  decreases  earning 
capacity ;  is  the  most  serious  cause  of  disruption  of  home  and  happiness, 
and  causes  untold  suffering  and  misery.  Withal,  it  is  preventable  and 
curable.  The  public  health  control  of  syphilis  depends  upon  early 
diagnosis  and  facilities  for  prompt  treatment. 

GONORRHEA 

Gonorrhea  is  much  more  prevalent  than  syphilis,  and  common  opin- 
ion regards  it  as  a  mild  and  not  very  shameful  disease,  that  is,  "no  worse 
than  an  ordinary  cold."  As  a  matter  of  fact,  gonorrhea  is  one  of  the 
serious  infectious  diseases,  and  the  gonococcus  occupies  a  position  of 
high  rank  among  the  virulent  pathogenic  microorganisms.  From  an 
economic  and  public  health  standpoint,  gonorrhea  does  not  fall  very 
far  short  of  syphilis  in  importance. 

The  gonococcus  occurs  characteristically  in  the  polymorphonuclear 
leukocytes  as  small,  biscuit-shaped.  Gram  negative  diplococci.  The  or- 
ganism is  aerobic  and  can  be  cultivated  only  on  special  media  and  then 
with  difficulty.  It  is  killed  in  a  few  minutes  at  55°  C.  It  soon  dies  when 
dried  or  when  exposed  to  the  air.  It  is  very  frail,  outside  the  body, 
weak  germicides  being  sufficient  to  kill  the  coccus.  Cultures  soon 
lose  their  virulence.  Infantile  types  appear  to  be  much  less  pathogenic 
than  adult  types. 

The  complications  of  gonorrhea  are:  periurethral  abscess,  prostatitis 
and  epididymitis  in  the  male;  vaginitis,  endocervicitis  and  inflamma- 
tion of  the  glands  of  Bartholini  in  the  female.  Perhaps  the  mose  serious 
of  all  the  sequelae  of  gonorrhea  are  those  which  result  from  the  spread  by 
direct  continuity  of  tissues,  such  as  inflammation  of  the  uterus,  often 
extending  into  the  fallopian  tubes  to  the  ovary,  and  even  the  peritoneum. 
The  gonococcus  has  been  found  in  pure  culture  in  cases  of  acute  general 
peritonitis.     Other  inflammations  caused  by  the  spread  of  the  infection 


68  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

are  cystitis,  which  sometimes  extends  upward  through  the  ureters  to 
the  kidneys. 

The  gonococcus  sometimes  invades  the  blood  and  produces  a  general 
septicemia;  death  may  occur  from  acute  endocarditis.  Gonorrheal 
arthritis  is,  in  many  respects,  the  most  damaging,  disabling,  and  serious 
of  all  the  complications  of  gonorrhea.  It  may  even  follow  ophthalmia 
neonatorum.  It  is  more  frequent  in  males  than  in  females,  but  a 
gonorrheal  arthritis  of  great  intensity  may  occur  in  a  newly  married 
woman  infected  by  an  old  gleet  in  her  husband.  The  serious  nature 
of  gonorrheal  complications  in  the  eye  will  be  considered  separately 
under  Ophthalmia  Neonatorum.  Gynecologists  tell  us  that  the  greater 
part  of  their  practice  is  made  up  of  the  consequences  of  gonorrhea. 

Morrow  ^^  assures  us  that  80  per  cent,  of  deaths  from  infections 
peculiar  to  women  are  due  to  gonorrhea.  From  75  to  80  per  cent,  of  all 
operations  of  the  female  genital  tract  are  said  to  be  due  to >  gonorrheal 
infections  alone. 

Sterility  is  one  of  the  serious  consequences  of  gonorrhea.  This  may 
be  caused  in  the  male  through  epididymitis  or  orchitis,  which  is  a  very 
common  complication,  and  in  the  female  by  salpingitis,  which  closes  or 
obstructs  the  fallopian  tubes.  Gonorrhea  is  said  to  be  the  cause  of  about 
one-half  of  all  cases  of  sterility. 

Stricture  of  the  urethra  in  the  male  is  a  frequent  sequel. 

Gonorrhea  is  usually  transmitted  by  sexual  congress;  however,  acci- 
dental or  innocent  infections  are  not  infrequent,  especially  in  children. 

Standards  of  Cure. — It  is  difficult  to  determine  when  a  case  is 
cured.  The  following  tentative  rules  are  laid  down  by  the  U.  S.  Public 
Health  Service: 

Males:  (1)  Freedom  from  discharge.  (2)  Clear  urine;  no  shreds. 
(3)  The  pus  expressed  from  the  urethra  by  prostatic  massage  must  be 
negative  for  gonococci  on  four  successive  examinations  at  intervals  of 
one  week.  (4)  After  dilation  of  the  urethra  by  passage  of  a  full-sized 
sound,  the  resulting  inflammatory  discharge  must  be  negative  for 
gonococci. 

Females:  (1)  No  urethral  or  vaginal  discharge.  (2)  Two  suc- 
cessive negative  examinations  for  gonococci  of  secretions  of  the  urethra, 
vagina,  and  the  cervix,  with  an  interval  of  48  hours  and  repeated  on  4 
successive  weeks. 

The  diagnosis  of  gonorrhea  is  usually  made  from  stained  smears  of 
the  secretions.  Unless  the  preparation  is  well  made,  properly  stained, 
and  examined  by  a  competent  microscopist,  the  results  may  not  be  de- 
pendable. Positive  results  are  indicated  by  the  presence  of  Gram- 
negative  diplococci  in  the  leukocytes.  Negative  findings  do  not  rule  out 
the  disease,  especially  in  the  female.    The  specificity  of  the  complement 

''^Boston  Med.  d  Surg.  Journ.,  1911,  CLXV,  p.  520. 


VENEREAL  DISEASES  69 

fixation  test  depends  upon  the  tethnii.'  and  the  operator :  When  positive, 
it  indicates  gonorrhea.  A  negative  test  does  not  exclude  tlie  disease. 
This  test  has  not  yet  heen  standardized. 

Prevention. — Inject,  as  soon  after  exposure  as  practicable,  2  per  cent, 
protargol  or  lU  per  cent,  argyrol.     See  page  82 

Vulvovaginitis  in  Children,. — Vulvovaginitis  (epidemic  vaginitis) 
is  common  in  children  and  is  frequently  due  to  the  gonococcus.  Out- 
breaks are  common  in  schools,  tenements,  playgrounds,  asylums,  hos- 
pitals or  Avherever  children  congregate  in  considerable  numbers  and 
where  the  same  lavatories,  towels,  nurses,  etc.,  are  provided  in  common. 
Paul  Bendig  ^^  reports  the  following  instance :  Of  40  girls  sent  for  con- 
valescence to  a  brine  bath,  15  showed  signs  of  gonorrhea  after  the  re- 
turn. The  infection  came  from  an  eight  year  old  girl,  who  apparently 
had  been  suffering  from  gonorrhea  for  several  years,  and  was  spread 
through  indiscriminate  bathing  in  one  bath  tub  and  the  use  of  the  same 
bath  towel. 

Infants  may  contract  the  infection  from  the  hands  of  the  nurse. 
Syringes,  bed  pans,  catheters,  thermometers,  towels,  diapers,  wash  cloths, 
and  bed  linen  may  account  for  the  transmission  of  the  gonococcus  in 
hospitals  and  asylums,  although  the  rapidity  with  Avhich  the  gonococcus 
dies  when  dried  diminishes  the  danger  somewhat  from  this  source. 
Diapers  should  always  be  disinfected  by  boiling  or  steaming  before  they 
are  again  used,  especially  in  institutions;  this,  not  only  on  account  of 
gonorrhea,  but  of  infectious  diarrheas.  In  the  public  bath,  children  who 
use  the  same  towel,  tub,  soap,  etc.,  run  a  great  risk.  Taussig  ^^  believes 
the  seat  of  the  water-closet  favors  the  infection  in  little  girls.  These 
seats  are  usually  too  high  and  thus  readily  become  smeared  with  the 
discharges  from  the  vagina,  and  thus  infect  others.  In  schools  and 
tenements  the  water-closets  are  often  used  by  a  stream  of  children  one 
after  another.    Hence,  such  seats  should  be  low  and  U-shaped. 

The  frequency  of  gonorrhea  in  children  may  be  judged  from  the 
observations  of  Pollack,  who  reports  187  cases  treated  in  the  Women's 
Venereal  Department  of  Johns  Hopkins  Hospital  during  the  year  1919.^- 
Pollack  estimates  that  800  to  1000  children  are  infected  each  year  in 
Baltimore,  and  that  the  same  proportion  probably  holds  good  for  other 
cities.  Seippel  estimates  that  500  cases  occur  annually  in  Chicago.  One 
cause  of  the  infection  among  children  is  the  horrible  superstition  that  a 
person  infected  with  gonorrhea  may  get  rid  of  it  by  infecting  another — 
especially  a  virgin.     Gonorrhea  in  children  due  to  rape  is  rare. 

When  gonorrhea  enters  a  children's  hospital  or  an  infant's  home  it 
is  prone  to  become  epidemic  and  is  very  difficult  to  eradicate.     The 

*"  Miinchener  med.  Wochenschr.,  1909,  p.  1846. 

^^Amer.  Journ.  Med.  Sciences,  CXLVIII.  4,  Oct.,  1914,  p.  480. 

'^  Johns  Hopkins  Hospital  Bull.,  May,  1909,  p.  142. 


70  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

story  of  the  infection  in  the  Babies'  Hospital,  New  York,  for  eleven 
years,  as  told  by  Holt,^^  illustrates  the  singular  obstinacy  of  the  in- 
fection. In  spite  of  the  greatest  care  and  precaution,  there  were,  in 
1903,  65  cases  of  vaginitis  with  2  of  ophthalmia  and  12  of  arthritis.  In 
1904  there  were  52  cases  of  vaginitis,  only  16  of  which  would  have  been 
recognized  without  the  bacteriological  examination.  In  all,  in  the  eleven 
years,  there  were  273  cases  of  vaginitis;  6  with  ophthalmia,  and  26  with 
arthritis.  Holt  urges  isolation  and  prolonged  quarantine  as  the  only 
measures  to  combat  successfully  the  disease.  It  is  impossible  to  control 
such  epidemics  without  bacteriological  diagnosis,  aided  by  complement 
fixation  tests. 

Hess  believes  that  the  greatest  obstacle  to  controlling  the  disease  is 
the  difficulty  of  recognizing  latent  cases.  It  is  possible  to  convert  the 
concealed  carrier  into  an  open  case  by  means  of  provocative  inoculations 
of  gonococcus  vaccines.  The  complement  fixation  test  gives 'a  very  high 
percentage  of  positive  results  when  gonococci  are  present,  except  in  the 
very  acute  stage. 

Epidemic  vaginitis  is  intractable  in  children  and  tends  to  a  spon- 
taneous cure  at  puberty.  Many  cases  continue  for  years  despite  careful 
treatment,  and  disappear  spontaneously  at  puberty. 

Complications  and  sequelae  of  vulvovaginitis  in  children  are  much 
less  common  than  gonococcus  complications  and  sequelae  in  the  adult. 
Louise  Pearce  ®*  has  shown  that  the  infant  types  of  gonococci  differ 
from  the  adult  types  when  tested  by  agglutination  and  complement 
fixation.  The  infantile  types  are  also  much  less  virulent,  and  cause  fewer 
complications. 

The  social  and  public  health  problems  which  this  disease  presents 
are  very  great,  and  our  knowledge  of  the  disease  from  the  standpoint  of 
diagnosis,  quarantine,  and  treatment,  is  not  sufficient  to  enable  us  to 
handle  this  question  in  a  satisfactory  manner.  A  diagnosis  resting 
solely  upon  the  morphological  and  staining  characteristics  of  the  or- 
ganisms found  in  smears  is  not  sufficient  to  brand  a  child  with  the 
diagnosis  of  gonorrhea.  Vulvovaginitis  in  children  is  not  a  venereal  dis- 
ease. If  the  term  gonorrheal  or  gonococcus  vaginitis  were  dropped  from 
the  literature,  and  the  term  epidemic  vaginitis  substituted,  it  would  be 
much  easier  to  handle  these  cases  from  a  public  health  standpoint. 

For  the  prevention  of  vulvovaginitis  in  children,  the  good  advice  of 
the  American  Pediatric  Society  should  be  followed :  ^^ 

(a)  That  cities  be  required  to  provide  adequate  hospital  and  dis- 
pensary facilities  for  the  care  and  treatment  of  children  having 
vaginitis. 

"2V.  y.  Med.  Journ.,  March,  1905. 

^*Journ.   Exper.   Med.,   XXI,   4,   April,   1915,   p.   289. 

»'  Arch,  of  Ped.,  XXXII,  1916,  p.  361. 


VENEREAL  DISEASES  71 

(b)  That  matrons  be  placed  in  charge  of  the  girls'  toilet  rooms  in 
public  schools. 

(c)  That  toilet  seats  embodying  the  principle  of  the  U-shape  be 
used  in  all  schools  and  that  the  toilets  bo  of  proper  height  for  different 
ages. 

(d)  That  city  and  state  laboratories  be  empowered  and  equipped 
to  make  bacteriological  examinations  for  physicians  when  patients  can- 
not afford  to  pay  a  private  laboratory  fee. 

(e)  That  educational  literature  on  the  subject  of  vaginitis  be  pre- 
pared and  distributed  to  mothers  through  the  medium  of  physicians, 
hospitals,  dispensaries,  health  centers,  municipal  and  visiting  nurses. 

(f)  That  asylums  for  children  and  day  nurseries  be  licensed  and 
that  the  license  be  not  granted  unless :  first,  the  institution  has  adequate 
facilities  for  the  recognition  of  gonococcus  vaginitis;  and  second,  the 
institution  excludes  children  having  this  disease  if  they  cannot  be  prop- 
erly isolated. 

That  the  American  Pediatric  Society  address  a  special  letter  to 
hospitals  which  care  for  children,  containing  the  following  recom- 
mendations : 

(a)  That  separate  wards  be  maintained  for  the  treatment  of  chil- 
dren with  vaginitis  who  are  also  suffering  from  other  diseases. 

(b)  That  microscopic  examinations  of  smears  be  made  before  ad- 
mission to  the  general  wards  of  the  hospital.  In  securing  material  for 
the  smears  extreme  care  should  be  taken  to  observe  rigid  aseptic  pre- 
cautions, 

(c)  That  observation  wards  be  provided. 

(d)  That  individual  syringes,  bed  pans,  catheters,  clinical  ther- 
mometers, thermometer  lubricant,  wash  basin,  soap,  powder,  wash  cloths 
and  towels  be  provided. 

.  (e)  That  single  service  diapers  be  used  (at  least  for  girls)  ;  or, 
that  diapers  be  sterilized  in  an  autoclave  at  15  pounds  pressure  for 
five  minutes. 

(f)  That  nurses  be  required  to  make  daily  inspection  of  the  vulva 
of  each  girl  at  the  time  of  bathing  and  to  report  immediately  the  pres- 
ence of  the  slightest  suggestion  of  a  vaginal  discharge. 

(g)  That  low  toilets  be  provided  and  equipped  with  seats  embody- 
ing the  principle  of  the  U-shape. 

(h)  That  for  routine  purposes,  the  spray  be  used  in  place  of  tub 
baths  for  the  bathing  of  young  girls,  and  that  older  girls  be  sponged 
in  beds. 

(i)  That  nurses  receive  special  instruction  as  to  the  nature  of 
vaginitis,  the  ease  with  which  it  is  transmitted,  the  methods  of  prevent- 
ing its  spread  and  the  necessity  for  rigid  aseptic  surgical  technic  in  its 
handling  and  treatment. 


72  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

(j)  That  a  dispensary  with  special  facilities  for  the  treatment  of 
gonococcus  vaginitis  be  provided. 

(k)      That  nursing  care  and  supervision  be  given  in  the  home. 

(1)  That  mothers  be  instructed  as  to  the  dangers  of  vaginitis,  the 
manner  in  which  it  is  transmitted,  the  "best  method  of  protecting  other 
children,  and  the  necessity  of  prolonged  observation. 

(m)  That  all  cases  of  vaginitis  under  observation  be  voluntarily 
reported  to  the  local  health  officer  in  states  or  cities  where  no  legal 
requirements  are  in  force. 

Summary. — Gonorrhea  is  the  most  constantly  prevalent  of  all  serious 
infectious  diseases,  except  measles;  affects  all  ages  and  all  classes  of 
society;  is  responsible  for  from  6,000  to  10,000  cases  of  blindness  in  the 
United  States ;  is  the  cause  of  60  per  cent,  of  blindness  of  the  new  born ; 
is  the  cause  of  more  than  10  per  cent,  of  all  blindness;  is  the  cause  of 
from  60  to  75  per  cent,  of  surgical  operations  on  the  female  generative 
organs;  of  50  per  cent,  of  sterility;  of  many  chronic  diseases  of  the  joints, 
bladder  and  generative  organs ;  greatly  decreases  earning  capacity ;  is 
the  underlying  cause  of  untold  suffering  and  misery;  and  affects  prac- 
tically all  prostitutes,  public  and  clandestine.  Xotwithstanding,  gon- 
orrhea is  a  preventable  disease. 

Further  measures  for  the  prevention  of  gonorrhea  are  considered  with 
Venereal  Prophylaxis  and  Hygiene  of  Sex,  pages  73  to  86. 

CHANCROID 

Chancroid  is  a  specific,  local,  auto-inoculable,  and  contagious  venereal 
ulcer,  caused  by  the  streptobacillus  of  Ducrey  (1889).  The  ulcers  are 
often  multiple  and  confer  no  immunity.  Chancroids  are  local  ulcers 
and  cause  no  sequelae  or  general  systemic  effects,  such  as  follow  chancres. 
Chancroids,  or  soft  chancres,  are  peculiarly  liable  to  mixed  infections, 
and  are  apt  to  become  phagedenic. 

As  many  as  50  per  cent,  of  soft  chancres  are  mixed  infections  with  the 
Spirochceta  pallida.  Every  venereal  lesion  should  be  examined  by  dark- 
field  illumination  for  spirochetes.  This  is  of  great  importance  from  a 
public  health  standpoint  as  well  as  for  individual  prophylaxis. 

A  little  soap  and  water  at  the  time  of  exposure  is  almost  an  absolute 
preventive  against  chancroid.  If  the  ulcer  has  developed  it  may  be 
aborted  by  cauterization,  provided  the  chancroid  is  not  more  than  three 
days  old.  Even  when  seven  days  old  the  ulcers  may  often  thus  be 
cured,  but  when  more  than  a  week  old,  cauterization  should  not  be  em- 
ployed, for,  if  it  fails,  it  leaves  the  sore  larger  than  ever.  The  method 
of  cauterization  advised  by  Keyes  consists  in  washing  the  ulcers  with 
peroxid  of  hydrogen,  drying,  applying  pure  carbolic  acid,  then  pure 
nitric  acid,  washing  again  with  peroxid  of  hydrogen,  and  dusting  with 


VENEREAL  PROPHYLAXIS  AND  HYGIENE  OF  SEX       73 

calomel.  Spiroi'lietofiiU's  should  nut  be  used  locally  until  syphilis  has 
been  delhiitely  excluded  by  dark  held  illumination. 

Chancroids  are  usually  contracted  in  venery.  The  disease  should  not 
be  regarded  as  a  slight  or  negligible  malady,  for,  on  account  of  the  mixed 
infections  to  wliich  they  are  prone,  serious  consequences,  and  sometimes 
death,  may  result.  The  complications  of  the  ulcers  are  various  forms 
of  phimosis,  resulting  from  inflammation  and  swelling;  destruction  of 
the  frenum;  gangrene  and  phagedena;  lymphangitis,  with  inguinal 
adenitis.     Tiie  inguinal  buboes  arc  painful  and  frequently  suppurate. 

Chancroid  is  usually  given  subordinate  consideration  because  syphilis 
and  gonorrhea  are  much  more  prevalent  and  much  more  serious. 

VENEREAL  PROPHYLAXIS  AND  HYGIENE  OF  SEX 

The  same  principles  apply  to  the  prevention  of  the  venereal  diseases 
as  apply  to  the  prevention  of  other  communicable  diseases.  The  fight 
against  venereal  diseases,  however,  is  especially  complicated  and  ditficult 
because  of  the  close  association  with  prostitution,  the  problems  of  sex, 
morality,  and  alcoholism — in  fact,  the  question  pervades  the  woof  and 
warp  of  society.  There  are  three  primitive  ai^petites  of  man — hunger, 
thirst,  and  the  sexual  appetite.  .  The  first  two  persist  throughout  life; 
the  last  comes  on  at  puberty,  grows  stronger  during  adolescence,  and 
wanes  with  age.  Any  program  for  the  control  of  the  venereal  diseases 
or  the  hygiene  of  sex  must  take  into  account  the  fact  that  we  are  deal- 
ing with,  a  primal,  impulsive,  and  natural  passion  which  is  the  greatest 
force  for  social  good,  when  nsed  in  accordance  with  the  laws  of  nature, 
but  may  result  in  dire  consequences  when  these  laws  are  transgressed. 
The  venereal  diseases  are  among  the  most  widespread  and  universal  of 
all  human  ills,  and  enter  more  largely  into  the  marring  of  domestic 
happiness  than  any  other  disease  known  to  man.  The  difficulties  of  the 
situation  should  not  deter  the  health  officer  and  all  those  who  labor  for 
social  uplift,  for  there  is  no  more  pressing  problem  in  preventive 
medicine. 

Prevalence. — The  prevalence  of  the  venereal  diseases  among  the  popu- 
lation at  large  can  only  be  approximated.  Definite  figures,  however, 
are  at  hand  for  selected  groups.  The  reports  from  the  armies  of  the 
various  nations  give  the  following  figures :  ^^ 

VENEREAL.  INFECTIONS    PER  THOUSAND   MEN 


Years 

Per 

Thousand 

Germany 

1905-6 

19.8 

France 

1906 

28.6 

Austria 

1907 

54.2 

Russia 

1906 

62.7 

United   States 

United  Kingdom 

1907 

;.  .  .1907 

167.8 
68.4 

Wliite  and  Melville,  Lancet,  London,   1911,  II,  1615. 


74  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

Kober  ^"^  gives  a  somewhat  more  recent  and  more  detailed  table. 

DIFFERENTIATED    INFECTION   PER  THOUSAND   MEN 


Year 


U.  S.  Army 1909  \ 

V.  S.  Navy 1909 

Japanese  Navy 1907 

British  Navy 1908 

British   Army 1908 

Japanese    Army 1907 

Prussian   Army 1907 


Syphilis 

Chancroid 

Gonorrhea 

Total 

30.45 

30.77 

135.77 

196.99 

26.49 

28.23 

105.11 

159.83 
139.75 

37.46 

17.87 

67.16 

122.49 

35.1 

28.23 

40.7 

75.8 

10.1 

10.4 

17.1 

37.6 

4.4 

2.1 

12.2 

18.7 

Both  these  tables  indicate  that  the  English-speaking  people  are,  in 
their  navy  and  military  organizations  at  least,  greater  sufferers  from 
venereal  infections  than  the  other  nations.  The  figures  however  are  not 
strictly  comparable,  because  of  different  methods  used  of  recording  these 
diseases.  The  venereal  disease  incidence,  expressed  as  annual  rates  per 
1,000  of  mean  strength  for  United  States  Continental  (excluding 
Alaska)  enlisted  men,  ])y  years  190G  to  1917,  follows: 


1906  — 

143.63 

1907  — 

149.21 

1908  — 

155.17 

1909  — 

151.35 

1910  — 

137.98 

1911  — 

145.29 

1912  — 

115.74 

1913  — 

85.83 

1914  — 

89.84 

1915  — 

83.60 

1916  — 

91.23 

1917  — 

113.82 

Of  the  first  990,592  physical  records  received  by  the  Surgeon  Gen- 
eral, Y.  S.  Army,  under  the  Selective  Service  Act,  a  total  of  28,411  men 
had  venereal  disease — 2.86  per  cent.  Of  these,  23,049  had  gonorrhea, 
4,412  had  syphilis,  and  941  chancroid.  Camp  medical  examiners  found 
a  higher  percentage — 5.4.  These  figures  indicate  the  minimal  amount 
of  venereal  disease  coming  from  civilian  life  among  the  first  million 
drafted.  After  enlistment,  venereal  cases  expressed  as  annual  rates  per 
1,000  of  mean  strength,  averaged  15  during  the  year  1919.  In  slightly 
over  a  year  and  a  half  after  the  first  drafted  men  were  mobilized,  225,000 
cases  of  venereal  disease  were  reported  to  the  Surgeon  General,  .TJ.  S. 
Army,  among  all  troops  in  the  United  States.  Approximately  200,000 
of  these  were  contracted  in  civilian  life.*^ 

In  civil  life  accurate  figures  are  not  obtainable.     Cunningham  ^^  says  . 
that  60  per  cent,  of  men  acquire  venereal  infection  some  time.     Twenty 
per  cent,  of  these  are  incurred  before  the  20th  year,  50  per  cent,  before 

"Kober,  Tr.  Assn.  Am.  Phys..  Phila.,  1011,  XXVI,  155. 

''  The  venereal  disease  rate  in  American  troops  in  France  was  about  45 
cases  per  1,000  men  per  annum.  This  rate  was  never  before  closely  approached 
in  the  U.  S.  Army.  The  corresponding  incidence  rate  in  the  United  States 
averaged  above  60. 

•  *°  Cunningham,  Boston  Med.  and  Surg.  Jour.,   1913,  LXVIII,   77. 


VENEREAL  PROPHYLAXIS  AND  IIVCIK.M-:  OF  SKX   75 

the  •v^")tll  year,  and  80  per  cent,  before  the  30th  yt'ar.  (Jerrisli  ^°  estimates 
that  10  per  cent,  of  the  popuhition  of  New  York  has  syphilis.  Fischer  "^ 
guesses  that'  18  per  cent.  re])reseuts  the  syphilitic  cases  in  the  United 
States,  and  further,  that  there,  are  250,000  deaths  each  year  due  to 
venereal  infections.  Biggs  °-  judges  that  there  were  about  200,000  cases 
of  venereal  diseases  in  the  city  of  New  Y'^ork  in  1912.  Morrow  °^  states 
that  75  per  cent,  of  adult  males  acquire  gonorrhea  at  some  time,  and  that 
from  5  to  10  per  cent,  acquire  syphilis;  these  figures  are  based,  not  alone 
on  his  own  observations,  but  on  tlie  opinion  of  such  men  as  Xeisser  and 
Fournier.  Zinsser "''  estimates  that  10  per  cent,  of  the  men  registered  for 
draft  under  the  selective  service  act  were  actively  infected.  There  were 
2-4,234,021  men  between  18  and  45  registered.  It  is  conservatively  esti- 
mated that  of  this  number  2,600,000  were  diseased,  of  whom  500,000 
were  syphilitic. 

The  pathologists  of  Melbourne,  Australia,^^  found  syphilitic  lesions 
in  30  per  cent,  of  200  necropsies ;  furthermore,  5  per  cent,  of  the  popula- 
tion within  a  ten-mile  radius  from  the  Melbourne  postoffice  were  positive 
to  the  Wassermanu  test.  Banks  ^'^  states  that  we  have  nearly  two  and 
one-half  million  cases  of  venereal  diseases  occurring  yearly  in  the  United 
States — about  one  person  in  every  forty.  These  findings  are  ample  to 
indicate  the  extent  of  the  scourge.     See  also  page  58. 

Attitude. — Our  attitude  toward  the  venereal  diseases  is  very  incon- 
sistent. There  is  a  natural  aversion  toward  these  aiflictions.  The  sani- 
tarian should  make  no  distinction  between  the  venereal  diseases  and 
other  epidemic  diseases;  he  should  regard  the  greatpox  in  the  same 
light  that  he  regards  the  smallpox.  The  principles  for  the  control  of 
syphilis  and  gonorrhea  differ  in  no  wise  from  those  used  to  control 
smallpox,  leprosy,  tuberculosis,  measles^  diphtheria,  etc.  The  health 
officer  must  not  regard  venereal  disease  as  a  punishment  for  sin — the 
victim  or  culprit  needs  help,  even  sympathy.  The  immediate  problem  is 
the  prevention  of  further  spread  of  the  infection.  A  person  afflicted  with 
a  venereal  disease  should  be  treated  in  the  same  humane  spirit  that 
actuates  us  in  other  diseases.  Furthermore,  the  interests  of  the  com- 
munity require  that  the  patient  be  accorded  the  best  possible  care  and 
treatment.  The  usual  attitude  toward  the  venereal  diseases  may  well 
startle  us  when  we  consider  that  in  most  of  our  large  cities  no  hospital 
will  take  a  case  of  s}^hilis  or  gonorrhea  during  the  acute  stages,  when 
these  diseases  are  especially  communicable.  Morrow  holds  that  the 
notoriously  inadequate  provision  made  for  the  reception  and  treatment 

*°Gerrish,  "Social  Diseases,"  New  York.  1911.  II.  ]. 

»>  Fischer,  Public  Health,  Lansincr.  Mich..   1913.  VIII,  .51. 

*' Biggs,  .Y.  Y.  Med.  Jour.,  191.3,  XCVIII,  1009.' 

^'Morrow,  Boston,  Med.  and  Surg.  Jour..   1911,  CLXV,  520. 

^♦Letter,  .June  21,  1919,  Am.  8oc.  Hi/g.  Assn. 

"Barrett,    West   Canada   Med.   Journ..   1913,   YII,    164. 

^Public  Health  Rep.,  Feb.  26,   1915,  XXX,  9,  p.  618. 


76  ■  DISEASES  HAYING  SPECIAL  PROPHYLAXIS 

of  venereal  patients  is  a  disgrace  to  our  civilization.  Formerly  lepers 
were  segregated  in  vile  lazarettos  and  cases  of  smallpox  isolated  in  hor- 
rible pesthouses ;  now  we  have  comfortable  and  congenial  isolation  wards 
or  special  sanatoria  for  these  diseases.  From  the  standpoint  of  pre- 
vention suitable  hospital  accommodations  must  be  provided  for  venereal 
cases. 

Education, — Ed^ication  in  sex  hygiene  and  the  venereal  peril  ac- 
complishes a  certain  amount  of  good.  A  knowledge  of  the  consequences 
will  not  control  passion.  Efforts  to  instill  a  wholesome  fear  of  venereal 
diseases  are  futile.  Even  one  attack  of  a  venereal  disease  does  not  act 
as  a  deterrent  to  future  immorality,  and  medical  students  who  are  pre- 
sumably informed  are  no  more  moral  than  other  members  of  the  student 
body.  The  only  education  that  will  effect  a  reduction  in  immorality  is 
the  education  that  forms  character  and,  as  Huxley  says,  "Molds  the 
desire  to  live  in  accordance  with  the  laws  of  nature." 

However,  the  old-style  innocence  must  be  regarded  as  present-day 
ignorance.  Every  boy  and  girl,  before  reaching  the  age  of  puberty, 
should  have  a  knowledge  of  sex,  and  every  man  and  woman  before  the 
marriageable  age  should  be  informed  on  the  subject  of  reproduction 
and  the  dangers  of  venereal  diseases.  Superficial  information  is  not 
true  education.  On  the  other  hand,  it  is  a  mistake  to  dwell  unduly 
upon  the  subject,  for  in  many  instances  the  imagination  and  passion 
of  youth  are  inflamed  by  simply  calling  attention  to  the  subject.  One 
of  the  objects  of  education  is  to  avoid  the  dangers  of  sex  impurities, 
and  all  agree  that  this  may  often  best  be  accomplished  by  keeping  the 
mind  clean,  that  is,  away  from  the  subject.  The  education  must, 
therefore,  be  clear,  pointed,  brief,  and  direct.  The  object  of  educa- 
tion is  not  alone  to  help  the  individual  to  help  himself,  but  to  influence 
necessary  legislation  and  concerted  public  action;  also  to  lessen  the 
influence  of  quacks.  A  simple  knowledge  of  the  facts  is  a  sufficient 
deterrent  for  some;  others  may  be  influenced  through  fear  of  the  con- 
sequences. Boys,  as  a  rule,  cannot  be  controlled  through  fear.  The 
spirit  of  adventure  is  rife  in  healthy  lads;  they  love  to  take  a  chance. 
Boys  may  be  reached  by  an  appeal  to  their  better  natures  and  by  allu- 
sions to  sister  or  mother.  ISTormal  boys  are  heedless  of  self,  but  are  re- 
gardful of  others :  hence,  a  knowledge  of  the  peril  to  future  wife  and 
offspring  is  the  most  impressive  fact  to  keep  boys  straight. 

Instruction  in  sex  hygiene  should  emphasize  the  rewards  of  strength 
and  virtue,  rather  than  the  penalties  of  weakness  and  vice.  The  only 
foundation  for  a  healthy  sex  life  is  an  individual  and  social  morality, 
combined  with  a  knowledge  and  full  understanding  of  sexual  realities. 
The  teaching  of  sex  from  a  biological  standpoint  alone  is  inadequate,  for 
there  is  little  basis  for  character  forming  or  ethical  instruction  in  the 
physiological  analogies  of  animal  and  plant  life.     Instruction  should  be 


VENEREAL  PROPHYLAXIS  AND  HYGIENE  OF  SEX       77 

positive  rather  than  negative,  constructive  rather  than  destructive,  Tlie 
fear  of  disease  or  fear  of  anything  else  is  not  a  sufficient  motive  for 
goodness.  In  contrast  to  the  usual  procedures,  the  empliasis  should  he 
placed  on  the  beauty  of  goodness  rather  than  on  the  ugliness  of  vice. 

In  general,  it  may  be  said  that  the  best  plan  of  education  in  mat- 
ters sexual  is  to  answer  the  questions  of  young  children  upon  the  subject 
of  maternity  frankly  and  truthfully,  but  to  offer  them  no  information  on 
the  subject.  The  growing  child  at  the  age  of  puberty  should  be  offered 
a  certain  amount  of  information  concerning  unnatural  habits  and  should 
study  physiolog}',  biology,  especially  botany,  and  the  facts  of  fertiliza- 
tion. At  about  the  age  of  sixteen  or  eighteen  girls  as  well  as  boys 
should  be  instructed  as  to  the  venereal  peril.  Emphasis  should  be 
placed  upon  the  future  hazard  to  wife  and  offspring.  The  person  to 
impart  the  information  may  be  parent,  doctor,  minister,  friend,  or 
teacher — in  any  event,  two  qualifications  are  essential:  (1)  Knowledge 
of  the  facts;  (2)  an  impressive  personality.  As  a  rule  the  school- 
teacher is  not  naturally  endowed  nor  is  the  class-room  the  best  place 
to  attain  the  reverent  attitude  essential  to  teach  lessons  in  sex  hy- 
giene. 

Unless  education  in  sex  hygiene  to  the  young  is  properly  given,  which 
is  most  difficult,  it  may  do  more  harm  than  good.  Some  of  it  excites 
morbid  curiosity,  and  there  is  a  peculiar  twist  to  human  nature  that 
drives  many  to  do  anything  specifically  charged  not  to  do.  The  general 
reluctance  of  parents  and  teachers  to  discuss  sex  matters  with  the  young 
is  ascribed  by  many  to  prudery,  but  it  is  often  a  safe  instinct  to  follow. 
The  problem  of  sex  should  be  approached  in  the  spirit  of  personal  re- 
serve that  we  associate  with  the  better  sort  of  home  life  rather  than  in 
the  spirit  of  eager  curiosity  and  practical  experimentation  that  we 
associate  with  the  school.  The  ideal  method  of  instruction  in  these 
matters  is  therefore  individual.     See  also  pages  -139-441,  447,  448. 

Admirable  pamphlets  are  distributed  by  the  United  States  Public 
Health  Service,  Washington,  D.  C,  by  the  American  Social  Hygiene 
Association,  105  West  40th  Street,  New  York  City,  and  by  some  state 
and  city  boards  of  health. 

Some  of  the  facts  all  young  men  should  know  are :  that  the  true 
purpose  of  the  sex  function  is  reproduction  and  not  sensual  pleasure; 
that  the  testicles  have  a  twofold  function,  (a)  reproduction  and  (b)  to 
supply  force  and  energy  to  other  organs  of  the  body;  that  occasional 
seminal  emissions  at  night  are  evidences  of  normal  physiological  activity ; 
that  sexual  intercourse  is  not  essential  to  the  preservation  of  virility; 
that  chastit}'  is  compatible  with  health ;  and  that  the  sex  instinct  in  man 
may  be  controlled. 

The  primary  function  of  the  testicles  is  to  build  the  boy  into  the 
man.     Castration  in  early  life,  as  in  the  case  of  eunuchs,  results   in 


78  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

a  loss  of  the  internal  secretion  ^^  of  the  testicles  and  a  failure  in  develop- 
ment of  the  secondary  sexual  characters  which  distinguish  the  male. 
There  are  an  alteration  in  physical  conformation  and  in  the  voice,  lack 
of  beard,  development  of  the  mammae,  etc. — in  other  words,  an  approach 
to  the  feminine  type.  Healthy  sexuality,  stimulates  the  imagination, 
sentiment,  the  esthetic  sense,  and  the  higher  creative  functions.  Excesses 
or  any  influence  which  weakens  the  sexual  system  impair  the  will  power, 
influence  self-respect,  and  diminish  mental  force.  Experience  shows 
that  arduous  physical  and  mental  labor,  even  after  maturity  is  attained, 
is  best  performed  when  the  sex  organs  are  not  exercised ;  that  is,  sexual 
excess  distinctly  impairs  muscular  strength  and  mental  efficiency.  It 
is  unwise  to  frighten  boys  by  exaggerating  the  results  of  self -abuse, 
which  is  rather  the  effect  and  not  the  cause  of  idiocy,  insanity,  degen- 
eracy, and  other  defects  of  the  central  nervous  organization.  Self- 
abuse  is  no  worse  in  its  effects  than  natural  coitus,  except  for  its  in- 
fluence upon  character.  Both  are  alike  harmful  when  indulged  in  to 
excess. 

Eesults  through  education  will  be  slow,  for  the  aggressive  conscience 
of  the  world  in  these  matters  has  awakened  too  recently  to  have  achieved 
as  yet  a  great  deal.  Good  results  are  already  apparent  upon  the  youth 
of  the  growing  generation. 

Notification. — It  is  not  possible  to  control  any  communicable  dis- 
ease, especially  one  that  is  pandemic,  such  as  syphilis  or  gonorrhea,  with- 
out a  knowledge  of  the  cases  and  deaths.  It  is  perhaps  even  more  impor- 
tant to  collect  morbidity  and  mortality  statistics  of  the  greatpox  than  it  is 
of  the  smallpox.  But  the  public  registration  of  private  disease  at  once 
defeats  its  own  object.  Compulsory  methods  are  only  partly  successful, 
and  little  may  be  expected  from  voluntary  registration.  When  we 
consider  that  in  our  country  we  have  no  means  of  knowing  the  amount 
and  distribution  of  smallpox,  except  to  a  limited  degree  in  the  registra- 
tion area,  what  can  we  expect  from  the  registration  of  the  closely  guarded 
secrets  of  the  underworld?  The  public  registration  of  ophthalmia 
neonatorum  is  successful  because  this  form  of  gonorrhea  is  so  apparent 
and  the  consequences  so  immediate  and  serious. 

Notification  by  serial  number  became  effective  in  Massachusetts  in 
February,  1918,  and  is  meeting  with  increasing  success.  In  the  11 
months  of  1918,  7,681  cases  of  gonorrhea  and  3,281  cases  of  syphilis 
were  reported  to  the  State  Department  of  Public  Health;  in  1919,  9,435 
cases  of  gonorrhea  and  4,127  cases  of  syphilis. 

To  be  effective,  compulsory  notification  must,  in  the  judgment  of 
the  National  Council  for  Combating  Venereal  Diseases,  include  as  the 
first  and  most  necessary  measures:  (1)  The  provision  in  every  area  of 
adequate  facilities  for  prompt  diagnosis  and  efficient  treatment,  free  of 

*'  Both  the  testes  and  ovaries  produce  hormones. 


VENEREAL  PROPHYLAXIS  AND  HVOIFAK  OF  SEX       79 

charge.  (2)  The  pruliibitioii  of  <juack  trcatnicnt.  (;5)  (iraiitin",^  of 
privilege  to  any  communication  nunlc  in  j;tio<l  faith  by  a  medical  man 
in  order  to  ]irevent  the  spread  of  infection.  False  reporting  hy  number 
docs  not,  after  all,  give  the  information  necessary  to  deal  Avith  the  con- 
ditions. Tlic  Australian  hiw  requires  notification  hy  physicians  and 
requires  that  the  patient  go  to  a  qualified  practitioner  for  treatment 
upon  penalty  of  (hie  and  imprisonment.  Any  system  of  notification 
without  adequate  facilities  for  treatment  will  fail  of  its  ])urposo.  The 
difficulties,  however,  need  not  deter  us,  and  registration  should  he  at- 
tempted even  though  the  returns  are  incomplete.  A  start  should  l)e 
made,  and,  though  the  returns  will  he  only  partial  at  first,  a  gradual  im- 
provement may  be  expected.  Every  case  known  and  properly  cared  for 
is  a  focus  of  infection  neutralized. 

Continence. —  One  of  tlie  important  facts  to  teach  boys  is  that  con- 
tinence is  compatible  with  health.  It  is  also  the  best  preventive  against 
venereal  infection.  The  testicles  are  like  the  tear  gland  and  the  sweat 
glands,  in  that  they  do  not  atrophy  with  disuse.  Benjamin  Franklin 
taught,  as  many  another  man  of  influence  believes  to-day,  that  the  exer- 
cise of  the  sexual  functions  is  necessary  for  health.  This  is  a  mistake 
and  has  done  much  harm.  The  physiologic  normal  for  frequency  of 
nocturnal  emissions  in  sexually  abstinent  males  is  commonly  given  as 
one  to  four  per  month. 

The  sex  principle  is  universal  in  nature.  It  is  the  force  behind 
the  constructive  and  progressive  processes  of  all  life,  from  the  color 
adaptations  of  birds  and  flowers  to  the  highest  leadership  in  men.  Re- 
production is  only  one  of  its  many  functions;  and  the  man  who  assumes 
that  the  so-called  physical  desire  that  at  times  thrills  him  indicates  a 
need  of  sexual  intercourse  is  in  danger  of  depleting  and  wasting  from 
his  life  a  chief  source  of  physical  and  mental  power. 

-  The  single  standard  for  men  and  women  must  be  insisted  upon,  and 
the  parent  or  guardian  is  justified  in  demanding  a  clean  bill  of  health 
of  the  young  man  who  proposes  marriage.  The  young  man,  in  turn,  is 
entitled  to  the  same  from  his  prospective  father-in-law.  One  of  the 
defects  of  our  artificial  civilization  which  leads  to  harm  is  the  post- 
ponement of  the  marriage  age. 

To  denounce  youth  as  vicious  when  youth  has  merely  followed  the 
impulse  of  adolescence  is  futile,  because  youth  will  not  believe  this; 
other  and  juster  reasons  must  be  given,  if  youth  is  to  listen  and  be 
controlled.  Any  young  man,  properly  warned  and  properly  informed 
will  not  be  merely  w^illing  hut  anxious  to  learn  from  his  doctor  before 
marriage  if  he  is  fit  to  be  a  husband  and  a  father. 

Carnal  lust  may  be  cooled  and  quelled  by  hard  w^ork  of  the  body, 
as  well  as  attention  to  personal  hygiene — hence,  one  of  the  great  ad- 
vantages of  athletic  sports  for  growing  young  men. 


80  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

Personal  Hygiene. — Idleness,  stimulating  food,  overeating,  impure 
thoughts,  evil  associates,  and  alcohol  excite  the  passions  and  are  the  bed- 
fellows of  the  venereal  diseases.  Purity  of  mind  and  cleanliness  of 
body  are  helpful  prophylactics.  Physical  exercise  and  an  out-of-door  life 
divert  the  mind  and  help  the  body ;  it  is  a  good  safety  valve  for  the  excess 
animalism  of  youth.  A  full  diet  raises  basal  metabolism  and  stimulates 
sexual  desire,  whereas  a  low  diet  diminishes  procreative  interest  and 
power.^® 

The  public  should  be  taught  the  necessity  for  thorough  daily  cleans- 
ing of  the  external  genitals  in  both  sexes,  even  in  children.  The  large 
number  of  secreting  glands  and  the  decomposition  of  their  secretions 
are  liable  to  induce  irritation  and  even  minute  lesions  which  open  portals 
to  infection  of  all  kinds. 

Circumcision  is  recommended  as  an  aid  to  genital  cleanliness;  as  a 
prophylactic  against  syphilis  and  chancroid,  venereal  warts,  herpes,  and 
epithelioma,  balanitis  and  phimosis;  and  also  as  a  deterrent  to  mastur- 
bation. 

In  order  to  prevent  innocent  infections  it  is  necessary  to  educate  the 
public  to  place  chief  dependence  upon  personal  prophylaxis.  The  hazard 
of  kissing,  the  common  drinking  cup,  unsanitary  barbers,  and  the  un- 
hygienic practice  of  mouthing  pipes  and  other  things  must  become 
better  known. 

Alcohol. — The  strongest  indictment  against  alcohol  is  that  it  excites 
the  passions  and  at  the  same  time  diminishes  the  will  power.  The  fact 
that  alcohol  blunts  moral  tone  does  much  more  harm  than  all  the 
cirrhotic  livers,  hardened  arteries,  shrunken  kidneys,  inflamed  stomachs, 
and  other  lesions  believed  to  be  caused  by  its  excessive  use.  Alcohol  is 
not  a  stimulant,  but  depresses  the  higher  functions  of  the  brain  from 
the  beginning.     See  Index  for  references  to  Alcohol. 

Prostitution. — Any  sanitary  measures  taken  for  the  prevention  of 
venereal  diseases  which  do  not  include  some  method  for  treating  the 
problem  of  prostitution  are  doomed  in  advance  to  failure,  since  they 
will  ignore  the  main  source  and  root  of  these  diseases.  Fournier  ^^  states 
that  among  the  class  of  men  seeking  treatment  in  the  hospitals  of 
Paris,  72  per  cent,  of  all  syphilitic  infections  were  derived  from  regis- 
tered prostitutes,  25.1  per  cent,  were  derived  from  clandestine  prosti- 
tutes and  general  immorality,  and  only  2.7  per  cent,  of  these  infections 
from  adulterous  relations.  The  Chicago  Vice  Commission  states  that: 
"So  long  as  there  is  lust  in  the  hearts  of  men  it  will  seek  out  some 
method  of  expression.  Until  the  hearts  of  men  are  changed,  we  can 
hope  for  no  absolute  annihilation  of  the  social  evil."  While  waiting  for 
the  slow  evolution  that  aims  at  bettering  the  moral  fiber  of  mankind, 

«*  Miles,  Jour,  of  Neur.  and  Mental  Dis.,  Vol.  49,  No.  3,  March,  1919. 
^  Les  Chancres  Extragenitaux,  Paris,  1897. 


VENEREAL  PROPHYLAXIS  AND  HYGIENE  OF  SEX       81 

the  I'ollowiiii;-  four  ways  of  dealing  with  prostitution  have  been  at- 
tempted: (1)  laissez-faire,  (2)  suppression,  (3)  regulation,  and  (4) 
the  systematic  treatment  of  all  infected.  A  policy  of  non-interference 
satisfies  no  one.  Despite  the  didiculties  and  complexities  of  the  situa- 
tion, we  must  insist  that  prostitution  be  met  with  determined  but  humane 
action  to  lessen  its  extent  and  diminish  its  dangers.  Prostitution  must 
at  least  be  made  difficult  and  distant,  for  the  extent  of  the  patronage  is  in 
direct  ratio  to  its  accessibility.  The  elimination  of  prostitution  is  beyond 
the  dream  of  even  the  theoretical  reformer.  Any  program  must  take  into 
account  the  facts  that  a  great  nuijority  of  jirostitutes  are  feeble-minded. 

Suppression  does  not  suppress.  Virtue  cannot  be  secured  by  legisla- 
tion. Repressive  measures  drive  the  traffic  into  obscurity  and  reduce  it 
materially.  Vice  is  not  flaunted  in  public,  but  is  driven  into  corners 
Avhere  the  vicious  will  find  it,  but  where  it  will  not  entice  the  innocent 
and  unwary.  Between  the  flagrant  evil  of  segregation  and  the  im- 
perfections of  suppression,  the  choice  is  with  the  latter. 

Regulation  of  prostitution  by  means  of  medical  inspection  and  li- 
censure has  proven  a  failure  wherever  tried.  Regulation  implies  the 
absence  of  any  expectation  of  male  self-restraint;  it  is  society's  tacit 
assent  to  laxity.  Regulation  fails  because  it  makes  vice  easy,  gives  a 
false  sense  of  security,  and  does  not  reach  clandestine  prostitution.  The 
systematic  treatment  of  all  infected  persons,  especially  of  prostitutes, 
would  go  far  towards  diminishing  the  prevalence  of  venereal  disease. 
To  accomplish  this,  we  must  have  adequate  facilities  for  treatment. 
See  page  85. 

Segregation. — Theoretically,  every  case  of  syphilis  or  gonorrhea 
should  be  isolated  until  the  danger  of  infection  is  passed.  Practically, 
however,  segregation  is  impracticable  except  with  a  limited  number  of 
cases.  With  better  and  more  attractive  hospital  facilities  and  free  beds 
a  certain  amount  of  segregation  may  be  accomplished  voluntarily  and 
humanely.  An  alert  health  officer  can  trace  the  source  of  infection  in 
certain  cases,  aiid  induce  the  women  responsible  to  take  the  salvarsan 
treattoent  in  the  case  of  syphilis,  or  to  submit  to  hospital  care  in  the 
case  of  gonorrhea  or  chancroid. 

Sanitary  isolation  through  self  restraint  and  care  necessary  to  pre- 
vent the  infection  of  innocent  persons  must  be  taught  and  impressed 
upon  all  infected  individuals. 

Medical  Prophylaxis. — In  accordance  with  the  researches  of  Metch- 
nikoff  and  Roux  a  reasonably  efficient  prophylaxis  against  syphilis  is 
now  possible. 

Calomel  ointment  (331/3  per  cent.)  applied  within  an  hour  of  inter- 
course is  generally  effective  in  preventing  syphilitic  infection.  There 
are  several  more  or  less  efficient  irrigations  or  ointments  destructive 
to  the  gonococcus  if  used  soon  enough — the  silver  salts  being  the  best 


82  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

(2  per  cent,  protargol  or  10  per  cent,  argyrol).  Prophylaxis  is  there- 
fore possible,  but  it  takes  a  great  deal  of  care  and  vigilance,  and  the 
double  method  must  be  promptly  and  skillfully  applied  in  order  to  be 
effective.  It  has  been  used  with  success  in  armies  and  navies,  but  in 
civil  life,  where  strict  routine  and  control  of  men  are  impossible,  it  is  im- 
practicable except  in  individual  instances;  even  then  it  requires  time,  in- 
telligence, and  sobriety.  For  this  reason,  it  has  been  found  inadvisable 
to  furnish  soldiers  and  sailors  with  prophylactic  packages.^""  Better  re- 
sults are  obtained  by  shortening  leaves  of  absence  and  applying  the  pro- 
phylactic by  competent  attendants.  To  be  effective  it  should  be  applied 
within  six  hours  of  beginning  of  exposure ;  the  best  results  are  obtained 
when  used  within  one  hour. 

Method  of  Using  Prophylactic. — Before  intercourse  use  a  liberal 
amount  of  vaselin  or  other  lubricant.  This  aids  in  preventing  abrasions 
and  forms  a  coating  through  which  infectious  organisms  penetrate  with 
difficulty.     As  soon  as  possible  after  intercourse: 

1.  Wash  the  genitalia  thoroughly  with  soap  and  water,  using  plenty 
of  soap.  Soap  solution  is  a  spirocheticide,  and  there  is  good  evidence 
that  chancroid  infection  may  also  thus  be  avoided. 

2.  When  the  prophylaxis  is  performed  under  medical  instruction 
or  by  a  man  of  sufficient  intelligence  this  may  be  followed  by  a  wash  of 
1-1000  mercuric  chlorid.  The  efficacy  of  this  solution  is  undoubted, 
but  it  should  not  be  used  by  ignorant  persons,  nor  should  bichlorid  of 
mercury  tablets  be  issued  as  a  routine. 

3.  Dry,  and  apply  about  1  dram  of  33  per  cent,  calomel  ointment  in 
lanolin.  Anhydrous  lanolin  ^°^  should  not  be  used,  and  the  ointment 
should  be  most  thoroughly  mixed.  This  should  be  well  rubbed  in  for 
at  least  ten  minutes,  paying  particular  attention  to  the  glans,  corona  and 
prepuce,  but  neglecting  no  part  of  the  penis  and  the  anterior  portion  of 
the  scrotum.  This  should  be  rubbed  in  for  at  least  ten  minutes,  and 
should  not  be  removed  but  should  be  allowed  to  remain  for  12  hours, 
meanwhile  protecting  the  clothes  by  the  application  of  an  impervious 
paper  napkin.  This  favors  absorption  and  ensures  prolonged  action  of 
the  mercury  on  any  organisms  that  may  remain. 

4.  For  the  prevention  of  gonorrhea,  a  solution  of  argyrol  10  per 
cent,  or  protargol  2  per  cent,  should  be  injected  into  the  urethra. 

In  the  United  States  Navy  the  following  method  is  employed:  The 
entire  penis  is  scrubbed  with  liquid  soaj)  and  water  for  several  minutes 
and  then  washed  well  with  a  solution  of  mercuric  bichlorid,  1  to  2,000 
in  strength.  If  there  are  any  abrasions  present,  they  are  sprayed  with 
hydrogen  peroxid  from  a  hand  atomizer.     The  man  is  then  placed  in 

^""Package  K  of  the  Army;  and  Sanitube  of  the  Navy  containing  33%  per 
cent,  calomel  and  2  per  cent,  tricresol. 
"^Adeps  lanae  hydrosus,  see  page  66. 


VENEREAL  PROPPIYLAXIS  AND  HYOTENE  OF  SEX       83 

a  sitting  position,  well  forward  in  a  cliair  in  front  of  a  convenient  re- 
ceptacle, and  given  two  injections  of  a  10  per  cent,  solution  of  argyrol. 
He  is  required  to  retain  each  injection  in  the  urethra  for  five  minutes. 
After  taking  tlio  injections,  the  entire  penis  is  thoroughly  anointed  with 
a  33  per  cent,  calomel  ointment.  He  is  told  not  to  urinate  for  at  least 
two  hours,  and  to  allow  the  ointment  to  remain  on  tlie  penis  for  some 
hours.  A  temporary  dressing  is  placed  on  the  parts  to  protect  his 
clothes. 

Medical  prophylaxis  has  been  in  general  use  in  the  United  States 
Army  and  Navy  since  about  1908,  and  since  1912  the  use  of  prophylac- 
tics has  been  compulsory  in  the  army.  Many  officers  have  published 
their  opinions,  for  the  most  part  favorable,  and  a  few  have  furnished 
some  statistics. 

The  best  figures  on  this  subject  are  given  by  Riggs,^°-  who  records 
5,103  prophylactic  treatments  with  only  81  infections,  as  shown  by  the 
following  table: 


Hours    Subsequent   to 
Exposure 

Number  of 
Treatments 

Number  of  Infections 

(Syphilis,  Gonorrhea, 

Chancroid) 

Per  cent. 

of 
Infections 

1 

1,180 

1 

0.08 

2 

1,172 

7 

0.59 

3 

521 

4 

0.77 

4 

330 

2 

0.61 

5 

199 

3 

1.57 

6 

321 

5 

1.58 

7 

277 

6 

2.27 

8 

390 

16 

4.22 

9 

283 

10 

3.62 

10 

214 

11 

5.14 

More   than   10 

216 

16 

7.40 

Total..  5, 103 

81 

1.58 

.  There  were  1,180  treatments  during  the  first  hour  which  were  fol- 
lowed by  a  single  infection.  This  infection  was  carefully  investigated 
and  there  is  considerable  doubt  as  to  whether  it  was  genuine  or  not. 
The  disea-se  was  diagnosed  as  chancroid,  and  w^as  cured  in  two  days. 
These  figures  emphasize  the  importance  of  time — the  efficiency  of  the 
prophylactic  diminishes  as  the  time  increases.  Riggs  states  that  out  of 
3,556  prophylactic  treatments  there  were  only  67  infections,  and  of  these 
only  8  were  cases  of  syphilis. 

Ledbetter  ^°^  reports  that  at  Cavite,  before  medical  prophylaxis  was 
instituted,  the  percentage  of  venereal  diseases  of  all  classes  among  the 
men  averaged  from  25  to  30  per  cent,  annually,  and  at  times  even 
higher.  The  percentage  of  gonorrhea  was  reduced  to  8  per  cent,  an- 
nually, and  this  percentage  included  about  30  patients  w-ho  did  not  re- 

^"^  Social  Hygiene,  1917,  III,  299. 

^"'Ledbetter,  Robert  E.,  "Venereal  Prophylaxis  in  the  U.  S.  Xavy,"  Jour. 
A.  M.  A.,  April  15,  1911,  Vol.  LVI,  No.  15,  p.  1098. 


84  DISEASES  HAVING  SPECIAL  TROPHYLAXIS 

port  for  treatment.  Chancroid  was  reduced  from  5  to  2  per  cent., 
which,  included  2  patients  not  reporting  for  treatment.  Syphilis  has 
been  reduced  from  about  20  cases  annually  to  one  case  for  the  entire 
year  1910,  and  this  patient  did  not  report  for  prophylactic  treatment. 
The  results  speak  for  themselves  and  show  the  efficiency  of  the  prophy- 
lactic measures  if  properly  and  thoroughly  carried  out. 

Holcomb  and  Cather  ^°*  report  the  following  as  a  result  of  treatment 
used  by  them  in  3,268  persons  in  the  TJ.  S.  ISTavy  between  May  1,  1910, 
and  August  31,  1911.  Treatment  taken  within  eight  hours  after  ex- 
posure in  1,385  cases  shows  19  infections,  or  but  1.37  per  cent.  In  the 
interval  of  from  eight  to  twelve  hours  after  exposure  in  741  cases  shows 
25  infections,  or  3.31  per  cent.  Between  twelve  and  twenty-four  hours 
in  920  cases  shows  46  infections,  or  5  per  cent.  Of  the  56  cases  of 
gonorrhea  occurring  in  the  first  twenty-four-hour  interval,  ^6  were  re- 
current cases;  the  remaining  30  were  primary  infections. 

Eiggs  states  that  the  normal  expectancy  for  venereal  disease  re- 
sulting from  illicit  sexual  intercourse  not  followed  by  prophylaxis  is 
about  1  in  20  or  1  in  30.  The  expectancy  for  venereal  disease  when 
prophylaxis  is  used  depends  almost  entirely  upon  the  factor  of  time. 
The  absence  of  the  time  factor  in  a  set  of  prophylactic  statistics  invali- 
dates any  conclusion  that  may  be  drawn  concerning  probable  efficiency 
of  prophylaxis.  In  actual  practise  the  number  of  infections  appears  to 
be  reduced  by  nearly  one-half.  The  questionnaire  method  of  investiga- 
tion, in  which  the  identity  of  the  individual  is  concealed,  has  proved 
unreliable  and  the  results  obtained  cannot  be  accepted  with  any  con- 
fidence as  to  their  accuracy.  Furthermore,  many  of  the  reported  results 
are  difficult  to  analyze  on  account  of  lack  of  accurate  data,  and  especially 
lack  of  control  figures.  ^°^ 

The  use  of  salvarsan  early  in  syphilis  will  prevent  the  further  spread 
of  the  infection. 

Mechanical  Methods. — The  condom  was  introduced  late  in  the  17th 
or  early  in  the  18th  century  in  England.  It  was  described  by  Turner 
in  1717,  who  attributed  its  invention  to  a  Dr.  Condom,  from  whom  the 
device  was  named.  Le  Pileur,  who  has  made  a  study  of  this  literature, 
questions  the  existence  of  Dr.  Condom,  and  thinks  it  more  probable  that 
the  name  is  derived  from  the  Latin  verb  condere,  meaning  to  hide  or 
to  protect.  Most  authorities  agree  that  the  use  of  a  condom  is  an  al- 
most certain  protection  against  venereal  infection,  being  even  more  re- 
liable than  prophylactic  ointments.  In  regard  to  the  protection  afforded, 
we  may  conclude  that  the  condom  if  properly  tested  and  made  of  good 
rubber  will  afford  practically  complete  protection  to   anyone  who  can 

^»^  Holcomb,  E.  C,  and  Cather,  D.  C,  U.  S.  N.,  "Study  of  3,268  Venereal 
Prophylactic  Treatments,"  Jotir.  A.  M.  A.,  Vol.  LVIII,  No.  5,  February  3,  1912, 
p.  368. 

"=U.  S.  Naval  Med.  Bull.,  1921,  Vol.  XV,  No.  1. 


VENEREAL  PKOPHYLAXIS  AND  HYGIENE  OF  SEX       85 

obtain  and  will  use  it,  and  it  may  therefore  be  recommended  to  those  in- 
dividuals who  persist  in  immorality  in  spite  of  advice  to  the  contrary. 

Specific  Treatment. — From  the  standpoint  of  preventing  syphilis,  the 
treatment  of  the  infected  is  perhaps  the  most  efficacious  single  method 
that  can  be  applied.  It  is  obvious  that  if  all  infected  individuals  are 
rendered  incapable  of  transmitting  their  infection,  the  disease  will  dis- 
appear. Notification,  early  recognition,  and  prompt  treatment,  there- 
fore, become  our  most  important  prophj'lactic  measures  against  syphilis. 

Salvarsan  (arsphenamine  and  related  arsenical  compounds)  promptly 
kills  the  spirochetes  in  the  chancre,  mucous  patches  and  other  exposed 
lesions,  and  thereby  destroys  the  focus  of  infection.  Salvarsan  promptly 
used  is  a  specific  and  a  preventive,  even  though  some  of  the  parasites 
hidden  in  the  cells  of  the  inner  organs  escape  destruction.  Unfor- 
tunately, salvarsan  has  always  been  a  drug  of  the  proprietary  class, 
made  in  an  atmosphere  of  mystery,  under  a  patent  giving  an  imperfect 
account  of  its  preparation,  produced  at  small  cost  and  sold  at  a  very 
high  price.  Eecent  efi'orts  in  this  country  to  make  and  distribute  this 
chemical  free  of  charge  in  the  same  way  that  antitoxins  and  vaccine 
virus  are  distributed  by  boards  of  health  is  a  commendable  public  health 
measure. 

The  danger  of  syphilis  to  the  community  or  individual  is  increased 
in  proportion  to  the  inadequacy  of  the  treatment  received  by  those  suf- 
fering with  the  disease.  The  possibility  of  controlling  the  amount  of 
syphilis  acquired,  whether  by  prostitution  or  general  immorality,  by 
means  of  enforced  systematic  treatment,  has  not  yet  been  given  the  se- 
rious consideration  that  the  subject  merits.  When  proper  facilities  are 
afforded  the  poor  for  the  treatment  of  this  class  of  diseases,  one  of  the 
main  props  of  the  quack  will  have  been  removed.  The  Massachusetts 
State  Department  of  Public  Health  has  made  and  distributed  arsphena- 
mine free  of  charge  since  December,  1917. 

Hospitals  and  Clinics. — Pontoppidan,  on  the  basis  of  his  large  expe- 
rience with  the  Danish  system,  estimates  that  1  bed  to  2,000  of  the  pop 
ulation  is  insufficient  to  care  for  sexual  diseases.  Stokes,^"®  says  that  in 
1914  it  was  estimated  that  the  city  of  London,  with  7,000,000  inhabi- 
tants, had  only  163  beds  available  for  the  treatment  of  venereal  disease, 
and  the  same  condition  obtained  throughout  Great  Britain.  Of  30  gen- 
eral hospitals  in  New  York  City,  a  recent  investigation  showed  that  only 
10  received  recognized  cases  of  s}T)hilis;  13  of  30  will  not  receive  medi- 
cal cases  with  complications  of  s}'philis  or  gonorrhea.  Chicago  has  200 
beds  in  the  Cook  Coimty  Hospital  for  2,000,000  people.  All  the  con- 
temporary comment  clearly  indicates  that  the  attitude  of  the  general 
hospital  toward  syphilis  and  other  venereal  diseases  is  slowly  changing. 
Special  hospitals  for  the  treatment  of  venereal  diseases  will  not  serve  the 

^"Wour.  A.  M.  A.,  1916,  LXVII,  1960. 


86  DISEASES  HAYING  SPECIAL  PEOPHYLAXIS 

purpose,  for  while  a  patient  might  go  to  a  general  hospital  for  the 
treatment  of  these  conditions,  very  few  would  seek  assistance  in  a  hos- 
pital openly  devoted  to  the  treatment  of  venereal  diseases  because  of  the 
stigma  necessarily  attached.  Every  general  hospital  should  have  wards 
assigned  for  the  treatment  of  syphilis  and  gonorrhea.  Beds  are  neces- 
sary in  order  that  salvarsan  or  similar  drugs  may  be  administered  un- 
der proper  safeguards,  No  patient  would  occupy  a  bed  long,  since 
salvarsan  usually  causes  a  prompt  disappearance  of  external  lesions.  It 
will  be  generally  admitted  that  present  facilities  are  sadly  deficient,  and 
that  the  extension  of  those  facilities  should  be  among  the  first  steps  to 
be  taken  to  control  this  disease. 

Summary. — Finally,  in  considering  venereal  prophylaxis,  it  should 
be  remembered  that  these  diseases  are  of  great  antiquity  and  seem  likely 
to  continue  indefinitely;  that  they  already  affect  a  large  number  of  the 
population,  and  are  spreading;  that  the  existing  means  for  the  treat- 
ment of  them  among  the  poor  is  insufficient ;  that  the  common  mode  of 
propagation  is  irregular  and  illicit  intercourse;  that  prostitution  arose 
in  response  to  the  strongest  instincts  and  passions  in  the  human  breast ; 
and  that  prostitutes  themselves  need  protection  and  have  claims  on  the 
humanity  of  the  law.  Furthermore,  Lecky  thinks  that  "The  prostitute 
is  ultimately  the  efficient  guardian  of  virtue." 

To  diminish  the  amount  of  venereal  infection  requires  education  and 
publicity,  notification,  laboratory  facilities  for  diagnosis,  dispensary  and 
hospital  facilities,  public  health  nurses  and  social  service,  and  good 
laws  actively  administered.  Medical  schools  should  give  more  time  to 
the  diagnosis  and  handling  of  early  syphilis,  since  at  this  time  the  best 
results  in  treatment  and  prevention  can  be  offered.  A  stricter  super- 
vision of  barber  shops,  restaurants,  hotels,  soda  water  fountains,  in- 
fant asylums  and  schools  should  be  maintained;  prostitution  should  be 
made  difficult  and  distant  and  early  treatment  of  all  cases  instituted. 
Medical  prophylaxis  should  be  better  understood  and  the  importance 
of  personal  hygiene  impressed.  Insistence  should  be  stressed  upon  con- 
tinence and  efforts  made  to  improve  the  moral  and  physical  fiber  of  man- 
kind. 

REFERENCES 

The  American  Social  Hygiene  Association,  105  West  40th  Street,  New  York 
City.  Popular  prints.  Also  the  publications  of  the  IJ.  S.  Public  Health 
Service. 

Social  Hygiene.    Pub.  by  the  Am.  Soc.  Hyg.  Assn.,  New  York  City. 


PREVENTABLE  BLINDNESS 


PREVENTABLE  BLINDNESS 

Preventable  blindness  is  considered  in  this  place  because  the  largest 
single  factor  causing  needless  loss  of  eyesight  is  gonorrhea.  Among 
the  infectious  eye  troubles  llie  most  destructive  is  ophthalinia  neona- 
torum. 

There  were  04,000  registered  blind  persons  in  the  United  States,  ac- 
cording to  the  census  of  1910.^"'  Ten  per  cent,  (between  six  and  seven 
thousand)  arc  blind  as  the  result  of  ophthalmia  neonatorum.  From 
25  to  30  per  cent,  of  all  the  blind  children  in  all  the  blind  schools  of 
this  country  owe  tlieir  infliction  to  gonorrhea.  It  has  been  estimated 
that  probably  one-half  of  the  blindness  in  the  world  is  preventable. 

Emphasis  upon  the  great  harm  done  by  ophthalmia  neonatorum 
should  not  blind  us  to  the  fact  that  there  are  other  causes  of  blindness 
and  eye  deterioration  which  are  preventable;  thus  we  have  to  consider 
the  later  pus  infections,  also  syphilis,  tuberculosis,  smallpox,  trachoma, 
sympathetic  inflammations,  industrial  accidents,  accidents  at  play,  pro- 
gressive near-sightedness  caused  by  violation  of  ocular  hygiene,  and  a 
variety  of  inflammatory  conditions.  Functional  disturbances  of  vision 
(toxic  amblyopia)  followed  in  severe  cases  by  atrophy  of  the  optic  nerve 
and  permanent  blindness  may  be  brought  about  by  poisoning  with  lead, 
wood  alcohol,  tobacco,  and  other  poisons.  This  form  of  dimness  of 
vision,  or  even  loss  of  sight,  occurs  rather  frequently,  and  in  most  in- 
stances is  preventable. 

One  of  the  common  causes  of  impaired  sight  is  phlyctemdar  heraiitis 
which  leaves  scars  on  the  cornea.  This  condition  is  often  associated 
with  tubercular  glands  of  the  neck  and  is  probably  a  form  of  bovine 
tuberculosis,  hence  preventable. 

OPHTHALMIA  NEONATORUM 

Ophthalmia  neonatorum  or  inflammation  of  the  eyes  of  the  new- 
born includes  all  the  inflammatory  conditions  of  the  conjunctiva  that 
occur  shortly  after  birth — usually  before  the  end  of  the  first  month. 
The  conjunctivae  of  the  newborn  are  peculiarly  liable  to  infections. 
The  gonococcus  is  usually  the  cause  of  severe  conjunctivitis  occurring  in 
a  baby  a  few  days  old.  The  gonococcus  causes  about  60  per  cent,  of  all 
cases,  mild  and  severe. 

^'"  These  figures  we  now  believe  are  altogether  too  low.  Green  states  that  in 
Massachusetts  only  about  53  per  cent,  of  the  actual  cases  had  been  recorded, 
and  estimates  the  total  blindness  in  the  United  States  to  be  not  less  than 
118,999.  The  figures  vary  greatly,  because  there  is  no  accepted  rule  as  to  what 
constitutes  blindness.  A  watchmaker  would  be  practically  blind  with  vision 
ample  for  a  masoa. 


88  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

Ophthalmia  neonatorum  is  not  always  gonorrheal,  but  may  be  pro- 
duced by  other  virulent  microorganisms  or  by  irritating  substances.  The 
microorganisms  other  than  the  gonococcus  that  sometimes  cause  conjunc- 
tivitis during  the  early  days  of  life:  pneumococci,  streptococci,  men- 
ingococci, the  Koch-Week's  bacillus,  the  diphtheria  bacillus,  and  even 
staphylococci.  These  are  relatively  so  rare  or  benign  that  we  may  dis- 
regard their  etiological  signiiicance  for  our  present  purpose.  The  diag- 
nosis of  gonorrheal  ophthalmia  may  readily  be  made  by  simply  examin- 
ing a  stained  smear  of  the  secretion  for  Gram-negative,  biscuit-shaped 
diplococci,  although  in  rare  cases  infection  with  the  micrococcus  catar- 
rhalis  may  cause  confusion. 

The  infection  commonly  occurs  during  the  passage  of  the  child 
through  the  genital  tract  of  the  mother  and  usually  just  before  delivery. 
It  is  caused  by  the  entrance  of  the  vaginal  secretion  containing  gonococci 
into  the  conjunctival  sac.  It  may  also  occur  after  delivery  by  infected 
hands,  towels,  sponges,  or  other  objects. 

The  disease  varies  in  severity;  sometimes  it  is  very  mild,  with  slow 
onset  and  spontaneous  recovery.  Usually,  however,  it  is  severe  and 
serious.  The  inflammation  may  extend  from  the  conjunctiva  to  the 
cornea  leading  to  corneal  ulcers  and  partial  or  complete  loss  of  vision. 
In  a  typical  case  both  the  ocular  and  palpebral  conjunctivae  are  red 
and  very  much  swollen;  the  eyelids  and  surrounding  tissues  are  infil- 
trated and  there  is  a  thick,  creamy,  abundant  secretion. 

There  are  many  grades  of  mild  inflammatory  conditions,  which  must 
not  be  mistaken  for  gonorrhea.  At  birth  the  eyelids  are  almost  always 
glued  together  with  a  normal  sticky  secretion.  It  is  common,  too,  for 
the  lids  to  remain  red  and  sticky  for  a  day  or  so.  The  diagnosis  may 
be  made  in  a  few  minutes  by  a  microscopic  examination. 

Prevalence. — Kerr  calls  attention  to  the  fact  that  there  are  no  com- 
plete statistics  showing  the  prevalence  of  ophthalmia  neonatorum,  and 
only  an  approximate  idea  can  be  had  of  the  number  of  cases  by  study- 
ing the  admissions  to  schools  for  the  blind.  A  committee  of  the  Brit- 
ish Medical  Association  found  that  more  than  one-third  of  those  in 
blind  schools  of  Great  Britain  owed  their  affliction  to  this  disease.^"® 

In  the  United  States  and  Canada,  in  1907,  out  of  224  admissions  to 
10  schools  for  the  blind,  59,  or  24.38  per  cent.,  were  blind  as  a  result 
of  ophthalmia  neonatorum  ;^°^  and  out  of  351  admissions  to  certain 
schools  in  the  United  States  and  Canada  in  1910,  84,  or  23.9  per  cent., 
were  blind  from  this  cause.^^*' 

As  a  result  of  studies  made  of  ophthalmia  neonatorum  in  10  man- 
ufacturing cities  of  Massachusetts,  Greene  has  presented  figures  which 

^"^  British  Medical  Journal,  Mav  8,  1909.  , 

^"Wour.  A.  M.  A.,  May  23,  1909,  p.  1745. 
^"Jour.  A.  M.  A.,  July  ],  1911,  p.  72. 


PREVENTABLE  BLINDNESS  89 

show  that  the  minimum  morbidity  rate  for  this  disease  was  6.4  per 
1,000  births.  A  more  compk^te  oonsus  made  l)y  him  from  the  practice 
of  173  physicians  in  9  cities  revealed  an  average  morbidity  rate  of  10.8 
per  1,000  births."' 

It  is  estimated  that  tlie  total  annual  loss  from  gonorrheal  ophthalmia 
in  the  United  States  is  seven  million  dollars,  and  that  more  than  one 
million  dollars  annually  is  spent  in  partially  caring  for  its  victims.  A 
blind  child  costs  the  community  an  excess  of  about  $4,500  for  its  school- 
ing. 

Prevention. — Crede's  Method. — Crcde  in  1881  introduced  an  effi- 
cient method  of  preventing  ophthalmia  neonatorum  at  the  Lying-in 
Hospital  at  Leipzig,  thereby  connecting  forever  his  name  with  the  pre- 
vention of  the  disease  and  the  subsequent  saving  of  the  sight  of  many 
persons.  Crede's  original  method  consisted  simply  in  placing  one  or  two 
drops  of  a  2  per  cent,  solution  of  silver  nitrate  in  each  conjunctival  sac, 
as  soon  as  practicable  after  the  birth  of  the  head. 

In  order  to  prevent  gonococcic  as  well  as  other  infections  of  babies' 
eyes,  the  following  procedure  is  recommended:  During  pregnancy 
women  should  be  instructed  to  practice  daily  external  cleansing  with 
soap  and  water  and  a  clean  wash-cloth.  In  case  of  any  irritating  dis- 
charge or  even  profuse  white  discharge,  a  physician  should  at  once  be 
consulted. 

Immediately  after  labor  the  eyelids  should  be  carefully  cleaned  with 
sterile  absorbent  cotton  or  gauze  and  a  saturated  solution  of  boric  acid. 
A  separate  pledget  should  be  used  for  each  eye  and  the  lids  washed  from 
the  nose  outward  until  quite  free  of  all  mucus,  blood,  or  meconium 
without  opening  the  lids.  Next  the  lids  should  be  separated  and  one  or 
two  drops  of  a  1  per  cent,  silver  nitrate  solution  should  be  dropped  into 
each  eye,  between  the  outer  ends  of  the  lids.  The  lids  should  be  sep- 
arated and  elevated  away  from  the  eyeball  so  that  a  lake  of  silver  nitrate 
solution  may  lie  for  one-half  minute  or  longer  between,  them,  coming 
in  contact  with  every  portion  of  the  conjunctival  sac.  One  application 
only  of  the  silver  nitrate  should  be  made,  and  ordinarily  no  further  at- 
tention need  be  given  to  the  eyes  for  several  hours.  Each  time  the  child 
is  bathed  the  eyes  should  first  be  wiped  and  cleaned  with  pledgets  of 
sterile  absorbent  cotton  wet  with  a  saturated  solution  of  horacic  acid. 

Crede  used  a  2  per  cent,  solution  of  silver  nitrate,  but,  as  this  is 
sometimes  irritating,  a  1  per  cent,  solution  is  now  commonly  employed, 
and  seems  to  afford  equally  efficient  protection.  The  silver  nitrate  solu- 
tion should  be  instilled  into  each  conjunctival  sac  but  once.  Eepeated 
applications  may  cause  serious  inflammations.  In  fact,  a  single  treat- 
ment  sometimes    causes    a    conjunctivitis,    known    as    "silver    catarrh." 

^^  Monograph  Series  of  Hie  American  Association  for  Conservation  of  Vision, 
Vol.  I,  Xo.   1. 


90  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

Other  prophylactic  substances  have  been  proposed.  The  best  substitutes 
are  the  newer  silver  compounds,  as  argyrol,  which  is  a  collodial  silver 
(25  per  cent.),  or  protargol  (3  per  cent.).  The  following  have  also 
been  recommended:  Bichlorid  of  mercury,  1-3,000  or  1-5,000,  silver 
acetate,  0.23  per  cent.,  recommended  by  Zweifel,  who  used  it  in  5,222 
cases.  Schmidt  and  Eimpler  recommend  aqua  chlorini.  Carbolic  acid  (1 
per  cent.)  or  other  antiseptics  have  also  been  tried.  ISTo  substance,  how- 
ever, is  known  to  be  as  reliable  as  silver  nitrate,  which  should  be  used 
in  all  cases  where  there  is  any  reason  for  believing  that  the  mother  is 
infected  with  the  gonococcus. 

There  is  no  specific  treatment  for  this  disease.  While  silver  nitrate 
and  the  various  silver  preparations  are  undoubtedly  effective  as  pro- 
phylactics, when  once  the  organisms  have  penetrated  the  tissues  these 
agents  can  no  longer  reach  them  in  effective  concentration  and  hence 
are  useless  in  treatment.  They  are,  however,  still  generally  used  for  this 
purpose.  The  disease  is  practically  self  limited,  but  the  frequency  of 
corneal  complications  can  be  greatly  reduced  by  frequent  irrigations 
with  non-irritating  solutions,  such  as  boric  acid  or  normal  saline  solution. 
Great  care  should  be  taken  not  to  abrade  the  cornea. 

As  a  general  rule,  it  is  advisable  to  use  a  prophylactic  as  a  matter 
of  routine  in  hospital  and  private  practice.  To  use  Crede's  method  upon 
every  case  necessitates  the  unpleasant  suspicion  that  every  woman  is  a 
possible  source  of  gonococcus  infection.  If  statements  of  the  father 
about  his  previous  life  can  be  relied  upon,  an  eye  prophylactic  may  be 
omitted.  In  his  private  work  Williams  uses  a  boric  acid  solution  ex- 
cept where  there  is  special  reason  for  believing  that  the  mother  has 
gonorrhea.  The  responsibility  for  risking  the  baby's  eyes  rests  upon  the 
medical  attendant.  There  can  only  be  one  safe  rule  in  case  of  doubt. 
It  should  be  remembered  that  gonococcic  infections  of  the  conjunctiva 
occur  in  about  one  to  every  two  hundred  births  (Edgar). 

The  good  results  of  Crede's  method  are  sufficiently  convincing  to 
justify  criminal  proceedings  upon  those  who  fail  to  apply  this  simple 
prophylactic.  Crede  reduced  ophthalmia  neonatorum  in  the  Leipzig 
Lying-in  Hospital  from  10.8  per  cent,  to  0.1  per  cent.  Haab  reduced  the 
frequency  of  ophthalmia  neonatorum  in  hospital  practice  from  9  to  1  per 
cent.,  while  the  statistics  of  many  hospitals  show  only  a  very  small 
fraction  of  1  per  cent.  At  the  Sloane  Maternity  Hospital  in  New  York, 
there  were  4,660  births  during  a  period  of  6  years,  in  which  Crede's 
method  was  carried  out  without  a  single  case  of  ophthalmia.  Stephen- 
son's results  are  typical.  In  2,265  births,  ophthalmia  neonatorum  de- 
veloped in  10  per  cent,  of  the  cases  preceding  the  use  of  Crede's  method. 
In  1,160  births  after  this  method  only  0.17  developed  any  trouble. 

The  technic  of  applying  the  nitrate  of  silver  is  very  important,  for, 
in  the  opinion  of  Edgar,  when  ophthalmia  neonatorum  develops  after 


PREVENTABLE  BLINDNESS  91 

the  use  of  nitrate  of  silver,  it  is  due  either  to  a  secondary  infection  or  to 
the  fact  that  the  solution  does  not  really  bathe  the  mucous  membranes, 
but  remains  upon  the  lashes.  The  lids  must  be  everted  and  the  silver 
solution  placed  in  the  conjunctival  sac  either  from  a  glass  rod  or  a 
pipette.  Care  must  be  taken  not  to  touch  or  injure  the  delicate  mem- 
brane. 

Crede's  method  does;  not  strike  at  the  root  of  the  evil.  It  would,  of 
course,  be  much  better  to  eradicate  gonorrhea  from  men  and  women 
than  to  be  compelled  to  drop  silver  nitrate  into  babies'  eyes.  Wrapped 
up  with  the  question  of  ophthalmia  neonatorum  is  the  question  of  mid- 
wives,  for  to  prevent  blindness  we  must  have  intelligent  and  conscien- 
tious obstetrical  atendants,  especially  for  the  poor  and  i.cfnorant  cla.<ses. 
Midwifery  practice  needs  regulation,  supervision,  and  elevation.  Educa- 
tion is  one  of  the  bulwarks  of  prevention  in  this  as  well  as  other  pre- 
ventable infections. 

Legislation. — Ophthalmia  neonatorum  is  an  instance  in  which  ''the 
protection  of  the  citizen  from  the  assaults  of  ignorance,  indifference,  or 
neglect,  when  they  threaten  his  well-being  and  even  his  economic  ef- 
ficiency, is  a  duty  which  the  state  cannot  evade  and  which  he  has  a  right 
to  exact." 

Laws  for  the  prevention  of  the  blindness  of  newborn  infants  are  mak- 
ing progress  slowly.  Many  states  have  now  made  prophylaxis  com- 
pulsory. In  some  states  the  nurse,  midwife,  or  parent  is  required  to  re- 
port the  disease,  in  other  states  the  attending  physician. 

Maine  was  the  first  state  to  take  legal  steps  in  1891  to  control 
ophthalmia  neonatorum.  In  1892  Xew  York  followed,  with  an  amend- 
ment to  the  law  relative  to  midwives  and  nurses.  Subsequently  most  of 
the  other  states  took  legislative  action.^^^    The  provisions  of  the  several 

"^Kerr,  J.  W.,  '"Ophthalmia  Neonatorum:  An  Analysis  of  the  Laws  and 
Regnilations  Relating  Thereto  in  Force  in  the  United  States,"  Public  Health 
Bull.  Xo.  Jf9,  U.  S.  P.  H.  &  M.  H.  S.,  October,  1911. 

The  Massachusetts  law  reads  as  follows: 

Section  49.  .  .  .  Should  one  or  both  eyes  of  an  infant  become  inflamed, 
swollen  and  red,  and  show  an  unnatural  discharge  at  any  time  within  two 
weeks  after  its  birth,  it  shall  be  the  duty  of  the  nurse,  relative,  or  other 
attendant  having  charge  of  such  an  infant  to  report  in  writing  within  six 
hours  thereafter,  to  the  board  of  health  of  a  city  or  toAvn  in  which  the  parents  of 
the  infant  reside,  the  fact  that  such  inflammation,  swelling,  and  redness  of  the 
eyes  and  unnatural  discharge  exist.  On  receipt  of  such  report,  or  of  notice  of 
the  same  spnptoms  given  by  a  physician  as  provided  by  the  following  section, 
the  board  of  health  shall  take  such  immediate  action  as  it  may  deem  neoec- 
sary  in   order   that  blindness  may  be   prevented.     Whoever  violates  the  pro- 

VI.SIOXS  OF  THIS  SECTION  SHALL  BE  PUNISHED  BY  A  FIXE  OF  XOT  MORE  THAN  OXE 
HUXDRED  DOLLARS. 

Section  50.  ...  If  a  physician  knows  that  ...  if  one  or  both  eyes  of  an 
infant  whom  or  whose  mother  he  is  called  to  visit  become  inflamed,  swollen, 
and  red.  and  show  an  unnatural  discharge  within  two  weeks  after  birth  of  such 
infant,  he  shall  inmiediately  give  notice  thereof  in  writing  over  his  own  signa- 
ture to  the  selectmen  or  board  of  health  of  the  to^vn ;  axd  if  he  refl'SES  or  xeg- 

LECTS    TO   GIVE   SUCH   XOTICE.   HE    SHALL  FORFEIT   XOT  LESS   THAX   FIFTY  XOR    irORE 

THAX  TWO  HUXDRED  DOLLARS  FOR  EACH  OFFEXCE.      (Revised  Laws.  Chapter  75.) 


92  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

laws  are  quite  varied.  In  all  of  them,  however,  the  object  is  to  insure 
early  treatment,  and  to  this  end  compulsory  notification  is  generally  re- 
quired. The  health  authorities  of  many  states  furnish  prophylactic  out- 
fits to  physicians.  The  outfit  ordinarily  consists  of  a  small  vial,  protected 
from  the  light,  containing  a  1  per  cent,  solution  of  nitrate  of  silver,  a 
sterilized  dropper  and  bulb,  and  a  circular  of  instructions. 

In  3  years  following  the  enforcement  of  the  law  of  1911,  Massa- 
chusetts reduced  the  number  of  cases  of  blindness  from  this  cause  50 
per  cent.;  and  in  1919  and  1920  no  new  cases  of  blindness  from  gonor- 
rheal ophthalmia  occurred.  Good  results  are  also  evident  in  New  York 
and  wherever  intelligent  measures  are  vigorously  carried  out. 

In  order  to  make  material  progress  against  ophthalmia  neonatorum, 
as  well  as  against  infant  mortality,  it  is  essential  that  laws  require 
prompt  report  of  all  births ;  it  is  the  duty  of  the  health  authorities  to  see 
to  it  that  such  laws  are  effectively  carried  out. 

TRACHOMA 

Trachoma  is  a  menace  to  the  intregrity  of  sight.  It  is  a  specific, 
communicable,  destructive  inflammation  of  the  conjunctiva,  charac- 
terized by  the  formation  of  the  so-called  trachoma  granulations,  which 
may  be  either  papillary  or  follicular;  the  ultimate  formation  of  scar 
tissue;  marked  chronicity  and  intractability  to  all  forms  of  local  treat- 
ment. The  disease  has  been  transmitted  experimentally  in  human  be- 
ings and  possibly  also  in  apes,  but  neither  the  degree  nor  the  nature  of 
its  contagiousness  is  understood.  The  virus  of  trachoma  is  probably 
frail.  Important  factors  in  communicability  are  poor  hygienic  surround- 
ings and  lowered  resistance  from  any  cause,  Avhich  accounts  for  the  slow 
and  uncertain  manner  in  which  the  disease  spreads  in  families.  The 
disease  may  occasionally  be  confined  to  one  eye. 

The  filtrability  of  the  virus  of  trachoma  remains  undetermined. 
Experimental  evidence  permits  no  more  than  the  suspicion  that  the 
virus  may  be  filtrable  under  some  circumstances.  In  1907  Prowaczek  ^^^ 
described  the  so-called  inclusion  or  trachoma  bodies.  The  nature  of 
these  bodies  and  their  possible  etiologic  relation  to  trachoma  still  re- 
main undetermined.  Noguchi  and  Cohen  ^^*  have  reported  the  suc- 
cessful cultivation  of  these  inclusion  bodies,  but  since  the  cultivated 
bodies  proved  non-pathogenic  the  question  still  remains  an  open 
one. 

Trachoma  flourishes  best  where  sanitary  conditions  are  worst;  it  oc- 
curs chiefly  among  the  overcrowded,  underfed  and  overworked.     The 

"^  Halberstadter  and  Prowaczek.  Deut.  med.  Wochnschr.,  1907,  XXXIII, 
1285,  Arb.  a.  d.  Tc.  Oesundheitsamte,  1907,  XXVI,  44. 

"*  "Experiments  on  Cultivation  of  So-Called  Trachoma  Bodies,"  Jour.  Exp. 
Med.,  1913,  XVIII,  No.  5. 


TRACHOMA  93 

diagnosis  rests  upon  the  history  and  ilu>  appearance  of  the  lesions,  es- 
pecially scar  tissue,  papillary  <j:ranu  hit  ions,  trachoma  follicles  and  pan- 
nus  of  the  cornea. 

Trachoma  presents  varying-  rliniial  aspects,  and  as  there  is  no  cri- 
terion of  the  disease,  errors  in  diagnosis  arc  frequent.  It  should  be 
differentiated  from  other  infiannnatory  conditions  of  the  conjunctiva, 
especially  from  follicular  cvnjunclirilis.  wiiich  is  benign;  from  vernal 
catarrh.  Avhich  is  accompanied  by  a  poiuliar  })avement-like  appearance 
and  ])ron()uneed  subjective  symptoms  during  the  first  M-arm  davs  o[ 
spring;  from  Parinaud's  conjunctivitis,  which  is  an  acute  febrile  disease, 
with  glandular  enlargements,  and  conjunctivitis  usually  limited  to  one 
eye. 

Impairment  of  vision  can  be  prevented  and  often  greatly  improved 
by  surgery — grattage.  Adults  who  for  years  have  been  burdens  to  them- 
selves and  often  charges  on  the  community,  and  children  who  have 
been  compelled  to  remain  out  of  school  have  been  "cured"  by  surgical 
methods.  Free  trachoma  hospitals  have  been  established  in  Kentuck}^ 
Virginia,  "West  Virginia,  Tennessee,  and  Xorth  Dakota. ^^^ 

A  case  cannot  be  said  to  be  cured  until  all  the  conjunctiva  of  the 
upper  lids  has  become  replaced  by  smooth,  white,  avascular,  fibrous  scar 
tissue,  and  the  lower  lids  are  free  from  any  evidence  of  disease.  The 
control  of  trachoma  consists  in  eliminating  the  foci  of  the  disease,  im- 
proving personal  hygiene,  and  community  sanitation.  The  disease  is 
slow  and  insidious  in  its  development;  acute  or  fulminating  cases  are 
rare.  Impairment  of  sight  is  due  to  involvement  of  the  cornea,  especially 
to  scars  resulting  from  recurring  corneal  ulcers. 

The  infection  is  rubbed  into  the  eye  by  roller  towels,  handkerchiefs, 
fingers,  and  other  ways.  "When  once  established,  the  disease  is  chronic, 
and  permanent  cures  are  doubtful. 

-  Trachoma  is  much  more  prevalent  in  the  "United  States  than  is  ordi- 
narily supposed.  It  is  not  an  exotic  disease,  but  a  public  health  problem 
of  some  magnitude  in  many  states.  The  public  eye  clinics  of  Chicago 
are  filled  with  patients  showing  the  resulting  deformities.  Wilder  located 
a  center  in  southern  Illinois,  and  it  has  also  been  found  in  the  moun- 
tains of  Kentucky  and  Tennessee,  while  in  Oklahoma  this  disease  has 
become  a  public  menace.  It  is  more  or  less  prevalent  in  the  poorer  sec- 
tions of  all  the  larger  centers. 

Trachoma  is  of  such  a  serious  nature  that  all  immigrants  arriving  at 
our  shores  have  their  eyelids  everted  and  conjunctivae  examined  for 
evidence  of  this  infection.  An  alien  immigrant  arriving  with  trachoma 
is  deported,  and  the  steamship  is  liable  to  a  fine  of  one  hundred  dollars 
for  bringing  every  case  of  trachoma  where  it  can  be  shown  that  the 
disease  might  have  been  recognized  at  the  port  of  departure. 

,-         i«J.  A.  M.  A.,  October  23,  1920,  p.  1109. 


94  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 


TOXIC  AMBLYOPIA 

Toxic  amblyopia^  may  be  caused  by  wood  alcohol,  tobacco,  lead, 
quinin,  salicylic  acid,  male  fern,  santonin,  iodoform,  atoxyl  (arsenilic 
acid  and  derivatives),  and  also  digitalis. 

Wood  alcohol,  Columbian  spirits,  methyl  alcohol  (CH3OH), 
causes  blindness  through  atrophy  of  the  optic  nerves.  As  small  a  quan- 
tity as  a  teaspoonful  has  caused  loss  of  vision.  Blindness  may  even  be 
caused  by  inhaling  the  vapor.  Quantities  as  small  as  0,2  per  cent,  in 
the  inspired  air  may  accumulate  in  the  body  and  cause  toxic  effects. 
Wood  alcohol  is  used  as  an  adulterant,  especially  in  liquors  and  lotions, 
and  also  in  industry  as  a  solvent.  It  should  be  prohibited  in  any  form 
of  material  used  for  internal  or  external  use  on  the  human  body.  Ample 
ventilation  should  be  provided  in  all  works  where  wood  alcohol  is  made 
or  used,  as  in  brewery  vats.  Containers  in  which  wood  alcohol  is  mar- 
keted should  have  suitable  display  of  labels  of  warning. 

The  very  selective  effect  of  wood  alcohol  is  shown  by  the  way  it 
poisons  specifically  only  those  fibres  of  the  optic  nerve  which  are  con- 
nected with  the  macula,  lutea  in  the  retina,  the  seat  of  direct  and  most 
acute  vision,  other  portions  of  the  retina  and  optic  nerve  escaping.  In 
severe  cases,  total  atrophy  of  the  fibres  occurs. 

Tobacco. — When  tobacco  impairs  sight,  it  is  always  the  result  of 
a  combination  of  several  circumstances :  (1)  adult  life;  (2)  absorption 
of  a  large  quantity  of  nicotin,  either  by  smoking,  chewing  or  taking  snuff 
to  excess,  or  by  prolonged  handling  of  tobacco  by  workers  in  the  weed ; 
(3)  disturbed  digestion  which  may  be  an  indirect  consequence  of  to- 
bacco abuse;  and  (4)  too  free  use  of  alcohol.  Individuals  vary  greatly 
in  susceptibility.  The  symptoms  are  dimness  of  sight  and  a  loss  of  color 
sense  in  central  vision.  This  is  the  cause  of  some  marine  and  railroad 
accidents. 

The  use  of  tobacco  becomes  largely  a  habit.  Few  gain  the  pleasure 
and  solace  from  it  which  they  crave  and  expect;  on  the  other  hand,  to- 
bacco is  in  no  way  a  help  to  health.  Under  ordinary  circumstances, 
smoking  three  or  four  moderately  strong  cigars  a  day  should  suffice  as 
a  maximum;  at  least,  this  amount  is  not  likely  to  cause  trouble  with 
vision. 

ACCIDENTS 

Accidents. — In  New  York  State  about  200  industrial  accidents 
resulting  in  total  blindness  occur  annually.  Besides  this,  there  are  a 
large  number  of  accidents  occurring  on  railroads,  in  construction  work, 
and  in  the  field  and  forest. 

Many  of  the  accidents  to  the  eyes  occurring  in  factories  are  pre- 


TETANUS  95 

venlable  through  the  use  of  nifchanical  guards  or  goggles.     As  a  rule, 
the  majority  of  such  accidents  are  due  to  small  flying  particles. 

A  material  proportion  of  blindness  is  caused  by  accidents  to  children 
at  play;  sometimes  the  eyeball  is  torn  by  a  buttonhook,  or  pierced  by  a 
knife  or  awl;  or  a  scissors  blade,  used  to  untie  a  knot,  slips.  Some 
eyes  have  been  injured  by  the  crack  of  a  whip,  by  a  shot  from  an  air-gun 
or  toy  pistol.  Accidents  also  occur  to  the  eyes  from  fireworks,  curling 
tongs,  a  child's  finger  scratching  the  parent's  cornea,  or  a  doll's  china 
head  broken  into  the  eyes  of  its  tumbling  "mother." 

Many  cases  of  blindness  were  caused  by  the  gases  used  in  the  World 
War. 

Ocular  Hygiene,  see  page  91G. 

COLLATERAL  READING 

National  Com.  for  the  Prevention  of  Blindness,  130  E.  22nd  St.,  N.  Y.  C. 
Popular  prints. 

TETANUS 

(Locl-jaiv) 

Compared  with  the  major  plagues  of  man,  lockjaw  has  always  been 
a  rare  disease.  It  is  on  account  of  the  characteristic  and  fatal  spasms 
that  it  early  attracted  attention.  The  student  will  be  well  repaid  by  a 
study  of  the  historical  development  of  the  theories  that  have  been  ad- 
vanced since  the  time  of  Hippocrates  to  explain  the  cause  of  tetanus. 
These  theories  mirror  the  prevailing  thought  upon  the  nature  of  dis- 
ease as  it  developed  from  that  of  evil  spirits,  through  the  humoral 
theory,  the  realm  of  miasms  and  noxious  effluvia,  to  the  germ  theory. 
Tetanus  could  not  escape  the  rheumatism  theory  which  has  been  such 
an  alluring  catchall  for  symptoms  and  diseases  difficult  of  explanation. 
"Taking  cold"  was  assigned  its  usual  role  here  as  elsewhere.  When  no 
assignable  cause  seemed  at  hand,  the  disease  was  given  the  learned  title 
— idiopathic  tetanus. 

Etiology. — Carle  and  Eattini,^^^  in  1884,  first  clearly  demonstrated 
the  infectious  nature  of  tetanus  by  inoculating  rabbits  subcutaneously 
with  pus  from  a  human  case  of  the  disease.  In  the  same  year,  Xico- 
laier  ^^^  inoculated  laboratory  animals  subcutaneously  and  saw  the  tetanus 
bacillus  at  the  site  of  injection.  In  1889,  Kitasato  "*  for  the  first  time 
grew  the  organism  in  pure  culture,  and  by  successful  inoculation  ex- 
periments proved  that  this  bacillus  was  the  real  cause  of  tetanus.  Kita- 
sato further  showed  that  the  tetanus  bacillus  is  not  found  in  the  heart's 

"°  Giornale  della   T.  acad.  di  Med.  di  Torino. 

^"  Deutsch.   med.  Wchnschr.,   1884,  No.   52:   Inaug.  Diss.,  Gottingen,   1885. 

^''Deutsch.  med.  Wchnschr.,  1889,  No.  31:  Zt.schr.  f.  Hyg.,  1889,  VII,  225. 


96  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

blood  of  mice  dead  of  tetanus,  and  therefore  concluded  that  we  are  deal- 
ing with  an  intoxication,  and  not  bacteremia.  We  now  regard  tetanus 
as  a  type  of  the  true  toxemias;  that  is,  the  virus  remains  localized  in 
the  wound,  and  the  soluble  toxin  does  the  damage.  This  work  of  Kita- 
sato's  was  one  of  great  importance,  and  led  to  the  epochmaking  dis- 
covery of  Behring  and  Kitasato  ^^^  in  the  following  year  (1890)  upon 
tetanus  and  diphtheria  toxins  and  antitoxins,  laying  the  foundation  of 
serum  therapy. 

Tetanus  may  be  regarded  almost  solely  as  a  wound  complication. 
All  wounds  are  not  equally  liable  to  this  complication,  even  though 
tetanus  spores  are  present.  Punctured,  lacerated,  and  contused  wounds 
are  much  more  susceptible  to  tetanus  than  clean-cut  or  open  wounds. 
The  size  of  the  wound  is  of  much  less  consequence  than  its  character  and 
content.  Fatal  tetanus  may  develop  from  trivial  wounds,  such  as  pin 
scratches,  small  splinters,  insect  bites,  vaccinations,  etc.  Necrotic 
tissue,  foreign  bodies  and  other  irritants  favor  the  development  of 
tetanus. 

Symbiosis  is  an  important  factor  in  tetanus.  Wounds  infected  with 
the  gas  bacillus,  vihrion.  septique,  pyogenic  organisms  and  other  bacteria 
favor  anaerobic  conditions  and  permit  the  tetanus  spores  to  germinate, 
and  seem  to  encourage  the  growth  of  the  bacillus  and  the  development 
of  toxin. ^-°  Tetanus  spores  washed  free  of  toxin  and  placed  in  healthy 
tissues  do  no  harm,  but  add  a  trace  of  gas  gangrene  toxin,  or  a  chemical 
irritant  as  saponin,  or  a  physical  irritant  such  as  a  foreign  body,  and 
tetanus  develops. 

Weinberg  ^^^  has  shown  the  multiplicity  of  anaerobic  wound  infec- 
tions, and  has  also  shown  how  they  influence  each  other.  The  gas  bacil- 
lus {B.  perfringens,  also  known  as  B.  Welcliii)  plays  an  auxiliary 
part  in  the  causation  of  tetanus.  The  bacillus  of  malignant  edema  {vi- 
brion  septique)  is  also  an  ally  of  tetanus.  Antitoxins  against  both  these 
spore-bearing  anaerobes  have  been  produced.  These  antitoxic  sera,  as  in 
the  case  of  tetanus,  have  prophylactic  value,  but  feeble  curative  prop- 
erties. The  experience  in  the  war  soon  taught  the  usefulness  of  em- 
ploying, for  the  prevention  of  tetanus,  a  serum  containing  three  anti- 
bodies: (1)  against  tetanus,  (2)  against  the  gas  bacillus,  and  (3) 
against  vibrion  septique.  These  are  the  commonest  but  not  the  only  in- 
fective agents  that  play  a  part  in  stimulating  the  growth  of  the  tetanus 
bacillus  in  wounds.  Tulloch  ^^^  on  the  basis  of  agglutination  tests  has 
separated  tetanus  cultures  into  four  types.  Fortunately,  any  one  of  the 
four  antitoxins  will  neutralize  any  or  all  of  the  four  toxins. 

^' Deutsch.  med.  Wchnschr.,  XVI,  No.  40,  p.   1113. 

^^  In  the  laboratory  some  of  the  strongest  tetanus  toxins  have  been  prepared 
from  mixed  or  contaminated  cultures. 

'''Ann.  de  I'lnst.  Pasteur,  Sept.,  1917,  XXXI,  No.  9,  p.  442. 
'^^  Proc   Royal  Soc,  Series  B,  April,  1918. 


TETANUS  97 

The  normal  habitat  of  tetanus  is  in  the  intestinal  tract  of  herbiv- 
orous animals.  Sanchez,  Toledo,  and  Veillon  ^-^  found  tetanus  in  the 
feces  of  4  out  of  (i  horses  and  in  the  feces  of  1  of  3  cows.  Turk  found 
tetanus  bacilli  in  the  intestines  of  about  15  per  cent,  of  horses  and  calves 
living  in  the  vicinity  of  Xew  York  City.  They  are  present  to  a  variable 
e.xtent  in  the  intestines  of  man;  from  5  per  cent,  up  to  20  per  cent,  in 
ostlers  and  dairymen. 

It  is  rather  a  curious  paradox  that  the  horse,  which  is  the  most  sus- 
ceptible of  all  animals  to  tetanus  toxin,  is  one  of  the  principal  hosts  of 
the  tetanus  bacillus.  The  intestinal  canals  of  certain  animals  are  per- 
fect anaerobic  incubators  for  the  growth  of  tetanus  bacilli ;  such  animals 
may  be  regarded  as  "tetanus  carriers." 

Occurrence. — The  spores  taken  in  the  food  are  not  affected  by  gastric 
digestion,  and  in  the  intestines  find  ideal  anaerobic  conditions,  food 
supply  and  temperature  for  growth  and  development.  Here  they  multi- 
ply and  pass  in  the  dejecta  to  pollute  the  soil.  The  soil,  therefore,  in 
all  regions  inhabited  by  man  and  domestic  animals  is  more  or  less  con- 
taminated with  tetanus.  The  bacilli,  however,  do  not  multiply  in  the 
soil.  While  the  soil  acts  only  as  a  vehicle,  it  is  the  immediate  source 
of  the  large  proportion  of  tetanus  in  man.  The  presence  of  tetanus 
spores  in  soil,  street  dust,  fresh  vegetables  and  on  clothing  and  the  skin 
may  be  traced  to  fecal  contamination. 

On  account  of  the  great  resistance  of  the  spores,  they  are  blown  about 
in  dust  and  are  spread  everywhere  by  dirt  and  manure.  Tetanus  has 
been  found  in  hay  dust,  on  horses'  hair,  in  the  dust  of  houses,  barracks, 
and  hospitals,  in  the  mortar  of  old  masonry,  in  street  dust,  on  food,  in 
gelatin,  on  the  skin,  and  in  the  greatest  variety  of  places. 

One  of  the  agencies  in  the  distribution  of  tetanus  spores  over  limited 
areas  is  undoubtedly  the  common  house  fly.  The  poisoned  arrowheads 
of  certain  savages  in  the  Xew  Hebrides  contain  tetanus  spores  obtained 
by  smearing  the  arrowheads  with  dirt  from  crab  holes  in  the  swamps 
(Le  Dantic). 

Tetanus  bacilli  are  not  equally  numerous  in  all  localities.  The  in- 
fection is  much  more  prevalent  in  warm  than  in  cold  countries.  It  is 
especially  severe  in  the  tropics,  yet  Iceland  at  one  time  suffered  severely 
from  tetanus  neonatorum.  In  the  United  States,  tetanus  occurs  es- 
pecially in  the  Atlantic  States,  and  in  some  parts  of  Long  Island,  New 
Jersey,  and  the  Hudson  Valley,  which  have  become  noticeable  for  the 
number  of  cases  of  tetanus  complicating  small  wounds.  The  soil  of 
Flanders  and  France  has  through  long  cultivation  become  saturated  with 
the  spores  of  tetanus  and  other  anaerobes.  One  grain  of  it  from  the 
trenches  injected  into  a  laboratory  animal  invariably  produced  tetanus. 
Tetanus  spores  are  widely  disseminated  in  India.     Goodrich  states  that 

"^La  Semaine  Med.,  1890,  X,  p.  45. 


98  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

in  Boiiibay  alone  there  were  1,955  cases  of  tetanus  in  five  years.     These 
do  not  include  the  puerperal  cases. 

Tetanus  occurs  either  sporadically  or  in  epidemic  form.  Formerly 
epidemics  in  hospitals  (especially  in  lying-in  hospitals),  and  in  wars 
were  rather  common.  The  conditions  of  trench  warfare  in  the  World 
War  favored  wound  complications,  and  included  a  frightful  amount  of 
tetanus  until  antitoxin  was  used  as  a  routine  prophylactic  in  all  wounds. 
Before  the  days  of  asepsis  the  infection  was  often  spread  through  sur- 
gical instruments,  fingers,  bandages,  etc. 

The  wounds  produced  by  blank  cartridges  are  especially  liable  to 
develop  tetanus.  The  source  of  the  tetanus  spore  in  these  cases  is  not 
entirely  clear.  Wells  examined  200  cartridges  from  five  firms  without 
finding  the  tetanus  bacillus.  It  is  probable  that  the  spore  is  upon  the 
skin  and  is  carried  along  with  the  paper  and  powder  from  the  blank 
cartridge.  The  peculiar  character  of  the  wound  favors  the  development 
of  tetanus. 

The  great  decrease  in  the  number  of  cases  of  tetanus  following 
Fourth  of  July  wounds  is  due  to  the  vigorous  campaign  carried  on  by 
the  American  Medical  Association.  In  1903  there  were  406  deaths 
from  tetanus;  in  1904,  91;  1905,  87;  1906,  75;  1907,  73;  1908,  76;  in 
1911  only  18  cases  and  10  deaths  and  so  on  until  1916  when  no  deaths 
occurred  from  this  cause.  Eighty  per  cent,  of  these  followed  blank 
cartridge  wounds.  The  good  results  are  attributed  to  the  more  thorough 
and  careful  treatment  of  the  wounds  and  especially  the  use  of  tetanus 
antitoxin  as  a  prophylactic — and  more  recently  to  safer  and  saner 
methods  of  celebration. 

Tetanus  spores  or  toxin  may  contaminate  bacterial  vaccines,  anti- 
toxic sera,  vaccine  virus,  and  other  biologic  products  used  in  human 
therapy.  The  possible  association  of  tetanus  with  bacterial  vaccines  was 
demonstrated  in  the  unfortunate  outbreak  at  Mulkowal,  India,  in 
1902.^^*  One  hundred  and  seven  persons  were  inoculated  with  Haii- 
kine's  plague  prophylactic.  Of  these  19  were  affected  with  symptoms 
of  tetanus  and  died.  In  this  case  the  tetanus  probably  grew  as  a  con- 
tamination in  the  plague  culture,  for  it  is  now  well  known  that  the 
anaerobic  conditions  produced  in  B.  diphtheriae,  B.  pestis,  B.  suhtilis, 
and  other  organisms  in  liquid  culture  media  favor  the  growth  of  tetanus 
and  the  development  of  its  toxin. 

In  St.  Louis  (1901)  diphtheria  antitoxin  was  taken  from  a  horse 
during  the  period  of  inculcation  of  tetanus  and  used  in  amounts  from  5 
to  10  c.  c.  upon  7  children,  all  of  whom  died  of  tetanus.  Bolton,  Fisch, 
and  Walden  ^-■'  found  that  the  serum  was  sterile,  but  contained  tetanus 

^^*Jour.  Trop.  Med.  <md  Hyg.,  1907,  X,  p.  .3.3. 

"=  Bolton,  Fisch,  and  Walden  in  .S'f.  Louis  Medical  Review,  Vol.  XLIV,  No. 
21,  Nov.  23,  1910,  p.  361. 


TETANUS  99 

toxin  iu  considerable  amount.  If  the  serum  had  first  been  tested  upon 
animals,  its  poisonous  properties  would  have  been  discovered.  This  test 
is  now  required  by  the  United  States  law  of  July  1,  1902,  for  all  serums 
and  vaccines  sold  in  interstate  traffic.  As  a  further  precaution  against 
this  complication  horses  undergoing  treatment  for  the  production  of  im- 
mune sera  are  given  prophylactic  doses  of  tetanus  antitoxin  from  time 
to  time.  Tetanus  sometimes  occurs  as  a  complication  of  vaccination. 
See  page  22. 

It  is,  of  course,  not  the  rust  on  a  nail  that  is  dangerous,  so  far  as 
tetanus  is  concerned,  but  the  spore-bearing  dirt  it  carries  into  the  deep, 
contused  wound  that  causes  the  trouble.  Gelatin  may  contain  tetanus 
spores,  and  the  subcutaneous  injection  of  imperfectly  sterilized  gelatin 
as  a  hemostatic  has  sometimes  resulted  in  accidents. 

Tetanus  is  harmless  when  taken  by  the  mouth.  Susceptible  animals 
•mav  be  given  enormous  doses  of  tetanus  toxin  by  the  mouth  without 
producing  the  disease.  The  bacillus  and  its  spore  may  be  regarded  as 
a  saprophyte  in  the  intestinal  tract.  There  is.  however,  a  suspicion  that 
tetanus  spores  sometimes  invade  the  organism  through  small  wounds  in 
the  digestive  or  respiratory  tract.  Perhaps  some  of  the  cases  following 
surgical  operations  may  be  accounted  for  in  this  way  rather  than  by  in- 
fection of  the  catgut  used  for  ligatures. 

Tetanus  sometimes  occurs  where  no  wound  can  be  found.  This 
is  the  so-called  "idiopathic  tetanus."  One  explanation  of  these  cases 
is  to  be  found  in  the  fact  that  the  spores  are  numerous  in  street  dust 
and  may  enter  the  respiratory  tract.  They  cannot  do  harm  so  long  as 
the  mucous  membrane  is  healthy,  but  may  enter  through  inflamed  mem- 
branes or  through  small  wounds  in  the  nose. 

Tetanus  bacilli  have  been  found  in  the  bronchial  mucus  of  idiopathic 
cases.  Tetanus  spores  have  occasionally  been  found  in  the  lymph  glands, 
liver,  and  other  parts  of  the  body,  upsetting  our  previous  view  that  they 
are  always  strictly  confined  to  the  site  of  the  wound.  The  spores  may 
remain  latent  or  dormant  in  scar  tissue  or  the  sequestrum  of  bone  and 
may  be  released  and  start  an  attack  months  or  years  afterwards,  thus 
giving  another  plausible  explanation  of  some  cases  of  idiopathic  tet- 
anus. 

Puerperal  tetanus  was  formerly  a  frequent  and  serious  complication 
following  childbirth,  but  has  been  conquered  by  asepsis. 

Trismus  Neonatorum,  or  tetanus  of  the  newborn,  is  still  a  common 
and  very  fatal  infection,  especially  in  the  tropics.  Before  the  days  of 
asepsis  the  infection  was  permitted  to  enter  through  the  umbilical  wound. 
In  certain  of  the  West  Indian  islands  more  than  one-half  of  the  mortality 
among  the  negro  children  has  been  due  to  this  cause.  In  Venezuela, 
trismus  neonatorum  is  one  of  the  chief  causes  of  deaths,  and  goes  by  the 
name  of  mocezuelo. 


100  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

The  following  figures  are  taken  from  official  reports  :^-^ 


Total  Deaths 

Population 

Total  Deaths 

Deaths  from 

from  Tetanus,  all 

Year 

of 

in 

Infantile 

Forms  Except 

Venezuela 

Venezuela 

Tetanus 

Puerperal 
Variety 

1905 

2,598,063 

58,100* 

3,316 

1906 

52,949 

3,485 

1907 

52,140 

3,713 

1908 

56,903 

4,360 

1909 

53,364 

2,782 

3,942 

1910 

2,685,440 

55,436 

3,574 

4,721 

1911 

55,428 

3,474 

4,505 

1912 

65,729 

2824 

3,794 

1913 

52,847 

2,743 

3,662 

1914 

51,697 

2,816 

3,691 

1915 

2,818.220 

63,133 

2,804 

3,699 

Total 

617,736 

18,201 

28,015 

*  Infantile 
1908,  inclusive. 


tetanus    not    separated    from  total    of    tetanus    deaths    in    years    1905- 


Incubation. — The  period  of  incubation  in  man  is  usually  from  6 
to  14  days.  The  period  is  directly  proportional  to  the  amount  of  toxin 
and  the  severity  of  the  disease.  This  can  readily  be  demonstrated  upon 
susceptible  animals.  In  a  study  of  600  serial  tests,  Bosenau  and  Ander- 
son found  this  direct  relation  between  the  period  of  incubation  and  the 
severity  of  symptoms  by  the  subcutaneous  injection  of  varying  amounts 
of  toxin  into  guinea  pigs.  Thus  guinea  pigs  receiving  fairly  large  doses 
showed  symptoms  on  the  third  day  and  usually  died;  when  the  dose  is 
smaller,  the  period  of  incubation  is  longer,  the  disease  milder,  and  the 
chances  of  recovery  greater.  In  man,  with  a  short  period  of  incubation, 
6  days  or  less,  the  disease  is  almost  invariably  fatal.  With  longer 
periods  the  disease  is  usually  milder  and  recovery  frequently  takes  place 
without  the  use  of  antitoxin  or  other  measures.  Tetanus  toxin  is  ab- 
sorbed by  the  terminal  nerve  endings,  and  travels  up  the  axis  cylinders 
of  the  nerves  to  the  cord  and  brain.  It  is  also  distributed  in  the  blood. 
The  period  of  incubation,  therefore,  depends  somewhat  upon  the  point 
of  entrance  of  the  poison  and  its  proximity  to  abundant  motor  nerve 
endings.  ^^'^ 

Resistance. — The  tetanus  hacillus  is  readily  destroyed  by  the  or- 
dinary agencies  that  kill  vegetative  bacteria.  It  is  killed  almost  at  once 
in  contact  with  the  free  oxygen  of  the  air.  On  the  other  hand,  few,  if 
any,  forms  of  life  have  a  greater  resistance  than  the  tetanus  spore. 
Hours  of  exposure  to  60°  or  70°  C.  do  not  affect  them.  They  usually 
survive  an  exposure  of  one  hour  to  80°  C,  but,  as  a  rule,  are  killed  in 

^^^  Furnished  by  Surgeon  W.  J.  Stewart,  U.  S.  Public  Health  Service. 
'^^  For  discussion  of  tetanus  toxin  and  tetanus  antitoxin,  see  pages  103,  553 
and  568. 


TETANUS  101 

streaming  steam  or  boiling  water  in  60  minutes.  Tetanus  spores,  how- 
ever, vary  greatly  in  the  power  to  resist  the  boiling  temperature.  Kita- 
sato  ^^*  found  them  to  resist  80°  C.  for  one  hour,  but  to  be  killed  in 
streaming  steam  in  5  minutes.  Vaillard  and  Vincent  ^^^  found  that  the 
spores  heated  in  the  presence  of  moisture  in  a  closed  vessel  would  re- 
sist destruction  at  80°  C.  for  G  hours,  at  90°  C.  for  2  hours,  and  100° 
C.  3  to  4  minutes,  that  they  were  not  always  destroyed  in  5  minutes, 
but  never  resisted  more  than  8  minutes  at  100°  C.  Levy  and  Bruns  ^^° 
found  that  destruction  begins  at  8I/2  minutes  at  100°  C. ;  after  15 
minutes  few  survive,  after  30  minutes  none.  Falcioni  ^^^  studied  the 
subject  in  view  of  the  dangers  of  the  subcutaneous  injection  of  gelatin. 
He  impregnated  gelatin  with  spores  of  tetanus  bacilli  grown  in  agar  or 
broth  for  10  to  12  days,  and  used  Koch's  steam  sterilizer.  He  found 
the  spores  to  resist  destruction  for  2^4;-  but  not  for  3,  hours  in  stream- 
ing steam. 

The  experimental  results  are,  therefore,  sufficiently  varied  and  con- 
flicting to  suggest  that  races  of  tetanus  bacilli  exist,  the  spores  of  which 
vary  widely  in  their  resistance  to  moist  heat  at  100°  C.  Theobald 
Smith  ^^^  found  that  under  certain  conditions  of  cultivation  some  tet- 
anus spores  survive  a  single  boiling  or  streaming  steam  regularly  for  20 
minutes,  usually  for  40  minutes,  and  occasionally  for  60  minutes;  in 
one  case  70  minutes'  exposure  did  not  destroy  the  spores.  He  also 
showed  the  possibility  of  tetanus  spores  surviving  in  culture  fluids 
sterilized  by  discontinuous  boiling  or  steaming  in  routine  laboratory 
work  for  fully  20  minutes  on  three  successive  days. 

In  general,  dry  spores  are  more  resistant  than  moist  spores;  and 
young  spores  are  often  harder  to  kill  than  old  spores. 

Tetanus  spores  resist  the  action  of  5  per  cent,  carbolic  acid  for  10 
hours,  but  are  killed  in  15  hours.  A  5  per  cent,  solution  of  carbolic  acid, 
however,  to  which  0.5  per  cent,  of  hydrochloric  acid  has  been  added, 
destroys  them  in  2  hours.  Bichlorid  of  mercury,  1-1,000  kills  the  spores 
in  3  hours,  and  in  30  minutes  when  0.5  per  cent,  of  hydrochloric  acid  is 
added  to  the  solution.  According  to  Park,  silver  nitrate  solution  de- 
stroys the  spores  of  average  resistance  in  1  minute  in  1  per  cent,  solu- 
tion, and  in  about  5  minutes  in  a  1  to  1,000  solution.  Tetanus  spores 
are  destroyed  u'xtli  certainty  when  exposed  to  dry  heat  at  or  above  160° 
C.  for  one  hour,  or  to  steam  at  120°  C.  for  20  minutes.  Entire  con- 
fidence may  he  placed  upon  either  of  these  tiro  methods. 

The  temperature  recorded  on  the  thermometer  of  the  sterilizer  may 
be  higher  than  the  actual   temperature  within  the  apparatus.     Good 

^^Zeiiselir.  f.  Hijg.,  VII,  p.  225. 

^^Ann.  de  Vlnst.  ^Pasteur.  1891.  V.  p.  1. 

"^  Grenzgeb.  d.  Med.  u.  Chir..  1902.  X.  p.  235. 

^^  Annali  d'igiene  sperimentale,  1904.  N.  S..  XIV,  p.  319. 

^'Wour.  A.  il.  A.,  March  21,  1908,  Vol.  L,  pp.  929-934. 


10?  DISEASES  HAVIXCt  SPECIAL  PROPHYLAXIS 

sterilizing  technic  is  essential  and  a  factor  of  safety  desirable.  The  time 
necessary  for  penetration  must  be  taken  into  account.  Thus,  the  gov- 
ernment regulations  ^^^  require  an  exposure  of  170°  C.  for  two  hours 
for  dry  sterilization  of  glassware  intended  to  contain  biologic  products. 
These  same  regulations  require  121°  C.  (15  pounds)  for  30  minutes  for 
steam  sterilization  of  glassware  and  rubber  tubing.  Glassware  and  rub- 
ber tubing  must  be  moistened  immediately  before  steam  sterilization  and 
each  flask  or  hollow  apparatus  should  contain  one-eighth  of  its  volume 
of  water  when  put  in  the  autoclave.  This  is  for  the  purpose  of  insuring 
that  steam  will  be  in  contact  with  all  surfaces.  In  some  cases,  rubber 
goods  may  be  sterilized  by  boiling  for  30  minutes  in  3  to  5  per  cent, 
phenol  or  some  similar  disinfectant. 

Direct  sunlight  does  not  kill  the  spores,  but  seems  to  diminish  their 
virulence.  Under  certain  circumstances  they  may  live  a  very  long  time; 
Henrijean  reports  that,  by  means  of  a  splinter  of  wood  'which  once 
caused  tetanus,  he  was  able  after  11  years  again  to  cause  the  disease  by 
inoculating  an  animal  with  the  infective  material. 

Prophylaxis. — Local  Treatment  of  Wounds. — Thorough  surgical 
treatment  of  the  wound  as  soon  as  possible  is  the  first  important  meas- 
ure in  the  prevention  of  tetanus.  Wounds,  however  insignificant,  should 
be  thoroughly  cleansed.  Punctured  or  lacerated  wounds,  in  which  there 
is  special  danger  of  tetanus,  should  be  freely  opened,  and  every  particle 
of  foreign  matter  carefully  removed.  Promptness  in  cleansing  the 
wound  surgically  is  almost  as  important  as  thoroughness.  Gunshot 
wounds  and  wounds  containing  garden  earth,  street  dust,  or  other  ma- 
terial liable  to  contain  tetanus  spores  should  receive  special  considera- 
tion. All  necrotic  tissue,  or  tissue  likely  to  die^  must  be  removed.  The 
experience  of  the  war  demonstrated  that  thorough  excision  of  the  wound 
(debridement)  is  good  practice.  Germicides  are  useless — the  surgeon's 
knife  is  the  best  antiseptic.  The  division  of  the  umbilical  cord  and  the 
treatment  of  the  navel  in  the  newborn  must  be  done  under  the  strictest 
asepsis.  Wounds  in  which  there  is  suspicion  of  tetanus  should  be  kept 
open  and  freely  drained,  and  otherwise  treated  so  as  to  discourage 
anaerobic  conditions. 

Tetanus  spores  gain  entrance  into  wounds  not  only  from  manure, 
garden  soil,  street  dust,  and  similar  sources,  but  also  from  the  hands, 
instruments,  bandages,  suture  material,  or  other  objects.  It  is  impor- 
tant to  remember  that  the  tetanus  spore  is  exceedingly  resistant  to  heat 
and  chemical  agents,  and  that  in  surgical  and  obstetrical  practice  con- 
fidence should  not  be  placed  simply  upon  brief  boiling  to  destroy  the 
spores.  A^ery  particular  care  must  be  exercised  in  the  disinfection 
of  substances  injected  into  the  body,  such  as  gelatin  and  other  organic 
materials. 

133  Regulations  of  the  U.  S.  Public  Health  Service,  Oct.   1,  1919. 


TETANUS  103 

Specific  Propliylaxis. — Tetanus  antitoxin  is  a  specific  and  trust- 
worthy preventive.  The  great  experience  of  the  war  adds  confirmation 
to  the  protective  power  of  this  specific  and  sovereign  serum.  Its  use, 
however,  must  he  understood  to  achieve  satisfactory  results.  The  anti- 
toxin must  he  administered  before  the  advent  of  symptoms,  for  after 
the  tetanus  toxin  has  combined  with  the  motor  nerve  cells  in  the  central 
nervous  system  it  can  neither  be  displaced  nor  neutralized  with  anti- 
toxin. In  such  cases  the  most  that  the  antitoxin  can  do  is  to  combine 
with  and  neutralize  the  free  toxin  and  thus  prevent  further  damage. 

From  500  to  1500  units  of  tetanus  antitoxin  are  used  as  a  prophy- 
lactic dose.^^*  The  amount  varies  with  the  severity  of  the  wound  and 
the  hazard  of  tetanus.  In  wounds  liable  to  infection,  the  injection 
should  be  repeated  every  seven  days  until  the  wound  is  clean,  or  the 
danger  passed.  It  is  important  to  remember  that  the  tetanus  antitoxin 
is  eliminated  or  otherwise  disposed  of  in  the  body  in  the  course  of  10 
days  or  2  weeks.  Therefore,  in  cases  in  which  the  wound  does  not  heal 
Well,  as  a  result  of  mixed  infection,  or  for  other  reasons,  it  is  desirable  to 
repeat  the  injection.  This  may  be  done  at  intervals  of  7  or  8  days  as 
long  as  the  danger  persists.  Occasionally  tetanus  bacilli  persist  in  the 
pus-infected  tissues,  and,  when  the  injected  antitoxin  has  been  exhausted, 
there  may  occur  a  late  development  of  tetanus.  Instances  in  which 
1,500  units  of  tetanus  antitoxin,  repeated  if  necessary,  have  failed  to 
prevent  the  development  of  tetanus  are  rare.  During  the  latter  part  of 
the  war,  a  triple  antitoxin,  made  from  the  tetanus  bacillus,  the  gas 
bacillus  ^^^  {B.  perfringens) ,  and  the  bacillus  of  malignant  edema 
{vibrion  septique),  was  used  as  a  routine  prophylactic,  and  resulted  in 
preventing  much  suffering  and  saving  many  lives. 

Gunshot  wounds  and  wounds  produced  by  blank  cartridges  should 
always  be  regarded  as  suspicious,  and  should  be  given  careful  local 
treatment,  supplemented  with  a  prophylactic  injection  of  antitoxin. 
Tetanus  was  a  frequent  complication  of  trench  foot,  and  therefore  a 
prophylactic  injection  of  antitoxic  serum  should  be  given  and  repeated 
at  intervals  of  seven  days  until  the  wounds  are  healed. 

The  prevention  of  tetanus  complication  of  vaccine  wounds  con- 
sists in:  (1)  The  use  of  a  reliable  vaccine  which  has  been  biologically 
tested  in  accordance  with  the  federal  act.     (2)  Proper  methods  of  vac- 

^'■'^  As  soon  as  symptoms  appear  20.000  units  or  more  of  tetanus  antitoxin 
should  be  introduced  directly  into  the  circulation  by  intravenous  injection;  some 
antitoxin  may  also  be  injected  into  the  nerves  leading  from  the  wound.  Xicolle 
has  obtained  favorable  results  with  antitoxin,  even  after  symptoms  liave  devel- 
oped, by  injecting  3  to  5.000  units  into  the  spinal  canal,  10.000  units  intra- 
venously, and  10,000  units  subcutaneously.  {Jour.  A.  M.  A.,  LXTV.  24.  .Tune  12, 
191.5,  p.  19S2.)  In  tetanus,  as  in  diphtheria,  time  is  the  important  element.  A 
few  units  introduced  early  are  worth  more  than  thousands  late. 

"^  Bull,  C.  G..  and  Pritcliett.  I.  W. :  "''Toxin  and  Antitoxin  of  and  Protective 
Inoculation  against  Bacillus  Welchii."  Jour.  Exp.  Med.,  XXVI,  Xo.  1,  Julv, 
1917,  p.  119. 


104  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

cination  to  avoid  unnecessary  scabs  and  anaerobic  wound  conditions. 
(3)  Surgical  asepsis  of  the  operation  and  after-treatment. 

Tetanus  and  other  wound  infections  may  be  avoided,  in  those  ex- 
posed to  accidents,  by  cleanliness  of  body  and  clothing.  A  bath  before 
a  battle  is  a  reasonable  protection  said  to  be  adopted  in  the  Japanese 
Army  and  jSTavy,  The  common  experience  of  mankind  teaches  that  most 
wounds  heal  without  tetanus,  and  that  tetanus  is,  in  fact,  a  relatively 
rare  infection.  The  physician,  however,  is  in  no  case  Justified  in  taking 
chances,  and  it  is  one  of  the  duties  of  the  medical  profession  to  teach 
the  public  that  it  pays  to  thoroughly  cleanse  and  care  for  wounds,  how- 
ever trivial,  at  once,  and  in  accordance  with  modem  methods. 


CHAPTER  IT 

DISEASES  SPREAD  LARGELY  THROUGH  THE  ALYINE 
DISCHARGES ' 

TYPHOID  FEVER 

{Typlius  Ahdominalis) 

Typhoid  fever  is  a  sanitan'  problem  of  first  magnitude,  especially 
in  this  country,  where  it  is  still  unduly  prevalent.  In  the  United  States 
typhoid  fever  for  a  long  time  stood  fourth  on  the  list  of  mortality  tables : 
tuberculosis  coming  first,  then  pneumonia  and  cancer;  typhoid  fever  has 
now  been  reduced  to  about  ninth  place.  The  average  case  fatalit}'  from 
typhoid  fever  being  nearly  10  per  cent.,  it  would,  therefore,  take 
higher  rank  on  the  morbidity  tables.  In  1910  there  were  25,000  deaths 
from  typhoid  fever  in  the  United  States,  representing  at  least  250,000 
cases — one  person  in  every  400.  Marked  improvement  began  to  occur 
about  1910,  and  from  that  time  on  nearly  every  year  has  witnessed  a 
fall  in  the  t}T)hoid  death  rate.  For  about  27,000,000  people  in  60  cities 
of  the  United  States,  in  1919  it  reached  the  exceedingly  low  point  of  4.2. 

Our  general  attitude  toward  typhoid  fever  is  inconsistent;  familiar- 
ity has  bred  a  remarkable  indifference  to  the  disease.  Every  case  of 
typhoid  fever  means  a  short  circuit  between  the  alvine  discharges  of  one 
person  and  the  mouth  of  another.  The  physician  has  a  dual  duty  in 
the  care  of  a  case  of  t^'phoid  fever :  one  is  to  assist  the  patient,  the 
other  is  to  protect  the  community.  On  the  other  hand,  the  people  should 
learn  the  lesson  that  a  case  of  typhoid  fever  must  be  regarded  as  se- 
riously as  a  case  of  cholera.  These  two  diseases  present  many  features 
in.  common.  Both  are  intestinal  infections  of  bacterial  nature ;  in  both 
diseases  the  alvine  discharges  contain  the  microorganisms  which  rein- 
fect another  person  when  taken  by  the  mouth.  Both  diseases  prevail  es- 
pecially in  hot  weather,  and  both  diseases  are  peculiar  to  man,  so  that 
the  patient  is  the  fountainhead  of  each  infection.  Water,  food,  fingers, 
flies,  contacts  and  carriers  play  a  similar  role  in  both  instances.  In  the 
case  of  cholera  the  dread  of  the  disease  is  an  important  factor  in  keep- 

'  The  control  of  this  group  of  infections  is  one  of  the  most  notable  achieve- 
ments in  preventive  medicine.  The  cause,  mode  of  transmission,  and  prevention 
are  well  understood  in  theory  and  readily  attainable  in  practice.  Sanitation 
here  finds  its  first  fruitful  field,  hygiene  its  useful  lessons,  and  immunology  its 
special  application. 

105 


106     DISEASES  SPREAD  BY  THE  ALVINE  DISCHARGES 

ing  it  out  of  the  country  or  in  preventing  its  spread  when  once  intro- 
duced. By  strange  contrast,  there  is  a  remarkable  indifference  to  ty- 
phoid fever.  A  wholesome  fear  of  typhoid  fever  would  materially  as- 
sist the  health  authorities  in  combating  what  may  be  considered  one  of 
the  major  sanitary  problems  of  the  age.  From  the  standpoint  of  pre- 
ventive medicine,  it  is  proper  to  regard  an  outbreak  of  typhoid  fever  as  a 
reproach  to  the  sanitation  and  civilization  of  the  community  in  which  it 
occurs.  When  the  matter  is  better  understood  health  authorities  will 
be  held  responsible  for  this  and  other  preventable  infections,  just  as 
some  one  is  now  held  responsible  for  preventable  accidents.  ^^ 

Much  harm  has  been  done  by  insisting  that  typhoid  fever  is  in- 
fectious, but  not  contagious;  it  is  both — that  is,  communicable.^ 

Typhoid  fever  occurs  both  in  endemic  and  epidemic  forms.  It  may 
truly  be  regarded  as  pandemic.  iSTormally,  typhoid  fever  is  a  warm 
weather  disease.  It  recurs  as  an  annual  crop  from  July  to  October.^ 
Epidemics  caused  by  infected  water  occur  especially  in  cold  weather. 
Milk  outbreaks  may  occur  at  any  time  of  the  year.  Autumnal  typhoid 
is  due  partly  to  infection  contracted  at  "health"  resorts,  and  has,  there- 
fore, been  called  a  vacation  disease. 

Typhoid  fever  is  more  prevalent  in  rural  districts  than  in  cities.  In 
the  United  States  there  is  more  typhoid  fever  in  the  southern  states 
than  in  the  northern  zone.  The  only  explanation  to  account  for  this  is 
the  influence  of  temperature,  rural  conditions,  and  association  with  the 
negro.  Typhoid  fever  is  no  respecter  of  ric4i  or  poor;  it  attacks  those 
in  robust  health,  all  ages,  both  sexes. 

The  period  of  incubation  is  usually  7  to  23  days,  commonly  about 
10  to  14  days. 

Typhoid  fever  is  a  disease  which  ordinarily  attacks  the  individual 
during  the  period  of  greatest  economic  value  to  the  community.  The 
economic  loss,  therefore,  is  appalling,  and  has  been  estimated  to  reach 
the  sum  of  no  less  than  $100,000,000  annually  in  the  United  States. 
Again,  typhoid  fever  is  an  infection  against  which  the  individual  alone 
cannot  protect  himself  wholly  without  the  aid  of  the  community. 

The  control  of  typhoid  fever  in  modern  armies  and  the  marked  re- 
duction in  its  prevalence  in  the  civilian  population  in  the  United  States 
in  recent  years  is  one  of  the  great  triumphs  of  preventive  medicine. 

Historical  Landmarks. — Typhoid  fever  was  confused  for  centuries 
with  other  continued  fevers,  such  as  recurrent  fever,  septic  infections, 
and  typhus  fever.  The  first  full  description  of  what  was  probably  typhoid 
fever  was  written  by  Thomas  Willis,  an  English  physician,  who,  in  1643, 
described  an  epidemic  that  occurred  in  Parliamentary  troops.     Breton- 

la  See  Vennen  vs.  New  Dells  Lumber  Co.,  page  1291. 
^  For  distinction  between  these  terms  see  page  463. 
^In  the  southern  hemisphere  the  typhoid  season  is  during  our  winter. 


TYPHOID  FEVET?  107 

neau  in  1826  further  described  tho  clinical  characteristics  and  called  it 
"dothienentcritis,"  or  abscess  of  the  small  intestine,  a  name  it  fre- 
quently bears  in  French  literature.  Ix)uis,  the  distinguished  French 
clinician,  in  1820  gave  the  name  typhoid  fever  to  the  malady  to  dis- 
tinguish it  from  typhus  fever.  William  Gerard,  of  Philadelphia,  a  pupil 
of  Louis,  showed  the  difference  in  the  lesions  between  these  two  fevers, 
which  established  typhoid  fever  as  a  distinct  disease. 

William  Budd  in  1856  pointed  out  that  the  disease  is  transmitted 
by  the  patient's  excreta.  He  stated  that:  "The  living  human  body, 
therefore,  is  the  soil  in  which  this  specific  poison  breeds  and  multiplies; 
and  that  most  specific  of  processes  which  constitutes  the  fever  itself  is 
the  process  by  which  the  multiplication  is  effected."  The  first  water- 
borne  outbreak  carefully  studied  and  described  was  at  Lausanne,  Swit- 
^^erland,  in  1872  ;  the  first  water-borne  outbreak  to  attract  attention  in 
the  United  States  occurred  in  Plymouth,  Pennsylvania,  in  1885.  In 
1873,  Murchinson  traced  an  epidemic  to  a  contaminated  milk  supply. 
Eberth  in  1880  saw  the  Bacillus  typhosus  in  the  tissues,  and  four  years 
later  Gaffky  grew  it  in  pure  culture.  Metchnikoff  and  Besredka,  in  1900, 
finally  established  the  etiological  relation  by  producing  the  disease  in  an- 
thropoid apes  with  pure  cultures.  In  1894,  Pfeiffer  and  Kolle  first  gave 
small  subcutaneous  inoculations  of  dead  typhoid  bacilli.  x\bout  the  same 
time,  and  independently,  A.  E.  Wright  began  similar  inoculations  in 
British  soldiers,  but  it  took  something  over  10  years  to  establish  the 
prophylactic  value  of  typhoid  vaccines. 

Prevalence. — Typhoid  fever  prevails  more  or  less  in  all  countries 
— the  amount  of  the  disease,  however,  varies  greatly.  It  appears  to  be 
a  disease  of  defective  civilization,  for  those  communities  paying  least 
attention  to  sanitation,  as  a  rule,  suffer  most.  In  the  United  States 
there  are  comparatively  few  communities  of  1,000  inhabitants  or  more 
wh-ich,  during  any  period  of  twelve  consecutive  months  within  the  last 
decade,  have  been  entirely  free  from  typhoid  fever.  According  to  the 
United  States  census  report  fox  1900,  the  average  typhoid  death-rate  in 
the  United  States  was  46.5  per  100,000  inhabitants.  In  1917,  this  was 
reduced  to  13.4. 

The  improvement  in  the  situation  within  recent  years  is  shown  by 
the  following  rates  per  100,000  of  population  for  the  registration  areas: 

1910  23.5 

1911  21.0 

1912  16.5 

1913  17.9 

1914  15.4 

1915  12.4 

1916  13.3 

1917  13.4 


108     DISEASES  SPREAD  BY  THE  ALVINE  DISCHARGES 

A  still  greater  lowering  of  the  typhoid  rates  in  our  large  cities  is 
shown  in  table,  page  109.  In  1908  the  death  toll  from  typhoid  fever 
was  no  less  than  35,000  in  the  United  States.  In  other  words,  one  person 
in  about  300  in  the  United  States  contracted  typhoid  fever  that  year.  It 
is  estimated  that  in  1910-11  the  number  of  deaths  was  reduced  to  about 
25,000. 

The  significance  of  these  figures  may  be  judged  by  estimating  the 
probable  number  of  cases  of  typhoid  fever  among  persons  handling  the 
milk  supply.  Take,  for  instance,  a  city,  as  Washington,  receiving  its 
milk  from  a  thousand  dairy  farms.  On  the  average  there  will  be  about 
four  persons  on  each  farm  who  in  one  way  or  another  come  in  contact 
with  the  milk.  That  makes  4,000  persons  among  whom  about  20  cases 
of  typhoid  may  be  expected  to  occur  annually.  Add  to  this  the  carriers, 
and  it  is  no  wonder  that  milk-borne  outbreaks  of  typhoid  fever  are  fre- 
quent occurrences. 

The  rate  of  prevalence  of  typhoid  fever  in  the  United  States  in  com- 
parison with  the  rates  of  many  other  countries  was  very  high.  Thus, 
the  annual  death-rate  from  typhoid  fever  per  100,000  population  for 
the  period  1901-1905  was:  in  Scotland,  6.2;  in  Germany,  7.6;  in  Eng- 
land and  Wales,  11.2;  in  Belgium,  16.8;  in  Austria  (1901-1904),  19.9; 
in  Hungary,  28.3 ;  in  Italy,  35.2 ;  while  the  rate  in  the  United  States 
during  the  same  period  was  about  46.5.  A  great  improvement  in  the 
typhoid  situation  is  now  taking  place  in  this  country — and  many  states 
and  cities  are  reporting  figures  approaching  and  even  bettering  the  Eu- 
ropean rates.  In  1917,  the  rate  in  the  registration  area  of  the  United 
States  was  13.4,  a  reduction  of  63  per  cent,  since  1900. 

In  northern  Europe  the  33  principal  cities,  with  an  aggregate  pop- 
ulation of  31,500,000,  had  an  average  typhoid  death-rate  per  100,000 
population  of  6.5  in  1909  and  1910.  This  includes  such  a  notorious  ty- 
phoid center  as  Petrograd,  which  had  a  rate  of  33.7  in  1910.  The  high 
rate  in  Petrograd  was  due  to  the  water  supply,  which  is  partly  filtered 
and  partly  raw  JSTeva  water. 

A  comparison  of  these  rates  with  typhoid  fever  in  America  is  given 
in  Table  2,  page  109. 

The  typhoid  rates  in  our  larger  cities  are  coming  down,  owing  to 
safer  water  supplies,  better  sanitary  conditions  and  the  increasing 
use  of  typhoid  vaccines.  In  fact  the  improvement  in  our  typhoid  situa- 
tion is  one  of  the  great  sanitary  reforms  now  going  on.  This  improve- 
ment is  shown  in  the  table  on  the  following  page,  which  gives  the  death 
rates  in  the  large  cities  of  the  United  States. 

Eesidual  or  "Normal"  Typhoid. — When  a  city,  such  as  Albany, 
Chicago,  Lawrence,  Lowell,  or  Pittsburgh,  which  had  been  using  grossly 
polluted  water,  is  furnished  with  a  water  supply  of  good  sanitary  qual- 
itv,  there  at  once  results  a  marked  reduction  in  the  amount  of  typhoid 


TYPITOTD  FEVER 


109 


Annual  Death  Rates  from  Typhoid  Fever  per  100.000  Population  in  50  Cities  of 
THE  United  States  Having  Mque  than   100,000   Inhaiutants 


City 

1909 

1910 

19H 

1912 

1913 

1914 

1915 

1916 

1917 

1918 

Birmingham,  Ala.. 
Los  Angeles.  Cal..  . 

Oakland,    Cal 

San  Francisco,  Cal  . 

Denver.    Colo 

Bridgeport,    Conn.. 
New  Haven.  Conn.. 
Washington,  D.  C. . 

Atlanta,  Ga 

Chicago,   111 

Indianapolis,    Ind.. 

Louisville.    Ky 

New   Orleans.    La  . . 

Baltimore.   Md 

Boston.    Mass 

Cambridge.   Mass.  . 
Fall  River,  Mass..  . 

Lowell.    Mass 

Worcester.  Mass  . .  . 

Detroit,    Mich 

Grand  Rapids.  Mich 
Minneapolis,    Minn  . 
St.   Paul,   Minn..  .  . 
Kansas  City,   Mo..  . 

St.  Louis,  Mo 

Omaha,   Nebr 

Jersey  City.  N.  J  . . 

Newark.   N.   J 

Paterson,   N.   J.  .  .  . 

Albany,  N.  Y 

Buffalo,  N.  Y 

New  York.  N.  Y  . .  . 
Rochester,  N.   Y.  .  . 
Syracuse.  N.  Y  . .  . . 
Cincinnati,  Ohio  ..  . 
Cleveland,   Ohio..  .  . 
Columbus.   Ohio.  ..  . 

Dayton,    Ohio 

Toledo,    Ohio 

Portland.    Oregon.  . 
Philadelphia.    Penn. 
Pittsburgh,    Penn.. 
Scranton.   Penn. ..  . 
Providence.   R.    I..  . 
Memphis,   Tenn..  .. 
Nashville.  Tenn. . .  . 

Richmond.   Va 

Seattle.   Wash 

Spokane,  Wash .... 
Milwaukee,   Wis. .  . . 

59.7 
16.1 
11.2 
13.9 

24.1 

9.0 
20.5 
34.3 
50.0 
12.6 
22.3 
45.0 
28.4 
24.9 
13.8 

7.7 
21.3 
10.5 

8.4 
20.5 
17.2 
21.t» 
18.9 
29.3 
16.2 
36.8 

8.8 
11.9 

9.7 
19.0 
23.8 
12.1 

9.4 
11.2 
13.3 
13.3 
19.6 
26.9 
41.7 
22.0 
22.3 
24.6 
16.4 
11.4 
48.8 
52.0 
24.1 
23.8 
43.2 
21.4 

49.5 
14.2 
16.5 
15.5 
27.5 

4.9 
17.9 
23.2 
50.1 
13.7 
28.5 
31.7 
31.5 
42.0 
11.3 

9.5 
15.0 
19.7 
15.7 
23.0 
28.3 
58.7 
19.5 
54.4 
14.9 
86.7 
11.5 
13.1 

7.1 
14.0 
20.4 
11.6 
13.7 
28.2 

8.8 
17.9 
18.1 
21.4 
37.2 
22.4 
17.5 
27.8 
16.9 
17.7 
27.4 
48.9 
21.9 
14.2 
45.4 
45.7 

45.5 
11.6 
14.0 
15.3 
18.0 

3.8 
24.9 
22.2 
66.1 
10.9 
25.8 
23.7 
31.0 
27.6 

8.7 

2.8 
14.7 

7.3 

6.0 
15.8 
26.7 
11.9 
10.5 
29.9 
16.1 
18.1 

7.2 
10.5 

7.0 
18'.8 
25.0 
10.9 
10.6 
16.2 
11.4 
14.2 
13.9 
18.6 
23.1 
19.1 
14.6 
25.6 
14.3 
12.1 
65.4 
53.9 
17.8 
10.3 
35.6 
19.0 

37.3 

15.0 

13.7 

13.6 

16.2 

8.3 

24.4 

23.0 

41.9 

7.4 

17.8 

21.8 

14.0 

24.6 

8.0 

3.7 

18.0 

10.1 

3.3 

17.5 

33.9 

11.7 

10.6 

12.0 

10.7 

14.0 

7.8 

8.1 

5.4 

17.7 

11.8 

9.6 

11.7 

16.7 

7.7 

6.9 

19.6 

19.1 

31.7 

16.6 

12.8 

13.1 

10.3 

10.2 

58.9 

32.8 

16.7 

7.6 

17.4 

25.7 

36.0 
12.1 
12.0 
16.1 
13.5 

6.2 
12.7 
16.4 
21.9 
10.4 
24.4 
23.2 
16.9 
23.8 

8.2 

9.2 

8.9 
10.0 

5.6 
29.4 
18.2 
12.0 

9.1 
21.9 
16.9 

7.6 
10.8 

8.7 

8.3 
27.4 
15.4 

7.0 

8.9 
13.0 

6.8 
14.1 
19.1 
18.0 
41.6 

6.5 
15.7 
19.5 

9.4 
11.2 
34.2 
36.9 
20.3 

4.7 

7.0 
11.3 

39.7 

7.7 

6.6 

12.7 

9.0 

3.5 

15.2 

11.9 

46.3 

6.6 

25.8 

25.9 

21.9 

22.6 

9.0 

1.8 

9.6 

10.8 

3.8 

14.1 

27.6 

12.5 

11.0 

16.3 

12.0 

4.5 

7.5 

7.5 

4.5 

17.5 

16.3 

6.3 

10.2 

10.0 

6.2 

8.1 

13.2 

11.3 

36.9 

6.9 

7.6 

15.0 

9.2 

11.0 

42.6 

51.3 

14.8 

7.0 

12.5 

8.1 

36.2 

5.7 

6.8 

9.0 

6.3 

5.1 

19.7 

12.0 

15.7 

5.3 

14.3 

13.9 

20.5 

20.7 

5.2 

1.8 

15.0 

16.1 

5.6 

13.5 

27.8 

7.6 

7.0 

9.7 

6.8 

6.1 

5.7 

2.8 

4.4 

12.6 

10.0 

6.0 

6.0 

5.9 

7.4 

7.9 

13.4 

17.5 

22.9 

5.1 

6.8 

10.3 

12.5 

8.0 

26.7 

37.1 

12.3 

2.4 

9.8 

5.1 

43.5 

2.6 

4.0 

3.5 

7.3 

9.0 

8.7 

12.9 

22.0 

5.2 

26.1 

13.4 

23.1 

18.1 

3.4 

1.8 

10.9 

11.5 

3.7 

14.7 

16.4 

5.5 

5.7 

11.4 

9.4 

3.0 

7.2 

6.1 

4.3 

7.5 

10.9 

3.9 

5.0 

12.2 

3.2 

5.3 

13.0 

19.7 

22.2 

4.7 

7.6 

9.0 

6.1 

5.1 

36.3 

29.9 

23.6 

3.2 

2.0 

15.3 

53.8 
5.8 
2.4 

4.7 

5.2 

8.0 

10.5 

13.3 

20.9 

1.9 

10.9 

15.4 

23.3 

15.6 

3.0 

4.4 

16.9 

6.1 

6.0 

17.8 

12.8 

6.4 

2.4 

12.1 

8.2 

4.5 

3.5 

4.1 

12.1 

12.2 

10.1 

3.9 

3.0 

6.3 

3.9 

7.7 

7.7 

14.7 

8.9 

5.5 

6.3 

11.9 

6.0 

6.2 

25.0 

22.9 

6.9 

4.9 

7.6 

6.1 

31.9 

2.8 

4.7 

4.6 

8.7 

3.9 

5.2 

11.9 

14.4 

1.4 

6.6 

12.4 

20.1 

12.2 

2.5 

2.7 

7.0 

1.8 

4.6 

16.0 

10.3 

7.6 

3.5 

13.7 

7.2 

5.0 

4.1 

3.5 

2.1 

10.7 

7.8 

3.7 

1.9 

9.3 

4.1 

4.7 

8.9 

6.9 

9.9 

5.6 

3.0 

9.8 

5.2 

4.5 

14.9 

32.7 

65.3 

2.3 

9.1 

6.2 

Official   figures  kindly  furnished  by  Richard   C.   Lappin,   Chief  Statistician,   Division 
of    Vital    Statistics,    Bureau    of    the    Census,  U.   S.   Dept.   of  Commerce. 


fever.  The  curve  is  not  only  lowered,  but  it  is  also  changed  in  char- 
acter. The  remaining  typhoid  after  the  water-borne  infection  has  been 
removed  is  known  as  residual  typhoid,  and  the  curve  in  such  cases  is 
spoken  of  as  the  "normal"  typhoid  curve.  The  normal  curve  shows  a 
distinct  summer  prevalence  recurring  with  marked  uniformit}'  each  year, 
and  lacks  the  great  irregularities  which  characterize  the  curve  of  a  com- 
munity drinking  badly  infected  water.  ISTormal  typhoid  is  endemic  ty- 
phoid; Sedgwick  has  proposed  the  name  "prosodemic"  {proso,  through, 
and  demos,  the  people)  as  more  expressive  of  this  type  of  the  disease. 
The  amount  of  residual  typhoid  varies  markedly  in  different  localities; 
thus,  it  is  twice  as  high  in  the  southern  as  in  the  northern  part  of  our 
countr5\    Eesidual  typhoid  should  not  exceed  5  deaths  per  100,000  pop- 


110    DISEASES  SPREAD  BY  THE  ALVTNE  DISCHARGES 

ulation.  It  is  due  to^carriers,  milk,  other  food,  contacts,  flies,  etc.,  and 
may  be  controlled  by  sanitary  housecleaning. 

Channels  of  Entrance  and  Exit. — The  typhoid  bacillus  probably  al- 
ways enters  by  the  mouth.  Typhoid  fever  is  generally  regarded  as 
primarily  a  gastro-intestinal  infection,  although  the  disease  itself  is 
not  produced  unless  the  blood,  glands,  and  other  structures  of  the 
body  are  invaded  v/ith  the  specific  microorganism.  The  disease  is  now 
regarded  as  primarily  a  blood  infection  or  bacteremia.  The  typhoid 
bacillus  grows  and  multiplies  in  the  intestinal  tract,  penetrates  the  mu- 
cosa, and  thus  invades  the  body.  The  bacilli  leave  the  body  mainly 
in  the  feces  and  urine,  occasionally  in  the  sputum  and  other  discharges. 
Typhoid  bacilli  appear  in  the  feces  early  in  the  disease;  sometimes  be- 
fore the  fever.  Later  in  the  disease  they  diminish  in  number  and  usu- 
ally disappear  during  convalescence,  although  they  may  continue  indefi- 
nitely (see  Bacillus  Carriers) .  The  feces  may  contain  only  a  few  typhoid 
bacilli;  usually  they  are  present  in  considerable  numbers;  occasionally 
practically  replacing  the  colon  bacillus. 

Typhoid  bacilli  commonly  appear  in  the  urine  about  the  second, 
third,  or  fourth  week.  They  grow  well  in  this  fluid  both  within  and 
without  the  body,  and  may  be  present  in  such  enormous  numbers  that 
the  urine  resembles  a  24-hour-old  bouillon  culture.  From  the  standpoint 
of  prevention,  it  is  very  important  not  to  neglect  the  virus  in  the  nrine. 
Hexamethylenamin  in  ten-grain  doses  or  more,  three  times  a  day,  di- 
minishes the  frequency  of  typhoid  bacilluria.  This  drug  is  eliminated  as 
formaldehyd,  provided  the  urine  is  acid,  and  is  therefore  not  effective  in 
an  alkaline  urine. 

The  sputum  ordinarily  does  not  contain  the  bacilli  unless  there  is  a 
pneumonia  or  severe  bronchitis.  Gould  and  Quales,  and  also  Purjesz 
and  Perl,*  have  found  typhoid  bacilli  in  about  50  per  cent,  of  the  cases 
by  rubbing  the  gums,  tonsils,  and  tongue  of  patients  suffering  with  ty- 
phoid fever.  The  microorganisms  from  the  mouth  were  found  as  late 
as  the  fourth  to  eighth  week  of  convalescence.  These  findings  are  im- 
portant from  the  standpoint  of  diagnosis  and  prevention.  The  bacilli  may 
be  eliminated  with  the  discharges  from  suppurating  middle  ears ;  from 
abscesses,  such  as  periostitis,  months  and  even  years  after  the  disease. 

Diagnosis. — An  early  diagnosis  of  typhoid  fever  is  essential  for  the 
successful  treatment  of  the  patient,  and  is  of  vital  importance  in.  con- 
trolling the  spread  of  the  infection.  Early  diagnosis  can  only  be  assured 
through  laboratory  methods.  Typhoid  bacilli  may  be  readily  isolated 
from  the  blood,  the  feces,  or  the  urine. 

Blood  Cultures. — Probably  the  easiest  method,  as  well  as  the  one 
giving  the  maximum  information,  is  through  blood  cultures.  The  tak- 
ing of  a  little  blood  for  this  purpose  is  no  more  difficult  or  annoying 

*Wien.  klin.  Woch.,  1912,  XXV,  1494. 


TVriloll)   Kl-'.VKK  111 

to  the  patient  than  s\\al)l)in^f  the  Ihitiat  I'nr  diplilhcria.  A  few  drops 
of  blood  may  be  obUiined  by  puneturini^  the  lobe  of  tiie  ear  or  the  finger, 
with  the  \isual  iireiaiitions  to  prevent  bacterial  contaniination.  A  much 
better  method,  however,  consists  in  withdrawing  5  to  lU  e.  c.  of  blood 
by  means  of  a  syringe  from  (inc  of  the  veins  at  the  bend  of  the  elbow. 
The  technic  is  very  simple,  and,  if  the  needle  is  sharp,  the  patient 
scarcely  feels  the  puncture.  The  blood  may  be  planted  in  bouillon,  or  in 
bile.  After  24  hours  in  the  incul)ator,  any  growth  that  occurs  is  trans- 
planted to  Endo's  medium,  colonics  isolated,  and  tested  for  agglutina- 
tion. Often  a  pure  culture  is  ol)taincd  in  the  first  medium,  so  that  the 
diagnosis  may  l)c.  established  in  21  hours — at  most,  in  2  or  3  days. 

Typhoid  iKuilli  ai)pcar  in  tlie  blood  early  in  the  disease,  perhaps 
occasionally  during  the  prodromal  symptoms.  Kayscr  obtained  positive 
results  from  90  per  cent,  in  the  first  week,  ()5  per  cent,  in  the  second, 
42  per  cent,  in  the  third,  35  per  cent,  in  the  fourth.  Our  results  in 
AVashington  were  approximately  the  same.  The  typhoid  bacilli  prob- 
ably do  not  grow  in  the  blood  during  life.  Their  presence  in  the  blood 
stream  represents  an  overflow  from  the  spleen  and  lymphatic  tissues. 
The  presence  of  typhoid  bacilli  in  the  blood  may  be  taken  to  mean  ty- 
phoid fever.  The  same  cannot  always  be  said  if  they  are  found  in  the 
feces  or  urine. 

The  Feces. — From  the  feces  or  urine  typhoid  Ijacilli  are  best  iso- 
lated upon  Endo's  medium.'^  This  consists  of  a  4  per  cent,  alkaline  agar 
containing  fuchsin,  which  has  been  decolorized  with  sodium  sulphite. 
Upon  the  surface  of  this  medium  typhoid  colonies  appear  in  24  hours 
as  translucent,  dewdrop-like  colonies,  whereas  colon  bacilli  and  other 
organisms  that  produce  acid  and  split  the  fuchsin  appear  as  red  colonies. 
Suspicious  colonies  are  fished  and  may  be  tested  at  once  under  the  micro- 
scope for  agglutination,  or  may  be  planted  in  bouillon  to  obtain  a  growth 
sufficient  for  macroscopic  agglutination  tests.  In  an}'  critical  case  pure 
cultures  should  be  obtained  and  studied  for  morphological,  cultural,  and 
other  biological  characters.  The  specimen  of  feces  may  be  preserved 
hours  or  days  by  placing  it  in  glycerin,  ®  one  part  of  feces  to  2  parts 
of  30  per  cent,  glycerin.  This  percentage  of  glycerin  has  the  further 
advantage  of  keeping  down  B.  coli  and  other  associated  bacteria. 

Technic. — Mal^e  plain,  nutrient,  sugar-free  agar  as  follows :  Tap 
water  (cold),  one  thousand  cubic  centimeters;  powdered  agar,  fifteen 
grams;  peptone  '  (Witte),  ten  grams;  meat  extract  (Liebig),  three 
grams.  Cook  in  double  boiler  one  hour.  Make  the  reaction  just  al- 
kaline to  litmus  by  the  cautious  addition  of  XaOH.  Cook  fifteen  min- 
utes to  set  the  reaction,  and  then  filter  through  absorbent  cotton. 

'Otlior  useful  media  are:  Drigalski-Cunradi,  Kruiiiwiede  or  Russell's  dou- 
ble sugar. 

"Teague  and  Clurman:     Jour.  Inf.  Dis.,  XVIII,  6,  June,  1916,  p.  653. 


113     DISEASES  SPEEAD  BY  THE  ALVINE  DISCHAEGES 

The  tap  water  should  be  as  cold  as  possible  and  the  agar  should  be 
"dusted"  on  the  surface  and  allowed  to  settle  into  the  medium  before 
heat  is  applied  and  before  the  other  ingredients  are  added. 

After  filtration,  the  medium  is  stored  in  flasks  containing  known 
amounts,  conveniently  in  one  hundred-cubic-centimeter  lots,  and  steri- 
lized in  the  autoclave. 

To  use  the  medium:  (a)  Prepare  a  ten  per  cent,  solution  of  fuch- 
sin  in  ninety-six  per  cent,  alcohol,  (b)  Prepare  a  ten  per  cent,  solu- 
tion of  sodium  sulphite  in  water. 

Add  one  cubic  centimeter  of  (a)  to  ten  cubic  centimeters  of  (b) 
and  heat  in  the  Arnold  sterilizer  for  twenty  minutes  =  (c). 

Add  one  per  cent,  of  lactose  (which  must  be  chemically  pure)  to 
the  agar  medium  described  above,  and  heat  in  the  Arnold  sterilizer 
until  the  medium  is  melted  and  the  lactose  thoroughly  distributed  in 
it.  The  decolorized  fuchsin  solution  (c)  is  then  added  in  the  pro- 
portion of  one  cubic  centimeter  of  the  mixture  to  each  one  hundred 
cubic  centimeters  of  medium;  then  thoroughly  mixed. 

Plates  are  then  poured  and  allowed  to  harden  (with  the  covers  re- 
moved) in  the  incubator  for  thirty  minutes,  after  which  time  they  are 
ready  for  inoculation. 

Preparation  of  Feces  for  Inoculation. — The  feces  are  collected  pref- 
erably in  the  small  rectal  tubes  described  by  Kendall.'^  A  small  por- 
tion of  feces  (about  a  loopful)  is  thoroughly  emulsified  in  ten  cubic 
centimeters  of  sugar-free  broth,  and  preferably  incubated  one  hour  at 
37°  C.  prior  "to  the  inoculation  of  the  plates.  This  preliminary  incu- 
bation does  two  things:  the  clumps  of  bacteria  settle  down,  leaving  a 
more  uniform  suspension  of  bacteria  in  the  supernatant  fluid  for  inocu- 
lation, and  these  bacteria  undergo  a  slight  development  in  a  medium 
particularly  suited  for  their  growth.  The  thin  suspension  of  the  stool 
is  noAV  rubbed  upon  the  surface  of  the  agar  plates  by  means  of  a  bent, 
sterile,  glass  rod,  and  the  plates  incubated  for  18  hours  at  37°  C.  The 
suspicious  translucent,  colorless  colonies  are  removed  entire  to  small 
test  tubes  containing  one  cubic  centimeter  of  broth  and  incubated  for 
two  hours  at  37°  C.  At  the  end  of  this  time  there  will  be  sufficient 
growth  to  make  the  customary  microscopic  agglutination  tests.  Con- 
firmatory cultural  characters  may  be  obtained  by  inoculating  suitable 
media  from  the  same  tubes  as  those  from  which  the  organisms  for  agglu- 
tination were  obtained. 

Physicians  should  encourage  boards  of  health  to  furnish  diagnostic 
aids  of  a  laboratory  nature.  Such  work  should  be  in  the  hands  of 
specialists  rather  than  entrusted  to  those  who  make  occasional  anal- 
yses.    Early  and  accurate  diagnosis  is  just  as  important  to  prevent  the 

''Boston  Med.  and  Surg.  Jour.,  CLXIV,  No.  1,  Sept.,  1911. 


TYPHOID  FEVER  113 

spread  of  other  communicable  diseases  as  it  is  with  tyj>hui(l.  Those 
facts  emphasized  here  will  not  be  repeated  uiidcu-  each  disease. 

Bacillus  Carriers.''* — About  33  per  cent,  of  cases  continue  to  discliarf^^e 
typhoid  bacilli  for  three  weeks  after  the  onset  of  tlio  disease,  and  about 
11  per  cent,  for  8  to  10  weeks;  these  are  known  as  coHvaJcscnil  carriers. 
From  2  to  4  per  cent,  of  all  cases  continno  to  discharji^e  typlidid  bacilli 
indefinitely;  these  are  chronic  or  permanent  carriers.  '^ry])lioid  bacilli 
are  found  in  the  stools  of  some  ]iersons  witliout  a  clinical  history  of  hav- 
ing had  the  disease;  these  are  pnssirr.  carriers,  also  called  healthy  or 
normal  carriers.  Albert  states  that  25  per  cent,  of  all  chronic  ty])hoid 
carriers  have  never  had  typhoid  fever,  and  further  estiniales  tliat  1  in 
every  1,000  of  the  i^eneral  population  is  a  carrier.  In  our  \Vashin,<^ton 
studies,®  Ave  found  0.3  per  cent,  of  the  population  in  1!)0S  to  l)e  tem- 
porary passive  carriers.  At  the  Strassburg  Station  (li)03-5)  Klinger 
reported  11  or  O.Gl  per  cent,  of  1,700  healthy  individuals  to  be  temporary 
passive  carriers,  and  12  to  be  permanent  carriers.  In  my  laboratory  at 
Harvard,  specimens  from  over  2,000  healthy  persons  were  examined  in 
1917,  with  only  one  typhoid  carrier — a  man  who  had  the  disease  several 
years  before.  The  per  cent  of  carriers  naturally  varies  with  time,  place, 
personnel,  and  prevalence  of  typhoid  fever, 

Woinen  outnumber  men  as  carriers  about  4  to  1,  About  80  per  cent, 
of  all  chronic  carriers  and  about  60  per  cent,  of  temporary  carriers  are 
females.  Women  are  more  subject  to  inflammation  of  the  gall-bladder 
and  to  gall  stones,  and  it  is  now  well  understood  that  typhoid  bacilli 
localize  and  maintain  themselves  in  the  gall-bladder  and  bile  ducts.  The 
gall-bladder  is  the  source  of  the  fecal  typhoid  bacilli  found  in  carriers. 
Children  are  less  subject  to  gall-bladder  disease,  and  therefore  seldom 
become  carriers.  The  significance  of  these  facts  is  of  importance  in 
looking  for  carriers,  special  attention  being  given  to  women  who  have 
or  have  had  symptoms,  however  slight,  in  connection  with  the  gall- 
bladder or  liver.  The  remarkable  tendency  of  women  to  become  car- 
riers is  particularly  hazardous  when  we  bear  in  mind  their  intimate  asso- 
ciation with  the  handling  and  preparation  of  food. 

Typhoid  carriers  are  either  fecal  or  urinari/,  or  both;  the  former  is 
more  frequent  than  the  latter,  and  apparently  also  more  dangerous ;  that 
is,  most  outbreaks  of  typhoid  fever  traced  to  carriers  turn  out  to  be  indi- 
viduals who  discharge  typhoid  bacilli  in  the  feces  rather  than  in  the  urine. 

It  seems  that  some  carriers  are  more  dangerous  than  others.  This 
is  due  partly  to  personal  habits,  partly  to  opportunity  to  infect  food  and 
drink,  and  partly  to  the  virulence  of  the  organism.  Further,  carriers 
are  quite  irregular  in  the  elimination  of  typhoid  bacilli. 


See  also  pages  401-2. 

Rosenau,    Lumsden   and   Kastle:      Uyff.    Lah.    Bull.,   "No.   52,   U.    S.   Public 
Health  Service,  p.  124. 


S  T?^ 


114     DISEASES  SPREAD  BY  THE  ALA^IXE  DISCHAEGES 

Typhoid  carriers  in  dairies  have  been  responsible  for  many  outbreaks. 
A  carrier  employed  as  a  cook,  waiter,  nurse,  or  in  a  dairy  is  a  special 
menace.  A  very  large  percentage  (from  5  to  -±U  per  cent.)  of  cases  of 
typhoid  fever  have  been  traced  to  carriers.  Carriers  have  a  greater 
opportunity  to  spread  the  infection  than  bed-ridden  cases.  The  amount 
of  harm  which  a  single  individual  can  cause  is  amazing. 

The  story  of  "Typhoid  Maet"  was  the  first  of  its  kind  to  be  re- 
ported ^  in  America,  and  has  become  a  classic.  ]\Iary  Mallon  was  a  cook 
in  a  family  for  three  years,  and  in  1901  she  developed  typhoid  fever. 
About  the  same  time  a  visitor  to  the  family  had  the  disease.  One  month 
later  the  laundress  in  this  family  was  taken  ill. 

In  1902,  Mary  obtained  a  new  place,  and  two  weeks  after  her  arrival 
the  laundress  was  taken  ill  with  typhoid  fever.  In  a  Aveek,  a  second  case 
developed,  and  soon  seven  members  of  the  household  were  si.ck. 

In  1904,  the  cook  went  to  a  home  on  Long  Island.  There  were  four 
in  the  family,  besides  seven  servants.  Within  three  weeks  after  her 
arrival,  four  servants  were  attacked. 

In  1906  Mary  went  to  another  family,  and  six  of  the  eleven  mem- 
bers of  this  family  were  attacked  with  typhoid  between  August  27th 
and  September  3rd.  At  this  time,  the  cook  was  first  suspected.  She 
entered  another  family  on  September  21st,  and  on  October  5th  the 
laundress  developed  typhoid  fever. 

In  1907,  she  entered  a  home  in  Xew  York  City  and  two  months 
after  her  arrival  two  eases  developed,  one  of  which  proved  fatal.  During 
these  five  years,  "Typhoid  Mary"  is  kno\\Ti  to  have  been  the  cause  of 
twenty-six  cases  of  typhoid  fever. 

She  was  virtually  a  prisoner  by  the  Xew  York  Department  of  Health 
in  a  hospital  from  March  19,  1917.  Cultures  taken  every  few  days 
showed  bacilli  on  and  off  for  three  years.  Sometimes  the  stools  contained 
enormous  numbers  of  typhoid  bacilli,  and  again  for  days  none  could 
be  foimd. 

"Typhoid  Mary"  then  escaped  from  observation  until  1914.  In  Oc- 
tober of  that  year,  she  was  engaged  as  cook  in  the  Sloane  Hospital  for 
"Women  in  Xew  York.  In  January  and  February  of  1915,  an  outbreak 
of  typhoid  occurred,  principally  among  the  doctors,  nurses  and  help  of 
the  institution,  involving  twenty-five  cases.  The  cook  was  suspected, 
but  she  left  the  premises  on  a  few  hours'  leave,  and  did  not  return  or  leave 
her  address.  She  was,  however,  located  by  the  Health  Department 
under  an  assumed  name,  and  an  investigation  established  her  identity  as 
the  famous  "Typhoid  Mary." 

A  subsequent  study  of  her  career  showed  that  she  had  infected  still 
other  individuals  beyond  those  already  mentioned,   and  that   she  ma\ 

V.  A.  M.  A.,  June  1.5,  1907,  XLVIII,  p.  2019.  Military  Surgeon,  July,  1910, 
— a  review  of  the  facts  by  Geo.  A.  Soper. 


TYPHOID  FEVER  115 

have  given  rise  to  the  avcU  known  water-borne  outbreak  of  typhoid  in 
Itliaca,  Xew  York,  in  1903,  involving  over  1,300  cases  (see  page  11T7). 
The  fact  is  that  a  person  by  the  name  of  Mary  Mallon  had  been  em- 
ployed as  a  cook  in  the  vicinity  of  the  place  where  the  fir.<t  case  appeared, 
and  from  which  contamination  of  the  water  supply  occurred. 

Sawyer  ^°  reports  a  very  instructive  history  of  a  typhoid  carrier 
(H.  0.)  responsible  for  several  outbreaks.  The  carrier  was  carefully  stud- 
ied over  a  period  of  several  years,  during  which  time  he  infected  thirty 
persons,  five  of  whom  died.  Frequent  examinations  of  feces  of  this  car- 
rier gave  negative  results  for  four  months  after  he  had  been  treated  witli 
autogenous  typhoid  vaccines;  nevertheless,  he  infected  three  persons 
Avhen  suljsequently  released  from  quarantine  on  parole.  The  removal  of 
the  gall-bladder  failed  to  cure  II.  0.,  for  typhoid  bacilli  were  found  in 
the  feces  several  times  after  the  operation.  It  is  particularly  noteworthy 
that  41  successive  examinations  of  feces  during  a  period  of  fourteen 
months  all  proved  negative,  yet  the  typhoid  bacillus  was  finally  isolated 
from  the  stomach  contents  containing  bile.  This  carrier,  on  account  of 
the  virulence  of  the  organism,  or  careless  personal  habits,  is  unusually 
dangerous  and  represents  a  class  that  should  be  controlled  by  quarantine 
or  close  supervision.  He  further  illustrates  the  saying  "once  a  carrier, 
always  a  carrier,^'  which  seems  to  be  true  of  chronic  typhoid  carriers. 

Another  instructive  outbreak  caused  by  a  carrier  is  reported  by 
Sawyer  ^^  in  which  93  cases  of  tA'phoid  fever  occurred  in  Hanford,  Cal., 
as  a  result  of  infected  food  served  at  a  public  dinner.  The  vehicle  of 
infection  was  a  large  pan  of  spaghetti  prepared  by  a  carrier.  This  dish 
was  baked  after  it  had  been  infected,  but  this  baking  was  shown  by 
laboratory  experiments  to  have  incubated  the  bacteria  instead  of  disin- 
fecting the  food. 

The  Widal  reaction  is  present  in  the  blood  of  about  60  to  75  per 
cent,  of  typhoid  bacillus  carriers.  It  is,  therefore,  of  value  as  a  pre- 
liminary test  in  the  epidemiological  search  for  carriers.  In  blood  test- 
ing for  this  purpose  dilutions  of  1 :50  and  1 :25,  and  even  a  titer  of  1 :10, 
may  be  used.  The  test  should  be  made  with  both  B.  typhosus  and.  B. 
paraiyphosus  a  and  p.  The  bacilli  should  then  be  searched  for  in  the 
urine  and  feces  of  those  giving  a  positive  reaction.  It  should  be  remem- 
bered that  about  90  per  cent,  of  persons  immunized  with  typhoid  vac- 
cine will  give  a  positive  agglutination  reaction,  and  that  on  the  other 
hand  it  may  be  very  weak  in  a  carrier. 

The  question  of  preventing  the  spread  of  the  disease  through  bacil- 
lus carriers  is  important  and  difncult.  Surgical  methods  fail  to  cure 
carriers,  for  the  typhoid  bacillus  may  continue  to  grow  in  the  bile  ducts 
after  removal  of  the  gall-bladder,  and  perhaps  also  in  the  small  intes- 

^Jour.  A.  M.  A.,  June  19,  1915,  LXR',  25.  p.  2051. 
"^Jour.  A.  M.  A.,  Oct.  31,  1914,  LXIII,  IS,  p.  1537. 


116     DISEASES  SPBEAD  BY  THE  ALVINE  DISCHAEGES 

tine.  Nichols^  Simmons  and  Stimmel  ^^  believe  that  the  so-called  uri- 
nary typhoid  carriers  are  really  kidney  carriers,  and  can  be  cured  by 
nephrectomy;  that  intestinal  carriers  are  really  bile  passage  carriers  of 
two  kinds:  (a)  cases  in  which  the  gall-bladder  alone  is  infected 
and  which  can  be  cured  by  cholecystectomy,  and  (b)  cases  in  which 
gall-bladder  and  bile  passages  are  both  infected,  and  which  cannot  be 
cured  by  surgical  measures. 

Medical  measures,  such  as  hexamethylenamin,  are  efficient  for  bacil- 
luria,  but  are  of  no  avail  in  the  fecal  carriers.  Attempts  have  been  made 
to  relieve  the  condition  by  the  use  of  bacterial  vaccines.  Petruschky  ^^ 
and  also  Header  have  reported  encouraging  results,  especially  with  the 
use  of  autogenous  cultures.  Hektoen  suggests  the  use  of  kaolin,  which 
acts  by  adsorption.  Most  cases  resist  all  attempts  to  relieve  the  condi- 
tion. It  is  unnecessary  to  place  bacillus  carriers  incommunicado. 
It  is  sufficient  to  restrict  their  activities  so  that  they  cannot 
infect  food  or  their  surroundings.  With  proper  care  and  cleanliness 
typhoid  carriers  may  present  little  danger  to  their  fellow  men.  This, 
however,  requires  intelligence  and  conscientiousness.  The  problem,  at 
present,  is  to  detect  the  carriers,  so  as  to  establish  a  sanitary  isola- 
tion, if  not  an  actual  quarantine.  See  Eecognition  of  Carriers,  page 
111. 

A  chronic  carrier  should  never  be  allowed  to  handle  or  prepare  food, 
even  though  a  number  of  consecutive  examinations  prove  negative.  The 
intermittent  and  irregular  character  of  the  carrying  state  should  be 
borne  in  mind.  Gregg  reports  a  carrier  who  had  typhoid  fever  53  years 
before,  and  Bolduan  and  Noble  one  of  46  years  standing,  who  then 
caused  a  large  milk-borne  outbreak.  Compulsory  control  of  irrespon- 
sible carriers  is  essential.  The  prevention  and.  cure  of  the  carrying  state 
is  one  of  the  practical  and  rewardful  problems  for  research. 

Resistance  of  the  "Virus. — The  typhoid  bacillus  has  no  spore.  It  is, 
therefore,  comparatively  easy  to  destroy.  The  only  difficulty  present- 
ing itself  is  getting  at  the  bacillus  when  imbedded  in  fecal  masses. 
When  dry,  most  typhoid  bacilli  die  in  a  few  hours;  occasionally  a  few 
survive  for  months.  The  fact  that  typhoid  bacilli  are  killed  by  drjdng 
renders  infection  through  dust  unlikely. 

When  a  moist  medium,  such  as  water,  milk,  or  urine,  is  heated  to 
60°  C,  practically  all  the  typhoid  bacilli  such  a  medium  may  contain 
are  killed.  An  exposure  at  60°  C.  for  20  minutes  will  surely  kill  all  of 
these  microorganisms.  They  are  not  destroyed  by  freezing.  See  Eela- 
tion  to  Ice,  page  1184  et  seq. 

In  their  resistance  to  germicides  typhoid  bacilli  behave  like  the  aver- 
age  non-spore-bearing   bacilli.      Thus,    bichlorid   of    mercury,    1-1,000; 

^^Jour.  A.  M.  A.,  Aug.  30,  1910,  Vol.  LXXTIT.  No.  9,  p.  680. 
"Dettt.  med.  Woclischr.,  July  11,  1912,  XXXVIII,  28. 


TYrHOID  FEVER  117 

phenol  21A  per  cent;  formalin,  10  \)vr  cent,  are  effective  upon  the 
naked  germs.  In  order  to  kill  the  typhoid  bacilli  in  feces  special  pre- 
cautions or  stronger  solutions  are  necessary  (see  page  143'2). 

The  viability  of  typhoid  bacilli  in  feces  is  very  variable,  depending 
on  the  composition  of  the  feces  and  tlio  varieties  of  other  bacteria 
present.  Sometimes  the  typhoid  bacilli  in  feces  perish  in  a  few  hours, 
often  in  a  day;  under  certain  circumstances  they  may  live  for 
much  longer  periods.  In  the  Plymouth  epidemic  typhoid  bacilli  prob- 
ably remained  alive  and  virulent  in  the  feces,  exposed  to  the  winter's 
cold,  for  several  months.  Levy  and  Kayser  found  that  they  remained 
alive  in  feces  for  5  months  in  the  Avintcr.  The  life  of  the  organism  in 
privies  and  in  water  is  usually  comparatively  short.  In  nature  they 
seldom  if  ever  live  in  water  beyond  7  days,  and  are  often  dead  in  48 
hours.  They  probably  live  longer  in  clean  water  than  in  contaminated 
water.  In  the  outer  world  antibiosis  plays  an  important  part,  also  the 
presence  of  deleterious  chemicals,  temperature,  light,  desiccation,  sun- 
light, and  other  factors  known  to  be  injurious  to  spore-free  bacteria. 
As  a  rule,  the  typhoid  bacillus  does  not  survive  long  in  the  soil  under  the 
usual  conditions. 

Typhoid  Bacillus  in  Nature. — The  typhoid  bacillus  should  be  re- 
garded as  a  pathogen,  not  as  a  saprophyte.  It  lives  and  grows  prin- 
cipally in  the  human  body.  It  has  a  tendency  to  die  in  water,  air, 
soil,  upon  fomites,  or  in  nature  generally.  The  grand  exception  to  this 
statement  is  in  the  case  of  milk,  in  which  the  typhoid  bacillus  grows 
well. 

The  typhoid  bacillus  may  live  12  days  in  crude  sewage  (Firth)  ;  1-i 
days  in  a  septic  tank  (Pickard)  ;  4  months  in  butter  (Bailey  and  Field)  ; 
5  days  in  home-made  cheese  (Heim)  ;  12  days  in  pot  cheese  (Lemke)  ; 
39  days  in  ice  cream  (Mitchell).  It  is  destroyed  in  24  hours  in 
■milk,  butter-milk,  whey  or  butter  having  an  acidity  of  0.3  to  0.4 
per  cent.  Krumwiede  and  ISToble  found  that  with  a  moderate  con- 
tamination, typhoid  bacilli  are  killed  in  sour  cream  in  about  four 
days. 

In  endemic  centers  the  typhoid  bacillus  is  much  more  widely  dis- 
tributed in  man  than  the  cases  indicate.  Thus,  in  the  District  of 
Columbia,  of  1,000  healthy  persons  examined  during  the  typhoid  season 
of  1908,  typhoid  bacilli  were  found  in  the  feces  in  3  instances."  At 
least  one  and  perhaps  two  of  these  individuals  were  regarded  as  tem- 
porary carriers.  In  each  instance  the  organisms  were  found  only  once. 
The  population  of  the  District  of  Columbia  in  1908  was  300,000,  and  at 
the  ratio  of  1  per  1,000  this  would  represent  about  300  healthy  persons 
in  that  community  harboring  and  shedding  typhoid  bacilli  for  a  brief 
period  of  time  during  the  typhoid  season. 

"Roscnau,  Lumsdeii  and  Kastle:     I^i/ff-  Lab.  Bull.,  No.  52,  U.  S.  P.  H.  S. 


118     DISEASES  SPREAD  BY  THE  ALVINE  DISCHARGES 


MODES  OF  SPREAD 

Typhoid  fever  is  spread  from  cases  and  carriers  both  by  direct  or 
indirect  contact — indirect  through  water,  milk,  milk-products,  oysters, 
and  other  foods;  also  flies,  fingers,  and  fomites.  Each  of  these  modes 
of  spread  needs  separate  consideration. 

Man  is  the  source  of  the  infection,  and  the  disease  must  be  fought 
in  the  light  of  an  infection  spread  directly  and  indirectly  from  man  to 
man. 

Water. — Water-borne  typhoid  is  a  common  occurrence.  Not  long 
ago  it  was  regarded  as  the  sole  or  usual  mode  of  spread;  now  we  know 
that  this  was  a  mistake.  Most  fecal  matter  ultimately  finds  its  way 
to  water;  most  water  courses  draining  inhabited  regions  are  contam- 
inated with  human  feces.  Surface  water  is,  therefore,  apt  to  contain 
typhoid  bacilli.  The  f-act  that  there  may  be  no  clinical  case  of  typhoid 
fever  in  the  drainage  area  is  no  guarantee  that  the  water  may  not  be 
infected — in  view  of  the  prevalence  of  missed  cases  and  bacillus  carriers. 

Fortunately,  typhoid  bacilli  do  not  grow  and  multiply  in  Avater 
under  natural  conditions.  They  usually  die  in  a  few  days,  and  rarely 
persist  longer  than  7  days.  They  succumb  more  quickly  in  some  waters 
than  others,  more  quickly  in  summer  than  winter.  Euediger  ^^  has 
shown,  that  typhoid  bacilli  disappear  much  more  rapidly  from  polluted 
water  during  the  summer  months  than  during  the  winter  months  when 
the  river  is  protected  with  a  covering  of  ice  and  snow. 

Water  plays  a  large  but  diminishing  role  in  the  spread  of  typhoid 
fever.  The  great  water-borne  epidemics  have  overshadowed  the  other 
modes  of  communication.  We  know  that  the  larger  part  of  the  typhoid 
now  prevalent  in  this  country  is  not  water-borne;  Whipple  in  1908 
estimated  it  at  35  per  cent.;  it  is  now  certainly  much  less.  Typhoid 
fever  may  be  excessively  prevalent,  even  epidemic,  in  a  city  having  a 
water  supply  of  good  sanitary  quality. 

In  the  vast  majority  of  cases  water-borne  typhoid  is  contracted  from 
a  surface  supply,  that  is,  a  river,  small  stream,  pond,  or  lake.  Ground 
water  becomes  a  source  of  danger  only  under  special  conditions,  espe- 
cially in  limestone  regions.     See  chapter  on  Water. 

Water-borne  epidemics  present  certain  definite  characteristics.  They 
almost  always  occur  in  the  spring,  fall,  or  winter,  when  the  water 
is  cold.  Most  of  the  great  water-borne  epidemics  have  occurred  in 
northern  cities,  both  in  this  country  and  in  Europe.  They  usually 
have  a  sharp  onset,  the  curve  rises  to  a  peak,  and  declines  rapidly. 
The  pollution  is  usually  nearby;  that  is,  there  is  a  rather  direct  trans- 
fer of  fresh  virulent  infection.     Granting  that  the  typhoid  bacillus  does 

« Jotw.  Am.  Pub.  Health  Assn.,  June,  1911,  Vol.  I,  No.  16,  p.  411. 


TYPHOID     FKVEn,    1902    TO    lOlC 
(Doixth    Rate    per   100,000    of    Population) 


ciTy 


Richmond  boToujh.K.y. 
2u«nstx)rouflh.Y.K. 
Cam6fli.X.J. 
iQiii^((,Mas5. 


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Dayton.  Ohio 
Mfmphfe.Ttnn 


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5anAnfomo.Taa3 

^duannfllt.fifl 


Nfiul-on.flass. 


Mcu)  Orleans,  La. 
Covington  .xy. 
Richmond.Ua. 
LouisuUU,Kij. 
AHantfl,6fl 


S<attk.Wash. 
Euansuilk.lni. 
Springncli.lU. 
Gran6HapiAi5,Wic(i. 
Wllminaron.  Del. 
Lancasftr.Pa. 
Mauist'ura.Pa. 
ii)ti«linfl  ]})  \h\. 


flinnwpolis.Mino. 
ToU^o.Ohio 
Cincinnati. Ohio 
Ph»la6c(phia,Pa. 
AUwheny.Pa. 
Pi^^sburd  Pa 


RochcsKrA'.y. 

Suracusf.ar.y. 

Fall  R\v<r,<na35. 

Brockron.Mass. 

Taunton.Mass. 

Hav<rhUl,tiass. 

PorHan6,01e. 

Sfll^m,Mns5i 


MllwauKfe  Wis. 

t)etroit,Mich. 

Chicago.  111. 

Buffalo.X.a. 

iTit.Pa. 

CUuclani.OJiio 

PulLith  Minn 


Tucnburg.rtass. 
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Somcrviut  .i:\as5. 
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BTi6flcport,Cc»nn. 
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cndsea.Wass. 
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BrooKlun  PoTOUjfi.A'.y. 
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HE  N0HKi3  rETKRS  CO.,  WASMtNCT< 


Fig.  11. — Influence  of  Public  Water  Supplies  on  the  Typhoid  Feveb  Death 

Rate 

(Diagram  prepared  by  Marshall  0.  Leighton,  U.  S.  Geological  Survey,  from 
figures  furnished  by  Dr.  Cressy  L.  Wilbur,  Chief  Statistician  of  Vital  Sta- 
tistics, Bureau  of  tlie  Census — from  Kober.) 


119 


120     DISEASES  SPREAD  BY  THE  ALVINE  DISCHAEGES 

not  grow  in  cold  water,  there  must  have  heen  a  very  considerahle  dilu- 
tion in  most  of  the  epidemics. 

The  follovring  examples  are  given  of  the  fact  that  "water-borne 
outbreaks  of  t}'phoid  fever  occur  during  the  winter,  fall,  or  early- 
spring,  when  the  water  is  cold.  Thus  we  have  the  water-borne  epidemic 
in  Plymouth,  Penn.,  in  1SS5,  which  began  with  the  spring  thaw  and 
doubtless  came  from  the  frozen  accumulation  of  t3T3hoid  excrement 
from  a  single  case.  Yery  similar  to  the  Plymouth  outbreak  was  that  at 
New  Haven,  Conn.,  in  1901.  The  outbreak  at  Ithaca,  X.  Y.,  started 
in  epidemic  proportions  in  January.  The  epidemic  in  Sherboume,  Eng- 
land, in  1873,  likewise  started  in  January.  Four  acute  epidemic  exacer- 
bations are  recorded  in  Philadelphia  in  December  of  the  years  1884, 
1890,  1899,  and  1903.  Several  similar  epidemics  have  occurred:  in  the 
Avinter  time  in  Chicago — one  in  January,  1890,  another  in  January, 
1896,  and  one  in  March,  1891.  Another  striking  instance  Is  the  epi- 
demic in  JSTewark,  IST.  J.,  in  February,  1899,  and  one  in  December,  1891. 
Abroad,  epidemics  are  recorded  in  Berlin  in  Februar}',  1899,  in  Paris  in 
February,  1894,  and  in  Yienna  in  Xovember,  1888.  All  af  thjese  are 
generally  believed  to  have  been  water-borne  'and  must  have  taken  place 
when  the  water  was  very  cold.  In  fact,  as  previously  pointed  out,  ex- 
tensive water-borne  epidemics  of  typhoid  fever  rarely  occur  in  the  sum- 
mer time.  i1~t~ 

It  was  formerly  thought  that  a  high  typhoid  rate  necessarily  meant 
badly  infected  water.  "We  know  now  that  this  does  not  necessarily  fol- 
low, as  has  been  proved  by  the  experiences  in  Washington,  Winnipeg, 
army  camps,  and  many  southern  cities. 

Almost  all  the  water-borne  epidemics  of  typhoid  fever  rest  upon  cir- 
cumstantial evidence.  It  is  difficult  to  isolate  the  typhoid  bacillus  from 
water,  and  the  damage  is  usually  done  before  suspicion  points  to  the 
water.^^ 

It  is  clear  that  in  cities  which  have  had  safe  water  supplies  for  a 
period  of  years  the  typhoid  death  rate  (residual  typhoid)  should  not 
be  above  5  per  100,000,  unless  some  unusual  conditions  exist,  such  as 
poor  control  of  railk,  or  lack  of  control  over  patients  and  carriers,  and 
disregard  of  modern  sanitary  knowledge. 

Ko  single  measure  in  reducing  typhoid  fever  on  a  large  scale  ap- 
proaches the  effect  of  substituting  a  safe  for  a  polluted  water  supply.  As 
an  instance  of  this  wholesale  saving  of  human  life,  the  reduction  of 
typhoid  fever  in  four  American  cities  is  shown  in  Fig.  13. 

Ice. — Ice  may,  under  exceptional  circumstances,  occasionally  be  the 
vehicle  by  Avhieh  typhoid  bacilli  are  transferred.  Freezing  does  not  kill 
B.  typhosus,  but  there  is  a  great  quantitative  reduction  not  only  in  the 

^*  Examples  of  water-borne  outbreaks  of  typhoid  fever  will  be  found  in  the 
chapter  on  Water. 


TYPHOID  FE\KI{ 


121 


act  of  freezing,  hut  during  storage;  hence  the  danger  is  greatly  lessened. 
The  only  suggestive  outbreak  of  typhoid  fever  attributed  to  ice  was 
reported  by  ITutchins  and  Wheeler  in  1903  in  the  St.  Lawrence  Hospital, 
three  miles  below  Ogdensburg.  A  few  other  instances  in  which  ice  is 
believed  to  have  conveyed  the  infection  have  been  reported,  but  are  based 
upon  flimsy  evidence.  The  fact  that  natural  ice  is  usually  stored  many 
weeks  or  months  before  it  is  used  is  a  sanitary  safeguard.    Manufactured 


P/TTSBURGH,  ?t\.  - 

-Typh 

01 D  Fever. 

D£ATH  MTE  PCK   100.000  /900  TO   1910. 

1900 

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1903 

iqott 

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1909 

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Fig.   12. — IMMEDIATE  AND  Steikixg  Effect   of  Purifying  a  Badly  Infected 
Wateb  Supply  upon  the  Typhoid  Situation. 


ice  made  from  distilled  water  and  handled  with  cleanly  methods  is  above 
reproach.  For  a  discussion  of  ice  in  relation  to  typhoid  fever  and  other 
infections,  see  page  1188  et  seq. 

Milk. — Trask  collected  317  typhoid  epidemics  up  to  1908  caused  by 
infected  milk.  Since  then .  many  more  instances  have  come  to  light. 
Doubtless  many  milk  outbreaks  have  escaped  attention  or  have  been 
attributed  to  water  or  other  sources.  The  typhoid  bacillus  grows  well 
in  milk,  and  it  is  now  realized  that  this  medium  is  a  frequent  and 
important  mode  of  communication.     Most  milk  outbreaks  are  reported 


122     DISEASES  SPREAD  BY  THE  ALVINE  DISCHAEGES 

from  England  or  America.  On  account  of  the  almost  universal  custom 
of  boiling  the  milk  in  European  and  tropical  countries,  milk  outbreaks 
are  rarely  reported  from  these  regions.  During  our  four  years'  study  of 
typhoid  fever  in  Washington,  it  was  found  that  at  least  10  per  cent,  of 
the  cases  were  milk-borne. 

The  milk  usually  becomes  contaminated  on  the  farm,  from  a  case 
or  a  carrier.  It  may  also  become  infected  in  transportation,  at  the  city 
dairy,  or  in  the  home.  Milk  outbreaks  come  abruptly,  rise  to  a  peak  like 
a  water  epidemic,  and  subside  rather  sharply.  There  are  comparatively 
few  secondary  cases.  Milk-borne  epidemics  of  typhoid  fever  have  certain 
characteristics  which  permit  ready  recognition. 


o       so      AO     6  0      eo     lOo     lao      i4o      i6o     iso     aoo       | 

1903   pi 

1904  ■■ 

1905 

VVa.UrTowft.Xr. 

1906 

1982 

■ 

1893 

w 

1894 

Lawrence,  Miss. 

1895 

1996 

1898 

m 

mmmlgg^^i^^ 

1899 

w 

1900 

1 

AlbaiiiiXr 

1901 

I90&  H 

BB^^i  1 

■ 

1908 

Cincinnati.  Onio. 

Fig.   1.3. — Abrupt  Reduction  in  Death  Rates  from  Typhoid  Fever  Incident 

TO  Water  Purification  in  Four  American  Cities. 
Column   X. — The   Black   Squares   Indicate   Raw   Water    and   the   Clear    Squares 

Filtered  Water. 


(a)  There  is  a  special  incidence  of  the  disease  on  the  track  of  the 
implicated  milk  supply.  The  disease  follows  the  route  of  the  milk 
wagon.    The  outbreak  is  localized  to  such  areas. 

(b)  The  better  class  of  houses  are  invaded,  and  persons  in  better  cir- 
cumstances generally  suffer  most. 

(c)  Those  who  drink  milk  are  chiefly  affected  and  those  suffer  most 
who  are  large  consumers  of  raw  milk. 

(d)  The  incidence  is  high  among  women  and  children. 

(e)  The  incubation  period  may  be  shortened  perhaps  on  account  of 
the  large  amount  of  infection  taken. 

(f)  More  than  one  case  occurs  simultaneously  in  a  house.  This  is  a 
very  suspicious  circumstance  to  the  epidemiologists.  The  .first  indication 
of  a  milk  outbreak  in  a  city  with  a  good  water  supply  is  usually  the  fact 


TYIMIOII)  FKVEl?  123 

that  two  or  more  persons  in  a  liouscliold  come  down  witli  lyiilioid  fever 
within  a  few  days  of  each  other. 

(g)  Clinically  the  disease  often  runs  a  mild  course,  owing  to  the 
fact,  no  doubt,  that  the  virus  becomes  attenuated  in  the  process  of  mul- 
tiplication in  iho  milk.  In  water-borne  typhoid  the  same  germs  are 
ingested  that  were  passed ;  in  milk-borne  typhoid  it  may  be  the  succeed- 
ing generations  tliat  are  ingested. 

Milk-borne  outbreaks  are  sometimes  very  extensive.  One  of  the 
largest  epidemics  occurred  in  Boston  (Jamaica  Plain)  in  March  and 
April,  1908.  Four  hundred  and  ten  cases  were  reported;  348  of  them 
drank  the  suspected  milk.  Among  the  first  victims  of  the  disease  was 
the  milkman,  wlio  was  believed  to  have  infected  the  milk  through  tasting 
it.  The  number  of  persons  involved  in  a  milk-borne  epidemic  varies 
greatly,  depending  upon  the  amount  of  milk  infected  and  other  factors. 
It  must  not  be  uncommon  for  a  single  bottle  of  milk  or  a  small  quantity 
to  become  infected,  and  thus  transmit  the  disease  to  one  or  two  persons. 
Such  instances  are  exceedingly  difficult  to  trace.  Ofttimes  the  milk 
becomes  infected  from  a  carrier.  An  instance  of  this  occurred  in  "Wash- 
ington (Georgetown)  in  1908.  In  this  case  the  milkmaid  had  typhoid 
fever  18  years  previously.  Examinations  showed  almost  pure  culture  of 
B.  typJiosus  in  her  feces.  Fifty-five  persons  who  drank  the  infected 
milk  contracted  the  disease. 

Milk  Products. — Fresh  milk  products,  such  as  cream,  ice  cream, 
butter,  and  buttermilk,  and  fresh  cheese,  may  contain  the  typhoid  bacil- 
lus, and  are  occasionally  media  of  communication. 

Cream  contains  more  bacteria  than  the  milk  from  which  it  is  taken. 

The  use  of  infected  cream  in  coffee,  on  cereals,  etc.,  is  sufficient  to  cause 

the  disease.     Several  instances  in  the  Washington  studies  were  traced 

■  to  such  use  of  cream.  As  a  rule,  coffee  in  the  cup  is  not  hot  enough  to 

kill  the  typhoid  bacillus,  if  present  in  the  cream  added. 

In  "Washington  several  cases  of  the  disease  were  traced  to  ice  cream. 
Mitchell  working  in  my  laboratory  found  that  B.  typhosus  survives  in 
ice  cream  for  from  12  to  39  days.  Lumsden^'  traced  the  Birmingham, 
Alabama,  outbreak  in  1916,  and  another  in  Chattanooga,  Tennessee,  in 
1917,  to  ice  cream.  An  outbreak  at  Helm,  California,  in  1916,  was 
found  by  Cumming  to  be  due  to  ice  cream.^® 

Bruck  has  sho-«Ti  that  the  typhoid  bacillus  will  live  in  butter  for  27 
days. 

BuitermUk  may  be  quite  as  dangerous  as  the  cream  from  which  it 
is  derived.  The  acidity  and  overgrowth  of  other  organisms  is  said  to 
kill  the  typhoid  bacillus  in  24  hours.  In  clieese  the  time  of  fer- 
mentation,   antibiosis,    etc.,    lessens    the   likelihood    of    survival    of    the 

"Am.  Jour.  Public  Health,  December,   1917, 
"J.  A.  M.  A.,  April  21,  1917,  LXVIII,  16. 


124    DISEASES  SPEEAD  BY  THE  ALVINE  DISCHARGES 

typhoid  bacillus.  Fresh  cream  cheese,  such  as  cottage  cheese,  may  be 
responsible  for  an  occasional  case. 

Oysters,  Mussels,  and  Shellfish. — The  first  outbreak  of  typhoid 
fever  attributed  to  this  source  was  investigated  by  Conn  at  Wesleyan 
University,  Middletown,  October,  1894.  Twenty-five  cases  were  attrib- 
uted to  eating  infected  oysters;  4  died.  Not  all  of  those  who  took  sick 
had  clinical  typhoid  fever.  Some  had  gastro-intestinal  disturbances  with 
illness  lasting  but  a  few  days.  About  one-quarter  of  those  attending  the 
dinners  at  which  the  oysters  were  served  were  made  ill. 

A  similar  instance  occurred  at  the  Mayors'  banquets  at  South  Hamp- 
ton and  Winchester,  in  1903. 

Dr.  L.  W.  Darra  Mair^^  showed  that  much  of  the  typhoid  fever  in 
Belfast,  Ireland,  from  1897  to  1901,  was  due  to  eating  cockles  and  mus- 
sels taken  from  sewage  polluted  water.  The  amount  of  the  fever  dimin- 
ished markedly  and  its  seasonal  prevalence  was  changed  by  "betterment 
of  the  shellfish  situation. 

In  Brighton,  England,  Dr.  J.  T.  C.  Nash^"  proved  that  much  of  the 
typhoid  fever  in  the  Borough  of  Southhead-on-Sea  prior  to  1899  was  due 
to  infected  oysters.  There  was  a  sharp  reduction  in  the  amount  of  fever 
when  the  fore  shore  fisheries  were  stopped,  and  almost  a  cessation  of  all 
cases  when  attention  was  given  to  all  shellfish,  including  the  improved 
laying  and  cooking  of  cockles. 

In  the  Washington  studies  it  seems  that  oysters  and  shellfish  play  a 
minor  role  in  the  spread  of  the  disease,  which  occurs  mostly  in  the  sum- 
mer time,  while  oysters  and  similar  sea  food  are  relished  mainly  in 
winter.  Comparatively  few  of  the  cases  studied  gave  a  history  of  having 
eaten  oysters  within  30  days  prior  to  the  onset  of  the  disease.  Oysters 
become  dangerous  when  consumed  soon  after  taking  them  from  a  pol- 
luted bed,  or  when  floated  or  bloated  in  infected  water.  For  further 
discussion  of  this  topic,  see  page  840. 

Fruits  and  Vegetables. — Vegetables,  such  as  celery,  lettuce,  water 
cress,  and  radishes,  partaken  raw,  and  grown  on  land  fertilized  with 
fresh  night  soil,  may  be  infected,  and  this  probably  accounts  for  an 
occasional  case.^^  Vegetables  so  contaminated  are  not  made  safe  by  the 
ordinary  methods  used  in  preparation  of  such  food  for  table  use.  In 
large  cities  it  is  practically  impossible  to  trace  this  source  of  infection. 
It  therefore  remains  more  a  suspicion  than  a  conviction.  An  outbreak 
which  occurred  in  the  summer  of  1905,  in  Springfield,  Mass.,  was  attrib- 
uted to  infected  fruits  and  vegetables. 

At  a  wedding  breakfast  in  Philadelphia  June  24th,  with  43  guests  in 

"Proc.  Roy.  Soc,  Epidemiology  Sec,  April,  1909,  Vol.  II.  Part  2. 

^  Idem. 

^'Melick,  J.,  Infcts.  Dis.,  Vol.  XXI,  No.  1,  July,  1917,  p.  38. 


TYrilOII)  FEVER  125 

attendance,  19  persons  ate  watercress  sandwiches.'^  Eighteen  of  these 
were  ill  July  2'2nd  with  typhoid  fever,  only  2  of  them  beiiiii;  in  Thilu- 
delphia  at  the  time,  while  the  other  K!  were  scattered  in  suburban  terri- 
tory and  in  summer  resorts  along  the  Atlantic  Coast  as  far  north  as 
Maine.  The  watercress  had  been  secured  from  a  farm  on  which  the 
sanitary  conditions  were  quite  unsatisfactory.  A  similar  outbreak  oc- 
curred in  Hackney,  London,  in  1903,  although  the  evidence  in  that  out- 
break was  not  so  convincing.  ]\Iorse  -^  reports  an  outbreak  presumably 
due  to  celery. 

Creel  -*  found  typhoid  bacilli  upon  the  tips  of  leaves  of  plants  culti- 
vated in  contaminated  soil.  Under  conditions  most  unfavorable  to  the 
B.  typhosus  the  infection  lasted  at  least  31  days — a  period  sufficiently 
long  for  some  varieties  of  lettuce  and  radishes  to  mature. 

Vegetable  salads  are  sometimes  accused  of  conveying  typhoid  and 
other  infections,  but  in  these  instances  it  is  more  apt  to  be  the  salad 
dressing  than  the  salad  itself.  See  an  outbreak  reported  by  Leake  due 
to  mayonnaise  dressing  prepared  by  a  person  in  the  early  stage  of  the 
disease.^^ 

Flies. — The  evidence  is  now  complete  that  the  common  house  fly 
(Musca  domestica)  may  convey  the  infection  of  typhoid.  It  is  not  inap- 
propriately called  the  typhoid  fly.  The  typhoid  bacilli  may  be  smeared 
upon  the  feet  or  other  parts  of  the  insect,  or  may  live  in  the  intestinal 
tract  and  pass  in  the  dejecta  in  almost  pure  culture.  Flies  live,  feed, 
and  breed  in  fecal  matter  and  decomposing  organic  substances  of  all 
kinds.  It  is  easy  to  see  how  they  may  convey  infections  from  this  source 
to  our  food,  lips,  or  fingers.  Alice  Hamilton  isolated  typhoid  bacilli  from 
5  out  of  18  house  flies  captured  in  Chicago  in  the  privy  and  on  a  fence 
near  a  sick  room  during  a  local  water-borne  epidemic.  It  has  been  shown 
experimentally  that  living  typhoid  bacilli  may  remain  upon  the  bodies 
of  flies  for  as  long  as  23  days.  Special  attention  to  the  role  played  by 
the  fly  was  given  by  Eeed,  Vaughan,  and  Shakespeare  in  their  studies  of 
the  prevalence  of  typhoid  fever  in  our  army  camps  in  1898.  They 
concluded  that  flies  undoubtedly  served  as  carriers  of  the  infection  and 
attributed  about  15  per  cent,  of  the  cases  to  this  mode  of  communica- 
tion. They  found  that  "flies  swarm  over  infected  fecal  matter  in  the  pits 
and  then  deposit  it  and  feed  upon  the  food  prepared  for  the  soldiers  at 
the  mess  tents.  In  some  instances,  where  lime  had  recently  been 
sprinkled  over  the  contents  of  the  pits,  flies  with  their  feet  whitened 
with  lime  were  seen  walking  over  the  food."  The  danger  from  fly  trans- 
mission varies  very  much,  and  depends  upon  circumstances.  In  a  camp 
it  is  considerable;  in  a  well  sewered  city  the  risk  is  diminished.     In  our 

^Engineering  I^^eics,  Aug.    14,   1913. 

'^Report  State  Board  of  Health  of  Mass.,  1899,  p.  751. 

"^  Public  Health  Reports,  Feb.  9.   1912.  p.  187.  XXVIl.  6. 

^Public  Health  Reports,  Sept.  17,  1920,  Vol.  XXXV,  No.  38,  p.  2197. 


126     DISEASES  SPEEAD  BY  THE  ALVINE  DISCHAEGES 

Washington  studies  we  could  find  no  relation  between  fly  abundance  in 
the  summer  of  1908  and  typhoid  prevalence.  It  is  not  possible  to  express 
mathematically  the  percentage  of  cases  caused  by  flies — the  figures  would 
vary  greatly,  depending  upon  circumstances.  The  danger  of  typhoid 
from  flies  in  cities  has  doubtless  been  overstated.  However,  if  only  one 
per  cent,  of  the  cases  were  thus  transmitted,  the  suppression  of  flies 
would  still  be  quite  worth  while  (page  312). 

Dust. — Typhoid  bacilli  soon  die  when  dried,  especially  when  exposed 
to  the  sun  and  air.  Dust-borne  infection  in  this  disease  must  be  rare. 
In  the  South  African  War  there  were  frequent  dust  storms  in  some  local- 
ities, so  that  the  food  was  covered  with  dust  and  sand.  Some  of  the 
infection  was  believed  to  have  been  conveyed  in  this  way. 

Fomites. — The  infection  may  be  conveyed  upon  soiled  linen, 
blankets,  and  other  objects.  It  was  believed  by  Eeed,  Yaughan,  and 
Shakespeare  that  the  clothing,  blankets,  and  tents  in  the  Spanish- 
American  War  became  infected  and  were  a  prime  factor  in  spreading  the 
disease.  After  the  South  African  War  some  of  the  blankets  used  by  the 
troops  were  sent  back  to  England  and  used  on  a  training  ship,  on  which 
typhoid  fever  appeared.  The  blankets  were  found  to  be  dirty  and  soiled 
with  fecal  matter,  from  which  Klein  is  reported  to  have  obtained  living 
typhoid  bacilli.  The  danger  of  fomites  contaminated  with  fresh  infec- 
tion is  real,  and  emphasizes  the  importance  of  disinfecting  bedding, 
towels,  handkerchiefs,  body  linen,  and  other  fabrics. 

Soil. — The  soil,  long  regarded  as  the  most  important  factor  in  the 
spread  of  typhoid  fever,  and  by  Pettenkofer  and  others  considered  an 
essential  element,  is  now  given  scant  consideration.  Pollution  of  the 
soil,  however,  cannot  be  disregarded.  The  typhoid  bacillus  may  live  fcr 
a  long  time  in  sewage-soaked  earth,  A  polluted  soil  may  endanger  the 
water,  milk,  and  other  foods,  or  infect  indirectly  through  flies  and  other 
means.   For  more  extended  information  on  this  subject,  see  Section  VII. 

Contact  Infection. — "Contact"  is  a  convenient  term  to  indicate 
the  spread  of  infection  directly  or  indirectly  as  a  result  of  close  associa- 
tion between  the  sick  and  the  sound.  Actual  contact  is  not  necessarily 
implied.  The  term  is  used  to  indicate  the  transfer  of  the  infection 
through  a  short  intervening  space  in  a  brief  period  of  time  (see  page 
461).  Thus  the  infection  may  be  passed  from  one  to  another  through 
kissing,  soiled  hands,  remnants  of  food,  infected  thermometers,  or  tongue 
depressors,  contaminated  towels  or  other  fabrics;  cups,  spoons,  glasses, 
etc.  If  the  nurse  infects  a  cup  of  milk  or  glass  of  water  that  carries  the 
infection  to  another  member  of  the  household,  such  cases  are  included 
under  "contacts."  The  infection  may  also  be  spread  in  the  household  by 
flies,  fingers,  and  various  other  means,  usually  difficult  to  trace,  and 
which  are,  therefore,  all  included  under  this  group.  Eegarded  in  this 
light,  contacts  play  a  large  role  in  the  spread  of  the  disease. 


TYPHOID  FEVER  127 

Extensive  nuini(ii)al  out  breaks  have  been  repoiifd  as  largely  or  en- 
tirely due  to  contact  infection.  Winslow  in  1901  studied  such  an  out- 
break in  Newport.  Others  have  been  reported  from  Knoxville,  Winni- 
peg, Springfield,  and  from  Germany  and  England.  Jvoch  regarded  the 
spread  of  typhoid  in  Triur  in  the  light  of  contact  infection.  Freeman 
says  that  the  majority  of  outbreaks  in  the  smaller  towns  of  Virginia  are 
due  to  this  cause.  Extensive  outbreaks  in  institutions  are  often  due  to 
contact  with  mild  t'ases  or  carriers.  *'Flies.  fingers,  and  lood"  (Sedg- 
wick), and  "dirt,  diarrhea,  and  dinner"  (Chapin),  which  too  often  get 
sadly  confused,  explain  the  occurrence  of  many  a  case  of  contact  infec- 
tion in  typhoid  fever  as  well  as  other  diseases. 

In  army  camps  with  clean  water  and  good  milk,  contact  infection 
may  rise  to  epidemic  proportions.  In  the  Spanish-American  War,  of 
107,361  of  our  troops  in  camp,  20,738  contracted  typhoid,  mostly  by 
"contact";  1,580  died.  Similar  conditions  prevail  in  rapidly  growing 
cities,  in  crowded  apartments,  and  in  congested  regions  with  a  susceptible 
population  and  other  favoring  conditions.  The  danger  of  contact  is  well 
shown  by  the  frequency  with  which  nurses,  ward  attendants,  house 
physicians,  and  others  similarly  exposed  take  typhoid  fever.  Studies  of 
the  incidence  of  the  disease  in  the  Massachusetts  General  Hospital,  Bos- 
ton, in  the  Presbyterian  Hospital,  Philadelphia,  and  in  the  Johns  Hop- 
kins Hospital,  Baltimore,  show  that  typhoid  fever  was  at  least  twice  and 
may  be  eight  times  as  prevalent  among  those  who  came  in  close  and  fre- 
quent association  with  the  patient  as  among  the  population  at  large. 
Further,  the  disease  contracted  under  such  conditions  seems  to  run  a 
course  of  more  than  ordinary  severity,  with  a  greater  number  of  compli- 
cations and  with  a  high  mortality.  This  is  doubtless  due  largely  to  the 
fact  that  the  contactors  receive  fresh  virulent  virus. 

In  our  studies  of  typhoid  fever  in  Washington  we  were  impressed 
with  the  importance  and  frequency  of  contact  infection  in  that  endemic 
center.  In  1907  we  attributed  6  per  cent,  of  the  cases  to  contacts;  in 
1908,  15  per  cent._,  and  in  1909,  17  per  cent.  This  included  only  contact 
with  cases  during  the  febrile  stage  of  the  disease.  In  Strassburg,  Kayser 
attributed  16.8  per  cent,  of  the  cases  occurring  during  3  years  in  that 
city  to  contact  infection.  Little  groups  of  cases  following  a  primary 
cia.se  in  a  suburban  focus,  in  my  experience,  frequently  fall  in  the  cate- 
gory of  contacts. 

Typhoid  fever,  in  view  of  all  the  facts,  must  now  be  regarded  as  a 
"contagious"  disease.  We  will  never  have  an  end  of  it  until  it  is  so 
regarded  and  managed  accordingly. 


128    DISEASES  SPEEAD  BY  THE  ALVINE  DISCHAEGES 


TYPHOID  VACCINES 

Preventive  Typhoid  Inoculations. — An  active  immunity  to  typhoid 
fever  may  be  induced  by  introducing  dead  typhoid  bacilli  into  the 
subcutaneous  tissue.  The  procedure  is  harmless,  rational,  and  effective. 

Our  knowledge  of  inoculations  against  typhoid  fever  began  with  the 
work  of  Pfeiffer  and  Kolle,^''  who  inoculated  two  volunteers  in  1896. 
About  the  same  time  Almroth  Wright  ^^  inoculated  several  persons,  and 
in  1898  continued  the  work  upon  an  extensive  scale  in  India  upon  4,000 
British  soldiers.  In  1900,  during  the  Boer  War,  Wright,  together  with 
Leishman,  prepared  a  vaccine  ^^  and  supervised  the  inoculation  of  100,000 
British  troops.  The  results  in  India  were  quite  encouraging,  but  for 
various  reasons  the  same  procedure  in  South  Africa  was  not  as  satisfac- 
tory as  had  been  anticipated.  Prophylactic  inoculation  on  the  advice  of 
Koch  was  used  by  the  .Germans  in  the  Herero  campaign  in  southern  West 
Africa  in  1904.  The  prophylactic  was  voluntary  and  only  about  half  of 
the  command  (7,287  men)  availed  themselves  of  it.  The  results,  while 
good,  fell  short  of  expectations.  In  this  country  Eichardson  was  the  first 
to  advocate  and  practice  inoculations  as  a  means  of  protection  against 
typhoid  fever.  The  best  results  have  been  obtained  in  the  United  States 
Army  where  typhoid  inoculations  were  recommended  as  a  voluntary  pro- 
tection in  1909,  but  were  made  compulsory  in  1911. 

Leishman  ^^  in  his  Harben  lecture  (1910)  explains  the  lack  of  success 
in  early  years  by  saying  that  the  vaccine  may  have  been  made  less 
efficient  by  the  use  of  too  great  heat  in  killing  the  bacilli.  Further,  it 
should  be  noted  that  smaller  doses  and  fewer  injections  were  given  then 
than  now.  It  is  well  to  know  that  it  took  about  ten  years  to  establish 
the  efficiency  of  typhoid  prophylactic  inoculations. 

The  typhoid  vaccines  may  be  prepared  in  a  number  of  different  ways. 
Usually  dead  bacilli  are  used,  although  live  bacilli  have  been  inoculated. 
The  bacilli  may  be  killed  either  with  the  aid  of  heat  or  germicidal  sub- 
stances ;  the  dead  or  live  bacilli  may  be  sensitized  by  the  addition  of  anti- 
typhoid serum;  the  vaccines  may  be  prepared  with  pulverized  bacilli, 
from  bacillary  extracts,  or  by  the  use  of  various  chemical  methods. 

Lipovaccines  are  made  by  suspending  the  bacilli  in  a  fluid  fatty 
substance  of  suitable  consistency.  The  vegetable  oils  are  better  for 
this  purpose  than  the  animal  fats.  Lipovaccines  are  absorbed  slowly 
and  therefore  the  entire  amount  can  be  inoculated  at  one  time.    Experi- 

^'Pfeiflfer  and  Kolle:     Deutsche  med.  Woohnschr.,  1896,  XXII,  735. 

*' Wright:  Lancet,  London,  Sept.  19,  1896,  807;  Brit.  Med.  Jour.,  Jan.  30, 
1897,  16. 

="The  material  injected  is  called  a  vaccine  and  the  process  is  spoken  of  as 
vaccination.     The  term  in  this  connection  is  a  little  confusing. 

^Leishman,  W.  B.:    Jour.  Roy.  Inst.  Pub.  Health,  London,  1910,  XVIII,  394. 


TYPHOID  FEVER 


129 


ments  indicate  that  liiiovaccim's  have  only  about  one-half  the  protective 
power  of  saline  .^suspensions.     See  Lipovaccincs,  [)aj;e  ol^li. 

T"'^sually  the  vaccine  is  made  from  a  twenty-four-hour-old  culture 
killed  by  heatinfj  to  53°  C.  for  thirty  minutes,  depending  upon  phenol 
(0.5  per  I'ciit.)  to  kill  any  bacilli  thai  may  have  survived.  Overheating 
impairs  the  immunizing  j^ower  of  the  vaccine.  IMost  typhoid  bacilli  die 
before  the  temperature  reaches  60°  C.  Some  of  the  strains  have  a  lower 
thermal  death  point.  Cultures  killed  without  heat  have  perhaps  greater 
protective  properties.  The  killed  cultures  are  suspended  in  saline  solu- 
tion,— isotonic  salt  solution. 

Certain  strains  seem  to  cause  the  production  of  more  antibodies  than 
others.  In  the  earlier  work  it  was  believed  that  the  more  virulent  strains 
produce  a  greater  protection.  This  is  doubtful,  for  it  appears  that  the 
protection  afforded  is  not  in  proportion  to  the  local  or  febrile  reaction, 
but  to  the  amount  and  variety  of  antibodies  stimulated.  The  Rawlins 
strain  is  now  greatly  used  in  this  country  for  experience  has  proved  its 
protective  power. 

The  injections  are  given  subcutaneously  at  intervals  of  from  five  to 
ten  days.  From  500,000,000  to  1,000,000,000  dead  typhoid  bacilli  are  in- 
jected at  each  inoculation.  The  number  of  inoculations  varies  with 
different  authorities.  At  least  3,  preferably  4,  should  be  given;  the 
greater  the  number  of  injections  the  greater  the  immunity  induced. 

The  reactions  are  usually  moderate  and  never  serious.  They  consist 
of  local  manifestations;  irritation,  and  inflammation  about  the  site  of 
inoculation,  such  as  pain,  redness,  swelling,  edema;  also  general  symp- 
toms, such  as  malaise,  pains  in  the  back  and  limbs,  and  fever.  The  num- 
ber and  character  of  the  reactions  in  the  experience  of  the  United  States 
Army  ^°  are  shown  in  the  following  table : 


Number  of 
doses 

Reaction, 
Absent 

Reaction, 
Mild 

Reaction, 
Moderate 

Reaction, 
Severe 

First    dose 

45,680 
44,321 
38,902 

68.2% 
71.3% 
78.0% 

28.9% 
25.7% 
20.3% 

2.4% 
2.6% 
1.5% 

0.3% 

0.2% 

Third  dose 

0.1% 

Children,  as  a  rule,  react  less  than  adults.  Of  1,101  persons  inocu- 
lated by  Hartsock,  11  per  cent,  showed  no  reaction,  83  per  cent,  mild 
reaction,  5  per  cent,  a  moderate  reaction,  and  1  per  cent,  a  severe  reac- 
tion. There  is  always  some  local  tenderness  and  redness  at  the  point  of 
inoculation.    The  systemic  symptoms  usually  pass  in  24  hours. 

The  best  time  to  give  the  treatment  is  late  in  the  afternoon,  for  then 
the  severest  part  of  the  reaction  is  over  by  the  morning.    The  injections 


Russell,  F.  F.:     Jour.  A.  M.  A.,  LVIII,  No.  18,  May  4,  1912. 


130    DISEASES  SPREAD  BY  THE  ALVINE  DISCHARGES 

are  usually  given  into  the  subcutaneous  tissue  of  the  outer  side  of  the 
arm  or  into  the  abdominal  wall;  sometimes  the  interscapular  space. 

There  is  no  laboratory  index  of  the  degree  or  duration  of  the  immu- 
nity produced  as  a  result  of  the  inoculations.  The  following  antibodies 
appear  in  the  blood :  agglutinins,  precipitins,  opsonins,  lysins,  stimulins ; 
agglutinins  persist  for  2  years  and  even  longer.  There  are  factors  in- 
volved in  the  immunity  not  understood,  and  therefore,  the  subsequent 
freedom  of  typhoid  fever  among  individuals  protected  in  this  manner  is 
the  only  index  of  value. 

The  negative  phase  advanced  by  Wright  and  denied  by  Leishman  and 
others  does  not  occur.  At  least  there  appears  to  be  no  increased  sus- 
ceptibility to  the  disease  during  the  so-called  negative  phase.  There 
is,  therefore,  no  known  objection  to  giving  the  prophylactic  to  those 
exposed  to  the  disease  or  during  an  epidemic.  In  fact,  the  typhoid  vac- 
cines have  been  used  as  a  therapeutic  agent  during  the  fever. 

The  immunity  varies  in  degree  and  also  in  duration ;  at  least  one  year 
(Pfeiffer  and  Kolle's  vaccine) ;  four  years  (Wright's  vaccine).  On  the 
average,  the  immunity  may  probably  be  depended  upon  for  about  3  years 
when  produced  by  4  injections  of  dead  bacilli. 

In  the  United  States  Army  typhoid  immunization  is  repeated  every 
three  years.  In  case,  however,  two  or  more  cases  occur  in  the  same  com- 
mand within  two  weeks,  then  the  entire  command  is  again  inoculated. 
The  experience  of  the  American  Expeditionary  Forces  showed  that  the 
immunity  is  not  sufficiently  strong  or  durable  to  protect  against  mass 
infections.  The  immunity  may  be  prolonged  or  renewed  by  recourse  to 
reinoculation. 

One  attack  of  typhoid  fever,  however  mild,  produces,  as  a  rule,  a 
lasting  immunity.  Second  attacks,  however,  occur.  Draschfeld's  fig- 
ures, based  on  2,000  persons  in  the  Antwerp  Hospital,  show  that  only 
0.7  per  cent,  of  that  number  were  affected  twice.  This  percentage  is 
doubtless  too  high,  for  the  figures  were  collected  before  our  knowledge 
of  paratyphoid  infections.  The  typhoid  vaccines  do  not  protect  against 
paratyphoid  infections,  and  contrariwise  paratyphoid  does  not  protect 
against  typhoid. 

In  the  United  States  Army,  where  the  vaccinations  are  done  under 
the  supervision  of  Major  Russell,  we  have  the  following  results : 

During  1913  the  army  had  only  two  cases  of  typhoid  in  the  enlisted 
force  of  over  80,000  men.  One  of  these  occurred  in  a  man  who  had  not 
been  vaccinated ;  the  other  was  among  the  troops  in  China,  who  had  been 
immunized  in  1911  and  the  history  of  the  case  is  in  doubt.  In  six 
years,  1909  to  1914,  there  was  only  one  death  from  typhoid  in  the  U.  S. 
Army,  while  the  rate  in  the  country  at  large  averaged  over  16.5  per  hun- 
dred thousand. 

The  health   record   established  by   the  Maneuver   Division   of  the 


TYPHOID  FEVER 


131 


TABLE   3. — ^TYPHOID,  1901-1012,  FOR  THE  WHOLE  ARMY.  AT  HOME  AND  ADROAD— 

OFFICERS   AND    ENLISTED   MEN 

(Not  Including  native  organizations,  as  Porto  Rican  Infantry  and  Philippine  Scouts.) 


Year 


1901. 
1902. 
1903. 
1904. 
1905. 
1906. 
1907. 
1908. 
1909* 
1910* 
1911* 
1912. 
1913. 
1914. 
1915. 
1916. 
1917. 
1918. 


Mean 

Cases 

Deaths 

Strengtli 

Ratios 

Ratios 

Number 

1,000  of 

Number 

1,000  of 

Case 

Mean 

of 

Mean 

Fatality 

Strength 

Strength 

81,885 

552 

6.74 

74 

.88 

13.0 

80,778 

565 

6.99 

69 

.85 

12.2 

67.643 

34  T 

5.14 

30 

.44 

8.6 

67,311 

293 

4.35 

23 

.33 

7.8 

65,688 

206 

3.14 

20 

.30 

9.7 

65,159 

373 

5.72 

18 

.27 

4.8 

62,523 

237 

3.79 

19 

.30 

8.0 

74.692 

239 

3.20 

24 

.31 

lO.O 

84,077 

282 

3.35 

22 

.26 

7.8 

81.434 

198 

2.43 

14 

.17 

7.1 

82,802 

70 

.85 

8 

.10 

11.4 

88,478 

27 

.31 

4 

.044 

14.8 

80,766 

4 

.04 

87,228 

7 

.07 

3 

.03 

42.8 

97.656 

8 

.08 

0 

.  .    • 

110.454 

25 

.24 

3 

.03 

12.0 

671,156 

297 

.44 

23 

.03 

7.7 

W'ld  War 

768 

.30 

133 

.05 

Occurring 

Among  Those 

Who  Were 

Vaccinated 


Deaths      Cases 


1 

7 
11 


*  Typhoid  vaccination  was  voluntary  during  1909  and  1910,  and  until  Sept.  30,  1911, 
when  It  was  made  compulsory  for  officers  and  men. 

United  States  Army  at  San  Antonio,  Texas,  during  the  summer  of  1911, 
is  a  triumph  in  preventive  medicine.  The  division  had  a  mean  strength 
of  12,801  men.  All  were  treated  with  the  typhoid  vaccines.  The  result 
was  that  from  March  10th  to  July  10th  only  two  cases  of  typhoid  fever 
developed;  no  deaths.  One  patient  was  a  private  of  the  hospital  corps 
who  had  not  completed  his  immunization,  having  taken  only  two  doses. 
His  case  was  very  mild  and  probably  would  have  been  overlooked  but  for 
the  rule  that  blood  cultures  were  made  in  all  cases  of  fever  of  over  48 
hours'  duration.  The  other  case  was  a  teamster  who  had  not  been  inocu- 
lated. Among  the  12,801  men  there  were  only  11  deaths  from  all  dis- 
eases. Typhoid  fever  prevailed  at  the  time  in  the  neighborhood.  Thus, 
there  were  49  cases  of  typhoid  fever  with  19  deaths  in  the  city  of  San 
Antonio  during  this  period.  This  contrasts  markedly  with  the  t}^hoid 
record  of  the  United  States  Army  during  the  Spanish-American  War, 
when  the  typhoid  record  of  a  division  of  volunteer  troops  camped  at 
Jacksonville,  Florida,  in  1898,  under  conditions  similar  to  those  at  San 
Antonio,  was  as  follows:  The  division  at  Jacksonville  had  2,693  cases 
with  248  deaths,  which  was  about  the  average  typhoid  incidence  of  the 
camps. 

The  U.  S.  Navy  had  only  seven  cases  among  50,000  men  during  the 
year  ending  June,  1913.  Four  of  these  occurred  among  men  treated  at 
a  tropical  station,  where  the  vaccine  had  deteriorated.  All  the  cases  were 
mild.  The  results  in  recent  years  are  still  better.  By  contrast,  in  1911 
the  rate  was  3.61  per  1,000. 


132    DISEASES  SPREAD  BY  THE  ALVINE  DISCHARGES 

Spooner  reports  that  in  the  Massachusetts  General  Hospital/^  among 
the  nurses  and  others  exposed  to  typhoid  fever,  80  per  cent,  of  whom  had 
been  inoculated  during  the  previous  three  years,  not  a  case  was  con- 
tracted, and  for  the  first  year  in  the  history  of  the  institution  (1912) 
there  were  no  cases  among  the  nurses  or  attendants.  The  morbidity  rate 
in  training  schools  for  nurses  in  Massachusetts  during  three  years  was 
nearly  nine  times  greater  in  the  uninoculated  than  among  the  inocu- 
lated. 

Metchnikoff  and  Besredka  ^^  failed  to  protect  chimpanzees  against 
typhoid  infection  by  means  of  killed  bacilli,  but  obtained  immunity 
apparently  as  definite  as  that  produced  by  an  attack  of  the  disease  by  the 
use  of  living  cultures.^^ 

Polyvalent  Vaccines, — It  is  now  customary  to  use  a  vaccine  con- 
sisting of  a  mixture  of  B.  typhosus,  B.  paratyphosus  a,  and  B.  para- 
typhosus  P  as  a  routine,  because  the  typhoid  vaccines  do  not  protect 
against  paratyphoid  infections,  and  vice  versa.  During  the  World  War, 
it  was  customary  to  add  other  cultures  such  as  cholera,  dysentery  or 
plague  to  the  mixture  for  troops  serving  in  localities  where  these  infec- 
tions prevailed.  These  various  mixtures  apparently  produce  no  greater 
reaction  than  the  single  typhoid  vaccine  and  induce  a  specific  active 
immunity  against  each  virus  represented  in  the  mixture.  Dose  nad  num- 
ber of  injections  remain  approximately  the  same  as  for  single  vaccines. 

Summary. — The  results  of  typhoid  inoculations  can  no  longer  be 
questioned.  The  morbidity  is  lowered  in  those  who  have  been  properly 
"vaccinated."  The  most  striking  effect  is  in  the  lowering  of  the  mor- 
tality. Preventive  typhoid  inoculations  involve  no  risk  whatever,  and 
•are  especially  applicable  to  those  unduly  exposed  to  the  infection, 
such  as  nurses,  hospital  attendants,  physicians,  travelers,  soldiers  in 
camps,  persons  in  epidemic  localities,  and  individuals  in  the  family  of  a 
bacillus  carrier.  Typhoid  vaccination  should  be  mandatory  in  asylums 
and  other  custodial  institutions.  The  method  is  serviceable  for  general 
use  among  the  public  in  endemic  foci,  but  it  is  a  question  whether  this 
artificial  method  of  acquiring  immunity  would  serve  as  good  a  purpose 
in  the  end  as  fighting  the  disease  along  the  lines  of  general  sanitation — 
which  has  been  so  successfully  done  in  many  European  centers.  It  would 
certainly  be  a  mistake  to  immunize  the  population  with  this  artificial 
method  to  the  neglect  of  general  sanitary  improvements,  such  as  good 
water,  clean  milk,  fly  suppression,  cleanliness,  and  personal  hygiene. 
Because  a  person  has  received  the  protection  afforded  by  typhoid  inocula- 
tions is  no  reason  for  reckless  disregard  of  other  prophylactic  measures. 
The  experience  of  the  American  Expeditionary  Forces  showed  that  vac- 

'^  Transactions  of  the  Assn.  of  Amer.  Physicians,  1912. 
"^Ann.  de  I'Inst.  Pasteur,  Dec,  1911,  XXV,  12,  p.  865. 
^^Ann.  de  I'Inst.  Pasteur,  Mar.  25,  1911,  and  Dec,  1911. 


TYPHOID  FEVER  133 

cination  is  a  partial  protection  only,  and  tliat  iyphoid  vaccination  is  no 
substiiiitc  for  sanilari/  precautions. 

Typhoid  vaiiination  can  bo  used  to  hclj)  t^upprcss  a  typhoid  epidemic. 

Management  of  a  Case  so  as  to  Prevent  Spread. — Success  depends 
upon  an  early  and  accurate  diagnosit;.  All  cases  of  typhoid  fever  and 
all  cases  suspected  of  being  typhoid  fever  should  be  isolated.  This  does 
not  mean  imprisonment  in  a  lazaretto.  The  proper  place  to  care 
for  typhoid  fever  is  in  a  suitable  hospital.  A  private  home  is  a  poor 
makeshift  for  a  hospital,  and  it  is  imreasonable  to  turn  a  household 
into  a  hospital  for  4  to  8  weeks  or  longer.  The  room  in  which  the 
patient  is  treated  should  be  large  and  well  ventilated,  and  should 
contain  no  unnecessary  furniture,  curtains,  carpets,  etc.  It  must  be 
well  screened  and  kept  scrupulously  clean,  dry  sweeping  and  dusting 
prohibited. 

The  case  should  be  reported  to  the  health  authorities  without  delay; 
the  house  should  be  placarded  so  as  to  warn  others,  and  visiting  dis- 
couraged. Under  no  circumstances  should  visitors  be  admitted  into  the 
sick  room. 

The  health  officer  should  send  an  epidemiologist  or  a  public  health 
nurse  without  delay  to  the  premises  to  instruct  and  to  see  that  all  neces- 
sary measures  are  being  taken. 

The  disinfection  of  the  stools.^  urine,  sputum,  and  other  excretions  is 
of  the  first  importance,  and  should  be  carried  out  with  great  care  and 
conscientiousness.  For  the  urine,  sufficient  bichlorid  may  be  added  to 
make  a  1-1,000  solution,  or  carbolic,  2.5  per  cent.,  or  formalin,  10  per 
cent.,  and  allowed  to  stand  one  hour  before  discarding.  Stools  may  be 
disinfected  with  bleaching  powder,  3  per  cent.;  milk  of  lime  (1  to  8) ; 
cresol,  1  per  cent.;  carbolic  acid,  5  per  cent.;  formalin,  10  per  cent.;  or 
unslacked  lime  and  hot  water  (page  1-432).  The  discharges  should  be 
received  in  a  glass  or  earthenware  vessel  containing  some  of  the  germi- 
cidal solution.  Then  add  more  of  the  solution  so  that  it  shall  be  present 
in  twice  the  volume  of  the  excreta  to  be  disinfected;  disintegrate  the 
masses  thoroughly  and  let  stand  at  least  two  hours,  protected  from  flies. 
Masses  are  so  difficult  to  penetrate  that  they  must  be  broken  up  thor- 
oughly with  a  wooden  paddle.  It  takes  a  strong  carbolic  solution  12 
hours  to  penetrate  the  interior  of  a  small  fecal  mass ;  larger  masses  are 
impenetrable  to  most  germicides. 

The  sputum  may  "be  burned  or  boiled.  Strong  carbolic  acid,  cresol, 
or  formalin  are  also  applicable. 

The  patient  should  have  his  own  dishes,  cups,  spoons,  glasses,  etc., 
which  should  be  scalded  after  each  use.  Eemnants  of  lunch,  especially 
meat,  milk,  gelatin,  broths,  and  other  organic  food  in  which  the  infection 
may  live  and  even  grow,  should  not  be  eaten  by  others.  Such  remnants 
may  be  burned  or  first  boiled  and  then  discarded.    Those  who  nurse  the 


134    DISEASES  SPREAD  BY  THE  ALVINE  DISCHARGES 

sick  should  keep  out  of  the  kitchen  on  account  of  the  risk  of  contam- 
inating the  food. 

Handkerchiefs,  towels,  sheets,  nightgowns,  and  all  fabrics  used  about 
the  patient  should  be  disinfected  either  by  boiling,  or  by  immersion  for 
one  hoir,  in  bichlorid  of  mercury,  1-1,000,  carbolic  acid,  2.5  per  cent.,  or 
cresol,  1  per  cent. 

The  water  used  to  bathe  the  patient  should  be  disinfected  before  it  is 
allowed  to  run  into  the  sewer.  This  may  be  done  by  heat  or  by  adding 
sufficient  carbolic  acid  or  bleaching  powder;  the  latter  is  cheapest  and 
most  practical. 

Milk  bottles  must  be  kept  out  of  the  sick  room.  In  any  case,  they 
should  be  scalded  before  leaving  the  house  and  again  disinfected  before 
returning  to  the  dairy. 

The  thermometer  should  be  kept  in  formalin,  alcohpl  or  other  suitable 
germicidal  solution.  Rectal  tubes,  especially  in  hospital  practice,  must 
be  carefully  disinfected  each  time  before  using.  Individual  instruments 
are  preferable. 

The  nurse  must  protect  herself  as  well  as  others;  a  solution  of 
bichlorid  should  be  kept  constantly  at  hand.  Every  time  the  patient  is 
bathed,  his  mouth  cleaned,  or  his  buttocks  washed,  the  hands  must  be 
washed  in  soap  and  water  and  disinfected.  The  nurse  muvst  exercise 
especial  care  if  she  is  to  go  to  the  kitchen  or  to  the  ice-box,  etc.,  as  is 
frequently  the  case  in  private  houses,  where  a  special  diet  kitchen  cannot 
be  provided.  The  nurses,  physicians,  ward  attendants,  and  others  par- 
ticularly exposed  should  protect  themselves  with  preventive  typhoid 
inoculations.  The  physician  should  be  quite  as  careful  as  the  nurse,  not 
only  that  he  may  not  carry  the  infection  to  himself  or  other  patients, 
but  also  that  his  practice  may  serve  as  a  stimulating  example. 

At  the  conclusion  of  the  case  a  general  cleansing  and  disinfection  of 
the  room  and  its  contents  should  be  practiced. 

Convalescents  should  not  be  given  liberty  imtil  the  danger  of  bacillus 
carrying  has  passed.  A  large  percentage  of  patients  continue  to  eliminate 
typhoid  bacilli  during  convalescence.  This  may  be  determined  only  by 
bacteriologic  examinations  of  the  stools  and  urine.  Four  successive 
negative  results  at  intervals  of  several  days  are  required  before  a  report 
may  be  vouchsafed  in  the  case  of  the  stools.  In  the  case  of  a  chronic 
bacillus  carrier,  the  failure  to  find  typhoid  bacilli  in  the  stools  is  no 
assurance  of  cure.  In  Sawyer's  case  frequent  examinations  extending 
over  a  period  of  4  months  proved  negative,  yet  the  carrier  subsequently 
infected  3  persons.  One  examination  of  the  urine  is  ordinarily  suffi- 
cient. 

The  use  of  hexamethylenamin  during  the  fever  diminishes  the  in- 
cidence of  bacilluria,  and  should  be  a  routine  practice. 

Finally,  every  case  of  t}"phoid  fever  should  be  painstakingly  traced 


TV  ri  I  oil)   FEVER  135 

to  its  source.  In  tliis  way,  carriers  and  other  foci  will  be  detected  aud 
much  further  harm  prevented. 

Summary — Personal  Prophylaxis. — The  prevention  of  typhoid  fever 
may  be  summed  up  in  the  word  cleanliness — j)hysieal  and  biological 
cleanliness.  By  this  is  meant  not  only  clean  food,  especially  water  and 
milk,  but  also  cleanliness  of  ])erson  and  environment.  Tyi)hoid  fever  has 
always  prevailed  where  cleanliness  is  neglected  and  has  diminished  where 
it  has  been  intelligently  observed.  It  is  true  that  typhoid  bacilli  do  not 
breed  in  the  rubbish  aud  dirt  of  back  yards  and  alleys,  or  in  unkempt 
city  lotS;,  but  these  conditions  in  a  community  may  be  taken  as  an  index 
of  the  general  cleanliness  of  its  inhabitants. 

The  eradication  of  typhoid  fever  is  easier  in  cities  than  in  country 
districts;  clean  cities  now  have  less  typhoid  fever  than  the  surrounding 
rural  regions.  Cities  can  well  afford  extensive  and  expensive  sanitary 
works  which  are  beyond  the  financial  possibilities  of  sparsely  settled  dis- 
tricts. If  a  clean  water  from  natural  sources  is  not  available,  then  large 
volumes  of  a  polluted  water  may  be  rendered  reasonably  safe  for  munici- 
pal use  by  slow^  sand  filtration  and  by  bleaching  powder.  Further,  cities 
can  afford  to  inspect  their  milk  supply  and  to  supervise  the  pasteurization 
of  all  that  is  not  safe.  These  two  measures  W'Ould> practically  eliminate 
typhoid  infection  coming  into  cities  in  its  food  supply — especially  if  in 
addition  to  this  a  supervision  is  maintained  over  oysters  and  shellfish, 
and  vegetables  partaken  in  their  raw  state.  Further,  cities  can  well  afford 
to  employ  skilled  and  experienced  health  officials  and  are  financially  able 
to  engage  the  services  of  experts.  On  the  other  hand,  each  farmhouse 
represents,  in  miniature,  all  the  problems  with  which  the  city  deals  by 
wholesale,  and  is  often  not  financially  able  to  meet  its  sanitary  require- 
ments. The  country  is  the  w'eakest  link  in  our  sanitary  chain.  The 
good  results  obtained  in  the  rural  region  of  Yakima,  Washington,  and  in 
several  counties  of  Maryland  by  Lumsden,  through  intelligent  and  in- 
tensive measures,  are  a  great  object  lesson  in  rural  sanitation. 

Cities  will  find  it  a  paying  proposition  to  suppress  flies,  rats,  and 
other  vermin,  wdiich  may  be  done  much  more  easily  than  under  rural  or 
suburban  conditions.  This  should  be  done  not  only  on  account  of  the 
suppression  of  typhoid  fever,  but  other  diseases  thus  conveyed.  The  city 
beautiful  must  also  be  the  city  clean, — clean  in  its  cellars,  garrets,  back 
yards,  empty  lots,  alleys,  and  stables. 

To  sum  up,  the  main  factors  in  the  spread  of  typhoid  fever  in  our 
large  cities  are:  (1)  water;  (2)  milk;  (3)  contact;  (4)  miscellaneous. 
In  a  cit}'  having  a  clean  water  su])ply  the  residual  typhoid  must  be 
attacked  along  two  definite  lines,  viz.,  improvement  of  the  milk  supply 
and  its  pasteurization,  and  a  warfare  against  the  disease  in  the  light  of 
an  infection  spread  from  man  to  man. 

The  health  officer  should  establish  a  laboratory  for  the  early  diagnosis 


136    DISEASES  SPEEAD  BY  THE  ALVINE  DISCHAEGES 

of  cases  and  for  the  discovery  of  carriers.  The  health  officer  should  at 
once  send  a  trained  agent  to  every  house  from  which  a  case  of  typhoid 
fever  is  reported.  The  visit  should  be  made  as  early  as  practicable  and 
with  the  object  of  seeing  that  the  stools  and  urine  are  properly  disin- 
fected, patients  isolated,  milk  bottles  scalded,  sick  rooms  screened,  house 
placarded,  visiting  discouraged,  and  other  necessary  measures  taken  to 
prevent  the  spread  of  the  infection.  Eacli  case  should  he  traced  so  as 
to  prevent  further  harm  from  the  same  source.  Convalescents  should  not 
be  released  until  the  absence  of  typhoid  bacilli  from  the  urine  and  stools 
has  been  demonstrated  by  at  least  four  successive  examinations.  Carriers 
need  not  be  indefinitely  quarantined,  but  should  be  prohibited  from  en- 
gaging in  any  employment  having  to  do  with  foods,  or  in  which  close 
personal  contact,  as  in  nursing,  is  required.  Carriers  should  be  in- 
structed concerning  the  danger  and  educated  to  wash  and  disinfect  their 
hands  thoroughly,  especially  after  a  visit  to  the  toilet. 

The  health  officer  -alone  cannot  eliminate  typhoid  fever  from  a  city. 
He  needs  the  help  of  the  community.  Much  can  be  done  through  educa- 
tion. A  stimulating  leader  may  accomplish  a  world  of  good  through 
voluntary  effort,  but  in  the  end  it  requires  comprehensive  laws  and  an 
energetic  enforcement  of  them,  without  fear  or  favor. 

The  personal  prevention  of  typhoid  fever  resolves  itself  into  boiling 
the  water,  if  suspicious;  partaking  only  of  milk  or  fresh  milk  products 
that  have  been  pasteurized,  and  otherwise  assuring  oneself  that  all  food 
has  been  thoroughly  cooked.  In  addition  to  this,  direct  and  indirect  con- 
tact with  persons  who  have  the  disease,  or  who  are  known  to  be  carriers, 
must  be  avoided.  Sanitary  habits  should  be  encouraged,  especially  the 
one  simple  precaution  of  washing  the  hands  after  defecation  and  before 
eating,  and  of  keeping  the  fingers  and  other  unnecessary  objects  away 
from  the  mouth  and  nose.  Finally  the  protection  afforded  through 
typhoid  inoculations  may  be  used. 


PARATYPHOID  FEVER 

Paratyphoid  fever  both  clinically  and  etiologically  is  a  first  cousin 
of  typhoid  fever.  The  two  diseases  are  indistinguishable  at  the  bedside. 
It  needs  the  aid  of  the  laboratory  to  differentiate  one  from  the  other. 
The  epidemiology  of  paratyphoid  fever  shows  marked  differences  from 
that  of  typhoid  fever. 

Paratyphoid  is  a  world-wide  infection;  outbreaks  occur,  but,  as  a 
rule,  are  of  limited  extent.  Paratyphoid  never  occurs  as  great  epidemic 
calamities,  such  as  have  been  frequently  observed  in  water-borne  or 
milk-borne  typhoid.  Paratyphoid  coexists  with  typhoid  in  endemic 
foci.     Thus,  in  Washington  somewhat  over  1  per  cent,  of  all  the  cases 


PARATYPHOID  FEVEP  137 

reported  as  typhoid  fever  Avero  sliowii,  upon  bacteriolo^^ical  examination, 
to  have  been  paratyplioid.  In  India  the  proportion  is  greater,  being  as 
high  as  15  jier  cent.  In  many  localities,  about  10  per  cent,  of  typhoid 
fever  is  in  reality  paratyphoid  fever. 

In  1896  Acharde  and  Bensaude  isolated  from  the  urine  of  a  case  of 
apparent  enteric  fever,  and  also  from  a  purulent  arthritis,  following  a 
similar  illness,  a  bacillus  Avhich  they  called  the  "paratyphoid  bacillus.'' 
In  1900-01  Schottmiiller  obtained  from  the  blood  of  patients  whose  symp- 
toms were  those  of  enteric  fever  two  bacilli  resembling  the  paratyphoid 
bacillus  of  Acharde  and  Bensaude.  These  two  organisms  were  later 
named  by  Brion  and  Kaiser  "paratyphosus  a"  and  "paratyphosus  ^" 
Paratyphoid  (3  is  much  more  common  and  widespread  than  paraty- 
phoid a. 

The  paratyphoid  bacillus  is  a  small  rod  with  rounded  ends  and 
peritrichal  flagellae  resembling  the  typhoid  bacillus.  It  stains  readily 
with  anilin  dyes,  is  decolorized  by  Gram's  method,  does  not  liquefy 
gelatin,  has  no  spore,  and  is  a  facultative  aerobe ;  it  clouds  bouillon  uni- 
formly, and  does  not  produce  indol.  Upon  Endo's  medium  the  para- 
typhoid colonies  are  pale,  moist,  translucent,  with  a  bluish  cast,  quite 
similar  to  typhoid  colonies. 

The  paratyphoid  bacillus  ferments  dextrose,  mannite  and  maltose 
with  the  production  of  gas — whereas  the  typhoid  bacillus  produces  no 
gas.  They  also  vary  greatly  in  pathogenicity  for  the  lower  animals.  Ty- 
phoid cultures,  as  a  rule,  are  not  very  pathogenic  for  the  lower  animals,^* 
whereas  guinea-pigs  and  mice  are  susceptible  to  paratyphoid  cultures; 
most  strains  will  kill  guinea-pigs  when  1/50  to  1/100  of  a  loop  is  in- 
jected into  the  peritoneal  cavity.  Rabbits  are  also  susceptible;  birds  are 
entirely  refractory;  cattle,  dogs,  cats,  hogs,  and  sheep,  show  a  high  de- 
gree of  resistance  to  paratyphoid  cultures. 

A  fundamental  point  of  difference  between  the  paratyphoid  and  the 
typhoid  organisms  is  that  each  has  specific  agglutinating  properties. 
This  difference  and  gas  formation  in  certain  sugars  are  the  most  im- 
portant distinguishing  features.  Care  must  be  taken,  in  using  agglu- 
tinins, in  differentiating  these  closely  allied  species,  to  guard  against 
confusion  through  group  agglutinins,  and  also  to  keep  the  pro-agglu- 
tinized  zone  in  mind. 

The  paratyphoid  bacillus  may  be  found  in  the  blood  and  internal 
organs,  also  in  the  feces;  seldom  in  the  urine.  It  produces  a  continued 
fever  in  man  closely  resembling  typhoid  fever.  As  a  rule,  paratyphoid 
is  milder  than  typhoid.  Lentz  ^^  gives  a  mortality  of  3.3  per  cent, 
against  typhoid,  which  is  about  9  per  cent. 

^*  Cultures  injected  into  animals  do  not  produce  fevers  clinically  similar  to 
typhoid  or  paratyphoid  fevers. 

"  Centralblatt.  f.  Bakt.,  Referate,  Bd.  XXXVIII. 


138     DISEASES  SPREAD  BY  THE  ALVINE  DISCHAEGES 

Paratyphoid  fever  may  be  complicated  with  hemorrhages  from  the 
bowels,  bronchitis,  and  pneumonic  jDrocesses,  just  as  in  typhoid  fever; 
relapses  are  rare.  It  is  not  definitely  known  how  much  of  an  immunity 
is  conferred  by  one  attack,  but  it  is  known  that  paratyphoid  fever  does 
not  protect  against  typhoid  fever  nor  does  typhoid  protect  against  para- 
typhoid. The  prophylactic  power  of  each  bacterial  vaccine  is  also 
specific;  that  is,  typhoid  vaccine  does  not  protect  against  paratyphoid 
fever,  and  vice  versa. 

Paratyphoid  outbreaks  have  resulted  from  infected  water,  milk,  and 
other  food.  The  outbreaks  are  usually  limited  in  number  and  extent. 
Contact  infection  occurs,  and  carriers  spread  the  disease.  Prevention  is 
a  counterpart  of  that  for  typhoid  fever. 

Paratyphoid  Fever  and  Food  Poisoning'. — B.  paratyplwsus  (5  is 
closely  related  to  the  bacillus  of  hog  cholera  {B.  suipestifer)  and  to 
Gaertner's  bacillus  {B.  enteritidis)  ;  in  fact,  these  three  bacilli  are  very 
close  kin.  In  the  German  literature,  B.  suipestifer  and  B.  paratyphosus 
(5  are  considered  to  be  identical.  Differences,  however,  have  been  clearly 
established  by  the  extended  use  of  cultural,  agglutination  and  absorp- 
tion tests,  especially  by  the  English  investigators  Bainbridge  and 
Savage,  and  by  the  American  bacteriologist  Weiss  and  also  Krum- 
wiede. 

Food  poisoning  is  commonly  due  to  the  Bacillus  enteritidis  of  Gaert- 
ner,  or  B.  suipestifer  (see  page  696).  Some  investigators  still  include 
B.  paratyphosus  (3^  and  these  cases  were  formerly  called  meat  poisoning. 
Conradi  and  Eommeler  believe  that  food  infection  may  be  caused  by  the 
paratyphoid  bacillus  and  think  that  under  these  circumstances  the  food 
usually  becomes  infected  from  human  carriers. 

In  most  outbreaks  of  food  infection,  the  cases  are  acute,  with  the 
ordinary  s}'mptoms  of  gastro-intestinal  irritation, — nausea,  vomiting, 
cramps  and  diarrhea, — but  a  few  protracted  cases  of  febrile  infection 
are  met  with. 

There  is  evidence  in  the  very  interesting  outbreak  recorded  by  Bain- 
bridge and  Duffield  (1911),  that  B.  paratyphosus  (3  can  cause  acute 
gastro-enteritis,  simulating  food  poisoning.  This  occurrence,  however, 
Avas  probably  not  due  to  a  common  food  supply  and  the  infection  is 
believed  to  have  come  from  a  carrier. 

Savage  insists  that  no  food  poisoning  outbreaks  have  been  shown  to 
be  due  to  B.  paratyphosus  (3,  but  that  all  are  due  to  B.  suipestifer 
or  B.  enteritidis,  with  possibly  a  few  closely  allied  forms.  Human 
carriers  of  B.  suipestifer  and  B.  enteritidis  are  rare.  There  is  still 
much  work  to  be  done  before  these  closely  addiel  organisms  are  finally 
classified. 

For  further  discussion  of  this  subject,  see  Food  Poisoning,  page 
692. 


CHOLKRA  139 

CHOLERA 

The  prevention  of  cholera  corresponds  to  the  prevention  of  typhoid 
fever.  In  the  case  of  cholera,  vigorous  measures  have  been  rewarded  with 
signal  success.  It  is  quite  possible  to  live  in  the  midst  of  a  raging  cholera 
epidemic  without  contracting  the  disease.  Within  recent  years  epidemics 
have  been  suppressed  and  the  spread  of  the  infection  limited. 

The  home  of  true  cholera  is  the  delta  of  the  Ganges,  hence  it  is  usually 
called  "Asiatic  cholera"  to  distinguish  it  from  Cholera  nostras  or  Cholera 
morbus.  During  the  sixteenth,  seventeenth,  and  eighteenth  centuries 
cholera  was  epidemic  at  various  times  in  India.  It  is  estimated  that 
4,000,000  died  of  cholera  in  India  from  1902  to  1911.  It  is  only  in  the 
nineteenth  century  that  cholera  has  spread  along  the  routes  of  trade  and 
travel  to  Europe  (first  in  1830)  ;  Africa,  and  America  in  1833.  There 
have  been  four  pandemics;  one  from  1817  to  1823,  another  182G  to  1837, 
a  third  1846  to  18G2,  and  a  fourth  from  1864  to  1875.  In  1832  it  entered 
the  United  States  by  way  of  Xew  York  and  Quebec  and  reached  as  far 
west  as  the  military  posts  of  the  upper  Mississippi.  The  disease  recurred 
in  1835  and  1836.  In  1848  it  entered  the  country  through  Xew  Orleans 
and  spread  widely  up  the  Mississippi  and  was  dragged  across  the  conti- 
nent by  the  searchers  for  gold  all  the  way  to  California  (1849).  It  again 
prevailed  widely  through  this  country  in  1854,  having  been  introduced 
by  immigrant  ships  into  Xew  York.  In  1866  and  1867  there  were  less 
extensive  epidemics.  In  1873  it  again  appeared  in  the  United  States,  but 
did  not  prevail  widely.  Since  then,  only  occasional  cases  at  seaports 
have  occurred.  In  1892  the  great  epidemic  of  Hamburg  occurred,  and 
the  disease  threatened  to  become  pandemic  in  Asia,  Africa,  and  Europe. 
Cases  were  brought  by  transatlantic  liners  to  Xew  York,  and  a  few 
cases  occurred  in  the  city,  but  its  spread  was  prevented  by  aggressive 
measures.  Cholera  has  prevailed  for  years  in  the  Philippines,  but  is  now 
under  control.  While  the  home  of  cholera  is  in  the  tropics,  there  is 
scarcely  a  country  in  the  world  that  has  not  been  visited  some  time  or 
other  by  the  ravages  of  this  fatal  disease. 

The  incubation  period  of  cholera  is  short,  frequently  1  or  2  days, 
rarely  over  5.  The  period  of  detention  in  quarantine  is  5  days.  One 
attack  produces  a  mild  grade  of  immunity  which  is  not  lasting.  The 
disease  is  peculiar  to  man. 

The  Cause  and  Contributing  Causes  of  Cholera. — The  Vibrio  cliolerae 

or  the  "comma  bacillus"  discovered  by  Koch  in  1883  is  the  undisputed 

cause  of  the  disease.^*^     The  conditions  of  infection,  however,  are  com- 

^' Choleraic  s\mptoms  may  be  induced  by  other  organisms,  or  by  certain 
poisons.  These  cases,  knowTi  as  cholera  nostras  or  cholera  morbus,  are  becoming 
increasingly  rare.  Winter  cholera  is  the  name  of  a  mild  diarrheal  disease  in 
this  country.  It  is  of  unknown  etiology,  but  has  nothing  to  do  with  true  cholera. 
Most  outbreaks  seem  to  be  water-borne. 


UO    DISEASES  SPREAD  BY  THE  ALVINE  DISCHARGES 

plex.  Kot  everyone  who  takes  the  specific  microorganism  by  the  mouth 
necessarily  gets  the  disease^  but  without  it  there  can  be  no  cholera.  Many 
cholera  vibrios  probably  die  in  the  acid  Juices  of  the  stomach.  There  is, 
therefore,  perhaps  less  danger  in  taking  small  amounts  of  infection  dur- 
ing active  digestion  than  upon  an  empty  stomach,  for  it  has  been  shown 
experimentally  that  cold  drinks  do  not  stay  long  in  an  empty  stomach, 
but  pass  quickly  through  the  pylorus.  After  the  cholera  vibrio  has 
passed  the  pylorus  and  reaches  the  alkaline  juices  of  the  intestines,  it 
may  find  ideal  conditions  for  growth  or  may  still  have  a  hard  struggle 
for  existence.  Here  symbiosis  or  antibiosis  must  play  a  dominant  role. 
It  is  well  known  in  all  cholera  epidemics  that  a  deranged  digestion  is 
an  important  predisposing  factor  to  the  disease.  An  attack  may  thus  be 
precipitated  in  healthy  carriers.  In  the  Hamburg  epidemic  a  marked 
access  of  cases  on  Monday  following  the  Sunday  indiscretions  was  noted. 
Raw  fruits,  crude  fibrous  vegetables,  and  fermentable  food,  'difficult  of 
digestion,  seem  to  favor  the  growth  and  multiplication  of  the  cholera 
vibrio  in  the  intestinal  tract.  In  the  light  of  this  view  such  food  may 
often  be  the  predisposing  factor  rather  than  the  medium  which  conveys 
the  infection.  Just  what  the  factors  are  that  favor  or  handicap  the 
growth  of  the  cholera  vibrio  in  the  intestinal  tract  are  undetermined. 
Susceptibility  to  the  infection  also  depends  partly  upon  antibodies. 

Pettenkofer  stoutly  maintained  that  the  "comma  bacillus"  was  only 
one  of  the  factors  in  the  etiology  of  the  disease.  He  placed  special  im- 
portance upon  the  condition  of  the  host  and  his  environment,  and  con- 
sidered at  least  three  fundamental  factors  in  his  X,  Y,  Z  theory:  X  is 
the  germ,  Y  the  host  or  soil,  Z  the  environment.  In  this  connection  the 
disease  may  aptly  be  compared  to  fermentation,  in  which  X  represents 
the  yeast,  Y  the  carbohydrate,  and  Z  the  temperature,  moisture,  reaction, 
and  other  essential  conditions  for  the  growth  and  activity  of  the  yeast. 
Pettenkofer  maintained  that  X  without  Y  and  Z  would  not  produce 
cholera,  that  is,  while  the  cholera  vibrio  was  pathogenic  in  India  or 
Hamburg  (1893),  where  Y  and  Z  were  favorable,  it  would  be  harmless 
in  Munich,  where  Y  and  Z  were  unfavorable.  To  prove  this  theory, 
he  and  his  assistant,  Emmerich,  drank  pure  cultures  of  cholera 
after  first  rendering  the  stomach  contents  alkaline.  Pettenkofer,  then 
an  old  man,  soon  developed  a  diarrhea;  Emmerich  had  a  choleraic  attack. 
Pettenkofer  did  not  regard  his  own  case  as  cholera,  and  insisted  that 
the  inconclusive  results  lent  confirmation  to  his  theory  of  the  im- 
portance of  contributing  factors  (Y  and  Z).  Metchnikoff  and  his 
pupils  drank  pure  cultures  of  vibrios  from  four  different  sources  and 
were  able  to  produce  true  Asiatic  cholera,  which  although  mild  had 
all  the  classical  symptomis  of  the  disease :  rice  water  stools,  subnormal 
temperature,  vomiting,  cramps,  suppression  of  urine,  and  vibrios  in  al- 
most pure  culture  in  the  stools.     Similar  convincing  experiments  have 


CHOLERA  141 

occurred  amoiif^  laboratory  workers,  who  have  acci<lentally  gotten  pure 
cultures  of  cholera  into  their  mouths.  On  the  other  hand,  a  number  of 
persons  who  imitated  Pettenkofer's  experiment  were  not  aifected. 

The  cholera  vibrio  is  an  aerobic,  liquefying,  actively  motile  spirillum. 
It  stains  best  with  carbol  fuchsin,  1  to  10.  It  grows  well  on  ordinary 
culture  media,  but  is  very  susceptible  to  acids  and  antiseptics.  It  is 
somewhat  frailer  than  the  average  spore-free  bacteria. 

Diagnosis. — The  diagnosis  of  cholera  depends  upon  isolation  and 
identification  of  the  cholera  vibrio  in  pure  culture.  This  has  become 
comparatively  simple,  but  great  care  must  be  taken  not  to  confuse  the 
true  vibrio  of  cholera  with  a  great  host  of  other  microorganisms  which 
closely  resemble  it. 

A  presumptive  diagnosis  of  cholera  may  be  made  by  finding  large 
numbers  of  comma-shaped  bacilli  on  direct  mic;roscopic  examination  of. 
stained  preparations,  or  in  hanging  drops  of  the  mucous  flakes  ordinarily 
found  in  cholera  stools.  This  test  is  only  presumptive,  the  final  criterion 
being  the  biological  reactions  of  the  microorganism  obtained  in  pure 
culture.  The  two  reactions  ivhicJi  are  specific  and  reliable  are  Pfeiffer's 
phenomenon  and  agglutination. 

Dependence  should  not  be  placed  upon  morphological  characters,  cul- 
tural peculiarities,  or  pathogenicity  upon  laboratory  animals,  for  these 
do  not  furnish  the  means  of  certainly  defining  the  cholera  vibrio.  For 
the  isolation  of  the  cholera  vibrio,  agar  is  preferable  to  gelatin,  formerly 
so  much  used.  The  suspected  material  should  be  planted  upon  the  sur- 
face of  ordinary  alkaline  agar  or  upon  Dieudonne's  medium,  using  one 
of  the  small  rice-like  flakes  or  an  equivalent  quantity  of  feces. 

Dieudonne's  medium  is  prepared  as  follows : 

Sol,  A. — Equal  parts  of  a  normal  solution  of  potassium  hydroxid  and 
defibrinated  ox-blood  are  mixed  and  sterilized  in  the  autoclave. 

Sol.  B. — Ordinary  nutrient  agar,  exactly  neutral  to  litmus. 

Seven  parts  of  B  are  mixed  with  3  parts  of  A  and  poured  into  Petri 
dishes.  The  plates  should  not  be  used  immediately  after  their  prepara- 
tion. Dieudonne  recommends  keeping  them  several  hours  in  the  incu- 
bator at  37°  C,  uncovered  and  face  down,  or  to  heat  them  for  5  minutes 
at  65°  C.  Equally  good  results  can  be  obtained  by  keeping  them  48 
hours  at  room  temperature.  The  surface  of  the  agar  should  be  slightly 
dry.  Once  in  condition,  the  plates  should  be  used  in  a  period  not  exceed- 
ing 5  or  6  days. 

Upon  this  medium  cholera  vibrios  grow  abundantly.  On  the  con- 
trary, the  organisms  which  most  often  accompany  them  on  plate  cul- 
tures, especially  B.  coli,  grow  either  very  poorly  or  not  at  all. 

When  it  is  suspected  that  the  cholera  vibrios  are  few  in  number,  they 
may  be  enriched  by  first  planting  in  Dunham's  solution.  Approximately 
1  c.  c.  of  fecal  matter  should  be  placed  in  50  c.  c.  of  the  peptone  solution. 


143    DISEASES  SPEEAD  BY  THE  ALVINE  DISCHARGES 

This  is  incubated  at  37°  C.^,  and  in  from  6  to  8  hours  a  loopful  is  taken 
from  the  surface  and  transferred  to  ordinary  agar  or  Dieudonne's 
medium.  ^''  Suspicious  colonies  are  fished  and  studied  further.  A  quick 
method  of  detecting  carriers  is  given  on  page  145. 

Kolle  and  Gotchlich  have  shown  from  a  large  number  of  observations 
that  with  strongly  agglutinative  serum,  the  power  of  which  reaches 
1-4,000,  the  agglutinative  power  for  common  vibrios,  not  cholera,  does 
not,  as  a  general  rule,  exceed  1-50  and  rarely  reaches  1-200 ;  agglutination 
in  dilutions  of  1-500  has  been  only  very  exceptionally  observed.  On  the 
contrary,  the  true  cholera  vibrios  agglutinate  in  dilutions  varying  from 
1-1,000  and  1-20,000  and  sometimes  even  higher.  Therefore,  with  a 
specific  agglutinating  serum  having  a  titer  of  1-4,000,  any  organism 
which  is  agglutinated  in  1-1,000  may  be  considered  true  cholera.  Organ- 
isms agglutinating  in  dilutions  of  1-500  should  be  regarded  as  doubt- 
ful. 

In  any  critical  case  Pfeiffer's  reaction  (see  page  576)  should  be  tried. 
This  is  specific.     See  also  page  145. 

Modes  of  Transmission. — Cholera  is  spread  by  man  from  place  to 
place.  It  follows  the  lines  of  trade  and  travel.  Seaports  are  invariably 
first  attacked.  The  epidemic  at  Hamburg  in  1892  was  brought  to  that 
port  by  immigrants  on  board  vessels  from  Eussia.  There  are  many  sim- 
ilar instances.  In  1849  many  a  gold  hunter  found  another  Eldorado 
than  the  one  he  was  searching  for,  as  cholera  was  dragged  across  the  con- 
tinent by  the  caravans  seeking  fortunes  in  California.  The  same  thing 
takes  place  in  the  Indian  pilgrimages  to  Mecca. 

The  cholera  vibrio  enters  the  digestive  tract  through  the  mouth.  It 
is  taken  in  food  and  drink.  Infected  water  is  a  frequent  medium  of 
transference,  and  probably  the  sole  vector  of  the  great  epidemic  out- 
bursts. Cholera,  however,  may  be  transferred  from  man  to  man  directly, 
also  indirectly  by  flies,  fingers,  food,  and  all  the  innumerable  channels 
from  the  anus  of  one  man  to  the  mouth  of  another  that  have  been 
described  in  the  case  of  typhoid. 

In  endemic  or  residual  cholera,  water-borne  infection  plays  a  minor 
role.  This  was  well  proved  in  the  sanitary  campaign  against  the  disease 
in  the  Philippine  Islands,  in  which  the  water  was  practically  ignored 
and  the  disease  conquered  in  the  light  of  a  contact  infection  com- 
municated rather  directly  from  man  to  man.  Convalescent  carriers 
and  healthy  passive  carriers  are  common  means  of  spreading  the  in- 
fection. 

The  cholera  vibrio  leaves  the  body  in  enormous  numbers  in  the 
dejecta,  also  sometimes  in  the  matter  vomited.  The  cholera  vibrio  is 
seldom  found  in  the  blood,  but  has  been  located  in  the  gall-bladder  and 

"  Some  New  Selective  Cholera  Media.  Goldberger,  Hyg.  Lah.  Bull.,  91, 
U.  S.  P.  H.  S. 


CHOLERA  143 

other  tissues.  Disinfection  in  tliis  disease  must.  tluTcfore,  be  concen- 
trated upon  the  discharge  from  the  bowels  and  mouth,  and  also  the 
urine  at  the  bedside. 

Water. — The  cholera  vibrio  nuiy  live  and  even  multiply  in  water. 
Koch  in  his  original  investigations  found  the  organism  in  the  foul  water 
of  a  tank  in  India  which  was  used  by  the  natives  for  drinking  purpo.scs. 
It  has  been  shown  by  experiment  that  the  cholera  vibrio  may  multiply  to 
some  extent  in  sterilized  river  water  or  well  water ;  and  that  it  preserve? 
its  vitality  in  such  water  for  several  weeks  or  even  months.  In  recent 
times  cholera  organisms  have  been  found  not  infrequently  in  the  water 
of  wells,  water  mains,  rivers,  harbors,  canals,  and  even  sea  water  (the 
IsTorth  Sea  near  the  mouth  of  the  Elbe),  which  have  become  contam- 
inated with  the  discharges  of  cholera  patients.  It  is  plain  from  the 
nature  of  the  case  that  infected  water  must  play  a  very  large  role  in 
spreading  this  infection. 

The  earliest  and  now  classic  instance  in  favor  of  the  water-borne 
theory  we  owe  to  Dr.  John  Snow.  This  is  the  classic  Broad  Street 
pump  outbreak  in  London  in  1854,  an  account  of  which  will  be  found 
on  page  llGl. 

The  best  example  of  water-borne  cholera  is  the  Hamburg  epidemic  of 
1892,  which  I  was  fortunate  enough  to  see  in  part.  In  this  case  no  link 
in  the  chain  of  evidence  is  missing.  Cholera  was  brought  to  Hamburg 
by  immigrants  from  Eussia.  The  water  of  the  Elbe  was  infected  with 
their  discharges.  The  Vibrio  cholerae  was  readily  isolated  from  the 
river  water  which  was  distributed  throughout  the  city  for  drinking  pur- 
poses without  purification.  The  sewers  of  Hamburg  emptied  into  the 
river  Elbe  near  the  water  intake,  which  produced  a  vicious  circle.  An 
account  of  the  epidemic  will  be  found  on  page  1165. 

Other  Modes  of  Transference. — The  fact  that  water-borne  infec- 
tion is  practically  the  only  cause  of  the  large  cholera  epidemics  must  not 
overshadow  the  importance  of  other  modes  of  transmission.  In  addition 
to  the  violent  outbreaks,  cholera  occurs  in  nests  or  smoulders  like  endemic 
typhoid.  It  is  difficult  to  trace  the  connection  between  cases  in  endemic 
areas.  Thus,  a  careful  study  of  the  cholera  situation  in  Manila  disclosed 
the  fact  that  isolated  cases  would  crop  up  at  widely  different  points  with- 
out any  evident  connection  between  them.  Cholera  carriers  were  sus- 
pected and  later  demonstrated.  At  irregular  intervals  of  several  years 
the  disease  Avould  gather  force,  and  cases  multiply,  until  it  assumed 
epidemic  proi)ortions,  entirely  independent,  it  is  believed,  of  the  water 
supply.  The  way  cholera  was  dragged  across  our  continent  by  the  "forty- 
niners,''  and  its  occurrence  among  the  ]\Iecca  pilgrims,  are  instances  of 
its  spread  largely  independent  of  infected  water. 

Contact  Infection. — Contact  infection  in  cholera  must  not  be 
underestimated.     Persons  frequently  become  infected  through  handling 


144     DISEASES  SPREAD  BY  THE  ALVINE  DISCHAEGES 

the  dejecta  cr  through  freshly  infected  fomites,  such  as  soiled  linen. 
Direct  transmission  from  person  to  person  was  formerly  seen  among 
physicians  and  nurses.  In  congested  quarters,  where  many  persons  live 
under  uncleanly  conditions,  contact  infection  plays  an  important  part. 
The  same  thing  may  be  seen  on  board  vessels,  in  which  case  the  disease 
may  be  confined  to  the  firemen,  stewards,  or  some  other  limited  group 
who  are  required  to  live  in  close  contact  with  each  other.  Epidemic  out- 
breal^s  due  to  contact  infection  have  been  recorded,  such  as  the  30  cases 
which  occurred  in  the  fall  of  1892  in  Boizenburg. 

Cholera  is  not  highly  "contagious,"  for  physicians,  nurses,  and  others 
in  close  contact  with  patients  need  not  become  infected  provided  intelli- 
gent measures  r.re  adopted.  On  the  other  hand,  there  is  great  danger  of 
the  spread  of  the  disease  through  devious  and  hidden  routes,  as  is  the 
case  with  typhoid  and  dysentery.  Washerwomen  and  those  who  are 
brought  in  very  close  contact  with  the  linen  of  cholera  patients  or  with 
their  stools  may  contract  the  disease.  Koch,  in  his  original  inves- 
tigations, found  that  the  "comma  bacillus"  may  multiply  rapidly  upon 
the  surface  of  moist  linen. 

Milk  may  be  contaminated,  but  is  probably  not  a  frequent  medium 
of  infection,  for  the  reason  that  its  acid  reaction  is  inimical  to  the  cholera 
vibrio.  Green  vegetables  and  fruit  that  have  been  washed  in  an  infected 
water  may  convey  the  disease.  The  bacilli  may  live  on  fresh  bread,  but- 
ter, and  meat  for  from  6  to  8  days,  if  not  too  acid. 

Flies,  etc. — It  has  been  shown  that  the  cholera  vibrios  may  live  in 
the  intestines  of  flies  for  at  least  3  days,  and  these  and  other  insects  may 
also  spread  the  infection  mechanically.  The  cholera  vibrio  is  a  frail 
organism  and  dies  rapidly  when  dried  or  exposed  to  light  and  other 
injurious  influences.  Infection  through  the  air  is,  therefore,  not  to  be 
dreaded.  Fomites,  such  as  bed  and  body  linen  or  other  objects,  including 
spoons,  dishes,  toys,  etc.,  contaminated  with  the  discharges,  can  be  re- 
garded as  possible  sources  of  infection.  There  is,  however,  a  special 
limitation  in  this  case,  owing  to  the  fact  that  this  organism  is  so  readily 
destroyed  by  desiccation  and  crowded  out  by  saprophytic  microorganisms. 
Thus,  as  a  rule,  only  fresh  dejecta  and  freshly  contaminated  objects  are 
liable  to  convey  the  infection. 

Bacillus  Carriers.^* — The  cholera  vibrios  are  passed  in  enormous 
numbers  in  the  feces  during  the  early  part  of  the  disease.  They  usually 
disappear  after  the  fourth  to  the  fourteenth  day,  but  may  remain  one 
or  two  months.  These  are  convalescent  carriers.  Chronic  carriers  are 
rare.     Healthy  or  passive  carriers  occur  and  are  an  important  and  in- 

''  The  recognition  of  the  carrier  principle  in  connection  with  the  dissemina- 
tion of  various  communicable  infections  was  first  established  by  Robert  Koch  in 
the  course  of  his  well-known  investigations  into  the  cholera  outbreak  which  oc- 
curred in  Germany  during  the  Avinter  of  1892-3.  {Zeitschr.  f.  Hyg.,  1893,  XV,  p. 
89.) 


CHOLERA  145 

sidious  means  of  spreading  the  infection;  they  may  also  develop  the 
disease. 

McLoughlin  (1908)  found  haciUus  carriers  numerous  in  epidemic 
centers  in  the  Philippine  Islands.  Thus  he  found  (5  to  7  per  cent,  of 
carriers  among  healthy  individuals  living  in  the  infected  neighhorhoods 
in  Manila.  On  the  other  hand,  carriers  were  exceedingly  rare  in  neigh- 
borhoods having  few  cases.  Cholera  carriers,  therefore,  play  a  similar 
role  to  typhoid  carriers  in  spreading  the  infection.  Carriers  are  the 
principal  factor  in  the  spread  of  endemic  cholera  and  they  keep  the  in- 
fection alive  in  the  Philippines,  on  Indian  pilgrimages,  and  in  other 
places  where  there  is  little  or  no  water-horne  infection. 

In  the  outbreak  of  cholera  in  Manila,  191-1,  carriers  were  the  most 
numerous  and  also  the  most  insidious  source  of  infection.^^ 

Detection  of  Carriers. — Specimens  are  best  obtained  by  adminis- 
tering a  saline  cathartic  or  by  using  a  rectal  tube  with  "eyes"  cut  into  it. 

Several  different  methods  for  the  detection  of  cholera  carriers  are 
applicable.  All  of  them  are  based  upon  the  facility  with  which  the 
vibrio  grows  upon  Dunham's  solution.  Particles  of  feces  are  planted  in 
this  medium  and  subsequently  examined  for  comma-shaped  micro- 
organisms. If  found,  the  diagnosis  is  presumptive.  Pure  cultures  should 
then  be  made  and  studied  for  agglutination.  Details  of  the  method  are 
the  same  as  described  on  page  141. 

The  routine  bacteriological  examination  of  immigrants  from  cholera- 
infected  ports,  as  practiced  at  the  Quarantine  Station  at  Xew  York,  in 
1912,  was  as  follows  :^° 

1.  Inoculation  of  feces  into  Dunham's  peptone  solution  (at  37°  C). 

2.  Subinoculation  at  the  end  of  six  hours  of  one  loop  of  the  surface 
growth  into  a  second  Dunham's  peptone  tube. 

3.  Examination  of  a  smear  taken  from  the  surface  grow^th  of  the 
second  Dunham's  peptone  tube,  after  incubation  6  to  9  hours  at  37°  C. 

Bendick  uses  a  modified  Dunham's  solution  containing  sodium  car- 
bonate, 1  gram;  saccharose,  5  grams;  and  phenolphthalein  solution,  5 
e.  c,  in  addition  to  the  usual  amount  of  water,  peptone  and  salt.  The 
cholera  vibrios  ferment  the  saccharose;  the  acid  produced  unites  with  the 
sodium  carbonate  and  the  medium  becomes  neutral,  hence  the  red  color 
of  the  phenolphthalein  disappears. 

Immunity  and  Prophylactic  Inoculations. — The  immunity  produced 
by  an  attack  of  the  disease  is  of  short  duration.  An  active  immunity 
may  readily  be  induced  in  susceptible  animals  against  cholera  vibrios. 
Attempts  to  immunize  man  with  cholera  vaccines  were  made  by  Ferran 
in  Spain  in  1884,  and  Haffkine  in  India  in  1895.  These  early  attempts 
did  not  produce  a  high  degree  of  immunity,  and  the  results  were  not 

^Philippine  Jour.  ffc.  Sec.  B..  Trop.  Med..  1915,  X,  p.  1. 

*>  Bendick:  Jour,  of  Am.  Pub.  Health  Assn.,  I,  No.  12,  906,  Dec,  1911. 


146     DISEASES  SPEEAD  BY  THE  ALVINE  DISCHARGES 

conclusive.  It  has  since  been  shown  by  Kolle,  Powell,  Simpson,  Wright 
and  others  that  prophylactic  vaccines  against  cholera  are  a  practical  and 
useful  method  of  protection.  Convincing  figures  are  not  readily  obtain- 
able, but  all  observers  are  assured  of  its  usefulness.  Cholera  vaccines, 
either  alone  or  mixed  with  typhoid  vaccines,  were  much  used  in  the  war 
to  protect  the  troops  serving  in  districts  where  the  disease  prevailed. 
Cholera  vaccines  have  been  much  used  in  Japan,  where  good  results  are 
reported.  Most  of  the  inconclusive  results  were  due  to  using  too  small 
a  dose  or  not  giving  a  sufficient  number  of  inoculations. 

Haffkine  used  live  cultures  attenuated  after  the  principles  of  Pasteur. 
He  first  injected  a  culture  weakened  by  prolonged  cultivation  in  artificial 
media  at  39°  C;  a  second  injection  was  given  of  a  culture  which  had 
been  rapidly  passed  through  animals.  He  subsequently  modified  his 
method  to  a  single  inoculation  of  a  virulent  culture  recently  recovered 
from  the  peritoneum  of  a  guinea-pig.  The  dose  for  an  adult'  is  0.5  c.  c. 
of  an  emulsion  of  an  .agar  slant  in  5  c.  c.  of  sterile  water,  injected  sub- 
cutaneously.  It  is  not  possible  to  produce  cholera  by  introducing  the 
spirilla  parenterally. 

Kolle  uses  a  more  practical  method,  standardized  so  that  one  c.  c.  of 
the  suspension  contains  2  milligrams  of  culture.  The  vibrios  are  grown 
on  agar  slants,  suspended  in  salt  solution  and  then  heated  to  58°  C.  for 
one  hour;  0.5  c.  c.  of  phenolis  added  as  a  preservative.  One  c.  c.  (2 
milligrams  of  culture)  is  given  subcutaneously,  3  or  4  times,  at  intervals 
of  5  to  7  days. 

The  immunity  produced  by  these  protective  inoculations  lasts  about 
a  year,  when  the  specific  antibodies  begin  to  diminish  in  the  blood  serum. 

There  seems  to  be  little  doubt  in  Japan  concerning  the  value  of  the 
protection  aiforded  by  the  inoculation  of  dead  cultures,  for  in  the  district 
of  Hiogo,  during  the  epidemic  of  1902,  77,907  persons  were  inoculated. 
Of  these  47,  or  0.06  per  cent.,  took  cholera,  and  20,  or  0.02  per  cent., 
died,  whereas,  among  825,287  persons  not  inoculated,  1,152,  or  0.13  per 
cent.,  took  the  disease,  and  863,  or  0.1  per  cent.,  died.  It  is  especially 
noteworthy  that  all  the  cases  among  the  inoculated  group  were  in  those 
who  received  an  injection  of  2  mg.  of  the  dead  culture.  Later  4 
mg.  were  used,  and  in  this  group  no  cases  occurred.  Good  results 
were  also  obtained  in  the  Russian  epidemic  of  1908-9,  and  in  the 
World  War. 

Protective  inoculations  as  a  prophylactic  measure  against  cholera  will 
never  be  popular  or  necessary  in  communities  with  sufficient  sanitation. 
It  is,  however,  of  value  in  camps,  armies  on  the  march,  for  physicians, 
nurses,  ward  tenders,  travelers,  and  others  especially  exposed. 

Quarantine. — Cholera  is  an  infection  which  fully  justifies  maritime 
quarantine  practice.  The  disease  may  be  blocked  by  a  careful  system  of 
inspection,  detention,  and  disinfection  at  the  seaport.    In  order  for  mar- 


CHOLEHA  147 

itime  quarantine  to  be  ell'ective  for  cholera,  it  must  have  the  assistance 
of  a  bacteriological  laboratory  to  diagnose  cases  and  recognize  carriers. 
A  bacteriological  examination  of  the  feces  of  all  persons  coming  from 
cholera-infected  places  has  entirely  supplanted  the  old-fashioned  period 
of  indiscriminate  detention  for  live  days. 

In  the  summer  of  191'^  the  quarantine  authorities  at  the  large  sea- 
ports on  our  Atlantic  littoral  examined  about  o4,U00  specimens  of  bowel 
discharges  from  passengers  and  crews  from  cholera-infected  ports.  At  the 
New  York  quarantine  the  cholera  vibrio  was  isolated  from  28  persons 
sick  with  the  disease,  and  27  healthy  persons  were  found  to  be  discharg- 
ing vibrios  in  their  feces.  These  carriers  could  not  have  been  discovered 
except  by  laboratory  examination.  Seven  cases  of  cholera  were  detected 
at  other  ports  by  the  same  methods.  There  can  be  no  doubt  that  the 
adoption  of  this  measure  kept  cholera  out  of  the  country. 

Similar  measures  used  at  the  port  of  departure  can  be  successfully 
applied.  Owing  to  the  fact  that  most  cholera  carriers  soon  purge  them- 
selves of  the  vibrios,  the  detention  in  quarantine  is  ordinarily  not  pro- 
longed. Three  or  more  negative  bacteriological  findings  at  intervals  of 
two  days  should  be  required  before  releasing  a  carrier  (see  page  503). 

Personal  prophylaxis  requires,  first  of  all,  scrupulous  cleanliness  on 
the  part  of  the  person  and  his  surroundings.  Those  who  handle  cholera 
patients,  their  dejecta,  or  infected  articles  must  carefully  disinfect  their 
hands  each  time,  and  should  under  no  circumstances  eat  or  drink  any- 
thing in  the  sick  room.  During  cholera  times  all  water  and  food  of  every 
description  should  be  boiled  or  thoroughly  cooked  just  before  it  is  par- 
taken. Great  care  must  be  exercised  that  the  water  or  food  does  not 
become  infected  after  it  has  been  boiled  or  cooked.  The  usual  measures 
should  be  taken  to  guard  against  flies  and  other  vermin.  With  strict 
attention  to  these  measures,  it  is  possible  to  avoid  the  infection.  In  addi- 
tion, however,  attention  to  general  hygiene  and  especially  to  the  char- 
acter of  the  food  and  regularity  of  meals  should  be  given.  Slight  attacks 
of  indigestion  and  diarrhea  should  receive  prompt  medical  attention. 
Those  exposed  should  protect  themselves  with  cholera  inoculations.  The 
disinfection  of  fecal  discharges  and  other  special  measures  are  the  same 
as  for  typhoid  fever. 

A  summary  of  the  preventive  measures  necessary  to  control  an  epi- 
demic of  cholera  are :  centralization  of  authority  in  one  person ;  estab- 
lishment of  a  system  of  securing  and  reporting  information;  organiza- 
tion of  the  personnel  for  the  sanitary  work ;  enactment  of  necessary  ordi- 
nances; house  to  house  inspection;  safe  disposal  of  feces  of  entire  popu- 
lation ;  provision  for  a  safe  water  supply ;  supervisory  control  of  food  and 
drink;  a  search  for,  and  control  of  carriers;  isolation  and  care  of  patients 
in  special  hospitals;  separate  hospitals  or  wards  for  suspects;  a  labora- 
tory; detention  camps  or  barracks  for  those  desiring  to  leave  the  infected 


148     DISEASES  SPREAD  BY  THE  ALVINE  DISCHARGES 

area ;  disinfection,  etc.    For  further  discussion  concerning  the  control  of 
epidemics,  see  page  495. 

DYSENTERY 

(Flux) 

Dysentery  is  a  form  of  intestinal  flux,  characterized  by  frequent 
passages  of  blood  and  mucus,  and  straining  at  stool.  Diarrheas  of  this 
type  may  be  due  to  several  causes,  and  for  the  purpose  of  prevention  we 
may  consider  all  dysenteries  under  three  heads:  (1)  Bacillary,  due  to 
B.  dysenteriae;  (2)  amebic,  due  to  Entame'ba  histolytica ;  and  (3)  symp- 
tomatic, due  to  a  variety  of  irritating  poisons. 

BACILLARY  DYSENTERY 

Bacillary  dysentery  is  a  specific  infection  caused  by  Bacillus  dyseiv- 
teriae,  of  which  there  are  a  number  of  strains.  It  is  usually  a  self-lim- 
ited disease,  running  an  acute  course  without  complications  or  sequelae. 
Bacillary  dysentery  occurs  in  all  countries  and  climes,  with  a  tendency 
to  summer  prevalence.  All  grades  of  severity  are  met  with,  and  the 
case  fatality  rate  varies  greatly,  often  running  as  high  as  30  per  cent. 
Bacillary  dysentery  increases  in  amount  and  severity  as  we  approach  the 
Equator,  but  severe  outbreaks  occur  in  temperate  and  even  in  Arctic  re- 
gions. It  affects  all  ages  and  is  one  of  the  chief  causes  of  summer  diar- 
rheas in  infants.  The  disease  occurs  as  great  epidemics,  in  local  out- 
breaks and  sporadically.  In  all  armies  up  to  recent  times  it  has  caused 
great  ravages.  Dysentery  bacilli  have  killed  many  more  soldiers  in  the 
world's  history  than  bullets.  In  the  Federal  Service  during  the  Civil 
War,  there  were  259,071  cases  of  acute  dysentery.  Practically  all  epi- 
demics of  dysentery  in  camps  and  institutions  are  bacillary.  Overcrowd- 
ing, lack  of  cleanliness,  and  other  unhygienic  conditions  favor  its  spread 
so  that  it  is  called  famine,  asylum,  jail,  ship,  or  camp  dysentery. 

B.  dysenteriae  is  a  gram-negative,  spore-free,  non-liquefying  bacillus 
belonging  to  the  typhoid-colon  group.  There  are  at  least  four  different 
groups  or  strains :  Shiga,  Flexner,  Strong,  and  Y.  The  Flexner  type 
is  most  frequently  found  in  the  United  States.  The  symptoms  and 
lesions  produced  by  the  different  strains  are  identical.  See  table,  page 
700.  A  strong  toxin  may  be  obtained  from  the  Shiga  strain  which  when 
injected  intravenously  into  rabbits  produces  a  fatal  toxemia  with  a 
faithful  reproduction  of  the  symptoms  and  lesions  of  bacillary  dysentery. 
Two  toxic  substances  have  been  demonstrated  by  Olitsky  and  Kligler  *^ 
in  this  toxin:   (1)   an  exotoxin,  which  acts  especially  upon  the  nerves 

^'Jour.  Exp.  Med.,  1920,  XXXI,  1,  p.  19. 


DYSENTERY  119 

and  is  therefore  called  a  neurotoxin;  (2)  another,  Avhich  is  probahly  an 
endotoxin,  acts  upon  the  intestinal  tract  and  is  therefore  called  an  entero- 
toxin. 

Resistance. — The  dysentery  bacillus  has  about  the  same  resistance  to 
germicides  and  other  unfavorable  conditions  as  the  general  class  of  spore- 
free  bacteria.  It  dies  in  about  8  to  10  days  when  dried.  It  may  live  for 
months  wlion  moist.  It  is  sensitive  to  acids.  Phenol,  0.5  per  cent.,  kills 
the  dysentery  bacillus  in  6  hours.  1  per  cent,  in  30  minutes,  3  per  cent,  in 
1  to  2  minutes.  Bichlorid  of  mercury,  1-1,000,  kills  it  at  once,  and 
direct  sunlight  in  about  one-half  an  hour.  I  have  found  certain  strains 
of  the  dysentery  bacilli  somewhat  more  resistant  to  heat  than  the  typhoid 
bacillus.  They  are  killed  with  certainty  at  58°  C.  for  one  hour,  or  at  60° 
C.  for  20  minutes.  The  dysentery  bacillus  resists  cold  and  may  live  for 
months  when  frozen. 

BaciU US-carrying  in  dysentery  occurs,  and  probably  plays  a  more 
important  part  in  spreading  the  disease  than  we  now  suspect.  As  a 
rule,  the  bacilli  soon  disappear  from  the  stools  in  the  light  cases,  but 
they  may  persist  from  2  to  6  weeks  after  clinical  recovery.  Shiga  has 
found  them  more  persistent  in.  some  instances.  Yon  Drigalski  reports 
an  outbreak  in  Germany  caused  by  a  returning  soldier.  Eecent  conval- 
escents may  spread  the  infection.  Permanent  or  chronic  carriers  have 
not  been  discovered.  In  1917,  the  feces  of  over  2,000  healthy  persons 
in  and  around  Boston  were  examined  in  my  laboratory  without  finding 
a  single  dysentery  carrier. 

Inmiunity. — The  susceptibility  to  dysentery  varies  greatly.  This  is 
doubtless  due  in  part  to  the  bacterial  flora  of  the  intestinal  tract  as  well 
as  the  conditions  of  the  intestinal  mucosa.  Svonbiosis  or  antibiosis  must 
play  a  very  important  role  either  in  permitting  or  hindering  the 
growth  of  the  dysentery  bacillus  in  the  intestinal  tract.  There  is  still  a 
question  whether  a  true  immunity  is  acquired  by  one  attack  of  bacillary 
dysentery.  This  seems  probable,  although  it  is  not  unusual  for  a  person 
to  have  two  or  more  attacks  of  dysentery  in  one  season.  Kolle  looks  upon 
this  as  an  exacerbation  of  a  chronic  type  brought  on  by  errors  of  diet, 
exposure,  etc.  The  experiments  on  animals  indicate  that  dysentery  prob- 
ably belongs  to  that  group  of  diseases  which  leave  a  certain  amount  of 
protection  after  one  attack.  A  definite  and  high  grade  of  immunity 
can  be  produced  experimentally  in  several  of  the  lower  animals.  Upon 
this  question,  however,  we  need  light.  Horses  may  be  immunized  to  a 
high  degree,  and  their  sera  contain  a  certain  amount  of  antitoxin  and 
other  antibodies.  This  serum  has  been  used  in  treatment,  but  has  no 
particular  value  as  a  preventive.  There  is  no  immunity  in  amebic 
dysentery. 

The  methods  of  spread  and  prevention  of  dysentery  are  an  exact 
counterpart  of  those  of  typhoid  fever:  food,  fingers,  flies,  contacts  and 


150     DISEASES  SPEEAD  BY  THE  ALVI^E  DISCHARGES 

carriers  play  a  role.  Milk-borne  and  water-borne  outbreaks  have  been 
traced. 

Bacillary  dysentery  is  a  common  disease  in  infants,  and  it  would  be 
a  wise  precaution  to  consider  all  cases  of  infantile  diarrhea  as  infectious 
and  to  take  precautions  accordingly.  The  protection  of  babies  against 
dysentery  requires  biologic  cleanliness,  sanitary  isolation,  and  a  cease- 
less and  intelligent  technique.  Dysentery  is  one  of  the  greatest  single 
factors  in  high  infant  mortality  (page  1275). 

Dysentery  vaccines  have  definite  protective  value,  and  were  used 
among  certain  troops  during  the  World  War.  Convincing  figures  are 
difficult  to  obtain,  but  the  protective  value  seems  obvious. 

AMEBIC  DYSENTERY 

Amebic  dysentery  (amebiasis,  tropical  dysentery)  is  caused  by 
the  Entameba  histolytica,  and  is  characterized  by  a  colitis  with  tendency 
to  chronicity,  and  a  special  liability  to  the  formation  of  abscesses  of 
the  liver  (amebic  hepatitis).  Ipecac  and  its  alkaloid  emetin  have 
curative  virtues.  Amebic  dysentery  often  starts  insidiously  and  shows 
a  tendency  to  become  chronic,  with  exacerbations  and  relapses;  acute 
attacks  occur.  The  parasite  is  taken  in  by  the  mouth  and 'passed  by 
the  bowels.     There  is  no  immunity. 

Amebic  dysentery  is  more  severe  and  more  frequent  in  the  tropics, 
and  in  subtropical  climates,  but  cases  are  surprisingly  widespread 
through  the  temperate  zones  and  even  in  arctic  regions.  The  classical 
report  of  Losch,*^  1875,  recorded  the  case  of  a  patient  with  amebic 
dysentery  in  St.  Petersburg,  Eussia.  Cases  have  been  also  reported  in 
Alaska.  *^ 

Amebic  dysentery  occurs  mainly  in  endemic  form,  rarely  in  epidemic 
proportions.  This  is  perhaps  due  to  the  fact  that  the  amebas  are  trans- 
ferred almost  always  by  rather  direct  and  intimate  contact.  Food  in- 
fection may  occur,  but  is  not  the  cause  of  explosive  outbreaks,  such  as 
we  see  in  typhoid  fever  and  bacillary  dysentery.  Milk  and  water-borne 
outbreaks  of  amebiasis  do  not  occur  as  in  the  case  of  bacillary 
dysentery, 

Entameba  histolytica  may  be  found,  sometimes  in  great  numbers, 
in  the  discharges  from  the  bowels  and  in  the  pus  from  liver  abscesses. 
There  are  two  chief  amebas  in  human  feces — the  pathogenic  variety 
(Entameba  histolytica)  and  a  harmless  form  (Entameba  coli).  The 
pathogenic  form,  Entameba  histolytica,  is  distinguished  from  Entameba 

*'  Massenhafte  Entwickelung  von  Amohen  im  Dickdarm,  Virchows  Arch,  f. 
path.  Anat.,  1875,  LXV,  196. 

^' Axtell,  W.  H. :  "Amoebic  Dysentery  Contracted  in  the  Arctics  of  Alaska: 
Report  of  a  Case."     Northwest.  Med.,  1911,  K  S.,  Ill,  51. 


DYSENTERY  151 

coli  l)y  tlie  fact  that  tlu'  patliogi'iiic  form  usiiallv  lias  not  more  than 
four  iiiulei  in  the  encysted  stages,  wlici-cas  I'ltthuiirba  coli  shows  tyiii- 
cally  eight  nuclei;  for  the  positive  (lilVerentiation  hetweeu  these  two 
species  it  is  important  to  distinguish  the  encysted  forms.  ^I'his  differ- 
ence is  absolute.  The  following  are  relative:  The  ])athogenic  forms 
are  (1)  larger  size,  (2)  gi'eenish  color,  (3)  distinct  hyaliii,  with 
refractile  ectoplasm,  (4)  have  a  faint  nucleus,  (5)  many  vacuoles  and 
red  blood  cells,  (f!)  marked  motility,  with  pseudojiodia  of  clear  ecto- 
plasm. 

Eniameha  hisloJytica  is  an  obligate  parasite.  It  has  a  comparatively 
simple  life  cycle,  with  no  free  living  stage.  The  motile  amebae  are 
very  frail,  but  the  encysted  form  which  appears  later  in  the  disease 
and  in  carriers  is  more  hardy.  The  encysted  form  is  infective  and 
dangerous.  It  is  specific  for  man.  Kittens  may  be  infected  by  inject- 
ing the  infectious  material  directly  into  the  cecum.*^  None  of  the 
parasitic  amebae  have  yet  been  successfully  cultivated  upon  artificial 
media. 

Emetin,  one  of  the  alkaloid^  of  ipecac,  is  quite  as  specific  for  amebic 
dysentery  as  quinin  is  for  malaria.  Large  doses  of  ipecac  have  been 
used  for  many  years  in  the  treatment  of  dysentery,  particularly  by 
English  practitioners  in  India.  The  difficulty  has  been  in  inducing 
patients  to  retain  a  sufficient  amount  of  the  drug  by  the  mouth.  Pelle- 
tier,  in  1878,  described  an  alkaloid  in  ipecacuanha  which  he  called 
"emetin.''  Eogers  in  1907  demonstrated  that  this  alkaloid  would  rapidly 
cure  an  amebic  hepatitis  in  the  presuppurative  stage,  and  thus  prevent 
the  formation  of  liver  abscess.  Rogers  first  used  emetin  subcutaneously 
in  June,  1912.  It  is  now  clear  that  emetin,  when  so  administered, 
promptly  causes  a  disappearance  of  the  motile  forms  of  the  ameba  from 
the  feces,  but  has  no  effect  whatever  upon  the  encysted  forms;  it 
promptly  relieves  the  symptoms,  but  does  not  cure  or  prevent  ameba 
carriers;  it  does  not  prevent  relapses,  but  cures  them  when  they  occur. 
Emetin  hydrochlorid  is  given  intramuscularly  in  doses  of  about  %  grain 
every  3  hours  for  3  to  6  days;  repeated  if  necessary.  Emetin-bismuth 
iodid  and  also  Chapparo  amargoso  are  useful. 

The  prevention  of  amebic  dysentery  consists  in  a  search  for  and 
control  of  carriers,  also  mild,  latent  and  chronic  cases.  These  should  be 
treated  with  injections  into  the  colon  of  solutions  of  quinin,  kerosene 
and  other  amebicides,  Emetin  does  not  kill  the  encysted  stage,  and 
hence  will  not  cure  carriers. 

Contrast  between  Bacillary  and  Amebic  Dysentery. — There  are 
fundamental  distinctions  between  these  two  diseases,  which  are  sum- 
marized in  the  following  parallel  columns : 

**  Sellards  and  Baetjer,  Am.  Joum.  Trop.  Dis.  and  Prev.  Med.,  11,  4,  October, 
1914,  p.  231. 


153     DISEASES  SPREAD  BY  THE  ALVIN^E  DISCHAEGES 

BACILLAEY   DYSENTERY  I  AMEBIC   DYSENTERY 


Cause — Bacillus  dysenteriae. 


An  acute,  febrile,  self-limiting  disease 
with  severe  toxemia.  (Sometimes 
very  mild.) 


Lesions  are  diffuse  in  the  large  intes- 
tines, and  sometimes  occur  in  the 
small  intestines.  Varies  greatly  in 
severity. 


Few  sequelae. 


Incubation — 2  to  7  days. 


Defiiaite  immunity. 


Chief  cause  of  infantile  "diarrheas." 


Vaccines  are  protective. 

Temporary  active  carriers  play  a  rOle, 
but  probably  are  not  the  chief  agent 
in  spread.     Chronic  carriers  are  rare. 

Epidemics  frequent  and  often  wide- 
spread. Frequent  outbreaks  in  in- 
stitutions. The  disease  is  called  jail, 
asylum,  camp,  and  ship  dysentery. 

Most  prevalent  and  most  severe  in 
tropical  and  subtropical  countries. 
Widespread  in  temperate  climes. 

Mode  of  spread — like  typhoid;  water, 
milk,  food,  flies,  fingers,  contacts, 
carriers,  etc. 


No  specific  cure. 


Cause — Entameia  histolytica. 

An  insidious  and  chronic  infection, 
often  afebrile,  and  little  or  no  signs 
of  toxemia.  (Sometimes  acute  with 
fever. ) 


Lesions  localized  in  large  bowels,  never 
in  the  small  intestines.  Ulcers  un- 
dermined. 


Liver  abscess  common  sequela. 

Prolonged  and  variable.  . 

Xo  im.munity. 

Uncommon   in  children  in  the  temper- 
ate zone. 

Xo  specific  prophylactic  is  known. 

Chronic    carriers     frequent    and    play 
chief  role  in  spreading  infection. 


An  endemic  disease;  does  not  occur  in 
epidemic  outbreaks. 


Same  geographic  distribution;  less 
common  in  temperate  and  cold 
climes. 


Spread  by  intimate  personal  contact. 
Water,  milk,  and  food  outbreaks  not 
known. 


Emetin  cures  symptoms. 


Dysentery  should  be  included  in  the  notifiable  diseases  and  laboratory 
aid  furnished  by  Boards  of  Health  to  assist  diagnosis.  Cases  should 
be  isolated  in  the  same  sense  that  cases  of  typhoid  are  isolated,  and  disin- 
fection practiced  at  the  bedside.  Outbreaks  in  institutions  should  always 
be  investigated  and  vigorous  measures  taken  to  check  further  spread  and 
to  prevent  recurrences.  In  all  respects  the  prevention  of  dysentery  is  a 
close  parallel  to  that  of  typhoid. 


HOOKWORM  DISEASE  153 

HOOKWORM  DISEASE 

(  Uncinariusis  or  A  nci/lusloinlasv<) 

Theorctioally  the  prevention  of  hookworm  disease  is  comparatively 
simple,  for  here  we  have  an  infection  of  wliich  we  know  the  parasite  and 
its  life  liistory.  its  mode  of  exit  and  entrance  into  the  l)ody,  and  we 
possess  a  satisfactory  cure  for  the  disease  within  reach  of  all.  Practi- 
cally, however,  we  have  ignorance,  apathy,  poverty,  and  uncleanliness  to 
deal  with  hefore  satisfactory  prevention,  niudi  less  eradication,  can  be 
achieved.  It  is  no-w  plain  that  hookworm  disease  presents  a  sanitary 
problem  of  first  magnitude,  not  alone  in  our  southland,  but  in  practically 
all  tropical  and  subtropical  countries.  Further,  there  is  a  large  economic 
and  industrial  aspect  to  this  question  in  medical  biolog}\ 

Distribution. — Hookworm  disease  encircles  the  globe  in  the  tropical 
and  subtropical  climes;  it  diminishes  toward  the  temperate  regions.  It 
is  not  endemic  in  the  colder  latitudes,  except  in  mines,  especially  those 
of  Wales,  Germany,  Xetherlands.  Belgium,  France,  and  Spain.  The 
infection  belts  the  earth  in  a  zone  about  (i6°  wide,  extending  from  par- 
allel 3G  north  to  parallel  30  south  latitude.  The  amount  of  infection  is 
great  in  American  Samoa,  where  it  is  found  in  70  per  cent,  of  the  pop- 
ulation; in  the  southern  two-thirds  of  China,  in  75  per  cent,  of  the  pop- 
ulation; in  India  from  60  to  80  per  cent,  of  the  300,000,000  population 
have  the  worms ;  in  Ceylon,  90  per  cent,  in  many  parts ;  in  Natal,  50  per 
cent,  of  the  coolies  on  sugar  and  tea  estates;  in  Egypt,  50  per  cent,  of 
the  laboring  class;  in  Dutch  Guiana,  90  per  cent,  in  many  parts;  in 
British  Guiana,  50  per  cent,  of  all;  in  Colombia,  90  per  cent,  of  those 
living  between  sea-level  and  3,000  feet,  which  includes  most  of  the  pop- 
ulation ;  in  190-i  the  Porto  Eican  Anemia  Commission  found  that  90  per 
cent,  of  the  rural  population  of  that  island  -were  infested.  Stiles  esti- 
mates that  in  this  country  2,000,000  individuals  have  the  parasites  from 
the  Potomac  to  the  Mississippi,  along  the  Atlantic  littoral  and  the  Gulf 
states.  In  some  German  mines  from  30  to  80  per  cent,  of  the  miners 
have  been  found  to  be  infested.  Gunn  ^^  has  shown  that  from  50  to  SO 
per  cent,  of  those  working  in  the  California  mines  harbored  hookworms 
in  1911.  It  is  probable  that  all  the  older  mines  employing  foreign 
laborers  sooner  or  later  become  endemic  foci. 

In  1879  an  outbreak  of  hookworm  disease  occurred  among  the  labor- 
ers in  St.  Gothard's  tunnel  and  was  called  miner's  anemia.  This  aroused 
the  interest  of  the  scientific  world.  The  polluted  soil  of  the  tunnel  was 
found  to  be  impregnated  with  the  eggs  and  larvae.  Interest  in  the  dis- 
ease in  this  country  was  aroused  through  the  work  and  enthusiasm  of 
Stiles. 

*'Jour.  A.  M.  A.,  Vol.  LVI,  No.  4,  Jan.  28,  1011,  p.  2-59. 


154     DISEASES  SPEEAD  BY  THE  ALVINE  DISCHAEGES 

Species  of  Hookworm. — Many  mammalian  animals  have  hookworms, 
but  in  general  each  host  species  has  a  diiferent  kind  of  hookworm;  that 
is,  the  hookworms  of  the  dog,  sheep,  horse,  the  seal,  etc.,  differ  from  each 
other,  and  are  specific.  The  common  hookworm  of  the  dog  in  this 
country  will  not  infest  man;  the  hookworms  of  man  do  not  as  a  rule 
develop  to  maturity  in  the  lower  animals. 

Three  species  ^'^  of  hookworm  are  found  in  man — the  old  world  form 
( Ancylosto7na  duodenale)  and  the  Ceylon  hookworm  ( Ancylosioma 
ceylanicum)  ;  and  the  new  world  form  (Necaior  americanus) .  The  dis- 
tinction between  these  worms  has  a  zoological  rather  than  a  practical 
bearing,  for  all  three  produce  the  same  symptoms,  require  the  same 
treatment^  have  the  same  life  history,  and  call  for  the  same  preventive 
measures. 

The  chief  differences  between  the  two  genera  of  hookworms  of  man 
consist  in  the  fact  that  Ancylostoma  has  one  pair  of  ventral' hooks,  two 
conical  dorsal  teeth,  and  the  posterior  ray  of  the  caudal  bursa  divides 
two-thirds  its  way  from  the  base,  and  each  division  has  three  tips  (tri- 
partite), while  Necator  has  ventral  lips,  a  dorsal  median  tooth,  one  pair 
of  dorsal  and  one  pair  of  ventral  lancets  deep  in  the  buccal  capsule,  and 
the  posterior  ray  of  the  caudal  bursa  divides  at  its  base  and  each  division 
has  two  tips   (bipartite). 

According  to  Stiles,  the  vast  majority  of  cases  of  hookworm  disease 
in  man  in  the  United  States  are  due  to  the  new  world  form  (Necator 
ameriainus). 

Modes  of  Transmission. — The  usual  mode  of  transmission,  per- 
haps in  90  per  cent,  or  more  of  the  cases,  is  through  the  skin.  The 
embryos  may  also  be  taken  by  the  mouth  in  drinking  water  or  solid  food, 
or  from  contaminated  objects,  such  as  dirty  fingers.  It  has  been  shown 
by  experiment  that  animals  can  be  infected  by  drinking  water  containing 
the  embryos.  While  this  source  of  infection  plays  a  minor  role,  it  is  not 
to  be  disregarded. 

The  infection  leaves  the  body  exclusively  in  the  feces,  which  contain 
the  eggs  of  the  parasite. 

The  Parasite. — For  a  correct  understanding  of  the  prevention  of 
hookworm  disease  it  is  necessary  to  have  a  knowledge  of  the  essential 
features  of  the  life  history  of  the  parasite. 

Hookworms  are  round  worms  (nematodes)  belonging  to  the  supra- 
family  Sirongyloides.  The  adult  worm  is  about  one-half  to  three- 
quarters  of  an  inch  long,  and  about  the  diameter  of  a  wire  hairpin. 

The  adult  hookworm  lives  in  the  intestinal  tract,  usually  in  the 
small  intestine.  It  attaches  itself  to  the  intestinal  wall,  wounds  the 
mucosa,  sucks  blood,  eats  the  epithelium,  and  probably  produces  a  toxic 
substance  which  injures  the  host. 

^°  Two  genera — Ancylostoma  and  Necator. 


HOOKWORAf  DISEASE 


155 


(  ) 


Fig.  14.  —  IIook- 

WOKMS,  XaITTKAL 
SiZK. 


The  female  worm  lays  a  jirudigiuus  juiiuber  ul'  eggs  in  a  uever-eiiding 
stream,  which  pass  from  the  host  in  the  feces.  The  emhryo  does  not 
mature  within  the  egg  except  in  the  presence  of 
oxygen.  Hookworm  embryos,  therefore,  do  not 
imdergo  full  development  until  the  eggs  are  dis- 
charged into  the  outer  world.  On  the  other  hand, 
tStrongyloides  siercoralis,  the  parasite  of  Cochin- 
China  diarrhea,  develop  embryos  which  escape  from 
the  shell  and  are  passed  in  the  stools.  The  hookworm  embryos  become 
mature  within  the  egg  in  G  to  8  hours  in  the  presence  of  favorable  con- 
ditions of  moisture,  warmth,  and  oxygen.  It  is,  therefore,  necessary  to 
examine  the  fresh  stools  in  order  that  this  dif- 
ference between  the  two  infections  may  be  of 
value  in  differential  diagnosis. 

Under  favorable  conditions  the  hookworm 
embryo  escapes  from  the  Qgg  and  becomes  a  larva 
in  about  24  hours.  This  free-living  embryo 
exists  and  moves  in  moist  soil  and  feeds  npon  the 
organic  matter  found  there.  In  the  course  of 
two  days  or  more  it  sheds  its  skin  (undergoes 
ecdysis)  and  thus  passes  to  the  first  molt.  The 
resulting  larva  continues  as  a  free-living  parasite, 
and  in  about  a  week  again  sheds  its  skin,  but 
now  continues  to  live  encysted  inside  this  dis- 
carded skin.  This  is  the  second  ecdysis  and  this 
encysted  larva  no  longer  takes  food.  This  stage 
in  the  life  history  of  the  parasite  is  of  special 
importance  for  the  reason  that  it  is  capable  of 
piercing  the  skin;  that  is,  it  is  the  infecting 
stage.  In  this  condition  the  parasite  may  con- 
tinue its  free  living  existence  for  5  to  12  months, 
perhaps  longer.  The  larva  has  a  slow  motion 
and  under  favorable  conditions  probably  travels 
a  number  of  yards,  increasing  the  radius  of  soil 
pollution. 

The  hookworm   larva  passes  in   all  through 
four  ecdyses  or  molts.     Two  of  them  occur  dur- 
ing its  free-living  stage  and  two  of  them  during 
its  residence  in  the  host.     With  each  ecdysis  the 
larva  approaches  more  nearly  the  appearance  and 
structure  of  the  adult  worm. 
The  larva  pierces  the  skin  and  passes  by  a  circuitous  route  to  the 
intestinal  tract.     The  parasite  may  enter  the  skin  at  any  place,  but  it 
usually  goes  through  the  soft  and  thin  skin  between  the  toes.     In  its 


Fig. 


1 5 . — Hookworm 
Embryo. 


15G     DISEASES  SPEEAD  BY  THE  ALVINE  DISCHARGES 

passage  through  the  skin  the  larva  produces  an  inflammatory  reaction 
(ground-itch)  which  results  partly  from  the  irritating  action  of  the 
presence  of  the  foreign  body,  but  mainly  from  the  bacteria  carried  along 
with  the  larva.  These  primary  lesions  may  consist  of  a  few  itching 
papules  or  pustules  to  a  severe  dermatitis.  Of  4,741  patients  questioned 
by  Ashford,  King,  and  Guiterrez  in  Porto  Eico,  4,664,  or  about  98  per 
cent.,  gave  a  history  of  ground-itch,  which  is  now  recognized  as  the  first 
stage  of  the  disease. 

The  fact  that  the  infection  with  hookworm  disease  is  usually  con- 
tracted through  the  skin  was  discovered  by  Looss  in  Cairo,  Egypt.  He 
also  unraveled  the  course  of  the  parasite  from  the  skin  to  the  intestine. 
This  brilliant  discovery,  which  is  one  of  the  romances  of  medical  biology, 
is  the  foundation  upon  which  prevention  against  the  infection  depends. 
In  1895  Looss  accidentally  spilled  a  drop  of  water  containing  many 
encysted  larvae  upon  his  hand,  and  noted  that  they  disappeared,  leaving 
their  delicate  sheaths  behind  them.  Seventy-one  days  subsequently  he 
developed  intestinal  uncinariasis.  The  experiment  was  then  repeated 
upon  a  volunteer,  and  hookworm  eggs  appeared  in  his  stools  in  74  days. 
Claude  Smith  found  eggs  in  the  feces  6%  weeks  and  7  weeks  after  experi- 
mental skin  infection  on  two  persons  with  the  American  parasite  (Neca- 
tor  americanus) . 

The  wanderings  of  the  parasite  from  the  skin  to  the  intestine  were 
worked  out  by  Looss  partly  by  placing  larvae  upon  an  amputated  leg  and 
also  by  studying  the  question  upon  puppies.  The  hookworm  larva 
usually  pierces  the  skin  through  a  hair  follicle,  enters  the  subcutaneous 
tissue,  and  then  finds  its  way  through  the  lymphatics  to  the  neighboring 
lymph  nodes.  The  larvae  are  able  to  squirm  through  the  lymph  nodes, 
pass  to  the  thoracic  duct,  and  thence  to  the  vena  cava  and  the  right 
heart.  From  the  right  heart  they  are  carried  in  the  blood  stream  to  the 
lungs.  The  larvae  are  too  large  to  pass  the  capillaries  of  the  lungs. 
They  pierce  the  capillary  walls  and  appear  in  the  alveoli  and  are  now,  to 
all  intents  and  purposes,  again  in  the  outer  world.  They  pass  up  the 
bronchi  and  trachea  to  the  throat,  whence  they  are  swallowed,  and  finally 
lodge  in  the  small  intestines.  During  their  travel  through  the  body  they 
pass  through  two  ecdj^ses. 

The  adult  worm  attaches  itself  to  the  mucous  membrane  by  means  of 
the  powerful  buccal  lancet.  The  epithelium  is  drawn  into  the  buccal 
cavity  as  though  by  a  powerful  suction.  The  worms  are  usually  found  in 
the  small  intestine,  especially  in  the  jejunum,  less  often  in  the  duo- 
denum, and  rarely  in  the  ileum  and  lower  reaches  of  the  intestinal  tract; 
they  are  occasionally  met  with  in  the  stomach. 

The  parasites  imbibe  large  amounts  of  blood,  some  of  which  passes 
through  the  worm  unaltered.  The  wound  continues  to  bleed  after  the 
worm  releases  its  hold,  owing  perhaps  to  a  hemolytic  substance  in  the 


HOOKWORM  DISEASE  157 

luoulh  parts  of  the  parasite.  The  worm  does  not  remain  fastened  to  one 
jilace  indefinitely,  but  releases  its  hold  and  attaches  itself  anew.  This 
produces  numerous  minute  wounds,  favorinji^  secondary  infections.  The 
hookworm  probably  produces  a  poison  which  is  absorbed  and  which  ac- 
counts, in  part,  for  the  anemia  and  other  symptoms  of  the  disease.  The 
severity  of  tiie  symptoms  ])r()bal)ly  bears  a  definite  relation  to  the  number 
of  worms.  A  few  hookworms  rarely  ])roducc  clinical  evidence  of  their 
presence.  The  number  varies  greatly  in  individual  cases;  from  one  or 
two  to  thousands.  Sandwith  counted  250  worms  and  575  bites  in  one 
case;  2,000  worms  are  not  an  uncommon  number.  The  Porto  Rican 
Anemia  Commission  counted  as  many  as  4. GOO  passed  by  one  individual. 

Immunity. — There  is  no  acquired  immunity  to  this  disease.  There 
is,  however,  a  racial  resistance  to  the  effects  of  the  infection,  as  shown 
by  the  negroes  and  the  Filipinos,  who  are  often  infested  but  have  com- 
paratively slight  symptoms.  Stiles  found  that  in  this  country  the  negro 
is  a  reservoir  for  hookworm  disease  in  that  while  he  is  frequently  in- 
fected he  is  but  slightly  affected  when  compared  Avith  white  patients. 
Perhaps  the  negro  has  had  the  disease  so  many  generations  in  Africa 
that  he  has  become  relatively  immune.  It  is  conjectured  that  the  infec- 
tion was  brought  to  America  through  the  negro  slave  trade.  Hookworm 
disease  lowers  resistance  and  greatly  increases  the  effects  of  other  infec- 
tions, especially  tuberculosis.  The  secondary  results  are  often  more 
disastrous  than  the  primary  effects. 

Resistance  of  the  Parasite. — The  adult  worm  in  the  intestinal  tract 
may  be  benumbed  or  killed  with  thymol,  betanaphthol,  chloroform,  chen- 
opodium,  eucalyptus  oil,  and  other  vermifuges. 

From  the  standpoint  of  prevention,  it  is  more  important  to  know  the 
resistance  of  the  eggs  and  larvae  during  their  free-living  stages.  Stiles 
and  Gardener  have  shown  that  the  soil  under  and  around  privies  is  not 
entirely  free  from  infection  with  hookworm  even  five  months  after  the 
ipTixj  was  last  used,  although  the  infection  is  considerably  reduced  at  the 
end  of  four  months.  Wlien  the  fecal  matter  has  undergone  decom- 
position under  water  most  of  the  hookworm  eggs  are  dead  in  about  ten 
weeks,  though  some  still  survive,  but  probably  all  are  dead  in  three 
months.  It  would  not  be  safe  to  use  such  material  as  a  fertilizer  in  less 
than  three  months.  The  encysted  larvae  may  live  in  water  several 
months. 

The  larvae  are  readily  killed  by  dryness  and  freezing.  The  infection 
was  once  considered  to  be  dust-borne,  but  the  fact  that  the  parasites  are 
killed  by  drying  renders  the  danger  from  dust  negligible.  The  fact  that 
freezing  kills  the  eggs  and  larvae  largely  explains  why  the  disease  is  not 
endemic  in  this  country  north  of  the  Potomac. 

It  has  been  shown  that  chlorinated  lime  fails  to  kill  hookworm  eggs 
in  22  to  40  hours.    Schiiffler  kept  the  larvae  alive  almost  four  months  in 


158     DISEASES  SPREAD  BY  THE  ALVINE  DISCHARGES 

water  with  two  or  three  drops  of  a  one  per  cent,  quinin  solution  to  10  c.  c. 
Oliver  found  that  sea  water  killed  the  larvae  in  37  minutes. 

Prevention. — The  prevention  of  hookworm  disease  consists  in  pre- 
venting pollution  of  the  soil  and  in  treating  existing  cases  so  as  to 
diminish  the  amount  of  infection.  The  principles  of  prevention  are  easy 
in  theory,  but  their  application  is  difficult  in  practice  on  account  of  the 
widespread  and  enormous  amount  of  the  disease.  The  suppression  of 
hookworm  disease  means  the  social  and  economic  uplift  of  nations,  the 
education  of  millions  of  people,  and  an  entire  change  in  their  daily 
hygienic  habits.  Education  of  the  masses  is  an  important  factor,  calling 
for  cooperation  between  the  health  authorities,  civic  forces,  the  medical 
profession,  schools,  and  philanthropic  agencies;  it  is  something  for  the 
preacher  and  teacher. 

Soil  Pollution. — The  prevention  of  soil  pollution  is  the  essential 
factor;  it  is  the  key  to  the  situation.  This  one  line  of  prevention  could 
blot  hookworm  disease  out  of  existence.  This  requires  not  only  the 
building  of  proper  privies,  and  insisting  upon  their  being  used  in  country 
districts,  but  also  the  Mosaic  method  of  burial  of  feces  when  defecating 
in  fields  or  woods.*''  In  warm  countries  direct  pollution  of  the  soil  is 
much  more  common  and  also  much  more  dangerous  than  in  cold  coun- 
tries. Add  to  this  the  custom  of  going  barefooted  and  we  have  all  the 
factors  necessary  for  the  dissemination  of  hookworm  infection. 

Stiles  estimates  that  about  50  per  cent,  of  the  rural  homes  in  the 
South  are  without  privies.  Even  many  schools  and  churches  do  not 
have  these  accommodations,  and  are,  therefore,  hotbeds  of  infection. 
For  the  care  and  disposal  of  night  soil  see  chapter  on  Sewage. 

The  Eradication  of  the  Infection  in  Man. — Hookworms  may  be 
expelled  from  the  intestinal  tract  by  the  use  of  thymol,  oil  of  chenopo- 
dium.  betanaphthol,  or  certain  other  anthelmintic.  The  eradication  of 
the  infection  through  the  treatment  of  all  infected  persons  is  an  essential 
factor  in  preventive  measures. 

Thymol.- — The  usual  treatment  is  as  follows :  Saturday  eve- 
ning a  full  dose  of  magnesium  sulphate  is  given  to  permit  di- 
rect access  of  the  thymol  to  the  worms,  which  are  often  im- 
bedded in  the  mucus  or  chyme.  The  object  is  to  treat  the 
parasite  and  not  the  host.  On  Sunday  morning,  at  8  o'clock,  2  grams 
(30  grains)  of  thymol,  for  an  adult,  finely  powdered  in  capsules,  are 
given  by  the  mouth.  Two  hours  later,  at  10  o'clock,  2  more  grams  are 
administered;  and  at  12  o'clock  another  dose  of  salts  (never  castor  oil). 
On  account  of  occasional  cases  of  idiosyncrasy  to  thymol.  Stiles  prefers 
to  divide  the  total  dose  (60  grams  for  an  adult)   into  three  portions, 

*'The  cat  usually  buries  its  feces  and  as  a  result  it  rarely  has  hookworm 
infection;  dogs  do  not  usually  bury  their  feces  and  as  a  result  hookworms  are 
common  in  these  animals. 


HOOKWORM  DISEASE  159 

which  are  administered  at  6,  7  and  8  o'elock,  followed  by  salts  at  10. 
The  dose  for  children  should  be  based  upon  the  apparent  rather  than 
upon  the  actual  age.  During  the  treatment  it  is  important  to  avoid 
alcohol,  fats,  and  oils,  as  thymol  is  soluble  in  these  substances  and  may, 
therefore,  be  diingerous,  as  they  favor  absorption.  The  treatment  is 
repeated  every  Sunday  until  the  eggs  disappear.  Usually  two  or  more 
treatments  are  necessar}'.  Roughly  speaking,  about  one-half  of  the 
cases  clear  up  in  three  treatments,  DO  per  cent,  in  five  treatments,  and 
it  is  necessary  to  administer  drugs  to  the  other  10  per  cent,  anywhere 
from  6  to  20  times,  according  to  the  case.  A  microscopic  examination  of 
the  feces  for  eggs  will  determine  when  the  treatment  has  been  effective; 
this  examination  should  not  be  made  until  a  week  after  the  treatment, 
as  thymol  frequently  inhibits  the  egg-laying  by  the  worm. 

Chenopodium. — On  account  of  the  World  War,  the  supply  of  thymol 
became  nearly  exhausted,  and  oil  of  chenopodium  came  into  widespread 
use  in  hookworm  disease.  This  drug  is  undoubtedly  a  powerful  anthel- 
mintic, but,  like  thymol,  it  should  be  used  with  discretion.  Unfor- 
tunately it  is  not  always  of  uniform  strength  and  toxicity.  If  redis- 
tilled, the  lighter  distillate  is  more  powerful  as  an  anthelmintic  and  is 
less  poisonous  than  the  heavier  distillate.  There  are  many  different 
methods  of  administering  it,  and  authors  are  not  agreed  as  to  whether 
it  is  better  to  follow  it  with  salts  or  wnth  castor  oil.  Laboratory  experi- 
ments by  Hall  are  distinctly  in  favor  of  castor  oil,  but  some  prominent 
clinicians  prefer  to  use  salts.  It  is  important  to  recall  that  chenopodium 
inhibits  peristalsis,  hence  increases  constipation;  accordingly,  prompt 
purgation  is  important  in  order  to  avoid  poisoning.  Chenopodium  is 
also  a  cardiac  and  respiratory  depressant  and  has  an  effect  on  the  kid- 
neys, occasionally  producing  nephritis.  Despite  these  objections,  it  is 
an  exceedingly  valuable  drug  if  properly  used,  and  it  bids  fair  to  equal 
or  surpass  thj-mol  in  popularity.  It  is  certainly  preferred  to  thymol 
by  the  patients  and  it  is  more  efficient  against  hookworm  and  ascaris. 
As  it  strongly  inhibits  oviposition  the  reexamination  of  the  stools  for 
eggs  should  be  postponed  for  1-i  days  after  treatment.  As  it  is  cumu- 
lative in  effect,  the  treatments  should  not  be  repeated  oftener  than  once  a 
week,  better  two  weeks.  Authors  are  not  entirely  agreed  as  to  dosage, 
but  experience  seems  to  indicate  that  the  total  daily  maximum  dose  for 
an  adult  is  3  c.  c,  and  that  half  the  maximum  dose  (1.5  c.  c.  given  three 
times  in  doses  of  0.5  c.  c.)  is  best  as  a  routine  vermicide.  The  Inter- 
national Health  Board  **  uses  1.5  c.  c.  in  2  doses;  thus,  0.75  c.  c.  at  6  A. 
M.,  0.75  c.  c.  at  8  A.  :M.,  and  a  large  saline  purge  at  10  A.  M.  Xo  pre- 
liminary dieting  is  necessary.  Oil  of  chenopodium  will  eliminate  90  per 
cent,  of  hookworm  and  ascaris.    Detailed  tables  of  doses  for  the  different 

^*  Darling:  J.  A.  M.  A.,  Feb.  23,  1918,  LXX,  p.  499:  also,  Lancet,  1920, 
II,  69. 


160     DISEASES  SPREAD  BY  THE  ALVINE  DISCHARGES 

age  groups  have  been  worked  out  by  several  authors :  for  instance,  2  to  12 
years,  1  minim  for  each  year  minus  1  minim  (example,  6  years,  5 
minims) ;  13  and  14  years,  13  minims;  15  to  16  years,  16  minims;  17  to 
18  years,  20  minims;  19  to  20  years,  24  minims. 

Plan  of  a  Hookworm  Campaig^n. — The  eradication  of  the  infection 
in  man  was  carried  out  on  a  wholesale  scale  by  the  Porto  Rican  Anemia 
Commission,  consisting  of  Ashford,  King,  and  Gutierrez.  Their  methods 
were  highly  successful  and  have  served  an  equally  useful  purpose  in 
other  places.  They  established  a  clinic  for  the  microscopic  diagnosis 
and  free  treatment  of  the  disease.  The  good  results  of  treatment  spread 
rapidly,  so  that  the  facilities  of  the  clinic  were  soon  taxed  to  its  utmost 
capacity.  Kot  the  least  important  function  of  the  clinic  was  to  educate 
the  profession  as  well  as  the  people.  In  a  little  while  the  clinic  was 
moved  to  another  point,  and  so  on,  until  it  gradually  covered  the  entire 
island.  The  same  general  plan  was  used  in  the  south  and  is  used  now 
in  various  other  parts  of  the  world,  especially  by  the  International 
Health  Board. 

Educaiion. — Education  is  one  of  the  most  important  factors  in  erad- 
icating hookworm  disease,  for  the  reason  that  its  final  control  depends 
upon  improvements  in  the  sanitary  habits  of  the  people,  especially  in  the 
rural  districts.  To  change  the  daily  habits  of  half  a  nation  is  an  uplift 
that  requires  time  and  patience.  It  is  perhaps  best  to  begin  with  the 
school  children;  even  then  it  will  take  a  generation  for  results.  Very 
little  can  be  accomplished  by  force,  and,  if  the  customs  and  prejudices  of 
the  people  are  ignored,  the  reformer  and  benefactor  meet  with  rebuff  and 
failure.  It  is  a  good  idea  to  have  a  public  health  day  or  a  public  health 
week  in  the  schools,  during  which  time  lectures  and  educational  work 
upon  hookworm,  typhoid,  tuberculosis,  and  other  prevalent  infections  are 
considered.  The  children  carry  the  lesson  into  the  home.  Pamphlets, 
posters,  lectures,  exhibits,  and  popular  articles  in  the  magazines  and 
newspapers  all  contribute  their  share.  The  medical  profession  in  the 
infected  areas  may  need  instruction  and  a  little  prodding  to  awaken 
interest  in  the  problem.  In  the  popular  education  on  health  matters 
the  medical  profession  should  lead,  especially  through  the  health  authori- 
ties.   This  has  also  become  one  of  the  manifest  duties  of  the  practitioner. 

Cleanliness. — After  all,  the  prevention  of  hookworm  disease  is  a 
question  of  decency  and  cleanliness.  Water  sometimes  carries  the  infec- 
tion, hence  it  should  be  clean  or  cleansed  by  filtration  or  boiling.  Soiled 
hands  may  carry  the  infection  to  the  mouth,  hence  they  should  be  washed 
before  eating.  Vegetables  fertilized  with  night  soil  may  be  infected. 
This  practice  is  not  clean  and  should  be  forbidden,  especially  in  the  case 
of  those  vegetables  usually  eaten  raw.  With  cleanly  habits  there  would 
be  no  soil  pollution,  and  the  disease  would  be  checked. 

Personal   Prophylaxis. — Personal    prophylaxis    consists    in    wearing 


HOOKWOKM  DISEASE  101 

shoes  and  otherwise  avoiding  contact  with  the  infected  soil.  ^liners, 
l)rick  makers  and  others  compelled  to  work  in  infested  soil  may  wear 
gloves.  Other  measures,  such  as  boiling  the  water,  eating  only  cooked 
or  clean  food,  washing  the  hands,  and  avoiding  the  infected  area,  have 
either  been  dwelt  upon  or  are  too  obvious  to  need  further  emphasis. 

Immigration. — An  important  factor  in  the  spread  of  liookworm  dis- 
ease in  the  Ignited  States  is  immigration.  Every  country  that  brings 
laborers  from  hookworm  regions  is  bringing  in  a  constant  stream  of 
infection,  California  has  established  quarantine  measures  against  In- 
dian coolies,  90  per  cent,  of  whom  are  infected. 

Collateral  Benefits. — The  best  part  of  a  hookworm  campaign  is  the 
collateral  good  it  does.  This  applies  as  well  to  a  sanitary  campaign 
directed  against  almost  any  disease.  The  suppression  of  hookworm  dis- 
ease will  diminish  the  amount  of  tuberculosis,  typhoid  fever,  dysentery, 
and  other  infections.  Thus,  in  Bilibid  prison,  Manila,  the  death  rate 
was  formerly  excessive — 234  per  thousand  when  the  Americans  took 
charge.  This  was  reduced  to  75  per  thousand  by  sanitary  measures, 
such  as  boiled  water,  screens,  disinfection,  improved  food,  less  crowding, 
better  air,  more  sunlight,  etc.,  but  despite  these  sanitary  improvements 
the  death  rate  could  not  be  hammered  down  below  75  per  thousand. 
Then  it  was  found  that  many  of  the  prisoners  were  infected  with  hook- 
worms. Thymol  was  administered  and  the  death  rate  fell  to  13.5  per 
thousand.  Schapiro  *^  found  that  treating  hookworm  disease  on  planta- 
tions in  Costa  Rica  caused  an  increase  in  earning  capacity  and  in  acre- 
age cultivated.  On  one  farm,  the  laborers  earned  27  per  cent, 
more,  and  on  another  1-4.6  per  cent.  more.  Another  farm  cultivated 
33  per  cent,  more  coffee  with  the  same  number  of  laborers,  at  a  lower 
unit  cost.  He  also  noted  a  reduction  in  morbidity  and  infant  mor- 
tality. 

-  Another  instance  of  the  collateral  benefits  resulting  from  sanitary 
work  is  the  plague  campaign  in  San  Francisco,  which  cut  typhoid  fever 
in  half,  although  no  special  attention  whatever  was  paid  to  the  latter  dis- 
ease. The  purification  of  the  water  supply  in  Hamburg  by  filtration  cut 
down  the  general  death  rate  and  diminished  the  morbidity  of  diseases  not 
water-borne.  One  of  the  most  encouraging  phases  of  sanitary  work 
directed  against  tuberculosis,  typhoid  fever,  and  hookworm  disease  is  the 
assurance  that  a  successful  campaign  will  result  in  fundamental  and 
permanent  control  or  eradication  of  other  communicable  diseases.  The 
prevention  of  tuberculosis  deals  especially  with  personal  hygiene,  and  the 
prevention  of  typhoid  fever  and  hookworm  with  the  sanitation  of  the 
environment.  The  combination  of  the  two,  therefore,  embraces  almost 
the  entire  range  of  preventive  medicine. 

**  Schapiro,  L.:  "The  Physical  and  Economic  Benefits  of  Treatment  for 
Hookworm  Disease."     J.  A.  M.'A.,  Nov.  15,  1919,  LXXVIII,  Xo.  20,  p.  1507. 


163     DISEASES  SPKEAD  BY  THE  ALVINE  DISCHARGES 

REFERENCES 

For  an  extensive  bibliography  of  hookworm  disease  see  Stiles  and  Hassell, 

1920,  Index  "Catalogue  of  Medical  and  Veterinary  Zoology,"  Bull.  114, 

Hyg.  Lab.,  U.  S.  Public  Health  Service. 
For  discussion  of  campaigns  see  especially  the  reports  of  the  Porto  Rican 

Commission,  the  Rockefeller  Sanitary  Commission  (1910-14)  and  the 

International  Health  Board. 
For  discussion  of  sanitary  privies,  see  special  bulletins  on  this  subject  by 

the  U.  S.  Public  Health  Service,  and  by  many,  especially  the  southern 

state  Boards  of  Health,  particularly  Health  Bulletin,  N.  C.  State  Board 

of  Health,  V.  34,  Nov.  7,  1919. 


CHAPTER    III 

DISEASES  SPREAD  LARGELY  THROUGH  DISCHARGES  FROM 
THE  MOUTH  AND  NOSE 

This  group  of  diseases  is  the  most  prevalent  and  damaging  of  the 
infections  to  which  flesh  is  heir.  The  respiratory  diseases  prevail  more 
especially  in  temperate,  cold  and  variable  climates,  but  occur  also  in 
warm  latitudes  and  even  in  the  tropics.  They  are  endemic  everywhere, 
epidemics  are  frequent,  and  pandemics  sweep  the  world  like  a  devastat- 
ing plague  about  once  a  generation.  As  a  group,  the  respiratory  infec- 
tions are  less  well  understood  and  hence  less  controllable  than  the  in- 
testinal diseases.  In  addition  to  the  usual  modes  of  spread  by  contact 
and  through  the  discharges  from  the  mouth  and  nose,  the  respiratory 
diseases  may  also  be  transferred  in  many  other  ways;  thus,  infection 
may  be  contracted  in  food  and  drink,  by  hand  to  mouth  infection,  or 
by  fomites,  such  as  cups,  spoons  and  other  things  that  are  mouthed. 
Infection  taken  into  the  mouth  and  nose  does  not  necessarily  cause  a 
respiratory  disease,  as,  for  example,  cerebrospinal  fever. 


TUBERCULOSIS 

Tuberculosis  is  the  most  frequent  and  Avidespread  of  all  the  major 
infections.  In  this  country  9  per  cent,  of  all  deaths,  and  in  Germany  12 
per  cent.,  are  caused  by  tuberculosis.  The  toll  falls  heaviest  during  the 
period  of  life  of  greatest  usefulness — thus  30  per  cent,  of  all  deaths 
between  the  years  of  15  and  60  are  due  to  pulmonary  tuberculosis  alone. 
Naegeli,  from  a  careful  examination  of  a  large  number  of  bodies  in 
Zurich,  found  evidence  of  tuberculosis  in  over  90  per  cent.  The  lowest 
figures  based  on  the  evidence  of  pathologic  anatomy  are  those  of  Beitzke, 
who  examined  1,100  bodies  in  Berlin.  In  children  under  15  he  found 
evidence  in  27.3  per  cent.,  and  in  persons  over  15,  58.2  per  cent.  The 
difference  between  Naegeli's  figures  and  Beitzke's  is  due  to  a  difference  in 
the  interpretation  of  the  pulmonary  scars  and  adhesions  at  the  apices, 
and  the  small  fibrous  nodules  in  the  lungs.  Beitzke  does  not  consider 
such  lesions  as  of  tuberculous  origin,  and  leaves  them  out  of  his  figures. 
If  these  were  included,  his  percentage  would  also  be  very  much  higher. 
The  frequency  with  which  we  become  tuberculized  is  indicated  by  the 

163 


164     DISEASES  FEOM  DISCHAKGES  OF  MOUTH  AND  NOSE 

fact  that  70  per  cent,  of  persons  more  than  15  years  old  give  the  von 
Pirquet  cutaneous  reaction. 

In  the  United  States  it  is  estimated  that  160,000  persons  die  each 
year  of  tuberculosis.^  Of  the  100.000,000  people  now  living  in  this 
country,  it  is  estimated  that  9,000,000  are  doomed  to  die  of  tuberculosis, 
unless  the  disease  is  checked.  The  loss  in  life  and  treasure  is  appalling. 
It  cost-s  the  United  States  alone  about  $500,000,000  annually.  It  is, 
therefore,  most  encouraging  that  preventive  measures  based  upon  modern 
conceptions  of  the  disease  as  a  communicable  infection  are  beginning  to 
give  encouraging  results. 

The  number  of  cases  of  clinical  tuberculosis  in  a  community  may  be 
estimated,  according  to  Philip  of  Edinburgh,  by  multiplying  the  number 
of  deaths  from  tuberculosis  at  a  given  time  by  20.  More  conservative 
estimates  in  this  country  use  10  as  a  factor.  Thus  in  1911  there  were 
4,817  deaths  from  tuberculosis  in  Massachusetts,  which  would  mean 
nearly  50,000  cases  in  the  state  during  that  year.  About  1/5  of  these 
are  extrapulmonary,  and  about  1/5,  or  10,000,  need  hospital  or  sani- 
tarium care.  Therefore,  the  number  of  deaths  from  tuberculosis  multi- 
plied by  2  gives  an  approximate  estimate  of  the  number  of  beds  necessary 
to  provide  for  the  open  cases.  In  the  Framingham  demonstration,  Arm- 
strong found  1  per  cent,  of  the  population  had  active  tuberculosis,  and 
2.15  per  cent,  had  active  or  arrested  tuberculosis.  From  this  it  is  esti- 
mated that  in  the  United  States  at  large  the  ratio  of  the  known  cases 
to  deaths  would  be  about  7  to  1  for  active  tuberculosis  and  15  to  1  for 
active  and  arrested  cases.  In  Cleveland,  Ohio,  4.7  active  cases  were 
registered  with  the  health  department  per  death  from  tuberculosis. 

Tuberculosis  began  to  decline  before  the  nature  of  the  infection  was 
known.2  The  decline  is  gradual.  Modern  methods  have  so  far  made 
little  apparent  impression  upon  the  gross  amount  of  the  infection.  The 
social  and  economic  conditions  of  the  mass  of  the  population  must  be 
improved  before  any  great  decline  in  the  mortality  rate  can  be  expected, 
as  will  presently  be  pointed  out. 

Tuberculosis  is  fast  becoming,  in  fact  already  is,  a  class  disease;  it  is 
more  prevalent  among  t|;ie  poor  than  the  well-to-do.  Hence  the  preven- 
tion of  tuberculosis  has  become  a  sociologic  problem.  Poverty  with  its 
attendant  hardships — poor  food,  bad  housing,  crowding,  overwork  and 
worry — diminishes  resistance  to  the  disease;  while  prosperity,  which 
buys  good  food,  rest,  change  of  air  and  scene,  choice  of  occupation,  and 
diversion,  increases  our  resistance  to  the  disease,  and  avoids  contact 
with  the  infection.    An  increase  of  wage  or  decrease  in  the  cost  of  living; 

^  The  death  rate  from  all  forms  of  tuberculosis  in  the  registration  area  of 
the  United  States  in  1917  was  146.4  per  100,000,  and  from  tuberculosis  of  the 
lungs  128.9. 

^Villamin  in  1865  demonstrated  by  inoculation  of  rabbits  that  tuberculosis 
is  an  infectious  disease;  proven  by  Koch  in  1882. 


TUBEKCITLOSTS  1G5 

shortenin*]:  tlie  hours  of  work;  improving  the  conditions  of  industrial 
liv'i'ieno;  iiddinir  to  the  number  of  holidays;  playgrounds,  ])arks.  and 
wholesome  recreation,  all  h(dj)  to  increase  our  resistance  against  and 
iliminisii  the  prevalence  of  tuhereulosis.  Science  lias  shown  the  way;  it 
remains  for  society  to  apply  the  knowledge.  "Social  Justice"  is  part  of 
the  ])rogram  of  ])reventive  nu'dicine. 

A  distinction  shoiild  he  drawn  between  luhcrculoits.  wliicli  means  a 
])r()cess  due  to  tbe  tubercle  bacillus,  and  Inhcrcuhtr.  wliicb  means  tuber- 
culous like.  The  student  should  also  keep  in  mind  the  difference  be- 
tween tuberculous  infection  and  tuberculous  disease,  for  only  a  small 
proportion  of  those  infected  develop  clinical  tuberculosis.  If  tubercu- 
losis were  an  acute  disease  with  a  short  period  of  incubation,  its 
contagious  nature  would  be  as  apparent  as  diphtheria  or  scarlet 
fever. 

The  Difference  between  the  Human  and  the  Bovine  Tubercle  Bacilli. 
— There  are  at  least  three  kinds  of  tubercle  bacilli :  human,  bovine,  and 
avian.  The  human  and  bovine  varieties  resemble  each  other  closely; 
the  essential  difference  lies  in  the  fact  that  the  human  type  is  very 
pathogenic  for  man,  but  has  little  pathogenicity  for  cattle,  rabbits,  mon- 
keys, and  other  animals.  On  the  other  hand,  the  bovine  type  is  very 
pathogenic  for  almost  all  mammalian  animals  except  man ;  it  is  patho- 
genic for  man,  but  less  so  than  the  human  bacillus.  Even  when  large 
numbers  of  the  human  bacilli  are  injected  into  a  calf,  a  general  disease 
does  not  usually  result ;  at  most  only  a  local  lesion  is  produced.  The 
critical  test  used  in  almost  all  laboratories  is  upon  rabbits.  When  0.01 
milligram  of  a  bovine  culture  is  injected  intravenously,  or  10  milligrams 
subcutaneously,  into  a  full-grown  rabbit,  generalized  tuberculosis  results 
in  about  6  weeks;  whereas  10  to  100  times  these  amounts  of  a  human 
strain  produce  at  most  a  slight  localized  tuberculosis.  The  culture  must 
be' young,  that  is,  about  3  weeks  old;  it  should  be  taken  from  solid  media 
and  weighed  while  moist. 

The  human  bacillus  grows  luxuriantly  upon  culture  media, 
covering  the  entire  surface  of  the  medium  with  a  rich,  dry,  crinkled, 
mold-like  vegetation.  The  growth  of  the  bovine  bacillus  upon  artificial 
culture  media  is  more  sparse,  thinner,  less  extensive,  and  somewhat 
slower.  According  to  Theobald  Smith,  who  in  1898  pointed  out  the  dif- 
ferences betw^een  these  two  types,  the  human  bacillus  produces  in  arti- 
ficial culture  media  a  different  reaction  curve  from  that  produced  by  the 
bovine  bacillus. 

Morphologically  the  bovine  bacillus  is  often  shorter,  plumper,  and 
stains  more  uniformly  than  the  human  bacillus,  which  is  ordinarily  club- 
shaped,  irregular,  and  stains  with  interrupted  markings.  The  morpho- 
logical and  tinctorial  characters  are  not  sufficiently  distinctive  to  dis- 
tinguish one  type  from  the  other. 


1G6     DISEASES  ri70M  DTSOHABaES  OF  MOUTH  AND  XOSE 

There  are  no  specific  differences  between  the  tuberculins  of  bovine 
and  human  origin. 

The  avian  tubercle  bacillus  is  found  most  frequently  in  chickens  and 
also  in  pigeons,  pheasants,  and  guinea-fowl.  Geese  and  ducks  appear 
immune.  The  avian  bacillus  is  quite  pleomorphic  and  stains  somewhat 
more  readily  than  either  the  human  or  bovine  types.  The  avian  bacillus 
grows  luxuriantly  upon  artificial  culture  media  at  45°  C.  and  even  multi- 
plies at  temperatures  as  high  as  50°  C,  which  is  in  marked  contrast  to 
the  mammalian  types,  which  do  not  vegetate  above  40°  C.  The  avian 
bacillus  grows  rapidly,  so  that  upon  glycerin-agar  or  upon  blood  serum 
there  is  an  abundant  growth  in  10  days,  which  consists  of  a  white,  moist, 
and  greasy  mass  quite  different  in  young  cultures  from  the  dried  and 
crinkled  appearance  of  the  human  type.  Guinea-pigs  show  a  decided 
resistance  to  the  avian  cultures,  but  rabbits  are  susceptible,  although 
characteristic  lesions  do  not  develop.  Chickens  and  pigeons  may  be 
infected  with  certainty  by  feeding,  and  it  is  probable  that  in  nature 
avian  tuberculosis  is  generally  transmitted  in  this  way. 

Acid-fast  bacilli  are  found  in  cold-blooded  animals,  and  are  also 
widely  distributed  in  nature.  They  grow  best  at  room  temperature 
(20  to  30°  C),  and  are  inhibited  at  blood  heat.  They  are  not  patho- 
genic for  warm-blooded  animals.  Some  of  these  cultures  are  called 
fish  tubercle  bacilli,  but  their  relationship  to  tuberculosis  is  doubt- 
ful. 

Bovine  Tuberculosis  in  Man. — Concerning  bovine  tuberculosis  in  man, 
we  now  possess  definite  knowledge  which  permits  of  precise  statements. 
At  one  time  the  danger  of  bovine  tuberculosis  to  man  was  greatly  exag- 
gerated. Koch  went  too  far  on  the  other  side  when  he  announced  at 
London  before  the  International  Congress  on  Tuberculosis  in  1901  that 
there  was  practically  no  danger  of  man  contracting  tuberculosis  from 
cattle.  Later  Koch  modified  this  dictum,  for  it  was  soon  proved  that 
the  bovine  bacillus  has  a  certain  amount  of  pathogenic  power  for  man 
and  that  some  of  the  tuberculosis  in  man  is  contracted  from  bovine 
sources.  About  25  per  cent,  of  all  tuberculosis  under  5  years  is  associated 
with  the  bovine  bacillus.  Fatal  bovine  tubei-culosis  is  rare  after  the 
fifth  year.  The  bovine  bacillus  is  responsible  for  about  0.5  per  cent,  of 
all  deaths  due  to  tuberculosis. 

Pulmonary  tuberculosis  in  man  is  practically  never  associated  with 
the  bovine  bacillus.  Bovine  tuberculosis  in  man  is  usually  a  disease  of 
the  lymph  glands  or  bones — the  lymph  nodes  of  the  cervical  region  and 
the  lymph  nodes  in  the  abdomen  being  especially  attacked.  This  is  due 
to  the  fact  that  the  portal  of  entry  of  the  bovine  bacillus  is  usually 
through  the  tonsils  or  the  small  intestines.  Bovine  tuberculosis  may 
become  a  fatal  infection  in  man  when  it  is  generalized  through  the 
blood  in  the  form  of  acute  miliary  tuberculosis  or  when  it  localizes  in  the 


TUBERCULOSIS 


167 


meninges  or  other  vital  parts.  About  oiie-qiiarter  to  onc-tliird  of  all 
cases  of  tuberculosis  in  children  under  5  years  of  age  is  associated  with 
the  bovine  type.  It  is  probable  that  all  these  cases  derive  their  infection 
through  the  ingestion  of  tubercle  bacilli  in  cow's  milk.  There  is  little 
danger  from  meat,  as  it  is  usually  cooked  and  tuberculosis  of  the  muscles 
is  very  rare. 

The  following  table^  shows  the  relation  between  bovine  and  human 
tuberculosis  in  2,527  cases: 

These  cases  include  all  that  have  been  published  up  to  1917,  namely: 

1511   cases  collected  by   Park  and   Krumwiede    (1912),  which  also 
include  those  of  the  British  Eoyal  Commission   (1907-11), 
and  those  of  Bulloch  (1910). 
356  cases  of  Eastwood  and  Fred  Griffith  (1911),  (1916). 
430  cases  of  Stanley  Griffith  (1914),  (1915-17),  (1916). 
70  cases  of  Fraser  (1912). 
72  cases  of  Mitchell  (191-1),  and 
88  cases  of  Wang  (1917). 


2527  total  cases. 


COMBINED  TABLE  OF  ALL  CASES 


CLASSIFICATION 

Adults  16  years 
and  over 

Children 
16  yea 

5   to 

rs 

Children   under 
5  years 

Human 

1  Bovine 

Human     Bovine 

1 

Human 

Bovine 

Pulmonary    tuberculosis,    including 

1000(a) 
24 
39 

6 
35 
12 
62(d) 

6 
82(e) 

2 

5 

5 

7(b) 

2 

'i 

3 

10 

'i 
1 
2 

28 

17 
3 
5 

'    6 

76 

"ei 

2 

1 

45 

29 

169 

55 

"2 

18 
4 
89(g) 

4 

1 

13 
32 
13 

34 

22(c) 
10(c) 

4 

4         1 
61(d) 
8         1 
255(f) : 

2     : 

! 

Tuberculous  cervical  adenitis 

75 

Tuberculous  bones  and  joints 

64(h) 
1 

Miscellaneous    (other  forms)... 

at 
irk 

2 

1273 

38 

420 

171 

415 

199 

Percentage   of  bovine   infection 
each  age  period 

,_ 

J 

2 

9 

28.9 

32 

4 

Mixed    strains    reported    by    Pi 
and  Krumwiede 

Total    .  . 
Grand  t 

2,516 

11 

Dtal.  .2,55 

!7 

(a)  Including  4  atypical  strains. 

(b)  '■  1  intermediate  strain. 

(c)  "  1  mixed  strain. 

(d)  "  1   atypical   strain. 


(e)  Including     3  atypical  strains. 

(f)  "  10 

(g)  "  2 

(h)  "  3  mixed   strains. 


*Jour.  of  Path,  and  Bad.,  Apr.,  1917,  p.  131. 


168     DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 

From  a  study  of  1,038  of  these  cases  we  find : 

16  years  and  over 686  cases     9  with  bovine  bacilli=  1.3% 

Between  5  and  16  years 132       "      33      "  "  "     =35.0% 


132 
Under  5  years 120 


59 


:49.1% 


Many  of  the  cases  included  in  the  above  total  were  selected  cases. 
The  436  cases  studied  in  the  Research  Laboratory  in  New  York,  however, 
were  not  selected;  of  these  cases  the  following  were  found  associated 
with  the  bovine  bacillus: 


Diagnosis 


Pulmonary  tuberculosis 

Tuberculous  adenitis,  cervical 

Abdominal  tuberculosis 

Generalized  tuberculosis 

Tubercular  meningitis  with  or  without  generalized 

lesions 

Tuberculosis  of  bones  and  joints 


Adults 


None 
4% 

16% 
3% 


5% 


Five  to 
Sixteen 


None 

37% 
50%' 
40% 


3% 


Under 
Five 


None 

57% 
68% 
26% 

15% 


KosseFs  table  also  brings  out  the  significant  fact  that  in  organs 
directly  related  to  the  digestive  tract,  like  the  lymph  nodes  of  the  neck 
and  the  abdominal  organs,  bovine  bacilli  are  as  frequent  as  human 
bacilli. 

Eastwood  and  also  Griffith*  studied  a  series  of  195  deaths  from  all 
causes,  between  the  ages  of  2  and  10  years.  The  results  of  these  interest- 
ing studies  are  combined  in  the  following  table : 


Number  of  Cases 

Classification  of  Culture  Isolated 

Age  Periods 

Free  from 

Tubercle 

BaciUi 

Tubercle 
Bacilli 
Dead 

Tubercle 
Bacilli 
Living 

Bovine 

Human 

Mixed 

Bovine  and 

Human 

27 

12 

14 

12 

1 

3 

4 

4 

1 

2 
4 
3 
3 
2 
2 
3 

19 

21 

14 

15 

16 

2 

4 

7 

6 

4 

1 

3 

1 
2 

13 

17 

13 

14 

13 

2 

3 

5 

3 —  4  .years 

— 

1 

77 

20 

98 

17 

80 

1 

It  will  be  noted  that  of  the  total  of  195  children,  118,  or  60.5  per 
cent.,  showed  evidence  of  tuberculous  infection.  The  condition  found  in 
the  118  was  as  follows:  In  92  (47.2  per  cent,  of  195  or  78.0  per  cent, 
of  118)  tuberculous  lesions,  verified  by  subsequent  cultures,  were  found; 


*  Reports  to  the  Local  Government  Board  on  Pub.  Health  and  Med.  Subjects. 
London,  1914,  N.  S..  88.  1914. 


TUBEECULOSTS  169 

in  six  (3.1  per  cent,  of  195  or  5.1  per  cent,  of  118)  livinj^^  bacilli  were  ob- 
tained in  culture,  but  there  were  no  tuberculous  lesions;  and  in  20  (10.3 
per  cent,  of  195  or  16.9  per  cent,  of  118)  tuberculous  lesions  were 
present,  but  the  tubercle  bacilli  apparently  were  dead.  One  of  the  inter- 
esting features  of  this  investigation  is  that  living  tubercle  bacilli  may  be 
present  in  children  in  the  absence  of  lesions,  and  on  the  other  hand, 
tuberculous  lesions  may  be  present  while  the  bacilli  responsible  for  them 
may  be  dead. 

The  more  recent  figures  are  well  summarized  by  Griffith,^  who  an- 
alyzed 1,068  cases  studied  by  the  British  Connnission  on  Tuberculosis. 
Of  this  numher,  803  showed  human  bacillus  infection,  191  bovine  bacil- 
lus infection,  and  5  a  mixed  infection.  Of  various  regions  involved, 
the  examination  showed  that  bovine  infections  occurred  as  follows: 
Bones  and  joints,  19.7  per  cent.;  genito-urinary  organs,  17.65  per  cent.; 
cervical  glands,  46.3  per  cent. ;  meninges,  20  per  cent. ;  scrofuloderma. 
34.65  per  cent.;  lupus,  48.9  per  cent.  As  to  the  age  periods,  bovine 
infection  occurred  as  follows:  during  the  first  five  years  of  life,  37.55 
per  cent.;  from  five  to  ten  years,  29.45  per  cent.;  from  ten  to  sixteen 
years,  14.66  per  cent.;  after  sixteen,  6.25  per  cent. 

Woodward  voices  the  prevailing  opinion  when  he  maintains  that  the 
more  deeply  we  go  into  the  subject,  the  bovine  side  of  the  question  comes 
to  take  a  larger  and  larger  place,  especially  in  connection  with  surgical 
and  abdominal  tuberculosis,  not  only  in  the  child  but  even  in  the  adult. 

From  the  standpoint  of  our  present  knowledge  we  must  consider  that 
practically  every  case  of  bovine  tuberculosis  in  man  is  ingestion  tubercu- 
losis, contracted  from  milk  or  fresh  milk  products.  However,  it  may 
require  favorable  circumstances  in  the  teeth,  tonsils,  intestines,  or  other 
portions  of  the  digestive  tube  to  permit  the  bacilli  to  penetrate.  Oft- 
times  the  bovine  bacillus  lodges  in  the  glands  but  fails  to  set  up  disease 
on  account  of  low  virulence  or  resistance  of  the  host.  How  the  tubercle 
bacilli  get  into  milk  and  the  frequency  with  which  it  is  infected  are 
discussed  on  page  777. 

Occasionally  butchers  and  also  pathologists  at  autopsies  become  in- 
fected with  the  bovine  bacillus  through  wounds.  These  accidents  furjiish 
further  experimental  proof  that  the  bovine  type  of  the  tubercle  bacillus 
possesses  a  certain  degree  of  pathogenicity  for  man,  though  in  the  adult 
it  appears  to  be  comparatively  slight.  Skin  tuberculosis  is  usually 
benign. 

'  "The    Bacteriological    Characteristics    of    Tubercle    Bacilli    from    DiflFerent 
Kinds  of  Human  Tuberculosis."    Journ.  of  Path,  and  Bad.,  Feb.,  1920. 


170     DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 


MODES  OF  INFECTION 

There  are  two  great  sources  of  human  tuberculosis:  the  principal 
source  is  man  himself;  the  secondary  source  is  cattle. 

From  man  tubercle  bacilli  leave  the  body  mainly  in  the  sputum,  where 
they  are  found  in  great  numbers  in  all  open  cases  of  pulmonary  tubercu- 
losis. Tubercle  bacilli  may  also  leave  the  body  in  the  discharges  from 
any  open  tuberculous  lesion  wherever  situated,  especially  in  discharges 
from  the  lymphatic  glands,  bones,  intestinal  or  genito-urinary  tracts,  or 
the  skin.  In  open  cases  of  pulmonary  tuberculosis  some  of  the  sputum 
is  swallowed  and  the  bacilli  appear  in  the  feces,  therefore  any  or  all  of 
the  discharges  from  the  body  may  be  infective.  But,  from  the  practical 
standpoint  of  prevention,  the  bacilli  in  the  matter  brought  up  from  the 
lungs  are  the  source  of  the  danger  in  the  overwhelming  majority  of  cases. 

Practically  all  observers  agree  with  Koch  that  human  sputum  is  the 
main  source  of  human  tuberculosis.  Whether  the  tubercle  bacillus  is 
usually  transferred  directly  or  indirectly,  in  moist  or  in  dry  state,  by 
inhalation  or  ingestion,  are  questions  still  undetermined.  The  question 
at  issue  is  a  quantitative  one ;  that  is,  how  often  are  we  infected  by  the 
direct  aerogenic  route,  how  often  through  the  tonsils  and  upper  respira- 
tory passages,  how  often  through  the  digestive  tube,  etc.  ? 

Aerogenic  Infection — The  Cornet-Koch  Theory. — The  belief  that 
tuberculosis  is  air-borne,  that  is,  that  pulmonary  tuberculosis  is  a  primary 
inhalation  infection,  has  long  been  the  natural  and  favorite  theory, 
from  the  fact  that  the  lungs  are  most  frequently  affected.  This  opinion 
was  strongly  expressed  by  Koch  in  1884,  and  repeated  by  him  in  1901,  at 
the  British  Congress  on  Tuberculosis.  For  many  years  it  found  prac- 
tically universal  acceptance.  Cornet  taught  that  the  tubercle  bacilli 
entered  the  lungs  in  the  dust  of  dried  and  pulverized  sputum. 

The  evidence  of  pathologic  anatomy  ■  strengthens  the  belief  in  the 
importance  of  aerogenic  infections  as  the  chief  portal  of  entry.  Thus, 
the  studies  by  Ghon,^  at  the  St.  Anne's  Children's  Hospital  in 
Vienna,  indicate  very  strongly  that  the  actual  path  of  infection  is  by  the 
air  passages.  Approximately  95  per  cent,  of  181  autopsies  studied  by 
him  represent  a  primary  localization  of  the  bacilli  in  the  lungs.  On  the 
other  hand,  it  seems  that  direct  aerogenic  infection  has  been  greatly  over- 
estimated, while  some  students  of  the  subject  go  so  far  as  to  state  it  is  of 
little  or  no  practical  importance.  It  is  believed  that  very  few  bacteria 
suspended  in  the  air  actually  reach  the  lungs,  being  caught  on  the  moist 
mucous  membranes  of  the  upper  air  passages.  Further,  tuberculosis  of 
the  lungs  is  usually  at  the  apex,  which  is  not  in  the  direct  line  that  float- 
ing particles  in  the  air  would  usually  be  mechanically  carried.    It  is  true 

'  "Der  primare  Lungenherd  bei  der  Tuberkulose  der  Kinder/'  Berlin,  1912. 


TUBERCULOSIS  171 

that  duyt  uiulor  certain  conditions  may  contain  tubercle  bacilli,  but  it  is 
now  known  that  this  organism  soon  dies  when  exposed  directly  to  the  sun 
and  air,  and  that  the  dust  out  of  doors  is  not  apt  to  contain  many  live 
bacilli,  and  when  it  does  so  the  dilution  must  be  enormous.  It  is  differ- 
ent with  house  dust.  Tubercle  bacilli  may  live  a  long  time  in  dark,  moist 
places,  but  even  here  the  danger  cannot  be  as  great  as  miglit  bo  supposed 
when  we  study  the  nature  of  tuberculous  sputum.  This  substance  is 
usually  tenacious  and  gummy,  and  dries  into  tough,  glue-like  masses, 
which  are  pulverized  with  great  difficulty.  It  therefore  seems  unlikely 
that  dust  under  ordinary  circumstances  would  contain  dangerous  num- 
bers of  live  tubercle  bacilli.  The  danger  from  this  source  is  further 
diminished  when  we  consider  that  a  large  number  of  tubercle  bacilli  die 
in  sputum  even  M'hen  protected  from  sunlight  and  other  injurious  influ- 
ences. It  is  now  known  that  even  under  most  favorable  conditions  in 
artificial  culture  media  the  great  majority,  perhaps  99  per  cent.,  of  the 
bacilli  die  within  three  months.  Transplants  made  from  cultures  over 
six  months  old  usually  do  not  grow.  The  danger  of  house  dust  contain- 
ing live  tubercle  bacilli  from  a  quantitative  standpoint  is,  therefore,  re- 
duced; on  the  other  hand,  street  dust  raised  by  a  March  wind,  or  house 
dust  raised  by  beating  carpets  or  dry  sweeping  is  a  real  peril. 

A  dusty  atmosphere,  even  though  it  contains  no  tubercle  bacilli,  is, 
however,  dangerous,  in  that  it  irritates  the  delicate  mucous  membranes 
and  thus  opens  the  door  for  infection. 

One  point  of  importance  in  this  controversy  is  the  experimental  evi- 
dence that  it  requires  very  few  tubercle  bacilli  by  inhalation  to  produce 
the  disease,  whereas  it  may  require  hundreds  and  even  thousands  to  cause 
infection  by  ingestion.  Findel  found  that  from  6,000  to  19,000  times 
as  many  tubercle  bacilli  are  needed  when  fed  as  when  inhaled,  to  pro- 
duce the  disease  in  guinea-pigs.  This  is  given  as  a  reason  why  infection 
via  the  digestive  tract  is  comparatively  rare  in  man. 

Cornet  and  others  have  actually  found  live  tubercle  bacilli  in  the  dust 
and  upon  objects  of  rooms  where  tuberculous  patients  are  careless  with 
their  sputum.  In  one  of  Cornet's  experiments  47  out  of  48  guinea-pigs 
exposed  to  the  dust  produced  by  sweeping  a  carpet  with  a  stiff  broom 
became  tuberculous.  The  carpet  had  been  purposely  infected  with  tuber- 
culous sputum  shortly  before.  Dust  containing  tubercle  bacilli  may  also 
enter  the  atmosphere  from  soiled  linen,  upholstery,  handkerchiefs,  and 
other  fabrics  containing  the  dried  tuberculous  sputum.  Tuberculous  dust 
may  also  be  stirred  up  by  walking  over  floors  and  dragging  the  infection 
by  ladies'  skirts.  Crawling  infants  and  playing  children  are  exposed 
to  especial  danger  of  infection.  They  get  the  fresh  virulent  material 
on  their  hands,  which  are  then  carried  to  the  mouth.  It  is  now  believed 
that  in  most  cases  of  tuberculosis  the  infection  is  contracted  in  child- 
hood, but  the  disease  develops  later. 


172     DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 

Droplet  Infection. — When  it  was  found  that  the  danger  from  dust 
theoretically  was  not  as  great  as  was  supposed,  Fliigge  called  attention 
to  the  fact  that  in  speaking,  coughing,  sneezing,  and  in  other  violent 
expiratory  efforts  the  fluid  contents  of  the  mouth  are  sprayed  into  the 
air  in  the  form  of  a  fine  mist.  These  tiny  droplets  contain  tubercle 
bacilli  or  germs  of  any  other  infection  that  may  be  in  the  mouth.  Ordi- 
narily these  droplets  are  only  carried  2  or  3  feet,  but  under  exceptional 
circumstances  may  be  carried  30  or  40  feet  or  more;  however,  at  these 
distances  the  dilution  is  enormous  and  the  danger,  therefore,  much 
diminished.  The  tubercle  bacilli  contained  in  the  droplets  sprayed  from 
the  mouth  are  fresh  and  virulent,  and  may  land  directly  upon  the  mucous 
membranes  of  the  healthy  individual  or  may  be  conveyed  indirectly 
through  food,  fingers,  and  other  objsects.  There  is  danger  from  droplet 
infection,  but  it  cannot  be  the  usual  mode  of  transmission  in  tuberculosis 
from  the  nature  of  the  circumstances.  The  danger  from  droplet  infec- 
tion is  increased  by  close  association  with  the  patient  in  stuffy,  ill-venti- 
lated rooms,  especially  if  the  individual  does  not  take  proper  care  in 
coughing  and  sneezing.  For  a  further  discussion  of  droplet  infection 
see  pages  461  and  940. 

Ingestion  Infection. — Little  by  little  the  view  gained  ground  that 
some  cases  of  tuberculosis,  particularly  in  children,  might  be  due  to 
bacilli  entering  through  the  mucous  membrane  of  the  alimentary  canal. 
Now  we  recognize  that  much  of  the  tuberculosis  in  children  comes  through 
the  alimentary  tract.  Many  years  before  the  discovery  of  the  tubercle 
bacillus  Chauveau  (1868)  was  inclined  to  the  belief  that  the  alimentary 
canal  may  be  the  portal  of  entry  in  tuberculosis.  Woodward  in  1894 
maintained  that  the  infecting  bacilli  might  reach  the  lungs  through  some 
part  of  the  alimentary  canal.  He  drew  attention  to  the  fact  that  in  many 
children,  and  also  in  animals  fed  on  tuberculous  material,  the  lungs  may 
be  markedly  affected.  He  traced  the  course  of  the  infection  through 
caseous  or  old  calcareous  mesenteric  glands  up  through  the  diaphragm 
to  the  posterior  mediastinal  glands,  and  so  to  the  lungs.  Still  in  1899 
analyzed  259  fatal  cases  of  tuberculosis  occurring  in  the  Hospital  for 
Sick  Children,  London,  and  concluded  that  the  infection  had  occurred 
through  the  alimentary  canal  in  20.5  per  cent,  of  the  cases.  Shennan  in 
1900,  dealing  with  316  autopsies  at  the  Royal  Hospital  for  Sick  Children 
in  Edinburgh,  found  this  ratio  to  be  28.1  per  cent. 

There  is  no  doubt  that  the  lungs  are  more  or  less  involved  in  all  cases 
of  generalized  infection,  especially  in  children,  but  these  are  not  cases  of 
pulmonary  tuberculosis  (phthisis)  in  the  usual  meaning  of  the  term. 
Children  rarely  have  phthisis.  It  is  phthisis  or  pulmonary  tuberculosis 
which  causes  87.5  per  cent,  of  all  the  mortality  from  tuberculosis  and 
whose  mode  of  origin  is  now  in  question. 

Behring  in  1903  maintained  that  the  tubercle  bacilli  might  be  taken 


TTTBET^CULOSTS  170 

up  from  tlie  intestine  and  pa.^s  thi()u<:li  the  niesentcric  j^dands,  so  <i[ainint^ 
access  by  the  blood  stream  to  tlie  lungs  witlioiit  lcii\  inir  any  lesion  in  the 
gut  or  glands  to  mark  the  portal  through  which  they  iiad  entered  or  the 
route  by  whieh  they  had  traveled,  and  that  pulmonary  tuberculosis  was 
commonly  caused  in  this  way.  Behring's  theory  of  the  origin  of  phthisis 
did  not  find  a  ready  acceptanee.  Nevertheless,  the  belief  that  phthisis 
may  be  caused  by  bacilli  which  have  been  swallowed  and  absorbed  from 
the  digestive  tube  gradually  gained  ground.  \'allee  in  1904  concluded 
from  his  own  investigations  that  ingestion  of  dust  or  food  infected  with 
tubercle  bacilli  was  the  quickest  and  surest  method  of  infection.  A  little 
later  Calmette  (1905),  of  Lille,  appeared  as  a  strong  supporter  of  this 
view.  Calmette  went  so  far  as  to  assert  that  the  immense  majority  of 
cases  of  pulmonary  tuberculosis  in  man  are  caused  by  ingested  bacilli  and 
not  by  inhalation.  Whitla,  in  1908,  and  Symmers  repeated  some  of  this 
work  and  became  converted  to  Calmette's  doctrine,  and  these  views  have 
gained  a  number  of  adherents.  Cobbett  (1910)  considers  that  the  inges- 
tion theory  is  based  on  a  slender  substructure  of  experiments  from  which 
too  sweeping  conclusions  have  been  formed.  Thus  Calmette  and  his  col- 
leagues claim  that  even  anthracosis  is  caused  not  b}'  the  carbon  particles 
inhaled,  but  the  particles  ingested,  which  pass  through  the  intestinal 
mucosa  and  lodge  in  the  lungs.  Cobbett  showed  the  experimental  error 
and  demonstrated  that  India  ink  intimately  mixed  with  cream  is  not 
absorbed  in  any  great  amount  from  the  intestine,  for  the  cream  reappears 
of  a  normal  color  in  the  lacteals.  He  found,  however,  that  feeding  finely 
divided  carbon  matter  caused  traces  of  pigmentation  in  the  lung  and 
bronchial  glands  when  long  continued.  Heller  and  Yulcanstein  showed 
that  the  feeding  of  large  amounts  of  coal  dust  never  produces  that  grade 
of  anthracosis  which  is  found  after  the  inhalation  of  much  smaller 
amounts. 

'  There  is  now  sufficient  proof  to  state  definitely  that  tubercle  bacilli, 
when  taken  in  food  or  drink,  may  pierce  the  mucous  membrane  of  the 
digestive  tube  and  produce  lesions  in  distant  parts  of  the  body.  It  is  also 
demonstrated  that  the  tubercle  bacillus  may  thus  travel  without  leaving 
macroscopic  evidence  of  its  passage  in  its  wake.  Fraenkel  '  and  others 
have  shown  that  the  tubercle  bacilli  may  pass  through  the  uninjured  skin 
of  guinea-pigs,  leaving  no  trace  of  their  passage  at  the  place  where  they 
had  been  rubbed  upon  the  skin,  yet  causing  tuberculosis  of  the  internal 
organs.  Tubercle  bacilli  remain  alive  in  l}Tnph  nodes,  as  well  as  other 
organs,  for  104  days  (Bartel)  without  producing  gross  or  visible  changes. 
Eavenel  and  others  have  shown  that  tubercle  bacilli  may  pass  through  the 
intestinal  wall  without  leaving  a  trail  behind  them.  It  does  not,  there- 
fore, necessarily  follow  that  the  seat  of  the  primary  lesion  in  tuberculosis 
is  the  site  of  the  entrance  of  the  infection. 

''Hijg.  Rundschau,  XX,  1.5,  Aug.   1,   IfllO,  p.  817. 


174     DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 

It  is  also  claimed  that,  no  matter  how  the  tubercle  bacillus  reaches  us, 
whether  in  dust  or  droplets,  by  kissing,  or  through  fingers,  flies,  cups, 
handkerchiefs,  or  milk,  it  either  passes  through  the  tonsils  or  mucous 
membrane  of  the  upper  respiratory  passages,  or  is  carried  into  the  intes- 
tinal tract  and  absorbed  from  the  intestines.  Viewed  in  this  light,  the 
portal  of  entry  even  in  dust  infection  may  be  through  ingestion  rather 
than  through  direct  aerogenic  infection  of  the  lungs.  Experimentally  it 
is  easy  to  prove  that  tubercle  bacilli  given  by  the  mouth  may  produce  a 
generalized  and  fatal  tuberculosis;  thus,  of  100  guinea-pigs  given  one 
large  feeding  of  a  bovine  culture  by  Rosenau  and  Anderson,  99  died  of 
tuberculosis.  That  infection  by  ingestion  does  not  tell  the  whole  story  is 
judged  from  the  fact  that  primary  tuberculosis  of  the  mesenteric  nodes  in 
man  is  not  as  common  as  we  might  expect.  On  the  other  hand,  it  is 
claimed  that  the  tubercle  bacillus  may  pass  these  lymph  glands,  leaving 
little  or  no  trace  behind  them.  Thus  the  work  of  Weichselbaum  and  his 
pupils,  Bartel,  iSTeuman,  and  Spieler,  strengthens  the  importance  of 
ingestion  as  the  portal  of  entry.  These  investigators  found  that  the 
tubercle  bacillus  produces,  in  addition  to  the  specific  tubercles,  other 
lesions  of  a  simple  lymphatic  hyperplastic  character.  These  early  lesions 
are  called  the  "lymphoid  stage"  ("lymphoide  stadium").  The  recogni- 
tion of  this  early  stage  is  of  importance  in  determining  the  point  of 
invasion. 

These  investigators  assume  that  the  tubercle  bacillus  is  carried  from 
the  mesenteric  or  the  neck  glands  either  through  the  lymphatics  directly, 
or  through  the  thoracic  duct  and  the  arterial  circulation  to  the  lungs  and 
other  tissues  and  organs  of  the  body.  The  disease  usually  localizes  itself 
in  the  lung  because  this  organ  presents  the  least  resistance. 

Weichselbaum  believes  that  ingestion  tuberculosis  occurs  much  more 
often  in  man  than  is  commonly  supposed,  and  especially  in  children.  He 
assumes  that  the  tubercle  bacilli  may  pass  through  the  mouth,  nose,  or 
throat.  It  seems  immaterial  whether  the  bacillus  is  taken  with  food  or 
other  substances  placed  in  the  mouth,  or  is  contained  in  the  inspired  air, 
or  enters  the  mouth  and  nose  through  any  other  medium.  The  first 
lesions  do  not  consist  in  the  formation  of  specific  tubercles,  but  in  the 
so-called  lymphatic  tuberculosis.  This  stage  lasts  a  variable  time  and 
may  end  in  recovery  or  may  lead  to  specific  tuberculosis  either  through 
reinfection,  or  it  may  light  up  itself  without  a  new  infection.  The  specific 
tubercles  may  occur  either  at  the  portal  of  entry  or  in  the  lungs  and 
bronchial  glands  or  in  other  organs. 

Behring  (1903)  brought  forward  the  theory  that  alimentary  infection 
occurs  in  the  early  months  of  life.  The  tender  mucous  membrane  of 
babies  permits  the  bacillus  to  pass  readily.  The  bacilli  remain  latent  in 
the  tissues  and  acquire  increased  activity  later  in  life.    According  to  this 


TUBEKCULOSrS  175 

view  tuberculosis  of  adults  is  the  "eiul  of  a  son;r.  tiie  beginning  of  whieh 
for  the  unfortunate  patient  was  sun<^  in  the  cradU'.'' 

It  is  clear  from  the  evidence  at  hand  that  pulmonary  tuberculosis  may 
arise  either  by  inhalation  or  by  ingestion,  but  it  is  becoming  increasingly 
clear  that  in  most  cases  the  l)acilli  enter  the  liody  tlirough  the  mouth, 
throat  and  tonsils,  which  are  common  passages  (or  air  and  food.  Before 
a  final  judgment  can  be  given  concerning  the  usual  cliannel  of 
entrance  of  the  tubercle  bacillus,  we  will  need  more  information  on  the 
subject.  There  are  many  other  things  about  tuberculosis  that  are  im- 
perfectly understood.     Th.e  disease  needs  further  study. 

Flies. — Under  certain  circumstances  flies  may  readily  transfer  tuber- 
cle bacilli  from  exposed  sputum  to  fingers,  lips,  or  food.  This  may 
account  for  an  occasional  case. 

Water. — Large  quantities  of  tuberculous  sputum  that  escape  disinfec- 
tion and  an  additional  large  number  of  tubercle  bacilli  in  the  excreta 
finally  reach  the  drinking  water.  Xearly  all  persons  with  tubercle  bacilli 
in  their  sputum,  pass  some  of  them  in  their  feces.  The  tubercle  bacillus 
is  particularly  resistant  to  putrefactive  processes,  and  may  live  a  long 
time  in  water.  The  use  of  contaminated  water  can,  therefore,  not  be 
disregarded.  Lawrason  Brown  found  tubercle  bacilli  in  the  water  of  the 
Saranac  Eiver  into  which  sewage  from  a  sanatorium  was  discharged.  A 
study  of  the  vit^.l  statistics  of  Hamburg,  Lowell,  and  Lawrence  seems  to 
show  a  diminution  in  tuberculosis  following  a  purification  of  the  water 
supply  by  filtration  (Mills-Eeincke  Phenomenon,  page  1148).  It  is  clear, 
however,  that  tuberculosis  is  not  ordinarily  a  water-borne  infection. 

Infection  in  Childhood. — Every  child  has  numerous  opportunities 
to  become  infected.  Beginning  with  no  infection  at  birth,  a  very  small 
proportion  of  infants  become  infected  by  the  end  of  the  first  year,  as 
indicated  by  the  von  Pirquet  skin  tuberculin  test.  At  the  age  of  2  years, 
the  percentage  is  10;  at  4  years,  25  to  30  per  cent.;  from  5  to  10  years, 
about  50  per  cent.;  and  by  15  years,  from  GO  to  70  per  cent.  Pulmonary 
tuberculosis  is  rare  in  childhood;  glandular  tuberculosis  common. 

The  infant  at  birth  has  a  clean  bill  of  health.  After  a  year,  it  be- 
comes a  quadruped  and  on  all  fours,  so  that  it  comes  in  close  contact 
with  sputum  on  the  floor.  Soon  it  drinks  cow's  milk,  much  of  which 
contains  tubercle  bacilli.  As  the  child  grows,  it  continues  in  close  con- 
tact with  raw  sputum  in  the  dust  and  dirt  of  floors,  streets,  gutters  and 
surfaces,  so  that  it  soon  "eats  its  peck  of  dirt."  At  school,  at  play,  and 
at  home  the  ingestion  of  offal  and  filth  of  all  kinds  is  repeated.  The 
contact  between  child  and  child,  and  between  child  and  adult  is  intimate, 
and  of  such  a  nature  as  to  favor  the  spread  of  infection.  The  child  at 
play,  at  marbles,  at  ball,  at  hoop  rolling,  at  top  spinning,  at  rope  skip- 
ping, and  in  scores  of  other  ways  cannot  help  getting  on  its  hands  the 
sputum  of  others.    Children  have  no  inherent  sense  of  cleanliness.    Hand 


176     DISEASES  FEOM  DISCHARGES  OF  MOUTH  AND  NOSE 

to  mouth  infection  becomes  a  hygienic  problem  of  first  rank.  Children 
thus  have  frequent  chances  of  acquiring  tubercle  bacilli  from  dust,  dirt, 
milk,  droplets,  and  other  sources.  Krause  believes  that  the  "schmutz  and 
schleim"  infection  of  Volland  plays  a  major  role  in  children,  and  that  the 
adult  disease  is  an  expression  of  childhood  infection. 

Contact  Infection. — The  majority  of  cases  of  tuberculosis  contract 
the  disease  through  "contact."  Contact  infection  is  a  general  and  con- 
venient term ;  it  implies  the  rather  quick  transference  of  fresh  infection 
in  which  the  bacilli  pass  from  one  individual  to  the  other  in  a  brief  space 
of  time  and  through  a  short  distance.  Contact  infection  may  be  either 
direct  or  indirect;  through  dust,  through  bacilli  in  the  air,  or  through 
contaminated  food,  through  soiled  fingers  or  objects;  through  sputum 
smeared  surfaces,  as  well  as  in  numerous  other  ways.  The  infections 
transferred  through  kissing,  pencils,  pipes,  toys,  cups,  and  other  objects 
all  come  under  the  convenient  category  of  "contacts."  Even  infec- 
tion through  droplets" is  included  in  the  present-day  conception  of  con- 
tact infection.  The  term  is  a  practical  one,  and  implies  close  association, 
though  not  necessarily  actual  contact,  between  the  sick  and  the  well. 
Viewed  in  this  sense,  tuberculosis  is  a  house  disease  or  a  family  disease. 
With  this  conception  it  makes  little  practical  difference  whether  the  in- 
fection enters  the  body  through  the  respiratory  tract  or  the  digestive  tube. 
Either  or  both  would  be  possible  in  regarding  the  disease  as  "contagious" 
in  the  sense  of  contact  infection. 

Dr.  H.  G.  Lampson  in  his  "Studies  on  the  Spread  of  Tuberculosis  in 
Five  Counties  of  Minnesota"  ^  came  to  the  conclusion  that  79  per  cent,  of 
individuals  fully  exposed  for  a  long  period  of  time  to  open  cases  of 
tuberculosis  became  infected.  Only  28  per  cent,  of  those  partially  ex- 
posed or  exposed  for  a  short  period  of  time  became  infected.  The  per- 
centage of  infections  from  casual  exposure  such  as  everyone  encounters, 
was  small,  8  per  cent.  The  more  frequent  infection  of  children  is  ex- 
plained, at  least  in  part,  by  their  more  intimate  contact  with  the  patient. 
At  all  ages,  the  intimacy  and  length  of  exposure  are  the  determining 
factors. 

Pollak  states  that  the  earlier  the  infection  the  more  serious  the  out- 
come. This  receives  support  from  Wallgren's  statistics,  for  out  of  51 
consumptives,  15  had  been  exposed  during  the  first  5  years  of  life, 
whereas  of  the  13  healthy  persons  who  gave  a  history  of  exposure,  in  but 
1  case  had  that  exposure  been  before  the  sixth  year.  It  is  now  believed 
that  the  infection  is  usually  received  during  childhood,  but  remains  latent 
until  adolescence  or  early  adult  life,  when  the  disease  becomes  clinically 
apparent. 

Although  there  is  some  doubt  concerning  the  exact  mode  of  transmis- 
sion and  the  portal  of  entry  that  the  tubercle  bacillus  usually  takes,  we 

»  U.  ^.  Public  Health  Reports,  Vol.  XXX,  No.  2,  Jan.  8,  1915, 


TUBERCULOSIS  177 

have  sutlicieiit  knowledge  to  guide  our  preventive  measures  with  every 
assuranee  of  success.  One  thing  is  certain:  tuberculosis  is  an  infection 
spread  mainly  from  man  to  man,  usually  because  sputum  in  some  form  or 
other  enters  the  mouth;  and  secondarily  from  cows,  through  milk. 

IMMUNITY 

Man  possesses  a  considerable  resistance  to  tuberculosis.  This  is  shown 
by  the  fact  that  many  cases  recover  spontaneously  and  that  70  per  cent, 
of  all  individuals  who  reach  the  age  of  IG  years  and  who  spend  most  of 
this  time  in  association  with  their  fellowmen  under  the  usual  urban  con- 
ditions have  at  one  or  more  times  been  infected.  The  resistance  to  tuber- 
culosis increases  after  middle  life,  due  perhaps  to  the  immunity  which  is 
induced  by  these  prior  infections.  The  rarity  of  conjugal  phthisis  is 
thus  explained.  There  is  probably  no  true  racial  immunity  to  tubercu- 
losis. Some  races  show  a  smaller  incidence  to  the  disease,  owing  prob- 
ably to  modes,  of  life,  habits  of  nutrition,  and  conditions  of  exposure. 
Some  of  the  white  races  seem  to  have  acquired  a  certain  degree  of  resist- 
ance through  inheritance  (?)  and  almost  universal  infection.  All  races 
long  removed  from  civilization  are  particularly  susceptible. 

The  human  body  is  capable  of  taking  care  of  a  certain  amount  of 
infection  -without  the  development  of  clinical  tuberculosis.  The  dose, 
that  is,  the  number  of  tubercle  bacilli  and  their  virulence,  is,  therefore, 
a  very  important  factor  in  determining  the  course  of  events.  This 
may  readily  be  demonstrated  upon  susceptible  animals  and  is  doubtless 
true  of  man.  It  takes  at  least  ten  tubercle  bacilli  to  infect  a  guinea- 
pig.  Frequent'  reinfections  occurring  at  short  intervals  with  small 
numbers  of  tubercle  bacilli  may  break  down  the  immunity.  In  man  the 
balance  between  immuniiy  and  suscepiihUity  to  tuberculosis  is  delicately 
ad-justed:  there  is  a  very  small  factor  of  safety.  The  resistance  to  the 
infection  may  be  increased  by  attention  to  personal  hygiene,  fresh  air, 
and  good  food ;  immunity  may  readily  be  broken  down  by  any  weakening 
influence;  herein  lies  the  keynote  of  personal  prophylaxis. 

The  immunity  to  tuberculosis  is  not  sufficiently  strong  to  overcome 
a  large  amount  of  infection.  As  in  all  other  infectious  processes,  the 
strongest  and  most  robust  individuals  in  the  prime  of  life  succumb  to 
the  disease  in  a  short  time  if  they  receive  into  the  tissues  a  large  number 
of  virulent  tubercle  bacilli.  Hence  the  avoidance  of  the  infection  is  one 
of  the  most  important  of  our  preventive  measures. 

Romer  has  shown  that  active  tuberculous  guinea-pigs  resist  a  second 
small  dose  of  tubercle  bacilli.  Krause  coniirmed  these  results  on 
monkeys,  and  von  Behring  and  Calmette  on  cattle.  This  indicates  that 
a  disease  which  is  progressive  within  the  body  may  ward  off  fresh  infec- 
tion from  without.     Superinfections  may,  however,  occur  under  certain 


178     DISEASES  FROM  DISCHAEGES  OF  MOUTH  AND  NOSE 

conditions.  Krause  believes  that  tuberculous  infection  can  occur  once 
only  during  the  life  of  man,  and  this  usually  takes  place  in  childhood. 
The  frequency  with  which  such  diseases  as  measles^  whooping  cough, 
syphilis,  typhoid  fever  and  other  infections  are  followed  by  tuberculosis 
makes  us  believe  that  most  acute  infectious  processes  diminish  resistance 
to  the  tubercle  bacillus.  Syphilis  predisposes  to  tuberculosis.  A  high 
percentage  of  adult  consumptives  give  a  positive  Wassermann  reaction.^ 
The  mechanism  of  the  immunity  to  tuberculosis  is  probably  exceed- 
ingly complex.  There  is  no  antitoxic  immunity.  The  tuberculins  are 
not  true  toxins.  Phagocytosis  and  cellular  reactions  play  a  very  impor- 
tant role.  Studies  upon  anaphylaxis  throw  a  certain  amount  of  light 
upon  the  mechanism  of  immunity  in  tuberculosis.  The  phenomenon  of 
hypersusceptibility  is  beautifully  illustrated  in  the  action  of  tuberculin, 
which  is  a  comparatively  harmless  substance  to  a  normal  individual,  but 
produces  a  marked  reaction  in  a  sensitized  individual.  This  reaction 
must  be  useful  in  protecting  the  body  against  the  invasion  of  the 
tubercle  bacillus,  and  also  in  guarding  it  against  the  spread  of  the  disease 
after  it  has  become  localized.  Thus,  if  tuberculin  is  placed  upon  a 
normal  conjunctiva  no  reaction  follows.^*'  This  first  application,  however, 
sensitizes  the  tissues  of  the  conjunctiva  so  that,  if  the  application  is 
repeated  after  the  lapse  of  a  few  weeks,  there  is  a  violent  reaction.  The 
same  phenomenon  doubtless  occurs  when  a  tubercle  bacillus  lodges  in  a 
lymph  gland  or  in  the  lung  or  some  other  part  of  the  body.  The  first 
time  it  meets  with  little  resistance ;  the  next  time  the  tissues  react  imme- 
diately and  vigorously.  All  of  nature's  protecting  agencies,  such  as  the 
germicidal  substances  in  the  blood,  the  phagocytic  cells,  and  antibodies, 
a;re  concentrated  upon  the  point  where  they  are  most  needed.  In  the 
same  way  the  body  protects  itself  against  the  extension  of  a  tuberculous 
focus.  The  parts  surrounding  a  tubercle  become  sensitized  and  react  so 
as  to  encapsulate  the  focus  with  a  cellular  and  fibrous  coat  of  mail.  This 
reaction  is  probably  stimulated  by  small  amounts  of  tuberculin  produced 
within  the  tuberculous  focus.  When  the  tuberculin  is  not  produced 
autogenously  in  sufficient  amounts,  as  in  chronic  lesions  of  the  bones, 
or  inactive  processes  of  the  glands  or  skin,  the  specific  reaction  may  be 
stimulated  to  advantage  by  the  injection  of  small  quantities  of  tuberculin. 
If,  however,  the  tuberculin  is  given  in  too  large  amounts  or  too  fre- 
quently, the  power  of  reaction  is  readily  broken  down.^^  When  this  occurs 
the  mechanism  of  immunity  has  been  destroyed,  there  is  little  resistance 
left  to  the  extension  of  the  infection,  and  death  soon  occurs.  Clinical 
experience  has  demonstrated  the  danger  of  large  doses  of  tuberculin  or 
small  amounts  too  often  repeated  in  tuberculosis.    The  same  may  readily 

'See  pages  59,  65,  581;  also  J.  A.  M.  A.,  April  27,  1918,  p.  1211. 
"Rosenau  and  Anderson,  J.  A.  M.  A.,  Vol.  I,  March  28,   1908,  p.  961. 
"  A  state  of  anti-anaphylaxis  is  produced. 


TUBKl^OTILOSIS  179 

be  demonstrated  experimentally  in  tin-  lower  animals.  Those  facts  are 
of  fundaniontal  iniport-ancc  in  Uw.  us(>  of  tulxTculin  both  in  diagnosis 
and  tlieraj)}'. 

It  is  quite  proper  to  deny  dogmatically  the  hereditary  transmission  of 
tuberculosis  in  educational  pamphlets  i'or  popular  use.  The  infection 
is  not  transmitted  hereditarily,  although  it  occasionally  passes  from 
mother  to  fetus  congenitally.  Tubercle  bacilli  do  not  occur  in  the 
spermatozoon,  and  do  not  appear  in  the  seminal  fluid.  They  are  not 
found  in  the  ovum;  in  fact,  a  tubercle  bacillus  in  the  ovum  would  doubt- 
less result  in  the  death  of  the  egg.  The  bacilli,  however,  may  pass  from 
mother  to  fetus  through  the  placenta.  Warthin  shows  that  placental 
tuberculosis  is  more  common  than  is  supposed.  The  lesions  in  the  pla- 
centa are  not  those  of  typical  tubercle  formation. 

While  the  tubercle  bacillus  itself  is  rarely  transmitted  from  parent 
to  fetus,  an  hereditary  tendency  or  disposition  to  the  disease  may  be 
transmitted.  We  have  no  definite  knowledge  as  to  what  this  decreased 
resistance  consists  in ;  it  may  be  a  diminished  power  of  reaction.  For  this 
view  there  is  analogy  in  the  experiments  upon  anaphylaxis  in  guinea- 
pigs,  in  which  it  has  been  shown  that  hypersusceptibility  to  a  foreign 
protein  such  as  tuberculin  may  be  transmitted  from  mother  to  young. 

A  mild  infection  with  bovine  tuberculosis  in  early  life  seems  to  leave 
a  certain  degree  of  immunity  against  the  human  strain.  At  least,  persons 
who  have  glandular  tuberculosis  of  the  bovine  type  in  childhood  are  said 
to  be  less  apt  to  have  tuberculosis  of  the  lungs  in  later  life.  Likewise, 
the  human  strain  injected  into  cattle  produces  a  definite  immunity 
against  the  bovine  type.  Cattle  may  be  immunized  by  the  intravenous 
injection  of  2  c.  c.  of  a  suspension  of  a  pure  culture  of  the  human  tubercle 
bacillus.  This  produces  an  immunity  which  probably  lasts  for  1  to  2 
years.  It  should  be  remembered  that  the  himian  bacillus  under  these 
cixcumstances  remains  alive  for  a  very  long  time,  and  may  appear  in  the 
milk  provided  there  is  a  lesion  in  the  udder.  This  presents  a  danger 
which  cannot  be  disregarded. 

Trudeau  long  ago  showed  that  the  only  definite  immunity  that  could 
be  induced  in  experimental  animals  was  through  the  use  of  live  tubercle 
bacilli.  Webb  and  Williams  ^^  have  produced  a  certain  amount  of  immu- 
nity in  guinea-pigs  and  monkeys  by  the  injection  of  small  numbers  of 
live  tubercle  bacilli.    This  procedure  is  not  practical,  even  hazardous. 

Calmette  and  Guerin  have  recently  reported  striking  results  on  im- 
munity to  tuberculosis  in  cattle,  produced  by  vaccination  with  tubercle 
bacilli  of  the  bovine  type,  reduced  in  virulence  by  prolonged  cultivation 

""Immunity  in  Tuberculosis,"  J.  A.  M.  A.,  Oct.  28,  1911,  Vol.  LVII,  No.  18, 
p.  1431.  Trans'  6th  Int.  Cong,  on  Tuberculosis,  1908.  210:  also,  Lieh,  Jour n. 
Med.  Res.,  1910,  XXX,  .3;  also,  Lawrason  Brown,  Heise,  and  PetrofF,  Joi:rn. 
Med.  Res.,  July,   1914. 


180     DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 

in  media  containing  bile.  These  authors  in  1911  ^^  showed  that  guinea 
pigs,  monkeys  and  cattle  could  tolerate  large  doses  of  tubercle  bacilli 
attenuated  by  this  method  without  acquiring  generalized  disease,  at  the 
same  time  developing  a  pronounced  immunity  to  subsequent  virulent 
infection  by  the  intravenous  route.  In  a  series  just  reported,^*  cattle 
vaccinated  with  attenuated  bacilli  showed  an  immunity  of  18  months' 
duration  to  the  most  intense  exposure. 

The  injection  of  dead  tubercle  bacilli  and  their  products  long  ago 
proved  valueless.  The  injection  of  small  doses  of  virulent  bacilli  has 
more  than  once  proved  dangerous.  The  work  of  Calmette  and  Guerin 
points  in  the  right  direction,  for  there  is  abundant  evidence  for  the 
dictum  of  Krause  that  infection  is  a  sine  qua  non  of  immunity  in 
tuberculosis:  "No  resistance  without  tubercle."  It  appears  that  immu- 
nity to  tuberculosis  is  not  general,  but  quite  specific. 

RESISTANCE  OF  THE  VIRUS 

We  have  no  easy  method  of  determining  just  when  the  tubercle  bacil- 
lus dies.  The  criterion  of  death  depends  upon  animal  experimentation. 
The  tubercle  bacillus  has  no  spore  and  may  be  classed  with  other  non- 
spore-bearing  organisms  so  far  as  its  viability  is  concerned.  Its  virulence 
fades  before  it  dies.  It  is  doubtful  whether  the  waxy  substances  protect 
the  bacillus  against  external  harmful  influences  to  any  unusual  extent. 
The  thermal  death  point  is  60°  C.  for  20  minutes.  This  is  much  less 
than  was  once  considered. ^'^  Failure  to  recognize  the  lesions  produced  by 
the  dead  tubercle  bacillus  is  responsible  for  some  of  the  false  conclusions 
reached  by  experimenters  upon  this  subject. 

From  a  practical  standpoint  the  resistance  of  the  tubercle  bacillus  in 
sputum  is  of  prime  importance.  Protected  from  the  sunlight,  it  is  now 
known  that  they  may  live  in  dried  sputum  for  months.  All  the  bacilli 
do  not  survive  under  these  conditions,  but  we  lack  methods  to  determine 
the  quantitative  reduction. 

The  tubercle  bacillus  withstands  cold  very  well.  It  has  a  marked 
resistance  against  putrefactive  processes.  It  will  live  a  year  in  water, 
which  is  a  fact  not  to  be  neglected,  as  many  tubercle  bacilli  finally  find 
their  way  into  drinking  water,  and  occasional  trouble  from  this  source 
is  possible. 

For  the  destruction  of  the  bacilli  in  sputum  only  very  strong  germi- 
cides or  exposure  to  steam  or  boiling  water  should  be  depended  upon. 
Burning  is  the  most  practical  method  for  disposing  of  tuberculous 
sputum  (see  page  1434).    Five  per  cent,  carbolic  acid  is  sufficient,  pro- 

^  Ann.  de  I'Inst.  Pasteur,  1911. 
"  Ann.  de  I'Inst   Pasteur,  XXXIV,  553,  1920. 

"  The  thermal  death  point  of  pathogenic  microorganisms  in  milk.  M.  J. 
Eosenau,  Hyg.  Lab.  Bull.  U.  8.  Pub.  Health  and  Ma/r.  Hosp.  Serv.,  No.  42. 


TUBERCULOSIS  181 

vided  equal  parts  of  t^putum  ami  solution  are  mixed  and  tiie  exposure 
continued  for  ti4  hours. 

Sunlight  is  one  of  the  best  germicides  and  often  destroys  tubercle 
bacilli  quickly.  In  direct  sunlight  the  naked  bacilli  exposed  directly 
die  in  a  few  hours;  in  diffused  sunlight,  in  a  few  days.  Tubercle  bacilli 
imbedded  in  sputum  masses  may  be  protected  against  the  germicidal 
action  of  the  sun's  rays.  The  time  the  bacilli  may  live  under  these  cir- 
cumstances is  variable.^^ 

PREVENTION 

Preventive  measures  are  based  upon  two  important  facts :  that  tuber- 
culosis is  an  infection  mainly  spread  from  man  to  man  through  tubercu- 
lous sputum,  and  secondarily  from  cattle  through  infected  milk. 
Preventive  measures  fall  into  two  categories:  (1)  avoiding  the  infection, 
and  (2)  increasing  resistance  through  personal  hygiene.  Both  are  neces- 
sary. The  infection  may  be  avoided  through  segregation;  the  use  of 
pasteurized  milk,  or  milk  from  tuberculin-tested  cattle ;  education ;  dis- 
infection ;  proper  disposal  of  tuberculous  sputum ;  the  avoidance  of  con- 
tact with  open  cases,  especially  with  those  who  do  not  use  proper  pre- 
cautions; early  diagnosis,  etc.  Increased  resistance  may  be  gained 
through  fresh  air,  good  food,  rest,  and  compliance  with  the  dictates  of 
personal  hygiene.  This  part  of  the  subject  includes  sociologic  and  eco- 
nomic reforms,  without  which  the  warfare  against  tuberculosis  cannot 
succeed.  Improvement  in  housing  conditions,  lowering  of  the  cost  of 
living,  increase  in  the  scale  of  wages,  and  all  forms  of  uplift  help 
secondarily  to  diminish  the  amount  of  the  disease.  Furthermore,  it  will 
be  necessary  to  consider  secondary  agencies,  as  preventive  clinics, 
health  insurance,  notification,  open-air  schools,  day  and  night  camps, 
etc. 

It  is  well  to  remember  that  tuberculosis  has  gradually  declined  in 
England  and  also  in  Massachusetts  since  1850 — before  the  tubercle  bacil- 
lus was  discovered.  The  decline  was  gradual  from  1850-1885,  but  quite 
pronounced  since  that  date.     (See  Fig.  16.) 

The  causes  of  this  decline  have  been  much  discussed.  It  may  be 
due  to  better  food  supply  at  all  seasons  of  the  year,  brought  about  by  im- 
proved methods  of  transportation,  and  the  general  use  of  refrigeration 
and  canning;  it  may  be  due  to  amelioration  of  social  and  domestic  life; 
it  may  be  due  to  better  hygiene  and  sanitation ;  or,  it  may  be  due  in  part 
to  the  special  antituberculosis  measures.  On  the  other  hand,  the  decline 
may  have  been  little  influenced  by  any  of  the  usually  assigned  causes,  but 
may  simply  be  a  biological  phenomenon  indicating  a  falling  off  in  the 
virulence  of  the  tubercle  bacillus,  or,  what  seems  less  likely,  an  increased 

"  V^on  Berfren,  Schweiserische  med,  Wochnschr.,  Dec.  2,  1920,  L,  No.  49,  p. 
1120;  also,  Tecon,  Paris  Med.,  Jan.  3,  1920,  X,  33. 


182     DISEASES  FEOM  DISCHARGES  OF  MOUTH  AND  NOSE 

resistance  owing  to  specific  immunization  of  the  population.  During 
recent  years,  there  has  clearly  been  a  lessened  mortality,  but  apparently 
an  increased  morbidity.  In  other  words,  the  infection  seems  to  be  more 
prevalent,  but  the  disease  less  fatal. 

Seg^eg-ation — Sanatoria.— Tuberculosis  is  a  "contagious"  disease,  and 
it  is  now  perfectly  plain  that  one  of  the  most  important  single  preventive 
measures  in  this  as  in  all  other  communicable  diseases  consists  in  isola- 
tion.    A  case  isolated  is  a  case  neutralized,  hence  the  great  value  to  the 


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TUBERCULOSIb 

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j-iG.  16. Showiis'g  the  Decline  in  the  Death-Rate  from  Tuberculosis 

The  decline  is  general  from  1850  until  1882,  when  the  tubercle  bacillus  was 
discovered,  since  which  time  the  decline  is  sharper.  Since  1910,  the  curve 
shows  a  tendency  to  stabilize. 

community  of  sanatorium  treatment.  Isolation  in  this  case  refers  only 
to  those  individuals  having  tubercle  bacilli  in  their  sputum.  It  should 
not  be  used  as  a  terminal  measure.  Too  often  the  door  is  locked  after 
the  damage  is  done.  The  power  of  forcible  removal  and  isolation  of 
the  irresponsible,  careless  or  indigent  consumptive  is  essential  to 
success.  The  isolation  in  tuberculosis  need  not  go  to  the  extreme  prac- 
ticed in  the  acute  communicable  fevers.  In  fact,  we  cannot  for  many 
years  to  come  object  to  giving  a  case  of  open  pulmonary  tuberculosis 
restricted  liberty,  provided  he  is  careful  and  cleanly  and  uses  proper 
precautions  in  the  disposal  of  his  expectoration.     When  the  disease 


TUBERCULOSIS  183 

Ijocoines  U'ss  i)roval('iit,  iiun-c  striii>;-ciil.  ;iii<l  ni'ltit  r;wv  inriisiircs  may  llidi 
be  eiil'orcoil. 

Special  measures  inusl.  l)e  taken  to  pruieil  iiii'aiits  and  eliihlren 
against  the  infeetion. 

"Every  case  of  tuberculosis  isolated  means  an  average  of  at  least 
three  less  new  infections,"  Sanatoria  should,  therefore,  be  attractive  and 
as  clieap  as  it  is  possible  to  run  them.  Free  hospital  care  for  the  open 
rases  is  necessary,  especially  tor  the  poor.  Tuberculosis  has  diiniiiished 
most  in  those  countries  where  sanatoria  are  most  in  use. 

Separate  sanatoria  ^^  should  be  provided  for  the  incipient  cases  and 
for  the  advanced  cases.  A  sharp  division  is  not  always  possible,  for  an 
incipient  case  may  develop  into  an  open  case  within  a  week,  and,  on  the 
other  hand,  open  cases  may  return  to  latency  in  a  short  time.  It  is  better 
for  each  locality  to  have  its  own  sanatorium  than  to  provide  large  insti- 
tutions which  become  unwieldy.  Furthermore,  tuberculosis,  like  other 
widespread  infections,  is  largely  a  local  problem.  A  distant  sanatorium 
will  neither  attract,  nor  keep  the  chronic  cases.  Persons  with  tubercu- 
losis need  not  necessarily  go  to  a  sanatorium  with  the  object  of  remaining 
until  cured.  It  is  worth  while  if  they  go  there  but  for  a  few  months 
to  learn  the  methods  of  treatment  and  the  technic  of  prevention.  While 
sanatoria  should  be  well  built  and  comfortable,  extravagance  is  not 
necessary.  Special  police  power  to  restrain  the  incorrigible  consumptive 
in  special  detention  wards  or  places  is  desirable. 

Tuberculosis  Dispensaries. — Every  community  should  be  provided 
with  a  dispensary  for  diagnosis,  treatment,  and  for  teaching  the  consump- 
tive how  to  care  for  himself  at  home.  Each  dispensary  should  have  at 
least  one  physician  and  a  nurse  with  special  experience  in  the  problem. 
Much  social  service  work  can  be  done  from  such  a  dispensary,  especially 
in  following  up  cases  after  leaving  the  sanatorium.  Dispensaries  are 
ne-cessary  for  early  diagnosis, — one  of  the  essentials  for  treatment  and 
prevention. 

Anti-Tuberculosis  Associations. — Associations  for  the  cure  and  relief 
of  tuberculosis  are  essential  parts  of  the  problem,  and  such  associations 
should  be  active  in  every  community  in  order  to  obtain  hospital  accommo- 
dations for  the  advanced  cases,  sanatorium  treatment  for  the  hopeful 

"Dr.  Edward  Trudeau  went  to  Saranac  in  1873  as  a  hopeless  victim  of 
consumption.  All  his  friends  were  filled  with  horror  at  the  idea  of  his  going 
practically  alone  to  die,  as  they  believed,  in  the  Adirondack  wilderness,  in  a 
little  town  consisting  of  little  more  than  a  sawmill  and  half  a  dozen  cabins, 
forty-two  miles  from  a  railroad.  Dr.  Trudeau  did  not  die,  however,  during  the 
winter  of  1873,  but  grew  very  much  better;  and  some  ten  years  later,  as  a 
result  of  his  experience,  he  founded  the  Adirondack  Cottage  Sanatorium,  which 
in  its  primitive  form  consisted  of  a  single  house  in  which,  with  great  difficulty, 
he  persuaded  two  consumptive  patients  to  live.  That  was  the  beginning  of 
tlie  demonstration  in  this  country  -J  the  fresh-air  treatment  of  tuberculosis, 
which  Brehmer  and  others  had  introduced  on  the  other  side  of  the  water- 
(Winslow.)      Read  Trudeau's  inspiring  autobiography. 


184     DISEASES  FEOM  DISCHAEGES  OF  MOUTH  AND  XOSE 

cases,  and  advice  for  the  incipient  cases,  to  obtain  and  maintain  dis- 
pensaries, district  nursing  and  necessary  legislation  and  help  in  the 
problem  of  education. 

Personal  Prophylaxis. — Personal  prophylaxis  consists  in  avoiding 
the  infection  and  in  obeying  all  the  dictates  of  personal  hygiene — that 
is,  living  a  clean,  normal,  and  temperate  life. 

Close  association  with  persons  known  to  have  tubercle  bacilli  in  their 
sputum  is  hazardous.  This  becomes  especially  dangerous  when  the  con- 
tact is  prolonged  and  intimate,  such  as  working  in  the  same  room,  espe- 
cially if  it  is  small  and  ill-ventilated,  or  living  in  the  same  house,  sleeping 
in  the  same  bed.  The  more  intimate  the  association  and  the  less  care 
the  tuberculous  individual  takes  with  the  expectoration,  the  greater  is  the 
hazard.  The  danger  diminishes  somewhat  with  age ;  infants  and  children 
need  special  protection.  The  infection  may  further  be  avoided  by  refus- 
ing to  drink  from  common  cups,  by  taking  care  in  placing  objects  in  the 
mouth  that  do  not  belong  there,  by  avoiding  dusty  atmosphere,  and  refus- 
ing to.  drink  milk  that  does  not  come  from  tuberculin-tested  cattle  unless 
it  is  pasteurized. 

Mechanical  obstructions  to  breathing  should  be  corrected,  by  surgical 
methods  if  necessary.  Functional  lack  of  proportion  in  the  chest  and 
lungs  of  young  people  favor  infection,  and  every  effort  should  be  made 
to  help  the  child  to  outgrow  them.  Breathing  exercises  and  outdoor  play 
are  especially  useful. 

A  generous  diet  is  one  of  the  best  prophylactics  against  tuberculosis. 
Good  nutrition  is  fundamental  both  in  the  prevention  and  cure  of  tuber- 
culosis. 

Resistance  to  the  disease  is  increased  by  rest,  fresh  air,  good  food, 
sunshine,  the  avoidance  of  all  depressing  influences,  such  as  worry,  over- 
work, strain,  intemperance,  and  excesses  of  all  kinds.  Attention  should 
be  given  to  slight  colds  and  other  conditions  known  to  be  predisposing 
causes  to  the  disease.  Tuberculosis  is  the  one  disease  in  which  the 
measures  of  treatment  and  of  prevention  are  to  a  large  extent  identical. 

Conditions  favoring  tuberculosis  are  anemia  and  underweight,  con- 
tinuous overfatigue,  recurrent  colds,  especially  recurrent  bronchitis,  slow 
recuperation  from  any  acute  infection,  whether  influenza,  measles  or 
whooping-cough,  prolonged  septic  processes,  or  typhoid  fever.  Syphilis 
is  one  of  the  predisposing  causes  of  tuberculosis.  It  is  well  to  remember 
that  maturity  of  tissues,  freedom  from  trauma,  normal  nutrition,  and 
the  absence  of  intercurrent  disease  or  toxic  influences  are  the  important 
"factors  of  safety"  on  the  part  of  the  body. 

Personal  prophylaxis  becomes  the  keynote  of  prevention  when  we 
recall  that  most  of  us  become  infected  during  childhood.  It  is,  there- 
fore, our  problem  to  live  so  that  the  disease  will  not  break  out  in  adult 
life. 


TUBERCULOSIS  185 

Education. — The  prevoiitioii  of  tul)tM"c-ulosis,  like  all  other  widusproafl 
infections,  depends  for  its  success  upon  the  education  of  the  people.  We 
are  now  in  possession  of  sufficient  information  of  a  precise  nature  to 
l)laie  the  facts  in  plain  words  hcforc  the  public.  This  has  been  done  in 
numerous  excellent  pamphlets  ^*  and  popular  articles  in  the  daily  press 
and  mafjazincs,  through  loitures,  conferences,  moving  pictures,  exhibits, 
and  meetings,  so  that  there  is  now  a  widespread  understanding  of  the 
problem.  Tlie  modern  message  in  tuberculosis  has  been  one  of  hope,  in 
that  the  disease  is  curable;  and  one  of  fear,  in  that  it  is  transmissible. 
The  former  has  been  a  great  encouragement  and  has  added  strength  to 
the  movement;  the  latter  is  also  helpful,  although  it  has  run  to  extremes 
in  some  quarters.  An  unwarranted  fear  of  tuberculosis  (phthisiophobia) 
has  subjected  the  tuberculous  individual  to  severe  hardships  by  branding 
him  as  a  leper.  Even  cured  cases  of  the  disease  may  find  difficulty  in 
obtaining  work.  A  wholesome  regard  for  the  infection  is  useful  and 
helpful  in  preventive  medicine,  but  an  hysterical  fear  of  tuberculosis  is 
quite  as  unwarranted  as  a  total  disregard  for  the  infection. 

Notification. — Tuberculosis  should  be  included  among  the  list  of  dis- 
eases requiring  compulsory  notification.  Without  this  important  feature 
an  adequate  control  of  the  disease  cannot  be  effected.  The  objection  to 
compulsory  notification  is  based  largely  upon  sympathy  with  the  large 
number  of  individuals  affected  and  the  sensitiveness  of  the  afflicted. 
Compulsory  notification  may  occasionally  result  in  individual  harm,  but 
is  necessary  for  the  communal  good.  The  prejudice  against  notification 
in  tuberculosis  is  rapidly  being  worn  down,  and  successful  reporting  is 
part  of  the  program  of  all  up-to-date  health  administrators. 

Tuberculosis  is  required  to  be  reported  in  ^faine,  Michigan,  Massa- 
chusetts (since  1907)  ;  many  cities:  Alameda,  California;  Asbury  Park, 
N".  J. ;  Boston,  Buffalo,  Cincinnati,  Xew  York,  Salt  Lake  City,  Trenton, 
Yonkers — also  in  Washington,  D.  C,  Minneapolis,  San  Francisco,  and 
Syracuse,    The  list  is  growing  and  the  returns  are  gradually  improving. 

In  England  and  Wales  the  notification  of  all  forms  of  tuberculosis, 
whether  in  public  or  private  practice,  is  obligatory,  since  Feb.  1,  1913. 
The  information  thus  received  is  held  as  confidential. 

Disposal  of  the  Sputum. — As  the  tuberculous  sputum  is  the  principal 
source  of  the  infection,  it  should  be  disinfected  or  disposed  of  so  that 
it  will  be  harmless  to  others.  Perhaps  the  best  way  is  to  receive  the 
expectorated  matter  into  cloths,  which  may  be  burned,  or  the  material 
may  be  received  into  one  of  the  various  forms  of  sputum  cups  and  finally 
burned  or  disinfected.  Persons  with  pulmonary  tuberculosis  must  be 
warned  against  the  possible  danger  to  others  of  coughing  without  holding 
the  handkerchief  before  the  mouth  and  nose ;  under  no  circumstances 
should  they  spit  upon  the  floor.    Penalty  for  spitting  upon  the  sidewalk. 

"International  Prize  Essay,  by  Knopf.    Published  by  The  Survey,  New  York. 


186     DISEASES  FEOM  DISCHARGES  OF  MOUTH  AND  NOSE 

upon  the  floor  of  public  buildings,  and  in  street  cars  serves  a  useful 
purpose  in  diminishing  the  spread  of  tuberculosis  as  well  as  other 
diseases.     See  Disinfection  of  Sputum,  page  1434. 

Disinfection. — Eooms  occupied  by  tuberculous  individuals  should  be 
kept  clean  and  disinfected  from  time  to  time.  A  thorough  disinfection 
and  cleansing  should  also  be  practiced  before  such  rooms  are  occupied  by 
other  persons.  This  may  be  accomplished  by  washing  all  surfaces  with 
hot  soap  and  soda,  followed  by  mopping  with  the  usual  solutions  of 
bichlorid  of  mercury  or  one  of  the  coal-tar  preparations,  and  then  a 
thorough  airing  and  sunning.  Formaldehyd  gas  alone  cannot  be  de- 
pended upon  because  it  lacks  the  power  of  penetration.  The  room  may 
finally  be  renovated  and  refurnished.  All  fabrics,  handkerchiefs,  bed 
and  body  linen  should  be  boiled  or  steamed. 

Early  Diagnosis,. — Early  diagnosis  plays  an  important  role  in  success- 
ful prevention;  not  only  does  it  give  the  individual  the  best'chances  of 
cure,  but  at  the  same  time  it  assures  the  possibility  of  maximum  protec- 
tion to  others.  Through  the  use  of  X-rays,  tuberculin  and  other  re- 
finements of  clinical  methods  it  is  now  possible  to  diagnose  tuberculosis 
at  a  st?ge  when  it  was  formerly  not  suspected.  It  is  a  great  mistake,  from 
the  standpoint  of  prevention,  to  wait  until  tubercle  bacilli  appear  in 
the  sputum  before  making  a  diagnosis  of  tuberculosis.  The  symptoms 
that  suggest  incipient  tuberculosis  are  rather  general  in  character.  It 
is  often  necessary  to  make  a  diagnosis  by  exclusion,  for  it  may  be  im- 
possible for  the  clinician  to  state  just  where  the  process  is  located.  The 
symptoms  that  suggest  incipient  tuberculosis  are  loss  of  weight,  rise  of 
temperature  in  the  afternoon,  or  subnormal  temperature  with  rapid  pulse, 
loss  of  appetite,  languor  and  lack  of  energy,  anemia,  dyspepsia,  with  or 
without  a  cough.  Probably  many  cases  of  "a  slight  run-down  condition," 
of  transient  and  irregular  febrile  attacks,  are  due  to  a  small  focus  of 
tuberculosis  hidden  from  the  ken  of  the  clinician.  In  such  cases  a  course 
of  rest,  fresh  air,  and  better  food,  with  a  change  of  scene,  may  often 
prevent  irreparable  damage.  The  establishment  of  preventive  clinics  to 
look  after  such  cases  and  the  maintenance  of  medical  clinics  to  diagnose 
and  care  for  the  early  cases  are  important  adjuncts  to  preventive  meas- 
ures. 

Housing  Conditions. — It  has  long  been  realized,  even  before  the  rea- 
sons were  understood,  that  the  incidence  to  tuberculosis  diminishes  with 
improvement  in  housing  conditions.  This  is  a  common  observation  in 
the  stabling  of  cattle  as  well  as  the  domicile  of  man.  The  reasons  for  this 
are  complex.  In  addition  to  raising  the  standard  of  living,  better  houses 
lessen  the  chances  of  contact  infection,  afford  better  air  and  more  sun- 
shine, and  tend  generally  to  the  well-being  and  uplift  of  mankind. 
House  infection  is  after  all  another  name  for  contact  infection.  Better 
housing  helps  to  lessen  the  opportunity  for  the  infection  to  develop  into 


TlTBEUnULOSTS  ,  187 

the  disease.  Municipalities  do  well  to  enact  and  cnlorce  strinrrent  laws 
re<:^ulatin^  the  coiistnictioii  of  huuses,  oltices,  stores,  and  workshops.  The 
congested  and  squalid  slums  are  hotii  a  disgrace  and  a  nicnace.  (Icnns 
are  social  climbers,  and  many  a  palace  is  invaded  w  illi  an  inrcction  from 
a  nearby  neglected  alley.  Philanthropists  cannot  do  better  than  assist 
in  improving  the  housing  conditions  of  the  poor  and  thus  help  the  art 
of  hygienic  living.     See  j)age  1337. 

Care  of  the  Cases  in  the  Home. — Open  eases  of  tuberculosis  should 
not  be  cared  for  in  the  home,  but  in  case  they  are,  such  homes  should  be 
visited  by  a  public  health  nurse. ^•'  Home  visitation  is  a  simple  but  very 
powerful  means  of  attacking  this  and  other  diseases.  It  is  the  surest 
way  of  reaching  the  indiflferent  and  ignorant  portion  of  the  public  which 
constitutes  the  great  obstacle  in  the  successful  prevention  of  disease. 
Home  visitation  is  not  merely  applicable,  but  almost  indispensable  in 
many  public  health  problems,  and  should  become  one  of  the  routine 
methods  of  a  good  public  health  organization.  Such  a  system  recognizes 
the  fact  that  tuberculosis  is  not  merely  a  bacterial  invasion,  but  a  disease 
of  defective  civilization.  Through  this  means  social  relief  may  teach 
better  standards  of  living  and  provide  better  food,  light,  air,  housing, 
clothing,  and  occupation.  A  study  of  tuberculosis  at  close  range  has 
taught  the  lesson  of  the  absolute  necessity  for  individualizing  the  treat- 
ment of  each  case  in  order  to  obtain  satisfactory  results. 

Industrial  Conditions. — Cornet  taught  that  many  a  case  of  tubercu- 
losis is  contracted  by  those  who  are  required  to  work  alongside  of  a  fellow 
workman  who  has  pulmonary  tuberculosis,  especially  in  crowded,  poorly 
ventilated  and  insanitary  workshops.  We  now  believe,  however,  that 
most  cases  are  infected  during  childhood;  nevertheless,  exposure  at  any 
period  of  life  may  be  hazardous.  Mr.  Allen  Joslin  helped  to  suppress 
the  disease  within  two  years  at  Oxford,  Mass.,  where  tuberculosis  was 
unduly  prevalent,  through  medical  inspection,  aided  by  a  nurse;  remov- 
ing the  sick  to  sanatoria,  and  by  a  general  improvement  in  the  sanitary 
and  hygienic  conditions  of  the  mill.  Similar  measures  have  been  met 
with  signal  success  in  other  industrial  centers.  Much  real  good  can  be 
accomplished  along  these  lines. 

Tuberculosis  in  Children. — In  one  sense  tuberculosis  is  an  infection 
of  childhood,  for  about  70  per  cent,  of  all  children  by  the  time  they  reach 
sixteen  years  of  age  react  to  tuberculin,  thus  indicating  that  they  have 
become  sensitized  or  ^'tuberculized.''  The  hazard  to  a  child  living  in  a 
house  wath  an  open  case  of  consumption  is  very  great.  One  of  the 
fundamental  considerations  is  to  separate  babies  at  once  from  such  an 
environment.  Children  rarely  have  tuberculosis  of  the  lungs  (con- 
sumption) ;  when  they  do  it  is  usually  rapidly  fatal.     It  is  hazardous 

"' Tliat  is,  a  nurse  specially  qualified  in  the  tuberculosis  problem,  and  with 
social  service  instinct  and  training. 


188     DISEASES  FEO:\I  DISCHARGES  OF  MOUTH  AND  NOSE 

to  permit  such  children  in  schoolrooms  or  even  to  remain  at  home ;  they 
should  be  cared  for  in  sanatoria.  It  is  the  anemic,  incipient,  pretubercu- 
lar,  glandular,  or  scrofulous  type  that  demands  especial  attention.  Such 
children  are  best  cared  for  in  school-hospitals,  sometimes  called  open-air 
schools.  These  children  are  going  to  furnish  a  large  percentage  of  the 
open  pulmonary  cases  in  later  life.  In  a  school-hospital  emphasis  should 
be  laid  on  treatment,  and  the  teaching  given  secondary  consideration. 
See  page  1337. 

Bovine  Tuberculosis. — The  prevention  of  bovine  tuberculosis  consists 
simply  in  using  milk,  cream,  and  fresh  milk  products  from  tuberculin- 
tested  cattle.  The  cattle  should  be  tested  frequently,  at  least  twice  a 
year,  for  the  disease  may  develop  in  the  cow  in  a  few  months.  When 
milk  from  non-tested  cattle  is  used,  it  should  be  pasteurized,  and  the 
same  precaution  applies  to  the  milk  used  for  making  cream,  butter,  ice- 
cream, and  other  fresh  milk  products. 

Directions  for  Testing  Cattle  with  Tuberculin. — Three  tests  are  now 
used:  (A)  the  subcutaneous  test;  (B)  the  intradermic  test;  and  (C)  the 
ophthalmic  test.    The  subcutaneous  test  is  carried  out  as  follows : 

1.  Stable  cattle  under  usual  conditions  and  among  usual  surround- 
ings, feeding  and  watering  in  the  customary  manner. 

2.  Make  a  physical  examination  of  each  animal,  and  give  to  each 
one  some  designation  by  which  the  animal  will  be  known  throughout  the 
test. 

3.  Take  each  animal's  temperature  at  least  three  times  at  two  or 
three  hour  intervals  on  the  day  of  injection;  for  instance,  at  2,  5,  and 
8  p.m. 

4.  At  8  or  10  p.m.  inject  a  dose  of  tuberculin  under  the  skin  in  the 
region  of  the  shoulder,  using  a  sterile  hypodermic  syringe  after  disin- 
fecting the  skin  at  the  seat  of  injection  with  a  5  per  cent,  solution  of 
carbolic  acid  or  a  similar  antiseptic  solution. 

5.  Tuberculin  is  not  always  concentrated  to  the  same  degree,  and 
therefore  the  dose,  which  should  always  appear  on  the  label,  varies  con- 
siderably. The  dose  of  imported  tuberculin  is  .25  c.  c.  for  an  adult  cow, 
and  before  injection  is  diluted  with  sterile  water  to  2  c.  c.  The  tuberculin 
made  by  the  Bureau  of  Animal  Industry  is  prepared  so  that  it  will  not 
be  necessary  to  dilute  it,  and  the  dose  is  2  c.  c.  for  an  adult  animal. 
Yearlings  and  2  year  olds,  according  to  size,  should  receive  from  1  to 
1.5  c.  c,  while  bulls  and  very  large  animals  may  receive  3  c.  c. 

6.  At  6  a.m.  on  the  day  following  the  injection  of  tuberculin  com- 
mence taking  temperatures,  and  continue  every  two  or  three  hours  until 
the  twentieth  hour  after  injection,  at  which  time  if  there  is  no  tendency 
for  the  temperature  to  rise  the  test  may  cease. 

7.  A  rise  of  2°  F.  or  more  above  the  maximum  temperature  observed 
on  the  previous  day,  providing  the  temperature  after  injection  exceeds 


TUBIOKCULOSIS  isi) 

103.8°  F.,  should  be  ret^^arded  as  an  indication  of  tulx-rciilosis.  Those 
cases  which  approximate  but  do  not  reach  this  standard  should  be  con- 
sidered as  suspicious  and  hold  for  a  retest  six  weeks  later,  giving  double 
the  original  dose. 

The  intradermic  test  consists  of  injecting  one  cubic  centimeter  of 
undiluted  tuberculin  into  the  skin  of  the  caudal  fold  at  the  root  of  the 
tail.  It  is  thcrut'ore  called  the  tail  test.  When  positive,  a  swelling 
appears  wiiich  persists,  and  should  be  read  in  about  72  hours.  This 
test  requires  good  teclinic.  It  is  becoming  popular  because  it  is  easier 
to  interpret  than  the  subcutaneous  test,  and  is  sometimes  positive  when 
the  latter  is  negalive. 

The  ophthalmic  test  consists  in  placing  a  tablet  containing  tuber- 
culin in  the  conjunctival  sac.  Susceptible  animals  show  a  distinct  re- 
action, consisting  of  injection,  swelling  and  exudation. 

Each  of  the  three  tests  has  limitations.  It  is  often  desirable  to  use 
two.  or  all  three  in  special  cases. 

The  Bang  Method  of  Suppressing  Bovine  Tuberculosis. — More  work 
has  been  done  in  Denmark  in  accordance  with  the  recommendations  of 
Bang  in  the  suppression  of  tuberculosis  of  cattle,  and  the  results  achieved 
are  of  greater  value  than  in  any  other  part  of  the  world.  The  system, 
in  short,  is  as  follows :  Herds  are  tested  with  tuberculin  upon  the  appli- 
cation of  the  owner  of  the  cattle.  After  the  test,  the  herd  is  divided  into 
two  parts,  (1)  tho  healthy  section  and  (2)  the  reacting  or  tuberculous 
section.  These  herds  are,  if  possible,  kept  in  separate  buildings.  If  this 
cannot  be  done,  they  are  kept  in  separate  parts  of  the  same  building,  a 
tight  partition  separating  them.  The  milk  from  both  sections  is  used  by 
the  creameries,  but  it  is  the  almost  universal  practice  in  Denmark  to 
pasteurize  the  cream  preparatory  to  ripening  it  for  churning,  and  the  law 
requires  that  skim  milk  shsll  be  heated  to  a  point  that  will  kill  the  tuber- 
cle bacilli  before  it  is  returned  to  the  farmers  to  be  used  for  feeding 
purposes.  The  lalv  further  provides  that  the  sediment  that  remains  in 
the  separator  shall  be  burned. 

The  calves  froiin  the  cows  in  the  reacting  sections  are  removed  from 
their  dams  immedlitely  after  birth  and  are  reared  on  the  milk  of  healthy 
cows  or  on  milk  of  reactors  that  has  been  heated.  These  calves  are  tested 
when  they  are  three  or  four  months  old,  and  if  they  do  not  react,  they  are 
permitted  to  enter  the  sound  section  of  the  herd.  As  a  matter  of  fact, 
reactors  are  very  rare  among  these  calves.  Most  of  them  are  born  healthy, 
and  when  cared  foir  as  directed,  they  remain  free  from  tuberculosis.  All 
cows  with  tuberculosis  of  the  udder  are  required  to  be  reported  and  are 
killed.  Some  compensation  is  allowed  for  them.  The  appraisement  is 
equivalent  to  one- fourth  of  the  meat  value  of  the  animal.  The  other 
tuberculous  cattle  in  the  reacting  section  are  examined  physically  from 
time  to  time  and  killed  in  public  abattoirs  under  veterinary  control. 


190     DISP]ASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 

Their  flesh  is  then  disposed  of  in  accordance  with  the  recommendation 
of  the  inspector.  Some  of  it  is  seized  and  destroyed,  some  of  it  is  sold 
for  food.  The  law  further  provides  that  cattle  brought  into  Denmark 
shall  be  kept  in  quarantine  until  tested  with  tuberculin  and  found  free 
from  tuberculosis. 

Many  herds  have  been  tested  in  Denmark  with  negative  results,  prov- 
ing that  tuberculosis  is  not  a  necessary  disease  among  highly  developed 
dairy  cattle,  and  that  the  tubercle  bacilli  are  not  omnipresent. 

Health  Insurance. — Health  insurance,  sick  benefits,  pensions,  non- 
employment  insurance,  and  similar  schemes  to  attempt  social  justice  are 
helpful  in  the  fight  against  tuberculosis.  The  German  industrial  associa- 
tions were  under  goverment  supervision  and  did  more  than  care  for  the 
tuberculous  workman.  The  heavy  drains  upon  the  funds  of  the  industrial 
associations  were  checked  by  the  establishment  of  "preventoria."'  These 
are  attractive  country  places  where  the  working  man  can  go  when  he  is 
"run  down."  This  simple  measure  is  a  great  boon,  and  prevents  the 
development  of  many  a  case  of  tuberculosis  as  well  as  other  diseases.  See 
also  page  1291. 

Org-anizing  a  Local  Tuberculosis  Campaign. — Tuberculosis  being  a 
local  problem  should  be  attacked  by  every  town  throughout  the  country. 
The  method  of  organizing  a  tuberculosis  campaign  is  first  to  interest  a 
number  of  different  agencies,  such  as  the  church,  business,  doctors,  politi- 
cians, women's  clubs,  the  press,  and  the  board  of  health.  This  beginning 
can  best  be  done  by  one  person  who  will  devote  himself  or  herself  to  the 
work.  After  the  press  has  printed  a  few  articles  on  tuberculosis  and  the 
pulpit  has  helped  to  emphasize  the  importance  of  the  movement,  a  local 
committee  should  then  be  formed  to  invite  a  tuberculosis  exhibit.  These 
exhibits  may  be  obtained  either  from  the  National  Association  for  Tuber- 
culosis, or  from  most  of  the  state  boards  of  health.  It  will  require  at 
least  one  hundred  and  fifty  dollars  to  finance  such  an  exhibit.  A  tubercu- 
losis society  should  then  be  formed.  The  next  step  is  to  establish  a  dis- 
pensary with  a  physician  and  a  nurse.  An  efficient  nurse  with  social 
service  training  is  essential  for  the  success  of  the  movement.  After  this 
is  well  under  way,  a  day  camp  should  be  started  in  a  modest  way  at  a 
convenient  locality,  and,  should  this  succeed,  a  night  camp  may  be  added. 
A  day  and  a  night  camp  is  the  equivalent  of  a  local  sanatorium.  This 
much  can  be  done  by  voluntary  efforts  and  private  subscription,  but  at 
this  point  the  authorities  should  take  over  the  work. 

Collateral  Benefits. — The  collateral  benefits  of  a  tuberculosis  cam- 
paign may  be  even  greater  than  the  effects  upon  the  actual  control  of 
the  disease.  Even  if  the  measures  used  prevent  only  a  few  cases  of 
tuberculosis,  they  still  would  be  worth  while,  for  they  preach  the  gospel 
of  hygiene.  The  problem  of  tuberculosis  is  closely  interwoven  with 
everything  that  pertains  to  human  welfare. 


DIPHTHERIA  191 

Outlook. — The    control    of    tuberculosis    is    complex    and    difficult. 

M;iii\-  (if  tlu'  I'iictors  arc  not  iindcrslood.  Tlic  pi'cNriii ion  of  tuberculosis 
is  no  longer  solely  a  niedieal  problem  but  larj^ely  a  sociolo^dcal  problem. 
It  is  a  disease  ol'  defective  society.  Its  eradication  will,  bowever,  take 
time  on  account  of  tbe  cbronic  nature  of  the  disease  and  its  widespread 
prevalen.ce.  We  should  be  satisfied  if  we  diminish  the  amount  of  tuber- 
culosis ai)i)recialdy  in  a  generation.  The  momentum  thus  gained  will 
increase  rapidly.  The  time  will  come  when  the  comparatively  few  cases 
left  may  be  treated  by  com])uls()ry  isolati(jn  or  other  aggressive  measures. 
I'ersistence  along  the  lines  now  understood  will  in  time  control  the 
disease,  which  will  be  the  crowning  achievement  in  preventive  medicine. 

BEFEBENCES 

The  American  Review  of  Tuherculosis,  published  monthly  by  the  National 
Tuberculosis  Association,  Baltimore,  Md. 

ViLLEMiN,  J.  A. :    Etudes  sur  la  Tuberculose,  1868. 

CoHXHEiM,  J. :  Die  Tuberculose  vom  Standpunkte  der  Infektionslehre, 
1879. 

Koch,  R.:  "Die  Aetiologie  der  Tubei'culose,"  Berl.  Klin.  Wchnschr.,  April, 
1S82;  Mitth.  a.  d.  k.  GsndUsamte,  Berlin,  1884,  II,  p.  1. 

Cornet,  G.  :  Ueber  Tuberculose.  Die  Verbreitung  der  Tubercelbacillen 
ausserhalb  des  Korpers,   1890. 

Straus,  I. :    La  Tuberculose  et  son  Bacilli,  1895. 

Flugge,  C.  G.  :  Die  Verbreitungsweise  under  Bekampfung  der  Tuberculose 
auf  Grund  experimenteller  Untersuchungen  im  hygienisehen  Institut  der 
Kgl.  Universitat  Breslau,  1897-1908.  A  collection  of  articles  by  vari- 
ous authors,  edited  by  Flugge. 

VON  PiRQUET,  C. :  Die  Allergieprobe  zur  Diagnose  der  Tuberculose  im  Kin- 
desalter.     Wien.  med.  Wchnschr.,  1907,  Ivii,  1369. 

Newsholme,  a.  :    The  Prevention  of  Tuberculosis,  1908. 


DIPHTHERIA 

Our  knowledge  of  diphtheria  is  most  satisfactory  in  that  we  know  the 
cause  of  the  disease  and  its  modes  of  transmission ;  we  are  able  to  check 
its  spread,  and  possess  a  specific  preventive  and  curative  agent  of  great 
potency. 

Diphtheria  spreads  slowly  from  person  to  person  and  from  community 
to  community.  It  is  not  necessary  to  consider  it  endemic  in  special 
indigenous  foci,  because  it  is  never  completely  absent  in  any  large  com- 
munity. Newsholme  points  out  that  diphtheria  epidemics  and  pandemics 
occur  cyclically.  The  intervals  between  the  years  of  epidemic  prevalence 
vary  greatly.     The  large  American  cities  formerly  suffered  severely. 


192     DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 

In  Boston  diphtheria  was  epidemic  in  1863-64,  1875-76,  1880-81,  1889- 
90,  and  1894;  in  New  York  in  1876-78,  1880-82,  1886-88,  and  1893-94; 
in  Chicago  in  1860-65,  1869-70,  1876-79-81,  1886-87,  and  1890.  Within 
recent  years  such  epidemic  outbreaks  have  not  taken  place,  and  the 
disease  should  never  again  be  allowed  to  get  out  of  hand.  The  death  rate 
in  the  United  States  in  1917  was  16.5  per  100,000.  Diphtheria  in 
Massachusetts  in  1919  was  responsible  for  14.9  deaths  per  100,000;  or 
a  total  of  591  deaths  out  of  7,926  cases  reported  in  the  state. 

The  cause  of  epidemic  outbursts  is  doubtless  due  to  a  fortuitous 
combination  of  such  circumstances  as  a  new  crop  of  susceptible  children, 
a  particularly  virulent  strain  of  the  bacillus,  opportunity  for  co^ntact, 
and  similar  factors  favoring  the  spread  of  the  infection.  On  the  other 
hand,  external  conditions,  such  as  dryness,  may  be  important,  for 
Newsholme  states  that  "diphtheria  only  becomes  epidemic  in  years 
in  which  the  rainfall  is  deficient.  There  is  no  instance  of  a  succession 
of  wet  years  in  which  diphtheria  was  epidemic."  It  is  more  than 
likely  that  the  great  outbreaks  are  due  to  a  combination  of  the  three 
factors  (1)  man,  (2)  the  bacillus,  and  (3)  the  environment.  Just  as  a 
spark  in  a  forest  may  cause  a  brush  fire  or  a  conflagration,  depend- 
ing upon  the  amount  of  plant  growth,  its  distribution,  its  condition 
as  to  dryness,  the  direction  and  force  of  the  wind,  the  topography 
and  nature  of  the  soil,  and  many  other  conditions,  so  diphtheria  and 
other  infections  will  smolder  or  burst  into  flame,  depending  upon 
similar  factors. 

Outbreaks  in  congested  centers,  schools,  camps,  on  board  ships, 
and  in  other  crowded  places,  are  common.  Widespread  epidemics 
have  occurred  in  country  districts.  Washington  died  of  diphtheria. 
In  the  tropics  diphtheria  is  not  a  serious  disease.  It  prevails  especially  in 
the  temperate  zones.  Newsholme  pointed  out  that  it  is  more  of  a  conti- 
nental than  an  insular  disease.  The  fatality  from  diphtheria  has 
been  greatly  lowered  since  1894,  owing  to  the  use  of  antitoxin  and 
to  refinements  of  diagnosis,  as  a  result  of  which  many  mild  cases 
are  now  included  that  were  formerly  omitted  from  the  statistical 
records.  Whether  or  not  there  has  been  a  natural  tendency  for  the 
disease  to  become  milder  in  recent  years  cannot  be  stated. 

Diphtheria  reaches  its  maximum  prevalence  in  the  autumn  of  each 
year,  which  corresponds  to  ..the  seasonal  prevalence  of  scarlet  fever. 
Diphtheria  is  a  cold  weather  disease.  The  influence  of  climate  is  con- 
firmed by  its  rare  incidence  in  the  tropics.  While  the  seasonal  prevalence 
is  in  the  colder  months,  an  epidemic  once  established  may  go  on  regard- 
less of  season,  reaching  its  maximum  at  the  period  of  highest  tempera- 
ture. 

In  1878  Dr.  Thrushfield  published  papers  illustrating  the  way  in 
which  diphtheria  hung  about  damp  houses.     A  damp  dwelling  favors 


DIPHTHKHIA  193 

sore  throats  and  colds,  aiul  may  lliiis  oiicii  a  way  lor  iii\asi(tii  of  tlie 
bacilli,  just  as  any  depressing-  iiilluciicc  may  [ii-i'dispose  to  the  infection. 
Children  with  scarlet  fever  or  measles  are  especially  prone  to  take  diph- 
theria if  the  infection  is  around.  Any  abnormal  condition  of  the  mucous 
membrane  of  the  throat  and  nose  favors  the  localization  of  the  diph- 
theria bacillus,  and  may  thus  act  as  a  predisposing  cause;  tiierefore,  sore 
throat,  foreign  bodies,  adenoids,  as  well  as  dust  or  any  irritant,  may  pre- 
dispose to  the  disease  if  the  diphtheria  bacillus  is  present.  Formerly, 
imperfect  drains  and  sewer  gas  were  givi'U  as  the  causes  of  diphtheria; 
this  is  a  fetish  which  dies  hard. 

Studies  with  the  Schick  reaction  plainly  indicate  that  two  main  con- 
ditions determine  diphtheria:  (1)  a  virulent  strain  of  the  bacillus;  and 
(2)  susceptibility. 

Modes  of  Transmission,. — The  diphtheria  bacillus  enters  by  the 
mouth  or  nose,  and  the  lesions  are  usually  localized  in  the  mucous  mem- 
branes of  the  throat,  nose,  larynx,  or  upper  respiratory  tract.  The 
bacillus  leaves  the  body  in  the  discharges  from  the  mouth  and  nose. 
Diphtheria  occasionally  affects  other  mucous  membranes  or  abraded  sur- 
faces, such  as  the  conjunctiva  or  vaginal  mucous  membrane,  or  open 
wounds ;  the  discharges  from  these  lesions  containing  the  infective  agent. 

The  bacillus  may  be  transmitted  directly  from  one  person  to  another, 
as  by  kissing;  or  exposure  to  droplet  infection  in  coughing,  speaking, 
sneezing.  The  infection  may  be  conveyed  indirectly  from  one  person  to 
another  in  many  ways ;  most  common  among  children,  perhaps,  are  toys, 
slate  pencils,  food,  fingers,  spoons,  cups,  handkerchiefs,  or  other  objects 
that  have  heen  mouthed  first  by  the  infected  child  and  then  by  the 
susceptible  child.  Experience  points  clearly  to  the  conclusion  that  diph- 
theria is  transmitted  usually  by  a  direct  exchange  of  the  flora  of  the 
nose  and  throat,  rather  than  indirectly  through  inanimate  objects. 
Bacillus  carriers  play  a  large  role  in  spreading  the  infection.  Milk  may 
become  infected  and  transmit  the  disease.  The  diphtheria  bacillus'  is 
frail  and  soon  dies  when  dried  or  exposed  to  sunlight,  therefore  air-borne 
infection  is  probable  only  in  the  case  of  close  association,  that  is,  within  a 
few  feet  of  the  infected  person  and  within  the  radius  of  the  possibility  of 
droplet  infection. 

Experience  clearly  teaches  that  diphtheria  is  spread  mainly  by  the 
active  cases;  recent  convalescents;  mild  and  missed  cases;  and  carriers. 

The  following  description  by  Chapin  illustrates  how  diphtheria  and 
all  other  infections  contained  in  the  secretions  from  the  mouth  and  nose 
may  be  transmitted;  it  also  emphasizes  the  importance  of  education  in 
personal  hygiene  based  upon  habits  of  biological  cleanliness : 

"Not  only  is  the  saliva  made  use  of  for  a  great  variety  of  purposes, 
and  numberless  articles  are  for  one  reason  or  another  placed  in  the  mouth, 
but,  for  no  reason  whatever,  and  all  unconsciously,  the  fingers  are  with 


194     DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 

great  frequency  raised  to  the  lips  or  the  nose.  Who  can  doubt  that  if 
the  salivary  glands  secreted  i^ndigo  the  fingers  would  not  continually  be 
stained  a  deep  blue,  and  who  can  doubt  that  if  the  nasal  and  oral  secre- 
tions contain  the  germs  of  disease  these  germs  will  not  be  almost  as  con- 
stantly found  upon  the  fingers?  All  successful  commerce  is  reciprocal, 
and  in  this  universal  trade  in  human  saliva  the  fingers  not  only  bring 
foreign  secretions  to  the  mouth  of  their  owner,  but  there,  exchanging  it 
for  his  own,  distribute  the  latter  to  everything  that  the  hand  touches. 
This  happens  not  once,  but  scores  and  hundreds  of  times  during  the  day's 
round  of  the  individual.  The  cook  spreads  his  saliva  on  the  muffins  and 
rolls,  the  waitress  infects  the  glasses  and  spoons,  the  moistened  fingers  of 
the  peddler  arrange  his  fruit,  the  thumb  of  the  milkman  is  in  his 
measure,  the  reader  moistens  the  pages  of  his  book,  the  conductor  his 
transfer  tickets,  the  lady'  the  fingers  of  her  glove.  Everyone  is  busily 
engaged  in  this  distribution  of  saliva,  so  that  the  end  of  each  day  finds 
this  secretion  freely  distributed  on  the  doors,  window  sills,  furniture, 
and  playthings  in  the  home,  the  straps  of  trolley  cars,  the  rails  and  coun- 
ters and  desks  of  shops  and  public  buildings,  and,  indeed,  upon  every- 
thing that  the  hands  of  man  touch.  What  avails  it  if  the  pathogens  do 
die  quickly?  A  fresh  supply  is  furnished  each  day.  Besides  the  moisten- 
ing of  the  fingers  with  saliva  and  the  use  of  the  common  drinking  cup, 
the  mouth  is  put  to  numberless  improper  uses  which  may  result  in  the 
spread  of  infection.  It  is  used  to  hold  pins,  string,  pencils,  paper  and 
money.  The  lips  are  used  to  moisten  the  pencil,  to  point  the  thread  for 
the  needle ;  to  wet  postage  stamps  and  envelopes.  Children  'swap'  apples, 
cake,  and  lollipops,  while  men  exchange  their  pipes  and  women  their  hat- 
pins. Sometimes  the  mother  is  seen  'cleansing'  the  face  of  her  child 
with  her  saliva-moistened  handkerchief,  and  perhaps  the  visitor  is  shortly 
after  invited  to  kiss  the  little  one. 

"Childr^  have  no  instinct  of  cleanliness,  and  their  faces,  hands,  toys, 
clothing,  and  everything  that  they  touch  must  of  necessit}'  be  continually 
daubed  with  the  secretions  of  the  nose  and  mouth.  It  is  well  known  that 
children  between  the  ages  of  two  and  eight  years  are  more  susceptible  to 
scarlet  fever,  diphtheria,  measles,  and  whooping-cough  than  at  other 
ages,  and  it  may  be  that  one  reason  for  this  is  the  great  opportunity  that 
is  afforded  by  their  habits  at  these  ages  for  the  transfer  of  the  secretions. 
Infants  do  not,  of  course,  mingle  freely  with  one  another,  and  older  chil- 
dren do  not  come  in  close  contact  in  their  play,  and  they  also  begin  to 
have  a  little  idea  of  cleanliness." 

Domestic  Animals,  especially  cats,  dogs  and  horses,  have  been  sus- 
pected as  sources  of  infection,  but  the  evidence  lacks  definite  foundation 
of  fact.  Savage  ^°  recently  reexamined  the  whole  subject,  and  concluded 
that  cats  do  not  suffer  from  diphtheria.     He  failed  to  infect  young  kit- 

'^Jour.  Hygiene,  XVIII,  448,  Feb.,  1920. 


DIPHTHERIA  195 

tens  with  cultures  of  the  Klebs-I^ffler  bacillus,  and  found  that  these 
organisms  usually  disappear  within  24  hours  when  implanted  into  the 
nasal  cavity  and  upon  the  throat.  He  concludes  that  there  is  no  evi- 
dence that  cats  serve  as  carriers  of  diphtheria.  On  the  other  hand,  Major 
Simmons'^  has  isolated  virulent  diphtheria  bacilli  from  two  cats  which 
were  pets  of  a  person  who  contracted  a  fatal  diphtheritic  pharyngitis. 
It  is  quite  probable  that  domestic  animals,  especially  pets,  may  occasion- 
ally transfer  the  infection. 

Milk-borne  Diphtheria, — The  diphtheria  bacillus  grows  well  in  milk 
withoi:t  appreciably  changing  its  flavor  or  appearance.  Trask  collected 
23  diphtheria  epidemics  from  the  literature  between  1895  and  1907.  Fif- 
teen of  these  occurred  in  the  United  States  and  8  in  Great  Britain. 
The  milk  is  usually  contaminated  by  cases  of  the  disease  occurring  on  the 
farm  or  at  the  dairy  or  milk  shop.  In  some  cases  the  diseased  person 
milks  the  cows  or  the  same  person  nurses  the  sick  and  handles  the  milk. 
In  two  instances  the  outbreak  w'as  supposed  to  be  due  to  disease  of  the 
cow.  One  instance  studied  by  Dean  and  Todd  is  instructive.  In  certain 
families  supplied  with  milk  from  two  cows  there  occurred  two  cases  of 
clinically  typical  .diphtheria  and  three  of  sore  throat,  whereas  in  another 
family  using  the  milk,  only  after  sterilization,  no  case  occurred.  One 
of  the  cows  had  mammitis  and  furnished  a  scanty,  ropy,  semi-purulent, 
and  slightly  blood-tinged  milk.  The  Klebs-Loffler  bacilli  were  isolated  in 
all  cases  and  also  from  the  milk  of  the  cow  with  mammitis.  Experiments 
justified  the  conclusion  that  the  ulcers  upon  the  udder  of  the  cow  with 
mammitis  had  become  secondarily  infected  with  B.  dipliilieriae,  acci- 
dentally from  some  apparently  healthy  person.  Usually,  however,  the 
milk  is  infected  directly  from  a  case  or  carrier. 

The  diphtheria  bacillus  is  not  killed  by  freezing.  An  outbreak  at 
Newport,  E.  I.,  and  vicinity,  due  to  ice  cream,  was  reported  by  McCoy, 
Bolton  and  Bernstein. -- 

Bacillus  Carriers. — It  was  in  the  case  of  diphtheria  that  the  danger 
of  bacillus  carriers  was  first  realized.  It  is  now  known  that  persons  who 
come  in  contact  with  diphtheria  patients  are  very  apt  to  harbor  diph- 
theria bacilli,  though  they  may  remain  in  good  health.  It  is  also  now 
well  known  that  a  certain  percentage  of  the  population  at  large  harbor 
the  diphtheria  bacilli  in  their  nose  or  throat,  even  though  they  have  had 
no  known  association  with  the  disease.  Graham-Smith  found  that  &Q> 
per  cent,  of  the  members  of  the  family  to  which  the  diseased  person 
belonged  were  infected  ;  the  proportion  being  higher  (100  to  50  per  cent.) 
in  families  in  which  no  precautions  were  taken  to  isolate  the  sick,  and 
much  lower  (10  per  cent.)  when  such  precautions  were  taken.  Of  the 
more  distant  relatives  examined,  29  per  cent,  were  found  to  be  carriers. 

"Am.  Jour.  Med.  Sc,  CLX,  589.  Oct..  1920. 

^Public  Health  Reports,  Vol.  XXXII,  No.  43,  Oct.  26,  1917. 


196     DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 

Bacilli  were  found  in  37  per  cent,  of  persons  in  attendance  on  the  sick. 
Observations  of  the  inmates  of  hospital  wards  and  institutions  showed 
that  14  per  cent,  are  likely  to  give  positive  cultures  when  diphtheria 
occurs  among  them.  In  infected  schools  8.7  per  cent,  of  the  pupils 
were  found  to  be  bacillus  carriers.  In  Xew  York,  Scholley  examined 
1,000  children  from  the  tenement  districts,  and  found  18  with  virulent 
and  38  with  non-virulent  bacilli.  Moss,  Guthrie  and  Gelien  found  B. 
diphtheriae  in  3.61  per  cent,  of  1,217  school  children  in  Baltimore,  and 
3.48  per  cent,  of  1,290  individuals  in  the  city  at  large.  Only  18  per  cent, 
of  the  positive  cultures  were  virulent.  Goldberger  and  Williams  exam- 
ined 4,093  healthy  persons  in  Detroit  in  1914  and  found  0.928  per  cent, 
to  harbor  morphological  typical  bacilli,  and  0.097  per  cent,  to  be  carriers 
of  virulent  bacilli.  Diphtheria  was  unduly  prevalent  at  the  time.  Slack, 
Arms,  Wade,  and  Blanchard  took  cultures  at  the  beginning  of  the  school 
year  from  about  4,500  pupils  in  the  Brighton  district,  Boston.  Diph- 
theria was  not  prevailing  at  the  time.  Nevertheless,  at  least  1  per  cent, 
of  all  these  healthy  school  children  were  found  to  carry  morphological 
typical  diphtheria  bacilli.  It  is  estimated  that  this  is  the  average  ratio 
in  the  population  at  large. 

The  virulent  and  the  non-virulent  strains  of  the  diphtheria  bacillus 
remain  true  to  type.  All  attempts  to  exalt  the  pathogenicity  of  the  aviru- 
lent  strains  by  passage  through  animals  have  failed.  The  avirulent  diph- 
theria bacilli  do  not  produce  toxin,  do  not  kill  guinea-pigs,  and  do  not 
produce  antitoxin;  the  virulent  and  avirulent  strains  look  alike  under 
the  microscope.  The  virulent  strain  can  therefore  only  be  distinguished 
by  animal  tests. 

Diphtheria  bacilli  from  patients  with  diphtheria  and  from  carriers 
who  have  been  in  contact  with  such  patients  are  practically  always  viru- 
lent. Diphtheria  is  kept  alive  by  these  virulent  strains  in  immune  per- 
sons. Carriers  with  the  avirulent  strain  may  be  disregarded.  None  of  the 
children  in  the  Brighton  district  above  mentioned  had  any  known  asso- 
ciation with  the  disease,  nor  did  they  afterward  develop  diphtheria.  The 
danger  of  such  carriers  is  nil.  The  dangerous  carrier  is  he  who  harbors 
the  virulent  strain^  and  this  is  usually  ohtained  from  the  patient,  conva^ 
lescent,  or  from  a  third  person  who  has  come  in  contact  with  the  patient. 

The  virulent  bacilli  may  be  differentiated  from  the. avirulent  strains 
by  injecting  pure  cultures  into  guinea-pigs.  Zingher  and  Soletsky  ^^  have 
improved  Neisser's  method  by  using  2  guinea-pigs  for  the  testing  of  from 
4  to  6  different  strains.  One  guinea-pig  serves  as  a  control  and  receives 
about  200  units  of  antitoxin  intracardially  at  the  time  of  making  the  test, 
or  intraperitoneally  24  hours  before.  Both  pigs  are  injected  with  sus- 
pensions of  the  cultures  to  be  tested  intracutaneously.     A  fresh  24-hour 

^  Zingher  and  Soletskv:  Proceedings  of  the  Xew  York  Pathological  Society, 
N.  S.,  Voh  XV,  Xos.  1  and  2,  January  and  February,  191.5. 


DIPHTHERIA  107 

irrowtli  from  an  ordinary  LfiHlcr  slant  is  suspended  in  •^5  to  ;U)  c.  c.  of 
normal  salt  solution;  0.1  c.  c.  is  injected  into  the  skin.  The  results  of 
tlip  tests  are  noted  in  24  to  48  hours.  Virulent  strains  produce  a  definite 
local  inflammatory  lesion,  which  shows  a  superficial  necrosis  in  48  to  72 
hours.  In  the  control  pig  the  skin  remains  normal.  With  non-virulent 
strains  no  lesions  will  be  found  in  either  control  or  test  animal.  It  is 
plain  that  the  control  of  diphtheria  outbreaks  in  institutions,  camps, 
on  shipboard,  schools,  and  in  similar  places,  where  a  number  of  people 
are  crowded  together,  as  well  as  the  final  control  of  the  disease  in  cities 
and  towns,  depends  eventually  upon  the  recognition  of  true  carriers  and 
their  isolation. 

Diphtheria  bacilli  disappear  in  about  50  per  cent,  of  cases  by  the  time 
the  local  membrane  has  disappeared.  The  bacilli  persist  in  about  5  per 
cent,  of  persons  at  the  end  of  two  months,  about  2  per  cent,  at  the  end 
of  3  months,  and  approximately  1  per  cent,  continue  as  chronic  bacillus 
carriers.    The  virulence  is  not  lessened  during  the  carrier  condition. 

It  is  important  to  remember  that  diphtheria  bacilli  may  be  either 
in  the  nose  or  throat  or  both.  It  is  therefore  essential  to  take  nose  as 
well  as  throat  cultures  in  searching  for  carriers.  Two,  three  or  more 
examinations  may  be  necessar}'  to  discover  all  the  carriers. 

Many  methods  have  been  used  to  cure  diphtheria  carriers.  These 
consist  of  liquid  antiseptics  applied  as  swabs,  sprays  or  gargles;  the 
inhalation  of  antiseptic  vapors ;  the  use  of  diphtheria  vaccine,  toxin,  anti- 
toxin, and  antibacillary  serum;  also  toxins  of  the  Bacillus  pyocyaneus; 
and  the  introduction  of  cultures  of  staphylococci,  yeast  and  other  micro- 
organisms. Hektoen  and  Rappaport  ^*  suggested  the  use  of  kaolin. 
Good  results  have  sometimes  followed  but  mostly  failed  in  all  the 
methods  so  far  tried. 

The  diphtheria  bacilli  probably  do  not  long  persist  upon  normal 
mucous  membranes,  but  continue  in  pockets,  folds,  crypts  of  the  tonsils, 
fissures  of  adenoids,  spaces  about  the  turbinates,  the  sinuses  connected 
with  the  nasal  cavity,  and  in  any  irritated,  inflamed  or  ulcerated  portion 
of  the  mucous  membrane.  Therefore,  the  removal  of  enlarged  tonsils, 
polypi,  foreign  bodies,  and  other  sources  of  irritation  and  inflammation 
has  resulted  in  the  cure  of  diphtheria  carriers.  The  first  indication  is 
to  treat  the  mucous  membrane  of  the  upper  respiratory  passages  so  as  to 
get  it  in  a  normal  condition. 

The  disappearance  of  the  bacilli  from  the  throat  and  nose  cannot  be 
hastened  by  the  usual  injections  of  antitoxin.  Diphtheria  antitoxin  neu- 
tralizes the  toxin,  but  does  not  harm  the  bacilli.  A  serum  containing 
agglutinins  has  been  used.  This  serum  in  powdered  form  is  blown  into 
the  throat.  The  diphtheria  bacilli  are  supposedly  agglutinated  and  may 
then  be  more  readily  washed  away  by  gargling  and  douching.     A  sub- 

'^Jour.  A.  M.  A.,  LXIV.  24.  June  12.   1915    n.   1901. 


198     DISEASES  FROM  DISCHARGES  OF  MOXJTH  AND  NOSE 

stance  proposed  by  Emmerich  known  as  "pyocyanase"  has  been  used. 
This  contains  a  fefment  from  bouillon  cultures  of  the  Bacillus  pyocy- 
aneus.    It  is  applied  locally  and  acts  by  its  power  of  bacteriolysis. 

Encouraging  results  have  been  reported  by  "over-riding"  the  throats 
of  diphtheria  carriers  with  suspensions  of  Staphylococcus  pyogenes 
aureus,  which  are  sprayed  into  the  throat  and  nose.  The  method  was 
introduced  by  Schiotz,  in  1909,  who  reported  the  prompt  disappearance 
of  diphtheria  bacilli  in  six  carriers.  Page,  also  Catlin,  Scott  and  Day, 
Lorenz  and  Ravenel,  and  others,  have  reported  successful  results. 

Hewlett  and  Nankivell,  and  also  Petruschky,  report  encouraging 
results  in  clearing  up  diphtheria  carriers  by  the  subcutaneous  injection 
of  a  diphtheria  vaccine. 

We  must  acknowledge  that  all  these  measures  often  fail.  The  relief  of 
bacillus  carriers  is  one  of  the  unsolved  problems  in  preventive  medicine. 

DiagTiosis.^The  diagnosis  of  diphtheria  often  rests  upon  a  com- 
bination of  clinical  symptoms  and  laboratory  findings.  Positive  cultures 
alone  do  not  necessarily  mean  clinical  diphtheria,  even  though  sore 
throat  and  fever  are  present.  Cases  of  streptococcal  tonsillitis,  with 
follicular  patches  resembling  false  membrane,  occur  in  diphtheria  bacil- 
lus.  carriers.  Such  persons  give  negative  Schick  reactions,  and  do  not 
have  clinical  diphtheria,  despite  the  positive  findings  in  cultures  taken 
from  their  throats.  It  is  important  to  remember  that  the  diagnosis  of 
clinical  diphtheria  cannot  be  made  in  the  laboratory  as  a  result  of 
finding  virulent  diphtheria  bacilli  in  cultures.  Diphtheria  often  begins 
msidiously,  and  valuable  time  is  lost  in  waiting  for  false  membrane  or 
other  symptoms;  cultures  should  be  taken  of  all  sore  throats  in  order 
to  exclude  or  confirm  diphtheria. 

On  the  other  hand,  negative  cultures  are  significant  in  excluding 
diphtheria,  provided  the  material  is  taken  from  the  proper  place  and 
good  technic  is  used. 

Always  give  antitoxin  in  a  clinical  case  of  diphtheria  at  once,  with- 
out waiting  for  laboratory  confirmation  of  the  diagnosis.  No  harm 
will  be  done  and  lives  will  be  saved  by  this  rule,  for  time  is  the  important 
element  in  the  life-saving  properties  of  antitoxin.  In  mild  cases,  sub- 
cutaneous or  intramuscular  injection  may  be  used,  but  in  severe  cases 
intravenous  injection  is  called  for. 

Resistance. — The  diphtheria  bacillus  has  less  resistance  to  adverse 
conditions  than  the  majority  of  the  spore-free  bacteria.  It  is  more  read- 
ily destroyed  by  light,  heat,  and  disinfecting  substances  than  the  typhoid 
bacillus.  In  this  regard  it  corresponds  more  to  the  frailer  streptococci. 
Under  certain  circumstances  the  diphtheria  bacillus  resists  drying  for  a 
long  time.  When  enclosed  in  the  false  membrane  or  other  albuminous 
substances,  they  may  remain  virulent  for  some  months.  It  is  not  killed 
by  freezing. 


DIPHTHERIA 


199 


IMMiWirV 

Immunity  to  diphtheria  is  mainly  an  antitoxic  immunity  and  per- 
sists a  variable  time.  Second  attacks  sometimes  occur  witiiin  a  few 
weeks  while  the  patient  is  still  in  the  hospital.  Keiche  "  states  that 
5.8  per  cent,  of  4,761  cases  of  diphtheria  in  Hamburg  were  known  to 
have  had  a  previous  attack,  lie  presents  further  data  to  confirm 
the  absence  of  any  lasting  immunization  by  a  single  attack  of  diphtheria. 
A  positive  Schick  reaction  may  be  obtained  in  children  who  have  re- 
covered from  the  disease.  Graef  and  Ginsberg  ^^  have  shown  by  the 
Schick  reaction  that  immunity  obtained  by  an  attack  of  the  disease  lasts 
from  a  month  to  several  years,  varying  greatly  in  different  individuals, 
and  being  very  brief  in  children.  The  fact  that  healthy  persons  may 
harbor  virulent  bacilli  upon  their  mucous  membrane  for  a  long  time 
without  contracting  the  disease  shows  the  high  grade  immunity  enjoyed 
by  many  individuals,  due  to  antitoxin  constantly  in  the  blood.  Persons 
vary  markedly  in  susceptibility.  During  the  first  few  months  of  life 
there  is  a  very  high  grade  immunity.  Antitoxin  is  transmitted  to  the 
fetus  through  the  placental  circulation  and  to  the  infant  in  the  mother's 
milk.  This  immunity  during  the  early  months  of  life  is  passive  and 
soon  wears  off,  so  that  by  the  end  of  two  years  70  per  cent,  are  sus- 
ceptible. After  this  period,  children  begin  to  manufacture  their  own 
diphtheria  antitoxin,  so  that  the  percentage  of  susceptible  children 
gradually  decreases  until  the  twentieth  year,  when  only  12  per  cent. 
give  a  positive  Schick  reaction;  in  other  words,  88  per  cent,  of  the 
adult  population  are  immune  to  diphtheria. 

As  a  result  of  extensive  studies  by  means  of  the  Schick  test  con- 
ducted under  the  direction  of  Dr.  W.  H.  Park,  it  has  been  found  that 
susceptibility  to  diphtheria  is  present  in  about  the  following  proportions : 


Age 


Under  3  months .  . . 

3  to  6  months 

6  months  to  1  year. 

1  to  2  years 

2  to  3  years 

3  to  5  years 

5  to  10  years 

10  to  20  years 

Over  20  years 


Per  Cent. 

Per  Cent. 

Susceptible 

Immune 

Positive 

Xegative 

Schick  Ke- 

Schick  Re 

action 

action 

15 

85 

30 

70 

60 

40 

70 

30 

60 

40 

40 

60 

30 

70 

20 

80 

12 

88 

*'Reiche,  F.:    Reinfection  with  Diphtheria.     Med.  Klin,,  Berlin,  Oct.  12,  IX, 
No.  41,  pp.  1663-1708. 

'^jQur.  A.  M.  A.,  LXIV,  1915,  p.   1205, 


200     DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 

The  curve  of  these  figures  corresponds  closely  to  the  age  incidence 
of  the  disease. 

Passive  Immunity. — This  can  be  induced  by  injecting  antitoxin.  The 
usual  immunizing  dose  is  1,000  to  1,500  units  for  adults  and  750  to  1,000 
units  for  children.  The  protection  thus  afforded  disappears  in  3  to  8 
weeks.  A  second  injection  of  antitoxin  renews  the  immunity,  which, 
however,  lasts  a  still  shorter  time.  Passive  immunity,  while  occasionally 
of  great  practical  service  in  individual  prophylaxis,  cannot  be  depended 
upon  to  control  epidemics. 

The  great  advantage  of  passive  immunity  is  that  it  is  prompt;  the 
disadvantages  are  that  it  lasts  a  brief  time,  produces  serum  reactions, 
and  is  relatively  much  more  expensive  than  active  immunity. 

Active  Immunity. — This  can  be  induced  by  injecting  a  mixture  of 
toxin  and  antitoxin. ^^  The  toxin  and  antitoxin  are  mixed  so  that  the 
toxin  is  not  quite  neutralized;  in  other  words,  there  is  some  free 
poison  in  the  mixture.  This  is  accomplished  by  adding  about  86  per 
cent,  of  an  L+  dose  of  toxin  to  each  unit  of  antitoxin.  Such  a  mixture 
contains  free  toxon,  but  no  uncombined  toxin.  Five  c.  c.  of  this  mixture 
injected  into  guinea-pigs  does  not  produce  acute  symptoms  of  toxic  ir- 
ritation and  poisoning,  the  result  of  toxin,  but  causes  late  paralysis, 
which  begins  about  the  10th  day,  the  result  of  toxon.  The  mixture  is 
diluted  so  that  three  units  of  antitoxin  and  about  3  L+  doses  of  toxin 
are  contained  in  each  c.  c. 

The  dose  of  toxin-antitoxin  mixture  is  1  c.  c.  subcutaneously,  re- 
peated every  week,  until  three  injections  are  given.  Children  react 
less  than  adults  and  therefore  can  be  given  a  full  dose.^®  The  immunity 
appears  slowly,  sometimes  in  eight  to  twelve  weeks,  but  once  established 
seems  lasting.  Park  finds  that  children  immunized  five  years  ago  still 
have  antitoxin  in  their  blood  as  demonstrated  by  negative  Schick  reac- 
tions. One  injection  will  immunize  about  60  per  cent.,  two  injections 
about  80  per  cent.,  and  three  injections  from  90  to  99  per  cent.  A  small 
percentage  of  persons  will  show  a  positive  Schick  reaction  at  the  end  of 
three  months,  after  three  injections  of  the  toxin-antitoxin  mixture.  Such 
persons  may  be  given  two  or  three  more  injections  and  in  this  way  an 
active  immunity  may  be  developed  in  almost  all  susceptible  persons. 

An  immunizing  dose  of  antitoxin  interferes  with  the  production  of 
an  active  immunity  with  toxin-antitoxin  mixtures.  In  other  words,  an 
overneutralized  toxin  interferes  with  the  stimulation  of  antibody  forma- 
tion. 

By  actively  immunizing  all  children  under  18  months  and  only  those 
children  over  18  months  who  give  a  positive  Schick  reaction,  we  can 

"  This  method  was  suggested  by  Theobold  Smith,  but  first  attempted  by 
Behring  in  1912.  It  has  lieen  studied  especially  by  Park  and  Zingher  of  the 
New  York  City  Department  cf  Health. 

^  Infants  do  not  rea^ct  at  all  and  may  be  given  1.5  c.  c, 


iJli'liTliEiUA  2U1 

render  the  child  population  immune  to  diphtheria,  and  tide  it  over  the 
period  ol"  greatest  susceptibility.  It  sliould  bo  remembered  that  in  adult 
life  the  great  majority  (88  to  90  and  even  95  per  cent.)  are  naturally 
immune.     The  percentage  is  higher  in  urban  than  rural  districts. 

The  advantages  of  active  immunity,  produced  by  injecting  toxin- 
antitoxin  mixture  are  that  it  is  lasting,  cheap  and  simple,  and  the 
reactions  are  slight.  Its  only  disadvantage  is  that  it  takes  several  weeks 
or  months  to  ap])ear. 

The  Schick  Reaction. — The  presence  or  absence  of  immunity  in  any 
individual  nuiy  readily  be  determined  by  the  Schick  test,  which  tells 
whether  antitoxin  is  present  or  absent  in  the  blood  of  that  individual. 
The  Schick  reaction  is  made  by  injecting  a  small  amount  of  diphtheria 
toxin  into  the  skin.  The  precise  quantity  used  is  l/50th  of  a  min- 
imum lethal  dose  of  diphtheria  toxin  for  a  250-gram  guinea-pig.  This 
amount  of  toxin  is  diluted  so  that  it  is  contained  in  0.1  or  better  0.2  c.  c. 
of  salt  solution.  The  injection  must  be  made  into  and  not  under  the 
skin.  A  positive  reaction  at  the  site  of  the  injection  means  absence  of 
antitoxin,  that  is^  a  susceptible  individual.  A  negative  reaction  means 
the  presence  of  antitoxin,  hence  immunity. 

A  positive  reaction  is  indicated  by  redness  at  the  site  of  injection 
which  appears  gradually  and  becomes  distinct  in  24  to  48  hours,  reaching 
its  height  on  the  third  or  fourth  day.  The  reaction  then  consists  of  a 
circumscribed  area  of  redness  and  slight  infiltration,  about  one  to  two 
centimeters  in  diameter.  The  degree  of  redness  and  infiltration  varies 
with  the  relative  susceptibility  of  the  individual.  The  reaction  slowly 
disappears  leaving  a  definite  circumscribed  scaling  area  of  brownish  pig- 
mentation, which  persists  three  to  six  weeks.  A  positive  reaction  repre- 
sents the  effect  of  an  irritating  toxin  upon  tissue  cells  that  are  not  pro- 
tected by  antitoxin.  The  reaction  is  sufficiently  delicate  to  indicate  less 
than  1/3 0th  of  a  unit  of  antitoxin  in  each  cubic  centimeter  of  blood 
serum.     Such  persons  are  susceptible  to  diphtheria. 

The  intensity  of  the  reaction  varies.  A  well-marked  redness  indi- 
cates an  almost  complete  absence  of  antitoxin.  Faint  reactions  point  to 
the  presence  of  very  small  amounts  of  antitoxin.  All  gradations  are 
observed. 

In  a  negative  reaction,  the  skin  at  the  site  of  injection  remains 
normal.  The  toxin  is  neutralized  by  the  antitoxin,  and  therefore  causes 
no  irritation.  Such  persons  are  immune  and  need  not  fear  diphtheria.  A 
negative  reaction  in  a  child  that  has  reached  the  age  of  three  years  indi- 
cates an  immunity  that  is  probably  permanent.  Xo  instance  has  yet  been 
reported  of  an  individual  with  a  negative  reaction  contracting  diphtheria, 
even  though  exposed  to  the  disease,  or  after  becoming  carriers  of  viru- 
lent diphtheria  bacilli. 

A  pseudoreaction  represents  a  local  anaphylactic  response  to   pro- 


202     DISEASES  FEOM  DISCHARGES  OF  MOUTH  AITD  NOSE 

teins  in  the  material  injected.  This  reaction  is  urticarial,  appears  within 
6  to  18  hours,  reaches  its  height  in  36  to  48  hours',  and  disappears  on 
the  third  or  fourth  day,  when  the  true  reaction  is  at  its  height.  Control 
tests  should  therefore  always  be  made. 

Pseudoreactions  occur  only  in  older  children  and  adults,  not  in  in- 
fants. Comhified  reactions  also  occur,  that  is  pseudo  and  true  at  the 
same  time.  The  rule  is  to  retest  all  doubtful  cases  or  to  play  on  the 
side  of  safety  by  considering  them  positive  reactions. 

Control  tests  consist  in  injecting  toxin  heated  to  75°  C.  for  five 
minutes.  The  reaction  at  the  site  of  the  control  will  help  interpret  the 
reaction  at  the  site  of  the  test  injection.  The  accuracy  of  the  Schick 
test  depends  upon  the  strength  of  the  toxin,  the  technic  of  the  test,  and 
the  interpretation  of  the  reaction. 

We  therefore  possess  a  ready  method  of  determining  who  is  sus- 
ceptible and  who  is  naturally  immune.  Persons  who  react  negatively  to 
the  Schick  test  will  not  develop  diphtheria.  Therefore  when  an  epidemic 
breaks  out,  such  persons  need  not  be  treated  with  prophylactic  doses  of 
diphtheria  antitoxin. 

The  Schick  test  shows  a  striking  similarity  in  reactions  in  fam- 
ilies. If  the  youngest  child  of  a  family  has  a  negative  reaction  all  the 
older  children  are  likely  to  be  negative,  and  if  the  older  children  are 
positive  the  young  ones  are  also.  When  variations  are  found,  the  younger 
children  show  the  positive  reaction  (Park).  The  Schick  reaction  may 
be  used  to  differentiate  between  clinically  doubtful  cases  of  diphtheria, 
in  experimental  work,  and  in  the  handling  of  diphtheria  epidemics  in 
institutions,  etc.,  and  it  is  particularly  applicable  as  a  preliminary 
measure  for  all  persons  who  have  been  exposed  to  diphtheria. 

THE  CONTROL  OF  OUTBREAKS 

Diphtheria  frequently  appears  in  asylums,  hospitals,  camps,  jails, 
on  shipboard,  and  similar  places.  Under  these  conditions  of  crowding, 
the  disease  has  a  highly  contagious  tendency.  It  may,  however,  be 
controlled  with  every  assurance  of  success  by  the  application  of  well- 
tried  measures. 

The  most  important  measure  to  suppress  diphtheria  is  to  isolate  all 
eases  and  all  carriers.  This  is  easier  to  do  in  an  institution,  or  limited 
compound  than  in  the  population  at  large.  The  isolation  of  both  cases 
and  carriers  is  the  first  of  our  preventive  measures.  The  most  radical  is 
the  active  immunization  of  all  susceptible  individuals  with  toxin-anti- 
toxin mixture. 

The  following  measures  are  recommended  for  the  control  of  an 
outbreak: — (1)  The  recognition  and  quarantining  of  cases;  (2)  the 
finding  and  isolation  of  carriers;  (3)  the  discovery  of  the  susceptible  by 


DIPHTHERIA  203 

means  of  the  Schick  test;  (4)  active  immunization  of  all  susceptible 
persons;  (5)  inspection  of  all  susceptible  persons  every  12  or  24  hours, 
and  the  use  of  antitoxin  upon  the  first  appearance  of  s5'mptoms;  (6) 
disinfection,  laboratory  facilities,  skilled  epidemiologists,  and  other 
administrative  measures. 

Recognition  and  Quarantining  of  Cases. — These  are  the  immediate 
demands.  It  should  be  remembered  that  diphtheria  often  comes  on 
insidiously  and  that  the  patient  may  have  his  throat  plastered  with  false 
membrane  of  three  or  four  days'  standing  before  feeling  ill  enough  to 
attract  attention.  Early  recognition  of  the  disease  is  important  both  for 
successful  treatment  and  prevention.  In  all  endemic  centers  the  exami- 
nation of  the  throat,  especially  of  children,  should  be  made  a  routine 
procedure  by  practicing  physicians.  In  outbreaks  a  daily  inspection 
and  taking  of  temperatures  morning  and  evening  will  detect  cases 
early. 

In  hospitals,  cases  may  be  isolated  in  cubicles,  or  separated  by  sheets. 
Gauze  masks  may  also  be  used.  Careful  nursing  technic  is  essential 
to  prevent  cross  infections. 

Convalescents  should  not  be  released  from  quarantine  until  at  least 
two  cultures  taken  from  both  the  nose  and  throat  are  negative. 

Finding  and  Isolating  Carriers. — Throat  and  nose  cultures  from  all 
exposed  persons  and  from  all  persons  in  an  institutional  epidemic  should 
be  made.  All  positive  carriers  based  upon  morphologic  diagnosis  should 
be  isolated.  At  a  later  date,  when  time  permits,  the  carriers  of  avirulent 
bacilli  may  be  released.  It  is  sometimes  necessary  to  go  through  a  camp 
or  school  twice,  thrice^,  or  oftener  to  detect  all  the  carriers,  or  to  discover 
new  ones. 

While  it  is  practical  to  isolate  all  the  carriers  in  a  limited  outbreak, 
such  as  a  camp,  ship,  or  asylum,  this  is  not  always  feasible  in  the  commu- 
nity' at  large.  Yet  most  of  the  dangerous  carriers  even  in  a  metropolitan 
city  can  be  discovered  by  taking  cultures  from  all  persons  closely  asso- 
ciated with  cases. 

The  bacilli  frequently  grow  in  the  mucous  membrane  of  the  nose  and 
nasal  pharviix  without  anything  to  indicate  their  localization.  Unless 
cultures  are  taken  from  the  nose,  many  carriers  wiU  be  overlooked,  leav- 
ing a  large  loophole  in  our  preventive  measures.  Ward  and  Henderson, 
in  a  public  school  epidemic  in  Berkeley  in  1907,  found  that  all  attempts 
to  isolate  infected  children  had  no  effect  on  the  epidemic  so  long  as  they 
made  throat  cultures  alone.  When  they  took  both  nose  and  throat  cul- 
tures and  quarantined  all  the  children  showing  positive  cultures,  the 
epidemic  stopped. 

Good  results  can  be  obtained  only  where  care  is  exercised  in  obtain- 
ing the  material  and  skill  used  in  the  technic  of  the  bacteriological 
examination. 


204     DISEASES  FEOM  DISCHARGES  OF  MOUTH  AND  NOSE 

Diphtheria  bacilli  sometimes  leave  the  body  in  the  discharges  from 
middle  ear  disease,  and  occasionally  also  from  infected  wounds. 

Schick  Reaction. — As  soon  as  practical,  all  those  exposed  to  the 
infection,  whether  in  a  family  or  in  an  epidemic  focus,  should  be  tested 
for  immunity  by  the  Schick  test.  In  an  institution,  both  the  inmates 
and  the  administrative  force  should  be  tested.  ISTo  special  concern, 
need  be  given  those  who  react  negatively,  for  they  are  immune  and  will 
not  contract  the  disease.  Such  persons,  however,  may  be  carriers  of 
virulent  strains,  in  which  case  they  should  be  isolated. 

Active  Immunization. — All  those  who  show  a  positive  Shick  re- 
action should  at  once  be  given  the  toxin-antitoxin  mixtures.  Three  suc- 
cessive injections  of  1  c.  c.  at  intervals  of  a  week  are  given.  The 
immunity  comes  on  slowly  (2  to  12  weeks).  Such  individuals  should 
therefore  be  carefully  inspected  every  day,  so  that  the  first  indications 
of  infection  may  be  met  with  an  injection  of  antitoxin.  Under  this 
system,  cases  of  the  "disease  may  arise  during  the  time  it  takes  these 
persons  to  develop  an  active  immunity,  but  with  the  timely  use  of  anti- 
toxin no  deaths  will  occur. 

This  is  the  most  effective  method  of  eradicating  diphtheria,  both  in 
endemic  centers  as  well  as  in  epidemic  foci.  The  results  obtained  are 
permanent.  It  requires  time,  and  very  careful  supervision  of  all  the 
details,  with  a  corps  of  skilled  and  trained  technicians,  to  carry  it  out 
successfully. 

An  immunizing  dose  of  antitoxin  should  not  be  used  to  tide  over 
the  interval  it  takes  for  toxin-antitoxin  immunity  to  become  established, 
because  this  interferes  with  the  production  of  active  immunity.  In 
other  words,  the  methods  of  active  and  passive  immunization  should  not 
be  used  at  the  same  time. 

For  the  population  at  large,  the  best  time  to  test  susceptibility  with 
the  Schick  reaction  is  between  6  months  and  2  years.  At  this  time  of 
life,  the  percentage  of  positive  Schick  reactions  is  largest,  and  the  sus- 
ceptibility to  diphtheria  as  well  as  the  mortality  from  the  disease  is 
greatest.  All  those  showing  positive  reactions  at  this  period  should  be 
immunized  with  the  mixture  (see  page  200).  Very  young  infants  do  not 
react  at  all  to  the  toxin-antitoxin  injections,  and  Park  proposes  to  im- 
munize all  at  this  period  of  life,  without  a  Schick  test. 

Zingher  ^®  recommends  the  following  procedures  for  the  protection 
of  children: — (1)  All  children  over  18  months  of  age  in  the  entire  com- 
munity should  have  their  susceptibility  to  diphtheria  determined  by 
means  of  the  Schick  test,  and  the  reaction  which  they  show  should  be 
noted  either  in  institutional  records  or  in  the  records  of  the  family 
physician.  (2)  In  infants  below  18  months  of  age,  the  Schick  test  is 
not  necessary  because  a  negative  reaction  may  give  rise  to  a  false  sense 

*»  Reprint  No.  72,  Dept.  of  Health,  New  York  City,  Nov.,  1918. 


DIPHTHRRIA  205 

of  security.  Very  young  infants  may  exhibit  a  negative  Schick  test 
owing  to  the  immunity  passively  acquired  from  the  mother,  but  inas- 
much as  this  type  of  immunity  is  transient,  it  is  safer  to  assume -that 
no  child  under  18  months  possesses  permanent  immunity.  (3)  All 
infants  below  IS  months  of  age  accordingly  should  be  actively  im- 
munized M'ith  three  doses  of  1  c.  c'.  each  of  di{)hthcria  toxin-antitoxin 
mixture,  irrespective  of  the  reaction  to  the  Schick  test  which  the  infant 
might  show  at  the  time  of  immunization.  (4)  All  children  over  18 
months  of  age  who  give  a  positive  Schick  test  should  be  immunized  by 
receiving  three  subcutaneous  injections  of  1  c.  c.  each  of  toxin-antitoxin 
at  intervals  of  7  days.  (5)  All  children  immunized  by  this  method 
should  be  retested  three  months  after  the  last  injection  and  reimmunized 
if  they  should  by  any  chance  still  give  a  positive  Schick  reaction. 

Passive  Immunization. — This  consists  in  injecting  diphtheria  anti- 
toxin. The  customary  immunizing  dose  is  1000  units.  Schick  recom- 
mends 50  units  per  kilogram  of  body  weight.  The  protection  wears  off 
in  3  to  8  weeks,  but  fhe  immunizing  dose  can  be  repeated  every  2  or  3 
weeks  until  the  danger  is  passed. 

Antitoxic  immunity  cannot  be  depended  upon  to  stamp  out  the  infec- 
tion. It  has  several  disadvantages  that  should  not  be  disregarded.  The 
bacilli  remain  in  the  throats  of  those  immunized  and  the  disease  con- 
tinues to  crop  out  from  time  to  time  as  the  antitoxin  disappears. 
Where  large  numbers  are  involved  the  method  is  very  expensive,  time- 
consuming,  and  the  resulting  serum  reactions  often  disturbing,  especially 
where  repeated  immunization  is  called  for,  A  blind  reliance  upon  anti- 
toxic immunity  has  proved  disappointing  and  futile  in  many  institu- 
tional outbreaks.  In  the  end,  the  active  immunity  induced  by  toxin-anti- 
toxin mixtures  does  not  take  much  more  time  and  is  much  more  certain. 

Antitoxic  immunity  has  a  distinct  place  in  personal  prophylaxis  and 
in  selected  individual  cases,  especially  in  family  practice,  but  will  grad- 
ually be  replaced  with  active  immunization. 

Disinfection. — Disinfection  has  a  place  in  controlling  the  spread  of 
the  infection.  The  discharges  from  the  patient  should  be  burned.  All 
fabrics,  bed  and  body  linen,  that  have  come  in  contact  with  the  discharges 
from  the  mouth  and  nose,  and  all  objects  such  as  spoons,  cups,  ther- 
mometers, toys,  etc.,  that  have  been  mouthed  should  be  boiled,  steamed 
or  soaked  in  one  of  the  standard  germicidal  solutions.  The  hands  of  the 
nurse  need  attention  and  proper  nursing  technic  should  be  carried  out. 

Terminal  fumigation  is  of  little  avail.  A  special  cleansing  and 
disinfection  of  floors,  waUs,  door  knobs,  bed  frames,  and  other  surfaces 
that  have  been  contaminated  will  sufhce.  The  germicidal  solutions  avail- 
able are  bichlorid  of  mercury,  1  to  1000;  carbolic  acid,  2.5  per  cent.; 
formalin,  10  per  cent.;  or  liquor  cresolis  compositus,  1  per  cent.  They 
should  be  used  hot 


206     DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 

Administrative  Measures. — Diphtheria  requires  a  well  trained  force 
familiar  with  the  modern  prohlem  and  skilled  in  the  technical-  sides  of 
diagnosis  and  the  Schick  reaction.  Laboratory  facilities  are  indis- 
pensable. With  an  adequate  force,  including  an  experienced  epidemiolo- 
gist, diphtheria  should  never  get  out  of  hand  in  any  community,  and 
epidemics  should  be  promptly  controlled.  Education  of  the  public  and 
profession  is  part  of  the  program.  Personal  hygiene  and  sanitary  habits 
must  be  taught  and  encouraged.  Care  should  be  taken  that  the  infec- 
tion is  not  spread  by  tableware,  handkerchiefs,  wash  bowls,  and  articles 
in  common  use.  Better  sanitary  control  over  restaurants  and  soda  water 
fountains  should  be  maintained.  All  table  ware  should  be  scalded  be- 
fore it  is  again  used.  Sanitary  habits  regarding  "hand  to  mouth  infec- 
tion" and  measures  to  "screen  the  sneeze"  need  emphasis  in  nursery, 
schools  and  workshops. 

In  almost  all  communities  diphtheria  is  now  one  of  the  diseases 
which  must  be  reported  to  the  health  authorities.  The  houses  are 
placarded  and  the  cases  isolated.  There  is  no  grea4;  objection  to  treating 
a  case  of  diphtheria  in  the  household  provided  the  patient  and  the  nurse 
may  also  be  quarantined  from  the  rest  of  the  household.  Under  these 
circumstances  and  with  intelligent  care  and  disinfection  at  the  bedside 
there  is  little  danger  to  the  rest  of  the  family;  but  the  great  menace 
that  some  of  the  members  of  the  family  will  become  bacillus  carriers  of  a 
dangerous  type  makes  it  advisable  to  treat  all  cases  of  diphtheria  in  a 
special  hospital. 

All  outbreaks  should  of  course  be  investigated  as  to  their  st)urce. 
The  possibility  of  milk-borne  infection  is  usually  evident.  In  any  case, 
milk  should  be  pasteurized  and  care  taken  to  prevent  infection  in  the 
kitchen  or  in  serving  and  handling  food. 

Schools  need  not  be  closed  during  an  epidemic  of  diphtheria ;  in  fact, 
better  results  will  be  achieved  by  daily  inspection,  and  examination  of 
cultures  from  the  nose  and  throat  of  each  pupil  from  time  to  time.  The 
well  children  of  a  household,  where  a  person  is  ill  with  diphtheria, 
should  be  excluded  from  school  until  one  week  has  expired  from  the  date 
of  the  last  exposure,  unless  showing  two  negative  cultures  from  throat 
and  nose.  All  other  members  of  the  household  may  be  allowed  to 
continue  their  usual  occupations,  except  those  who  are  engaged  in  the 
handling  of  milk. 

Responsibility  of  the  Medical  Profession. — People  still  die  of 
diphtheria — usually  because  the  diagnosis  is  not  made  early  and  because 
diphtheria  antitoxin  is  not  given  in  time. 

Diphtheria  antitoxin  is  a  specific  and  sovereign  remedy.  When  given 
in  sufficient  amounts  during  the  first  24  hours  of  the  disease  it  reduces 
the  mortality  to  practically  nil.  Upon  the  first  appearance  of  sore 
throat,  fever,  or  other  suggestive  symptoms  in  persons  who  are  exposed 


DIPHTHERIA  207 

to  diphtheria,  a  full  dose  of  3,000  to  10,000  units  should  be  administered 
subcutaneously  without  delay.  It  is  absorbed  more  quickly  when  given 
intraniuscularl3\  In  very  toxic  cases,  or  for  late  use,  it  acts  most  quickly 
when  given  intravenously.  In  order  to  obtain  the  full  life-saving  bene- 
fits of  diphtheria  antitoxin,  it  should  be  given  early  in  the  disease.  Time 
is  the  most  important  factor.  When  the  damage  to  the  cells  has  been 
done,  it  may  be  too  late.  It  is  not  always  advisable  to  wait  for  bacterial 
confirmation. 

Many  unnecessary  deaths  from  diphtheria  occur.  In  New  York  City 
alone,  over  1,000  deaths  occur  annually,  approximately  20  per  100,000  of 
population.  Similar  rates  prevail  in  Rhode  Island,  Pennsylvania,  Ken- 
tucky, North  Carolina.  Massachusetts,  Michigan,  and  elsewhere. 

In  a  study  of  1,000  deaths  recently  made  by  Carey  ^^  of  the  Massachu- 
setts State  Department  of  Health,  it  is  shown  that  the  useful  knowledge 
and  facilities  for  dealing  with  diphtheria  are  still  utilized  far  too  little. 
In  23.1  per  cent,  of  the  cases,  the  patient  was  ill  a  week  before  the 
physician  was  called.  In  4.2  per  cent.,  the  patients  had  been  ill  from 
one  to  two  weeks  before  they  received  attention.  In  7.6  per  cent,  of  the 
deaths,  the  disease  was  not  recognized  during  life.  In  a  number  of 
fatal  cases,  the  physician  delayed  antitoxin  treatment  by  waiting  for 
laboratory  confirmation  of  the  diagnosis.  In  not  a  single  instance  was 
the  antitoxin  given  intravenously,  A  similar  situation  was  found  in 
New  York  City — "with  a  diagnostic  laboratory  service  unsurpassed, 
with  Schick  test  outfits,  antitoxic  serum,  and  active  immunization  out- 
fits practically  at  their  elbow,  the  physicians  of  New  York  were  charged 
with  insufficient  or  delayed  utilization  of  these  aids  and  with  responsi- 
bility of  continued  prevalence  of  fatal  cases  of  diphtheria,"  Every 
death  from  diphtheria  should  be  investigated  and  the  responsible  party 
brought  to  task.  The  facts  indicate  the  further  need  of  education  of 
both  the  profession  and  the  public,  in  order  to  save  lives  from  this  and 
other  preventable  infections. 

The  disease  often  begins  insidiously  and  the  true  diagnosis  is  often 
not  made  until  too  late  for  antitoxin  to  exert  its  life-saving  power. 

PREVENTION  OF  POSTDIPHTEEEITIC  PARALYSIS 

It  has  been  observed  that  postdiphtheritic  paralysis  is  more  fre- 
quent since  the  use  of  antitoxin  than  before  the  days  of  serum  therapy. 
This  is  due  to  the  fact  that  many  cases  now  recover  that  would  for- 
merly have  died.  It  is  also  due  to  the  fact  that  diphtheria  antitoxin 
is  sometimes  used  too  late,  thus  neutralizing  only  the  acute  effects  of 
the  toxin,  but  not  neutralizing  the  after  effects  of  the  toxon  which 
acts  specifically  upon  the  nerves.     The  prevention  of  postdiphtheritic 

^'Boston  Med,  and  Surg.  Jour.,  CLXXX,  3,  p.  67,  Jan.  16,  1919, 


208     DISEASES  FROM  DISCHAEGES  OF  MOUTH  AND  NOSE 

paralysis,  therefore,  consists  in  giving  sufficient  amounts  of  antitoxin 
early  in  the  disease.  The  antitoxin  does  not  influence  the  paralysis 
after  it  has  once  appeared. 

PREVENTION  OF  SERUM  SICKNESS  AND  ANAPHYLACTIC 

SHOCK 

This  subject  may  appropriately  be  considered  here,  although  it  is 
a  condition  that  may  follow  the  injection  of  any  alien  serum  into 
the  system.  Serum  sickness  is  a  syndrome  which  frequently  follows 
the  injection  of  horse  serum  into  man.  The  symptoms  come  on  after 
about  8  or  10  days  following  the  injection.  They  consist  of  various  skin 
eruptions,  usually  urticarial  or  erythematous  in  character;  also  fever, 
vomiting,  edema,  glandular  and  splenic  enlargements,  rheumatic-like 
pains  in  the  joints  and  muscles;  and  albuminuria.  The  eruptions  may  be 
either  local  or  general,  and  sometimes  resemble  those  of  scarlet  fever 
or  measles.  Serum  sickness  has  nothing  to  do  with  the  antitoxin,  but 
is  caused  entirely  by  the  foreign  proteins  contained  in  the  horse  serum. 
It  may  be  produced  with  normal  horse  serum  as  well  as  with  antitoxic 
horse  serum.  The  studies  upon  anaphylaxis  have  throAvn  much  light 
upon  the  nature  of  this  complication.  The  occurrence  and  severity  of 
the  symptoms  depend  upon  the  amount  of  foreign  protein  injected  and 
the  sensitiveness  of  the  individual.  Fortunately,  this  form  of  anaphy- 
lactic reaction  soon  passes  away  and  is  never  serious.  Under  certain 
^  ircumstances,  however,  there  may  be  an  accelerated  or  immediate  reac- 
tion threatening  in  its  consequence  or  even  leading  to  death.  Eosenau 
and  Anderson  have  collected  some  19  cases  of  sudden  death  following 
the  injection  of  horse  serum,  and  they  know  of  more  instances  which 
have  not  appeared  in  the  literature.  This  unusual  and  serious  complica- 
tion comes  on  within  5  or  10  minutes  of  the  injection,  and  is  character- 
ized by  collapse,  unconsciousness,  cyanosis,  labored  respiration,  and 
edema.  The  heart  continues  to  beat  after  respiration  has  ceased.  The 
entire  picture  is  an  exact  counterpart  of  the  anaphylactic  shock  so  readily 
reproduced  by  a  second  injection  of  horse  serum  or  other  foreign  protein 
in  the  guinea-pig.  Contrary  to  the  experimental  work  on  the  lower 
animals,  the  cases  of  sudden  death  in  man  follow  the  first  injection  of 
horse  serum.  The  serious  symptoms  and  death  in  these  cases  are  not 
due  to  any  inherent  poisonous  property  in  the  antitoxic  serum,  but 
result  entirely  from  a  hypersusceptibility  of  the  individual.  Just  how 
man  becomes  sensitized  in  these  cases  is  not  known  (page  599).  Most 
of  the  cases  occur  in  healthy  persons  who  give  a  history  of  asthma 
or  discomfort  when  about  horses.  This  is  a  practical  and  important 
point,  and  should  be  inquired  into  before  horse  serum  of  any  kind  is 
injected.     Horse  serum  should  not  be  injected  into  such  individuals 


SERUM  SICKNESS  209 

unless  the  indications  are  oloar,  and  then  only  with  a  statement  as  to 
the  possible  outcome.     Bovine  serum  may  be  usefl. 

Diphtheria  antitoxin  may  ])e  given  without  fear  of  anaphylactic 
shock  in  cases  of  diphtheria.  I'he  few  serious  accidents  have  occuiTed 
only  with  propliylactic  doses  in  healtliy  persons.  Tliere  is  no  instance 
on  record  of  diphtheria  antitoxin  causing  fatal  anapliylactic  shock  in 
a  person  ill  with  diplitheria.  We  now  have  an  experimental  confirma- 
tion of  this,  for  Bronfcnl)rcnner/^  working  in  my  laboratory,  has  shown 
that  diphtheria  toxin  prevents  anaphylactic  shock  in  sensitized  guinea 
pigs.  It  is  therefore  inexcusable  to  delay  or  hesitate  to  use  full  thera^ 
peuiic  doses  of  anfifo.rin  in  diphtheria. 

Desensitization. — In  order  to  prevent  anaphylactic  shock  following 
the  use  of  serum  in  pneumonia  and  other  diseases  in  which  large 
amounts  of  alien  proteins  gre  injected,  desensitization  may  be  attempted. 
Sensitiveness  should  first  be  tested  by  injecting  minute  amounts  of  the 
alien  protein  into  the  skin.  Within  an  hour  a  characteristic  local  edema 
and  erythema  takes  place  at  the  site  of  the  injection.  Desensitization 
may  be  accomplished  by  injecting  exceedingly  minute  amounts  subcuta- 
neously  and  repeating  this  every  half -hour  or  hour  with  doses  of  gradu- 
ally increasing  size.  Persons  may  also  be  desensitized  by  injecting  0.5  to 
1.0  c.  c.  of  the  serum  to  be  used,  subcutaneously,  several  hours  before 
giving  intravenous  injections.  Whether  the  patient  is  susceptible  or 
not,  intravenous  injections  should  be  given  very  slowly. 

Friedberger  and  Mita  ^~  found  it  possible  to  avoid  all  symptoms  of 
anaphylaxis  in  experimental  work  with  guinea-pigs  by  injecting  the 
serum  extremely  slowly.  When  thus  introduced  animals  are  able  to 
tolerate  an  amount  far  beyond  the  ordinary  lethal  dose. 

Adrenalin,  pituitrin,  chloral,  chloroform,  and  atropin  in  full  thera- 
peutic amounts  are  claimed  to  ameliorate  or  even  prevent  anaphylactic 
shock,  but  it  must  be  admitted  that  none  of  the  above  procedures  is 
wholly  satisfactory. 

Historical  Note  and  References. — A  complete  summary  and  bibli- 
ography of  diphtheria  up  to  1908  will  be  found  in  the  system  edited  by 
Kuttall  and  Graham-Smith  entitled  "The  Bacteriology  of  Diphtheria," 
containing  articles  by  Loffler,  Newsholme,  Mallor}',  Graham-Smith, 
Dean,  Park,  and  Bolduan ;  Cambridge  University  Press,  1908. 

The  modern  clinical  description  of  the  disease  is,  by  common  assent, 
attributed  to  Bretonneau,  of  Tours,  in  1826 :  Traite  de  la  diphtherite. 
Des  inflammations  speciales  du  tissu  muqueux  et  au  particular  de  la 

^  Proceed.  Soc.  Exp.  Biol,  and  Med..  Feb.  16.  1920. 

^'Friedberger,  E..  and  Mita.  S. :  "To  Prevent  Anaphylaxis  in  Serotherapy" 
("Methode,  prossere  ]\Iengen  artfremden  Serums  bei  iiberempfindlichen  Tndividuen 
zu  injizieren"),  Deutsche  vied.  Wochenschr.,  Berlin,  Feb.  1,  XXXVIII,  Xo.  5,  pp. 
201-248. 


210     DISEASES  FEOM  DISCHAEGES  OF  MOUTH  AND  NOSE 

diphtherite  ou  inflammation  pelliculaire,  connue  sous  le  nom  de  croup, 
d'angine  maligne,  d'angine  gangreneuse,  etc.,  Paris. 

The  bacillus  of  diphtheria  was  first  cultivated  and  adequately  de- 
scribed by  Loffler,  1884:  Untersuchungen  iiber  die  Bedeutung  der 
Mikroorganismen  fiir  die  Entstehung  der  Diphtherie  beim  Menschen, 
bei  der  Taube  und  beim  Kalbe.  MittJi.  a.,  d.  h.  Gesundheitsamte, 
ii,  451. 

The  classical  article  in  which  Behring  and  Kitasato  announced 
their  discovery  of  diphtheria  antitoxin  in  1890  will  be  found  in  Deutsche 
med.  Wochenschr.,  xyi,  1113.  Ueber  das  Zustandekommen  der  Diph- 
therieimmunitat  und  die  Tetanusimmunitat  bei  Tieren. 

Ehrlich's  important  work,  in  which  he  laid  the  foundations  of  his 
side-chain  theory  and  established  the  present  satisfactory  method  of 
standardizing  diphtheria  antitoxin,  will  be  found  in  the  following:  Die 
Werthbemessung  des  Diphtherieheilserums  und  deren  iheoretische 
Grundlagen.  Klin.  Jahrh.,  Jena,  v,  6  (2),  1897,  pp.  299-326.  Ueber 
die  Constitution  des  Diphtheriegiftes.  Deut.  med.  Woch.,  Leipzig,  v, 
24  (38),  1898,  pp.  597-600.  Croonian  lecture.  On  Immunity  with 
Special  Eeference  to  Cell  Life.  Proc.  Eoy.  Soc,  London,  v,  66,  pp. 
424-448,  pis.  6-7. 

The  official  method  for  standardizing  diphtheria  antitoxin  in  this 
country  and  the  principle  upon  which  it  is  based  are  described  by 
Eosenau  (1905),  The  Immunity  Unit  for  Standardizing  Diphtheria 
Antitoxin  (based  on  Ehrlich's  normal  serum).  Hygienic  Laboratory 
Bull,  Kg.  21,  P.  H.  and  M.  H.  S.,  Washington,  Govt.  Print.  Office, 
92  pp. 

The  Schick  test  was  first  described  in  the  Miinch.  med.  WochnscJir., 
Nov.  25,  1913,  p.  2608. 

VINCENT'S  ANGINA 

Vincent's  angina  was  first  described  by  Professor  Vincent  in  1898. 
It  is  an  important  disease  in  itself,  and  also  because  it  is  very  likely 
to  be  mistaken  for  diphtheria.  Vincent's  angina  is  due  to  a  fusiform 
bacillus  and  an  accompanying  spirillum  (spirochete  ?).  In  early  cases 
the  bacilli  are  usually  more  numerous  than  the  spirilla,  but  in  more 
advanced  cases  the  spirilla  usually  predominate.  The  organisms  are  best 
stained  with  carbol-gentian  violet.  Both  the  spirilla  and  the  bacilli 
are  usually  gram  negative.  They  have  been  grown  by  Tunnicliff  ^^  an- 
aerobically  in  ascitic  broth  containing  a  piece  of  tissue.  She  regards 
them  as  identical  for  the  reason  that  the  spirillum  appeared  to  develop 
from  a  pure  culture  of  the  fusiform  bacillus. 

The   disease   is    characterized   by   slight   constitutional   disturbance 

^Jour.  Inf.  Dis.,  III.  1,  Mar..  1906,  p.  148. 


VmCENT'S  ANGINA  '>tl 

and  no  fever;  the  temiu'iatuif  lari'ly  ^^oes  over  lOO"^  K. ;  there  is  pain 
on  swallowing;  the  subniaxiliarv  lyni|)liati{'  <rlaii(ls  are  enlarj^ed  and 
tender,  the  lesions  are  often  unilateral;  the  yellowish-gj-ay  membra- 
nous exiuhite  is  usually  easily  removed,  leaving  a  raw,  hleeding  surfaee; 
albumin  rarely  aj'pears  in  the  urine. 

The  fusiform  baeillus  and  the.  long  spirilluin  were  ilrst  demon- 
strated in  cases  of  ulceromemhranous  angina,  and  later  l'(nind  in  cases 
of  uleeromeml)ranous  stomatitis;  also  in  gingivitis,  noma,  hospital 
gangrene,  pyorrhea  alveolaris,  appendicitis,  ahscesses,  and  other  morbid 
processes.  Xoguchi  found  these  organisms  in  a  case  of  ulcer  of  the 
labia,  and  Vincent  himself  reported  a  case  of  gastro-enteritis  in  which 
large  numbers  of  typical  organisms  were  found.  Corbus  and  Harris 
have  described  ulcerative  balanitis  due  to  this  organism,  and  they  called 
it  "the  fourth  venereal  disease." 

This  infection  is  peculiar  to  man;  at  least,  experiments  on  animals 
are  negative.  Second  attacks  and  recurrent  attacks  occur,  indicating 
that  there  is  little  or  no  innnunity  conferred.  Local  applications  of 
arsphenamine  appear  useful,  both  in  treatment  and  for  prophylaxis. 

Vincent's  angina  is  often  mistaken  for  diphtheria.  It  must  be  dif- 
ferentiated from  syphilis.  The  disease  is  much  more  common  than  is 
ordinarily  supposed.  Under  military  conditions  the  incidence  is  greatly 
increased,  and  it  was  a  common  cause  of  disability  in  the  World  War. 
The  disease  is  favored  by  any  debilitating  condition,  such  as  fatigue, 
chill,  exposure,  insuificient  and  improper  food,  and  excessive  use  of 
alcohol  and  tobacco. 

The  organisms  are  found  in  normal  mouths,  especially  in  those  with 
poor  teeth  and  lack  of  oral  hygiene.  Campbell  and  Dyas  found  a  few 
Vincent's  organisms  in  about  50  per  cent,  of  all  swabs  taken  from  the 
throats  of  troops  at  Bramshott.  Eeckf ord  and  Baker  ^*  found  only  one 
ca^-rier  in  fifty  normal  individuals,  whereas  fusiform  bacilli  and  spiril- 
la were  found  in  90  per  cent,  of  the  smears  from  diseased  teeth  in 
a  dental  clinic. 

The  disease  is  spread  through  the  discharges  from  the  lesions  and  by 
carriers  in  the  same  ways  that  diphtheria  is  spread.  The  prophylaxis 
is  similar;  special  attention  must  be  given  to  predisposing  factors, 
such  as  undernutrition,  to  oral  hygiene,  and  to  measures  that  improve 
health. 

^  J.  A.  M.  A.,  Vol.  LXXV,  No.  24,  p.  1620. 


213     DISEASES  FROM  DISCHARGES  OP  MOUTH  AKD  NOSE 


MEASLES 

(MorhilU,  Rubeola) 

Measles  is  usually  taken  as  the  type  of  a  contagious  disease  because 
it  is  one  of  the  most  readily  communicable  of  all  diseases,  in  this  re- 
gard ranking  with  smallpox  and  pandemic  influenza.  As  a  cause  of 
death  it  ranks  high  among  the  acute  fevers  of  children. 

In  the  registration  area  of  the  United  States,  during  the  twelve  years 
from  1900-1911,  50,000  deaths  from  measles  were  recorded,  and  it  is 
estimated  that  over  100,000  deaths  were  caused  by  measles  in  the  con- 
tinental United  States  during  the  same  period.  The  number  of  deaths 
from  measles  as  compared  with  those  of  certain  other  diseases  in  the 
registration  area  during  the  years  1910  and  1917  is  sho.wn  in  the 
following  table: 


1910 

1917 

Disease 

Deaths 

Deaths  per 

100,000 
Population 

Deaths 

Deaths  per 

100,000 
Population 

Diphtheria  and  croup 

Measles 

11,512 
6,598 
6,255 
6,148 
2,272 
1,459 

21.4 
12.3 
11.6 
11.4 
4.2 
2.7 

12,453 

10,745 

3,141 

7,837 
6,890 

16.5 
14.3 

Scarlet  fever 

4.2 

Whooping  cough 

10.4 

Cerebrospinal  meningitis  .  .  . 
Infantile  paralysis 

9.1 

It  is  estimated  that  10,000  deaths  from  measles  take  place  each  year 
in  the  United  States.  These  figures  are  conservative,  for  many  deaths 
from  measles  are  recorded  as  pneumonia. 

Measles  is  an  infection  peculiar  to  man.  Experimental  measles 
has  been  produced  in  monkeys,  but  the  susceptibility  is  not  marked 
and  subject  to  variations.  The  virus  is  contained  in  the  blood,  as 
has  been  shown  by  Hektoen,  who  thus  transmitted  the  disease  from 
man  to  man.  More  important  from  the  standpoint  of  prevention,  the 
virus  has  been  demonstrated  in  the  secretions  from  the  nose  and  mouth 
by  Anderson  and  Goldberger.  The  period  of  incubation  is  quite  con- 
stant (from  9  to  11  days),  and  the  rash  appears  quite  uniformly  on  the 
13th  or  14th  day  after  the  infection.  In  Hektoen's  two  experimental 
cases'  the  eruption  appeared  on  the  14th  day.  The  cause  of  measles 
is  not  known. 

Measles  is  more  or  less  constantly  present  in  all  large  cities  in  the 
temperate  zone;  it  is  less,  common  in  the  tropics,  although  it  spreads 
as  readily  in  hot  as  in  cold  climates.    All  races  are  susceptible ;  the  death 


MEASLES  213 

rate  is  higher  in  urban  than  in  rural  districts.^'  Measles  frequently 
becomes  epidemic,  usually  in  the  cooler  months,  in  this  respect  resem- 
bling influenza,  scarlet  fever  and  smallpox.  The  epidemics  recur  cycli- 
cally, at  intervals  of  two  or  three  years,  with  considerable  regularity  in 
thickly  settled  communities.  In  more  sparsely  populated  areas,  these 
waves  recur  at  longer  and  more  irregular  intervals.  Levy  and  Foster 
noticed  that  in  Richmond,  Va.,  epidemic  outbreaks  recurred  at  intervals 
of  about  3  years.  They  were  able  to  predict  and  warn  against  an 
epidemic  prevalence  of  the  disease  in  the  winter  of  1910.  During  1909, 
40  cases  of  measles  occurred  in  Richmond,  but  during  this  year  the 
disease  showed  no  special  tendency  to  spread.  In  the  middle  of  Feb- 
ruary, 1910,  8  cases  occurred  among  the  pupils  of  one  school  and  the 
infection  showed  a  high  degree  of  communicability.  According  to  the 
history  of  the  disease,  an  epidemic  year  was  due  and  an  epidemic  was 
predicted.     Over  2,000  cases  occurred  with  26  deaths. 

Measles  is  highly  contagious  during  the  preemptive  stage,  when  the 
nature  of  the  disease  is  not  recognized  and  when  most  of  the  damage 
is  done;  it  remains  contagious  for  a  variable  time  during  convalescence. 
Recent  experimental  evidence  and  clinical  experience  plainly  indicate 
that  the  infection  of  measles  soon  dies  out.  and  that  there  is  little  danger 
of  transmitting  the  disease  after  the  temperature  returns  to  normal. 
An  isolation  of  two  weeks  from  the  onset  of  the  disease  is  sufficient  in 
public  health  work;  health  officers,  however,  adopt  arbitrary  times. 
For  public  health  purposes  the  maximum  period  of  incubation  is  placed 
at  14  days. 

Measles  is  malignant  in  virgin  soil.  An  increased  virulence  is  also 
observed  wherever  many  cases  of  measles  are  brought  together.  This 
is  explained  on  the  theory  of  cross-infection  with  the  chief  complica- 
tions— streptococci  and  pneumonia. 

Imnmnity. — One  attack  of  measles  confers  a  definite  protection 
against  subsequent  attacks;  second  attacks,  however,  are  more  com- 
monly reported  than  in  the  other  eruptive  fevers.  Some  persons  are  said 
to  have  the  disease  three  or  four  times.^^  The  close  similarity  between 
rubella  (German  measles)  and  rubeola  (measles)  accounts  for  many  so- 
called  second  attacks  of  measles.  As  with  smallpox,  there  appears  to  be 
no  natural  immunit}'  to  measles — man  is  exquisitely  susceptible  to  these 
two  infections.  There  appears  to  be  a  relative  immunity  sometimes  of 
a  high  grade  during  the  first  few  months  of  life,  although  measles  oc- 
casionally occurs  in  infants  of  a  month  or  six  weeks. 

"Crum,  F.  S.:  A  Statistical  Study  of  Measles.  Am.  Jour,  of  Pub.  Health, 
April,  1914,  Vol.  IV,  Xo.  4,  p.  289. 

^Wagener  (Monshrift  fiir  Kinderheilkunde,  xii,  2,  p.  477)  describes  mild 
catarrhal  attacks  during  epidemics  in  adults  who  have  had  measles,  and  believes 
these  to  be  atypical  cases.  He  states  that  the  disease  is  spread  by  these  missed 
cases. 


214     DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 

Adults  are  susceptible  to  measles,  provided  they  have  not  had-  a 
previous  attack.  Susceptibility  to  the  infection  does  not  diminish  with 
increasing  age;  the  disease  is  apparently  one  of  childhood  only  on  ac- 
count of  the  chances  of  exposure  in  early  life.  Before  the  days  of  vac- 
cination smallpox  was  also  a  disease  mainly  of  childhood. 

The  following  instances  demonstrate  the  susceptibility  of  adults  to 
measles  and  also  the  serious  nature  of  the  disease:  Measles  was  intro- 
duced into  the  Faroe  Islands  in  1846  from  Copenhagen,  and  over  6,000 
of  the  7,782  inhabitants  were  stricken.  Panum  found  no  natural  im- 
munity in  this  epidemic.  In  1775  it  was  introduced  into  the  Sandwich 
Islands,  and  in  4  months  40,000  of  the  population  of  150,000  died.  In 
1874,  Thacombau,  the  native  chief  of  the  Fiji  Islands,  had  measles 
while  on  a  visit  to  Sydney.  His  son  and  a  native  attendant  sickened 
on  the  voyage  home,  and  carried  the  infection  to  the  islands,  with  the 
result  that  one-fifth  of  the  population  (20,000)  died.  The  Virulence  of 
measles  under  these  conditions  makes  us  conclude  that  a  certain  amount 
of  resistance  is  acquired  by  communities  in  which  the  disease  has  pre- 
vailed a  long  time. 

Measles  is  common  in  army  camps,  especially  among  troops  enlisted 
from  country  districts,  who  are  thus  exposed  to  the  infection  for  the 
first  time.  In  the  "World  War,  measles  was  a  serious  cause  of  disability 
in  our  mobilization  and  training  camps.  Pneumonia  was  the  common 
complication,  often  resulting  fatally. 

Measles  itself  is  rarely  fatal — 95  per  cent,  of  the  deaths  are  due  to 
pneumonic  infection.  In  this  regard,  influenza  and  measles  are  alike. 
Both  diseases  become  malignant  when  introduced  into  a  population 
where  they  have  not  prevailed  for  a  long  time.  Measles  lowers  the  re- 
sistance to  diphtheria,  pneumonia,  streptococci,  tuberculosis  and  noma; 
it  is  a  common  history  for  tuberculosis  to  develop  after  an  attack  of 
measles. 

Measles,  perhaps  more  than  any  other  disease,  lowers  resistance 
to  other  infections.  Immune  bodies  diminish  or  disappear  from  the 
blood  during  and  soon  after  measles.  Thus,  the  tuberculin  reaction  is  in 
abeyance  during  and  some  months  after  an  attack;  typhoid  agglutinins 
diminish  in  the  blood.     There  is  a  distinct  leukopenia. 

Nicolle  and  Conseil  attempted  to  immunize  children  with  the  blood 
serum  of  convalescents  and  also  with  virus.  Similar  attempts  are  now 
being  carried  out  by  several  investigators.  This  work  is  too  recent  to 
form  a  judgment,  but  the  control  of  measles  clearly  depends  upon  a 
specific  prophylactic. 

Resistance  of  the  Virus. — In  general  the  virus  of  measles  is  known 
to  be  much  less  resistant  than  that  of  scarlet  fever  and  many  other  in- 
fections. The  virus  does  not  live  long  upon  fomites,  probably  less  than 
24  hours.     The  infection  is  commonly  passed  directly  from  person  to 


MEASLES  215 

person.  There  is  practically  no  danger  of  children  contracting  the  infec- 
tion from  the  room  in  wliich  the  patient  was  treated,  even  though  no 
disinfection  was  practiced,  provided  two  weeks  have  elapsed. 

Goldberger  and  Anderson  ^^  found,  as  the  result  of  experiments  upon 
monkeys,  that  the  virus  in  measles*  blood  may  pass  through  a  Berkefeld 
filter.  In  blood  serum  it  resists  desiccation  for  25^,^  hours,  loses  its 
infectivity  after  15  minutes  at  55°  C,  resists  freezing  for  25  hours, 
and  possibly  retains  some  infectivity  after  2-i  hours  at  15°  C. 

From  the  standpoint  of  our  present  knowledge  it  is  evident  that 
any  of  the  ordinary  germicidal  agents  sufficient  to  kill  spore-free  bac- 
teria will  serve  as  effective  disinfectants  for  measles.  Aside  from  the 
few  scientific  observations  upon  the  viability  of  the  virus  of  measles, 
epidemiological  observations  have  long  pointed  out  the  fact  that 
the  virus  of  measles  is  frail  and  soon  dies  in  the  convalescent  as  well 
as  in  the  environment.  So  far  as  is  known,  there  are  no  carriers  of 
measles. 

Modes  of  Transmission. — The  virus  of  measles  is  contained  in  the 
nasal  and  buccal  secretions.  While  it  is  possible  that  the  virus  may 
leave  the  body  in  other  secretions,  it  is  highly  probable  that  the  dis- 
charges from  the  nose  and  mouth  are  the  means  of  transmitting  the 
infection  in  the  vast  majority  of  cas'es.  We  are  less  certain  concerning 
the  modes  of  entrance  into  the  body,  although  it  is  presumed  that  the 
virus  also  enters  by  the  moutli  and  nose.  The  evidence  is  clear  that 
measles  is  usually  transmitted  by  direct  contact. 

Mayr  ^^  showed  in  1852  by  experiments  on  the  human  subject  that 
the  buccal  and  nasal  secretions  were  infective.  Anderson  and  Gold- 
berger ^^  have  demonstrated  bv  experiments  upon  monkeys  that  the  nasal 
and  buccal  secretions  of  uncomplicated  cases  of  measles  may  be  at  times, 
but  are  not  always,  infective.  Hektoen  ^^  in  1905,  as  well  as  Goldberger 
and  Anderson,  1911,  demonstrated  that  the  virus  of  measles  is  also 
contained  in  the  circulating  blood.  The  virus  appears  in  the  blood  at 
least  24  hours  before  the  eruption  appears,  and  begins  to  diminish  about 
25  hours  after  the  first  appearance  of  the  eruption.  Xicolle  and  Conseil, 
also  Lucas  and  Prizer  have  produced  experimental  measles  in  monkeys. 
Blake  and  Trask's  results  are  convincing.'*"^ 

It  had  long  been  assumed  that  the  virus  of  measles  is  carried  in  the 
fine  bran-like  desquamating  epithelium,  which  is  one  of  the  characteris- 
tics of  the  disease.  ^Mayr  long  ago  failed  in  his  attempts  to  inoculate 
children  with  measles  by  using  the  desquamating  epithelium.  Anderson 
and  Goldberger  also  obtained  negative  results  in  three  experiments,  in 

"J.  A.  M.  A.,  Vol.  'LYJI,  No.  12,  Sept.  16,  1911,  p.  971. 

^Mavr,  Franz:  Zeitschr.  d.  k.  k.  Gesemch.  de  Aertze  zii  TTien,  18.52,  I.  13-14, 

^J.  A.  M.  A.,  Vol.  LVII,  Xov.  11,  1911,  p.  1612. 

'"Experimental  Measles:     Jour.  Infect.  Dis.,  190.5,  Vol.  II.  p.  238. 

*^Jour.  Ex.  Med.,  March,  1920. 


21G     DISEASES  FEOM  DISCHAEGES  OP  MOUTH  AND  NOSE 

which  it  was  shown  that  the  "scales"  were  not  infective  for  monkeys. 
These  authorities  believe  that  it  is  highly  probable,  if  not  altogether 
certain,  that  the  desquamating  epithelium  of  measles  in  itself  does  not 
carry  the  virus  of  the  disease.  This  conclusion  is  warranted  by  epidemio- 
logical evidence. 

Measles  is  so  readily  communicable  that  clinicians  receive  the  im- 
pression that  the  virus  is  "volatile."  It  has  long  been  suspected  that 
the  virus  is  contained  in  the  expired  breath,  but  this  is  very  doubtful. 
In  fact,  it  may  now  be  stated  with  confidence  that  measles  is  not  air- 
borne, in  the  sense  in  which  this  term  is  usually  understood.  In  any 
case,  the  radius  of  danger  through  the  air  is  confined  to  the  immediate 
surroundings  of  the  patient — that  is,  within  the  danger  zone  of  droplet 
infection.  Droplet  infection  is  quite  possible,  as  the  virus  is  contained 
in  the  secretions  of  the  mouth  and  nose;  furthermore,  it  evidently  re- 
quires an  exceedingly  minute  quantity  of  the  virus  to  reproduce  the 
disease  in  man,  who  is  exquisitely  susceptible  to  this  infection. 

Chapin  has  collected  important  evidence  indicating  that  the  infec- 
tion of  measles  is  not  air-borne.  Thus,  in  the  Pasteur  Hospital,  Paris, 
each  patient  is  cared  for  in  a  separate  room  opening  into  a  common 
hall.  Trained  nurses  exercise  strict  medical  asepsis.  In  2%  years  after 
this  hospital  was  opened  in  1900  many  cases  of  smallpox,  diphtheria, 
scarlet  fever,  and  126  cases  of  measles  were  cared  for.  In  no  instance 
did  measles  spread  within  the  hospital.  At  the  Children's  Hospital  in 
Paris  (Hopital  des  Infants  Malades),  instead  of  being  in  separate  rooms, 
the  beds  are  separated  only  by  partitions.  Strict  asepsis  is  observed. 
Of  5,017  cases  there  were  only  7  cross-infections,  6  of  measles  and  1  of 
diphtheria.  Dr.  Moizard  thinks  that  this  experience  proves  that  even 
measles  is  not  air-borne,  for  the  few  cases  of  this  disease  which  did 
arise  were  not  all  in  cubicles  adjoining  those  occupied  by  measles 
patients.  Grancher  in  another  Paris  hospital  had  two  wards  in  which 
there  were  no  partitions,  but  only  wire  screens  around  the  beds,  simply 
as  a  reminder  for  the  nurses.  Of  6,541  patients  treated  from  1890-1900, 
115  contracted  measles,  7  scarlet  fever,  and  1  diphtheria.  Grancher 
insists  that  measles  is  probably  not  an  air-borne  disease.  Adjacent  pa- 
tients do  not  necessarily  infect  one  another.  At  various  other  hospitals 
similar  methods  have  been  tried  with  success.  These  experiences  indi- 
cate that  the  danger  of  aerial  infection  in  measles  is  much  less  than  is. 
generally  supposed. 

The  infection  of  measles  is  usually  transmitted  more  or  less  directly 
from  person  to  person  by  means  of  the  excretions  from  the  mouth  and 
nose,  and  most  often  during  the  early  stages  of  the  disease.  Measles 
may  be  transmitted  by  third  persons  or  by  fomites  only  when  the  time 
interval  is  short;  such  instances  are  rather  exceptional.  Carriers  are 
not  known. 


MEASLES  21? 

Prevention. — The  suppression  of  measles  is  one  of  tiie  most  difficult 
problems  we  have  to  face,  for  the  reason  that  the  disease  is  one  of  thj 
most  highly  communicable  of  all  infections,  and  for  the  further  reason 
that  it  is  most  contagious  during  the  preemptive  stage.  To  tiio  student 
of  preventive  medicine  the  prol)lcm  of  measles  is  very  similar  to  that 
of  smallpox  and  influenza,  and  the  final  control  will  probably  have  to 
await  a  specific  prophylactic  measure.  Improved  sanitation,  better 
hygiene,  and  the  general  advance  of  civilization,  which  have  made  such  a 
marked  impression  upon  typhus  fever,  relapsing  fever,  typhoid  fever, 
and  other  "filth"'  diseases,  have  no  influence  whatever  upon  such  infec- 
tions as  measles,  smallpox  or  influenza. 

Measles  is  such  a  common  disease  that  parents  are  prone  to  take 
little  pains  to  avoid  the  infection;  they  even  sometimes  purposely  ex- 
pose their  children.  This  is  a  mistaken  attitude.  Special  care  should 
be  exercised  especially  during  the  first  five  years  of  life,  as  over  90  per 
cent,  of  the  fatal  cases  occur  in  this  period.  While  it  may  be  almost 
hopeless  to  lessen  the  morbidity  in  measles,  it  is  quite  possible  materially 
to  decrease  the  mortaHty  by  simply  delaying  the  age  incidence. 

Clinical  experience  plainly  indicates  that  few  people  die  of  measles 
if  properly  cared  for.  The  mortality  may,  therefore,  be  decreased  by 
careful  nursing  and  protection,  especially  from  streptococci  and  pneu- 
mococci,  which  are  the  cause  of  the  most  dangerous  complications.  Xew- 
man  sums  up  the  matter  of  prophylaxis  when  he  states  that  "the  preven- 
tion and  control  of  measles,  like  that  of  whooping-cough  and  tuberculosis, 
is  largely  in  the  hands  of  the  public  themselves." 

In  the  present  state  of  our  knowledge  the  prophylaxis  of  measles 
rests  almost  entirely  upon  one  measure — isolation.  Koplik  spots  are 
valuable  signs  to  detect  cases  early.  They  appear  two  or  three  days,  and 
sometimes  six  days  before  the  rash.  Exposed  persons  may  be  quaran- 
tined or  watched  fourteen  days.  Chapin  believes  that  isolation  has  been 
a  failure  in  measles.  This  is  because  of  the  unrecognized  but  infectious 
preemptive  stage.  "Xo  amount  of  isolation  after  the  disease  is  recog- 
nized can  atone  for  the  harm  done  before  the  diagnosis  is  made."  Isola- 
tion, however,  accomplishes  one  "worthy  object,  viz.,  the  prevention  of 
further  damage.  Isolation,  as  carried  out  in  our  large  cities,  has  had  no 
apparent  effect  upon  the  prevalence  of  the  disease.  In  Aberdeen,  re- 
strictive measures  apparently  protected  only  7  to  10  per  cent,  of  the 
population. 

Despite  its  limitations,  isolation  is  quite  worth  while.  Cases  should 
be  at  once  reported  to  the  health  officer,  the  house  placarded,  and  visit- 
ing prohibited.  Quarantine  should  not  be  raised  nor  should  the  child 
be  permitted  to  return  to  school  until  the  manifestations  of  the  disease 
have  disappeared.  Home  treatment  with  individual  care  gives  the  pa- 
tient the  best  chance  of  recovery.    Herman  advises  against  sending  chil- 


218     DISEASES  FKOM  DISCHAEGES  OF  MOUTH  AND  NOSE 

dreii  having  measles  to  the  hospital  on  account  of  the  danger  of  cross- 
infection.  It  is  difficult  under  ordinary  circumstances  to  prevent  the 
spread  of  the  disease  to  the  other  children  in  a  household.  If  the  case  is 
treated  at  home,  the  children  who  have  not  had  the  disease  may  be  sent 
iaway,  but  kept  under  observation  and  also  under  conditions  that  will  not 
endanger  other  children  in  case  the  disease  develops. 

Measles  patients  must  be  carefully  protected  against  common  colds, 
diphtheria,  pneumonia,  streptococcal  and  other  infections;  also  against 
exposure  and  other  depressing  influences. 

Mild  atypical  and  unrecognized  cases  of  measles  occur,  but  are  far 
less  numerous  than  such  cases  in  scarlet  fever,  diphtheria,  and  typhoid. 
Clinical  evidence  points  to  the  fact  that  "carriers"  of  measles  do  not 
occur.  The  disease  is  usually  spread  directly  from  person  to  person, 
rarely  indirectly  through  a  third  person,  or  by  fomites.  When  measles 
is  conveyed  by  a  third  person  or  by  fomites  it  is  by  means' of  contam- 
ination with  the  fres'h  buccal,  nasal,  or  bronchial  secretions  upon  the 
hands,  handkerchief,  or  some  other  object  that  comes  in  contact  with 
the  mouth  or  nostrils  of  a  susceptible  child.  Physicians  may  readily 
avoid  this  danger  by  wearing  a  gown  and  carefully  washing  the  hands, 
face,  and  hair,  and  waiting  a  reasonable  time  before  visiting  healthy 
children. 

Terminal  fumigation  is  of  no  value  in  preventing  the  spread  of 
measles.  After  the  patient  is  released  from  isolation  a  general  cleaning 
with  boiling  of  fabrics  should  be  practiced,  especially  if  healthy  children 
are  soon  to  occupy  the  playroom  or  bedroom.  However,  if  from  3  to  3 
weeks  have  elapsed,  there  is  practically  no  danger  in  a  well-ventilated, 
sunny,  and  clean  room.  All  bedding,  towels,  handkerchiefs,  and  other 
fabrics  that  have  been  exposed  should  be  boiled  or  otherwise  disinfected. 
Terminal  fumigation  for  measles  has  been  given  up  in  New  York  and 
other  cities  as  unnecessary. 

Closing  the  schools  has  little  effect  in  preventing  the  spread  of 
measles.  If  the  school  is  closed  at  the  beginning  of  an  outbreak  and 
the  disease  continues  to  spread  after  two  weeks,  little  more  will  be  gained 
in  keeping  the  school  closed,  for  it  must  then  be  evident  that  other 
factors  are  at  work  in  spreading  the  infection.  As  the  disease  is 
mainly  spread  in  the  preeruptive  stage,  it  is  sufficient  to  examine  the 
children  each  morning  before  they  enter  school  for  symptoms  of  a  cold, 
injection  of  the  eyes,  running  at  the  nose,  cough,  sore  throat,  fever,  but 
especially  for  Koplik  spots.  All  such  cases  should  be  sent  home  to 
await  further  developments. 

McVail  suggests  that  when  a  child  develops  measles  all  the  children 
exposed  may  be  allowed  to  continue  at  school  8  or  10  days,  and  then 
excluded  for  a  week  to  ten  days,  when  those  who  do  not  develop  the  dis- 
ease may  be  allowed  to  return,     This  is  a  rational  plan  used  in  certain 


SCARLET  FEVER  219 

districts  in  Eiigland..  Wlieii  measles  breaks  out  in  an  orphan  asylum, 
a  public  institution,  or  an  encampment,  the  only  chance  of  checking  the 
spread  of  the  disease  is  through  the  early  recognition  of  first  symptom^ 
and  isolation. 

GERMAN  MEASLES 

{Rubella,  llolheln) 

German  measles  is  a  distinct  disease.  It  is  usually  mild  and  without 
special  complications.  It  is  distinguished  from  measles  by  the  absence 
of  Koplik  spots,  the  slightness  of  the  prodromal  symptoms,  the  mild- 
ness or  absence  of  fever,  the  more  diffuse  character  of  the  rash,  its  rose 
red  color  and  the  early  enlargement  of  the  cervical  glands.  The  in- 
cubation period  is  longer  than  in  measles — 14  to  21  days,  average  17. 
The  two  diseases  do  not  protect  against  each  otlier.  German  measles  is 
very  communicable  and  extensive  epidemics  occur. 

The  cause  of  German  measles  is  not  known.  Prevention  is  the  same 
as  for  measles. 

Clement  Dukes  described  two  forms  of  German  measles,  one  of 
which  he  considers  a  distinct  disease  somewhat  resembling  mild  scarlet 
fever,  rather  than  measles.  It  goes  by  the  name  of  Dukes'  disease,  or 
"the  fourth  disease." 

SCARLET  FEVER 

Scarlet  fever  is  an  acute  febrile  infection  characterized  by  a  diffuse 
eruption  which  appears  during  the  first  day  or  two  of  the  fever,  and 
sore  throat  of  variable  intensity.  The  seasonal  j^revalence  of  scarlet 
fever  resembles  that  of  diphtheria.  The  disease  increases  in  the  fall 
of  the  year,  and  continues  high  until  ]\Iay :  there  is  a  sharp  drop  in  June 
and  the  curve  is  low  during  the  hot  months  of  July  and  August.  The 
period  of  incubation  is  from  2  to  7  days:  usually  3  to  4.  In  a  few 
instances,  in  which  individuals  have  been  inoculated  with  the  blood  of 
scarlet  fever  patients,  3  to  4  days  elapsed  before  the  onset  of  symptoms. 
For  public  health  purposes  the  maximum  period  of  incubation  is  placed 
at  8  days.  Scarlet  fever  is  rare  in  the  tropics;  when  introduced  it 
soon  dies  out.  There  is  probably  always  more  or  less  scarlet  fever  in 
every  thickly  settled  district  in  the  temperate  zone.  The  infection  is  kept 
alive  largely  through  the  mild  and  unrecognized  cases.  Scarlet  fever 
varies  greatly  in  intensity  in  different  outbreaks.  In  some  epidemics 
the  death  rate  is  30  per  cent. ;  in  others  it  is  practically  nil.  In  recent 
years  the  disease  is  distinctly  milder  than  formerly. 

Landsteiner,  Levaditi  and  Prasek  *^  apparently  succeeded  in  transf  er- 
*^Ann.  de  I'lnst.  Pasteur,  Oct.,  1911,  XXV,  Xo.  10,  p.  754. 


220     DISEASES  FROM  DISCHAKGES  OF  MOUTH  AND  NOSE 

ring  scarlet  fever  to  chimpanzees  and  also  to  monkeys.  The  animals 
were  inoculated  both  by  applying  throat  swabs  from  scarlet  fever  patients 
to  the  pharynx  of  the  animals,  and  also  by  injecting  the  animals  with 
blood  from  scarlet  fever  patients.  While  the  nature  of  the  virus  is  still 
unknown,  it  seems  to  be  present  in  the  tonsils,  tongue,  blood,  lymph 
nodes,  and  pericardial  fluid. 

The  cause  of  scarlet  fever  is  not  known.  Mallory  and  Medlar  *^  de- 
scribed a  small  bacillus  (B.  scarlatinae)  in  the  mucous  membrane  of 
the  tonsils  and  throat  and  upper  respiratory  passages  in  the  early  stages 
of  the  disease,  which  has  since  been  identified  as  B.  hroncliisepticns. 
Streptococci  are  almost  constantly  found  in  the  throat  and  blood  of 
scarlet  fever  cases.  Klein  in  1885  was  the  first  to  advocate  the  Strepto- 
coccus scarlatinae  as  the  specific  cause  of  scarlet  fever.  Kurth  assigns  an 
etiological  factor  to  the  Streptococcus  conglomeratus.  It  is  said  to  pro- 
duce a  rash  in  animals  and  men  who  are  injected  with  it.  Streptococci 
of  the  beta  type  described  by  Theobald  Smith  are  the  pathogenic  type 
frequently  found  in  scarlet  fever.  The  chief  reasons  for  considering 
streptococci  as  the  cause  of  scarlet  fever  are  that  they  are  constantly 
found  in  the  throat  of  scarlet  fever  patients ;  that  frequently  they  can  be 
isolated  from  the  blood  of  scarlet  fever  patients  during  life,  and  almost 
constantly  after  death ;  and  that  they  are  the  cause  of  the  complications 
and  death  in  the  majority  of  eases  of  scarlet  fever.  It  is  probable, 
however,  that  streptococci  play  a  secondary  role  in  scarlet  fever  as 
they  do  in  smallpox;  the  disease  itself  may  be  due  to  a  virus,  which 
lowers  resistance  to  streptococcal  invasion. 

It  is  clinically  impossible  to  distinguish  some  cases  of  septic  sore 
throat  from  scarlet  fever. 

Modes  of  Transmission. — It  is  taken  for  granted  that  the  virus  of 
scarlet  fever  is  contained  in  the  secretions  from  the  nose,  throat,  and 
respiratory  tract.  The  virus  probably  enters  by  the  mouth  and  respira- 
tory passages.  It  is  commonly  stated  that  scarlet  fever  is  not  contagious 
during  the  period  of  incubation;  little,  if  any,  during  the  period  of 
invasion,  and  most  contagious  during  the  period  of  eruption.  The  con- 
tagiousness depends  upon  the  discharge  of  the  virus,  which  in  turn  de- 
pends upon  the  condition  of  the  mucoas  membranes  of  the  nose  and 
throat.  This  varies  in  different  cases,  but  as  the  catarrhal  symptoms  are 
usually  most  pronounced  during  the  time  of  the  rash  this  is  therefore 
the  time  of  greatest  danger  in  the  average  case.  Scarlet  fever  may  be 
communicable  from  the  beginning  of  mucous  membrane  lesions  until 
long  after  convalescence.  Scarlet  fever  is  readily  communicable,  but  less 
so  than  measles  or  smallpox ;  it  ranks  about  with  diphtheria. 

Scarlet  fever  is  mainly  spread  by  contact,  carriers  and  milk. 

It  has  long  been  accepted  and  taught  by  the  medical  profession 

*^  Journal  of  Medical  Research,  March,  1916,  Vol.  XXXIV,  No.  1,  pp.  127-130. 


SCARLET  FEVER  221 

that  the  desquamation  is  the  most  infectious  stage  of  scarlet  fever,  and 
it  is  now  very  difficult  to  untcach  the  public  this  erroneous  view.  It  is 
now  known  that  desquamating  patients  may,  as  a  rule,  be  safely  released 
from  quarantine  in  the  6th  week  of  their  attack  of  scarlet  fever,  provided 
they  have  no  mucous  complications  or  other  sequelae.  Convalescents 
may  be  a  source  of  danger  to  others  even  after  desquamation  has  ceased. 
This  fact  has  been  emphasized  from  a  study  of  the  so-called  "return 
cases.'"  Thus  convalescents  are  released  from  hospital  and  permitted  to 
return  home;  soon  another  case  appears  in  one  of  the  members  of  the 
household,  who  in  turn  comes  to  the  hospital.  Xeech  in  a  study  of 
15,000  cases  found  that  the  percentage  of  return  cases  was  1.86  in  those 
cases  who  submitted  to  an  average  period  of  isolation  of  49  days  or 
under.  With  an  average  period  of  50  to  56  days  the  percentage  was  1.12 ; 
where  the  isolation  extended  to  between  57  and  65  days  the  percentage  of 
return  cases  was  1.  McCollom  states  that  in  the  South  Department  of 
the  City  Hospital,  Boston,  the  children  are  kept  50  days,  and  no  patient 
is  released  who  has  a  discharge  from  the  nose  or  an  abnormal  condition 
of  the  throat;  nevertheless  of  3,000  patients  discharged  from  the  scarlet 
fever  ward,  1.7  per  cent,  of  return  cases  occurred. 

There  is  no  accurate  means  of  determining  just  how  long  a  child 
remains  infective  after  scarlet  fever.  The  period  of  detention  varies 
very  much.  Fifty  days  may  be  taken  as  a  working  average.  In  New 
Haven  and  Seattle  cases  are  dismissed  after  desquamation ;  in  Xorth  Da- 
kota 5  days  after  desquamation ;  in  Ohio  and  South  Dakota  10  days  after 
desquamation.  In  various  cities  and  states  the  period  of  isolation  varies 
from  3  weeks  to  8  weeks  unless  the  physician  certifies  that  desquamation 
has  ceased.  In  Milwaukee,  Paterson,  and  Pittsburgh  it  is  never  main- 
tained longer  than  30  days,  even  if  desquamation  continues.  Owing  to 
our  lack  of  knowledge  on  the  subject,  the  jieriod  of  isolation  must  remain 
more  or  less  guesswork.  An  unduly  long  detention  is  a  hardship  upon 
the  patient  and  the  family;  on  the  other  hand,  a  scant  period  is  hazard- 
ous to  the  community.  Cases  with  rhinorrhea,  otorrhea,  throat  trouble, 
or  discharging  abscesses  must  receive  special  care,  as  the  secretions  from 
these  parts  are  now  known  to  remain  infective  for  a  long  time.  Any 
unhealed  area  of  the  body  surface  either  cutaneous  or  mucous  may 
discharge  the  virus. 

Many  cases  of  walking  scarlet  fever  present  little  further  evidence 
than  a  passing  sore  throat.  These  cases  doubtless  spread  the  disease 
by  contact.  Third  persons  may  carry  the  virus  perhaps  on  their  person 
and  perhaps  also  as  carriers.  Toys,  cups,  spoons,  pencils,  chewing  gum, 
candy,  drinking  glasses,  thermometers,  handkerchiefs,  and  other  objects 
contaminated  by  the  secretions  of  the  mouth  play  the  same  role  here  that 
they  do  in  diphtheria.  Scarlet  fever  is  not  air-borne ;  at  least  the  radius 
of  infection  is  limited  to  droplet  infection. 


222     DISEASES  FEOM  DISCHAEGES  OF  MOUTH  AjS^D  NOSE 

Direct  contact  is  the  most  important  and  most  frequent  method  of 
transmitting  scarlet  fevex.*'  The  susceptibility  is  indicated  by  the  fact 
that  less  than  3  per  cent,  of  the  nurses  at  the  South  Department  (Boston 
City  Hospital)  contract  the  disease;  and  only  a  small  fraction  of  a  per 
cent,  of  medical  students.  Place  believes  that  a  large  majority  of  people, 
pjrobably  75  per  cent.,  escape  scarlet  fever. 

MiUc-horne  Scarlet  Fever. — Milk  is  a  rather  frequent  vehicle  for 
scarlet  fever  infection.  The  milk  is  practically  always  contaminated 
from  human  sources.  There  is,  however,  some  suspicion  that  strepto- 
coccal diseases  of  the  cow  may  in  some  instances  be  identical  with  scarlet 
fever.  This  is  doubtful.  It  is  believed,  however,  that  some  diseases  of  the 
udders  of  the  cows  may  cause  outbreaks  of  an  infection  resembling  scarlet 
fever.  Trask  collected  51  scarlet  fever  epidemics  reported  as  spread 
b}'  milk.  Twenty-five  of  these  occurred  in  the  United  States  and  26  in 
Great  Britain.  In  35  of  the  epidemics  a  case  of  scarlet  fever  was  found 
at  the  producing  farm,  the  distributing  dairy,  or  milkshop  at  such  a  time 
as  to  have  been  the  possible  source  of  infection ;  in  3  of  the  outbreaks  the 
bottles  returned  from  infected  households  and  refilled  without  previous 
sterilization  were  given  as  the  source  of  infection;  in  3  of  the  outbreaks 
scarlet  fever  persons  handled  the  milk  or  milk  utensils,  and  in  13  of  the 
outbreaks  the  cows  were  milked  by  persons  having  scarlet  fever;  in  one 
epidemic  the  same  person  nursed  the  sick  and  handled  the  milk;  in  3 
of  the  outbreaks  the  source  of  infection  was  supposed  to  be  due  to  disease 
of  the  cow.  A  milk-borne  outbreak  in  Washington  was  traced  to  a  con- 
valescent \\-ith  a  discharging  ulcer  on  the  finger.  Milk-borne  outbreaks 
of  scarlet  fever  are  sometimes  verj-  extensive. 

An  unusually  extensive  milk-borne  outbreak  of  scarlet  fever  occurred 
in  Boston  during  April  and  May,  1910.  A  total  of  843  cases  were 
reported  from  Boston  and  the  surrounding  towns  of  Chelsea,  Winthrop, 
Cambridge,  Somerville,  Maiden,  and  Everett.  Investigation  showed  that 
most  of  the  cases  occurred  on  the  route  of  a  large  milk  contractor.  Of 
the  409  cases  in  Boston,  286,  or  nearly  TO  per  cent.,  Avere  on  the  route 
of  this  dealer;  while  123,  or  30  per  cent.,  used  other  milk.  Of  the  155 
cases  that  occurred  in  Cambridge,  126,  or  over  80  per  cent.,  were  on  the 
route  of  the  same  dealer.  About  the  same  proportion  of  the  cases  in 
the  other  cities  used  the  milk  of  this  dealer.  The  cases  appeared  sud- 
denly i^pril  25th,  and  the  outbreak  ceased  May  7th.  The  epidemic 
reached  its  highest  mark  on  April  29th,  when  128  cases  were  reported. 
The  indications  were  plain  that  the  outbreak  was  the  result  of  more 
than  a  single  infection.  The  milk  was  pasteurized  at  60°  C.  for  30 
minutes  on  April  27th,  and  three  days  following  there  was  a  notable  and 
sharp  decline  in  the  number  of  cases.  The  source  of  the  infection  could 
not  be  traced,  although  it  probably  consisted  of  a  ''missed"  case  on  one  of 
"Kobrak,  Zeitschr.  f.  Einderheilkunde,  Aug.  16,  1920,  p.  137. 


SCARLET  FEVER  223 

the  250  dairy  farms  from  wliirh  the  dealer  ohtainod  this  particular  sup- 
ply of  milk. 

Immunity. — One  attack  of  scarlet  fever  usually  protects  against  sub- 
sequent attacks.  In  rare  instances  second  attacks  may  occur  after  an 
interval  of  several  years.  Children  under  10  are  most  susceptible.  Suck- 
lings are  rarely  attacked,  though  susceptible.  After  the  10th  year  the 
resistance  to  the  disease  increases.  Xinety  per  cent,  of  the  fatal  cases 
occur  in  children  under  10  years  old.  The  re^ason  ^vhy  infants  al  the 
breast  are  less  likely  to  take  the  disease  may  be  on  account  of  the  dimin- 
ished chances  of  the  infection  entering  the  mouth.  The  immunity  ac- 
quired in  later  life  may  in  part  be  due  to  previous  unrecognized  mild 
attacks.     Family  susceptibility  occurs. 

Prophylaxis. — Prophylaxis  in  scarlet  fever  must  necessarily  be  in 
excess  of  the  requirements,  awaiting  more  precise  kno\\'ledge  of  its 
cause  and  modes  of  transmission.  The  essential  features  of  prevention 
consist  in  isolation  and  disinfection.  It  is  important  to  recognize  the 
mild  cases  in  schools  through  an  efficient  medical  inspection.  The  answer 
to  the  question  whether  schools  should  be  closed  when  scarlet  fever  breaks 
out  varies  with  the  circumstances.  In  country  districts  this  is  advisable, 
as  the  children  may  be  kept  separate,  but  in  the  cities  little  is  gained. 
Better  results  may  often  be  achieved  by  daily  inspection  of  all  pupils 
than  by  closing  the  school.  All  members  of  the  household,  where  a  per- 
son is  ill  with  scarlet  fever,  should  be  excluded  from  school  until  one  week 
has  expired  from  the  last  possible  exposure,  unless  immunized  by  a  pre- 
vious attack  of  the  disease.  All  other  members  of  the  household  may 
be  allowed  to  continue  their  usual  occupations  except  those  engaged  in 
handling  milk.  Patients  with  scarlet  fever  should  be  cared  for  in  hos- 
pital. There  is  no  objection  to  treating  a  case  of  scarlet  fever  in  the 
household,  provided  a  suitable  room  and  trained  attendant  may  be  had. 
The  infection  may  be  confined  to  the  sick  room,  but  it  is  preferable  to 
take  no  chances  and  send  the  susceptible  individuals  out  of  the  house. 
The  nurse  should  use  the  precautions  described  for  diphtheria,  smallpox, 
or  measles.  The  physician  should  wear  a  gown  and  thoroughly  disinfect 
his  hands  and  other  exposed  parts  after  the  visit.  Special  care  must  be 
taken  with  the  thermometer  and  other  instruments.  The  physician  may 
find  the  necessary  precautions  and  disinfection  to  be  irksome,  but  they 
should  not  be  shirked  in  justice  to  his  other  patients  and  the  community. 

The  discharges  from  the  mouth,  nose,  and  respiratory  passages,  etc., 
should  be  collected  upon  suitable  fabrics  and  burned.  Bed  and  body 
clothing,  dishes,  and  other  exposed  objects  must  be  disinfected.  Care 
must  be  taken  concerning  remnants  of  food  from  the  sick  room. 

Scarlet  fever  is  not  as  highly  contagious  as  measles,  but  the  meas- 
ures employed  should  be  practically  the  same  until  at  least  we  have 
more  definite  knowledge  concerning  the  channels  of  entrance  and  exit 


224     DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 

of  the  virus  and  its  modes  of  transmission.  The  virus  of  scarlet 
fever  is  more  resistant  than  that  of  measles.  It  clings  persistently  to 
clothing  and  various  objects.  A  terminal  fumigation  with  formaldehyd 
gas  may  be  practiced,  although  little  seems  to  be  gained  thereby.  A 
thorough  cleansing  of  all  surfaces,  with  a  good  sunning  and  airing  of 
the  room,  is  always  in  order.  All  fabrics  and  other  objects  that  have 
been  exposed  should  be  disinfected.  The  virus  is  killed  with  agents 
that  destroy  non-spore-bearing  bacteria.  In  Glasgow  a  sanitary  wash- 
house  has  been  established,  where  the  clothing  of  scarlet  fever  cases  may 
be  disinfected  and  washed.  This  is  a  commendable  example  that  might 
be  followed  with  advantage  by  other  cities.  The  prevention  of  nephritis, 
which  is  a  frequent  and  serious  sequel  of  scarlet  fever,  consists  in  abso- 
lute rest  in  bed  for  four  weeks  even  in  the  mildest  cases,  and  a  low 
protein  diet — chiefly  bread  and  milk. 

Specific  Prophylaxis. — Attempts  at  artificial  immunity  by  inocu- 
lation have  failed  because  the  inoculated  disease  does  not  prove  milder, 
as  in  the  case  of  smallpox.  Whether  immunity  may  be  secured  through 
general  hygiene  is  doubtful,  although  good  care  of  the  teeth  and  gums, 
normal  tonsils  and  healthy  mucous  membranes  of  the  throat  may  afford 
some  protection. 

Gabritschewsky  first  proposed  the  use  of  streptococcus  vaccines  as  a 
prophylaxis  against  scarlet  fe^'er.  The  results  of  streptococcal  vaccines 
in  Russia  indicate  that  vaccinated  persons  contract  the  disease  in  from  0 
to  8.5  per  cent,  in  different  villages  as  contrasted  with  13.3  per  cent,  to 
70.6  per  cent,  in  unvaccinated.  Of  ninety-one  unvaccinated  persons  re- 
ported by  Smirnoff,  37.3  per  cent,  developed  scarlet  fever  as  contrasted 
with  3.93  per  cent,  of  127  vaccinated.  The  value  of  these  vaccines  for 
scarlet  fever  needs  confirmation  and  until  more  evidence  is  obtained  we 
must  remain  skeptical  as  to  their  prophylactic  value. 

Moser^s  polyvalent  antistreptococcus  serum  has  been  used  in  the 
treatment  of  the  disease,  but  has  not  been  advocated  as  a  prophylactic. 


WHOOPING-COUGH 

(Pertussis) 

Whooping-cough  occurs  in  epidemics,  which  vary  greatly  in  viru- 
lence, intensity,  and  mortality.  The  disease  is  more  frequent  and  severe 
in  cold  climates;  otherwise  uninfluenced  by  season  and  weather.**  The 
cause  of  whooping-cough  is  a  small  bacillus,  described  by  Bordet  and 
Gengou,  recognized  by  agglutination  and   complement  fixation  tests.*^ 

"In  New  York,  most  cases  during  the  past  10  years  occurred  during  the 
spring  and  summer. 

*^Ann.  de  VInst.  Pasteur,  Vol.  XX,  1906,  p.  731. 


WHOOPING-COUGH  225 

This  bacillus  is  found  most  readily  in  the  l)eo:inning  of  the  disease,  in 
the  matter  from  the  depths  of  the  bronchi  brought  up  during  the  par- 
oxysms. In  this  exudate,  whicli  is  white,  thick,  and  rich  in  leukocytes, 
the  bacilli  exist  in  considerable  numbers  and  sometimes  in  almost  pure 
culture. 

In  the  early  catarrhal  stages  it  is  ditlicult  to  obtain  sputum.  The 
bacillus  can  bo  isolated  by  holding  a  Petri  dish  with  suitable  medium 
close  to  the  child's  mouth  while  coughing.  It  is  rare  to  find  the  Bordet- 
Gengou  })ncillus  after  the  fourth  week. 

Mode  of  Transmission. — Whooping-cough  is  usually  transmitted 
directly  from  person  to  person  in  the  same  ways  that  diphtheria  and 
other  infections  contained  in  the  secretions  of  the  mouth  and  nose  are 
spread.  Handkerchiefs,  toys,  drinking  cups,  roller  towels,  and  other 
objects  recently  contaminated  with  the  infective  secretions  may  act  as 
vectors.  It  is  also  transmitted  by  droplet  infection,  kissing  and  close 
contact.  In  60  per  cent,  of  the  cases  studied  in  New  York,  the  source  of 
infection  was  given  as  coming  from  a  neighbor  (Luttinger).**'  Parents 
are  prone  to  contract  the  disease  from  their  children. 

Jahn  and  others  called  attention  to  the  fact  that  domestic  animals 
may  be  affected  by  whooping-cough,  and  that  they  may  be  the  means  of 
transmitting  it  to  children.  Coughs  of  a  paroxysmal  nature  have  been 
observed  in  dogs,  and  also  in  cats.  Klimenco  *^  and  Fraenkel  ^^  were  able 
to  produce  what  seemed  like  typical  pertussis  in  monkeys,  and  Inabo  ^^ 
showed  that  injection  of  the  bacillus  in  an  ape  gave  rise  to  a  typical 
whooping-cough  with  an  incubation  period  of  13  days.  Kittens  and  pup- 
pies do  not  take  the  disease  under  ordinary  circumstances  and  for  prac- 
tical purposes  of  prevention  are  usually  disregarded.  Mallory  and 
Horner  ^^  have  shown  that  masses  of  B.  hronchisepticus  are  found  in  the 
superficial  layer  of  the  trachea,  thereby  mechanically  paralyzing  the 
cilia.  Some  of  the  whooping-cough  of  animals  may  be  confused  with 
this  infection,  for  the  two  organisms  resemble  each  other  closely  ( Ferry 
and  Noble)." 

Whooping-cough  is  apparently  not  contagious  during  the  period  of 
incubation,  but  is  communicable  from  the  appearance  of  the  first  symp- 
tom, and  is  most  contagious  during  the  early  stage  before  the  whoop  de- 
velops. It  may  be  transmitted  in  the  late  stages  and  after  convalescence. 
While  the  virus  is  known  to  be  in  the  secretions  from  the  respiratory 
tract,  all  secretions  from  the  mouth  and  nose  (including  vomitus)  must 
be  regarded  as  infective. 

*^Bull  No.  1,9.  Dept.  of  Health,  N.  Y.  City,  Sept.,  1916. 

"CentralU.  f.  BakterioL,  1908,  XLVIII,  64. 

*^  Miinchen.  med.  Wochnschr..   1908.  LV.   1683. 

*^  Ztschr.  f.  Kinderh.,  June  15,  1912. 

'Vowr.  Med.  Res.,  Xov.,  1912,  XXVII,  2,  p.  115. 

^Wour.  Bad.,  May,  1918,  p.  19-'' 


226    DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 

Immuiiity. — There  is  no  natural  immunity  to  whooping-cough;  all 
are  susceptible.  WhoOping-cough  at  one  time  or  another  affects  almost 
every  member  of  a  community  and  causes  10,000  or  more  deaths  yearly 
in  this  country  alone.  The  greatest  susceptibility  is  between  6  months 
to  5  years.  After  5  years  the  susceptibility  decreases  with  age.  One  at- 
tack confers  a  definite  and  prolonged  immunity;  second  attacks  are 
rare. 

There  is  a  higher  incidence  and  mortality  among  girls  (56  per  cent.) 
than  boys  (44  per  cent.).  Whooping-cough  is  the  only  communicable 
disease  of  childhood  that  shows  this  peculiarity. 

The  death  rate  for  whooping-cough  in  the  United  States  in  1917 
was  10.4  per  100,000. 

Prevention. — The  incubation  is  probably  2  to  3  weeks,  but  the 
time  is  indefinite,  owing  to  vagueness  of  the  onset  of  symptoms.  If  16 
days  have  passed  without  symptoms  the  danger  may  be  considered  as  hav- 
ing passed.  For  practical  purposes  of  prevention  14  days  will  cover  most 
cases.  The  long-drawn-out  nature  of  the  disease,  the  difficulty  of  diag- 
nosis in  the  early  stages  when  it  is  most  contagious,  and  the  fact  that 
patients  sometimes  continue  to  spread  the  infection  for  4  to  6  weeks 
after  apparent  recovery,  make  the  control  of  whooping-cough  an  exceed- 
ingly difficult  problem.  Hence,  with  whooping-cough  we  have  the  same 
difficult  problem  that  confronts  us  in  the  prevention  of  measles.  Effec- 
tive measures  must  await  specific  prophylactic  methods. 

Whooping-cough  should  be  reported,  houses  placarded,  and  the  pa- 
tient isolated,  but  the  isolation  in  this  case  need  not  include  strict  con- 
finement to  a  room.  This,  in  fact,  may  be  an  unnecessary  hardship  to 
the  patient,  who  does  better  out  of  doors.  If  the  patient  is  permitted 
to  take  the  air,  he  must  avoid  contact  with  his  fellowmen  and  not  go 
to  school,  theater,  church,  public  assemblies,  nor  ride  in  st^-eet  cars  or 
public  vehicles.  Children  should  go  out  only  when  accompanied  by  an 
intelligent  caretaker  as  a  protection  to  others.  It  has  been  suggested 
that  children  with  whooping-cough  who  are  permitted  their  liberty 
should  be  plainly  labeled  with  a  red  cross  on  their  arm,  or  a  yellow 
flag,  or  the  word  "whooping-cough"  conspicuously  displayed  on  their 
clothing,  to  serve  as  a  warning  to  others.  Children  who  have  been  ex- 
posed should  be  isolated  as  soon  as  they  show  catarrhal  symptoms  or 
begin  to  cough,  not  waiting  for  the  characteristic  spasmodic  whoop.  Each 
community  should  provide  a  hospital-farm  for  children  with  whooping- 
cough  who  lack  proper  care. 

Early  diagnosis  and  prompt  reporting  of  cases  are  essential.  Other 
catarrhal  diseases  may  cause  paroxysmal  cough,  hence  a  positive  diag- 
nosis can  only  be  made  from  cultures.  Luttinger  states  that  only  about 
10  per  cent,  of  the  cases  of  whooping-cough  in  New  York  City  are  re- 
ported.   The  disease  is  most  communicable  during  the  catarrhal  or  early 


WHOOPING-COUGH  2«7 

stao-es,  vheu  the  infection  can  be  recognized  only  by  bacteriological 
methods. 

Patients  should  not  be  released  from  quarantine  until  at  least  4  weeks 
have  elapsed  after  the  onset  of  symptoms.  The  duration  of  isolation 
varies  in  different  cities;  thus  it  is  6  weeks  in  Montclair,  N.  J.;  on  re- 
covery in  Providence;  as  long  as  the  cough  lasts  in  Boston.  In  Michigan 
the  disease  is  considered  infectious  3  weeks  before  the  whoop  and  4  to  6 
weeks  after  apparent  recovery.  The  Danish  regulations  permit  release 
from  quarantine  after  four  weeks  and  two  negative  cultures.^^  The 
State  Board  of  Health  of  Michigan  requires  disinfection  of  the  clothing 
and  premises  before  the  patient  is  released,  and  forbids  public  funerals 
in  deaths  from  whooping-cough. 

Individual  prophylaxis  consists  in  avoiding  the  infection.  The  great- 
est care  in  this  regard  should  be  taken  with  children  before  the  age 
of  5  years.  Xinety-six  per  cent,  of  the  6,324  deaths  from  whooping- 
cough  in  the  United  States  in  1906  were  in  children  under  5  years  of  age. 
Dogs,  cats,  and  other  domestic  animals  should  be  kept  away  from  the 
patient,  and  the  possibility  of  conveying  the  disease  in  this  way  must 
be  guarded  against  in  the  susceptible. 

The  Bordet-Gengou  bacillus  is  frail  and  soon  dies  in  the  environ- 
ment; therefore,  terminal  fumigation  of  the  room  is  not  necessary, 
although  cleaning  and  airing  of  the  premises  are  in  order.  Handker- 
chiefs, fabrics,  toys,  and  other  objects  that  have  come  in  contact  with 
the  secretions  from  the  mouth  and  nose  should  be  boiled  or  saturated 
with  a  strong  germicidal  solution.  The  sputum  and  vomitus  should  be 
burned  or  disinfected  as  for  tuberculosis. 

Mild,  abortive,  and  missed  cases  spread  the  infection.  Most  cases  of 
whooping-cough,  however,  give  a  clear  history  of  recent  contact  with 
another  case. 

-  Whooping-cough  usually  runs  a  favorable  course  in  healthy  children 
over  five  years  old,  and  after  puberty  it  is  rarely  fatal.  The  most  im- 
portant thing  then  is  to  keep  babies  and  young  children  from  having  the 
disease.  Delaying  the  age  incidence  will  materially  decrease  the  mor- 
tality. Particular  care  should  be  taken  during  and  for  several  months 
following  convalescence  to  prevent  the  development  of  tuberculosis. 

Schools  need  not  be  closed  on'  account  of  whooping-cough.  Daily  in- 
spection of  pupils  may  achieve  better  results:  The  well  children  of  a 
household,  where  a  person  is  ill  with  whooping-cough,  should  be  excluded 
from  schools  unless  they  have  had  the  disease  or  until  two  weeks  have 
elapsed  since  the  last  exposure,  and  then  only  provided  they  are  free 
from  catarrhal  symptoms.  Other  members  of  the  household  may  be 
allowed  to  follow  their  usual  occupations. 

Hess  and  others  have  recently  used  vaccines  of  the  Bordet-Gengou 

•^Chievitz  and  Meyer:     Ann.  de  I'Inst.  Pasteur,  1916,  30,  p.  503. 


228     DISEASES  FROM  DISCHAEGES  OF  MOUTH  AND  NOSE 

bacillus  as  a  prophylactic  with  seeming  success.  The  evidence  so  far 
shows  no  striking  protective  power  of  these  vaccines.  The  immunity 
produced  is  slight  if  any.     The  subject  is  being  studied. 

The,  control  of  whooping-cough  is  a  matter  which  is  largely  in  the 
hands  of  the  public  itself.  The  dangerous  nature  of  this  infection 
should  be  emphasized,  and  people  taught  that  it  is  contagious  both  be- 
fore and  after  the  "whoop."  Mild  cases  which  do  not  have  the  charac- 
teristic whoop  spread  the  disease ;  this  is  especially  common  in  adults. 

Mortality. — The  dangerous  nature  of  whooping-cough  is  not  gen- 
erally realized.  "\\Tiooping-cough  almost  everywhere  causes  more  .deaths 
than  scarlet  fever.  Many  deaths  registered  as  bronchitis  and  broncho- 
pneumonia are  secondary  to  whooping-cough;  during  the  summer, 
gastro-intestinal  complications  are  serious  in  young  children.  In  the 
United  States  in  1910  the  death  rate  per  100,000  was  as  follows :  Whoop- 
ing-cough 11.4;  scarlet  fever  11.6;  measles  12.3;  and  diphtheria  21.4.  In 
Glasgow  the  annual  mortality  from  whooping-cough  for  40  years,  1855- 
1894,  was  13.5  per  hundred  thousand  inhabitants,  and  exceeded  that 
from  any  other  acute  communicable  disease.  In  England  and  Wales  in 
1891  more  deaths  occurred  from  whooping-cough  than  from  measles, 
diphtheria,  scarlet  fever,  or  typhoid  fever.  The  mortality  figures  would 
be  still  higher  if  all  the  deaths  directly  or  indirectly  due  to  it  were  com- 
pletely reported,  for  the  fatal  termination  is  usually  due  to  complica- 
tions and  sequelae  which  occur  in  one-fourth  to  one-third  of  all  cases. 
As  a  result  of  these  complications  the  original  disease  is  frequently  lost 
sight  of  entirely  in  the  vital  statistics.  According  to  Farr's  law — that 
contagious  diseases  increase  as  density  of  population  increases — the 
death  rate  from  whooping-cough  in  our  country  will  undoubtedly  in- 
crease in  our  more  sparsely  settled  states  with  increasing  population  and 
rapidly  extending  lines  of  railroad  and  other  facilities,  and  with  easy, 
frequent,  and  rapid  movements  of  the  people. 

The  gravity  of  v/hooping-cough  is  scarcely  appreciated,  either  by  the 
physician  or  the  public,  and  there  is  much  heedless  neglect  with  reference 
to  the  prevention  of  this  infection. 

MUMPS 

{Epidemic  Parotitis) 

Mumps  usually  occurs  between  the  ages  of  5  to  15  years.  There  is 
decreased  susceptibility  both  before  and  after  this  time.  It  is  a  disease 
of  children  and  young  adults.  As  a  military  problem,  mumps  frequently 
occurs  in  men  between  21  and  31  years.  In  the  soldier  and  sailor  the 
infection  is  dreaded  because  it  is  disabling  and  unmanageable.  In  1918, 
there  were  5,756  cases  of  mumps  among  18,000  men  at  Camp  Wheeler, 


MtJMl'S  229 

an  incidt'iice  of  32  per  cent.  One  ailnck  usually  coiit'iTs  iinniunilv.  hut 
second  attacks  occur,  and  third  attacks  arc  sonictinics  rcpoi'tcd.  The 
disease  may  occur  as  epidemics  in  civil  institutions  and  military  estah- 
lishmcnts.  which  usually  develop  slowly  and  last  a  Iowj:  (inie.  Tt  is  diffi- 
cult to  trace  and  eradicate.  Orchitis  is  a  frequent  and  ])ainful  complica- 
tion and  when  hoth  testicles  are  involved  may  cause  sterility.  Other 
complications  are:  great  prostration;  a  tendency  to  develop  mania,  or 
wild  delirium,  or  a  comatose  state  reseml)ling  uremia;  meningism, 
mastitis,  otitis  media,  tonsillitis,  and  pneumonia  also  occur.  Mumps  is 
contagious  before  the  symptoms  appear,  and  for  some  time,  even  6  weeks, 
after  symptoms  have  disappeared.  It  is  probahly  transmissible  as  long 
as  the  glands  are  sw^ollen.  The  parotids  are  most  frequently  involved, 
ne::t  the  subnui.xillary,  and  last  the  sublingual.  The  lachrymal  glands 
escape.  The  disease  is  usually  spread  by  direct  contact;  rarely  by 
indirect  contact  or  by  a  third  person.  It  is  not  air-borne.  The  virus 
is  contained  in  the  secretions  from  the  mouth  and  perhaps  the  nose. 
The  incubation  is  variously  stated  at  from  4  to  25  days;  it  is  variable 
and  sometimes  prolonged.  For  public  health  purposes  the  maximum 
period  of  incubation  is  placed  at  21  days. 

Granata  in  1908^  and  Nicolle  and  Conseil  ^^  in  1913  obtained  indi- 
cations that  mumps  may  be  due  to  a  filterable  virus ;  ]\Iartha  Wollstein  ^* 
in  1918  showed  that  the  salivary  secretion  in  mumps  contains  a  virus, 
which  when  filtered  and  injected  into  the  parotid  glands  and  testicles 
of  cats,  causes  pathological  changes  resembling  mumps  in  human  beings. 

The  virus  is  detected  most  readily  in  the  saliva  during  the  first  three 
days  of  the  disease,  less  easily  on  the  6th,  and  not  at  all  on  the  9th  day. 
It  is  also  present  in  the  blood  of  patients  showing  marked  constitutional 
symptoms,  but  not  in  the  cerebrospinal  fluid. 

Mumps  is  required  to  be  reported  in  Maryland,  Grand  Eapids,  and 
Raleigh,  and  placarded  in  Cleveland.  Prevention  depends  upon  the 
usual  practice  of  isolation  and  disinfection. 

Hess  ^''  injected  6  to  8  c.  c.  of  blood  of  convalescents  intramuscularly 
into  17  children.  ISTone  of  these  children  developed  mumps,  although 
exposed  to  it  in  an  institution  where  the  disease  was  epidemic.  If  con- 
firmed, this  procedure  could  be  made  use  of  in  the  home  as  well  as  in 
institutions. 

Orchitis  occurs  as  a  complication  in  as  high  as  25  per  cent,  of  the 
cases.  It  is  rare  before  puberty.  There  is  some  support  for  the  old 
suggestion  that  the  infection  is  conveyed  to  the  testicles  by  hand-urethral 
inoculation,  but  more  likely  the  virus  is  brought  to  the  testicles  by  the 
blood  stream.     Traumatism  of  the  testicles  predisposes  to  orchitis,  hence 

''  Conipt.  rend.  Aead.  d.  Sc,  1913,  CLVII,  340. 

"Joi.m.  Exp.  Med.,  March,  1916,  pp.  265-429;   Oct.   1,  1918,  p.  337. 

"Proceed.  Soc.  f.  Exp.  Biol,  and  Med.,  Apr.  21,  1915,  XII,  7,  p.  144. 


230    DISEASES  FROM  DISCHAEGES  OF  MOUTH  AND  NOSE 

iiijurious    palpation    and    injuries    however    slight    should   be   avoided. 
Rest  in  bed  is  also  a  prevention. 


LOBAR  PNEUMONIA 

Lobar  pneumonia  is  a  communicable  disease  which  should  be  classi- 
fied with  the  infectious  fevers.  If  pneumonia  were  a  new  disease  it 
would  be  regarded  as  "contagious/'  and  its  spread  would  be  guarded 
against  by  isolation  and  the  application  of  antiseptic  principles.  Many- 
different  infections  are  caused  by  the  pneumococcus,  but  here  we  will 
consider  only  the  specific  self-limiting  disease  associated  with  involve- 
ments of  one  or  more  lobes  of  the  lung,  known  as  fibrinous,  lobar,  or 
croupous  pneumonia — also  lung  fever.  The  pneumonia  considered  in 
this  article  is  an  acute,  self-limiting,  febrile  disease  caused, by  one  of 
the  pneumococci.  The  pneumococcus  is  the  common  cause  of  pneumonia, 
but  pneumonitis  may  also  be  caused  by  a  long  list  of  other  pathogenic 
microorganisms,  such  as  streptococci,  influenza  bacilli,  Friedlander's 
bacilli,  plague  bacilli,  typhoid  bacilli,  etc.  A  pneumonic  condition  of 
the  lung  is  also  a  frequent  terminal  state,  especially  in  the  young  and 
in  the  old.  Owing  to  these  facts,  there  is  much  confusion  in  the  litera- 
ture as  well  as  in  the  morbidity  and  mortality  records  concerning 
pneumonia. 

The  pneumococcus  is  found  not  alone  in  the  local  lung  lesions,  but 
also  invades  the  blood.  When  this  happens  in  large  numbers  it  increases 
the  seA'erity  of  the  disease.  The  pneumococcus  has  a  capsule  and  is 
soluble  in  bile.  It  also  gives  specific^,  immunity  reactions,  especially  ag- 
glutination and  precipitin  tests. 

Pneumonia  is  one  of  the  most  prevalent  and  fatal  of  all  acute  diseases. 
As  a  cause  of  death  it  rivals  and  sometimes  exceeds  tuberculosis.  Accord- 
ing to  the  U.  S.  Census  of  1890,  over  9  per  cent,  of  all  deaths  were 
due  to  pneumonia,  10.2  per  cent,  in  1900,  9.8  per  cent,  in  1910,  and  9.7 
per  cent,  in  1915.  The  death  rate  varies.  In  the  United  States  it  was 
127  per  100,000  in  1914,  and  119.8  in  1917  and  still  higher  during  the 
influenza  pandemic  of  1918-19.  Pneumonia  is  probably  on  the  increase, 
owing  to  factors  favoring  the  spread  of  the  infection,  especially  crowd- 
ing; and  also  to  certain  devitalizing  influences  of  modern  life  which 
heighten  susceptibility  to  the  disease;  further,  more  persons  are  now 
saved  from  the  acute  and  fatal  infections  of  childhood  and  adolescence 
to  become  victims  of  pneumonia  later  in  life. 

Pneumonia  occurs  in  all  climates:  it  is  prevalent  in  tropical  as  well 
as  in  cold  countries.  Like  other  communicable  infections,  it  shows  geo- 
graphic differences:  thus,  it  is  more  virulent  in  the  United  States  than' 
In  England.  This  is  said  to  be  due  to  the  dry,  overheated  air  of  our 
homes,  offices  and  work  rooms. 


LOBAR  TNEUMONIA  231 

Pneumonia  shows  a  distinct  seasonal  prevalence:  it  is  most  frequent 
in  tlie  Avintcr  and  sprinsf  months.  This  is  not  necessarily  accounted  for 
hy  the  chilliii,<r  cH'octs  of  cold  moist  air.  for  Crccuherg  has  shown  that  a 
low  rclatJNt'  Immidity  is  conduciNc  to  a  liiijli  dcalh  rate'"'"  Cold,  wet- 
ting and  chilling  are  generally  regarded  as  important  predisposing 
causes.  They  may  favor  autoinfection  through  inspiration,  or  may  lower 
the  resistance  of  the  hroncliinl  and  jjidmonary  tissues.  Fatigue,  or  some 
unusual  exertion,  also  ])hiys  a  ]iart  here.  Pneumonia  is  often  preceded 
by  an  ordinary  catarrhal  inflammation.  Cold  and  crowding  also  favors 
the  spread  of  other  respiratory  infections,  such  as  pneumonic  plague, 
common  colds,  sore  throats,  etc. 

Pneumonia  is  fatal  among  negroes  to  a  greater  extent  than  among 
whites;  and  is  more  frequent  in  males.  It  attacks  all  ages.  The  inci- 
dence is  marked  at  both  extremes  of  life.  It  is  common  in  children  under 
six  j'ears ;  between  the  sixth  and  fifteenth  year  the  predisposition  is  less 
nmrked,  but  for  each  subsequent  decade  it  increases.  The  relation  to  age 
is  well  shown  in  the  United  States  Census  Report  for  1900.  The  death 
rate  from  pneumonia  in  persons  from  15  to  45  years  was  100.5  per 
100,000  population;  from  45  to  65  years,  it  was  263.12;  and  in  persons 
65  years  and  over  it  was  733.77 !  Osier  says,  "Pneumonia  may  well  be 
called  the  friend  of  the  aged.  Taken  off  by  it  in  an  acute,  short,  not  often 
painful  illness,  the  old  escape  those  'cold  gradations  of  decay'  that  make 
the  last  stage  of  all  so  distressing."  Pneumonia  often  attacks  the 
strong  and  robust  in  early  adult  life,  but  under  these  circumstances  the 
chances  of  recovery  are  good. 

Types  of  Pneumococci. — Four  groups  or  types  of  pneumococci  are 
now  recognized,  based  upon  immunological  reactions.  In  three  of 
the  groups  these  reactions  are  fixed  and  specific.  This  grouping  is 
important  both  from  the  standpoint  of  treatment  and  prevention. 
-  Group  I  is  found  in  about  33  per  cent,  of  all  cases  of  pneumonia, 
and  has  a  mortality  of  about  25  to  30  per  cent,  of  cases  caused  by  it. 
With  the  use  of  specific  serum  the  mortality  has  been  reduced  to  about 
6  or  8  per  cent.  This  type  of  pneumococcus  is  rarely  found  except  in 
cases  of  pneumonia,  or  in  healthy  carriers  closely  associated  with  cases. 
Carriers  of  this  type  are  temporary. 

Group  II  is  indistinguishable  from  Group  I  save  by  the  agglutination 
reaction.  It  is  found  in  about  33  per  cent,  of  all  cases  of  pneumonia, 
and  has  a  mortality  of  about  25  to  30  per  cent.  An  immune  serum  has 
been  produced  for  this  group,  but  it  has  feeble  therapeutic  power. 
Healthy  carriers  are  temporary  and  infrequent,  and  only  found  in  per- 
sons who  have  been  in  contact  with  cases  of  Type  II  pneumonia. 

A  number  of  atypical  members  of  this  group  are  now  classified  as 
sub-group  II. 

^J.  A.  M.  A.,  Jan.  25,  1919. 


232     DISEASES  FEOM  DISCHARGES  OF  MOUTH  AND  NOSE 

Group  III  is  the  pneumo coccus  mucosu^,  formerly  confused  with  the 
streptococcus  mucosus.  These  pneumococci  are  distinguished  not  only 
by  specific  immunological  reactions,  but  by  the  fact  that  they  have  a 
large  capsule,  and  colonies  on  solid  media  form  an  abundant,  sticky, 
mucoid  growth.  This  type  is  the  cause  of  about  10  to  15  per  cent,  of 
all  pneumonia,  and  is  fatal  in  about  50  to  60  per  cent,  of  cases.  While 
infrequent  it  is  malignant.  No  therapeutic  serum  of  practical  value 
has  been  obtained  against  this  type  of  infection.  Healthy  carriers  occur, 
but  do  not  give  a  history  of  close  association  with  pneumonia. 

Group  IV  comprises  all  pneumococci  that  do  not  belong  to  groups 
1,  II  or  III.  The  strains  in  this  group  are  not  specific.  They  are  fre- 
quently found  in  normal  mouths.  These  organisms  have  a  comparatively 
lower  virulence,  causing  about  20  per  cent,  of  cases,  but  under  certain 
conditions  strains  of  Group  IV  may  have  an  exalted  virulence  as  in  the 
Rand  miners  in  South  Africa. 

These  four  groups -seem  quite  stable  and  show  no  tendency  to  muta- 
tion. The  percentage  of  incidence  and  death  rates  naturally  varies  with 
time  and  place;  however,  the  Rockefeller  figures  given  above  have  been 
fairly  consistent  from  year  to  year,  and  the  figures  obtained  by  others 
have  not  varied  widely  from  those  stated. 

The  pneumococci  of  the  first  two  groups  caused  about  65  per  cent,  of 
all  cases  of  pneumonia  in  the  United  States,  during  the  years  studied. 
They  occurred  only  in  the  mouths  of  people  recovering  from  the  disease  or 
of  those  in  direct  contact  with  such  cases.  From  these  results,  pneu- 
monia was  a  contact  disease  in  at  least  65  per  cent,  of  cases,  the  infection 
being  obtained  from  a  patient  or  carrier. 

Resistance  of  the  Virus. — The  pneumococcus  is  a  frail  organism;  it 
does  not  multiply  in  nature  outside  of  the  body  and  indirect  trans- 
mission is  not  likely  except  with  fresh  infectious  material.  Even  upon 
artificial  culture  media  the  life  of  the  pneumococcus  is  brief;  it  must 
be  transplanted  frequently  in  order  to  keep  it  alive;  it  is  customary  in 
laboratories  to  pass  it  through  a  susceptible  animal,  such  as  a  mouse  or 
rabbit,  from  time  to  time,  in  order  to  maintain  its  virulence. 

The  pneumococcus  is  readily  destroyed  by  heat;  52°  C.  for  10  min- 
utes is  sufficient.  On  the  other  hand,  it  withstands  low  temperatures 
very  well.  The  ordinary  germicidal  agents  destroy  it  quickly  and  with 
certainty.  It  may  live  for  months  in  dried  sputum,  in  which  it  also 
maintains  its  virulence.  It  has  been  found  in  the  dust  of  rooms  occu- 
pied by  cases  or  carriers,  and  may  persist  for  weeks. 

Modes  of  Transmission. — The  pneumococcus  leaves  the  body  mainly 
in  the  discharges  from  the  mouth  and  nose,  and  enters  the  system 
through  the  same  channels.  The  infection  is  spread  directly  by  close 
personal  contact,  also  indirectly  through  the  great  variety  of  ways  dis- 
cussed under  diphtheria  and  tuberculosis.  Indirect  transmissions  through 


LOBAR  PNEUMONIA  233 

cups,  fiii^'cvs,  haiKlkcrcliicrs,  and  dtlici-  (tliji'cts  coiilaiiiiiiiitcd  witli  fresh 
discharges  nia}'  occur;  haiKl-io-inoiith  and  di'()])lcl  inlVction  also  come 
into  consideration. 

Pneumonia  is  s])read  chiefly  by  close  personal  contact  witli  cases  or 
carriers.  Carriers  of  the  pneumococci  may  infect  themselves  hy  inspira- 
tion. The  effect  of  crowding  is  well  shoAvn  l)y  the  fact  that  the  disease 
is  more  prevalent  in  cities  than  in  country  districts. 

Pneumonia  occurs  in  well-marked  epidemics.  Wells  gives  an  exhaus- 
tive tabulation  of  the  e])ideniics  of  pneumonia  extendiiig  back  to  1440.-" 
Epidemics  of  pneumonia  have  occurred  in  all  parts  of.  the  world:  in 
Alaska,  at  Erlangen,  Boston,  Ireland,  Italy,  France,  Switzerland,  and 
on  board  ships.  The  disease  has  also  been  observed  to  spread  in  hospitals 
and  in  houses.  The  excessive  prevalence  of  pneumonia  often  found  in 
camps,  barracks  and  among  working  people,  as  at  Panama  and  at  the 
African  mines,  is  due  to  contact  infection  resulting  from  crowding  of 
susceptible  people. 

Pneumonia  as  a  complication  of  influenza  became  one  of  the  chief 
causes  of  death  in  our  army  in  the  World  War.  It  is  quite  proper 
to  regard  pneumonia  as  endemic  everywhere,  with  occasional  epidemic 
outbreaks. 

The  workers  of  the  Rockefeller  Institute  examined  175  specimens  of 
dust  from  houses  with  cases  of  pneumonia  due  to  Type  I  or  Type  II.  In 
75  of  these  specimens,  pneumococci  were  found,  and  in  47  they  were 
Type  I  or  Type  II,  and  in  all  these  cases,  but  two,  the  type  of  pneu- 
mococcus  found  in  the  dust  corresponded  in  type  to  that  isolated  from 
the  patient.  On  the  other  hand,  in  62  specimens  of  dust  obtained  from 
houses  in  which  no  cases  of  pneumonia  were  known  to  exist,  pneumococci 
were  isolated  18  times,  but  in  only  one  instance  were  pneumococci  of 
the  fixed  Types  I  or  II  present,  and  in  this  one  instance  a  known 
carrier  of  the  corresponding  fixed  type  was  found  to  be  visiting  at  the 
time.  Dust  transmission  is  therefore  to  be  feared  and  measures  taken 
accordingly. 

Carriers.— Pneumococci  are  frequently  found  in  the  mouths  and 
throats  of  healthy  persons.  Sternberg  in  1880  first  demonstrated  a  pneu- 
mococcus  in  his  own  saliva.  Netter  found  it  in  20  per  cent,  of  the 
persons  whom  he  examined,  and  the  New  York  Commission  reported 
its  presence  in  from  48  to  85  per  cent.  In  other  M^ords,  the  majority  of 
persons  seem  to  be  pneumococcus  carriers.  One  fortunate  feature  of  this 
situation  is  the  fact  that  practically  all  the  common  mouth  pneumococci 
belong  to  Group  IV,  which  has  a  low  virulence.  Pneumococci  of  Types 
I  and  II  usually  disappear  from  the  mouth  within  a  few  weeks  after 
convalescence  is  established,  the  longest  time  so  far  observed  being  83 
days.  Practically  the  same  facts  apply  to  the  persistence  of  these  types 
"J.  A.  M.  A.,  Feb.  23,  1889.     Med.  News,  May  20,  1905. 


234    DISEASES  FROM  DISCHAEGES  OF  MOUTH  A^Tf  NOSE 

of  pneumococci  in  the  mouths  of  healthy  carriers.  In  other  words, 
carriers  of  these  types  are  temporary,  not  very  numerous,  and  almost 
always  give  a  history  of  recent  association  with  a  case  of  pneumonia. 

On  the  other  hand,  carriers  of  Type  III  and  Type  IV  are  very  nu- 
merous and  persistent.  Type  III  is  our  most  severe  type  of  pneumonia, 
although  it  occurs  only  relatively  infrequently.  Cole  found  pneumo- 
cocci of  Type  III  85  times  among  450  healthy  carriers.  Practically 
none  of  these  was  associated  with  cases  of  pneumonia.  Moreover,  this 
type  may  he  carried  for  years. 

Stillman  ^^  found  that  Type  IV  predominates  in  the  mouths  of 
healthy  individuals,  that  Type  III  is  fairly  frequent,  and  that  atypical 
organisms  of  Type  II  are  usually  associated  with  eases  of  pneumonia,  al- 
though occasionally  it  is  impossible  to  trace  any  such  connection.  In 
these  cases,  it  is  probable  that  the  pneumococcus  was  contracted  from  a 
carrier  or  indirectly  through  cups,  spoons,  glasses  or  dust  from  a  case  of 
the  disease. 

These  facts  suggest  the  following  conclusions  concerning  the  epidemi- 
ology of  lobar  pneumonia.  Infection  with  pneumococcus  of  Types  I  and 
II  must  be  regarded  as  dependent  upon  either  direct  or  indirect  contact 
with  a  previous  case  of  lobar  pneumonia  due  to  the  same  type  of  organ- 
ism. These  types  of  infection  are  either  acquired  by  direct  contact 
with  a  previous  case  of  pneumonia,  by  association  with  a  healthy  carrier 
of  one  of  these  types  of  pneumococcus,  or  possibly  by  infection  from 
dust  or  objects  smeared  with  saliva.  Infection  with  the  common  sputum- 
types  of  pneumococcus,  namely  Types  III  and  IV,  and  the  atypical 
strains  of  Type  II,  may  be  autogenic,  or  brought  about  by  a  special  sus- 
ceptible.    No  known  measures  will  relieve  pneumococcus  carriers. 

Ethylhydrocuprein  hydrochlorid  has  special  pneumococcidal  activ- 
ity,^® and  has  been  recommended  to  disinfect  carriers.  Kolmer  and 
Steinfield  '^^  recommend  a  mouth  wash  and  gargle  of  the  following  for- 
mula: 

Ethylhydrocuprein  hydrochlorid  (or  quinin  bisulphid)    .005  gm. 
Liquor  thymolis  5.0      e.  c. 

Distilled  water  sufficient  to  make  50.0      c.  c. 

Immunity. — One  attack  of  pneumonia  does  not  leave  an  immunity. 
In  fact,  one  attack  predisposes  to  subsequent  attacks,  as  is  the  case  with 
erysipelas  and  rheumatic  fever.  Man,  however,  must  possess  a  certain 
degree  of  resistance  to  the  pneumococcus,  else  the  disease  would  be 
even  more  prevalent  than  it  is,  and  recovery  would  probably  be  less  fre- 

^^Journ.  Exp.  Med.,  Dec,   1916,  XXIV,  6,  651;   also  a  study  of  100  normal 
individuals  by  Jacob  Myer,  J.  A.  M.  A.,  Nov.  6,  1920,  Vol.  LXXV,  No.  19,  p.  1268. 
^^Morgenroth  and  Levy,  Berlin,  klin.  Woohn:schr.,  1911,  48. 
«V.  A.  M.  A.,  Jan.  5,  1918,  Vol.  70,  No.  1,  p.   14. 


LOBAR  PNEUMONIA  235 

qiient.  Recurrence  is  more  common  in  pneumonia  than  in  any  other 
acute  disease.  Instances  are  on  record  of  individuals  wlio  have  had  10 
or  more  attacks.  Kush  <;ivos  an  instance  in  which  Ihrre  were  28  attacks. 
All  kinds  of  animals,  even  the  most  susce])tihl(',  inav  Ix'  rendered 
actively  immune  to  ])ii<'umococcus  infection  by  the  previous  injection  of 
non-lethal  doses  of  livinij  ])neumococci,  or  cvcti  by  the  injection  of  the 
dead  cocci.  The  serum  of  sudi  actively  immunized  animals,  in  many 
cases,  possesses  protective  and  oven  curative  power.  'J'he  chief  anti- 
bodies which  can  be  demonstrated  in  this  immune  serum  are  agglu- 
tinins and  opsonins  or  bacteriotrophins. 

The  mechanism  of  the  immunity  to  this  infection  is  not  at  all  un- 
derstood. Phagocytosis  may  play  a  prominent,  perhaps  a  dominant, 
role.  Protective  antibodies,  rather  feeble,  have  been  found  in  the  blood 
serum  of  immunized  animals,  and  also  in  the  blood  serum  of  persons 
who  have  recovered  from  pneumonia.  The  pneumococcic  attack,  espe- 
cially the  crisis,  resembles  an  anaphylactic  reaction,  and,  while  the 
mechanism  of  immunity  in  this  infection  is  probably  complex,  the  best 
explanation  of  it  at  present  is  in  terms  of  anaphylaxis.  The  immunity 
is  quite  specific. 

Many  weakening  diseases  diminish  resistance  to  the  pneumococcus. 
Pneumonia  is  frequent  in  alcoholics  and  is  commonly  brought  on  by 
exposure  to  cold,  to  trauma,  or  to  local  irritation.  It  is  a  frequent 
complication  of  influenza,  measles,  whooping-cough,  typhoid  fever  and 
other  infections.  Pneumonia  often  closes  the  scene  in  chronic  heart 
disease,  pulmonary  phthisis,  Bright's  disease,  diabetes  and  other  debili- 
tating affections. 

Immaturity  and  old  age,  as  well  as  other  enfeebling  conditions, 
may  act  as  a  predisposing  cause  by  lowering  immunity.  Other  factors 
which  predispose  to  pneumonia  are  sudden  changes  in  temperature, 
trauma,  irritation  caused  by  aspiration  of  foreign  substances,  or  the  in- 
halation of  dust  or  irritating  vapors. 

It  should  be  remembered  that  pneumonia,  like  other  communicable 
infections,  frequently  attacks  the  strong  and  robust. 

Fatigue,  exposure  and  overexertion  have  long  been  recognized  as 
contributing  causes  of  pneumonia.  Fatigue  and  overexertion  favor  the 
inspiration  of  infectious  material  into  the  trachea.  Blake  and  Cecil  ^^ 
have  produced  pneumonia  in  monkeys  simply  by  injecting  small  amounts 
of  a  pure  culture  by  means  of  a  fine  needle  into  the  trachea.  Kinyoun 
and  Eosenau,  also  Meltzer  and  his  colleagues  have  produced  pneumonia 
by  intratracheal  insufflation  of  large  amounts  into  dogs. 

The  pneumococcus  is  particularly  virulent  when  it  attacks  races  in 

^Jour.  Exp.  Med.,  Apr.  1.  1920,  Vol.  XXXI,  No.  4,  pp.  403,  445;  May  1, 
1920,  No.  5,  pp.  499,  .519;  June  1,  1920.  No.  6,  pp.  657,  685:  July  1.  1920,  Vol. 
XXXII,  No.  1,  p.  1;  Oct.  1,  1920,  No.  4,  p.  401;  Dec.  1,  1920,  No.  6,  pp.  691,  719, 


23G    DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 

which  the  disease  has  not  been  prevalent.  This  was  the  case  with  the 
laborers  on  the  Panama  Canal  and  the  miners  on  the  Eand.  Such  cir- 
cumstances indicate  that  a  certain  amount  of  racial  resistance  is  acquired 
through  long  conflict  with  the  pneumococcus. 

Prevention. — Vaccines  are  now  being  tried  as  a  prophylactic  against 
pneumonia.  The  I'etically,  we  might  expect  it  to  be  a  hopeless  task  to 
produce  by  artificial  methods  a  useful  immunity  to  a  disease  which 
leaves  little  or  no  natural  immunity;  in  fact  one  attack  predisposes  to 
recurrences.  On  the  other  hand,  a  high  degree  of  protection  can  easily  be 
induced  in  susceptible  animals  to  virulent  cultures  of  pneumococci  when 
injected  into  the  peritoneal  cavity,  the  blood  stream,  or  subcutaneously. 
The  results  of  preventive  inoculation  upon  man  are  encouraging,  but 
must  await  some  years  of  careful  observation,  with  controls,  before  we 
know  the  quality  of  the  protection  afforded  and  the  proper  vaccine  to 
use. 

Following  the  promising  but  inexact  experiments  of  Wright  in  South 
Africa,  Lister  ®^  carried  out  prophylactic  immimization  in  a  large  num- 
ber of  Eand  mine  workers,  using  a  composite  vaccine  made  from  pneu- 
mococcus types  prevalent  in  that  region.  He  found  that  subcutaneous 
injections  protected  against  the  types  used  in  the  vaccines. 

Cecil  and  Austin  ^^  inoculated  some  12,000  seasoned  troops  (20  per 
cent,  of  the  command)  at  Camp  Upton,  with  a  saline  pneumococcus  vac- 
cine containing  Types  I,  II  and  III.  Three  or  four  doses  were  given 
at  weekly  intervals,  the  first  containing  three  billion  organisms,  and  the 
final  doses  from  six  to  seven  and  one-half  billions.  While  the  period  of 
observation  after  the  inoculation  was  only  ten  weeks,  evidence  of  protec- 
tion was  made  apparent  by  the  fact  that  no  cases  of  pneumonia  of  Types 
I,  II  or  III  occurred  in  the  vaccinated  groups,  while  26  cases  due  to  these 
types  originated  in  the  unvaccinated  groups.  Only  17  cases  of  pneumo- 
nia of  all  types  developed  among  the  vaccinated  as  contrasted  with  172 
cases  among  the  unvaccinated  men. 

Cecil  and  Vaughan  ®*  immunized  80  per  cent,  of  the  command  at 
Camp  "^Tieeler.  The  conditions  here  differed  materially  from  those  at 
Camp  Upton  in  several  respects:  (1)  a  larger  number  of  the  troops  were 
recruits,  and  hence  more  susceptible;  ^°  (2)  the  work  was  complicated  by 
the  influenza  epidemic;  (3)  a  lipovaccine  was  substituted  for  the  saline 
vaccine.  This  vaccine  contained  the  3  types  of  pneumococci  in  a  dos- 
age of  10  billion  organisms,  and  only  one  injection  was  required.  Dur- 
ing a  period  of  three  months,  363  cases  of  pneumonia  of  all  varieties 
occurred  among  the  men  vaccinated  (80  per  cent,  of  the  command),  and 
327  cases  among  the  unvaccinated  troops  (20  per  cent,  of  the  command). 

«^So.  African  Inst,  for  Med.  Eesearch,  10,  1917. 

«J.  Exper.  Med.,  XXVIII,  19,  Julv,  1918. 

"76/r/.,  XXIX.  457,  1919. 

^Opie,  E.  L.,  et  al.:  J.  A.  M.  A.,  72,  108,  Jan.  11,  1919;  72,  .556,  Feb.  22,  1919. 


LOBAR  PNEUMONIA  237* 

Only  S  cases  of  Types  I,  II,  and  III  developed  among  the  vaccinated 
men,  and  these  were  all  secondary  to  severe  cases  of  influenza.  This 
excellent  work  in  the  army  could  not  he  followed  up,  was  in  a  compli- 
cated situation,  and  is  therefore  not  conclusive. 

Pneumococcic  immunity  is  strictly  specific.  Vaccines  protect  only 
against  the  pneumonia  caused  hy  tliose  groups  represented  in  the  vac- 
cine. Much  more  work  will  have  to  he  done  before  a  statement  can  be 
made  concerning  the  prophylactic  value  of  these  measures.  Studies  are 
now  being  made  hy  a  Commission  "*'  upon  groups  involving  many  thou- 
sands with  equal  numbers  of  controls.  The  results  of  this  work  will  not 
be  known  for  several  years.  Antipneumocoecus  serum  is  useful  in  the 
treatment  of  Type  I  pneumonia  if  given  early  and  in  sufficient  amount, 
but  has  no  preventive  virtues. 

Preventive  Measures. — The  prevention  of  pneumonia  is  rapidly  be- 
coming more  definite  through  a  better  understanding  of  the  causes  of  the 
infection,  and  the  factors  which  contribute  to  its  spread.  We  must  keep 
in  mind  that  the  disease  called  pneumonia  is  a  group  of  closely  related 
infections  which  may  require  somewhat  different  methods  of  control. 
In  Types  I  and  II,  the  emphasis  must  be  placed  upon  direct  contact 
with  cases  and  carriers,  and  also  dust;  in  Types  III  and  IV,  these 
factors  also  obtain,  but  personal  prophylaxis  to  prevent  auto-infection 
may  be  especially  important.  Until  we  have  more  precise  knowledge, 
our  measures  should  be  general  enough  to  include  all  members  of  the 
group. 

Man  is  the  source  and  fountain  head  of  the  infection.  Each  case  of 
pneumonia  is  a  focus  for  the  spread  of  virulent  pneumococci.  Isola- 
tion and  disinfection  of  discharges  are  the  first  indications.  Limiting 
the  number  of  persons  who  come  in  contact  with  the  patient  will  lessen 
the  number  of  carriers. 

Pneumonia  should  be  added  to  the  list  of  diseases  requiring  com- 
pulsory notification.  Cases  should  be  isolated  at  least  in  the  same  sense 
that  diphtheria  is  isolated — the  discharges  from  the  nose  and  throat 
should  be  burned  or  disinfected.  If  the  patient  is  treated  at  home,  the 
house  should  be  placarded  in  order  to  discourage  visiting  and  as  an 
educational  measure. 

Isolation  in  hospitals  may  be  accomplished  by  proper  nursing  technic, 
including  the  disinfection  of  discharges  and  all  objects  soiled  with  the 
infectious  materials,  especially  fabrics,  hands,  spoons,  cups,  thermom- 
eters, etc.  Sanitary  isolation  may  be  favored  by  the  use  of  cubicles  or 
screens  between  beds,  and  also  by  the  use  of  masks  by  patient,  doctor, 
nurse  and  attendants.     Hospitals  should  take  active  measures  to  pre- 

^  The  Commission  for  the  Study  of  the  Cause  and  Prevention  of  Influenza 
and  Pneumonia  of  the  ^letropolitan  Life  Insurance  Company,  consisting  of:  Dr. 
Lee  K.  Frankel,  Dr.  A.  S.  Knight,  Dr.  W.  H.  Park,  Dr.  W.  H.  Frost,  Dr.  G.  W. 
McCoy,  Dr.  E.  0.  Jordan,  and  Dr.  M.  J.  Rosenau,  Chairman. 


238    DISEASES  FROM  DISCHAEGES  OF  MOUTH  AND  NOSE 

vent  cross  infection  and  institutional  outbreaks.  It  appears  that  pneu- 
monia complicating  measles,  influenza  and  other  diseases  is  apt  to  spread 
in  hospitals,  unless  cases  are  isolated  and  guarded  with  special  care. 

Crowding,  especially  of  the  kind  that  favors  the  spread  of  the  buccal 
flora  from  mouth  to  mouth,  must  be  discouraged.  Persons  who  sleep, 
work  and  play  together,  wash  from  the  same  bowl  and  eat  with  the 
same  tableware,  have  every  opportunity  of  spreading  infections  of  the 
upper  respiratory  tract.  This  is  why  pneumonia  and  other  acute  infec- 
tions of  the  mucous  membrane  of  the  upper  respiratory  tract  are  com- 
mon and  often  epidemic  in  camps,  schools,  prisons,  institutions,  ships 
and  industrial  establishments.  The  factor  of  crowding  and  close  per- 
sonal contact  needs  emphasis  and  attention. 

Upon  the  Isthmus  of  Panama  pneumonia  was  unduly  prevalent  ow- 
ing to  overcrowding,  which  favors  contact  infection.  The  ^  same  was 
found  by  General  Gorgas  among  the  workmen  of  the  African  mines. 
The  prevention  consisted  in  scattering  the  workmen,  giving  them  sep- 
arate homes  in  place  of  barracks.  Allaying  street  dust  and  house  dust 
removes  one  of  the  predisposing  causes  of  pneumonia  and  other  res- 
piratory infections. 

As  carriers  doubtless  play  an  important  role  in  disseminating  this 
infection,  the  education  of  the  public  concerning  certain  sanitary  habits 
should  be  actively  continued.  These  include  the  danger  of  spitting 
promiscuously  and  of  kissing ;  the  proper  care  to  be  exercised  in  sneezing 
and  coughing;  the  peril  in  the  common  drinking  cup,  the  roller  towel; 
and  the  habit  of  placing  unnecessary  things  in  the  mouth,  especially 
the  fingers.  Restaurants,  hotels  and  soda  fountains  should  be  required 
to  scald  all  glasses,  cups,  spoons,  etc.,  every  time  they  are  used.  Lynch 
and  Gumming  ^'^  emphasize  the  importance  of  the  sputum-borne  diseases 
through  hand  to  mouth  infection  and  the  warm  water  used  to  wash  mess- 
kits,  and  dishes  in  hotels,  restaurants,  etc. 

It  should  become  common  knowledge  that  anything  which  tends  to 
reduce  vitality  predisposes  to  pneumonia,  such  as  dissipation,  loss  of 
sleep,  overwork,  worry,  poor  or  insulficient  food,  lack  of  exercise,  al- 
cohol, colds,  or  excesses  of  all  kinds;  the  atonic  effect  of  living  in  over- 
heated rooms,  and  the  injurious  effect  of  excessively  dried  and  warmed 
air,  and  sleeping  in  warmed  rooms.  Cold  baths,  regulation  of  tempera- 
ture and  ventilation,  sleeping  with  open  windows  or  in  the  open  air, 
as  well  as  oral  hygiene,  are  useful  prophylactic  measures  for  pneumonia 
as  well  as  tuberculosis,  "colds,''  and  a  large  group  of  diseases. 

*' Lynch,  C.  C,  and  Gumming,  J.  G. :  Military  Burgeon,  Dec,  1918;  Am. 
Jour.  Puhlio  Health,  Jan..  1919,  Vol.  IX,  No.  1,  p.  2.5;  Jour.  Lab.  and  Clin.  Med., 
Vol.  V,  No.  6;  Military  Surgeon,  Oct.,  1919. 

Gumming,  J.  G. :  Am.  Jour.  Public  Health,  Nov.,  1919,  Vol.  IX,  No.  11, 
p.  849;  Military  Surgeon,  Feb.,  1920;  Am.  Jour.  Public  Health,  Nov.,  1920, 
Vol.  X,  No.  11,  p.  849'. 


LXFLUENZA  239 

A  case  of  pneumonia  due  to  Type  I  or  II  should  not  be  released  from 
quarantine  until  those  fixed  types  have  disappeared  from  the  mouth. 
This  is  usually  only  a  matter  of  a  few  weeks.  After  the  patient  is  dis- 
charged, the  room  should  be  given  a  thorough  cleaning  with  soap  and 
water,  and  disinfected  with  one  of  the  germicidal  solutions. 

Close  supervision  is  needed  of  the  acute  respiratory  infections  such 
as  ordinary  "colds,"  so-called  influenza,  bronchitis,  and  sore  throats. 
These  catarrhal  inflammations  are  often  associated  with  pneumococci 
and  predispose  to  pneumonia.  Persons  suffering  with  these  "minor" 
infections  should  be  isolated  in  bed  during  the  acute  stage  and  at  least 
as  long  as  there  is  fever.  Exposure,  overexertion,  and  fatigue  under 
these  circumstances  may  be  hazardous. 

Health  officers  may  assist  by  disseminating  knowledge  concerning 
the  disease,  by  enforcing  antispitting  regulations,  by  proper  cleans- 
ing and  oiling  of  streets,  by  requiring  a  stricter  compliance  with  build- 
ing and  housing  laws,  and  by  the  regulation  of  the  ventilation  and  con- 
ditions of  the  air  in  theaters,  schools,  street  cars,  and  public  buildings, 
as  well  as  the  crowding  of  such  plac-es;  also  by  providing  free  facilities 
for  laboratory  diagnosis,  to  aid  in  the  search  for  carriers,  to  assist  diag- 
nosis and  serum  therapy,  and  to  trace  epidemics. 

The  virulent  pneumococcus  should  not  be  lightly  regarded  as  a  nor- 
mal inhabitant  of  the  mouth,  throat,  and  nose.  Because  the  pneumo- 
coccus is  very  widely  spread  and  the  disease  is  ubiquitous,  and  because 
the  associated  factors  which  determine  infection  seem  complicated  and 
not  well  understood,  are  not  sufficient  excuses  for  a  supine  and  hope- 
less attitude.  The  problem  of  tuberculosis  has  been  attacked  with  rigor 
with  scarcely  better  understanding  of  the  fundamental  problems  at 
issue.  Each  case  of  pneumonia  should  be  regarded  as  a  focus  for  the 
spread  of  the  infection.  We  should  think  of  pneumonia  xevj  much  as 
"we  think  of  whooping-cough  and  influenza, — as  an  infection  which  is 
spread  from  man  to  man  through  the  secretions  of  the  mouth  and  nose. 

REFERENCE 

Avery,  O.  T.,  Chickerixg,  H.  T.,  Cole,  E.,  and  Dochez,  A.  E. :  Acute 
Lobar  Pneumonia — Prevention  and  Serum  Treatment.  !Monograph 
No.  7,  Eockefeller  Inst.,  Oct.  16,  1917. 

INFLUENZA 

(La  Grippe — Grip) 

Influenza  is  an  acute,  highly  communicable,  febrile  disease,  charac- 
terized by  great  pandemic  outbreaks.  The  fever  lasts  three  days  and 
shows  a  special  tendency  to  bronchial  and  pneumonic  complications. 
When  influenza  sweeps  over  the  world  in  pandemic  form,  it  becomes  the 


240    DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 

most  serious  and  furious  of  epidemics  on  account  of  the  large  numbers 
of  people  attacked  in  a  short  time.  There  is  a  high  incidence,  but  a 
comparatively  low  case  fatality  rate,  but  the  mortality  is  high  on  ac- 
count of  the  great  number  of  cases.  Influenza  itself  probably  never 
kills.  Death  is  alv/ays  due  to  some  complication,  usually  pneumonia. 
Pandemic  influenza  acts  very  much  like  measles  in  a  virgin  population. 

In  the  world  wide  pandemic  of  1918-19,  it  is  estimated  that  there 
were  over  200,000,000  cases  and  that  upwards  of  10,000,000  deaths 
occurred  in  less  than  12  months;  in  the  United  States  alone  there  were 
more  than  20,000,000  cases  and  about  450,000  deaths  in  less  than  6 
months.  In  India,  4,933,132  deaths  from  influenza  were  reported  from 
June  to  November,  1918. 

The  term  influenza  has  become  both  popular  and  vague.  It  is  ap- 
plied to  common  colds,  acute  bronchitis,  catarrhal  inflammations,  nerv- 
ous indispositions,  and  brief  febrile  attacks  of  unknown  origin.  Ac- 
count of  an  epidemic,  probably  influenza,  was  recorded  in  1173.  Many 
outbreaks  of  "plagues,"  some  of  them  doubtless  influenza,  occurred  long 
before  this.  The  first  authentic  outbreak  was  described  in  1510  by  the 
famous  physicians  Willis  arid  Sydenliam.  There  have  been  about  80 
epidemics,  more  or  less  authentic,  since  1173.  Fourteen  pandemics  have 
been  recorded  since  1510;  they  are  those  of  1510,  1557,  1580,  1593,  1729, 
1732,  1762,  1788,  1830,  1833,  1836,  1847,  1889  and  1918.  The  disease 
appears  to  have  been  epidemic  in  North  America  in  the  years  1627,  1647, 
1729,  1732,  1737,  1762,  1782,  1789,  1811,  1832,  1850,  1857,  1860,  1874, 
1879,  1889-90,  1916  and  1918.  The  relation  of  sporadic  and  inter- 
epidemic  outbreaks  to  pandemics  of  influenza  is  not  clear.  Scarcely  a 
year  passes,  particularly  during  the  past  century,  without  news  of  the 
epidemic  occurrence  of  influenza  at  some  point  or  other  of  the  earth's 
surface. 

The  cause  of  influenza  is  not  determined.  Filterable  viruses  have  been 
described  "^  and  denied.^^  In  1892,  Pfeiffer  ^°  discovered  the  Bacillus  in- 
fluenzae—a  small.  Gram  negative,  hemoglobinphilic,  frail  bacillus.  This 
organism  is  found  in  about  30  per  cent,  of  normal  throats  and  is  prac- 
tically always  present  in  measles  and  whooping-cough.  ,  The  percentage 
of  times  it  is  found  in  influenza  varies  with  the  observer,  many  bac- 
teriologists flnding  it  almost  constantly  in  the  recent  outbreak.     The 

"*Nicolle  and  LeBailly,  Compt.  rend.  Acad.  d.  Sc,  1918,  167,  p.  607.  Dugar- 
ric  de  la  Riviere,  Compt.  rend.  Acad.  d.  8c.,  1918,  167,  p.  606.  Olitsky,  P.  K., 
and  Gates,  F.  L.,  Jour.  Exp.  Med.,  Feb.  1,  1921,  Vol.  XXXIII,  2,  p.  125,  and 
others. 

*"  Rosenau,  M.  J.,  et  al. :  Some  Interesting  though  Unsuccessful  Attempts 
to  Transmit  Influenza  Experimentallv.  Public  Health  Reports.  34,  No.  2,  Jan. 
10,  1919;  also  Hyg.  Lab.  Bull.  No.  123,  Feb.,  1921.  Williams,  A.  W.,  Nevin,  M., 
and  Gurley,  C.  R.,  Jour.  Immunoloqif.  Jan..  1921.  Vol.  VI,  I,  p.  5.  Branham  S. 
E.,  and  Hall,  I.  C,  Jour.  Inf.  Dis.,  Feb.,  1921,  Vol.  XXVIII,  No.  2,  p.  143. 

'"Deutsch.  med.  Wochensohr.,  2,  1892,  p.  28.     Zeitschr.  f.  Hyg.,  XIII,  1893, 


INFLUENZA  241 

etiological  relation  to  tiio  disease  is  doubtful  "' — iiowever,  the  recent  ex- 
perience has  gi'eatly  raised  our  respect  for  Pfeiffer's  bacillus,  for  if  it 
is  not  the  cause  of  influenza,  it  may  become  a  virulent  secondary  in- 
vader, and  the  cause  of  serious  complications.  Olitsky  and  Gates  recently 
cultivated  filterable  bodies  as  the  cause  of  influenza. ^^* 

Etiology. — Influenza  is  not  a  clean-cut  clinical  entity.  The  mani- 
festations are  extraordinarily  complex.  The  fever  lasts  three  days;  if 
prolonged,  some  coni])lic'ation  should  be  suspected,  especially  bronchitis 
or  pneumonia.  The  attack  often  starts  a])ruptly:  hence  the  term  "grip." 
The  prostration  is  out  of  all  proj^ortion  to  the  fever  and  lesions.  Cough 
and  pains  in  the  head,  back  and  limbs  are  almost  always  present.  There 
is  a  leukopenia.  The  disease  itself  is  rarely,  if  every,  fatal,  death  being 
due  almost  always  to  pneumonia.  The  clinical  features  of  each  out- 
break vary, — usually  the  respiratory  form  predominates.  In  the  1889- 
90  epidemic,  neuritis  and  the  "nervous  form"  were  common.  A  gastro- 
intestinal form  is  described.  In  the  recent  pandemic,  pneumonic  com- 
plications were  conspicuous  and  the  disease  was  unusually  virulent  in 
pregnant  women.  The  diagnosis  of  influenza  from  the  clinical  stand- 
point is  not  trustworthy.  There  is  no  criterion  by  which  the  infection 
may  be  recognized.  Until  the  cause  is  established,  we  cannot  know  the 
relationship  between  influenza  and  the  ordinary  cases '  of  "catarrhal 
fever,"  "grip,"  common  colds,  and  "influenza  colds." 

Mode  of  Infection. — It  is  assumed  that  the  virus  leaves  the  body  in 
the  secretions  from  the  mouth  and  nose,  and  enters  through  the  same 
channel.  Therefore,  it  is  probable  that  the  infection  is  contracted 
through  direct  and  indirect  contact  and  droplet  infection.  Lynch  and 
Gumming  '^^  believe  that  indirect  contact  and  hand  to  mouth  infection  are 
the  chief  modes  of  spread.  Water,  milk,  and  food  are  not  known  to 
carry  the  virus.  Eosenau,  Goldberger  and  McGoy '^^  were  not  able  to 
transmit  the  disease  to  volunteers. 

Epidemiology. — Influenza  attacks  all  ages  and  both  sexes.  During 
the  1919  pandemic  it  was  most  fatal  during  the  age  period  20  to  30, 
and  seemed  to  have  a  predilection  for  strong,  sturdy,  robust  young  men. 
More  females  than  males  were  affected,  but  the  death  rate  was  higher 
among  males.  It  spares  neither  class  nor  race ;  it  takes  the  rich  and  poor 
alike,  the  strong  and  the  weak,  the  clean  and  the  dirty.  Hygiene  and 
sanitation  therefore  have  practically  no  effect  in  controlling  diseases  like 
influenza,  measles  and  smallpox. 

Influenza  occurs  as  great  pandemic  waves  at  irregular  intervals  of  a 
generation  or  two.    These  are  followed  by  years  of  epidemic  and  sporadic 

"^Journ.  of  Immunology.  Jan.,  1921,  Vol.  VI,  No.  1. 

""J.  A.  M.  A.,  March  5,  1921;  Jour.  Exp.  Med.,  March,  1921,  XXXIII,  3. 
'''^  MiUtartj  Surgeon.  Dec,  1918;   other  references,  page  238. 
"Public  Health  Rpts.,  34,  No.  2,  Jan.  10,  1919;   also  Hyg.  Lab.  Bui.,  U.  S. 
P.  H.  S.,  No.  123,  Feb.,  1921. 


242    DISEASES  FEOM  DISCHARGES  OF  MOUTH  AND  NOSE 

prevalence — the  etiologic  relationship  is  not  established.  A  pandemic 
occurs  in  succeeding  waves;  the  secondary  waves  are  at  intervals  of  8 
months/*  The  entire  cycle  of  a  pandemic  lasts  4  to  6  years.  Epidemics 
are  intermittent  and  tend  to  develop  periodicity. 

WTien  pandemic,  the  disease  attacks  13  to  53  per  cent,  of  the  popula- 
tion, averaging  about  30  per  cent.  The  incidence  on  board  ship  or  other 
limited  localities  runs  as  high  as  84  per  cent.'^^  The  disease  spreads  with 
amazing  rapidity.  It  travels  ordinarily  from  east  to  west :  the  1889-90 
pandemic  was  supposed  to  start  in  Eussia.  Other  world-wide  epidemics 
have  been  traced  to  the  far  East.  The  last  pandemic  was  called  Spanish 
Influenza  because  it  first  came  to  notice  in  Spain,  but  probably  did  not 
originate  there.  It  started  in  malignant  form  in  this  country  in  Boston 
on  Commonwealth  Pier,  then  used  as  a  Xaval  Eeceiving  Ship,  in  Sep- 
tember, 1918,  and  rapidly  spread  over  the  entire  country.  By  November 
it  was  difficult  to  find  a  community  anywhere  that  was  not  affected.  By 
January  it  was  on  the  wane,  and  by  March  it  had  subsided.  The  dura- 
tion of  an  epidemic  in  any  one  locality  is  from  6  to  8  weeks.  In  compact 
communities,  such  as  camps,  it  may  run  its  course  in  from  4  to  6  weeks. 
No  other  disease,  except  perhaps  dengue,  attacks  such  a  large  propor- 
tion of  the  people  in  so  short  a  time.  Dengue,  however,  is  limited  geo- 
graphically to  mosquito  centers  of  warm  countries. 

Influenza  occurs  at  all  seasons  of  the  year,  with  a  preference  for 
cold  weather.  Del  Pont,  from  an  historical  review  of  125  pandemics, 
shows  that  50  occurred  in  the  winter,  35  in  the  spring,  16  in  the  summer, 
and  24  in  the  fall.  It  is  conveyed  by  human  contact,  independent  of 
climate,  wind,  or  weather,  except  that  secondary  waves  avoid  the  sum- 
mer. Epidemics  break  out  with  explosive  violence.  This  is  one  of  its 
chief  characteristics.  The  curve  is  steeple-like  (see  chart).  Epidemic 
outbursts  of  this  character  usually  mean  that  some  common  medium  is 
spreading  the  virus  which  is  infecting  a  large  number  of  people  about 
the  same  time.  The  explosive  character  of  epidemics  is  explained  by  the 
short  period  of  incubation,  high  degree  of  communicability  of  the  dis- 
ease and  susceptibility  of  the  population.  The  rapid  spread  is  further 
assisted  by  the  fact  that  many  who  have  the  disease  do  not  go  to  bed, 
but  continue  to  mingle  with  their  fellow  men.  Secondary  waves  in  a 
pandemic  cycle  are  less  explosive  and  the  curve  is  apt  to  be  longer  and 
less  symmetrical  than  the  first  onrush  of  a  new  pandemic.  The  curve 
of  a  primary  outbreak  is  uniform,  while  secondary  waves  may  be  variable. 
The  disease  is  apt  to  be  mild  and  uncomplicated  in  the  beginning  of  a* 
pandemic  cycle.  It  increases  in  virulence  to  the  peak  of  the  wave  and 
again  decreases  as  the  epidemic  wanes. 

"Brownlee.     Lancet,  Nov.  8,   1919. 

"  U.  S.  S.  "Yacona"  in  1919:  80  of  95  persons  stricken  within  about  one 
week. 


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Fig.  17. — Curve  of  the  Ixfluexza  Epidemic  ix  the  Naval  Training  Camp  at 
Pelham  Park,  Xew  York,  September  and  October,  1918;  Showing  (1) 
Case.s  of  Influenza,  (2)  Cases  of  Pneumonia,  and  (3)  Deaths.  iSTote 
the  steeple-like  appearance  of  the  curve,  its  symmetrical  character,  the  short 
duration  and  explosive  nature  of  the  outbreak. 

243 


244    DISEASES  FROM  DISCHARGES  OF  MOTJTH  AND  NOSE 

Although  influenza  spreads  with  amazing  rapidity,  it  is  not  known 
to  outstrip  human  travel.  It  moves  from  place  to  place  in  a  pair  of 
shoes.  It  sometimes  seems  to  outrun  travel;  at  least  it  is  reported  to 
break  out  simultaneously  in  widely  separated  parts  of  the  globe.  The 
vagaries  of  epidemics  have  given  point  to  the  name  influenza,  referring 
to  some  hidden  influence. 

No  other  disease  is  more  disabling  to  community  life,  for  the  reason 
that  so  many  are  placed  upon  the  non-effective  list  at  the  same"  time. 
Trade  and  travel  become  temporarily  paralyzed;  there  is  a  shortage  of 
doctors  and  nurses;  hospital  facilities  are  inadequate.  The  lesson  of 
the  past  pandemic  should  teach  us  to  mobilize  the  medical,  nursing, 
hospital,  and  social  service  facilities  in  anticipation  of  such  emer- 
gencies. 

The  incubatio7i  period  is  usually  short — 20  to  48  hours.  The  disease 
is  presumably  most  communicable  during  the  early  stages.  Carriers 
may  spread  the  infection  and  are  suspected.  If  the  Bacillus  influenzae 
is  the  cause  of  the  disease,  then  bacillus  carrying  is  exceedingly  common. 
We  do  not  know  how  long  a  person  remains  infective  and  little  is  known 
concerning  carriers. 

The  question  of  immunity  is  not  settled;  it  does  not  last  a  year. 
Second  and  third  attacks  were  said  to  occur  in  1889-90,  but  were  un- 
common in  1919.  Some  persons  have  recurring  "influenza-like"  attacks 
yearly. 

During  epidemics  of  influenza,  other  diseases  do  not  prevail  to  the 
same  extent.  On  the  other  hand,  influenza  is  supposed  to  depress  resist- 
ance so  as  to  favor  or  hasten  certain  infections  such  as  tuberculosis;  of 
this,  however,  we  lack  proof.  There  seems  to  be  an  epidemiological  rela- 
tionship between  influenza  and  cerebrospinal  fever.  The  influenza  bacil- 
lus is  sometimes  found  in  pure  culture  in  meningitis,  which  may  also 
occur  as  a  complication  of  influenza.  Encephalitis  lethargica  also 
bears  an  epidemiologic  relation  to  epidemics  of  influenza. 

Influenza  was  prevalent  and  fatal  among  horses  in  1919,  and  the 
cause  of  much  trouble  to  the  army  supply  service.  It  also  prevailed  as 
an  epizootic  in  this  country  in  1889-90.  Other  distempers  among  ani- 
mals resemble  influenza.    The  relationship  to  man  is  not  known. 

Crowding  and  human  contact  seem  to  favor  its  spread,  although  it 
travels  with  surprising  rapidity  through  rural  communities. 

Vaccines. — Two  classes  of  vaccines  are  used  to  protect  against  in- 
fluenza:  (1)  influenza  bacilli,  (2)  mixtures  of  pneumococci  (Types 
I,  II,  III  and  IV),  hemolytic  streptococci,  staphylococci  aurei,  influenza 
bacilli, '^^  and  other  microorganisms. 

Contradictory  results  have  been  reported  with  both  types  of  vaccines. 
My  own  observations  at  Monson,  Pelham  Park  Naval  Training  Station, 

"Rosenow:    J.  A.  M.  A.,  Jan.  14,  1919,  Vol.  LXXII,  p.  31. 


TXFfJ'KNZA  245 

and  elsewhere  lead  me  to  conclude  that  vaccines  made  with  dead  cultures 
of  Pfeiffer's  bacillus  have  no  protective  value  wliatever.  Whether  the 
polyvalent  vaccines  prevent  pneumonic  complications  has  not  been 
established. 

ADMINISTRATIVE  MEASURES 

Isolation  is  possible,  but  not  very  practical  during  epidemics.  In 
1889-90  some  large  institutions  were  saved  through  a  strict  quarantine. 
Once  within  the  walls,  it  is  exceedingly  difficult  to  control.  In  1918-19, 
the  infection  was  kept  out  of  Goat  Island  in  San  Francisco  Harbor,  but 
finally  got  in.  Several  other  localities  had  a  similar  experience.  Aus- 
tralia established  a  quarantine  which  proljably  delayed  the  epidemic  six 
months,  when  it  was  milder  than  elsewhere. 

Patients  for  their  own  good  should  remain  in  bed  during  the  febrile 
stage.  This  one  measure  would  help  control  the  spread  of  influenza 
as  well  as  common  colds.  It  is  quite  worth  while  to  isolate  the  first 
case  in  a  household  in  order  to  prevent  a  house  epidemic.  This  may 
be  done  on  lines  precisely  parallel  to  those  described  for  diphtheria. 

Masks. — During  the  1919  outbreak,  face  masks  were  compulsory  in 
San  Francisco,  Sacramento,  and  a  few  other  cities.  They  did  not  lessen 
the  incidence  nor  shorten  the  course  of  the  epidemic. 

Closing  of  schools,  theaters,  and  other  places  of  assembly,  and  regula- 
tions to  prevent  crowding  were  enforced  in  many  cities  during  the  epi- 
demic of  1918-19,  but  so  far  as  can  be  judged  had  no  favorable  effect 
whatever. 

Hospitalization  is  not  always  advisable,  for  the  condensation  of  many 
cases  seems  to  favor  the  number  and  severity  of  complications.  This 
same  phenomenon  is  seen  with  measles.  It  is  believed  that  pneumonic 
complications  are  sometimes  contracted  in  large  hospitals. 

Personal  pi-ophylaxis  follows  the  lines  laid  dovra  for  other  infections 
transferred  by  the  secretions  from  the  mouth  and  nose.  During  epi- 
demics individuals  should  avoid  theaters,  mass  meetings,  closed  and 
crowded  cars,  and  close  contact  with  their  fellow  men,  especially  those 
who  have  catarrhal  symptoms  or  fever.  The  danger  from  kissing,  droplet 
infection,  the  use  of  the  common  drinking  cup,  the  roller  towel,  hand- 
kerchiefs, pipes,  toys,  soda  water  glasses,  spoons,  and  other  objects 
recently  mouthed  should  be  emphasized;  spitting  ordinances  enforced, 
ventilation  and  overcrowding  of  street  cars  corrected,  and  dust  allayed. 
Hand  to  mouth  infection  should  be  remembered,  and  the  hands  washed 
before  eating  and  the  fingers  kept  away  from  the  mouth  and  nostrils. 
Convalescence  is  often  protracted,  and  subject  to  complications.  Ample 
time  should  therefore  be  given  to  full  return  to  health. 

There  may  be  unknown  factors  in  the  spread  of  influenza  so  that 


246     DISEASES  FEOM  DISCHARGES  OP  MOUTH  AND  NOSE 

our  preyentive  measures  lack  precision  and  confidence.  We  have  no 
specific  prophylactic.  So  far  as  can  be  judged,  the  ^  measures  taken 
during  the  epidemic  of  1918-19  did  not  control  the  disease  to  any 
appreciable  degree. 

COMMON  COLDS 

(Acute  Coryza) 

More  people  probably  suffer  from  common  colds  than  from  any  other 
single  ailment.  Vital  statistics  give  no  hint  of  the  prevalence  and  im- 
portance of  these  minor  affections  because  the  mortality  is  nil  and  the 
morbidity  records  are  notoriously  imperfect  and  difficult  to  collect. 
Could  the  sum  total  of  suffering,  inconveniences,  sequelae,  and  eco- 
nomic loss  resulting  from  common  colds  be  obtained,  it  would  at  once 
promote  these  infections  from  the  trivial  into  the  rank  of -the  serious 
diseases. 

The  common  colds  here  considered  are  a  group  of  acute  infections  of 
the  mucous  membranes  of  the  nose,  often  extending  into  the  throat; 
the  larynx,  trachea,  or  larger  bronchi  may  be  also  involved.  A  common 
cold  is  not  merely  a  congestion,  it  is  an  acute  infectious  disease. 

Congestion  and  inflammation  of  the  mucous  membrane  of  the  upper 
respiratory  tract  frequently  occur  as  a  result  of  irritants  other  than 
bacteria.  Thus,  chemical  and  mechanical  irritants  will  produce  a  con- 
gestion or  inflammation;  an  increased  acidity  causes  a  flaring  up  of 
the  mucous  membranes,  especially  of  the  nose;  and  many  other  local 
and  reflex  causes  lead  to  acute  or  chronic  catarrhal  conditions  of  these 
membranes,  "which  may  become  exquisitely  sensitive  and  sometimes 
hypersusceptible.  In  the  absence  of  the  proper  microorganism,  however, 
these  conditions  do  not  develop  into  infectious  colds,  and  are,  therefore, 
not  communicable. 

The  popular  fallacy  of  colds  being  due  to  exposure  to  drafts,  sudden 
changes  of  temperature,  and  chilling  of  the  body  clings  persistently  in 
both  the  professional  and  lay  mind.  These  are  predisposing  causes 
and  will  not  produce  a  cold  without  the  presence  of  the  specific  cause. 
The  bacteria  usually  found  associated  with  these  catarrhal  infections  are : 
staphylococci,  streptococci  (viridens  and  hemoMicus),  pneumococci,  in- 
fluenza bacilli,  the  Gram  negative  cocci  classed  together  as  members 
of  the  micrococcus  catarrhalis  group,  diphtheroid  bacilli,  and  other 
microorganisms.  The  etiological  relationship  between  these  organisms 
and  the  disease  is  not  always  clear.  Many  of  the  above-mentioned 
bacteria  arp  also  found  normally  upon  the  mucous  membranes  of  the  nose, 
mouth,  throat,  and  upper  respiratory  passages;  auto-infections  must, 
therefore,  be  common,  and  predisposing  factors  which  diminish  resist- 
ance have  a  special  importance. 


COMMON  COLDS  247 

Tunnicliff"  described  a  Bacillus  rhinitis  associated  with  acute  and 
chronic  rhinitis.  Experimental  inoculations  of  pure  cultures  produced 
colds. 

Foster,  working]:  in  my  laboratory,  has  just  confirmed  and  extended 
Kruse's  ''^  observations,  showing  the  ])resence  of  a  filterable  virus  in  the 
secretions  from  the  nose  in  common  colds.  I'his  filtrate,  as  well  as  sub- 
cultures grown  in  selective  media,  when  dropped  into  the  nostril  of 
healthy  jiersons,  ])roduces  a  cold.'^^'^  There  are  different  types  of  colds, 
due  to  dilferent  viruses,  or  to  the  associated  bacteria.  A  number  of 
negative  results  have  also  been  recorded.''^ 

Colds  are  contracted  from  other  persons  having  colds,  just  as  diph- 
theria is  contracted  from  diphtheria.  Arctic  explorers  exposed  to  all 
the  conditions  ordinarily  supposed  to  produce  colds  do  not  suffer  from 
these  ailments  until  they  return  to  civilization  and  become  reinfected 
by  contact  with  their  fellowonen.  A  campaign  to  prevent  the  spread 
of  the  common  cold  would  have  much  collateral  good  in  aiding  the 
suppression  of  tuberculosis  and  causing  a  diminution  of  pneumonia  and 
other  infections.  Common  colds  occur  in  epidemics  and  have  all  the 
earmarks  of  a  contagious  disease.  Colds  are  apt  to  go  through  all  the 
members  of  a  household,  and  outbreaks  in  schools,  factories,  and  other 
places  where  people  are  closely  associated,  frequently  occur  and  result  in 
considerable  loss  of  time  and  money. 

While  common  colds  are  never  fatal,  the  complications  and  sequelae 
are  serious.  These  are :  rheumatic  fever,  pneumonia,  sinusitis,  nephritis, 
and  a  depressed  vitality  which  favors  other  infections  and  hastens  the 
progress  of  organic  diseases. 

Common  colds  are  perhaps  most  contagious  during  the  early  stages. 
If  persons  would  isolate  themselves  by  remaining  in  bed  during  the 
first  three  days  of  a  cold,  they  would  not  only  benefit  themselves,  but 
would  largely  prevent  the  spread  of  the  infection.  The  contagiousness 
and  severity  of  colds  vary  greatly  in  different  epidemics  and  in  dif- 
ferent seasons  of  the  year,  depending  upon  the  particular  microorganism 
involved  and  other  factors  not  well  understood. 

Prevention. — The  prevention  of  colds  consists,  first,  in  avoiding  the 
infection,  and,  secondly,  in  guarding  against  the  predisposing  causes. 
Contact  should  be  avoided  with  persons  who  have  colds,  especially  in 
street  cars,  offices,  and  other  poorly  ventilated  spaces  where  the  risk  of 
persons  coughing  or  sneezing  directly  in  one's  face  is  imminent.  Con- 
tact with  the  infection  may  further  be  guarded  against  by  a  careful 

"Journ.  Inf.  Dis.,  19]  3,  XIII.  283. 
''^Milnch.  med.  Wochnschr.,  1914,  LXI,  1.547. 
''"J.  A.  M.  A.,  April  8,  1916,  Vol.  LXVI,  No.  14. 

"Park,  W.  H.,  Williams,  A.  W.,  and  Krumwiede,  C,  Jo-wr.  of  Immunology, 
Jan.,  1921,  Vol.  VI,  No.  1,  p.  1.,  and  others. 


248    DISEASES  FROM  DISCHAEGES  OF  MOUTH  AND  NOSE 

self-education  in  sanitary  habits  and  cleanliness  based  upon  the  modern 
conception  of  contact  infection. 

Colds,  like  other  diseases  conveyed  in  the  secretions  from  the  nose 
and  mouth,  are  often  transferred  by  direct  and  indirect  contact  through 
lack  of  hygienic  cleanliness  and  a  disregard  of  sanitary  habits.  Kissing, 
the  common  drinking  cup,  the  roller  towel,  pipes,  toys,  pencils,  fingers, 
food,  and  other  objects  contaminated  with  the  fresh  secretions  will 
transmit  the  disease. 

The  predisposing  causes  of  colds  include  a  number  of  conditions  that 
depress  vitality  and  thereby  diminish  resistance.  The  mechanism  by 
which  immunity  is  lessened  is  discussed  on  page  542.  The  principal 
predisposing  factors  in  "catching"  cold  are:  vitiated  air,  dust,  drafts, 
sudden  changes  of  temperature,  exposure  to  cold  and  wet,  overwork, 
loss  of  sleep  or  insufficient  rest,  improper  food,  and  other  conditions  that 
lower  the  general  vitality  of  the  body.  On  the  other  hand.  It  must  be 
clearly  kept  in  mind  that  vigorous  persons  in  prime  health  will  contract 
a  cold  if  they  receive  the  infection. 

Other  important  predisposing  factors  to  colds  are  mechanical  defects 
in  breathing,  or  the  filtering  power  of  the  upper  respiratory  passages,  also 
local  pathological  conditions,  such  as  adenoids,  polypus,  enlarged  tonsils, 
deviation  of  thf.  septum,  chronic  catarrhal  conditions,  all  of  which  should 
receive  appropriate  treatment. 

One  of  the  most  important  predisposing  factors  to  cold  is  breathing 
vitiated  and  dusty  air.  Good  ventilation,  therefore,  with  air  not  too 
dry  nor  too  warm,  and  the  allaying  of  dust  would  prevent  many  a  cold. 
The  bacteria  accompanying  colds  are  frequently  found  in  the  mouth, 
nose,  throat  and  teeth  of  persons  in  good  health.  Cleanliness  and  care  of 
these  parts  is,  therefore,  an  important  consideration  in  the  prevention  of 
the  complications  of  common  colds. 

Drafts  and  Chilling. — Drafts  in  themselves  cannot  produce  an  in- 
fectious cold.  The  first  symptom  of  the  disease  is  a  chill,  which  is  not 
the  cause,  but  the  effect,  of  the  infection.  It  is  a  common  belief  that 
the  cold  is  caught  when  the  chill  occurs.  The  rigor  frequently  consists 
of  only  a  transient  chilliness,  and  it  is  during  this  time  that  the  indi- 
vidual is  sensitive  to  drafts  which  he  thinks  are  producing  his  cold.  See 
page  891. 

A  large  number  of  investigators,  including  Lipardi,^°  Lode,^^  Pas- 
teur,^^  Kline  and  Winternitz,^^  the  New  York  State  Commission  on  Ven- 
tilation,®* Miller  and  Noble,®^  and  others,   have  experienced  variously 

»"Morgagni,  1888,  XXX,  523,  575,  651. 

^"■Arch.  Hyg.,  XXVIII,  344. 

«2"Life  of  Pasteur,"  R.  Vallerv-Radot,  N.  Y.,  1902,  II,  61. 

^Journ.  Exp.  Med.,  1915.  XXI.  304. 

^*J.  A.  M.  A.,  Apr.  15,  1916,  p.  1201. 

^Journ.  Exp.  Med.,  Sept.  1.  1916,  p.  223. 


COMMON  COLDS  240 

with  animals  and  man.  and  all  aro  in  accord  with  tlio  geueral  conclu- 
sion that  exposures  to  sud<h'n  changes  of  temperature  lessen  the  resist- 
ance of  animals  to  ini'cction.  Nejjative  results  are  also  found  in  the 
literature.  It  seems  evident  that  the  exposure  of  a  portion  of  the  body 
to  cold  is  more  likely  to  l)e  followed  hy  acute  respiratory  infections  than 
when  the  entire  body  surface  is  subjected  to  the  same  low  temperature, 
and  the  popular  idea  that  drafts  predispose  to  respiratory  infections  in 
some  individuals  is  therefore  not  without  foundation. 

Chilling  causes  vasomotor  contraction  of  the  capillaries  of  the  skin, 
which  is  doubtless  designed  to  conserve  body  temperature;  coincidently 
there  is  turgid  ity  of  the  erectile  tissue  of  the  mucous  membrane  of  the 
turbinates,  which  is  probably  a  defensive  action.  This  congestion  partly 
closes  the  nose  and  causes  snuffling  and  increased  secretion,  which  is 
ordinarily  called  a  cold.  A  great  variety  of  mechanical,  chemical  and 
even  psychic  stimuli  will  produce  congestion  of  the  cavernous  tissue  over 
the  turbinate,  in  fact,  the  mucous  membrane  of  the  nose  may  become  very 
sensitive,  even  hypersusceptible.  Anaphylactic  reactions  to  pollen  and 
proteins  are  common  manifestations  of  the  nasal  mucosa. 

It  has  always  been  assumed  that  the  contraction  of  the  capillaries 
of  the  skin  caused  by  chilling  is  attended  with  congestion  of  the 
internal  organs,  but  Mudd  and  Grant  *®  have  shown  that  chilling  of  the 
skin  causes  vasomotor  contraction  and  ischemia  of  the  mucous  mem- 
brane of  the  tonsils,  palate,  and  pharynx,  as  well  as  the  skin,  with  a  drop 
in  temperature  and  a  subsequent  increase  in  the  bacteria  on  these  parts. 
On  rewarming  the  subject,  the  tonsils  tend  quickly  to  recover  their  blood 
supply,  in  some  instances  actually  becoming  hyperemic ;  the  skin  returns 
to  about  its  normal  condition,  but  the  palate  and  pharynx  remain  some- 
what ischemic.  This  may  explain  why  chilling  so  often  seems  responsible 
for  sore  throat,  which  in  this  case  would  be  an  auto-infection. 

'  Chilling  has  a  great  variety  of  effects.  In  some  persons  it  causes 
diarrhea,  in  others  neuralgic  or  muscular  pain,  sometimes  it  seems  to  be 
responsible  for  nephritis,  bronchitis,  pneumonia,  etc.  It  brings  out  a 
latent  malaria  (page  290).  Chilling  is  much  less  apt  to  cause  harm  if 
accompanied  with  active  muscular  exercise,  which  probably  helps  by 
keeping  up  the  body  temperature  and  vasomotor  tone. 

Drafts  are  much  less  apt  to  injure  persons  in  good  physical  tone. 
They  are,  however,  injurious  to  infants,  the  aged,  and  to  susceptible 
individuals.  Drafts  are  particularly  apt  to  harm  persons  accustomed 
only  to  still,  warm  air.  "It  is  not  the  engine  drivers  and  firemen  of 
trains  that  catch  colds,  but  the  passengers  in  the  stuffy  carriages." 
Coddling  renders  one  susceptible  to  drafts,  partly  for  the  reason  that 
the  vasomotor  impulses  which  contract  the  blood  vessels  of  the  skin  are 

^Journ.  Med.  Research,  XL,  1,  p.  53,  Mav,  1919.  Jour.  Exp.  Med.,  1920, 
XXXII,  p.  87. 


250    DISEASES  FEOM  DISCHARGES  OE  MOUTH  AND  NOSE 

not  sent  out  by  the  nervous  mechanism,  and  consequently  undue  cool- 
ing of  the  part  blown  upon,  and  perhaps  of  the  blood  itself,  takes  place. 
Normally,  when  the  wind  blows  upon  the  skin  the  vasomotor  contraction 
reduces  the  supply  of  blood  and  the  tendency  to  cooling  is  further  met 
by  a  stimulus  which  increases  heat  production.  While  it  is  true  that  a 
draft  can  no  more  cause  an  infectious  cold  than  it  can  cause  diphtheria, 
nevertheless,  it  is  true  that  a  draft  may  increase  the  severity  of  a  cold 
or  be  the  predisposing  cause  by  which  immunity  is  lowered,  thus  favor- 
ing auto-infection.  It  is  noteworthy  that  colds  so  contracted  have  little 
or  no  contagious  tendency. 

It  is  a  mistake  to  think  that  the  skin  alone  is  involved  in  the  ques- 
tion of  drafts.  The  "hardening'^  of  the  skin  as  a  prevention  of  colds  is, 
therefore,  a  misnomer.  The  good  effects  of  cold  baths,  exercise,  fresh 
air,  sunlight,  and  wholesome  food  do  not  consist  in  "hardening"  the 
skin,  but  in  improving  the  nutrition,  stimulating  the  metabolism,  help- 
ing the  control  of  the  nervous  system,  improving  the  tone  of  the  vaso- 
motor system,  strengthening  the  musculature,  and  enriching  the  blood. 
In  preventing  the  ill  effects  of  drafts,  therefore,  the  entire  organiza- 
tion of  the  body  must  be  considered,  and  not  the  skin  alone. 


CEREBROSPINAL  FEVER 

Cerebrospinal  fever  is  an  infection  with  the  meningococcus  (Diplo- 
coccus  intracellularis  meningitidis,  Weichselbaum).  The  essential 
lesions  of  the  disease  are  chiefly  focused  upon  the  meninges  of  the  brain 
and  cord.  The  disease  occurs  both  in  localized  epidemics  and  spo- 
radically. 

It  is  characterized  by  a  clinical  course  of  great  irregularity,  and  be- 
fore the  use  of  specific  serum  had  a  very  high  case  fatality  rate.  On 
account  of  the  eruption  which  is  often  present,  cerebrospinal  fever 
was  formerly  called  spotted  fever,  petechial  fever,  and  malignant  pur- 
puric fever. 

A  clear  distinction  should  be  drawn  between  cerebrospinal  fever  and 
cerebrospinal  meningitis :  the  former  is  caused  by  the  meningococcus,  the 
latter  by  a  great  variety  of  organisms,  such  as  the  tubercle  bacillus,  the 
pneumococcus,  streptococcus,  influenza  bacillus,  the  colon  bacillus,  the 
typhoid  bacillus,  the  bacillus  of  bubonic  plague,  and  of  glanders.  The 
gonococcus  may  also  cause  meningitis  as  a  secondary  complication. 
The  epidemic  form,  or  cerebrospinal  fever,  is  always  due  to  the  men- 
ingococcus. 

The  first  epidemic  outbreak  of  cerebrospinal  fever  was  reported  by 
Vieusseux  in  Geneva  in  1805.  The  next  year  James  Jackson,  Thomas 
Welch,  and  J.   C,  Warren  investigated  an  outbreak  in  Massachusetts. 


CEREBROSPINAL  FEVER  251 

Since  then  numerous  epidemics  have  occurred,  iu  tlie  iSTew  York  epi- 
demic of  1904-05  there  were  6,755  cases  and  3,455  deaths.  This  was 
part  of  a  pandemic  that  started  in  Europe  and  within  5  or  6  years 
spread  over  the  entire  globe  and  then  became  quiescent,  but  was  again 
stirred  to  renewed  activity  by  the  war. 

Cerebrospinal  meningitis  is  spread  chiefly  by  carriers.  The  period 
of  incubation  is  difficult  to  determine ;  it  is  stated  to  be  from  two  to  ten 
days,  commonly  seven.  It  may  be  one  day  in  the  young.  It  is  ex- 
tremely variable  in  some  instances,  as  when  carriers  infect  themselves. 

Epidemiology. — Epidemics  of  cerebrospinal  fever  are  usually  local- 
ized, and  rarely  widespread.  They  almost  always  occur  under  crowded 
conditions,  as  in  camps  and  on  shipboard.  Mining  districts  and  sea- 
ports have  suiTered  most  severely.  On  the  other  hand,  rural  districts 
have  also  suffered  severely,  and  widespread  outbreaks  have  occurred  in 
the  tropics. 

Cerebrospinal  fever  shows  a  distinct  seasonal  prevalence  for  the 
colder  months  of  the  fall  and  winter.  In  this  respect  it  resembles  other 
infections  spread  by  the  secretions  of  the  mouth  and  nose,  as  pneumonia, 
scarlet  fever,  measles,  diphtheria,  etc.  This  is  in  sharp  contrast  to  the. 
seasonal  prevalence  of  infantile  paralysis  which  follows  the  curve  of 
the  summer  diarrheas. 

Children  and  young  adults  are  most  susceptible.  Cerebrospinal  fever 
is  called  a  disease  of  children  and  soldiers.  The  soldiers  who  suffer  most 
are  those  living  in  barracks,  garrisons,  towns  and  camps,  rather  than 
those  on  the  march  or  in  the  field.  The  recruit  and  the  young  soldier 
are  especially  liable.  Crowding,  which  favors  contact  infection,  and 
fatigue  which  predisposes  to  this  disease,  explain  the  special  liability 
under  these  conditions.     Seasoned  troops  rarely  suffer  from  the  disease. 

Predisposing  factors  play  an  important  role  in  depressing  immunity 
and  facilitating  infection  with  the  meningococcus.  Over-exertion,  long 
marches  in  the  heat,  depressing  mental  and  bodily  surroundings,  catar- 
rhal inflammations,  the  misery  and  squalor  of  tenement  life,  and  the 
sad  conditions  of  some  mining  and  laboring  camps  have  long  been 
recognized  as  predisposing  causes.  It  is  not  the  hardened  soldier  but 
the  recruit  in  the  making  who  is  susceptible.  The  emergencies  of  the 
war  again  showed  the  hazard  of  haste  in  training  the  soldier  and  the 
sailor. 

Weed  has  shown  by  experiments  on  animals  that  diminution  of 
the  pressure  of  the  cerebrospinal  fluid  facilitates  infection  of  the  men- 
inges with  meningococci  or  any  other  microorganism  that  may  be  in  the 
blood  stream.  The  pressure  of  the  cerebrospinal  fluid  may  be  decreased 
by  puncture,  by  pressure  on  the  vessels  of  the  neck,  and  other  ways.  This 
may  prove  an  important  predisposing  factor. 

Cerebrospinal  fever  has  long  been  recognized  as  a  war  disease.     No 


552     DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOi^S 

great  epidemics  of  the  disease  occur  among  troops,  but  the  affection  pre- 
vails more  or  less  in  all  armies.  Sharp  localized  outbreaks  occurred 
here  and  there.  Between  1837  and  1850  a  very  widespread  epidemic 
occurred  in  France,  the  disease  being  carried  from  place  to  place  by 
the  movements  of  the  18th  Regiment  of  Infantry,  in  which  the  infection 
had  established  itself. 

Cerebrospinal  fever  is  not  highly  communicable,  but  spreads  slowly 
and  irregularly.  It  is  usually  difficult  to  trace  connection  between  one 
case  and  the  next — ^its  movement  shows  curious  pranks.  This  is  now 
explained  through  carriers.  Except  in  sharply  localized  outbreaks,  it 
is  rare  to  have  more  than  one  or  two  cases  in  a  home,  even  where  pre- 
cautions are  not  taken.  Sporadic  cases  are  apt  to  crop  out  almost 
anywhere,  at  any  time  of  the  year.  Only  a  small  proportion  of  those 
who  receive  the  infection  develop  the  disease;  the  meningococcus  is 
passed  on  from  one  to  another  until  a  susceptible  individual  is  reached 
who   develops  meningitis. 

The  case  fatality  rate  is  usually  high,  about  75  per  cent.,  occasionally 
being  as  low  as  20  per  cent,  in  some  epidemics.  The  use  of  serum  has 
reduced  the  death  rate  to  about  25  per  cent. 

The  immunity  produced  by  one  attack  is  not  lasting.  Councilman 
reports  five  instances  in  which  the  same  individual  is  reported  to  have 
had  the  disease  twice. 

Modes  of  Transmission. — It  is  probable  that  the  meningococcus  enters 
the  system  through  the  mucous  membrane  of  the  nasopharynx.  From 
this  position  it  may  reach  the  meninges  directly  through  the  lymph 
channels,  but  usually  indirectly  through  the  circulation.  The  experi- 
ments of  Flexner  in  the  monkey  indicate  that  when  the  meningococcus* 
is  introduced  into  the  cerebral  cavity  it  escapes  by  a  reversed  lymphatic 
current,  so  that  under  these  circumstances  it  may  be  found  in  the  mucous 
membrane  of  the  nasopharynx.  Cerebrospinal  fever  is  therefore  spread 
through  the  discharges  from  the  nose  and  mouth.  It  is  a  contact  in- 
fection, due  in  the  great  majority  of  cases  to  rather  direct  association 
with  cases  or  carriers.  Indirect  transfer  is  quite  possible  through  fingers, 
dishes,  pipes,  handkerchiefs,  toys,  and  other  objects  contaminated  with 
fresh  discharges.  Droplet  infection  also  plays  its  role.  Crowding  and 
close  personal  contact  favor  the  spread  of  the  infection.  The  meningo- 
coccus is  so  frail  that  our  environment  does  not  remain  infective 
very  long. 

While  carriers  are  chiefly  responsible  for  the  spread  of  cerebrospinal 
fever,  it  has  recently  been  recognized  that  there  are  mild  and  abortive 
cases  of  the  disease.  These  "missed'^  cases  spread  the  virulent  infection 
quite  as  actively  as  carriers.  Cases  of  pharyngitis  associated  with  and 
perhaps  due  to  the  meningococcus  have  been  observed  to  occur  fre- 
quently in  endemic  centers  and  in  epidemic  times.     The  theory  of  th'.^ 


CEREBROSPINAL  FEVER  253 

disease  is  that  it  is  ordinarily  mild  and  prevalent,  and  liiat  only  occa- 
sionally does  it  cause  menin^ifitia. 

The  meningococcus  may  pass  through  the  cribriform  plate  of  the 
ethmoid  bone,  but  probably  reaches  the  meninges  in  almost  all  instances 
by  the  blood  stream.    The  disease  is  primarily  a  bacteremia. 

The  meningococcus  is  a  strict  parasite  and  is  unknown  in  nature 
outside  of  the  human  host.  It  is  a  frail,  Gram  negative  microorganism, 
resembling  the  gonococcus.  Both  are  biscuit-shaped  cocci ;  both  grow- 
feebly  on  artificial  media.  They  arc  readily  killed  by  drying,  sunlight, 
heat,  and  other  unfavorable  conditions.  They  live  a  strict  parasitic 
existence  and  cause  diseases  peculiar  to  man,  with  lesions  which  resemble 
each  other,  both  as  far  as  the  character  of  the  inflammation  and  the 
distribution  of  the  cocci  within  the  cells  are  concerned.  As  a  rule,  these 
two  microorganisms  are  usually  distinguished  by  the  source  from  which 
they  are  obtained.  Otherwise  the  differentiation  depends  upon  their 
relation  to  the  fermentation  of  sugars,  agglutination,  and  complement 
fixation.  The  medium  for  the  growth  of  the  meningococcus  must  con- 
tain hemoglobin.  Blood  agar  or  liver  agar  is  suitable.  Involution,  or 
"ghost"  forms,  appear  in  young  cultures  and  after  24  hours  autolysis  is 
very  active. 

All  bacteriologists  now  recognize  the  fact  that  there  are  very  many 
diiferent  strains  of  meningococci,  distinguished  mainly  by  their  reaction 
towards  specific  agglutinins.  As  many  as  52  different  strains  were 
used  to  inject  a  horse  for  the  purpose  of  preparing  a  polyvalent  serum. 
Gordon  recognized  4  groups ;  French  observers  ^'^  speak  of  meningococci 
and  parameningococci,  the  latter  being  commonly  associated  with  the 
disease  in  the  United  States.  A  classification  around  definite  types,  as 
in  the  case  of  pneumococci,  has  been  attempted,  but  is  not  yet  definite. 
The  Hygienic  Laboratory  of  the  United  States  Public  Health  Service 
recognizes  12  strains,  which  comprise  4  agglutinating  and  5  tropin 
groups,  including  all  known  types. 

The  meningococcus  has  been  found  in  the  blood  almost  constantly 
in  the  early  stages  of  the  disease.  The  modern  notion  of  cerebrospinal 
fever  is  that  it  is  primarily  a  septicemia  with  a  predilection  to  localize 
in  the  meninges.  Other  structures  are  often  attacked,  especially  the 
joints  and  the  heart  valves.  In  fulminating  cases  the  septicemia  may 
overshadow  the  meningitis.    Death  may  occur  in  24  hours,  or  less. 

The  effect  of  sunlight  on  the  meningococcus  is  rather  surprising,  the 
organism  being  very  resistant  to  it.  Elser  and  Huntoon  *®  found  that 
some  strains  survived  eight  or  nine  hours'  exposure;  Foster  and  Gas- 
kell,*^  seven  hours'  exposure.     All  strains  tested  survived  one  or  two 

"Dopter:     Compt.  Rend.  8oc.  de  Biol.,  1909,  67,  p.  74. 

^Journ.  Med.  Research,  XX,  1909,  p.  494. 

**  Cerebrospinal  Fever.     Cambridge  Univ.  Press,  1916. 


254    DISEASES  FEOM  DISCHARGES  OF  MOUTH  AND  NOSE 

hours'  exposure  to  full  sunlight.  Drying,  on  the  other  hand,  has  a 
marked  effect  in  killing  meningococci.  No  growth  could  be  obtained 
from  cover  slips  with  meningococcus  cultures  after  five  or  ten  minutes' 
dr}dng  in  a  sulphuric  acid  desiccator.  When  dried  on  glass  in  ordinary 
air,  twenty-four  hours'  exposure  has  been  found  by  various  observers  to 
destroy  the  organism.  Elser  and  Huntoon  found  that  under  certain 
circumstances  the  meningococci  can  survive  somewhat  longer.  It  is 
very  sensitive  to  germicides  and  heat. 

Carriers. — Healthy  passive  carriers  outnumber  the  cases  of  cerebro- 
spinal fever  10  or  30  to  1.  Persons  directly  associated  with  the 
patient  rarely  take  the  disease,  but  often  become  carriers  and  thus 
transmit  the  infection  to  others,  and  these  to  others  and  so  on  indefi- 
nitely. Only  a  small  percentage  of  carriers  is  susceptible  and  develops 
the  disease.  Cerebrospinal  fever  is  disseminated  almost  wholly  by, 
carriers. 

The  meningococcus  is  found  quite  constantly  in  the  nasopharynx 
during  the  first  five  days  of  the  disease.  It  then  begins  to  disappear 
and  is  gone  after  four  weeks  or  a  few  months  of  convalescence.  Only 
rarely  are  chronic  active  carriers  found.  On  the  other  hand,  a  large 
proportion  of  the  healthy  persons  who  come  in  immediate  contact  with 
a  case  or  a  carrier  become  carriers.  The  healthy  passive  carrier  there- 
fore is  the  chief  factor  in  disseminating  the  infection. 

The  number  of  carriers  varies  with  circumstances.  In  Boston  in 
1917,  we  found  from  1  per  cent,  among  persons  who  had  no  known 
contact  with  the  disease,  up  to  80  per  cent,  among  intimate  contacts 
under  military  conditions.  On  account  of  the  carrier  state  in  this 
infection,  Gordon  considers  all  persons  who  have  come  within  3  yards 
of  a  case  under  conditions  favorable  for  infection  as  "contacts." 

A  mother  who  nurses  a  meningococcic  infant  is  sure  to  become  a 
carrier,  and  vice  versa.  Of  16  room-mates  of  a  soldier  stricken  with 
meningitis,  10  were  carriers.  The  meningococcus  has  been  found  in 
as  many  as  100  per  cent,  of  those  in  the  immediate  entourage  of  a  case. 
It  was  a  common  experience  during  the  World  War  to  find  20,  30  and  40 
per  cent,  of  a  command,  in  the  army  or  navy,  to  be  carriers.  The  per- 
centage increases  with  the  degree  of  crowding  and  the  intimacy  of  con- 
tact. Where  people  eat,  sleep,  work,  and  wash  together  as  in  camps 
and  on  shipboard,  there  is  every  facility  for  interchange  of  the  flora  of 
the  mouth  and  nose. 

The  number  of  carriers  varies  with  factors  other  than  crowding. 
There  are  more  in  the  cold  months  than  in  summer,  more  when  an 
epidemic  is  fully  developed  than  during  the  waxing  and  waning  stages, 
and  more  in  severe  epidemics  than  in  mild. 

Most  carriers  are  temporary,  at  least,  the  meningococci  cannot  be 
found  after  a  month  or  two.    Hundreds  of  carriers  observed  in  Boston 


CEREBROSPINAL  FEVER  255 

during  the  World  War  cleared  up  pruniptly  with  the  coiniiig  of  warm 
weather.     This  is  a   common   experience. 

Almost  pure  cultures  of  meningococci  are  obtained  from  the  naso- 
pharynx of  many  carriers;  in  others  only  an  occasional  colony.  All 
intermediate  grades  occur.  Only  a  very  small  percentage  of  the  carriers 
<leveIops  the  disease.  This  may  be  due  to  an  immunity  or  to  lack  of 
facilitating  factors  which  determine  infection  of  the  meninges.  Most 
carriers  are  adults,  whereas  the  disease  has  a  special  predilection  for 
children.  Differences  in  the  anatomical  structure  of  the  lymphatic 
structure  may  account  for  the  resistance  of  adults.  The  quantity  of 
carriers  does  not  seem  to  influence  the  incidence  of  the  disease.  During 
the  World  War  tiie  number  of  carriers  discovered  was  so  great  that  it 
became  impractical  from  a  military  standpoint  to  isolate  them.  In  some 
places  separate  training  camps  for  meningitis  carriers  were  established. 

There  is  no  evidence  that  chronic  carriers  develop  the  disease.  I  can- 
not escape  the  conviction  that  many  of  the  carriers  of  meningococci  are 
not  dangerous,  either  to  themselves  or  their  fellow  men.  This  may  be 
on  account  of  the  lack  of  virulence  of  the  organism.  Perhaps  we  have 
a  similar  situation  with  meningococcus  carriers  that  we  have  in  diph- 
theria carriers,  but  we  have  no  method  at  present  of  distinguishing  true 
or  virulent  carriers  of  cerebrospinal  fever  from  the  harmless  varie- 
ties.^° 

Many  measures  have  been  tried  to  cure  carriers.  Local  applications 
of  germicidal  substances  such  as  chloramin  in  0.5  to  1.0  solutions  (Gor- 
don), peroxid  of  hydrogen,  various  cresol  preparations,  permanganate 
of  potash,  and  zinc  sulphate  have  been  tried.  The  difficulty  is  in  reach- 
ing the  meningococci.  Warm,  moist  rooms,  with  and  without  germi- 
cides added  to  the  air,  have  been  tried.  Vaccines  do  not  relieve  carriers. 
Those  with  tonsillitis  and  catarrhal  inflammation  of  the  nasopharynx 
lose  the  meningococcus  more  slowly  than  those  with  normal  mucous 
membranes.    No  measures  so  far  are  effective. 

The  Recognition  of  Meningococcus  Carriers. — The  specimen  should 
be  taken  from  the  roof  of  the  nasopharynx,  with  a  sterile  cotton 
swab,  guarded  by  a  glass  tube,  as  shown  in  the  illustration  (Fig.  18). 
It  is  iinportant  to  prevent  contaminations  by  organisms  in  the  mouth 
and  saliva. 

Proper  technic  in  obtaining  the  specimen  and  in  seeding  the  plates 
can  only  be  gained  by  practice. 

The  meningococcus  is  very  frail,  and  therefore  the  plates  should  be 
made  immediately.  It  is  very  sensitive  to  acid  and  is  soon  destroyed 
by  the  acidity  of  contaminating  organisms.  Sodium  chlorid  is  also  toxic 
to  the  meningococcus,  and  therefore  salt  solution  should  not  be  used  as 
a  diluent,  and  salt  is  commonly  omitted  from  the  culture  media. 

*»  Ponder,  Brit.  Med.  Joum.,  Sept.  18,  1920,  p.  42.7. 


256    DISEASES  FEOM  DISCHARGES  OF  MOUTH  AND  NOSE 

The  meningococcus  may  be  grown  upon  sheep-serum  dextrose  agar, 
ascitic  agar,  blood-serum  agar,  pea-extract  trypsin  agar,  or  liver  agar. 

The  sheep-serum  agar  is  made  with  one  part  of  sheep  serum  and 
three  parts  of  double  distilled  water.  The  sheep  serum  is  obtained  by 
clotting  and  centrifuging.  This  diluted  serum  is  then  sterilized  frac- 
tionally in  the  Arnold  for  thirty  minutes  on  three  successive  days.  The 
agar  is  prepared  separately  with  2  per  cent,  agar  and  1  per  cent,  peptone. 


Fig.  18. — West  Swab  Tube. 


reaction  0.2  to  phenolphthalein.    The  plates  are  made  by  adding  1  c.  c. 
of  the  diluted  sheep  serum  to  5  c.  c.  of  the  liquefied  agar  at'40°  C. 

The  Petri  plate  is  seeded  with  the  swab  by  simply  touching  the  tip  to 
one  place  on  the  plate.  From  this  spot  the  material  is  spread  by  means 
of  a  loop  or  flat  wire.  The  plate  is  then  incubated  over  night,  at  37°  C. 
Watch  for  small  moist  colonies  with  regular  outline ;  then  let  the  plates 
stand  at  room  temperature  (about  25°  C.)  for  several  hours.    This  per- 


v/ 


Fig.  19. — Diagram  Illustrating  the  Method  of  Taking  Material  from  the 
Nasopharynx  by  Means  of  a  Special  Swab.  W — ^wire  holder  of  S — swab; 
P — soft  palate;  D — tongue  depressor.      (After  Dopter. ) 

mits  the  colonies  of  Micrococcus  catan-Jialis  to  grow  and  affords  a  ready 
method  of  differentiation,  for  the  meningococcus  does  not  multiply  at 
room  temperature. 

Young  meningococcus  colonies  are  colorless,  translucent,  have  a  regu- 
lar contour  (lens  effect),  uniform  granular  structure,  mix  easily  in  salt 
solution,  and  make  an  homogeneous  suspension.  Suspicious  colonies  may 
be  tested  directly  by  the  drop  method  on  a  microscopic  slide,  fished  to 
sheep-serum  dextrose  agar  slants  or  other  suitable  media,  incubated  over 
night,  and  tested  for  macroscopic  agglutination.     The  cultures  for  the 


CEEEBTJOSnXAL  FEVER  257 

agglutination  tost  should  lie  less  than  twciily-rdiir  hours  old,  for  by  ti)at 
time  involution  forms  a])pi'ar,  and  the  ohlcr  colonics  make  less  satisfac- 
tory suspensions. 

The  agglutination  is  best  done  maeroscopically  at  56°  C.  and  the  tubes 
are  allowed  to  stand  at  this  temperature  for  12  to  20  hours  before  taking 
the  final  reading. 

Cultures  tliat  are  agglutinated  with  a  dilution  of  1:100  with  a  poly- 
valent serum,  but  that  fail  to  agglutinate  in  normal  control  serum  in 
half  this  titer,  may  l)e  regarded  as  presumptively  positive.  After  the 
presumptive  test,  careful  study  of  the  culture  must  be  made  in  order  to 
identify  it. 

The  meningococcus  must  be  carefully  distinguished  from  ^licrococcus 
flavus,  Micrococcus  crassus,  ]\Iicrococcus  pharyngis  siccus,  Micrococcus 
catarrhalis,  and  other  confusing  organisms.  For  details  see  Olitsky's 
method  ^^  and  Krumwiede's  macroscopic  slide  agglutination  test.^^ 

Prevention. — A  better  knowledge  of  the  facts  concerning  cerebro- 
spinal fever  has  shaken  our  confidence  in  the  practical  value  of  preven- 
tive measures.  Theoretically  the  case  is  plain ;  practically,  very  difficult. 
The  wide  prevalence  of  the  infection,  the  large  number  of  carriers,  the 
existence  of  mild  and  abortive  cases,  all  add  to  the  complexity  of  the 
administrative  control  of  the  disease.  It  is  not  clear  that  any  of  the 
measures  so  far  taken  have  either  materially  influenced  the  course  of 
epidemics  or  prevented  the  spread  of  the  disease. 

The  first  problem  is  the  recognition  of  cases  and  strict  isolation  with 
a  view  of  diminishing  the  number  of  carriers.  Cerebrospinal  fever  is  a 
disease  which  requires  skilled  laboratory  facilities,  and  these  should  be 
provided  by  health  authorities  in  all  communities. 

Individual  prophylaxis  consists  in  guarding  against  the  well  known 
predisposing  causes  such  as  over-exertion,  fatigue,  exposure,  depressing 
influences  of  all  kinds,  and  catarrhal  inflammation  of  the  nasopharynx. 
Coryzas  and  catarrhas  should  receive  attention,  because  they  are  not 
only  facilitating  factors  of  infection,  but  are  sometimes  associated  with 
meningococci.  Crowding  must  be  avoided.  Sprays  and  douches  have 
no  protective  value,  and  injudiciously  used  may  be  mischievous.  They 
should  be  used  only  under  skilled  medical  advice.  Sanitary  habits 
of  the  sort  that  discourage  the  carrying  of  infection  to  the  mouth  and 
nose  should  be  taught  and  learned.  General  health  and  the  tone  of  the 
machine  should  be  maintained. 

In  military  practice,  the  isolation  of  meningitis  carriers  is  not  only 
extravagant  and  against  military  efficiency,  but  also  impractical  and 
non-effective.  The  search  for  carriers  and  their  care  should  not  cause 
neglect  of  the  more  general  measures,  such  as  prevention  of  crowding, 

^J.  A.  M.  A.,  LXX,  3,  Jan.  19,  1918,  p.  153. 
^Ibid.,  LXIX,  1917,  P.  359. 


258    DISEASES  FROM  DISCHARGES  OF  MOUTH  AND  NOSE 

control  of  hand  to  mouth  infection,  the  allowance  of  ample  time  for  the 
"hardening  and  seasoning"  of  recruits,  protection  from  weather,  over- 
work, and  fatigue,  and  the  use  of  all  measures  that  will  promote  the 
general  health  of  the  command. 

We  must  frankly  admit  that  when  cerebrospinal  meningitis  has  once 
become  epidemic  it  cannot  be  stamped  out  by  any  known  means  of  prac- 
tical application. 

This  does  not  mean  that  we  should  assume  a  supine  attitude,  for, 
even  though  the  disease  cannot  be  satisfactorily  controlled,  a  certain 
number  of  secondary  cases  can  be  prevented.  Vaccines  have  been  tried, 
but  their  usefulness  has  not  been  established.  The  procedure  is  logical 
and  deserves  extended  observation.  Agglutinins  develop  in  the  blood 
of  those  vaccinated. 

Antimeningitis  serum  is  useful  in  the  treatment  of  the  disease;  it 
is  not  practical  as  a  preventive.  It  must  be  introduced  into  the  subdural 
space  "by  lumbar  puncture.  Intravenous  injections  to  counteract  blood 
infection  are  also  indicated.  The  serum  should  always  be  matched  with 
the  particular  strain  of  meningococcus  to  obtain  specific  results.  The 
serum  should  be  provided  free  of  cost  or  at  a  minimum  price  by  health 
authorities.  Further,  boards  of  health  should  provide  laboratory  facili- 
ties for  the  bacteriological  diagnosis  of  the  disease,  and  the  recognition  of 
carriers. 

REFERENCES 

Elser  and  Huntoon  :     Monograph.     Jour.  Med.  Research,  1909,  XX,  pp. 

377-536. 
Foster  and  Gaskell  :     Cerebrospinal  Fever.    Cambridge  University  Press, 

1916. 
Flexner,  Simox  :     Mode  of  Infection,  Means  of  Prevention  and  Specific 

Treatment  of  Epidemic  Meningitis.    J.  A.  M.  A.,  Aug.  25  and  Sept.  1, 

1917. 


CHAPTER  IV 
INSECT-BORNE  DISEASES 

GENERAL  CONSIDERATIONS 

The  fact  that  disease  may  be  transmitted  through  the  bites  of  in- 
sects was  suspected  for  years,  but  it  was  not  until  1893  that  it  was 
demonstrated  as  a  new  principle  by  Theobald  Smith  in  the  case  of 
Texas  fever  of  cattle  and  the  tick.^  Since  then  many  diseases  have 
been  added  to  the  list,  which  is  constantly  growing.  We  now  know 
that  some  diseases  are  always  transmitted  through  insects  and  others 
occasionally.  A  thorough  comprehension  of  the  subject  is  necessary  for 
sanitarians  and  others  in  the  fight  against  disease  in  all  climates  and 
in  all  countries. 

It  may  be  stated  as  a  general  law  that,  if  a  period  of  incubation 
in  the  insect  is  necessary,  it  indicates  that  the  parasite  probably  be- 
longs to  the  animal  kingdom  and  passes  part  of  its  life  cycle  within 
the  insect.  This  constitutes  the  so-called  extrinsic  period  of  incubation. 
Malaria  and  yellow  fever  are  examples  of  this  class,  which  is  spoken 
of  as  biological  transmission.  If,  on  the  other  hand,  insects  convey 
infection  at  once  without  a  period  of  incubation  in  the  insect,  the  trans- 
fer is  a  meclianical  one;  in  this  case  the  insect  does  not  play  the  part- 
of  an  intermediate  host  in  the  true  biological  sense,  and  there  is  no 
cy-cle  of  development  of  the  parasite  within  the  insect.  These  cases  are 
almost  all  bacterial  infections. 

It  may  be  stated  as  a  general  rule  that  the  insect  hosts  are  not 
harmed  by  the  parasites  which  they  harbor  and  which  are  pathogenic 
for  man.  Thus,  the  malarial  protozoon  is  pathogenic  for  man,  but  appar- 
ently harmless  for  the  mosquito.  The  same  is  tine  of  yellow  fever  and 
the  Stegomyia,  Texas  fever  and  the  tick,  plague  and  the  flea,  sleeping 
sickness  and  the  tsetse  fly,  typhoid  and  the  house  fly,  typhus  fever  and 
the  louse,  etc. 

The  intermediate  host  in  the  zoological  sense  is  that  animal  which 
harbors  the  asexual  phase  of  the  life  cycle  of  the  parasite;  the  definitive 
host  is  the  animal  which  harbors  the  sexual  phase.    Thus,  in  malaria  man 

^  The  other  names  associated  with  the  early  work  upon  insects  and  their  re- 
lation to  disease  are:  Manson,  Finlav.  Ross,  Grassi,  and  the  U.  S.  Army  Com- 
mission— Reed,  Carroll,  Lazear,  and  Agramonte. 

259 


260  INSECT-BOENE  DISEASES 

is  the  intermediate  host,  the  mosquito  the  definitive  host.     In  popular 
parlance,  the  insects  are  spoken  of  as  the  intermediate  hosts  in  all  cases. 

Insects  transfer  infections  mechanically  in  a  variety  of  ways.  The 
mouth  parts,  legs,  or  outer  surfaces  of  the  body  may  be  smeaTed  with 
the  virus,  which  is  then  simply  carried  to  the  lips,  fingers  or  food,  and 
thus  enters  the  susceptible  individual ;  or  the  virus  may  remain  attached 
to  the  proboscis  of  a  biting  insect,  thus  transferring  the  infection  very 
much  as  a  hypodermic  needle  would;  or  the  virus  may  be  contained 
in  the  dejecta  of  the  insect  and  be  scratched  or  rubbed  into  the  wound 
made  by  the  bite;  or  the  virus  may  be  contained  in  the  digestive  tube 
or  the  body  cavity  and  be  released  when  the  insect  bites  or  is  crushed. 

Insect-borne  infections  are  types  of  true  endemic  diseases,  and  they 
are  necessarily  limited  in  geographical  distribution  to  the  habitat  of  the 
insect  host.  They  prevail  especially  in  tropical  and  warm,  mojst  regions, 
where  insect  life  abounds.  The  seasonal  prevalence  of  insect-borne  dis- 
eases is  therefore  distinctive. 

As  a  rule,  only  one  species,  or  at  most  a  single  genus,  acts  the  part 
of  a  host  for  any  particular  infection,  excepting  in  the  mechanical 
transference  of  infection  by  insects.  Malaria  is  confined  to  Anopheles, 
yellow  fever  to  Stegomyia,  Texas  fever  to  the  Margaropus  (innulatus, 
sleeping  sickness  to  the  Glossina  palpalis,  etc.  This  is  a  question  of 
specificity.  The  specific  nature  of  some  of  these  diseases  may  be  due 
to  the  fact  that  the  parasite  is  not  pathogenic  for  other  hosts.  Thus, 
most  of  the  insect-borne  diseases  do  not  occur  naturally  in  the  lower 
animals  and  cannot  as  a  rule  be  transferred  even  though  large  amounts 
of  the  infected  blood  be  inoculated.  The  disease  may  be  specific,  in  the 
sense  that  it  is  confined  to  one  species,  because  the  insect  conveying  the 
infection  refuses  to  bite  other  than  its  own  host.  True  specificity  is 
found  in  all  the  cases  of  biological  transference,  whereas  mechanical 
transference  of  infection  may  take  place  through  widely  separated  genera. 

In  some  instances  the  virus  is  transmitted  "hereditarily"  through  the 
insect  from  one  molt  to  another,  and  even  from  one  generation  to  the 
next.  So  far  as  known,  however,  hereditary  transmission  takes  place 
only  in  those  "insects"  having  an  incomplete  metamorphosis,  such  as  the 
ticks.  Brues  suggests  that  the  hereditary  transmission  of  a  virus  is 
practically  impossible  in  insects  passing  through  complete  metamorpho- 
sis, owing  to  the  active  phagocytosis  during  the  pupal  stage. 

Protozoa,  bacteria,  and  even  parasitic  worms  may  be  transferred 
by  insects.  The  character  of  the  disease  cannot  be  predicated  from  the 
nature  of  the  insect  host.  Thus,  ticks  convey  Pirosoma  and  also  spi- 
rochetes; flies  convey  trypanosomes,  bacteria,  the  eggs  of  worms,  and 
a  variety  of  other  infections;  mosquitoes  are  concerned  in  the  transmis- 
sion of  the  Plasmodium  (a  protozoon,  filaria  (a  round  worm),  and 
spirochetes  (a  filtrable  virus). 


GENERAL  CONSTDERATTONS 


261 


Insect-borne  diseases  may  (icciir  in  ^rcat  cpidciiiics,  as  yellow  fever, 
nialacia,  (Icii^LiUt',  tvplius,  I'clapsiiiL;-  rcxcr,  cic  W'licii  this  occurs  it  means 
that  the  ])arti<'iihir  insect  involved  ]ircvails  in  enormous  numl)('rs  in  the 
epidemic  area. 

Ticks  and  mites  belong  to  the  lower  class  of  the  Arachnida  and 
are  not,  strictly  speaking,  insects  (insecta),  but  are  here  considered  in  the 
same  group  for  practical  convenience. 

All  the  parasitic  animals  wliicli  live  upon  man  and  other  animals 
may  act  as  go-betweens  in  the  transportation  of  the  microorganisms 
of  disease.  Parasites  which  live  upon  the  skin  are  known  as  ectoparasites, 
in  contradistinction  to  cudu parasites,  which  live  within  the  body.  The 
ectoparasites  may  be  tempo- 
rary parasites,  as  the  mos- 
quito; or  permanent,  as 
the  tick,  which  spends  all 
but  its  earliest  and  last 
days  attached  to  the  skin 
of  its  host.  Between  these 
extremes  there  are  para- 
sites spending  more  or  less 
of  their  life  attached  to  the 
host;  thus,  the  bedbug  and 
flea  are  temporary,  where- 
as lice  are  more  permanent 
parasites. 

Many  of  the  insect-  Fig.  20. — A  South  African  Blood-Sucking  Fly 
,  T.  J,  (Pannonia) ,  Illustrating  Long  Proboscis 

borne  diseases  were  form-  ,^^  p^^^^^j^   Heavy   Fur   of  Certain   Ani- 

erly  known  as  "place  dis-  mals.      (Brues.) 

eases."      Thus,    in    yellow 

fever  it  was  realized  that  the  infection  was  not  conveyed  directly  from 
man  to  man,  but  it  was  believed  that  the  house  or  place  became  in- 
fected, and  it  was  thought  that  the  virus  lived  in  the  soil,  upon  the 
bedding,  or  on  the  clothing.  This  led  to  the  notion  that  fomites  or 
inanimate  objects  played  an  important  role  in  the  transference  of  dis- 
ease. The  early  studies  in  bacteriology  gave  countenance  to  this  view 
until  our  knowledge  of  the  part  played  by  insects  ^nd  the  importance 
of  "contacts"  and  "carriers"  has  placed  fomites  in  a  subordinate  and 
oftentimes  negligible  position  in  public  health  work. 

The  prevention  of  the  insect-borne  diseases  depends  upon  a  knowledge 
and  thorough  comprehension  of  three  factors:  (1)  the  disease,  (2)  the 
parasite,  and  (3)  the  insect.  The  suppression  or  control  of  the  insect 
depends  upon  a  precise  knowledge  of  its  biolog}'.  Entomology,  therefore, 
has  become  a  vitally  important  subject  so  far  as  preventive  medicine  is 
concerned.     Without  an  acquaintance  of  the  life  history  and  habits  of 


262  IN"SECT-BORNE  DISEASES 

the  insect  host  there  will  be  economic  loss,  wasted  energy,  and  disappoint- 
ing results.  The  malarial  mosquito  is  active  at  night  and  breeds  in  the 
swamps;  the  yellow  fever  mosquito  is  active  by  day  and  breeds  about 
houses.  Other  mosquitoes  have  their  own  particular  breeding  and  hiding 
places.  The  suppression  of  lice  depends  largely  upon  bodily  cleanliness, 
the  suppression  of  the  bedbug  upon  house  cleanliness,  the  dangerous  fleas 
come  largely  from  association  with  other  animals,  the  flies  from  manure 
and  decomposing  organic  filth,  the  ticks  from  other  animals  and  from  the 
infested  ground  and  woods. 

For  the  control  of  the  inseet-borne  diseases  it  is  not  always  neces- 
sary to  exterminate  the  particular  insect  host.  In  fact,  the  extermination 
of  a  particular  species,  much  more  a  genus,  is  practically  a  biologic 
impossibility.  A  material  reduction  in  the  numbers  of  the  insects  in  a 
particular  area  will  often  result  in  an  elimination  of  the  disease. 

The  geographical  distribution  of  the  disease  is  always  more  limited 
than  the  geographic  distribution  of  the  insect  host:  x\nopheles  exist 
in  many  places  where  there  is  little  or  no  malaria.  Stegomyia  mos- 
quitoes are  numerous  in  the  Philippines,  but  yellow  fever  has  not  yet 
been  carried  there. 

In  the  migration  of  insect-borne  diseases  it  is  usually  the  human 
host  and  not  the  insect  that  acts  as  the  traveler.  Insects,  as  a  rule,  do 
not  go  great  distances  of  their  own  volition,  and  never  overseas  or 
from  one  country  to  another,  unless  taken  in  the  conveyances  of  man 
or  upon  some  animal  host.  When  yellow  fever  or  malaria  go  from  one 
country  to  another,  the  infection  is  translated  in  man.  The  infected 
mosquitoes  are  rarely  transported,  except  occasionally  upon  wooden 
sailing  vessels  with  water  barrels  that  afford  breeding  places. 

An  apparent  exception  to  this  statement  is  the  case  of  plague.  It  is 
the  rat  rather  than  man  that  spreads  plague  from  land  to  land.  In  this 
case,  however,  the  disease  is  primarily  an  infection  of  the  rat,  which 
carries  the  flea  along  and  man  is  secondarily  attacked.  Mies,  mosquitoes, 
and  other  insects  are  known  to  travel  or  be  blo^vn  a  mile  or  more  upon 
the  wing. 

An  effective  campaign  against  mosquitoes,  flies,  or  other  insect 
pests  requires  the  expenditure  of  time  and  money.  Further,  it  requires 
the  assistance  of  the  entomologist,  the  engineer,  and  the  practical  admin- 
istrator. When  the  campaign  involves  extensive  drainage  or  filling-in 
operations,  this  calls  for  the  services  of  an  engineer  who  has  specialized 
along  these  lines.  To  attack  the  problem  without  a  complete  knowledge 
obtained  from  a  careful  study  of  the  habits  and  breeding  places  of  the 
particular  species  of  insect  will  probably  result  in  economic  waste.  The 
habits  and  habitat  of  some  species  may  vary  in  different  localities,  and 
a  careful  study  of  the  local  conditions  is  important  to  insure  success.  In 
the  organization  of  a  mosquito  campaign  the  several  branches  of  the  work 


GENERAL  CONSIDERATIONS  263 

may  be  allotli'd  to  si)ecial  divisions,  cacli  coiisistiiiff  of  a  foreman,  and 
crew.  These  men  become  skilled  in  tlieir  particular  duties,  and  efficiency 
is  thereby  greatly  promoted.  One  division  shouM  have  charge  of  the 
oiling,  another  of  the  fumigation,  another  should  seek  to  destroy  the 
natural  breeding  places,  another  should  attend  to  the  screening,  etc.  In 
fly  suppression  one  division  should  look  after  the  storing  and  handling 
of  horse  manure,  another  to  garbage  and  organic  refuse,  and  so  on.  All 
the  Mork  must  be  centralized  under  the  direction  of  one  person  Avith 
executive  al)ility  and  a  thorough  understanding  of  the  problem. 

The  suppression  of  insects  and  household  vermin  is  essentially  a 
question  of  cleanliness.  The  most  effective  measures  are  those  which 
strike  at  the  breeding  places,  and  these  will  be  considered  separately  under 
mosquitoes,  flies,  ticks,  lice,  fleas  and  bedbugs.  Next  to  the  suppression 
of  their  breeding  places,  the  most  important  measure  in  a  household 
is  to  starve  out  these  pests.  Food  must  be  so  protected  that  insects, 
mice,  and  rats  cannot  gain  access  to  it.  Floors  and  other  surfaces 
must  be  kept  clean,  so  that  they  do  not  have  the  least  film  of  organic 
dirt  upon  which  insects  feed.  There  should  be  no  cracks  or  crevices 
to  collect  dust  and  dirt,  which  offer  comfort  for  insect  life.  Cleanli- 
ness and  incessant  care  must  not  only  be  exercised  in  the  household 
itself,  particularly  in  kitchen,  pantry,  dining  room,  cellar,  attic,  and 
toilets,  but  must  also  include  the  back  yard  and  surroundings  of  the 
house.  Old  cans  and  broken  bottles,  rubbish,  garbage,  and  general  untidi- 
ness around  the  household  afford  breeding  places,  hiding  places,  or  food 
for  vermin. 

All  the  blood-sucking  parasites  must  be  regarded  as  dangerous.  If 
they  do  not  play  the  role  of  an  intermediate  host  in  the  biological 
sense,  they  may  occasionally  transfer  infections  in  a  mechanical  way, 
or  the  little  wounds  may  allow  the  entrance  of  such  infections  as  ery- 
sipelas, the  pus  cocci,  anthrax,  tetanus,  and  other  microorganisms.  Fur- 
ther, all  blood-sucking  parasites  are  potentially  dangerous,  in  that 
new  diseases  may  be  established  as  the  old  ones  must  have  been  es- 
tablished at  one  time  through  the  triple  alliance  of  host,  insect,  and 
parasite. 

Insect-borne  diseases  may  be  controlled  by  attacking  the  insect,  or  the 
parasite  in  the  host,  or  both.  The  object  should  be  to  attack  the  weak- 
est link  in  the  chain. 

Science  has  demonstrated  the  danger  from  insects.  Experience  long 
ago  decided  that  a  healthy  home  must  be  free  of  insects  and  vermin  of 
all  kinds — it  remains  for  the  future  to  extend  this  kind  of  cleanliness 
to  municipal  housekeeping  and  rural  sanitation. 

The  principal  insect-borne  diseases,  their  causes,  and  the  insect  re- 
sponsible in  each  case  are  stated  in  the  following  table : 


264 


INSECT-BOENE  DISEASES 
The  Principal  Insect-borne  Diseases 


MOSQUITOES 


Malaria     (Laveran,     1880,     the 
parasite;    Ronald   Ross,    1895- 
1898,  relation  to  the  mosquito) 

Plasmodium  malariae  (Laveran) 
Plasmodium  vivax  (Grassi  and 

Feletti) 
Plasmodium  falciparum  (Welch) 

Anophelinae 

Yellow   Fever    (Reed,    Carroll, 
Lazear,  and  Agramonte,  1903- 
1902) 

A  filtrable  virus 
Leptospira  icleroides   (Noguchi, 
1919) 

Slegomyia  calopus 

FiLARiAsis     (Demarquay,     1863; 
Manson,  1899) 

Filaria  bancrofti 

Cutex  Jatigans 

JJengue  (Graham,  1903;  Ashburn 
and  Glegg,  1907) 

A  filtrable  virus  (?) 

Stegomyia  calopus 

FLIES 


Sleeping    Sickness    (Gambian) 
(Dutton,  1902) 

Trypanosoma  gambiense 

Glossina  palpalis — A  tsetse_fly 

Sleeping  Sickness   (Rhodesian) 
(Stephens  &  Fantham,  1910) 

Trypanosoma  rhodesiense 

Glossina  morsitans — A  tsetse  fly 

Typhoid,  Cholera,  Dysentery, 
etc.      Contagious    ophthalmia, 
"pink  ej.e,"  erysipelas,  anthrax, 
glanders,  skin  infections.  Small- 
pox and  other  exanthemata. 

Flies  and  other  insects,  by  me- 
chancial  transmission 

Nagana  (of  cattle,  etc.)   (Bruce, 
1895) 

Trypanosoma  brucei 

Glossina  morsitans — A  tsetse  fly 

Surra    (of    horses,    etc.)    (Steel, 
1885) 

Trypanosoma  evansi             ° 

Tabaninae,  Stomoxys  calcilrans. 
and  other  biting  flies;  also  fleas 

Pappataci  Fever   (3  day  fever) 
(Doerr,  1909) 

A  filtrable  virus  (?) 

Phlebolomus  pappatasii — A  dip- 
terous biting  gnat 

Calabar    Swelling     (Loa    loa) 
(Cobbold,  18G4;  Manson,  1891) 

Filaria  diurna 

Chrysops  dimidialus — A  biting  fly 

South  American  Trypanosomi- 
asis (Barbiero  fever)   (Chagas, 
1909) 

Trypanosoma  cruzi 

Lamus  megislus — A  hemipterous 
biting  insect 

Deer-Fly  Fever  (Francis,  1919) 

Bacterium  lularense  (McCoy  and 
Chapin,  1912) 

Biting  fly  (Crysops) 

TICKS 


Texas  Fever  (of  cattle)    (Smith 
&  Kilbourne,  1893) 

Babesia  bigemina 

Margaropus  annulatus 

Rocky  Mountain  Spotted  Fever 
(Ricketts,  1906;  Wolbach,  1916) 

Rickettsia 

Dermacentor  andersoni 

Relapsing    Fever    (W.    Africa) 
(African  tick  fever)  (Dutton  and 
Todd,  1904) 

Spiroschaudinnia  duttoni 

Ornithodorus  m,oubata; 
also    lice,   and    perhaps  bedbugs, 
etc. 

BEDBUGS 


European     Relapsing      Fever 
(Obermeier,  1873) 


Spiroschaudinnia  recurrentis 


Clinocoris  lectularis  (?) 
Pediculi  (?) 


Indian  Kala-azar  (Ross,  1903)       Leishmania  donovani 


Clinocoris  rotundatus 
Conorhinus  (?) 


(Continued  on  next  page.) 


GENERAL  CONSIDERATIONS 
Insect-bome  Diseases —  ( Continued) 


265 


LICE 


Algerian  Relapsing  Fever  (Ser- 
gent  and  Foley,  1910) 

Spiroschaudinnia  berbera 

Pediculi 

European      RELAPSI^JG      Fever 
(Obernieier,  1873) 

Spiroschaudinnia  recurrentis 

Clinocoris  (?) 
Pediculi  (?) 

Asiatic  Relapsing  Fever  (Car- 
ter, 1877) 

Spiroschaudinnia  carteri 

Pediculus  vestimentis  (?) 

Typhus    Fever    (Nicolle,    1909; 
Ricketts  &  Wilder,   1910;  An- 
derson &  Goldberger,  1910) 

Rickettsia  prowazeki 

Pediculus  veslimenli  (corporis) 
Pediculus  capitis 
Pediculus  humanus 

Trench  Fever 

Rickettsia  pediculi 

Pediculus  huinanus,  var.  corporis 

FLEAS 

Plague  (Kitasato,  189i;  Yersin, 
1894) 

Bacillus  pestis 

Xenopsylla  cheopis  and  others 

Infantile   Kala-azar   (Pianese, 
1905) 

Leishmania  infantum 

Ctenocephalus  canis  (?) 

The  following  table  gives  a  list  of  the  principal  diseases  which  are 
transmitted  by  "intermediate"  hosts  other  than  insects. 


disease  and  adult 
parasite 

intermediate  or 

USUAL  host 

INTECTING  STAGE 
OF  PARASITE 

MODE  OF 
INFECTION 

Liver  fluke 
Fasciola  hepatica 

Snails 

Limnaeus 

Cercariae 

Ingestion 

Liver  fluke 
Clonorchis  endemicus 

Fish 

Encysted  stage 

Ingestion 

Lung  fluke 
Paragonimus  westermanii 

Fresh-water  crab 
Potamon  dehaanii 

Encysted  larvae 

Ingestion 

"Katayama  disease" 
Schistosomum  janonicum 

Fresh-water  snails 
Katayama  nosophora 

Cercariae 

Through  the 
skin 

Fish  tapeworm 
Dibothricephalus  latus 

Pike,  salmon,  etc. 

Plerocercoids 

Ingestion 

Dog  tapeworm 
Dr^pihdium  caninum 

Dog  fleas  and  dog  lice 

Cysticercoids 

Contact 
with  dogs 

Rat  tapeworm 
Hymenolepis  diminuta 

Meal  moth,  Asopia  farinalis  and 
other  insects 

Cysticercus 

Ingestion 

Dwarf  tapeworm 
Hymenolepis  nana 

(?) 

Cysticercoid 

Ingestion 

Pork  tapeworm 
Taenia  solium 

Swine 

Cysticercus 

Ingestion 

Beef  tapeworm 
Taenia  saginata 

Cattle 

Cysticercus 

Ingestion 

Hydatid  disease 
Echinococcus  granulosus 

Dogs 

Onchosphere 

Ingestion 

Guinea  worm 
Dracunculus  medinensis 

A  small  crustacean 
Cyclops  coronatus 

Larvae 

Ingestion 

Lamblia  intestinalis 

Rats,  mice 

Encysted  stage 

Ingestion 

Trichinosis 
Trichinella  spiralis 

Swine 

Encysted  stage 

Ingestion 

Infectious  Jaundice,  Weil's  Dis- 
ease 
Spirochaeta  icterohaemorrhagiae 

Rats* 

Other  diseases  transmitted  by  rats,  see  page  335. 


266  INSECT-BORNE  DISEASES 


INSECTICIDES  ^ 

Practically  all  germicidal  agents  are  also  insecticides.  There  are 
some  exceptions  to  this  statement,  notably  formaldehyd,  which  is  a 
potent  germicide,  but  has  little  or  no  effect  upon  insect  life  in  its  gaseous 
state. 

The  action  of  insecticides  may  be  considered  under  three  classes : 
(1)  those  that  act  as  general  protoplasmic  poisons,  such  as  strong  acids 
or  alkalies,  hydrocyanic  acid,  sulphur  dioxid,  etc.;  (2)  those  that  suf- 
focate the  insects,  such  as  oily  substances;  (3)  those  that  act  upon 
the  nervous  structures,  such  as  chloroform,  ether,  and  other  general 
anesthetics. 

Another  classification  considers  insecticides  under  four  groups:  (1) 
those  used  by  contact  in  liquid  forna  or  in  solution;  (2)  those  used 
by  contact  in  dry  or  powdered  form;  (3)  those  used  by  contact  in 
vapor  form;  (4)  those  used  by  mixing  with  food  and  which  are  poisonous 
when  ingested. 

Insects  differ  markedly  in  their  power  of  resisting  insecticides. 
Those  with  well-developed  chitinous  protection,  such  as  bedbugs  and 
roaches,  are  more  difficult  to  kill  than  flies,  fleas,  and  mosquitoes.  Many 
insecticides  have  marked  specific  action.  Thus,  iodoform  kills  lice 
within  10  to  15  minutes,  but  has  practically  no  harmful  action  on 
bedbugs,  and  very  little  effect  on  fleas.  Pyrethrum  has  a  more  powerful 
action  on  bedbugs  than  on  lice,  etc. 

The  most  practical  of  the  insecticides  for  the  destruction  of  the 
winged  insects  in  an  enclosed  space  are  those  that  may  be  used  in  the 
gaseous  state.  Of  these,  sulphur  dioxid,  and  hydrocyanic  acid  gas  are 
most  commonly  employed  and  are  most  reliable.  The  method  of  killing 
insects  by  gases  and  fumes  is  called  fumigation.  See  pages  1352  and  1390. 
Preparation  of  the  Room  for  Fumig^ation. — It  is  more  important  to 
seal  tightly  a  room  in  which  insects  are  to  be  destroyed  than  where 
only  a  germicidal  action  of  the  gas  is  looked  for.  Insects  may  escape 
through  minute  openings,  and  they  may  hide  in  nooks  and  cracks 
where  the  gas  permeates  slowly  and  feebly,  or  may  take  cover  under 
the  folds  of  crumpled  paper  or  folded  fabrics,  and  thus  escape  the  in- 
secticidal  action  of  the  gas.  Self-preservation  tempts  mosquitoes  and 
other  insects,  as  well  as  rats  and  mice,  to  seek  the  light  when  in  the 
presence  of  an  irritating  gas.  It  is,  therefore,  convenient  to  darken 
the  place  to  be  treated,  leaving  one  source  of  light.  The  dead  vermin 
may  then  be  readily  collected  about  this  place. 

''All  insecticides  sold  in  interstate  traffic  in  the  United  States  must  comply 
with  the  Insecticide  and  Fungicide  Act  of  1910,  administered  by  the  U.  S.  Dept. 
of  Agriculture. 


INSECTICIDES 


267 


Strips  of  i)aper  should  be  pasted  over  doors  and  windows.  Cracks 
and  crevices  may  be  calked  with  towels,  waste,  or  other  suitable  sub- 
stance. Ventilators,  fireplaces,  hot-air  registers,  and  all  openings  into 
the  room  must  be  covered,  otherwise  both  the  gas  and  the  insects  will 
escape.  Closets  and  small  doors  should  be  opened  and  all  drawers, 
lockers,  and  similar  places  exposed  in  such  a  way  that  the  gas  may 
have  fresh  access  to  remote  corners.     Furniture  should  be  moved  away 


Fig.  21. — Example  of  Sealixg  Doors  for  Purpose  of  Fumigatiox. 


from  the  walls.  Fabrics,  paintings,  instruments,  bright  metal  work,  or 
other  objects  liable  to  injury  may  be  removed  or  covered,  especially  when 
sulphur  is  used.    See  also  page  1390. 

The  Relative  Efficiency  of  Insecticides. — McClintock,  Hamilton,  and 
Lowe  ^  tested  a  number  of  insecticidal  substances,  the  values  of  which 
are  shown  in  Table  4.  which  gives  a  list  of  the  substances  tested  and 
the  species  of  insects  used  in  the  experiments,  together  with  the  quantity 
of  each  substance  which,  when  properly  transformed  into  vapors,  was 

^Jour.  Am.  Pub.  Health  Assn.,  Vol.  II,  No.  4,  Apr.,  1911,  p.  227. 


268 


INSECT-BORNE  DISEASES 


sufficient  to  kill  the  species  indicated.  The  coefficient  column  shows 
the  inverse  ratio  between  this  quantity  and  8  grams,  the  weight  of 
sulphur  which,  when  burned,  kills  the  bedbug  in  800,000  c.  c.  of  in- 
closed space.  The  efficient  dilution  of  the  vapors  of  any  substances  may 
be  obtained  from  this  coefficient  by  multiplying  by  100,000. 

For  example,  if  one  wishes  to  use  carbon  disulphid,  by  consulting 
No.  28  in  the  table  it  is  shown  that  24  grams  were  required  to  kill 
bedbugs,  while  only  8  grams  of  sulphur  were  required.  It  is  therefore 
only  one-third  as  strong  and  its  coefficient  is  0.3-[-.  Its  efficient  dilu- 
tion is  33,000. 


Table   4. — INSECTICIDES 


Time  of  exposure — Varied  as  conditions   required. 
Column   1 — Quantity  used  to  kill  the  specified  insect. 

Column  2 — Coefficient  of   efficiency   compared   with   the   efficiency   of   sulphur   dioxid 
on  bedbugs. 


Substance 


1  Sulphur  Dioxid  as  Sulphur 

2  Pyridin 

3  Pyridin  Bases  (Merck).. 

4  Quinolin 

5  Creosote  Oil 

6  Carbolic  Acid 

7  Naphthalene 

8  Kerosene 

9  Anilin  Oil 

10  Cedar  Oil 

11  Citronella  Oil 

12  Cloves  Oil 

13  Peppermint  Oil 

14  Pennyroyal  Oil 

15  Australene 

16  Turpentine  (Oregon  Fir). 

17  Oil  Pinus  Palustris 

18  Oil  Turpentine 

19  Turpentine(Mich. Wood) 

20  Benzaldehyd 

21  Nitrcbenzol 

22  Ammonia  28% 

23  Alcohol,  Ethyl 

24  Alcohol,  Methyl 

25  Acetone 

26  Chloroform 

27  Ether  (Ethyl  Oxid)  .... 

28  Carbon  Disulphid 

29  Carbon  Tetrachlorid..  .  . 

30  Chloretone 

31  Camiphor 

32*Nicotin,  80%  Sol 

33  Hydrocyanic  Acid,  as  Po- 

tassium Cyanid 

34  Paraform 

35tFormaldehyd  40%  Sol..  . 

36  Stramonium  Leaves.  .  .  . 

37  Sabadilla  Seeds 

38  Chrysanthemum  Flowers 


Bedbug 


4  + 

8 

8  + 
16  + 

6.3  + 
11.5  + 

4  + 

4  + 

4  + 

8  + 

8  + 
36  + 
16  + 
20  + 
16  + 

4  + 

8  + 
36  + 
80  + 
80  + 
40  + 
40  + 

24 

40 

4  + 

8  + 
25 

6.3 

8  + 
54  + 
10 

8  + 
80  + 


1 

1 

1.6 

1 

2 

1 

1 

0.5 

1.3 

0.7 

2 

2 

2 

1 

1 

0.2 

0.5 

0.4 

0.5 

2 

1 

0.2 

0.1 

0.1 

0.2 

0.2 

6!3 

0.2 
2 

1 
4 

1.3 
1 

0.1 
0.8 

6!i 


Cockroach 


4 
4 
4 
8 
4  + 


16  + 

6.3  + 
111.5 

4  + 
4  + 
4  + 


36  + 
16  + 
20  + 
24  + 

4  + 

8 
36  + 
80  + 
80  + 
40  + 
40  + 

36'" 

40  + 

4  + 
8 
25 

6.3 

8  + 
54  + 
10 

8  + 
80  + 


2 
2 
2 

1 

2 

1 

1 

0.5 

1.3 

0.7 

2 

2 

2 

1 

1 

0.2 

0.5 

0.4 

0.3 

2 

1 

0.2 

0.1 

0.1 

0.2 

0.2 

6.'2 
0.2 
2 

1 
4 

1.3 

1 

0.1 

0.8 

o'.i 


House  Fly 


3.2 

2 

1.6 


2 

4  + 

6.3 

8 

2 

2 

4 

4 

3.2 
36  + 

4 
20 
16 

2 

1.6 
20  + 
80  + 
80  + 
40  + 
16  + 

15  + 
4 

40  + 
4 
4 
6 

2 
4 

16  + 
10  + 
16 

2.6 


2.5 

4 

5 

4" 
1 
4 
2 

1.3 
1 
4 
4 
2 
2 

2.5 
0.2 
2 

0.4 
0.5 
4 
5 

0.4 
0.1 
0.1 
0.2 
0.5 
0.5 
2 

0.2 
2 
2 
20 

4 

2 

0.5 

0.8 

0.5 

3 


Clothes 
Moth 


2.6 

i;6 

1.6 
2 


4 

4 

6.3 

2 

4 

2 

4  + 

4 

8 
16  + 

4 
20 
16 

2 

1.6 
36  + 
80  + 
80  + 
40  + 
16 

2    ' 

40  + 

4 

4 
25 


16  + 

10  + 

16  + 

4 


3 
5 
5 

4 

8 

1 

2 

2 

1.3 

4 

2 

4 

2 

2 

1 

0.5 

2 

0.4 

0.5 

4 

5 

0.2 

6.1 

0.1 

0.2 

0.5 

4" 
0.2 
2 
2 

40 


1 

0.5 

0.8 

0.5 

2 


Mosquito 


3.2 

1.6 


4 

1 

1 
1 
1 
2 
1 
2 
8 
2 
10 


1 

1 
20 
80 
80  + 
14a- 
16  + 

"4" 

40 
1 
2 

1 

2 

1 

1+ 
4 

1 


2.5 
5 


4 
1 
4 
0.8 


0.4 
0.1 
0.1 
0.2 
0.5 

26" 
0.2 
8 
4 

100 

40 
8 
1 
2 
2 


The   +    sign   after  a  number  indicates  that  this  quantity  was  the  largest  used  and 

■    that  it   was   insufficient. 
•  Coefficient  of  nicotin  based  on   100%    alkaloid. 

t  Quantity  of  formaldehyd  to  be   an  efficient  germicide  is  13%   c.  c.  or  a  coefficient 
of  0.625. 


INSECTICIDES  2G9 

The  best  methods  of  generating  gases  for  fumigating  purposes  are 
considered  below.  For  further  information  concerning  these  substances, 
with  special  reference  to  their  germicidal  action,  see  Section  XIV. 

To  insure  success  the  gas  used  to  fumigate  a  room  should  be  liber- 
ated in  a  large  volume  in  a  short  time.  If  the  gas  is  evolved  slowly 
much  of  it  will  be  lost  before  the  room  can  become  charged  with  a 
sullicient  amount  to  kill  the  insects. 

The  amount  of  gas  and  the  time  of  exposure  stated  in  each  case 
are  the  minimum.  When  large,  leaky,  or  irregularly  shaped  spaces  are 
to  be  fumigated,  the  amount  of  gas  should  be  increased  and  the  time 
of  exposure  prolonged.  It  is  also  advisable  to  generate  the  fumes 
in  as  many  different  places  as  practicable,  as  this  favors  rapid  diffu- 
sion. 

Sulphur. — Sulphur  is  one  of  the  most  valuable  insecticides  we  pos- 
sess. It  may  be  used  either  as  a  gas — SO, — or  in  its  powdered  form — 
flowers  of  sulphur. 

Sulphur  dioxid  is  destructive  to  all  forms  of  life.  It  will  kill 
mosquitoes,  flies,  fleas,  roaches,  bedbugs,  and  all  kinds  of  vermin,*  in- 
cluding rats  and  mice.  While  sulphur  dioxid  is  one  of  the  most  de- 
pendable insecticides  it  is  a  rather  feeble  germicide.  It  diffuses  poorly 
and  has  feeble  penetrating  power,  requires  expensive  or  cumbersome 
apparatus,  and  much  labor.  It  is  also  rather  slow  and  has  some  risk 
of  fire.  It  is  further  limited  in  practice  on  account  of  its  destructive 
and  corrosive  action  due  to  sulphurous  acid  and  sulphuric  acid  pro- 
duced in  the  presence  of  moisture.  Fortunately  the  dry  gas  is  quite 
as  poisonous  to  mosquitoes,  flies,  rats,  mice,  etc.,  as  the  moist  gas. 
Dry  sulphur  dioxid,  however,  has  absolutely  no  germicidal  value. 

Sulphur  dioxid  tarnishes  metals,  rots  fabrics,  and  bleaches  pigments, 
especially  when  moist.  Fumigation  with  SO,  may,  however,  be  done 
with  little  damage  to  property  on  dry  days.  Metal  work,  fabrics,  and 
pigments  that  cannot  be  removed  from  the  room  may  be  protected  from 
the  sulphur  fumes  by  coating  with  petroleum  jelly  or  covering  with 
paper. 

Sulphur  dioxid  may  be  produced  either  by  burning  sulphur  or  by 
liberating  liquefied  sulphur  dioxid.  The  methods  of  generating  the 
gas  will  be  found  on  page  1396.  Two  pounds  of  sulphur  burned  for  each 
thousand  cubic  feet  of  air  space  and  an  exposure  of  two  hours  are  sufficient 
to  kill  mosquitoes,  flies,  and  other  insects  in  a  small  tight  space;  three 
to  four  pounds  and  an  exposure  of  6  hours  are  ample  for  rats  and  mice. 
If  the  space  is  large  or  leaky,  the  amount  of  gas  should  be  increased  and 
the  time  of  exposure  prolonged.     See  pages  384  and  1396. 

Flowers  of  Sulphur. — Sulphur  in  its  dry,  powdered  state  is  use- 
ful against  a  number  of  parasites.     In  this  form,  however,  it  has  little 

*  Sulphur'  cannot  be  depended  upon  to  kill  the  eggs  of  lice,  fleas,  mites,  etc. 


270  INSECT-BORNE  DISEASES 

use  as  an  insecticide  in  preventive  medicine,  not  being  efficacious  against 
bedbugs,  ants,  roaches,  or  fleas. 

It  may  be  applied  in  several  ways,  the  simplest  of  which  is  to 
sprinkle  the  dry  sulphur  about  the  places  where  insects  are  found. 
Flowers  of  sulphur  may  also  be  combined  advantageously  with  other 
insecticides,  such  as  kerosene  emulsion,  resin  wash,  or  soap  wash.  It 
should  first  be  mixed  into  a  paste  and  then  added  to  the  spray  tank 
in  the  proportion  of  about  1  or  2  pounds  to  50  gallons.  It  is  very 
efficacious  for  the  destruction  of  the  mites  and  rust  of  plants  and  fruits. 

Sulphur  in  the  form  of  an  ointment  is  particularly  obnoxious  to 
ticks  and  other  ectoparasites.  The  itch-mite  (Sarcoptes  scabiei)  is 
very  susceptible  to  the  flowers  of  sulphur,  which  is,  therefore,  one  of 
the  ingredients  of  almost  all  ointments  used  in  this  skin  affection — 
scabies. 

Sulphur  dips  are  used  to  destroy  the  mites  on  domestic  animals. 
The  formula  now  recommended  for  the  treatment  of  scabies  of  cattle  is 
as  follows:  Flowers  of  sulphur,  24  pounds;  unslaked  lime,  12  pounds; 
water,  100  gallons.  It  is  common  experience  that,  while  sulphur  dips 
may  be  depended  upon  to  destroy  the  mites,  they  do  not  destroy  the 
eggs,  hence  the  treatment  should  be  repeated  in  about  10  days,  which 
permits  time  for  the  eggs  to  hatch  and  develop  into  adults.  The  lime 
and  sulphur  dips  are  widely  used  for  both  cattle  and  sheep  affected  with 
scabies.  The  advantages  of  this  class  of  dips  over  arsenical  dips  are  that 
they  are  effective,  but  not  poisonous  for  cattle  or  man.  Lime  and 
sulphur  dips  are  not  effective  for  the  Texas  fever  tick,  and  arsenic 
should  therefore  be  used. 

Formaldehyd. — Formaldehyd,  while  holding  the  front  rank  as  a 
germicide,  is  a  feeble  insecticide.  The  gas  seems  to  have  no  effect 
whatever  upon  roaches,  bedbugs,  and  insects  of  this  class  even  after 
prolonged  exposure  to  very  high  percentages.  As  a  differential  poison 
formaldehyd  gas  is  a  very  remarkable  substance.  It  destroys  bacteria 
almost  instantly,  but,  while  it  is  irritating  to  the  higher  forms  of  ani- 
mal life,  it  is  not  very  toxic.  I  have  repeatedly  found  that  roaches  and 
other  insects  with  strong  chitinous  protection  seem  unharmed  after 
12  hours'  exposure  to  very  strong  percentages  of  the  gas  in  air-tight  dis- 
infecting chambers.  Mosquitoes  may  live  in  a  weak  atmosphere  of  the 
gas  over  night.  It  will  kill  them,  however,  if  the  gas  is  brought  in  direct 
contact  with  them  in  the  full  strength  and  time  prescribed  for  bac- 
terial disinfection. 

When  a  weak  insecticidal  gas  is  used,  it  is  much  more  difficult  to 
obtain  direct  contact  between  the  gas  and  the  insects  than  between 
the  gas  and  germs,  because  the  sense  of  self-preservation  aids  the  for- 
mer in  escaping  from  the  effects  of  the  irritating  substance.  Mos- 
quitoes and  other  insects   hide  in  the  folds   of  towels,  bed   clothing, 


INSECTICIDES  271 

hangings,  fabrics,  and  out-ol'-tho-way  places  where  ilic  forinaldehyd  gas 
does  not  permeate  in  sunicicnt  slren^-lh  lo  kill  tlieni.  The  gas  tends  to 
polymerize  and  deposit  as  j)arat'()rni  on  tlie  surface  of  fabrics  wliich 
prevents  its  penetration,  and  lar^e  quantities  are  lost  by  being  al)sorbed 
by  the  organic  matter  of  mooU'u  fabrics.  ^Mosquitoes  have  a  lively  in- 
stinct in  finding  cracks  or  chinks  where  fresh  air  may  enter  a  room 
or  other  places  where  the  gas  is  so  diluted  that  they  escape  destruc- 
tion. Therefore,  formaldehyd  gas,  as  well  as  otlicr  culicides,  cannot 
be  trusted  to  kill  all  the  mosquitoes  in  a  room  wliich  cannot  be  tightly 
sealed.  On  account  of  its  feeble  action,  formaldehyd  should  not  be 
used  as  an  insecticide. 

For  the  best  methods  of  evolving  formaldehyd  gas,  the  quantities 
to  be  used,  and  other  details  of  the  process,  see  page  1391. 

Formaldehyd  gas  in  watery  solution,  known  as  formalin,  is  use- 
ful for  the  destruction  of  flies.  Small  quantities  of  dilute  formalin 
(1,25- to  2.5  per  cent.)  placed  in  saucers  about  the  room  attract  flies. 
They  drink  the  fluid,  which  soon  kills  them. 

Pyrethrum. — Pyrethrum  is  a  popular  and  much  used  insecticide 
because  it  is  comparatively  cheap  and  non-poisonous  to  man  and  the 
higher  animals.  It  is  also  non-corrosive,  but  unfortunately  it  has  but  a 
feeble  action  against  roaches,  ants,  bedbugs,  flies,  fleas,  mosquitoes,  etc. 
It  has  no  germicidal  action. 

Pyrethrum,  also  sold  under  the  names  of  Buhach  or  Persian  insect 
powder,  or  simply  "insect  powder,"  is  the  flowers  of  the  Chrysanthemum 
roseiim  and  the  Chrysanthemum  carneum,  both  hardy  perennials  and 
resembling  camomile  in  appearance.  According  to  Kalbrunner,  4  grains 
of  the  pure  powder  sprinkled  on  a  fly  in  a  vial  should  stupefy  it  in 
1  minute,  and  kill  it  in  2  or  3  minutes.  It  acts  on  insects  exter- 
nally through  their  breathing  pores.  It  may  be  used  either  as  a  dry 
powder  or  by  its  burning  fumes.  As  a  dry  powder  it  may  be  used 
pure  or  mixed  with  flour,  in  which  form  it  should  be  puffed  about  the 
room,  especially  into  cracks. 

When  pyrethrum  powder  is  ignited  it  smolders,  giving  off  fumes 
which  stun,  but  do  not  always  kill,  mosquitoes.^  It  is  not,  therefore, 
a  dependable  insecticide.  This  uncertainty  of  pyrethrum  restricts  its 
field  of  usefulness. 

Pyrethrum  fumes  do  not  corrode  metals  nor  act  injuriously  upon 
fabrics  and  pigments.  However,  a  slight  brown  deposit  is  occasionally 
left  on  exposed  surfaces  which  may  stain  linen  a  yellowish  color.  This 
deposit  or  stain  is  readily  washed  out,  or  soon  fades. 

P3^rethrum  powder  has  been  useful  in  those  cases  where  sulphur  is 
prohibited  on  account  of  the  danger  of  damage  to  paintings,  fabrics, 

*  Tobacco  smoke  and  other  substances  which  produce  dense  fumes,  particu- 
larly those  containing  pyroligneous  products,  will  kill  mosquitoes. 


272  INSECT-BOENE  DISEASES 

tapestries,  metal  work,  musical  instruments,  upholstered  furniture,  and 
the  like.  It  is  used  in  the  proportion  of  2  pounds  per  1,000  cubic  feet 
of  air  space,  the  exposure  being  for  not  less  than  4  hours.  As  its  insecti- 
cidal  effect  is  uncertain,  it  is  necessary  carefully  to  sweep  up  and  burn  all 
the  mosquitoes  that  have  been  stunned  and  are  apparently  dead  after 
the  fumigation.  Most  of  these  mosquitoes  will  be  found  on  the  window 
sill  or  on  the  floor  close  to  the  window,  where  they  are  attracted  by 
the  light  in  their  efforts  to  find  an  exit  to  escape  the  fumes.  Ad- 
vantage should  be  taken  of  this  tendency  of  the  mosquito  to  seek  the 
light  by  darkening  all  but  one  window. 

Sheets  of  paper  containing  some  sticky  preparation  may  be  placed 
upon  the  floor  and  upon  the  window  sill  in  order  to  catch  the 
mosquitoes.  A  satisfactory  adhesive  preparation  may  be  made  by 
dissolving,  by  the  aid  of  heat,  65  parts  of  colophony  resin  in  35 
parts  of  castor  oil.  This  simplifies  the  collection  and  disposal  of  the 
insects. 

Pyrethrum  powder  should  be  distributed  in  pots  or  pans  and  set  on 
fire  with  a  little  alcohol,  which  should  first  be  sprinkled  over  it.  The 
quantity  apportioned  to  any  one  pot  or  pan  should  not  exceed  1^^ 
inches  in  depth,  if  the  exposure  is  to  be  for  4  hours.  The  pots  and 
pans  should  be  set  on  bricks  to  prevent  scorching  the  floor. 

Much  of  the  pyrethrum  upon  the  market  is  impure,  which  further 
weakens  what  is  a  feeble  insecticide  at  best.^ 

Phenol-camphor  (Mini's  Culicide). — Camphophenique  or  phenol- 
camphor  is  prepared  by  rubbing  up  equal  weights  of  phenol  crystals  and 
camphor.  It  may  be  more  conveniently  prepared  by  first  liquefying. the 
phenol  by- gentle  heat  and  then  pouring  it  over  the  camphor.  The  cam- 
phor and  phenol  combine  to  form  a  new  chemical  compound,  which  re- 
mains fluid  at  ordinary  temperatures.  When  phenol-camphor  is  mod- 
erately heated  it  gives  off  dense  fumes,  which  rise  rapidly  and  diffuse 
slowly,  and  after  30  to  60  minutes,  depending  upon  the  amount  em- 
ployed and  the  temperature  of  the  air,  the  fumes  condense  and  are 
deposited  as  a  slight  moisture  on  all  exposed  surfaces.  As  a  culicide 
phenol-camphor  is  about  equal  to  pyrethrum;  the  fumes  stun  the  mos- 
quitoes, but  do  not  always  kill  them.  The  fumes  are  somewhat  irritating 
to  the  mucous  membranes,  especially  the  eyes;  they  may  cause  dizziness, 
headache,  cloudy  urine,  and  other  mild  symptoms  of  phenol  poisoning 
in  susceptible  individuals  much  exposed  to  their  inhalation.  The 
fumes  of  phenol-camphor  do  not  tarnish  metals,  rot  fabrics,  or  bleach 
pigments.  They,  however,  have  the  disagreeable  property  of  softening 
the  varnish  of  surfaces  on  which  they  condense.  On  account  of  its 
slight  power  of  diff'usion,  relatively  high  cost,  and  uncertainty  of  action, 
it  cannot  take  the- place  of  sulphur  except  in  the  parlor,  pilot  house, 

"Insect  Poioder,  Bull.  824,  U.  S.  Dept.  of  Agriculture,  1920. 


INSECTICIDES  273 

and  other  compartments  where  sulphur  is  prohibited  on  account  of 
the  damage  it  produces. 

Phenol-camphor  is  used  in  the  proportion  of  4  ounces  to  every  thou- 
sand cubic  feet  of  air  s|iace,  and  with  an  exposure  of  2  hours.  In  this 
proportion  and  time  the  film  of  condensation  is  slight  and  is  rapidly  dis- 
sipated after  the  doors  and  windows  are  opened.  The  preparation  of 
the  room  is  the  same  as  that  described  above.  The  phenol-camphor  ap- 
portioned to  the  room  to  be  fumigated  should  be  distributed  in  agate- 
ware basins,  not  more  than  S  to  ID  ounces  to  any  one  basin.  Each 
basin  is  set  over  an  alcohol  lamp  at  such  an  elevation  and  in  such  a 
manner  as  will  permit  a  rapid  evolution  of  the  fumes.  Care  must  be 
taken  not  to  heat  the  basin  so  quickly  as  to  cause  the  liquid  to  become 
overheated  and  take  fire.  This  point  must  first  be  determined  experi- 
mentally for  each  type  of  lamp  used.  One  of  the  small  brass  alcohol 
vapor  lamps  to  be  found  on  the  market  serves  excellently.  As  a  safe- 
guard against  accidents  the  lamp  should  stand  in  a  pan  containing  about 
one-half  inch  of  water.  The  basin  containing  the  phenol-camphor  may 
be  set  upon  a  section  of  galvanized  iron  stove-pipe,  at  one  end  of  which 
sectors  are  cut  out  so  as  to  form  legs  of  a  length  equal  to  the  height  of 
the  lamp;  just  below  the  upper  margin  of  the  pipe  a  series  of  holes 
are  punched  so  as  to  provide  for  draft.  The  stove-pipe  should  be  of 
such  a  length  as  to  support  the  basin  containing  the  phenol-camphor 
about  10  inches  above  the  flame.  This  ingenious  and  simple  device, 
suggested  by  Berry  and  Francis,  acts  as  a  chimney,  protects  the  flame, 
is  relatively  cheap,  and  has  proved  satisfactory. 

Hydrocyanic  Acid  G-as. — Hydrocyanic  acid  gas  is  extremely  poison- 
ous to  all  forms  of  life.  It  kills  roaches,  bedbugs,  mosquitoes,  fleas, 
flies,  rats,  mice,  and  other  vermin  with  great  certainty  and  very  quickly. 
HCX  also  kills  insect  eggs,  which  sulphur  dioxid  and  other  gases  fail  to 
do.  Hydrocyanic  acid  gas  is  not  a  germicide.  It  is  not  very  poisonous  to 
the  higher  forms  of  plant  life.  Hydrocyanic  acid  gas  is  much  used  in 
greenhouses  for  the  destruction  of  insect  pests  and  for  scale  and  other 
parasites  of  fruit  trees.  The  gas  has  a  distinct  place  in  the  fumigation 
of  granaries,  stables,  ships,  barns,  outhouses,  railroad  cars,  and  other 
uninhabited  structures  infested  with  vermin.  It  is  also  extensively  used 
in  flouring  mills  against  weevils,  in  railroad  cajs  against  bedbugs,  and 
in  tobacco  warehouses  against  insects  in  general.  It  shoiild  be  used  in 
the  household  only  with  the  greatest  precaution,  as  the  least  careless- 
ness with  it  would  probably  mean  the  loss  of  human  life.  It  has  the 
marked  advantage  that  it  does  not  harm  metals,  fabrics,  or  pigments, 
and  may  be  used  in  the  most  expensive  drawing  rooms. 

Hydrocyanic  acid  gas  is  lighter  than  air  and  has  an  agreeable 
aromatic  odor  quite  familiar  in  the  flavoring  essence  of  bitter  almonds. 
The  best  method  of  generating  it  for  the  purpose  of  fumigation  is  by 


274  INSECT-BOENE  DISEASES 

the  action  of  dilute  sulphuric  acid  upon  potassium  cyanid,  in  the  fol- 
lowing proportions : 

Sodium  cyanid  1       ounce  Potassium  cyanid      1.0  ounce 

Sulphuric   acid  li^  ounces         Sulphuric  acid  1.0  ounce 

Water  2       ounces         Water  2.5  ounces 

The  first  step  is  to  dilute  the  acid,  which  is  done  by  adding  the 
acid  to  water  in  a  vitrified  clay  jar  or  receptacle  capable  of  withstand- 
ing the  heat.  The  whole  amount  of  cyanid  should  be  put  into  the  acid 
at  once.  As  the  evolution  of  the  gas  is  rapid,  the  operator  should  be 
ready  to  leave  the  spot  without  delay.  As  pointed  out  by  Fulton,  it 
is  convenient  to  tie  the  cyanid  up  in  a  bag  made  of  cheese  cloth  or  tissue 
paper,  which  is  lowered  into  the  acid  by  a  cord  passing  outside  of  the 
room.  The  amount  of  gas  used  for  fumigation,  expressed  in  terms  of 
cyanid,  is  from  I/2  ounce  to  10  ounces  per  100  cubic  feet  of  space. 
From  30  minutes  to  2  hours  will  kill  lice,  bedbugs  and  roaches,  but  in 
practice  an  exposure  of  2  to  6  hours  is  advisable  (page  514).  Hydro- 
cyanic acid  gas  is  quite  as  effective  as  sulphur  dioxid,  is  not  destructive, 
is  reasonably  cheap,  and  is  certain  in  its  action,  but  its  poisonous 
nature  is  such  a  serious  drawback  that  it  has  a  limited  place  as  an 
insecticide  in  public  health  work.  It  is  finding  favor  in  maritime  quar- 
antine practice,  where  it  is  largely  replacing  SO2.  See  pages  515  and 
1402. 

Bisulphid  of  Carbon. — Bisulphid  of  carbon  (CSg)  is  a  very  efficient 
insecticide,  but  a  dangerous  one,  on  account  of  its  inflammable  and  ex- 
plosive nature.  It  quickly  kills  mosquitoes,  roaches,  flies,  ants,  and 
insects  of  all  kinds,  as  well  as  rats,  mice,  and  squirrels.  When  pure  it 
is  a  mobile,  colorless  liquid  with  an  agreeable  ethereal  odor,  but  often 
it  has  a  more  or  less  fetid  odor  from  the  presence  of  other  volatile 
compounds.  The  liquid  must  be  kept  in  well-stoppered  bottles  in  a  cool 
place,  and  away  from  the  light  and  fire.  It  evaporates  rapidly  at  ordi- 
nary temperatures,  so  that  in  using  this  substance  in  a  confined  space  it 
is  sufficient  to  pour  it  into  open  pans.  Carbon  bisulphid  is  very  in- 
flammable— more  so  than  ether — and  bums  with  a  pale  blue  flame 
yielding  sulphur  dioxid  and  carbon  dioxid  or  monoxid.  In  its  use 
every  precaution  must ,  be  taken  to  see  that  there  is  no  fire,  lighted 
cigar,  etc.,  in  or  about  the  field  of  operation.  On  account  of  its  poison- 
ous nature,  if  used  in  a  house  or  other  inhabited  structure,  the  rooms 
must  be  thoroughly  aired  after  its  use. 

According  to  Hinds,  shallow  tin  pans  or  plates  make  good  evaporat- 
ing dishes  for  carbon  bisulphid.  The  larger  the  evaporating  area  the 
better.  About  one  square  foot  of  evaporating  surface  is  used  to  every 
25  square  feet  of  floor  area,  and  one-half  to  one  pound  of  the  liquid 
carbon   bisulphid  is  used  for  each  square  foot  of  evaporating  surface. 


INSECTICIDES  275 

Those  fig-urcs,  of  fourso,  are  only  sii<f^a'stive  and  ai)proximate.  The 
pans  should  be  placed  as  high  in  the  room  as  possible,  since  the  vapor 
is  so  heavy  that  it  settles  ra])idly.  Care  should  l)e  taken  when  placing 
the  pans  to  see  that  they  are  nearly  level  so  as  to  hold  the  liquid,  though 
ordinarily  no  particular  harm  will  be  done  if  some  of  it  is  spilled.  It 
should  not  be  found  necessary  to  lose  time  in  adjusting  such  things  after 
the  operation  has  begun. 

Carbon  bisulphid  was  extensively  used  in  California  in  the  plague 
campaign.  A  piece  of  waste  the  size  of  an  orange  is  saturated  with 
the  liquid  and  the  wet  ball  placed  in  the  mouth  of  the  squirrel  hole. 
Wet  clay  is  then  stamped  into  the  warren  so  that  the  gas  which  is 
generating  may  have  no  opportunity  to  escape.  All  of  the  holes  of 
the  burrows  are  treated  in  this  way.  In  some  instances  the  ball  is 
placed  deeply  in  the  hole  and  then  ignited.  This  is  more  or  less  un- 
certain, as  an  explosion  occurs,  and,  while  the  gas  is  thus  disseminated, 
its  action  only  covers  a  limited  period  of  time,  and  is,  therefore,  not  as 
certain  as  simply  allowing  the  carbon  bisulphid  to  evaporate.  It  not  only 
kills  the  squirrels,  but  also  the  fleas  on  them. 

Carbon  tetraclilorid  (CCI4)  may  be  used  in  place  of  carbon  bisulphid. 
It  is  neither  inflammable  nor  explosive,  but  somewhat  more  poisonous 
than  chloroform.  The  sale  of  carbon  tetrachlorid  is  forbidden  in  Paris 
on  account  of  deaths  from  its  use  as  a  shampoo.  It  is  sold  in  this 
country  as  a  cleaning  agent. 

Petroleum. — Petroleum,  kerosene,  or  coal  oil  is  a  very  valuable  in- 
secticide. Petroleum  and  its  products,  such  as  gasoline  or  naphthalene, 
are  the  most  dependable  insecticides  we  have,  and  are  used  more  and 
more  in  one  form  or  another. 

As  a  remedy  for  mosquitoes  coal  oil  is  applied  in  the  proportion  of 
about  1  ounce  to  15  square  feet  of  water  surface.  It  should  form  a 
uniform  film  over  the  surface,  and  will  then  destroy  the  larvae  and 
pupae  of  the  mosquito  and  the  adult  females  coming  to  the  water  to  lay 
their  eggs.  The  oil  must  be  renewed  every  week  or  two,  depending 
upon  the  temperature  and  other  conditions.  A  light  grade  of  fuel  oil 
is  best  for  this  purpose.     See  page  282. 

Petroleum  is  also  useful  against  roaches,  bedbugs,  fleas,  lice,  and 
other  insect  vermin  when  used  by  direct  application  or  by  spraying, 
either  in  the  form  of  the  pure  oil  or  as  an  emulsion.  Petroleum  is 
very  efficient  against  fleas.  Frequent  application  to  the  floor  or  other 
places  will  keep  away  ants,  and  by  direct  application  to  the  breeding, 
feeding,  and  traveling  places,  it  is  a  useful  remedy  against  house- 
hold vermin  in  general.  Coal  oil  is  the  cheapest  and  most  effective 
remedy  for  lice,  by  direct  application  to  the  head  or  other  parts 
affected. 

Emulsion  of  crude  petroleum  for  application  to  the  skin  of  animals 


276  IISrSECT-BOENE  DISEASES 

or  to  trees,  or  other  plants,  or  for  general  insecticidal  purposes  is  made 
from  the  formula  of  T.  M.  Price : 

Crude   petroleum 2  gallons 

Water  %  gallon 

Hard  soap  %  pound 

Dissolve  the  soap  in  the  water  with  the  aid  of  heat.  To  this  add 
the  crude  petroleum;  mix  with  a  spray  pump  or  shake  vigorously  and 
dilute  with  the  desired  amount  of  water.  The  emulsion  of  crude  petro- 
leum made  according  to  this  modified  formula  remains  fluid,  and  can 
be  easily  poured.  It  will  stand  indefinitely  without  any  tendency 
toward  separation  of  the  oil  and  water,  and  can  be  diluted  in  any  pro- 
portion with  cold  soft  water. 

Gasoline^  naphtha,  and  benzine,  also  naphthalene  are  among  the  best 
pulicides,  and  as  such  are  extensively  used  to  kill  lice  in  typhus  fever 
campaigns.     See  page  3G8. 

Arsenic. — The  arsenical  compounds,  according  to  Marlatt,''  have  sup- 
planted practically  all  other  substances  as  a  food  poison  for  biting  in- 
sects. The  two  arsenicals  in  most  common  use  obtainable  everywhere 
are  arsenate  of  lead  and  Paris  green.  Scheele's  green,  or  arsenite  of 
copper,  is  less  known  and  less  easily  obtainable,  but  in  some  respects 
is  better  than  Paris  green.  The  use  of  powdered  white  arsenic  is  not 
recommended  on  account  of  its  corrosive  action,  as  well  as  the  fact  that 
it  is  apt  to  be  mistaken  for  harmless  substances. 

The  arsenical  poisons  may  be  applied  in  one  of  three  ways:  (1)  in 
suspension,  as  poisoned  waters,  mainly  in  the  form  of  sprays;  (2)  as  a 
dry  powder  blown  or  dusted  about  the  infested  areas;  or  (3)  as  poi- 
soned bait. 

It  must  be  remembered  that  the  arsenicals  are  very  poisonous;  they 
should  be  so  labeled,  and  care  taken  to  prevent  accidents. 

Paris  green  is  a  definite  chemical  compound  of  arsenic,  copper,  and 
acetic  acid  (acetoarsenite  of  copper),  and  should  have  a  nearly  uniform 
composition.  It  is  rather  a  coarse  powder,  or,  more  properly  speaking, 
crystal,  and  settles  rapidly  in  water,  which  is  its  greatest  fault  so  far  as 
the  making  of  suspensions  of  this  substance  is  concerned. 

Scheele's  green  is  similar  to  Paris  green  in  color  and  differs  from 
it  only  in  lacking  acetic  acid;  in  other  words,  it  is  simply  arsenite  of 
copper  (CuHAsOs).  It  is  a  finer  powder  than  Paris  green,  and,  there- 
fore, is  more  easily  kept  in  suspension. 

Arsenious  oxid  (AsoOg),  or  white  arsenic,  commonly  known  as  ar- 
senic, is  used  in  dips  to  destroy  ticks.     See  page  355. 

Arsenate  of  lead  is  prepared  by  combining,  approximately,  3  parts 
of  the  arsenate  of  soda  with  7  parts  of  the  acetate  of  lead  (white  sugar 

''Farmers'  Bulletin  No.  19,  U.  S.  Dept.  of  Agriculture. 


INSECTICIDES  277 

of  lead)  in  water.  These  substances,  when  pulverized,  unite  readily 
and  form  a  wiiite  precipitate,  which  is  more  easily  kept  suspended  in 
water  tlian  any  of  the  other  arsenical  poisons.  Its  use  is  advised  where 
excessive  strengths  are  not  desirable,  and  upon  delicate  plants,  where 
otherwise  scalding  is  likely  to  result. 

An  average  of  one  pound  of  eitlier  Paris  green  or  Scheele's  green,  or 
London  purple  to  150  gallons  of  water  is  a  good  strength  for  general 
purposes  in  using  the  wet  method.  The  powder  should  first  be  made 
up  into  a  thin  paste  in  a  small  quantity  of  water,  and,  if  the  suspen- 
sion is  to  be  used  upon  plants,  vegetables,  or  about  foliage,  an  equal 
amount  of  quicklime  should  be  added  to  take  up  the  free  arsenic  and 
remove  or  lessen  the  danger  of  scalding. 

For  the  distribution  of  dry  poison  the  arsenicals  are  diluted  with 
10  parts  of  flour,  lime,  or  dry  g}^psum. 

The  following  mixtures  are  used  in  the  form  of  sprays,  to  destroy 
insects  and  fungi  upon  plants.^  The  arsenate  of  lead  mixture  has  been 
much  used  in  Massachusetts  with  success  against  the  gipsy  moth  and 
other  destructive  insects  upon  trees  and  plants.  These  mixtures  are 
equally  useful  as  insecticides  wherever  sprays  or  local  applications  are 
practicable. 

ARSENATE  OF  LEAD 

Arsenate  of  soda  (5  per  cent,  strength),  4  ounces. 
Acetate  of  lead,  11  ounces. 
Water,  100  gallons. 

Put  the  arsenate  of  soda  in  2  quarts  of  w^ater  in  a  wooden  pail,  and 
the  acetate  of  lead  in  four  quarts  of  water  in  another  w^ooden  pail. 
When  both  are  dissolved,  mix  with  the  rest  of  the  w'ater.  Warm  water 
in  the  pails  will  hasten  the  process.  For  the  elm-leaf  beetle  use  10 
instead  of  100  gallons  of  water. 

A  number  of  ready-made  arsenates  of  lead  are  now  on  the  market, 
and,  except  when  very  large  amounts  are  needed,  it  will  probably  prove 
cheaper  to  buy  the  prepared  material  than  to  make  it.  With  this 
ready-made  material  use  3  pounds  to  50  gallons  of  water  for  codling 
moths,  and  5  pounds  to  50  gallons  for  the  elm-leaf  beetle  and  on 
potatoes. 

ARSENATE  OF  LIME 

White  arsenic,  2  pounds. 
Sal-soda,  8  pounds. 
Water,  2  gallons. 

'  From  Bulletin  No.  123,  April.  1908,  of  the  Massachusetts  Agricultural 
Experiment  Station  by  Stone  and  Ferald. 


278  INSECT-BORNE  DISEASES 

Boil  till  the  arsenic  all  dissolves — about  45  minutes.  Make  up  the 
water  lost  by  boiling  and  place  in  an  earthen  dish.  For  use  take  one 
pint  of  this  stock,  2  pounds  freshly  slaked  lime,  and  45  gallons  water, 
and  spray. 

KEROSENE  EMULSION 

Hard  soap,  shaved  fine,  %  pound. 
Water,  1  gallon. 
Kerosene,  2  gallons. 

Dissolve  the  soap  in  the  water,  which  should  be  boiling;  remove 
from  the  fire  and  pour  it  into  the  kerosene  while  hot.  Churn  this  with 
a  spray  pump  till  it  changes  to  a  creamy,  then  to  a  soft, .  butter-like 
mass.  Keep  this  as  a  stock,  using  one  part  in  nine  of  water  for  soft- 
bodied  insects,  such  as  plant  lice,  or  stronger  in  certain  cases. 

-     EESIN-LIME  MIXTURE 

Pulverized  resin,  5  pounds. 
Concentrated  lye,  1  pound. 
Fish  or  other  animal  oil,  1  pint. 
Water,  5  gallons. 

Place  the  oil,  resin  and  one  gallon  of  hot  water  in  an  iron  kettle 
and  heat  till  the  resin  softens;  then  add  the  lye  and  stir  thoroughly; 
now  add  4  gallons  of  hot  water  and  boil  till  a  little  will  mix  with  cold 
water  and  give  a  clear,  amber-colored  liquid;  add  water  to  make  up  5 
gallons.    Keep  this  as  a  stock  solution.    For  use  take : 

Stock  solution,  1  gallon. 
Water,  16  gallons. 
Milk  of  lime,  3  gallons. 
Paris  green,  ^  pound. 

BORDEAUX  MIXTURE 

Copper  sulphate  (blue  vitriol),  4  pounds. 
Lime   (unslaked),  4  pounds. 
Water,  25  to  50  gallons. 

Dissolve  the  copper  in  hot  or  cold  water,  using  a  wood  or  earthen 
vessel.  Slake  the  lime  in  a  tub,  adding  the  water  cautiously  and  only 
in  sufficient  amount  to  insure  thorough  slaking.  After  thoroughly 
slaking,  more  water  can  be  added  and  stirred  in  until  it  has  the  con- 
sistency of  thick  cream.  When  both  are  cold,  dilute  each  to  the  re- 
quired strength  and  pour  both  together  in  a  separate  receptacle  and 
thoroughly  mix.  Before  using,  strain  through  a  fine  mesh  sieve  or  a 
gunny  cloth ;  the  mixture  is  then  ready  for  use. 


MOSQUITOES  279 

If  the  amount  of  lime  in  the  Bordeaux  mixture  is  insufficient  there 
is  danger  of  burning  tender  foliage.  In  order  to  obviate  this,  the  mix- 
ture can  be  tested  with  a  knife  blade  or  with  ferrocyanid  of  potassium 
(1  oz.  to  5  or  (i  oz.  of  water).  If  the  amount  of  the  lime  is  insufficient, 
copper  will  be  deposited  on  ihe  knife  blade,  while  a  deep  brownish-red 
color  will  be  imparted  to  the  mixture  when  ferrocyanid  of  potassium 
is  added.  Lime  should  be  added  until  neither  reaction  occurs.  A  slight 
excess  of  lime,  however,  is  desirable,  and  it  is  seldom  one  has  to  apply 
these  tests.  The  Bordeaux  mixture  is  a  good  fungicide,  but  is  less  useful 
as  an  insecticide. 

The  abundant  and  increasing  use  of  the  salts  of  lead,  arsenic  and 
copper  to  spray  fruits,  berries,  and  vegetables  of  all  sorts  has  opened  a 
new  question,  as  these  substances  are  poisonous  for  man.  Ordinarily, 
an  apple  will  carry  about  0.5  mgm.  of  arsenate  of  lead.  However,  as 
much  as  5  mgm.  has  been  found  on  the  surface  of  an  apple  directly 
after  spraying.  One  quarter  of  a  quart  of  strawberries  may  carry  as 
much  as  8  mgm.  of  oxid  of  arsenic.  A  head  of  cabbage  may  carry  a 
relatively  large  amount  especially  on  the  outer  leaves.  The  importance 
of  thoroughly  washing  all  fruits,  vegetables,  and  berries  is  again  em- 
phasized. 

MOSQUITOES 

Mosquitoes  differ  markedly  in  their  habits.  Some  species  may  be 
classed  as  domestic  animals  because  they  are  commonly  or  almost  ex- 
clusively found  in  or  close"  to  human  habitations.  This  is  notably  the 
case  with  Stegomyia  calopus,  the  yellow  fever  and  dengue  mosquito; 
Culex  quinque  fascial  us  fatigans,  the  intermediary  for  Filaria  hancrofti 
(filariasis).  The  sylvan  or  wild  mosquitoes,  of  which  the  Culex  sollici- 
tans,  the  common  salt  marsh  mosquito  of  our  Atlantic  coast,  is  a  well- 
known  example,  are  seldom  met  with  in  human  habitations.  A  third  or 
semi-domestic  class  may  be  encountered  either  in  or  near  houses,  or  in 
fields  or  swamps.  This  class  includes  the  malarial  mosquitoes  belonging 
to  the  genus  Anopheles. 

The  adult  mosquito  may  be  carried  to  considerable  distances  by 
winds;  but  of  its  own  volition  it  does  not  ordinarily  travel  outside  of 
a  radius  of  half  a  mile  from  its  breeding  place.  The  longest  flights 
noted  by  le  Prince  are  about  a  mile.  Most  species  do  not  fly  nearly  so 
far.  This  means  that  the  destruction  of  all  breeding  places  within  a 
camparatively  small  radius  of  a  habitation  will  rid  it  of  all  but  those 
mosquitoes  which  are  blown  in  by  the  winds  from  more  or  less  distant 
marshes,  or  which  are  brought  in  the  vessels  and  vehicles  of  trade 
and  travel. 


280  INSECT-BOENE  DISEASES 

Life  History  and  Habits. — Mosquitoes  pass  through  four  stages:  (1) 
the  egg  or  embryo,  (2)  the  larva.  (3)  the  pupa,  and  (4)  the  imago 
or  adult  winged  insect.  The  egg,  larval,  and  pupal  stages  are  aquatic. 
Mosquitoes  never  breed  in  damp  grass,  weeds,  or  bushes,  as  is  popularly 
supposed,  but  the  winged  insects  frequently  rest  and  hide  in  vegeta- 
tion. The  different  species  of  mosquitoes  not  only  differ  markedly  in 
their  habits,  but  differ  considerably  in  the  character  of  their  breeding 
places.  The  domestic  species,  such  as  the  yellow  fever  mosquito  and 
Culex  pipiens,  may  be  found  breeding  in  any  collection  of  water  in  or 
about  houses.  Thus,  they  have  been  found  in  discarded  tin  cans,  bottles, 
and  broken  crockery  on  the  garbage  heap ;  in  buckets,  tubs,  barrels, 
cisterns,  and  wells;  in  baptismal  fonts;  in  flower  pots  and  sagging  roof 
gutters ;  in  street  and  roadside  puddles,  gutters,  and  ditches ;  in  cesspools 
and  sewers. 

The  semi-domestic  mosquitoes,  to  which  the  malarial-bearing  insects 
belong,  may  occasionally  be  found  breeding  in  tin  cans,  barrels,  hoof 
prints,  post  holes,  and  hollows  in  trees  or  tree  stumps,  but  they  usually 
prefer  grass-bordered  pools,  slowly  flowing  ditches,  the  margins  of  lakes 
and  streams,  even  such  as  are  stocked  with  fish,  jorovided  the  margins 
are  shallow  or  are  more  or  less  choked  with  reeds  and  water  plants  so 
that  the  fish  cannot  reach  them.  Some  species  of  Anopheles  breed 
freely  in  the  grassy  edges  and  eddies  of  fairly  free  running  clear  brooks. 
The  sylvan  or  wild  mosquitoes  select  breeding  places  of  much  the  same 
character  as  do  the  semi-domestic  species,  with  which  they  are  not  in- 
frequently found  associated,  except  that  such  breeding  places  are  more 
or  less  remote  from  human  habitations,  in  woods,  swamps,  and  fresh 
or  salt   (brackish)   coastal  marshes. 

Male  mosquitoes  are  vegetarians.  The  females  of  many  species 
have  developed  a  taste  for  blood,  and,  indeed,  blood  has  become  indis- 
pensable to  nearly  all  for  the  full  development  of  their  eggs.  This 
is  the  case  with  Siegomyia  calopus.  Eemembering  how  all-important 
the  generative  instinct  is,  we  can  now  well  understand  why  the  yellow 
fever  mosquito,  for  example,  will,  when  disturbed,  return  again  and 
again  in  an  endeavor  to  obtain  her  fill  of  this  life-giving  fluid. 

The  mosquito  usually  lays  her  eggs  upon  the  surface  of  the  water, 
and  these,  depending  upon  the  species,  either  float  separately  on  their 
sides  (Stegomyia  and  Anopheles),  or  adhere  together  in  irregular,  raft- 
like masses  (Culex).  In  a  day  or  two,  under  ordinary  conditions,  the 
eggs  hatch  out  into  larvae  or  "wiggle-tails."  Although  the  larva  is 
an  aquatic  animal,  it  is  a  true  air-breather.  The  larva  of  Anopheles 
ordinarily  rests  and  feeds  at  the  surface,  where  it  lies  in  an  almost 
horizontal  position,  its  tail  and  dorsal  bristles  touching  the  surface 
film,  while  it  breathes  through  a  breathing  siphon,  which  is  very  short 
and  insignificant  in  appearance.. 


MOSQUITOES  281 

The  larvae  of  the  other  species  move  about  more  or  less,  actively 
searching  for  food,  but  at  intervals  of  a  minute  or  two  they  may  be 
seen  to  come  to  the  surface  for  air,  where  tiiey  han<?,  head  down,  at- 
tached by  their  more  or  less  prominent  conical  breathing  tubes  to  the 
surface  film.  Tiie  mosquito  remains  in  the  larval  stage  about  a  week — 
the  length  of  time  varying  with  the  species,  and  for  any  species  with 
the  temperature;  and  is  then  transformed  into  a  curiously  shaped 
creature  known  as  the  pupa. 

The  ])upa  has  no  mouth  and  does  not  feed.  It  remains  quietly  at 
the  surface  except  wbcn  disturl)cd.  It  breathes  through  a  pair  of  trum- 
pet-shaped tubes,  which  project  from  the  dorsum  of  the  throat.  The 
pupal  stage  usually  lasts  two  or  three  days,  and  is  terminated  by  the 
emergence  of  the  adult  winged  insect  (imago)  from  its  pupal  case 
through  a  rent  in  the  region  of  the  breathing  tubes. 

The  time  from  the  laying  of  the  egg  to  the  winged  insect  may,  there- 
fore, be  as  short  as  nine  days.  The  time  depends  upon  the  tempera- 
ture and  the  abundance  of  the  food  supply.  Warmth  favors  and  cold 
retards;  therefore,  mosquitoes  are  most  abundant  during  the  summer, 
late  spring,  and  early  fall  months  in  our  climate.  In  the  tropics  the 
wild  species  become  more  abundant  during  the  wet  season. 

The  way  in  which  mosquitoes  manage  to  pass  through  the  rigors  of 
the  winter  probably  varies  with  the  different  species.  Some,  like  the 
malarial  Anopheles,  hide  in  sheltered  cellars  or  dark  nooks,  or  hibernate 
in  other  out-of-the-way  places.  Other  species  survive  through  the  power 
of  the  larva  or  egg  to  resist  cold,  for  the  larvae  or  eggs  of  some  species 
will  hatch  even  after  they  have  been  frozen. 

THE  DESTRUCTION  OF  MOSQUITOES  "> 

'  The  measures  aimed  at  the  destruction  of  the  mosquito  naturally 
fall  into  two  classes:  (a)  those  directed  against  the  Qgg,  larva  and 
pupa — the  aquatic  stages — and  (b)  those  directed  against  the  winged 
insect. 

For  the  extermination  of  mosquitoes  the  most  effective  measures 
are  those  which  destroy  their  breeding  places,  and  thus  prevent  their 
multiplication.  For  the  best  results,  both  individual  and  communal 
effort  are  necessary,  but  the  importance  of  individual  effort  alone  cannot 
be  too  much  emphasized.  The  individual,  by  attacking  the  problem 
on  his  own  premises,  grounds,- or  estate,  can  not  only  do  much  to  rid 
his  own  immediate  neighborhood  of  mosquitoes,  and  thereby  increase 
his  own  comfort  and  guard  against  disease,  but  the  example  thus  set 
will  perhaps  stimulate  his  less  enterprising  neighbors. 

"Le  Prince  and  Orenstein:  Mosquito  Control  in  Panama.  J.  P.  Putnam's 
Sons,  New  York,  1916. 


282  INSECT-BORNE  DISEASES 

To  insure  success  it  is  important  to  know  the  habits  and  breeding 
places  of  the  particular  species  that  it  is  desired  to  suppress. 

Natural  Breeding-  Places. — Natural  collections  of  water  which  may 
serve  as  breeding  places  are  best  dealt  with  by  filling  in  or  by  draining. 
-Ill  this  way  they  are  disposed  of  once  for  all.  For  filling,  inorganic 
refuse,  such  as  cinders  and  ashes,  may  be  employed,  or  sufficient  earth 
may  be  dug  from  a  nearby  knoll  or  hill,  care  being  observed  that  in  so 
doing  a  depression  capable  of  holding  water  is  not  made.  Low  marshy 
lands  adjacent  to  rivers,  lakes,  or  the  sea  may  be  filled  by  pumping 
silt  or  sand. 

When  filling  is  not  practicable,  good  and  permanent  results  may 
be  obtained  by  drainage.  As  a  rule,  the  draining  of  ponds,  pools,  or 
marshes  is  the  simpler  and  cheaper  method.  By  the  draining  of  marshes 
is  meant  the  draining  of  the  pools  of  stagnant  water,  or  in  the  case  of 
coastal  marshes  the  draining  of  the  stagnant  fishless  pools  tfiat  are  be- 
yond the  reach  of  the  ordinary  tides ;  it  does  not  necessarily  include  the 
draining  of  the  water-soaked  soil  itself.  The  underdraining  of  wide 
acreages  of  our  arable  land  in  the  Middle  West  has  been  very  effective 
in  suppressing  the  malarial  mosquito.  Marshy  lands  may  be  drained 
simply  by  means  of  ditches.  These  must  be  dug  of  depth  sufficient  com- 
pletely to  empty  the  pools  under  treatment  and  have  sufficient  fall  to 
prevent  stagnation  in  the  course  of  the  ditch  itself.  Where  a  sufficient 
fall  is  not  obtainable,  fishless  pools  may  be  connected  with  those  con- 
taining fish  or  with  a  neighboring  stream,  so  that  the  fish  may  freely 
enter.  Mosquito  breeding  places  in  the  pools  in  coastal  marshes  may 
be  suppressed  by  connecting  them  with  tide  water,  so  that  they  may 
be  freely  scoured  by  the  daily  tides.  Ditches  should  have  straight  sides 
and  must  be  inspected  at  frequent  intervals,  and  care  must  be  taken  to 
see  that  they  do  not  become  choked. 

Fish  are  among  the  most  effective  of  the  natural  enemies  of  the 
mosquito.  The  fish  may  be  admitted  to  ponds  and  pools  in  the  man- 
ner just  described,  or  the  ponds,  pools,  ornamental  lakes,  and  fountains 
may  be  directly  stocked  with  minnows  or  gold  fish.  The  margins  of 
pools,  rivers,  and  other  bodies  of  water  must  be  kept  free  of  reeds 
and  water  plants,  so  as  to  permit  the  fish  to  reach  the  edges — a  favorite 
breeding  place  for  mosquitoes.  In  still  waters,  fish  are  much  more 
effective  than  in  free-running  streams.  One  of  the  very  best  means  of 
clearing  the  land  of  the  numerous  small  natural  collections  of  water 
is  to  place  it  under  cultivation. 

When  radical  measures,  such  as  filling  in  or  draining,  are  not  prac- 
ticable, resort  may  then  be  had  to  coal  oil.  Coal  oil  upon  the  surface 
of  the  water  acts  by  poisoning  and  also  by  suffocating  the  larvae  and 
pupae.     A  light  quality  of  oil  should  be  used,^°  and  it  may  be  poured 

"  The  best  oil  for  the  purpose  is  known  to  dealers  as  "Fuel  oil  29-31." 


MOSQUITOES  283 

upon  tho  purfaco  from  an  ordinary  sprinkling  pot,  or  the  surface  may 
be  sprayed  -with  a  hose.  Aloii<,r  the  banks  of  ponds,  hikes,  and  slowly 
moving-  streams  with  shallow  margins  containing  vegetation,  which  offer 
favorite  breeding  ])laces  for  the  mosquito,  the  oil  may  he  a])plied  with 
a  mop.  This  ])racti(.-e  is  laborious,  ])ut  effective.  Sufficient  oil  sliould  be 
used  to  cover  the  entire  surface  with  a  thin  film.  As  the  oil  is  volatile, 
it  may  disappear  within  a  few  days.  Furthermore,  the  film,  which 
should  be  intact  to  be  effective,  may  be  broken  by  winds.  A  strong 
wind  will  bloAV  all  of  the  oil  to  one  side,  thereby  largely  defeating  the 
object  desired.  It  is,  therefore,  important  to  repeat  the  oiling  regularly 
at  intervals  of  about  one  week  or  13  to  14  days  for  Anopheles.  Oil- 
ing, though  fairly  effective  when  properly  carried  out,  is  only  a  tem- 
porary expedient,  and  in  the  end  is  rather  expensive.  See  also  page 
275. 

The  Panama  larvicide  is  made  as  follows :  150  gallons  of  crude 
carbolic  acid  having  a  specific  gravity  not  greater  than  0.97  and  con- 
taining not  less  than  30  per  cent,  tar  acids,  is  heated  in  an  iron  tank 
with  a  steam  coil  to  a  temperature  of  212°  F.,  then  200  pounds  of 
powdered  or  finely  broken  common  resin  is  poured  in.  The  mixture  is 
kept  at  a  temperature  of  212°  F.  Thirty  pounds  of  caustic  soda  dis- 
solved in  GO  gallons  of  water  are  then  added,  and  the  solution  is  kept  at 
the  same  temperature  initil  a  perfectly  dark  emulsion  without  sediment 
is  formed.  The  mixture  is  thoroughly  stirred  from  the  time  the  resin 
is  added  until  the  end.  One  part  of  this  emulsion  to  10,000  parts  of 
water  is  said  to  kill  Anopheles  larvae  in  less  than  half  an  hour,  while  1 
part  to  5,000  parts  of  water  will  kill  them  in  from  5  to  10  minutes. 

The  Panama  larvicide  is  mixed  with  5  parts  of  w^ater  and  sprayed 
upon  pools  or  along  the  banks  of  streams.  This  larvicide  added  to  5 
parts  of  crude  petroleum  favors  its  spread  upon  the  surface  of  the  water. 
A  good  method  is  to  place  the  mixture  in  a  barrel  and  permit  it  to 
drip  upon  the  surface  of  the  stream  or  pond  to  be  treated. 

Other  larvicides  that  may  be  used  in  non-potable  water  are :  sul- 
phuric, hydrochloric,  and  other  acids,  potassium  permanganate,  sulphate 
of  copper,  sulphate  of  iron,  bichlorid  of  mercury,  carbolic  acid,  aniliu 
products,  or  coal  tar.  They  must  be  used  in  relatively  large  amounts 
to  be  effective,  and  frequently  renewed  according  to  circumstances. 
Probably  the  most  practical  larvicide  for  water  barrels  is  ''nitre 
cake,"  a  by-product  of  powder  and  dynamite  factories — one  pound  to  a 
barrel. 

No  body  of  water  is  too  small  for  a  mosquito  nursery.  They  breed 
in  puddles  by  the  roadside;  in  water  that  accumulates  in  furrows  in 
gardens  or  fields,  especially  in  clayey  soil;  in  street  gutters  and  house 
gutters ;  in  holes  in  rocks ;  in  hollows  of  trees,  in  pitcher  plants,  or  any- 
where that  a  gill  of  water  is  allowed  to  stand. 


284  mSECT-BORNE  DISEASES 

Artificial  Breeding  Places. — The  permanent  elimination  of  artificial 
breeding  places  for  mosquitoes  in  a  city  depends  first  of  all  upon  provid- 
ing a  good  quality  and  sufficient  quantity  of  potable  water  by  means  of  a 
modern  closed  system.  This  will  permanently  do  away  with  the  neces- 
sity of  cisterns,  barrels,  and  tubs  for  the  storage  of  water  about  the 
premises.  When  domestic  storage  is  a  necessity,  care  must  be  taken  to 
prevent  the  mosquito  from  gaining  access  to  the  water.  The  water  bar- 
rels should  be  provided  with  tightly  fitting  covers.  Burlap,  sheeting,  or 
several  thicknesses  of  cheese-cloth,  or,  better,  wire  screening  held  in 
place  by  a  well-fitting  hoop,  serve  this  purpose  very  well.  Wooden 
covers  are  unsatisfactory,  for  they  rarely  fit  accurately  enough  to  keep 
out  the  mosquito,  and  this  defect  is  enhanced  by  the  warping  of  the 
wood,  which  usually  makes  an  old  cover  worse  than  useless.  More 
satisfactory  than  the  wooden  cover  is  one  made  of  light  ^  galvanized 
sheet  iron,  the  central  portion  of  which  may  be  made  of  wire  gauze.  The 
rim  of  the  barrel  should  be  trimmed  to  remove  any  irregularities  that 
might  prevent  the  cover  from  fitting  evenly  all  around.  Whatever  the 
form  of  the  cover  employed,  it  should  not  be  removed  except  for  cleaning 
or  refilling  the  barrel.  The  water  should  be  drawn  from  a  spigot. 
Where  the  water  is  very  turbid  and  must  undergo  sedimentation  before 
being  used,  several  barrels  should  be  provided  for  its  storage  and  the 
water  used  from  each  barrel  in  turn.  In  such  a  case  the  spigot  should 
be  placed  about  a  foot  from  the  bottom,  so  that  the  sediment  need  not 
be  disturbed  as  the  water  is  drawn  off  for  use.  Wells  should  be  pro- 
vided with  tight  covers  and  the  water  drawn  by  pumps. 

Cisterns  and  tanks  should  also  be  provided  with  accurately  fitting 
covers,  and  should  be  inspected  frequently  for  seams  and  cracks  result- 
ing from  warping  and  shrinking  of  the  wood.  To  guard  against  this 
loophole,  wire  gauze  should  be  used  to  screen  the  joint  between  the  tank 
and  its  cover.  The  gauze  should  include  about  one  foot  of  the  tank 
and  overlap  well  upon  the  cover.  The  inlet  to  the  tank  or  cistern 
should  be  provided  with  a  cap  of  copper  meshed  wire  gauze  which  may 
be  protected  by  another  and  coarser  meshed  cap  of  stout  wire,  to  pre- 
vent its  choking  with  leaves,  etc.  As  an  additional  precaution,  the  in- 
let pipe  should  stop  above  the  top  of  the  cistern,  discharging  its  water 
on  to  the  gauze  part  of  the  cover.  In  cases  of  emergency,  as  in  times 
of  epidemics  of  yellow  fever  or  dengue,  where  the  permanent  measures 
for  preventing  mosquito  breeding  have  been  neglected,  the  surface  of  the 
water  in  barrels,  tanks,  and  cisterns  may  be  covered  with  some  neutral 
non-volatile  oil  which  does  not  impart  a  taste  to  the  water. 

Cesspools  and  privy  vaults  should  be  done  away  with  and  replaced 
with  dry  earth  closets  or  a  water  carriage  system.  Where  this  has  not 
been  done  they  may  be  frequently  and  copiously  oiled. 

Among  the  artificial  breeding  places  for  mosquitoes  may  be  men- 


MOSQUITOES  285 

tioued  eliicken-pens  in  poultry  yards;  water  cups  on  the  frames  of 
grindstones;  baptismal  fonts;  tin  cans  or  broken  bottles  in  back  yards; 
the  catch  basins  of  sewers;  the  water  that  stands  in  sagging  house  gut- 
ters; flower-pots,  fire  buckets,  and  similar  places. 

Screening. — ^losquito  screens  are  the  obvious  and  most  effective 
single  measure  for  personal  prophylaxis  where  disease-carrying  mosqui- 
toes exist.  In  order  to  be  effective  the  screening  must  be  intelligently 
carried  out  with  careful  attention  to  details.  The  screen  itself  must 
be  sufficiently  close  to  keep  out  the  mosquitoes.  Some  of  them  are  able 
to  squeeze  through  surprisingly  narrow  chinks.  I  was  able  to  demon- 
strate, in  the  experimental  work  at  Vera  Cruz,  that  the  Stegomyia  mos- 
quito can  pass  a  metal  wire  screen  containing  16  strands  or  15  meshes  to 
the  inch,  but  cannot  pass  one  containing  19  strands  or  18  meshes  to  the 
inch.  When  the  screen  consists  of  a  fabric  which  is  apt  to  pull  out  of 
shape  so  that  some  of  the  meshes  are  larger  than  others,  it  is  advisable 
to  use  a  net  woven  closer  than  20  strands  to  the  inch.  Experience  in 
malarial  and  yellow  fever  districts  has  taught  this  lesson,  so  that  it  is 
customary  in  those  countries  to  use  a  rather  closely  woven  material  re- 
sembling nainsook.  Metal  screens  made  of  iron  wire  are  cheapest  only 
when  first  cost  is  considered.  They  hardly  last  a  season  unless  painted, 
in  which  case  the  size  of  the  mesh  is  considerably  reduced  and  inter- 
feres with  ventilation,  a  serious  objection  in  hot  weather  or  a  tropical 
climate.  Mesh  made  of  galvanized  iron  wire  has  a  greater  durability. 
Screens  made  of  brass  or  bronze  are  expensive,  but  cheap  in  the  long 
run,  as  they  last  almost  indefinitely. 

The  screening  should  include  the  entire  house,  or  at  least  those 
parts  that  are  occupied.  In  the  tropics  it  is  better  to  screen  the  "gal- 
leries" than  each  individual  window.  In  any  case,  frequent  and  repeated 
inspection  should  be  made  to  discover  breaks  in  the  screen  or  openings 
due  to  warping  of  the  woodwork.  Care  must  be  exercised  not  to  over- 
look fireplaces,  ventilators,  and  other  openings.  The  door  should  be 
guarded  by  a  screened  vestibule  of  such  a  depth  as  to  make  it  impossible 
for  a  person  to  hold  both  doors  open  at  the  same  time.  The  screen  door 
should  open  outward  and,  if  possible,  should  be  exposed  to  the  direct 
sunlight  during  the  day,  without  vines  or  nearby  vegetation  of  any  kind 
to  protect  and  lodge  the  mosquitoes.  During  the  night  the  door  should 
not  be  in  an  artificial  light,  which  attracts  many  mosquitoes.  x\n  electric 
fan  directed  outward  is  a  very  good  de\'ice  to  prevent  mosquitoes  flying 
through  the  doorway.  In  addition,  a  whiskbroom  or  feather  duster  should 
hang  in  the  vestibule  to  brush  off  the  insects  that  may  rest  upon  the 
clothing.    A  screened  house  is  safe  only  to  careful  and  intelligent  people. 

In  addition  to  screening  the  house,  mosquito  bars  over  the  bed  will 
be  found  necessary  in  mosquito-infested  places.  It  is  best  to  suspend  the 
mosquito  bar  from  the  ceiling  and  carefully  gather  the  bottom  together 


286  INSECT-BOENE  DISEASES 

so  as  to  keep  the  insects  out  during  the  day  time.  At  night  the  bar 
should  be  carefully  tucked  in  around  the  bed  so  as  to  leave  no  openings. 
Mosquitoes  have  no  trouble  in  biting  through  the  meshes  of  the  bar, 
provided  a  restless  sleeper  comes  close  enough  to  it. 

Persons  who  are  required  to  go  out  at  night  in  a  malarious  district, 
or  who  must  expose  themselves  during  yellow  fever  times,  may  screen 
themselves  effectively  with  a  veil  of  mosquito  netting  hanging  from  a 
broad-brimmed  hat  to  the  shoulders  and  chest.  The  hands  and  wrists 
may  be  protected  with  gloves,  and  the  ankles  with  leather  leggings  or 
other  suitable  mechanical  device. 

Volatile  Substances. — Spirits  of  camphor,  oil  of  pennyroyal,  and 
other  volatile  substances,  such  as  oil  of  peppermint,  lemon  juice,  or 
vinegar,  rubbed  upon  the  face  and  hands,  or  a  few  drops  on  the  pillow 
at  night,  may  keep  mosquitoes  away  only  for  a  time.  Oil  of  citronella 
is  one  of  the  best  known  substances  used  in  this  way.  Ordinarily  a 
few  drops  on  a  bath  towel  hung  over  the  head  of  the  bed  may  keep  some 
mosquitoes  away.  When  they  are  very  abundant  and  persist,  a  few 
drops  rubbed  oh  the  face  and  hands  may  be  tried.  All  these  substances 
soon  lose  their  efficiency ;  none  of  them  last  until  morning. 

The  diseases  known  to  be  conveyed  by  mosquitoes  are :  malaria 
(Anopheles  spp.),  yellow  fever  (Stegomyicb  calopus),  filariasis  (Culex 
and  Anopheles) ,  dengue  ( Stegomyia  calopus),  and  doubtless  others. 

MALARIA 

Malaria  is  one  of  the  most  prevalent  of  all  preventable  diseases ;  it  is 
the  scourge  of  the  tropics.  The  cause  of  this  infection  was  one  of  the 
first  to  be  discovered  (Laveran,  1880),  and  its  mode  of  transmission 
was  one  of  the  most  brilliant  discoveries  in  sanitary  science  (Eoss, 
1895).  Despite  the  fact  that  we  have  more  exact  knowledge  of  malaria, 
considering  the  difficulties  of  the  subject,  than  perhaps  any  other  dis- 
ease, despite  the  fact  that  we  have  accurate  means  of  diagnosis  and  a 
ready  cure,  and  despite  the  fact  that  we  have  assured  measures  of  pre- 
vention, malaria  counts  its  victims  by  the  hundreds  of  thousands  annu- 
ally. In  geographic  distribution  malaria  extends  from  the  Arctic  circle 
to  the  Equator,  but  becomes  more  virulent  the  warmer  the  climate. 

There  are  probably  a  million  cases  of  clinical  malaria  in  our  south- 
ern states  each  year — and  the  carriers  far  outnumber  the  cases.  The 
distribution  is  very  unequal,  but  chiefly  rural.  Wherever  malaria  pre- 
vails, and  almost  in  direct  proportion  to  its  prevalence,  the  population 
is  generally  subnormal  physically,  mentally  and  economically. 

At  least  three  separate  malarial  parasites  of  man  are  known,  namely : 
(1)  Plasmodium  malariae  (Laveran),  quartan  fever;  (2)  Plasmodium 
vivax  (Grassi  and  Feletti),  tertian  fever;  and  (3)  Plasmodium  falcip- 


MOSQUITOES  287 

(tru)it  (\Vc'k-li),  t'.sti\()-aiitiiiiiiiiil  oi-  tropiial  malaria.  Tiiese  are  closely 
allied  hcmatocytozoa  or  1)1(h)(1  parasites.  They  i)r()(lii((>  diseases  with 
well-defined  clinical  dilTcrences,  hut  havinf^  the  same  ('ti()l()<ry  and  mode 
of  transference,  so  that,  as  far  as  prevention  is  concerned,  they  may 
be  regarded  as  one  infection. 

IMany  species  of  animals  have  a  malarial-like  infection  closely  re- 
sembling malaria  in  man;  for  example,  Texas  fever  of  cattle,  piroplas- 
mosis  of  dogs  and  sheep,  proteosoma  of  birds,  etc.  So  far  as  is  known, 
no  other  animal  than  the  Anopheles  mosquito  is  subject  to  the  malarial 
parasites  pathogenic  for  man.  Both  man  and  the  mosquito  are  neces- 
sary to  complete  the  life  cycle  of  the  plasmodium.  Man  is  the  inter- 
mediate host  harboring  the  asexual  phase,  and  the  mosquito  is  the  defin- 
itive host  harboring  the  sexual  phase  of  the  life  cycle  of  the  plas- 
modium. 

Mosquito  Transmission. — It  is  now  definitely  known  that  in  nature 
malaria  is  transmitted  only  by  the  bite  of  the  Anopheles  mosquito. ^^ 
Experimentally,  the  infection  may  be  transferred  by  injecting  blood 
(containing  the  parasites)  of  one  person  into  the  blood  of  another. 
Nearly  2,000  years  ago  Yarro  and  Columbella  mentioned  the  possibility 
that  the  disease  was  transmitted  by  mosquitoes.  In  Africa  some  savage 
tribes  call  malaria  the  "mosquito  disease."  In  1848  Xott,  of  Xew  Or- 
leans, considered  the  matter  proved  from  biological  analogies.  In  1882 
King,  of  Washington,  vigorously  advocated  the  mosquito  theory  based 
upon  philosophical  deductions  but  no  proof.  In  1881:  Laveran  suggested 
mosquito  transmission  as  probable.  In  1894  Manson  elaborated  the 
mosquito  theory  and  inspired  Eoss,  of  the  Indian  Army  Medical  Service, 
who  in  1895  demonstrated  that  the  crescents  of  estivo-autumnal  malaria 
undergo  changes  in  the  mosquito.  In  1896  Bignami  advocated  the 
theory  and  compared  it  to  the  transmission  of  Texas  fever  by  the  tick. 
In  1897  Eoss  published  further  convincing  observations  upon  the  de- 
\'elopment  of  the  estivo-autumnal  parasite  in  the  mosquito.  In  1897  Mac- 
Callum  observed  an  important  missing  link  in  the  life  cycle  by  observ- 
ing the  fiagellum  of  the  microgametocyte  (male)  fertilize  the  macro- 
gametocyte  (female)  with  the  formation  of  the  vermicule.  These  ob- 
servations were  made  upon  Halteridium  or  malaria  of  birds ;  later  he  saw 
the  same  phenomenon  in  estivo-autumnal  malaria.  The  life  cycle  of  the 
malarial  parasite  has  been  confirmed  by  Daniels,  Koch,  Grassi,  Big- 
nami, Celli,  Manneberg,  Schaudinn,  and  many  others. 

Further  evidence  that  malaria  is  transmitted  by  the  mosquito  was 
furnished  by  Sambon  and  Low,  of  the  London  School  of  Tropical  iledi- 
cine,  and  Dr.  Terzi.  who  lived  during  the  three  most  malarial  months  of 

"The  subfamily  Anophelinae  has  been  divided  by  Theobald  (1901)  into  sev- 
eral genera:  Anopheles,  Myzomyia,  Cellia,  Myzorhynchus,  ISTyssorhyncus,  Py- 
retophorus,  etc.    This  classification  serves  no  useful  purpose  and  is  unnecessary. 


288 


IKSECT-BORNE  DISEASES 


1900  in  Ostia,  a  very  malarial  locality  of  the  Eoman  Campagna.  These 
observers  escaped  infection  simply  by  keeping  within  their  well-screened 
huts  from  before  sundown  until  after  sunrise.  The  final  proof  was  fur- 
nished in  1900  by  Dr.  P.  Thurber  Manson  and  Mr.  George  Warren,  who 
were  bitten  by  infected  mosquitoes  forwarded  from  Italy  in  cages  to 
London. 

In  the  United  States,  malaria  probably  hibernates  in  man  and  not  in 
the  mosquito.  Mitzmain  ^~  believes  man  the  sole  winter  carrier  of  ma- 
laria in  our  southern  states,  aiid 
the  new  crop  of  mosquitoes  are 
infected  in  the  spring  from  the 
gametocytes  in  the  blood  of  ma- 
larial carriers.  Hence  the  im- 
portance of  starting^  preventive 
measures  in  the  winter  or  early 
spring. 

The  Malarial  Mosquito. — At 
least  twenty-five  species,  in  six 
genera  of  the  subfamily  Anophe- 
linae  are  more  or  less  definitely 
known  to  carry  malaria.^^  In 
Europe  Anopheles  maculipennis ; 
in  tropical  America  A.  argyro- 
tarsus  or  albipes;  in  temperate 
America,  A.  quadrimaculatus, 
which  is  probably  the  same  as 
A.  maculipennis,  also  A.  punctipennis  and  A.  crucians;  in  India  A.  sinen- 
sis; in  Africa  A.  costalis  are  the  chief  culprits.  Darling  ^*  found  that  70.8 
per  cent,  of  Anopheles  albimanus  induced  to  bite  malarial  patients  be- 
came infective,  while  with  Anopheles  pseudopunctipennis  only  12.9  per 
cent,  could  be  infected. 

The  Anopheles  mosquitoes  are  brownish  and  rather  large.  They  may 
be  distinguished  by  the  fact  that  the  palpi  in  both  the  male  and  the 
female  are  at  least  as  long  as  the  proboscis.  Only  the  female  transmits 
the  infection.  It  sits  more  or  less  at  right  angles  upon  the  wall,  the 
head,  thorax,  and  abdomen  being  in  a  straight  line.  Contrary  to  the 
yellow  fever  mosquito,  the  malarial  mosquito  is  nocturnal  in  its  habits 
and  breeds  chiefly  in  the  open  ponds,  puddles,  and  natural  collections 
of  water  in  the  woods,  fields  and  swamps. 

^^  Public  Health  Bulletin  No.  84,  Dec,  1916. 

"  See  Craig,  The  Malarial  Fevers,  New  York,  1909,  and  Knab,  Am.  Jour,  of 
Tropical  Diseases  and  Preventive  Medicine,  July,  1913,  I,  1,  p.  37,  also  Castellani 
and  Chalmers,  Manual  of  Tropical  Medicine,  1919,  for  full  list,  classification  and 
geographical  distribution. 

"  Darling,  Samuel  T.  Transmission  of  Malarial  Fever  in  the  Canal  Zone  by 
Anopheles  Mosquitoes.    Jour.  A.  M.  A.,  1909,  LIU,  pp.  2051-2053. 


Fig.  22. — Anopheles  Punctipennis. 


MOSQUITOES  289 

The  mosquito  becomes  infected  upon  (lrinkin<^  the  blood  containing 
the  micro-  and  macro-gametocytes.  It  requires  about  twelve  days  before 
the  sporozoites  appear  in  the  salivary  glands  of  the  insect.  It  cannot, 
therefore,  transmit  the  infection  to  another  person  until  the  lapse  of 
this  extrinsic  period  of  incubation.  The  infected  mosquito  may  live  a 
long  time  and  infect  more  than  one  person  successively.  The  malarial 
parasite  does  not  seem  to  harm  the  mosquito. 

The  parasite  will  not  develop  in  the  mosquito  when  the  mean  tem- 
perature is  below  00°  F. 

They  can,  however,  survive  at  much  lower  temperatures  for  a  short 
time.  King  ^^  has  shown  that  the  tertian  parasite  is  able  to  survive  ex- 
posure to  a  temperature  of  30°  F.  for  2  days;  31°  F.  for  4  days;  and  a 
mean  temperature  of  46°  F.  for  17  days.  The  sporonts  of  the  estivo- 
autumnal  parasite  have  resisted  35°  F.  for  24  hours. 

JSTone  of  the  Anophelinae  are  "domestic"  in  the  sense  of  our  house 
mosquitoes,  such  as  Culex  pipiens,  C.  quinquefasciafus  and  A'edes  calo- 
pns,  and  this  is  not  necessary  for  the  transmission  of  malaria.  The  long 
presence  of  the  malarial  parasite  in  the  human  circulation,  and  the  conse- 
quent frequent  opportunity  for  the  mosquito  to  acquire  the  infection 
from  carriers  compensates  for  a  very  loose  association  between  man 
and  insect. 

Immunity. — A  person  who  once  has  had  malaria  seems  more  apt  to 
have  subsequent  attacks.  Often  there  appears  to  be  an  increased  suscep- 
tibility rather  than  an  immunity,  although  these  subsequent  attacks  may 
be  relapses.  However,  repeated  infections,  during  early  life,  leave  a  pro- 
nounced resistance.  In  malarious  regions  many  children  carry  the  para- 
sites in  their  circulating  blood  w^ithout  any  manifestations  of  the  disease. 
These  carriers  are  important  factors  in  spreading  the  infection  in 
endemic  areas,  and  must  be  taken  into  account  in  preventive  measures. 
In  endemic  regions  carriers  far  outnumber  the  cases.  It  requires  much 
more  quinin  to  sterilize  a  carrier  than  to  cure  a  clinical  case. 

There  is  no  true  racial  immunity  in  this  disease.  Practically  all 
persons  who  receive  the  infection  for  the  first  time  are  susceptible.  The 
freedom  from  malaria  which  some  persons  seem  to  enjoy  may  be  ac- 
counted for  partly  by  the  fact  that  mosquitoes  seldom  bite  such  persons. 
It  is  well  known  that  on  account  of  the  odors,  or  what  not,  mosquitoes 
do  not  bother  certain  individuals.  ISTo  doubt  the  infection  of  a  small 
number  of  parasites  is  often  overcome  largely  through  a  vigorous  phago- 
cytosis. 

Individual  resistance  varies  in  different  individuals  and  in  the  same 
individual  at  different  times.  The  parasite  may  remain  latent  in  the 
spleen  or  other  organs  for  years.  Exposure,  overeating,  fasting,  over- 
work, or  worry,  or  anything  that  lowers  the  vitality  of  such  individuals 

«Jowm.  Exp.  Med.,  March  1,  1917,  XXV,  No.  3. 


290  INSECT-BORNE  DISEASES 

predisposes  to  an  attack  of  malaria.  The  disease  often  breaks  out  in 
persons  in  good  health  leaving  a  malarial  region  for  a  health  resort, 
whether  mountain  or  seashore.  I  was  enabled  to  confirm  this  observa- 
tion upon  the  returning  transports  from  Cuba  following  the  Spanish- 
American  war,  when  many  cases  of  malaria  broke  out  among  the  troops 
previously  in  good  health  upon  exposure  to  the  cold  winds  about  Cape 
Hatteras.  Personal  prophylaxis,  therefore,  includes  careful  attention  to 
personal  hygiene. 

Prevention. — The  successful  suppression  of  malaria  requires  a  com- 
bined attack  upon  the  mosquito  and  the  parasite  in  the  human  host. 
Ultimate  success  rests  upon  the  suppression  of  the  mosquito.  Imme- 
diate relief  is  most  quickly  gained  by  measures  directed  against  the  in- 
fection in  man.  Screening  and  quinin  prophylaxis,  while  practical,  are 
only  temporary  measures. 

Celli  ^^  found  that  although  the  destruction  of  mosquitoes  is"  possible 
in  the  laboratory  and  in  small  areas,  the  difficulties  in  extensive  areas 
are  generally  insuperable. 

Harris  maintains  that  the  most  practical  measure  at  this  time  in  the 
crusade  against  malaria  is  the  radical  cure  of  those  harboring  parasites. 
Every  person  cured  means  one  less  focus  of  infection.  Koch  and  Celli, 
in  1900,  urged  that  the  best  way  to  deal  with  malaria  in  the  island  of 
Mauritius  would  be  to  leave  the  mosquito  alone  and  to  cure  the  human 
patients  from  whom  the  insects  become  infected.  By  the  use  of  this 
method  Eoss  tells  us  that  Stephensport  in  New  Guinea  was  cleared  of 
malaria  in  a  few  months.  The  method  has  also  been  successful  at  Lonoke, 
Arkansas  (by  Geiger),  and  in  the  Yazoo  Delta,  Mississippi  (by  Bass). 
Good  results  with  both  methods  have  been  obtained  by  the  Public 
Health  Service  and  also  by  the  International  Health  Board. 

Le  Prince  ^^  demonstrated  that  at  Gatun  Anopheles  will  ily  great 
distances.  Le  Prince  and  Griffith  registered  flights  of  a  mile  in  South 
Carolina  by  A.  quadrimacnJatvs  from  breeding  places  producing  pro- 
fusely. This  was  confirmed  by  Geiger  in  Arkansas  and  by  Metz  for  A. 
crucians  in  Alabama.  There  is,  however,  very  little  doubt  that  in  the 
majority  of  places  malaria  is  a  local  infection;  that  is,  the  mosquitoes 
acquire  the  gametes  and  transmit  the  sporozoites  within  a  restricted 
area. 

The  maximum  malarial  rate  is  at  its  height  at  or  toward  the  end  of 
the  warm  season,  because  warmth  over  60°  F.  favors  the  development 
of  the  parasite  within  the  mosquito.     The  best  time  to  attack  the  para- 

"  Celli:  Cited  bv  Leslie:  Proc.  of  the  Imperial  Malarial  Conf.,  Simla.  India, 
1910,  p.  8.  ' 

"  Le  Prince:  "Recent  Progress  in  Antimalaria  Work,  with  Special  Reference 
to  Anopheles  Flight  as  Studied  on  the  Isthmus  of  Panama."  Tr.  Fifteenth  In- 
ternat.  Cong,  on  Hyg.  and  Demog.,  V,  Part  II,  p.  544.  Public  Health  Reports, 
May  4,  1917. 


MOSQUITOES  291 

sites  in  man  is  during  the  winter  and  early  spring  so  as  to  prevent  in- 
fection of  the  new  summer  brood  of  mosquitoes. 

Measures  iJireefed  against  the  Mosquito. — If  the  breeding  of 
Anophelinae  mosquito  could  be  stopped  malaria  would  cease.  Mosquito 
suppression  is  fundamental  and  radical.  The  best  way  to  abolish  the 
breeding  places  of  malaria  mosquitoes  is  to  fill  up  low  places  or  to  dry 
the  surface  of  the  land  with  drains.  These  two  measures  hold  first 
place  as  permanent  work.  The  underdraining  of  large  areas  of  our 
arable  land  of  the  Middle  West  with  tiled  drain  has  been  very  effective 
in  suppressing  malaria.  Open  ditches  properly  constructed  and  cared 
for  are  likewise  effective.  In  the  tropics  the  ditches  should  be  lined 
with  cement,  on  account  of  the  luxuriant  vegetation  which  soon  inter- 
feres with  their  efficiency  or  may  actually  convert  them  into  breeding 
places.  The  open  ditches  are  much  the  cheapest  in  first  cost,  but  not 
when  maintenance  is  reckoned.  The  draining  of  swamp  lands  is  an 
engineering  problem  in  which  the  economic  factor  looms  large.  One  of 
the  very  best  means  of  destroying  the  breeding  places  of  the  malaria 
mosquito  is  to  clear  the  land  and  to  keep  it  under  cultivation. 

When  drainage  is  not  practical,  the  number  of  mosquitoes  may  be 
kept  down  by  introducing  fish  into  the  pools,  streams,  ditches,  and  other 
collections  of  water.  Upon  limited  water  surfaces  the  larvae  may  be 
killed  with  a  film  of  coal  oil  or  the  Panama  larvicide  (page  283). 

Large  open  spaces  cause  the  destruction  of  a  number  of  mosquitoes, 
as  they  cannot  live  long  in  the  hot  sun;  therefore,  clearing  the  brush 
and  high  grass,  which  furnish  shelter  to  the  insects,  aids  in  preventing 
wild  mosquitoes  approaching  dwelling  houses. 

Bats  are  natural  enemies  of  mosquitoes  and  should  therefore  be  pro- 
tected.^^ 

The  use  of  screens  and  culicides  has  already  been  referred  to  (pages 
268  and  285). 

The  best  time  to  begin  antimosquito  measures  is  as  early  in  the 
spring  as  possible. 

Wickliffe  Eose  states  that  for  the  average  town  in  our  southern 
states  having  a  thousand  or  more  inh-abitants  and  a  reasonably  high  in- 
fection rate,  malarial  control  by  antimosquito  measures  is  economically 
feasible  and  a  sound  business  investment. 

Personal  Prophylaxis. — Persons  visiting  or  residing  in  a  malari-  • 
ous  region  should  be  particularly  careful  not  to  expose  themselves  at 
night  time.  The  experience  of  Sambon  and  Low  on  the  Eoman  Cam- 
pagna  (page  287)  is  instructive  and  should  be  imitated.  The  location  of 
the  residence  is  important.  In  a  city  it  should  be  a  reasonably  safe 
distance  from  the  native  quarter,  because  the  infection  is  there  most 
concentrated;  but  not  in  the  suburbs.     The  dwelling  should,  if  possible, 

^Howard,  L.  0.:  U.  8.  Public  Health  Reports,  35,  July  15,  1920,  p.  1789. 


292  INSECT-BORNE  DISEASES 

face  the  trade  winds.  A  row  of  tall  trees  will  partly  screen  the  house 
from  the  swamp,  but  the  trees  must  not  be  too  close,  else  they  will  fur- 
nish shelter  for  the  insects.  The  house  should  be  on  high  land  if  prac- 
ticable, as  it  is  an  old  observation  that  the  malarial  mosquito  does  not 
fly  high.  People  living  upon  the  second  floor  are  less  apt  to  contract 
the  infection  than  those  who  sleep  on  the  ground  floor.  If  it  is  neces- 
sary to  go  out  in  the  night  time,  one  may  protect  himself  by  the  use  of 
gloves  and  mosquito  netting  hanging  from  the  helmet  to  the  shoulders. 
Care  must  be  taken  to  guard  the  ankles  against  mosquito  bites.  x\s  all 
these  measures  require  much  time  and  attention  to  details,  they  are 
usually  not  efficient  in  actual  practice.  Therefore,  quinin  prophylaxis 
is  much  used. 

Quinin  Prophylaxis. — Theoretically  the  administration  of  quinin 
to  healthy  individuals  for  the  prevention  of  malaria  is  not  an  ideal 
method  of  prophylaxis,  for  it  does  not  prevent  infection,  but  only  de- 
stroys the  parasites  in  the  blood  during  the  period  of  incubation;  prac- 
tically it  is  cheap  and  eifective.  It  should  be  remembered  that  quinin 
kills  only  the  young  and  tender  forms  of  the  plasmodium,  and  has  no 
influence  upon  the  crescents.  Quinin  prophylaxis  is  indicated  in  propor- 
tion to  the  difficulty  of  pursuing  more  permanent  methods.  It  is  es- 
pecially valuable  where  screens  and  mosquito  bars  are  not  available,  as 
in  camping,  marching,  traveling,  or  where  the  occupation  takes  one  out 
at  night.  When  residents  of  non-malarial  countries  go  into  malarial 
localities,  especially  in  the  rural  districts,  for  short  periods  of  time, 
quinin  is  a  valuable  preventive. 

A  farmer  may  not  be  able  to  drain  and  clear  his  land  so  as  to  get 
rid  of  mosquitoes ;  he  may  not  be  able  to  screen  his  house  and  keep  his 
screens  in  order,  but  he  will  always  be  able  to  buy  the  amount  of  quinin 
which  will  protect  his  family  from  fever,  especially  as  it  may  cost  no 
more  to  prevent  malaria  than  it  would  to  cure  it — maybe  less.  Quinin 
prophylaxis  is  not  so  good  a  method  as  suppressing  mosquitoes,  but  in 
many  communities  this  is  impracticable;  it  is  not  so  good  as  screening, 
carefully  watched,  but  this  is  also  impracticable  in  many  rural  com- 
munities. 

The  systematic  use  of  quinin  as  a  prophylactic  on  a  large  scale  is 
of  recent  origin.  The  government  of  Italy  in  1902  began  the  sale  of 
quinin  at  cost  price-to  communities  and  towns,  which  agreed  to  distribute 
it  gratuitously  to  those  unable  to  purchase  it.  In  1903  the  towns,  etc., 
were  obligated  to  issue  it  free  of  cost  to  poor  people  for  prophylactic 
use.  The  next  year,  1904,  it  was  ordered  to  be  given  to  all  working 
people  for  use  in  this  way.  This  is  a  beneficent  public  health  measure 
comparable  to  the  free  distribution  of  antitoxin  and  vaccine  virus.  There 
has  been  a  great  diminution  in  the  amount  of  malaria  among  the  farm- 
ing  people  of  Italy  since  the  introduction  of  quinin  prophylaxis ;  further- 


MOSQUITOES  293 

more,  the  reduction  has  been  progressive — increasing  as  the  people  learn 
its  value. 

To  be  effective  as  a  preventive  of  malaria,  quinin  must  be  taken  in 
sufficient  doses  during  the  entire  malarial  season.  The  size  of  the  dose 
and  the  interval  at  wliich  the  prophylactic  is  administered  are  of  the 
utmost  importance.  There  are  two  principal  methods  of  administration : 
the  one,  canonized  by  Koch,  consists  of  large  doses  at  considerable  inter- 
vals; the  other,  used  in  Italy,  consists  of  smaller  daily  amounts.  Koch 
advised  IG  grains  (one  gram)  of  quinin  every  sixth  and  seventh  day,  or 
every  seventh  and  eighth  day,  eighth  and  ninth,  ninth  and  tenth  day,  ac- 
cording to  the  danger  of  the  infection.  This  manifestly  leaves  several 
intervening  days  in  which  there  is  no  quinin  in  the  circulation.  The 
method  has  been  eminently  successful  in  the  very  malarious  districts 
of  German  West  Africa,  and  also  in  the  hands  of  the  Japanese  in  For- 
mosa. There  are  several  modifications  of  Koch's  method.  Plehn  advises 
8  grains  every  five  days ;  this  amount  may  even  be  taken  twice  a  week. 

Zicmann  gives  a  gram  of  quinin  sulphate  every  four  days.  The  al- 
kaloid is  administered  in  solution  with  5  drops  of  hydrochloric  acid  early 
in  the  morning  or  about  one  and  one-half  to  two  hours  after  a  meal. 
A  convenient  rule  is  to  give  a  dose  on  the  first  of  the  month  and  there- 
after on  each  day  of  the  month  divisible  by  4.  By  this  method  the  alka- 
loid is  probably  constantly  in  the  circulating  blood. 

The  administration  of  small  doses  of  quinin  daily  is  the  oldest  method 
of  giving  quinin  as  a  prophylactic.  The  amount  varies  from  l^^  to  7 
grains  daily.  In  Italy  the  average  amount  is  5  to  7  grains  of  sulphate 
of  quinin  daily,  and  half  that  amount  for  children  under  10  years.  For 
children  the  tannate  of  quinin  made  up  into  chocolates  is  recommended. 
The  tannate  of  quinin  contains  only  about  half  the  amount  of  quinin 
found  in  the  sulphate,  therefore  about  5  grains  of  the  tannate  is  the 
equivalent  of  S^o  grains  of  the  sulphate. 

On  the  Isthmus  of  Panama  good  results  have  been  obtained  by  the 
use  of  moderate  doses,  3  to  6  grains  per  day.  When  the  disease  in- 
creases in  prevalence  or  virulence  the  amount  is  raised  to  8  or  10  grains 
per  day,  then  dropping  off  to  4  or  5.  Craig  found  Si/o  grains  of  quinin 
per  day  sufficient  against  tertian  and  quartan  infections.  James  lays 
stress  on  giving  the  daily  do«e  of  quinin  in  the  evening. 

The  particular  method  of  election  in  giving  quinin  prophylaxis 
should  be  chosen  according  to  the  experience  of  the  region.  Wliatever 
method  of  quinin  prophylaxis  is  selected  the  quinin  should  be  taken 
throughout  the  malarial  season,  say  June  to  Xovember.  Those  who  have 
had  malaria  should  begin  in  March  or  April  in  order  to  prevent  re- 
lapses, for  latent  malaria  is  very  apt  to  reassert  itself  in  the  spring. 

It  is  advisable  not  to  stop  the  use  of  quinin  immediately  on  the 
advent  of  cold  weather  or  on  leaving  a  malarial  district,  even  if  one  has 


294  INSECT-BOEJiTE  DISEASES 

not  had  malarial  fever.  It  is  good  practice  to  continue  the  quinin  for 
one  or  two  months,  until  natural  resistance  can  overcome  the  infec- 
tion. 

No  ill  effects  have  been  noted  from  the  prolonged  use  of  quinin  as 
advised  above.  Carter  ^^  states  that  many  Americans  at  Panama,  where 
the  malarial  season  lasts  12  months,  took  three  2-gTain  tablets  of  quinin 
daily  for  2i^  years  without  complaint  or  injury.  The  quinin  was  passed 
around  at  the  mess  tables  at  Ancon  Hospital  as  regularly  as  the  bis- 
cuits. 

Occasionally  an  individual  is  found  who  has  an  idiosyncrasy  to 
quinin.  Some  people  bear  quinin  less  well  than  others.  Five  to  7  grains 
may  cause  discomfort  at  first,  but  a  tolerance  may  be  established  by 
persevering  a  week  or  two. 

Quinin  taken  as  a  prophylactic  does  not  develop  '^blackwater  fever'^ — 
on  the  contrary,  by  diminishing  the  number  and  severity  of  the, malarial 
attacks,  it  diminishes  the  liability  to  hemorrhagic  malarial  fever.  Some 
persons  seem  to  have  an  idiosyncrasy  to  quinin  and  there  is  a  suspicion 
that  large  doses  predispose  to  hemoglobinuria.  The  etiology  and  pre- 
vention of  blackwater  fever  is  still  uncertain. 

Quinin  prophylaxis  lowers  the  malarial  sick-rate  and  death-rate. 
Celli's  statistics  for  Italy  are  convincing.  Good  results  are  also  reported 
from  Greece,  Algeria  and  Panama.  The  deaths  from  malaria  in  Italy 
during  ten  years  preceding  1902  averaged  14,048  annually,  whereas  dur- 
ing the  nine  years  following  1902  the  average  fell  to  3,853  per  year  as 
a  result  of  quinin  prophylaxis.  Better  results  were  obtained  when  quinin 
prophylaxis  was  compulsory  as  in  the  penal  agricultural  colony  at  Castia- 
das,  where  the  malaria  was  reduced  from  76  per  cent,  of  the  force  to 
0  per  cent.  The  results  in  the  Italian  Army  were  equally  good.  When 
the  quinin  was  taken  under  orders  malarial  fever  fell  from  27.5  per 
cent,  in  1902  to  4.9  per  cent.,  of  which  3  per  cent,  were  relapses,  in  1911. 
Bass  obtained  good  results  in  controlling  malaria  in  Bolivar  and  Sun- 
flower Counties  in  Mississippi  from  1916  to  1918,  by  using  10  grains 
of  quinin  daily  before  retiring,  for  a  period  of  eight  weeks. 

The  way  quinin  prevents  the  development  of  malaria  is  almost  cer- 
tainly by  keeping  the  number  of  parasites  below  the  number  necessary 
to  produce  an  attack.  It  does  not  prevent  the  development  of  "carriers," 
yet  it  lessens  the  amount  of  malaria  by  diminishing  the  number  of  para- 
sites. As  malaria  lessens,  prosperity  increases  due  to  improvement  in 
strength  and  energy  of  the  people,  and  with  increased  prosperity  comes 
land  better  cleared  and  better  drained,  houses  screened,  and  better  hy- 
giene generally — an  endless  chain  of  betterment.  It  is  only  in  this  way — 
by  quinin  prophylaxis  leading  to  antimosquito  work — that  permanent  re- 
sults can  be  obtained  in  some  places. 

"P.  H.  Reports,  Mar.  28,  1914,  Vol.  29,  No.  13.  p.  741. 


MOSQT^TTOES  295 

Qiiinin  prophylaxis  has  advantages  that  commend  it  as  a  prompt, 
cheap  and  practical  measure.  It  is  at  best,  however,  only  tentative  and 
does  not  take  the  place  of  mosquito  suppression. 

Quinin  treatment  should  be  aimed  at  relieving  symptoms,  prevent- 
ing relapses  and  also  preventing  transmission  of  the  infection  to  others. 
The  following  method  of  using  quinin  will  usually  accomplish  all  these 
purposes :  For  the  acute  attack,  10  grains  of  quinin  sulphate,  by  mouth, 
three  times  a  day  for  a  period  of  at  least  3  or  4  days,  to  be  followed 
by  10  grains  every  night  before  retiring  for  a  period  of  8  weeks;  for 
infected  persons  not  having  acute  symptoms  at  the  time,  only  the  8 
weeks'  treatment  is  required. 

REFERENCES 

Deadrick  :    "A  Practical  Study  of  Malaria."    Philadelphia,  1909. 

Craig  :    "The  Malarial  Fevers,  Hemoglobinuric  Fever  and  the  Blood  Proto- 
zoa of  Man."    New  York,  1909. 

Henson:    "Malaria  Etiology,  Pathology,  Diagnosis,  Prophylaxis  and  Treat- 
ment."   St.  Louis,  1913. 

Boss:     "The  Prevention  of  Malaria."    London,  1910. 

The  original  discovery  of  the  malarial  parasite  was  announced  by  Laveran 
in  the  Acad,  de  Med.,  Paris,  Nov.  23,  1880,  and  Dec.  28,  1880. 

Publications   of  the  LTnited   States   Public  Health   Service,   Washington,  ^ 
D.  C,  and  the  International  Health  Board  of  the  Rockefeller  Founda- 
tion, 61  Broadway,  New  York  City. 


YELLOW  FEVER 

The  prevention  of  yellow  fever  rests  entirely  upon  the  fact  that  it 
is  communicated  through  the  bite  of  an  infected  mosquito — the  Stego- 
myia  calopus^^  The  mosquito  becomes  infected  by  sucking  the  blood  of 
yellow  fever  patients  during  the  first  three  days  of  the  fever.  All  the 
experimental  evidence  thus  far  shows  that  the  infection  is  absent  from 
the  blood  after  the  third  day,  and  that  mosquitoes  do  not  become  in- 
fective after  this  period.  The  importance  of  this  fact  in  preventing  the 
spread  of  the  disease  is  evident.  The  mosquito,  after  drinking  the  in- 
fected blood,  is  not  able  to  transfer  the  infection  to  another  person  until 
about  twelve  days  -^  have  elapsed ;  that  is,  it  requires  about  twelve  days 
for  the  yellow  fever  parasite,  whatever  it  may  be,  to  undergo  its  cycle 
of  development  in  the  mosquito.     The  mosquito  once  infected  remains 

^This  mosquito  ^vas  first  called  Ciilex  fasciatits,  which  was  changed  to 
Stegomyia  fasciatiis,  and  then  to  Stegomyia  calopus,  recently  expressed  as  Aedes 
calopus  by  Coquillett,  and  now,  Stegomyia  argentens. 

"This  constitutes  the  extrinsic  period  of  incubation,  in  contradistinction  to 
the  intrinsic  period  of  incubation,  that  is,  the  time  between  the  mosquito  bite 
and  the  onset  of  symptoms,  which  is  from  2  to  5  and  sometimes  6  days  in  this 
disease. 


296  mSECT-BORNE  DISEASES 

so  during  the  rest  of  its  life,  which  may  he  many  months.  Only  the 
female  mosquito  transmits  the  infection;  the  male  Stegomijia  calopus  is 
a  vegetarian;  its  prohoscis  is  too  soft  to  penetrate  the  skin.  A  single 
sting  of  a  single  infected  mosquito  is  sufficient  to  produce  the  disease. 
An.  infected  mosquito  may  infect  more  than  one  person  at  different 
times. 

The  prevention  and  control  of  yellow  fever  are  hased  upon  a  series 
of  epoch-making  investigations  and  discoveries  (1900-1902)  by  a  com- 
mission composed  of  Walter  Eeed,  James  Carroll,  Aristides  Agramonte, 
and  Jesse  W.  Lazear,  medical'  officers  of  the  United  States  Army.  These  ■ 
experiments  have  been  fully  confirmed,  and  in  some  respects  amplified, 
by  independent  workers,  namely,  Guiteras  of  Cuba  (1901)  ;  Elbos  of  Sao 
Paulo  (1901);  Barreto,  de  Barros,  and  Eodrigues,  of  Brazil  (1903); 
Eoss  (1902) ;  Parker,  Beyer,  and  Pothier  (1903)  ;  Eosenau,  Parker, 
Francis,  and  Beyer  (1904)  ;  Eosenau  and  Goldberger  (1906),  of  Amer- 
ica; Marchoux,  Salimbeni,  and  Simond  (1903)  ;  Marchoux  and  Simond 
(1906),  of  France;  and  Otto  and  Xeumann  (190-5),  of  Germany. 

Xoguchi  ^^  describes  a  spirochete  (Leptospira  icteroides),  which  he 
isolated  from  cases  of  fever  at  Guayaquil,  Lima  and  Merida,  as  the  cause 
of  yellow  fever.  It  closeh'  resembles  Leptospira  icteroliaemorrliagiae,  the 
cause  of  infectious  jaundice. 

The  virus,  is  "ultramicroscopic,"  that  is,  passes  the  close-grained  pores 
of  the  finest  porcelain  filter.  While  in  nature  the  disease  is  transmitted 
only  through  the  bite  of  an  infected  Stegomyia,  the  disease  may  be  trans- 
ferred experimentally  by  taking  some  of  the  blood  from  a  patient  during 
the  first  three  days  of  the  fever  and  injecting  it  into  a  susceptible  indi- 
vidual. So  far  as  is  known,  yellow  fever  is  peculiar  to  man — ^no  other 
animal  has  the  disease  naturally ;  Xoguchi,  however,  finds  the  Leptospira 
icteroides  pathogenic  for  guinea-pigs  and  rats.  At  one  time  it  was  gen- 
erally believed  that  yellow  fever  infection  was  conveyed  by  fomites. 
This  has  been  disproved,  and  we  now  know  that  there  is  no  danger  from 
soiled  clothing  or  other  inanimate  things,  even  though  stained  with  the 
black  vomit  and  other  discharges. 

The  diagnosis  of  yellow  fever  rests  upon  clinical  evidence  and  is  fre- 
quently difficult  to  make,  especially  in  the  early  stages.  It  is,  therefore, 
important  to  screen  all  cases  of  fever  in  a  yellow  fever  campaign  until 
the  nature  of  the  illness  is  established. 

Immunity. — There  is  no  natural  immunity  to  yellow  fever.  All  per- 
sons receiving  the  infection  for  the  first  time  seem  to  be  susceptible. 
Contrary  to  the  usual  statement,  there  is  no  racial  immunity  in  this  dis- 
ease; negroes,  Chinese,  Indians,  and  other  races  are  subject  to  it.  The 
disease  is,  however,  less  severe  in  negroes    than  in  whites.     One  attack 

^  Journ.  Exp.  Med.,  XXIX,  6,  June  1,  1919,  and  a  series  of  articles  in  the 
following  numbers. 


MOSQUITOES 


297 


of  yellow  fever  affords  protection  against  a  subsequent  attack.  The 
acquired  inniiuniiy  in  this  disease  is  one  of  the  strongest  knowri  and 
lasts  throughout  the  lifetime  of  the  individual.  Two  attacks  of  yellow 
fever  are  almost  unknown.  1  reported  a  sujiposod  instance  in  a  Span- 
iard in  Havana,  hut  tlic  diagnosis  of  tin-  Hist  allack  was  not  con- 
clusive. 

In  cndcmii-  areas  children  ot'U'ii  have  yellow  fever,  which  leaves  them 
immune  for  life.  The 
disease  often  runs  a  mild 
and  unrecognized  course 
in  children,  and  this  fact 
explains  the  supposed 
natural  immunity  of  na- 
tives in  endemic  foci. 

Noguchi  has  prepared 
a  serum  for  the  treat- 
ment and  a  vaccine  for 
the  prevention  of  yellow 
fever. 

The  Yellow  Fever 
Mosquito.  —  The  yellow 
fever  mosquito  has  a  wide 
distribution  ranging 
from  38  degrees  south  to 
38  degrees  north  latitude. 
They  are  found  in  the 
East  and  West  Indies, 
China;,  Sumatra,  Java, 
India,  Philippine  Islands, 
Japan,  Hawaiian  Islands, 
in  the  southern  part  of 
Italy,  Africa,  Spain, 
South  America,  etc. 
They  usually  prefer  the 
lowlands.  1  have  found  them  as  far  up  the  mountains  as  Orizaba  in 
Mexico,  4,200  feet  above  sea  level.  In  the  United  States  they  are 
very  prevalent  south  of  the  Potomac  along  the  gulf  coast,  but  are  absent 
or  rare  in  the  higher  elevations  of  Georgia  or  Alabama,  which  are,  there- 
fore, non-inf ectable  regions. 

The  yellow  fever  mosquito  is  a  domestic  insect.  It  breeds  by  pref- 
erence in  any  standing  water  about  the  household,  such  as  cisterns,  rain 
barrels,  or  any  collection  of  water  in  buckets,  bottles,  old  cans,  etc.  The 
yellow  fever  mosquito  does  not  breed  in  the  fields,  woods,  and  swamps, 
which  are  the  favorite  resorts  of  the  malarial  mosquito.    The  Stegomyia 


Fig.  23. — Stegomyia  Calopus   (fejiale 


298 


INSECT-BORNE  DISEASES 


mosquitoes  do  not  fly  far  of  their  own  volition,  but  show  a  cat-like  ten- 
dency to  remain  about  their  place  of  birth  or  adoption.  All  these  facts 
have  an  evident  bearing  upon  preventive  measures.  A  thorough  knowl- 
edge of  the  biology  of  the  mosquito  is  essential  to  the  success  of  a 
yellow  fever  campaign. 

It  is  important  to  remember  that  the  yellow  fever  mosquito  is  chiefly 
active  during  the  day  time.  It  cannot,  however,  distinguish  between 
artificial  light  and  sunlight.  I  have  vi^atched  Stegomyia  mosquitoes  bite 
me  by  electric  light  at  eleven  o'clock  at  night.  Its  attack  is  often  noise- 
less and  its  bite  painless.  However,  as  a  rule,  they  rest  at  night,  which, 

therefore,  diminishes  the  risk 
of  exposure  at  that  time^.  The 
Stegomyia  mosquito,  however, 
cannot  survive  for  long  in  the 
direct  rays  of  a  tropical  sun. 
There  is,  therefore,  little 
danger  in  visiting  a  commun- 
ity where  yellow  fever  is  epi- 
demic during  the  day  time, 
provided  the  person  keeps  out 
of  houses.  The  experiences 
during  the  last  yellow  fever 
epidemic  at  New  Orleans, 
1905,  showed  that  the  radius 
of  activity  of  an  infected 
Stegomyia  is  contracted.  It 
may  possibly  at  times  fly  across 
the  street,  but  it  is  evident 
that  it  neither  flies  far  nor  is  it  ordinarily  transported  to  any  great 
distance  on  railroad  cars,  although  it  may  be  carried  over  seas  on  ships. 
The  yellow  fever  mosquito  may  pass  a  screen  composed  of  16 
strands  or  15  meshes  to  the  inch,  but  cannot  pass  one  containing  20 
strands  or  19  meshes  to  the  inch.  Effective  screens  must,  therefore,  be 
at  least  this  fine. 

Stegomyia  calopus  is  a  grayish  mosquito  of  average  size  with  beauti- 
ful glistening  silver-white  markings.  These  markings  are  lyre-shaped 
on  the  back  of  the  thorax;  silver-white  spots  are  seen  on  the  side  of  the 
thorax.  White  lines  are  apparent  at  each  tarsal  joint  and  also  on  the 
palpi;  the  scutellum  is  white.  In  the  female  the  palpi  are  much  shorter 
than  the  proboscis,  which  at  once  distinguishes  it  from  Anopheles. 

Egg. — The  female  lays  her  eggs  on  the  surface  of  the  water  or  just 
above  the  water  line.  The  eggs  do  not  adhere  to  one  another,  and  hence 
do  not  form  the  compact  boat-shaped  mass  characteristic  of  the  culex, 
but  float  on  their  sides  more  or  less  singly.     At  the  moment  of  laying 


Fig.  24. — Head  of  Stegomyia  Calopus 

( MALE )  . 


MOSQUITOES 


299 


the  eggs  are  a  cream  color,  hut  rapidly  bccoiiic  jd  black.  They  are 
somewhat,  cigar-shajx'il,  and  measure  on  the  average  about  0.55  mm. 
in  lengtii  and  0.1  (i  mm.  in  width  at  the  broadest  part.  The  eggs  show 
marked  powers  of  resistance  to  unfavorable  influences.  They  may  be 
kept  dry  for  six  and  one-half  months,  and  still  retain  their  vitality, 
and  hatch  out  when  put  back  into  the  water.  Freezing  does  not  kill 
them.  The  egg  probably  plays  an  important  role  in  the  hibernation  of 
the  yellow  fever  mosquito.  The  winged  insect  may  also  survive  a  short 
winter.    Under  the  most  favorable  conditions  as  to  temperature  (30°  C.) 


Fig.  25. — Eggs  of  Steggmyia  Calopus. 


Stegomyia  eggs  hatch  out  in  about  36  hours  after  they  are  laid.    Under 
20°  C.  they  will  not  hatch  at  all. 

Larva. — The  egg  hatches  the  larva  ("wiggle-tail"),  which  has  a 
black  barrel-shaped  respiratory  siphon.  This  distinguishes  it  from  Culex 
fatigans,  its  common  messmate,  in  which  the  air  tube  is  brown,  longer, 
and  more  slender.  Although  the  larva  lives  in  the  water,  it  is  strictly 
an  air-breather  and  must  come  to  the  surface  for  air.  It  thrusts  its 
breathing  tube  up  into  the  surface  film  and  remains  suspended,  head 
down,  at  an  angle  of  somewhat  less  than  45  degrees,  which  distinguishes 
it  from  Anopheles  larvae,  which  lie  horizontal.  A  film  of  oil  on  the 
surface  of  the  water  is  sufficient  to  obstruct  the  air  tube  and  thus  cause 
the  death  of  the  larva  by  suffocation.  The  larva  is  very  timid,  so  that 
a  slight  jar  or  agitation  or  a  sudden  shadow  will  cause  it  to  wriggle 
rapidly  to  the  bottom,  where,  indeed,  it  may  very  commonly  be  observed 
to  feed.  The  duration  of  the  larval  stage  is  never  less  than  6  to  7 
days,  and  depends  upon  the  food  supply  and  temperature.     Under  un- 


300 


INSECT-BORNE  DISEASES 


favorable  conditions  it  may  be  prolonged  for  weeks.     Freezing  for  short 
periods  does  not  appear  to  injure  it. 

.  Pupa. — The  larva  changes  into  the  pupa.  The  pupa  is  not  provided 
with  a  mouth  and  does  not  feed.  It  is  an  air-breather  and  spends  most 
of  its  time  at  the  surface  of  the  water.  The  pupal  stage  lasts  at  least 
36  hours,  during  which  time  metamorphosis  occurs  into  the  imago  or 
perfect  winged  insect. 

Imago. — Under  the  most  favorable  conditions  it  is  at  least  9  days 
from  the  time  the  Stegomyia  lays  its  egg  to  the  appearance  of  the. 


Fig.  26. — Larva  of  Stegomyia  Calopus. 
Respiratory  Syphon  of  Culex  to  the  Right. 


imago.  Under  natural  conditions  the  length  of  life  of  the  adult  fe- 
male probably  varies  greatly.  Guiteras  succeeded  in  keeping  a  presum- 
ably infected  one  alive  for  154  days  during  the  fall  and  winter  temper- 
ature in  Havana.  Deprived  of  water,  it  does  not  usually  survive  longer 
than  3^  to  4  days,  and  only  very  exceptionally  5  days.  This  fact  has  a 
bearing  on  the  possibility  of  transporting  the  mosquito  in  band-boxes, 
trunks,  and  other  containers. 

"Aerial"  Conveyance. — It  is  notorious  that  yellow  fever  is  usually 
conveyed  but  a  short  distance  "aerially" — perhaps  across  the  street,  or, 
more  often,  to  a  neighboring  house  in  the  rear.  This  represents  a  dis- 
tance of  some  75  yards,  which  is  about  as  far  as  we  may  expect  it  to 
be  thus  conveyed,  from  our  knowledge  of  the  habits  and  flight  of  the 
Stegomyia  mosquito.  The  longest  distance  recorded  in  recent  years  of 
aerial  conveyance  is  one  of  225  meters   (Melier)   and  one  of  456  feet 


MOSQUITOES  .  301 

(Carter),  These  are  entirely  exceptional.  My  experience  in  the  deten- 
tion of  hundreds  of  susceptible  innnitjjrants  in  quarantine  for  days  in 
Havana  harbor  showed  that  infected  Stegoniyiae  do  not  travel  a  short 
distance  across  the  water.  This  observation  is  in  confirmation  of  others, 
that  vessels  moored  within  1,200  feet  off  the  shore  are  entirely  safe  so 
far  as  yellow  fever  is  concerned,  provided,  of  course,  personal  intercourse 
is  interdicted  or  sujiervised. 

Prevention. — The  ])rcvention  or  suppression  of  yellow  fever  may  be 
attacked  in  either  one  of  its  two  hosts,  man  oi'  insect.     If  every  person 


Fig.  27. — Pupa  of  Stegomyia  Calopus. 

developing  yellow  fever  were  immediately  isolated  from  the  Stegomyia 
mosquito,  the  disease  would  inevitably  cease.  The  elimination  of  the 
Stegomyia  mosquito  would  give  the  same  happy  result.  Usually  both 
methods  of  attack  are  employed.  It  would  seem  easier  to  control  the 
human  host  simply  by  screening  during  the  first  three  or  four  days 
of  the  fever.  Practically  this  method  has  been  found  insufficient,  be- 
cause the  disease  is  difficult  to  diagnose  in  the  early  stage,  and  the 
mild  cases  escape  attention.  The  essence  of  yellow  fever  prevention, 
therefore,  consists  in:  (1)  screening  cases  of  yellow  fever  and  all  sus- 
pected cases  of  yellow  fever;  (2)  destruction  of  infected  insects;  (3) 
the  suppression  of  Stegoniyiae  through  the  control  of  their  breeding 
places.  It  is  a  combination  of  these  three  methods  which  was  first 
so  brilliantly  carried  out  by  Gorgas  in  Havana  in  1901,  and  later 
in  Panama;  by   White  in  New   Orleans,   1905;   by   Liceaga  in   A'^era 


303  -  INSECT-BORNE  DISEASES 

Cruz,    and   recently   by    Oswaklo    Cruz    in    Rio    de    Janeiro,    in    1909. 

Yellow  fever  patients  should  be  isolated  only  in  the  sense  of  separat- 
ing them  from  Stegomy'm  ailopus.  This  may  be  done  by  proper  screen- 
ing. It  is  not  necessary  to  remove  the  patient  to  a  hospital,  although 
this  is  desirable,  for  the  reason  that  a  special  hospital  is  more  carefully 
guarded  than  is  practicable  in  a  private  house,  and  the  trained  assistants 
are  an  additional  safeguard.  As  soon  as  the  patient  is  removed,  the 
mosquitoes  in  the  house  and  the  surrounding  houses  should  at  once  be 
destroyed.  YeUow  fever  patients  must  be  moved  with  caution,  for  the 
reason  that  undue  excitement  or  exertion  seems  to  increase  the  severity 
of  the  disease. 

The  insecticides  best  suited  for  the  destruction  of  mosquitoes  are: 
sulphur  dioxid,  hydrocyanic  acid  gas,  pyrethrum  powder,  tobacco  smoke, 
Mini's  culicide  (camphor  and  phenol).  See  page  281.  At  first  glance 
it  might  appear  to  be  a  hopeless  task  to  attempt  to  eradicate  the  yel- 
low fever  mosquito  in  a  large  city,  but  that  this  is  possible  was  demon- 
strated in  New  Orleans  in  1905,  when,  after  several  months  of  a  vigorous 
campaign,  it  was  difficult  to  find  a  Stegomyia  mosquito.  The  measures 
consisted  mainly  in  screening  the  water  cisterns  and  eliminating  all 
standing  collections  of  water  in  and  about  the  household.  Yellow  fever 
tends  to  die  out  in  a  city  with  a  stationary  population;  in  other  words, 
it  burns  itself  out.  An  important  measure  of  prevention,  therefore, 
consists  in  controlling  immigration  and  travel  into  an  endemic  center 
so  as  to  give  it  a  chance  to  cleanse  itself  through  the  elimination  of 
susceptible  material. 

Maritime  quarantine  for  yelloAv  fever,  see  page  507. 

References. — Dr.  Charles  J.  Einlay  studied  the  relation  of  the  mos- 
quito to  yellow  fever  as  far  back  as  1883  and  1883.  The  first  in- 
sects used  by  the  United  States  Army  Commission  to  bring  about  the 
demonstration  of  the  new  doctrine  were  received  from  the  hands  of  Dr. 
Finlay.  Finlay  believed  that  the  cause  of  the  disease  was  a  micrococcus 
and  considered  that  the  insects  were  capable  of  transmitting  the  infection 
a  few  days  after  they  had  stung  a  yellow  fever  patient.  Sternberg's 
studies  upon  yellow  fever  are  published  by  the  Government  as  a  report 
of  the  United  States  Marine  Hospital  Service  on  the  Etiology  and 
Prevention  of  Yellow  Fever,  1890.  Carter's  observations  at  Orwood, 
Mississippi,  upon  the  extrinsic  period  of  incubation  were  published  in 
N.  0.  Med.  and  Surg.  Jour.,  May,  1900,  and  the  Medical  Record,  June 
15,  1901. 

The  work  of  the  United  States  Army  Commission  appeared  in  the 
following  publications : 

"The  Etiology  of  Yellow  Fever — a  Preliminary  Note,"  Proceedings 
of  the  28th  Annual  Meeting  of  the  Am.  Pub.  Health  Assn.,  Oct.  22-26, 
1900;  also  Pliiladelpliia  Med.  Jour.,  Oct.  27,  1900. 


MOSQUITOES  303 

"The  Etiolog}'  of  Yellow  Fever— An  Ad.litioiiiil  Note,"  ,/.  ,1.  M.  A., 
Feb.  16,  1901. 

"Experimenlal  ^■(■ll()u■  Fever,"  .1///.  Med.  Juitr..  .Inly  (i,  li>Ol. 

"Etiology  of  ^■('llo\v  Fever — Sii|)|)lcni('iital  Xolc,"  .1///.  Med.  Jour., 
Feb.  22,  1902. 

A  series  of  artiik's  by  Xogiu'hi,  (Ic'scribing  JA'plospira  icteroide.s;  ap- 
]H';ire(l  in  llic  ■/itiinidl  of  /•j.r/iiTimcnhtl  Medicine,  .liiiu^  1,  IDl'.t,  A'ol.  oO, 
No.  5,  and  siiccoiMliiii;-  numlicrs. 

Prevention  of  Malaria  and  Yellow  Fever  Contrasted. — For  the  pre- 
vention of  niabuia  the  same  principles  guide  us  that  have  been  set 
forth  for  the  prevention  of  yellow  fever.  In  practical  application,  how- 
ever, our  methods  of  attack  differ,  owing  to  differences  in  the  habits  of 
the  two  mosquitoes,  and  owing  to  differences  in  the  two  diseases.  The 
malarial  problem  is  much  more  difficult,  because  it  is  harder  to  get  rid 
of  Anopheles  than  of  Stegomyia.  The  breeding  places  of  the  yellow 
fever  mosquito  are  practically  confined  to  artificial  containers  in  the' 
neighborhood  of  human  habitations,  "^vhile  those  of  Anopheles  are  found 
in  marshes,  pools,  or  streams,  and  often  in  collections  of  water  in  the 
grass  or  brush.  The  breeding  places  of  the  malarial  mosquito  cover  a 
much  larger  area,  frequently  the  whole  country,  and  are  rather  hard 
to  find  and  difficult  to  destroy;  also  this  insect  travels  much  farther 
from  its  breeding  place  than  the  Stegomyia.  Compared  with  yellow  fever, 
the  control  of  the  malarial  human  host  presents  special  difficulties.  In 
yellow  fever  man  is  infective  to  the  Stegomyia  only  three  days;  in  ma- 
laria the  parasites  continue  in  the  circulating  blood  a  very  long  time.  In 
the  case  of  malaria,  then,  we  have  to  deal  with  chronic  carriers,  which, 
fortunately  for  us,  does  not  occur  in  yellow  fever.  For  malaria  we  have 
quinin  as  a  prophylactic,  whereas  no  known  drug  will  prevent  yellow 
fever. 

DENGUE 

Dengue  is  an  acute  specific  febrile  infection,  characterized  by  pains 
in  the  joints  and  muscles  and  a  variable  eruption.  It  is  popularly  called 
hrmh  lone  fever  in  the  south  on  account  of  the  atrocious  character  of 
the  pain,  and  dandy  fever,  from  the  stiff  and  dandified  gait.  It  occurs 
only  in  tropical  and  subtropical  regions  where  Stegomyia  mosquitoes 
abound. 

All  who  visit  the  tropics  or  subtropical  countries  where  dengue  pre- 
vails are  very  apt  sooner  or  later  to  contract  this  infection.  So  far  as 
known,  few  persons  have  ever  died  of  dengue.  Although  the  mortality 
is  practically  nil,  the  disease  is  a  painful  affection  and  sometimes  leaves 
the  body  in  a  weakened  condition  for  long  periods  of  time.  In  its 
epidemiology  and  symptomatology  the  disease  strikingly  parallels  yellow, 
fever,  which  adds  to  its  importance.     Outbreaks  of  dengue  may  precede 


304  INSECT-BOENE  DISEASES 

and  may  be  coincident  with  those  of  yellow  fever.  In  the  tropics  influ- 
enza and  dengue  are  also  frequently  confused.  Dengue  also  has  some 
resemblance  to  the  three-day  fever  or  pappataci  fever  of  Herzegovina, 
which  is  transmitted  by  the  bite  of  the  Phlebotomus  papaiassii,  a  biting 
fly.  Outbreaks  of  dengue  occur  with  explosive  violence,  attacking  almost 
everyone  in  the  community  during  a  brief  period.  In  this  respect,  the 
epidemiology  of  dengue  and  influenza  are  strikingly  similar.  No  other 
disease  attacks  such  a  large  proportion  of  the  population  in  a  short 
time. 

There  is  no  permanent  immunity  produced  by  an  attack  of  dengue. 
Persons  often  give  a  histor}^  of  an  attack  in  each  outbreak.  The  cause 
of  the  disease  is  not  known. 

Graham  studied  dengue  in  Beirut,  Syria,  and  described  a  protozoon 
inhabiting  the  red  blood  corpuscles  and  closely  resembling  the  Plasmo- 
dium of  malaria  except  for  the  absence  of  pigment. ^^  Graham  believed 
that  this  organism  undergoes  a  developmental  stage  within  the  mos- 
quito (Culex  fatigans).  He  claimed  to  have  observed  the  spores  of  this 
organism  "in  among  the  cells  of  the  salivary  glands"  after  48  hours  in 
mosquitoes  which  had  bitten  a  dengue  patient  upon  the  fourth  day  of 
the  disease.  Graham  produced  a  very  severe  case  of  fever  resembling 
dengue  by  inoculating  a  man  subcutaneously  with  peptonized  normal 
salt  solution  containing  the  salivary  glands  of  a  mosquito  which  had 
bitten  a  dengue  patient  24  hours  before.  Graham's  observations  con- 
cerning the  parasite  in  the  blood  and  in  the  mosquito  have  not  been 
confirmed,  although  the  subject  has  been  studied  by  several  experienced 
microscopists.  Carpenter  and  Sutton,^*  however,  obtained  two  positive 
results  out  of  four  experimental  cases  of  mosquito  inoculation.  The 
period  of  incubation  in  one  of  these,  however,  was  two  weeks,  and  the 
subjects  were  not  sufficiently  r-ontrolled  to  exclude  the  bites  of  other  mos- 
quitoes. Agramonte  ^^  studied  an  epidemic  in  Havana  which  was  ac- 
companied by  a  plague  of  Culex  fatigans.  He  attempted  to  transmit 
the  disease  by  mosquitoes,  trying  various  species  at  various  intervals 
after  the  insects  had  fed  upon  dengue  patients,  but  did  not  succeed  in 
producing  the  disease  in  this  way.  Guiteras  and  Finlay  ^^  endeavored 
to  transmit  the  disease  with  Culex  pipiens,  but  with  negative  results. 
Guiteras,  Finlay,  Agramonte,  and  others  who  have  worked  upon  this 
subject  state  that  their  faith  remains  unshaken  that  the  mosquito  acts 
as  the  vector  of  dengue,  despite  the  negative  results  of  their  experi- 
ments. 

Graham,-'^  in  1903,  tried  a  few  experiments  which  seemed  to  show 

"^Joiir.  Trop,  Med.,  1903,  Vol.  VI,  p.  209. 

"^Joiir.  A.  M.  A.,  1905,  XLIV. 

''^Neic  York  Med.  Jour.,  1906,  LXXXIV. 

'^Rev.  Med.  Trop.,  1906,  Vol.  VII,  p.  53. 

'"Journ.  Trop.  Med.,  July  1,  1903,  Vol.  VI,  p.  209. 


MOSQUITOES  305 

that  Culex  fatigans  is  able  to  convey  the  infection  of  dengue  fever.  He 
admits,  howe\cr,  that  in  many,  jx-rhaps  in  all,  of  his  experiments,  Stego- 
myia  fasciata  wore  present  amongst  his  mosquitoes.  While  he  demon- 
strated that  mosquitoes  can  carry  the  disease,  the  variety  remained  in 
doubt.  Bancroft,-'*  in  1905,  transmitted  dengue  in  two  apparently  suc- 
cessful cases  which  were  bitten  b}'^  Stegomyia  fascwta,  12  and  10  days 
after  they  had  bitten  dcngne  patients,  but  failed  when  the  period  was 
longer.  Bancroft  worked  in  an  infected  district,  and  his  results  are 
not  convincing.  Ashburn  and  Craig,-^  in  1907,  reported  one  doubtful 
case  in  nine  persons  bitten  by  Culex  fatigans,  suggesting  the  possibility 
of  that  species  being  a  vector  of  dengue.  Cleland,  Bradley  and  Mc- 
Donald,^" in  1916,  reproduced  the  disease  in  four  out  of  seven  persons 
on  whom  biting  experiments  were  conducted  with  Stegomyia  fasciata 
mosquitoes  caught  in  a  dengue-infected  district  in  the  surroundings  of 
cases  of  the  disease,  and  some  of  them  known  to  have  fed  on  a  dengue 
patient  on  the  first  and  second  days  of  his  illness,  and  then  transported 
to  a  non-dengue  district.  The  incubation  period  of  the  four  cases  was 
found  to  be  between  five  and  nine  and  one-half  days.  The  disease  did 
not  spread  from  any  of  the  above  cases.  Experiments  with  Culex  fati- 
gans were  negative.  The  blood  taken  from  the  experimental  cases  when 
injected  into  further  persons  reproduced  the  disease. 

All  our  preventive  measures  are  now  based  upon  the  supposition  that 
dengue  is  a  mosquito-borne  infection.  An  instance  showing  the  non- 
contagiousness  of  dengue  is  given  by  Persons,  U.  S.  N. :  A  squad  of 
marines  from  the  U.  S.  S.  Baltimore  were  given  shore  leave  at  Cavite. 
Twenty  of  the  24:  marines  who  had  been  ashore  came  down  with  the 
disease  after  returning  to  the  ship,  while  there  was  a  total  absence  of 
infection  among  those  who  had  remained  aboard.  Observations  made 
at  the  Naval  Hospital  at  Canacao  demonstrated  that  in  the  mosquito- 
free  wards  the  disease  did  not  spread,  whereas  when  the  hospital  was 
located  at  Cavite  it  was  noted  that  practically  every  case  admitted 
became  infected  with  dengue  while  under  treatment  for  the  original 
complaint  (Stitt). 

FILABIA8I8 

The  filaria  is  a  long,  slender  filiform  threadworm  with  a  curved  or 
spiral  tail.  The  adult  worms  live  in  the  connective  tissue,  lymphatics, 
and  body  cavities.  The  embryos  or  larvae  are  found  in  great  numbers 
in  the  blood.  In  several  species  of  which  the  life  history  is  known  mos- 
quitoes act  as  the  intermediate  host.  The  most  important  filariae  of  man 
are:      (1)   Filaria  hancrofti,  the  larva  of  which  is  known  as  Filaria 

"^  Austral.  Med.  Gaz.,  Jan.  1906,  p.  17. 

""  Philippine  Journ.  Sci..  II.  2,  p.  93,  May,  1907;  also  Craig,  J.  A.  M.  A., 
Vol.  75,  IS.  p.  1171.     Oct.  :jn.  1920. 

^^  Med.  Journ.  of  Austral.  Sept.  2,  1916.  p.  179;  Sept.  9,  1916.  p.  200. 


306  mSECT-BOENE  DISEASES 

nocturna,  appearing  in  the  blood  at  night  and  occurring  in  all  tropical 
lands,  including  America;  (2)  Filaria  loa,  the  larva  of  which  is  known 
as  Microfilaria,  diurna  occurring  in  the  blood  by  day  and  prevalent  in 
West  Africa  and  India;  (3)  the  Microfilaria  perstans,  the  larva  of 
which  is  known  as  Filaria  perstans,  which  persists  in  the  blood  both  day 
and  night,  and  occurs  especially  in  West  Africa  and  a  number  of  other 
places.  None  of  these  young  worms  do  any  appreciable  injury  in  the 
blood;  of  the  adult  worms, -only  one,  namely,  Filaria  hancrofti,  can  be 
viewed  as  serious,  causing  elephantiasis,  dryluria,  etc.,  Avhiie  the  second 
species,  Filaria  loa  is  more  or  less  troublesome.  According  to  Manson, 
we  are  hardly  justified  at  present  in  assuming  that  all  the  other  species 
are  entirely  without  elfect  upon  their  hosts.  These  parasites  infect  man 
throughout  the  tropical  and  subtropical  belt.  In  the  United  States 
the  infection,  while  not  very  prevalent,  is  endemic  in  Charleston.  Fran- 
cis ^^  finds  that  Charleston,  South  Carolina,  is  the  only  city  in  the  United 
States  showing  a  considerable  number  of  human  infestations.  Charles- 
ton, it  is  believed,  was  infected  from  a  shipload  of  slaves  many  years 
ago. 

According  to  Manson,  Culex  fatigans,  and,  according  to  James,  the 
Anopheles  nigerrinus,  are  the  intermediate  hosts.  Francis  confirms  the 
Cnlex.  fatigans  as  the  usual  host  of  Filaria  .hancrofti.  Development 
probably  takes  place  in  many  species  of  culicines  and  anopheliues.  When 
fed  on  the  blood  of  a  filarial-infested  individual,  it  is  found  that  the 
filarial  larvae  soon  escape  from  their  sheaths  in  the  thickened  blood 
within  the  stomach  of  the  mosquito.  They  pierce  the  stomach  wall, 
enter  the  thoracic  imiscles  of  the  insect,  pass  through  a  metamorphosis 
which  takes  from  16  to  20  days  (longer  or  shorter,  according  to  atmos- 
pheric temperature)  ;  they  now  quit  the  thorax  and  a  few  find  their  way 
to  the  abdomen;  the  vast  majority,  however,  pass  forward  through  the 
prothorax  and  neck,  and,  entering  the  head,  coil  themselves  up  close  to 
the  base  of  the  proboscis  and  beneath  the  pharynx  and  under  surface  of 
the  cephalic  ganglia.  This  account  is  taken  from  Manson,  to  whose 
personal  interest  in  this  disease  we  are  indebted  for  the  advances  in  our 
knowledge  of  the  entire  subject  of  filariasis.  The  wonderful  preparations 
of  Low  may  be  seen  at  the  London  School  of  Tropical  Medicine,^^  show- 
ing the  Filaria  nocturna  in  the  head  and  proboscis  of  the  mosquito 
ready  to  come  out  when  the  proboscis  of  the  insect  pierces  its  victim. 
The  fact  that  the  mosquito  is  the  intermediate  host  in  conveying  the  in- 
fection of  Filaria  rests  upon  these  observations  and  not  upon  experi- 
ments which  demonstrate  the  actual  transference  of  the  disease.  Whether 
the  worm  may  obtain  an  entrance  by  any  other  channel  or  medium 

^^  Hygienic  Lab(yratory  Bull.  No.  117,  1919. 

^^  In  this  country  the  convincins:  preparations  of  Edward  Francis  are  illus- 
trated in  Hyg.  Lab.  Bull.  No.  117,  V.  S.  Public  Health  Service,  June,  1919. 


FLIES 


307 


would,  according  to  ^lanson,  he  hard  to  prove  and  rash  to  deny.  Our 
correct  preventive  measures  are  l)ased  upon  the  theory  tliat  tliis  is  an 
insect-borne  disease,  althoui^di  other  possii)le  modes  of  transference  must 
not  be  neglected.  Pro])hyla.\is,  therefore,  dej)ends  upon  tlie  suppres- 
sion of  the  mosquito  and  the  prevention  of  the  infective  mosquito-bite. 
As  it  is  not  definitely  known  how  many  species  of  mosquitoes  convey 
the  infection,  the  preventive  measures  must  be  along  general  lines;  a 
combination  of  those  described  under  malaria  and  yellow  fever,  as  well 
as  general  sanitation  and  personal  hygiene. 


FLIES 

The  true  flies  have  but  two  wings,  that  is,  they  belong  to  the  order 
Diptera.  They  comprise  an  enormous  number  of  species.  Contrary  to 
popular  opinion,  flies  are  poor  scavengers.  Most  flies  prefer  the  sun- 
shine, but  species  vary  greatly  in  their  habits  and  breeding  places. 
However,  surprisingly  little  is  known  of  the  life  history  and  habits  of 
most  flies.  The  subject  lacks 
attraction — especially  the  mag- 
gots or  larval  stage.  The  life 
history  of  the  house  fly  in  gen- 
eral was,  down  to  1873,  men- 
tioned in  only  three  Europeaii 
works,  and  few  exact  facts  were 
given.  Dr.  A.  S.  Packard,  then 
of  Salem,  Mass.,  studied  the 
house  fly  and  gave  descriptions 
of  ^11  its  stages,  showing  that 
the  growth  of  a  generation  from 
the   egg  to   the   adult   occupies 

from  10  to  14  days.  In  1895  Howard  further  traced  the  life  history  and 
indicated  that  about  120  eggs  are  laid  by  a  single  female  at  one  time  and 
that  a  generation  is  produced  every  10  days  at  the  summer  tempera- 
tures of  Washington.  There  may  be,  therefore,  12  generations  in  a 
summer.  If  each  female  lays  only  120  eggs  (four  such  batches  may 
be  laid)  we  have  the  possibility  of  countless  millions  coming  from  a 
single  fly  during  a  single  season.  Allowing  2,880  flies  to  the  ounce,  it 
has  been  estimated  that  the  total  product  of  a  single  fly  in  10  days 
would  equal  810  pounds,  provided  only  one-half  of  them  survived; 
hence,  tlie  logical  time  to  begin  fly  suppression  is  in  the  early 
spring. 

Flies  transmit  disease  in  one  of  several  ways.  The  biting  flies,  such 
as  the  tsetse  flies^  which  transmit  sleeping  sickness,  inoculate  the  try- 
panosome  directly  into  the  system  by  piercing  the  skin  with  their  mouth 


Fig.  28. — House  Fly  (Musca  domestica) , 
Showing  Proboscis  in  the  Act  of 
Eating  Sugar. 


308  INSECT-BORNE  DISEASES 

parts.  Biting  flies,  such  as  the  Stomoxys  caldtrans,  abound  in  the 
United  States  in  stables,  houses,  and  also  in  nature.  They  have  been 
implicated  as  go-betweens  in  anthrax,  relapsing  fever,  horse  sickness 
(Pferdesterbe),  and  epithelioma  of  fowls  and  other  infections.     Other 


Fig.  29. — Eggs  of  House  Fly  as  Laid  ix  a  Mass. 

blood-sucking  genera,  such  us  Tabanus,  CJirysops,  Haematohia,  etc.,  are 
of  common  occurrence,  but  are  not  known  to  carry  any  infection  regn- 
larly.  The  common  house  fly  does  not  bite.  These  and  other  non- 
biting  flies  transmit  diseases  by  mechanical  transfer  of  bacteria  on  the 
surface  of  their  bodies,  or  by  contaminating  foodstuffs,  etc.,  with  their 
excreta  or  vomit. 

The  following  brief  account  of  the  common  house  fly  may  be  taken 


Fig.  .30. — Eggs  of  House.  Fly.    Some  have  hatched. 

as  a  type  of  the  life  history  and  habits  of  flies  in  general.  Eemedies 
and  preventive  measures  depend  upon  the  peculiarities  in  the  life  his- 
tory and  habits  of  each  particular  genus  and  species. 


FLIES 


309 


Life  History  of  the  Musca  Domestica. — The  eggs  of  the  common 
house  fly  are  usually  laid  in  masses  (Fig.  29)  in  certain  favorai)le  spots, 
each  mass  beini?  the  result  of  deposition  by  several  females.  In  6  to  8 
hours  the  eiigs  hatih  into  larvae  (maggots),  which  grow  rapidly  and  are 
fully  developed  in  4  or  5  days.     Kach  larva  then  becomes  a  pupa  in  a 


Fig.  .31. — -Larvae  of  House  Fly. 

hard  brown  case — the  puparium.  In  5  days  more  the  pupal  case  opens 
and  the  adult  fly  appears  for  a  season  of  activity  covering  several  weeks. 
It  takes  about  10  days  from  egg  to  imago.  Most  of  them  die  in  the 
early  autumn,  in  great  part  due  to  a  fungus  disease,  caused  by  Empusa 
muscae  which  becomes  prevalent 
among  the  flies  at  this  season  of 
the  year.  Those  remaining  out 
of  doors  are  killed  by  the  first 
cold  nights,  those  which  find  their 
way  into  heated  buildings  gradu- 
ally die  out.  and  there  is  no  evi- 
dence that  hibernation  of  adult 
flies  occurs.  They  overwinter  as 
larvae  or  pupae  in  manure  heaps 
or  beneath  the  soil.  It  is  pos- 
sible for  flies  to  continue  breed- 
ing throughout  the  winter  in 
heated  locations  such  as  animal 
houses  and  the  like,  where  food 
andbreedingmaterialsarepresent. 


Fig.  .32. — Pcparkm  of  House  Flt. 


The  chief  breeding  place  of  common  house  flies  is  in  horse  manure. 
They  also  have  been  found  to  breed  in  human  excrement,  fermenting 
vegetable  and  putrefying  animal  matter,  in  the  bedding  in  poultry  pens, 
in  refuse  hog  hair,  in  tallow  vats,  in  carcasses  of  various  animals,  and  in 


310 


INSECT-BOR^^E  DISEASES 


garbage  and  organic  material  of  all  kinds :     All  of  which  means  that  if 
we  allow  the  accumulation  of  filth  we  will  have  house  flies. 

The  larvae  of  house  flies  have  a  tendency  to  crawl  away  from  their 
breeding  places;  many  of  them  burrow  into  the  loose  ground  just  beneath 
the  manure  piles,  or  crawl  under  boards  or  stones,  or  into  dry  manure 


Fig.   33. — Stable   Fly    (Stomoscys   calcitrans} .     After   Brues. 


collected  under  platforms  or  the  like.  This  tendency  of  migrating 
appears  three  or  four  days  before  pupating.  The  larvae  leave  the  moist 
manure  for  a  dry,  dark  place.  This  migrating  habit  is  of  great  advan- 
tage to  the  winged  fly,  at  the  time  of  emergence,  as  it  afiiords  an  easy 
path  to  freedom.  Advantage  may  be  taken  of  this  migrating  habit  to 
trap  many  larvae.  They  can  be  made  to  leave  the  manure  if  it  is  kept 
moist,  and  can  be  trapped  and  drowned  in  a  box 
or  tray  partly  filled  with  water. 

Life  History  of  Stomoxys  Calcitrans. — Stom- 
oxys  calcitrans,  the  biting  stable  fly,  is  very 
similar  to  the  house  fly  in  its  life  history  and  in 
appearance  during  the  preparatory  stages,  but  de- 
velops more  slowly,  requiring  nearly  a  month  to 
undergo  a  complete  life  cycle.  The  eggs  are  laid 
like  those  of  the  house  fly  in  horse  manure,  but 
more  frequently  in  fermenting  heaps  of  grass, 
cow-dung,  brewer's  refuse  ("spent  hops"),  etc. 
The  adult  flies  are  much  like  the  house  fly,  but 
have  a  sharp,  needle-like  proboscis.  They  feed  exclusively  on  mammalian 
blood  and  are  a  great  annoyance  to  horses  and  cattle  in  late  summer 
and  autumn.  They  bite  persons  less  frequently,  but  are  of  importance 
on  account  of  their  possible  relation  to  transmitting  infections.  The 
stable  fly  can  best  be  controlled  by  eliminating  its  breeding  places. 


Fig.  34. — Head  Show- 
ing Proboscis 
(Stomoxys  calcit- 
rans ) .    After  Brues. 


FLIES 


311 


Flies  as  Mechanical  Carriers  of  Infection. — Leidy  in  1864  attributed 
the  spread  of  gangrene  in  li()S|)il;ils  during  the  Civil  War  to  the  agency 
of  the  house  fly.  Shortly  thereafter  it  wa.-^  discovered  that  the  bite  of  the 
gad-fly  may  transmit  anthrax  from  cattle  to  man.  Later  it  was  found 
that  purulent  oplitliahnia  of  tho  Egyptians  is  carried  by  the  house  fly, 
and  the  spread  of  an  infectious  conjunctivitis  known  as  "pink  eye"  in 
the  South  has  been  shown  by  Hubbard  to  be  facilitated  by  little  midges 
of  the  genus  Hippelates.  Reference  has  already  been  made  to  the  bite 
of  the  tsetse  flies  in  spreading  nagana,  sleeping  sickness,  and  other  try- 
panosomatic  infections.  Recently  the  stable  fly  has  been  shown  to  be 
able  to  transmit  various  infections  in  a  mechanical  way. 

It  is  now  known  that  typhoid  fever  and  other  intestinal  infections  may 
be  transmitted  by  the  common  house  fly.  Celli  in  1888  fed  flies  with 
pure  cultures  of  typhoid,  tuberculosis  and  anthrax,  and  showed  that  the 
virulent  bacilli  were  passed  in  the  dejecta.     Kober  in  1892  was  one  of 


Fig.  :5.3. — \^'I.\G  op'  Stable  Fly  (Stomoxys  calcitraus) . 

the  first  to  call  special  attention  to  the  danger  of  contaminating  food 
supplies  by  flies  coming  from  the  excreta  of  typhoid  patients.  The 
Lnited  States  Army  Commission — Reed,  Yaughan.  and  Shakespeare  ^^ 
—studied  the  presence  of  typhoid  fever  in  our  camps  during  the  Span- 
i.;h-American  War  in  the  summer  of  1898.  They  concluded  that  flies 
undoubtedly  serve  as  carriers  of  the  infection.  "Flies  swarm  over  in- 
fected fecal  matter  in  the  pits  and  then  deposit  it  and  feed  upon  the 
food  prepared  for  the  soldiers  at  the  mess  tents.  In  some  instances, 
where  lime  had  recently  been  sprinkled  over  the  contents  of  the  pits,  flies 
with  their  feet  whitened  with  lime  w^ere  seen  walking  over  the  food."  ^* 
Vaughan  subsequently  stated  that  he  considered  that  about  15  per  cent, 
of  the  cases  of  typhoid  in  the  camps  were  caused  by  fly  transmission. 

Alice  Hamilton  ^^  isolated  typhoid  bacilli  from  5  out  of  18  house  flies 
captured  in  Chicago  in  the  privies  and  fence  near  a  sick  room  during  a 
local  water-borne  outbreak.    It  has  been  shown  experimentally  that  living 

^Rep.  on  Origin  and  Spread  of  Tvphoid  Fever  in  U.  S.  Military  Camps  in 
Spanish  War  of  1898,  1904. 

^'Am.  Journ.  Med.  Sci.,  1899,  CXVIII,  10. 
"^Jour.  A.  M.  A.,  1903,  XL,  40,  p.  .576. 


312 


INSECT-BOE^TE  DISEASES 


typhoid  bacilli  may  remain  in  or  upon  the  bodies  of  flies  a  long  time. 
Ticker  ^^  isolated  B.  typhosus  from  flies  from  a  house  in  which  there 
were  8  cases  of  typhoid  fever.  He  further  proved  by  experimentation 
that  flies  fed  on  typhoid  bacilli  transmitted  the  microorganism  23  days 
after  feeding.  Klein,"  Faichnie,^^  Graham  Smith/^  Bertarelli/"  and 
others  also  isolated  B.  typhosus  from  flies  kept  in  nature,  but  in  prox- 
imity to  the  infection.  Howard  studied  fly  abundance  in  relation  to  the 
origin  and  prevalence  of  typhoid  fever  in  the  District  of  Columbia  in 
the  summer  of  1908.^^  No  particular  correlation  between  the  prevalence 
of  the  flies  and  the  prevalence  of  the  disease  could  be  made  out. 

Flies  undoubtedly 
spread  the  infection  of 
typhoid  fever,  but  the  im- 
portance of  the  role  they 
play  in  this  regard  varies 
considerably  with  circum- 
stances. In  camps,  un- 
sewered  towns,  and  over- 
crowded places  in  poor 
sanitary  condition  the 
danger  from  flies  may  be 
considerable,  but  even 
under  the  worst  condi- 
tions it  is  doubtful 
whether  flies  ever  play  the  major  role  or  are  responsible  for  the  bulk 
of  typhoid  fever,  as  has  been  stated.  In  a  well-sewered  city,  such  as 
Washington,  we  concluded  that  the  flies  are  probably  responsible  but  for 
an  occasional  case  of  the  disease.  It  is  very  difficult  in  any  particular 
instance  to  know  quantitatively  just  how  much  of  the  infection  is  con- 
veyed by  flies  and  how  nrnch  by  contacts.  The  danger  of  flies  is  great 
enough  without  the  need  of  exaggeration,  and  their  suppression  fully 
justifies  the  best  energies  of  the  health  officer.  It  is  perhaps  a  mistake 
to  call  the  common  house  fly  the  "typhoid  fly,"  not  alone  for  the  reason 
that  the  disease  is  spread  in  many  other  ways,  but  for  the  reason  that 
the  fly  is  responsible  for  the  spread  of  many  infections  other  than  typhoid 
fever.  Flies  undoubtedly  play  the  same  role  in  dysentery,  cholera,  and 
all  other  intestinal  infections  that  they  do  in  typhoid  fever.  Tizzoni 
and  Cattani  in  1896  demonstrated  active  cholera  organisms  in  the  de- 
jecta of  flies  caught  in  the  cholera  colonies  of  Bologna,  Italy.     These 

^"Arch.  f.  Hyg.,  1903,  XLVI,  275. 
^''Brit.  Med.  Journ.,  1908,  II,  1150. 
'■  '^  Journ.  Roy.  Army  Med.  Corps,  1909,  XIII,  580,  672. 
.  ,  3«Eep.  Loc.  Govt.  Bd.,  London,  1910,  No.  40, 
'    ^''Cent.  f.  Bakt.,  1910.  LIII,  486. 

*^Rosenau,  Lumsden,  and  Kastle:     Report  No.  3,  1908,  P.  H.  and  M.  H.  S., 
Hygienic  Laboratory  Bull.  No.  52. 


J?IG.  36.- 


-The  "Little  House  Fly"   {Homalomyia 
canicularis  ^.     After  Hewitt. 


FLIES 


313 


observations  were  subsequently  verified  and  extended  by  Simonds,  Offel- 
man,  McRae,  and  otbcrs. 

It  is  quite  evident  that  ilies  lighting  upon  a  case  of  smallpox, 
measles,  scarlet  fever,  and  other  exantheniatous  disease  may  very  readily 
transmit  these  infections  to  another  person.  I  have  actually  seen  mag- 
gots breeding  in  the  o})en  lesions  of  a  case  of  smallpox  treated  in  huts 
at  Eagle  Pass,  Texas. 

Flies  may,  in  the  same  mechanical  way,  transmit  the  infection  of 
erysipelas,  anthrax,  glanders,  and  other  skin  infections.  It  is  known 
that  flies  may  ingest  tuberculous  sputum  and  excrete  tubercle  bacilli 
which  may  remain  virulent  as  long  as  15  days.  Flies  have  also  been 
associated  with  leprosy  and  many  other  diseases. 


Fig.  37.-^Wikg  of  House  Fly,  Showing  How  It  Carries  Dust  Particles. 


Esten  and  Mason  *-  counted  the  bacterial  population  of  415  flies  and 
found  that  the  number  of  bacteria  on  a  single  fly  may  range  all  the 
Avay  from  550  to  6,600,000.  Early  in  the  fly  season  the  numbers  of 
bacteria  on  flies  are  comparatively  small,  while  later  the  numbers  are 
very  large.  The  places  where  flies  live  also  determine  largely  the  num- 
ber of  bacteria  they  carry.  The  average  of  the  415  flies  was  about  one 
'and  one-quarter  million  bacteria.  The  method  of  the  experiment  was 
to  introduce  the  flies  into  a  sterile  bottle  and  pour  into  the  bottle  a 
known  quantity  of  sterilized  water,  then  shake  the  bottle  to  wash  the 
bacteria  from  the  body  of  the  fly.  The  numbers,  therefore,  only  repre- 
sent those  carried  on  the  outside  and  not  those  in  the  intestinal  tract. 
The  experiments  of  Esten  and  Mason  were  designed  to  simulate  the 
number  of  microorganisms  that  would  come  from  a  fly  in  falling  into, 
milk. 

Torrey*^  found  that  a  single  fly  may  carry  from  570  to  4,400,000 
bacteria  upon  its  surface,  and  from  16,000  to  38,000,000  in  its  intes- 
tinal tract.  The  prevailing  types  are  Streptococcus  equinus  fecalis  and 
salivariuSj  which  are  also  found  in  the  breeding  and  feeding  places  of 

*' Starr's  Agriculiural  Experiment  Station,  Bull.  No.  51,  April,  1908. 
^J.  A.  M.  A.,  May  11,  1912,  LVIII,  No.  19,  p.  144.3. 


314  INSECT-BORNE  DISEASES 

the  house  fly.     Torrey  also  obtained  three  cultures  of  B.  pa/ratyphosus 
which  is  especially  significant. 

Even  though  flies  breed  in  manure,  and  the  larvae  teem  with  bacteria, 
the  adult  winged  insect,  when  newly  hatched,  contains  fewer  micro- 
organisms. This  cleansing  is  due  to  the  active  phagocytosis  which  takes 
place  during  metamorphosis  from  pupa  to  imago.  The  bacteria  in  the 
intestinal  tract  of  the  newly  hatched  imago  are  mostly  extruded  soon 
after  emergence  from  the  puparium. 

Bacot,**  however,  has  shown  that  certain  species  of  bacilli  ingested 
during  the  larval  period  of  Musca  domestica  can  retain  their  existence' 
while  their  host  is  undergoing  the  process  of  metamorphosis,  and  con- 
tinue their  existence  in  the  gut  of  the  adult  fly,  but  that  their  number 
diminishes  suddenly  after  emergence.  In  a  subsequent  work  Bacot  *^ 
demonstrated  that  Bacillus  pyocyaneus  may  thus  survive.  Faichnie*^ 
shows  how  B.  typhosus  may  also  persist.  Ledingham  confirms  these 
conclusions,  and  states  that  he  has  recently  isolated  B.  typhosus  from 
pupa,  the  larvae  of  which  have  fed  on  this  organism. 

Graham-Smith  ^^  recovered  B.  anthracis  from  blow  flies  bred  from 
larvae  fed  on  meat  infected  with  the  organism,  but  failed  to  recover 
B.  typhosus  and  B.  enteritidis. 

Among  the  list  of  diseases  of  which  there  is  more  or  less  evidence 
that  the  infection  may  be  conveyed  by  flies  are:  typhoid,  cholera,  dysen- 
tery, diarrhea  in  infants,  anthrax,  yaws,  erysipelas,  ophthalmia,  diph- 
theria, smallpox,  plague,  tropical  sore,  parasitic  worms,  sleeping  sick- 
ness, loa  loa,  relapsing  fever,  deer  fly  fever,  and  several  infections  of  the 
lower  animals. 

An  interesting  light  was  thrown  on  the  possible  modes  of  dissemina- 
tion of  the  eggs  and  larvae  of  hookworms  by  Galli-Valerio  (1905).  He 
placed  eggs  and  larvae  of  Ankylostomcb  duodenalis  in  a  bottle  with  flies, 
and  on  washing  found  many  eggs  and  encapsulated  larvae  which  had 
adhered  to  their  bodies,  but  none  in  the  flies'  intestines. 

Elies  may  transmit  the  virus  of  disease  mechanically,  either  through 
their  dejecta  or  upon  their  mouth  parts,  legs,  and  other  surfaces  of  the 
body.  The  flies  may  carry  the  infection  directly  to  our  lips  or  indirectly 
to  our  food  or  to  any  surface  upon  which  they  light. 

English  observers  prove  that  house  flies  may  come  a  mile  from  an 
infected  dump  to  the  nearest  village.  Hodge,*^  investigating  the  abun- 
dance of  flies  on  the  cribs  in  Lake  Erie  off  Cleveland,  came  to  the  con- 
clusion that  flies  are  blown  at  least  six  miles  offshore,  and  that  they 
gather  on  the  cribs  as  temporary  resting  places. 

^"^  Trans.  Ento.  Soc,  London,  1911,  Part  II,  p.  497. 

"^Parasitology,  IV,  1,  Mar.,  1911,  p.  68. 

*^Jour.  Roy.  Army  Med.  Corps.  XIII,  1909. 

"'Repts.   to  Local   Gov.   Bd.,  New   Series,  Xo.   53,   1911. 

^  Hodge,  C.  F.:    Science,  1913,  XXXVIII,  512. 


FLIES 


315 


The  maxiimnii  ili<xlit  in  the  oxperiuu'iits  made  at  Cambridge,  Eng- 
land, was  770  yards  across  open  fenland.''  'I'heir  dispersal  is  favored 
by  fine  weatluT  and  warm  temperature.  They  will  even  go  against  or 
across  the  wind,  attracted  ])erhaps  by  the  odors  it  may  convey.  Flies  do 
not  travel  as  far  in  towns  as  in  open  countiy,  probably  on  account  of 
food  and  shelter  afforded  by  the  houses. 

Suppression. — Tlie  suppression  of  the  common  house  fly  may  be  ac- 
complished by  striking  at  their  breeding  places.  In  a  city  this  does  not 
present  very  great  difficulty.  It  resolves  itself  simply  into  a  matter  of 
cleanliness — organic  cleanliness  of 
oiir  environment.  The  chief  breed- 
ing places  are  in  horse  manure  and 
garbage.  These  should  be  given  first 
attention.  One  neglected  stable 
will  furnish  a  plague  of  flies  for 
an  entire  neighborhood.  Their  sup- 
pression in  a  well  ordered  city  for- 
tunately is  neither  expensive  nor 
difficult,  but  it  requires  a  well- 
trained  and  capable  corps  of  inspect- 
ors with  sufficient  authority  to  en- 
force the  regulations.  The  suppres- 
sion of  flies  by  voluntary  effort 
tlirough  the  slow  process  of  educa- 
tion cannot  be  relied  upon. 

In  cities,  stable  manure  should 
be  placed  in  properly  covered  recep- 
tacles and  removed  at  least  once  a 

week.  This  one  measure  obviates  the  use  of  kerosene,  chlorid  of  lime, 
Paris  green,  or  arsenate  of  lead,  all  of  which  are  expensive  and  un- 
certain unless  used  frequently  and  in  liberal  amounts;  further,  they 
may  decrease  the  fertilizing  value  of  manure. 

Garbage  should  be  kept  in  water-tight  cans  with  good  covers  and 
removed  frequently,  especially  in  the  warm  weather,  Eefuse  on  city 
lots,  in  back  yards,  in  alleys,  about  wharves,  markets,  and  similar  places 
should  be  regularly  taken  away.  Householders,  provision  merchants, 
storekeepers,  and  others  should  be  held  responsible  for  the  cleanliness 
and  tidiness  of  their  premises,  and  those  who.  violate  these  simple  and 
primitive  hygienic  requirements  should  have  their  places  cleaned  up 
for  them  at  their  own  expense. 

Where  it  is  not  practicable  to  remove  manure,  it  may  be  kept  cov- 
ered in  a  dark  place,  which  discourages  the  visitation  and  breeding  of 

''Local  Gov.  Board  on  Public  Health  Subjects,  191.3.  N.  S.  No.  85,  pp.  20-41, 
by  Hindley  and  Merriman,  also  Jour.  Hijg.,  1914,  XIV,  2.3. 


Fig. 


38.— The  Hodge  Fly  Trap 
ox  A  Garbage  Can. 


316  INSECT-BOET^E  DISEASES 

flies,  and  in  addition  should  be  carefully  screened.  Larvae  may  be  de- 
stroyed. The  best  results  are  obtained  by  the  use  of  borax  (sodium 
borate)  and  calcined  colemanite  (crude  calcium  borate). •'''°  Both  sub- 
stances possess  a  marked  larvicidal  action,  but  appear  to  exert  no  per- 
manent injury  on  bacteria.  In  order  to  kill  fly  eggs  and  maggots,  apply 
0.62  pound  borax  or  0.75  pound  calcined  colemanite  to  every  10  cu.  ft. 
(8  bushels)  of  manure  immediately  on  its  removal  from  the  barn.  Apply 
the  borax  particularly  around  the  outer  edges  of  the  pile  with  a  flour 
sieve  or  any  fine  sieve  and  sprinkle  two  or  three  gallons  of  water  over 
the  borax  treated  mass.  As  the  maggots  congregate  at  the  outer  edges 
of  the  pile,  most  of  the  borax  should  be  applied  there.  The  treatment 
should  be  repeated  with  each  addition  of  fresh  manure.  Borax  may  also 
be  applied  to  floors  and  crevices  in  barns,  markets,  stables,  etc.,  as  well  as 
to  street  sweepings.  The  borax  does  not  appear  to  injure  the  fertilizing 
value  of  the  manure  if  it  is  applied  carefully,  applied  so  as  in  no  case 
to  exceed  0.62  pound  per  10  cubic  feet. 

Unsatisfactory  results  are  obtained  with  the  use  of  kerosene,  iron  sul- 
phate, potassium  cyanid,  copper  sulphate,  lime  sulphur  mixture,  Paris 
green,  sodium  fluorite,  formaldehyd,  and  the  Isthmian  Canal  Com- 
mission larvieide. 

Another  method  of  suppression  which  has  been  found  quite  effective 
in  certain  army  camps  is  the  simultaneous  application  of  three  measures : 
first,  the  removal  of  the  manure  as  early  in  the  morning  as  possible, 
before  it  has  become  infested;  second,  the  removal  of  the  manure  to  a 
considerable  distance  and  building  it  up  as  a  compact  heap  in  which  the 
pressure  and  heat  tend  to  prevent  breeding,  except  possibly  at  the  outer 
edges,  but  even  these  will  soon  become  unfavorable  in  very  dry  weather; 
third,  the  use  of  fly  traps  kept  well  baited.  Fly  traps  work  most 
efficiently  when  there  is  no  manure,  kitchen  refuse  or  other  soil  pollu- 
tion to  compete  with  the  bait  as  an  attraction. 

Flies  are  thirsty  insects  and  will  be  attracted  to  a  saucer  of  water 
containing  a  little  formalin  (1.25  to  2.5  per  cent.).  Sodium- salicylate 
(1  per  cent.)  is  a  muscicide  of  about  equal  efficiency.^^  This  simple 
measure  will  kill  many  of  them  in  a  room.  The  salts  of  barium,  cobalt, 
and  other  poisons,  such  as  arsenic,  potassium  bichromate,  or  quassia 
infusion,  may  be  used  instead  of  formalin,  and  are  better  bait  if 
sweetened.  Sticky  fly-paper,^^  fly  traps,  electric  fans,  and  other  well- 
known  measures  will  help,  dispose  of  a  certain  number  of  flies,  but  all 
these  measures  are  tentative,  and  attack  the  problem  at  the  wrong  end. 

The  fly  has  a  number  of  natural  enemies :  various  fungi,  especially 

one  belonging  to  the  EntomophtJioreae,  which  destroys  flies  in  the  au- 

™The  United  States  Department  of  Agriculture    {Bull,   of  the  U.  S.   Dept. 
Agriculture,  No.  118,  July  14,  1914). 
''  Hyg.  Lai.  Bull.  No.  108. 
"  Formula  for  sticky  fly-paper,  see  page  272. 


FLIES  317 

tunm.  Flics  also  harlx)!-  jjrotozoa  and  nematodes  as  parasites,  which, 
however,  seem  to  do  tluMu  little  harm.  The  little  bright  red  objects 
often  seen  attached  to  tlics  arc  mites,  which  are  usually  only  temporary 
ectoparasites  stealing  a  free  ride.  When  spider  webs  are  not  disturbed 
they  catch,  and  the  spiders  devour,  a  large  number  of  flies.  The  house 
centipede  (Scutigera)  also  sometimes  catches  and  eats  flies,  as  do 
the  common  garden  toad,  some  lizards,  and  a  few  insectivorous 
birds. 

Flies  and  similar  dipterous  insects  are  responsible  for  the  transmis- 
sion of  a  large  number  of  diseases,  most  of  which  are  discussed  else- 
where. It  now  remains  to  consider  sleeping  sickness,  transmitted  by 
the  tsetse  fly  (Glossina  paJiKiHs),  pappataci  fever,  transmitted  by  a  biting 
dipterous  insect  (Fhlehoiomus  papaia-ssii) .  and  deer  fly  fever  (Crysops). 
For  convenience  a  general  consideration  of  the  trypanosomes  is  inserted 
in  this  chapter. 

SLEEPING  SICKNESS 

(The  Trypanosome  Fevers — Trypanosomiasis) 

Sleeping  sickness  was  limited  to  tropical  Africa,  especially  in  the 
Congo,  on  the  shores  of  Victoria  Nyanza,  and  about  the  head  waters 
of  the  Xile,  but  is  gradually  spreading.  Many  thousands  have  perished 
from  this  infection,  caused  by  Trypanosoma  gamhiense  and  transmit- 
ted by  the  tsetse  fly  (Glossina  palpalis).  The  disease  is  characterized 
by  two  stages:  in  the  first  there  are  irregular  fever,  glandular  enlarge- 
ments, an  erythematous  rash,  and  localized  edemas.  In  the  second  there 
are  slowly  increasing  lethargy  and  other  morbid,  nervous  symptoms. 
After  a  chronic  course  sleeping  sickness  usually  terminates  in  death; 
few  cases  recover.  Many  instances  of  fatal  "homesickness"  in  the  negroes 
during  the  slave  trade  are  now  believed  to  have  been  this  disease. 

The  Trypanosoma  gamhiense  was  discovered  by  Button  in  1901  dur- 
ing the  first  or  febrile  stage  of  sleeping  sickness,  and  subsequently 
studied  by  Button  and  Todd,  who  did  not  at  first  suspect  the  relation 
of  the  trypanosome  to  sleeping  sickness.  This  was  shown  by  Castellani 
in  1903.  The  trypanosomes  are  found  in  the  cerebrospinal  fluid,  in 
the  enlarged  lymphatic  glands,  and  also  in  the  circulating  blood.  It 
seems  that  when  the  trypanosomes  are  inoculated  through  the  skin  by. 
the  tsetse  fly  they  are  temporarily  blocked  by  the  lymphatic  glands. 
From  here  small  numbers  of  them  pass  into  the  circulation  and  thus 
to  other  parts  of  the  body.  They  are  always  in  the  fluids ;  never  in  the 
cells  or  tissues.  Xov^^  and  McXeal  in  1903  accomplished  the  remarkable 
feat  of  growing  trypanosomes  in  the  water  of  condensation  of  blood 
agar  tubes.  Pure  cultures  show  marked  differences  between  the  Try- 
panosoma  lewisi  of  the  rat  and  the  Trypanosoma  grussei  of  horses  and 


318 


mSECT-BOENE  DISEASES 


other  domestic  animals.  So  far  no  one  has  succeeded  in  .cultivating  the 
Trypanosoma  gambiense  in  artificial  culture  media. 

Sleeping  sickness  in  Ehodesia  is  caused  by  Trypanosoma  rhodesiense 
(Stephens  and  Fantham,  1910),  transmitted  by  Glossina  morsitans 
(Kinghorn  and  York,  1912).  The  disease  in  Rhodesia  is  similar  to 
that  in  the  Gambia;  furthermore,  the  parasites  and  tsetse  flies  of  both 
are  closely  allied  species. 

The  relation  of  the  tsetse  fly  to  the  transmission  of  this  disease 
rests  upon  satisfactory  evidence.  Button  and  Todd,  as  well  as  others, 
find  these  flies  abundant  wherever  sleeping  sickness  exists.     Wherever 


Fig.  39. — Tsetse  Fly  {Glossina  palpalis) 


the  Glossina  palpalis  is  absent  sleeping  sickness  never  spreads,  as  Koch 
observed;  while,  on  the  other  hand,  if  a  case  is  brought  to  a  locality 
where  the  tsetse  fly  prevails,  it  soon  spreads.  It  is  probable  that  the 
transmission  by  the  tsetse  fly  is  not  of  the  simple  mechanical  type,  but 
that  the  parasite  undergoes  a  sexual  evolution  within  the  insect.  Flies 
seem  to  lose  their  power  of  transmission  soon  after  feeding  on  an  infected 
animal,  and  Bruce  considers  it  thoroughly  impossible  that  mechanical 
transmission  alone  could  explain  the  situation.  Kleine's  experiment  on 
monkeys,  confirmed  by  Bruce,  showed  that  the  flies  may  convey  the 
disease  31  days  after  one  feeding  upon  a  monkey  infected  with  sleeping 
sickness.  In  another  experiment  by  Taute,  which  is  reported  by  Kleine, 
infection  was  produced  on  each  of  the  first  three  days  after  feeding. 
From  the  fourth  to  the  tenth  day  no  infection  resulted.  The  flies  then 
became  infective  again  and  produced  the  disease  from  the  eleventh  to 
the  forty-fourth  day.  Kleine  ^^  concludes  that  the  period  of  develop- 
ment or  extrinsic  period  of  incubation  in  the  fly  is  about  20  days  or  a 
little  less.  Flies  remain  infective  at  least  75  days.  Not  all  flies  which 
^^Bull.  of  the  Sleeping  Sickness  Bureau,  No.  7,  1909. 


FLTES  319 

drink  blood  coiitaining  tiyjjiuiosomes  become  inrectivc.  The  proportion 
is  about  1  in  '2(1  Of  the  flies  eaught  in  nature  in  endemic  areas,  from 
2  to  10  in  one  thousand  are  capable  of  transmitting  the  disease  to 
animals.  Xovy  has  eniphnsizecl,  and  Minchim  has  corroborated  the 
fact,  that  tsetse  flies  may  hai-lior  ntni-pathogenie  as  well  as  pathogenic 
trypanosomes,  a  fact  which  ini])airs  the  value  of  a  great  deal  of  the 
microscopic  work  which  has  been  done.  As  a  means  of  avoiding  the 
accident  of  dealing  with  naturally  infected  flies,  it  is  best  to  use  those 
which  have  been  bred  and  raised  in  the  laboratory. 

Prevention. — The  prevention  of  sleeping  sickness  in  the  present  state 
of  our  knowledge  depends  first  upon  isolation  of  the  sick,  protecting 
both  the  sick  and  the  well  against  fly  bites,  and  the  suppression  of  the 
flies  themselves.  The  sick  should  be  isolated  in  a  location  where  Glos- 
sina  palpalis  is  absent,  or  in  a  well-screened  and  carefully  managed 
hospital.  It  is  especially  important  to  isolate  all  those  who  carry  the 
infection  in  the  early  stages  of  the  disease,  whether  they  feel  sick  or 
not.  It  is  not  sufficient  simply  to  isolate  those  who  have  enlarged 
glands  but  careful  blood  examinations  must  be  made.  The  trypano- 
somes have  been  found  in  the  circulating  blood  of  persons  with  normal 
lymph  glands. 

All  persons  taken  to  the  hospital  and  detention  station  are  given  a 
thorough  treatment  with  atoxyl  (a  combination  of  arsenious  acid  and 
anilin  oil).  x\toxyl  is  one-tenth  as  toxic  and  contains  about  three  times 
as  much  arsenic  as  arsenious  acid  alone.  The  dose  is  from  %  to  3 
grains  (0.05-0.2  grams)  subcutaneously,  combined  with  antimony  in 
the  form  of  tartar  emetic. 

The  extermination  of  the  tsetse  fly  seems  a  hopeless  task.  The  larvae 
remain  in  the  body  of  the  mother  fly  until  fully  developed  and  are  then 
dropped  on  moist  soil,  in  which  they  burrow  to  undergo  transformation 
to  the  adult  state;  therefore,  clearing  of  the  land  in  limited  locations 
largely  diminishes  the  number  of  flies.  Clearing  the  brush  exposes  the 
earth  to  the  sun,  and  the  surface  becomes  dry  and  hard,  so  that  flies  die 
during  the  pupal  period.  This  measure  has  limited  possibilities,  but  is 
useful,  as  Shirata  points  out,  around  ports,  in  the  neighborhood  of 
villages,  wharves,  and  other  places. 

The  tsetse  fly  may  also  be  fought  by  suppressing  its  food  supply.  It 
must  obtain  the  blood  of  some  vertebrate  animal  every  two  or  three  days. 
The  German  Commission  has  shown  that  on  the  banks  of  the  Victoria 
Xyanza  the  tsetse  fly  lives  largely  upon  crocodile  blood.  This  fact  was 
discovered  by  the  interesting  observation  that  the  flies  frequently  con- 
tain parasites  peculiar  to  the  crocodile's  blood.  Koch  believes  that  the 
disease  may  be  successfully  controlled  by  destruction  of  the  crocodiles, 
a  theory  which  later  research  has  rendered  very  unlikely,  for  the  flies 
feed  upon  other  animals. 


320 


INSECT-BOKNE  DISEASES 


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FLIES  321 

Authorities  advocate  the  exteriuiniitiuii  of  big  game  on  the  belicl'  that 
they  are  the  vertebrate  reservoir  ol'  the  parasite.  This,  however,  requires 
further  study  before  attempting  to  put  such  a  radical  measure  into  effect. 

Todd  and  Wolbach  ''"'  suggest  a  systematic  e.xamination  of  the  natives 
in  the  endemic  area  by  gland  palpation  and  gland  puncture.  The  latter 
consists  in  withdrawing  a  drop  of  fluid  from  one  of  tiic  enlarged 
lymphatic  glands  by  means  of  a  li\  itodrrniic  syringe,  'i'hc  little  drop 
of  bloody  fluid  thus  obtained  is  cxaiiiiiicd  as  a  fresh  preparation  under 
the  microscope  for  trypanosomes.  By  this  method  these  investigators 
found  at  least  0.8  per  cent,  of  the  population  of  the  Gambia  to  harbor 
trypanosomes.  If  all  the  infected  individuals  could  be  collected  in  vil- 
lages for  observation,  treatment,  and  isolation,  it  would  do  much  to 
limit  the  disease. 

Chagas'  Disease,  or  Brazilian  trypanosomiasis,  is  caused  by  Trypano- 
soma criizi,  and  transmitted  by  Lanus  magistus  (Triatoma  magista),  a 
predacious  bug  which  has  acquired  a  liking  for  human  blood. 

Trypanosomes  are  the  cause  of  numerous  diseases  in  animals,  as  will 
be  seen  by  reference  to  the  table  on  page  330.  So  far  as  known,  sleep- 
ing sickness  and  Chagas'  Disease  are  the  only  important  diseases  of  man 
produced  by  trypanosomes.  Kala-azar,  however,  is  produced  by  a  flag- 
ellated protozoon  parasite  which  is  closely  allied  to  the  trypanosomes. 

Practically  all  animals  are  susceptible  to  almost  all  trypanosomes. 
The  trypanosomes  which  infect  man  may  readily  be  transmitted  to  mon- 
keys, guinea-pigs,  rabbits,  etc. 

DEEE-FLY  FEVER 

(Pahvent  Valley  Plague) 

Deer-fly  fever  is  a  mild  specific  febrile  infection  due  to  Bacterium 
tularense,  and  transmitted  by  Crysops,  a  biting  fly.  The  disease  is 
limited  to  the  rural  population  of  Millard  County,  Utah.  It  is  char- 
acterized by  enlargement  of  the  lymph  glands,  which  drain  the  bitten 
area,  and  by  a  fever  of  septic  type  lasting  from  three  to  six  weeks.  The 
site  of  the  bite  and  the  affected  lymph  glands  become  tender,  inflamed 
and  commonly  suppurate.  There  is  marked  prostration  and  the  patient 
is  confined  to  his  bed.  Probably  two  dozen  cases  occurred  in  the  Pahvent ' 
Valley  in  Utah  in  each  of  the  years  1917,  1918  and  1919.  The  disease 
is  mild;  the  first  case  known  to  have  terminated  fatally  was  reported  in 
1919. 

Bacterium  tularense  was  discovered  by  McCoy  and  Chapin  ^^  in  1913 

^Annals  of  Tropical  Medicine  and  Parasitology,  Vol.  V,  No.  2,  Aug.,  1911, 
p.  245. 

"'Public  Health  Bull.  No.  53,  U.  S.  Public  Health  Service. 


322  INSECT-BOENE  DISEASES 

as  the  cause  of  a  plague-like  disease  of  rodents  in  California.  The  year 
before,  McCoy  ^^  described  this  new  plague-like  disease  which  he  found 
in  the  ground  squirrels  of  California.  Bacterium  tidarense  grows  only 
on  coagulated  Qgg  yolk.  It  is  a  small  coccobacillus,  and  is  doubtless 
identical  with  the  organism  described  by  Francis  ^'^  as  the  cause  of  deer- 
fly  fever  in  Utah.  ^Yherry  and  Lamb  ^*  described  an  infection  of  man 
with  this  organism. 

Francis  has  shown  that  guinea-pigs  and  rabbits  are  susceptible  when 
inoculated  with  blood  or  with  pus  from  a  suppurating  gland  of  a  pa- 
tient. The  disease  in  experimental  animals  is  fatal;  the  lesions  are 
caseation  of  the  lymph  glands  and  small  necrotic  foci  throughout  the 
liver  and  spleen.  The  infection  presumably  is  kept  alive  in  Utah  in 
rabbits  and  perhaps  other  rodents. 

PAPPATACI  FEVER 

(Three-day  Fever,  Phlehotomus  Fever,  Sand-fly  Fever) 

Doerr  and  Euss,^^  and  also  Doerr,  Franz,  and  Taussig  originally 
described  a  three-day  fever  which  occurs  on  the  shores  of  the  Mediter- 
ranean ;  it  is  also  known  in  India,  Egypt  and  South  America.  The  cause 
of  pappataci  fever,  or  sand-fly  fever,  is  not  known.  The  period  of 
incubation  is  3  to  5  days;  the  onset  is  sudden.  Uncomplicated  cases 
are  never  fatal.  The  disease  occurs  in  epidemics  with  a  high  incidence 
rate.  Pappataci  fever  has  many  resemblances  to  dengue  fever.  It  is 
transmitted  through  the  bite  of  a  dipterous  insect — Phlehotomus  pap- 
patasii.  This  little  gnat  only  bites  in  darkness  and  only  in  houses. 
Prevention  consists  in  using  a  fine  mosquito  netting,  and  insecticidal 
agents. 

FLEAS 

Fleas  are  laterally  flattened,  wingless  creatures  related  to  the  Diptera. 
They  pass  through  a  complete  metamorphosis :  egg,  larva,  pupa,  and 
imago.  The  adult  female  flea  deposits  her  eggs  among  the  hair  or  fur 
of  the  host  animal,  but,  unlike  the  eggs  of  many  ectoparasites,  they  are 
not  fastened  to  the  hairs  and  therefore  fall  freely  to  the  ground.  The 
eggs  are  oval,  whitish,  and  smooth  and  about  half  a  millimeter  long. 
The  larvae  escape  from  the  eggs  in  2  to  5  days.  They  are  able  to  break 
the  egg  shell  by  a  slender  process  on  the  top  of  the  head  which  disappears 
after  the  first  molt.     The  larva  is  a  slender,  legless,  cylindrical  creature, 

^"Public  Health  Bull.  ^'o.  ^3,  U.  S.  Public  Health  Service. 

^'  Puhlic  Health  Rpts.,  U.  S.  Public  Health  Service,  Sept.  12.  1919. 

^Jour.  Inf.  Dis.,  1914,  Vol.  15.  p.  .331. 

^^Schijfs  und  Tropen  Hyg.,  1909,  Vol.  XIII,  Xo.  22.  n.  693. 


FLEAS 


323 


whitish  or  yellowish  in  color,  with  a  head  and  13  segments.  There  are  a 
few  scattered  hairs  or  bristles  on  the  body,  and  at  the  tip  is  a  pair  of  cor- 
neous processes.  At  the  front  of  the  head  is  a  pair  of  biting  jaws  or 
mandibles.  The  larvae  feed  on  almost  any  kind  of  refuse.  They  have 
been  reared  on  the  sweepings  from  rooms.  There  is  always  some  organic 
matter  in  such  dust,  and  this,  is  doubtless  their  nourishment.  In 
houses  the  larvae  usually  crawl  into  cracks  or  in  carpets,  where  they  feed 
and  grow.  Tliosc  tbat  infest  wild,  animals  probably  feed  on  the  refuse 
in  the  nests  or  retreats  of  these  animals.  It  will  be  noticed  that, 
unlike  the  mosquito,  the  larval  and  pupal  stages  of  the  flea  are  not 
aquatic.     They  remain   in  the  larval  stage  from  a  week  to  ten  days, 


1 

J&/    1:.    1   I 

^ 

/  (  ' 

Fig.  40. — The  Indian  Rat  Flea   (XefiopsyUa  cheopis  Rothsc.)^ 


sometimes  two  weeks,  molting  the  skin  three  times  in  this  interval. 
Then  they  spin  flat,  white,  silken  cocoons  in  which  they  transform  to 
the  pupal  stage.  In  from  5  to  8  days  the  adult  flea  emerges  from  the 
cocoon.  The  period  of  their  transformation  is  affected  by  the  tempera- 
ture and  moisture.  In  warm,  damp  weather  a  generation  may  develop 
in  10  days  or  2  weeks,  but  usually  about  IS  days  to  3  weeks  elapse  from 
the  egg  to  the  adult.  Although  some  moisture  is  necessary  for  their 
development,  an  excess  is  apt  to  destroy  the  larvae. 

The  leaping  ability  of  adult  fleas  is  familiar  to  all.  This,  however, 
has  been  greatly  exaggerated.  The  British  Plague  Commission  deter- 
mined that  fleas  jump  3  to  5  inches,  never  over  6.  Xo  part  of  the 
leg  is  particularly  enlarged,  so  that  the  jump  is  made  by  the  entire  leg,  as 
in  the  leaf-hopper  insect,  and  not  by  the  femur  of  the  hind  leg,  as  in 
the  grass-hopper.  Fleas  do  not  vary  much  in  size.  They  are  mostly 
about  2  to  3  millimeters  long.  The  adnlt  insect  has  a  hard,  strongly 
chitinized  body.  The  mouth  parts  resemble  somewhat  those  of  the  mos- 
quito.   Both  the  male  and  the  female  flea  are  capable  of  piercing  the  skin 

™  Formerly  Loemopsylla  cheopis. 


324 


mSECT-BOENE  DISEASES 


to  obtain  blood  and  thus  transmit  infection.  Fleas,  as  a  rule,  prefer 
certain  hosts,  but  are  not  as  particular  in  this  regard  as  are  many  para- 
sites. Those  species  which  are  best  known  are  found  to  attack  several 
hosts,  including  man.  This  is  one  reason  that  makes  them  dangerous 
so  far  as  plague  and  other  infections  are  concerned.     Over  300  species 


^m 

tfBRk 

• 

Fig.  41. — The  Common  Rat  Feea  of  Europe  axd  Xorth  America (C'eraiop/t i/Z/wi- 

fasciatus  Bosc.) . 

are  described.  Formerly  all  fleas  were  classified  in  the  single  family 
Pulicidae,  genus  Pulex;  now  they  are  arranged  in  many  genera  and 
these  genera  grouped  into  families.^^  Pulex  serraticeps  or  Ct&nocephaliis 
canis  occurs  all  over  the  world,  infesting  cats  and  dogs,  also  many 
other  animals.  They  are  frequently  brought  into  houses  upon  domestic 
animals,  and  thus  become  troublesome  to  man.     Pulex  irritans  is  the 


Fig.  42. — The  Human  Flea  [Pulex  irritans  Linn.). 


human  flea,  sometimes  called  the  '%ouse  flea"  or  "common  flea."     The 

fleas  concerned  in  the  transmission  of  plague  are  Xenopsylla  cheopis,  the 

India   rat   flea,   and   Ceratophyllus  fasciatus,  the   common   rat   flea  of 

Europe  and  North  America.     Plague  may  also  be  transmitted  by  Cteno- 

^  Banks:     "The  Rat  and  Its  Relation  to  the  Public  Health,"  P.  H.  and  M. 
H.  S.,  p.  69. 


KELATIOX  OF  IM.ACUJE  TO  IfATS  .VXD   KI.KAS         325 

cephalus  fells,  the  cat  Ilea;  Puh.r  irrihiiis,  the  hiiniau  flea;  C eratopliyllus 
acutus,  the  squirrel  flea,  and  (hnihtless  other  genera  and  species. 

In  addition  fleas  act  as  intermediate  hosts  for  certain  tapeworms 
(Dipylidium  caninum) ,  and  doubtless  are  the  mechanical  or  biol<)<fical 
carriers  of  other  infections.  Kicollo  incriminates  the  flea  in  typhus 
fever. 

Pulicides. — Adult  fleas  succumb  to  the  ag'ents  a|>|)lical)le  to  insects 
in  general.  Mitzmain "-  has  shown  that  water  ih  of  little  value  in 
the  destruction  of  mature  fleas.  Glycerin  is  also  practictilly  inert  as  a 
pulicide,  but  tincture  of  green  soap  is  very  quick  and  effective.  Kerosene 
(coal  oil)  is  a  very  efficient  flea  destroyer.  An  emulsion  of  petroleum 
and  soft  soap,  with  or  without  naphthalene,  is  a  good  pulicide.  Formalin, 
phenol,  mercuric  bichlorid,  and  tricresol  in  the  strength  used  as  disin- 
fectants are  of  little  value  in  killing  fleas.  Powdered  sulphur  seems  to 
be  of  no  value. 

Hydrocyanic  acid  is  the  most  efficient  of  the  gases  because  it  kills 
both  the  fleas  and  their  eggs.  The  amount  used  is  2i.^  ounces  of  sodium 
cyanid  per  thousand  cubic  feet  of  air  space.  -See  page  515.  Sulphur 
dioxid,  3  pounds  per  thousand  cubic  feet,  and  also  disulphid  of  carbon 
will  kill  fleas,  but  cannot  be  depended  upon  to  destroy  their  eggs.  Chlo- 
roform or  ether  first  anesthetizes  fleas,  and  if  continued  kills  them.  This 
is  important  for  the  safe  handling  of  rats,  squirrels,  and  other  plague 
animals.  The  host  may  be  chloroformed  and  the  fleas  and  other  ecto- 
parasites removed  with  a  comb.  The  anesthetic  may  be  controlled  by 
practice  so  that  the  host  will  recover  and  the  fleas  die,  or  both  recover, 
or  both  die,  as  may  be  desired. 

In  flea-infected  houses  the  larvae,  living  in  the  cracks  of  the  floor, 
etc.,  may  be  controlled  by  sprinkling  a  thin  coating  of  flake  naphthalene 
on  the  floor  and  then  leaving  the  room  tightly  closed  over  night.  In 
the  morning  the  naphthalene  may  be  swept  up  and  what  remains  used 
again. 

Kitasato  ^^  confirms  the  efficacy  of  the  method  of  collecting  rat  fleas 
by  turning  guinea-pigs  loose  in  a  building.  The  fleas  collect  upon  the 
guinea-pigs  and  both  the  fleas  and  the  pigs  may  then  be  examined  for 
plague  bacilli. 

RELATION  OF  PLAGUE  TO  RATS  AND  FLEAS 

Plague  is  primarily  a  disease  of  the  rat  and  secondarily  of  man. 
This  fact  is  now  firmly  established  not  only  by  the  recent  experiences, 
but  especially  through  the  admirable  studies  of  the  Indian  Plague  Com- 

^' Public  Health  Reports,  July  29,  1910,  Vol.  XXV,  No.  30,  p.  1039. 
"  Kitasato,   S. :      ''Bubonic  Plague   and   Rat   Fleas."     Berl.   klin.   Wchnschr.^ 
Oct.  13,  L,  41,  pp.  1881-1928. 


326  IKSECT-BORNE  DISE'ASES 

mission,^*  which  established  beyond  doubt  the  fact  that  plague  may  be 
and  generally  is  transmitted  from  rat  to  rat  and  from  rat  to  man 
through  the  agency  of  the  flea — Xenopsylla  cheopis — and  sometimes  by 
C eratopliyllus  fasciatus,  et  al.  During  some  plague  epidemics  it  has 
been  noted  that  the  rats  die  in  great  numbers  before  and  during  the  out- 
break. It  is  now  known  that  this  epizootic  in  the  rat  is  true  plague. 
In  nature,  rats  suffer  both  with  acute  and  chronic  plague. 

In  the  laborator}^,  rats  may  be  infected  with  plague  by  ingestion,  by 
application  of  the  virus  to  mucous  or  cutaneous  surfaces,  or  by  sub- 
cutaneous inoculation.  In  nature,  rats  may  become  infected  by  any  of 
these  means,  but  probably  flea  transmission  is  the  only  one  that  ordi- 
narily operates  to  any  extent. 

Eats  are  great  travelers,  and  have  carried  the  plague  to  all  quarters 
of  the  globe.  A  more  complete  discussion  of  the  rat  and  its  relation 
to  plague  and  other  diseases  will  be  found  on  page  335. 

Within  the  past  few  years  it  has  been  discovered  that,  while  the 
rat  is  the  great  medium  for  the  spread  of  plague,  the  disease  was  prob- 
ably preserved  from  extinction  in  Thibet  by  another  rodent,  the  marmot 
(Arctomys  hohac).  The  tarbagan,  a  fur-bearing  rodent,  infected  trap- 
pers and  traders,  who  in  turn  started  the  epidemic  of  pneumonic  plague 
in  Manchuria  in  1910-1911.  In  California  the  infection  has  gotten  into 
the  ground  squirrels  (Citellus  heecheyi),  in  which  the  disease  will  doubt- 
less be  kept  alive  for  many  years  to  come.  To  realize  the  full  impor- 
tance of  these  discoveries,  it  is  only  necessary  to  call  to  mind  that,  in 
order  to  eradicate  plague  a  warfare  against  the  rat  alone  is  not  sufficient, 
but  must  include  the  rodents  mentioned  and  perhaps  others. 

Simond  in  1897  advanced  the  theory  that  plague  was  carried  by 
fleas.  This  theory  was  developed  by  J.  Ashburton  Thompson  and  others 
and  conclusively  proved  by  the  Indian  Plague  Commission.  The  exact 
method  by  which  the  flea  transmits  the  infection  from  animal  to  ani- 
mal is  not  definitely  understood.  The  mouth  parts  appear  not  to  re- 
main infected.  It  is  improbable  that  the  salivary  secretions  contain  the 
microorganisms.  It  is  known  that  the  plague  bacilli  may  live  in  the 
digestive  tract  and  be  passed  in  live  and  virulent  numbers  in  the  de- 
jecta. It  is  easy  to  understand  how  some  of  the  infected  dejecta  may 
be  rubbed  or  scratched  into  the  little  wound  produced  by  the  flea  bite. 

Bacot  and  Martin  ®^  found  that  Xenopsylla  cheopis  and  C eratopliyllus 
fasciatus  may  transmit  plague  during  the  act  of  sucking  by  regurgitating 
some  of  the  blood.  These  investigators  found  that  in  a  proportion  of 
infected  fleas  the  plague  bacilli  develop  to  such  an  extent  in  the  esopha- 
gus and  pro ventri cuius  as  to  occlude  the  alimentary  canal  at  the  entrance 
to  the  stomach.     Fleas  in  this  condition  are  not  prevented  from  sucking 

"*  Journal  of  Hygiene,  Vol.  VI,  No.  4;  Vol.  VII,  Nos.  3,  6;  Vol.  VIII,  No.  2. 
^Uhid.,  Plague  Supplement,  III,  p.  423,  1914. 


RELATION  OF  PLAGUE  TO  RATS  AND  FLEAS 


327 


blood  as  llio  puni])  is  in  the  pharynx,  l)ut  (hey  only  succeed  in  distending 
an  already  obstructed  esophagus,  and  on  cessation  of  the  pumping  act 
some  of  the  blood  is  forced  back  into  the  wound.  Such  fleas  are  per- 
sistent in  their  endeavors  to  feed,  and  .this  renders  them  particularly 
dangerous. 

When  it  was  found  that  the  connnon  rat  flea  of  Europe,  the  Cera- 
lopJn/llus  fascialus,  docs  not  readily  bite  man,  considerable  doubt  was 
thrown  upon  the  ])arl  ])1ayed  by  the  flea  in  plague  transmission.  These 
negative  results,  however,  are  ofl'set  by  the  convincing  positive  proofs 
of  the  British  Plague  Commission  in  India,  and  by  McCoy  and  Mitz- 
main  in  San  Francisco,  who  showed  that  under  certain  conditions  the 
rat  flea  will  bite  num.  especially  if  the  natural  food  supply  is  limited, 


Fig.  43. — A  Squirrel  Flea   {Hoplopsyllus  anomnhts  BaJcer.) . 


and  that  these  fleas  may  feed  on  a  man's  hand  even  in  the  presence  o£ 
a  rat. 

Paybaud  ^'^  calls  attention  to  the  fact  that  the  rat  flea  {CeratopkyUas 
fasciaius)  is  able  to  hibernate  for  a  month  or  45  days  without  nourish- 
ment, and  that  virulent  plague  germs  may  persist  unharmed  in  its 
stomach  during  this  length  of  time  and  even  longer.  This  fact  may 
be  of  importance  for  the  transmission  of  plague  to  a  distance. 

Bacot  and  Martin  *"■  found  that  infected  fleas  which  were  fed  regu- 
larly might  live  for  50  days,  at  from  10  to  15°  C.  and  23  days  at  27°  C. 
and  remain  infected  at  death. 

The  Commission  for  the  Investigation  of  the  Plague  in  India  '^^  found 
that  infection  conveyed  by  fleas  might  take  place  three  weeks  after  the 
flea  population  had  any  opportunity  of  imbibing  infected  blood.  Bacot  ^^ 
has  observed  that  fleas  (Ceratophyllus  fasciatus)  are  able  to  carry  the 

^"Presse  Medicate,  March  8,  1911,  No.  20. 

«Vowr.  A.  M.  A.,  Apr.  10,  1915,  LXIV,  15,  p.  1251. 

•^  Reports  on  Plague  Investigations  in  India,  Jour.  Hyg.,  1906,  VI,  435. 

^Observations  on  the  length  of  time  that  fleas  (Ceratophyllus  fasciatus) 
carrying  Bacillus  pcstis  in  their  alimentary  canals  are  able  to  survive  and  retain 
the  power  to  reinfect  with  plague,  Jour.  Hyg.,  Plague  Supplement  IV,  1915,  770. 


328  INSECT-BORNE  DISEASES 

bacillus  of  plague  for  periods  up  to  47  days  and  subsequently  infect  a 
mouse. 

The  indications  thus  are^,  that  plagixe  infection  may  persist  in  fleas 
at  least  1  or  2  months  in  cold  weather  and  subsequently  give  rise  to 
an  epizootic. 

The  development  of  plague  bacilli  in  the  flea.,  as  well  as  the  activity 
of  the  flea  itself,  is  restricted  both  in  very  hot  and  very  cold  weather. 
Extremes  of  temperature  are  therefore  not  favorable  for  the  spread  of 
the  bubonic  form  of  the  disease.  The  pneumonic  form  spreads  best  when 
the  weather  is  very  cold. 

It  should  be  remembered  that,  according  to  the  observations  of  Nut- 
tall  and  Yersin,  flies  and  possibly  other  insects  may  also  occasionally 
convey  the  infection.  Walker  '"^  considers,  as  the  result  of  experiments, 
that  bedbugs  and  other  biting  insects  play  an  important  role  in  the 
transmission  of  plague.  Bacot  ''^  has  demonstrated  that  bedbugs  are 
capable  of  carrying  Bacillus  pestis  and  may  thus  infect  mice  after  a 
period  of  48  days'  starvation. 


RATS  AND  OTHER  RODENTS 

Eats,  mice,  squirrels,  and  other  rodents  have  become  a  serious  prob- 
lem in  preventive  medicine,  and  their  habits  and  methods  of  suppression 
may  be  considered  conveniently  at  this  place.  Plague  being  primarily 
a  disease  of  rats,  the  prevention  and  suppression  of  this  infection  re- 
solve themselves  into  a  war  upon  these  rodents.  For  the  control  of 
plague  it  is,  therefore,  necessary  to  have  a  knowledge  of  the  life  history 
and  methods  of  attacking  the  problem  in  the  lower  animals.  In  addi- 
tion to  plague,  rats  are  a  reservoir  of  trichinosis.  They  are  responsible 
for  infectious  jaundice,  for  the  transmission  of  certain  tapeworms  and 
other  parasites.  They  are  subject  to  leprosy,  cancer,  and  numerous 
other  diseases,  some  of  which  concern  man.  Eats  and  mice  also  are 
carriers  of  B.  enteritidis,  which  is  connected  with  food  infection. 

Eodents  comprise  more  than  one-third  of  all  living  species  of  mam- 
mals, and  exceed  any  other  mammalian  order  in  the  number  of  in- 
dividuals. They  have  no  canine  teeth,  but  strongly  developed  incisors. 
Only  the  front  of  the  incisors  is  covered  with  enamel,  which  keeps 
them  sharp  and  chisel-like,  owing  to  the  more  rapid  wearing  away  of 
the  softer  dentine.  The  incisor  teeth  continue  to  grow  throughout  the 
life  of  the  animal.  The  most  extensive  family  of  rodents  is  the  Muridae, 
Avhich   includes  the  true  rats   and  mice,   typified   by  the  genus   Mus. 

'"Walker:     Indian  Med.  Oaz.,  1910,  No.  3,  p.  93. 

"Notes  on  the  Development  of  Bacillusi  pestis  in  Bugs  (Cimex  Lectularius) 
and  Their  Power  to  Convey  Infection,  Jour.  Hyg.,  Plague  Supplement  IV,  1915, 
p.  779. 


EATS  AND  OTHER  liODP^NTS  329 

Trouessart,  in  liis  "('atal()^''us  inaiiinialiuni,"  enumerates  250  species  of 
Mtis  described  before  1905,  Since  that  date  a  number  of  new  forms 
have  been  described. 

The  genus  Mas  is  characterized  by  narrow,  ungrooved  incisors;  three 
small-rooted  molars;  soft  fur  mixed  with  hairs,  sometimes  with  spines; 
a  rudimentary  pollcx  (thumb)  having  a  short  nail  instead  of  a  claw; 
a  long  tail  bearing  rings  or  overlapping  scales  and  often  naked  or 
nearly  so.  The  ears  are  rather  large,  the  eyes  bright  and  prominent, 
and  the  muzzle  somewhat  pointed. 

The  distinction  between  rats  and  mice  is  arbitrary  and  based  on 
size.  Of  the  many  species  of  the  genus  Mus  only  three  or  four  have 
developed  the  ability  to  adapt  themselves  to  such  a  variety  of  condi- 
tions as  to  become  cosmopolitan.  Four  have  found  lodgment  in 
America : 

The  common  house  mouse,  Mus  musculus. 

The  English  black  rat,  Mus  rattus. 

The  Egyptian  or  roof  rat,  Mu^  alexandrinus. 

The  brown  rat,  Mus  norvegicus  (formerly  decumarms) . 

The  black  rat  and  the  roof  rat  differ  from  each  other  mostly  in 
color,  and  some  zoologists  regard  them  as  races  of  the  same  species. 
The  brown  rat  is  also  known  as  the  gray  rat,  barn  rat,  wharf  rat,  sewer 
rat,  and  Norway  rat. 

The  black  rat  (Mus  rattus)  has  been  known  in  Europe  since  the 
twelfth  century,  and  from  there  has  been  carried  to  America.  The 
brown  rat  (Mus  norvegiciis)  came  later,  and,  as  it  is  more  destructive, 
larger,  and  more  ferocious,  it  is  rapidly  driving  the  black  rat  before  it. 
The  brown,  rat  differs  somewhat  in  habits  from  the  black  rat,  especially 
in  that  it  burrows,  which  protects  it  against  its  enemies  and  renders  its 
suppression  more  difficult. 

The  house  mouse  holds  its  own  everywhere  against  the  brown  or 
Norway  rat,  as  it  is  able  to  get  into  holes  too  small  for  the  rat  to  fol- 
low. Albinism  and  melinism  occur  in  all  species;  pied  forms  are  com- 
mon.. The  white  rat  of  the  laboratory  is  an  albino  form  of  either  Mus 
rattus  or  Mus  norvegicus. 

Breeding-  and  Prevalence. — The  bro^^Ti  rat  is  more  prolific  than 
either  the  roof  rat  or  the  black  rat.  The  brown  rat  reproduces  from, 
three  to  five  times  a  year,  each  time  bringing  forth  from  6  to  9, 
and  sometimes  as  many  as  23  or  23,  young.  They  breed  more  rapidly 
in  temperate  and  equable  climates  than  in  those  of  great  variability. 
The  number  of  rats  is  only  limited  by  the  food  supply  and  opportu- 
nities to  nest.  Few  people  have  any  conception  of  the  enormous  num- 
bers of  rats  in  cities  and  on  farms.  Although  few  are  seen  in  the  day 
time,  at  night  they  fairly  swarm  along  river  fronts  and  wharves,  as 


330  mSECT-BOENE  DISEASES 

well  as  in  sewers,  stables,  warehouses,  markets,  and  other  places  where 
food  may  be  found.  A  few  instances  will  illustrate  the  prolific  habits 
and  give  an  idea  of  the  destructive  tendency  of  rats. 

In  1901  an  estate  near  Chichester,  England,  was  badly  infested  with 
rats;''^  31,981  were  killed  by  traps,  poisons,  and  ferrets,  while  it  is  esti- 
mated that  tenants,  at  the  threshing,  destroyed  fully  5,000  more.  Even 
then  the  property  was  by  no  means  free  from  rats. 

During  the  plague  of  rats  on  the  island  of  Jamaica,  in  1833,  the 
number  killed  on  a  single  plantation  in  a  year  was  38,000.''^  The  in- 
jury to  sugar  cane  on  the  island  caused  by  the  animals  was  at  that  time 
estimated  at  half  a  million  dollars  a  year. 

The  report  of  the  Indian  Famine  Commission  in  1881  affords  one 
of  the  best  illustrations  of  the  number  of  rats  that  may  infest  a  coun- 
try. An  extraordinary  number  of  the  animals  at  that  time  inhabited 
the  Southern  Deccan  and  Mahratta  districts  of  India. '^*  The  autumn 
crop  of  1878  and  the  spring  crop  of  1879  were  both  below  the  average, 
and  a  large  portion  of  each  was  destroyed  by  rats.  The  resulting  scarcity 
of  food  led  to  the  payment  of  rewards  for  the  destruction  of  the  pests, 
and  over  12,000,000  were  killed. 

The  average  life  of  a  rat  is  about  two  years. 

Migration. — The  migrations  of  rats  have  often  been  recorded.  The 
brown  rat  is  known  in  Europe  quite  generally  as  the  migratory  rat; 
the  Germans  call  it  the  Wanderraite.  Pallas  relates  that  in  the  autumn 
of  1773  they  arrived  from  the  East  at  Astrakhan,  southeastern  Eussia, 
in  such  great  numbers  and  so  suddenly  that  nothing  could  be  done  to 
oppose  them.  They  crossed  the  Volga  in  immense  troops.  The  cause 
of  this  general  migration  was  attributed  to  an  earthquake,  but,  since 
similar  movements  of  the  same  species  often  occur  without  earthquakes, 
it  is  probable  that  only  the  food  supply  of  the  animals  was  involved 
in  the  migration  which  first  brought  the  brown  rat  to  Europe, 

Seasonable  movements  of  rats  from  houses  and  barns  to  the  open 
fields  take  place  in  the  spring,  when  green  and  succulent  plant  food  is 
ready  for  them.  The  return  movement  takes  place  in  the  autumn. 
This  seasonal  migration  is  notable  even  in  large  cities.  In  1903  a 
multitude  of  migrating  rats  spread  over  several  counties  of  western 
Illinois.  They  traveled  in  great  armies  and  invaded  the  farms  and 
villages  of  Eock  Island  and  Mercer  counties,  and  caused  heavy  losses 
during  the  winter  and  summer  of  1904.  In  one  month  Mr.  Montgomery 
of  Mercer  county  killed  3,435  rats  on  his  farm.  He  caught  most  of 
them  in  traps. 

In  England  a  general  movement  of  rats  inland  from  the  coast  oc- 

"  The  Field,  London,  Vol.  C,  p.  545,  1902. 
'^New  England  Farmer,  Vol.  XII,  p.  315,  1834. 
""'British  Med.  Jour.,  Sept.  16,  1905,  p.  623. 


I?ATS  AND  OTHER  EODENTS  331 

curs  every  October.  This  is  known  to  be  closely  connected  with  the 
closing  of  the  herring  season.  During  the  fishing  the  rodents  swarm 
to  the  coast  attracted  by  the  offal  left  in  cleaning  the  herring,  and 
when  this  food  fails  the  animals  troop  back  to  the  farms  and  vil- 
lages. 

An  invasion  of  rats  (Mns  rattus)  in  the  Bermuda  Islands  occurred 
about  the  year  1G15.  Within  two  years  they  had  increased  so  alarmingly 
that  none  of  the  islands  was  free  from  them.  The  rodents  "devoured 
everything  that  came  in  their  way — fruits,  plants,  and  even  trees" — so 
that  for  a  year  or  two  the  people  were  nearly  destitute  of  food,  A  law 
was  passed  requiring  every  man  in  the  island  to  keep  12  traps.  In 
spite  of  all  efforts  the  animals  continued  to  increase;  but  they  finally 
disappeared,  so  suddenly  that  it  is  supposed  they  must  have  been  vic- 
tims of  a  pestilence. 

While  stationed  upon  Angel  Island  in  San  Francisco  harbor  I  ob- 
served several  migrations  of  rats  between  the  army  post  and  the  quar- 
antine station,  which  were  about  a  mile  apart  and  separated  by  an  in- 
tervening ridge.  Everyone  is  familiar  with  the  sudden  invasion  of 
stores,  factories,  and  other  structures  with  these  rodent  pests,  which 
causes  considerable  economic  loss. 

On  Vessels. — Eats  are  found  on  all  vessels;  they  are  great  travelers. 
It  is  through  this  seagoing  tendency  that  the  rat  has  become  cosmo- 
politan. Eats  get  on  board  vessels  readily  as  they  lie  at  their  dock; 
sometimes  they  are  carried  on  board  in  the  cargo. 

It  is  very  important  to  prevent  the  introduction  of  rats  on  vessels 
at  plague-infected  ports;  it  is  also  important  to  prevent  the  passage  of 
rats  from  ship  to  shore,  particularly  if  the  vessel  is  from  a  plague  port. 
In  order  to  accomplish  this,  it  is  necessary  to  exercise  particular  care. 
In  extreme  cases  the  ship  should  not  approach  the  dock,  but  the  cargo 
should  be  handled  by  means  of  lighters.  When  the  ship  lies  at  its 
moorings  in  a  stream  or  in  the  open  bay,  rats  may  get  on  board  by 
swimming,  and  climbing  in  through  the  hawse  pipe.  Eats  rarely  swim 
more  than  one-quarter  to  one-third  of  a  mile.  If  the  vessel  ties  up  at 
the  dock,  inverted  funnels  should  be  placed  on  the  hawsers.  The  gang- 
planks should  be  watched  during  the  day  and  always  taken  up  at  night. 
Vessels  from  plague  ports  should  always  be  treated  wnth  sulphur  dioxid, 
preferably  when  empty,  and  always  before  leaving,  and  also  en  route,- 
to  kill  the  rats  that  may  be  on  board.  A  wise  measure  in  international 
sanitation  would  be  to  require  all  vessels,  whether  trading  at  plague 
ports  or  not,  to  fumigate  for  rats  no  less  than  three  or  four  times  a  year. 
For  destruction  of  rats  on  vessels,  see  page  505. 

Food. — Eats  are  not  strictly  herbivorous,  as  might  be  inferred  from 
their  dentition;  they  are  practically  omnivorous.  Their  bill  of  fare  in- 
cludes grains  and  seeds  of  every  kind ;  flour_,  meal,  and  all  food  products 


332  INSECT-BORNE  DISEASES 

made  from  them;  garden  vegetables,  mushrooms,  bark  of  growing  trees, 
bulbs,  roots,  stems,  leaves,  and  flowers  of  herbaceous  plants;  eggs,  chick- 
ens, ducklings,  squabs,  and  young  rabbits,  milk,  butter,  and  cheese; 
fresh  meat  and  carrion;  fish,  frogs,  mollusks,  and  crustaceans;  they  are 
also  cannibals.  This  great  variety  of  food  explains  the  ease  with  which 
rats  maintain  themselves  in  almost  any  environment. 

Habits. — The  roof  rat  (Mus  alexandrinus)  and  the  black  rat  {Mus 
rattiis)  are  more  expert  climbers  than  the  brown  rat,  which  is  larger 
and  clumsier.  In  buildings  the  brown  rat  keeps  mainly  to  the  cellar 
and  lower  parts,  where  it  commonly  lives  in  burrows.  From  these  re- 
treats it  makes  nightly  excursions  in  search  of  food.  The  roof  rat  and 
the  black  rat  live  in  the  walls  or  in  the  space  between  ceilings  and  roofs. 
Eats  readily  climb  trees  to  obtain  fruit.  In  the  tropics  the  roof  rat 
and  the  black  rat  habitually  nest  in  trees.  In  the  open,  rats  seem  to 
have  defective  vision ;  by  daylight  they  move  slowly  and  uncertainly ; 
on  the  contrary,  at  the  side  of  the  room  and  in  contact  with  the  wall 
they  run  with  great  celerity.  This  fact  suggests  that  the  vihrissae 
(whiskers)  serve  as  feelers,  and  that  the  sense  of  touch  in  them  is  ex- 
tremely delicate.  The  animals  always  prefer  narrow  places  as  high- 
ways— another  circumstance  which  may  be  made  use  of  in  placing 
traps. 

The  ferocity  of  rats  has  been  grossly  exaggerated.  They  fight  fiercely 
when  cornered.  They  sometimes  bite  sleeping  infants  and  adults.  Ordi- 
narily the  probability  of  being  bitten  by  rats  is  remote,  and  the  bite  is 
not  usually  poisonous.  Miyake "  has  described  a  "rat-bite  disease," 
called  in  Japan  Sodoku,  or  rat -bite  fever. 

Rat-Bite  Fever. — Rat -bite  fever  is  '^'^  a  rare  and  curious  infection 
sometimes  following  a  rat  bite.  In  all  only  80  cases  of  human  infection 
have  been  reported  in  the  literature  up  to  1918.  The  symptoms  come  on 
after  the  wound  has  healed.  There  is  inflammation  of  the  bitten  part 
with  swelling  of  the  lymph  glands,  paroxysms  of  fever  of  the  relapsing 
type  which  may  last  a  very  long  time,  and  an  eruption  of  the  skin 
which  usually  occurs  during  the  second  febrile  paroxysm.  The  case 
fatality  is  about  10  per  cent. 

The  cause  of  rat-bite  fever  is  probably  a  spirochete  described  by 
Japanese  investigators — Spirochaeta  morsus  muris.''''  This  spirochete 
is  found  in  the  blood  of  rats  and  also  in  human  cases.  It  is  not  found 
in  the  saliva  of  infected  rats  and  the  infection  is  supposed  to  be  trans- 
mitted during  the  bite  by  blood  caused  by  wounds  of  the  gums.  Bear- 
ing upon  a  spirochete  as  the  cause  of  this  infection,   salvarsan  seems 

"  Mitt.  a.  d.  Grenzgeb.  d.  Med.  u.  Cliir.,  1902 ;  also  Proescher,  Internat.  Clin- 
ics, IV,  25th  Series,  p.  77. 

''^Journ.  Exp.  Medicine,  Vol.  XXIII,  No.  1,  January  1,  1916,  p.  39. 

'"Ibid.,  1916,  XXIII,  p.  249;  1917,  XXV,  No.  1,  p.  33;  1917,  XXV,  No.  1, 
p.  45;   1919,  XXXI,  No.  4,  p.  366. 


RATS  AND  OTHER  RODENTS  333 

to  be  specific  in  the  experimental  disease  in  animals;  favorable  results 
are  reported  for  man. 

Other  infections  may  follow  rat  bites.  Thus,  SchottmuUer  in  1914 
described  SireptofhHx  rnuris-  niKi.  The  same  or  a  similar  streptothrix 
was  also  found  by  Blake  in  a  fatal  case  at  the  Peter  Bent  Brigham  Hos- 
pital in  Boston,  by  Ruth  Tunnicliff  in  Chicago,  and  by  Tileston  in  New 
Haven.  Acute  infectious  jaundice,  due  to  the  Spirochaeta  icterohemor- 
rhagiae,  is  an  infection  of  rats  transmitted  to  man.  The  disease  occurs 
ill  outljroaks,  oppocially  among  troops,  and  is  discussed  on  page  335. 

Pla^e  in  Rats. — Tt  is  now  known  that  rat  fleas  are  responsible  for 
most  cases  of  human  plague  of  the  bubonic  type,  and  in  addition  are  the 
most"  frequent  medium  by  which  plague  is  carried  from  one  locality  to 
another.  They  also  convey  the  plague  infection  to  other  rodents,  such 
as  ground  squirrels. 

The  clinical  manifestations  of  plague  in  rats  are  not  very  evident. 
It  is  generally  said  that  a  plague-infected  rat  staggers  about  with  a 
drunken  gait,  loses  fear  of  its  natural  enemies,  and  is  readily  captured. 
Rats  experimentally  infected  show  no  marked  manifestations  of  illness 
until  shortly  before  death,  when  they  become  quiet,  crouch  in  the  cor- 
ner of  the  cage,  and  try  to  hide.  It  is  rather  surprising  that  compara- 
tively few  dead  plague  rats  are  found  in  endemic  centers.  In  the  San 
Francisco  campaign  ^IcCoy  estimates  that  certainly  not  more  than  20 
per  cent,  of  the  infected  rodents  were  found  dead,  the  remainder  being 
trapped. 

Rats  suffer  both  with  acute  plague  and  chronic  plague,  the  lesions 
of  which,  differ. 

The  diagnosis  of  plague  in.  rats  may  be  made  macroscopically.  The 
Indian  Plague  Commission,  which  had  the  opportunity  of  examining  an 
enormous  number  of  plague  rats  in  Bombay  and  elsewhere  in  India,  state 
that  "the  results  of  tests  carried  out  for  the  purpose  of  comparison 
make  it  manifest  that  the  naked  eye  is  markedly  superior  to  the  micro- 
scopic method  as  an  aid  in  diagnosis,  and  as  the  result  of  our  experi- 
ence we  are  prepared  to  make  a  diagnosis  of  plague  on  the  strength  of 
the  macroscopical  appearance  alone,  even  though  the  other  results  of 
cutaneous  inoculation  and  culture  are  negative  and  the  animals  show 
signs  of  putrefaction."  The  experience  of  McCoy  and  others  in  the 
Federal  Plague  Laboratory  in  San  Francisco  leads  to  the  same  conclu- 
sion. It  should  be  remembered,  however,  that  occasionally  plague  oc- 
curs in  rats  without  gross  lesions.  This  has  been  observed  by  Dunbar 
and  Kister  and  also  b}'  McCoy.  In  any  critical  case  the  bacteriological 
confirmation  is  essential. 

Acute  plague  in  rats  is  characterized  by  engorgement  of  the  subcu- 
taneous blood  vessels  and  a  diffuse  pink  color  of  the  subcutaneous 
structures  and  muscles.     The  diagnosis  may  often  be  inferred  at  the 


334  INSECT-BORNE  DISEASES 

first  incision.  The  lymphatic  glands  of  the  neck,  axilla,  groin,  or  pel- 
vis are  enlarged  and  frequently  surrounded  by  a  hemorrhagic  exudate 
and  edema.  The  liver  is  granular  with  focal  necroses,  the  spleen  en- 
larged and  friable,  and  pleural  effusions  are  common. 

.  Chronic  plague  in  rats  has  been  encountered  in  a  considerable  num- 
ber of  cases  among  Mus  rattus  in  the  Punjab  villages  of  Kasel  and 
Dhand.  It  has  not  been  found  in  California.  In  the  chronic  disease 
the  lesions  consist  of  purulent  or  caseous  foci,  usually  of  the  visceral 
type;  that  is,  they  occur  as  splenic  nodules  and  abscesses,  or  mesenteric 
abscesses.  Sometimes  the  abscesses  are  situated  in  the  regions  of  the 
peripheral  lymph  glands.  Plague  bacilli  are  either  absent  or  very 
scanty  upon  microscopic  examination  in  these  abscesses,  but  they  may 
be  recovered  by  cultural  methods  or  more  surely  by  inoculating  the 
material  into  susceptible  animals.  There  is  no  evidence  to  show  that 
chronic  rat  plague  has  anything  to  do  with  the  recurrence  of  acu-te  plague 
among  the  rats. 

Eats  may  be  infected  by  the  ingestion  of  infective  material  or  the 
application  of  virulent  plague  bacilli  to  a  mucous  or  cutaneous  surface, 
or  by  subcutaneous  injection  of  the  microorganism.  The  infection  may 
also  be  transferred  from  rat  to  rat  through  the  agency  of  the  flea.  In 
nature  the  mode  of  transference  probably  takes  place  through  all  of 
these  methods,  but  commonly  through  the  flea. 

Contrary  to  the  general  impression,  the  wild  rat  has  a  considerable 
resistance  to  plague  infection.  The  Indian  Plague  Commission  found 
that  59  per  cent,  were  immune  when  inoculated  by  the  subcutaneous 
method  from  the  spleen  of  infected  rats.  A  series  of  experiments  con- 
ducted in  the  Federal  laboratory  in  San  Francisco  also  showed  a  high 
grade  of  immunity,  especially  among  the  large  rats.  About  15  per 
cent,  of  small  rats  and  about  50  per  cent,  of  large  rats  were  found  to 
be  immune  when  inoculated  with  highly  virulent  material.  The  experi- 
ments demonstrated  that  this  immunity  is  not  acquired  through  a  prior 
attack  of  the  disease,  but  must  be  a  natural  immunity. 

The  natural  subsidence  of  plague  among  rats  in  any  community  is  a 
point  about  which  much  more  evidence  must  be  obtained  before  we  can 
speak  with  any  degree  of  authority.  It  may  be  due  to  a  lack  of  suscep- 
tible material,  possibly  to  a  loss  of  virulence  of  the  organism,  but  it 
seems  more  probable  that  it  is  due  to  a  change  in  the  number  or  ac- 
tivities of  the  rat  fleas. 

In  a  rat  survey  to  determine  the  existence  of  plague  the  number  of 
rats  examined  should  be  at  least  1,000  for  every  10,000  of  the  human 
population,  and  a  preliminary  survey  should  be  made  in  order  that  the 
most  promising  locations  shall  be  trapped. 


RAT-BOENE  DISEASES  335 

RAT-BORNE  DISEASES 

ACUTE  ISFECTIOUS  JAUNDICE''^ 
(Epidemic  Catarrhal  Jaundice — Weil's  Disease.) 

Infectious  jaundice,  or  ei)idemic  catarrhal  jaundice,  has  been  known 
for  a  long  time  to  occur  among  troops,  among  sewer  workers,  among 
miners,  and  among  agricultural  laborers  working  in  wet  soil,  as  rice 
planters;  also  people  who  handle  food,  at  least  in  Japan,  are  said  to 
be  attacked  with  especial  frequency.  It  was  recognized  as  a  clinical 
entity  by  Ozenam,  1849 ;  Monneret,  1859 ;  Laverau,  1865 ;  Lancerau, 
1883;  Landouzy,  1882;  :\rathieu,  1886;  and  Weil,  1886,  who  described 
four  cases  M'ith  typical  s}Tnptoms;  the  disease  is  very  often  called 
by  his  name. 

It  is  an  acute  infection,  caused  by  the  Spirochaeta  icterohaemorrha- 
giae,  and  characterized  by  malaise,  prostration  and  gastro-intestinal 
symptoms  at  the  onset;  by  fever  of  varying  degree,  and  by  jaundice  of 
varying  intensity  and  duration.  In  severe  cases  bleeding  from  mucous 
surfaces  and  albuminuria  are  common.  Light  cases  are  clinically 
indistinguishable  from  ordinary  catarrhal  jaundice. 

In  most  outbreaks  the  mortality  is  low,  but  in  Japan  the  infection 
is  both  more  prevalent  and  more  virulent  than  in  Europe  or  America. 
Among  the  Japanese  the  case  fatality  rate  is  as  high  as  38  per  cent., 
while  in  European  soldiers  in  the  Great  "War  it  did  not  exceed  2  or  3 
per  cent.  The  infection  is  endemic  on  all  continents  among  rats.  The 
disease  in  man  is  associated  with  moist  soil  and  moderate  temperature; 
that  is,  few  cases  occur  in  the  hottest  or  coldest  weather.  Sporadic 
cases  are  recorded,  but  usually  the  disease  occurs  in  epidemic  form,  often 
with  a  high  attack  incidence. 

The  cause  of  acute  infectious  jaundice  is  the  Spirochaeta  icterohaem- 
orrliagiae  of  Inada,'^  (1916)  and  his  co-workers.  Xoguchi ''^  believes 
the  spirochete  belongs  to  a  special  genus  and  has  named  it  Leptospira 
icteroliaemorrliagiae. 

An  account  of  an  outbreak  of  jaundice  among  troops  in  the  War  of 
1812  has  come  down  to  us.  ISTot  less  than  71,691  cases  occurred  among 
white  troops  of  the  Union  Army  in  the  American  Civil  War.  In  the 
South  African  War  5,61:8  cases  of  epidemic  jaundice  occurred  among' 
the  British  troops.  Many  cases  of  acute  infectious  jaundice  occurred 
among  the  troops  on  both  sides  of  the  Ehine  in.  the  World  War.  It 
prevailed  from  Belgium  to  Gallipoli. 

"*  A  complete  bibliography  to  date  is  contained  in  Neil's  article  on  'The 
Problem  of  Acute  Infectious  Jaundice  in  the  United  States."  U.  S.  Public  Health 
Reports.  Reprint  Xo.  466.  Mar  10,  1918. 

'Wourn.  Exp.  Med.,  XXIII,  377,  Mar.,  1916. 

'^Ibid.,  XXV,  755,  May,  1917. 


336  INSECT-BOENE  DISEASES 

Official  statistics  give  no  adequate  idea  of  the  prevalence  of  this 
disease,  as  large  numbers  of  men  continued  on  duty  throughout  their 
illness.  Eegimental  medical  ofF.cers  have  stated  that  as  many  as  one- 
tenth  of  their  men  actually  in  the  trenches  were  jaundiced.  In  one 
battalion  there  were  100  cases  during  October,  but  only  36  were  regarded 
as  of  sufficient  severity  to  be  sent  into  a  field  ambulance.  It  was  called 
trench  jaundice.  A  number  of  epidemics  of  catarrhal  jaundice  have 
been  reported  among  the  civil  population  of  the  United  States.  A  list  of 
these  outbreaks  is  given  by  Neil.^° 

The  Relation  of  the  Disease  to  the  Rat. — Acute  infectious  jaundice 
is  a  disease  primarily  of  rats,  secondarily  of  man.  About  10  per  cent, 
or  more  of  all  wild  rats,  wherever  examined,  harbor  the  spirochetes. 
Eats  have  a  remarkable  immunity  to  the  infection,  gained  perhaps 
through  long  association  between  parasite  and  host.  The  spirochetes 
live  in  the  kidneys  of  the  rats  and  are  excreted  in  the  urine.  They  have 
also  been  found  in  the  blood  and  other  organs,  and  in  the  mouth. 

Noguchi  found  the  spirochetes  in  rats  caught  about  the  Bronx; 
Jobling  and  Eggstein  found  10  per  cent,  of  the  rats  examined  in  ISTash- 
ville  to  be  infected;  Neil  10  per  cent,  of  the  rats  in  Washington;  and 
Otteraaen  found  the  parasites  in  the  rats  of  Chicago.  This,  therefore, 
reveals  a  latent  danger  to  which  we  have  been  constantly  exposed,  but 
from  which  we  can  escape  as  long  as  sanitary  conditions  are  satisfactory. 

The  credit  of  first  finding  the  Spirochaeia  icterohaemorrliagiae  in 
rodents  belongs  to  the  Japanese  investigators  who  first  demonstrated 
these  parasites  in  the  kidneys  of  field  mice.  Further  investigations  in 
the  coal  mining  regions  of  Japan  showed  that  40  per  cent,  of  the  wild 
rats  harbored  the  organism,  and  that  many  cases  of  infectious  jaundice 
in  human  beings  occur  in  this  region. 

Transmission. — Just  how  the  disease  is  usually  transmitted  from 
rat  to  rat  and  from  rat  to  man  is  not  entirely  clear.  There  are  several 
possibilities.  There  is  scant  evidence  that  the  infection  is  transmitted 
from  man  to  man. 

The  spirochete  is  found  in  the  kidney  of  the  rat  and  is  excreted  in 
the  urine  which  contaminates  the  soil,  and  infection  takes  place  either 
through  the  skin  or  by  the  mouth.  Susceptible  animals  may  be  in- 
fected by  either  route.  The  infection  will  pass  through  the  unbroken 
skin  of  guinea-pigs.  The  spirochete  is  frail,*^  but  may  live  thre3  days 
in  moist  soil;  it  soon  dies  when  dried.  This  probably  explains  the 
relation  of  the  infection  to  moist  soil  and  a  moderate  temperature.  It 
also  makes  clear  the  reason  why  the  wet  trenches,  overrun  with  rats, 
favored  the  transfer  of  the  disease  from  rats  to  man  during  the 
World  War. 

^TJ.  8.  PuhliG  Health  Reports,  May  10,  1918. 
^Journ.  Exp.  Med.,  May  1,  1918,  p.  609. 


RAT-B01?NE  DISEASES  337 

The  spirochete  lias  hrt-ii  found  in  the  mouth  of  rats  and  the  infec- 
tion has  heen  transmitted  to  guinea-pigs  by  the  bites  of  sudi  rats.  This 
probably  is  not  the  usual  method  of  spread  in  nature, 

Foulerton  ^~  found  Spirochaefa  {cferohaemorrhngine  in  the  fcccii.  of  in- 
fected guinea-pigs,  and  its  presence  in  the  feces  of  cases  of  spirochetal 
jaundice  in  man  may  be  assumed. 

Tliere  is  no  adequate  evidence  that  any  insect  plays  a  part  in  the 
transmission  of  the  disease,  although  the  experimental  evidence  in  thii 
regard  is  by  no  means  complete. 

rreveniion  consists  in  warfare  against  rats  (page  338).  The  disea-se 
is  not  known  to  he  communicated  directly  from  man  to  man.  Sanitation 
both  in  civil  and  military  life  to  guard  against  contamination  with  rat 
excrement  is  an  essential  element  of  prophylaxis.  Shoes  should  be 
worn,  especially  in  wet  soil  and  where  the  infection  abounds.  Food 
must  be  carefully  guarded  against  rats  and  mice,  for  infection  by  the 
mouth  occurs,  and  food  soiled  with  rat  urine  is  hazardous.  The  heat 
of  cooking  is  sufficient  to  kill  the  spirochete.  Prophylaxis  against  this 
disease  is  a  question  of  biologic  cleanliness. 

RAT  LEPROSY 

An  infection  resembling  leprosy  occurs  spontaneously  among  rats 
and  bears  a  close  resemblance  to  the  disease  in  man,  but  it  seems  that  rat 
leprosy  is  not  communicable  to  man.  For  a  fiirther  discussion  of  rat 
leprosy  see  page  414. 

TRICHINOSIS 

The  three  most  important  hosts  for  the  Trichinella  spiralis  are  man, 
swine,  and  rats.  The  infection  is  spread  by  one  animal  eating  the  flesh 
of  another.  It  is,  therefore,  evident  that  if  the  disease  occurred  only  in 
hogs  and  man  it  could  be  controlled.  Hence,  a  well-directed  public  health 
campaign  against  trichinosis  shonld  consider  the  eradication  of  rats,  es- 
pecially around  slaughter  houses,  butcher  shops,  hog  pens,  and  similar 
places. 

Trichinosis  is  very  common  among  rats;  they  become  infected  by  ' 
eating  each  other,  by  eating  scraps  of  pork  found  on  the  otfal  pile  of 
slaughter  houses,  butcher  shops,  or  in  swill.  Swine  become  infected  by 
eating  rats  and  infected  offal.  Man  becomes  infected  almost  exclusively 
b}^  eating  pork  or  boar  meat  that  has  not  been  thoroughly  cooked.  See 
page  830. 

Food  infection  due  to  the  Gaertner  group  of  bacilli  may  be  associated 
with  rats  and  mice,  for  these  rodents  may  be  carriers  of  these  micro- 
organisms. The  opportunity  for  food  to  become  contaminated  with  rat 
and  mice  feces  is  frequent  in  the  slaughter  house  and  butcher  shop,  in 

*Voi/r.  Pathol,  and  Bacieriol.,  Vol.  XXIII,  Xo.  78,  October,  1919. 


338  INSECT-BORNE  DISEASES 

the  grocery  and  home,  and  in  storage  and  transportation.     See  page  704. 

Other  Parasites. — Eats  and  mice  may  harbor  eleven  species  of  inter- 
nal parasites  which  also  occur  in  man.  Several  of  these  are  of  academic 
importance  only. 

Those  vi^hich  concern  ns  principally,  in  addition  to  TrichinsUa  spi- 
ralis, are  Hymenolepis  nana,  Tlymenolepis  diminvia,  and  Lamblia  in- 
testinalis.  Eats  are  also  susceptible  to  experimental  infection  with 
Trypanosoma  gamhiense,  the  cause  of  sleeping  sickness,  but  are  not 
known  to  play  any  part  in  the  spread  of  this  disease  under  natural  con- 
ditions. 

Lynch  ®^  states  that  the  rat  (Mus  norvegicus)  suffers  from  spon- 
taneous amebic  dysentery  similar  to  that  occurring  in  man.  The  rat  is, 
therefore,  a  possible  disseminator  of  dysentery  amebas  pathogenic  for 
man. 

Eats  have  also  been  accused  of  dragging  typhoid  from  the  sewers 
to  our  food.  The  connection  is  close  and  the  possibility  apparent.  A 
recent  outbreak  of  typhoid  fever  in  an  asylum  has,  in  fact,  been  traced 
to  this  source  by  Dr.  Mills. ^* 

ECONOMIC  IMPORTANCE 

The  destruction  of  food,  merchandise,  and  property  by  rats  is  so 
great  that  this  alone  would  justify  active  measures  of  suppression, 
even  though  they  were  not  responsible  for  plague,  trichinosis,  and 
other  infections.  Eats  destroy  grain  while  growing;  invade  stores, 
destroy  flowers,  laces,  silks,  carpets;  eat  fruits,  vegetables,  meat,  etc., 
in  the  market;  destroy  by  pollution  ten  times  as  much  as  they  eat; 
cause  conflagration  by  dragging  matches  into  their  holes;  gnaw  lead 
pipes  and  floors  of  houses;  ruin  artificial  ponds  and  embankments  by 
burrowing;  destroy  eggs  and  young  poultry;  damage  foundations,  floors, 
doors,  piers;  in  short,  they  have  become  the  worst  mammalian  pest 
among  us.  It  is  estimated  that  in  the  United  States  alone  the  losses 
due  to  rat  depredations  are  over  $167,000,000  annually  computing  the 
upkeep  of  a  rat  at  one-half  cent  a  day.^^ 

SUPPRESSION  OF  RATS 

The  extermination  of  the  rat  is  hopeless;  they  are  very  intelligent 
and  cautious.  Extermination  seems  a  biological  impossibility,  for 
killing  off  large  numbers  gives  the  survivors  an  easier  living.  Mil- 
lions of  rats  have  been  killed  in  India,  Japan,  San  Francisco, 
and  other  places  during  the  recent  plague  measures  without  making 

«Jow.  A.  M.  A.,  LXV,  No.  26.  Dec.  25,  1915,  p.  2232. 
^*Brit.  Med.  Jour.,  January  21.   1911. 
^^Publio  Health  Bull.  No.  103,  June,  1919, 


SUPPRESSION  OF  RATS  33d 

an  appreciable  impress  upon  the  numbers  remaining.  They  may  be 
exterminated  and  kept  out  of  a  limited  area,  such  as  a  ship,  a  granary, 
a  stable,  a  warehouse,  a  nuirket,  or  local  compound.  In  the  well-built 
residential  sections  of  a  city,  with  concrete  walks,  asphalt  streets,  stone 
cellars,  and  few  stables,  there  are  very  few  rats.  In  ten  years  of  resi- 
dence in  such  a  district  in  Washington  I  never  saw  or  heard  of  one  in 
the  neighborhood.  Mtis  rattus  and  Mus  alexandrinus  are  much  more 
difficult  to  suppress  than  Mus  norvegicus;  indeed  it  is  probable  that  we 
have  no  very  satisfactory  method  of  dealing  with  these  rats,  owing  to  the 
fact  that  frequently  they  live  in  trees  and  in  the  fields. 

The  measures  for  the  repression  and  destruction  of  rats  will  be 
considered  under:  (1)  rat-proof  buildings,  (2)  keeping  food  from  rats, 
(3)  natural  enemies,  (4)  traps,  (5)  poisons,  (6)  domestic  animals,  (7) 
shooting,  (8)  fumigation,  and  (9)  bacterial  viruses. 

Rat-proof  Building^s. — This  is  a  measure  of  first  importance  in 
the  fight  against  rats.  Eats  can  only  gain  entrance  to  a  cement  struc- 
ture properly  constructed  through  neglect  or  ignorance.  They  come  in 
through  drain  pipes  if  left  open;  through  doors,  especially  from  alleys; 
and  through  basement  windows.  Once  in,  they  intrench  themselves  in 
out-of-the-way  places,  nest  behind  rubbish,  and  are  difficult  to  dislodge. 
The  lower  parts  of  the  outer  doors  of  public  structures,  such  as  markets 
and  wharves,  should  be  reenforced  with  metal  to  keep  the  rats  from 
gnawing  through.  Basement  windows  should  be  screened  and  doors 
provided  with  springs  to  keep  them  closed.  Screens  or  wire  cloth  to 
keep  out  the  rats  must  be  not  less  than  20  gauge  nor  greater  than  %  an 
inch  mesh.  The  special  points  of  ingress  and  egress  of  rats  which  must 
be  guarded  against  besides  basement  windows  and  doors  are  hatches, 
ventilators,  skylights,  unused  chimney  flues,  and  openings  around  water, 
sewer,  gas,  and  steam  pipes,  and  electric  wires. 

Foundation  walls  should  be  laid  without  a  break  around  the  entire 
building  and  should  extend  not  less  than  18  inches  beneath  the  surface 
of  the  surrounding  soil,  and  should  always  be  flush  with  the  under- 
surface  of  the  floor  above.  Floor  joists  should  be  imbedded  in  this  wall 
or  the  spaces  between  the  joists  filled  in  and  completely  closed  up  to  the 
floor  level.  Ground  areas  should  be  concreted  with  a  layer  at  least  3 
inches  in  thickness,  finished  with  a  wearing  surface  of  cement  about 
%  an  inch  thick.  The  walls  of  a  wooden  house  should  have  one  foot 
of  concrete  between  the  sheathing  and  lathing.  All  water  and  drain 
pipes  should  be  surrounded  with  cement  where  they  pierce  the  walls. 
Eat  holes  may  be  closed  with  a  mixture  of  cement,  sand,  and  broken 
glass,  or  sharp  bits  of  crockery  and  stone. 

Buildings  may  be  raised  from  the  surface  of  the  ground  on  piers, 
thus  rendering  them  rat-proof.  Cribs  for  grain  in  the  country  can  be 
so  raised  and  further  protected  with  metal  netting. 


340  mSECT-BOENE  DISEASES 

Aside  from  dwellings,  the  chief  refuges  for  rats  in  cities  are  sewers, 
wharves,  stables,  provision  houses,  markets,  out-buildings,  slaughter 
houses,  restaurant  kitchens,  bakery  shops,  candy  factories,  and  uninhab- 
ited structures.  Modern  sewers  are  highways  and  not  nesting  places  for 
rats.  They  find  a  safe  retreat  from  nearly  all  enemies  under  wooden 
sidewalks.  In  the  country  it  is  important  to  build  corn  cribs,  barns,  and 
granaries  rat-proof  with  the  liberal  use  of  cement,  iron  sheeting,  or 
galvanized  iron  netting. 

Keeping  Food  from  Rats. — Well-fed  rats  mature  quickly,  breed 
often,  and  have  large  litters.  A  scarcity  of  food  helps  all  other  sup- 
pressive measures.  Garbage  and  offal  must  be  disposed  of  so  that  rats 
cannot  get  at  such  stuff.  Well-covered  garbage  cans  should  be  required 
and  the  garbage  frequently  removed  and  burned.  To  deposit  it  upon 
the  ground  anywhere  only  invites  and  nourishes  rats  and  other  vermin. 
Slaughter  houses  are  centers  of  rat  propagation.  The  offal  is  best  dis- 
posed of  by  burning.  Care  should  also  be  taken  as  to  the  disposal  of 
remnants  of  lunches  in  office  buildings  and  the  disposal  of  organic  waste 
generally.    Produce  in  provision  stores  may  be  protected  with  wire  cages. 

Natural  Enemies. — The  natural  enemies  of  the  rat  are  the  larger 
hawks,  owls,  snakes,  skunks,  foxes,  coyotes,  weasels,  minks,  dogs,  cats, 
and  ferrets.  The  persistent  killing  off  of  the  carnivorous  birds  and 
mammals  that  prey  upon  rats  has  been  an  important  factor  in  the 
increase  of  these  rodents  in  the  United  States.  Eats  actually  destroy 
more  eggs,  chickens,  and  game  than  all  the  wild  animals  combined. 

Traps. — There  are  many  kinds  of  traps,  such  as  the  guillotine,  spring 
trap,  the  cage  trap,  the  barrel  and  pit  trap.  One  of  the  best  is  the  old- 
fashioned  wire  cage  trap.  The  rats  get  in  but  cannot  get  out.  In  plac- 
ing the  trap  it  is  advisable  to  leave  a  rat  in  as  a  decoy.  The  trap  should 
be  placed  along  runways,  or  the  entrance  to  the  trap  may  be  arranged  so 
that  the  rats  first  have  to  go  through  a  pipe,  as  they  like  to  explore 
dark  passages.  It  requires  ingenuity  to  trap  rats  successfully.  They 
are  very  wary  and  avoid  man-smell.  To  guard  against  this  the  traps 
may  be  burned  and  then  smeared  with  the  bait,  always  handling  them 
with  tongs  or  properly  prepared  gloves.  Cheese,  bacon,  grain,  and  also 
meat,  vegetables,  or  bread  are  the  best  baits. 

Poisons. — Poisons  are  objectionable  in  dwellings,  owing  to  the  odor 
of  the  dead  rats.  They  are  of  service  in  granaries,  stables,  wharves, 
storage  depots,  garbage  dumps  and  similar  places  where  rat-proofing  is 
difficult  or  too  expensive.  Most  rat  poisons  are  dangerous  to  children 
as  well  as  to  chickens  and  other  domestic  animals,  and,  therefore,  the 
greatest  care  must  be  exercised  in  their  use.  It  requires  experience  in 
laying  out  poisons;  the  old  rats  are  very  smart  and  will  refuse  the  bait 
unless  artfully  concealed  and  judiciously  placed. 

The  principal  poisons  used  for  rats  are  barium  carbonate,  strychnin. 


SUPPRESSION"  OF  EATS  341 

arsenic,  and  phosphorus.  In  several  states  the  hiw  requires  that  notice 
of  intention  to  lay  poison  must  be  given  to  persons  living  in  the  neigh- 
borhood. Poisons  for  rats  should  never  be  placed  in  open  or  unsheltered 
places.  In  buildings  and  yards  occupied  by  poultry  the  following  pro- 
cedure is  recommended:  Two  wooden  boxes  should  be  used,  one  con- 
siderably larger  than  the  other,  and  each  having  two  or  more  holes  in  the 
sides  large  enough  to  admit  rats.  The  poisoned  bait  should  be  placed 
in  the  bottom  and  near  ilie  middle  of  the  smaller  box,  and  the  larger 
box  should  then  be  inverted  over  tlie  other.  Eats  thus  have  free  access 
to  the  bait,  but  fowls  are  excluded. 

The  cheapest  and  most  eJTective  poison  is  Itarium  carbonate.  This 
may  be  made  into  a  dough  with  four  parts  of  meal  or  flour  to  one  part 
of  barium  carbonate.  A  good  plan  is  to  spread  the  barium  carl)onate 
upon  fish,  on  toasted  bread  (moistened),  or  upon  ordinary  bread  and 
butter. 

Strychnin  is  effective  and  may  be  used  by  inserting  the  dry  crystals 
in  a  piece  of  meat,  cheese,  or  sausage,  which  is  placed  in  the  runways. 

Arsenic  is  popular;  the  powdered  white  arsenic  (arsenious  acid) 
may  be  used  as  described  for  strychnin  or  barium;  or  a  stiff  dough 
may  be  made  by  mixing  twelve  parts  by  weight  of  corn  meal  and  one 
part  of  arsenic  with  white '  of  egg.  An  old  English  formula  is  one 
pound  of  oatmeal,  one  pound  of  brown  sugar,  and  a  spoonful  of 
arsenic. 

Phosphorus  is  an  effective  and  attractive  bait.  The  yellow  phos- 
phorus in  the  proportion  of  one  to  four  per  cent,  may  be  mixed  with 
glucose  or  other  suitable  material.  Kitano  ^^  soaks  the  phosphorus  into 
bread,  which  is  cut  into  pieces  containing  0.025  gm.  of  phosphorus  per 
piece.  The  use  of  phosphorus  is  very  dangerous  on  account  of  fire. 
Eats  poisoned  with  phosphorus  may  die  on  the  premises  and  decompose, 
contrary  to  the  statements  sometimes  made  in  the  advertisements. 

The  following  formula  is  recommended  as  a  poisonous  bait  for  rats, 
mice,  squirrels,  etc. : 

Strychnin    1  oz. 

Cyanid    of    potassium 2  oz. 

Eggs    1  doz. 

Honey    1  pint 

Wheat  or  barley 30  lbs. 

Stir  eggs  well,  then  mix  in  honey  and  again  stir.  Then  put  in  dry 
powdered  strychnin  and  cyanid  and  stir  until  well  mixed.  Put  wheat 
in  large  box  or  can  and  pour  in  the  mixture  of  poison  and  stir  until 
it  is  well  distributed  over  the  wheat.     Stir  two  or  three  times  during 

^<^Am.  Jour.  Trop.  Dis.,  Ill,  12,  June,  1916,  p.  635. 


343  I]!Q"SECT-BOEFE  DISEASES 

twenty-four  hours,  then  spread  out  and  dry.  Before  putting  it  out  for 
squirrels  add  oil  of  rhodium,  1  dram. 

Poisons  and  traps  reduce  the  number  of  rats  but  do  not  eliminate 
them.  Poisons  and  traps  find  their  greatest  usefulness  in  ridding  large 
rat-proof  structures  of  contained  rats.  Starving  rats  by  keeping  food 
from  them  is  one  of  the  best  methods  of  suppression. 

Domestic  Animals. — A  well-trained  dog  may  be  relied  upon  to 
keep  the  farm  premises  reasonably  free  of  rats.  Small  Irish,  Scotch, 
and  fox  terriers  make  the  best  ratters;  the  ordinary  cur  and  the  larger 
breeds  of  dogs  seldom  develop  the  necessary  qualities  for  ratters. 

However  valuable  cats  may  be  as  mousers,  few  of  them  care  to 
catch  rats.  The  ordinary  house  cat  is  too  well  fed  and  too  lazy  to  un- 
dertake the  capture  of  an  animal  as  formidable  as  the  brown  rat.  Koch 
has  advised  the  breeding  and  distribution  of  cats  capable  and  willing  to 
attack  rats. 

Shooting. — Many  rats. may  be  shot  as  they  come  out  to  forage  about 
sundown.  This  method  is  particularly  effective  in  a  large  building 
which  is  suddenly  overrun  with  the  rodents.  The  shooting  of  a  number 
of  them  upon  two  or  three  successive  nights  discourages  the  remainder, 
who  leave  for  some  other  happier  hunting  ground. 

Tumig-ation. — Eats  may  be  killed  with  certainty  in  any  inclosed 
structure  by  the  use  of  sulphur  dioxid,  carbon  bisulphid,  hydrocyanic 
acid  gas,  or  carbon  monoxid.  The  methods  of  evolving  these  sub- 
stances are  described  in  Section  XII.  Hydrocyanic  acid  gas  or  sulphur 
dioxid  are  particularly  useful  to  destroy  rats  on  board  ships,  in  cellars, 
stables,  sewers,  and  places  where  they  abound.  Enormous  numbers  of 
rats  are  frequently  killed  when  ships  are  fumigated  with  sulphur  dioxid, 
I  have  seen  buckets  full  thrown  overboard  from  comparatively  small 
vessels.  Hobdy  counted  310  on  a  lumber-carrying  schooner  of  only  260 
tons  burden.  The  S.S.  Minnehaha,  a  vessel  only  nine  months  in  com- 
mission, fumigated  in  London  in  May,  1901,  yielded  a  bag  of  1,700 
rats.     See  pages  513  to  518. 

Carbon  Monoxid. — Carbon  monoxid  is  an  exceedingly  poisonous  gas. 
From  the  fact  that  it  has  no  odor,  it  is  even  more  hazardous  in  practice 
than  hydrocyanic  acid.  Carbon  monoxid  is  fatal  to  all  forms  of  mam- 
malian life,  but  has  no  gernricidal  properties  whatever.  It  has  been 
used  in  Hamburg  ^^  and  other  ports  for  the  destruction  of  rats  on  ships. 

Carbon  monoxid  is  a  colorless,  odorless  gas,  lighter  than  air.  It 
forms  a  stable  compound  with  the  hemoglobin  of  the  blood — carbon 
monoxid-hemoglobin.  For  the  toxic  action  of  this  gas  and  its  other 
properties  see  page  941.  The  particular  advantages  of  carbon  monoxid 
for  the  destruction  of  rats  on  board  ship  are  that  it  may  be  generated 

^^Nocht  and  Giemsa:  Arheiten  a.  d.  kaiserlichen  Gesundheitsamte,  Bd.  20, 
Erstes  Heft,  1904,  p.  91. 


SUPPEESSION  OF  RATS  343 

cheaply,  is  quickly  effective,  and  docs  no  injury  to  cargo  or  vessel.  The 
disadvantages  are  that  it  is  poisonous  and  inflammable.  The  addition 
of  a  little  sulphur  dioxid  to  the  gas  makes  its  presence  known  and  tends 
to  prevent  accidents.  After  exposure  the  hold  must  be  thoroughly  ven- 
tilated, and  it  is  customary  to  lower  a  mouse  in  a  cage  for  10  minutes 
to  be  sure  that  it  is  safe  for  a  man  to  enter.  Divers'  hehlicts  should 
also  be  kept  in  readiness  so  that  the  bold  may  be  entered  in  case  of 
need. 

A  gas  generator  has  been  made  by  Pintsch  which  furnishes  a  mix- 
ture consisting  of  CO,  5  per  cent.,  COg,  18  per  cent.,  N,  77  per  cent. 
These  gases  are  generated  by  the  incomplete  combustion  of  coke.  The 
mixture  of  gases  is  pumped  into  the  hold  of  the  vessel  or  other  com- 
partments where  it  is  desired.  The  hold  should  be  kept  tightly  closed 
from  7  to  8  hours.    Funnel  gases  are  also  serviceable. 

The  Bacterial  Rat  Viruses. — Eats  are  notoriously  resistant  to  bac- 
terial infection.'^*  Even  plague  usually  fails  markedly  to  diminish 
their  prevalence.  An  epizootic  of  bacterial  nature,  therefore,  cannot  be 
classed  with  the  natural  enemies  of  the  rat.  We  are  not  surprised,  then, 
to  learn  that  the  bacterial  rat  viruses  have  signally  failed  to  accomplish 
their  mission. 

These  bacterial  viruses  belong  to  the  colon-typhoid  group  of  organ- 
isms. They  are  either  identical  with  or  closely  related,  to  the  original 
bacillus  of  mouse  typhoid  (B.  typhi  murium)  discovered  by  LoeflEler,  or 
the  paratyphoid  bacillus,  type  B,  or  the  Bacillus  enteritidis  of  Gaertner, 
which  have  been  associated  with  gastro-intestinal  disorders. 

The  claim  that  these  rat  viruses  are  harmless  to  man  needs  revision, 
in  view  of  the  instances  of  sickness  and  death  reported  by  various  ob- 
servers. The  pathogenicity  for  man  depends  upon  the  virulence  of  the 
culture,  the  amount  ingested,  the  nature  of  the  medium  in  which  it 
grows,  and  many  other  factors. 

Danysz  virus  (B.  typhi  murium)  is  pathogenic  for  rats  under  labora- 
tory conditions,  but  has  feeble  powers  of  propagating  itself  from  rat  to 
rat.  It  rapidly  loses  its  virulence,  especially  when  exposed  to  light  and 
air.  The  result  depends  largely  upon  the  amount  ingested.  The  other 
viruses  have  proved  even  less  satisfactory. 

Under  natural  conditions  these  rat  viruses  may  be  likened  to  a 
chemical  poison,  with  the  great  disadvantage  that  they  rapidly  lose  their  . 
virulence  and  are  comparatively  expensive.  They  also  have  the  further 
disadvantage  that  chemical  poisons  do  not  possess  of  rendering  animals 
immune  by  the  ingestion  of  amounts  that  are  insufficient  to  kill  or  by 
the  ingestion  of  cultures  that  have  lost  their  virulence. 

*'  "The  Inefficiency  of  Bacterial  Viruses  in  the  Extermination  of  Rats,"  M.  J. 
Rosenau.  "The  Rat  and  Its  Relation  to  the  Public  Health,"  Bulletin  of  the 
P.  H.  &  M.  H.  S.,  1910. 


344  mSECT-BORNE  DISEASES 


SQUIRRELS  AND  PLAGUE 

Squirrels. — In  August,  1903,  a  blacksmith  died  of  plague  probably 
contracted  from  a  squirrel  in  Contra  Costa  County,  California.  In 
1904  Currie  demonstrated  the  susceptibility  of  the  ground  squirrel  to 
bubonic  plague.  In  1908  McCoy  and  Wherry  discovered  natural  plague 
in  ground  squirrels.  It  was  then  learned  that  thousands  of  squirrels 
had  died  of  some  disease  during  1904,  1905,  and  1906.  This  epizootic 
was  doubtless  plague.  It  is  now  realized  that  plague  has  become  en- 
demic in  California,  in  the  squirrel.  It  is  also  believed  that  the  disease 
has  been  kept  alive  in  the  endemic  foci  of  Tibet  in  another  rodent,  the 
marmot  (Arctomys  hohac).  The  eradication  of  plague  must,  therefore, 
consider  these  and  perhaps  other  susceptible  wild  animals. 

California  is  overrun  with  three  species  of  ground  squirrels.  The 
commonest  is  the  Citellvs  ieecheyi.  They  live  in  colonies  in  burrows 
or  warrens.  The  booby  owl  is  a  frequent  companion  occupying  the  same 
burrow,  and  they  probably  spread  the  infection  by  carrying  fleas.  Squir- 
rels become  infected  through  fleas  from  each  other  and  from  rats.  The 
squirrel  flea  (Ceratophyllus  acutus)  attacks  man  just  as  the  rat  flea 
does.  The  infection  may  also  be  conveyed  to  man  through  squirrel  bites, 
as  in  the  case  of  the  child  in  Los  Angeles  studied  by  Stimson.  Squir- 
rels make  good  food  for  man,  but  since  the  danger  has  been  realized 
the  shooting  or  trapping  of  them  for  food  purposes  is  now  forbidden 
in  California. 

An  outbreak  of  pneumonic  plague  in  Oakland,  California,  during 
August  and  September,  1919,  started  with  a  man  who  went  squirrel 
hunting  in  Berkeley  Hills  on  August  11th  and  13th,  and  took  ill  August 
15th,     The  outbreak  involved  14  cases,  13  of  whom  died.®^ 

Plague  in  the  squirrel  may  be  recognized  ^°  by  the  gross  anatomical 
lesions  in  the  lymphatic  glands,  the  liver,  and  lungs.  The  pneumonic 
form  of  the  disease  is  common  in  the  squirrel.  Many  cases  are  subacute 
or  chronic.  Smear  preparations  from  squirrels  dead  of  plague  are  fre- 
quently negative  for  plague-like  bacilli.  The  diagnosis  may,  therefore, 
be  made  more  surely  by  animal  experimentation.  Subcutaneous  inocula- 
tion is  surer  than  the  cutaneous  method,  as  the  latter  often  fails  on 
account  of  the  comparatively  few  plague  bacilli  present  in  squirrel 
lesions. 

Squirrels  may  be  destroyed  by  various  means.  One  of  the  most 
successful  is  to  saturate  cotton  waste  the  size  of  an  orange  with  carbon 
bisulphid  and  place  it  in  the  warren;  then  close  the  opening  with  wet 

^*  Kellogg,  W.  H.,  An  Epidemic  of  Pneumonic  Plague.  Am.  Jour.  Pui. 
Health,  July,  1920,  Vol.  X,  No.  7,  p.  599. 

""McCoy:    Jour,  of  Infect.  Dis.,  Nov.  26,  1909,  Vol.  V,  No.  5. 


THE  PLAGUE  345 

clay.  Officers  of  (he  I'ulilic  llcaltli  Service  workiiii,^  in  California  have 
devised  an  apparatus  I'or  vaporizin<i^  carhon  bisul{)hid  and  pumping  the 
gas  into  the  burrows.  This  method  is  reported  to  be  much  more  suc- 
cessful than  any  other  tliat  iias  been  employed.  Poisoned  bait,  such  as 
strychnin,  phosphorus,  or  cyanid  of  potassium,  is  effective.  Traps  are 
not  very  successful,  as  the  squirrel  is  wary.  Natural  enemies,  such  as  the 
coyote,  wolf,  badger,  skunk,  mountain  lion,  the  cobra  snake,  and  red- 
tailed  hawk  should  be  encouraged.^^ 


THE  PLAGUE 

(Pede) 

Plague  is  an  infection  primarily  of  rats  and  other  rodents,  second- 
arily of  men ;  caused  by  Bacillus  pestis.  In  addition  to  this  specific 
definition  the  term  p'ague  still  has  a  generic  meaning.  There  is  much 
confusion  in  the  literature,  because  formerly  all  serious  epidemics  were 
called  plague  and  we  still  speak  of  them  as  plagues. 

The  Philistines  made  offerings  of  golden  images  of  the  mice  that 
marred  the  land  to  stay  a  pestilence  II  Samuel.  The  plague  of 
Athens  and  the  pestilence  in  the  reign  of  Marcus  Aurelius,  according  to 
Payne,  may  not  have  been  this  disease.  Epidemics  of  varying  severity 
occurred  in  Europe  for  over  1,100  years — from  the  sixth  century  in  the 
days  of  Justinian  to  the  middle  of  the  seventeenth  century.  The  most 
devastating  was  the  "Black  Death"  of  the  fourteenth  century  which  over- 
ran Europe  and  destroyed  one-fourth  of  the  population.  The  disease 
gradually  subsided  and  disappeared  from  Europe  and  became  endemic 
in  a  few  remote  parts  of  the  world  (page  350).  We  thought  it  had 
passed  away,  when  suddenly,  in  1894,  it  reappeared  at  Hongkong  and 
from  there  again  spread  over  the  world.  This  recrudescence  of  a  disease 
thought  to  be  extinct  is  one  of  the  most  striking  facts  in  epidemiology. 

The  recent  pandemic  is  the  most  widespread  of  all,  having  been 
carried  to  the  four  quarters  of  the  globe  by  trade  and  travel.  It  is  quite 
as  virulent  as  the  Black  Death  of  the  fourteenth  century;  thus,  from 
the  autumn  of  1896  when  plague  first  gained  a  footing  at  Bombay,  to 
the  end  of  1917,  about  10  millions  of  people  are  reported  to  have  died 
of  the  disease  in  India : — In  1904,  there  were  1,143,993  deaths  from 
plague;  in  1905,  1,069,140;  in  1907,  1,315,892;  in  1908,  156,480;  in 
1909,  178,808;  in  1914,  296,623;  in  1915,  438,866;  in  1916,  276,195; 

*^  In  this  chapter  material  has  been  freely  drawn  from  "The  Rat  and  Its 
Relation  to  the  Public  Health,"  Public  Health  and  Marine  Hospital  Service,  1910, 
particularly  articles  by  Lantz,  McCoy,  Brinckerhoff,  Banks,  Stiles,  Rucker,  Creel, 
Holdy,  Kerr,  and  Rosenau.  This  book  may  be  obtained  by  addressing  the  Surgeon- 
General  or  the  Superintendent  of  Public  Documents,  Washington,  D.  C. 


346  INSECT-BOENE  DISEASES 

in  1917,  537,404.  The  Manchurian  outbreak  in  the  winter  of  1910-11 
was  the  pneumonic  type  of  the  disease;  it  was  virulent  and  extensive,  and 
claimed  over  45,000  persons  in  a  few  months. 

In  1664-65,  the  Black  Death  in  London  carried  off  70,000  of  a 
population  then  numbering  500,000.  A  graphic  description  is  given  by 
Defoe  in  "A  Journal  of  the  Plague  Year."  Numerous  references  to  the 
disease  will  be  found  in-  Pepys'  Diary.  Benvenuto  Cellini  describes 
his  own  case  in  his  autobiography.  The  disease  profoundly  affected  the 
economic,  social  and  political  history  of  Europe.  Plague  started  in 
Stratford-on-Avon  in  July,  1564,  when  Shakespeare  was  a  baby  three 
months  old.  From  July  to  December  of  that  year,  237  deaths  are 
recorded  in  the  parish  register  of  the  little  vicarage  of  Avon.  The  in- 
fection swept  away  entire  families.  Fortunately,  not  a  Shakespeare  is 
on  the  list.  How  much  has  mankind  lost  throughout  the  world's  long 
history  by  the  untimely  death  of  genius  on  account  of  preventable  in- 
fections ! 

There  are  now  four  endemic  foci  in  the  United  States — one  on  the 
Pacific  coast  and  three  in  the  Gulf  states.  The  number  of  cases  in  the 
United  States  and  their  occurrence  is  shown  in  the  table  on  the  fol- 
lowing page.^^ 

In  considering  the  prevention  of  plague  it  is  necessary  to  recog^ 
nize  that  the  different  types  of  the  disease  are  spread  in  different  ways. 
At  least  three  clinical  types  are  now  recognized:  (1)  bubonic,  (2)  pneu- 
monic, and  (3)  septicemic.®^  In  the  bubonic  and  septicemic  types  of 
the  disease  the  plague  bacillus  is  locked  up  in  the  glands,  blood,  and  other 
tissues  and  organs  of  the  body,  and  is  not  eliminated  in  the  usual  ex- 
cretions. These  forms  of  the  disease  are  therefore,  not  "contagious," 
but  are  spread  mainly  through  the  agency  of  the  flea.  On  the  other 
hand,  in  the  pneumonic  type  of  the  disease  plague  bacilli  are  contained 
in  enormous  numbers  in  the  sputum.  The  disease  is  transmitted  directly 
by  close  association  with  a  patient  having  plague  pneumonia.  The 
pneumonic  type  of  the  disease  usually  follows  when  the  infection  is 
taken  into  the  system  through  the  respiratory  chaDnel;  on  the  other 
hand,  it  may  result  from  infection  through  a  flea  bite. 

Bubonic  plague  is  an  insect-borne  disease  and  has  an  entirely  dif- 
ferent epidemiology  from  pneumonic  plague,  which  is  a  contact  in- 
fection. 

Pneumonic  plague  may  assume  epidemic  proportions,  especially  in 
the  cold  weather  and  under  circumstances  where  people  come  in  close 
association.  This  was  the  case  in  the  Manchurian  epidemic  of  1910-1911 
which  occurred   during  the  winter  and  was  one  of  the  most  virulent 

"='  From  data  collected  by  Dr.  G.  W.  McCoy. 

"^  Occasionally  other  varieties  occur  in  which  the  chief  manifestations  are  in 
the  skin  and  subcutaneous  tissues,  or  in  the  intestines,  causing  diarrhea.  In  the 
latter  case  the  infection  is  excreted  in  the  feces. 


THE  PLAGUE 


347 


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348  INSECT-BORNE  DISEASES 

epidemics  of  modern  times,  the  mortality  being  over  90  per  cent.  Epi- 
demics of  pneumonic  plague  are  restricted  to  northern  climates,  as 
northern  Asia  and  the  northern  higher  regions  of  India.  A  limited 
outbreak  was  reported  in  1919  from  California,  which  started  from  an 
infected  squirrel. 

Teague  and  Barber  "*  explain  the  rapid  spread  of  pneumonic  plague 
in  Manchuria  and  the  failure  of  this  type  of  the  disease  to  spread  in 
India  upon  the  assumption  that  'n  the  warm  temperatures  of  India  the 
droplets  quickly  dry  and  the  plague  bacilli  soon  die,  whereas  in  Man- 
churia the  temperature  and  humidity  do  not  favor  evaporation  and 
hence  the  droplets  of  sputum  persist  longer  in  the  cold  atmosphere  and 
the  plague  bacilli  remain  alive  longer. 

The  Bacillus  pestis  (Yersin,  1894)  has  more  than  fulfilled  Koch's 
laws.  Several  accidents  in  which  pure  cultures  have  been  inoculated 
into  man,  producing  all  the  symptoms  and  lesions  of  the  di^sease,  have 
added  to  the  proof  that  this  organism  is  the  cause  of  plague  (Vienna, 
1898,  Ann  Arbor,  1902,  and  also  in  laboratories  in  Russia,  Berlin,  and 
Japan).  The  plague  bacillus  is  comparatively  easy  to  isolate  and  grows 
readily  on  artificial  culture  media,  and  has  characteristics  that  readily 
distinguish  it  from  all  other  species.  It  is  a  short  rod  with  rounded  ends, 
with  a  tendency  to  bi-polar  staining,  not  motile,  decolorized  by  Gram's 
method,  and  grows  well  at  room  temperature  though  less  luxuriantly 
than  at  37°  C. 

Recognition  of  the  plague  bacillus  rests  upon  the  following  charac- 
teristics: (1)  Curious  involution  forms  upon  salt  agar  within  24  hours; 
(2)  stalactite  growth  in  liquid  media;  (3)  characteristic  lesions  pro- 
duced by  experimental  plague  in  guinea-pigs,  rabbits,  rats,  etc.  Kolle's 
method  consists  in  rubbing  the  material  containing  the  plague  bacillus 
upon  a  shaved  area  of  the  skin  of  a  guinea-pig.  The  plague  bacilli  pene- 
trate the  skin,  leaving  other  organisms  behind.  The  skin  of  the  guinea- 
pig  thus  acts  as  a  differential  filter.  (4)  The  final  test  of  the  identity  of 
the  plague  bacillus  is  the  fact  that  its  pathogenicity  may  be  neutralized 
by  the  use  of  antiplague  serum. 

The  Bacillus  pestis  does  not  live  a  saprophytic  existence  in  nature. 
It  is  readily  killed  by  drying,  sunlight,  heat,  and  the  usual  germicides. 
The  organism  does  not  live  long  in  the  soil  or  upon  the  floors  of  houses, 
as  was  once  commonly  supposed.  There  is,  therefore,  comparatively 
little  danger  from  these  sources. 

Immunity. — One  attack  of  plague  usually  protects  for  life.  Occa- 
sionally second  attacks  are  noted  in  the  same  person.  In  such  cases 
the  second  attack  is  usually  mild.     This  is  an  old  observation  and  led 

»*  TeafTue,  0. :  "A  Further  Note  on  the  Influence  of  Atmospheric  Temperature 
on  the  Spread  of  Pneumonic  Plague,"  Philippine  Jour.  So.,  B.,  Tropical  Med., 
1913,  VIII,  241. 


THE  PLAGUE  349 

to  the  employment  of  persons  with  a  plague  history  or  a  plague  scar 
in  hospitals  and  laboratories. 

Artificial  immunity  of  either  an  active  or  passive  nature  may  be 
acquired  by  various  procedures.  The  passive  immunity  produced  by 
the  injection  of  antiplague  serum  lasts  only  about  three  to  four  weeks. 
The  active  immunity  produced  by  vaccination  of  cultures  may  be  de- 
pended upon  for  al)<)ut  six  months. 

IJajfkinc's  prophylactic  consists  of  a  killed  culture  of  the  plague 
bacillus,  which  is  injected  subcutaneously.  HafFkine  used  a  bouillon 
culture,  six  weeks  old,  gi'own  at  25-30°  C.  and  killed  at  65°  C,  for 
one  hour.  One-half  of  one  per  cent,  of  phenol  is  then  added.  From 
2  to  3.5  c.  c.  (tliis  was  later  increased  to  20  c.  c. )  of  this  vaccine  are  in- 
jected subcutaneously.  Ten  days  later  a  second  injection  of  a  still  larger 
amount  is  given. 

In  twelve  districts  in  India  224,228  persons  were  inoculated  with 
Haffkine's  prophylactic.  Of  these  3,399  took  the  disease.  Of  639,600 
not  inoculated  in  the  same  districts  49,430  were  attacked.  C.  J,  Martin 
concludes  that  the  chances  of  subsequent  infection  are  reduced  four- 
fifths,  and  the  chances  of  recovery  are  2.5  times  as  great  as  in  the  cases 
of  the  non-vaccinated. 

The  German  Plague  Commission  prepared  their  prophylactic  vac- 
cine from  a  fresh  virulent  agar  culture,  suspending  the  bacilli  in  salt 
solution  or  bouillon.  The  organisms  are  killed  at  65°  C.  for  one  to 
two  hours,  and  0.5  per  cent,  phenol  added.  The  amount  injected  rep- 
resents one  agar  culture. 

Lustig  and  Galeoti  extract  the  immunizing  substance  from  the  bac- 
terial cell  (endotoxin)  with  weak  potassium  hydroxid.  This  nucleo- 
protein  is  collected  and  dried,  and  thus  permits  of  exact  dosage.  The 
amount  injected  is  two  to  three  milligrams  of  the  dry  extract  dis- 
solved in  water. 

Terni  and  Bandi  recommend  the  peritoneal  exudate  of  plague- 
infected  guinea-pigs,  sterilized  fractionally  at  50°  C,  and  the  addition 
of  0.5  per  cent,  of  phenol,  0.25  per  cent,  sodium  carbonate,  and  0.75 
per  cent,  sodium  chlorid. 

Shiga  prefers  a  combined  active  and  passive  immunity  produced 
with  killed  cultures  and  antipest  serum,  because  this  mixed  immu- 
nizing process  has  the  advantage  of  producing  milder  reactions. 

Kollc  and  also  Strong  started  out  from  the  principle  that  a  much 
higher  degree  of  immunity  is  produced  by  living  microorganisms  than 
dead  ones,  and  recommended  the  use  of  live  attenuated  cultures.  Strong 
has  a  strain,  an  entire  agar  culture  of  which  ma)'  be  injected  into  man 
without  harm.  In  Manila  42  persons  were  given  a  preventive  inocula- 
tion with  this  culture. 

Tiie    reactions    which    follow    vaccination    with    a    plague    culture, 


350  INSECT-BORNE  DISEASES 

whether  alive  or  dead,  are  sometimes  marked.  The  symptoms  consist 
of  a  rise  in  temperature  to  39°  C,  malaise,  depression,  and  headache, 
and  swelling  and  pain  at  the  site  of  the  inoculation.  The  symptoms 
usually  pass  away  in  24  to  48  hours. 

The  production  of  an  active  acquired  immunity  has  a  distinct  prac- 
tical usefulness  in  the  prevention  of  the  disease,  although  it  cannot  take 
the  place  of  rat  and  flea  eradication.  It  has  been  used  on  a  large 
scale  by  Haffkine  in  India,  and  to  a  lesser  extent  by  others  in  many 
parts  of  the  world  during  the  recent  plague  pandemic.  Those  who 
get  plague  after  Haffkinization  usually  have  a  mild  form  of  the  dis- 
ease, which,  in  the  experience  in  India,  rarely  results  in  death.  It  is 
of  first  importance  in  protecting  small  communities,  on  shipboard,  in 
camps  and  barracks,  at  quarantine  stations,  in  plague  laboratories,  among 
rat  brigades,  as  well  as  for  physicians,  nurses,  and  others  who  are  ex- 
posed. 

McCoy  and  Chapin  ^^  state  that  there  is  no  evidence  indicating  that 
vaccination  for  plague  has  ever  controlled  an  outbreak.  A  community 
should  not  be  allowed  to  delude  itself  into  the  belief  that  plague  may 
be  controlled  in  this  manner. 

Yersin's  serum  is  obtained  from  a  horse  that  has  received  repeated 
injections  of  plague  cultures;  at  first  killed  plague  cultures,  afterward 
living  bacilli,  are  used.  At  most  this  antitoxic  serum  is  weak;  it  has 
feeble  and  transient  protective  properties,  and  slight  if  any  curative 
power.  Very  large  quantities  must  be  administered  early  in  the  disease  to 
obtain  any  effect  at  all. 

Endemic  Foci, — There  are  four  historic  endemic  foci  in  which  plague 
has  slumbered  for  ages.  One  is  on  the  eastern  slope  of  the  Himalayas, 
in  the  province  of  Yiinnan.  The  great  epidemic  in  Hongkong  in  1894 
came  from  this  center.  A  second  endemic  focus  near,  and  perhaps  con- 
nected with  the  first  is  on  the  western  slope  of  the  Himalayas.  From 
here  the  infection  was  carried  to  Bombay  in  1896,  where  it  still  prevails. 
A  third  plague  focus  exists  from  about  the  center  of  Arabia  to  near 
Mesopotamia.  From  here  the  infection  was  dragged  to  Samarkand,  the 
Black  Sea,  and  Persia.  The  fourth  endemic  area  was  discovered  by  Koch 
in  1898  in  the  interior  of  Africa,  near  the  source  of  the  White  Nile  in 
Uganda.  We  must  now  add  to  this  a  fifth  endemic  focus,  for  plague  has 
obtained  a  foothold  in  California  in  the  ground  squirrels,  which  will 
take  years  of  well-directed  energy  to  control.  The  disease  also  has 
gained  a  foothold  in  the  Gulf  States — Louisiana,  Texas  and  Florida; 
and  is  endemic  in  many  parts  of  India,  Africa,  South  America  and  Asia. 

Manag^ement  of  a  Plague  Epidemic. — The  handling  of  a  plague  epi- 
demic is  conducted  along  two  definite  lines  of  activity.  One  is  to  find 
and  care  for  the  human  cases,  the  other  consists  in  a  warfare  against 

»» U.  S.  Public  Health  Rpts.,  Vol.  XXXV,  No.  28,  July  9,  1920,  p.  1647. 


THE  PLAGUE  351 

rats.  The  organization  and  general  management  of  a  plague  campaign 
do  not  differ  radically  from  similar  work  in  other  epidemics  (see  page 
495).  Cases  of  the  disease  must  be  sought  for  and  early  diagnosis  con- 
firmed; all  deaths  from  no  matter  what  cause  must  be  investigated, 
and  the  body  examined  by  an  expert  before  burial  is  permitted.  A 
bacteriological  la1)oratory  is  a  mne  qua  non.  Cases  of  the  disease  should 
be  isolated  and  the  usual  disinfection  of  excreta  and  surroundings  exer- 
cised. Particular  care  must  be  taken  that  the  isolation  wards  are  ver- 
min-free. The  place  from  which  the  case  is  removed  should  be  given  a 
preliminary  disinfection  with  sulphur  dioxid  or  other  substance  that  may 
be  depended  upon  to  kill  rats  and  fleas,  and  a  search  made  in  the  neigh- 
borhood for  secondary  cases  both  in  man  and  rodents. 

The  campaign  against  the  rat  is  expensive  and  difficult,  but  must 
be  vigorously  prosecuted  to  insure  success.  The  rat  warfare  may  be 
briefly  summarized  as  a  simultaneous  attack  upon  the  habitation  and 
food  supply  of  the  rat;  the  destruction  of  rat  burrows  and  nesting 
places ;  the  separation  of  the  rat  from  his  food  supply  by  concreting  and 
screening  such  places  as  stables,  warehouses,  markets,  restaurants,  etc. ; 
the  prevention  of  the  entry  of  the  rat  into  human  habitations  by  the 
use  of  concrete,  wire  netting,  or  other  barriers;  and  the  use  of  poisons, 
traps,  etc.  For  further  consideration  concerning  rats  and  their  eradi- 
cation see  page  338.  All  the  rats  that  are  caught  in  traps  or  found 
dead  are  brought  to  the  bacteriological  laboratory,  where  they  are  ex- 
amined and  careful  records  kept  concerning  the  species,  the  location, 
the  place  where  the  rat  was  caught,  the  character  of  the  infection,  etc. 
As  it  is  a  liopeless  task  to  exterminate  rats  from  a  large  city,  Heiser 
has  proposed  a  practical  plan  which  proved  effective  in  Manila.  A 
list  of  the  places  in  which  the  plague-infected  rats  were  found  was 
made.  Each  was  regarded  as  a  center  of  infection.  Radiating  lines, 
usually  five  in  number,  were  prolonged  from  this  center,  evenly  placed 
like  the  spokes  of  a  wheel.  Eats  were  caught  along  these  lines  and 
examined.  Plague  rats  were  seldom  found  more  than  a  few  blocks 
away.  The  furthermost  points  at  which  the  infected  rats  were  found 
were  then  connected  with  a  line,  as  is  roughly  shown  in  the  diagram. 
Figs.  44  and  45.  The  place  inclosed  by  the  dotted  line  was  regarded  as  a 
section  of  infection.  The  entire  rat-catching  force  was  then  concen- 
trated along  the  border  of  the  infected  section,  that  is,  along  the  dotted 
line.  They  then  commenced  to  move  toward  the  center,  catching  the 
rats  as  they  closed  in.  Behind  them  ratproofing  was  carried  out.  One 
section  after  another  was  treated  in  this  way,  until  they  had  all  been 
wiped  out.  Once  weekly  thereafter  rats  were  caught  in  the  previously 
infected  sections  and  at  other  places,  especially  those  which  had  been 
infected  in  years  gone  by.  Since  the  above  system  was  adopted  plague 
has  disappeared  in  the  city  of  Manila,  and  at  a  cost  of  only  a  small 


352 


INSECT-BOENE  DISEASES 


fraction  of  that  of  a  general  rat  extermination  campaign.  A  campaign 
along  these  same  general  lines  has  also  been  successful  in  New  Orleans. 
Quarantine. — Plague  infection  is  frequently  carried  overseas  in 
vessels.  When  this  happens  it  is  more  apt  to  be  due  to  the  disease  in 
the  rat  than  man.  Maritime  quarantine,  therefore,  finds  its  greatest 
justification  in  keeping  out  plague.  To  be  successful,  measures  must 
be  directed  almost  entirely  against  the  rat.  Eats  may  be  kept  down 
on  board  a  vessel  by  the  frequent  use  of  sulphur  dioxid.     All  vessels 


Fig.  44. 


trading  with  a  plague-infected  port  should  have  each  cargo  compartment 
fumigated  with  this  gas^  or  better,  hydrocyanic  acid,  at  least  when  it 
is  empty,  at  the  port  of  departure.  The  vessel  must  be  again  fumigated 
on  arrival.  Both  at  the  infected  port  and  at  the  port  of  arrival,  care 
must  be  taken  to  prevent  the  ingress  and  egress  of  rats.  The  period  of 
detention  of  the  personnel  for  a  plague  ship  is  seven  days.  For  further 
details  concerning  quarantine  see  page  498. 

Prevention — Summary. — The  principles  and  many  of  the  details  for 
the  prevention  of  plague  have  been  stated  in  the  foregoing  pages,  and 
need  not  be  repeated. 


THE  PLAGUE 


353 


Personal  prophylaxis  consists  in  avoidin<r  the  infected  regions  and 
guarding  against  ilea  bites.  Physicians  and  nurses  should  remember 
that  the  pneumonic  form  of  the  disease  is  highly  "contagious"  in  the 
ordinary  sense  of  the  term.  Attendants  and  persons  who  come  in  con- 
tact with  such  cases  may  protect  themselves  with  Haflkine's  pro])hylac- 
tic.  Individual  measures  to  guard  against  droplet  infection,  such  as  the 
wearing  of  masks  or  veils  of  cheesecloth,  may  be  resorted  to.  The 
bubonic  and  septicemic  forms  of  tlie  disease  are  not,  as  a  rule,  directly 


Fig.  45. — Isolated  Plague-infested  Center,  Manila,  P.  I. 


communicable,  and,  therefore,  the  preventive  measures  recommended  for 
typhoid  fever  are  effective. 

The  ordinary  germicidal  solutions,  such  as  bichlorid  of  mercury, 
1-1,000,  carbolic  acid,  2i/^  per  cent.,  formalin,  10  per  cent.,  are  effec- 
tive against  the  Bacillus  peslis.  Of  the  gaseous  disinfectants,  sulphur 
dioxid  is  preferred,  because  it  not  only  kills  the  frail  plague  bacillus, 
but  also  destroys  rats,  fleas,  etc. 

Cases  of  plague  should  be  isolated  in  a  well-screened  room  other- 
wise free  of  insects.  Fabrics  and  other  objects  which  become  contam- 
inated with  the  discharges  should  be  thoroughly  disinfected  by  proper 
methods. 

It  is  important  to  have  prompt  reports  of  all  cases  of  suspected 


354  mSECT-BOENE  DISEASES 

plague,  and  the  diagnosis  must  be  confirmed  by  bacteriological  meth- 
ods. In  all  plague  centers  there  should  be  a  special  hospital  and  also 
a  laboratory  where  diagnostic  work  may  be  carried  on;  this  is  an  es- 
sential part  of  the  equipment  for  a  successful  campaign.  A  traveling 
laboratory  organized  like  a  flying  squadron  for  quick  service  should 
be  provided  to  furnish  this  service  wherever  it  may  be  demanded. 

The  prevention  of  plague,  after  all,  is  reduced  to  warfare  against 
rats  and  fleas.  This  has  been  fully  discussed.  All  seaport  towns  hav 
ing  communication  with  plague  countries  should  examine  rats  caught 
about  the  wharves  and  other  places  for  plague.  This,  in  fact,  should 
be  one  of  the  routine  duties  of  the  port  sanitary  authorities.  Plague 
may  slumber  in  the  rats  for  years  before  human  cases  occur.  Other 
preventive  measures  are  obvious  from  the  nature  of  the  infection  and 
its  mode  of  transmission,  or  have  already  been  stated  in  the  preceding 
pages. 

Plague  quarantine,  see  page  505. 


TICKS 

Ticks  belong  to  the  family  Ixodidae;  quite  a  number  of  different 
species  are  known  to  attack  man. 

Ticks,  or  wood  lice,  are  not  true  Insecta,  but  belong  to  the  acarines 
which  include  the  mites,  and  are  closely  allied  to  spiders  and  itchmites 
(scabies).  Ticks  have  an  unsegmented  body  with  eight  legs  m  the 
adult  stage  and  six  legs  in  the  larval  stage.  In  some  of  their  habits 
they  resemble  bedbugs.  So  far  as  is  known,  they  take  no  vegetable 
food,  but  live  on  blood.  Ticks  are  ectoparasites  of  man  and  many  ani- 
mals. They  frequently  hang  tenaciously  to  the  skin,  in  which  they 
partly  bury  themselves.  If  covered  with  oil  or  vaselm,  thus  clos- 
ing their  breathing  pores  situated  behind  the  fourth  pair  of  legs,  they 
may  be  induced  to  release  their  hold.  If  pulled  off  roughly  the  head 
(capitulum)  is  likely  to  break  off  and  remain  in  the  skin.  Sulphur 
in  some  form  is  useful  to  destroy  ticks  in  the  adult  stage.  Sulphur 
ointment  is  particularly  obnoxious  to  this  group  of  parasites.  Arsenic 
and  crude  oil  also  act  as  poisons  to  the  tick,  and  may  be  used  by  local 
application.     McCormack  states  that  tick  bites  cause  paralysis. 

The  life  cycle  of  the  tick  consists  of  four  distinct  stages,  viz.,  egg 
(embryo),  larva,  nymph,  and  adult.  The  eggs  are  invariably  deposited 
on  the  ground  in  large  masses.  The  larvae  which  emerge  from  the 
eggs  are  minute  six-legged  creatures.  The  larvae  attach  themselves  to 
a  suitable  host,  upon  which  they  feed,  then  usually  drop  to  the  ground 
and  molt,  becoming  nymphs.  The  nymphs  have  eight  legs.  The  nymph 
waits  until  it  can  attach  itself  to  a  host,  engorges  blood,  usually  drops, 


TICKS  355 

molts  its  skin,  and  becomes  adult.  Ticks  take  at  least  two,  and  some- 
times four  or  five,  years  to  mature.  They  liil)ernate  during  the  winter. 
They  prefer  shady  places,  and  are  dcstroyt'd  by  sunshine;  hence,  clear- 
ing the  land  and  cultivation  arc  good  measures  of  eradication.  The  life 
history  of  the  tick  differs  from  the  mosquito  in  that  the  larval  and  pupal 
stages  are  not  aquatic. 

It  was  first  shown  l\y  Smith  and  Kilborne  that  in  the  case  of  Texas 
fever  the  microorganism  within  the  adult  tick  passes  into  the  egg  and 
is,  therefore,  transmitted  "hereditarily"  to  the  next  generation.  The 
infection  of  Rocky  ^Mountain  spotted  fever,  of  canine  piroplasmosis,  and 
probably  also  that  of  African  tick  fever,  is  also  transmitted  by  the  female 
i;o  the  next  generation.  Tick-borne  diseases  are  not  always  transmitted 
in  nature  in  this  way.  The  virus  may  be  transferred  directly  by  the 
larva,  the  nymph,  or  the  adult.  Thus,  some  ticks  leave  their  host  re- 
peatedly, and  the  parasites  they  draw  from  one  animal  may  be  injected 
into  another  animal  either  during  the  same  or  at  a  subsequent  stage  in 
the  development  of  the  tick. 

Ticks  upon  domestic  stock  may  be  controlled  by  dipping,  spraying, 
or  by  hand  methods.  The  arsenical  dip  has  practically  displaced  all 
others  for  the  destruction  of  ticks  in  the  various  parts  of  the  world. 
Arsenical  solutions  containing  sodium  arsenite  in  amounts  equivalent 
to  about  0.2  per  cent,  arsenious  oxid  (AsgOg),  or  less  according  to  the 
frequency  of  dipping  and  other  conditions,  give  the  best  results  in  kill- 
ing ticks  without  injury  to  the  stock.  This  strength  of  arsenic,  how-- 
ever,  will  not  kill  or  prevent  egg-laying  by  all  the  engorged  females. 
Crude  petroleum  oils  have  been  used  to  a  considerable  extent.  They 
are  more  expensive  than  the  arsenical  dip,  and  dangerous  to  cattle  under 
some  conditions.  Serious  losses  have  followed  the  use  of  heavy  oils 
in  dry  regions,  or  where  it  has  been  necessary  to  drive  the  cattle  any 
considerable  distance  after  dipping. 

A  commonly  used  formula  for  arsenical  dip  is  as  follows: 

Sodium  carbonate   (sal  soda) 24  lbs. 

Arsenic   trioxid    (white   arsenic) 8  lbs. 

Pine  tar    1  to       2  gals. 

Water   sufficient  to  make  500  gals. 

The  above  formula  may  be  used  when  treatments  are  given,  not 
oftener  than  every  two  weeks,  but  in  some  tick-borne  diseases  more 
frequent  dippings  are  necessary  owing  to  peculiarities  in  the  life  his- 
tories of  the  various  species  of  ticks,  and  weaker  solutions,  although 
less  effective  in  destroying  ticks,  must  be  used  to  avoid  injury  to  the 
cattle. 

Sometimes  dipping  is  not  practical.  Instead  of  driving  cattle  con- 
siderable distances  to  dipping  vats  it  will  be  found  sufficient  to  treat 


356  INSECT-BORNE  DISEASES 

them  thoroughly  by  hand  methods.  The  procedure  consists  simply  in 
applying  the  arsenical  mixture  liberally  by  means  of  rags,  mops,  or 
brushes,  or  by  means  of  spray  pumps.  Crude  oil  may  be  used  by  hand 
instead  of  the  arsenical  solution. 

The  following  diseases  transmitted  by  ticks  will  be  given  brief  con- 
sideration:  Texas  fever  (Margaropus  annulatus),  South  African  tick 
fever  (Ornitliodoros  savignyi),  Eocky  Mountain  spotted  fever  (Derma- 
centor  ve/nustus),  and  relapsing  fever  (Ornitliodoros  mouhata) ;  al- 
though it  is  probable  that  the  latter  disease  is  also  transmitted  by  the 
Argas  persicus  and  perhaps  other  biting  insects. 

TEXAS  FEVEB 

Texas  fever  or  splenetic  fever  is  also  known  as  bovine  malaria,  tick 
fever,  and  hemoglobinuria.  The  disease  does  not  affect  man.  It  is 
confined  to  cattle,  and  is  of  very  great  economic  importance.  Texas 
fever  is  an  infoction  which  should  be  understood  by  all  sanitarians,  on 
account  of  its  scientific  and  historic  importance.  The  cause  of  this  in- 
fection and  its  mode  of  transmission  were  ascertained  in  1893  by  Smith 
and  Kilborne.  The  discovery  that  the  tick  is  the  intermediate  host  of 
Texas  fever  opened  an  entirely  new  principle  in  the  sanitary  sciences. 

Texas  fever  is  caused  by  a  protozoou  parasite.  This  parasite  was 
first  named  Pyrosoma  higeminum  on  account  of  the  twin-like,  pear- 
shaped  forms  commonly  seen  in  the  red  corpuscles.  This  genus  was 
changed  by  Patton  in  1895  to  Piroplasma.  These  terms  having  been 
preoccupied,  the  present  name  of  the  parasite  is  Babesia  higemina.^^ 

The  contagium  is  carried  by  the  cattle  tick,  Boophilus  hovis,  now 
Margaropus  annulatus.  This  tick  lives  upon  the  skin  and  feeds  upon  the 
infected  blood,  becomes  sexually  mature  at  the  last  molt;  the  female 
drops  to  the  ground  and  lays  about  2,000  eggs ;  the  newly  hatched  larvae 
attach  themselves  to  the  skin  of  a  fresh  host,  which  they  infect.  This 
explains  the  long  extrinsic  period  of  incubation  in  this  disease,  40-60 
days,  30  days  of  which  are  required  for  the  development  of  the  larvae 
and  the  remainder  for  the  development  of  the  parasite  within  the  host. 

ROCKY  MOUNTAIN  SPOTTED  FEVER 

Rocky  mountain  spotted  fever  is  an  interesting  infection,  with  a 
very  limited  geographic  distribution.  The  symptoms  closely  resemble 
those  of  typhus  fever,  including  an  eruption,  first  macular  then  petechial. 
This  may  go  on  to  gangrene  of  the  skin,  due  to  thrombi  of  the  peripheral 
vessels.    Irritability  and  hyperesthesia  of  the  skin  are  common  symptoms 

°'  These  various  names  are  given  for  the  reason  that  they  are  all  found  in  the 
literature. 


TICKS 


S&t 


and  are  due  to  infiltration  of  the  peripheral  nerves.  There  is  no  leuko- 
cytosis, but  an  increased  number  of  mononuclear  cells. 

The  disease  is  very  mild  in  Idaho  and  very  virulent  in  Montana, 
which  has  a  case  fatality  as  liii^h  as  90  per  cent.  About  500  cases  occur 
in  the  United  States  a  year.  The  disease  prevails  especially  in  the 
spring. 

IJorky  ^lountain  spotted  fever  may  be  distinguished  from  typhus 
fever  in  the  guinea-pig: — After  intraperitoneal  injection  of  infected 
blood,  the  period  of  incubation  in  Kocky  Mountain  spotted  fever  is  3 
days,  while  in  typhus  it  is  9  to  11  days;  typiuis  does  not  show  the  scrotal 
and  foot  lesions  of  IJucky  Muuntaiii  spott('(l  fuvcr;  the  virus  of  typhus 
is  much  less  virulent  for  guinea-pigs;  there  is  no  cross  immunity: — the 
two  diseases  are  therefore  distinct. 


Fig.  46. — The  Texas  Fever  Tick   {Margaropus  annulatus). 


Eocky  Mountain  spotted  fever  is  widely  spread  over  seven  states  in 
the  Eocky  Mountain  region;  namely,  Colorado,  Idaho,  Montana,  Ne- 
vada, Utah,  Oregon,  and  Wyoming,  and  is  also  found  in  California, 
South  Dakota,  Washington  and  British  Columbia.  The  disease  has 
been  studied  especially  in  the  Bitter  Eoot  Valley  of  Montana,  where  it 
is  limited  to  the  western  slope. 

Wilson  and  Chowning  first  suggested  that  the  tick  acts  as  the  car- 
rier of  Eocky  Mountain  spotted  fever.  This  was  proved  by  Eicketts 
in  1906,  who  showed  that  the  particular  tick  is  Dermacentor  andersoni,^'' 
Dermacentor  modestiis  and  Dermacentor  marginatus  also  transmit  the 
infection.  The  infection  may  be  transmitted  by  the  larva,  the  nymph, 
and  both  the  adult  male  and  female  ticks.  The  disease  is  transmitted 
to  susceptible  small  animals  by  the  larvae  and  nymphs;  but  the  mouth 
parts  of  these  immature  forms  are  probably  not  strong  enough  to  feed 
on  man  and  other  large  animals,  which  are  infected  by  the  adult  ticks. 
The  infection  is  also  transmitted  "hereditarily"  through  the  ticks  to 
their  larvae.     The  disease  has  been  transmitted  from  man  to  monkey 

"  Also  called  D.  ocddentalis  and  D.  venustus. 


358 


IKSECT-BORNE  DISEASES 


and  the  guinea-pig,  and  also  from  monkey  to  monkey  and  from  guinea- 
pig  to  guinea-pig.  Eabbits,  ground  squirrels,  woodchucks,  and  other 
animals  are  susceptible. 


Fig.  47. — Rocky  MouNTAiTf  Spotted  Fever  Tick.    {Dermacentor  venustus). 
1,  Adult  female,  imengorged,  dorsal  view;  2,  Adult  male,  dorsal  view;   3,  Adult 
female,   unengorged,   ventral   view;    4,   Adult   male,   ventral   view;    5,   Adult 
female  in  act  of  depositing  eggs. 


Infected  ticks  have  actually  been  found  in  nature.  Eicketts  found 
one  out  of  296;  Maver,  2  out  of  402;  and  McClintic,  6  out  of  1,037. 
The  ticks  were  collected   from  known   infected   districts  and  fed  on 


TICKS  359 

jj^uiiiea-jii^s  in  ^toiiiis.  McCIiiitic  dii'd  of  K'ocky  Moiintaiii  spottefl 
fever  while  studying  the  disease. 

Maver  "■'■''  has  jirovcd  by  cxiuMMniciit  that-  dilVeriJiit  speeies  of  ticks  col- 
lected from  various  regions  |  Dcriitacoihir  nnirr/inalus  (Utah),  Ambly- 
omnia  aincn-iminis  liiniacus  (Missouri),  aii<l  Pcrfnacenlor  va/ri(d)ilig 
(Mass.)]  are  ahle  to  transmit  the  virus  of  IJocky  Mountain  spotted 
fever.  The  inference  is  that  the  disease  may  find  favorable  conditions 
for  its  existence  in  localities  other  than  those  to  whicii  it  is  now  lim- 
ited. 

One  attack  of  the  disease  establishes  a  very  high  degree  of  immu- 
nity. No  authentic  case  of  a  subsequent  attack,  in  rnau  is  known,  and 
laboratory  animals  have  always  been  found  completely  immune  after  a 
primary  infection.  The  blood  scrum  of  recovered  cases  contains  protec- 
tive properties  of  a  rather  liigh  degree  for  guinea-pigs  (King).  The 
virus  is  not  filterable  through  a  Berkefeld  filter. 

Kicketts  found  "bodies"  in  the  blood  of  human  and  experimental  cases 
and  also  in  the  tissues  and  eggs  of  infected  ticks.  These  observations 
have  been  con  Firmed  by  Wolbach,*'^  who  finds  bacillus-like  bodies  in  the 
lesions  of  Rocky  Mountain  spotted  fever.  The  characteristic  form  is  a 
short  rod,  in  pairs  and  clusters,  growing  in  great  numbers  in  the  lesions 
of  the  blood  vessels,  testicle,  skin,  and  subcutaneous  tissues.  Wolbach 
later  identified  these  bodies  as  Rickettsia,  which  are  described  on  page 
372. 

This  organism  has  not  been  grown  in  artificial  culture  media.  It 
invades  all  the  tissues  of  the  tick,  even  the  ova  and  the  spermatozoa, 
which  accounts  for  "hereditary"  transmission  of  the  infection.  In  man 
these  Rickettsia  bodies  are  mainly  localized  in  the  smaller  peripheral 
blood  vessels,  causing  proliferating  endarteritis. 

The  prevention  of  Rocky  Mountain  spotted  fever  is  directed  en- 
tirely against  the  tick.  Ticks  are  to  be  avoided  in  the  infected  region. 
If  it  is  necessary  to  work  in  the  fields  and  woods  and  about  animals 
where  these  ticks  abound,  the  bites  should  at  once  be  cauterized  with 
strong  carbolic  acid.  In  endemic  regions  the  entire  body  and  clothing 
should  be  examined  twice  daily  for  ticks. 

The  ultimate  control  of  Rocky  Mountain  spotted  fever  depends  upon 
the  suppression  of  the  Dermacentor  andersoni  and  related  ticks  in 
infected  areas.  This,  perhaps,  is  not  so  hopeless  a  task  as  may  at  first 
seem  likely.^*'"  Henshaw  and  Birdseye  ^"^  found  ticks  either  in  the  imma- 
ture or   adult   stage   upon   twenty   species   of   five   hundred   mammals 

^Jour.  Infect.  Dis.,  April  12,  1911. 

"^  Journal  of  Medical  Research,  March,  1916,  Vol.  XXXIV,  1,  pp.  121-126,  and 
XLI,   1,  Nov.,   1919. 

100  Fortunately  the  Dermacentor  andersoni  is  the  only  tick  in  the  endemic 
region  which  attacks  man. 

"'  U.  S.  Dept.  of  Agr.,  Bureau  of  Biol.  Survey,  Cir.  82. 


360  INSECT-BOENE  DISEASES 

examined  in  and  around  Bitter  Boot  Valley.  The  mammalian  hosts  of 
fever  ticks  fall  naturally  into  two  groups :  those  that  harbor  chiefly  adult 
ticks  and  those  that  harbor  the  younger  stages.  In  the  former  class 
belong  mountain  goats,  bears,  coyotes,  badgers,  woodchucks,  and  possibly 
elk,  deer,  mountain  sheep,  rabbits,  and  domestic  stock,  such  as  horses, 
cattle,  and  sheep.  Those  of  the  second  class  harboring  the  nymphs  and 
larvae  are  mainly  rodents  and  comprise  ground  squirrels,  woodchucks, 
chipmunks,  pine  squirrels,  mice,  and  wood  rats.  These  smaller  animals 
are  too  agile  to  permit  the  adult  ticks  to  remain  upon  them. 

Unquestionably  the  great  bulk  of  fever  ticks  (Dermacentor  ander- 
soni)  which  become  engorged  in  the  Bitter  Boot  Valley  do  so  on  domestic 
stock — horses,  cattle,  sheep,  and  sometimes  dogs.  They  obtain  the 
ticks  from  the  pastures  and  other  uncultivated  land  infested  by  wild 
animals.  It  is  obvious,  therefore,  that,  if  the  domestic  animals  in  the 
valley  are  rendered  tick-free  by  dipping,  spraying,  or  by  some  other 
equally  effective  method,  the  chances, of  the  infection  of  human  beings 
will  be  vastly  lessened. 

The  measures  proposed  for  the  eradication  of  the  tick  are  as  follows : 
Clearing  and  cultivation  of  tillable  land;  burning  over  of  foothills  and 
"slashings" ;  killing  of  small  wild  mammals ;  dipping  of  domestic  animals 
in  arsenical  dip;  spraying  and  removing  ticks  by  hand  from  domestic 
animals.  Each  one  of  these  measures  has  a  rational  basis  in  the  bionomics 
of  the  tick  Dermacentor,  but  although  all  of  these  methods  have  been 
attempted  on  the  west  side  of  the  Bitter  Boot  Valley  for  three  years 
or  more  they  have  not  greatly  diminished  the  number  of  ticks  to  be 
found  nor  the  number  of  deaths  from  spotted  fever.  The  extent  and 
inaccessibility  of  the  infested  territory,  and  the  consequent  expense 
have  rendered  the  problem  difficult.  Fricks  ^"^  recommends  sheep  grazing 
to  diminish  the  number  of  ticks,  for  the  reason  that  ticks  die  upon  sheep, 
and  many  of  the  engorged  females  are  not  fertilized  on  account  of  the 
difficulty  experienced  by  the  males  in  propelling  themselves  through  the 
thick  wool  in  search  of  the  females. 

McClintic  infected  Bhesus  monkeys  and  guinea-pigs  with  spotted 
fever  and  treated  them  with  the  following  drugs:  salvarsan,  sodium 
cacodylate,  and  urotropin.  The  results  obtained,  however,  do  not  in- 
dicate that  any  of  these  drugs  possess  any  value  whatever  either  as  a 
prophylactic  or  in  the  treatment  of  spotted  fever,  but,  on  the  contrary, 
their  administration  seems  on  the  whole  rather  to  intensify  the  severity 
of  the  disease  in  the  animals  compared  with  the  course  of  the  disease 
in  the  controls.^"^ 


i*"  Hunter,  W.  D.,  and  Bishopp,  F.  C:  "The  Rocky  Mountain  Spotted  Fever 
Tick,"  Bureau  of  Entomology  Bull.  No.  105,  U.  S.  Dept.  of  Agr. 

"'  U.  S.  Pub.  Health  Reports,  Vol.  XXVII,  No.  20,  May  17,  1912,  and  XXVII, 
No.  32,  Aug.  8,   1913,  p.   1647. 


TICKS  361 

JAPANESE  RIVER  FEVER 

Japanese  river  fever  ueiur.s  alon^  the  river  bottoms  with  a  preference 
for  sandy  soil.  Cliniially,  it  resembles  typhus  fever.  It  is  transmitted 
by  a  small  mite  {Leplus  akamiishi)  which  lives  upon  field  mice.  The 
field  mouse  is  the  reservoir  of  the  infection.  The  disease  also  occurs 
in  Sumatra  and  Formosa  and  probably  in  China.  It  is  also  known  as 
tsutsugamushi  disease. 

RELAPSING  FEVERS 

Eelapsing  fever,  also  called  famine  fever,  tick  fever,  and  seven-day 
fever,  is  found  upon  all  the  five  continents  of  the  globe.  Epidemics  of 
this  disease  have  been  reported,  especially  from  Ireland  and  Russia.  The 
infection  prevails  in  India,  where  Vandyke  Carter  of  Bombay  made  his 
classic  investigations.  Eelapsing  fever  was  epidemic  in  New  York  and 
Philadelphia  in  1869.  It  has  not  reappeared  in  epidemic  form,  but 
cases  occasionally  occur  in  various  parts  of  the  United  States.  The 
disease  has  receded  from  civilization  where  sanitation  is  practical  and 
hygiene  is  observed. 

The  term  "relapsing  fever"  includes  a  group  of  tropical,  febrile  in- 
fections caused  by  different,  but  very  closely  allied,  spirochetes — spiro- 
scliaudinniae.  The  European  relapsing  fever  is  caused  by  S.  recurrentis 
and  transmitted  by  bedbugs  and  lice.  The  relapsing  fevers  of  East  and 
West  Africa  are  caused  by  S.  duttoni  and  transmitted  by  the  tick  (Or- 
nithodorus  mouhata).  The  North  African,  or  Algerian  relapsing  fever 
is  caused  by  S.  herhera  and  is  transmitted  by  lice  (Pedicuhis  vestimenti 
and  Pediculus  capitis) .  The  relapsing  fever  of  Asia  and  India  is  caused 
by  S.  carieri  and  is  transmitted  by  lice.  These  various  spirochetes  re- 
semble each  other  morphologically,  but  show  a  difference  in  pathogenic- 
ity to  laboratory  animals  and  are  further  distinguished  from  each  other 
by  specific  agglutinins. 

Eelapsing  fever  is  characterized  by  sudden  onset,  intense  frontal 
headache  and  pains  of  back  and  limbs.  The  fever  continues  from  three 
to  five  days  and  falls  by  crisis.  The  temperature  remains  normal  for 
about  a  week,  when  the  fever  repeats  itself.  There  may  be  four  or  five 
such  relapses,  sometimes  ten.  The  spirochetes  are  foimd  in  the  -per- 
ipheral blood  only  during  the  febrile  period. 

Obermeier  in  1868  discovered  the  "spirillum"  in  the  blood — Spiril- 
lum ^^^  ohermeieri.  Carter  and  Koch  in  1878  showed  that  the  infection 
may  be  transferred  to  apes  by  the  inoculation  of  the  blood  of  a  patient. 
Miinch  and  Moczutkowski  transferred  the  disease  by  the  inoculation  of 
relapsing  fever  blood  to  healthy  individuals.     Koch  and  also  Dutton  and 

^'^  Spirillum  was  changed  to  spirochaeta  and  then  to  spiroschaudiyini. 


362  mSECT-BORNE  DISEASES 

Todd  succeeded  in  demonstrating  that  the  spirochetes  of  African  relaps- 
ing fever  multiplied  in  the  tick  (Omithodorus  moubata),  and  that  the 
bite  of  this  tick  may  convey  the  disease  to  healthy  men.  The  spirochetes 
are  found  in  the  coxal  glands  and  in  the  feces  of  the  tick,  which  is  rubbed 
into  the  wound  made  by  the  tick  bite.  Other  insects,  as  bedbugs,  fleas, 
biting  flies,  and  lice,  may  convey  the  infection.  Lice  do  not  infect  by 
biting,  but  when  the  insects  are  crushed  and  rubbed  into  a  scratched  sur- 
face of  the  skin. 

Leishman  ^"^  has  demonstrated  that  the  Spirocliaeta  duttoni  may  be 
transmitted  "hereditarily"  in  the  tick.  He  has  obtained  positive  results 
in  the  second  generation,  the  bites  of  which  were  infective  for  mice 
and  monkeys.  Attempts  to  carry  the  infection  to  the  third  generation 
in  the  tick  have  so  far  failed.  Leishman  considers  the  hereditary  trans- 
mission of  the  infection  as  biological  evidence  that  the  spirochetes  be- 
long to  the  protozoa  rather  than  the  bacteria. 

Schuberg  and  Manteufe  ^"^  found  that  a  temperature  of  33°  C.  is 
not  favorable  for  the  spirochete  in  the  Ornithodorus  moubata.  This 
was  shown  by  experiments  upon  rats  in  which  the  infection  through 
the  bite  of  the  tick  disappeared  more  quickly  at  33°  C.  than  at  higher 
temperatures. 

One  attack  protects  against  subsequent  attacks.  Second  attacks  occur 
among  negroes  in  Africa  after  years  but  are  very  light.  The  only  sus- 
ceptible animals  are  man,  the  apes,  mice,  and  rats. 

The  prevention  of  relapsing  fever  is  based  upon  sanitation  of  the 
environment  and  personal  and  domestic  cleanliness  and  the  avoidance  of 
tick  and  other  bug  bites.  Personal  prophylaxis  depends  upon  keeping 
aloof  from  vermin-infested  places,  especially  where  the  disease  prevails. 
Manson  suggests  that  a  mosquito  net,  a  vermin-free  bed  well  off  the 
ground,  and  a  night  light  are  indispensable  in  Africa,  where  the  nocturnal 
habits  of  the  Ornithodorus  moubata  render  the  hours  of  sleep  especially 
dangerous.  This  tick  has  habits  somewhat  similar  to  those  of  a  bedbug, 
and  lives  in  cracks  of  the  walls  and  floors  of  the  native  huts.  Salvarsan 
is  a  specific  remedy. 

LICE 

Lice  are  degraded,  wingless  insects,  and  are  divided  into  two  groups 
according  to  their  method  of  feeding.  The  Mallopliaga  included  biting 
lice,  like  the  bird  lice  which  feed  on  the  hair  and  feathers  of  animals, 
but  do  not  suck  blood.  As  far  as  is  known,  these  lice  do  not  transmit 
disease.  The  Anoplura,  or  sucking  lice,  feed  upon  blood,  and  is  the 
group  concerned  in  the  transmission  of  disease.    Lice  do  not  travel  much, 

^"^  Lancet,  Jan.  1,  1910,  Vol.  I,  p.  11. 

^"^  Zeitsohr.  f.  Immwnitatsforschung,  Orig.  Bd.  4,  1910,  p.  512. 


LICE  363 

and  keep  fairly  close  to  one  host,  ro  they  are  not  as  dangerous  as  some 
more  active  parasites. 

Human  lice  belong  to  three  species:  Pediculus  capitis,  head  lice; 
Pediculus  vestimenti  or  corporis,  clothes  or  body  lice ;  Phthirus  pubis, 
pubic  or  crab  lice.  Nuttall  ^"^  and  Bacot ""  regard  the  head  louse  and 
clothes  louse  as  races  of  the  same  species,  and  so  Nuttall  united  them 
under  the  title  Pediciihis  hitmanus,  designating  the  head  louse  as  capitis 
and  the  clothes  louse  as  corporis. 

Pediculus  corporis  is  often  called  the  "body  louse"  or  "clothes  louse/' 
or  the  '^grayback"  of  Civil  War  days,  or  "cootie"  in  the  World  War. 
This  louse,  also  known  as  Pediculus  vestimenti,  is  a  parasite  which  de- 
pends upon  human  blood  for  sustenance  and  man's  body  and  clotliing 
for  prolonged  life  and  reproduction.  The  size  varies  with  its  maturity; 
a  newly  hatched  louse  is  about  the  size  of  a  pin  head,  while  a  full  grown, 
well  fed  louse  is  about  one-sixth  of  an  inch  in  length.  The  louse  has  a 
smooth,  hard,  chitinous  covering,  which  is  impenetrable  to  most  chemi- 
cals. 

The  body  is  divided  into  head,  thorax  and  abdomen.  At  the  sides  of 
the  head  are  two  antennae,  the  mouth  has  a  long  sharp  stylet  or  stabber 
which  is  used  for  puncturing  the  skin.  This  stylet  consists  of  three  parts 
which  are  so  formed  as  to  make  a  hollow  tube  through  which  the  blood 
jflows.  Attached  to  the  thorax  are  six  legs  which  are  Joined,  and  at  each 
end  is  a  single  large  claw.  The  abdomen  is  divided  into  six  or  eight 
segments.  The  terminal  one  is  indented  in  the  female  and  rounded  in 
the  male.  The  abdomen  of  the  female  is  broader  than  that  of  the  male- 
There  is  some  evidence  that  there  are  more  females  than  males.  Both 
sexes  bite  and  convey  disease. 

The  life  histories  of  Pediculus  capitis,  P.  corporis,  and  Phthirus 
puhis  are  similar,  in  that  the  insects,  after  emerging  from  the  egg,  under- 
go three  molts  before  attaining  sexual  maturity. 

The  eggs  or  nits  are  laid  on  fibers  of  clothing  or  body  hair.  They 
prefer  to  lay  eggs  on  rough  material  such  as  felt,  wool  or  flannel,  but 
will  deposit  eggs  on  silk.  The  eggs  are  ovoid,  about  1/25  of  an  inch 
long,  with  a  granulated  cap  or  operculum;  they  are  firmly  cemented  to 
the  hair.  The  freshly  laid  egg  is  almost  transparent,  but  as  the  embryo 
develops  it  assumes  a  yellowish  color.  The  empty  shell  is  hard  and  re- 
mains attached  after  the  louse  has  emerged.  The  shell  and  the  cenaent 
is  resistant  to  chemicals,  no  solution  will  remove  it  without  first  destroy- 
ing the  hair  or  fiber  to  which  it  is  attached.  At  the  temperature  which 
ordinarily  exists  between  the  skin  and  the  clothing,  the  eggs  hatch  in 
from  seven  to  ten  days,  but  if  kept  in  a  cooler  atmosphere,  the  incubation 
period  is  lengthened.     The  first  molt  occurs  after  two  days;  the  second, 

^'"Parasitology,  IX,  293:   X,  No.  1;  X,  No.  4,  X,  375-382;  X,  383. 
^"^Brit.  Med.  Jbur.,  1,  788-9,  June  3,  1916. 


364  INSECT-BOENE  DISEASES 

two  days  later;  and  the  third,  after  three  days.  A  complete  cycle  from 
egg  to  egg  takes  about  sixteen  days. 

Oviposition  in  Pediculus  humanus  commences  twenty-four  to  thirty- 
six  hours  after  the  emergence  of  the  female  from  the  third  larval  skin. 
The  number  of  eggs  laid  depends  upon  the  food  supply  and  the  tempera- 
ture at  which  the  female  is  maintained.  Under  optimum  natural  condi- 
tions, three  hundred  eggs  represent  the-  normal  number  which  a  female 
is  capable  of  laying.  Bacot  ^°^  states  that  a  female  louse  under  ideal 
conditions  might  have  four  thousand  offspring  during  her  lifetime.  The 
average  life  of  a  louse  is  from  thirty-five  to  forty  days,  probably  a  little 
less  for  the  males.  Development  of  eggs  is  eight  days  at  33°  C,  which  is 
the  optimum  temperature.  This  period  may  be  lengthened  or  shortened 
by  varying  the  temperature.  Therefore,  persons  who  remove  their 
clothing  at  night  will  become  less  heavily  infested  than  those  who  wear 
their  clothing  continuously.  The  periodic  cooling  of  the  clothing  and 
contained  lice  leads  to  their  progeny  being  materially  reduced. 

Lice  feed  immediately  after  emerging  from  the  egg.  A  young  louse 
will  die  within  twenty-four  hours  if  no  food  is  obtainable,  while  a  well 
fed  louse  can  live  ten  days  away  from  its  host.  Lice  feed  many  times 
during  the  day.  They  feed  most  frequently  at  night  when  the  host  is 
at  rest.  When  lice  become  ravenous  with  hunger  they  feed  to  excess 
and  may  rupture  their  intestinal  canal.  The  louse  depends  upon  the 
salivary  secretion  to  dilate  the  capillaries  so  that  blood  flows  freely. 
While  feeding,  the  insect  passes  excreta,  which  contains  a  large  propor- 
tion of  undigested  red  blood  cells. 

Vermin  infestation  is  spread  either  by  contact  with  infested  persons 
themselves,  their  clothing  or  their  personal  effects.  One  vermin-infested 
man  may  spread  lice  to  many  of  his  associates.  The  soldiers  abroad 
believed  that  trenches  and  dugouts  were  "lousy"  and  that  they  obtained 
their  infestation  from  them.  This  was  not  exactly  true,  for  the  infesta- 
tion was  obtained  owing  to  the  overcrowding  in  these  places.  Lice 
desert  their  host  when  the  person  has  fever  or  dies.^^°  In  the  first  instance 
the  excessive  heat  drives  them  off,  and  in  the  latter  the  lack  of  food 
supply.  Lice  may  be  dislodged  by  brushing  and  so  fall  to  the  ground. 
It  has  been  found  that  lice  buried  at  a  depth  of  four  inches  will  crawl 
to  the  surface.  They  may  be  blown  by  wind.  Lice  are  ordinarily  not 
found  in  bedding  and  blankets  unless  recently  occupied  by  vermin 
infested  individuals. 

Lice  are  most  often  found  in  those  parts  of  the  garment  which 
are  in  closest  contact  with  the  body,  such  as  the  fork  of  the  trousers, 
waistline,  armpits  and  neck.     They  are  found  in  the  inner  as  well  as 

^"^Parasitology,  IX,  228-258,  Feb.  26,  1917.  Proc.  Royal  Soc.  Med.,  London, 
X,  61-94,  June,  1917. 

""  Observed  by  Plotz  during  typhus  fever  epidemic  in  Serbia  and  Bulgaria, 
1915-16. 


LICE  366 

the  oiitor  ^rarineiits.  Lice  may  be  fouiul  on  any  garment  or  article 
worn  by  an  infested  man.  In  conduct iii^^  inspections  for  lousiness,  it 
is  important  to  remondx-r  this,  and  to  bear  in  mind  that  the  body  louse 
may  lay  its  eg^s  on  the  hair  of  the  head  as  well  as  any  other  hairy 
part  of  the  body.  This  is  of  importance^  and  neglect  of  it  leads  to 
unsatisfactory  results.     The  delousing  of  clothing  alone  is  not  sufficient. 

redicuJus  capids,  or  the  head  louse,  is  perhaps  the  commonest 
variety  of  louse  in  ci\il  life.  Sobol  ^^^  states  that  about  twenty-two  per 
cent,  of  the  school  children  in  Xew  York  are  infested,  some  150,000  to 
185,000  cases  being  reported  during  the  years  1909  to  1912.  P.  capitis 
shows  no  material  difference  in  its  biology  from  the  P.  corporis:  It 
lays  fewer  eggs  and  is  perhaps  shorter  lived.  It  is  found  mostly  in 
children,  especially  in  girls  on  account  of  their  long  hair,  and  in  old 
people.  It  is  fond  of  the  temporal  and  occipital  regions.  Although 
the  hairy  head  is  the  common  habitat,  still  it  may  be  found  on  other 
parts  of  the  body,  in  which  case  it  would  be  difficult  to  say  whether  it 
yvas' corporis  or  capitis.  This  insect  is  spread  by  contact  such  as  occurs 
in  schools,  and  by  brushes  and  hats.  The  common  clothes-hook  in  school 
houses  may  be  a  method  of  transfer.  If  hair  is  worn  short  infestation 
rarely  occurs.  It  has  been  reported  by  Goldberger  ^^^  that  the  head 
louse  may  transfer  typhus  fever. 

An  effective  treatment  is  to  anoint  the  head  with  a  mixture  of 
equal  parts  of  kerosene  and  vinegar  or  kerosene  and  olive  oil;  head  to  be 
wrapped  in  a  towel  over  night  and  shampooed  in  the  morning.  Eepeti- 
tion  of  this  procedure  may  be  necessary.  Combing  with  a  fine^  warm 
comb  will  remove  the  nits.  In  males  the  hair  should  be  cut  (see  page 
1347). 

Phthirus  pubis,  crab  louse. — This  insect  looks  unlike  Pediculi  and 
closely  resembles  a  crab.  It  is  about  one-sixteenth  of  an  inch  long. 
It  is  usually  found  in  the  pubic  and  perianal  region,  but  may  be  found 
over  the  abdomen  and  chest,  axillae  and  down  over  the  thighs.  Crab 
lice  have  been  found  in  the  eyebrows.  The  nit  is  laid  near  the  base  of 
the  hair.  Phthirus  feeds  almost  continuously,  and  hence  dies  rapidly 
when  removed.  A  female  lays  about  twenty-five  eggs  in  her  lifetime. 
Eggs  hatch  in  about  seven  days.  Development  is  the  same  as  Pediculus. 
This  insect  is  transmitted  mainly  by  contact  in  lodging  houses,  houses 
of  prostitution,  bath  tubs,  and  from  toilet  seats.  It  has  not  been  known 
to  transmit  disease.  Treatment  consists  in  shaving.  If  skin  irritation 
is  present  apply  some  bland  ointment.  The  use  of  blue  ointment  may 
cause  skin  irritation  and  therefore  should  not  be  so  commonly  employed. 

Lice  Bites  and  Trajismission  of  Disease. — Lice  most  likely  transmit 
disease  by  way  of  the  excreta,  the  virus  gaining  entrance  through  the 

^  N.  Y.  Med.  Journ.,  XCVIII.  656-664,  Oct.  4,  1913, 
"="  Public  Health  Reports,  XXVll,  297-307,  1912. 


366  INSECT-BORNE  DISEASES 

punctured  wound  made  by  the  louse  while  feeding,  or  scratched  in  by 
the  individual.  Mueller  and  Urizio  ^^^  were  able  to  transmit  typhus 
fever  even  without  the  bite  of  the  insect.  Mueller  himself  contracted 
typhus  fever  as  the  result  of  an  accident,  in  which  an  emulsion  of  lice 
feces  spilled  on  his  hands.     The  period  of  incubation  was  17  days. 

The  effects  of  the  presence  of  lice  upon  men  differ  according  to 
individual  susceptibility.  Persons  who  are  constantly  vermin  infested 
are  immunized  against  the  salivary  secretion,  and  the  local  reaction  of 
the  bites  is  very  slight.  Sometimes  only  a  slight  puncture  wound  is 
discernible.  In  persons  who  have  never  been  lousy  before,  the  local 
reaction  is  intense  and  indicated  by  an  urticarial  wheal  or  hemorrhagic 
spot.  Lice  bites  in  themselves  may  cause  a  mild  febrile  reaction  and  a 
generalized  eruption  resembling  measles.^^* 

Delousing". — The  best  delousing  methods  should  not  only  destroy 
lice  and  their  eggs,  but  also  the  viruses  transmitted  by  the  insect. 
Fortunately,  the  viruses  of  relapsing  fever,  typhus  fever  and  trench 
fever  are  comparatively  frail;  they -are  destroyed  at  70°  C.  moist  heat 
for  30  minutes.  Lice  and  nits  are  killed  at  this  temperature;  also  at 
55°  C.  dry  heat  in  5  minutes.  It  is  a  comparatively  simple  matter  to 
kill  lice  and  their  nits — only  the  administrative  aspect  of  the  problem 
presents  any  real  difficulty.  The  most  frequently  used  methods  are  heat, 
chemicals  or  storage. 

Heat. — Dry  heat  is  convenient,  but  not  effective  in  large  scale  opera- 
tions because  it  lacks  the  power  of  penetration.  Dry  heat  has  the  ad- 
vantage in  the  case  of  leather  material  and  rubber  goods,  which  may  be 
thus  disinfested  without  injury.  Shoes  are  rarely  infested;  in  fact, 
leather  and  rubber  articles  as  a  rule  need  not  be  treated  except  in  the 
presence  of  heavy  infestations  or  an  epidemic.  Steam  penetrates  better, 
is  quicker,  surer ;  and  it  also  disinfects. 

Heat  may  be  applied  in  a  great  variety  of  ways : — boiling  water, 
Serbian  barrel,  steam,  flat  iron,  hot  oven,  hot  air  boxes  or  huts,  steam 
disinfectors. 

The  -flat  iron  was  employed  in  some  armies.  The  method  is  effective, 
but  impracticable  on  a  large  scale  as  it  is  time-consuming.  If  used  in 
connection  with  a  delousing  plant,  the  number  of  ironers  would  have 
to  equal  the  number  of  bathers  so  that  the  clothes  would  be  ready  for 
the  men  when  they  came  out  of  the  bath.  It  takes  about  15  minutes 
to  iron  a  uniform  and  underclothes. 

Hot  ovens  have  been  used.  This  method  may  be  applied  on  a  small 
scale.  Care  must  be  observed  not  to  scorch  the  clothing.  A  very  effec- 
tive hot  air  method  is  the  hot  air  hut,  described  by  Captain  Orr  of  the 

"5  Riforma  Medioa,  Aug.  30,  1919.  XXXV,  No.  35,  p.  734. 

"^  Hirschfelder  and  Moore:  Arch.  Int.  Med.,  Apr.  5,  1919,  XXIV,  No.  4,  p.  419. 

"^Parasitology,  Vol.  X,  No.  4,  p.  441,  May,  1918. 


LICE 


367 


Canadian  Army.^"  The  penetration  with  dry  heat  is  not  as  complete 
as  when  using  steam.  Stagnant  hot  air  is  less  cfTective  than  circulating 
hot  air.  In  the  front  area,  in  dugouts  and  trenches,  the  hot  box  ^^" 
may  be  used.  This  box  is  based  on  the  principle  of  the  firek^s  cooker, 
and  used  by  heating  a  piece  of  metal,  and  placing  the  clothing,  which 
is  protected  from  coming  in  contact  with  the  metal,  over  it.  The 
temperature  obtained  is  sutlicient  to  destroy  lice  and  eggs. 

Hot   water. — Lice  and  eggs  immersed   in  water  at  70^   C.  for  30 


Fig.  48. 


minutes  are  killed  with  certainty — this  method  is  not  practical  on  a 
large  scale. 

The  Serbian  barrel  is  one  of  the  best  improvised  methods  for  de- 
lousing  with  steam.  It  was  used  during  the  typhus  campaign  in  Serbia 
and  Bulgaria.  It  consists  of  a  large  barrel,  the  bottom  of  whi-ch  is 
freely  perforated,  while  the  top  is  removed  and  replaced  by  a  weighted 
lid.  At  the  lower  end  is  a  sand  bag  collar  to  prevent  the  escape  of 
steam,  which  enters  the  barrel  from  a  metal  boiler  upon  which  it  rests, 
both  barrel  and  boiler  being  imbedded  at  their  junction  in  the  brick 
work  forming  the  furnace.     The  furnace  may  be  made  long  and  narrow, 

"°  Devised  by  Harry  Plotz,  War  Department. 


368  mSECT-BOENE  DISEASES 

with  a  chimney  at  one  end^  and  the  boilers  and  barrels  placed  in  series. 
It  is  important  that  steam  be  generated  rapidly.  The  clothing  to  be 
deloused  is  placed  in  at  the  top  and  the  lid  placed  on  tightly.  After  the 
steam  is  generated,  the  clothing  remains  in  the  barrel  for  one  hour. 

All  clothing,  except  leather  material,  rubber  and  celluloid,  may  be 
handled  in  this  manner.  There  are  various  other  improvised  methods 
for  obtaining  steam  such  as  boxes  and  huts. 

Steam  Disinfectors. — The  large  commercial  steam  disinfectors  are 
the  best  and  quickest  way  of  delousing  large  quantities  of  clothing. 
With  the  aid  of  the  vacuum,  penetration  is  sure  and  the  materials  are- 
both  disinfested  and  disinfected.  Steam  may  also  be  used  in  improvised 
methods  in  a  freight  car,  obtaining  the  steam  from  the  locomotive;  or 
in  the  compartments  of  a  ship. 

The  steam  laundry  is  a  good  delousing  apparatus,  provided  live 
steam  is  run  into  the  wash  wheel.  It  takes  about  15  minutes  to  insure 
a  proper  temperature. 

Clothing  can  be  freed  of  lice  by  storage.  Sufficient  length  of  time 
must  elapse  for  the  adult  lice  to  die  and  nits  to  hatch.  Nuttall  '^'^'^ 
advises  clothing  stored  in  a  dry  temperature  for  two  to  three  weeks. 
Since  hatching  has  been  delayed  thirty-five  days  by  low  temperature, 
it  would  be  safe  to  allow  thirty  to  forty  days  during  cool  weather. 

Chemicals  are  used  for  two  purposes;  to  destroy  lice  and  nits  on 
clothing  and  hair,  or  to  repel  them.  Numerous  licicides  have  been 
recommended,  but  experience  has  shown  most  of  them  to  be  worthless; 
they  may  destroy  lice,  but  rarely  do  they  destroy  nits. 

The  most  effective  insecticides  for  louse  control  are  kerosene,  naph- 
thalene, carbonbisulphid  and  lysol.  The  English  employed  the  IST.  C.  I. 
powder  with  some  success.     This  consists  of 

Naphthalene    96  per  cent. 

Creosote    2  per  cent. 

Iodoform   2  per  cent. 

The  conmiercial  naphthalene  is  the  best.  This  powder  acts  as  a  repel- 
lent; therefore  it  should  be  dusted  into  the  clothing  frequently — every 
three  days.  The  best  results  are  obtained  by  dusting  the  seams  of  the 
clothing  freely  and  then  rolling  in  a  blanket.  Care  must  be  exercised 
in  using  the  powder  in  the  fork  of  the  trousers,  as  it  may  cause  smart- 
ing. Some  observers  have  had  just  as  good  results  with  crude  naphtha- 
lene. A  powder  consisting  of  talc,  20  gms.,  creosote,  1  c.  c,  sulphur, 
0.5  gms.,  has  been  suggested  by  Moore,^^®  and  is  supposed  to  be  effective. 
It  causes  less  irritation  to  the  skin  than  the  jST.  C.  I.  powder. 

^^''  Parasitology,  IX,  pp.  293-294;  X,  No.  1,  Nov.,  1917;  X,  No.  4,  May,  1918; 
X,  pp.  375-382;  X,  pp.  383-405. 

"VoMr?i.  Lab.  and  Clin.  Med.,  Ill,  1917-18,  p.  261. 


LICE  369 

In  conjunction  with  the  N.  C.  I.  powder,  the  Englisli  use  a  mixture 
known  as  Verniijclli,  which  consists  of: 

Crude  niiiicial   oil 5Vi>  pints. 

Soft  soap    -5       Ihs. 

Water    Mioiit  '/i:  P'"t. 

This  is  smeared  in  the  interior  seams  of  the  clothing.  Impregnation 
of  underclothing  with  various  chemicals  has  given  unsatisfactory  results. 
Sachets  are  only  elTective  for  a  short  time. 

Various  funngaiion  methods  have  heen  recommended,  but  experience 
has  shown  tliat  most  of  the  gases  do  not  destroy  nits.  The  value  of 
sulphur  and  formaldehyd  has  been  overestimated.  Nits  are  not  destroyed. 
The  use  of  liydrocyanic  acid  gas  has  been  recommended,  and  it  was 
found  that  3  ounces  to  3-|-  ounces  per  100  cubic  feet  would  be  sufficient 
to  kill  adult  lice  and  to  prevent  eggs  from  hatching,  Avhen  the  surface 
of  the  clothes  are  freely  exposed  to  the  fumes  for  one-half  hour.  When 
clothes  are  tightly  packed  in  trunks,  6  ounces  per  100  cubic  feet  with 
85  inch  vacuum  should  be  used  for  two  hours  in  special  apparatus. 
As  this  gas  is  very  dangerous,  it  should  not  be  employed  in  camps. 
It  does  not  destroy  bacteria.  Chlorpicrin  has  been  recommended  by 
Moore,^^^  who  states  that  it  penetrates  clothing  and  is  said  to  kill 
lice  and  eggs.    He  uses  4  c.  c.  to  1  cubic  foot  for  30  minutes. 

Lice  as  a  Military  Problem. — The  control  of  vermin  infestation  and 
louse-borne  diseases  was  one  of  the  important  sanitary  and  medical 
problems  of  the  World  War.  As  an  army  problem,  the  unprecedented 
scale  of  the  war,  combined  with  th,e  conditions  under  which  it  was 
fought,  led  to  a  prevalence  of  lice  among  soldiers  that  has  never  been 
equaled  before.  No  army  was  spared  from  widespread  vermin  infesta- 
tion, and  diseases  transmitted  by  this  pest.  The  louse  not  only  transmits 
typhus  fever,  trench  fever  and  relapsing  fever,  but  its  presence  disturbs 
the  morale  of  the  soldier  by  causing  irritation  of  the  skin  and  scratching, 
often  followed  by  infection,  loss  of  sleep  and  impaired  efficiency.  The 
loss  of  life  from  typhus  fever  in  Serbia  and  Eoumania  was  enormous, 
and  the  non-effective  rate  from  trench  fever  was  so  high  as  to  cause 
serious  concern. 

Vermin  infestation  in  our  army  was  prevalent.  It  is  said  that 
practically  every  man  that  reached  the  front  area  became  infested. 
Any  large  assemblage  of  soldiers  is  likely  to  contain  a  few  verminous 
individuals,  who  are  primarily  the  cause  of  the  trouble,  which  is  greatly 
aggravated   by  the  crowding  and   camp   conditions. 

The  method  of  excluding  vermin  infestation  and  louse-borne  dis- 
ease by  returning  troops  was  handled  in  the  following  manner  :^^°     All 

^"Jcnirn.  Lab.  and  Clin.  Med.,  Ill,  1917-18,  p.  261. 
""  War  Department  Order. 


370  INSECT-BORNE  DISEASES 

troops  were  detained  for  two  weeks  at  foreign  ports  before  boarding  a 
transport,  during  which  time  contagious  disease  was  isolated  and  de- 
lousing  was  practiced.  All  troops  were  again  examined  on  transports 
as  soon  after  departure  as  possible,  and  reexamined  again  after  six 
days.  During  the  intervening  time,  each  soldier  was  instructed  to 
examine  his  clothing  daily  for  vermin.  On  arrival  in  the  United  States, 
civilians  were  carefully  kept  from  coming  in  contact  with  soldiers. 
All  soldiers  were  sent  to  the  nearest  camp,  where  debusing  was  again 
practiced.  An  area  was  set  aside  for  the  receipt  of  "unclean"  troops, 
and  following  delousing  they  were  placed  in  a  clean  area.  Up  to 
July,  1919,  about  2,000,000  troops  were  returned  to  the  United  States, 
and  not  a  single  case  of  a  louse-borne  disease  was  introduced  into  this 
country,  and  vermin  infestation  was  not  carried  into  civil  communities 
by  demobilized  soldiers. 

The  delousing  plant  ^^'^^  devised  by  Major  Harry  Plotz  is  shown  in 
Figure  49.  It  can  handle  200  soldiers  and  their  equipment  an  hour.  The 
U.  S.  Public  Health  Service  also  has  efficient  plants  at  its  maritime 
quarantine  stations,  and  traveling  railroad  equipment  for  work  on  the 
Mexican  border. 

TYPHUS  FEVER 

(Typhus  Exanthematicus) 

Typhus  fever  was  formerly  confused  with  typhoid  fever.  Louis  in 
1829  named  typhoid  fever,  but  it  remained  for  one  of  his  pupils, 
Gerhard,  clearly  to  lay  down  the  difference  between  the  two  diseases. 
Previous  to  that  time,  typhus  fever  was  prominent  and  prevailing, 
while  typhoid  fever  was  unknown  as  such  and  probably  did  not  occur 
in  great  epidemics.  Up  to  the  time  of  the  World  War,  the  situation 
was  reversed;  typhoid  fever  had  become  pandemic,  while  typhus  fever 
had  receded  with  civilization  and  improvements  in  sanitation.  Since 
the  beginning  of  the  World  War,  epidemics  of  typhus  fever  have  occurred 
in  Serbia,  Bulgaria,  Turkey,  Eussia,  Poland,  Germany  and  Mexico. 
The  history  of  this  disease  has  been  repeated  again.  War  followed  by 
poverty  and  distress  associated  with  vermin  infestation  favors  the  spread 
of  typhus  fever. 

Typhus  fever  is  a  disease  of  cool  and  temperate  climate,  and  is 
found  in  Europe,  Asia,  Africa  and  America,  the  most  common  foci  being 
Eussia  and  the  Balkans,  Ireland,  Poland,  Galicia,  Spain,  Italy  and 
Mexico.  In  ten  years,  1871-80,  in  Ireland  7,495  deaths  were  reported 
from  typhus  fever;  in  three  years,  1909-11,  the  number  had  fallen  to 
143.  It  is  reported  that  Serbia  lost  150,000  people  from  this  disease 
alone,  during  the  winter  of  1915-16. 

i3o»  rpj^g  details  of  construction  and  operation  are  described  in  /.  A,  M.  A., 
Feb.  1,  1919,  Vol.  LXXII,  p.  324. 


LICE 


371 


^ 


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2 

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tt: 


Zn  .  INSECT-BORITE  DISEASES 

Typhus  fever  prevailed  in  epidemic  form  in  the  United  States  in 
New  York  in  1881-1882,  and  again  in  1892-1893,  and  in  Philadelphia  in 
1883.  Since  then,  except  for  a  few  sporadic  cases  at  our  seaports,  the 
disease  has  been  thought  to  be  non-existent  in  the  United  States.  .How- 
ever, Anderson  and  Goldberger  have  shown  the  close  relationship  be- 
tween the  symptom '  complex  known  as  "Brill's  Disease"  and  ijyphus 
fever,  and  believe  that  European  typhus  fever  and  the  typhus  fejver  or 
"tabardillo"  of  Mexico  are  the  same  disease.  It  is  now  evident  that 
typhus  fever  has  been  smoldering  in  New  York  a  great  many  years, 
certainly  since  1896,  when  BriU  first  observed  the  cases  v/hich  he ' 
described.  The  disease  in  New  York  is  generally  mild.  It  is  believed 
that  some  cases  are  not  diagnosed;  therefore,  we  face  a  new  sanitary 
problem  in  this  country.  Typhus  fever  in  virulent  form  is  now  (1921) 
being  reintroduced  into  the  United  States  with  the  tide  of  immigration 
from  epidemic  centers. 

Typhus  fever,  when  prevalent  in  epidemic  form,  has  been  said  by 
the  older  writers  to  be  one  of  the.  most  highly  contagious  of  febrile 
diseases;  doctors  and  nurses  and  others  in  close  contact  with  the  disease 
being  almost  invariably  stricken.  Typhus  fever  claims  more  victims 
in  the  medical  profession  than  any  other  epidelnic  disease.  The  loss  of 
life  of  physicians  in  Serbia  and  Bulgaria  was  particularly  high.  The 
sad  case  of  Eicketts,  who  lost  his  life  in  endeavoring  to  unravel  this 
pathologic  puzzle  in  Mexico,  is  still  fresh  in  our  minds.  Others  who 
have  sacrificed  their  lives  in  studying  this  disease  are  Donnelly  and 
Macgruder  in  Serbia,  Husk  in  Mexico,  and  Jochmann  and  Prowazek 
in  Germany. 

The  period  of  incubation  is  from  five  to  twenty  days,  with  an  average 
of  twelve.  Typhus  epidemics  prevail  during  cold  weather — the  disease 
dies  down  in  summer,  probably  due  to  the  fact  that  heat  renders  lice 
sluggish.  One  attack  confers  a  very  definite  immunity,  second  attacks 
being  very  unusual. 

Etiolo^ — Rickettsia. — Bickettsia  are  small,  bacteria-like  bodies, 
probably  belonging  to  the  protozoa.  They  stain  with  difficulty;  best 
with  Geimsa  or  one  of  the  modifications  of  Romanowski's  stain.  EicTcett- 
sia  occur  in  pairs  and  clusters  within  the  cells  in  typhus  and  Rocky 
Mountain  spotted  fever  and  without  the  cells  in  trench  fever.  They  are 
small — a  pair  measures  about  one  micron  long.  They  do  not  grow  in 
artificial  culture  media.  They  are  frail  and  easily  killed.  Rickettsia 
appear  to  be  a  group  of  microorganisms  especially  adapted  to  insect 
life.  Some  representatives  of  the  group  are  pathogenic  for  man  and 
animals. 

Rickettsia  prowazeki  is  now  believed  to  be  the  cause  of  typhus  fever. 
It  was  named  by  da  Rocha  Lima  ^^^  in  memory  of  Ricketts  and  Prowa- 
"^Deutsch.  med.  Woch.,  July  3,  1919,  p.  732. 


LICE  373 

zek,  both  of  whom  siUTiunbLHl  to  iyplius  while  investigating  the  disease. 

Rickettsia,  prowazeki  found  in  typhus  fever  and  Rocky  IMountain 
spotted  fever  differs  from  Rickett.sia  pcdicuH,  associated  wiih  trench 
fever,  in  that  the  former  is  fomid  especially  in  the  epitlielial  colls  of  the 
alimentary  canal  of  the  louse,  while  the  latter  occurs  only  in  the  lumen 
of  the  alimentary  canal,  and  not  in  the  cells  of  the  louse. 

Wolbach  ^"  states  that  the  patholog}^  of  typhus  fever  consists  largely 
of  lesions  of  the  blood  vessels.  There  is  disintegration  of  the  endothelium 
and  proliferation  causing  thrombi  and  hemorrhages,  also  perivascular 
infiltration  with  cells.  These  lesions  in  the  brain  account  for  the  de- 
lirium and  other  mental  symptoms  which  are  prominent  in  typhus  fever. 
Similar  lesions  of  the  blood  vessels  of  the  skin  produce  the  macular  and 
hemorrhagic  eruption.  The  thrombi  give  rise  to  gangrene  which  is  often 
symmetrical. 

The  Weil-Felix  Reaction. — The  blood  of  typhus  fever  patients 
agglutinates  a  proteus-like  organism,  and  this  reaction  is  specific  and 
diagnostic,  despite  the  fact  that  the  proteus-like  bacillus  is  not  the 
cause  of  typhus  fever.^-^  This  reaction  appears  to  be  due  to  the  fact  that 
typhiis  fever  blood  contains  non-specific  agglutinins,  for  it  will  not  only 
actively  clump  the  proteus-like  bacilli,  but  also  typhoid,  dysentery  and 
many  other  bacilli. 

The  disease  may  be  transmitted  by  blood  inoculations  to  man, 
chimpanzees,  lower  monkeys  and  guinea-pigs.  The  reaction  in  animals 
is  quite  typical,  characterized  by  an  incubation  period  which  varies  from 
7  to  10  days  in  guinea-pigs,  and  rise  of  temperature  from  7  to  11  days, 
usually  ending  by  crisis.  An  animal  that  has  gone  through  such  a 
reaction  is  immune.  A  large  percentage  of  guinea-pigs  is  immune 
to  the  first  blood  inoculation  and  many  are  naturally  immune.  The 
virus  as  it  exists  in  the  circulating  blood  does  not  pass  through  a 
Berkefeld  filter.  It  is  not  killed  by  freezing  for  8  days,  but  is  deprived 
of  virulence  by  heating  at  55°  C.  for  15  minutes. 

Transmission. — Tobias  Coberus,  in  the  beginning  of  the  17th  cen- 
tury, associated  the  louse  with  typhus  fever,  but  ISTicolle,  Compte  and 
Conseil,  in  1909,  were  the  first  to  report  the  transmission  of  typhus 
fever  by  the  bite  of  the  louse  (Fed.  vestimenti).  Their  work  was  sug- 
gested b)^  the  successful  transmission  of  relapsing  fever  through  lice,  by 
Sergent.  Since  the  work  of  Nicolle  and  his  collaborators,  his  work  has 
been  confirmed  by  Eicketts  and  Wilder,  Anderson  and  Goldberger,  and 
others.  Goldberger  has  shown  that  the  head  louse  (Fed.  capitis)  may 
also  transmit  this  infection.  The  period  of  infectivity  in  lice,  follow- 
ing exposure  on  typhus  patients,  is  reported  to  vary  from  2  to  10  days 

^^International  Jour,  of  Puhlic  Health,  Sept.,  1920,  I,  No.  2;   Joum.  Med. 
Res.,  Nov.,  1919.  p.  197;  Journ.  Inf.  Dis.,  July,  1915,  p.  1. 
^^  Wien.  klin.  Wochnschr.,  XXIX,  Ko,  2,  1916. 


374  INSECT-BORNE  DISEASES 

by  different  observers.  Eiekettsia  bodies  have  been  found  in  the  stomach 
wall  of  typhus  infected  lice  by  Prowazek,  da  Rocha  Lima,  Wolbach  and 
others. 

The  feces  of  typhus-infected .  lice  are  infective  for  animals.  There 
is  a  difference  of  opinion  as  to  the  method  of  transmission  of  typhus 
fever  by  the  louse ;  that  is,  whether  it  occurs  by  tlie  bite  or  through  the 
excreta.  The  disease  is  most  likely  introduced  through  the  feces,  the 
virus  gaining  entrance  through  the  punctured  wound  made  by  the 
louse  while  sucking,  or  scratched  in  by  the  host. 

The  role  of  the  body  louse  in  the  transmission  of  typhus  fever  will 
receive  ready  support  from  students  of  the  epidemiology  of  typhus 
fever,  for  this  disease  presents  all  the  characteristics  of  an  insect-borne 
disease.  In  practice,  the  control  of  lice  has  greatly  reduced  the  incidence 
of  the  disease.  Since  the  transmission  of  the  disease  by  the  louse  has 
been  shown,  we  can  understand  why  typhus  fever  prevails  in  epidemic 
form  only  in  overcrowded,  filthy,  unhygienic  surroundings,  and  the 
truth  is  readily  understood  of  the  oft  quoted  sentence  of  Hirsch  that 
"the  history  of  typhus  is  the  history  of  human  wretchedness." 

Prevention. — The  disease  has  been  greatly  decreased  in  civilized 
centers  with  a  diminution  of  lousiness.  The  prevention  of  typhus  now 
focuses  itself  upon  the  eradication  of  the  body  louse — a  question  of 
personal  cleanliness.  Typhus  fever  is  also  a  social  problem  in  that  it 
is  so  closely  interwoven  with  squalor,  ignorance  and  poverty.  Meas- 
ures primarily  directed  to  the  destruction  of  lice  and  their  eggs  are 
described  on  page  366. 

In  the  presence  of  a  typhus  epidemic,  a  separate  typhus  hospital 
should  be  established  and  a  separate  building  or  enclosure  for  typhus 
contacts.  When  a  case  of  typhus  fever  is  discovered,  the  patient  should 
be  removed  to  the  typhus  fever  hospital,  never  treated  at  home.  All 
the  clothing  should  be  removed  in  the  receiving  ward,  and  all  articles 
of  apparel  taken  away.  This  material  should  be  disinfected  by  steam 
and  placed  in  a  storeroom;  never  allowed  to  be  taken  into  the  ward. 
The  hair  of  the  head,  axillary  and  pubic  region  should  be  cut  with  a 
hair  clipper.  The  hair  should  be  carefully  collected  and  burned.  The 
patient  is  then  bathed,  using  warm  water  and  a  kerosene  soap  mixture. 
Patients  can  be  rapidly  handled  if  the  receiving  department  is  divided 
into  a  receiving  room,  barber  shop,  bath  room,  drying  room,  and  examin- 
ing room.  The  patient  is  given  clean  pajamas  in  the  examining  room 
and  then  sent  to  the  ward.  Stress  is  laid  on  this  procedure  of  admitting 
patients,  in  order  to  prevent  lice  from  getting  into  the  ward. 

Daily  vermin  examinations  are  made  on  the  patients  and  in  the 
bedding.  Lice  wander  from  the  host  during  fever;  hence  they  may  be 
found  in  the  bedding.  This,  no  doubt,  accounts  for  the  high  incidence 
among  physicians  and  nurses.     AU  attendants  in  the  wards  and  all 


LICE  375 

nurses  and  doctors  should  wear  louse-proof  suits.  This  is  a  garment 
made  of  heavy  muslin,  like  pajamas,  which  goes  over  and  covers  the 
shoes  and  is  tied  about  the  neck.  A  hood  may  be  attached.  Cotton 
gloves  are  sewed  in  the  sleeves  by  machine  stitching.  Nurses  should 
wear  the  same  garment  with  a  skirt.  A  sterilized  garment  should  be 
put  on  each  time  the  attendant,  doctor  or  nurse  enters  the  ward.  On 
leaving  the  ward,  the  garment  is  removed  by  an  attendant,  preferably  a 
typhus  immune,  placed  in  a  bag  and  steamed.  A  shower  room  and 
clothes  closet  should  be  provided  near  the  exit  of  the  ward,  where 
nurses  may  change  their  costume.  Under  no  circumstances  should, 
visitors  be  allowed  into  the  ward.  In  typhus-stricken  countries,  one 
must  be  extremely  cautious  of  the  attendants.  As  these  people  usually 
come  from  the  peasant  class,  where  the  epidemic  prevails,  their  habits 
of  cleanliness  are  usually  very  primitive.  They  must  be  taught  the 
value  of  cleanliness,  supplied  with  proper  living  quarters  and  repeatedly 
inspected  for  vermin.  They  should  be  isolated  during  the  epidemic.  It 
is  preferable  to  have  typhus  immunes  as  attendants  in  the  hospital. 

The  room  from  which  the  patient  is  removed  should  be  fumigated 
with  sulphur,  or,  better,  hydrocyanic  acid  gas,  and  cleaned  with  kero- 
sene, and  should  then  be  closed  for  two  weeks  if  possible.  A  portable 
steam  disinfector  is  useful  to  disinfest  and  disinfect  fabrics,  etc.,  in  a 
tvphus  campaign.  Carriages  and  wagons  which  carry  patients  to  the 
hospital  should  be  carefully  inspected  for  lice  and  cleaned.  If  patients 
are  removed  on  trains,  the  cars  should  be  cleaned  by  vacuum  cleaner  and 
washed.  During  an  epidemic,  all  plush  on  railway  cars  should  be  re- 
moved ;  abroad  only  freight  cars  or  third-class  cars  are  employed. 

All  contacts  should  be  isolated  for  fourteen  days  at  least;  twenty- 
one  days  would  be  better,  in  a  separate  building  or  camp,  being  carefully 
deloused  before  entering.  They  should  be  directed  to  examine  their 
clothing  daily  for  lice  and  should  be  inspected  for  vermin  by  medical 
officers  daily.  Their  temperature  should  be  taken  twice  daily  and 
daily  inspections  made  for  the  first  symptoms  of  the  disease. 

An  educational  campaign  should  be  carried  on  in  the  cities  by  lectures 
in  public  places  and  schools,  pamphlets,  sermons  and  moving  pictures. 
As  tv'phus  fever  is  usually  associated  with  ignorance,  poverty  and  dis- 
tress, sanitary  instructions  as  well  as  proper  clothing  and  food  should 
be  supplied  the  stricken  people. 

The  fact  should  be  kept  constantly  in  mind  that  the  louse  is  necessary 
for  the  spread  of  tv'phus  fever,  just  as  the  mosquito  is  for  the  spread  of 
malaria,  and  our  efforts  towards  prophylaxis  should  be  conducted  with 
this  point  continuously  in  mind.  Even  with  the  knowledge  of  the  mode 
of  transmission  of  typhus  fever,  individual  prophylaxis  is  still  some- 
what difi&cult,  especially  where  infected  insects  abound  in  thickly  popu- 
lated centers. 


376  INSECT-BOENE  DISEASES 


TRENCH  FEVER 


Trench  fever  is  a  specific  infection  due  to  a  filterable  virus  trans- 
mitted by  the  louse  Pediculus  liumanus,  var.  corporis.  The  disease  is 
characterized  in  its  early  febrile  stage  by  recurrent  pyrexia,  headache, 
giddiness,  a  slow  pulse  in  comparison  to  the  degree  of  fever,  sweating, 
polyuria,  and  a  moderate  leukocytosis  at  the  height  of  the  fever.  Trench 
fever  is  never  fatal,  and  complete  recovery  usually  takes  place.  A  cer- 
tain percentage  of  the  patients,  however,  pass  into  a  stage  of  chronic 
ill  health;  that  is,  they  suffer  with  recurrent  pains  in  the  limbs,  head- 
ache and  nervous  manifestations,  such  as  mental  depression,  excessive 
tendency  to  sweating,  disordered  action  of  the  heart,  mild  degree  of 
anemia,  and  some  loss  of  weight.  The  infection  in  some  cases  is  very 
persistent,  and  acute  febrile  relapses  may  occur  after  months  ,of  quies- 
cence. 

The  Trench  Fever  Commission  of  the  American  Eed  Cross  ^^*  con- 
cluded, as  a  result  of  extensive  researches  as  follows: 

1.  Trench  fever  is  a  specific  infectious  disease;  it  is  not  a  modified 
form  of  typhoid  or  paratyphoid  fever,  and  is  not  related,  from  an 
etiological  standpoint,  to  these  diseases. 

2.  The  organism  causing  the  disease  is  a  resistant  filterable  virus. 

3.  The  virus  causing  trench  fever  is  present  particularly  in  the 
plasrha  of  the  blood  of  trench  fever  cases,  and  such  plasma  will  produce 
the  disease  on  inoculation  into  healthy  individuals. 

4.  The  disease  is  transmitted  naturally  by  the  louse  Pediculus  liu- 
manus, Linn.,  var.  corporis,  and  this  is  the  important  and  common  means 
of  transmission.  The  louse  may  transmit  the  disease  by  its  bite  alone, 
the  usual  manner  of  infection,  or  the  disease  may  be  produced  arti- 
ficially by  scarifying  the  skin  and  rubbing  in  a  small  amount  of  the 
infected  louse  excrement. 

5.  A  man.  may  be  entirely  free  from  lice  at  the  time  he  develops 
trench  fever,  the  louse  that  infected  him  having  left  him  some  time 
previously  as  its  host,  and  the  louse  need  only  remain  upon  the  indi- 
vidual for  a  short  period  of  time  in  order  to  infect  him. 

6.  The  virus  of  trench  fever  is  also  sometimes  present  in  the  urine 
of  trench  fever  cases,  and  occasionally  in  the  sputum,  and  the  disease 
may  be  produced  in  man  by  the  introduction  of  the  virus  in  the  urine 
or  sputum  through  the  scarified  or  otherwise  abraded  skin. 

7.  Since  the  urine  and  sometimes  the  sputum  of  trench  fever  patients 

"*  Trench  Fever.  Report  of  Commission,  Medical  Research  Committee,  Amer- 
ican Red  Cross:  Major  Richard  P.  Strong,  Major  Homer  Swift,  Major  Eugene 
L.  Opie,  Captain  Ward  J.  MacNeal,  Captain  Walter  Baetjer^  Captain  A.  M,  Pap- 
penheimer,  Captain  A.  D.  Peacock,  and  Lieutenant  David  Rappoport.  '  Oxford 
Univ.  Press,  1918.  ,.     - 


LTOR  377 

are  infective,  these  i^hould  be  sterilized  in  order  to  avoid  Ihe  possibility 
of  accidental  infection  from  them. 

8.  In  order  to  prevent  trench  fever  or  liniil  its  sincail,  and  thus 
save  man-power  for  the  armies,  greater  efforts  miisl  1)"  made  to  keep 
soldiers  in  general  from  infestation  with  lice. 

The  method  of  transmission  of  trench  fever  was  still  I'urlliLT  eluci- 
dated by  the  work  of  Byam  and  his  associates  on  the  British  Trench 
Fever  Commission.^-''  They  found  that  biting  by  infected  lice  was  not 
of  itself  sufficient  to  transmit  the  disease,  but  that  the  excreta  of  such 
lice,  rubbed  into  the  scarified  skin,  would  do  so  witli  great  regularity. 
The  excreta  were  found  to  be  infective  only  after  an  interval  of  seven 
days  or  more  after  feeding  on  the  trench  fever  patient;  this  fact  sug- 
gests the  possibility  that  the  organism  undergoes  a  developmental  cycle 
within  the  louse.  Lice  were  found  to  remain  infective  for  a  period  of 
at  least  twenty-three  days  after  feeding  on  the  patients.  These  experi- 
ments indicate  that  infection  in  nature  probably  occurs  by  rubbing  in 
the  louse  excreta  in  the  process  of  scratching. 

The  cause  of  trench  fever  is  believed  to  be  Eickettsia  pedicuU,  which 
are  described  on  page  373.  The  lesions  of  the  disease  are  largely  vascu- 
lar, similar  to  those  described  for  typhus  fever  and  Rocky  Mountain 
spotted  fever. 

Trench  fever  is  a  war  disease.  While  it  is  not  fatal,  the  morbidity 
resulting  from  it  exceeded  that  from  any  other  disease  on  the  western 
front  in  the  World  War.  JSTo  epidemics  of  the  disease  have  been  re- 
ported in  civil  life. 

The  prevention  of  trench  fever  resolves  itself  primarily  upon  an 
attack  against  lice.  In  addition,  urine,  sputum  and  other  secretions  are 
infective  and  disinfection  must  be  practiced.  The  Eed  Cross  Commis- 
sion recommends  the  following  measures : 

Exceedingly  great  care  should  be  taken  completely  to  disinfect  all 
patients  as  soon  as  practicable,  and  particularly  upon  their  entering 
the  hospital.  Patients  on  entrance  should  be  carefully  bathed,  and  sub- 
sequently sponged  with  alcohol.  Their  clothing  and  blankets  should  be 
removed,  and,  whether  or  not  lice  or  ova  are  found  upon  them,  should 
be  carefully  sterilized  by  moist  heat  at  a  temperature  not  below  70°  C. 
for  half  an  hour,  since  it  is  possible  for  the  virus  to  be  still  present  on 
the  clothing.  It  should  be  borne  in  mind  that  a  man  with  trench  fever 
may  be  entirely  free  from  lice  at  the  time  that  he  develops  symptoms 
of  the  disease.  Trench  fever  patients  should  at  all  times  be  carefully 
protected  from  louse  infestation,  and  inspection  of  them  for  lice  should 
be  made  daily.  They  should  be  treated  in  separate  wards.  As  the 
urine  contains  the  virus  and  is  infective,  it  should  be  sterilized  during 
the  active  stages  of  the  disease.     Sputum  cups  should  be  provided  for 

"'Jour.  A.  M.  A.,  LXXI,  pp.  21,  110,  188,  1918. 


378  IlSrSECT-BOENE  DISEASES 

patients,  and  any  expectorated  sputum  and  saliva  from  them  sterilized. 
Officers  should  regard  the  systematic  destruction  of  lice  as  one  of  the 
most  urgent  of  their  duties,  and  should  exercise  every  effort  to  prevent 
louse  infestation  among  soldiers  an"d  to  see  that  any  of  them  infested 
with  lice  are  promptly  disinfected  and  their  clothing  sterilized.  The 
above  precautions  are  of  the  utmost  importance  in  order  to  prevent  the 
further  spread  of  trench  fever  among  troops. 


BEDBUGS 

Cimex  lectularius  has  been  carried  by  man  to  all  parts  of  the  in- 
habited world.  It  has  become  a  true  domesticated  animal  and  has 
accommodated  itself  well  to  the  environment  of  human  habitations. 
The  bedbug  has  no  wings  and  a  very  flat  body,  which  enables  it  to  hide 
in  the  narrowest  chinks  and  cracks  of  beds  and  walls.  It  may  subsist 
for  incredibly  long  periods  of  time  without  food.  It  is  nocturnal  in  its 
habits. 

The  pronounced  odor  of  this  insect  is  produced  by  certain  glands 
opening  on  the  back  of  the  abdomen  in  young  bugs  and  on  the  under 
side  of  the  metasternum  in  the  adults.  The  odor  is  common  to  most 
members  of  the  group  to  which  this  insect  belongs.  It  is  useful  in 
plant  bugs,  protecting  them  from  their  enemies. 

The  bedbug  ^^®  undergoes  an  incomplete  metamorphosis,  the  young  be- 
ing very  similar  to  their  parents  in  appearance,  structure,  and  habits. 
The  eggs  are  white,  oval  objects  having  a  little  projecting  rim  around 
one  edge,  and  are  laid  in  batches  of  from  six  to  fifty,  in  cracks  and 
crevices  where  the  bugs  go  for  concealment.  The  eggs  hatch  in  a  week 
or  ten  days  and  the  young  escape  by  pushing  the  lid  within  the  pro- 
jecting rim  from  the  shell.  At  first  the  larvae  are  yellowish -white,  nearly 
transparent,  the  brown  color  of  the  more  mature  insect  increasing  with 
the  later  molts.  During  the  course  of  development  the  skin  is  shed  five 
times,  and  with  the  last  molt  the  minute  wing  pads,  characteristic  of  the 
adult  insect,  make  their  appearance.  Marlatt  found  that  under  favor- 
able conditions  about  seven  weeks  elapse  from  the  egg  to  the  adult  insect, 
and  that  the  time  between  molts  averages  about  eight  days.  Without 
food  they  may  remain  unchanged  for  an  indefinite  time.  Ordinarily 
but  one  meal  is  taken  between  molts,  so  that  each  bedbug  must  puncture 
its  host  five  times  before  becoming  mature,  and  at  least  once  afterward 
before  it  can  develop  eggs. 

The  presence  of  bedbugs  in  a  house  is  not  necessarity  an  indication 
of  neglect  or  carelessness.     They  are  very  apt  to  get  into  trunks  and 
satchels  of  travelers  or  may  be  introduced  in  the  homes  upon  the  cloth- 
es The  Bedbug,  V.  S.  Public  Health  Rpts.,  Dec.  10,  1920,  p.  2964. 


BEDBUGS 


379 


ing  of  servants,  workmen,  or  visitors.  The  bedbug  is  quite  capable  of 
migrating  from  one  house  to  another.  Ships  are  almost  sure  to  be 
infested  with  them.  They  are  not  especially  limited  by  cold,  and  are 
known  to  occur  well  north.  Th<'y  thrive  particularly  in  old  houses 
which  are  full  of  cracks  and  crevices,  in  which  they  can  conceal  them- 
selves beyond  easy  reach.  The  biting  organ  of  the  bedbug  is  similar 
to  that  of  other  hemipterous  insects.  The  skin  of  the  host  or  victim 
is  pierced  with  four  thread-like  hard  filaments  or  setae,  which  glide 
over  each  other  with  an  alternating  motion  and  thus  pierce  the  skin. 
The  blood  is  drawn  up  through  the  beak,  which  is  closely  applied  to 
the  point  of  puncture.    The  bite  of  the  bedbug  is  decidedly  irritating  to 


Fig.  50. — The  Bedbug. 

a,  Adult  female,  gorged  with  blood;   6,  Same  from  below;  c,  Rudimentary  wing 

pad ;  d,-  Mouth  parts.    After  Marlatt. 

some  individuals,   resulting  in   a   swelling  and  disagreeable  inj&amma- 
tion. 

The  Suppression  of  Bedbugs. — On  account  of  its  habits  of  conceal- 
ment the  bedbug  is  usually  beyond  the  reach  of  the  ordinary  insect 
powders,  which  are  practically  of  no  avail  against  it.  If  iron  or  brass 
bedsteads  are  used,  the  eradication  of  the  insect  is  made  easier.  Large 
wooden  bedsteads  furnish  many  cracks  and  crevices  into  which  the  bugs 
can  force  their  flat  thin  bodies,  and  extermination  becomes  a  matter 
of  considerable  difficulty.  The  most  practical  way  of  eradicating  bed- 
bugs is  by  a  very  liberal  application  of  gasoline,  benzene,  kerosene,  or 
any  other  of  the  petroleum  oils.  These  must  be  introduced  into  all  crev- 
ices with  small  brushes  or  feathers,  or  by  injecting  with  small  syringes; 
a  saturated  solution  of  corrosive  sublimate  in  water  is  also  of  value,  and 
oil  of  turpentine  may  be  used  in  the  same  way.  The  liberal  use  of  scald- 
ing hot  water  or  soap  suds  wherever  it  may  be  employed  without  damage 
to  furniture  is  also  an  effectual  method  of  destroying  both  eggs  and  active 


380  INSECT-BORI^E  DISEASES 

bugs.  Fumigation  with  hydrocyanic  acid  gas,  sulphur  dioxid,  or  carbon 
bisulphid  are  alike  effective.  Several  fumigations  may  be  necessary. 
Crevices  in  warm  parts  of  the  room  are  favorite  nesting  places,  as  under 
picture  moldings,  or  over  door  frames.  Finally,  the  room  should  be 
renovated,  all  imperfections  and  cracks  closed  and  sealed  with  paint. 

In  sleeping  cars  and  other  places  where  hydrocyanic  gas  may  be 
used  without  fear  of  accidents,  this  is  the  most  efficacious  and  least 
destructive  method. 

The  bedbug  has  long  been  under  suspicion  as  an  intermediate  host 
in  the  transference  of  many  communicable  infections.  There  is  more 
than  a  suspicion  that  it  is  concerned  in  relapsing  fever,  in  kala-azar, 
and.  it  has  been  accused  of  carrying  the  bacteria  of  plague,  leprosy,  and 
many  other  diseases.  On  the  other  hand,  there  is  no  convincing  evidence 
that  the  bedbug  is  the  usual  and  ordinary  insect  transmitter  of  these 
or  any  other  disease  at  present  known  to  us.  When  the  bedbug  acts  as 
an  intermediate  host,  it  apparently  does  so  by  mechanical  transmission 
of  the  virus  on  the  mouth  parts^and  this  occurs  only  under  grossly 
unsanitary  conditions.  Notwithstanding  the  minor  role  which  must  be 
assigned  the  bedbug  as  a  carrier  of  disease,  its  presence  is  an  offense 
against  sanitary  decency. 

LEISHMANIASIS 

(Kala^Azar,  "Dum-Dum  Fever"  Oriental  Sore,  Etc.) 

Leishmaniasis  ^^^  is  a  specific  infection  caused  by  a  minute  flagellated 
animal  parasite.  The  disease  usually  runs  a  chronic  course  and  is  char- 
acterized by  irregular  fever,  enlargement  of  the  spleen  and  anemia.  It 
is  found  in  most  tropical  countries,  but  is  unevenly  distributed.  It 
occurs  as  slowly  progressing  epidemics,  and  also  is  endemic  in  parts  of 
India,  China,  northern  Africa,  and  South  America.  There  are  three 
clinical  forms: 

(1)  Indian  Jcala-azar  (splenic  anemia)  is  a  chronic  disease  char- 
acterized by  a  very  large  spleen,  irregular  fever  and  anemia;  it  occurs 
at  all  ages.    It  is  caused  by  Leishmania  donovani. 

(2)  Mediterranean  hala-azar  usually  occurs  in  children  under  the 
age  of  five  or  six  years.  This  form  is  found  around  the  Mediterranean 
basin  and  is  characterized  by  the  severity  of  the  associated  anemia.  It 
is  caused  by  Leishmania  infantum. 

Laveran  believes  that  the  so-called  Indian  and  Mediterranean  forms 
of  the  disease  are  identical.  This  view,  however,  is  not  shared  by  other 
authorities.  Both  these  forms  are  generalized  infections  and  had  a 
high  mortality  (70  to  98  per  cent.)  before  the  use  of  tartar  emetic. 

"'Laveran,  A.:  Leishmaniases.  Kala-Azar.  Bouton  D'Orient.  Leishma- 
niose  Americaine.    Pub.  Masson  et  Cie.,  Paris,  1917. 


LEISHMANIASIS  381 

(3)  Oriental  sore  occurs  throufjhout  the  tropical  belt  and  passes 
under  many  names,  such  as,  'J'ropical  ulcer,  Delhi  boil,  Aleppo  boil, 
riskra  button,  and  Espundia.  Oriental  sore  usually  occurs  upon  the 
exposed  surface  of  the  body  and  starts  as  a  papule,  which  subsequently 
ulcerates.  The  ulcer  persists  for  months  or  years,  finally  healing  spon- 
taneously. It  la  thus  a  local  and  self-limited  form  of  leishmaniasis. 
The  parasite  (Lelshmania  iropica)  is  found  in  great  numbers  in  the 
ulcer,  but  apparently  never  becomes  disseminated  throughout  the  body. 
In  South  America  a  form  of  leishmaniasis  (Espundia)  occurs,  which 
often  extends  to  the  mucous  membrane  of  the  nose  and  palate,  causing  ex- 
tensive destruction  of  tissue  with  serious  deformity. 

The  parasite,  for  a  time  commonly  known  as  the  Leishman-Donovan 
body,  is  found  chiefly  in  the  endothelial  cells  of  the  liver,  spleen,  bone 
marrow  and  lymphatic  glands.  It  is  of  rounded  or  ovoid  form,  and 
contains  two  deeply  stained  granules  representing  nuclei.  This  body 
represents  the  non-motile  phase  of  the  life  cycle  of  a  flagellate.  It  was 
first  demonstrated  by  Leishman  ^-^  in  1900,  from  a  case  of  "Dum-dum 
fever."  Donovan  ^-^  in  1903,  found  similar  bodies  in  cases  in  ]\Iadras. 
James  Homer  Wright  ^^°  was  the  first  to  demonstrate  the  parasite  in  a 
case  of  Oriental  sore,  at  the  Massachusetts  General  Hospital,  in  Boston. 
The  nature  of  these  parasites  was  not  understood  until  Eogers  ^^^  suc- 
ceeded in  1904,  in  cultivating  them  in  citrated  blood  and  showed  them 
to  be  flagellated.  Later  on,  Xovy's  method  ^^^  for  the  cultivation  of 
trypanosomes  was  found  to  be  especially  useful.  On  Novy's  medium, 
the  parasite  increases  in  size,  develops  a  single  flagellum,  and  becomes 
actively  motile.  The  m?dium  known  as  X.  X.  X.  (Xovy-Mac  Xeal- 
Nicolle)  is  the  easiest  to  prepare  and  gives  the  best  results.  It  consists 
of  agar  (16  grams),  XaCl  (6  grams),  and  water  (9,000  c.  c),  which 
is  distributed  in  tubes,  sterilized  and  cooled  to  40°-50°  C,  when  one- 
third  its  volume  of  rabbit  blood  obtained  by  cardiac  puncture  is  added. 

Xo  marked  differences  have  been  discovered  between  the  three  "spe- 
cies" of  Leishmania  in  morphologic  or  cultural  characteristics.  Immune 
reactions  are  feeble  or  wanting,  which  corresponds  to  the  action  of  other 
animal  parasites.  A  certain  degree  of  immunity  is  present.  Thus,  Jew- 
ish physicians  in  Bagdad  have  long  practiced  inoculation  of  the  virus 
upon  the  leg  in  order  to  prevent  disfigurement  of  the  face. 

The  period  of  incubation  is  irregular,  and  somewhat  uncertain;  in 
Oriental  sore  it  may  be  months. 

The  precise  mode  of  transmission  of  leishmaniasis  is  still  in  doubt. 

^Brit.  Med.  Journ.,  1903,  I,  p.  125.3. 

^^  Lancet,   1904,  II,  p.  744;   also  Brit.   Med.  Journ.,   1904,  II,  p.  651. 
^^Join-n.  Med.  Research,  1903,  X,  3,  p.  472. 
^^Quar.  Journ.  Micros.  Sci.,  1904,  XLVIII,  p.  367. 

'^Contribution  to  Medical  Research,  dedicated  to  V.  C.  Vaughan,  Ann  Arbor, 
Michigan,  1903,  p.  549. 


382  INSECT-BORNE  DISEASES 

The  disease  is  limited  to  man,  except  that  it  occurs  naturally  in  dogs, 
especially  in  the  region  of  the  Mediterranean.  It  may  he  transmitted 
experimentally  to  monkeys,  dogs  and  mice.  The  disease  can  be  repro- 
duced in  man  and  animals  by  inoculation  of  pure  cultures,  or  tissue 
containing  the  parasites.  It  has  long  been  observed  that  in  regions 
where  it  is  endemic.  Oriental  sore  may  follow  injury  to  the  skin,  how- 
ever slight,  such  as  abrasions  or  insect  bites. 

Leishmaniasis  is  probably  an  insect-borne  disease,  although  wound 
infection  doubtless  also  occurs.  Experiments  designed  to  transmit-  the 
disease  by  blood-sucking  insects  have  thus  far  proved  unsuccessful.  The 
development  of  the  parasite  has  been  observed  in  various  blood-sucking 
arthropods.  Patton  ^"^  suspects  the  bedbug  as  the  iransmitter  and  finds 
that  Leishmania  donovani  can  develop  into  the  flagellate  stage  in  the 
digestive  tract  of  the  bedbug,  although  it  survives  for  only  a  short  time 
in  this  host.  Temporary  development  has  also  been  found  to  occur  in 
mosquitoes,  but  no  development  whatever  takes  place  in  lice  or  fleas. 
It  is  a  difficult  problem  to  differentiate  the  developing  forms  of  Leish- 
mania donovani  from  herpetomonads  which  naturally  occur  in  these 
insects. 

A  great  advance  in  the  treatment  and  prevention  of  leishmaniasis 
was  made  when  it  was  discovered  that  tartar  emetic  and  other  com- 
pounds of  antimony  are  specific  for  all  forms  of  the  infection.  Yianna  ^^* 
in  1913,  reported  the  effects  of  tartar  emetic  upon  the  disease  occurring 
in  Brazil.  This  was  soon  confirmed  by  Castellani,^^^  1914,  and  many 
others.  Rogers  employs  intravenous  injections  of  a  2  per  cent,  solu- 
tion of  tartar  emetic.  The  first  dose  is  2  c.  c.  (for  adults)  which  is  in- 
creased up  to  10  c.  c.  every  two  days,  until  symptoms  appear,  such  as 
nausea  and  eiDigastric  pains. 

The  prevention  of  leishmianiasis  consists  first  in  early  diagnosis  and 
specific  treatment.  Such  measures  generally  applied  would  greatly  de- 
crease the  amount  of  the  infection  and  its  liability  to  spread. ,  A  war- 
fare against  bedbugs,  mosquitoes  and  other  biting  insects  must  be 
carried  on,  for  even  if  some  insect  is  not  the  intermediate  host,  the 
wound  produced  from  a  bite  may  be  the  point  of  entrance  of  the  para- 
site which  is  very  prevalent  in  the  endemic  centers.  All  wounds,  how- 
ever trivial,  should  be  promptly  treated  and  adequately  protected. 

It  must  be  remembered  that  dogs  around  the  Mediterranean  basin 
have  the  infection  and  it  is  possible  that  children  may  contract  the 
disease  from  them. 

The  parasites  abound  in  the  ulcers  of  the  skin  and  intestinal  mucosa, 

^^8ci.  Mem.  Govt.,  India,  Nos.  27,  31,  1907-08. 

^^Arch.  bras,  de  Med.,  t.  II,  No.  3,  p.  426;  also,  Boletin  de  Soc.  Iras,  de 
Dermat.,  1913,  t.  II,  Xo.  1. 

^''Report  to  the  Advis.  Com.  for  the  Trop.  Res.  Fund,  1914,  et  Revista  di 
Pediatria,  1915,  fasc.  4. 


ROACHES  383 

from  wliitli  they  may  be  discharged  in  great  numbers.  Infection  through 
various  forms  of  tontact,  direct  and  indirect,  must  be  considered  and 
guarded  against.  Instances  are  recorded  in  which  Oriental  sore  has 
been  transmitted  indirectly  through  the  use  of  a  towel  and  other 
objects. 

ROACHES 

Roaches  are  among  the  commonest  and  most  offensive  of  the  insects 
wliich  frequent  human  habitations.  They  are  under  suspicion  of  convey- 
ing several  infections.  There  are  no  less  than  a  thousand  species  of  the 
family  BlaiUdae.  Four  of  these  have  become  domesticated  and  cosmo- 
politan. They  are  Periplaneta  americana,  Peripldneta  australasiae, 
JUalla  urifiilalis  and  Blatta  germanica. 

The  main  difference  between  Periplaneta  americana  and  Periplaneta 
australai<lae  is  that  the  Australian  roach  differs  strikingly  in  the  brighter 
and  more  definitely  limited  yellow  band  on  the  prothorax,  and  in  the 
yellow  dash  on  the  side  of  the  wings. 

Blatta  orientalis  or  black  beetle,  is  the  common  European  and  Eng- 
lish species.  The  female  is  nearly  wingless  in  the  adult  state.  Blatta 
germanica,  tlie  German  roach,  has  become  world-wide  in  distribution :  in 
this  country  it  is  styled  the  Croton  bug.  It  is  now  the  commonest 
and  best  known  of  the  domestic  roaches.  It  is  light  brown  in  color,  and 
characteristically  marked  on  the  thorax  with  two  dark  brown  stripes. 
It  is  the  smallest  of  the  domestic  roaches,  and  multiplies  more  rapidly 
than  any  of  them.  It  is  also  more  active  and  wary  than  the  larger 
species,  and  more  difficult  to  eradicate. 

Structure  and  Habits. — Roaches  are  smooth,  slippery  insects,  in 
shape  broad  and  flattened.  The  head  is  bent  downward  so  that  the  mouth 
parts  are  directed  backward,  and  the  eyes  directly  downward,  conforming 
to  their  groveling  habits.  The  antennae  are  very  long  and  slender,  often 
having  upward  of  100  joints.  The  males  usually  have  two  pair  of  wings. 
In  some  species,  as  the  Croton  bug,  the  females  are  nearly  wingless. 
The  legs  are  long  and  powerful,  and  armed  with  numerous  strong  bristles 
or  spines.  The  mouth  parts  are  well  developed  and  have  strong  biting 
jaws  like  those  of  a  grasshopper,  enabling  these  insects  to  eat  all  sorts 
of  substances. 

House  roaches  are  particularly  abundant  in  pantries,  kitchens, 
bakeries,  and  other  warm  places.  They  are  nocturnal  in  habits.  Their 
numbers  are  often  not  realized  unless  they  are  surprised  in  their  mid- 
night feasts.  Domestic  roaches  are  practically  omnivorous,  feeding  on 
almost  any  dead  animal  matter,  cereal  products  and  food  materials  of 
all  sorts.  They  are  believed  to  be  cannibalistic.  They  eat  or  gnaw 
woolens,  leather,  and  frequently  damage  the  cloth  and  leather  bindings 
of  books.    They  soil  everything  with  which  they  come  in  contact,  leaving 


384  IISrSECT-BORNE  DISEASES 

a  nauseous,  roachy  odor.  Food  so  tainted  is  beyond  redemption.  This 
odor  comes  partly  from  the  excrement,  but  chiefly  from  a  dark-colored 
fluid  exuded  from  the  mouth  of  the  insect,  and  also  in  part  from  the 
scent  glands.  Occasionally  they  migrate,  which  accounts  for  the  way  in 
which  new  houses  frequently  become  suddenly  overrun  with  these 
vermin. 

The  eggs  are  brought  together  within  the  abdomen  of  the  mother 
into  an  egg  capsule,  which  is  a  hard,  horny  pod.  It  is  retained  in  this 
position  sometimes  for  weeks,  or  until  the  young  larvae  are  ready  to 
emerge.  The  young  are  very  much  like  the  adults,  except  in  point  of 
size,  and  in  lacking  wings.  They  pass  through  a  number  of  molts,  some- 
times as  many  as' seven.  The  development  of  the  roach  is  slow,  and 
probably  under  the  most  favorable  conditions  rarely  more  than  one 
generation  per  year  is  produced.  The  abundance  of  roaches  is  therefore 
apparently  not  accounted  for  so  much  by  their  rapidity  of  multiplication 
as  by  their  unusual  ability  to  preserve  themselves  from  ordinary  means 
of  destruction,  and  by  the  scarcity  of  natural  enemies. 

Natural  enemies  of  the  roach  are  mice, .  rats,  guinea-fowl,  tree-frog, 
ichneumon  fly,  and  other  insectivorous  animals. 

The  warfare  against  roaches  consists  of :  (1)  cleanliness;  (2)  elimina- 
tion of  breeding  and  hiding  places;  (3)  fumigation;  (4)  poisons;  (5) 
traps;  (G)  natural  enemies.  Scrupulous  cleanliness  and  the  keeping  of 
food  in  jars  or  places  inaccessible  to  the  roach  is  of  prime  importance. 
All  unnecessary  corners,  cracks  and  imperfections  in  the  structure  of  the 
building  that  favor  breeding  and  hiding  places  must  be  eliminated. 
Eoaches  may  be  killed  with  hydrocyanic  acid  gas,  and  also  with  sulphur 
dioxid — several  fumigations  are  sometimes  necessary.  The  best  poison 
for  roaches  is  sodium  fluorid.  This  substance  very  finely  ground  and 
mixed  with  meal  of  some  sort  forms  the  basis  of  most  roach  powders 
found  upon  the  market.  The  powder  should  be  liberally  dusted  in  all 
corners,  drawers,  closets  and  runways.  Sodium  fluorid  is  only  toxic 
to  insects  when  taken  internally;  it  is  ineffective  against  bedbugs  prob- 
ably because  that  insect  cannot  be  induced  to  eat  it.  Other  poisons  some- 
times used  are:  pyrethrum  powder,  flowers  of  sulphur,  phosphorus  paste, 
containing  1  or  3  per  cent,  of  phosphorus  in  sweetened  flour.  Plaster-of- 
Paris,  1  part,  flour  3  or  4  parts,  may  be  set  near  a  convenient  flat  plate 
containing  pure  water.  The  insects  eat  the  mixture,  become  thirsty 
and  drink,  when  the  plaster-of-Paris  sets  and  clogs  the  intestines.  Many 
roaches  may  be  trapped  in  a  deep,  smooth  basin  or  Jar.  Sticks  leading 
up  to  the  rim  of  the  trap  make  runways  for  the  insects,  which  slip  into 
the  trap  but  cannot  get  out.  The  best  bait  for  these  traps  is  stale  beer. 
The  Croton  bug  is  too  wise  to  be  thus  trapped. 

The  roach  has  been  shown  by  Fibiger  ^^^  to  become  infested  with  a 

136  Fibiger,  J.:   Berliner  hlin.  Wochenschr.,  Feb.  17,  1913,  L,  No.  7,  pp.  289-332. 


ROACHES  385 

round  worm.  When  these  infested  roaclies  are  eaten  by  rats,  a  cancerous- 
like  growth  develops  in  the  stomachs  of  the  rats,  apparently  due  to  the 
irritating  presence  of  these  worms.  Herms  and  Xelsun  '"  and  also  Long- 
fellow 1^"  have  shown  tlie  jH)ssibility  of  the  conveyance  of  typlioid  and 
other  infections  by  means  of  the  roach.  When  we  consider  that  Iiouse 
roaches  feed  upon  all  kinds  of  breadstun's,  milk  and  its  products,  meat, 
clothing,  cooked  and  raw  food;  that  they  migrate  from  one  apartment  to 
another,  following  water  and  draiii  pipes,  from  cellar  and  sick  room  to 
living  rooms  and  bedroojns;  that  tlic-y  infest  kitchens,  store  rooms  and 
toilets,  opportunity  is  evidently  offered  to  drag  infection  mechanically 
from  one  place  to  another.  Roaches  must  therefore  be  regarded  as  a 
sanitary  menace. 

References. — The  literature  upon  insects  and  insect-borne  diseases 
is  very  widely  distributed.  Many  of  the  entomological  facts  contained 
in  this  chapter  have  been  taken  from  "'The  Insect  Book"  by  L.  0.  How- 
ard and  the  many  excellent  publications  of  Howard  and  his  colleagues 
of  the  Bureau  of  Entomolog}^,  Department  of  Agriculture.  The  Gov- 
ernment publications  may  be  had  upon  application  to  the  Superintendent 
of  Documents,  Washington,  D.  C.  Many  of  the  facts  concerning  the 
prevention  and  destruction  of  mosquitoes  have  been  taken  from  articles 
in  the  Public  Health  Beports  of  the  Public  Health  Service.  In  the  chap- 
ter upon  insecticides  free  reference  has  been  made  to  my  own  book  upon 
"Disinfection  and  Disinfectants,"  as  well  as  to  my  other  writings  and 
unpublished  work  in  different  phases  of  this  subject.  Other  references 
are  cited  in  the  text.     See  also : 

Fantham,  H.  B.,  Stephens,  J.  W.  W.,  and  Theobald,  F.  V.,  The  Animal 
Parasites  of  Man,  New  York,  1920.  Castellani,  A.,  and  Chalmers,  A.  J., 
Manual  of  Tropical  Medicine,  London,  1919. 

"'Herms,  W.  B.,  and  Nelson,  Y.:  Am.  Jour.  Puh.  Health,  Sept.,  1913,  III, 
9,  p.  929. 

"« Longfellow,  R.  C:    Am.  Jour.  Pub.  Health,  Jan.,  1913,  III,  1,  p.  58. 


CHAPTEE  V 
MISCELLANEOUS  DISEASES 

INFANTILE  PARALYSIS 

{Acute  Anterior  Poliomyelitis) 

Infantile  paralysis  is  an  acute  generalized  infection,  due  to  a  filter- 
able virus,  occurring  both  in  epidemic  and  sporadic  form.  The  virus 
attacks  the  nervous  system,  with  a  special  tendency  to  localization  in  the 
anterior  horns  of  the  gray  matter  of  the  spinal  cord,  hence  the  name 
anterior  poliomyelitis. 

Infantile  paralysis  is  often  called  the  Heine-Medin  disease,  from 
the  fact  that  Heine  ^  of  Connstadt,  in  1840,  first  established  the  disease 
as  a  clinical  entity,  and  Medin,^  a  Swedish  physician,  in  1890,  was  the 
first  carefully  to  study  an  epidemic  and  to  recognize  various  clinical 
types,  as  the  cerebral,  bulbar,  polyneuritic  and  ataxic  forms  of  the 
disease.  Bergenholtz,  in  1881,  described  an  outbreak  of  eighteen  cases  in 
Sweden  with  sufficient  accuracy  to  establish  the  epidemic  form  of  the 
disease.  The  first  outbreak  described  in  the  United  States  was  re- 
ported by  Caverley,^  in  1896,  in  Vermont.  Wickman,*  of  Sweden,  in 
1905-06,  defined  mild,  non-paralytic  types  not  before  recognized,  made 
the  first  systematic  study  of  the  disease  from  an  epidemiological  point 
of  vicAv,  and  found  evidence  that  it  was  contagious,  though  usually 
slightly  so.  He  directed  especial  attention  to  several  factors  in  its  spread, 
viz. :  routes  of  travel,  public  gatherings  of  children,  abortive  or  ambulant 
cases,  and  healthy  intermediate  carriers.  In  the  spring  of  1909  Land- 
steiner  and  Popper  ^  succeeded  in  transmitting  the  disease  to  two 
monkeys  by  inoculating  them  with  the  spinal  cord  of  a  child  who  had 
died  of  infantile  paralysis.  Later  in  the  year  Flexner  and  Lewis  ®  ob- 
tained the  same  results,  and  further  transmitted  the  infection  from  mon- 
key to  monkey  through  an  indefinite  number  of  passages.  To  Harbitz 
and  Scheel  of  Norway  we  are  indebted  for  formulating  the  pathologic 
anatomy  of  the  affection. 

^  Beobachtungen    iiber    Lahmungszustiinde    der    unteren    Extremitaten    und  . 
deren  Behandlung.     Stuttgart,  1840,  F.  H.  Kohler. 

^'Verhandl.  d.  x.  Internat.  Med.  Cong.  1890,  Berlin,  1891,  II,  6,  Abth.,  37-47. 

'Jour.  A.  M.  A.,  1896,  XXXVI,  1. 

*  Beitrage  zur  Kentniss  der  Heine-Medinischr.,  Krankheit,  Berlin,  1897. 

'  Zeit.  f.  Immun.,  Orig.,  1909,  II,  377. 

^Jour.  A.  M.  A.,  1909,  LIU,  639. 

386 


INFANTILE  PARALYSIS  387 

The  name,  infantile  paralysis,  is  misleading,  for  adults  are  attacked 
and  paralysis  is  not  constant.  The  period  of  incubation  is  not  known, 
although  stated  to  be  5  to  10  days,  commonly  6.  The  case  fatality 
rate  varies  in  dill'erent  epidemics  from  4  to  27  per  cent.  Gastro-intestinal 
symptoms  and  fever  lasting  3  or  4  days  often  precede  the  paralysis, 
although  a  child  may  go  to  bed  well  and  wake  up  in  the  morning  with 
paralysis  and  a  slight  fever. 

Epidemics  of  poliomyelitis  have  prevailed  in  all  quarters  of  the  world. 
The  disease  has  been  most  prevalent  in  the  northern  parts  of  Europe 
and  of  the  United  States.  Epidemics  have  been  more  severe,  and  the 
case  rates  have  been  higher,  in  small  towns  and  rural  districts  than  in 
the  more  densely  populated  cities.  Even  in  the  cities  the  disease  does 
not  especially  strike  the  crowded  districts.  Cold  countries  having  marked 
seasonal  variations  in  temperature  have  been  most  affected,  but  the 
disease  is  most  prevalent  in  the  warm,  dry  months,  from  ]May  to  No- 
vember in  the  northern  hemisphere  and  November  to  May  in  the  south- 
ern hemisphere.  A  severe  outbreak  (3,840  cases  and  380  deaths)  oc- 
curred in  Sweden  in  1911  in  the  late  fall — October  and  December.  Spor- 
adic cases  may  occur  at  any  time  throughout  the  year.  The  great  ma- 
jority (75  per  cent.)  of  cases  occur  in  children  under  five  years  of  age 
and  98  per  cent,  under  15  years. 

From  the  standpoint  of  prevention  it  is  important  to  note  that  social 
and  hygienic  conditions  apparently  have  no  influence  whatever  in  de- 
termining the  infection.  All  classes  are  affected  in  about  equal  pro- 
portion.    Sir  Walter  Scott  gives  a  graphic  account  of  his  own  case.'^ 

Infantile  paralysis  has  the  ear  marks  of  a  new  infection,  although 
instances  of  sudden  paralysis  in  babies  said  to  be  due  to  carelessness 
of  the  nurse,  are  found  in  the  literature  of  antiquity  and  some  of  these 
are  assumed  to  have  been  cases  of  infantile  paralysis.  It  is  quite  certain 
that  the  disease  has  become  more  and  more  common  and  more  wide- 

^  "I  shewed  every  sign  of  health  and  strength  until  I  was  about  eighteen 
months  old.  One  night,  I  have  often  been  told,  I  shewed  great  reluctance  to  be 
caught  and  put  to  bed;  and  after  being  chased  about  the  room,  was  apprehended 
and  consigned  to  my  dormitory  with  some  difficulty.  It  was  the  last  time  I  was 
to  show  such  personal  agility.  In  the  morning,  I  Avas  discovered  to  be  affected 
with  the  fever  which  often  accompanies  the  cutting  of  large  teeth.  It  held  me 
three  days.  On  the  fourth,  when  they  went  to  bathe  me  as  usual,  they  discov- 
ered that  I  had  lost  the  power  of  my  right  leg.  My  grandfather,  an  excellent 
anatomist  as  well  as  physician,  the  late  worthy  Alexander  Wood,  and  many 
others  of  the  most  respectable  of  the  faculty,  were  consulted.  There  appeared 
to  be  no  dislocation  or  sprain;  blisters  and  other  topical  remedies  were  applied 
in  vain.  When  the  efforts  of  regular  physicians  had  been  exhausted,  without 
the  slightest  success,  my  anxious  parents,  during  the  course  of  many  years, 
eagerly  grasped  at  every  prospect  of  cure  which  was  held  out  by  the  promise  of 
empirics,  or  of  ancient  ladies  or  gentlemen  who  conceived  themselves  entitled 
to  recommend  various  remedies,  some  of  which  were  of  a  nature  sufficiently 
singular.  But  the  advice  of  my  grandfather.  Dr.  Rutherford,  that  I  should  be 
sent  to  reside  in  the  country,  to  give  the  chance  of  natural  exertion,  excited  by 
free  air  and  liberty,  was  first  resorted  to."  From  "The  Life  of  Sir  Walter 
Scott,"  by  J.  G.  Lockhart,  p.  13. 


388  MISCELLANEOUS  DISEASES 

spread  of  late  years.    The  increase  cannot  be  wholly  accounted  for  by  the 
fact  that  the  disease  is  now  better  known  and  more  readily  recognized. 

Following  the  first  record  of  the  disease  in  an  epidemic  form  in 
Sweden  in  1881,  some  groups  of  cases  were  reported  in  1882  in  Italy, 
and  in  1886  in  (Norway,  Germany  and  France.  All  these  epidemics 
were  small  in  numbers  attacked.  In  1887,  Medin  described  an  epidemic 
in  Stockholm  of  forty-four  cases,  and  this  is  the  first  important  work 
on  the  subject.  In  1894,  an  epidemic  of  132  cases  occurred  in  Rutland, 
Massachusetts,  which  was  recorded  by  Caverley  and  McPbail.  Small 
epidemics  are  recorded  in  the  "nineties"  in  Italy,  France,  Australia, 
England,  and  America,  and  a  larger  one  occurred  in  Vienna  (forty- 
two  cases),  in  1898,  and  in  Norway  and  Sweden  in  1899.  The  last 
was  described  by  Wickham.  In  the  middle  of  the  next  decade,  1900 
to  1910,  the  record  of  cases,  which  before  had  been  limited  to  two  fig- 
ures, now  reached  to  four  figures,  and  during  the  years  1903-07,  it  may 
be  said  that  the  disease  was  pandemic  in  Norway  and  Sweden.  During 
the  years  1907-10,  large  epidemics'  occurred  in  the  states  of  New  York 
and  Massachusetts.  At  the  same  time  epidemics  of  the  disease  were 
recorded  in  Australia  (Stephens),  in  Vienna  (Zappert),  Westphalia 
(Krause  and  Eeckzek),  in  Paris  (Netter),  in  Austria  (Furnatt,  Pot- 
peschnigg,  Lindner  and  Mallu),  Switzerland  (Hagenback),  and  in  Rus- 
sia (Jogichess). 

Of  the  8,054  cases  reported  in  5  years  (1905-09),  the  United  States 
contributed  5,514  cases  or  about  five-sevenths  of  the  total  number.  The 
number  of  outbreaks  and  the  number  of  cases  have  progressively  in- 
creased, as  shown  in  the  following  table: 

Av.  No.  of  Cases 
Cases         Outbreaks     per  Outbreak 

1880-1884    23  2  11.5 

1885-1889    93  7  13. 

1890-1894    151  4  38. 

1895-1899    345  23  15. 

1900-1904   349  9  39. 

1905-1909    8,054  25  322. 

Since  1910,  the  disease  has  shown  a  rapid  increase.  From  1910  to 
1914  (inclusive),  18,800  cases  were  reported  in  the  United  States;  and 
31,500  cases  in  the  two  years  1915  and  1916.  The  disease  was  pro- 
gressive, the  epidemic  grew  in  extent  and  intensity,  until  it  became 
pandemic,  and  in  1916  swept  the  United  States,  involving  numbers  far 
in  excess  of  anything  hitherto  recorded.  In  1916  there  were  29,000  cases 
and  6,000  deaths;  Massachusetts  reported  1,926  cases,  and  New  York 
City  alone  over  8,928  cases  and  2,407  deaths.^     Since  1916  the  disease 

'  See  the  splendid  epidemiological  study  of  the  epidemic  of  1916,  Puhlic 
Health  Bulletin  No.  91,  July,  1918,  by  Lavinder,  Freeman  and  Frost.     Also  the 


INFANTILE  PARALYSIS  389 

has  subsided,  bui  luis  Id't  tlKiiisiuids  of  criiiplcd  childreii.  The  after-care 
of  infantile  paralysis  has  become  a  public  health  })roblern  of  con.siderable 
nia^aiitude,  which  requires  special  clinics  under  the  care  of  competent 
orthopedists  with  muscle  trainers  and  social  service  workers.  (See  Re- 
ports of  the  Harvard  Infantile  Paralysis  Commission.) 

The  virus  of  the  disease  is  present  in  greatest  virulence  or  concen- 
tration in  the  spinal  cord  of  infected  persons  and  animals.  One  one- 
hundredth  of  a  cubic  centimeter  of  an  emulsion  of  cord,  or  less,  is  suf- 
ficient to  infect  a  monkey.  The  virus  is  also  quite  constantly  present 
in  the  brain  and  other  organs  and  tissues,  as,  for  instance,  the  mucous 
membrane  of  the  nose  and  pharynx,  the  mesenteric  glands,  the  axillary 
and  inguinal  lymph  nodes,  also  in  the  blood,  and  in  the  cerebrospinal 
fluid.  The  virus  has  been  demonstrated  in  the  intestinal  secretions. 
The  suspicion  that  the  alvine  discharges  may,  therefore,  be  virulent  is 
sufficient  indication  that  they  should  be  disinfected  in  all  cases  until 
further  knowledge  of  the  subject  is  at  hand.  The  virus  has  been  grown 
by  Flexner  and  Noguchi  ^  as  minute  globoid  bodies  arranged  in  pairs, 
chains  and  masses  in  artificial  cultures. 

The  experimental  disease  in  monkeys  may  be  produced  by  injecting 
the  virus  directly  into  the  central  nervous  system,  preferably  the  brain. 
Monkeys  may  also  be  infected  by  introducing  the  virus  subcutaneously 
or  into  the  peritoneal  cavity,  and  even  by  intravenous  inoculation.  They 
have  been  infected  by  placing  virulent  material  upon  the  healthy  mucous 
membrane  of  the  nose  and  also  by  inhalation  of  the  infectious  material 
forced  into  the  trachea,  and  finally  by  introducing  the  virus  into  the 
stomach,  along  with  an  opiate,  to  restrain  peristalsis.  Leiner  and  Weis- 
ner  have  infected  monkeys  through  the  uninjured  nasal  mucous  mem- 
brane. I  have  obtained  similar  results.  Monkeys  have  so  far  never 
been  known  to  contract  the  disease  "spontaneously,"  even  though  they 
are  kept  in  intimate  association  with  infected  monkeys.  There  are 
many  paralytic  diseases  of  the  lower  animals,  but,  so  far  as  known, 
infantile  paralysis  as  a  natural  infection  is  peculiar  to  man. 

Resistance  of  the  Virus. — The  virus  of  infantile  paralysis  is  killed 
by  a  temperature  of  45°  to  50°  C,  in  half  an  hour;  also  by  comparatively 
weak  disinfectants,  such  as  a  1-500  solution  of  permanganate  of  potash, 
1  per  cent,  menthol  in  oil,  a  powder  containing  menthol,  0.5  per  cent., 
salol,  5  per  cent.,  boric  acid,  20  per  cent.  (Landsteiner  and  Levaditi), 
and  a  dilution  of  perhydrol  (Merck)  equivalent  to  1  per  cent,  of  peroxid 
of  hydrogen.  The  virus  is  not  destroyed  by  very  low  temperatures  nor 
by  drying  over  caustic  potash,  or  in  vacuo  for  a  considerable  period. 
A  virulent  cord  has  been  kept  for  almost  5  months  in  pure  glycerin 

"Epidemic  of  Poliomyelitis  in  New  York  City  in  1916,"  published  by  the  Depart- 
ment of  Health,  New  York  City. 

Vow.  A.  M.  A.,  Feb.  1,  1913,  LX,  3,  p.  362. 


390  MISCELLANEOUS  DISEASES 

without  losing  its  activit}',  resembling  in  this  respect  rabies,  vaccinia, 
and  other  filterable  viruses,  and  differing  for  the  most  part  from  non- 
spore-bearing  pathogenic  bacteria  which  are  usually  killed  by  pure  gly- 
cerin in  a  short  while.  The  virus  remains  virulent  in  ordinary  water 
for  31  days,^°  and  the  same  length  of  time  in  milk,  first  sterilized  by  heat. 

Immunity.- — One  attack  of  infantile  paralysis  apparently  confers  a 
high  degree  of  immunity.  Eecurrent  cases  and  second  attacks  have 
been  reported.  Monkeys  which  have  recovered  from  the  infection  show 
a  high  degree  of  resistance,  in  that  they  are  not  susceptible  to  infec- 
tion by  again  inoculating  them,  and  their  blood  serum  contains  anti- 
bodies capable  of  rendering  the  virus  harmless.  That  is,  if  the  blood 
serum  of  an  immune  monkey  is  mixed  with  an  emulsion  of  virulent 
spinal  cord  and  the  mixture  allowed  to  stand  for  several  hours,  the  virus 
is  no  longer  capable  of  producing  the  disease  in  susceptible  animals. 
This  property  has  been  used  by  Anderson  and  Frost  to  corroborate  the 
clinical  diagnosis  in  abortive  cases.  The  blood  of  a  person  who  has  not 
had  the  disease  does  not  neutralize -the  virus;  therefore,  if  the  injection 
of  the  virus  previously  treated  with  human  serum  fails  to  produce  the 
infection  in  susceptible  monkeys,  it  may  be  taken  as  evidence  that  the 
seriim  contained  specific  antibodies  and  came  from  an  individual  who  has 
had  the  disease.  Monkeys  often  fail  to  respond  to  injection  with  fresh 
virus.     Negative  results  must  therefore  be  studied  critically. 

Modes  of  Transmission — Contact  theory  (based  upon  the  as- 
sumption that  the  virus  is  discharged  from  the  mouth  and  nose 
and  enters  through  the  same  channel). — There  is  evidence  to  sup- 
port the  theory  that  the  disease  is  directly  transmissible  from  person  to 
person  and  there  is  a  suspicion  that  healthy  carriers  play  an  important 
role  in  spreading  the  infection.  This  view  was  enunciated  by  Wickman 
and  received  support  through  the  experiments  of  Kling,  Pettersson  and 
Wernstedt,  and  also  Flexner.  It  is  known  that  the  mucous  membrane 
of  the  nose  and  throat  contains  the  virus,  and  in  one  case  the  salivary 
glands  v.'ere  shown  to  be  infective.  Osgood  and  Lucas  demonstrated 
that  the  nasal  mucous  membrane  of  two  monkeys  experimentally  inocu- 
lated with  poliomyelitis  remained  infective  for  6  weeks  in  one  case  and 
5%  months  in  another.  This  observation  strengthens  the  suspicion  of 
the  existence  of  chronic  human  carriers.  If  healthy  carriers  continue 
to  spread  the  infection  months  after  the  attack,  it  increases  the  difficulty 
of  suppressing  the  disease,  and  further  renders  doubtful  the  efficiency 
of  strict  isolation  and  prophylactic  measures  directed  only  to  persons 
in  the  acute  stage  of  the  disease.  The  fact  that  the  mucous  membrane 
contains  the  virus  is  not,  however,  sufficient  proof  that  the  virus  is 
liberated  and  discharged  in  sufficient  amount  in  the  secretions  from 
the  mouth  and  nose  to  be  a  menace.  In  a  series  of  18  cases  Eosenau, 
^"Levaditi  and  Pasti,  Annal.  de  I'lnst.  Pasteur,  XXV,  11,  805. 


INFANTILE  PARALYSIS  391 

Sheppard  and  Amoss^^  wove  unable  to  demonstrate  the  virus  in  the 
nasal  and  buccal  secretions  obtained  from  persons  in  various  stages  of 
convalescence.  Strauss  '-  liad  similar  negative  results  in  a  series  of 
10  cases.  Amoss  and  Taylor'"'  demonstrated  that  tiie  normal  naso- 
pharyngeal secretions  are  al)le  to  neutralize  the  virus  of  infantile  paraly- 
sis, and  this  may  aecoimt  for  the  negative  results.  Flexner  and  Amoss  '* 
find  that  the  protective  povi'er  of  the  nasal  mucosa  is  not  in  itself  adequate 
to  prevent  infection  with  the  virus  placed  on  it,  since  slight  injury  to 
such  independent  structures  as  the  meningeal-choroid  plexus  favors  the 
passage  of  the  virus  from  the  nose  to  the  central  nervous  system.  On  the 
other  hand,  Kling,  Pettersson  and  Wernstedt  ^°  report  successful  results: 
by  experiments  upon  monkeys  they  demonstrated  the  infectiousness  of 
buccal  and  intestinal  secretions  of  living  subjects. 

The  latest  views  of  Flexner  and  Amoss  ^^  are  that  the  virus  is  regu- 
larly present  in  the  nasopharynx  in  cases  of  infantile  paralysis  in  the 
first  days  of  illness  and  especially  in  fatal  cases;  that  it  diminishes 
relatively  quickly  as  the  disease  progresses,  except  in  rare  instances; 
and  that  it  is  unusual  for  the  carrier  state  to  develop.  Hence,  the  period 
of  greatest  infectidty  would  be  early  in  the  disease. 

Tlie  Insect-born&  Theory. — Infantile  paralysis  shows  no  tendency 
to  prevail  in  congested  centers  or  to  spread  in  hospitals,  schools,  institu- 
tions, and  other  crowded  places;  its  seasonal  prevalence  corresponds  to 
the  seasonal  prevalence  of  most  insects,  and  does  not  correspond  to  the 
seasonal  prevalence  of  diseases  spread  through  secretions  of  the  mouth 
and  nose,  such  as  diphtheria,  scarlet  fever,  smallpox,  etc.  Many  other 
factors,  brought  to  light  by  the  studies  of  the  State  Board  of  Health  of 
Massachusetts  upon  the  epidemiology  of  the  disease,  under  the  able 
direction  of  Dr.  Mark  Eichardson,  indicate  that  the  disease  is  not  a  con- 
tagious one.  These  studies  ^'^  gradually  focused  attention  upon  some 
insect,  the  stable  fly  (Stomoxys  calcitrant)  in  particular.  Rosenau  and 
Brues  ^^  demonstrated  that  the  virus  may  sometimes  be  transmitted  from 
monkey  to  monkey  through  the  bite  of  the  stable  fly.    These  results  were 

"Rosenau,  M.  J.,  Sheppard,  P.  A.  E.,  Amoss,  H.  L.,  Boston  Med.  and  Swrg. 
Jour.,  May  25,  1911,  CLXIV,  21,  pp.  743-748. 

"Strauss,  I.,  J.  A.  M.  A.,  April  22,  1911,  LVI,  16,  1192. 

^^Journ.  Exp.  Med.,  1917,  XXV,  507. 

"Journ.  Exp.  Med.,  Feb.  1,  1920,  XXXI,  2,  p.   123. 

"  Kling,  C,  Pettersson,  A.,  and  Wernstedt,  W.,  Report  from  the  State  Medi- 
cal Institute  of  Sweden  to  the  XVth  International  Congress  on  Hygiene  and  Dem- 
ography, Washington,  D.  C,  1912.  Also,  Zeitschr.  f.  Immunitdtsforch.  u.-exper. 
Therapie,  Bd.  XII,  .Jena,  1912. 

^"Journ.  Exp.  Med.,  XXIX,  379,  April,  1919. 

"  Richardson,  M.  W.,  Monthly  Bull.,  State  Board  of  Health  of  Mass.,  Sept., 
1912,  7,  9,  pp.  308-315. 

Lovett,  R.  W.,  Report  to  the  Mass.  State  Board  of  Health,  1907.  Report 
to  the  Mass.  State  Board  of  Health,  1908,  1909,  1910,  1911. 

^'Rosenau,  M.  J.,  and  Brues,  C.  T.,  MontJily  Bull..  State  Board  of  Health  of 
Mass.,  Sept.,  1912,  7,  9,  pp.  314-318.  Also  Brues  and  Sheppard,  Jour,  of  Econom, 
Entomology,  Aug.,  1912,  V,  4,  305, 


392  MISCELLANEOUS  DISEASES 

soon  confirmed  by  Anderson  and  Frost.^®  The  insect-borne  theory  seems 
to  fit  the  case  as  the  disease  is  known  in  Massachusetts.  Subsequent 
work  by  Eosenau^  Anderson  and  others  has  given  negative  results.  Even 
though  infantile  paralysis  may  occasionally  be  transmitted  experiment- 
ally by  insects  biting  monkeys  in  a  cage,  it  seems  improbable  that  this 
is  the  way  the  infection  is  spread  from  man  to  man  in  nature. 

Other  Theories. — It  has  been  suggested  that  the  virus  may  be 
air-borne  in  the  sense  that  it  is  carried  in  the  dust.  Neustaedter  and 
Thro  ^^  claim  to  have  infected  monkeys  from  dust  collected  from  sick 
rooms.  Eichardson  believes  the  infection  comes  from  rats.  Infected 
food,  or  transmission  through  wounds  and  other  means,  have  not  been 
ruled  out  of  consideration. 

A  favorite  explanation  of  the  epidemiology  of  the  disease  is  to  regard 
it  as  a  very  communicable  disease  like  measles,  and  much  more  wide- 
spread in  the  community  than  indicated  by  the  paralytic  cases.  Most 
cases  are  mild,  escape  notice  and  leave  protection.  In  accordance  with 
this  theory  only  the  occasional  severe  case  with  paralysis  comes  to  clinical 
diagnosis.  In  accordance  with  this  view,  we  are  dealing  with  a  very 
common  infection,  always  present  in  the  community,  but  which  in  recent 
years  has  gained  an  increased  virulence. 

Prevention. — No  definite  or  effective  system  of  prevention  can  be 
formulated  until  we  are  sure  of  the  mode  of  transmission.  Meanwhile 
health  authorities  are  entirely  justified  in  requiring  cases  to  be  reported, 
isolated,  and  all  known  lines  of  preventive  measures  applied,  such  as 
disinfection,  screening,  and  guarding  against  insects,  allaying  unneces- 
sary dust,  etc.  The  infection  must  be  fought  as  one  conveyed  from  man 
to  man  directly.  Until  the  modes  of  transmission  of  the  disease  are 
established,  however,  we  can  have  no  confidence  in  our  prophylactic 
measures,  which  most  resemble  the  old  "shotgun"  prescription. 

The  following  measures  are  recommended:  The  patient  should  be 
isolated  as  completely  as  possible  in  a  clean,  bare  room,  well  screened 
to  keep  out  insects.  This  is  a  good  practice  despite  the  fact  that  the 
disease  shows  no  tendency  to  spread  in  children's  asylums,  hospitals, 
and  other  institutions,  or  even  in  the  home.  The  same  statement,  how- 
ever, was  made  of  typhoid  fever  not  many  years  ago.  Visiting  should 
be  interdicted  and  only  the  necessary  attendant  should  be  allowed  to 
come  in  contact  with  the  patient.  All  discharges,  including  sputum, 
nasal  secretions,  urine,  and  feces,  should  be  thoroughly  disinfected,  and 
special  care  should  be  taken  that  cups,  spoons,  remnants  of  food,  etc., 
which  may  have  become  contaminated  by  the  patient  are  burned,  scalded, 
or  otherwise  purified. 

"Anderson,  J.  F.,  and  Frost,  W.  H.,  Puh.  Health  Reports,  Oct.  25,  1912, 
XXVII,  43,  pp.  1733-1736. 

*•  Neustaedter,  M.,  and  Thro.,  W.  C,  2V.  Y.  Med.  Jowr.,  Sept.  23,  1911, 
XCIV,  13. 


INFAi^TILE  PARALYSIS  393 

Towels,  bed  linen,  and  other  fabrics  should  be  boiled  or  dipped  into 
a  germicidal  solution  strong  enough  to  destroy  the  typhoid  bacillus.  The 
nurse  and  physician  should  observe  the  same  precautions  regarding 
their  hands  and  clothing  as  are  recommended  in  attending  a  case  of 
scarlet  fever. 

The  j)eriod  during  which  the  isolation  should  be  maintained  cannot 
even  be  guessed  at.  Children  are  usually  not  permitted  to  return  to 
school  for  at  least  three  weeks,  but,  if  chronic  carriers  play  the  important 
role  suspected,  this  time  would  be  far  too  short  in  many  instances. 

Since  the  virus  can  be  killed  experimentally  by  a  1  per  cent,  solution 
of  peroxid  of  hydrogen,  antiseptic  gargles,  sprays,  and  nose  washes  of 
this  solution  have  been  used  by  the  patients,  the  nurse,  and  physician, 
and  other  members  of  the  family.  Germicidal  chemicals  applied  to  the 
nasal  mucosa  on  which  the  virus  has  been  deposited  have  no  protective 
action  and  are  of  doubtful  value ;  in  fact,  such  substances  may  affect  un- 
favorably the  protective  properties  of  the  nasal  mucosa.  They  may  even 
be  objectionable  by  injuring  the  delicate  mucous  membrane  and  thus 
favoring  infection. 

Normal  mucous  membranes  are  protective  against  this  as  against 
other  infections  of  the  upper  respiratory  tract.  According  to  Flexuer 
and  Amoss,  the  normal  nasal  mucosa  is  an  invaluable  defense  against 
infection  with  the  virus  of  poliomyelitis,  and  the  number  of  healthy 
and  chronic  carriers  of  the  virus  is  probably  determined  and  kept  down 
through  the  protective  activities  of  this  membrane. 

In  the  presence  of  an  epidemic,  street  and  house  dust  should  be 
kept  down  by  sprinkling,  oiling,  and  the  other  means  employed  for  this 
purpose.  Dust  should  be  allayed  whether  there  is  an  epidemic  of 
infantile  paralysis  or  not.  During  epidemics  children  should  be  kept 
away  from  public  gatherings,  prohibited  from  using  public  drinking 
cups,  and  special  attention  given  to  the  diet  to  prevent  gastro-intestinal 
disorders,  for  many  a  case  of  infantile  paralysis  starts  with  a  digestive 
upset. 

The  prevention  of  deformities  in  paralyzed  children  is  important. 
Massage,  exercise  and  all  active  measures  are  contraindicated  during  the 
acute  stage  and  as  long  as  there  is  tenderness.  Special  attention  must 
be  given  to  maintain  a  normal  position  of  paralyzed  limbs  so  as  to  pre- 
vent deformities  which  develop  quickly.  As  soon  as  acute  symptoms 
have  subsided,  muscle  training  should  be  instituted. 


394  MISCELLANEOUS  DISEASES 

EPIDEMIC  ENCEPHALITIS 

Epidemic  encephalitis,  also  called  encephalitis  lethargica,  infectious 
ophthahnoplegia,  acute  encephalitis,  and  nona,  is  an  acute  infection  due 
to  a  specific  virus  which  is  assumed  to  enter  the  system  through  the 
nasopharynx,  and  like  infantile  paralysis  has  a  special  affinity  for  the 
central  nervous  system,  although  for  different  areas  and  elements.  The 
disease  is  characterized  by  progressive  lethargy  or  stupor,  lesions  in 
or  about  the  nuclei  of  the  third  pair  of  cardinal  nerves,  and  fever.  Oph- 
thalmoplegia occurs  in  75  per  cent,  of  the  cases. 

The  only  epidemic  appearance  of  any  similar  disease  in  the  past 
has  been  in  connection  with  epidemics  of  influenza.  Following  the 
pandemic  of  1889-90,  the  mysterious  nona  appeared  in  northern  Italy, 
and  then  in  Hungary,  and  spread  to  Germany,  France  and  Italy.  Cam- 
erarius  described  a  grip  epidemic  in  Tiibingen  in  1718  and  mentioned  a 
sleeping  sickness  (Schlafkrankheit).  in  connection  with  it.  In  1768, 
Lepecq  de  la  Cloture  described  a  "coma  somnolentum"  after  the  grip, 
and  Ozanann  mentioned  epidemics  of  "catarrhal  fever"  with  "soporosite" 
as  having  occurred  in  Germany  in  174-5,  in  Lyons  in  1800,  and  in  Milan 
in  1802.  The  disease  did  not  follow  the  influenza  epidemic  which 
swept 'this  country  in  1889-90,  but  was  observed  after  the  1918-19  out- 
break. Von  Economo  described  cases  occurring  in  Vienna  during  the 
winter  of  1916-17,  and  since  then,  cases  have  occurred  in  England,  the 
United  States,  and  France. 

Flexner  ^^  points  out  that  lethargic  encephalitis  is  a  communicable 
disease,  imperfectly  understood.  Amoss  ^-  states  that  lethargic  encepha- 
litis is  an  epidemic  disease,  the  main  manifestations  of  which  relate 
to  injury  inflicted  upon  the  central  nervous  system,  in  particular  -  the 
basal  ganglia  of  the  brain.  This  distinguishes  it  froni  poliomyelitis, 
which  affects  in  particular  the  gray  matter  of  the  spinal  cord  and  me- 
dulla oblongata.  Furthermore,  infantile  paralysis  prevails  especially 
in  warm  weather,  whereas  lethargic  encephalitis  is  reported  mainly 
in  the  winter  season,  although  recently  cases  have  arisen  in  the  midsum- 
mer months.  Infantile  paralysis  is  readily  transmitted  to  monkeys, 
whereas  this  is  doubtful  with  lethargic  encephalitis.  The  two  diseases 
are  further  distinguished  by  the  fact  that  the  blood  serum  of  convales- 
cent cases  of  infantile  paralysis  neutralizes  the  virus  of  that  disease, 
while  the  blood  serum  of  convalescent  cases  of  epidemic  encephalitis  lacks 
this  power.  Loewe  and  Strauss  claim  to  have  reproduced  the  disease  in 
rabbits  and  monkeys  by  the  inoculation  of  brain  material  and  naso- 
pharyngeal washings;  also  by  means  of  cultures.^"* 

^"^Jour.  Inf.  Dis.,  Sept.,  1920;  confirmed  in  part  bv  Levaditi  and  Havier. 
^Jour.  A.  M.  A.,  Mar.  27,  1920,  Vol.  LXXIV,  p.  865. 
"^Jour.  Exp.  Med.,  Feb.  1,  1921,  XXXTII,  2,  p.  187. 


CHICKENPOX  395 

CHICKENPOX 

(Varicella) 

Chickenpox  (varicella)  is  usually  regarded  as  one  of  the  minor  com- 
municable diseases  in  that  the  mortality  is  low,  complications  and  se- 
quelae not  frequent.  Chickenpox  is  not  always  a  harmless  disease;  when 
it  runs  through  an  institution  with  many  small  children  it  occasionally 
develops  malignancy.  It  may  leave  disfiguring  scars ;  sepsis  or  erysipelas 
sometimes  originate  in  the  pustules;  complications,  such  as  pneumonia, 
nephritis,  and  gangrene  of  the  skin  also  occur. 

Chickenpox  is  very  readily  communicable  and  spreads  through  fam- 
ilies or  ihstitutions,  and  occurs  in  more  or  less  widespread  epidemics. 
The  cause  of  the  disease  and  its  modes  of  transmission  are  not  known. 
The  virus  is  contained  in  the  content  of  the  vesicle.  The  vesicles  appear 
early  on  the  mucous  membranes  and  rupture  as  soon  as  they  appear, 
rendering  the  disease  communicable  early,  even  before  the  exanthem 
is  in  evidence.  The  mode  of  transmission  is  directly  from  person  to 
person;  indirectly  through  articles  freshly  soiled  by  discharges  from  an 
infected  person. 

The  disease  is  peculiar  to  man;  animal  inoculations  have  so  far 
proved  negative.  The  period  of  incubation  is  probably  from  14  to  16 
days;  the  maximum  for  public  health  purposes  is  31  days.  One  attack 
produces  a  definite  immunity.    No  age  is  exempt. 

Health  officers  should  require  cases  of  chickenpox  to  be  reported,  if 
for  no  other  reason  than  that  it  is  often  mistaken  for  smallpox.  The 
differential  diagnosis  between  chickenpox  and  smallpox  is  often  an  im- 
portant and  difficult  public  health  matter.  The  distinction  may  be  made 
by  introducing  some  of  the  contents  of  the  vesicle  into  the  skin  of  a 
well-vaccinated  person.  If  smallpox,  an  "immediate"  reaction  results; 
if  chickenpox,  no  reaction  results.  Monkeys  are  not  susceptible  to 
chickenpox,  but  may  be  given  smallpox. 

The  differential  diagnosis  may  be  made  in  doubtful  cases  by  a  his- 
tological examination  of  the  pock,  or  by  inoculating  the  contents  of  the 
vesicle  upon  the  cornea  of  rabbits.  Vaccine  bodies  are  found  in  sections 
of  the  skin  lesion  in  smallpox,  not  in  chickenpox;  the  vesicle  of  the 
former  is  multilocular,  the  latter  unilocular.  The  vesicle  upon  the 
cornea  of  rabbits  produced  by  smallpox  is  distinct  and  contains  the  vac- 
cine bodies;  the  lesion  resulting  from  chickenpox  is  trifling  and  does 
not  contain  the  vaccine  bodies. 

Force  and  Beckwith  "  state  that  rabbits  previously  vaccinated  with 
vaccine  virus  will  give  a  marked  intradermal  reaction  with  smallpox 

''Jour.  A.  M.  A.,  Vol.  LXV,  No.  7,  August  14,  1915,  p.  588,  Force  and  Beck- 
with. 


396  MISCELLANEOUS  DISEASES 

vesicle  contents  in  from  twenty-four  to  forty-eight  hours,  but  will  not 
give  such  a  reaction  with  varicella  vesicle  contents.  I  have  not  been 
able  to  obtain  cleai-cut  results  with  this  test. 

The  prevention  of  chickenpox  depends  upon  isolation  and  disinfec- 
tion at  the  bedside.  Children  with  chickenpox  should  not  he  permitted 
to  go  to  school. 

Kling  ^*  favors  vaccination  with  chickenpox  virus,  in  the  face  of  an 
epidemic  in  an  institution.  The  response  to  such  vaccination  is  slight 
and  local.  The  virus  is  taken  from  a  fresh,  clear  vesicle  and  introduced 
into  the  skin.  Eight  days  later  red  papules  appear  at  the  site  of  "vac- 
cination," which  next  day  develop  into  typical  vesicles  of  chickenpox, 
with  a  slight  reddened  areola.  There  are  no  general  symptoms.  Previous 
vaccination  with  smallpox  does  not  prevent  a  positive  reaction  to  vac- 
cination with  chickenpox,  thus  emphasizing  the  essential  difference  be- 
tween the  two  diseases.  An  epidemic  of  chickenpox  at  the  Stockholm 
Children's  Hospital  in  August,  1914,  was  cut  short  by  vaccinating  all 
the  well  children  with  the  virus  from  a  chicken  pock.  Steinert  ^^  also 
obtained  successful  results.    Michael's  ^®  results  are  less  convincing. 

Hess  and  linger  ^'^  obtained  an  immunity  to  varicella  by  means  of  an 
intravenous  injection  of  the  contents  of  the  vesicles.  In  38  instances 
it  failed  to  protect  in  only  one  case. 


GLANDERS 

Glanders  or  farcy  is  a  widespread  communicable  disease  of  horses, 
mules,  asses,  and  other  animals,  and  is  readily  communicated  to  man. 
Cats  may  become  infected  by  eating  the  flesh  of  glandered  horses.  Goats 
also  have  the  disease.  Cattle  are  immune.  Guinea-pigs  and  field  mice 
are  very  susceptible  by  experimental  methods ;  white  mice  have  a  natural 
immunity.  In  both  man  and  horses  it  is  remarkable  for  its  fatality.  The 
disease  is  characterized  by  the  formation  of  inflammatory  nodules  either 
in  the  mucous  membrane  of  the  nose  (glanders)  or  in  the  skin  (farcy). 
The  nodules  break  down,  leaving  crater-like  ulcers.  On  the  skin  the  farcy 
buttons  break  down  and  discharge  an  oily  material.  The  mortality  is 
about  50  per  cent.    Glanders  occurs  both  as  an  acute  and  chronic  disease. 

Glanders  is  caused  by  the  Bacillus  mallei,  which  corresponds  to 
the  spore-free  bacteria  so  far  as  its  resistance  is  concerned.  In  gen- 
eral the  bacillus  of  glanders  is  killed  by  the  same  agents  used  against 
the  tubercle  bacillus,  which  it  resembles  in  some  particulars. 

The  infection  may  be  introduced  into  the  system  either  through  the 

''^Berl.  klin.  Woehenschr.,  Nov.  10,  1913,  L,  45,  p.  2083. 
^  Zeitschr.  f.  Kinderheilkunde,  Julv  28.  1920,  p.  94. 
''Arch,  of  Pediatrics,  Sept.,  XXXIV,  No.  9,  p.  702. 
'^  Am.  Journ.  Diseases  of  Children,  July,  1918,  XVI,  p.  34. 


GLANDEES  397 

skin  or  mucous  membrane,  and  is  usually  communicated  directly  from 
the  horse  to  man  by  contact  with  the  infected  discharges.  The  disease 
is  sometimes  communicated  from  man  to  man.  Washerwomen  have  be- 
come infected  from  the  clothes  of  a  patient. 

The  bacillus  of  glanders  does  not  have  a  spore.  It  is  comparatively 
frail  and  readily  destroyed  by  the  usual  physical  and  chemical  germi- 
cidal agencies  used  against  spore-free  bacteria.  The  bacillus,  however, 
is  frequently  protected  by  albuminous  matter  or  buried  in  the  dirt  of 
stables,  water  troughs,  harnesses,  and  other  objects.  While  the  naked 
germs  of  glanders  are  readily  destroyed,  they  are  frequently  hard  to  get 
at;  cleanliness  is,  therefore,  imperative. 

The  prevention  of  glanders  in  man  depends  primarily  upon  the  sup- 
pression of  the  disease  in  horses.  The  only  difficulty  in  controlling 
the  disease  in  horses  lies  in  the  early  diagnosis  and  recognition  of  mild 
or  missed  cases,  which  are  very  common.  Horses  affected  with  occult 
or  latent  glanders  are  important  factors  in  the  propagation  of  the  in- 
fection, especially  in  the  crowded  parts  of  cities.  The  clinical  diagnosis 
in  the  frank  cases  usually  is  made  without  difficulty  from  the  character- 
istic symptoms  and  the  lesions,  but  laboratory  aid  is  necessary  to  discover 
the  mild  and  atypical  cases. 

Dia^osis. — The  diagnosis  of  glanders  may  be  made  by:  (1)  the 
mallein  test,  both  subcutaneous  and  ophthalmic;  (2)  the  agglutination 
test;  (3)  the  Strauss  reaction;  (4)  isolation  oiB.  mallei  in  pure  culture; 
and  (5)  complement  fixation.  All  these  tests  serve  a  definite  purpose. 
However,  the  mallein  test,  the  agglutination  test,  and  the  Strauss  re- 
action have  certain  limitations.  The  isolation  of  the  glanders  bacillus 
in  pure  culture  is  definite  and  final,  but  time-consuming.  There  is  no 
absolute  relation  between  complement  fixation,  agglutination  and  mal- 
lein tests  in  horses.  An  apparently  healthy  horse  should  not  be  con- 
demned because  one  of  these  tests  is  positive  but  the  animal  should  be 
studied  further. 

The  Mallein  Test. — Mallein  is  a  product  of  the  glanders  bacillus 
corresponding  to  tuberculin.  The  injection  of  mallein  into  normal  ani- 
mals produces  no  reaction,  whereas  the  injection  into  glanderous  ani- 
mals causes  a  rise  in  temperature  and  a  local  reaction  about  the  lesions. 
With  the  mallein  test  a  large  proportion  of  latent  and  occult  cases  of 
glanders  can  be  diagnosed,  but  the  test  must  be  made  and  interpreted 
by  an  experienced  veterinarian,  else  the  results  may  be  unreliable.  "  The 
mallein  test  fails  to  give  a  typical  reaction  in  a  considerable  number  of 
glanderous  animals ;  on  the  other  hand,  a  reaction  may  follow  the  injec- 
tion of  mallein  in  the  absence  of  active  glanders.  Thus  mallein  is  not 
an  entirely  reliable  diagnostic  agent  and  has  never  been  considered  as 
specific  in  the  detection  of  this  disease  as  tuberculin  for  the  diagnosis  of 
tuberculosis. 


3'98  MISCELLANEOUS  DISEASES 

The  ophthalmic  lest  for  glanders  is  reliable,  and  has  a  great  advan- 
tage over  other  tests  on  account  of  its  very  simple  application.  It  is  only 
necessary  to  drop  into,  one  of  the  eyes  of  the  animal  three  drops  of  con- 
centrated mallein,  or  to  dip  a  camel's-hair  brush  into  mallein  and  intro- 
duce this  into  the  conjunctival  sac.  The  reaction  usually  commences  in 
five  or  six  hours  after  the  introduction  of  the  mallein  and  lasts  from 
twenty-four  to  thirty-six  hours.  A  positive  reaction  is  manifested  by 
swelling  of  the  eyelids  and  a  purulent  secretion  from  the  tested  eye. 
Irritation  of  the  conjunctivae  due  to  cold  weather,  dust  and  other  ir- 
ritating influ^ences  must  not  be  confused  with  a  positive  reaction. 

The  Agglutination  Test: — The  agglutination  test  is  of  value  in 
all  cases  of  recent  infection,  the  blood  serum  possessing  a  very  high 
agglutinating  power — 1-1,000  and  higher.  In  chronic  glanders  the  ag- 
glutinating power  of  the  blood  may  be  very  low — 1-400  or  less;  in  some 
cases  even  lower  than  that  of  normal  blood  serum — which  may.be  1-800 
and  even  higher.  It  is,  therefore,  plain  that  agglutination  tests  alone  do 
not  constitute  an  entirely  satisfactory  diagnostic  method  for  glanders. 
It  may  be  used  as  an  adjunct  to  other  tests. 

The  Strauss  Reaction. — The  Strauss  ^^  reaction  for  the  diagnosis 
of  glanders  consists  in  inoculating  material  containing  virulent  B. 
mallei  into  the  peritoneal  cavity  of  male  guinea-pigs,  which  causes  an 
enlargement  of  the  testicles,  involving  the  scrotum;  the  testes  become 
glued  to  their  sheaths.  A  positive  reaction  associated  with  organisms 
resembling  those  of  glanders,  and'  typical  cultures  obtained  from  the 
lesions,  are  unfailing  evidence  of  the  presence  of  ■  the  specific  virus. 
Failure  to  obtain  the  reaction  is  not  proof  that  a  suspected  specimen 
may  not  have  come  from  a  horse  or  animal  with  glanders.  Arms  "^  recom- 
mends that  it  is  better  to  use  more  than  one  guinea-pig  in  testing 
suspected  material,  and  that,  before  inoculating,  it  is  well  to  make  a 
microscopic  examination  as  a  guide  to  the  dosage.  A  culture  made  from 
the  swab  often  aids  in  the  early  diagnosis.  Guinea-pigs  should  be  kept 
under  observation  for  a  month,  and  if  a  lesion  of  any  kind  is  present 
an  autopsy  should  be  made  and  cultures  taken. 

Tlte  Isolation  of  B.  Mallei  in  Pure  Culture. — The  bacillus 
of  glanders  may  be  isolated  by  introducing  some  of  the  suspected  ma- 
terial subcutaneously  and  also  intraperitoneally  into  male  guinea-pigs. 
In  this  way  pure  cultures  may  be  obtained  from  the  pus  or  necrotic 
foci  in  the  spleen,  which  follow  subcutaneous  inoculation;  or  from  the 
characteristic  enlargement  of  the  testicle  which  is  observed  in  animals 
inoculated  intraperitoneally.  The  organism  isolated  must  be  studied 
for  cultural,  morphological,  and  biological  characters.  The  isolation  of 
the  bacillus  in  pure  culture  gives  positive  information  of  unquestioned 

^  Compt.  Rend.  Acad.  d.  Sc,  1889,  CVIII,  p.  530. 
^Jour.  A.  M,  A.,  LV,  7,  Aug.  13,  1910,  p.  591. 


GLANDEKS  399 

character  in  any  critical  case.  The  method  is  not  generally  applicable 
to  the  diagnosis  of  glanders  because  it  requires  too  much  time  and 
may  occasionally  fail  to  discover  the  bacillus.  One  of  the  chief  difficul- 
ties is  that  the  material  is  usually  grossly  contaminated  with  other 
pathogens. 

Complement  Flralion. — In  1909  Schiitz  and  Schubert '•'  published 
the  results  of  their  important  work  on  the  application  of  the  method 
of  complement  fixation  for  the  diagnosis  of  glanders.  The  splendid 
results  obtained  constitute,  without  doubt,  the  most  reliable  method 
for  the  diagnosis  of  glanders  which  we  have  at  our  command  at  the 
present  time.  The  complement  fixation  test  is,  in  fact,  one  of  the  most 
specific  of  the  biological  tests  in  immunity.  It  is  readily  applicable  to 
the  case  of  glanders.  It  has,  however,  less  value  in  testing  the  blood 
of  mules  than  horses  because  of  the  larger  percentage  of  false  positives 
in  the  former.     The  essential  elements  used  in  the  test  are  as  follows: 

The  hemoTyiic  mixture  consists  of  the  washed  red  blood  corpuscles 
of  a  sheep  and  the  blood  serum  of  a  rabbit  which  has  been  injected 
with  the  washed  red  blood  corpuscles  of  a  sheep.  For  preparation  see 
page  583. 

Complement. — The  complement  is  contained  in  the  fresh  blood  serum 
of  a  healthy  guinea-pig.     For  preparation  see  page  581. 

Antigen. — This  is  an  extract  obtained  by  shaking  glanders  bacilli 
in  salt  solution.  The  bacillus  is  grown  in  pure  culture  on  2  per 
cent,  acid,  6  per  cent,  glycerin  agar.  -A  luxuriant  growth  upon  the 
surface  of  the  medium  is  usually  obtained  in  48  hours.  This  is  sus- 
pended in  0.5  per  cent,  carbolized  normal  salt  solution,  heated  to  60°  C. 
for  four  hours  in  order  to  kill  the  bacilli.  After  heating,  the  dead 
bacilli  are  shaken  in  the  salt  solution  in  a  special  apparatus  for  eight 
to  twelve  hours.  The  bacilli  are  separated  in  the  centrifuge  and  the 
clear  supernatant  liquid  is  drawn  oif  and  preserved  with  0.5  per  cent, 
phenol.  The  strength  and  specific  quality  of  each  extract  must  be  de- 
termined by  suitable  methods  of  titration,  by  control  tests. 

Teclinic. — The  test  is  carried  out  by  adding  together,  in  proper 
proportions,  the  following:  (1)  The  blood  serum  of  the  horse  to  be 
tested;  (2)  the  antigen  (extract  of  glanders  bacilli);  (3)  complement 
(fresh  guinea-pig  serum)  ;  and  (4)  the  hemolytic  system.  If  the  blood 
serum  of  the  horse  to  be  tested  contains  the  specific  amboceptors,  these 
will  unite  with  the  bacteria,  fix  the  complement,  and  thus  prevent  hemol- 
ysis. If  the  blood  serum  of  the  horse  to  be  tested  does  not  contain 
these  specific  amboceptors,  this  fixation  of  the  complement  cannot 
take  place  and  hemolysis  results.     Therefore,  the  absence  of  hemolysis 

^'Schiitz  and  Schubert:   "Die  Ermittelung  der  Rotzkrankheit  mit  Hilfe  der 

Komplementablenkungsmethode."  Archiv  fur  tvissenschajtliche  und  praktische 
Tierheilkunde.     Bd.  35,  Heft  1  and  2,  pp.  44-83,  1909. 


400 


MISCELLANEOUS  DISEASES 


means  the  presence  of  glanders,  and  vice  versa.  The  tests  must  always 
be  carried  out  with  controls  and  carefully  conducted  as  to  the  amount 
of  each  substance  used,  the  temperature  and  time.^^  The  technic  and 
interpretation  is  precisely  that  of  the  Wassermann  reaction  (page  583), 
except  tliat  the  antigen  is  an  extract  of  the  glanders  bacilli. 

Prevention.- — When  glanders  is  discovered  or  suspected  among  horses 
in  a  stable,  the  horses  in  the  infected  stable  should  be  tested  in  the 


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FiG.  51. — Diagrammatic  Representation  of  Complement  Fixation.  Mohler  and 
Eichhorn,  Bull.  136,  B.A.I.,  U.  S.  Dept  of  Agriculture. 

A,  Hemolytic  system. 

B,  Bacteriolytic  system. 

C,  Negative  reaction  with  normal  horse  serum. 

D,  Positive  reaction  with  glandered  horse  serum. 

manner  above  described.    All  animals  with  glanders  should  be  destroyed 

without  further  consideration.    After  these  animals  have  been  killed  and 

properly   disposed   of,   tlie   stable   should  be   thoroughly   cleansed   and 

disinfected.     All  other  horses  which  have  in  any  way  been  associated 

with  the  infected  animals  should  be  carefully  watched  and  tested  again 

after  three  weeks,  and,  should  there  be  no  indication  of  the  disease  in 

the  second  test,  the  stable  may  be  considered  free  from  the  infection; 

otherwise  the  infected  animals  should  be  destroyed  and  the  tests  repeated 

every  three  weeks  until  the  disease  has  been  eliminated, 

"  A  complete  description  of  the  diagnosis  of  glanders  by  complement  fixa- 
tion, giving  in  full  all  the  details,  will  be  found  in  Bull.  136,  Bureau  of  Animal 
Industry,  Apr.  7,  1911,  by  Mohler  and  Eichhorn. 


ANTHRAX  401 

The  eradication  of  glaiidi'is  lioiii  a  stable  often  means  considerable 
loss  and  sometimes  a  sacrilicc  )!'  valuable  animals,  but  it  is  only  through 
vigorous  measures  that  the  disease  may  be  controlled.  In  the  disin- 
fection and  cleansing,  sjunial  attention  should  be  paid  to  the  stalls, 
harnesses,  water  troughs,  bits,  food  containers,  curry  combs,  sponges, 
and  other  objects  exposed  to  the  infection,  whicli  is  eliminated  mostly 
in  the  secretions  from  the  mouth  and  nose.  'VUc,  conmion  drinking 
trough  for  horses  spreads  the  infection.  The  bacillus  of  glanders  is 
very  susceptible  to  bleaching  powder,  and  it  therefore  is  a  cheap  and 
reliable  germicide  for  this  jmrpose. 

The  personal  prophylaxis  of  glanders  in  man  depends  upon  the 
education  and  care  of  those  who  have  to  handle  horses.  In  working 
with  horses  known  to  be  infected  rubber  gloves,  disinfection,  and  other 
methods  of  protection  should  be  employed.  Special  care  should  be 
taken  to  prevent  the  spread  of  the  disease  through  the  discharges  or 
by  infected  fomites  from  human  cases.  Fatal  accidents  have  occurred 
in  laboratories  in  research  workers  handling  pure  cultures  of  B.  mallei. 


ANTHRAX 

(Splenic  Fever.      Charhon.) 

Anthrax  has  figured  prominently  in  the  history  of  bacteriology  and 
immunology.  The  anthrax  bacillus  was  the  first  pathogenic  microor- 
ganism to  be  seen  under  the  microscope,  by  Pollender  in  1849.  Anthrax 
was  the  first  communicable  infection  to  be  experimentally  transferred, 
when  Davaine  and  Eayer,^-  in  1850,  communicated  splenic  fever  by  the 
direct  inoculation  of  blood  containing  "infusoria"  to  susceptible  animals. 
Anthrax  was  the  first  bacterium  to  be  grown  in  pure  culture  by  Koch, 
in  1875.^^  Anthrax  was  the  first  dramatic  demonstration  by  Pasteur,^* 
in  1881,  of  the  prophjdactic  value  of  an  attenuated  virus.  Pasteur's 
work  on  anthrax  closely  followed  similar  experiments  upon  fowl  cholera. 

Anthrax  belongs  to  that  group  of  diseases  which  occurs  primarily  in 
the  lower  animals  and  secondarily  in  man.  The  infection  is  found  espe- 
cially in  cattle,  but  also  in  horses,  sheep,  and  other  cloven-hoofed  animals, 
and  may  be  transmitted  experimentally  to  mice,  guinea-pigs,  rats,  and 
rabbits.  Cold-blooded  animals  and  birds,  as  well  as  dogs  and  swine,  are 
refractory.  Anthrax  has  a  world-wide  distribution ;  Eussia  is  one  of 
the  principal  foci  of  infection. 

In  man  the  infection  may  enter  the  skin  (malignant  pustule)  or 
the  lungs  (wool  sorters'  disease),  or  may  enter  the  digestive  tract  and 

^'Mem.  de  la  Soc.  de  Biol,  1850,  p.  141. 

^Cohn's  beit.  zur  biol.  de  pflazen,  1876,  II,  p.  277. 

^Compt.  rend,  de  VAcad.  de  Sc,  XCII,  1881,  p.  427. 


403  MISCELLANEOUS  DISEASES 

produce  intestinal  lesions.  Human  anthrax  is  mostly  an  industrial 
disease  contracted  through  the  handling  of  skins,  hair  or  animals.  In 
anthrax  of  the  skin  the  infection  usually  enters  through  slight  abrasions, 
scratches,  or  small  wounds,  especially  on  the  forearm,  hand,  neck,  or 
face.  In  butchers  or  persons  who  handle  infected  carcasses  or  hides,  it 
is  apt  to  occur  on  the  neck  and  shoulders. 

Many  cases  of  anthrax  in  the  United  States  and  in  England  have 
been  traced  to  shaving  brushes  made  of  horse  hair.  In  Massachusetts, 
47  cases  from  shaving  brushes  were  reported  in  1917. 

The  spores  have  been  carried  to  the  skin  by  flies;  Schuberg  and 
Kuhn  ^^  have  shoi^ni  that  anthrax  may  be  transferred  from  animal  to 
animal  through  the  bite  of  the  stable  fly  (Stomoxys  calcitrans).  Mitz- 
main  obtained  positive  results  with  the  stable  fly  and  also  with  Tahanus 
striatus.^^ 

Wool  Sorters'  Disease,  or  anthrax  of  the  lungs,  appears,  to  be  due 
to  the  inhalation  of  anthrax  spores.  It  is  observed  only  among  persons 
who  handle  skins  or  who  work  with  horse  hair,  wool,  or  other  raw 
materials  from  animals. afflicted  with  anthrax.  The  symptoms  are  like 
those  of  pneumonia ;  this  form  is  frequently  fatal. 

The  mode  of  transmission  in  intestinal  anthrax  is  through  meat 
from  an  anthrax  cadaver.  The  usual  heat  of  cooking  or  even  canning 
does  not  necessarily  kill  anthrax  spores.  Intestinal  anthrax  is  rare,  but 
when  it  does  occur  is  rapidly  fatal. 

Eesistance. — The  anthrax  spore  is  exceedingly  resistant  to  heat  and 
external  influences,  such  as  dryness  and  sunlight,  and  also  to  germi- 
cidal agents.  Its  resistance  may  be  compared  to  the  tetanus  spore, 
page  100. 

Prevention. — A  number  of  species  of  animals  have  a  natural  immu- 
nity to  anthrax,  and  an  artificially  acquired  immunity  may  be  induced 
in  cattle  or  sheep  through  the  injection  of  attenuated  cultures,  in  ac- 
cordance with  the  classical  method  of  Pasteur.  These  procedures  are 
not  applicable  to  man.  The  prevention  of  the  disease  in  man  must 
first  be  directed  to  a  suppression  of  the  infection  in  animals.  The  sick 
animals  should  be  isolated,  or,  better,  killed,  and  the  carcasses  burned 
or  buried  with  lime  at  least  three  feet  deep.  The  carcasses  may  be 
"tanked,"  that  is,  subjected  to  a  prolonged  exposure  to  steam  under 
pressure.  Tanks  for  this  purpose  are  found  in  all  the  larger  slaughter 
houses.  It  is  important  in  handling  the  body  of  an  animal  dead  of 
anthrax  not  to  open  it  or  shed  blood,  for  the  bacillus  does  not  produce 
its  spore  except  in  the  presence  of  oxygen,  that  is,  the  bacilli  are  mainly 
in  the  blood  and  internal  organs  and  will  not  sporulate  as  long  as  access 
to  the  air  is  prevented. 

^  Arbeiten  a.  d.  kaiserl.  Ges.-Amt.,  Bd.  XL,  Heft  2,  1912, 
*«  Public  Health  Keports,  Jan.  9,  1914,  p.  75, 


ANTHRAX  403 

The  neglect  of  precautions  in  disposing  of  anthrax  carcasses  favors 
(he  spread  of  the  infection  throiigli  the  activity  of  carrion  feeders.  Mor- 
ris ^^  has  shown  that  buzzards  may  carry  infection  for  long  distances 
and  contaminate  clean  ground  or  water  through  contamination  on  their 
feet  and  beaks.  Dogs  discharge  anthrax  spores  in  their  feces  114  hours 
after  feeding  upon  an  anthrax  carcass. 

Gegenbauer  ^^  points  out  that  animals  may  harbor  anthrax  organisms 
in  their  hair  without  themselves  being  infected. 

The  proper  prevention  of  anthrax  consists  in  the  veterinary  control 
of  the  disease  among  animals.  The  chief  preventive  measure  so  far  as 
man  is  concerned  is  the  disinfection  of  all  raw  material  in  those  trades 
in  which  horse  hair,  hides,  wool,  and  other  substances  liable  to  harbor 
the  anthrax  spore  are  handled.  Veterinary  surgeons  who  conduct 
autopsies  upon  anthrax  animals  should  exercise  special  precautions,  and, 
if  practicable,  wear  rubber  gloves. 

Workers  in  leather  tanneries,  hair  and  wool  factories  can  be  pro- 
tected by  rubber  gloves  and  rubber  aprons.  Protection  is  also  afforded 
by  an  effective  quarantine  against  all  hides,  wool,  and  hair  from  infected 
and  suspected  areas,  and  areas  about  which  information  is  lacking.  See 
also  page  1322. 

Proper  ventilation  should  be  provided  to  carry  off  the  dust  where 
hair  and  wool  are  handled,  especially  about  carding  machines.  The 
refuse  from  tanneries  and  woolen  mills  should  be  properly  disposed  of; 
otherwise  they  may  infect  streams  or  fields  through  fertilizers. 

A  serum  made  by  injecting  horses  with  virulent  anthrax  bacilli 
is  used  as  a  therapeutic  agent.  Normal  bovine  serum  also  has  curative 
value ;  neither  of  these  sera  is  practical  as  a  prophylactic. 

Disinfection. — Steam  disinfection  is  practicable  for  hair,  but  not  for 
wool  or  hides.  The  wool  fiber  and  hides  are  seriously  damaged  by  the 
action  of  the  steam.  Wool  may  be  disinfected  by  formaldehyd  used 
as  given  below.  The  method  preferred  for  hides  is  the  hydrochloric 
acid-salt  bath  of  Schattenfroh.  Manufacturers  object  to  the  disinfection 
of  hides  with  bichlorid  of  mercury  and  formic  acid,  according  to  the 
Seymour-Jones  method,  on  account  of  the  apparent  injury  of  such 
treatment. 

All  hides,  wool  and  hair  from  anthrax-infected  and  suspected  areas, 
or  areas  about  which  information  is  lacking,  should  be  disinfected.  This 
disinfection  should  be  done  in  the  country  where  the  hides,  wool .  and 
hair  are  collected,  preferably  at  the  market  center,  where  the  work  could 
be  done  under  skilled  supervision. 

Hair  for  Shaving  Brtishes. — The  disinfection  of  the  hair  used 
for  shaving  and  lather  brushes,  in  accordance  with  the  requirements  of 

"  Louisiana  Bull.  No.  136,  Agr.  Exp.  Sta.,  Nov.,  1912. 
^Arch.  f.  Hyg.,  89,  202,  1920. 


404  MISCELLANEOUS  DISEASES 

the  United  States  Govemment,^^  is  accomplished  by  one  of  the  following 
methods:  (a)  by  boiling  the  hair  or  bristles  for  not  less  than  three 
hours;  (b)  by  exposing  the  hair  or  bristles  to  steam  under  not  less  than 
fifteen  pounds  gauge  pressure  for  not  less  than  thirty  minutes  with 
a  preliminary  vacuum  of  not  less  than  ten  inches  before  turning  on 
the  steam;  (c)  by  exposure  to  streaming  steam  for  not  less  than  six 
hours. 

Shaving  Brushes. — Any  brushes  found  in  the  market  which  do  not 
bear  the  name  or  the  trade  mark  of  the  manufacturer  should  be  regarded, 
with  suspicion,  and  should  be  returned  to  the  source  from  which  they 
were  secured,  or  should  be  disinfected. 

For  the  sterilization  of  the  brushes  themselves  the  following  pro- 
cedure is  believed  to  be  effective: 

The  brush  should  be  soaked  for  four  hours  in  a  10  per  cent,  solution 
of  formalin  (by  formalin  is  meant  a  40  per  cent,  solution  of  formal- 
dehyd).  The  solution  should  be  kept  at  a  temperature  of  110°  F.  and 
the  brush  so  agitated  as  to  bring  the  solution  into  contact  with  all  hair 
or  bristles.*" 

Obviously  it  would  be  better  to  avoid  the  use  of  horse  hair  in  shav- 
ing brushes,  because  of  the  extraordinary  hazard  from  them. 

Wool. — The  Departmental  Committee  on  Anthrax  *^  recommends 
the  following  for  the  disinfection  of  wool,  goat  hair  and  camel  hair:  A 
preliminary  agitation  with  an  alkaline  solution  of  soap  in  water  at  a 
temperature  of  102°  to  110°  F. ;  exposure  for  20  minutes  in  a  2  to  2i/2 
per  cent,  solution  of  formaldehyd  in  water  at  a  temperature  of  102°  to 
105°  F.  The  hair  is  then  dried  in  a  current  of  air  at  160°  F.,  and 
allowed  to  stand  a  short  time  in  order  that  the  formaldehyd  may  com- 
plete its  germicidal  action. 

Hides  and  Skins. —  (1)  The  Seymour-Jones  method:  To  1  pound  of 
perchlorid  of  mercury  add  500  gallons  of  water,  and  to  this  mixture  add 
5  gallons  of  formic  acid  (commercial  50  per  cent,  strength).  In  this 
bath  steep  the  material  for  twenty-four  hours. 

(2)  The  Schattenfroh  method:  In  a  2  per  cent,  hydrochloric  acid 
solution  to  which  10  per  cent,  of  common  salt  has  been  added  steep  the 
material  for  40  hours  at  a  temperature  of  60°-70°  C.  A  quicker  method 
can  be  used  by  substituting  a  1  per  cent,  solution  of  hydrochloric  acid 
and  8  per  cent,  of  salt,  provided  the  temperature  of  the  solution  is  main- 
tained at  40°  C.  (104°  F.)  for  a  period  of  six  hours.*^ 

^  Interstate  Quarantine  Regulations,  Treasury  Dept.,  Washineton,  July  30, 
1918. 

*"  Report  of  the  Departmental  Committee  on  Anthrax,  Vol.  II,  London,  1918. 

*^  Public  Health  Bureau  Circular  Letter  No.  136,  dated  July  31,   1918. 

'^Industrial  Bull.  No.  6,  Commonwealth  of  Mass.,  State  Bd.  of  Labor  and 
Industries,  p.  7. 


FOOT-AND-MOUTH  DISEASE  405 

Hmr,  Bristles  and  Pigs'  ]Vool.—  {l)  By  letting  a  current  of 
steam  act  on  the  material  for  not  less  than  one-half  hour  at  a  pressure 
of  17  pounds  (0.15  above  atmospheric  pressure)  ; 

(2)  By  boiling  for  at  least  one-quarter  of  an  hour  in  a  solution  con- 
taining 2  per  cent,  of  permanganate  of  potassium,  and  subsequent  bleach- 
ing with  a  3  or  4  per  cent,  solution  of  sulphurous  acid ; 

(3)  By  boiling  in  water  for  not  less  than  two  hours. 

FOOT-AND-MOUTH  DISEASE 

Foot-and-mouth  disease  is  also  kno^\^^  as  aphthous  fever,  epizootic 
catarrh,  and  eczema  contagiosa.  It  is  an  acute  and  highly  commu- 
nicable disease,  generally  confined  to  cloven-footed  animals,  and  char- 
acterized by  an  eruption  of  vesicles  on  the  mucous  membrane  of  the 
mouth  and  on  the  skin  between  the  toes  and  above  the  hoofs;  seldom 
on  the  udder  or  other  parts  of  the  body.  The  vesicles  rupture,  leaving 
superficial  erosions  which  sometimes  develop  into  ulcers.  Other  symp- 
toms are:  salivation,  tenderness  of  the  affected  parts,  loss  of  appetite, 
lameness,  emaciation,  and  diminution  in  the  quantity  of  milk  secreted. 

Foot-and-mouth  disease  is  primarily  a  disease  of  cattle  and  sec- 
ondarily of  man.  It  also  affects  hogs,  sheep,  goats,  buffalo,  American 
bison,  camel,  chamois,  llama,  giraffe,  antelope,  and  even  dogs  and  cats 
are  said  to  occasionally  become  infected.  Horses  and  fowl  are  not 
susceptible. 

The  disease  prevails  in  European  countries,  especially  Eussia,  also 
South  America,  Asia  and  Africa,  and  occasions  great  economic  loss.  The 
mortality  is  low;  the  serious  losses  depend  chiefly  upon  the  diminution 
of  the  milk  secretion  and  the  loss  of  flesh  in  the  affected  animals  as  well 
as  the  disturbances  of  quarantine.  It  occurs  as  widespread  epizootics, 
especially  in  the  warm  season. 

Foot-and-mouth  disease  has  appeared  in  the  United  States  only  on 
six  different  occasions— in  1870,  1§80,  1884,  1902-3,  1908,  and  1914. 
Every  outbreak  on  x\merican  soil  has  thus  far  been  followed  by  its  com- 
plete suppression  through  the  application  of  well-known  preventive  meas- 
ures, such  as  isolation,  destruction  and  burial  of  the  affected  herds,  disin- 
fection, restriction  of  the  movements  of  cattle,  and  a  systematic 
inspection  of  all  farms  in  the  infected  area  to  detect  cases  of  the 
disease. 

Animals  may  be  infected  directly,  as  by  licking,  and  in  calves  by 
sucking,  or  indirectly  by  fomites  such  as  infected  manure,  hay,  utensils, 
drinking  troughs,  railway  cars,  animal  markets,  barnyards,  and  pastures. 
The  spread  of  the  disease  is  due  largely  to  carrying  of  the  infection  on 
the  hands  of  persons  who  examine,  milk,  or  otherwise  come  in  contact 
with  diseased  animals. 


406  MISCELLANEOUS  DISEASES 

Veterinary  inspectors  must  take  unusual  precautions  not  to  spread 
the  infection  in  their  efforts  to  control  it. 

Loffler  and  Frosch  *^  in  1898  showed  that  the  virus  will  pass  the 
finest  porcelain  filters.  This  was  the  first  "ultramicroscopic"  virus  dis- 
covered. The  specific  principle  is  contained  in  the  serum  of  the  vesicles ; 
in  the  saliva,  tears,  milk,  and  various  other  secretions  and  excretions; 
also  in  the  blood  until  the  eruption  comes  out,  then  it  disappears. 

No  definite  immunity  is  rendered  by  an  attack.  The  period  of  in- 
cubation is  variable,  usually  from  two  to  six  days  or  longer,  excep- 
tional instances  being  prolonged  to  fifteen  or  even  eighteen  days. 

The  disease  in  man  is  a  direct  counterpart  of  that  in  cattle.  The 
infection  is  transmitted  to  man  through  the  ingestion  of  raw  milk, 
buttermilk,  butter,  cheese,  and  whey  from  animals  suffering  with  foot- 
and-mouth  disease.  It  may  also,  though  more  rarely,  be  transmitted 
directly  from  the  salivary  secretions  or  other  infected  material  which 
gains  entrance  through  the  mucous  membrane  of  the  mouth.  It  is  doubt- 
ful whether  the  disease  can  be  transmitted  to  man  by  cutaneous  or  sub- 
cutaneous inoculations,  though  it  is  probable  that  the  infection  may  be 
communicated  if  the  virus  enters  the  blood  directly  through  wounds  of 
any  kind.  Children  are  most  frequently  infected  by  drinking  unboiled 
milk  during  the  time  in  which  the  disease  is  prevalent  in  the  neighbor- 
hood; while  persons  in  charge  of  diseased  animals  may  become  infected 
through  contact  with  the  affected  parts  or  by  milking,  slaughtering,  or 
caring  for  the  animals.  The  disease  is  usually  mild  in  man ;  death  prac- 
tically never  results,  except  in  weakened  children,  and  then  from  sec- 
ondary complications. 

The  original  experiments  of  Loffler  and  Frosch,  as  well  as  recent 
experiments  which  have  been  made  in  Denmark  and  Germany,  indicate 
that  the  virus  is  destroyed  comparatively  readily  by  heat  or  the  usual 
germicides,  except  phenols  and  cresols,  which  are  unreliable  for  this 
and  other  filterable  viruses.  Milk  pasteurized  at  a  temperature  of  60°  C. 
for  20  minutes  is  safe. 

Foot-and-mouth  disease  has  a  special  interest  on  account  of  the  fact 
that  it  may  be  associated  with  vaccinia.  Vaccine  virus  has  been  known 
to  contain  the  infection  of  foot-and-mouth  disease.**  Glycerin  acts  as  a 
preservative  for  the  virus  of  foot-and-mouth  disease,  so  that  it  may 
remain  viable  in  glycerinated  vaccine  virus  a  very  long  time.  No 
instance  of  the  transmission  of  foot-and-mouth  disease  to  man  through 
vaccine  virus  has  been  recorded,  and  it  is  doubtful,  in  view  of  the  known 
facts,  whether  it  is  possible  to  reproduce  the  disease  in  man  by  the 
cutaneous   inoculation   commonly  used  in  the   process  of  vaccination. 

"^Deut.  med.  Wochenschrift,  1898,  Vol.  XXIV,  p.  80. 

""The  Origin  of  the  Recent  Outbreak  of  Foot-and-Mouth  Disease  in  the 
United  States,"  by  Mohler  and  Rosenau,  Cir.  i|7,  Bureau  of  Animal  Industry, 
Dept.  of  Agriculture,  1909. 


MALTA  FEVER  407 

The  prevention  of  foot-and-nioutli  infection  in  vaccine  virus  is  assured 
through  fcnieral  inspection  and  through  special  tests.  See  Vaccine  Virus, 
page  '2\. 

The  prevention  of  foot-and-mouth  disease  consists  (1)  in  a  cattle 
quarantine,  to  keep  it  out  of  countries  wliere  it  does  not  exist;  (2)  in 
the  elimination  of  the  disease  in  cattle  through  isolation  of  infected 
herds,  destruction  and  burial  of  the  sick  animals,  and  disinfection; 
(3)  the  disease  in  man  may  be  avoided  by  care  in  the  selection  of  the 
animals  from  which  milk  is  taken  or  by  pasteurization  of  the  milk  when 
foot-and-mouth  disease  is  prevalent. 

Lisboa  and  da  Rocha  *^  report  good  results  from  the  use  of  a  vaccine 
which  confers  an  immunity  lasting  from  four  months  to  a  year. 


MALTA  FEVER 

Malta  fever  is  a  general  infection  not  unlike  other  specific  bacteri- 
emias,  such  as  typhoid  fever.  It  is  caused  by  the  Micrococcus  meliten- 
sis,  discovered  by  Bruce  in  1887  during  the  earlier  days  of  bacteriology. 
Clinically  the  disease  is  characterized  by  profuse  perspiration,  constipa- 
tion, frequent  relapses  often  accompanied  by  pains  of  a  rheumatic  or 
neuralgic  character,  and  sometimes  swelling  of  the  joints  or  orchitis. 
Malta  fever  is  further  characterized  by  its  low  mortality  and  long- 
drawn-out  and  indefinite  duration.  It  prevails  especially  about  the 
Mediterranean  basin.  Malta  fever  is  a  disease  primarily  of  goats,  sec- 
ondarily of  man. 

Gentry  and  Ferenbaugh  *"  in  1911  found  a  nest  of  malta  fever 
throughout  the  older  goat-raising  sections  of  Texas.  This  endemic  cen- 
ter embraces  an  area  approximately  300  miles  along  the  Rio  Grande 
extending  90  miles  to  the  north.  All  the  cases  of  malta  fever  found 
have  occurred  in  territory  devoted  to  goat  raising,  and  all  the  patients 
there  gave  a  history  of  drinking  unboiled  goats'  milk,  or  were  associated 
with  the  goat-raising  industry.  The  Micrococcus  melitensis  was  isolated 
from  several  of  the  cases. 

Modes  of  Transmission. — From  experimental  evidence  it  would  ap- 
pear that  the  infection  of  malta  fever  may  be  taken  in  through  wounds, 
the  mucous  membranes,  or  by  food  and  drink.  The  usual  mode  of  in- 
fection is  by  drinking  raw  goats'  milk.  The  Micrococcus  melitensis 
leaves  the  body  in  various  secretions  and  excretions.  Great  numbers 
of  the  cocci  in  pure  cultures  may  appear  in  the  urine.  The  milk  of 
goats  also  contains  the  virus.  All  the  secretions  from  the  body  must 
be  regarded  as  infectious  until  further  knowledge  on  the  subject  is  at 

«Mem.  de  Inst.  Oswaldo  Cruz,  1920,  XII,  No.  1,  p.  66. 
«./owr.  A.  M.  A.,  Aug.  26,  Sept.  9,  Sept.  23,  Sept.  30,  1911. 


408  MISCELLANEOUS  DISEASES 

hand.  In  man  the  coccus  may  be  isolated  from  the  spleen,  lymph  glands, 
bone  marrow,  and  mammary  glands.  In  goats  it  first  disappears  from 
the  blood,  then  the  spleen,  and,  last  of  all,  from  the  mammary  glands. 

Goats  are  susceptible  to  malta  fever  and  continue  to  discharge  the 
infection  in  the  milk  for  a  long  time.  The  disease  is  usually  contracted 
by  drinking  such  infected  milk.  While  this  is  the  common  mode  of 
infection,  occasional  cases  doubtless  arise  through  other  sources;  thus 
one  case  which  arose  in  England  is  supposed  to  have  been  conveyed 
from  son  to  father  by  using  a  clinical  thermometer  in  the  mouth  im- 
mediately after  its  use  by  the  patient.  Monkeys  may  readily  be  in- 
fected either  by  the  inoculation  of  pure  cultures  or  by  feeding  them. 
At  least  five  accidental  infections  have  occurred  in  bacteriological 
laboratories,  one  in  Washington.  Macfadyen  lost  his  life  from  a  labora- 
tory infection  with  the  Micrococcus  melitensis.  This  microorganism  has, 
therefore,  more  than  complied  with  all  the  requirements  of  Koch's  laws. 

There  has  long  been  a  suspicion  that  malta  fever  may  be  conveyed 
through  the  bite  of  an  ectoparasite.  In  fact,  Captain  Kennedy  was 
able  experimentally  to  infect  a  monkey  as  a  result  of  bites  of  mos- 
quitoes (Culex  pipiens)  which  had  fed  on  patients  suffering  with  malta 
fever.  This  probably  was  an  instance  of  mechanical  transference  of 
the  infection,  corresponding  in  all  respects  to  a  laboratory  inoculation 
with  fresh  virulent  material  from  a  hypodermic  syringe.  This  cannot 
be  a  frequent  way  by  which  the  infection  is  transmitted  in  nature,  for 
the  specific  organisms  are  found  in  small  numbers  in  the  peripheral 
blood  of  malta  fever  patients.  The  British  Commission  found  the  Micro- 
coccus melitensis  only  four  times  from  a  total  of  896  mosquitoes  studied. 

From  the  fact  that  the  micrococcus  may  be  successfully  introduced 
either  by  ingestion,  or  by  inoculation,  or  through  the  mucous  mem- 
branes, it  is  evident  that  occasionally  cases  may  receive  their  infection 
through  a  great  variety  of  means,  such  as  insect  bites  and  other  wounds, 
infected  food,  and  the  various  modes  of  contact  infection.  Contact 
infection,  however,  probably  plays  a  minor  role,  for  there  is  evidence 
that  the  disease,  is  not,  as  a  rule,  directly  transmitted  from  the  sick  to 
the  well. 

There  is  also  experimental  evidence  to  show  that  monkeys  can  be 
infected  by  dry  dust  artificially  contaminated  with  cultures  of  the  Micro- 
coccus melitensis.  The  path  of  entrance  may  be  through  the  nares, 
throat,  respiratory  passages,  or  alimentary  canal.  Dry  dust  contam- 
inated with  the  urine  of  cases  of  malta  fever  has  given  rise  to  infection 
in  goats  but  not  in  monkeys.  The  experience  gained  during  the  work 
performed  in  Malta  during  1904  and  1905  has  convinced  Horrocks  that 
men  are  more  susceptible  than  monkeys  and  goats.  Shaw's  work  on 
ambulatory  eases  of  malta  fever  among  Maltese  has  also  shown  that 
opportunities  for  the  creation  of  infected  dust  were  plentiful  in  Malta. 


MALTA  FEVER  409 

Infected  dry  dust  as  a  niodo  of  transmission  (.'aiinot,  therefore,  be 
discarded. 

Goats'  Milk  and  Malta  Fever. — We  are  indebted  to  tlie  six  reports 
of  the  liritish  Coniniissioii  for  ilic  investigation  of  Mediterranean  fever 
(1905-1907)  for  the  fact  that  nialta  fever  is  chiefly  spread  through  goats' 
milk.  Before  tlic  researches  of  this  coniniission  tlio  common  mode  of 
infection  Avas  not  definitely  known. 

The  usual  source  of  milk  in  Malta  is  the  goat.  The  udders,  which 
are  abnormally  long,  often  touch  the  ground  and  are  very  liable  to  be 
soiled.  It  was  first  shown  by  Zammit  in  the  report  of  1905  that  goats 
could  be  infected  by  feeding  them  with  the  Micrococcus  melitensis. 
In  the  same  year  Major  Horrocks  discovered  the  Micrococcus  melitensis 
in  the  milk  of  an  apparently  healthy  goat.  Further  studies  showed  that 
one  or  more  healthy  goats  in  every  herd  were  excreting  the  Micrococcus 
melitensis  in  their  milk  and  urine,  and  that  about  50  per  cent,  of  the 
goats  reacted  positively  when  examined  by  serum  agglutination  tests. 
All  the  available  evidence  points  to  their  food  as  the  main  vehicle  of  in- 
fection in  goats.  The  young  goats,  of  course,  are  infected  through  their 
mother's  milk.  Horrocks  and  Kennedy  consider  that  10  per  cent,  of  the 
goats  supplying  milk  to  various  parts  of  Malta  excrete  the  Micro- 
coccus melitensis  in  their  milk.  The  excretion  of  the  specific  micro- 
organisms may  continue  steadily  for  three  months  without  any  change 
occurring  in  the  physical  character  or  chemical  composition  of  the  milk 
and  without  the  animal  exhibiting  any  signs  of  ill  health.  On  the 
other  hand,  the  excretion  of  the  Micrococcus  melitensis  in  the  milk  may 
be  intermittent,  appearing  for  a  few  days  and  then  disappearing  for  a 
week  or  more. 

Major  Horrocks  in  Beport  No.  5  of  the  British  Commission  shows 
a  direct  relation  between  the  number  of  goats  in  Gibraltar  and  the  num- 
ber of  cases  of  malta  fever.  With  the  reduction  in  the  number  of  goats 
in  Gibraltar  there  was  also  a  decrease  in  the  number  of  cases,  so  that 
finally,  when  the  number  of  goats  had  decreased  to  about  200,  in  1905, 
malta  fever  had  practically  disappeared. 

The  story  of  the  steamship  Joshua  Nicholson  is  instructive  in  show- 
ing the  relation  between  goats'  milk  and  malta  fever  in  man.  Sixty- 
one  milch  goats,  all  healthy  in  appearance  and  good  milkers  (many 
being  prize  animals),  and  four  billygoats  were  shipped  on  board  the 
cargo  steamer  Joshua  Nicholson  August  19,  1905,  at  Malta  for  passage 
to  the  United  States  via  Antwerp.  Many  of  the  ship's  company  partook 
freely  of  the  milk.  The  officers  drank  "mixed"  milk  collected  in  a  large 
vessel;  the  members  of  the  crew  each  obtained  the  "whole"  milk  from 
one  goat  in  his  own  separate  pannikin.  Subsequent  bacteriological  exam- 
ination resulted  in  the  recovery  of  the  Micrococcus  melitensis  from  the 
milk  of  several  of  the  goats.    Of  23  men  on  board  the  steamer  who  drank 


410  MISCELLANEOUS  DISEASES 

the  goats'  milk  on  one  or  more  occasions,  no  evidence  whatever  is  avail- 
able as  to  13,  while  of  the  remaining  10,  9  suffered  from  febrile  attacks^, 
5  of  them  yielding  conclusive  evidence  of  infection  with  the  Micrococcus 
melitensis. 

The  Micrococcus  Melitensis. — The  Miarucoccus  melitensis  is  read- 
ily destroyed  by  heat.  I  have  shown  that  60°  C.  for  20  minutes 
is  sufficient  to  destroy  this  organism  in  milk  and  provides  at  the  same 
time  a  liberal  margin  of  safet3^  It  is  not  destroyed  at  55°  for  a  short 
time,  but  succumbs  in  one  hour;  the  majority  die  at  58°;  at  60°  all  are 
killed.  Phenol,  1  per  cent.,  destroys  the  coccus  in  15  minutes.  While 
this  micrococcus  shows  a  comparatively  feeble  resistance  against  heat 
and  the  ordinary  germicides,  it  shows  a  remarkable  resistance  to  dry- 
ness, for  it  may  remain  alive  in  this  state  for  months. 

The  micrococcus  grows  well,  but  slowly,  upon  artificial  culture  media. 
Visible  colonies  do  not  appear  until  about  the  fifth  day.  It  may  be  kept 
alive  indefinitely  by  transplanting  to  subcultures  at  frequent  intervals. 
Exceedingly  high  agglutinating  power  develops  in  persons  suffering  with 
malta  fever — sometimes  as  high  as  1-100,000.  In  such  cases  the  pro- 
agglutinoid  zone  may  appear,  that  is,  the  serum  may  refuse  to  agglu- 
tinate in  low  dilutions,  such  as  1-100,  but  agglutinate  actively  in  higher 
dilutions,  such  as  1-1,000. 

Meyer  and  Shaw*''  call  attention  to  the  fact  that  it  is  not  possible 
to  distinguish  between  Micrococcus  melitensis  and  Bacillus  abortus. 
Feusier  and  Meyer  **  show  a  similarity  in  agglutinins. 

Prevention. — Our  knowledge  of  the  cause  and  modes  of  transmission 
of  malta  fever  makes  the  prevention  of  this  disease  a  comparatively 
simple  problem.  The  infection  must  first  be  eliminated  in  the  goats. 
Until  this  is  done  goats'  milk  should  be  pasteurized.  Patients  having  the 
disease  should  be  treated  upon  the  same  principles  laid  down  for  typhoid 
fever,  in  order  to  prevent  the  spread  of  the  infection  through  food, 
fomites,  and  contact.  Convalescents  should  not  be  released  until  the 
micrococcus  has  disappeared  from  the  urine.  General  sanitary  meas- 
ures, such  as  the  suppression  of  flies  and  mosquitoes,  allaying  dust,  and 
the  promotion  of  general  cleanliness,  should  not  be  neglected. 

YAWS 

(Framhoesia  tropica) 

Yaws  is  a  communicable  infection  caused  by  the  Treponema  pertenue, 

described  by  Castellani  in   1905.     It  is  not  a  "venereal"   disease,  but 

closely  resembles  syphilis.     It  is  named  from  the  raspberry-like  (fram- 

besiform)  appearance  of  the  eruption. 

*Wour.  Inf.  Dis.,  Sept.,   1920,  Vol,  XXVII,  No.  3,  p.   173. 
*^Jbid.,  p.  185. 


LEPROSY  411 

Yaws  is  essentially  a  tropical  disease  and  exists  in  Africa,  especially 
on  the  west  coast;  in  Asia,  it  is  common  in  the  Malay  Peninsula,  Assam, 
Upper  Burma.  Siam,  Java,  Batavia  and  Ceylon.  In  America,  it  is 
common  in  the  West  Indies,  in  British  Guiana,  Venezuela,  Colombia 
and  Brazil.  Cases  have  been  reported  from  the  southern  United  States. 
Yaws  also  occurs  in  northern  Australia  and  in  many  of  the  Pacific 
islands.'*^ 

Treponema  perienue  of  yaws  closely  resembles  Treponema,  pallidum 
of  syphilis.  Tliey  are  distinguished  only  by  animal  tests;  thus,  monkeys 
immunized  with  perienue  do  not  become  immune  for  pallidum.  The 
parasite  is  found  constantly  in  the  primary  lesion  and  in  the  unbroken 
papules  of  the  general  eruption.  It  may  also  be  found  in  the  spleen, 
lymph  glands  and  bone  marrow. 

Paulet  in  1848  inoculated  1-4  negroes  with  the  secretions  from  fram- 
betie  granulomata.  All  of  them  developed  yaws  in  from  12  to  20  days. 
Syphilitic  patients  may  contract  yaws  naturally  and  experimentally; 
yaws  patients  may  likewise  contract  syphilis.  The  two  diseases  are 
therefore  distinct. 

Yaws  is  usually  conveyed  by  direct  contact.  It  appears,  however, 
that  there  must  be  some  abraded  surface  or  small  wound,  for  the  para- 
site probably  cannot  enter  through  the  normal  skin.  Women  are  fre- 
quently infected  by  their  children,  the  primary  lesion  appearing  on  the 
mammae.  Castellani  believes  that  the  virus  may  also  be  transmitted 
by  insects,  especially  flies. 

Salvarsan  and  neo-salvarsan  are  efficacious.  Mercury  is  useless. 
Prevention  consists  therefore  in  the  treatment  of  all  active  cases  so  as 
to  destroy  the  foci  of  infection.  Personal  prophylaxis  in  endemic  centers 
consists  in  avoiding  native  contact  and  promptly  treating  the  slightest 
abrasion  of  the  skin  with  an  active  germicide.  Patients  should  be 
isolated  until  cured.  The  skin  lesions  should  be  dressed  and  other 
measures  used  to  guard  against  infection  through  the  agency  of  flies 
and  other  insects.  Traveling  clinics  in  endemic  centers  for  the  admin- 
istration of  salvarsan,  organized  after  the  manner  of  the  hookworm 
work,  could  control  yaws.  Work  of  this  kind  has  been  demonstrated  in 
Santo  Domingo. 

LEPROSY 

Leprosy  is  a  contagious  disease  in  the  sense  that  it  is  probably  always 

communicated  directly  from  the  sick  to  the  well,  but  prolonged  and 

intimate  association  with  a  leper  ordinarily  seems  necessary  to  contract 

^  It  has  been  suggested  by  Hume,  Adams  and  others  that  yaws  was  the 
disease  which  afflicted  the  Israelites  during  their  emigration  from  Egypt,  and 
that  therefore  the  term  "saraat"  in  the  thirteenth  chapter  of  Leviticus  does  not 
mean  leprosy  as  usually  translated. 


412  MISCELLANEOUS  DISEASES 

the  infection.  The  degree  of  the  contagiousness  varies  very  much,  de- 
pending upon  conditions  not  well  understood,  but  it  is  plain  that  leprosy 
shows  little  tendency  to  spread  in  any  of  the  more  highly  civilized  nations 
practicing  personal  cleanliness  and  enjoying  the  benefits  of  modern  sani- 
tation. 

In  many  localities  the  introduction  of  even  a  number  of  lepers  does 
not  lead  to  the  spread  of  the  infection. 

When  the  standards  of  living  improve,  the  disease  tends  to  diminish. 
The  fear  of  the  disease  is  almost  without  parallel.  Leprosy  prevailed 
in  epidemic  form  in  Europe  in  the  middle  ages,  but  the  disease  has 
disappeared  from  central  Europe,  remaining  only  upon  the  fringe  of 
the  Continent,  in  ISTorway,  Sweden,  Spain,  Italy,  Greece,  Turkey,  Eus- 
sia,  and  Finland.  There  are  a  considerable  number  of  cases  of  local 
origin  in  Austria  (Bosnia  and  Herzegovina),  and  a  few  in  Germany 
(Memel),  France,  and  Bulgaria.  It  is  estimated  that  there 'are  from 
5,000  to  6,000  lepers  in  the  Philippine  Islands,  and  there  are  many  cases 
in  China  and  Japan.  In  India  the  census  of  1910  shows  an  increase 
from  100,000  to  110,000  during  the  previous  ten  years.  Leprosy  is  also 
on  the  increase  in  southern  Africa  (Bay on)  ;  in  Basutuland  alone  it  is 
estimated  (1912)  that  there  are  3,000  lepers,  in  a  population  of  about 
270,000.  The  greatest  incidence  is  found  among  the  natives,  of  the 
Hawaiian  Islands,  where  one  in  every  40  or  50  have  the  disease.  Leprosy 
began  to  attract  attention  in  the  Hawaiian  Islands  about  1859,  and 
there  found  conditions  particularly  favorable  for  spread.  Precisely 
when  it  was  introduced  is  uncertain. 

In  40  years  close  to  5,000  cases  were  reported.  A  Government  Com- 
mission in  1902  ^°  took  a  census  of  the  lepers  in  the  United  States  and 
found  278.  Of  these  145  were  born  in  the  United  States  and  186  prob- 
ably contracted  the  disease  in  the  United  States.  Of  the  entire  number 
72  of  the  cases  were  isolated  and  205  were  at  large.  BrinckerhofE  again 
studied  the  prevalence  of  leprosy  in  the  United  States  in  1909  and  found 
139  cases.  The  official  figures  for  1912  are  146.^^  Competent  leprol- 
ogists  believe  that  the  total  number  of  cases  is  not  far  from  500. 

It  is  evident  that  the  disease  is  not  markedly  on  the  increase  in  our 
country  and  that,  while  it  may  be  contracted  here,  it  is  "^contagious" 
with  great  difiiculty.  There  are  three  foci  of  leprosy  in  the  United 
States:  one  among  the  Scandinavians  in  the  region  of  the  Great  Lakes, 

^'' White,  Vaughan,  and  Rosenau,  Document  No.  269,  57th  Congress,  1st  Ses- 
sion, 1902. 

°^  Complete  returns  from  only  18  states.  The  incompleteness  of  the  official 
returns  is  indicated  by  the  fact  that  New  York  State  acknowledged  only  5  cases, 
whereas  at  a  recent  medical  meeting  more  than  that  number  of  cases  were 
shown  in  New  York  City  alone.  The  laws  concerning  leprosy  vary  in  the  differ- 
ent states.  New  York,  for  example,  has  no  stringent  laws  and  there  are  40  or 
50  cases  at  large  in  New  York  City.  Pennsylvania  and  Massachusetts,  on  the 
other  hand,  enforce  strict  segregation. 


LEPEOSY  413 

made  up  almost  exclusively  of  imported  cases,  another  among  the  Ori- 
entals on  the  Pacific  Coast,  likewise  chiefly  of  imported  cases,  and  the 
third  on  the  Cailf  Coast,  particularly  in  Louisiana,  Texas  and  Florida, 
where  most  of  the  cases  are  native  born.  According  to  the  most  recent 
figures  available  (1914)  the  number  of  cases  in  isolation  in  our  insular 
possessions  is  as  follows:  Hawaii,  .643 ;  Porto  I?ico,  28;  Philippine  Is- 
lands, 4,()2i) ;  the  Canal  Zone,  7.  The  lepers  in  Guam,  18  in  number, 
w^ere  transferred  to  the  Philippine  leper  colony  at  Culion  during  1913. 
It  is  known,  however,  that  everywhere  that  the  disease  prevails  many 
cases  escape  tabulation  in  the  official  returns.  There  are  perhaps  a 
million  lepers  in  the  world.  About  50  per  cent,  more  males  are  affected 
than  females. 

The  cause  of  leprosy  is  the  Bacillus  leprae  discovered  by  Armauer- 
Hansen  in  1874.  The  bacillus  of  leprosy  resembles  the  bacillus  of  tuber- 
culosis in  many,  though  superficial,  respects.  It -stains  more  readily  and 
decolorizes  somewhat  more  readily  than  the  tubercle  bacillus,  but  dif- 
ferential staining  reactions  are  not  trustworthy.  It  differs  from  the 
tubercle  bacillus  in  that  it  grows  with  difficulty  on  artificial  culture 
media  in  primary  cultures  and  is  not  pathogenic  for  the  lower  animals. 
Further,  lepra  bacilli  are  usually  found  in  dense  clusters  and  in  much 
greater  numbers  within  the  cells  than  is  the  case  with  the  tubercle 
bacillus. 

The  bacillus  of  leprosy  grows  with  "difficulty  upon  artificial  culture 
media.  For  years  it  has  evaded  all  attempts  until  Clegg  ^^  in  1909  suc- 
ceeded in  cultivating  an  acid-fast  bacillus  in  symbiosis  with  amebae  and 
cholera  vibrio  upon  plain  agar  and  weakly  nutrient  agar.  Clegg  based 
his  work  upon  the  belief  that  the  leprosy  bacillus  derives  its  nutrition 
from  the  products  of  the  tissue  cells  in  which  it  is  mainly  to  be  seen  in 
leprosy  lesions.  These  results  have  been  confirmed  by  Currie,  Brincker- 
hoff,  Holmann  and  McCoy  in  Hawaii  and  by  Duval  in  Xew  Orleans. 

The  latter  has  shown  that  the  amebas  are  not  essential  and  that 
other  microorganisms  may  replace  the  cholera  vibrio  or  that  the  addition 
of  certain  amino-acids  (tryptophan  and  cystein)  to  the  media  is  suffi- 
cient to  bring  about  the  necessary  conditions  for  growth."  There  is  no 
satisfactory  evidence  that  any  of  the  cultures  isolated  will  reproduce  the 
disease  in  experimental  animals. 

Immunity. — There  is  no  racial  immunity  to  leprosy.  The  white 
races  suffered  severely  during  the  middle  ages.  Malays,  Mongols  and 
Negroes  now  appear  most  liable  to  the  infection,  perhaps  on  account  of 
their  mode  of  life.  The  disease  is  remarkable  for  its  prolonged  period 
of  incubation  and  its  chronic  course.  The  lesions  may  not  be  noticed 
until  20  or  more  years  after  exposure.    The  disease  is  not  usually  recog- 

"  The  Philippine  Jour,  of  Science,  Vol.  IV,  No.  77,  Apr.,  1909.  Public  Health 
Bull.  No.  //7,  Sept.,  1911. 


414  MISCELLANEOUS  DISEASES 

nized  until  several  years  have  elapsed.  These  facts  indicate  that  the 
body  must  possess  a  high  degree  of  resistance  to  this  infection.  So  far 
as  known,  man  is  the  only  animal  subject  to  leprosy  under  natural  condi- 
tions. Inoculation  experiments  into  lower  animals  have  recently  been 
reported  in  the  guinea-pig  (Clegg)  ;  the  Japanese  dancing  mouse  (Su- 
gai)  ;  and  the  monkey  (Duval).  It  is  questionable,  however,  whether 
the  disease  has  been  reproduced  in  the  lower  animals. 

Leprous  material  has  been  inoculated  into  human  beings  by  Daniel- 
son,  Profeta,  Cagnina  and  Bargilli  with  negative  results.  These  experi- 
ments demonstrate  the  resistance  of  the  body  to  the  virus.  In  Arning's 
well-known  case  of  the  convict  Keanu,  who  was  pardoned  on  condition 
that  he  allow  himself  to  be  inoculated  with  leprosy,  the  disease  did 
develop,  but  the  experiment  is  somewhat  spoiled  by  the  fact  that  the 
man  lived  in  a  leprosy  focus  and  had  lepers  among  his  relatives. 

Rat  Leprosy. — There  is  a  disease  among  rats  which  is  a  close  coun- 
terpart of  leprosy  in  man.  It  occurs  naturally  in  the  Mus  norvegicus 
and  may  be  transferred  by  inoculation  to  the  more  tractable  laboratory 
white  rat.  The  disease  was  first  observed  by  Stenfansky  in  1903  in 
Odessa.  In  the  same  year  Eabinowitsch  found  the  disease  among  the 
rats  of  Berlin,  and  Dean  in  1903  discovered  the  disease  independently 
in  London,  and  in  a  later  publication  (1905)  reported  success  in  trans- 
ferring the  infection  by  artificial  inoculation.  Since  then  rat  leprosy 
has  been  found  by  Tidswell  in  the  rats  of  Sydney,  Australia ;  by  Kitasato 
in  Japan;  Marchoux  and  Leboeuf  in  Paris,  and  the  English  Plague 
Commission  observed  the  disease  among  the  rats  in  India.  Wherry  and 
McCoy  found  a  number  of  cases  among  the  rats  caught  in  San  Francisco, 
California. 

The  proportion  of  rats  infected  with  rat  leprosy  in  different  localities 
varies  greatly;  thus  in  Odessa  and  Paris  from  4  to  5  per  cent.,  in  San 
Francisco  0.2  per  cent.,  and  in  Sydney  only  0.001  per  cent.  Currie 
failed  to  find  leprosy  among  the  rats  of  Honolulu.  The  fact  that  the 
infection  is  absent  among  the  rats  of  Honolulu  and  present  among  the 
rats  in  Berlin  is  evidence  that  it  plays  no  part  in  the  epidemiology  of 
the  human  disease. 

Leprous  rats  in  a  late  stage  of  the  disease  are  usually  recognized 
by  the  presence  of  patchy  alopecia  associated  with  cutaneous  and  sub- 
cutaneous nodules  which  may  be  the  site  of  open  ulcers;  only  in  ad- 
vanced cases  are  the  internal  organs  affected.  The  diagnosis  is  readily 
confirmed  by  microscopic  examination  of  a  smear  from  an  ulcer  or  a 
nodule,  which  will  show  the  acid-  and  alcohol-fast  bacillus  of  the  disease 
in  enormous  numbers,  and  mostly  in  the  cells. 

Currie  has  shown  that  rats  may  infect  each  other  by  contact,  also 
that  bacilli  of  rat  leprosy  may  often  be  demonstrated  in  the  heart's 
blood   of  infected   rats.      Currie    and   also    Marchoux   and    Sorel   had 


LEPROSY  415 

no  difficulty  in  demonstrating  the  presence  of  acid-fast  bacilli  in  mites 
contained  on  the  bodies  of  rats  when  the  hitter's  heart's  blood  contained 
the  microorganisms.  The  fact  that  these  mites  so  frequently  contain  tlie 
bacilli  naturally  leads  to  the  suspicion  that  tlu-y  may  be  one  of  the  means 
of  transmitting  the  disease  from  rat  to  rat,  l)ut  up  tu  the  present  time  no 
positive  evidence  has  been  aihhiccd  that  such  is  the  case. 

Mezinccscu.  using  rat  leprosy  antigen,  obtained  complete  complement 
fixation  with  human  leprosy  serum;  this  confirmed  Slatineau's  work. 
Schmitt  obtained  positive  results  with  syphilitic  antigen  and  human 
leprosy  serum,  and  numerous  other  observers  have,  with  different  antigens 
and  serum,  obtained  positive  reactions  and  thus  have  shown  the  simi- 
larity of  the  two  diseases.  The  bacillus  has  been  cultivated  by  Dean, 
Hollman,  Chapin,  and  others. 

In  this  leprosy-like  disease  of  rats  v/e  have  an  infection  which  closely 
resembles  leprosy  in  man.  The  fact  that  the  infection  may  be  propagated 
in  a  laboratory  animal  permits  of  its  investigation,  and  it  is  hoped  that 
further  studies  upon  rat  leprosy  will  throw  light  upon  the  modes  of 
transmission  and  control  of  the  human  disease. 

Modes  of  Transmission. — The  leprosy  bacillus  is  found  in  all  the 
lesions  of  the  disease — the  nodules  on  the  skin  and  mucous  membranes, 
in  the  spleen,  liver,  and  testicles — in  fact,  in  all  the  internal  lesions. 
In  the  anesthetic  type  the  bacilli  are  found  in  the  cells  of  the  spinal 
cord  and  brain  and  also  in  the  peripheral  nerves.  Leprosy  bacilli  may 
also  be  found  in  the  circulating  blood  during  the  febrile  attacks.  Fre- 
quently they  are  in  the  endothelial  or  in  the  white  blood  cells.  The  lep- 
rosy bacillus  leaves  the  body  from  any  of  the  lesions  that  are  broken 
down.  From  the  degenerated  nodules  of  the  skin  or  mucous  membranes 
they  are  discharged  in  enormous  numbers.  If  we  may  depend  upon 
microchemical  evidence,  it  appears  that  most  of  these  bacilli  are  probably 
dead.  Leprosy  bacilli  also  occasionally  appear  in  the  feces  and  urine. 
They  occur  in  the  expectoration  from  lesions  in  the  throat  wdiich  are 
common. 

There  is  some  doubt  as  to  just  how  the  leprosy  bacillus  enters  the 
body,  whether  through  wounds  of  the  skin  or  through  the  mucous 
membrane  of  the  nose  and  throat  or  through  the  digestive  tract,  or 
possibly  during  coitus.     Insects  are  also  suspected. 

It  may  be  definitely  stated  that  leprosy  is  not  due  to  the  eating  of 
any  particular  food,  such  as  fish.  This  theory  has  been  stoutly  main- 
tained by  Jonathan  Hutchinson.  There  is  no  satisfactory  evidence  in 
support  of  the  fish  theory  and  many  facts  against  it.  One  thing  is  plain, 
and  that  is,  leprosy  is  not  contracted  from  any  of  the  lower  animals,  but 
is  an  infection  which  in  all  cases  passes  rather  directly  from  man  to  man. 

The  suspicion  that  parasitic  insects  may  play  some  role  in  the  trans- 
mission of  leprosy  has  existed  for  some  time.     The  evidence  is  reviewed 


416  MISCELLANEOUS  DISEASES 

by  ISTuttall,"  who  says :  "It  appears  that  Linnaeus  and  Rolander  consid- 
ered that  Chlorops  (musca)  leprae  was  able  to  cause  leprosy  by  its  bite." 
Blauchard  and  Corrodor  tell  of  flies  in  connection  with  leprosy.  Elies 
frequently  gather  in  great  numbers  on  the  leprous  ulcers  and  then  visit 
and  bite  other  persons.  An  observation  by  Boeck  of  the  presence  of 
Sarcoptes  scabei  in  a  case  of  cutaneous  leprosy  led  Joly  to  conclude  that 
these  parasites  might  at  times  serve  as  carriers  of  the  infection.  Pediculi 
are  usually  present  among  the  poor  classes  in  Algeria,  which  furnish  the 
greater  number  of  lepers.  Sommer  of  Buenos  Aires  expresses  the  belief 
that  mosquitoes  act  as  active  agents  in  the  spread  of  leprosy  in  warm 
countries.  Carrasquillo  of  Bogota  found  the  bacillus  of  Hansen  in  the 
intestinal  contents  of  flies.  The  British  Leprosy  Commission  investi- 
gated the  possible  role  played  by  insects  with  entirely  negative  results. 
Wherry  studied  the  occurrence  of  lepra-like  bacilli  in  certain  flies  and 
their  larva.  He  found  that  the  fly  Chlorops  vomitoria  took  up  enormous 
numbers  of  lepra  bacilli  from  the  carcass  of  a  leper  rat  and  deposited 
them  with  their  feces,  but  the  bacilli  apparently  do  not  multiply  in  the 
flies,  as  the  latter  are  clear  of  bacilli  in  less  than  48  hours.  Larvae  of 
Chlorops  vomitoria  hatched  out  in  the  carcass  of  a  leper  rat  become 
heavily  infested  with  lepra  bacilli.  If  such  larvae  are  removed  and  fed 
on  uninfected  meat  they  soon  rid  themselves  of  most  of  the  lepra  bacilli. 
A  fly,  Musca  domestica,  caught  on  the  face  of  a  human  leper  was  found 
to  be  infested  with  lepra-like  bacilli.  The  horrid  sight  of  flies  swarming 
about  leprous  lesions  and  the  nostrils  of  leprous  beggars  is  well-known 
to  travelers  in  eastern  countries.  Lepra-like  bacilli  have  been  found  in 
bedbugs  and  these  insects  have  long  been  associated  with  the  spread  of 
the  disease. 

The  evidence  bearing  on  the  possible  role  of  insects  in  the  transmis- 
sion of  leprosy  may  be  classified  as  purely  presumptive  evidence  based 
upon  analogy,  or  as  evidence  based  simply  upon  the  finding  of  acid-fast 
bacilli  in  certain  insects.  It  must  be  plain  that  the  simple  taking  up  of 
parasites  by  an  insect  does  not  necessarily  imply  that  the  insect  plays  a 
role  in  its  transmission  from  one  host  to  another.  Further,  not  all  acid- 
fast  bacilli  are  leprosy  bacilli.  It  cannot  be  denied  that  leprosy  may  be 
one  of  the  insect-borne  diseases;  the  final  verdict  will  depend  upon 
further  studies. 

A  great  majority  of  lepers  at  some  time  in  the  disease  have  lepra 
bacilli  ^*  in  their  nasal  secretions.  The  importance  of  the  nose  in  leprosy 
was  brought  into  prominence  at  the  First  International  Leper  -Confer- 
ence in  1897  by  the  work  of  Sticker,  who  made  sweeping  statements 
concerning  the  nose  as  the  site  of  the  primary  lesion  and  the  danger 

^^  Johns  Hopkins  Hospital  Reports,  1900,  VIII,  p.  1. 

"Acid-fast  bacilli,  resembling  the  bacillus  of  Hansen  are  called  "lepra 
bacilli."  There  are  many  acid-fast  bacilli,  and  we  have  no  clear  criterion  to 
differentiate  the  bacillus  of  leprosy. 


LEPROSY  417 

of  nasal  secretions  in  transmitting'  the  disease.  Jeanselme  and  Laurans 
(1895),  Oerber  (1901),  Werner  (1902),  Sheroux  (1903),  and  others 
have  shown  the  frequency  with  which  tlie  hacilli  of  leprosy  appear  in 
the  nasal  secretions  and  the  importance  of  the  nose  as  a  site  of  leprous 
lesions.  Sticker  cites  a  five-year-old  child  of  leprous  parents  seen  by 
him  in  India  with  an  \ilier  on  the  right  side  of  the  nasal  septum  which 
contained  lepra  bacilli  and  was  the  oidy  lesion  of  the  disease  present  in 
the  case.  Plumert  (1903)  mentions  the  finding  of  lepra  bacilli  in  the 
nasal  secretions  of  persons  in  intimate  family  contact  with  advanced 
cases  of  leprosy.  The  individuals  in  question  showed  no  other  evidence 
of  the  disease.  Falkao  observed  epistaxis  associated  with  small  ulcers 
on  the  nasal  septum  of  descendants  of  lepers,  and  lepra  bacilli  were 
found  in  the  crusts  from  these  ulcers.  The  results  of  Sticker,  Plumert, 
and  Falkao  would  indicate  that  in  the  early  stages  of  the  disease  the  nose 
is  frequently  the  site  of  a  lesion  discharging  lepra  bacilli.  Brinckerhoff 
and  Moore,  however,  who  made  a  careful  study  of  this  question  in 
Honolulu,  point  out  that  most  of  the  studies  upon  the  importance  of 
the  nose  in  leprosy  have  been  made  upon  relatively  advanced  cases  of 
the  disease.  They  found  the  nose  frequently  the  seat  of  infection  when 
the  disease  is  well  developed,  but  practically  never  as  a  primary  or 
incipient  lesion.  If  the  nose  were  the  usual  seat  of  the  primary  lesion 
in  leprosy,  it  might  indicate  that  the  infection  is  carried  there  upon 
the  finger. 

Holmann  studied  500  persons  in  the  Hawaiian  Islands  suffering  with 
a  recognizable  form  of  leprosy  for  periods  varying  from  three  months  to 
twenty-five  years,  and  found  410  with  lesions  of  the  nasal  mucous  mem- 
brane and  only  90  in  which  such  lesions  were  absent. 

Bearing  upon  the  contagiousness  of  leprosy  we  have  Kitasato's  statis- 
tics from  Japan  showing  that  the  children  of  lepers  become  leprous 
in  a  proportion  of  only  7.05  per  cent,  of  the  total.  Matrimonial  infection 
was  proved  in  3.8  per  cent,  of  cases,  while  persons  living  under  the 
same  roof  showed  a  proportion  of  only  2.7  per  cent.  Brothers  and  sisters 
infect  each  other  in  a  ratio  of  4.2  per  cent.  These  figures  roughly  corre- 
spond to  Sand  and  Lies'  studies  in  Norway.  It  is  a  common  observa- 
tion that  elderly  persons  are  less  likely  to  become  infected  with  the  dis- 
ease than  young  persons. 

Jeanselme  ^^  reports  observations  confirming  the  Chinese  and.  Jap- 
anese belief  that  leprosy  spreads  largely  by  sexual  contact.  Jeanselme 
found  "leprous"  urethritis  set  up  by  lepromata  which  invaded  the 
navicular  fossa.  He  further  states  that  myriads  of  acid-fast  bacilli  may 
be  found  in  a  drop  of  pus  which  may  be  squeezed  from  the  meatus 
under  this  condition. 

It  is  sufficient  for  practical  prevention  to  know  that  leprosy  is  spread 

^^  Bull,  de  la  Societe  de  Medecine  Exotique,  No.  7,  1914. 


418  MISCELLANEOUS  DISEASES 

mainly  by  direct  contact  and  perhaps  occasionally  by  indirect  contact 
with  persons  suffering  with  the  disease.  In  a  case  observed  in  northern 
Germany  one  girl  directly  and  indirectly  infected  28  people.  Leprosy  is 
most  prevalent  under  conditions  of  personal  and  domestic  uncleanliness 
and  overcrowding,  especially  where  there  is  close  and  protracted  associa- 
tion between  the  "clean"  and  the  "unclean."  There  are  instances  on 
record  in  which  persons  have  contracted  the  infection  after  a  stay  of 
only  a  day  or  two  in  a  leprous-ridden  area.  There  is  no  evidence  that 
leprosy  is  inherited.  Children  born  of  leprous  parents  do  not  as  a  rule 
develop  the  disease  if  removed  at  once.  The  occurrence  of  several  cases 
in  a  single  family  is  doubtless  due  to  "contact."  The  danger  of  infection 
from  leprous  persons  is,  of  course,  greater  when  there  is  a  discharge  from 
the  lesions  of  the  skin  and  mucous  membranes. 

Prevention. — The  prevention  of  leprosy  depends  almost  entirely 
upon  isolation,  care  of  the  infected  discharges,  personal  cleanliness,  and 
sanitary  surroundings.  The  disease  is  transmitted  with  difficulty;  how- 
ever, doctors,  nurses,  sisters  of  charity,  ward  tenders,  and  others  directly 
exposed  in  leprosaria  sometimes  become  infected.  Notable  examples  have 
been  Father  Damien  at  Molokai,  Hawaii,  Father  Bogliolo  in  New  Or- 
leans, Sir  George  Turner  in  Pretoria,  and  Miss  Mary  Eeed  in  India. 
About  5  per  cent,  of  the  healthy  consorts  of  lepers  become  infected  at  the 
Hawaiian  settlement.  Evidently  close,  prolonged  and  intimate  contact 
is  ordinarily  necessary  to  contract  the  infection. 

For  the  control  of  leprosy  the  most  important  administrative  meas- 
ure is  to  segregate  the  lepers  in  settlements  or  asylums.  Segregation 
also  entails  proper  treatment  and  humane  care.  Compulsory  notification 
of  every  case  of  leprosy  should  be  enforced,  if  for  no  other  reason  than 
to  keep  track  of  the  disease  and  to  know  whether  it  is  on  the  increase. 
The  leprosaria  should  be  inviting  and  should  contain  all  modern  im- 
provements for  the  care  and  treatment  of  the  disease.  Leprosy  is  by  no 
means  invariably  fatal.  In  the  United  States,  where  there  are  only  a 
few  hundred  lepers,  the  Government  has  provided  for  the  establishment 
of  a  national  leprosarium  which  is  located  at  Carville,  Louisiana.  To  re- 
quire each  state  to  provide  suitable  accommodations  to  segregate  its  few 
lepers  is  economically  wasteful. 

It  is  claimed  that  the  decrease  in  leprosy  in  Europe  during  the  middle 
ages  was  due  in  large  part  to  the  segregation  of  the  lepers  in  leprosaria, 
which  at  one  time  numbered  20,000.  On  the  other  hand,  the  value  of 
segregation  is  disputed  because  many  lepers  were  at  large;  however, 
they  were  not  allowed  in  churches  or  market  places,  and  were  branded 
as  "unclean"  by  a  distinctive  dress  and  were  further  required  to  make 
their  presence  known  by  a  bell  or  clapper.  Great  numbers  of  lepers 
were  swept  away  by  the  bubonic  plague  during  these  times.  As  a  rule, 
only  the  advanced   cases  are   detected   and   isolated.     In   some   of  the 


LEPROSY  419 

British  colonies  in  South  Africa,  where  only  about  half  of  the  leper 
population  is  segregated,  the  rate  of  admission  has  remained  constant 
for  the  last  ten  years.  Segregation  in  the  Hawaiian  Islands  and  the 
Philippines  probably  has  so  far  had  no  conspicuous  effect  upon  the  preva- 
lence of  the  disease;  the  results  are  the  subject  of  controversy.  There 
are  factors  in  the  control  of  Icpro^^y  not  yet  understood.  As  soon  as  a 
country  becomes  well  to  do  and  adopts  the  daily  tidiness  incident  to 
modern  civilized  life,  leprosy  dies  out. 

There  can  be  little  objection  in  a  country  such  as  ours,  where  leprosy 
shows  slight  tendency  to  spread,  to  give  a  clean  leper  his  freedom, 
except  in  the  endemic  foci  in  the  Gulf  States  and  elsewhere.  There 
is  no  more  danger  from  a  leprosy  patient  with  clean  personal  habits, 
who  exercises  care  concerning  the  discharges  from  the  lesions,  than 
there  is  from  an  open  case  of  tuberculosis  of  the  glands  of  the  neck. 
The  purely  nerve  cases,  particularly  if  there  are  no  ulcerations,  may 
properly  be  given  a  greater  degree  of  liberty  than  those  with  nodular 
manifestations. 

The  national  quarantine  regulations  forbid  the  landing  of  an  alien 
leper.  The  law  requires  that  such  person  be  deported  on  the  same  ves- 
sel that  brought  him.  A  citizen  of  the  United  States  having  leprosy 
cannot  be  debarred.  Such  individuals  are  admitted  and  then  come  un- 
der the  health  laws  of  the  state  or  port  of  entry. 

Specific  Prevention. — There  is  no  specific  prevention  or  cure  for 
leprosy.  Surgical  cleanliness  and  frequent  dressings  help  check  the 
spread  of  the  infection.  Nastin  is  a  substance  proposed  by  Deycke  and 
consists  of  a  neutral  fat  obtained  from  a  streptothrix.  The  reports  from 
its  use  are  not  particularly  encouraging.  Eost,  of  Rangoon,  Burma, 
uses  a  substance  which  he  calls  "leprolin,"  a  precipitate  from  leprous 
tubercles.  A  large  proportion  (75  to  80  per  cent.)  of  lepers  give  a 
positive  Wassermann  reaction  (independent  of  syphilis),  but  not  the 
luetin  reactions.  Tuberculin  in  somewhat  large  doses  injected  subcu- 
taneously  into  leprous  patients  produces  both  a  general  and  local  reac- 
tion, but  the  repeated  injections  do  not  materially  influence  the  dis- 
ease, although  such  treatment  seems  to  cause  a  local  improvement  or 
softening  of  the  leprous  tubercles.  Heiser,  in  Manila,  reports  favorable 
local  results  from  the  application  of  X-rays.  Chaulmoogra  oil  and 
Gurjun  balsam  have  been  extensively  used.  Rogers,  in  India,  has  re- 
cently reported  encouraging  results  from  the  subcutaneous  and  intra- 
venous use  of  gynocardate  of  sodium,  a  derivative  of  chaulmoogra  oil. 
McDonald  and  Dean  ^^  in  Hawaii  have  reported  good  results  from  ethyl 
esters  of  chaulmoogra  oil.  Many  observers  report  improvement  from 
good  food,  fresh  air,  cleanliness,  and  the  general  principles  applicable 
to  the  modern  treatment  and  prevention  of  tuberculosis. 

^Public  Health  Reports,  No.  34,  XXXV,  1919. 


420  MISCELLANEOUS  DISEASES 

In  appraising  the  influence  of  treatment  it  must  be  borne  in  mind 
that  leprosj'-  is  prone  to  prolonged  periods  of  quiescence  and  that  marked 
improvement  often  occurs  spontaneously,  and  indeed  that  this  may  go 
on  to  apparent  cure. 

REFERENCES 

Bertarelli,  E.  :     Centralbl.  f.  Bakt.,  etc.     1  Abt.  Eef.,  1911,  Bd.  49,  No.  3, 

p.  65  [good  review  and  long  list  of  references]. 
Hansen  :     Virchow's  Archiv,  1882,  Bd.  XC,  p.  542  [original  description  of 

the  bacillus]. 
Kedrowski,  W.  J. :    Centralbl.  f.  Bakt,  etc.    1  Abt.  Eef.,  1911,  No.  50,  p. 

143  [Diphtheroid  bacillus]. 
Lepra.    A  journal  containing  everything  upon  the  subject.    Published  since 

March,  1900. 
Marchoux  and  Sorel.     (Eat  Leprosy)  :    Ann.  de  I'Inst.  Pasteur,  1912,  Vol. 

xxvi,  Nos.  9  and  10. 
Public  Health  Bulletins :    Studies  on  Leprosy,  U.  S.  Public  Health  Service, 

Washington,  D.  C. 


SECTION  n 

MENTAL  HYGIENE 
V>Y  Thomas  W.  Salmon,  M.D. 

Medical  Director,  National  Committee  for  Mental  Hygiene;  formerly 

Passed  Assistant  Surgeon,  U.  S.  Public  Health  Service;  formerly 

Chairman,   New    York    State   Board    of   Alienists. 

A  very  few  years  ago  it  would  liave  been  difficult  to  justify  the  in- 
clusion of  a  chapter  on  mental  hygiene  in  a  general  treatise  on  preventive 
medicine  and  hygiene.  The  medico-legal  term  "insanity"  was  nsed  to 
designate  all  abnormal  mental  states  and  the  incorrect  conception  of 
mental  and  physical  diseases  as  distinct  and  practically  unrelated  was 
widely  accepted.  These  misconceptions  and  the  hopelessness,  both  as 
to  cure  and  prevention,  which  characterized  the  medical  attitude  toward 
mental  diseases  combined  to  disassociate  mental  medicine  and  its  prob- 
lems from  the  subjects  which  were  engaging  the  attention  of  physicians 
and  sanitarians  generally.  There  seemed  little  likelihood  that  the  de- 
termination to  prevent  diseases  w^hich  was  beginning  to  dominate  the 
medical  profession  would  soon  extend  into  the  domain  of  mental  medi- 
cine. Today,  however,  a  treatise  on  the  prevention  of  disease  which  failed 
to  include  a  chapter  on  mental  hygiene  would  neglect  an  important  field 
of  preventive  medicine.  The  realization  that  many  forms  of  mental  dis- 
ease depend  in  a  large  measure  upon  preventable  causes,  the  rapid  growth 
of  psychiatry  and  its  acceptance  as  a  department  of  scientific  medicine, 
and  the  newly  discovered  opportunities  for  utilizing  its  resources  in  prac- 
tical attempts  to  deal  with  social  problems  have  broken  down  the  barriers 
which  so  long  and  so  effectually  isolated  mental  medicine. 

It  is  not  easy  to  present  even  the  main  facts  of  mental  hygiene 
within  the  limits  of  a  single  chapter,  for  it  is  not  sufficient  to  discuss 
some  of  the  more  important  preventable  or  modifiable  causes  of  mental 
diseases  and  mental  deficiency  and  to  outline  some  of  the  means  which 
may  be  employed  in  their  control.  Hygiene  deals  with  measures  which 
promote  health  as  well  as  with  the  prevention  of  disease  and  it  is  neces- 
sary, in  any  useful  presentation  of  the  essentials  of  mental  hygiene, 
to  consider  to  what  extent  some  of  the  mental  factors  which  interfere 

*  In  the  first  edition  this  chapter  was  called  "The  Prevention  of  Mental  Dis- 
eases," but  the  prevention  of  mental  diseases  is  a  relatively  small  part  of 
the  field  of  mental  hygiene.  Tlierefore.  in  this  edition  both  the  title  and  the 
scope  of  this  chapter  have  been  changed  to  "Mental  Hygiene." 

421 


422  MENTAL  HYGIENE 

with  the  successful  adaptation  of  the  individual  to  the  environment  can 
be  favorably  modified.  It  is  clearly  within  the  sphere  of  mental  hygiene 
to  strive  to  prevent  those  failures  of  adaptation  which,  while  they  may 
never  bring  about  the  graver  disturbances  of  adjustment  which  we  term 
mental  diseases  (psychoses),  may,  nevertheless,  distort  the  life  and  pro- 
foundly impair  the  efficiency  and  happiness  of  the  individual. 


THE  PROBLEMS  OF  MENTAL  HYGIENE 

Nmnber  of  Insane  and  Mental  Defectives. — On  January  1,  1920, 
there  were  232,680  ^  patients  with  mental  diseases  in  hospitals  for  the 
insane  in  this  countr3\  If  the  number  on  parole  from  these  hospitals 
is  included,  the  total  number  of  patients  with  mental  diseases  under 
supervision  of  these  hospitals  on  that  date  was  over  250,000 — a  num- 
ber almost  equal  to  the  number  of  students  in  all  the  colleges  and  uni- 
versities in  the  United  States,  and  exceeding  the  population  of  Toledo, 
Ohio,  our  twent3^-sixth  city  in  size.  This  great  number  by  no  means 
included  all  persons  with  mental  diseases  in  this  country  or  even  the 
number  who  would  have  been  receiving  treatment  in  hospitals  on  Janu- 
ary 1,  1920,  had  all  the  states  supplied  adequate  provisions.  We  know 
that  the  ratio  of  persons  with  mental  diseases  to  the  whole  population 
is  about  the  same  in  different  parts  of  the  country,  for  wherever  suf- 
ficient institutional  provisions  ezist  they  are  utilized  to  very  much  the 
same  extent.  If,  therefore^  all  the  states  provided  for  the  insane  as 
adequately  as  do  Massachusetts  and.  New  York,  there  would  have  been 
more  than  350,000  patients  in  institutions  on  January  1,  1920,  instead 
of  232,680.  The  cost  of  caring  for  mental  diseases  in  a  state  which 
makes  adequate  provisions  exceeds  any  single  item  of  expense  except 
that  for  public  education.  The  average  annual  cost  of  caring  for  a 
patient  in  a  state  hospital  for  the  insane  is  about  $250,  making  the 
total  yearly  cost  of  caring  for  the  200,000  patients  under  treatment  in 
state  hospitals  alone  more  than  $50,000,000.  To  this  great  sum  should 
be  added,  if  we  are  to  state  fairly  the  cost  of  mental  diseases,  the 
economic  loss  through  the  withdrawal  from  active  life  of  more  than 
60,000  people  who  enter  these  hospitals  each  year. 

No  one  can  state  the  number  of  the  mentally  defective  in  this  coun- 
try or  even  the  number  requiring  institutional  care.  Massachusetts,  the 
state  which  has  supplied  institutional  provisions  most  liberally,  has 
one  bed  to  every  1,248  of  the  general  population  for  such  sufferers.^  If 
this  ratio  existed  in  every  state  there  would  be  84,682  mental  defectives 

'Pollock,  H.  M.,  and  Furbush,  Editli  M. :  "Patients  with  Mental  Disease, 
Mental  Defect,  Epilepsv,  Alcoholism  and  Drug  Addiction  in  Institutions  in  the 
United  States,  January  1,  1920."     Mental  Hygiene,  V,  Jan.,  1921. 

'Not  including  epileptics. 


THE  PROBLEMS  OF  MENTAL  HYGIENE  423 

in  state  institutions  at  tho  present  time.  Actually  there  are  approxi- 
mately 35,000.*  We  know,  however,  that  even  in  the  state  which  has 
made  the  most  liberal  provisions  there  are  many  mentally  defective 
persons  xmeared  for  and  many  who  are  improperly  confined  in  correc- 
tional institutions  or  in  almshouses.  There  is  reason  to  believe  that 
there  arc  no  less  than  four  mentally  defective  persons  in  every  thousand 
of  the  whole  population.  Although  their  cost  to  the  communities 
through  their  own  dependence,  the  support  of  their  illegitimate 
children,  and  the  crimes  and  misdemeanors  which  they  commit,  or 
more  frequently  invite,  cannot  be  estimated,  we  know  that  it  is  more 
even  than  the  great  co?t  of  caring  for  them  in  suitable  institutions 
would  be. 

Scope  of  Subject. — Such  statistics  as  these  serve  as  a  convenient 
means  for  comparing  the  cost  of  mental  diseases  and  mental  deficiency 
with  that  of  other  diseases,  but  they  cannot  convey  an  adequate  idea 
of  the  personal  suffering  and  unhappiness  and  the  social  and  family  dis- 
asters for  which  mental  disorders  are  directly  responsible.  It  should  be 
remembered  that  the  same  causes  which  bring  about  the  commitment 
of  many  thousands  of  persons  as  "insane"  each  year  are  responsible  for 
much  mental  disease  which  is  never  recognized  and  for  many  failures 
in  adaptation  which  prevent  people  from  meeting  difficult  situations  in 
life  and  which  lead  to  innumerable  conflicts  with  laws  and  conventions. 
To  avert  some  of  these  disasters  is  as  much  the  task  of  mental  hygiene 
as  to  control  the  preventable  causes  of  mental  disease  and  of  mental  de- 
ficiency. With  these  considerations  in  mind,  some  of  the  causes  of 
mental  diseases,  mental  deficiency,  and  other  abnormal  mental  states 
will  be  briefly  stated.  ]\Ieasures  of  prevention  which  seem  applicable  will 
be  considered  while  discussing  each  cause,  and  the  more  general  causa- 
tive conditions  and  more  general  measures  for  preventing  mental  disease 
and  promoting  mental  hygiene  will  he  taken  up  last. 

Definitions. — In  the  pages  which  follow,  the  term  psychoses  refers  to 
mental  diseases,  or  "forms  of  insanity"  as  they  are  more  familiarly  but 
less  accurately  called.  Dr.  William  A.  Wliite  has  pointed  out  the  enor- 
mous advantages  of  restricting  the  use  of  the  term  "insane''  to  that 
group  of  persons  who  suffer  from  civic  disabilities  of  one  kind  or  another 
(commitment  to  institutions,  testamentary  incapacity,  incompetency  to 
use  property,  etc.)  because  of  legal  proceedings  necessitated  by  mental 
diseases. 

Insanity  thus  becomes  a  strictly  legal  term,  with  which  physicians 
and  sanitarians  are  concerned  only  when  medico-legal  or  certain  social 
phases  of  mental  diseases  are  under  consideration.     Persons  with  mental 

*  Pollock,  H:  M.,  and  Furbush,  Edith  'SI.:  •'•'Patients  with  Mental  Disease, 
Mental  Defect,  Epilepsy,  Alcoholism,  and  Drug  Addiction  in  Institutions  in  the 
United  States,"  January  1,  1920.     Mental  Hygiene,  V,  Jan.,  1921. 


424  MENTAL  HYGIENE 

disease  may  or  may  not  be  "insane/'  The  term  insanity  will  be  used 
here  only  in  this  medico-legal  sense. 

The  term  mental  deficiencij  will  be  used  to  designate  the  various 
types  and  degrees  of  mental  defect  (idiocy,  imbecility,  feeble-mindedness, 
psychopathic  inferiority,  etc.)  existing  at  birth  or  arising  during  the 
early  period  of  development. 

The  term  psycJioneuroses  will  be  used  to  designate  the  group  of 
functional  nervous  diseases  that  includes  neurasthenia,  hysteria,  anxiety 
states  and  various  conditions  loosely  designated  by  the  laity  as  "nervous 
breakdowns." 

It  is  not  possible  to  find  a  single  word  with  which  to  designate  those 
minor  interferences  with  mental  health  or  with  mental  efficiency  which 
underlie  many  such  difficulties  of  adaptation  as  those  which  have  been 
mentioned. 

HEREDITY 

Psychoses. — The  accepted  theories  of  heredity  and  the  general  re- 
lation of  heredity  to  disease  have  been  considered  elsewhere  (Section  lY. 
Chapters  II  and  III,  page  607).  In  examining  the  relation  of  hered- 
ity to  mental  diseases,  the  advantage  of  dropping  the  use  of  the  medico- 
legal term  "insanity"  is  apparent,  for  statistical  studies  indicate  that 
in  some  mental  diseases  heredity  is  a  factor  of  the  utmost  importance, 
while  in  others  it  apparently  influences  causation  very  little  if  at  all. 

Eosanoff  and  Orr  ^  concluded  from  a  study  of  inheritance  in  73  cases 
of  mental  diseases,  representing  206  different  matings  and  1,097  off- 
spring, that  this  common  basis,  which  they  designated  the  "neuropathic 
constitution,"  is  inherited  in  accordance  with  Mendel's  law.  They  be- 
lieved the  neuropathic  constitution  to  be  a  trait  which  is  recessive  to 
the  normal  and,  furthermore,  that  various  clinical  neuropathic  manifesta- 
tions bear  to  each  other  the  relationship  of  traits  of  various  degrees  of 
the  recessive;  that  is  to  say,  neuropathic  traits  which  are  recessive  com- 
pared with  normal  traits  are  at  the  same  time  dominant  over  other  neuro- 
pathic traits.  The  degree  to  which  neuropathic  traits  are  recessive  seemed 
to  Eosanoff  and  Orr  to  conform  in  general  to  the  severity  of  the  type 
of  psychosis  or  neurosis.  Unfortunately,  these  findings  alone  are  not 
sufficient  evidence  upon  which  to  base  general  conclusions  as  to  the  rela- 
tion between  heredity  and  mental  diseases.  The  study  of  the  inheritance 
of  mental  diseases  presents  many  complex  problems  and  many  special  dif- 
ficulties, not  the  least  of  which  is  that  the  field  work  upon  which  it  de- 
pends so  greatly  cannot  be  entrusted  to  workers  who  have  not  had  psychi- 
atrical training.    Dr.  E.  Eiidin  of  Munich  has  made  very  careful  studies 

"Eosanoff,  A.  J.,  and  Orr,  Florence  T. :  "The  Study  of  Heredity  in  Insanity 
in  the  Light  of  the  Mendelian  Theory.     Bulletin  Wo.   V,  Eugenics  Record  Office. 


HEEEDTTY  425 

of  inheritance  in  mental  diseases,  his  investigations  being  particularly 
valuable  because  he  performed  the  actual  field  work  himself.  In  a 
communicition  summing  up  his  findings  from  1909  to  1911,  he  stated  ° 
that  he  felt  that  he  had  not  done  enough  work  to  justify  the  formulation 
of  laws  regarding  the  hereditary  factors  of  mental  diseases.  Scientific 
study  of  this  subject  is  being  carried  on  actively  and  it  seems  desirable, 
at  the  present  time,  to  reserve  judgment  as  to  the  conflicting  findings 
which  are  being  presented.'^ 

If  the  precise  part  played  by  inheritance  in  the  causation  of  mental 
diseases  cannot  be  stated,  it  should  not  be  thought  that  evidence  is 
lacking  to  show  its  importance.  It  is  probably  safe  to  say  that  heredity 
is  Tesponcible,  directly  and  indirectly,  for  more  cases  of  mental  disease 
than  any  other  single  cause.  In  about  50  per  cent,  of  all  admissions  to 
hospitals  in  which  careful  records  are  made  and  scientific  study  of 
cases  is  carried  on,  the  history  of  mental  diseases  in  other  members 
of  the  family  is  found.  There  are  no  statistics  in  this  country  to  show 
the  percentage  of  normal  persons  in  whose  families  the  histor}^  of  mental 
disease  is  found,  but  studies  elsewhere  have  shown  it  to  be  from  3  to 
7.5  per  cent. 

Effect  of  Environment. — ISTeuropathic  heredit}^  exercises  powerful 
indirect  influences  through  the  unfavorable  environmental  influences  in 
which  the  children  of  psychotic  parents  are  compelled  to  spend  their 
developmental  years.  Distorted  views  of  life,  queer  religious  and  po- 
litical beliefs  and  various  antisocial  attitudes  on  the  part  of  such  parents 
mold  the  mental  reactions  of  their  children  and  even  when  no  direct 
hereditary  tendency  is  transmitted  such  children  suffer  through  having 
their  education  interfered  with  and  their  capacity  for  social  adjustment 
restricted.  In  some  cases  they  acquire  and  firmly  hold  false  beliefs 
which,  on  the  part  of  their  parents,  were  actually  delusional. 

Mental  Deficiency. — In  mental  deficiency  we  have  one  of  the  best 
examples  of  a  pathological  condition  directly  transmitted  by  inheritance. 
Although  the  same  type  of  neuropathic  heredity  which  is  met  so  often 
in  the  psychoses  is  found  more  frequently  in  the  mentally  defective 
than  in  normal  persons,  mental  deficiency  depends  chiefly  upon  a  more 
specific  kind  of  inheritance — the  direct  transmission  of  the  same  condi- 
tion. Goddard  ^  found,  in  300  family  histories  in  which  the  data  were 
regarded  as  satisfactory,  that  54  per  cent,  showed  mentally  defective 
relatives  "in  such  numbers  or  in  such  relations  to  the  individual  case 
studied  as  to  leave  no  doubt  of  the  hereditary  character  of  mental  defect." 

^Riidin,  E. :  Zeitschriff  filr  die  Gesammte  Neurologic  und  Psi/cTiiatrie,  Vol. 
7,  Part  5,  November  IS,  1911. 

'  The  reader  who  is  interested  in  this  phase  of  mental  hygiene  will  find  an 
excellent  bibliography,  after  Riidin,  in  "Some  Problems  in  the  Study  of  Heredity 
in  INIental  Disease"  bv  Dr.  H.  A.  Cotton.  American  Journal  of  Insanity,  July, 
1912. 

'Goddard,  H.  H.:      "Feeblemindedness,"  1915,  p.  436. 


426  MENTAL  HYGIENE 

He  considered  11.3  per  cent,  of  the  remaining  cases  in  this  series  as 
"^probably  hereditary."  Other  studies  liave^  unfortunately,  grouped 
mental  deficiency,  mental  diseases  and  epilepsy  in  estimating  the  heredi- 
tary factors  in  mental  deficiency.  Tredgold  ^  found,  in  a  series  of  200 
cases  in  which  he  very  carefully  investigated  the  family  histories,  that 
64.5  per  cent,  had  m.ental  deficiency,  mental  diseases,  or  epilepsy  in  their 
ancestry.  Lapage  ^^  found  the  same  conditions  in  the  families  of  48.4 
per  cent,  of  the  children  in  the  special  schools  of  Manchester,  and 
Potts  ^^  found  45.6  per  cent,  in  the  families  of  children  in  similar  schools 
in  Birmingham. 

In  Tredgold's  series  of  200  cases,  a  marked  predisposition  to  paral- 
ysis, cerebral  hemorrhage  and  various  neuroses  existed  in  18  per  cent., 
making  the  proportion  in  which  either  a  mentally  defective  or  neuro- 
pathic heredity  was  found  82.5  per  cent.  Goddard  found  epilepsy, 
insanity,  blindness,  and  deafness  (which  he  grouped  under  the  term 
^'neuropathic  ancestry")  in  12  per  cent,  of  his  series.  It  is  most  un- 
fortunate that  different  methods  of  grouping  neuropathic  conditions 
should  be  employed  by  different  investigators,  for  it  makes  it  impossible 
to  compare  their  results.  It  is  also  unfortunate  that  widely  different 
conditions  should  be  included  in  the  same  group.  Certainly  blindness 
and  insanity  must  represent  very  different  types  of  heredity  in  God- 
dard's  cases,  while  cerebral  hemorrhage  and  the  neuroses  are  equally 
incongruous  members  of  the  same  group  in  Tredgold's  series. 

There  is  need  for  much  more  intensive  study  of  heredity  in  mental 
deficiency,  especially  in  those  cases  in  which  neuropathic  inheritance 
and  not  mental  deficiency  is  found  in  the  progenitors.  Even  in  the 
large  proportion  of  cases  in  which  mental  deficiency  seems  to  be  trans- 
mitted directly,  it  is  desirable  to  know  the  relation  of  heredity  to  the 
different  types  and  grades  of  mental  deficiency.  As  a  step  in  this  direc- 
tion, Goddard  has  pointed  out  that  his  series  seemed  to  indicate  that 
low-grade  cases  come  from  families  with  the  least  amount  of  mental 
defect.  In  the  interpretation  of  this  interesting  fact,  the  barriers  to 
reproduction  which  exist  among  low-grade  defectives,  their  high  mor- 
tality rate  before  puberty  and  the  excessive  prevalence  among  them 
of  severe  organic  lesions  of  the  brain,  many  of  them  accidental  or 
syphilitic,  must  be  taken  into  account. 

The  relation  of  heredity  to  mental  deficiency  is  a  matter  of  the 
greatest  importance  on  account  of  its  bearing  upon  prevention.  The 
general  fact  that  mental  deficiency  depends  chiefly  upon  inheritance 
having  been  well  established,  it  seems  most  essential  now  to  study 
heredity  specifically,  as  we  do  in  the  psychoses — that  is,  with  reference 

»  Tredgold,  A.  F.:     "Menfal  Deficiency,"  1914,  p.  40. 

^"Lapage,  C.  P.:     "Feeblemindedness  in  Children,"  1911. 

"Potts,  W.  A.:     British  Journal    of  Children's  Diseases,  March,  1909. 


HEREDITY  437 

to  particular  types  and  grades.  If  the  judicial  authorities  are  to  be 
asked  to  commit  a  mentally  defective  person  to  an  institution  for  life 
solely  because  of  the  danger  of  transmitting  his  defect  to  others,  they 
have  a  right  to  ask  Avhat  is  known  beyond  reasonable  doubt  regarding 
the  hereditary  factors  in  that  particular  case  and  in  that  particular  type 
of  mental  deficiency.  Tt  is  quite. certain  that  they  will  look  with  sus- 
picion Tipon  long-distance  diagnoses  by  inexpert  investigators  and  yet  it  is 
ii})()ii  precisely  that  kind  of  diagnosis  that  much  of  the  information 
which  we  are  making  widely  known  today  depends.  In  determining  the 
heredity  of  a  given  case  much  depends  npon  establishing  the  existence 
of  mental  defect  in  many  living  persons  not  in  institutions  and  in  others 
long  since  dead.  Many  field  workers  engaged  in  such  studies  are  poorly 
equipped  by  training  to  diagnose  mental  deficiency  even  in  a  formal 
examination,  with  all  the  aids  available  for  such  work,  and  some  of  them 
are  quite  inexperienced  in  estimating  the  significance  of  various  types 
of  antisocial  conduct.  It  has  been  said  in  justification  of  some  rather 
questionable  findings  of  snch  workers  that  physicians  conclude  upon 
evidence  "infinitely  weaker"  that  Napoleon,  Julius  Cassar,  and  Saint 
Paul  were  epileptics.  Without  considering  the  striking  outward  manifes- 
tations of  epilepsy,  it  should  be  said  that  extensive  medical  notes  by 
Napoleon's  physicians  are  in  existence  and  that  the  data  regarding 
Julius  Caesar  upon  which  the  existence  of  epilepsy  is  assumed  are  not 
much  less  trustworthy  than  those  available  regarding  some  obscure 
feeble-minded  persons  who  died  fifty  or  more  years  ago.  It  is  to  be  re- 
membered, however,  that  the  diagnoses  of  the  maladies  of  great  his- 
torical characters  which  are  offered  from  time  to  time  by  physicians  are 
presented  merely  as  interesting  surmises,  not  as  scientific  data  upon 
which  to  base  an  extensive  program  of  legislation  and  institutional 
provision. 

It  is  of  much  practical  importance,  with  reference  to  prevention,  to 
know  if  hereditary  mental  deficiency  is  transmitted  in  accordance  with 
definite  laws.  Goddard's  investigations  showed  a  correlation  between  the 
actual  findings  and  the  proportion  of  mental  defectives  which,  theoret- 
icall}^,  should  occur  in  the  324  matings  of  different  tj^pes  in  his  series  if 
mental  deficiency  is  transmitted  in  accordance  with  Mendel's  law  to 
justify  him  in  saying  that  "such  results  are  difficult  to  account  for  on 
any  other  basis  than  that  feeble-mindedness  is  transmitted  in  accord- 
ance with  the  Mendelian  formula." 

The  part  played  by  heredity  in  the  production  of  the  psychoneuroses 
is  not  very  clearly  established.  An  important  contribution  to  the  sub- 
ject was  made  by  Dr.  Julian  M.  Wolf  son  ^^  who  ascertained  that  a  neuro- 
pathic heredity  existed  in  10  per  cent,  of  a  group  of  100  British  soldiers 

"  Wolf  sohn,  Julian  M. :  "The  Predisposing  Factors  of  War  Pyschoneuroses," 
The  Lancet,  Feb.  2,  1918. 


428  MENTAL  HYGIENE 

in  the  Fourth  London  General  Hospital  who  were  suffering  from  wounds 
and  in  72  per  cent,  of  a  group  of  100  soldiers  in  another  department  of 
the  same  hospital  who  were  suffering  from  war  neuroses.  In  the  psycho- 
neuroses  in  civil  life  it  is  certain  that  a  neuropathic  heredity  is  more 
commonly  found  than  among  persons  who  do  not  suffer  from  these  dis- 
orders, but  there  are  many  individuals  who  suffer  severely  from  various 
psychoneurotic  difficulties  whose  parents  and  brothers  and  sisters  ap- 
parently have  no  such  disorders. 

Preventive  Measures. — This  is  the  domain  of  eugenics,  a  subject 
which  is  considered  elsewhere  in  this  volume  (Section  lY,  Chapter  II). 
In  considering  measures  for  controlling  the  inheritance  of  the  neuro- 
pathic constitution  the  caution  contained  in  the  following  statement 
by  Adolf  Meyer  ^^  ma)^  well  be  borne  in  mind :  "In  such  a  matter  as  the 
prevention  of  mental  trouble  due  to  heredity,  I  maintain  that,  although 
we  know  that  a  large  percentage  of  mental  cases  have  a  history  of 
heredity,  there  is  not  a  sufficiently  decisive  body  of  facts  established  for 
us  to  be  justified  in  making  sweeping  rules  against  the  marriage  of 
those  who  have  had  mental  troubles  either  themselves  or  in  their  families. 
Indeed,  we  might  thereby  run  the  risk  of  doing  a  grave  injustice  to  the 
race  as  well  as  infringing  on  the  rights  of  the  individual." 

In  the  case  of  hereditary  mental  defect  there  can  be  no  question 
that  the  right  of  the  individual  to  bear  children  must  be  disregarded 
in  the  interests  of  ordinary  humanity  as  well  as  in  the  interests  of  the 
race.  The  questions  of  the  sterilization  and  segregation  of  the  defective 
and  the  regulation  of  marriage  are  considered  elsewhere,  but  it  should 
be  said  here  that  in  not  a  few  mentally  defective  persons  there  is  an 
alternative  to  segregation  in  an  institution  for  life.  It  is  possible 
to  devise  a  system  of  safeguards  which,  with  registration  and  commit- 
ment to  guardianship  if  necessary,  will  make  a  supervised  life  in  the 
community  safe  for  a  very  carefully  selected  number  of  such  indi- 
viduals. The  establishment  of  such  a  system  of  supervision  and  registra- 
tion is  one  of  the  great  constructive  tasks  which  must  be  undertaken  if 
we  are  to  deal  with  the  problem  of  the  mentally  defective  in  the  most 
humane  and  effective  manner  possible. 

Few  people  would  care  to  say  that  persons  having  psychoneurotic 
disorders  should  not  marry,  or,  if  they  do  marry,  should  refrain  from 
having  children,  and  yet  it  would  be  certainly  wise  for  a  physician,  if 
consulted,  to  advise  against  the  marriage  of  two  persons  both  of  whom 
had  had  important  psychoneurotic  episodes  or  who  showed  evidence  of 
psychoneurotic  make-up. 

"Meyer,  Adolf:  "Organizing  the  Community  for  the  Protection  of  Its  Men- 
tal Health."     The  Survey,  September  18,  1915. 


ALCOHOL  429 


ALCOHOL 


Psychoses. — in  tliscussiug  alculiul  as  a  cause  of  mental  disease  it 
is  very  desirable  to  indicate  whether  it  is  being  considered  as  a  direct 
cause  or  as  one  of  several  etiological  factors.  Alcohol  is  the  essential 
cause  of  the  alcoholic  psychoses,  those  mental  diseases  which  from 
their  symptoms,  pathology,  or  course  we  have  come  to  recognize  as 
due  directly  to  alcohol,  Li  these  disorders — Korsakow's  disease,  alcoholic 
hallucinosis,  delirium  ireinens,  alcoholic  deterioration — to  diagnose  the 
condition  is  to  know  the  cause.  Other  causes,  such  as  trauma  and  dis- 
orders of  nutrition,  doubtless  contribute  in  many  cases  and  in  a  very 
large  proportion  of  cases  the  neuropathic  constitution  underlies  the  habit 
of  alcoholism,  but  whatever  other  mental  diseases  these  patients  might 
some  time  have,  they  could  not  develop  these  particular  psychoses  with- 
out the  intemperate  use  of  alcohol. 

The  alcoholic  psychoses  account  for  about  4  per  cent,  of  all  first  ad- 
missions to  hospitals  for  the  insane.  They  occur  about  three  times  as 
frequently  in  men  as  in  women  and,  in  general,  more  frequently  in  ad- 
missions from  cities  than  from  rural  districts.  This  difference  in  the 
environment  of  admissions  for  alcoholic  psychoses  is  much  more  striking 
in  the  case  of  women  than  in  men.^* 

It  is  difficult  and  perhaps  impossible  to  estimate  the  influence  of 
alcohol  in  the  causation  of  other  psychoses.  Of  the  cases  in  which  a 
satisfactory  history  as  to  alcoholic  habits  was  obtained  in  the  patients 
admitted  to  the  Xew  York  State  hospitals  during  1919,  about  16  per  cent, 
were  intemperate.  Excluding  the  alcoholic  psychoses,  the  prevalence 
of  intemperance  among  the  more  important  psychoses  is  shown  by  the 
following  table : 

Per  Cent. 

Psychoses  Intemperate 

Senile  psychoses  13.0 

General  paresis  23.9 

Psychoses  with  cerebral  arteriosclerosis  15.5 

Dementia  praecox  9.6 

Paranoia  and  paranoid  conditions  12.5 

Epileptic  psychoses  10.8 

Manic-depressive  6.0 

(From   New   York    State   Hospital    Commission    report   for   year    ended    June 
30,  1919.) 

"  There  has  been  a  steady  fall  in  the  percentage  of  admissions  with  alcoholic 
psychoses  during  recent  years.  This  may  be  partly  accounted  for  by  better  dis- 
tribution of  cases  formerly  thought  to  be  alcoholic  psychoses  but  it  is  possible 
that  it  is  due  in  part  to  the  growing  temperance  movement. 


430  MENTAL  HYGIENE 

No  statistics  are  available  to  show  the  extent  of  intemperance  among 
adults  in  the  community  generally;  nevertheless  it  seems  very  likely  that 
it  is  much  less  than  in  even  the  psychoses  shovring  the  least  frequency. 
Many  elements  have  to  be  taken  in  consideration  in  interpreting  these 
percentages,  especially  the  fact  that  defects  in  Judgment  and  relaxation 
of  inhibitions  due  to  mental  disease  lead  to  intemperance,  as  they  do  to 
other  disorders  of  conduct.  It  is  significant,  therefore,  that  general 
paresis  shows  the  highest  percentage  of  intemperance.  The  seclusive- 
ness  of  persons  with  paranoid  tendencies  and  dementia  praecox  and  the 
low  percentage  of  alcoholism  in  these  disorders  may  bear  some  rela- 
tion to  the  influence  of  conviviality  upon  intemperance. 

In  many  individual  cases  there  is  abundant  evidence  that  intemper- 
ance plays  a  prominent  part  in  the  psychoses  which  are  not  primarily 
dependent  upon  alcohol.  The  effects  of  alcohol  in  producing  excited 
episodes  in  the  mentally  defective  is  well  known  and  intemperance 
lends  a  tremendous  impetus  to  the  retrogressive  changes  in  senility.  As 
a  result  of  greatly  increased  attention  being  directed  to  the  alcoholic 
psychoses,  interesting  facts  are  being  brought  out.  It  has  been  shown 
by  Pollock  ^^  in  a  study  of  464  cases  of  the  alcoholic  psychoses  that  the 
average  duration  of  intemperance  before  the  onset  of  the  psychosis  was 
20.6  years.  As  will  be  seen,  this  fact  has  an  important  bearing  upon 
prevention.  It  does  not  seem  amiss  to  point  out  here  the  misleading  im- 
pression which  is  given  by  the  statement  often  made  that  alcohol  is 
"filling  our  hospitals  for  the  insane."  The  alcoholic  psychoses  are  of 
comparatively  short  duration;  the  recovery  rate  is  more  than  50  per 
cent.;  hence  the  number  of  patients  with  these  diseases  under  treat- 
ment at  any  time  is  always  less  than  the  annual  admission  rate  of  these 
diseases.  Such  statements  made  by  enthusiastic  temperance  advocates 
injure  a  splendid  cause  for  the  exaggerated  estimates  given  make  it 
impossible  to  show  the  expected  reduction  in  the  number  of  patients 
in  the  hospitals  of  prohibition  states  after  prohibition  has  gone  into 
effect,  thus  providing  the  enemies  of  prohibition  with  arguments  in 
advocacy  of  license. 

Mental  Deficiency. — Statistics  regarding  alcohol  as  a  cause  of  men- 
tal deficiency  deal  wholly  with  the  influence  which  intemperance  in  the 
parents  is  said  to  exercise.  The  data  available,  while  abundant,  are  very 
unsatisfactory  and  have  to  be  interpreted  with  especial  care  on  account 
of  the  fact  that  the  alcoholic  parents  whose  habits  are  so  often  thought 
to  have  been  responsible  for  mental  deficiency  in  their  children  were 
sometimes  also  mentally  defective  and  in  reality  transmitted  their  defect 
directly.    Tredgold  states  that  a  family  history  of  alcoholism  was  present 

"Pollock,  Horatio  M.:  "The  Use  and  Effect  of  Alcohol  in  Relation  to  the 
Alcoholic  Psychoses."  'New  York  State  Hospitals  Bulletin,  Y,  8,  pp.  264-79, 
August,  1915;  also,  Psychiatric  Bulletin,  Y,  2,  April,  1917. 


ALCOHOL  431 

in  46.5  per  cent,  of  the  scries  of  300  cases  which  he  studied  carefully,  hut 
that  no  loss  than  five-sixths  of  those  cases  with  an  alcoholic  parentage  also 
had  a  well-defined  neuropathic  inheritance.  lie  believes  that  paternal 
or  maternal  alcoholism  may  produce  mental  deficiency  in  the  offspring 
without  other  cause,  but  that  this  is  rare.  In  a  very  interesting  chapter, 
Goddard  discusses  the  alcoholics  (drunkards)  among  the  parents  in  his 
series  of  cases  and  concludes  that  '^everything  seems  to  indicate  that  alco- 
holism itself  is  only  a  symptom,  that  it  for  the  most  part  occurs  in 
families  where  there  is  some  form  of  neurotic  taint,  especially  feeble- 
mindedness." He  points  out  that  if  alcoholism  were  responsible  alone 
for  mental  deficiency  there  would  doubtless  be  much  more  mental 
deficiency  than  there  is,  especially  in  view  of  the  great  prevalence  of 
drunkenness  among  all  classes  only  a  few  generations  ago. 

Intemperance  at  the  time  of  conception  is  popularly  thought  in  many 
countries  to  be  a  cause  of  mental  deficiency.  Analyzing  the  last  Swiss 
census,  Bezzola  pointed  out  that  there  are  two  maximal  periods  in  which 
the  mentally  defective  persons  enumerated  were  conceived — the  time  of 
the  vintage  and  the  time  of  the  Lenten  carnival,  occasions  of  great 
revelry.  In  the  wine  cantons  the  time  of  the  vintage  was  the  time  of 
conception  in  a  great  majority  of  idiots.  Ireland  ^^  examined  the  birth 
dates  of  mentally  defective  children  born  in  certain  villages  in  Scotland 
where  there  is  much  seasonal  drunkenness  to  see  if  their  conception 
dates  bore  a  relation  to  such  periods,  but  was  unable  to  find  any  such 
evidence  as  that  discovered  by  Bezzola.  P.  ISTacke^^  gives  it  as  his 
opinion  that,  while  intoxication  at  the  time  of  conception  may  result  in 
mental  deficiency  in .  the  offspring,  such  an  event  is  extremely  rare. 
This  seems  in  accordance  with  the  biological  facts  of  conception.  The 
extent  of  the  popular  belief  that  some  delinquency  on  the  part  of  the 
parents  is  responsible  for  mental  deficiency  in  their  children  was  im- 
pressed upon  me  while  questioning  the  parents  of  mentally  defective 
immigrants  at  Ellis  Island.  I  had  an  opportunity  to  ask  hundreds  of 
such  parents,  representing  nearly  all  the  European  races,  what  they 
considered  to  be  the  real  cause  of  the  mental  deficiency  of  their  children 
and,  while  many  of  them  gave  all  kinds  of  infantile  accidents  and  very 
few  of  them,  as  might  be  expected,  suggested  hereditary  influence,  a 
considerable  number  said  shamefacedly  that  they  thought  it  was  due  to 
intoxication  at  the  time  of  conception,  to  early  sexual  faults  or  to  failure 
to  obey  the  Hebrew  injunctions  regarding  intercourse  after  marriage. 

Experiments  such  as  those  of  Kraepelin  ^*  in  memory  tests,  type- 
writing and  typesetting  indicate  that  even  very  moderate  drinking  no- 

*«  Ireland,  W.  W.:     "Mental  Affections  in  Childhood,"  1898. 
"Nacke,  P.:     "Die  Zeugung  im  Eausche."     Neurol.  Centralbl.,  No.  2,  1908. 
"  Reported  by  Smith,  A. :     Archiv  fiir  Psychiatrie,  1895.     Aschaffenberg,  G. : 
Psychologische  Arieiten,   1896. 


433  MENTAL  HYGIENE 

ticeably  impairs  mental  efficiency.  These  are  effects  of  alcohol  which 
cannot  be  ignored  in  mental  hygiene.     See  page  489. 

Preventive  Measures. — The  prevention  of  the  alcoholic  psychoses 
and  of  those  mental  diseases  in  which  alcohol  is  a  contributory  etiological 
factor  consists  in  the  control  of  alcoholism  and  the  promotion  of 
temperance.  These  matters  are  not  within  the  scope  of  a  chapter  on 
mental  hygiene.  Like  the  prevention  of  syphilis,  the  control  of  alcoholism 
is  a  great  social  question.  The  medical  man  can  help  best  by  contrib- 
uting information  as  to  the  ravages  of  these  two  enemies  of  the  race  and 
by  using  his  personal  and  professional  influence  to  aid  all  rational  move- 
ments for  reform.  If  alcohol  is  not  to  be  denied  to  all,  it  would  seem 
desirable  to  create  some  special  safeguards  for  the  neuropathic  component 
of  the  population  for  whom  it  involves  the  gravest  dangers.  It  is  the 
duty  of  the  physician  to  urge  total  abstinence  for  life  upon  such  people. 

At  the  Boston  Psychopathic  Hospital,  Dr.  E.  E.  Southard  formed  a 
club,  membership  in  which  was  restricted  to  those  who  had  recovered 
from  delirium  tremens  or  an  alcoholic  psychosis  in  that  institution. 
Such  associations — for  mutual  help  and  encouragement — of  those  to 
whom  successful  abstinence  is  the  only  means  of  preserving  mental 
health  or  even  life  itself  have  been  found  elsewhere  to  be  valuable 
aids. 

The  findings  of  Pollock  that  the  psychoses  come,  as  a  rule,  late  in 
the  course  of  chronic  intemperance  and  often  after  repeated  attacks 
of  delirium  tremens  should  give  renewed  impetus  to  all  movements  to 
reclaim  the  intemperate.  The  establishment  of  state  and  municipal 
colonies  for  the  treatment  of  alcoholism  will  yield  a  rich  return  in  the 
prevention  of  the  alcoholic  psychoses.  Anyone  interested  in  this  move- 
ment should  study  the  plans  of  the  New  York  City  Board  of  Inebriety 
and  the  management  of  the  Farm  Colony  which  that  Board  has  estab- 
lished. Such  movements  as  the  "Big  Brothers"  are  efficient  forces  in  this 
work  and  much  can  be  said  in  favor  of  their  aid  by  public  funds,  in  view 
of  the  valuable  public  service  which  they  perform. 

While  groups  of  people,  including  those  especially  predisposed  to 
alcoholism,  can  be  protected  to  a  certain  extent  by  various  movements 
for  regulation  of  the  liquor  traffic,  individual  prophylaxis  must  depend 
chiefly  if  not  wholly  upon  voluntary  abstinence.  Eecent  progress  in  the 
study  of  mental  mechanisms  has  provided  new  knowledge  of  great  value 
in  understanding  the  sources  from  which  the  alcoholic  craving  really 
springs  and,  in  not  a  few  cases,  in  devising  plans  for  prevention  or 
successful  treatment.  Careful  personal  studies  of  many  inebriates  show 
quite  clearly  that  inebriety  usually  represents  a  flight  from  reality  very 
similar  to  that  seen  in  the  psychoses  and  neuroses  (page  423).  Deter- 
mining by  psycho-analysis  and  other  methods  of  psychiatrical  investiga- 
tion the  nature  of  the  difficult  situation  from  which  the  individual  seeks 


OTHER  EXOGENOUS  POISONS  433 

to  fly  frequently  discloses  means  of  proventiou  as  well  as  of  cure.  When 
it  is  impossible  to  modify  the  main  factors  which  have  given  rise  to 
conflicts  in  mental  life,  much  may  be  done  by  securing  a  more  construc- 
tive solution  of  the  problem  than  that  affordeded  by  recourse  to  alcohol. 
Music,  art,  and  literature  present  avenues  of  escape  from  difficult  or 
intolerable  situations  in  real  life.  Wounded  self-esteem  can  be  restored 
by  the  satisfaction  which  comes  from  labor  for  the  welfare  of  others 
and  the  craving  for  alcohol  as  a  means  of  forgetting  or  transforming 
actuality  can  often  be  directed  into  safe  and  even  highly  constructive 
activities.  Such  forms  of  compensation  simply  suggest  that  useful 
work  in  the  prevention  or  control  of  inebriety  can  be  accomplished  by 
attempting  to  rehabilitate  the  individual  by  using  psychological  re- 
sources. It  must  be  insisted  upon,  however,  that  this  is  an  undertaking 
which  cannot  be  carried  on  with  groups.  It  is  applicable  to  individuals 
and  then  only  after  careful  personal  analysis  in  each  case.  Our  hope 
of  controlling  or  treating  inebriety  more  successfully  depends,  therefore, 
upon  concentration  upon  the  individual  inebriate. 

The  Eigh'teenth  Amendment  to  the  Constitution  of  the  United  States 
represents  the  most  sweeping  effort  yet  made  by  any  nation  to  control  in- 
temperance and  alcoholism.  Until  the  legislation  framed  to  give  effect 
to  this  amendment  has  been  fully  enforced  it  is  impossible  to  make  any 
statistical  comj)arison  of  the  prevalence  of  alcoholic  psychoses  before  and 
after  prohibition.  Incidental^,  this  legislation  constitutes  an  immense 
practical  experiment  in  ps^^chopatholojn.''  and  its  effects  upon  the  indi- 
vidual inebriate  ma}'',  when  any  large  number  is  actually  required  to 
abstain  from  alcohol,  furnish  valuable  material  and  enable  us  to  deter- 
mine what  some  of  the  essential  personal  factors  in  alcoholism  have 
been. 

OTHER  EXOGENOUS  POISONS 

Morphinism  and  other  drug  addictions  are  responsible  for  less  than 
1  per  cent,  of  first  admissions  to  hospitals  for  the  insane  in  this  coun- 
try. Fewer  such  patients  are  admitted  in  New  York  and  Massachusetts 
now  than  were  several  years  ago.  This  gratifying  fact  is  due,  in  part  at 
least,  to  stricter  enforcement  of  the  laws  regulating  the  sale  of  narcotics 
and  particularly  to  the  food  and  drug  laws  which  have  rendered  it  a  little 
more  difficult  to  dispense  habit-forming  drugs  in  patent  medicines. 
It  is  well  within  our  power  to  eliminate  this  cause  of  mental  disease  by 
wise  legislation  and  its  rigid  enforcement.     See  page  486. 

A  very  small  proportion  of  -admissions  is  caused  by  occupational 
poisonings.  This  small  proportion  can  be  still  further  reduced  by  in- 
creasing attention  to  measures  safeguarding  workmen  in  dangerous 
trades. 


434  MENTAL  HYGIENE 


ENDOGENOUS  POISONS 

The  endogenous  poisons  which  are  formed  in  the  course  of  various 
organic  diseases  are  responsible  for  not  a  few  cases  of  mental  disease. 
Their  prevention  is  the  work  of  general  hygiene. 

The  relation  of  mental  diseases  to  disturbances  of  the  organs  with 
internal  secretions  is  a  field  for  study  which  as  yet  is  almost  unexplored, 
but  which  may  yield  many  opportunities  for  applying  preventive  meas- 
ures. 

Pellagra  is  responsible  for  thousands  of  cases  of  mental  disease  in  the 
localities  in  which  it  is  prevalent.  The  high  hopes  for  the  control  of 
this  disease  which  have  been  raised  by  the  discoveries  of  Goldberger^^ 
make  it  practically  certain  that  pellagra  may  now  be  properly  counted 
a  preventable  cause  of  mental  disease.  The  studies  of  Lorenz^^'*  in  which 
it  was  shown  that  the  pellagrous  psychoses  are  undoubtedly  toxic  is  an 
instance  of  the  aid  which  psychiatry  can  often  lend  other  branches  of 
medicine  in  the  new  and  useful  alliance  between  the  psychiatrist  and 
the  sanitarian.  The  non-infectious  origin  of  pellagra  was  strongly  indi- 
cated by  Lorenz's  findings  and  thus  assistance  was  given  toward  clearing 
the  way  for  the  discoveries  of  Goldberger. 


SYPHILIS 

Psychoses. — Among  the  infections,  syphilis  deserves  separate  con- 
sideration as  a  cause  of  mental  diseases  because  it  is  the  essential  cause 
of  general  paresis,  a  psychosis  responsible  for  over  14  per  cent,  of  all 
male  first  admissions  to  hospitals  for  the  insane.  In  one  very  large  hos- 
pital, which  receives  its  patients  exclusively  from  'New  York  City,  one 
in  four  of  the  male  patients  admitted  has  general  paresis.  The  prev- 
alence of  this  disease  is  about  three  times  as  great  among  men  as  among 
women.  Although  general  paresis  is  uniformly  fatal,  the  number  of 
deaths  reported  from  this  cause  does  not  give  an  adequate  idea  of  its 
frequency,  for  death  in  this  disease  usually  results  from  some  late  com- 
plication, such  as  bronchopneumonia,  or  from  some  cerebral  accident  such 
as  hemorrhage,  which  are  direct  results  of  general" paresis  itself.  Al- 
though 830  paretics  died  in  the  New  York  State  hospitals  in  the  year 
ending  June  30,  1919,  only  742,  or  89  per  cent.,  of  these  deaths  were 
reported  as  due  to  general  paresis.  If  the  same  ratio  existed  in  those 
dying  outside  institutions  we  know  that  not  less  than  1,000  patients  with 

"See  page  686. 

^Lorenz,  William  F. :  "Mental  Manifestations  cf  Pellagra."  Puhllo  Health 
Reports,  February  4,  1916. 


SYPHILIS  435 

geueral  paresis  died  in  tlie  Slate  of  iSlew  York  during  that  year.  How- 
ever, deaths  from  this  cause  are  much  more  likely  to  be  reported  as  due 
to  complicating  disorders  outside  institutions  than  in  them,  where  the 
mental  condition  jiaturally  attracts  the  most  attention.  The  mental 
symptoms  of  general  paresis  are  so  very  often  subordinate  to  the  physical 
changes  that  admission  to  an  institution  for  the  insane  is  not  necessary 
in  all  cases  and  still  more  frequently  the  existence  of  the  disease  is 
overlooked  altogether.  It  is  apparent,  therefore,  that  general  paresis  is 
a  cause  of  many  more  deaths  than  are  attributed  to  it.  EJiowu  cases 
cause  more  deaths  in  'New  York  State  than  typhoid  fever.  The  deaths 
from  general  paresis  are  very  largely  grouped  in  the  two  decades  from  40 
to  60,  and  in  this  age-period  one  in  ililrty  of  the  deaths  among  men  and 
one  ill  sixiy-nine  of  those  among  'women  are  from  this  disease.  The 
course  of  general  paresis  is  usually  from  t^vo  to  five  years  and  the  aver- 
age hospital  residence  1.3  years.  It  attacks  people  who  have,  to  all  ap- 
pearances, recovered  from  syphilis  and  most  frequently  in  the  fourth 
decade  of  life  when  their  usefulness  to  their  families  and  to  the  com- 
munity is  greatest. 

The  relation  of  syphilis  to  general  jDaresis  has  long  been  suspected, 
and  even  before  the  discovery  by  Moore  and  ISToguchi  of  the  Treponema 
pallida  in  the  cerebral  substance  the  belief  was  general  among  psychia- 
trists that  all  cases  were  due  to  this  cause.  Other  imdetermined  factors 
apparently  contribute  to  general  paresis  but  syphilis  is  the  essential 
cause;  without  syphilis  there  could  be  no  general  paresis.  It  is  very 
desirable  to  know  what  proportion  of  cases  of  syphilis  result  in  general 
paresis,  but,  until  recently,  no  satisfactory  studies  had  been  undertaken 
to  determine  this,  and,  on  account  of  the  long  interval  between  infection 
with  syphilid  and  the  development  of  symptoms  of  general  paresis,  it 
seemed  impossible  to  find  a  group  of  population  in  which,  such  studies 
could  be  made.  Mattauschek  and  Pilcz  have  reported  the  results  of  a 
careful  examination  of  the  hiGtories  of  4,134  officers  of  the  Austrian 
Army  who  had  contracted  syphilis  during  the  period  1880-1890.  They 
ascertained  that  4.67  per  cent,  of  these  officers  developed  general 
paresis. ^°^ 

It  is  a  fact  that  general  paresis  is  a  much  more  frequent  nervous  form 
of  syphilis  than  locomotor  ataxia.  The  course  of  the  latter  disease  is 
from  six  to  eight  times  as  long  as  that  of  general  paresis  and  the  number 
of  persons  living  at  one  time  with  either  disease  is  about  the  same. 

A  relatively  small  proportion  of  other  psychoses  are  directly  due  to 
syphilis.  Mental  deterioration  is  associated  with  gummata  of  the  brain 
and  mental  changes  accompany  local  syphilitic  meningitis.  About  one 
per  cent,  of  all  men  admitted  to  hospitals  for  the  insane  and  about  half 
this  proportion  of  women  suifer  from  such  form  of  cerebral  syphilis. 

^"^  Berliner  Minisclie  JVochenschi-ift,  Feb.  19,  1912. 


436  MENTAL  HYGIENE 

It  is  impossible  to  estimate  the  part  played  by  syphilis  in  the  causation  of 
other  mental  diseases,  but  it  is  not  to  be  disregarded.  The  train  of 
pathological  processes  commencing  with  arterial  changes  and  culminating 
later  in  organic  changes  in  the  brain  with  their  accompanying  mental 
disease  is  not  infrequently  started  by  infection  with  syphilis. 

Mental  Deficiency. — Syphilis  has  been  thought  to  be  an  infrequent 
cause  of  mental  deficiency.  Tredgold  says  that  only  3.5  per  cent,  of  his 
cases  presented  undoubted  marks  of  syphilis,  while  Fletcher  Beach 
found  syphilis  in  only  1.17  per  cent,  of  2,380  mentally  defective  persons 
examined  in  London.  These  percentages  were  ascertained  before  the 
general  use  of  the  Wassermann  test.  An  esamination  of  400  patients  in 
the  asylums  of  the  Metropolitan  Asylum  Board  in  London  in  1913  by 
Gordon  ^^  showed  positive  reactions  in  31.8  per  cent,  of  cases  with  evi- 
dence of  gross  brain  disease  and  in  11.9  per  cent,  of  cases  without  such 
evidences.  In  this  ccujitry  Atwood  ^^  found  positive  reactiozas  in  15  per 
cent,  of  all  cases  and  Haines  ^^  found,  in  an  examination  of  365  children 
in  reform  schools  in  Ohio,  no  larger  percentage  among  the  mentally 
defective  than  among  the  normal  children.  Twenty  per  cent,  of  all  cases 
examined  gave  a  positive  Wassermann  reaction.  It  appears  very  probable 
that  the  percentages  of  mental  deficiency  attributed  to  syphilis  represent 
only  the  prevalence  of  syphilis  among  the  group  of  the  population  from 
which  the  mentally  defective  enter  American  institutions.  The  neuro- 
patholog}^  of  mental  deficiency  rarely  suggests  syphilis — either  heredi- 
tary or  acquired — and  it  seems  likely  that  this  is  not  a  relatively  impor- 
tant cause  of  mental  deficiency.  Tredgold  believes  that  the  existence  or 
absence  of  neuropathic  heredity  determines  whether  or  not  hereditary 
syphilis  Avill  result  in  mental  deficiency.  The  findings  in  net  a  few  cases 
of  so-called  "syphilitic  mental  deficiency"  show  quite  clearly  that  juvenile 
general  paresis  was  the  true  condition  present. 

Preventive  Measiires. — The  prevention  of  general  paresis  and  other 
mental  diseases  which  depend  directly  upon  syphilis  can  be  accomplished 
only  by  preventing  well  persons  from  contracting  syphilis  and  by  the 
early  and  effective  treatment  of  syphilitics  so  that  this  late  and  fatal 
manifestation  may  be  averted.  There  are  enough  cases  of  juvenile 
general  paresis  to  make  this  danger  an  additional  reason  for  inducing 
persons  with  syphilis  to  abstain  from  marriage.  The  prevention  of 
syphilis  is  considered  elsewhere  (Section  I,  Chapter  I).  It  is  a  rather 
surprising  fact  that  many  of  those  actively  engaged  in  the  campaign 
against  venereal  disease  are  quite  unaware  of  the  prevalence  of  general 
paresis  or  that  it  depends  upon  previous  infection  with  syphilis.     The 

^Gordon,  J.  L.:     The  Lancet,  September  20,  1913. 

^Atwood,  Charles  E. :  Journal  of  the  Amer.  Med.  Assn.,  Vol.  LVI   (1911). 

^^  Haines,  Thomas  H. :  "The  Incidence  of  Syphilis  Among  Juvenile  Delin- 
quents." 'Journal  of  the  American  Medical  Association,  V.  66,  pp.  102-05,  January 
8.  1916. 


OTHER  INFECTIONS  437 

psychiatrist  has  nothing  to  add  except  the  impressive  statistics  showing 
the  great  prevalence  of  this  terrible  result  of  syphilis  and  the  earnest 
recommendation  that  opportunities  for  the  early  and  thorough  treatment 
of  syphilis  should  be  greatly  increased.  In  the  larger  question  of  the 
control  of  prostitution,  which  is  interwoven  with  that  of  venereal  pro- 
phylaxis, the  information  being  gleaned  by  psychiatrical  study  of  the 
eprings  of  human  conduct  may  some  day  give  information  which  will 
enable  mankind  to  understand  prostitution  better  and  deal  with,  its  causes 
more  rationally. 

Increased  provision  for  tlie  mentally  defective  will  aid  in  limiting 
prostitution,  for  it  has  been  shown  that  the  feeble-minded  form  a  pro- 
lific source  for  the  recruiting  of  prostitutes.  When  the  relation  of 
syphilis  to  the  causation  of  mental  deficiency  becomes  better  defined  it 
may  be  shown  that  provision  for  the  menially  defective  vAll  decrease  the 
prevalence  of  syphilis,  and  the  control  of  syphilis  will  decrease  in  some 
measure  the  amount  of  menial  deficiency. 

OTHER  INFECTIONS 

Psychoses. — Other  infectious  diseases,  notably  tj'phoid  fever,  influ- 
enza, malarial  fever,  erysipelas,  and  septicemia  (particularly  from  uterine 
infection),  furnish  a  small  number  of  cases  of  mental  disease.  From  1 
to  2  per  cent,  of  all  first  admissions  are  mental  disease  belonging  to  the 
^'infective-exhaustive*^  group,  in  which  elevation  of  temperature,  exhaus- 
tion, and  poisoning  of  the  nsrvous  centers  by  bacterial  toxins  act  as  direct 
causes.  The  proportion  of  women  in  psychoses  in  this  group  is  about 
twice  that  of  men,  the  difference  being  due  to  the  number  of  puerperal 
cases.  In  other  psychoses,  acute  infections  often  play  a  very  important 
if  secondary  part,  apparently  'T.iberating^'  an  attack  or  adding  just 
enough  stress  to  make  the  onset  of  the  psychosis  possible.  Alcohol  and 
the  infections  exert  an  influence  together  sometimes  which  neither  cause 
can  exert  alone.  It  has  been  stated  that  tuberculosis  is  the  cause  of  a  defi- 
nite psychosis,  but  there  seems  to  be  no  evidence  upon  which  to  base  this 
tilief.     Exhaustion  psychoses  occur  in  this  disease  as  in  t^-phoid  fever. 

Mental  Deficiency. — The  growing  realization  of  the  importance  of 
heredity  as  a  cause  of  mental  deficiency  has  rather  obscured  other  factors, 
but  damage  to  the  brain  seems  responsible  for  a  considerable  number  of 
cases  of  mental  deficiency  in  families  where  there  is  no  evidence  of 
neuropathic  heredity  or  mental  deficiency.  "Where  cerebral  hemorrhage 
occurs  in  the  course  of  an  infectious  disease  in  infancy  or  early  childhood 
mental  deficiency  may  be  one  of  the  results  and  there  is  excellent  evidence 
— both  clinical  and  pathological — that  bacterial  toxins  may  permanently 
injure  the  brain  cells  or  prevent  their  development.  After  cerebrospinal 
meningitis  mental  deficiency  may  result  from  gross  damage  to  the  brain 


438  MEISTTAL  HYGIENE 

or  from  interference  with  development.  Local  meningitis  from  middle- 
ear  diseace  following  scarlet  fever  or  measles  may  also  cause  mental 
deficiency.  Serious  impairment  of  the  special  senses  as  a  result  of 
damage  to  the  cranial  nerves  may  cause  mental  deficiency  througli 
deprivation.  The  large  number  of  cases  which  have  been  attributed  to 
the  infections  of  childhood  upon  insufficient  evidence  while  really  due 
to  unmistakable  heredity  has  led  to  an  undue  skepticism  regarding 
the  influence  of  causes  acting  after  birth.  Goddard  casts  doubt  upon 
the  existence  of  such  cases,  except  those  resulting  from  cerebrospinal 
meningitis,  by  raising  the  question  as  to  why  such  diseases  as  measles  and 
whooping-cough  result  in  mental  deficiency  in  some  cases  and  not  in 
others.  Even  in  those  cases  in  which  a  cerebral  hemorrhage  has  occurred 
during  a  paroxysm  of  whooping-cough,  he  asks,  "Why  does  this  child's 
blood  vessel  burst  when  others  do  not?"  and  answers  his  question  by 
saying  that  it  can  only  be  because  there  is  "a  constitutional  ^weakness  of 
the  vascular  system  which  allows  of  a  rupture  here  and  not  in  other 
instances."  It  would  be  nearly  as  unreasonable  to  assert  that  heredity 
determines  whether  a  typhoid  fever  patient  has  an  intestinal  perforation 
or  does  not  or  whether  another  has  a  lymphangitis  or  not.  The  fact 
is  that  any  organ  of  the  child  can  be  affected  in  its  integrity  or  its 
development  by  the  infectious  diseases  through  which  he  passes,  and  yet 
we  are  asked  to  believe  that  one  of  the  most  delicate  of  them  all  can  be 
permanently  injured  only  if  heredity  has  already  laid  a  foundation  of 
predisposition.  It  is,  of  course,  very  desirable  to  know  the  mental 
condition  of  children  before  the  occurrence  of  these  accidental  causes  of 
mental  deficiency  in  order  that  errors  in  diagnosis  may  be  avoided. 

Preventive  Measures. — The  prevention  of  the  mental  diseases  and 
defects  dependent  upon  infections  consists  in  the  prevention  ,of  the  in- 
fectious diseases.  The  prevention  of  the  infectious  diseases  is  the  task  of 
preventive  medicine  and  is  considered  in  the  first  part  of  this  work. 
More  careful  methods  of  treating  febrile  diseases  and  especially  appre- 
ciation of  the  full  significance  of  delirium  will,  among  other  beneficial 
effects,  lessen  by  a  small  but  appreciable  number  the  cases  of  mental 
disease  and  mental  defect  which  follow  upon  injury  to  the  brain  in 
such  affections.  Those  individuals  who  respond  very  easily  to  delirium 
should  receive  most  careful  attention.  Hydrotherapeutic  measures  will 
probably  tend  to  prevent  cerebral  edema  and  changes  in  the  brain  cells. 


HEAD  INJURIES 

Psychoses. — A  very  small  number  of  patients  admitted  to  hospitals 
for  the  insane  suffer  from  psychoses  due  directly  to  traumatism  to  the 
brain.     Nearly  all  such  cases  are  men.     Injury  to  the  brain  often  seems 


MENTAL  CAUSES  439 

to  have  a  marked  effect  iu  precipitating  psychoses  in  alcoholics  and 
sometimes  iu  other  psychoses  dependent  primarily  upon  other  causes. 
Street  accidents  and  accidents  from  unprotected  machinery  are  responsi- 
ble for  many  head  injuries,  but  by  far  the  greater  number,  especially  in 
alcoholics,  are  due  to  the  too  vigorous  and  indiscriminate  use  of  police- 
men's clubs.  The  efficient  regidation  of  traffic  and  the  "safety  first" 
movement  are  apparently  diminishing  the  number  of  traumatic  cases 
quite  rai)i(lly,  but  it  is  possible  also  that  better  methods  of  psychiatrical 
study  are  assigning  some  of  the  cases  previously  thought  to  be  traumatic 
to  otlier  niore  appropriate  clinical  groups. 

Mental  Deficiency. — Injury  to  the  brain  or  cerebral  hemorrhage  oc- 
curring during  birth  may  be  looked  upon  as  a  cause  of  mental  deficiency 
which  is,  to  a  certain  extent,  preventable.  It  is  not  quite  as  easy  to 
determine  wliether  or  not  brain  injuries  during  infancy  and  early  child- 
hood are  the  essential  cause  of  mental  deficiency  unless  retardation  or 
cessation  in  the  mental  development  of  the  child  is  very  apparent  after 
the  injury,  for  extensive  damage,  with  definite  focal  signs,  is  often  unac- 
companied hy  mental  defect  and  a  history  of  head  injury  of  one  sort 
or  another  is  almost  always  given  by  relatives  in  cases  which  are  clearly 
hereditary,  Nevertheless,  there  are  not  a  few  instances  in  which  it 
seems  beyond  doubt  that  mental  deficiency  is  caused  by  head  injuries 
during  infancy  and  early  childhood. 

Preventive  Measures. — The  frequency  of  traumatic  psychoses  is 
hardly  great  enough  to  warrant  suggesting  specific  measures  of  preven- 
tion, but  the  "safety  first"  movement  will  prove  useful  here  as  well  as 
in  other  unsuspected  directions.  The  fairly  numerous  cases  of  brain 
injury  due  to  the  use  of  policemen's  clubs  might  be  lessened  if  police 
officials  were  given  an  idea  of  the  thinness  of  the  human  skull  and  were 
shown  a  few  persons  with  traumatic  psychoses  in  our  hospitals  for 
the  insane. 

Injuries  to  the  brain  at  birth  depend  in  some  part  at  least  upon 
careless  obstetric  work  and  the  long  labors  which  the  ignorant  manage- 
ment of  childbirth  by  midwives  entails. 


MENTAL  CAUSES 

Conflicts. — Important  recent  additions  to  our  knowledge  concerning 
the  psychology  of  mental  diseases  have  brought  about  radical  changes  of 
opinion  as  to  the  part  played  by  mental  causes.  The  statistical  tables  of 
hospital  reports  have  always  listed  as  etiological  factors  "grief,"  "worry," 
"death  of  a  relative,"  "fear,"  "remorse,"  "fright,"  and  "disappointment 
in  love."  Large  numbers  of  cases  have  been  attributed  to  such  causes  as 
these  without  any  knowledge  as  to  the  manner  in  which  they  operated. 


440  MENTAL  HYGIENE 

It  has  been  pointed  out  that  they  really  represent  little  more  than  a 
catalogue  of  the  untoward  circumstances  which,  to  a  greater  or  less  de- 
gree, shadow  the  life  of  every  individual  and  that  the  proportion  of  per- 
sons who  develop  mental  disease  in  consequence  must  be  extremely  small. 
This  difficulty  has  been  disposed  of  by  the  assumption  that  if  only  a  few 
of  those  who  are  exposed  to  such  adversities  develop  mental  disease,  an 
inherited  neuropathic  predisposition  must  determine  this  unfortunate 
outcome.  Eecent  studies,  however,  especially  those  which  have  followed 
•the  enormously  important  discoveries  of  Sigmund  Freud,  have  showri 
that  the  significance  of  such  factors  can  be  estimated  only  by  under- 
standing the  part  which  they  play  in  the  mental  lives  of  the  individuals 
affected.  Many  factors  which  have  been  listed  as  causes  of  mental 
disease  are  now  known  to  be  merely  striking  circumstances  attending 
the  progress  of  psychoses  or  surface  indications  of  deep-seated  conflicts 
in  personal  life. 

Adaptation. — The  psychoses  and  the  neuroses  are  often  clearly  seen 
to  be  attempts  at  adaptation — disastrous  to  be  sure  in  most  instances, 
but  sometimes  the  only  attempt  possible  under  the  circumstances.  They 
represent,  in  many  cases,  flights  into  the  unreal  from  intolerable  situa- 
tions in  the  life  of  the  individual.  Biologically,  these  results  may  not 
always  be  the  most  nn satisfactory  solution,  for  they  often  prolong  life. 
The  psychosis  is  not  infrequently  an  alternative  to  suicide.  As  society 
estimates  success,  however,  they  are  failures  in  adaptation.  It  would  be 
difficult,  even  if  this  entire  chapter  were  available  for  the  purpose,  to  de- 
scribe the  operation  of  mental  mechanisms  which  lead  in  the  one  case  to 
such  a  result  and  in  others  to  a  compensatory  set  of  reactions  which 
maintain  the  mental  health  and  efficiency  of  the  individual.  One  person 
deals  with  an  intolerable  situation  by  taking  refuge  in  silence,  inaccessi- 
bility and  refusal  to  eat  and,  in  consequence,  goes  to  a  hospital  for  the 
insane,  while  another  devotes  himself  to  altruistic  work  which  not  only 
increases  his  self-esteem  and  heals  the  hurts  of  an  unkind  fate,  but  at 
the  same  time  benefits  his  fellow-men.  The  explanation  of  such,  differ- 
ences in  reactions  to  events  would  lead  us  deeply  into  analysis  of  the 
personality  and  the  psychology  of  mental  diseases.  It  is  necessary,  how- 
ever, in  order  that  some  preventive  principles  may  be  presented,  to 
outline  in  a  very  general  way  the  conception  of  mental  conflict  which 
underlies  the  newer  attitude  toward  the  mental  causes  of  mental  dis- 
ease. 

Adjustments. — In  order  to  gain  an  idea  of  the  place  which  mental 
conflicts  occupy  in  the  life  of  the  individual  it  is  necessary  to  look  upon 
existence  as  a  continuous  series  of  adjustments — some  simple  and  some 
highly  difficult  and  complex — between  fundamental  instinctive  demands, 
on  the  one  hand,  and  the  requirements  of  society  on  the  other.  In  the 
young  infant,  the  care  given  by  others  makes  these  adjustments  un- 


MENTAL  CATTSES  441 

necessary.  If  this  care  is  not  furtlicoming  the  individual  perishes,  as 
there  exists  no  mechanism  by  whicii  adjustments  can  be  made.  In  the 
child,  the  adjustments  required  are  few  and  relatively  easy,  but  as  life 
unfolds  they  increase  in  number  and  complexity.  The  capacity  for  mak- 
ing these  adjustments  (upon  vhich  successful  living  depends)  varies 
greatly  in  different  individuals,  partly  as  a  result  of  differences  in  the 
inherent  capacity  for  adjustment  and  partly  as  a  result  of  failure  to 
establish,  through  experience  and  education,  the  kind  of  mental 
mechanisms  most  likely  to  aid  in  making  satisfactory  adjustments. 
The  first  factor  is  beyond  our  present  control  in  the  individual — 
heredity  has  already  determined  it — the  second,  we  are  coming  to 
believe,  may  be  greatly  modified  by  directing  attention  to  education 
and  experience. 

Behavior. — These  never-ending  conflicts  between  the  requirements 
of  reality  and  the  demands  of  instincts  determine  behavior — both  in- 
dividual and  social.  The  sex  instinct  is  involved  most  frequently  and 
most  profoundly  in  these  conflicts.  According  to  Freud,  it  is  directly  or 
indirectly  involved  in  all.  It  is  probably  more  within  the  bounds  of  mod- 
eration to  consider  these  conflicts  as  involving  any  of  the  fundamental  in- 
stincts, the  sex  instinct  most  often.  It  can  readily  be  seen  that  the 
necessity  for  continuous  adjustments  between  the  powerful  and  unalter- 
able urgings  of  the  instincts  and  the  constantly  changing  requirements 
of  daily  life  presents  innumerable  opportunities  for  mishaps  or  for  the 
establishment  of  habitual  reactions  which  are  undesirable.  Few  indi- 
viduals achieve  conspicuous  success  or  conspicuous  failure  in  this  great 
struggle  which  makes  up  the  most  of  mental  life. 

Conflicts  and  Adjustment  in  Civil  Life. — A  great  deal  of  conflict 
is  averted  through  the  intervention  of  customs  which  society,  quite 
unaware  of  their  real  purpose,  has  established  to  direct  effort  at  ad- 
justment along  paths  of  little  resistance.  Traditions  and  codes  which 
have  long  presented  opportunities  for  unsuccessful  conflict  are  con- 
stantly in  process  of  modification.  On  the  other  hand,  however,  new 
developments  in  social  life  bring  about  new  and  complex  situations. 
There  seems  to  be  evidence  that  the  requirements  of  advancing  civiliza- 
tion make,  upon  the  whole,  greater  demands  upon  the  capacity  for  ad- 
justment than  do  those  of  more  primitive  social  states.  As  Bernard 
Hart  has  pointed  out,-*  very  many  social  conventions  might  well  be 
modified  so  as  to  provide  alternatives  to  the  ruthless  decision  that 
all  individuals  who  cannot  live  "within  the  narrow  limits  assigned 
by  conventional  and  purely  arbitrary  standards  of  conduct  must 
be  segregated  from  society  or  even  prohibited  from  reproducing  their 
kind. 

"Hart,  Bernard:     '"The  Psychology  of  Insanity,"  Cambridge,  1914. 


442  MENTAL  HYGIENE 


EXPERIENCE  OF  THE  WORLD  WAR 

It  is  not  easy  to  form  an  approximate  idea  of  the  number  of  persons 
who  suffer  from  types  of  abnormal  mental  reactions  other  than  those 
which  have  been  mentioned.  Before  the  war  every  internist  and 
most  surgeons  knew  that  the  psychoneuroses  are  responsible  for  an 
enormous  amount  of  sickness  and  semi-invalidism  in  all  civilized  coun- 
tries under  such  names  as  "neurasthenia/'  "hysteria/'  "nervous  breaJi- 
down/'' "nervous  prostration/',  etc.  The  psychoneuroses  knew  no  dis- 
tinctions of  age,  sex  or  social  condition.  Complicating  other  diseases 
they  were  known  to  be  responsible  for  the  unnecessary  continuance  of 
disability,  the  intensification  of  suffering  and  for  a  great  deal  of  economic 
loss.  In  the  World  War,  however,  the  psychoneuroses  assumed  striking 
proportions  and  the  attention  of  physicians,  who  had  previously  ignored 
them  or  considered  them  relatively  unimportant  disorders  affecting 
chiefly  persons  in  fashionable  life,  was  directed  very  strongly  to  the 
scientific  consideration  of  these  diseases. 

"Shell  Shock"  and  Its  Lessons. — When  the  battered  British  divisions 
emerged  from  the  fierce  fighting  in  Belgium,  stories  came  with  them 
of  new  and  scarcely  credible  effects  of  modern  explosives.  Men  who 
had  been  exposed  to  shell  fire  but  who  bore  no  visible  wounds  were 
paralyzed,  mute,  dumb,  or  afflicted  with  strange  jerkings  and  twitchings 
of  muscles.  Others  seemed  literally  almost  frozen  into  postures  of 
attack,  defense  or  fear.  Others  were  confused  or  delirious,  had  lost 
their  memories  or  were  without  control  of  their  emotions.  Such  cases 
were  not  seen  in  really  large  numbers  but  nearly  every  unit  had  one, 
and  the  presence  of  more  remarkable  cases  in  other  units  was  quickly 
spread  by  word  of  mouth  and  usually  lost  little  in  the  telling.  Some 
of  the  mental  symptoms  noticed  were  so  similar  to  those  seen  in  grave 
forms  of  mental  disease  that  it  was  not  long  before  even  medical  officers 
began  to  say  that  men  had  "lost  their  minds"  as  the  result  of  concus- 
sion from  high  explosives.  From  all  the  armies — allied  and  enemy — 
came  the  same  stories  and  a  little  later  there  appeared  in  hospitals  at 
the  base  the  same  kinds  of  patients. 

At  the  very  outset  a  few  physicians  serving  with  troops  and  in  the 
military  hospitals  noted  the  resemblance  which  these  new  disorders  bore 
to  the  hysteria  of  civil  life  but  even  these  observers  were  loath  to  believe 
that,  appearing  in  men  who  might  have  been  concussed  by  explosions 
or  exposed  to  other  as  yet  unknown  effects  of  the  new  artillery,  the  weird 
symptoms  seen  might  not  represent  a  new  form  of  disease  or  at  least 
a  striking  modification  of  the  psychoneuroses  of  civil  life.  British  sol- 
diers invented  the  terse,  expressive  term  "shell  shock"  to  designate  all 
these  conditions  and  in  the  shortest  time  imaginable  it  had  come  into 


EXPERIENCE  OF  THE  WORLD  WAR  443 

general  use  in  the  army  not  only  aiuniii;'  flie  ol'iicers  ami  iiu'ii  of  llie  line 
but  among  doctors  and  luirscs  as  "well.  In  civil  life  one  heard  it  on 
every  side.  Two  years  later  strenuous  efforts  were  made,  on  account  of 
the  inestimable  damage  to  morale  that  its  indiscriminate  use  had 
wrought,  to  restrict  this  term  to  a  certain  class  of  cases,  but  so  deeply 
imbedded  was  it  in  speech  and  thought  that  all  these  efforts  failed. 

In  general,  "shell  shock"  was  thought  to  be  the  result  of  some  un- 
explained physical  phenomenon  connected  with  the  explosion  of  shells, 
bombs  or  mines.  The  French  medical  officers,  who  were  generally  fa- 
miliar with  the  work  of  their  own  great  students  of  functional  nervous 
disease, — Charcot,  Marie,  Dubois,  Janet  and  Babinski, — were  perhaps 
better  acquainted  than  their  British  colleagues  with  the  neuroses  as  seen 
in  civil  life  and  were  the  first  to  adapt  their  management  of  these  dis- 
orders in  war  to  this  conception  of  their  real  nature.  They  were  also 
the  first  to  separate  cases  in  which  concussion  seemed  actually  to  play 
an  important  part  from  those  in  which  the  situation  giving  rise  to  the 
disability  seemed  to  be  wholly  emotional. 

With  the  publication  of  reports  of  many  individual  cases,  a  long-con- 
tinued controversy  as  to  the  nature  of  "shell  shock"  arose.  The  observa- 
tions of  a  distinguished  neuropathologist  on  the  anatomical  changes 
found  in  the  brain  and  spinal  cord  of  several  cases  in  which  men  had  been 
killed  without  visible  injury  by  the  explosion  of  shells  or  by  being  buried 
by  parapets  were  accepted  as  evidence  that  in  all  or  the  greater  number 
of  "shell  shock"  cases  minute  injuries  to  the  central  nervous  system 
would  be  found  if  examination  could  be  made.  Various  theories  were 
advanced  to  account  for  the  types  of  damage  discovered  in  cases  coming 
to  autopsy.  Decompression  after  the  high  atmospheric  concentration 
brought  about  by  the  explosions  was  said  to  cause  the  liberation  of 
bubbles  of  gas  in  the  blood  stream.  Inhalation  of  drift  gases  from 
the  explosive  while  the  soldier  was  lying  unconscious  was  another  method 
by  which  it  was  thought  the  central  nervous  system  was  frequently 
damaged. 

Soon,  however,  evidence  commenced  to  accumulate  showing  that, 
whatever  organic  basis  there  might  be  for  "shell  shock,"  there  were  many 
cases  in  which  the  causative  factors  were  chiefly  or  wholly  psychological. 
Men  in  training  camps  in  England  and  France,  especially  those  about 
to  embark  or  entrain  for  active  sectors,  exhibited  exactly  the  same  symp- 
toms as  those  reported  in  men  who  had  become  incapacitated  under  shell 
fire.  Thousands  of  observations  upon  the  wounded  showed  that  very 
few  had  any  psychoneurotic  symptoms  whatever,  even  when  there  was 
gross  damage  to  the  brain  and  spinal  cord.  A  disproportionate  rate 
among  officers  was  difficult  to  explain  on  the  grounds  of  injury.  All 
sorts  of  extraordinary  recoveries,  such  as  would  have  been  quite  impos- 
sible if  the  extensive  symptoms  present  had  been  the  result  of  permanent 


444  MENTAL  HYGIEITE 

organic  damage,  commenced  to  be  reported  and  psychological  methods  of 
treatment  were  found  to  be  much  more  efficacious  than  any  others.  A 
comparison  of  the  personal  make-up  and  heredity  of  men  who  had  "^shell 
shock"  with  those  of  wounded  men  taken  for  control  showed  that 
among  the  former  there  was  a  heavy  preponderance  of  men  with  a 
personal  or  family  history  of  psychoneurotic  make-up.  The  extreme 
rarity  of  neuroses  among  prisoners,  even  in  large  groups  taken  in  the 
fiercest  fighting,  was  pointed  out.  More  and  more,  the  resemblance  of 
the  war  neuroses  to  those  of  civil  life  became  apparent,  especially  when 
the  vivid  setting  of  the  battlefield  was  replaced  by  that  of  the  train- 
ing camp  in  the  histories  of  patients  studied.  Slowly  the  conception 
of  "shell  shock''  as  wholly  in  some  cases  and  partly  in  most  others  a 
psychological  disorder  came  into  vogue  among  physicians.  Laymen 
became  dubious  regarding  certain  phases  of  the  affection  but,  in  gen- 
eral, remained  pretty  firmly  convinced  of  the  validity  of  the  first  popu- 
lar conception  of  "shell  shock"  as  a  new  and  unheard  effect  of  the 
use  of  high  explosives  in  modern  warfare. 

With  this  change  in  professional  opinion  (which  was  by  no  means 
universal)  there  came  about  new  methods  of  treatment  and  certain 
changes  in  administrative  management.  The  propriety  of  authorizing 
men  with  "shell  shock"  to  wear  wound  stripes  was  questioned  and  an 
attempt  made  to  regulate  it  so  that  only  those  who  had  actually  been 
concussed  in  battle  could  acquire  this  badge  of  honor.  The  practical 
difficulties  in  the  way  of  the  enforcement  of  such  regulations  are,  of 
course,  obvious.  The  suspicion  of  malingering,  which  had  existed  in 
the  minds  of  some  at  the  very  beginning,  commenced  to  be  expressed 
more  frequently  and  the  question  was  raised  in  Parliament  several 
times  as  to  the  possibility  of  severe  punishment  being  wrongly  inflicted 
upon  victims  of  these  disorders  by  those  who  held  this  view.  Against 
the  spread  of  a  rather  less  charitable  attitude  toward  the  "shell  shockers" 
there  was  brought  to  bear  the  intense  public  sympathy  that  always  went 
out  toward  men  in  such  a  pitiable  condition  and,  up  to  the  end  of  the 
war,  there  was  little  real  change  in  the  popular  or  official  attitude  toward 
soldiers  with  war  neuroses. 

Important  modifications  in  treatment,  however,  reflected  the  medical 
change  of  opinion.  Men  who  had  strongly  advocated  a  psychological 
approach  to  the  treatment  found  it  possible  to  secure  influential  sup- 
porters and  in  practically  all  the  special  hospitals  for  war  neurosis  cases 
in  England,  efforts  were  made  to  use  psychotherapy  in  one  form  or  an- 
other and  to  rely  upon  electricity,  massage,  passive  exercise  and  other 
means  directed  toward  the  elimination  of  symptoms  only  as  an  adjuvant 
CO  analysis  of  the  situation  and  reeducation  of  will. 

The  alarming  accumulation  of  uncured  cases  in  the  hospitals  led 
to  the  adoption  of  the  policy  of  not  sending  any  recovered  cases  back 


EXPERIENCE  OF  THE  WORLD  WAR  445 

to  the  front  line  duty.  Those  who  saw  the  great  dangers  to  morale 
that  were  involved  in  this  plan  warned  the  government  that  this  meas- 
ure would  greatly  increase  the  incidence  of  functional  nervous  diseases. 
Popular  opinion,  even  among  discharged  wounded  soldiers,  supported  it, 
however,  and  those  wlio  were  attempting  to  cure  the  disease  had  forced 
into  their  hands  a  measure  which  promoted  symptomatic  recovery  but 
constituted  a  new  enemy  to  the  morale  of  the  individual. 

Toward  the  beginning  of  1917  some  well  trained  psychiatrists  and 
neurologists  who  were  serving  with  troops  had  an  opportunity  to  treat 
suitable  cases  in  advanced  sanitary  formations.  They  had  astonishing 
results.  In  their  hands  symptoms  which  had  always  proved  most  in- 
tractable in  hospitals  at  the  base  were  found  to  be  readily  removable. 
The  whole  course  of  the  disease  seemed  in  many  instances  to  be  within 
the  power  of  these  physicians  to  influence,  and  it  was  found  relatively 
easy  to  prevent  the  fixation  of  psychoneurotic  symptoms  in  exhausted 
soldiers  and  those  who  had  undergone  the  severest  emotional  experiences 
if  efforts  could  be  commenced  within  a  few  hours  from  their  onset.  Some 
of  the  medical  officers  who  had  this  experience  attributed  their  success 
to  the  specific  methods  of  treatment  that  they  had  used — such  as  hypno- 
tism— but  others  saw  that  an  important  discovery  in  medico-military 
•therapeutics  had  been  made.  About  the  same  time  the  French,  who 
from  the  first  had  dealt  with  these  disorders  from  a  psychological  ap- 
proach, put  their  theories  fully  into  practice  and  established  in  each 
army  area  an  army  neurological  hospital  to  which  patients  could  be 
admitted  from  the  trenches  within  a  few  hours  and  (of  even  more  im- 
portance) from  which  they  could  be  returned  directly  to  duty  as  soon 
as  their  symptoms  had  disappeared. 

It  is  necessary  to  go  into  this  bit  of  medico-military  history  to  this 
extent  to  draw  a  picture  of  the  situation  with  regard  to  the  management 
of  the  war  neuroses  in  the  armies  of  our  allies  up  to  and  at  the  time 
of  our  own  participation  in  the  war.  The  methods  of  dealing  with  the 
psychoneuroses  in  war  are  quite  important,  for  the  lessons  which  a 
little  later  will  be  drawn  from  the  war  neuroses  are  in  reality  lessons 
from  their  management  and  not  from  the  diseases  themselves. 

The  prevalence  of  the  neuroses  during  the  full  tide  of  war  will  in- 
dicate the  practical  importance  of  those  disorders  to  a  nation  thrown 
back  upon  its  uttermost  resources  in  manpower.  By  July,  1917,  20 
per  cent,  of  all  discharges  from  the  British  Army  for  disability  had  been 
for  "shell  shock"  and  allied  conditions.  When  w^e  remember  that  the 
proportion  for  wounds  of  all  kinds  was  only  47  per  cent,  w^e  can  see 
how  important,  in  a  purely  military  sense,  the  withdrawal  from  active 
duty  of  this  number  of  unwounded  men  must  have  been  at  a  time 
when  every  effort  was  being,  made  to  comb  out  the  last  fit  man  and  to 


446  MENTAL  HYGIENE 

find  some  place  of  military  usefulness  for  those  who  were  only  partially 
fit. 

The  immense  number  of  persons  with  psychoneuroses  who  were 
studied  in  military  hospitals  during  the  war  afforded  striking  opportu- 
nities for  testing  the  soundness  of  such  observations  on  the  nature  of 
the  psychoses  and  psychoneuroses  as  have  been  given  above.  Out  of 
this  vast  experiment  have  developed  many  new  points  of  view,  but  the 
essential  soundness  of  the  modern  conception  of  the  part  played  by  con- 
flict in  mental  life  has  been  demonstrated  in  an  unexpectedly  dramatic 
way.  Whatever  differences  of  opinion  may  exist,  it  seems  fair  to  state 
that  the  opinion  expressed  by  Dr.  Sidney  I.  Schwab/^  that  the  war 
neuroses  are  protective  or  defensive  elaborations  of  the  primary  instinct 
of  self-preservation  in  the  face  of  destructive  incidents  of  war,  is  ac- 
cepted not  only  as  sound  in  theory  but  as  capable  of  having  built  upon 
it  a  structure  of  practical  treatment,  management  and  prophylaxis. 
With  the  observations  of  the  English  and  French  to  guide  us,  our  own 
army  was  able  to  put  into  effect  a  definite  mechanism  for  the  prophylaxis 
of  psychoneuroses  in  the  field.  This  was  carried  out  through  assign- 
ing to  each  tactical  division  a  competent  neuropsychiatrist.  In  the  be- 
ginning m.any  difficulties  arose,  some  of  them  quite  inseparable  from 
the  military  situations,  but  in  the  St.  Mihiel  and  Argonne-Meuse  of-. 
fensives  a  system  of  diagnosis,  prevention  and  early  treatment  was  put 
into  effect  with  striking  results.  This  consisted  of  the  assignment  of 
division,  corps  and  army  neuropsychiatrists,  the  concentration  of  small 
reserve  groups  of  neuropsychiatrists  at  the  advanced  neurological  hos- 
pitals, the  careful  examination  and  vigorous  treatment  of  psychoneu- 
rotic patients  in  field  sanitary  units,  more  prolonged  treatment  in  army 
units  and  the  utilization  of  the  special  hospital  in  the  Zone  of  the 
Advance.  Of  100  men  received  at  the  "triages"  or  sorting  field  hos- 
pitals, 65  were  returned  directly  to  their  units  for  duty,  in  spite  of  a 
pressure  for  room  in  these  divisional  sanitary  units  occasioned  by  the 
enormous  number  of  •  casualties.  Of  the  35  received  at  the  army  neu- 
rological hospitals,  20  were  returned  directly  to  their  divisions  for  duty, 
and  only  15  evacuated  to  the  rear  for  treatment  in  a  special  hospital  in 
the  Zone  of  the  Advance.  This  hospital  (Base  Hospital  117),  in  its 
entire  work,  had  only  35  per  cent,  of  its  patients  reclassified  for  non- 
combatant  duty,  and  only  6  per  cent,  returned  to  the  United  States  to 
be  discharged  from  the  military  service  for  disability.  Therefore,  of 
100  patients  with  psychoneurosis  who  came  to  the  attention  of  the  di- 
visional neuropsychiatrists,  only  five  were  permanently  invalided  for 
non-combatant  duty  and  only  one  returned  to  the  United  States.     The 

=^  Schwab,  Sidney  I.  (formerly  Major,  M.  C,  U.  S.  A.,  Medical  Director,  Base 
Hospital  117,  A.  E.  F.)  :  "The  War  Neuroses  as  Physiologic  Conservations." 
Arch,  of  Neurology  cmd  Psychiatry,  Maj,  1919,  V,  1,  p.  579. 


EXPERIENCE  OF  THE  WORLD  WAR  447 

methods  of  treatment  employed  from  the  most  advanced  stations  to 
the  special  base  hospitals  were,  of  course,  individual  and  varied,  but  in 
all  instances  their  foundation  was  the  psychological  conception  of  the 
nature  of  the  psyehoneuroses  outlined  in  the  preceding  pages. 

Preventive  Measures. — There  are  special  groups  of  the  population 
in  special  need  of  assistance  in  making  the  adjustments  to  their  en- 
vironment upon  which  successful  living  depends.  The  idiot,  like  the 
young  infant,  is  incapable  of  making  even  the  simplest  adjustments 
to  the  world  about  him  and  would  perish  if  others  did  not  make  for 
him  the  adaptations  whieh  he  cannot  make  for  himself.  Defectives  of 
higher  grade  can  make  relatively  simple  adjustments  and  in  an  en- 
vironment carefully  arranged  with  reference  to  the  extent  of  their  ad- 
justing capacity  happy  and  useful  living  is  possible.  As  Dr.  C.  Macfie 
Campbell  has  pointed  out,^''  "the  contented  and'  industrious  worker  iu 
an  institution  for  the  feeble-minded  may  have  exactly  the  same  consti- 
tution as  his  brother  wdio  is  in  jail  for  repeated  criminal  acts."  It  is 
not  with  the  mentally  defective,  however,  that  this  phase  of  mental 
hygiene  chiefly  concerns  itself.  Adjustments  cannot  be  made  by  some- 
body else  for  one  who  is  not  mentally  defective ;  they  must  be  made  by 
the  individual  and  all  that  others  can  do  is  so  to  train  and  direct  his 
activities  that  he  will  develop  good  mental  reactions  and  so  to  aid  him 
in  selecting  his  environment  that  he  will  live  upon  the  level  which,  for 
him,  offers  the  best  opportunities  for  efficient  and  happy  existence. 
The  practical  application  of  these  broad  principles  obviously  depends 
upon  the  recognition  of  the  capacities  and  limitations  of  the  individual. 
As  the  reactions  which  determine  success  or  failure  in  life  are  very 
largely  established  in  childhood,  it  is  to  the  child  that  preventive  meas- 
ures must  chiefly  be  applied. 

The  enormous  increase  of  interest  in  the  mental  life  of  childhood 
is  leading  to  the  recognition  at  a  much  earlier  period  than  formerly  of 
those  factors  which  endanger  mental  health.  Education  must  be  funda- 
mentally altered  to  fit  the  needs  of  subnormal  children  and  those  with 
special  difficulties  of  adaptation.  So  numerous  and  so  disastrous  are 
the  results  of  failure  to  make  the  modifications  in  teaching  which  these 
children  require  that  the  whole  educational  system  might  well  be  ex- 
amined with  reference  to  their  special  needs.  Constant  and  increasing 
efforts  should  be  made  to  determine  the  individual  requirements  of 
school  children  and  the  attention  of  the  best  educators  should  be  given 
to  devising  means  for  furnishing  such  children  with  an  equipment  which 
■will  fit  the  individual  child  to  live  successfully,  the  average  child  being, 
for  the  moment,  forgotten.  Special  classes  exist  now  only  for  mentally 
defective  children.     They  should  be  provided  for  all  kinds  of  atypical 

"Campbell,  C.  Macfie:  "Educational  Methods  and  Fundamental  Causes  of 
Dependency."     Mental  Hygiene,  Vol.  I,  No.  1,  p.  235,  April,  1917. 


448  MENTAL  HYGIENE 

children,  intellectual  defect  representing  only  one  and  not  perhaps  the 
most  important  cause  of  imperfect  mental  adjustment. 

Of  the  utmost  importance,  in  laying  the  foundations  in  childhood  for 
mental  reactions  which  in  later  life  may  prevent  psychoses,  is  the  culti- 
vation of  a  frank  emotional  attitude.  Personal  difficulties  should  never 
be  dissembled  but  always  faced  in  their  reality.  Children  do  not  feel 
the  same  emotions  as  adults  and  the  efforts  of  parents  and  teachers  to 
make  them  feel  or  "act  as  if  they  felt"  sympathy  or  sorrow  or  remorse, 
when  they  do  not,  simply  plants  the  seeds  for  unreal  emotional  attitudes 
in  later  years.  Eecourse  to  the  unreal  is  the  habit  which  it  is  mental 
hygiene's  great  task  to  prevent.  It  is  much  better  to  have  a  child  do 
something  to  relieve  suffering  than  to  induce  him  to  act  as  if  he  felt  an 
emotion  which  in  reality  he  does  not.  Thus  the  objectivity  of  life  will 
be  intensified  and  this  is  perhaps  the  chief  object  of  mental  hygiene. 
Lyman  Wells  has  said  (what  all  psychiatrists  know)  ^''  that  self-love  and 
self-consciousness  constitute  the  great  fountainhead  of  mental  mal- 
adaptations.  No  other  measures 'will  more  surely  prevent  their  growth 
than  the  frank  facing  of  actuality  in  childhood  when  mistakes  can  be 
acknowledged  without  loss  of  self-respect  and  rectified  without  difficulty. 
It  is  especially  important  that  a  frank  emotional  attitude  toward  sex 
should  be  established.  The  movement  for  instruction  in  sex  hygiene  has 
for  its  chief  objects  the  control  of  venereal  disease  and  the  prevention  of 
sexual  immorality.  If  this  movement  grows  upon  a  rational  and  strong 
foundation,  these  benefits  will  be  far  outweighed  by  its  effect  upon  the 
general  attitude  toward  sexual  difficulties. 

Preventive  measures  in  this  field  of  mental  hygiene  embrace  a  wide 
range  of  activities.  All  of  them  could  hardly  be  enumerated  here  but  the 
more  fundamental  ones  may  with  advantage  be  summed  up,  even  at  the 
risk  of  being  didactic,  in  these  injunctions :  determine  the  inherent  capac- 
ity of  each  individual  to  make  adjustments  to  his  environment;  realize 
that  the  causes  of  most  maladjustments  in  later  life  arise  in  the  early 
years  of  childhood ;  aid  each  individual  to  find  the  level  at  which  he  can 
live  most  successfully;  cultivate  a  frank  emotional  attitude,  especially  in 
matters  relating  to  sex;  deal  with  actualities  and  so  do  not  evade  diffi- 
culties or  transform  them  into  a  false  situation;  cultivate  an  objective 
view  of  life,  enjoying  to  the  full  art,  literature,  music,  and  other  desirable 
means  of  escaping  into  the  world  of  unreality,  but  at  the  same  time  real- 
izing their  real  nature;  distribute  interest  throughout  a  wide  range  of 
activities,  reserving  an  important  place  for  those  which  do  not  contribute 
directly  to  self-gratification  but  which  benefit  others. 

It  is  of  the  utmost  importance  in  this  field  of  mental  hygiene  to 
remember  that  individuals  in  need  of  assistance  in  making  difficult  ad- 

"  Wells,  Lyman  F.:  "Mental  Adaptation."  Mental  Hygiene,  Vol.  I,  p.  60, 
Jan.,  1917. 


ECONOMIC  FACTORS  449 

justments  are  rarely  able  to  umlerstand  tlie  situation  or  take  the  steps 
needed  to  bring  about  successful  adjustments  without  the  help  of  others 
and  that  those  who  give  such  help  must  possess  psychiatrical  knowledge. 
This  emphasizes  the  importance  of  mental  clinics  where  such  advice  and 
guidance  can  be  obtained.  Every  university  should  have  a  department 
of  mental  hygiene  in  charge  of  a  well-qualified  psychiatrist  whose  chief 
duty  should  be  to  help  students  to  understand  and  deal  with  their  per- 
sonal problems.  Every  city  school  system  should  have  such  a  department 
and  should  maintain  school  clinics  in  charge  of  competent  psychiatrists 
for  the  examination  and  treatment  of  all  children  experiencing  special 
difficulties.  If  these  recommendations  seem  radical  and  expensive,  it 
is  only  necessary  to  consider  the  enormous  loss  through  mental  diseases 
and  other  maladjustments  which  depend  upon  the  causes  that  we  have 
been  considering  and  then  remember  that  this  is  the  one  group  of  mental 
affections  in  which,  at  the  present  time,  practically  no  efforts  are  being 
made  for  prevention. 

Unless  the  experience  in  managing  the  psychoneuroses  in  war  is 
to  become  simply  an  interesting  and  striking  piece  of  medico-military 
histor}%  it  must  be  applied  in  civil  life.  The  psychiatrist  stationed  at  the 
''triage,"  examining  closely  into  the  nature  of  breaks  in  individual 
morale,  should  be  regarded  as  the  precursor  of  the  school  psychiatrist 
to  whom  are  referred  all  children  who  have  special  difficulties  in  adap- 
tation. The  neurological  hospitals  just  behind  the  line,  in  which  the 
actual  stress  was  occurring,  must  be  followed  by  the  establishment  of 
school  clinics  and  psychopathic  hospitals  where  individuals  wavering 
under  the  stress  of  adaptation  to  the  economic,  social  and  personal  situa- 
tions of  modern  life  may  have  skilled  advice  and  treatment.  Base  Hos- 
pital 117,  a  psychiatric  hospital,  which  was  never  concerned  with  issues 
of  insanity,  must  have  its  counterpart  in  hospitals  for  the  study  and 
treatment  of  the  more  severe  types  of  psychoneuroses  by  psychotherapy, 
physiotherapy  and  every  other  aid  kno^Ti  to  modern  psychopathology. 


ECONOMIC  FACTORS 

Unemployment,  overwork,  congestion  of  population,  child  labor,  and 
the  hundred  economic  causes  which  increase  the  stress  of  living  for  the 
poor  are  often  contributing  factors  in  the  production  of  mental  diseases. 
Weaknesses  in  constitutional  make-up — defects  in  the  armor  of  per- 
sonality— are  disclosed  under  the  stress  of  such  conditions,  but  might 
have  remained  undiscovered  under  happier  circumstances.  All  that  can 
be  said  of  the  prevention  of  such  causes  is  that  everything  which  makes 
for  the  betterment  of  those  upon  whom  the  stress  of  livi^ig  falls  heaviest 
wiU  save  many  from  mental  disease.    If  the  operation  of  these  powerful 


450  MENTAL  HYGIENE 

causes  cannot  be  prevented,  those  who  are  most  likely  to  be  harmed  might, 
perhaps,  be  shielded  a  little  if  the  special  danger  which  they  face  were 
more  generally  known. 

IMMIGRATION 

No  consideration  of  the  preventable  causes  of  mental  diseases  in  this 
country  would  be  complete  without  reference  to  this  important  element 
in  our  national  life.  It  is  a  question  peculiar  to  the  United  States.  Dur- 
ing the  last  95  years  32,027,424  immigrants  have  come  to  this  country.^^ 
This  vast  migration  has  no  parallel  in  history.  In  some  states  the  incre- 
ment to  the  population  from  immigration  every  year  exceeds  that  from 
births.  Under  such  conditions  movements  such  as  those  directed  against 
alcohol,  heredity,  or  the  economic  causes  of  insanity  are  feeble  in  their 
immediate  effects  compared  with  a  thorough  sifting  of  applicants  for 
admission  while  they  are  still  at  our  threshold.  We  have  the  absolutely 
unquestioned  right  to  require  any  rea'sonable  tests  which  can  be  proposed, 
and  yet  the  present  immigration  law  results  in  the  mental  examination 
of  the  smaller  portion  of  the  million  immigrants  who  seek  admission  each 
year.  There  is  no  provision  whatever  requiring  immigrants  to  present 
certificates  from  responsible  authorities  at  home,  testifying  to  their  free- 
dom from  mental  disease.  These  great  numbers  of  immigrants,  30  per 
cent,  of  the  adults  illiterate  and  less  than  20  per  cent,  with  any  trade, 
are,  without  adequate  mental  examination  or  selection,  projected  into 
our  most  congested  centers  of  population,  to  bear,  during  their  first 
years  in  America,  as  severe  stress  as  any  group  of  population  can  be 
called  upon  to  endure.  One  result  is  that  they  are  found  in  larger  num- 
bers in  our  hospitals  for  the  insane  than  their  ratio  to  the  whole  popula- 
tion warrants.  Hundreds  have  to  be  returned  during  the  first  year  for 
mental  disease  due  to  causes  which  existed  before  their  arrival.  In  the 
succeeding  years  the  proportion  rises  and  in  the  next  generation  and  the 
one  succeeding  it  we  shall  doubtless  reap  the  harvest  for  which  our  pres- 
ent policy  is  sowing  the  seed.  It  can  be  earnestly  asserted,  after  long 
study  of  this  question,  that  no  measures  for  the  control  of  mental  diseases 
and  mental  deficiency  which  have  yet  been  suggested  can  prove  so  eSica- 
cious  as  artificial  selection  of  additions  to  our  population  on  the  vast  scale 
which  an  adequate  mental  examination  of  immigrants  would  permit. 
This  is  a  measure  of  practical  eugenics  which  can  be  applied  successfully 
now  and  one  in  which  we  shall  not  have  to  wait  a  generation  to  note  the 
effect.  As  Professor  E.  DeC.  Ward  has  said,  '^It  is  merely  a  question 
whether  we  or  foreign  steamship  agents  shall  select  the  parents  of  future 
generations  of  Americans."  The  provisions  of  the  federal  immigration 
law  which  deal  with  the  exclusion  of  insane  immigrants  are  in  need  of 
=«  January  1,  1820,  to  June  30,  1915. 


AGENCIES  AVAILABLE  451 

thorough  anil  immediate  revision  and  the  enforcement  of  the  law  should 
receive  the  attention  which  its  importance  deserves. 

We  have  heen  far  too  careless  of  tiic  welfare  of  recently  landed  im- 
migrants. There  seems  to  be  a  general  impression  that,  however  unsani- 
tary their  surroundings  or  however  heavy  may  be  the  burdens  placed  upon 
them,  immigrants  are  in  some  way  fitted  for  such  hardships,  either  by 
nature  or  through  previous  experiences  in  their  homes.  Of  course,  this 
assumption  is  without  justification  and  it  is  time  that  the  social,  eco- 
nomic, physical,  and  moral  welfare  of  these  newcomers  be  given  the 
earnest  attention  of  the  federal  and  state  governments  and  of  societies 
and  individuals.  By  so  doing  something  may  be  done  to  lessen  the  dis- 
proportionate prevalence  of  mental  disease  in  this  large  group  of  our 
population. 


AGENCIES   AVAILABLE    FOR    THE    APPLICATION 
OF  PREVENTIVE  MEDICINE 

It  is  possible  to  mention  only  very  briefly  some  of  the  agencies  which 
can  be  utilized  in  the  application  of  preventive  measures. 

Hospitals  for  Mental  Disease. — A  very  large  proportion  of  the  per- 
sons with  mental  disease  in  any  state  will  be  found  under  treatment  in 
public  institutions.  This  is  not  the  case  with  other  diseases,  sufferers 
from  which  are  widely  scattered,  in  their  homes,  at  work,  and  in  hos- 
pitals. This  fact  makes  the  hospital  for  the  insane  seem  the  logical  place 
in  which  preventive  measures  should  originate.  As  Adolf  Meyer  ^^  has 
said :  '^A  modern  hospital  must  get  together  the  material  with  which 
to  reconstruct  the  patient's  life.  It  must  be  in  touch  with  the  patient's 
home.  .  .  P 

No  agency  for  practical  work  in  prevention  and  the  diffusion  of 
knowledge  regarding  mental  diseases  and  the  mental  factors  in  other 
diseases  can  compare  with  the  university  psychiatric  clinic.  Situated 
in  large  centers  of  population,  such  clinics  are  centers  for  research,  treat- 
ment, prophylaxis,  and  education.  Their  influence  is  felt  in  every  de- 
partment of  the  universities  in  which  they  are  located  and  their  social 
contacts  are  so  extensive  that  no  person  who  has  to  deal  with  mental 
problems,  whether  he  be  parent,  teacher,  magistrate  or  social  worker, 
goes  from  them  empty-handed.  Largely  on  account  of  the  populariza- 
tion of  neuropsychiatry  among  physicians  and  laymen  as  a  result  of  the 
war,  the  demand  for  university  psychiatric  clinics  is  rapidly  spreading 
in  this  country.  It  seems  now  quite  certain  that  within  ten  years'  time 
every  graduate  of  a  Class  A  medical  school  will  be  taught  mental  medi- 

^  Meyer,  A4olf:  "Organizing  the  Communitv  for  the  Protection  of  Its  Men- 
tal Life."     The  Survey,  September  18,  1915,  p.  557. 


453  MENTAL  HYGIENE 

cine  in  such  a  center.  This  is  a  development  which  might  have  been 
expected  to  follow  the  increase  of  interest  in  all  the  lesser  mental  dis- 
orders which  existed  in  the  military  service,  but  the  fact  that  such  a 
clinic  can  establish  and  maintain  the  closest  contact  with  the  social,  edu- 
cational and  the  economic  life  of  the  community  in  which  it  is  placed  is 
due  chiefly  to  the  work  of  the  late  Dr.  E.  E.  Southard  at  the  Boston 
Psychopathic  Hospital.  No  consideration  of  the  psychopathic  hospital 
as  an  agent  in  mental  hygiene  is  complete  without  testimony  to  the 
vision,  energy  and  resourcefulness  which  enabled  Dr.  Southard  to  show 
the  community  that  it  needed  the  psychopathic  hospital  and  to  show 
the  psychopathologist  that  he  was  needed  in  the  community. 

Public  Health  Authorities. — No  better  illustration  of  the  fact  that 
mental  hygiene  has  become  one  of  the  recognized  activities  of  health 
authorities  can  be  found  than  the  proposal  to  create  a  division  of  mental 
hygiene  in  the  United  States  Public  Health  Service.  A  bill  to  provide 
such  a  division  is  now  before  Congress.  Several  state  departments  of 
health  are  circulating  information  regarding  mental  hygiene  in  their 
work  of  educational  publicity.  Following  the  example  of  the  Department 
of  Preventive  Medicine  and  Hygiene  of  Harvard  Medical  School,  courses 
in  mental  hygiene  are  now  given  in  the  public  health  departments  of 
many  universities.  Special  courses  for  teachers,  nurses  and  other  groups 
are  being  established  throughout  the  country.  A  new  development  of 
much  importance  is  the  special  training  of  medical  and  social  workers 
in  psychiatric  social  work.  This  was  undertaken  at  Smith  College  dur- 
ing the  war  in  order  to  prepare  young  women  for  work  with  returning 
disabled  soldiers.  It  has  been  so  rapidly  extended  that  there  are  now 
no  less  than  a  dozen  schools  for  social  work  in  the  United  States  giving 
special  courses  for  psychiatric  social  workers. 

Educational  Authorities. — Under  the  direction  of  state  boards  of 
administration  and  encouraged  by  national  and  state  societies  for  mental 
hygiene,  much  can  be  done  toward  placing  the  education  of  psychopathic 
and  defective  children  upon  a  better  basis.  These  children  are  now 
chiefly  interesting  to  school  authorities,  for  they  constitute  a  special  class 
and  should  receive  separate  instruction,  both  for  their  own  good  and  the 
good  of  normal  children  whose  progress  is  retarded  on  account  of  the 
excessive  amount  of  time  teachers  must  give  defective  children.  They 
should  have  a  far  greater  interest  for  the  state  than  this,  for  every  child 
is  a  possible  patient  in  a  hospital  for  the  insane.  It  would  seem  desirable 
for  the  state  to  provide  very  liberally  for  the  study  of  these  children  and 
for  their  training.  To  this  end,  school  clinics  and  special  classes  in  the 
■  public  schools  should  be  fostered  by  the  state  educational  authorities 
and  even  subsidized  by  the  state  when  desirable. 

National  and  Local  Societies  for  Mental  Hyg-iene. — There  is  a  very 
clearly  defined  field  of  effort  for  national  and  local  societies  in  the  work 


AGENCIES  AVAILABLE  453 

of  prevention  of  nuMilal  diseases.  As  has  heeii  imlieated,  the  eare  oC  the 
insane  is,  far  more  than  that  of  any  oilier  ehiss  of  tlie  sick,  in  ollicial 
hands.  'Phere  is  hesides  a  great  deal  in  the  methods  of  commitment  and 
provisions  for  care  pending  commitment  which  is  regarded  wholly  as  an 
official  matter.  For  this  reason  there  is  decided  need  for  agencies  which 
can  hridge  the  gap  hctween  the  usual  environment  of  the  patient  and  the 
I)ublic  institution  which  is  to  assume  his  care.  A  certain  part  of  the 
social  service  work  which,  has  so  useful  a  place  in  the  care  of  the  insane, 
particularly  in  the  period  following  discharge  from  institutions,  should 
be  done  by  workers  under  the  direction  of  institutional  authorities,  but 
there  is  also  a  very  great  deal  which  can  be  done  better  by  societies  co- 
operating with  institutional  authorities  but  not  officially  connected  with 
them.  In  New  York  State  the  "Committee  on  Mental  Hygiene"  of  the 
State  Charities  Aid  Association  has  a  local  committee  in  each  hospital 
district.  Although  after-care  and  efforts  to  improve  the  kind  of  care 
afforded  the  insane  in  that  critical  period  while  commitment  is  pending 
constitute  the  chief  work  of  such  committees,  there  is  often  opportunity 
for  effective  work  in  prevention,  especially  in  popular  education  regard- 
ing preventable  causes.  In  Alabama,  California,  Connecticut,  District 
of  Columbia,  Illinois,  Louisiana,  Maryland,  Massachusetts,  North  Caro- 
lina, Ohio,  Pennsylvania,  Rhode  Island,  Iowa,  Virginia,  Kansas,  Georgia, 
Mississippi  and  Oregon,  there  are  societies  for  mental  hygiene  doing 
most  useful  work. 

There  is  a  National  Committee  for  Mental  Hygiene,  coordinating 
and,  in  a  measure,  directing  these  local  activities.  This  committee  has 
commenced  studies  of  existing  provisions  for  the  care  of  the  insane  and 
mentally  defective  in  all  the  states,  methods  of  commitment  and  care 
pending  commitment,  the  influence  of  preventable  causes,  etc.  With  a 
carefully  prepared  plan  of  work,  accurate  information  is  being  obtained 
upon  these  matters,  and,  as  fast  as  the  facts  in  the  possession  of  the 
committee  Justify  it,  active  work  is  undertaken  for  amelioration  or  pre- 
vention. It  is  believed  that  a  great  deal  can  be  done,  especially  in  the 
direction  of  standardizing  work  for  the  care  of  the  insane  and  the  pre- 
vention of  insanity,  and  in  coordinating  the  efforts  of  the  hospitals,  state 
boards  of  administration  and  some  of  those  organizations  which  (some- 
times unawares)  are  attacking  preventable  causes  of  mental  diseases  and 
mental  deficiency  from  different  angles.  The  National  Committee  aims 
to  stimulate  interest  on  the  part  of  the  federal,  state  and  local  authorities 
charged  with  health  work  and  the  care  of  the  insane  and  mentally  defec- 
tive and  to  sustain  interest  when  otherwise  it  might  flag.  Standards 
established  in  states  where  advanced  ideas  prevail  are  being  made  known 
in  states  where  there  is  indifference  or  lack  of  progress,  A  central 
"clearing  house"  for  the  collection  and  distribution  of  accurate  informa- 
tion regarding  the  care  and  prevention  of  mental  diseases  and  mental 


4S4  MENTAL  HYGIENE 

deficiency  is  provided.  Earlier  treatment  and  the  transfer  of  care  pend- 
ing commitment  from  the  policeman  to  the'  doctor — the  most  urgent 
needs  of  the  insane — are  important  aims  of  this  organization.  The 
lamentable  failure  to  provide  instruction  in  mental  diseases  in  the  medi- 
cal schools  is  being  shown  and  the  means  are  being  suggested  for  remedy- 
ing this  defect  in  medical  edlication.  It  is  a  fact  that  the  number  of 
beds  in  the  institutions  for  the  insane  in  this  country  is  almost  equal  to 
the  numbers  of  beds  in  all  the  general  hospitals  of  the  United  States. 
The  insane  are,  therefore,  the  most  numerous  class  of  the  sick  receiving 
public  care.  As  such,  they  are  entitled  to  a  much  larger  share  of  the  in- 
terest of  every  practitioner  than  they  receive.  Progress  in  every  branch 
of  preventive  medicine  depends  chiefly  upon  the  leadership  of  physicians. 
In  this  particular  field  there  is  need  of  much  wider  interest  on  the  part 
of  the  medical  profession  than  exists  today.  One  of  the  functions  of 
the  National  Committee  for  Mental  Hygiene  is  to  broaden  and  increase 
this  kind  of  interest. 

CONCLUSION 

The  attempt  has  been  made  to  outline  some  of  the  preventable  causes 
of  mental  diseases  and  mental  deficiency  and  to  indicate,  very  broadly, 
possible  preventive  measures.  It  seems  essential  that,  notwithstanding 
the  complexity  of  some  of  the  questions  involved,  the  prevention  of  mental 
diseases  and  mental  deficiency  should  be  considered  in  the  general  ad- 
vance which  is  being  made  against  diseases,  for  it  is  very  closely  related 
to  all  the  other  fields  of  preventive  medicine.  Eecent  advances  in  the 
field  of  psychiatry  have  given  grounds  for  encouragement,  for,  if  the 
outlook  in  some  directions  is  not  bright  the  accuracy  with  which  the 
part  played  by  certain  causes  is  being  defined  promises  much.  The  fact 
that  it  has  been  definitely  determined  that  there  are  certain  essential 
causes  of  mental  disease  and  mental  deficiency,  and  that  some  of  these 
essential  causes  are  entirely  controllable,  makes  it  imperative  that  pre- 
ventive measures  should  be  energetically  promoted.  At  the  same  time  the 
great  advantages  in  the  promotion  of  mental  efficiency  which  may  result 
from  better  understanding  of  the  nature  and  importance  of  mental  con- 
flicts and  of  the  means  by  which  more  successful  adaptations  may  be 
made  should  lead  to  developments  in  the  constructive  phases  of  mental 
hygiene  which,  in  the  end,  may  prove  the  greatest  service  to  mankind  of 
this  branch  of  hygiene. 

KEFERENCES 

Reports,  reprints,  bibliographies  on  special  phases  of  mental  hygiene 
and  the  publications  of  that  organization  may  be  obtained  without  cost 
from  the  National  Committee  for  Mental  Hygiene,  50  Union  Square,  New 
York  City. 


REFERENCES  455 

General  Subject 

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them.  Boston;  Massachusetts  Society  for  Mental  Hygiene,  1916.  p.  28. 
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456  MENTAL  HYGIENE 

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Principles  of  mental  hygiene  applied  to  the  management  of  children 
predisposed  to  nervousness.  New  York;  National  Committee  for 
Mental  Hygiene,  1911.     p.  15.     Publication  2. 

Bingham,  A.  T.:  What  can  be  done  for  the  maladjusted?  Eeprint  87 
from  Mental  Hygiene,  v.  4,  p.  422-33,  April,  1920. 

BuRNHAM,  W.  H. :  Mental  health  for  normal  chiklren.  Boston;  Massa- 
chusetts Society  for  Mental  Hygiene,  1917.     Leaflet  A. 

Campbell,  C.  M.  :  Experiences  of  the  child ;  how  they  affect  character  and 
behavior.  Eeprint  83  from  Mental  Hygiene,  v.  4,  p.  312-19,  April, 
1920. 

Nervous  children  and  their  training.  Eeprint  44  from  Mental  Hy- 
giene, V.  3,  p.  16-23,  Jan.,  1919. 

White,  W.  A. :  Childhood ;  the  golden  period  for  mental  hygiene.  Ee- 
print 81  from  Mental  Hygiene,  v.  4,  p.  257-67,  April,  1920. 

Mental  hygiene  of  childhood.  Boston;  Little,  Brown  &  Co.,  1919. 
p.  193. 

Military  Psychiatry 

Bailey,  Pearce:     War's  big  lesson  in  mental  and  nervous  disease.     Reprint 

from  New  York  Times,  Sept.  14,  1919.     p.  10. 
MacCurdy,  J.  T. :     War  neuroses.     Eeprint  from  Psychiatric  Bulletin,  v. 

2,  p.  243-354,  July,  1917. 
Salmon,  T.  W.  :     Care  and  treatment  of  mental  diseases  and  war  nei;roses 

("shell  shock")  in  the  British  Army.     New  York;  National  Committee 

for  Mental  Hygiene,  1917.     p.  117. 


REFERENCES  457 

SaIiMOn,  T.  W.  :     Future  of  psychiatry  in  tlie  army.     Reprint  I'roni  Military 

Surgeon,  v.  47,  p.  200-07,  Auji.,  1920. 
Schwab,   S.    I.:     Influence   of  war  upon   concepts   of   mental   diseases   and 

neuroses.     Reprint  98  from  Mental  Hygiene,  v.  4,  p.  654-69,  July,  1920. 
War   neuroses  a.s   physiologic   conservations.     Reprint   from    Archives 

of  Neurology  and  Psychiatry,  v.  1,  p.  579-G35,  May  1,  1919. 

Immigration  and  Mental  Hygiene 

Glueck,  Bernard:  The  mentally  defective  immigrant.  Reprint  from 
New  York  Medical  Journal,  v.  98,  p.  760-66,  Oct.  18,  1913. 

Paton,  Stewart  :  Memorandum  on  immigration  and  mental  hygiene,  pre- 
sented to  the  President  of  the  United  States,  January  22,  1915. 

Salmon,  T.  W.  :  Insanity  and  the  immigration  law.  Reprint  from  New 
York  State  Hospital  Bulletin,  new  series,  v.  4,  p.  379-98,  Nov.,  1911. 

Williams,  H.  S.  :  Immigration  and  the  prevention  of  insanity.  New  York 
State  Hospital  Bulletin,  new  series,  v.  8,  p.  93-102,  May,  1915. 

Williams,  L.  L.  :  The  medical  examination  of  mentally  defective  aliens; 
its  scope  and  limitations.  Reprint  from  American  Journal  of  In- 
sanity, V.  71,  p.  257-68,  Oct.,  1914. 

Societies  for  Mental  Hygiene 

Barker,  L.   F.  :     First  ten  years   of  the  National   Committee  for  Mental 

Hygiene.     Reprint  No.  39  from  Mental  Hygiene,  v.  3,  p.  240-52,  April, 

1918. 
Beers,  C.  W.  :     Purposes,  plans  and  work  of  state  societies  for  mental 

hygiene.     New  York;  National  Committee  for  Mental  Hygiene,  1915, 

p.    32.     Publication   7. 
Stedman,  H.  R.  :     A  program  of  practical  measures  for  mental  hygiene 

work.     Reprint  from  Boston  Medical  and  Surgical  Journal,  v.   170, 

p.  185-90,  Feb.  5,  1914. 


SECTION  III 
PUBLIC  HEALTH  MEASURES  AND  METHODS 

CHAPTER  I 
SOME  GENEEAL  CONSIDEEATIONS 

Sources  of  Infection. — There  are  two  great  sources  of  the  commu- 
nicable diseases  of  man,  viz.:  (1)  man  himself,  and  (2)  the  lower 
animals.  Most  of  the  communicable  diseases  of  man,  especially  those 
which  occur  in  epidemic  form,  are  peculiar  to  man.  This  is  the  case 
with  typhoid  fever,  cholera,  leprosy,  malaria,  yellow  fever,  syphilis, 
mumps,  measles,  scarlet  fever,  typhus  fever,  infantile  paralysis,  small- 
pox, chickenpox,  relapsing  fever,  dengue,  and  even  tuberculosis  in  large 
part.  It  is  quite  true  that  some  of  these  infections  may  be  communi- 
cated to  the  lower  animals  under  experimental  conditions,  but  they  do 
not,  as  a  rule,  occur  in  them  under  natural  conditions.  In  other  words, 
most  of  the  communicable  diseases  from  which  man  suffers  are  specific 
for  man;  the  degree  of  specificity  varying  slightly  with  the  different  in- 
fections. 

It  is,  therefore,  plain  that  man  is  the  great  source  and  reservoir  of 
human  infections.  Man  is  man's  greatest  foe  in  this  regard.  The  fact 
that  most  of  the  communicable  diseases  must  be  fought  in  the  light  of 
an  infection  spread  from  man  to  man  is  one  of  the  most  important 
advances  in  preventive  medicine.  This  new  thought  has  crystallized 
out  of  a  mass  of  work  in  the  sanitary  sciences  during  the  past  decade, 
especially  from  researches  upon  tuberculosis,  typhoid  fever,  cerebrospinal 
meningitis,  and  other  communicable  diseases.  Formerly,  sanitarians 
regarded  the  environment  as  the  main  source  of  infection.  We  now 
know  that  water,  soil.  air.  and  food  may  be  the  vehicles  by  which  the 
viruses  of  the  communicable  diseases  are  sometimes  transferred — that  is, 
they  are  media  of  conveyance  rather  than  sources  of  infection.  Most  of 
the  microorganisms  causing  the  communicable  diseases  of  man  are  frail 
and  soon  die  in  our  environment,  as  in  the  air,  soil,  or  water.  Most  of 
them  are  obligate  pathogens  and  cannot,  or  do  not,  grow  and  multiply 
under  the  adverse  conditions  of  our  environment. 

From  the  lower  animals,  particularly  the  domesticated  animals,  man 
contracts  a  number  of  infections.     Thus  we  contract  rabies  and  echino- 

459 


460    PUBLIC  HEALTH  MEASUEES  AND  METHODS 

coccus  cysts  from  the  dog ;  plague  from  the  rat ;  glanders  from  the  horse ; 
trichinosis  from  hogs ;  anthrax  from  cattle ;  malta  fever  from  goats ;  foot- 
and-mouth  disease  from  cattle;  tuberculosis,  in  part,  from  cattle;  tape- 
worms and  other  animal  parasites  from  the  meat  of  fish,  fowl,  and 
mammals.  Various  skin  parasites  are  also  contracted  from  the  lower 
animals,  as  ringworm  from  cats,  fleas  from  dogs,  etc.  The  number  of 
these  diseases  ^  and  the  extent  of  their  ravages  are  notably  less  than  those 
contracted  from  man  himself. 

The  association  between  man  and  the  domestic  animals  is  intimate, 
and  the  contact  with  rats,  mice,  and  vermin  is  much  closer  and  more 
frequent  than  we  suspect.  While  man  contracts  several  infections  from 
such  relations,  animals  on  the  other  hand  contract  a  few  diseases  from 
man,  such  as  trichinosis.  Taenia  solium.  Taenia  saginata,  and  cowpox. 

The  fact  that  most  infections  are  spread  rather  directly  from  man 
to  man  brings  in  the  forces  of  sociology  to  aid  those  of  preventive 
medicine. '  The  task  of  preventive  medicine  is  rendered  much  more 
difficult  from  the  fact  that  most  infections  depend  upon  the  control  of 
man  himself.  We  ruthlessly  wage  war  against  insects  or  against  in- 
fected food  or  water.  In  other  words,  we  can  arbitrarily  control  our 
environment  to  a  very  great  extent,  but  the  control  of  man  himself 
requires  the  consent  of  the  governed.  Thus,  it  is  easier  to  stamp  out 
yellow  fever  than  to  control  typhoid  fever.  It  is  easier  to  suppress 
malaria  than  syphilis,  rabies  than  influenza,  trichinosis  than  measles. 
Cattle  appear  to  be  mutely  thankful  when  protected  by  inoculation 
against  blackleg  or  anthrax,  but  man  rebels  against  one  of  the  best 
of  all  specifics — vaccination  against  smallpox.  The  fact  that  man  is 
the  chief  source  and  reservoir  of  most  of  his  own  infections  adds  greatly 
to  the  scope  and  difficulties  of  public  health  work  and  often  makes  the 
prevention  of  disease  dependent  upon  social  and  economic  changes.  In 
this  sense  preventive  medicine  is  a  very  important  factor  in  sociology. 

Modes  of  Transference. — The  viruses  of  the  communicable  diseases 
may  take  various  routes  of  transference  from  man  to  man  or  from 
animal  to  man.  These  routes  are  spoken  of  as  the  modes  of  infection, 
the  modes  of  transference,  or  sometimes  as  the  vehicles  of  infection. 
Formerly  they  were  spoken  of  as  the  "channels  of  infection,^'  but  now 
we  restrict  that  term  to  the  special  channels  by  which  the  infection 
enters  the  body.  Thus,  the  channel  of  infection  in  tuberculosis  may  be 
the  respiratory  tract,  the  digestive  system,  or  the  skin;  whereas  the 
mode  of  infection  is  from  tuberculous  sputum,  either  by  direct  contact 
or  through  the  air,  as  in  droplet  infection,  or  through  milk  or  some 
other  vehicle. 

The  modes  of  transference  may  be  grouped,  for  convenience,  under 

*A  list  of  the  diseases  of  animals  associated  with  human  diseases  is  given 
by  Davis  in  Science,  Sept.  8,  1916,  N.  S.  XLIV,  1132,  p.  339. 


SOME  GENERAL  CONSIDERATIONS  461 

three  general  heads:  (1)  direct,  (2)  indirect,  and  (3)  through  an  in- 
termediate host.  In  the  great  majority  of  eases  the  virus  is  transferred 
more  or  less  directly  by  what  is  now  known  as  contact  infection.  In 
many  instances  the  virus  is  transferred  indirectly  through  water,  food, 
soil,  air,  etc.  In  a  large  group  of  diseases  the  transfer  is  through  an 
intermediate  host  which  furnishes  the  growing  list  of  insect-borne 
diseases. 

The  transfer  is  usually  quite  direct  from  one  person  to  the  next.  The 
agents  of  infection,  as  a  rule,  do  not  travel  far.  The  danger  diminishes 
inversely  as  "the  cube  of  the  distance.'*  However,  viruses  may  be 
spread  broadcast  in  water  and  milk;  they  are  also  transported  great 
distances  in  the  host  along  the  routes  of  trade  and  travel,  by  cases 
and  carriers. 

Contact  Infection. — "Contact  infection"  is  a  convenient  term  in- 
tended to  include  a  group  of  circumstances  in  which  infection  is  spread 
more  or  less  directly  from  person  to  person.  Contact  infection  assumes 
a  quick  transfer  of  fresh  infective  material.  Actual  contact  between 
the  two  individuals  is  not  necessary,  but  the  conveyance  is,  nevertheless, 
pretty  close  in  time  and  space.  Contact  infection  alone  may  be  respons- 
ible for  epidemic  outbreaks,  even  in  the  case  of  such  a  disease  as  typhoid 
fever. 

The  diseases  in  which  contact  infection  plays  a  dominant  role  are 
those  in  which  the  virus  leaves  the  body  in  the  discharges  from  the 
mouth  and  nose,  as  tuberculosis,  diphtheria,  scarlet  fever,  measles,  in- 
fluenza, common  colds,  cerebrospinal  meningitis,  whooping-cough, 
mumps,  etc.  Contact  infection  also  plays  a  large  role  in  diseases  in 
which  the  virus  leaves  the  body  in  the  fecal  and  urinary  discharges,  as 
in  typhoid,  cholera,  dysentery,  and  other  intestinal  infections. 

Contact  plays  a  dominant  part  in  such  diseases  as  syphilis,  gonorrhea, 
skin  and  other  infections  having  open  sores  on  the  surface  of  the  body. 
In  contact  infection  the  virus  may  be  transferred  from  man  to  man 
directly  by  actual  contact,  as  in  kissing,  or  more  indirectly  upon  soiled 
hands,  contaminated  towels,  or  infected  cups,  spoons,  toys,  remnants 
of  food,  and  other  objects  which  have  recently  been  mouthed  or  handled 
by  the  infected  person.  Droplet  infection  is  also  included  under  the 
convenient  term  "contact."  As  a  matter  of  fact,  the  ways  by  which  the 
infection  may  be  transferred,  and  still  be  considered  contact  infection, 
are  numerous  and  varied.  In  every  instance,  however,  the  transfer  is 
brought  about  by  pretty  close  association  with  the  infected  person. 

Indirect  Infection. — A  large  group  of  diseases  are  conveyed  in- 
directly from  person  to  person  through  water,  food,  soil,  and  fomites. 
Diseases  may  be  conveyed  great  distances  by  means  of  food  or  water; 
they  are  never  conveyed  long  distances  through  the  air.  In  the  large 
majority  of  the  diseases  contracted  by  indirect  infection  the  virus  is 


462    PUBLIC  HEALTH  MEASURES  AND  METHODS 

taken  into  the  system  through  the  mouth  and  discharged  from  the  body 
in  the  feces.  The  best  examples  of  this  class  are  typhoid  fever,  cholera, 
and  dysentery.  The  relation  of  soil,  food,  water,  air,  and  our  environ- 
ment to  disease  is  discussed  separately. 

The  insect-borne  diseases  form  a  large  and  important  group,  which 
are  fully  discussed  in  Chapter  IV,  page  259. 

Carriers. — By  the  term  "carrier"  we  understand  a  person  who  is 
harboring  a  pathogenic  microorganism,  but  who,  nevertheless,  shows  no 
signs  or  symptoms  of  the  disease.  Thus  a  person  may  have  diphtheria 
bacilli  in  the  nose  and  throat,  but,  nevertheless,  be  in  good  health. 
The  same  is  true  with  the  pneumococcus,  the  meningococcus,  strepto- 
coccus, and  many  other  microorganisms.  Persons  may  have  typhoid 
bacilli,  cholera  vibrio,  or  hookworms  in  their  intestinal  tract  without 
showing  manifestations  of  these  parasites.  Furthermore,  persons  may 
have  Plasmodia  in  their  blood  or  spleen  without  having  clinical*  malaria, 
and  so  on  through  a  long  list  of  infections. 

Persons  who  harbor  pathogenic '  bacilli  without  showing  symptoms 
are  known  as  "bacillus  carriers,"  those  who  harbor  protozoa  are  known 
as  "protozoon  carriers,"  etc.  Carriers  may  be  acute  or  temporary, 
chronic  or  permanent,  convalescent,  passive  or  active,  intermittent,  intes- 
tinal, oral,  urinary,  etc.    These  terms  are  defined  on  page  540. 

The  demonstration  that  many  persons  are  carriers  has  thrown  a 
new  light  upon  the  control  of  the  communicable  diseases.  With  the 
new  facts  has  come  a  realization  of  added  difficulties.  Carriers  can 
only  be  detected  by  painstaking  laboratory  examinations.  When  dis- 
covered their  control  is  as  difficult  as  it  is  important.  We  cannot 
lightly  imprison  persons  in  good  health,  even  though  they  are  a  menace 
to  others,  especially  in  the  case  of  breadwinners.  In  some  infections 
there  are  so  many  carriers  that  it  would  require  military  rule  to  carry 
out  such  a  plan.  Fortunately  in  most  cases  absolute  quarantine  is  not 
necessary.  Sanitary  isolation  is  sufficient.  Thus  the  danger  from  a 
typhoid  carrier  may  be  neutralized  if  the  person  exercises  scrupulous 
and  intelligent  cleanliness,  and  is  not  allowed  to  handle  food  intended 
for  others.  Such  a  person  might  well  engage  as  carpenter,  banker,  seam- 
stress, etc.,  without  endangering  his  fellowmen. 

The  fact  that  carriers  exist  in  a  large  number  of  diseases  makes 
their  suppression  one  of  great  practical  difficulty.  The  cure  of  carriers 
is  one  of  the  pressing  problems  in  preventive  me^dicine.  One  hopeful 
feature  of  the  carrier  situation  is  that  their  number  may  be  diminished 
by  isolating  and  diminishing  the  cases  of  the  corresponding  disease. 
Thus,  the  number  of  typhoid  carriers  falls  off  sharply  as  a  result  of  any 
successful  measure  directed  only  against  the  clinical  cases.  The  facts 
concerning  carriers  have  been  discussed  separately  under  each  disease  in 
which  they  occur. 


SOME  GENERAL  CONSIDERATIONS  463 

Missed  Cases. — By  missed  cases  we  understand  mild  and  atypical 
instances  of  disease  which  are  not  reco^ized  clinically.  Almost  all 
diseases  vary  greatly  in  severity.  Thus  we  have  walking  typhoid  and 
ambulant  plague.  Wiiooping-cough,  scarlet  fever,  yellow  fever,  influ- 
enza, and  most  other  infections  may  be  so  mild  that  they  escape  notice. 
Even  the  patient  himself  may  not  know  he  is  sick.  These  mild  cases  go 
to  school,  ride  in  street  cars,  attend  tiieaters,  continue  at  their  usual  work, 
in  crowded  factories  and  other  places,  handle  our  food,  eat  at  restaurants,' 
and  thus  spread  infection.  It  is  now  well  known  that  missed  cases  are  a 
prolific  source  of  spreading  the  infection  of  many  of  the  communicable 
diseases;  they  form  an  important  factor  in  preventive  medicine. 

Channels  of  Infection. — There  are  numerous  channels  by  which 
infection  may  enter  the  body.  These  are  usually  grouped  under  three 
headings:  (1)  the  respiratory  tract,  (2)  the  digestive  tract,  and  (3) 
through  the  skin.  Perhaps  90  per  cent,  of  all  infections  are  taken  into 
the  body  through  the  mouth.  They  reach  the  mouth  in  water,  food, 
fingers,  dust,  and  upon  the  innumerable  objects  that  are  sometimes 
placed  in  the  mouth.  The  fact  that  the  great  majority  of  infections 
enter  by  way  of  the  mouth  gives  scientific  direction  to  personal  hygiene. 
Sanitary  habits  demand  that  the  hands  should  be  washed  after  defeca- 
tion and  always  before  eating,  and  fingers  should  be  kept  away  from  the 
mouth  and  nose,  and  that  no  unnecessary  objects  should  be  mouthed. 
All  food  and  drink  should  be  clean  and  thoroughly  cooked.  These  simple 
precautions  alone  would  prevent  many  a  case  of  infection. 

Viruses  taken  in  by  the  mouth  and  nose  do  not  necessarily  cause 
respiratory  infections.  Thus,  the  viruses  of  cerebrospinal  fever  and 
infantile  paralysis  enter  the  system  by  the  mouth;  so  also  with  typhoid 
fever,  dysentery,  cholera  and  other  intestinal  infections. 

"Contagious"  and  "Infectious." — These  are  popular  terms  which 
lack  scientific  precision.  The  words  have  been  used  in  very  diverse 
senses. 

A  contagious  (contingere,  to  touch)  disease  is  one  that  is  readily 
communicable — in  common  parlance,  "catching."  Formerly  a  con- 
tagious disease  was  considered  as  one  which  is  caught  from  another  by 
contact,  by  the  breath,  or  by  effluvia.  A  contagious  disease  implies  direct 
or  personal  contact.  If  contagious  diseases  are  limited  to  those  con- 
tracted by  direct  contact  or  touch,  as  the  etymology  of  the  word  signifies, 
only  sj'philis  and  diseases  similarly  contracted  would  be  contagious.  As 
a  matter  of  fact,  smallpox,  measles,  and  influenza  are  types  of  con- 
tagious diseases,  as  the  term  is  now  usually  understood. 

An  infectious  (inficere,  to  put  in,  dip  in,  or  mix  in)  disease  is  usually 
considered  as  one  not  conveyed  directly  and  obviously,  as  in  the  case  of 
contagion,  but  indirectly  through  some  hidden  influence  or  medium.  In 
the  days  when  specific  febrile  diseases  were  regarded  as  caused  by  mias- 


464  PUBLIC  HEALTH  MEASUEES  AND  METHODS 

mata  and  noxious  effluvia,  the  terms  "infectious"  and  "miasmatic"  dis- 
eases were  more  or  less  synonymous.  Typhoid  fever  was  often  taken  as 
a  type  of  an  infectious  disease.  Malaria  was  the  type  of  a  miasmatic 
disease. 

These  distinctions  are  entirely  artificial,  and  serve  no  useful  pur- 
pose. Most  of  the  communicable  diseases  may  be  transmitted  from  the 
sick  to  the  sound  in  several  ways.  Infectious  diseases  may  be  contagious, 
and  contagious  diseases  are  infectious.  Dividing  diseases  into  those 
which  are  contagious  and  those  which  are  infectious  entirely  leaves  out 
of  consideration  the  important  class  of  insect-borne  diseases.  The  terms 
contagious  and  infectious  have  always  lacked  scientific  precision  and 
have  been  the  source  of  some  confusion.  The  word  "communicable" 
is  a  much  better  term  and  should  be  given  preference. 

A  communicable  disease  is  one  caused  by  a  specific  virus  transferred 
in  a  great  variety  of  ways.  The  term  "communicable"  ignores  the  mode 
of  transference.  There  is  a  great  difference  in  the  degree  of  communi- 
cabiiity ;  some  diseases  are  readily  -  communicable,  others  transmitted 
with  difficulty.  The  evidences  of  communicability  are  not  so  obvious  in 
chronic  infections,  such  as  tuberculosis,  or  in  diseases  with  a  long  period 
of  incubation,  such  as  typhoid  fever.  The  relationship  between  one 
case  and  the  next  is  often  far  removed  m  time  and  space.  If  tuberculosis 
were  an  acute  infection  like  diphtheria  it  would  be  popularly  regarded 
as  being  just  as  contagious  as  that  disease. 

Epidemic,  Endemic,  Pandemic,  and  Prosodemic. — A  disease  is  said 
to  be  epidemic  (epi,  on,  upon,  and  demos,  people)  when  it  is  common 
to  or  affecting  a  large  number  of  persons  in  a  community  in  a  short 
time.  A  disease  which  spreads  rapidly  and  attacks  many  people  at  the 
same  time  is  usually  said  to  be  epidemic.  An  epidemic  involves  the 
conception  of  time,  place  and  numbers. 

A  disease  is  said  to  be  endemic  (en,  in,  demos,  people)  when  it 
is  peculiar  to  a  district  or  particular  locality,  or  limited  to  a  class  of 
persons.  An  endemic  disease  is  one  which  is  constantly  present  to  a 
greater  or  less  degree  in  any  place.  An  endemic  disease  smolders, 
whereas  an  epidemic  bursts  into  flames.  A  sporadic  (occurring  singly) 
disease  is  one  in  which  a  few  scattering  cases  occur  now  and  then. 

Endemic  diseases  are  apt  to  flare  up  and  become  epidemic.  Insect- 
borne  diseases  are  the  best  examples  of  endemicity,  as  their  prevalence 
is  strictly  limited  by  the  geographic  distribution  of  the  intermediate 
host.  Yellow  fever  has  long  been  endemic  in  Havana,  cholera  in  India, 
typhoid  fever  in  Washington,  and  plague  in  Tibet. 

These  terms  not  only  lack  precision,  but  are  variously  conceived  and 
differently  defined.  Thus  typhoid  fever  was  said  to  prevail  in  Boston, 
but  a  similar  number  of  cases  in  Berlin  would  have  been  regarded  as  an 
epidemic,     For  the  purposes  of  maritime  quarantine  a  disease  is  con- 


SOME  GENERAL  CONSIDERATIONS  465 

sidered  epidemic  if  there  is  more  than  one  focus  of  infection;  that  is, 
if  several  cases  occur  which  have  no  apparent  connection  with  each 
other.  Strictly,  therefore,  according  to  this  definition,  two  cases  may 
constitute  an  official  epidemic  and  the  port  would,  therefore,  be  regarded 
as  infected. 

It  is  not  feasible  to  state  just  how  many  cases  of  a  disease  constitute 
an  epidemic.  Ordinarily  a  few  cases  of  a  communicable  disease  in  a 
village  or  small  town  is  not  regarded  as  an  epidemic;  however,  five 
cases  of  typhoid  fever  in  Podunk  (population  1,000)  is  the  equivalent 
of  5,000  cases  in  a  city  of  1,000,000.  By  the  same  token,  one  or  two 
cases  in  a  small  village  Mould  proportionately  constitute  an  epidemic 
of  unknown  magnitude  in  a  metropolis. 

"Pandemic"  (pan,  all,  demos,  peoplej  is  a  term  used  to  describe  a 
disease  which  is  more  or  less  epidemic  everywhere.  Pandemics  affect  a 
large  numlicr  of  people  in  a  large  number  of  countries  at  the  same  time. 
Thus  there  have  been  four  great  pandemics  of  plague,  when  it  spread 
to  the  four  quarters  of  the  globe.  In  1889-90  and  again  in  1918-19  in- 
fluenza was  pandemic.  It  is  not  usual,  although  quite  proper,  to  regard 
tuberculosis,  syphilis  and  typhoid  fever  as  pandemic. 

Sedgwick  proposes  the  term  " prosodemic"  (proso,  through,  demos, 
people)  to  take  the  place  of  the  unsatisfactory  word  "endemic."  Proso- 
demic  suggests  the  creeping  or  smoldering  of  a  disease  which  is  being 
communicated  from  person  to  person  through  the  community  by  various 
means,  but  especially  by  contact. 

Fomites  (from  fomes,  touch-wood  or  tinder)  is  defined  as  any  sub- 
stance capable  of  absorbing,  retaining,  or  transporting  infectious  germs. 
Fomites  usually  refers  to  inanimate  things,  such  as  bedding,  clothing, 
etc.  The  term  was  especially  used  in  connection  with  yellow  fever,  in 
which  the  greatest  variety  of  objects,  such  as  a  lock  of  hair,  the  false 
bottom  of  a  trunk,  cofi^ee  sacks,  a  mattress,  and  letters  were  said  to  be 
the  fomites  which  touched  off  an  epidemic.  Woolen  clothing  or  the 
doctor's  beard  are  popular  and  supposedly  dangerous  examples  of 
fomites. 

The  importance  of  inanimate  objects  as  vectors  of  pathogenic  micro- 
organisms is  assuming  a  minor  role  in  the  minds  of  most  sanitarians. 
Thus  we  no  longer  think  of  such  objects  as  books,  umbrellas,  floors,  walls, 
curtains,  and  furniture  as  likely  to  transmit  the  virus  of  disease.  We 
know  that  most  of  the  pathogenic  bacteria  soon  die  when  exposed  to 
dryness  and  other  adverse  conditions  of  environment.  We  now  concen- 
trate our  efforts  more  upon  handkerchiefs,  towels,  bed  and  body  linen, 
drinking  cups,  remnants  of  food,  toys,  pencils,  table-ware,  and  other 
objects  that  have  recently  been  mouthed  by  the  infected  individual.  Such 
fomites  may  readily  transfer  fresh,  live  and  virulent  virus  from  one  per- 
son to  the  next. 


466 


PUBLIC  HEALTH  MEASURES  AND  METHODS 


RELATIVE   VALUES   OF   PUBLIC    HEALTH   WORK 


It  is  evidently  impossible  to  express  with  mathematical  precision  the 
relative  importance  of  different  public  health  procedures.  Nevertheless, 
efficient  administration  requires  a  sense  of  proportion.  The  relative  val- 
ues of  health  activities  vary  with  location,  character  of  population,  stage 
of  civilization,  etc.  In  many  communities  malaria,  dysentery,  hookworm 
disease,  plague  or  yellow  fever  will  need  chief  consideration.  A  well 
sewered  city  can  appropriate  money  for  lines  of  work  which  in  less  fortu- 
nate places  must  be  devoted  to  the  never  ending  task  of  privy  sanitation. 

Sanitation  or  municipal  housecleaning  logically  comes  first;  this  ac- 
complished, hygiene  must  occupy  most  of  the  attention  of  the  public 
health  administrator.  Disease  pretention  is  important,  but  health  con- 
servation is  fundamental;  education  is  essential,  but  scientific  research 
is  basic.  The  ideal  of  preventive  medicine  is  to  build  towards  depart- 
ments dealing  with  health  rather  than  departments  dealing  with  disease. 

In  what  way  should  the  appropriations  for  the  health  department  be 
expended  so  aS' to  save  the  most  lives  and  prevent  the  most  sickness? 
Chapin  ^  answers  this  question  in  the  following  table : 

RELATrVE   VALUES   OF   HEALTH   WORK 

'Medical  Inspection 100 

Nursing  

Hospitalization 50 

Immunization 50 

Venereal  diseases 20 

rNurses 60 

Tuberculosis -l  Dispensaries  40 

iHospitalization 40 

School  Inspection 80 

Nurses 80 

Supervision    of    Mid- 
wives  10 

Boarding  houses 5 

Milk  stations 5 

Consultations .  20 

Prenatal  clinics 10 

Privy  Sanitation 110 

Housing 20 

Plumbing 10 

Nuisances   10 

-Fly  and  Mosquito  control 10 

/Adulteration  0 

1  Sanitation  10 

/Adulteration  3 

\  Sanitation  17 

Care  of  sick  poor 50 

Laboratory   50 

Education   . 80 

Vital  Statistics 60 

1000 
•J.  A.  M.  A.,  July  14,  1917,  p.  90,  LXIX,  2.    • 


Communicable 
Diseases 


Child  Hygiene. 


Sanitation , 


Infant  Mortality. 


Food 
Milk. 


RELATIVE  VALUES  OK  PUBLIC  HEALTH  WORK      4G7 

The  figures  given  in  Ww  schcilulc  arc  intended  to  indicate  the  real 
health  conserving  vahic  of  certain  coimiiDii  fiiiictions  of  municipal  health 
departments.  For  many  activities  \vc  have  no  measurement,  hut  only 
guesses. 

Schneider'  calculates  the  relative  values  of  the  various  puhlic  health 
activities,  as  follows : 


CONTROL  OF  COMMUNICABLE  DISEASES: 

Tuberculosis   |  12.1 

Venereal  diseases 6.6 

All   others j  25.3 

Infant   hygiene 20.3 

Privy  and  well  sanitation 3.5 

Milk  control 2.7 

Fly  and  mosquito  suppression 2.4 

Food  sanitation 0.1 

Inspection  of  school  children 7.0 

Vital  Statistics 5.0 

Education    5.0 

Dispensary  and  clinics 5.0 

Laboratory   5.0 


Total   100.0 

It  is  interesting  to  note  that,  in  Schneider's  opinion,  the  control  of 

communicable  diseases  and  infant  hygiene  work  might  profitably  con- 
stitute two-thirds  of  the  activities  of  the  health  department. 

Brooks  *  of  the  ISTew  York  State  Department  of  Health  uses  the  fol- 
lowing score : 

1.  Communicable  diseases : 

(a)  Tuberculosis   60 

(b)  Other  than  tuberculosis   80 

2.  Laboratory  facilities,  local  or  State,  fully  utilized   90 

3.  School  inspection   85 

4.  Infant  and  maternal  welfare 90 

5.  Milk  and  food  inspection 80 

6.  Water  supply  90 

7.  Sewage,  garbage  and  manure 80 

8.  Record  keeping   90 

9.  Public  health  education   100 

10.  Appropriation    .• . .  100 

11.  Enforcement    of    regulations    regarding    barber    shops,    common 

towels  and  eating  and  drinking  utensils   20 

12.  Special  work  along  new  or  unusual  lines  or  especially  efficient 

work  or  good  results  with  old  methods 35 

^Amer.  Jour.  P.  H.,  VI,  9.  Sept.,  1916. 

*  Health  News,  Monthly  Bull.,  N.  Y.  State  Dep't.  Health,  May,  1919. 


468 


PUBLIC  HEALTH  MEASUEES  AND  METHODS 


Olson  ^  proposes  the  following  score  card  for  measuring  the  efficiency 
of  local  health  officers. 


SCORE  CARD— FOR  SCORING  THE  EFFICIENCY  OF  LOCAL 
HEALTH  OFFICERS 

1.  .  Activities 


Character  of  Activity 


4. 

5. 

6. 

7. 

8. 

9. 
10. 
XL 
12. 

13. 
14, 

15. 
16. 
17. 
18. 

19. 
20. 
21. 


Communicable  diseases:  Suppression  and  prevention. ... 

Laboratory  diagnosis:  Collection  and  transmission  of 
specimens  for  diagnosis  and  investigation.  Distribu- 
tion of  antitoxins  and  serums 

Education  of  public:  Exhibits,  lectures,  circulars,  news- 
paper  articles,   etc 

Vital  statistics 

Coordination  of  extraneous  health  agencies 

Concurrent   disinfection 

Infant  and  maternal  welfare  work 

Public  health  nursing 

Control  of  water  supplies ._ 

Inspection  and  control  of  milk  supplies  and  dairies.... 

Occupational  disease:   Prevention  and  control 

Medical  inspection  of  school  children  and  correction  of 
defects    

Mental  hygiene    

Control  of  such  preventable  diseases  as  heart  and  kidney 
diseases,  etc 

Clerical  work :   Correspondence,  records,  and  reports .... 

Sewage  disposal    

Attendance  at  conferences,  board  of  health  meetings,  etc.. 

Food  and  meat  inspections  and  control  of  slaughter 
houses,  butcher  shops,  and  grocery  stores 

Inspection  of  public  buildings 

Terminal  fumigation    

Investigation  and  abatement  of  nuisances 

Total 


Score  in  Points 


Perfect      Allowed 


18 


10 


7 
6 
6 
6 
5 
4 
4 
4 

4 
3 

3 
3 
3 
3 

1 

1 

1/2 


100 


2.     Equipment 


Nature  of  Equipment 


Score  in  Points 


1.  Telephone    

2.  Transportation     

3.  Clerk    

4.  Office 

5.  Report  cards: 

a.  From    physicians 

b.  To  State  board  of  health 

6.  Quarantine  placards 

7.  Vaccine  and  antitoxins  or  facilities  for  obtaining  same.. 

8.  Record  books  or  filing  cases 

9.  Literature  for  self-education  and  reference 

10.  Literature  for   distribution 

11.  Fumigants  or  facilities  for  obtaining  same 

Total  


^V.  8.  Public  Health  Rpts.,  Jan.   14,  1921,  Vol.  XXXVI,  No.  23,  p.  31. 


RELATIVE  VALUES  OF  PUBLIC  HEALTH  WORK      469 

A  Score  for  Health  Activities.* — Tlu'  New  'h'ork  State  l)('|tartment  of 
Health  has  {)rej)are(I  an  activities  score  for  cities  with  a  population  of 
from  t?ri,0()0  to  175,000  iiilmhitaiits.  Of  a  j)()ssihle  1,000  points  for  per- 
fect, adequate  public  licallli  niiisini:-  s('i-\  ice  coiinfs  7');  other  rollo\v-u|) 
social  service  10;  ailecpiate  dispeiisai'v  or  clinic  service  70;  hospital 
facilities  for  the  connnunicaljle  diseases  lA;  a  day  nursery  10;  Little 
Mothers'  Leag-ue  10;  y-ood  newspaper  publicity  rojjj-ardinf?  health  mat- 
ters 50;  and  a  physician  in  charge  of  the  infant  welfare  station  15. 
This  gives  a  total  of  285  points  for  activities  in  which  the  nurse  is 
directly  concerned.  In  general  the  score  provides  the  following  dis- 
tribution of  credit: 

Communicable  disease  control: 

Tuberculosis,  perfect  score 60 

Venereal  diseases,  perfect  score YO 

Other  communicable  diseases,  perfect  score 80 

Adeqiuite  laboratory  facilities  and  use  of  same 100 

Infant  and  maternal  welfare • 90 

Milk  and  food  inspection 100 

Water    supply 100 

Sewage,  garbage  and  manure  disposal 40 

Record  keeping 85 

Public  health  education 120 

An  appropriation  of  at  least  50  cents  per  capita  for  health  protection .  .  100 
Eifective  enforcement   of   regulations   governing  barber  shops,   com- 
mon  towels,   drinking   and   eating   utensils 20 

Unusually  meritorious  public  health  work  along  either  new  or  old  lines  35 

Total 1,000 

A  Public  Health  Program.  -The  principal  elements  in  a  comprehen- 
sive public  health  program,  in  ordered  sequence,  may  be  named  as  fol- 
lows: 

1.  Eugenics,  the  principles  of  sound  breeding  and  heredity.  Im- 
munity. 

2.  Maternity  and  the  care,  protection  and  encouragement  of  the 
function  of  motherhood. 

3.  Infant  w^elfare  and  the  reduction  of  infant  mortality. 

4.  The  health  and  development  (physical,  mental  and  moral)  of  the 
school  child  and  adolescent. 

5.  Food  and  nutrition,  the  relation  of  diet  to  growth  and  health. 

6.  Personal  hygiene.     Mental  hygiene. 

7.  Industrial  hygiene,  •  the  health  of  the  worker. 

8.  The  prevention  of  the  communicable  diseases.     Epidemiology. 

9.  The  prevention  of  the  non-communicable  diseases. 

10.  Sanitation,  or  biologic  cleanliness,  including  improved  environ- 
ment.    Sanitary  engineering.     Disposal  of  wastes. 


470    PUBLIC  HEALTH  MEASUEES  AND  METHODS 

11.  Vital  statistics,  the  bookkeeping  of  humanity, 

12.  Education,  the  diffusion  of  knowledge  among  the  people  in  all 
these  matters. 

13.  Kesearch  to  extend  the  boundaries  of  knowledge. 

Successful  public  health  administration  should  be  organized  so  as 
to  include  constructive  work  under  each  of  these  headings.  In  a  broad 
sense,  it  should  also  include  improvements  in  education  for  medical, 
dental,  veterinary,  nursing  and  public  health  practice. 

Org'anization  of  Health.  Departments. — 'The  administration  of  a. 
health  department  should  include  as  much  as  possible  of  the  above 
public  health  program.  Ordinarily,  health  work  falls  under  the  follow- 
ing headings: 

1.  Executive  and  administrative. 

2.  Vital  statistics. 

3.  Communicable  diseases — epidemiology. 

4.  Infant  welfare  and  child  hygiene. 

5.  Food  and  drugs. 

6.  Sanitation. 

7.  Industrial  hygiene. 

8.  Laboratories. 

9.  Education. 

A  health  department  should  have  a  "commissioner  of  health"  or 
"health  officer"  as  executive  head  of  all  activities.  The  chief  executive 
may  have  a  "public  health  council"  or  "advisory  board"  to  approve 
policies  and  regulations,  but  such  boards  should  have  no  executive  duties. 
In  metropolitan  cities  and  states,  the  health  departments  should  have 
skilled  and  trained  heads  for  each  of  the  above  mentioned  departments. 
It  is  sometimes  advisable  to  have  special  departments  for  some  of  the 
major  public  health  problems,  such  as  tuberculosis  or  venereal  diseases; 
or  malaria,  hookworm,  plague,  etc.,  where  such  diseases  prevail. 

The  smallest  health  department  must  contain  all  the  elements  essen- 
tial to  public  health  work,  and  should  consist  of  at  least  one  health 
officer,  one  public  health  nurse  and  one  clerk,  all  full-time  employees. 
The  health  officer  for  small  communities  must  be  epidemiologist,  edu- 
cator, dispensary  and  school  physician,  bacteriologist,  inspector,  executive, 
etc.  He  should  be  free  to  call  upon  expert  advice  when  confronted  with 
an  unusual  situation.  Such  specialists  are  provided  by  both  the  U.  S. 
Public  Health  Service,  by  state  departments  of  health,  bj  universities 
and  other  organizations. 

It  is  a  great  advantage  for  a  number  of  small  communities  to  pool 
their  health  interests  and  resources.  This  has  worked  well  at  Wellesley, 
Massachusetts,  where  five  of  the  neighboring  towns  have  entered  into 


RELATIVE  VALUES  OF  PUBLIC  HEALTH  WORK      471 

a  cooperative  health  organization.  The  plan  has  worked  well  and  should 
be  copied  widely. 

Each  coiint)^  may  have  its  own  health  organization,  and  all  pro- 
gressive states  are  divided  into  sanitary  districts  presided  over  by  a  dis- 
trict health  officer. 

Cost. — The  appropriation  necessary  to  maintain  a  minimum  health 
organization  varies  from  50  cents  to  $1.00  per  capita  per  annum.  For 
a  city  of  10,000  population,  75  cents  per  capita  would  be  sufficient  to 
maintain  a  minimum  organization  as  follows:^ 

One  health  officer $3,000 

One  public  health  nurse 1,200 

One  clerk    1,000 

Salaries    $5,200 

Maintenance    2,300 

Total    $7,500 

All  full-time. 

In  a  city  of  25,000  population,  75  cents  would  hardly  cover  the 
expense,  as  a  city  that  size  should  have  a  small  isolation  bospital.  The 
organization  for  a  city  of  25,000  follows: 

One  health  officer  $3,500 

One  epidemiologist 2,500 

Three  public   health   nurses— $1,200 3,600 

One  milk  inspector 1,500 

One  sanitary  inspector 1,200 

One   statistical   clerk 1,200 

One   stenographer 1,000 

Salaries   $14,500 

Maintenance    4,250 

Total  $18,750 

All  full-time. 

In  this  organization,  the  epidemiologist  performs  the  duties  of  bac- 
teriologist, and  he  divides  the  duties  of  school  inspector  and  dispensary 
physician  with  the  health  officer. 

N"o  provision  is  made  for  the  collection  of  garbage  and  other  city 
wastes,  street  cleaning,  etc.  These  activities  quite  properly  belong  to 
a  separate  department  of  the  city  government. 

In  some  cities  and  states,  the  management  of  public  hospitals,  tuber- 
culosis sanatoria  and  insane  asylums  are  placed  under  the  control  of 
the  health  office.  The  organization  of  health  departments  varies  in  dif- 
ferent parts  of  the  country  to  meet  special  conditions  and  local  tra- 
ditions. 

'  Fox,  C. :  Minimum  Standards  of  Organization  for  Municipal  Health  De- 
partments.   J.  A.  M.  A.,  Sept.  18,  1920,  Vol.  75,  No.  12,  p.  790. 


473 


PUBLIC  HEALTH  MEASURES  AND  METHODS 


THE  MEDIAN  ENDEMIC  INDEX 

In  epidemiological  work,  it  is  essential  that  the  health  officer  have 
some  system  by  which  he  may  compare  the  incidence  of  disease  in  the 
past  with  that  of  the  present.  For  this  purpose,  Dr.  W.  H.  Brown, 
then  Epidemiologist  of  the  Massachusetts  Department  of  Public  Health, 
devised  an  endemic  index  card.  The  endemic  index  was  determined  by 
averaging  the  number  of  reported  cases  for  five  years,  exclusive  of  epi- 
demics, for  the  various  municipalities  of  the  state.  This  average  was 
the  endemic  index.  The  personal  factor,  however,  entered  into  this  de- 
termination as  it  was  necessary  for  the  epidemiologist  to  decide  what 
constituted  an  epidemic. 

To  obviate  this  difficulty,  Hitchcock  and  Carey  of  the  Massachusetts 
Department  of  Public  Health  devised  a  median  endemic  index.  This 
median  endemic  index  is  a  record  of  actual  occurrence  and  takes  into 
consideration  all  cases  reported.  TJie  data  is  arranged  in  arithmetical 
sequence,  and  the  median  selected  as  the  index.  For  example,  the  num- 
ber of  cases  reported  for  the  month  of  January  for  nine  years  was  as 
follows : 


Year 

Diphtheria 

Scarlet  Fever 

1910 

912 
992 
519 
555 
846 
921 
840 
869 
950 

943 

1911 

631 

1912 

583 

1913 

833 

1914 

1  584 

1915 

953 

1916 

948 

191Y 

673 

1918 

609 

By  arranging  these  numbers  in  arithmetical  sequence  and  picking  the 
median  for  the  index,  the  median  indices  for  January  are  found  to  be : 

Diphtheria— 869. 
Scarlet  fever— 833. 

The  monthly  endemic  indices  for  the  various  diseases  are  plotted  on 
a  graph,  and  beside  it  is  placed  a  dial  marked  off  in  suitable  spacing  to 
show  the  daily  increase.  This  is  recorded  by  two  clock  hands,  the 
hour  hand  pointing  to  the  endemic  index  for  the  month  and  the  minute 
hand  progressing  as  cases  accumulate. 

An  endemic  index  card  is  kept  for  each  city  or  town  in  the  state. 
This  card  is  ruled  off  in  six  large  spaces  on  each  side  for  the  months 
of  the  year.    Each  of  these  large  spaces  is  in  turn  ruled  off  into  smaller 


HOUSING  473 

spaces  for  the  days  of  the  months  and  the  diseases  reportable.  The 
number  of  rases  reported  the  previous  year  and  the  endemic  indices 
for  the  various  diseases  are  also  recorded.  As  daily  reports  are  re- 
ceived, they  are  tabulated  in  their  proper  place. 

The  median  index  chart  used  in  conjunction  with  a  spot  map  and 
daily  index  cards  is  a  simple  and  effective  device  whereby  the  daily 
accumulation  of  reported  disease  may  be  watched  and  which  will  show 
at  a  glance  any  sudden  or  unusual  increase. 

HEALTH  CENTERS 

Health  centers  ^  are  local  agencies  where  the  health  activities  of  a 
community  are  administered.  This  concentration  increases  efficiency  and 
promotes  economies.  Health  centers  are  needed  in  metropolitan  cities 
as  well  as  in  country  divstricts;  their  organization,  however,  will  vary 
somewhat  in  large  cities,  in  medium  sized  towns  and  rural  situations. 
Health  centers  are  "clearing  houses"  for  all  hygienic,  sanitary,  medical, 
dental,  nursing  and  other  public  health  activities.  They  also  serve  as 
convenient  places  for  advice  and  information;  they  are  useful  for  pro- 
moting public  health  education  and  they  may  contain  attractive  social 
features. 

One  of  the  faults  with  public  health  administration  is  that  it  is  too 
remote  and  removed  from  the  people  and  their  problems.  Public  health 
centers  correct  this  fault  in  an  admirable  way.  It  is  proper  for  a  health 
center  to  have  facilities  for  prenatal  work,  maternity  care,  baby  hygiene 
station,  child  welfare,  tuberculosis  clinic,  venereal  dispensary,  dental 
service,  nursing  service,  Red  Cross  activities,  mental  hygiene,  distribution 
of  serums,  and  vaccines,  physical  examinations,  surgical  emergencies, 
etc.,  etc.  Health  centers  may  also  serve  as  the  district  office  for  federal, 
state  and  local  health  officials,  as  well  as  for  private  organizations. 
Charity  and  material  relief  should  be  kept  separate  from  such  centers. 

Health  centers  are  the  next  step  in  health  community  service.  Their 
possibilities  are  boundless,  but  their  successful  operation  requires  co- 
operation and  leadership.    Thus  far  there  are  few  types  and  no  models. 

HOUSING 

Housing  has  an  intimate  relation  to  health.  Housing  influences 
morbidity  and  mortality,  but  in  a  rather  indirect  way.  It  is  difficult  to 
separate  the  factors  of  crowding,  personal  habits,  poverty,  food  and  other 
hygienic  and  sanitary  influences  from  the  actual  housing  conditions.  A 
house  after  all  is  only  an  instrument  that  may  be  abused,  thus  a  good 

'  A  symposium  on  the  Health  Center,  Am.  Jour,  of  Public  Health,  March, 
1921,  Vol.  XI,  No.  3,  p.  212. 


474         PUBLIC  HEALTH  MEASURES  AND  METHODS 

house  may  be  crowded  and  unsanitary,  while  a  poor  house  may  be  clean 
and  fairly  adequate.  Good  housing  conditions  facilitate  an  adequate 
supply  of  fresh  air  and  sunshine,  promote  cleanliness  and  dryness,  and 
favor  sanitary  isolation;  good  housing  also  encourages  higher  standards 
of  living,  and  thus  favors  better  personal  hygiene  and  improved  sanita- 
tion of  the  environment. 

Housing  conditions  may  be  taken  as  a  good  index  of  the  general 
sanitary  condition  and  hygienic  habits  of  the  occupants.  Strict  laws  con- 
cerning new  construction  should  be  rigidly  enforced,  especially  with  re- 
spect to  safety,  air  space,  openings  for  air  and  sunshine,  water  supply 
and  disposal  of  wastes,  cellars,  toilets,  kitchens,  etc.  Eegulations  con- 
cerning the  number  of  occupants  and  the  use  of  the  house  should  be 
made  a  matter  of  supervision  through  official  inspection. 

There  is  a  difference  of  opinion  as  to  the  function  of  a  health  officer 
in  relation  to  housing.  In  my  judgment,  it  comes  under  the  purview  of 
good  health  administration,  although  it  is  largely  an  economic  and  social 
problem.  Most  of  the  laws  in  the  United  States  concerned  with  housing 
deal  more  with  structural  safety  than  with  sanitary  requirements. 

The  modern  tendency  is  to  leave  the  country  for  the  city.  About 
one-half  of  our  population  is  urban.  Cities  are  congested  and  crowded, 
and  many  live  in  cells  unfit  for  human  habitation.  The  best  results  in 
health  cannot  be  obtained  and  maintained  when  so  large  a  proportion  of 
our  inhabitants  live  such  a  parasitic  life.  Housing  is  an  index  of  these 
conditions  and  tendencies,  which  favor  the  spread  of  all  communicable 
infections.  Further,  such  artificial  and  unnatural  conditions  of  life 
make  it  difficult  to  maintain  tone,  vitality  and  efficiency. 

Housing  affects  health,  morals  and  progress  both  directly  and  indi- 
rectly. Dark  rooms  favor  the  spread  of  tuberculosis.  Dingy  houses 
make  cleanliness  difficult  and  give  comfort  to  vermin.  Indirectly,  bad 
housing  conditions  may  undermine  resistance  to  disease,  especially 
through  poor  lighting,  bad  ventilation,  and  improper  heating.  The 
present  lack  of  housing  facilities  is  a  serious  sanitary  menace. 

One  of  the  most  important  factors  in  housing  in  relation  to  health 
is  overcrowding.  Strict  regulations  should  be  enforced  by  the  health 
officer  to  prohibit  the  overuse  of  living  and  sleeping  rooms.  Careful 
sanitary  supervision  is  necessary  to  insure  an  abundant  supply  of  good 
water  and  an  adequate  system  of  disposal  of  wastes.  The  health  officer 
should  also  take  cognizance  of  nuisances  often  maintained  both  within 
and  without  houses.  It  is  usually  easier  to  prevent  such  nuisances  thai  \ 
to  abate  them.  The  records  of  the  health  officer  should  show  the 
cases  of  sickness  occurring  in  each  house,  for  much  useful  information 
is  thus  obtained. 

The  general  types  of  dwelling  concerned  in  urban  housing  problems 
are:  (a)  one-family  dwellings,  (b)  two-family  dwellings,  and  (c)  tene- 


EURAL  SANITATION  475 

ments.     The  detached  one-i'aniily  dwelling  with  space  all  around  it  is 
the  ideal. 

Good  housing  includes  a  consideration  of  construction,  site,  soil, 
dryness  and  drainage,  water  and  wastes,  lighting,  heating  and  ventila- 
tion, size,  arrangement  and  use  of  rooms,  facilities  for  cleanliness,  and 
also  the  environment  of  the  structure.  Each  one  of  these  topics  is  dis- 
cussed in  detail  in  other  chapters.     See  index. 

EURAL  SANITATION 

The  country  is  the  weakest  link  in  the  sanitary  chain.  This  is  largely 
due  to  economic  reasons,  with  the  added  handicaps  of  inadequate  organ- 
ization, great  distances,  and  imperfect  education.  Most  rural  health  de- 
partments are  under-manned,  poorly  supported,  and  render  inadequate 
service. 

From  the  standpoint  of  the  communicable  diseases,  our  better  cities 
are  now  much  safer  places  to  live  in  than  country  districts.  Before 
the  days  of  modern  sanitation,  the  cities  had  about  double  the  death 
rates  of  the  country. 

Infection  flows  from  the  country  to  the  city  in  the  water,  milk  and 
food  supplies.  It  is  carried  back  and  forth  in  the  persons  of  cases  and 
carriers.  Opportunities  for  contact  infection  are  much  more  frequent 
among  the  rural  population  than  is  ordinarily  conceived;  disease  trans- 
mitted by  contact  infection  often  spreads  through  sparsely  settled 
country  districts  like  wildfire. 

Eural  dwellings,  schools  and  meeting  houses  are  often  unsanitary, 
crowded  and  dark.  Sewage  disposal  is  apt  to  be  primitive  and  the  con- 
trol of  insects,  rats  and  vermin  difficult  and  neglected.  Heating,  light- 
ing and  ventilation  are  often  defective.  There  is  plenty  of  sunshine  in 
the  fields,  but  often  none  in  the  houses.  Further,  it  is  rather  difficult 
for  each  farmhouse  to  surround  itself  with  the  tidy  environment  equal 
to  that  of  a  city  park.  The  best  medical  service  has  a  tendency  to  desert 
country  practice  for  city  allurements. 

The  farmer's  work  is  fatiguing,  intensive  and  seasonal.  It  often 
requires  undue  exposure  to  wind  and  weather  both  summer  and  winter. 
The  hours  are  long  and  the  conditions  of  work  and  life  not  always  con- 
ducive to  health,  longevity  and  efficiency. 

Over  fifty  per  cent,  of  our  population  is  rural,  but  this  half  receives 
scant  attention.  Eural  sanitation  is  expensive,  but  costs  lees  than  sick- 
ness, with  its  attendant  inefficiency  and  block  to  progress  caused  by 
disease. 

There  should  be  a  full-time  health  officer  in  charge  of  a  county 
or  a  rural  sanitary  district,  with  a  health  center  and  staff  to  carry  on 
the  needed  work.     Hospital,  transportation  and  nursing  services  should 


476  PUBLIC  HEALTH  MEASURES  AND  METHODS 

be  organized   and   provided   in   each  sanitary   district  on   an   economic 


The  method  of  controlling  disease,  disposing  of  wastes,  improving 
housing  and  ventilation  and  the  art  of  sanitary  living  both  in  country 
and  city  are  discussed  in  detail  under  specific  chapters  throughout  this 
book. 

PUBLIC  HEALTH  EDUCATION 

Public  health  education  is  fundamental.  It  must  be  considered 
under  two  aspects:  (1)  Acquisition  of  knowledge  and  (2)  Diffusion  of 
knowledge. 

The  first  involves  researches  in  laboratories,  studies  at  the  bed-side 
and  investigations  in  the  field.  The  demonstrations  of  science  underlie 
all  sound  health  administration  and  are  the  only  safe  guide  for  health 
education.  Special  schools  are  needed  to  prepare  for  public  health  serv- 
ice; and  better  instruction  in  hygiene  and  sanitation  is  called  for  in 
medical  schools. 

In  the  diffusion  of  knowledge  concerning  health  and  the  prevention 
of  diseases,  public  health  authorities  should  take  a  leading  part.  Many 
other  agencies,  however,  assist  in  placing  the  facts  plainly  before  the 
people.  Health  education  should  begin  in  the  home  where  the  develop- 
ing child  is  taught  the  art  of  sanitary  living.  The  schools  should  teach 
the  structure  and  functions  of  the  body,  hygiene  of  the  person  and  san- 
itation of  his  surroundings.  This  is  the  most  important  part  of  the 
curriculum  from  kindergarten  to  university. 

The  popular  methods  in  health  education  are  through  newspapers, 
periodicals,  pictures,  bulletins,  exhibits,  lectures,  movies  and  feature 
campaigns,  such  as  "Health  Week,"  "Baby  Week,"  "Clean-Up  Week," 
etc.  The  doctors  are  also  looked  to  as  guides  and  counselors  in  health 
matters.  Hospitals,  dispensaries,  and  health  centers,  as  well  as  nurses, 
social  service  workers  and  others,  are  effective  and  helpful. 

Cooperation  and  assistance  in  Health  Education  may  be  obtained 
from  the  U.  S.  Public  Health  Service,  from  state  health  departments 
and  local  health  officers;  from  the  Federal  Child  Bureau,  as  well  as  the 
U.  S.  Bureaus  of  Education,  Census  and  Mines;  also  from  the  U.  S. 
Department  of  Agriculture,  The  American  Society  for  the  Study  and 
Prevention  of  Tuberculosis,  The  Eed  Cross,  The  Russell  Sage  Founda- 
tion, The  International  Health  Board,  The  Metropolitan  Life  Insurance 
Company,  The  American  Society  for  Control  of  Cancer,  the  American 
Safety  Council,  The  National  Child  Welfare  Committee  and  other 
agencies. 

It  is  very  important  that  the  facts  stated  in  popular  propaganda 
should  tell  the  truth.  It  is  more  important  to  be  correct  than  to  be  clever. 
Half   truths   are   often    dangerous.     Wrong   teaching   undermines    con- 


INFANT  MORTALITY  477 

fidence  in  health  nutliorities.      It  is  a  question  whether  the  subject  Vi 
dignified  by  the  use  of  cireus  methods,  or  the  antics  of  the  clown. 


INFANT  MORTALITY 

"Infant  mortality  is  the  most  sensitive  index  we  possess  of  social 
welfare.  If  babies  were  well  born  and  well  cared  for,  their  mortality 
would  be  negligible''  (Newsholme). 

Of  every  five  babies  born,  one  dies  before  it  is  able  to  walk  and  talk. 
The  awakening  of  the  world  to  the  consciousness  of  the  immense  and 
needless  sacrifice  of  infant  life  is  recent.  Most  of  it  has  come  since  about 
1870,  as  the  result  of  statistical  studies  showing  how  colossal  has  been 
this  "slaughter  of  the  innocents."  The  reasons  for  regarding  infant 
mortality  as  a  major  public  health  problem  are  humanitarian,  social 
and  economic.  Good  results  in  lessening  infant  mortality  depend  en- 
tirely upon  attacking  the  underlying  causes  with  intelligence.  This  is 
one  of  the  functions  of  every  well  organized  health  department.  Eeward- 
ful  results  are  purchasable. 

Queen  Anne  had  IS  or  19  children,  none  of  whom  were  living  at 
her  death.  Most  of  them  died  in  infancy,  and  only  one — the  Duke  of 
Gloucester — reached  the  age  of  11  years.  In  those  days,  they  "did  not 
expect  to  raise  them  all.''  While  conditions  have  greatly  improved,  infant 
mortality  almost  everywhere  is  still  excessive.  The  best  figures  are  from 
New  Zealand.  Our  own  figures  are  meager  and  imperfect.  Comparisons 
may  be  misleading  unless  we  are  assured  of  the  accuracy  of  birth  and 
death  returns  and  other  factors. 

Infant  mortality  means  deaths  under  one  year  of  age.  The  infant 
mortality  rate  is  the  ratio  of  deaths  under  one  year  to  births  during  the 
same  period;  the  births  being  the  easiest  method  of  determining  the 
number  in  this  age  group.  There  are  a  number  of  inaccuracies  in  infant 
mortality  rates,  which  are  mostly  too  high,  because  of  incomplete  birth 
registration,  Avhile  that  of  deaths  is  usually  fairly  reliable  (page  1275). 

Stillbirths  are  not  included  in  infant  mortality.  Registrars,  however, 
require  all  premature  and  all  stillbirths  to  be  recorded  by  a  birth  and  a 
death  certificate.  For  the  purposes  of  vital  statistics,  abortion  includes 
fetuses  up  to  four  months  of  pregnancy;  miscarriage,  between  four  and 
six  months;  premature  births,  from  six  months  (the  age  of  viability),  to 
fetal  maturity.  If  the  child  breathes  at  all,  it  must  not  be  recorded  as 
a  stillbirth. 

Infant  mortality  is  greater  in  cities  than  in  the  country,  not  because 
of  the  better  environment  of  country  life  and  air,  but  because  most  of 
the  important  conditions  which  cause  high  infant  mortality  are  con- 
centrated in  cities.     Infant  mortality  rates  are  not  determined  by  the 


478         PUBLIC  HEALTH  MEASURES  AND  METHODS 

size  of  the  city  or  the  density  of  population,  but  by  the  hygiene,  sanita- 
tion and  character  of  the  population;  thus,  we  have  the  following  in- 
fantile death  rate  from  the  United  States  Census  of  1900 : 

New  York  State   159.8 

New  York  City   189.4 

Nashua,  N.  H 261.0 

Lowell,  Mass 275.5 

Fall  River,  Mass 304.7 

Mobile,  Ala 344.5 

Savannah,  Ga 387.5 

Charleston,   S.   C 419.5 

Nashua,  Lowell  and  Fall  River  are  typical  factory  towns,  but  not 
large  ones.  A  similar  very  high  infantile  death  rate  is  seen  in  factory 
towns  in  England  and  elsewhere.  This  is  due  largely  to  the  gainful  em- 
ployment of  m^others  in  factories,  and  hence  bottle-feeding  and  neglect 
of  the  babies.  During  the  siege  of  Paris  in  1871,  while  the  general 
mortality  doubled,  the  infant  mortality  fell  40  per  cent.;  opportunities 
for  outside  work  were  shut  off  and  women  were  compelled  to  stay  home; 
so  nursed  their  babies.^ 

There  is  a  marked  contrast  between  the  death  rate  of  children  of 
the  poor  and  those  of  the  rich.  Infant  mortality  is  a  class  disease. 
In  this  case,  money  may  purchase  health  and  even  life  itself.  Thus, 
Clay  estimates  that  in  England  in  the  aristocratic  families  the  mortality 
of  the  first  year  is  10  per  cent.;  in  the  middle  class,  21  per  cent.;  in 
the  laboring  class,  32  per  cent.  Acute  gastro-intestinal  diseases  are 
chiefly  responsible  for  this.  Halle  states  that  of  170  infantile  deaths 
from  gastro-intestinal  diseases  investigated  in  Graz  in  1903  and  1904, 
there  were  161  among  the  poor,  9  among  the  well-to-do,  and  none  among 
the  rich.  Corresponding  figures  are  obtained  wherever  this  subject  is 
studied. 

A  high  infant  mortality  results  in  a  sacrifice  of  the  unfortunate  as 
well  as  the  unfit.  Newton  was  a  premature,  posthumous  baby,  saved 
only  by  careful  ministration.  Poverty  and  ignorance  are,  therefore, 
underlying  factors  of  great  importance  in  this  problem. 

The  mortality  is  especially  high  during  the  first  few  weeks  of  life. 
Ten  per  cent,  of  the  deaths  during  the  first  year  occur  on  the  first  day. 
Most  of  these  (about  70  per  cent.)  are  due  to  prematurity  and  injury 
at  birth.  From  25  to  40  per  cent,  of  the  total  deaths  during  the  first 
year  occur  during  the  first  month  of  life.  Some  of  these  (about  10 
per  cent.)  are  due  to  diarrheal  diseases,  but  most  of  them  are  due  to 
prematurity,  congenital  debility  and  malformation. 

'Brehmer:  Wochenschr.  f.  SauUngsfursorge,  1907,  209. 


INFANT  MOR-TALTTY  479 

Infant  mortal  it  v  const  itutt's  i'roni  20  to  ^5  per  cent,  of  all  deaths. 

The  Causes  of  Infant  Mortality. — The  death  returns  to  the  health 
officer  usually  cover  only  the  last  thing  which  happened  to  the  child. 
The  real  causes  which  are  hack  of  this  terminal  disease  do  not  appear 
on  the  records.  Diarrhea,  hronchitis,  and  pneumonia  are  often  end 
conditions  which  would  not  Iuinc  occurred  or  would  not  have  heen  fatal 
without  sonic. other  condition,  as  malnutrition,  neglect,  ignorance,  or 
marasmus,  which  existed  weeks  or  months  before  the  final  few  days  of 
acute  illness  which  closed  the  scene. 

The  underlying  factor  of  infant  mortality  is  infancy  itself — the  period 
in  which  the  flame  flickers  feeblest.  Most  infants  die  primarily  from 
accidental  and  therefore  preventable  causes — the  fundamental  causes  are 
the  results  of  poverty,  ignorance  and  neglect. 

The  chief  specific  causes  that  increase  infant  mortality  are  artificial 
feeding;  hot  weather;  dirty,  stale,  and  bacteria  laden  milk;  bad  feeding; 
illegitimacy;  lack  of  prenatal  care;  gainful  occupations  of  mothers; 
midwifery;  poor  housing;  lack  of  cleanliness;  alcoholism,  syphilis  and 
other  diseases;  imperfect  hygiene  and  sanitation.  The  causes,  then,  are 
multiple  and  exceedingly  complex,  and  include  social  and  economic 
factors. 

A  study  of  44,226  deaths  under  one  year  in  the  four  largest  American 
cities  gives  the  following  causes  of  infantile  deaths: 

Per  cent. 

Acute  gastro-intestinal  disease   28.01 

Prematurity,  congenital  debility  and  marasmus   25.5  l72% 

Acute  respiratory  diseases 18.5  I 

Acute  infectious  diseases 5.4 

Tuberculosis   (all  forms)    2,0 

Syphilis   1.2 

Malformations,  injuries  at  birth  and  other  conditions  of 

the  new-born 5.8 

Convulsions 3.4 

All  others 10.2 

From  the  above  analysis,  it  is  at  once  evident  that  72  per  cent,  of 
the  total  infant  mortality  is  made  up  of  the  first  three  causes. 

The  relative  importance  of  these  causes  varies  with  the  age  of  the 
infant;  thus,  nearly  70  per  cent,  of  deaths  occurring  on  the  first  day  of 
life  are  due  to  group  1  of  the  tabulation  on  the  next  page. 

Sepsis  in  the  new-born  formerly  carried  off  many  babies.  This  has 
been  largely  reduced  by  aseptic  methods  in  obstetrics.  The  toll  is  still 
large  where  these  principles  are  not  practiced.  See  Tetanus  Neona- 
torum, page  99. 

Vaccination  has  reduced  deaths  from  smallpox,  which  used  to  be 


480    PUBLIC  HEALTH  MEASURES  AND  METHODS 

a  children's  disease.    Improvement  in  the  control  of  other  communicable 
infections  has  also  helped  reduce  infant  mortality. 
Another  tabulation  of  causes  follows: 

Per  cent. 

1.  Prematurity,  congenital  defects,  debility  and  accidents 

at  birth 25 

2.  Diseases  of  nutrition 15^ 

3.  Acute  gastro-intestinal  diseases 25 

4.  Acute  respiratory  diseases   20 

5.  Acute  infectious  diseases 3 

6.  Tuberculosis    2 

7.  Syphilis  (direct  effects)    1 

8.  Unclassified    9 


40  I    85 


100 


Gastro-intestinal  Diseases.' — Gastro-intestinal  diseases  comprise  the 
largest  single  factor  almost  everywhere;  in  fact,  the  curve  of  diarrheal 
diseases  largely  controls  the  curve  of  infant  mortality.  These  dis- 
eases embrace  acute  gastritis,  gastro-enteritis,  diarrheas,  dysentery,  in- 
fectious diarrheas,  and  cholera  infantum — often  termed  summer  com- 
plaints. 

There  are  three  underlying  causes  of  gastro-intestinal  diseases  of  the 
first  year:  (1)  atmospheric  heat ;  (2)  methods  of  feeding;  (3)  infection; 
all  of  which  are  favored  by  city  residence. 

The  withering  effects  of  heat,  especially  when  combined  with  hu- 
midity, are  well  known.  Indoor  air  in  crowded  tenement  districts  may 
be  hot  and  humid,  while  the  temperature  and  humidity  at  the  observa- 
tion stations  of  the  weather  bureau  indicate  pleasant  weather. 

There  is  the  closest  possible  connection  between  the  frequency  and 
fatality  of  diarrheal  diseases  and  methods  of  feeding.  The  chances  are 
about  one  to  ten  against  the  bottle-fed  baby.  Eighty-five  per  cent, 
of  all  infant  deaths  are  bottle-fed  babies;  90  per  cent,  of  infant  deaths 
from  diarrheal  diseases  are  bottle-fed.  The  figures  are  sufficiently  im- 
pressive to  emphasize  the  importance  of  breast-feeding  in  prevention. 
This  one  measure  alone  would  reduce  infant  mortality  one-third. 

Hope,  of  Liverpool,  has  shown  that  in  1,000  breast-fed  infants  under 
three  months  there  were  only  20  deaths  from  diarrheal  diseases;  when 
in  1,000  bottle-fed  babies  under  three  months  there  were  300  deaths. 
Of  1,000  fatal  cases  of  diarrheal  diseases  investigated  by  the  Kew  York 
Health  Department  in  1908,  only  90  has  previously  been  entirely  breast- 
fed. Kewsholme  gives  almost  identical  figures  for  England ;  namely,  10 
per  cent,  of  deaths  in  breast-fed  infants,  and  90  per  cent,  in  bottle-fed 
infants. 


INFANT  MORTALITY  481 

It  is  not  artiiieial  feeding,  yer  se,  as  is  shown  by  the  relatively  fewer 
deaths  in  the  bottle-fed  babies  among  the  well-to-do.  Secondary  factors 
are  bad  milk,  unsuitable  foods,  improper  methods  of  feeding,  lack  of 
maternal  care,  bad  surroundings,  especially  heat,  humidity,  lack  of  clean- 
liness and  overcrowding,  which  favors  the  spread  of  infection;  in  short, 
imperfect  hygiene  and  sanitation. 

Breast-feeding  requires  but  little  experience  and  may  be  very  success- 
fully done  even  by  those  with  a  very  low  grade  of  intelligence  and  among 
the  poor;  but  artificial  feeding  is  not  successful,  unless  carried  on  with 
much  intelligence  and  experience  and  at  the  same  time  with  a  certain 
amount  of  money  to  secure  reliable  materials,  especially  pure  milk. 

The  method  of  feeding  is  especially  important  in  prematurity,  con- 
genital debility,  marasmus  and  inanition;  also  at  the  first  indications  of 
gastro-intestinal  disturbance  in  a  previously  healthy  child. 

Many  of  the  diarrheal  diseases  of  infants  are  true  bacillary  dysen- 
teries, or  infectious  diarrheas  of  specific  cause.  They  are  transmitted 
in  all  the  ways  that  typhoid  fever  and  dysentery  are  transmitted.  San- 
itary isolation,  the  boiling  of  diapers  and  aseptic  technic  of  food  and 
clothing  are  essential  to  protect  babies  against  these  preventable  infec- 
tions. 

Bronchitis  and  pneumonia  are  responsible  for  about  18  per  cent,  of 
the  total  infant  mortality.  Overcrowding  favors  the  spread  of  these  in- 
fections, and  common  colds,  influenza,  streptococcal  and  pneumococcal 
infections  are  ver}-  apt  to  cause  severe  bronchitis  or  bronchopneumonia 
in  infants.  These  conditions  are  often  terminal  and  not  at  all  the  true 
cause  of  the  baby's  death. 

AU  forms  of  tuberculosis  constitute  about  2  per  cent,  of  infantile 
deaths.  This  is  doubtless  an  under-estimate  because  of  the  difficulty  in 
recognizing  this  disease  in  infancy.  The  care  of  the  baby  is  often  left 
to  the  sick  father  or  mother  while  the  other  members  of  the  family  are 
at  their  work.  Tuberculosis  does  not  usually  manifest  itself  early,  but 
the  infec-tion  contracted  in  infancy  may  remain  latent  and  later  in  life 
break  out  into  the  clinical  disease.     See  page  175, 

Syphilis  accounts  for  about  1.2  per  cent,  of  infantile  deaths.  These 
figures  include  only  the  direct  effects  of  the  spirochete.  The  prevention 
consists  in  prompt  treatment  of  parents,  etc.     See  page  85. 

Acute  communicable  diseases  account  for  only  5.4  per  cent,  of  in- 
fantile deaths.  Whooping-cough  makes  up  about  half,  and  measles  and 
erysipelas  most  of  the  remainder,  for  the  other  diseases  are  relatively  in- 
frequent in  the  first  year. 

Premature  birth  or  feebleness  at  birth  too  great  to  support  an  inde- 
pendent existence  is  responsible  for  many  early  deaths.  Alcohol  and 
syphilis  are  prime  factors  favoring  these  conditions.  This  group  includes 
congenital  debility,  marasmus  and  inanition.     It  is  in  this  group  that 


482  PUBLIC  HEALTH  MEASUEES  AND  METHODS 

prenatal  care  and  proper  hospital  provision  for  premature  infants  is 
especially  helpful. 

Prenatal  care  and  especially  a  period  of  rest  and  good  food  before 
confinement  will  increase  the  weight,  vigor  and  maturity  of  the  baby. 

Prevention. — The  prevention  of  infant  mortality  consists  in  attack- 
ing the  problem  at  its  root,  in  concentrating  upon  the  preventable  causes, 
and  focusing  attention  upon  the  mother.  Attacking  the  problem  at  these 
points  will  give  rewardful  results.  The  preventable  causes  of  infant 
mortality  ^  may  be  grouped  as  follows : 

1.  Those  but  little  influenced  by  treatment: 

Malformations. 

Extreme  feebleness  or  prematurity  (before  the  seventh  month). 

Certain  accidents  during  birth. 

2.  Those  capable  of  considerable  reduction,  chiefly  through  proper 

hygiene,  sanitary  isolation  and  medical  treatment : 
Tuberculosis.     Syphilis. 
Acute  respiratory  diseases. 

Acute    contagious    diseases — Whooping-cough,    measles,    and 
diphtheria. 

3.  Those  capable  of  a  very  great  reduction  through  proper  feeding 

and  care: 

Acute  gastro-intestinal  diseases. 
Marasmus  and  inanition. 
Prematurity,  after  seventh  month. 

Poverty  and  ignorance  require  social  justice  and  education.  Other 
means  of  prevention  are :  prenatal  care,  hospitals  for  premature  infants, 
milk  depots,  educational  clinics,  public  health  nursing,  encouragement 
of  breast-feeding,  competent  and  compulsory  medical  supervision  of 
infancy,  clean  milk,  pasteurization,  escape  from  city  heat,  better  hous- 
ing, scattering  of  crowded  tenements,  cleanliness,  better  artificial  feeding 
when  necessar}^,  sanitary  isolation  from  dysentery  and  other  intestinal 
diseases,  also  from  influenza,  common  colds,  pneumonia  and  other  respi- 
ratory infections.  Milk  depots,  little  mothers'  leagues,  social  service 
workers,  public  health  nurses,  and  improvement  in  medical  and  obstetri- 
cal practice  are  part  of  the  program.  Foundlings  and  orphans  should 
be  raised  in  homes  rather  than  in  institutions. 

^Much  of  this  material  is  taken  from  the  excellent  articles  by  Dr.  L. 
Emmett  Holt  on  "Infant  Mortality  and  Its  Reduction,  Especially  in  New  York 
City,"  Journal  of  the  American  Medical  Association,  February  26,  1910;  and 
"Infant  Mortality  Ancient  and  Modern,"  Archives  of  Pediatrics,  XXX,  12,  De- 
cember, 1913.  Both  these  publications  contain  selective  bibliographies.  Consult 
also  the  publications  of  the  American  Association  for  the  Study  and  Prevention 
of  Infant  Mortality,  the  Archives  of  Pediatrics,  etc. 


NUISANCES  483 

PUBLIC  HEALTH  NURSING 

Public  health  nursinfj;-  is  one  of  the  most  important  links  in  the  chain 
of  efficient  public  health  administration.  The  duties  of  the  public  health 
nurse  are  vague  and  varied.  They  include  instruction  and  social  work 
as  well  as  nursing;  in  fact,  nursing  may  be  a  small  part  of  the  duties  of 
a  public  health  "nurse,"  and  the  term  is  therefore  misleading.  The 
office  of  the  public  health  nurse  is  part  of  an  organized  community  effort 
to  prevent  sickness,  maintain  efficiency^  prolong  life,  relieve  suffering  and 
promote  individual  and  public  health.  The  nursing  itself  must  be  pre- 
ventive as  well  as  curative  or  palliative. 

The  public  health  nursing  movement  is  recent  but  has  grown  steadily. 
The  first  district  nursing  association  was  established  in  Liverpool  in 
1859;  the  first  in  the  United  States  was  the  Instructive  District  Nurs- 
ing Association  in  Boston  in  1886.  The  movement  has  now  received 
recognition,  is  an  established  and  important  part  of  public  health  work, 
and  is  making  rapid  progress. 

Specialists  are  required  for  certain  problems,  such  as  the  venereal 
diseases,  tuberculosis,  infant  and  child  welfare,  school  nursing;  also 
mental  hygiene,  industrial  nursing,  medical  social  service,  and  dental 
hygiene.  Each  of  these  special  fields  requires  special  qualifications  which 
can  be  had  only  through  training  and  experience.  In  addition,  all  com- 
munities require  public  health  nurses  prepared  for  general  service.  A 
model  plan  of  organization  includes  both  the  general  nurse  and  special- 
ists. 

About  one  public  health  nurse  is  needed  for  each  3,000  population; 
in  addition  one  tuberculosis  nurse  for  each  20,000,  and  one  school  nurse 
for  each  1,500  children.  The  public  health  nurse  should  be  in  close 
touch  with  the  board  of  health  and  many  other  public  and  private 
agencies  in  the  community.    She  should  not  furnish  material  relief. 

REFERENCES 

Brainard,  Annie  M.  :   "Organization  of  Public  Health  Nursing."     Mac- 

millan  Co.,  1919. 
Gardner,  Mary  S.  :     "Public  Health  Nursing."    Macmillan  Co.,  1916. 
LaMotte,  Ellen:     "Tuberculosis  Nursing."     Macmillan  Co.,  1915. 
Nutting,  M.,  and  Dock,  L.  L.  :     "History  of  Nursing."     Macmillan  Co., 

1912. 
Struthers,  Lena:     "School  Nursing."    Macmillan  Co.,  1917- 
Wright,  Florence  S.  :     "Handbook  on  School  Nursing."     MacmiUan  Co., 

1919. 

NUISANCES 

A  nuisance  may  be  defined  as  "the  use  of  one's  property  in  such  a 
way  as  to  injure  the  rights  of  others,  and  to  inflict  damages."    Popularly 


484         PUBLIC  HEALTH  MEASUEES  AND  METHODS 

a  nuisance  is  an  annoyance.  Statutory  definitions  are  usually  more 
explicit  and  include  nuisances  not  directly  related  to  public  health.  A 
comprehensive  statutory  definition  is :  "Whatever  is  dangerous  to  human 
life,  and  whatever  renders  soil,  air,  water,  or  food  impure  or  unwhole- 
some, are  declared  to  be  nuisances,  and  every  person,  either  owner,  agent, 
or  occupant,  having  aided  in  creating  or  contributing  to  the  same,  or  who 
may  suffer  to  continue  or  retain  any  of  them  shall  be  deemed  guilty  of  a 
misdemeanor."  ^° 

The  following  are  considered  nuisances  in  different  states  and  cities : 
Filth,  such  as  garbage,  ashes,  and  slops,  either  on  private  property  or  on 
public  highways;  cesspools,  privy  vaults,  sink  drains,  dumps,  and  dirty 
yards;  low,  wet,  and  soggy  lands;  defective  plumbing  and  draining; 
faulty  cellars;  overcrowding  of  tenements  and  lodging  houses,  or  dwell- 
ings unfit  for  habitation;  excavations;  weeds;  flowers  with  offensive 
odors;  foul  closets  on  railroad  coaches;  dirty  street  cars;  use  pf  salt  on 
streets  in  snowy  weather;  disturbing  noises;  spitting  in  public  places; 
keeping  of  horses  and  cattle  in  city  limits;  manure;  hogs;  hog-pens, 
stables  and  barns ;  fowls ;  dead  animals ;  filthy  shores ;  stagnant  water  and 
marshes;  offensive  businesses  and  trades;  places  where  liquor  is  sold 
illegally;  and  offenses  against  decency.  While  some  of  these  conditions 
may  favor  the  spread  of  the  communicable  diseases,  yet  most  nuisances 
are  not  serious  health  problems. 

The  phrase  "source  of  filth  or  cause  of  sickness"  used  in  the  statutes 
of  no  less  than  fourteen  states,  is  copied  verbatim  from  a  law  enacted  in 
Massachusetts  in  1797.  At  that  time  miasmatic  vapors  and  the  inhala- 
tions from  decomposing  organic  matter  were  believed  to  be  the  principal 
causes  of  the  contagious  diseases.  The  Supreme  Court  of  Massachu- 
setts, however,  has  ruled  that  "in  order  to  amount  to  a  nuisance  it  is  not 
necessary  that  the  corruption  of  the  atmosphere  should  be  such  as  to  be 
dangerous  to  health ;  it  is  sufficient  that  the  effluvia  are  offensive  to  the 
senses  and  render  habitations  uncomfortable." 

By  far  the  greatest  number  of  all  the  complaints  reaching  the 
health  authorities  deal  with  real  or  supposed  nuisances.  There  seems  to 
be  a  widespread  belief  that  the  chief  function  of  the  health  officer  is  the 
abatement  of  nuisances.  Formerly  the  health  officer  was  a  general 
scavenger  and  his  main  duties  consisted  in  looking  after  nuisances. 
Nuisances  often  clog  the  health  office  and  crowd  out  more  important 
sanitary  and  hygienic  matters.  In  most  complaints  the  question  at  issue 
is  whether  the  nuisance  exists  or  not — a  question  of  fact  which  could 
be  decided  just  as  well  by  the  police  courts  as  by  a  board  of  health  or 
health  officer.  However,  the  abatement  of  nuisances  is  usually  assigned 
to  the  health  authorities  by  statutory  enactment. 

In  a  few  cities,  especially  those  with  liberal  charters,  the  ordinances 

"Utah,  Chapter  45  of  1889,  Sec.  1. 


FACE  MASKS  485 

covering  nuisances  are  so  definite  and  explicit  that  an  inspector  may 
determine  a  nuisance  and  issue  an  order  for  its  abatement.  In  cases 
where  condemnation  of  property  of  considerable  value  is  involved,  such 
for  example  as  when  an  oU'ensive  trade  is  alleged  to  be  a  nuisance,  it  is 
usually  necessary  to  prove  the  case  in  court  before  the  nuisance  can  be 
abated.  In  court,  substantial  injury  must  be  shown  and  the  health  officer 
should  bo  sure  lie  has  tlic  facts  as  to  the  nuisance  before  he  appears  in 
court.  He  will  be  required  by  the  court  to  establish  the  source,  fre- 
quency, and  nature  of  tlio  odors,  or  whatever  is  alleged  to  be  the  nuisance. 
It  is  exceedingly  difficult  to  establish  the  fact  that  many  nuisances  are 
dangerous  to  the  health  of  the  community  and  the  cause  of  sickness. 

In  general  two  methods  are  followed  for  the  control  of  nuisances: 
(1)  prevention;  (2)  abatement.  The  first  is  the  wisest  and  aims  to 
regulate  and  control  the  different  conditions  likely  to  cause  a  nuisance  or 
even  to  prohibit  them.  The  second  merely  provides  legal  steps  for 
their  abatement.  There  are  at  least  four  ways  in  law  of  dealing  with 
nuisances:  (1)  By  criminal  action;  (2)  by  injunction;  (3)  by  damages 
(private  suit) ;  (4)  by  abatement  under  statutory  powers. 


FACE  MASKS 

Face  masks  have  a  certain  degree  of  usefulness  in  limiting  the  spread 
of  infections  transmitted  by  the  secretions  from  the  mouth  and  nose. 
They  act  mechanically  to  check  the  diffusion  of  infectious  secretions  by 
the  patient,  or  they  may  be  used  by  well  persons  (recipients)  as  a  bar- 
rier against  such  infections.  They  are  especially  indicated  in  serious  dis- 
eases such  as  pneumonic  plague,  diphtheria,  scarlet  fever,  pneumonia 
and  other  malignant  infections  transmitted  by  droplets. 

Face  masks  have  long  been  in  successful  use  by  surgeons  to  guard 
against  droplet  infection  of  wounds.  They  are  also  useful  to  physicians 
in  throat  examination,  and  to  protect  nurses,  orderlies  and  others  about 
patients.  The  mask  may  be  worn  either  by  the  patient,  the  recipient,  or 
both. 

During  the  influenza  epidemic  of  1918  face  masks  came  into  vogue 
as  a  public  health  measure  to  check  the  spread  of  this  disease.  The 
"wearing  of  masks  was  made  compulsory  in  San  Francisco  and  other 
California  cities.  This  measure,  however,  had  no  noticeable  influence 
upon  the  course  of  the  epidemic.  Theoretically  this  measure  seems 
sound,  but  in  practice  it  is  disappointing,  for  there  are  many  loopholes. 
Droplet  infection  is  only  one  of  the  ways  by  which  these  diseases  are 
spread ;  in  fact,  droplet  infection  probably  accounts  for  only  a  small 
percentage  of  cases — other  modes,  such  as  hand  to  mouth  infection, 
various  forms  of  contact,   spoons,   cups  and   table  ware,   etc.,   explain 


486    PUBLIC  HEALTH  MEASUEES  AND  METHODS 

the  transfer  in  most  cases.  The  gauze  mask,  furthermore,  has  many  im- 
perfections of  construction  and  technic  of  wearing. 

For  complete  protection  the  eyes  of  the  recipient  must  also  be 
guarded.  Microorganisms  landing  upon  the  conjunctiva  may  find  their 
way  to  the  nose  in  5  minutes  and  to  the  throat  within  15  minutes. 
Weaver  ^^  insists  that  the  mask  must  be  properly  constructed  with  3  or  4 
layers  of  butter  cloth  (not  gauze  or  cheese  cloth)  and  held  by  a  wire 
frame  so  as  not  to  touch  the  lips  and  nose.  Kelloy  and  MacMillan  ^^  state 
that  when  the  mask  has  a  sufficient  degree  of  density  to  be  a  useful  filter, 
breathing  is  difficult  and  leakage  takes  place  around  the  edge  of  the 
mask.  Doust  and  Lyons  ^^  used  B.  prodigiosus  to  determine  the  danger 
zones  and  permeability  of  various  masks,  and  found  masks  of  medium 
gauze,  2  to  10  layers,  worthless;  but  masks  of  3  layers  of  butter  cloth 
effective. 

The  face  mask  has  a  limited  usefulness.  It  has  not  been  demon- 
strated to  have  that  degree  of  efficiency  to  warrant  compulsory  applica- 
tion for  the  checking  of  an  epidemic.  Even  when  masks  are  used  by 
doctors  and  nurses  at  the  bedside,  this  should  not  lead  to  the  neglect 
of  measures  necessary  to  prevent  the  spread  of  infections  by  hand  to 
mouth  and  other  means, 

DRUG  ADDICTION 

The  chief  habit  forming  drugs  are  alcohol;  opium  and  its  alkaloids, 
especially  morphin,  codein,  and  heroin ;  and  cocain.  It  has  only  recently 
been  realized  that  drug  addiction  is  an  important  public  health  problem, 
in  addition  to  its  sociologic  and  economic  aspects. 

It  is  conservatively  estimated  that  1  per  cent,  of  the  population  of  the 
United  States,  or  at  least  one  million  persons  are  drug  addicts  (exclud- 
ing alcohol) .  The  slums  and  the  vice  districts  of  cities  give  the  largest 
pro-rata  indulgence  in  drugs.  Blair  reports  that  in  Pennsylvania  there 
is  more  free  and  unrestricted  addiction  in  small  places  than  in  large 
cities.  The  age  of  addicts  ranges  from  12  to  75  years.  Many  heroin  ^* 
addicts  are  boys  and  girls  under  20  years  of  age.  Anyone  repeatedly  tak- 
ing a  narcotic  drug  for  thirty  days  is  in  grave  danger  of  becoming  a  slave 
to  the  drug.  The  reasons  for  beginning  the  vicious  practice  are  innumer- 
able. In  most  cases,  however,  once  learned,  there  is  an  underlying 
defect  or  weakness,  either  acquired  or  inherited,  that  chains  the  victim  to 
the  vice.     The  Harrison  law  meets  the  situation  only  in  small  part. 

^^Jour.  Am.  Med.  Assoc,  Oct.  12,  1918,  and  J.  Infec.  Dis.,  XXIV,  3,  March, 
1919,  p.  218.  . 

"Am.  J.  P.  H.,  Jan.,  1920,  X,  1,  p.  34. 

"J.  A.  M.  A.,  Oct.  12,  1918. 

"  Heroin  should  be  eliminated  from  all  medicinal  preparations  and  should 
not  be  administered,  prescribed  or  dispensed.  The  importation,  manufacture  and 
sale  of  heroin  should  be  prohibited. 


DRUG  ADDICTION  487 

More  aggressive  and  absolute  measures  are  necessary  to  combat  this 
growing  and  serious  habit,  which  undermines  health  and  interferes  with 
efificiency  and  character  of  a  very  large  number  of  persons.  See  also  page 
433, 

ALCOHOL 

Alcohol. — Ethyl  alcohol  (CoHr.OH)  has  been  used  since  the  dawn  of 
history.  lentil  recently,  we  had  little  precise  knowledge  concerning  the 
effects  of  alcohol.  .No  one  doubts  that  alcohol  is  harmful  when  used 
in  amounts  sufficient  to  produce  its  full  physiological  effects.  In  suf- 
ficient concentration,  it  is  a  poison  to  all  living  matter,  both  animal  and 
vegetable.  The  question  in  dispute  is  upon  the  effects  of  "small" 
amounts.  Alcohol  is  a  solvent  for  many  substances,  is  locally  irritating, 
is  quite  volatile,  and  has  other  well  defined  physical  and  chemical 
properties,  but  perhaps  the  most  striking  characteristic  is  that  "it  is 
equally  inflammable  whether  one  touches  a  match  to  it  or  writes 
about  it."' 

Local  Irritating  Action.. — Applied  to  the  skin  in  sufficient  concen- 
tration (60  to  90  per  cent.),  alcohol  produces  redness,  itching,  and  a 
feeling  of  heat  like  other  volatile  and  irritant  substances.  Upon  wounds 
a  concentrated  solution  causes  a  precipitation  of  the  proteins  and  acts 
first  as  an  astringent  and  then  as  a  corrosive.  The  effects  of  alcohol  on 
mucous  membranes  are  similar  to  those  on  wounds. 

Alcohol  as  a  Food. — Whether  alcohol  can  be  regarded  as  a  food  or 
not,  depends  upon  the  definition  of  a  food.  Alcohol  is  not  a  tissue 
builder,  but  within  limits  it  is  burnt  in  the  body  and  thus  furnishes 
heat  and  energ}\  In  this  sense,  then,  alcohol  is  a  food.  Thus,  one  gram 
of  alcohol  furnishes  seven  calories  of  heat  when  burned.  The  human 
body  is  not  able  to  burn  more  than  about  two  ounces  of  alcohol  a  day. 
If  more  than  this  amount  is  taken,  it  promotes  the  storage  of  fat.  The 
excess  alcohol  is  eliminated  unchanged  in  the  urine  and  by  the  skin 
and  lungs. 

Alcohol  may  be  compared  with  sugar  and  starches  as  a  food — both  are 
oxidized  in  the  body  and  furnish  heat  and  energy,  but  there  is  this 
difference :  sugar  and  starch  help  to  repair  waste,  which  alcohol  can- 
not do. 

Effect  upon  Digestion. — Alcohol  in  the  mouth  causes  a  very  appre- 
ciable secretion  of  saliva,  presumably  by  reflex  action.  It  is  not  unlikely 
that  the  taste  has  some  influence  on  this  result :  in  those  who  enjoy  the 
taste  of  alcohol,  it  induces  a  more  rapid  secretion  and  an  immediate 
digestion;  while  in  those  to  whom  it  is  disagreeable,  the  effect  is  less 
marked. 

Small  amounts  of  wines  and  liquors  used  as  a  condiment  to  flavor 
sauces  and  desserts  are  pleasing  to  the  taste  of  many  persons,  and  thus 


488  PUBLIC  HEALTH  MEASURES  AND  METHODS 

used  probably  stimulate  the  appetite,  and  through  the   psychic  effect 
of  savory  morsels  promote  the  secretion  of  digestion  juices. 

The  augmentation  of  the  activity  of  the  digestive  ferments  caused 
by  alcohol  is  so  slight  in  any  case  that  it  does  not  seem  likely  that  it 
plays  any  important  role  in  digestion- 
All  are  agreed  as  to  the  deleterious  action  of  any  but  moderate  doses 
of  alcohol  on  digestion.  Large  quantities  irritate  the  stomach  and  may 
lead  to  profuse  secretion  of  mucus,  nausea,  and  vomiting — irritative 
gastritis. 

Action  on  the  Nervous  System. — The  action  of  alcohol  on  the  nerve 
centers  seems  to  differ  in  individuals,  but  this  is  solely  a  difference  of 
manifestation,  for  the  physiological  action  is  essentially  the  same  in  all 
persons.  In  small  quantities,  it  produces  a  feeling  of  well  being  and 
goodfellowship,  along  with  increased  confidence  in  physical  power  and 
mental  ability.  This  confidence,  however,  is  due  to  removal  of  repres- 
sion and  inhibition.  Larger  quantities  are  followed  by  laughter,  loqua- 
city, gesticulation,  and  other  indications  of  animal  excitement.  The 
face  becomes  flushed  and  heated,  the  eyes  brighter  and  livelier,  and  the 
pulse  quickens.  Even  at  this  stage,  self  control  is  partially  lost,  and  the 
will  power  is  weakened.  The  speech  may  be  brilliant,  but  often  betrays 
the  speaker.  The  movements  are  more  lively,  but  they  are  often  undigni- 
fied. The  loss  of  self  control  is  often  indicated  further  by  furious  out- 
bursts of  anger  or  unreasonableness,  or  by  the  indulgence  in  maudlin 
sentimentality  and  sensual  fancies.  The  sense  of  responsibility  and  the 
power  of  discrimination  between  the  trivial  and  the  important  are  lost, 
and  the  individual  has  no  regard  for  the  feelings  of  others  or  the  ordi- 
nary conventions  of  life.  If  more  alcohol  is  imbibed,  the  movements 
become  uncertain,  the  speech  becomes  difficult  and  stammering,  the 
walk  becomes  a  stagger,  and  a  torpid  slumber  follows.  Often  nausea  and 
vomiting  set  in,  doubtless  due  to  the  direct  irritating  action  on  the 
gastric  mucosa.  On  recovery  from  slumber,  a  very  great  depression  is 
generally  suffered,  together  with  nausea  and  vomiting  and  want  of  appe- 
tite, which  may  last  several  days,  and  is  associated  with  all  the  symptoms 
of  acute  gastric  catarrh.  Very  large  quantities  of  alcohol  produce  total 
unconsciousness,  resembling  chloroform  anesthesia.  If  unconsciousness 
lasts  longer  than  ten  to  twelve  hours,  recovery  seldom  takes  place. 

On  the  lower  part  of  the  central  nervous  system,  alcohol  acts  as  a 
distinct  depressant,  for  the  coordination  of  movements  suffers  at  an 
early  stage.  In  the  spinal  cord,  there  is  a  depression  of  the  reflex,  which 
passes  into  complete  paralysis.  The  medulla  oblongata  is  the  last  part 
of  the  central  nervous  system  to  be  acted  on  by  alcohol.  Dodge  and 
Benedict  find  that  alcohol  depresses  the  lower  centers  most  and  the 
highest  centers  least.  It  retards  the  reaction  time.  In  one  sense,  alco- 
holic depression  may  be  regarded  as  a  conservation  process. 


DRUG  ADDICTION  489 

Alcohol  is  a  nerve  poison;  hence,  alcoholic  neuritis  is  well  known  to 
the  clinician.  The  repeated  use  of  excessive  amounts  of  alcohol  causes 
brain  injury,  as  Korsakoff's  disease,  alcoholic  hallucinosis,  delirium  tre- 
mens, and  other  forms  of  alcoholic  insanity. 

Alcohol  psychoses  account  for  about  12  per  cent,  of  all  first  admis- 
sions to  hospitals  for  the  insane.  They  occur  about  three  times  as 
frequently  in  men  as  in  women,  and  in  general  the  subjects  come  more 
frequently  from  the  cities  than  from  rural  districts. 

Alcohol  as  a  Stimulant. — Alcohol  acts  like  ether  and  chloroform 
and  other  narcotic  drugs.  There  is  a  preliminary  stage  of  excitement, 
mental  confusion,  and  often  excessive  and  incoordinate  activity. 

Binz  and  his  pupils  claim  that  alcohol  first  stimulates  and  then  de- 
presses the  nervous  cells,  but  the  preponderance  of  evidence  is  clearly 
in  favor  of  the  views  of  Schmiedeberg,  Bunge  and  their  followers,  that 
it  depresses  the  central  nervous  system  from  the  beginning.  The  ap- 
parent excitement  is  not  due  to  true  stimulation  of  the  motor  areas,  but 
is  the  result  of  these  areas  being  freed  from  control  by  the  weakening 
of  the  highest  powers  of  the  brain — the  will  and  self  restraint.  Even  the 
smallest  quantities  of  alcohol  tend  to  lessen  important  activities  of  the 
brain,  for  the  drug  acts  first  upon  those  qualities  which  have  been  built 
up  through  education  and  experience. 

One  of  the  most  deceptive  of  experiences  is  the  false  sense  of  stimula- 
tion which  alcohol  gives.  By  depressing  the  higher  cerebral  centers,  it 
releases  the  lower  mental  processes.  Hence,  its  first  effect  is  to  cloud 
the  judgment  and  dull  the  finer  feelings.  It  takes  off  the  brake  of 
restraint,  loosens  the  tongue,  and  sets  free  the  lower  animal  passions. 
It  is  this  blunting  of  the  higher  and  finer  mental  powers  which  causes 
people  to  say  things  and  do  deeds  under  the  influence  of  alcohol  that 
would  shock  their  sensibilities  otherwise. 

It  is  difficult  to  measure  the  harm  done  by  this  effect  of  inhibiting 
the  nobler  mental  functions,  but  it  must  be  great.  Alcohol  does  not 
relieve  fatigue,  but  makes  one  unconscious  of  fatigue. 

Effect  on  Efloiciency. — A  large  number  of  tests  have  demonstrated 
that  the  apparent  quickening  of  the  mind  and  body  under  alcohol  are 
false  sensations.  The  performance  of  difficult  operations  involving 
muscular  coordination  and  judgment  are  slower  and  less  accurate  under 
alcohol  than  normally.  It  is  difficult,  on  account  of  the  feeling  of  con- 
fidence that  comes  from  alcohol,  to  convince  a  typist,  a  sharp  shooter, 
or  type  setter  of  this  fact  until  shown  the  records.  Even  amounts  of 
alcohol  so  small  that  the  subject  and  observer  are  not  aware  of  any 
abnormality  of  appearance  or  behavior,  interfere  with  efficiency. 

It  has  been  found  that  regiments  not  supplied  with  alcohol  march 
farther  and  are  in  better  condition  at  the  end  of  the  day  than  others  to 
which  it  Las  been  given.     The  experiments  of  Durig  lead  to  the  same 


490         PUBLIC  HEALTH  MEASUEES  AND  METHODS 

results,  the  total  amount  of  work  being  smaller  under  alcohol,  and  the 
expenditure  of  energy  greater.  Forms  of  work  requiring  intelligence 
are  performed  less  correctly  with  alcohol  than  without  it;  thus,  type 
setters  can  do  more  work  and  make  fewer  mistakes  when  they  abstain 
from  its  use.  Even  Binz,  who  claims  that  alcohol  is  a  primary  stimu- 
lant, admits  that  this  action  is  transient^  and  is  followed  by  depression, 
so  that  the  total  amount  of  work  may  thus  be  reduced.  Kraepelin  found 
in  a  series  of  careful  measurements  of  the  simpler  processes,  that  the 
responsive  powers  were  weakened  by  very  small  quantities  of  alcohol, 
while  the  motor  functions  seemed  to  be  facilitated  by  small,  and  retarded 
by  large  quantities.  For  example,  a  person  under  even  a  small  dose  of 
alcohol  makes  more  errors  than  usual  in  adding  a  row  of  figures,  or  in 
reading  a  series  of  unconnected  syllables.  Of  special  importance  is 
the  fact  that  the  subject  of  the  experiment  is  quite  unaware  of  the 
inferiority  of  his  work,  and  believes  it  to  be  unusually  good.  Kraepelin 
has  shown  that  even  about  a  pint  of  beer  will  lower  intellectual  power, 
impair  memory,  and  retard  the  simpler  mental  processes.  Kraepelin's 
latest  investigations  tend  to  show  that  this  effect  of  alcohol  lasts  much 
longer  than  is  generally  recognized,  the  mental  equilibrium  being  rein- 
stated only  after  12  to  24  hours  after  even  moderate  indulgence.  In 
fact,  alcohol  may  be  found  in  the  blood  24  hours  after  its  ingestion. 

We  have  the  authority  of  Connie  Mack  that  alcohol  spoils  a  good 
baseball  player.  He  said  in  1910,  a  year  that  the  Philadelphia  Athletics 
won  the  world's  championship,  that  fifteen  of  his  twenty-five  players  did 
not  even  know  the  taste  of  alcohol. 

Pulse,  Reflex,  and  Temperature. — The  pulse  is  accelerated  during 
the  stage  of  excitement,  but  this  is  due  to  increased  muscular  effort, 
and  not  to  any  direct  stimulating  action  on  the  heart.  There  is  at 
first  a  slight  rise  in  blood  pressure  in  some  cases,  but  large  quantities 
affect  the  heart  in  the  same  way  as  ether  and  chloroform,  weakening 
the  auricular  and  ventricular  beat,  and  inducing  dilatation  and  slowing 
of  both  chambers. 

The  flushed,  perspiring  face  of  the  alcoholic  is  familiar.  This  indi- 
cates dilatation  of  the  skin  vessels,  which  is  sometimes  accompanied  by. a 
slight  contraction  of  the  internal  organs.  This  effect  of  alcohol  causes  a 
sense  of  warmth  and  comfort,  which  underlies  the  popular  belief  that 
it  is  helpful  to  take  alcohol  when  braving  exposure  to  cold  and  damp, 
during  a  chill,  etc.  Here  again  our  sensations  are  misleading  guides, 
for  the  temperature  of  the  body  may  fall  one  degree  C.  while  the  skin 
is  flushed  with  a  sense  of  warmth.  This  is  due  to  excessive  -heat  loss 
through  conduction  and  radiation,  and  also  to  the  fact  that  the  heat 
regulating  mechanism  is  rendered  less  sensitive  by  alcohol.  Hence, 
alcoholics  (when  inactive)  may  freeze  to  death  when  the  temperature 
is  scarcely  at  the  freezing  point. 


DRUG  ADDICTION  491 

The  changes  in  the  respiration  induced  by  alcohol  are  too  small  and 
too  inconsistent  to  be  of  any  special  importance. 

Alcohol  and  Venereal  Disease. — Alcohol  is  the  bedfellow  of  syphilis 
and  goiiorrliea.  It  is  intricatt'ly  interwoven  into  the  warp  and  woof  of 
sex  hygiene.  The  story  of  many  cases  of  sexual  immorality  begins  with 
the  influence  of  drink.  Alcohol  is  generally  accredited  with  increasing 
sexual  desire,  althougli  we  have  the  authority  of  Shakespeare  that  it 
interferes  with  the  consummation  of  sexual  intercourse.  The  unques- 
tioned sexual  excitement  is  not  due  to  stimulation  of  the  generative 
organs,  but  to  the  loss  of  self  control  and  the  anesthetic  action  of  alcohol 
upon  the  higher  centers  of  the  brain. 

Resistance. — It  has  long  been  known  clinically  that  persons  addicted 
to  the  use  of  alcohol  show  less  resistance  to  certain  diseases  and  to  opera- 
tions accompanied  by  shock,  than  more  temperate  individuals.  In  very 
intemperate  persons,  the  prognosis  must  be  guarded  in  an  attack  which 
would  ordinarily  be  accompanied  with  little  danger.  "Drunkards  have 
a  very  slim  chance  of  recovery  when  attacked  by  pneumonia"  (Osier). 

When  animals  are  subjected  to  treatment  with  alcohol,  and  then 
inoculated  with  pathogenic  microorganisms,  the  results  invariably  show 
a  greater  susceptibility  to  infection  and  a  greater  mortality  than  in 
control  animals.  A  similar  effect  is  produced  when  toxins  are  injected 
instead  of  bacteria.  The  reason  for  this  reduced  resistance  is  not  clear. 
It  may  result  from  inactivity  of  the  leukocytes  (Eubin),  or  a  reduction 
in  the  hemolytic  complement   (Abbott  and  Bergey). 

The  tolerance  to  alcohol  is  not  so  great  as  that  acquired  for  morphin 
and  nicotin. 

Life  insurance  figures  plainly  show  that  even  the  moderate  use  of 
alcohol  tends  to  shorten  life. 

Accidents. — Accidents  often  happen  under  the  influence  of  alcohol. 
Many  automobile  wrecks  and  railroad  collisions  can  be  traced  to  the 
recklessness  of  the  drinker.  Figures  show  that  industrial  accidents  are 
more  frequent  in  those  who  drink  than  in  abstainers.  It  is  regarded  as 
signiflcant  that  three  such  accidents  occur  on  Monday  to  two  on  other 
days. 

According  to  three  insurance  companies,  the  following  percentages 
of  accidents  are  attributed  directly  or  indirectly  to  alcohol : 

Railroad  accidents   »    7  per  cent. 

Streetcars   8  "  " 

Automobiles    10  "  " 

Vehicles  and  horses 8  "  " 

Heat  and  sunstroke 43  "  " 

Machinery   7  "  " 

Mines  and  quarries  8  "  " 

Drowning    ; ; . . .  13  "  " 

Gunshot    10  "  " 


492         PUBLIC  HEALTH  MEASURES  AND  METHODS 

Poverty. — There  would  be  much  less  poverty,  crime,  misery,  and 
distress  in  the  world  without  alcohol.  It  is  not  the  sole  cause  of  these 
ills,  but  a  potent  factor.  The  social  and  economic  aspects  of  the  alcohol 
question  are  plain  to  every  social  service  worker.  Of  352  able-bodied 
men  who  failed  to  support  their  families  in  Boston,  65  per  cent,  (243) 
were  drunkards. ^*^  About  25  per  cent,  of  cases  that  come  to  charitable 
organizations,  and  about  37  per  cent,  of  poverty  found  in  almshouses 
give  an  alcoholic  history. 

Three  fourths  of  the  cases  of  children  cared  for  by  the  Chicago 
Juvenile  Protection  Association  in  1911  grew  out  of  alcoholism  in  the 
parent  or  guardian. 

Crime. — Crime  is  often  committed  while  under  the  influence  of 
alcohol.  A  large  percentage  of  criminals  have  an  alcoholic  history.  The 
relation  between  alcohol  and  crime  is  not  disputed,  but  it  is  difficult  to 
express  its  influence  in  precise  percentages.  Drink  was  said  .to  be  the 
sole  cause  of  crime  in  16.8  per  cent,  of  13,402  convicts  in  12  states  of 
the  United  States  studied  by  the  Committee  of  Fifty.  Further, 
drink  contributed  to  49  per  cent,  of  the  crimes  against  property;  51 
per  cent,  of  the  crimes  against  person;  and  47  per  cent,  of  all  other 
crimes. 

The  first  action  of  the  police  in  a  local  uprising  is  to  close  the 
bars,  and  a  noteworthy  act  of  much  good  in  the  stress  of  the  World  War 
was  to  check  the  use  of  alcohol.  Alcohol  is  a  handicap  for  a  nation  in 
peace  or  war;  it  is  also  a  handicap  for  an  individual  in  the  struggle  for 
existence. 

Heredity. — The  relation  of  alcohol  to  heredity  is  difficult  to  appraise. 
Experiments  upon  lower  animals  give  various  results,  but  indicate  low- 
ered vitality  in  the  offspring.  The  craving  for  drink  is  not  transmitted, 
but  mental  deficiency  with  weakened  will  power  that  may  express  itself 
in  intemperance  is  inherited.  Many  alcoholics  are  also  defectives  and 
transmit  the  mental  defect.     This  subject  is  fully  discussed  on  page  430. 

Alcohol  in  Medicine. — Occasionally  alcohol  is  useful  in  the  treat- 
ment of  diabetes,  where  it  may  partly  replace  fats  and  carbohydrates 
when  these  are  harmful.  It  is  no  longer  considered  good  practice  to 
use  it  as  a  stimulant  in  fevers,  septic,  and  debilitated  states.  At  the 
Massachusetts  General  Hospital,  the  amount  of  alcohol  used  for  the 
patients  fell  70  per  cent,  from  1897  to  1906. 

It  may  be  a  serious  mistake  in  first  aid  to  induce  persons  who  have 
fainted,  or  who  have  been  injured,  or  who  have  lost  consciousness,  to 
drink  brandy  or  whiskey. 

Uses  of  Alcohol. — Because  alcohol  produces  a  fictitious  sense  of  well- 
being,  disguises  fatigue,  and  smothers  worry,  it  has  been  widely  used 
by  elderly  persons  and  certain  individuals,  particularly  convalescents  and 

"*  Report  of  the  Boston  Associated  Charities,  1910. 


SANITARY  SURVEYS  493 

those  upon  whom  life  hears  heavily.  AKoliol  is  used  in  such  cases  for 
its  physiological  effect  of  i)artially  heiiunihing  tlic  sensihilities  and  cre- 
ating an  artificial  sense  of  wcll-hoing.  In  such  situations,  the  use  of 
alcohol  often  seems  desirahle,  although  not  entirely  devoid  of  danger, 
especially  of  starting  the  habit  in  the  young. 

In  some  cases  the  depressing  action  of  alcohol  may  he  a  conservative 
process,  although  the  magnitude  of  the  harm  from  its  widespread  abuse 
outweighs  this  theoretical  advantage. 

Summary. — The  student  of  Preventive  Medicine  regards  the  alcohol 
question  as  a  major  public  health  problem.  Alcohol  is  a  habit-forming 
drug;  it  lowers  resistance  and  shortens  life,  impairs  efficiency,  promotes 
poverty,  increases  crime,  favors  accidents,  excites  passion  and  diminishes 
self-control ;  it  leads  to  immorality  and  tempts  venereal  infections.  Al- 
cohol increases  economic  waste  and  retards  social  progress.  It  is  not 
a  stimulant.  Its  local  irritating  action  and  its  toxic  effects  upon  nerve 
tissue  account  for  a  certain  amount  of  harm;  but  the  greatest  harm 
perhaps  results  from  the  fact  that  alcohol,  even  in  small  amounts,  clouds 
judgment,  depresses  will  power,  and  takes  the  check  off  self-restraint. 
In  short,  it  stupefies  the  highest  and  noblest  functions  of  the  mind. 

REFERENCES 

An  enormous  number  of  titles  is  included  in  the  available  bibliographies, 

notablj^  those  of  Abderhalden ""  and  Viazemsky."" 
Psychological  Effects  of  Alcohol. — An  Experimental  Investigation  of  the 

Effects  of  Moderate  Doses  of  Ethyl  Alcohol  on  a  Related  Group  of 

Neuro-Muscular  Processes  in  Man.     By  Raymond  Dodge  and  F.  G. 

Benedict.     Pub.  by  the  Carnegie  Institution  of  Washington,  1915. 


SANITARY  SURVEYS 

Sanitary  surveys  are  designed  to  determine  the  general  sanitary  and 
hygienic  conditions  of  a  community.  Surveys  are  often  made  to  discover 
one  OT  more  special  factors;  thus  we  have  tuberculosis  surveys,  school 
surveys,  privy  surveys,  milk  surveys,  water  shed  surveys,  housing  surveys, 
etc.  Survey  means  "to  look,"  and  the  conclusions  must  be  based  on  facts 
obtained  by  observation. 

The  following  is  an  outline  of  the  sanitary  survey  used  by  my  students 
in  the  School  of  Public  Health  and  also  in  the  Harvard  Medical  School. 

""Abderhalden:  Bibliographic  der  gesamten  wissenschaftlichen  Literatur 
iiber  den  Alkohol  und  den  Alkoholismus.  Berlin  and  Vienna,  1904. 

'■"^  Viazemsky :  A  Bibliography  on  the  question  of  alcoholism.  ]\Ioscow.  1909, 
Part  I  (Russian).  The  Russian  original,  together  with  an  English  translation 
made  by  H.  A.  Norman  and  H.  B.  Dine,  are  both  on  file  at  the  Nutrition 
Laboratory. 


494         PUBLIC  HEALTH  MEASURES  AND  METHODS 

SANITARY  SURVEY  OF  A  CITY  OR  TOWN 

Each  student  is  required  to  make  a  sanitary  survey  of  a  city  or  town, 
based  on  the  following  outline,  and  submit  a  written  report  of  the  same. 
The  report  should  consist  of  (a)  data;  (b)  interpretation  of  the  facts, 
and  (c)   criticisms  and  recommendations. 

Introduction. — General  description  of  the  town  including:  (a) 
History,  (b)  Geographical  position,  (c)  Topography,  (d)  Geology, 
(e)  Climate,  (f)  Population  (number  and  constitution),  (g)  Urban, 
suburban,  or  rural,  (h)  Other  information  about  the  town,  (i)  Or- 
ganization of  the  board  of  health. 

Water. —  (a)  The  water  shed — Sources  of  pollution,  methods  of  col- 
lection, storage,  purification,  (b)  An  analysis  of  the  water  and  its 
interpretation,  (c)  Public  or  private  wells,  (d)  Examine  a  sample  of 
the  water  in  the  laboratory. 

Sewage. —  (a)     System    of    disposal — if    purified    or    treated,    how? 

(b)  Efficiency,      (c)   Eelation  to  health  of  this  and  other  towns,     (d) 
Criticism  of  system. 

Garbage,  Refuse,  Ashes. —  (a)   Method  of  collection,     (b)   Disposal. 

(c)  Eelation  to  health,     (d)  Criticism  of  methods. 

Vital  Statistics. —  (a)  Death  rate.  (b)  Infant  mortality.  (c) 
Specific  rates  for:  (1)  Typhoid;  (2)  tuberculosis;  (3)  measles;  (4) 
scarlet  fever,  (d)  Submit  samples  of  blanks  used  by  the  department  of 
health,  especially  those  for  deaths,  births,  marriages,  and  notifiable  dis- 
eases. Fill  out  a  death  certificate  and  a  birth  certificate.  State  opinion 
as  to  thoroughness  of  reporting  morbidity,  mortality,  and  other  vital 
statistics. 

Milk. —  (a)  Report  on  the  sanitary  conditions  of  one  farm  and  one 
city  dairy,  using  score  cards,  (b)  Amount  of  milk  "certified.^'  If  pos- 
sible, visit  and  report  on  farm  producing  it.  (c)  Examine  a  sample  of 
the  milk  in  the  laboratory.     Interpret  result. 

Sanitary  Nuisances. —  (a)  Sources  of  odors,  (b)  Dust — causes  and 
method  of  prevention,  (c)  Rubbish  and  general  cleanliness.  Empty 
lots.  Dumps,  (d)  Plies  and  mosquitoes,  (e)  Rats  and  vermin,  (f) 
Stables  and  manure,  (g)  Breeding  places  of  mosquitoes,  (h)  Smoke, 
(i)  Unnecessary  noises,  (j)  Piggeries,  etc.  (k)  Legal  definition  of 
"nuisance"  and  method  of  abatement. 

Industrial  Hygiene.— (a)  Report  upon  one  industry  based  upon  a 
visit  to  a  factory  or  workshop. 

Housing. —  (a)  Sanitary  condition  of  one  tenement,  (b)  Ventila- 
tion of  one  large  building. 

Infectious  Diseases. —  (a)  Give  a  list  of  the  diseases,  notification  of 
which  is  required  by  the  board  of  health,  (b)  Quarantine  regulations, 
(c)   Methods  of  disinfection  and  fumigation,     (d)   What  measures  are 


MANAGP^MENT  OF  AN  EPIDEMIC  495 

taken  to  prevent  the  spread  of  tuherculosis?  (e)  Should  some  other 
disease  be  prevalent  what  measures  are  taken  to  control  it?  (f)  Venereal 
disoaso>J,  voportino^  and  control. 

Schools. —  (a)  Visit  and  report  on  one  school — ventilation,  lighting, 
temperature,  playgrounds,  etc.  (b)  Medical  inspection  of  school  chil- 
dren. How  conducted?  (c)  Diseases  for  which  cliildrcn  are  excluded 
from  school. 

Miscellaneous. —  (a)  Markets,  (b)  Provision  stores  and  soda  foun- 
tains, (c)  Slaughter  houses  and  meat  inspection,  (d)  Cold  storage 
plants,  (e)  Kitcliens  of  hotels  and  restaurants,  (f)  Wharves,  (g) 
Barber  shops,  (h)  Distribution  of  educational  and  other  pamphlets, 
(i)  Other  activities  of  the  board  of  health,  as  maintenance  of  diagnostic 
laborator}',  meat  inspection,  etc.  (j)  District  nursing  and  social  service, 
(k)  Charitable  institutions  or  organizations  of  importance  to  public 
health.     (1)  City  planning,     (m)  Food  and  drug  administration. 

General  Summary  of  (a)  Conditions  found,  (b)  Criticisms,  (c) 
Recommendations. 

MANAGEMENT  OF  AN  EPIDEMIC  CAMPAIGN 

The  Management  of  an  Epidemic  Campaign. — The  first  essential 
for  success  in  the  suppression  of  an  epidemic  is  a  knowledge  of  the 
epidemiolog}'  of  the  disease.  The  most  important  single  fact  from  a 
practical  standpoint  is  a  knowledge  of  the  mode  of  transfer  of  the 
infection.  Before  we  knew  the  cause  of  yellow  fever,  yellow  fever 
campaigns  were  crowned  with  success  because  we  knew  it  was  transmitted 
through  the  bite  of  a  mosquito.  We  know  the  cause  of  cerebrospinal 
meningitis,  but  there  are  still  uncertain  factors  concerning  its  mode 
of  transmission,  and,  therefore,  our  efforts  against  this  disease  have 
been  unavailing.  The  established  fact  that  hookworm  disease  is  trans- 
mitted by  the  larvae  through  the  skin  is  of  vital  importance  in  the 
control  of  this  disease.  Without  this  knowledge  at  least  90  per  cent, 
of  our  efforts  to  repress  hookworm  disease  would  be  wasted.  When 
typhoid  fever  was  regarded  as  a  water-borne  infection  only  partial  suc- 
cess was  achieved  because  contacts,  milk,  flies,  and  other  modes  of  trans- 
ference of  the  typhoid  bacillus  were  disregarded. 

In  case  the  disease  has  an  intermediate  host  or  the  virus  is  trans- 
ferred by  an  insect  or  other  animal,  a  knowledge  of  the  biology  of  the 
animal  in  question  is  of  prime  importance.  For  example,  the-  habits 
and  habitat  of  the  yellow  fever  mosquito  are  quite  different  from  those 
of  the  malarial  mosquito.  A  campaign  against  the  rat  and  flea  without 
an  acquaintance  with  their  breeding  and  feeding  places  and  the  best 
means  available  to  repress  or  suppress  such  vermin  would  be  unsuc- 
cessful. The  same  is  true  in  our  campaign  against  tuberculosis  with 
reference  to  cattle  and  man;  in  rabies  with  reference  to  dogs  and  other 


496    PUBLIC  HEALTH  MEASUEES  AND  METHODS 

mammals;  in  sleeping  sickness  with  reference  to  the  tsetse  fly;  in  Texas 
fever  with  reference  to  the  tick;  malta  fever  with  reference  to  the  goat; 
relapsing  fever  to  the  bedbug,  and  typhus  fever  with  reference  to  the 
louse,  etc. 

Authority. — Proper  authority  is  necessary  in  order  to  enforce  the 
necessary  measures.  This  authority  may  come  from  the  municipality, 
the  state,  or  the  federal  government.  In  localized  outbreaks,  municipal 
authority  is  sometimes  sufficient.  More  frequently  the  wider  authority 
of  the  state  is  desirable.  In  our  country  it  is  a  recognized  principle  of 
government  that  the  enforcement  of  health  laws  and  regulations  belong 
to  the  police  powers  of  the  individual  states.  In  most  instances  the  inter- 
state powers  of  the  federal  government  are  essential,  especially  as  inter- 
state problems  are  almost  always  involved  in  epidemic  outbreaks. 
The  federal  authority  is  limited  in  health  matters  by  the  constitution. 
It  therefore  cannot  act  within  a  state  unless  invited  to  do  so  by  the 
duly  constituted  authorities  of  the  state.  To  send  government  health 
officers  into  a  state  against  the  will  of  the  state  corresponds  to  the 
sending  of  the  regular  army  into  a  state  to  enforce  measures  against 
the  will  of  the  governor  of  that  state.  Such  extreme  measures  are,  there- 
fore, only  taken  in  times  of  emergency.  Occasionally  a  state,  refusing 
to  take  necessary  action  and  protect  the  other  states,  is  quarantined. 
Thus,  when  California  refused  officially  to  recognize  the  existence  of 
plague  in  1899,  the  federal  government  quarantined  the  entire  state.  On 
account  of  our  dual  form  of  government  it  is  important  that  the  federal 
government,  the  state,  and  the  local  authorities  cooperate  in  a  friendly 
spirit.  Epidemic  diseases  recognize  no  geographical  boundary,  and 
energetic  and  cooperative  action  is  always  called  for  to  suppress  an 
outbreak. 

It  is  the  common  experience  of  those  who  have  to  deal  with  epi- 
demics that  there  is  usually  insufficient  authority  in  law  to  provide  for 
an  emergency.  It  is,  therefore,  often  necessary  to  take  the  bit  in  the 
teeth  and  adopt  arbitrary  measures  which  usually  have  the  support  of 
the  community.  Advantage  may  be  taken  of  an  epidemic  to  obtain  laws 
to  improve  the  health  organization  or  the  powers  of  the  health  officer. 
In  this  way  an  epidemic  serves  a  useful  purpose  in  arousing  action. 

In  the  conduct  of  an  epidemic  it  is  very  important  that  all  the 
authority  should  center  in  one  person.  To  conduct  an  epidemic  with  a 
board  of  health  or  a  health  committee  or  a  commission  of  any  kind  in- 
vites failure.  It  would  be  just  as  foolish  to  have  a  board  of  generals  to 
fight  a  battle.  Those  who  have  been  through  many  epidemics  realize 
that  it  is  no  figure  of  speech  to  compare  an  epidemic  campaign  to  a 
battle.  It  is  a  fight  carried  on  at  high  tension,  and,  although  the  foe 
is  invisible,  it  is  war  in  every  sense  of  the  word.  The  casualties  often 
outnumber  the  bloodiest  conflicts, 


MANAGEMENT  OF  AN  EPIDEMIC  497 

Ways  and  Means. — It  is  ini[)o8.sible  to  carry  on  a  successful  cam- 
paign against  an  epidemic  without  material  resources.  An  epidemic 
campaign  is  expensive  and  success  depends  upon  generous  support.  In 
most  of  the  campaigns  against  yellow  fever,  plague,  and  cholera  that 
have  been  waged  in  this  country  the  expense  has  been  borne  in  part  by 
the  federal  government,  in  part  by  the  municipality  or  state,  and  in  part 
by  private  subscrij)tions.  The  govenmient  has  an  epidemic  fund  ap- 
propriated by  Congress  and  which  is  usually  kept  at  about  a  million 
dollars.  This  fund  is  available  for  plague,  yellow  fever  and  cholera, 
or  other  diseases  specifically  stated  in  the  appropriation  bill. 

Organization. — Headquarters  should  be  organized  in  a  convenient 
part  of  the  city  or  the  infected  area,  and  such  quarters  should  have  all 
the  modern  office  equipment  and  transportation  facilities  necessary  for 
the  quick  dispatch  of  business.  The  city  is  then  divided  into  sanitary 
districts.  These  may  correspond  to  the  political  wards  or  the  police 
districts  and  a  subordinate  is  placed  in  charge  of  the  work  in  each  dis- 
trict. These  districts  are  known  as  sanitary  divisions,  and  the  officer  in 
charge  of  each  division  must  establish  headquarters  for  the  work  of  that 
division.  The  actual  work  is  done  from  division  headquarters,  under  the 
direction  of  the  chief  in  charge  of  the  epidemic. 

It  is  also  necessary  to  establish  a  laboratory  in  case  laboratory  diag- 
nosis is  necessary  for  the  recognition  of  cases  or  carriers,  and  emergency 
hospitals  and  detention  barracks  must  be  provided.  Few  cities  have  suf- 
ficient hospital  facilities  to  meet  a  sudden  emergency.  Temporary  ar- 
rangements must  therefore  be  made.  A  modern  school  building  makes 
a  very  good  hospital  and  may  be  equipped  for  the  reception  of  patients 
at  short  notice.  Various  squads  must  now  be  organized  to  carry  on 
the  particular  work  at  hand.  In  the  case  of  yellow  fever  these  will  be 
mosquito  brigades;  in  the  case  of  plague,  rat  brigades  and  disinfectors, 
and  in  the  case  of  smallpox,  vaccinators,  etc. 

It  is  frequently  desirable,  in  fact  often  necessary,  to  make  a  house 
to  house  inspection  throughout  the  infected  district  in  order  to  collect 
certain  data,  to  determine  whether  cases  are  being  reported  or  hidden, 
and  to  carry  out  special  measures.  These  house  to  house  canvasses  are 
under  the  immediate  direction  of  the  officer  in  charge  of  the  san- 
itary district  and  should  be  repeated  as  often  as  the  occasion  may 
demand. 

It  is  essential  that  all  cases  or  suspected  cases  of  the  disease  be 
promptly  reported,  for  a  case  of  communicable  disease  known  is  a  case 
neutralized.  It  is  the  missed  cases  and  the  hidden  cases  that  are  par- 
ticularly dangerous. 

Education. — A  campaign  of  education  should  be  carried  on  at  the 
same  time  that  the  disease  is  being  attacked.  The  people  are  keenly 
alive  and  hungry  for  information.     Well-worded  articles  in  the  news- 


498    PUBLIC  HEALTH  MEASUEES  AND  METHODS 

papers,  circulars,  pamphlets,  lectures,  demonstrations,  and  the  other 
usual  methods  are  available.  The  education  of  the  community  is  im- 
portant in  order  to  obtain  cooperation,  for  it  is  a  handicap  to  fight  an 
epidemic  without  the  active  support  of  the  people.  While  the  first  duty 
of  the  officer  in  charge  is  to  allay  panic  and  calm  the  unreasonable  fears 
of  the  stricken  community,  the  opposite  extreme  must  be  avoided.  A 
healthy  fear  of  the  disease  is  one  of  the  best  instruments  in  the  armamen- 
tarium of  the  sanitarian.  It  is  almost  hopeless  to  make  progress  against 
disease  where  the  people  supinely  accept  the  conditions.  Thus,  if  the 
people  of  the  United  States  feared  typhoid  fever  as  they  do  yeUovr  fever, 
it  would  soon  diminish  to  the  vanishing  point. 


QUARANTINE 

The  word  "quarantine"  is  derived  from  the  Italian  word  "quaranta," 
meaning  forty.  Its  present-day  meaning  dates  from  the  middle  ages 
when  Venice  and  other  Hanseatic  cities  detained  arriving  ships  with 
cases  of  pestilence  aboard  for  a  period  of  forty  days.  This  was  the  first 
systematic  application  of  maritime  quarantine,  although  from  the  earliest 
times  lepers  were  segregated  as  unclean.  To-day  we  have  many  kinds 
of  quarantine :  maritime  quarantine,  interstate  quarantine,  house  quaran- 
tine, cattle  quarantine,  yellow  fever  quarantine,  "shotgun"  quarantine, 
etc. 

A  technical  distinction  is  now  drawn  between  quarantine  and  isola- 
tion. Quarantine  refers  to  the  detention  of  well  persons  exposed  to  in- 
fection for  the  period  of  incubation  of  the  disease.  Isolation  ^^^  refers  to 
the  segregation  of  the  sick  and  carriers.  The  terms  are  often  used  inter- 
changeably. Precise  knowledge  has  greatly  lessened  the  rigors  of  quaran- 
tine, which  aims  only  at  sanitary  isolation. 

The  dominating  principle  in  modern  quarantine  is  that  it  must  be 
a  sieve  or  filter  and  not  a  dam.  All  quarantines  based  upon  the  prin- 
ciple of  the  Chinese  wall  are  doomed  to  fail.  The  object  of  quaran- 
tine is,  then,  to  destroy,  detain,  or  isolate  infection  with  the  least  pos- 
sible hindrance  to  trade  and  travel.  The  art  consists  in  regulating  the 
openings  in  the  quarantine  sieve  so  as  to  hold  back  certain  infections, 
but  permit  all  else  to  pass.  Maritime  quarantine  may  be  regarded  as 
a  coast  defense  against  exotic  pestilence,  a  defense  which  guards  against 
an  invisible  foe  ofttimes  more  damaging  than  hostile  armies  and 
navies. 

The  cure  for  quarantine  is  sanitation.  Thus,  if  all  communities, 
especially  seaports,  were  to  place  their  cities  in  the  best  sanitary  con- 

""See  page  499. 


QUARANTINE  499 

dition  in  accordance  with  the  teachings  of  modern  science,  there  would 
be  little  danger  of  disease  spreading  to  epidemic  proportions  and  very 
little  need  of  maritime  quarantine.  If  the  ports  in  our  southern  littoral 
would  free  themselves  of  the  Stegomyia  mosquito  they  could  lau<^h  at 
yellow  fever,  A  city  containing  few  rats  could  not  have  an  epidemic  of 
plague.  A  port  supplied  with  a  pure,  well-protected  water  supply  need 
not  fear  a  water-borne  epidemic  or  cholera.  A  thoroughly  vaccinated 
community  runs  no  hazard  from  smallpox.  Typhus  fever  could  not 
spread  in  a  community  with  cleanly  personal  habits,  that  is,  one  free 
from  lice  and  other  vermin. 

ISOLATION 

In  theory  isolation  is  the  most  perfect  single  method  to  check  the 
spread  of  a  communicable  disease.  The  results  in  practice,  however, 
have  been  somewhat  disappointing  on  account  of  unusual  difficulties. 
The  statement  has  frequently  been  made,  especially  with  reference  to 
typhoid  fever,  that  if  all  the  cases  could  be  isolated  (which  includes 
the  disinfection  of  the  discharges)  we  would  soon  see  an  end  of  the 
infection.  We  now  know  that  this  statement  is  not  true,  on  account 
of  the  bacillus  carriers  and  the  mild  and  unrecognized  or  "missed" 
cases.  Because  the  isolation  of  the  reported  cases  represents  only  a 
portion  of  all  the  foci  of  infection  and,  therefore,  at  best  could  not  in 
itself  control  an  epidemic  disease,  discredit  has  been  thrown  upon  this 
procedure,  which  is  one  of  the  essential  features  of  all  systems  of  pre- 
vention. As  a  matter  of  fact,  it  has  been  shown  that  in  certain  diseases, 
like  measles,  which  is  communicable  for  three  days  or  more  before  the 
nature  of  the  disease  is  recognized,  isolation  has  practically  no  influ- 
ence in  diminishing  the  prevalence  of  this  widespread  infection.  It  is 
true  ordinarily  that  a  case  of  measles  does  most  harm  before  it  is 
isolated ;  nevertheless,  this  is  no  reason  why  it  should  be  permitted,  to 
endanger  the  community  further.  The  value  of  isolation  is  also 
diminished  by  the  prevalence  of  carriers.  In  fact,  its  practical  use- 
fulness in  a  given  infection  is  inversely  proportional  to  the  number  of 
carriers. 

If  each  case  isolated  prevents  on  the  average  only  one  other  fresh 
infection,  there  would  still  be  justification  sufficient  to  continue  the 
practice.  As  a  matter  of  fact,  the  practical  value  of  isolation  varies  with 
each  disease,  depending  upon  the  degree  of  its  communicability,  the 
time  when  it  is  communicable,  the  promptness  by  which  it  may  be 
recognized,  the  modes  by  which  it  is  transferred,  the  existence  of  latent 
infections,  missed  cases,  carriers,  and  other  factors  which  influence  the 
spread  of  the  infection. 


500         PUBLIC  HEALTH  MEASURES  AND  METHODS 

Young  ^^  reports  the  results  obtained  from  three  degrees  of  isolation 
in  the  home : 

A — Isolation  with  trained  attendant. 
B — Isolation  without  trained  attendant. 

C — Impossible  to  isolate  for  lack  of  room  for  exclusive  use  of  the 
patient. 

It  was  found  in  the  case  of  scarlet  fever  1.087  per  cent,  of  secondary  cases 
occur  in  Class  A,  5.22  per  cent,  in  Class  B ;  and  6.9  per  cent,  in  Class  C. 
Cases  cared  for  in  hospital  showed  2.32  per  cent,  of  secondary  cases.  In 
the  case  of  diphtheria  there  were  no  secondary  cases  in  Class  A;  1.18  per 
cent,  in  Class  B ;  4.88  per  cent,  in  Class  C ;  and  0.15  per  cent,  in  those 
treated  in  hospital.  These  figures  clearly  show  that  the  value  of  isolation 
depends  upon  the  intelligence  and  care  with  which  it  is  carried  out. 

•  The  degree  of  isolation  varies  markedly  with  the  difi^erent  infections. 
A  case  of  yellow  fever  may  be  isolated  under  a  mosquito  screen,  and  a 
case  of  diphtheria  or  scarlet  fever  may  be  effectively  isolated  in  a  bed  in  a 
general  ward,  provided  intelligent  and  painstaking  care  is  exercised  to 
destroy  the  infection  as  it  leaves  the  body.  Isolation  of  the  more  read- 
ily communicable  diseases,  as  smallpox  and  measles,  should  be  much 
more  absolute.  Typhoid  bacillus  carriers  need  not  be  imprisoned.  It 
is  sufficient  to  limit  their  activities,  especially  to  prevent  their  occupation 
in  kitchens,  dairies,  or  about  foodstuffs.  There  is  no  good  reason  to 
isolate  a  consumptive  or  leper  without  open  lesions — that  is,  cases  in 
which  the  bacilli  are  imprisoned  in  the  tissues  and  not  discharged  into 
the  environment.  A  careful  consumptive  or  leper  may  be  allowed  a 
wide  latitude.  On  the  other  hand,  isolation  in  chronic  infections,  such 
as  tuberculosis  and  leprosy,  with  open  lesions,  is  the  most  helpful  and 
at  the  same  time  the  most  difficult  single  procedure  we  have  to  control 
their  spread.  The  careless,  indigent,  ignorant,  or  helpless  consumptive  is 
a  public  menace  that  needs  energetic  and  sometimes  arbitrary  isolation. 
Isolation  may  most  readily  and  effectively  be  carried  out  in  hospitals 
or  sanatoria.  Proper  isolation  in  the  home  requires  a  special  room 
or  rooms,  intelligent  nursing,  appliances  for  disinfection,  etc.,  a  com- 
bination often  difficult  to  arrange.  House  quarantine  varies  with  the 
different  diseases.  To  carry  it  out  rigorously  in  all  cases  and  under  all 
conditions  is  folly.  Different  diseases  need  different  procedures.  Some- 
times it  is  sufficient  simply  to  placard  the  house  as  a  warning.  At  other 
times  it  may  be  necessary  to  station  sanitary  guards  about  the  premises 
to  enforce  the  quarantine.  The  imperfections  of  strict  isolation  by  the 
"shutting  in  of  houses"  are  graphically  described  in  Defoe's  "Journal  of 
the  Plague  Year." 

^^Jour.  A.  M.  A.,  Feb.  6,  1915,  LXIV,  6,  p.  488. 


QUARANTINE  501 

Isolation  camps  or  temporary  barracks  in  times  of  epidemics  are 
effective  measures  in  cheeking  the  spread  of  some  infections.  This 
method  has  proved  effective  in  actual  practice  in  the  case  of  smallpox, 
yellow  fever,  plague,  cholera,  and  other  diseases. 

It  often  becomes  a  difficult  question  to  determine  whether  the  well 
members  of  a  household  should  also  be  quarantined — especially  whether 
the  well  children  should  be  permitted  to  attend  school.  This  perplex- 
ing question  must  be  decided  for  each  disease  separately,  and  the  de- 
cision in  each  disease  is  sometimes  modified  by  attending  factors.  Usu- 
ally the  other  children  in  the  family  in  the  case  of  scarlet  fever  are 
excluded  from  school  for  four  weeks  from  the  beginning  of  the  last  case. 
In  most  cities  the  same  rule  holds  for  diphtheria,  although  here  we  are 
able  to  determine  whether  the  children  are  bacillus  carriers  or  not. 
At  least  two  negative  cultures  from  the  nose  and  throat  should  be  re- 
quired before  such  children  are  allowed  freely  to  mingle  with  other 
children.  The  principal  factors  which  determine  whether  the  well 
children  in  a  family  shall  be  permitted  to  attend  school  or  not  in  any 
particular  infection  rests  upon  our  knowledge  as  to  whether  the  disease 
is  conveyed  by  a  third  person  and  the  frequency  of  bacillus  carrying 
and  of  missed  cases. 

Isolation  becomes  one  of  our  most  valuable  public  health  measures 
when  communicable  diseases  affect  persons  working  about  milk,  meat, 
and  other  foods  capable  of  conveying  infection. 

One  of  the  practical  objections  to  isolation  and  one  reason  that  it 
meets  with  so  much  opposition  from  the  public  is  that  the  compensa- 
tion of  the  wage  earner  ceases  through  no  fault  of  his  own.  It  is  evi- 
dently unjust  practically  to  imprison  and  punish  a  wage  earner  for  the 
good  of  the  community,  because  he  or  some  member  of  his  family  has 
contracted  an  infection,  perhaps  through  some  fault  of  the  community 
itseK.  It  is,  therefore,  reasonable  and  just  that  wage  earners  at  least 
should  be  compensated  and  their  personal  interests  safeguarded  during 
enforced  isolation. 

In  practice,  isolation  only  reduces  to  a  moderate  degree  the  prevalence 
of  disease.  The  limitations  of  this  valuable  procedure  are  now  well  un- 
derstood. With  improved  methods  of  diagnosis  and  increased  knowledge 
of  the  methods  of  the  spread  of  disease,  isolation  will  be  made  increas- 
ingly effective.  Every  case  isolated  is  a  focus  of  infection  neutralized. 
Although  not  as  satisfactory  in  practice  as  it  is  in  theorj',  isolation  will 
ever  remain  one  of  the  chief  administrative  procedures  for  the  control 
of  the  communicable  diseases. 

In  the  past,  geographic  isolation  was  one  of  the  safeguards  of  the 
people  against  disease,  but  in  modern  times,  since  all  means  of  trans- 
portation have  improved,  and  communication  has  become  more  extended 
and  more  rapid,  the  diffusion  of  infection  is  facilitated. 


503         PUBLIC  HEALTH  MEASURES  AND  METHODS 

MARITIME  QUARANTINE 

Maritime  quarantine  in  this  country  is  enforced  only  against  six  dis- 
eases, viz.,  cholera,  yellow  fever,  plague,  typhus  fever,  smallpox,  and 
leprosy.  We  do  not  quarantine  against  typhoid  fever,  tuberculosis, 
measles,  and  other  infections  which  are  not  greatly  feared  and  which  are 
constantly  with  us.  Infections  of  a  non-quarantinable  nature,  such  as 
scariet  fever,  measles,  etc.,  arriving  at  a  port  are  permitted  to  enter, 
but  must  then  comply  with  the  local  laws  and  regulations. 

The  period  of  detention  is  based  upon  the  usual  period  of  incubation 
for  each  disease  and  is  as  follows: 

Cholera   5    days. 

Yellow  fever 5,  sometimes  6  days. 

Plague    7    days. 

Typhus  fever 12    days. 

Smallpox    14    days._ 

Leprosy  not  admitted. 

The  time  of  detention  is  usually  counted  from  the  completion  of 
disinfection  or  at  least  from  the  last  possible  exposure  to  the  infection. 
This  is  usually  not  a  very  difficult  matter  for  the  quarantine  officer  to 
decide,  but  in  case  of  doubt  the  public  is  given  the  benefit. 

At  well-equipped  stations  where  laboratory  facilities  are  available  it 
is  not  necessary  to  detain  cholera  contacts  for  the  full  period  of  incuba- 
tion. Stool  examinations  for  vibrios  will  furnish  reasonably  dependable 
evidence  upon  which  to  hold  or  release  those  persons  who  have  been  ex- 
posed to  infection.  In  the  case  of  smallpox,  those  who  have  had  the 
disease  or  have  recently  been  successfully  vaccinated  need  not  be  de- 
tained. 

No  communication  is  permitted  with  a  vessel  in  quarantine  except- 
ing under  supervision  of  the  quarantine  officer ;  that  is,  no  one  is  allowed 
to  board  the  vessel  or  leave  it,  and  nothing  is  allowed  to  be  thrown  over- 
board, taken  ashore,  or  brought  on  board  without  the  express  permission 
of  the  quarantine  officer.  These  restrictions  apply  alike  to  foods  and  to 
supplies  and  merchandise  of  all  kinds. 

The  vessel  itself  may  be  disinfected  and  furnished  with  a  fresh  crew 
and  released  from  quarantine  while  the  passengers  and  crew  are  detained 
in  suitahle  barracks.  Vessels  trading  with  infected  ports  should  carry 
immuiie  crews;  that  is,  persons  who  have  either  had  the  disease  or  have 
been  rendered  actively  immune  through  one  of  the  vaccines  or  viruses. 

When  a  quarantinable  disease  breaks  out  on  board  a  vessel  it  is  of 
practical  importance  for  the  quarantine  officer  to  determine  whether  the 
infection  was  contracted  on  board  the  vessel  or  on  land.  In  the  first  case 
the  vessel  must  be  regarded  as  infected  and  the  measures  used  for  its 
purification  are  much  more  exacting  than  in  the  second  case.     Thus,  if 


QUARANTINE  503 

plague  breaks  out  within  seven  days  from  the  time  a  vessel  leaves  an  in- 
fected port,  and  no  other  case  occurs,  it  is  exceedingly  probable  that  the 
patient  contracted  his  disease  ashore  and  was  in  the  period  of  incubation 
when  he  came  on  board.  If,  however,  plague  breaks  out  after  seven  days, 
and  especially  if  secondary  cases  occur,  it  is  evident  that  the  ship  itself 
is  infected.  The  same  reasoning  applies  to  yellow  fever  and  the  other 
communicable  diseases. 

The  measures  taken  at  quarantine  to  keep  out  these  diseases  depend 
upon  an  accurate  knowledge  of  their  cause  and  mode  of  transmission. 
Briefly  summarized,  the  measures  applicable  in  each  case  are  as  follows : 

CHOLERA 

The  sick  are  removed  from  the  vessel  and  isolated.^  Due  care  is 
taken  as  to  disinfection  and  disposal  of  the  patients'  discharges.  Eating 
utensils  and  all  other  articles  used  in  the  sick  room  should  be  disinfected 
before  removal,  and  the  room  should  be  well  screened  to  exclude  flies. 

All  suspected  cases,  especially  those  with  gastro-intestinal  symptoms, 
should  be  isolated  and  treated  as  positive  cases  until  laboratory  examina- 
tion indicates  the  correct  diagnosis.  All  contacts  are  segregated  in 
small  groups  and  stool  examination  instituted  immediately  for  the  pur- 
pose of  detecting  "carriers." 

In  the  meantime,  steps  have  been  taken  to  destroy  all  sources  of 
infection  on  board  the  vessel.  The  probabilities  of  infection  on  board 
can  largely  be  deteirmined  from  the  history  of  the  outbreak.  If  it  has 
been  of  an  "explosive"  type,  an  infection  of  the  water  supply  is  sug- 
gested. This  can  readily  be  determined  by  a  bacteriological  examina- 
tion of  the  water,  considering  the  presence  of  B.  coli  as  an  indicator,  or 
even  testing  for  the  cholera  vibrio.  If  there  be  any  scarcity  of  fresh 
water,  a  ship's  supply  should  not  be  condemned  unexamined.  If  there 
be  ample  fresh  water  available,  the  ship's  supply  can  be  disinfected  by 
the  addition  of  bleaching  powder  or  permanganate  of  potash  to  the  tanks, 
then  pumping  them  out,  after  which  a  fresh  supply  of  water  is  furnished. 
Or  otherwise,  the  water  supply  can  be  purified  by  the  addition  of  h}"po- 
chlorite  of  lime. 

If  the  voyage  has  consumed  a  number  of  days  and  there  are  only  a 
few  cases,  the  source  of  infection  will  generally  be  proved  to  be  a  carrier 
or  carriers.  The  protected  water  supply  and  water  carriage  system  of 
sewage  disposal  on  modern  vessels  have  materially  altered  the  potentiali- 
ties of  cholera  infection  on  ships.  Formerly  and  before  these  sanitary 
conveniences  were  provided,  the  appearance  of  a  case  of  cholera  on  a 
vessel  was  often  followed  by  contamination  of  the  water  supply  and  most 
of  the  passengers  and  crew  were  sooner  or  later  attacked  if  the  voyage 
was  a  length}^  one. 


504         PUBLIC  HEALTH  MEASURES  AND  METHODS 

As  an  added  precaution  for  safety  in  carrying  out  preventive  meas- 
ures on  a  cholera-infected  ship,  fruits  and  vegetables  that  are  generally 
not  cooked  before  being  eaten  should  be  destroyed.  The  clothing  and 
baggage  of  the  sick  and  carriers  should  be  disinfected,  preferably  by 
steam,  but  this  is  not  necessary  with  respect  to  the  ship's  personnel  in 
general.  The  bichlorid  baths  formerly  in  vogue  are  probably  a  waste 
of  time. 

Generally  speaking,  no  treatment  is  demanded  of  the  cargo  as  the 
holds  remain  sealed  throughout  the  voyage  and  the  chance  of  contamina- 
tion is  nil. 

Fumigation  or  disinfection  of  the  ship  is  not  necessary  except  in 
compartments  that  have  contained  the  sick  or  carriers,  and  thereby  may 
have  been  contaminated.  In  this  event,  the  floors  and  lower  walls  of 
such  compartments  should  be  washed  down  with  a  solution  of  carbolic 
acid  or  bichlorid  of  mercury,  or  other  equally  satisfactory  disinfectant. 
This  would  be  one  of  the  few  instances  in  which  bactericidal  measures 
are  still  called  for  in  maritime  quarantine  procedure.  The  bedclothes, 
mattresses  and  other  fabrics  from  the  compartment  where  the  sick  have 
been  should  be  steamed  or  soaked  in  a  germicidal  solution.  Other  than 
this  no  disinfection  of  the  ship  is  called  for. 

The  important  element  in  the  treatment  of  a  cholera-infected  ship 
(so-called  "infected  ship"  although  the  ship  itself  usually  is  not  infected 
at  all,  but  merely  the  personnel)  is  the  detection  and  isolation  of  cases 
and  carriers  with  the  safe  disposal  of  their  dejecta,  until,  by  laboratory 
examination,  they  are  proved  to  be  free  of  cholera  vibrio. 

If  the  quarantine  station  be  not  provided  with  adequate  laboratory 
facilities,  in  order  to  ascertain  whether  there  are  carriers,  contacts  will 
have  to  be  detained  for  the  period  of  incubation,  i.  e.,  five  days.  The 
detention  of  contacts  for  five  days  after  the  exposure  to  infection  was 
formerly  considered  to  be  sufficient  and  will  serve  the  purpose  of  ex- 
cluding active  cases  of  the  disease.  In  more  recent  years,  however,  the 
important  role  played  by  carriers  makes  it  essential  that  a  bacteriological 
examination  should  be  performed.     See  page  144. 

SMALLPOX 

Ordinarily  those  who  have  had  smallpox  or  who  have  had  a  recent 
successful  vaccination  are  not  detained.  All  others  must  submit  to 
vaccination.  Persons  declining  vaccination  are  detained  for  the  full 
period  of  14  days  before  they  are  released.  As  a  rule,  it  is  not  necessary 
to  detain  cabin  passengers  because  there  is  smallpox  in  the  steerage,  or 
to  detain  the  firemen  because  there  is  smallpox  among  the  stewards. 
Vessels  arriving  with  smallpox  on  board  on  which  the  cases  have  been 
properly  isolated,  personnel  vaccinated,  and  other  sufficient  precautions 


QUARANTINE  505 

taken  to  prevent  the  spn-ad  of  tlic  disease,  need  not  he  quarantined 
fnrther  than  the  removal  of  the  sick,  the  disinfection  of  compartments, 
baggage,  and  objects  tliat  have  been  exposed  to  tl)e  liability  of  infection. 

PLAGUE 

In  the  management  of  a  plagiic-inrt'cicd  vessel,  a  sharp  distinction 
should  be  made  between  bubonic  plague  and  pneumonic  plague.  From 
a  quarantine  standpoint,  they  are  two  separate  diseases,  one  transmitted 
by  insect  bite,  and  the  other  by  direct  contact. 

Pneumonic  plague  is  a  primary  pneumonia,  the  epidemiologic  factors 
of  which  appear  to  be  more  or  less  the  same  as  in  pneumococcus  or  influ- 
enza pneumonia.  Bubonic  plague  is  transmitted  solely  by  insects,  chiefly 
fleas,  but  possibly  and  on  rare  occasions  by  bedbugs. 

Thus  far,  pneumonic  plague  has  been  largely  confined  to  limited 
geographic  areas,  generally  a  northern  climate — North  Asia  and  the 
northern,  higher  regions  of  India.  A  few  cases  of  pneumonic  plague 
have  recently  (1919)  occurred  in  California.  This  form  of  the  disease 
has  not  been  detected  on  any  incoming  vessel.  Not  infrequently  there 
is  a  secondary  pneumonia  in  cases  of  bubonic  plague,  but  this  condition 
is  of  no  sanitary  significance,  and  is  distinctly  different  from  the  so- 
called  pneumonic  plague. 

Bubonic  Plague. — The  treatment  of  a  vessel  infected  with  bubonic 
plague  should  be  directed  towards  the  destruction  of  all  rats  and  fleas. 
Eats  found  dead  or  killed  by  fumigation  should  be  immersed  in  coal  oil 
and  autopsied  if  possible,  but  in  all  cases  the  carcasses  should  finally  be 
burned. 

It  is  not  necessary  to  detain  passengers  and  crew  who  are  in.  good 
health  any  longer  than  is  incidental  to  the  disinfection  of  the  vessel. 

Formerly,  much  stress  was  laid  on  the  examination  of  passengers 
and  crew,  but  there  is  no  record  of  bubonic  plague  ever  having  been  in- 
troduced into  any  port  or  place  by  infected  man.  It  is  only  the  infected 
rat  or  flea  that  carries  the  disease  from  one  locality  to  another. 

In  handling  an  infected  vessel  it  is  first  necessary  to  make  sure  that 
no  rat  may  escape.  Preferably,  the  ship  remains  at  anchor  in  quaran- 
tine, or  otherwise  may  tie  up  alongside  the  quarantine  station  wharf, 
with  all  mooring  lines  protected  by  metal  discs  three  feet  in  diameter 
fixed  at  right  angles  to  the  hawser  to  which  they  are  attached..  The 
discs  act  as  barriers  to  the  passage  of  rats  from  ship  to  shore.  After 
the  passengers  and  crew  are  removed  to  the  quarantine  station,  the  vessel 
must  be  simultaneously  fumigated  in  all  parts  to  destroy  rats  and  fleas. 
Hydrocyanic  acid  gas  is  the  most  efficient  fumigating  agency,  but  it  is 
very  dangerous  and  should  be  used  only  by  those  especially  trained. 

Sulphur  dioxid  is  not  very  effective  if  the  vessel  be  cargo  laden,  and 


606    PUBLIC  HEALTH  MEASUEES  AND  METHODS 

is  at  times  very  injurious  to  certain  kinds  of  cargo,  such  as  tea,  silk, 
coffee,  tobacco, 'etc.,  and  to  ship  furnishings,  and  will  often  discolor  paint, 
particularly  white  lead  pigment.  It  is  safe,  however,  and  fairly  effective 
when  the  compartment  is  empty  and  penetration  and  diffusion  not  so 
essential.  Details  of  ship  fumigation  are  described  under  separate  head- 
ing on  page  513. 

Funnel  gas  (carbon  monoxid)  is  not  lethal  to  insect  life,  and,  while 
satisfactory  for  ordinary  rat  destruction,  it  should  not  be  employed  for 
this  purpose  on  plague-infected  ships,  as  it  will  not  kill  fleas. 

Eodent  destruction  on  a  cargo-laden  vessel  is  best  accomplished  by 
repeated  fumigations,  the  upper  layers  of  cargo  being  discharged  after 
each  fumigation. 

While  it  is  ordinarily  not  necessary  to  disinfect  the  clothing  and 
personal  effects  of  passengers  and  crew,  as  fleas  are  seldom  found  on 
them,  certain  groups  of  persons  require  attention  along  this  line.  Las- 
cars and  other  Asiatic  crew  men  harbor  fleas  in  the  voluminous  folds  of 
linen  or  cotton  (generally  soiled)  with  which  they  swathe  their  bodies. 
The  quarantine  officer  must  necessarily  exercise  discretion  as  to  the 
disinfection  of  the  clothes  and  personal  effects  of  passengers  and  crew. 
•  Domestic  animals,  particularly  cats  and  dogs,  demand  special  atten- 
tion on  infected  vessels.  When  there  has  been  a  great  mortality  among 
the  rodent  population,  the  dislodged  fleas  are  very  prone  to  secure  tem- 
porary quarters  on  cats  and  dogs,  and  thus  these  pets,  themselves  immune 
to  plague,  may  become  a  serious  menace.  These  animals  should  be 
thoroughly  immersed  in  a  coal  oil  emulsion  so  as  to  kill  all  parasites. 

Pneumonic  Plague; — In  the  treatment  of  a  vessel  infected  with  pneu- 
monic plague,  the  sick  should  be  carefully  isolated  and  passengers  and 
crew  segregated  in  small  groups.  Kecovered  cases  should  not  be  dis- 
charged until  a  bacteriological  examination  of  the  secretions  of  the  nose 
and  throat  show  absence  of  B.  pestis,  as  cases  may  become  carriers,  at  least 
for  a  short  period  of  time.  Contacts  should  be  detained  seven  days  be- 
'fore  release.  Special  care  should  be  exercised  to  detect  new  cases 
amongst  the  groups  of  contacts.  Temperature  should  be  taken  twice 
daily,  and  any  person  developing  the  least  rise  of  temperature  should  be 
immediately  isolated  and  held  under  observation  until  the  diagnosis  is 
established. 

Kitchen  and  dining  room  utensils  used  by  the  sick  or  convalescent 
should  be  thoroughly  sterilized.  On  ship  all  living  quarters  should  be 
disinfected  and  washed  down  with  a  solution  of  bichlorid  of  mercury  or 
other  germicide.  Personal  effects  and  bed  clothes  should  be  disinfected 
by  steam. 

With  reference  to  measures  for  excluding  plague  infection,  it  is  neces- 
sary to  institute  preventive  measures,  not  only  against  vessels  known  to 
be  infected,  but  it  is  also  important  that  the  same  measures  be  carried 


QUARANTINE  507 

out  against  vessels  arrivin^^  I'loiii  ports  known  to  l)e  infected  with  rodent 
plagne.  Infection  may  have  hccn  introduced  into  the  holds  of  the 
vessel  and  spread  amongst  the  rats  without  any  evidence  of  the  disease 
being  noted.  Human  cases  on  hoard  a  vessel  would  probahly  not  appear 
unless  there  he  infected  rats  in  the  superstructure.  It  is  entirely  pos- 
sible for  rodent  infection  to  remain  quiescent  in  tlie  hold  of  a  vessel, 
or  for  an  un(k^tected  epizootic  to  prevail  amongst  the  rats  in  the  hold, 
even  though  the  voyage  may  have  consumed  several  weeks.  Infected  rats 
have  been  taken  from  the  holds  of  vessels  that  have  been  out  from  an 
infected  port  for  several  weeks,  notwithstanding  wdiich  there  were  no 
human  cases  reported  and  no  extensive  epizootic  amongst  the  rodents. 
See  also  page  331. 

YELLOW  FEVER 

Vessels  arriving  at  an  infectible  port  from  an  infected  port  are 
fumigated  aud  detained  five  days  as  a  precautionary  measure  during 
the  yellow  fever  season,  even  though  there  is  no  evidence  of  sickness  on 
board.  The  yellow  fever  season  usually  extends  from  May  1  until 
October  1.  The  infectible  ports  are  those  situated  upon  the  Atlantic 
seacoast  soutli  of  the  Chesapeake  and  those  on  the  Gulf  of  Mexico. 

Five  days  covers  the  period  of  incubation  of  most  cases  of  yellow 
fever  and  is  sufficient  as  a  precautionary  measure,  but  in  special  in- 
stances, as,  for  example,  if  a  case  of  yellow  fever  has  occurred  on  board 
the  vessel,  then  the  detention  is  six  days  following  fumigation.  The 
sick  are  isolated  by  the  use  of  mosquito  screens.  Patients  with  yellow 
fever  should  not  be  moved  if  this  involves  exertion  or  excitement,  which 
may  aggravate  the  disease. 

The  vessel  is  fumigated  with  an  insecticidal  substance,  preferably 
SO,,  or  HCN,  in  order  to  kill  the  Stegomyia  adopm.  A  search  is  made 
for  breeding  places,  such  as  water  casks,  fire  buckets,  and  other  collec- 
tions of  fresh  water  where  the  Stegomyia  larvae  and  pupae  may  develop. 
The  disinfection  of  baggage  and  fomites  is  no  longer  practiced  in  the  case 
of  yellow  fever.  Experience  has  sho-RTi  that  wooden  vessels  are  more  apt 
to  convey  yellow  fever  than  iron  vessels.  This  is  because  wooden  vessels 
carry  water  casks,  which  are  the  favorite  breeding  places  for  the  mos- 
quito, while  iron  vessels  store  their  drinking  water  in  tight  compartments 
deep  in  the  hold,  inaccessible  to  mosquitoes.  Vessels  plying  between 
infected  and  infectible  ports  should  carry  immune  crews.  See  page 
295. 

TYPHUS  FEVER 

Typhus  fever  is  one  of  the  quarantinable  diseases  in  which  if  one 
case  appears  on  board  a  vessel  there  are  apt  to  be  several,  especially  if 


608    PUBLIC  HEALTH  MEASURES  AND  METHODS 

the  infection  develops  amongst  the  crew  or  steerage  passengers,  and 
hence  all  possible  contacts  should  be  detained  in  quarantine  for  the 
full  period  of  incubation,  which  is  12  days. 

If  the  disease  has  been  confined  to  the  steerage,  there  is  no  necessity 
for  detaining  cabin  passengers,  and  vice  versa.  If  the  disease  has  ap- 
peared only  in  the  crew  quarters,  and  these  are  well  separated  from  the 
passenger  quarters,  there  is  no  occasion  for  the  detention  of  the  pas- 
sengers. 

First  of  all,  the  sick  should  be  removed  to  the  quarantine  hospital 
and  their  clothing,  personal  effects  and  baggage  thoroughly  treated  for 
the  destruction  of  lice.  The  patient's  body  is  treated  with  a  delousing 
solution  (mixture  of  kerosene  and  vinegar  in  equal  parts,  or  kerosene 
and  soft  soap),  and  the  application  of  some  such  solution  is  especially 
important  for  the  destruction  of  head  lice.  The  hair  should  be  clipped 
not  only  on  the  head  but  also  in  the  pubic  and  axillary  regions,  the  clip- 
pings burned,  and  finally,  the  patient  given  a  thorough  bath. 

Clothing  is  best  disinfected  by  steam.  Hydrocyanic  acid  is  very 
effective  for  the  destruction  of  lice,  but  is  not  a  germicide. 

All  contacts  should  be  passed  through  the  baths,  first  being  treated 
with  a  delousing  solution,  and  their  clothing  and  baggage  should  be  dis- 
infected. 

Those  detained  should  be  segregated  in  small  groups  and  tempera- 
tures taken  twice  daily,  but  if  the  delousing  procedure  has  been  efficiently 
performed,  secondary  cases  are  of  no  sanitary  consequence.  To  be  on 
the  safe  side,  however,  secondary  cases  should  be  isolated  immediately 
upon  their  detection. 

As  to  the  treatment  of  the  ship,  no  action  is  called  for  other  than  the 
assured  destruction  of  lice  in  living  quarters.  The  galleys,  storerooms 
and  holds  need  no  treatment  unless  there  be  unusual  circumstances  that 
render  them  probably  vermin-infested.  Staterooms,  crew  quarters  and 
steerage  compartments  should  be  fumigated  with  sulphur  dioxid  or  hy- 
drocyanic acid  gas  (technic  as  described  on  page  513),  with  bedclothes 
and  furnishings  remaining  in  place.  After  fumigation  the  vessel  may  be 
released  with  the  personnel  that  have  not  been  exposed — a  new  crew 
being  furnished,  if  necessary. 

Ine  important  feature  in  the  treatment  of  typhus  is  that  all  vermin 
should  be  destroyed,  cases  detained,  and  contacts  isolated  until  the  period 
of  incubation  has  elapsed.     See  page  370. 

LEPEOSY 

An  alien  leper  is  not  allowed  to  land.  The  law  requires  the  vessel 
on  which  he  arrives  to  take  him  back  again.  It  is  unconstitutional  to 
forbid  the  landing  of  an  American  leper,  but  as  soon  as  he  lands  he 


QUARANTINE  609 

comes  under  tlie  laws  of  tlie  city  or  ^Uito  in  which  he  finds  himself. 
Alien  lepers  are  detained  at  the  quarantine  station  and  placed  aboard 
again  wlicii  the  vessel  is  outward  hound. 

Quarantine  Procedures. — All  vessels  arriving  at  any  port  in  the 
United  States  from  a  foreign  port  are  considered  to  be  in  quarantine 
until  they  are  given  free  practique.  The  pracflque  is  a  certificate  signed 
by  the  quarantine  officer  to  the  effect  that  the  vessel  and  all  on  board  are 
free  from  quarantinable  disease,  or  the  danger  of  conveying  the  same. 
In  other  words,  free  practique  is  a  permit  issued  by  the  quarantine  officer 
which  the  master  of  the  vessel  must  present  to  the  collector  of  the  port 
in  order  that  his  vessel  may  be  admitted  to  entry. 

Vessels  in  quarantine  are  required  to  fly  a  yellow  flag  (letter  "Q" 
of  the  International  Code)  from  the  foremast.  The  quarantine  officer 
boards  the  vessel  usually  upon  the  starboard  side  and  examines  the  bill 
of  health,  the  ship  itself,  the  passengers,  the  crew,  as  well  as  the  mani- 
fests of  cargo,  and  sometimes  the  food  and  water  supplies,  etc.  Vessels 
arriving  after  sundown  must  wait  until  sunrise  for  this  inspection ;  the 
time  and  details,  however,  vary  greatly  and  depend  upon  circumstances. 
Thus,  at  the  port  of  Boston,  there  may  be  no  more  need  to  examine  ves- 
sels bringing  residents  of  London  or  Paris  than  there  w'ould  be  to  ex- 
amine a  trainload  of  passengers  from  Xew  York. 

The  detection  of  infection  on  board  a  vessel  requires  knowledge, 
tact,  and  sometimes  a  detective  instinct  on  the  part  of  the  quarantine 
officer.  Where  one  of  the  communicable  diseases  is  suspected  the  tem- 
perature of  every  person  on  board  should  be  taken.  As  a  rule,  all  hands 
are  mustered  at  a  designated  place  on  board  the  ship  and  then  passed 
in  review,  one  by  one,  before  the  examining  physician;  the  number  of 
persons  are  counted  and  compared  with  the  ship's  papers;  each  person 
is  critically  scrutinized  for  evidence  of  disease,  and  suspects  are  placed 
aside  for  more  careful  examination  later.  The  clinical  records  of  the 
ship's  surgeon  are  inspected  with  special  reference  to  the  diagnosis  of 
those  who  have  received  medical  care  during  the  voyage.  The  manifest 
of  cargo  is  examined  for  second-hand  goods,  upholstered  furniture,  bed- 
ding, hides,  hair,  or  other  objects  that  may  require  disinfection.  Finally, 
the  ship  itself  is  inspected,  attention  being  given  especially  to  the  fore- 
castle, steerage  quarters,  the  galley,  etc. 

The  Bill  of  Health.— The  United  States  Bill  of  Health  is  a  docu- 
ment issued  by  our  consul  at  the  port  of  departure  to  the  master  of 
the  vessel.  The  Bill  of  Health  contains  a  complete  description  of  the 
vessel,  the  number  of  officers,  crew^,  and  passengers  (cabin  and  steer- 
age), its  sanitary  history,  and  the  sources  and  wholesomeness  of  water, 
food  supply,  etc.  Finally,  it  contains  a  statement  giving  the  number 
of  cases  and  deaths  from  yellow  fever,  cholera,  smallpox,  typhus  fever. 


510    PUBLIC  HEALTH  MEASURES  AND  METHODS 

plague,  and  leprosy  at  the  port  of  departure  during  the  two  weeks  pre- 
ceding the  sailing  of  the  vessel. 

The  American  Bill  of  Health,  which  is  a  formidable  document,  must 
be  obtained  by  the  master  of  the  vessel  in  duplicate,  and  presented  to 
the  quarantine  officer  at  the  vessel's  port  of  destination.  After  these 
documents  have  served  their  purpose  in  affording  to  the  quarantine 
officer  the  necessary  information  concerning  quarantine  inspection  of 
the  vessel,  the  bills  of  health  are  returned  to  the  master  of  the  vessel  and 
by  him  surrendered  to  the  Collector  of  Customs. 

The  Bill  of  Health  is  a  consular  document  (State  Department)  at 
the  port  of  departure,  but  becomes  a  customs'  paper  (Treasury  Depart- 
ment) at  the  ]3ort  of  entry.  A^essels  arriving  at  any  port  in  the  United 
States  or  its  dependencies  from  a  foreign  port  without  this  official  Bill 
of  Health  in  duplicate  are  subject  to  a  fine  of  $5,000.  Before  the  days 
of  telegraphy  the  Bill  of  Health  was  an  important  document  and  often 
gave  the  quarantine  officer  the  first  information  of  pestilential  disease 
abroad.  The  quarantine  officer  must  now  keep  himself  informed  not  only 
of  the  health  conditions  of  the  port  of  departure,  but  of  the  places  from 
which  the  passengers  and  crew  are  recruited. 

There  are  many  kinds  of  bills  of  health;  each  country  has  a  form 
of  its  own.  Formerly  a  bill  of  health  was  simply  a  statement  that  the 
port  of  departure  was  or  was  not  free  of  pestilential  disease;  that  is,  the 
bill  of  health  was  either  "clean"  or  "foul."  The  American  Bill  of 
Health  gives  much  more  valuable  information  in  detail.  The  only  bill 
of  health  that  is  of  service  to  the  vessel  upon  arrival  is  the  American 
Bill  of  Health,  although  several  bills  of  health  may  be  issued  to  the 
vessel  at  the  port  of  departure'.  Thus,  a  British  vessel  leaving  the  port 
of  Eio  de  Janeiro  takes  three  bills  of  health,  one  from  the  British  con- 
sul, required  by  the  British  admiralty  laws,  another  from  the  Brazilian 
authorities,  which  is  a  clearance  paper,  and  the  third  from  the  Amer- 
ican consul,  which  is  the  only  one  of  service  upon  reaching  a  port  in 
the  United  States. 

The  Equipment  of  a  Quarantine  Station. — The  equipment  of  a 
quarantine  station  consists  of  wharves,  boarding  vessels,  such  as  tugs, 
launches,  and  rowboats;  of  an  inspection  place  where  passengers,  crew, 
and  suspects  may  be  examined  (the  facilities  on  board  the  ship  are  usu- 
ally inadequate  for  this  purpose)  ;  of  disinfecting  apparatus  for  the  use 
of  steam,  sulphur  dioxid,  formaldehyd,  and  insecticides;  shower  baths; 
detention  barracks  for  steerage,  intermediate,  and  cabin  passengers,  as 
well  as  the  crew  of  the  vessel;  isolation  wards  in  which  cases  of  the 
quarantinable  diseases  may  be  cared  for,  and  special  wards  where  sus- 
pects or  non-contagious  cases  may  receive  treatment.  A  well-equipped 
quarantine  station  further  needs  dining-rooms  and  kitchens  for  the  vari- 
ous-groups detained;  quarters  for  the  quarantine  officers  and  help;  a 


QUARANTINE  511 

wharf  and  boat  house,  and  some  provisions  for  recreation  of  those  in 
quarantine  to  dispel  the  ennui  of  tlio  isohition.  Finally,  a  crematory,  a 
steam  laundry,  and  special  arrangements  for  the  disposal  of  sewage  and 
garbage  are  important. 

A  laboratory  is  an  essential  feature  of  a  modern  quarantine  station. 
It  is  necessary  in  order  to  make  diagnoses  and  to  recognize  bacillus  car- 
riers, etc.  In  other  words,  a  quarantine  station,  on  account  of  its  im- 
portance and  isolation,  must  be  a  well-equipped  and  self-supporting  com- 
munity. 

Qualifications  of  the  Quarantine  Officer. — A  quarantine  officer  must 
necessarily  be  a  good  diagnostician.  He  should  have  an  especial  acquaint- 
ance with  the  diseases  against  which  he  stands  monitor.  The  diagnosis 
of  disease  on  an  arriving  vessel  is  doubly  important,  as  it  is  in  the  nature 
of  a  medico-legal  decision.  Failure  to  recognize  one  of  the  quarantinable 
diseases  jeopardizes  the  public  health  of  the  country,  but,  on  the  other 
hand,  an  error  in  diagnosis,  even  though  in  the  interest  of  public  health, 
may  result  in  a  needless  loss  of  time  and  money.  The  quarantine  officer, 
therefore,  should  be  an  experienced  bacteriologist  or  should  have  such  an 
expert  as  an  assistant,  since  the  accurate  diagnosis  of  several  of  the  quar- 
antinable diseases  is  essentially  a  laboratory  procedure,  and  even  in 
those  quarantinable  diseases  whose  diagnosis  yet  rests  on  clinical  evi- 
dence, laboratory  procedure  is  important  in  establishing  differential  diag- 
nosis. The  quarantine  officer  must  also  be  familiar  with  the  modes  of 
spread  of  the  quarantinable  diseases,  and  must  know  the  value  and  lim- 
itations of  the  germicidal  agents  and  insecticides  he  uses.  Finally,  he 
must  be  familiar  with  matters  nautical  and  have  an  extensive  knowledge 
of  geography.  It  is  the  duty  of  the  quarantine  officer  to  keep  posted 
as  to  the  sanitary  conditions  of  all  countries,  more  especially  towns  and 
places  having  commerce  with  his  port. 

Disinfection  of  Ships. — The  principles  in  the  disinfection  of  a  vessel 
do  not  differ  materially  from  those  of  house  and  room  disinfection.  It 
should  not,  however,  be  attempted  by  one  not  familiar  with  the  intrica- 
cies of  marine  architecture  and  matters  nautical,  for  many  special  condi- 
tions are  met  with  on  board  ship  that  are  very  different  from  those  found 
on  shore.  WTiile  the  principles  of  disinfecting  as  applied  to  a  vessel 
present  nothing  unusual,  the  application  of  these  principles  calls  for 
much  ingenuity  and  the  keenest  vigilance  on  the  part  of  the  disinfector. 

It  is  important  to  enlist  the  sympathies  of  those  on  board  with  the 
necessity  of  disinfection,  for  the  successful  accomplishment  of  the  puri- 
fication of  the  vessel  may  be  materially  helped  by  the  cheerful  cooperation 
of  the  passengers  and  crew;  otherwise  the  difficulties  of  the  problem  are 
greatly  magnified. 

Formerly  a  distinction  was  made  between  the  methods  of  disinfect- 
ing a  wooden  and  an  iron  vessel.    This  arose  from  the  fact  that  almost 


512         PUBLIC  HEALTH  MEASURES  AND  METHODS 

all  wooden  vessels  have  some  rotten  and  spongy  wood,  especially  about 
the  forefoot  and  bilge.  There  are  also  many  more  cracks  and  open  joints 
about  a  wooden  ship  than  a  metal  one  which  afford  lodgment  for  organic 
matter.  In  addition  to  this,  a  wooden  hull  is  always  damper  than  an 
iron  hull,  for  almost  all  wooden  vessels  leak  more  or  less.  It  was  for- 
merly believed  that  the  microorganisms  of  disease  were  apt  to  become 
deeply  lodged  in  the  moist  dirt  and  organic  matter  of  these  crevices. 

A  vessel  is  rarely  so  badly  infected  that  it  needs  a  disinfection 
throughout.  Just  what  portion  of  the  vessel  and  its  contents  requires 
treatment  is  often  a  very  difficult  problem  to  solve.  There  is  no  more 
reason  to  fumigate  the  hold  of  a  vessel  because  smallpox  appeared  in  the 
cabin  or  steerage  than  there  would  be  to  disinfect  the  basement  and  sub- 
basement  of  a  tenement  house  because  a  case  appeared  in  one  of  the 
upper  stories  of  the  building.  When  a  communicable  disease  occurs  on 
board  a  vessel  the  infection  may  be  confined  to  one  or  two  compartments 
or  to  a  limited  area  quite  as  successfully  as  this  may  be  done  in  buildings 
on  shore.  "In  case  of  doubt,  disinfect,"  is  not  a  bad  rule  for  the  quaran- 
tine officer  to  follow  in  his  practical  dealings  with  ships.  Although  the 
measures  which  must  be  taken  are  greatly  in  excess  of  the  absolute  re- 
quirements, yet  discrimination  is  necessary,  for  the  disinfection  of  ships 
for  the  quarantinable  diseases  has  been  greatly  overdone.  Vessels  often 
need  fumigation,  seldom  disinfection. 

No  routine  method  of  disinfection  can  be  prescribed  for  all  infected 
ships.  Discrimination  must  be  exercised;  disinfectants  or  fumigants 
must  be  selected  that  will  destroy  the  virus  and  also  the  infecting  agency 
involved. 

It  is,  therefore,  the  duty  of  the  quarantine  officer  to  require  a  very 
thorough  mechanical  cleansing  of  all  parts  of  the  ship  which,  in  his 
judgment,  require  it.  This  matter  is  dwelt  upon  because  filth  and  ver- 
min are  conditions  too  frequently  met  with  on  the  sea  and  one  of  great 
importance  to  communities  and  nations. 

While  the  general  methods  of  treating  vessels  are  the  same  for  most 
of  the  bacterial  infections,  special  methods  are  called  for  with  each  dis- 
ease. For  example,  in  cholera  particular  attention  must  be  paid  to  the 
water  and  food  supply;  for  plague  the  destruction  of  rats  and  fleas  is 
of  prime  importance ;  for  yellow  fever  attention  must  be  directed  against 
the  mosquito;  for  smallpox  yaccination  and  the  usual  disinfection  of  the 
living  apartments,  clothing,  bedding,  and  the  like  are  required,  while  for 
typhus  fever  the  warfare  must  be  waged  against  lice. 

Before  the  disinfection  of  a  vessel  is  commenced  it  should  be  brought 
alongside  the  pier  or  barge  containing  the  necessary  apparatus.  All 
the  passengers  are  then  to  be  taken  off  and  all  the  crew,  only  excepting 
the  few  who  are  necessary  for  the  safety  of  the  vessel  and  those  who 
are  to  help  in  the  purification.     The  quartermaster,  the  boatswain,  and 


QUARANTINE  513 

the  carpenter  are  very  useful  liands  to  aid  in  the  process  on  accoujit  of 
their  practical  knowledge  of  the  individual  peculiarities  of  the  construc- 
tion of  the  vessel  and  their  faithfulness  in  carrying  out  directions  with 
intelligence. 

The  disinfection  of  ships  applies  only  to  the  living  quarters  of  ves- 
sels infected  with  typhus,  pneumonic  plague,  smallpox,  leprosy  or  chol- 
era, and  then  only  to  the  particular  part  of  the  ship  in  which  the  sick 
have  been.  Steam  sterilization  of  the  ship  furnishings,  personal  effects, 
clothing,  etc.,  is  not  necessary  in  handling  bubonic  plague  or  yellow  fever 
infected  vessels. 

When  the  personnel  have  left  the  vessel  all  their  effects  are  removed 
and  disinfected,  if  necessary,  in  accordance  with  the  methods  outlined 
for  objects  of  that  class.  Disinfected  baggage,  bedding,  and  other  ob- 
jects, no  matter  what  their  character,  should  not  be  returned  on  board 
until  the  treatment  of  the  vessel  itself  is  finished.  This  injunction 
applies,  of  course,  equally  well  to  persons.  In  fact,  no  one  should  be 
allowed  on  the  vessel  except  those  actually  engaged  in  the  work,  who, 
as  far  as  practicable,  should  be  immune  and  should  wear  suitable  gar- 
ments. All  the  bedding,  bed  clothing,  hangings,  floor  runners,  and 
other  fabrics  that  have  been  exposed,  to  infection  must  now  be  removed 
to  the  steam  chamber.  Especial  care  must  be  taken  to  obtain  all  the 
used  and  soiled  linen,  which  is  usually  kept  in  special  compartments 
called  the  "dirty  linen  lockers/'  which  are  usually  under  the  care  of  one 
of  the  stewards.  For  some  reason  there  is  a  dislike  to  disclose  the  pres- 
ence of  this  soiled  wash  to  the  quarantine  officer. 

After  all  the  objects  needing  disinfection  by  a  special  process  have 
been  removed,  attention  is  then  directed  to  the  vessel  itself.  The  vari- 
ous compartments  of  the  vessel  may  be  disinfected  by  any  one  of  the 
methods  described  under  Eoom  Disinfection,  formaldehyd  being  the 
choice  of  the  gases  and  bichlorid  of  mercury  (1-1,000)  being  the  most 
suitable  solution  for  the  treatment  of  walls,  floors,  etc. 

As  to  bichlorid  disinfection,  it  may  be  stated  that  this  procedure  was 
formerly  much  employed  at  quarantine  stations  before  the  means  of 
transmission  of  plague,  typhus  and  yellow  fever  were  known.  One  of 
the  most  important  features  of  a  quarantine  station  was  the  tank  of 
bichlorid  of  mercury  solution  holding  several  thousand  gallons  of  the 
mixture.  It  is  a  practice  that  has  now  well-nigh  been  abandoned,  but 
still  has  a  limited  usefulness  in  washing  down  the  floors  and  walls  of 
compartments  that  have  been  contaminated  by  discharges  from  a  cholera 
patient. 

Fumigation  of  Ships. — In  the  purification  of  a  ship,  the  greatest  im- 
portance attaches  to  fumigation  with  sulphur  or  hydrocyanic  acid  gas. 
For  many  years  sulphur  dioxid  was  the  agency  chiefly  relied  on  in  the 
fumigation  of  vessels.     Cyanid  gas  was  regarded  as  too  dangerous  to  hu- 


514    PUBLIC  HEALTH  MEASUEES  AND  METHODS 

man  life,  and  in  the  strength  assumed  to  be  necessary,  i.  e.,  10  ounces 
per  thousand  cubic  feet  of  space,  was  also  too  expensive  for  routine 
employment.  During  the  last  four  or  five  years,  however,  there  has 
been  much  work  done  with  this  gas  by  officers  of  the  Public  Health  Serv- 
ice, and  while  it  can  in  no  sense  be  considered  a  "fool-proof*  gas  in  the 
hands  of  the  inexperienced,  the  procedure  has  been  so  developed  and 
improved  as  to  make  it  reasonably  safe  when  supervised  by  trained  op- 
eratives. 

Cyanid  gas  assuredly  has  many  points  of  superiority  over  sulphur 
dioxid.  Sulphur  dioxid  is  not  very  dilfusive,  and  when  used  on  cargo- 
laden  vessels  has  but  little  penetrating  power,  and  thus  the  air  pockets 
in  articles  of  cargo  or  between  packages  of  merchandise  will  often  afford 
the  rats  a  sufficient  protection  against  the  effects  of  the  sulphur  fumes. 
Sulphur  dioxid  is  highly  destructive  to  finer  textiles,  especially  if  damp; 
it  tarnishes  brass  and  gilt  fixtures,  damages  delicately  adjusted  instru- 
ments, and  causes  discoloration  of  painted  surfaces  which  contain  lead 
pigments.  The  generation  of  sulphur  fumes,  if  by  furnace,  requires  ex- 
pensive apparatus  and,  if  by  the  "pot  and  pan"  method,  much  labor  and 
cumbersome  apparatus.  The  pots  and  pans  necessitate  considerable  time 
in  placing  and  removing  them  and  the  exposure  required  is  from  6  to  13 
hours.  Added  to  these  defects,  there  is  always  the  risk  of  fire  from  the 
burning  sulphur.  In  contrasting  sulphur  fumigation  and  cyanid  fumi- 
gation, the  one  feature  in  favor  of  sulphur  is  that  it  is  not  dangerous  to 
human  life. 

On  the  other  hand^  cyanid  gas  is  highly  toxic  to  animal  and  insect 
life  in  the  strength  of  5  ounces  of  cyanid  per  thousand  cubic  feet  of 
space,  and  this  with  rather  short  exposure.  It  is  not  injurious  to  the 
finest  textiles  nor  to  such  articles  as  tea,  coffee,  tobacco,  sugar,  etc.  It 
does  not  tarnish  brass  or  gilt,  nor  discolor  painted  surfaces.  It  is  easily 
and  quickly  generated  and  requires  but  simple  equipment. 

Cyanid  Fumigation  of  Ships. — The  method  of  preparation  of  the  gas 
adopted  by  the  Public  Health  Service  is  as  follows :  Paraphernalia  re- 
quired includes  a  tight  wooden  barrel  (the  well-made  oak  barrel  used  for 
kerosene  serves  excellently)  for  use  in  holds;  earthen- ware  crocks  or  jars 
for  smaller  compartments,  and  earthen-ware  jugs  as  acid  containers. 
The  mixture  of  sulphuric  acid  and  water  is  first  prepared  in  the  propor- 
tion of  2  fluid  ounces  of  water  to  one  and  one-half  ounces  of  commercial 
(66B)  sulphuric  acid.  Finally,  when  most  of  the  hatch  coverings  have 
been  placed  in  position,  sodium  cyanid  is  lowered  in  a  cheesecloth  sack 
in  the  proportion  of  one  ounce  to  each  three  and  one-half  ounces  of  the 
above  mixture,  dropped  into  the  solution,  bag  and  all,  and  the  remaining 
hatch  covers  adjusted  and  battened  down  by  a  heavy  tarpaulin. 

The  strength  of  the  gas  and  the  duration  of  exposure  vary  with 


QUARANTINE  515 

the  objects  sought.  The  Public  Health  Service  standards  in  this  respect 
are  as  follows: 

For  destruction  of  mosquitoes:  One-half  ounce  of  sodium  cyanid 
per  thousand  cubic  feet  of  space,  exposure  one-half  hour. 

For  destruction  of  fleas:  Two  and  one-half  ounces  sodium  cyanid 
per  thousand  cubic  foct  of  space,  exposure  one-half  hour.  N.  B.  This 
is  of  academic  interest  only,  as  in  practice  ships  are  not  fumigated  for  flea 
destruction  only,  but  always  with  the  idea  of  rat  destruction  as  well  as 
flea  destruction. 

For  destruction  of  rodents  (rats  and  mice)  :  Five  ounces  of  sodium 
cyanid  per  thousand  cubic  feet  of  space,  exposure  for  one  and  one-half 
hours. 

For  destruction  of  lice:  Ten  ounces  of  sodium  cyanid  per  thousand 
cubic  feet  of  space,  exposure  two  hours. 

For  destruction  of  bedbugs :  Five  ounces  of  sodium  cyanid  per  thou- 
sand cubic  feet  of  space,  exposure  for  one  hour. 

The  above  standards  apply  to  empty  holds  and  superstructures,  ex- 
cept storerooms  that  have  a  large  quantity  of  stores.  In  cargo-laden 
holds  or  in  well-packed  storerooms,  the  length  of  exposure  is  doubled. 

If  the  potassium  salt  be  used,  a  greater  quantity  is  required.  Three 
and  three-fourths  ounces  of  sodium  cyanid  is  the  equivalent  of  five  ounces 
of  potassium  C5^anid,  and  the  latter  when  used  is  in  the  proportion  of 
one  ounce  of  potassium  cyanid  to  one  fluid  ounce  of  sulphuric  acid  and 
two  and  one-half  fluid  ounces  of  water. 

As  a  preliminary  to  cyanid  fumigation  the  quarantine  officer  should 
make  sure  that  no  persons  other  than  the  fumigating  force  are  on  the 
vessel,  and  a  certificate  to  this  effect  should  be  exacted  of  the  master. 
This  should  further  be  confirmed  by  a  search  of  the  vessel  by  the  quar- 
antine officer  himself  or  a  trusted  assistant.  The  compartments  above 
the  deck  should  have  danger  labels  pasted  on  doorways  after  the  fumi- 
gation has  commenced. 

The  experience  of  the  Public  Health  Service  in  fumigating  several 
thousand  vessels  by  cyanid  as  well  as  mammoth  storehouses,  makes  it 
appear  that  there  is  no  especial  danger  to  the  operator  in  the  prepara- 
tion of  the  gas. 

The  generation  of  gas  is  sufficiently  delayed  as  to  afford  ample  time 
for  the  fumigators  to  leave  the  compartment  after  dropping  the  cyanid 
into  the  acid  solution;  this,  provided  the  compartments  are  above  deck. 
The  serious  danger  to  human  life  arises  incident  to  entering  the  com- 
partment after  the  fumigation  has  been  completed  and  the  vessel  opened 
up.  To  obviate  this  danger,  powerful  ventilating  fans,  driven  by  portable 
gasoline  engines,  are  utilized  at  quarantine  stations.  They  are  lowered 
into  the  holds  or  placed  within  the  doorways  of  above-deck  compart- 
ments upon  the  completion  of  the  fumigation. 


516  PUBLIC  HEALTH  MEASURES  AND  METHODS 

The  Public  Health  Service  rules  provide  that  no  one  may  enter  a 
compartment  subsequent  to  cyanid  fumigation  until  it  has  been  pro- 
nounced safe  by  the  quarantine  officer.  To  determine  this  point,  captive 
rats,  cats,  or  guinea  pigs  are  used  as  "indicators." 

Sulphur  and  Cyanid  Contrasted. — At  one  of  the  large  quarantine 
stations  on  the  Gulf,  where  some  of  the  vessels  were  fumigated  by  sul- 
phur and  others  by  cyanid  gas,  a  very  thorough  study  was  made  as  to  the 
relative  effectiveness  of  cyanid  gas  and  sulphur  dioxid  when  used  on  ships 
for  rodent  destruction.  A  very  large  force  of  trained  trappers  was 
available  because  of  the  anti-plague  measures  being  carried  out  at  the 
port,  and,  as  the  vessels  generally  stayed  in  port  from  one  or  two  days 
to  a  week,  ample  opportunity  was  afforded  for  testing  the  effectiveness 
of  the  fumigation.  Subsequent  to  fumigation,  the  vessels  were  flooded 
with  traps.-  The  observations  extended  over  a  period  of  one  year  and 
results  recorded  on  several  hundred  ships.  The  number  of  traps  placed 
varied  from  20  to  140  per  ship,  according  to  the  size  of  the  vessel. 
Each  ship  after  fumigation  was  carefully  searched  for  dead  rats  and 
the  number  found  recorded  as  to  location.  The  number  of  days  ships 
were  trapped  varied  from  one  to  ten,  depending  on  the  length  of  time 
vessels  stayed  in  port. 

By  contrasting  the  number  of  rats  killed  by  fumigation  with  the 
number  subsequently  trapped,  a  fairly  reliable  estimate  was  afforded  as 
to  the  effectiveness  of  the  fumigation.  The  results  showed  that  cyanid 
fumigation  destroyed  95  per  cent,  of  all  the  rats  on  the  vessel  v/hether 
the  holds  were  empty  or  loaded,  and  without  regard  to  the  location 
from  which  the  rats  were  taken.  In  contrast  to  this  result,  sulphur  fumi- 
gation killed  only  77  per  cent,  of  the  rodent  population  on  vessels  under 
similar  conditions.  Studying  the  results  according  to  the  compartments 
fumigated,  it  was  noted  that  in  superstructures  (including  cahins,  store- 
rooms, poop  deck  and  crew's  quarters)  cyanid  fumes  destroyed  94  per 
cent,  of  the  rat  population,  whereas  sulphur  fumes,  under  similar  con- 
ditions, destroyed  only  55  per  cent,  of  the  rodent  population.  In  cargo- 
laden  holds,  sulphur  efficiency  was  64  per  cent,  in  contrast  to  80  per 
cent,  for  cyanid  fumes.  In  empty  holds,  the  results  of  the  two  practices 
were  more  or  less  parallel;  99  per  cent,  efficiency  for  cyanid,  and  96  per 
cent,  efficiency  for  sulphur  dioxid. 

In  this  series  of  observations  sulphur  dioxid  was  used  in  the 
strength  of  3  pounds  of  sulphur  per  1,000  cubic  feet  of  space,  ex- 
posure of  6  hours,  and  the  cyanid  was  used  in  the  proportion  of  5 
ounces  of  cyanid  per  1,000  cubic  feet  of  space  with  exposure  of  1^ 
hours  in  holds,  and  II/2  hour  for  superstructures.  Had  the  duration  of 
exposure  been  doubled,  the  effectiveness  of  cyanid  fumigation  would 
probably  have  been  perfect  and  the  results  of  the  sulphur  dioxid  fumi- 
gation would  have  been  much  better. 


QUARANTINE  517 

While  cyaiiid  fumigation  is  iiiuloiibtcdly  the  preferred  procedure 
where  trained  operators  are  available  aiid  the  conditions  I'avoralile,  sul- 
phur dio.xid  lias  yet  a  wide  field  of  usefulness,  and  on  account  of  its 
safety  in  unskilled  hands  and  the  lack  of  operators  experienced  in  cyanid 
fumigation,  will  doulillcss  contiiuu'  to  he  the  most  commonly  used  agency 
for  rodent  and  insect  destruction  on  vessels. 

Sulphur  Fumigation  of  Ships. — The  Public  Health  Service  standard 
for  sul])hur  dioxid  as  to  strength  and  exposure  is  as  follows: 

For  mosquito  destruction :  2  pounds  of  sulphur  per  thousand  cubic 
feet  of  spai-e,  exposure  for  one  hour. 

For  destruction  of  lice:  4  pounds  of  sulphur  per  thousand  cubic 
feet  of  space,  exposure  for  six  hours. 

For  destruction  of  rats  and  fleas :  3  pounds  of  sulphur  per  thousand 
cubic  feet  of  space,  exposure  for  six  hours. 

The  above  standard  is  for  superstructures,  partially  filled  storerooms, 
and  empty  holds.  For  cargo-laden  holds  and  well-filled  storerooms  or 
in  compartments  that  are  packed  with  materials,  the  period  of  exposure 
should  be  doubled. 

There  are  two  methods  in  common  use  for  generating  sulphur  dioxid 
for  ship  fumigation.  The  method  more  generally  utilized  is  that  known 
as  the  "pot  and  pan"  method,  but  at  a  number  of  quarantine  stations  sul- 
phur dioxid  is  generated  by  burning  sulphur  in  a  specially  constructed 
furnace,  the  fumes  being  led  into  the  holds  through  canvas  funnels  or 
hose.  In  the  "pot  and  pan"  method,  ordinary  Dutch  ovens  are  "used 
with  a  capacity  of  10  to  20  pounds  of  sulphur.  They  are  placed  in 
pans  of  water  in  elevated  positions  on  the  'tween  decks  or  piles  of  ballast 
and  distributed  about  the  ship.  To  aid  combustion,  one-half  gill  of  grain 
alcohol  is  added  to  each  sulphur  container.  When  all  the  pots  are  lighted, 
the  hatches  are  battened  down,  the  doors  of  the  superstructures  closed, 
and  cracks  closed  by  the  use  of  paste  paper.  A  pan  of  Avater  is  placed 
under  each  sulphur  pot;  this  acts  in  part  as  a  protection  against  fire, 
but  it  also  serves  the  purpose  of  evolving  moisture  which  is  essential  for 
the  effectiveness  of  sulphur  dioxid  as  a  germicide. 

•  For  the  purpose  of  computing  the  amount  of  sulphur  or  other  gas 
to  be  used,  a  registered  ton  contains  100  cubic  feet.  A  vessel  of  5,000 
net  tonnage  would  therefore  contain  500,000  cubic  feet  of  air  space  in 
the  cargo  holds  alone.  Gross  tonnage  of  a  vessel  indicates  the  actual 
cubic  capacity;  net  tonnage,  giving  the  cargo  carrying  capacity:  The 
difference  between  the  net  tonnage  and  the  gross  tonnage  indicates  the 
space  taken  up  by  the  engines  and  fireroom  and  the  structures  above 
deck.  In  sailing  vessels  and  freighters,  therefore,  there  is  not  such  a 
great  difference  between  the  gross  and  the  net  tonnage  as  there  is  in 
large  passenger  vessels.  In  estimating  freight-carrying  capacity,  40 
cubic  feet  of  merchandise  is  considered  a  ton,  but  this  unit  should  not 


518    PUBLIC  HEALTH  MEASURES  AND  METHODS 

be  confused  with   the  registered  tonnage,  which   is  the   basis  for   the 
measurement  of  the  vessel. 

Special  Precautions  in  Fumigating  Ships. — The  various  details  in 
connection  with  fumigation  of  vessels  are  quite  as  important  as  the  nature 
of  the  fumigant  used,  and  the  observance  of  these  details  to  a  large 
extent  determines  the  effectiveness  of  the  fumigation.  All  possible  care 
should  be  observed  by  the  quarantine  officer  to  see  that  dead  space  in 
the  vessel  is  opened  up  and  all  practical  measures  should  be  taken  to 
aid  in  the  diffusion  of  the  fumigating  gas;  this  is  most  essential  when 
sulphur  dioxid  is  used.  All  dunnage  and  loose  material  in  the  holds 
of  a  vessel  that  is  not  cargo-laden  should  be  arranged  in  compact  order 
and  placed  on  elevated  platforms  to  avoid  rat  harborage.  If  sulphur 
dioxid  is  generated  in  a  furnace  and  led  into  the  vessel  it  should 
be  introduced  at  the  lowest  point  and  the  hatches  left  open  for  a  short 
while  so  as  to  permit  the  escape  of  air  and  hasten  diffusion  of  the 
sulphur  fumes.  Pipe  casing  should  be  opened  up  and  from  one  end 
of  the  vessel  to  the  other  there  should  be  a  certain  number  of  limber 
boards  removed  so  as  to  permit  penetration  of  the  gas  into  the  bilges. 
Any  planked-over  space  between  the  outer  and  the  inner  sheathing  of  a 
vessel  should  also  be  freely  opened.  In  fact,  wherever  there  is  dead  space 
it  should  be  opened  up  so  that  there  will  be  free  circulation  of  the  gas. 
Careful  attention  should  be  given  to  lifeboats,  which  are  often  infested 
by  rats,  which  resort  to  those  places  for  water.  Preferably,  lifeboats 
should  be  cleaned  out  and  flooded  by  water  prior  to  fumigation.  Very 
close  attention  should  be  given  to  the  poop  deck,  which  is  a  space  fre- 
quently containing  a  heterogeneous  collection  of  litter  and  is  generally 
badly  rat-infested.  As  a  rule,  the  engine  room  and  fireroom  do  not 
harbor  rats,  but  in  the  treatment  of  a  plague-infected  vessel  they  should 
be  fumigated. 

Cargo. — As  a  rule,  the  cargo  of  a  vessel  infected  with  pestilential 
disease  needs  no  disinfection.  Individual  articles  of  the  cargo,  such  as 
rags,  household  goods,  second-hand  articles,  hides,  wool,  or  food  products, 
from  infected  localities  may  need  treatment.  New  articles  of  merchan- 
dise or  new  manufactured  goods  seldom  carry  infection. 

Foreign  Inspection  Service. — To  aid  the  quarantine  officer  every 
American  consul  is  required  to  report  regularly  certain  facts  concern- 
ing the  presence  and  progress  of  epidemic  diseases.  Medical  officers  of 
the  government  are  also  stationed  in  various  countries  in  order  to  su- 
pervise the  sanitary  condition  of  vessels,  their  cargo,  and  passengers 
leaving  for  the  United  States.  This  may  be  called  preventive  quaran- 
tine, for  it  is  a  distinct  help  in  keeping  out  infection  and  facilitates 
trade  and  travel.  Thus,  in  Italy,  during  the  cholera  times,  an  officer  of 
the  Public  Health  Service  stationed  at  Naples  successfully  kept  that 
disease  off  vessels  sailing  from  Naples  to  the  United  States,  whereas 


QUARANTINE  519 

vessels  sailing  from  Naples  to  other  ports  aiifl  without  sanitary  super- 
vision carried  cholera  in  several  instances. 

National  versus  State  Quarantine. — All  the  maritime  quarantine 
stations  in  this  t'ountry  are  now  controlled  hy  the  National  Government, 
excepting  only  the  port  of  New  York,  where  the  quarantine  function  still 
remains  under  the  jurisdiction  of  the  Sta.te."*  The  Federal  quarantine 
service  is  administered  hy  the  V.  S.  Puhlic  Health  Service,  a  Bureau 
of  the  Treasury  Dejiartmcnt. 

It  is  evident  that  maritime  quarantine  should  be  administered  uni- 
formly so  as  not  to  prejudice  or  favor  the  commerce  of  a  port.  One  of 
the  objections  to  local  control  of  quarantine  is  that  there  is  frequent 
rotation  in  the  position,  of  quarantine  officers  due  to  local  political 
changes.  In  addition  to  its  other  advantages,  national  control  of  quar- 
antine insures  the  availability  of  a  large  corps  of  trained  quarantine 
officers,  whose  experience  in  quarantinable  diseases  and  in  quarantine 
technic  has  been  increased  by  duty  in  foreign  countries  and  insular  pos- 
sessions where  such  diseases  mainly  prevail.  Federal  control  of  quaran- 
tine further  permits  of  greater  cooperation  with  other  branches  of  the 
Federal  Government  such  as  the  Immigration  and  the  Customs  Service. 
Furthermore,  the  Government  is  better  able  to  observe  the  obligations 
of  international  sanitary  treaties,  and  to  demand  reciprocal  action  on 
the  part  of  foreign  signatories  of  such  treaties.  Finally,  as  the  object 
of  quarantine  is  not  only  the  protection  of  the  local  port,  but  the  entire 
countrj^  and  since  the  benefits  derived  therefrom  are  not  merely  local 
in  effect,  the  expense  for  the  maintenance  of  quarantine  stations  should 
be  borne  by  the  country  as  a  whole. 

INTERSTATE  QUARANTINE 

The  regulations  prepared  under  this  act  are  more  comprehensive  with 
respect  to  quarantinable  diseases  than  are  the  National  Quarantine  Regu- 
lations, since  the  former  include  not  only  the  diseases  enumerated  in 
the  maritime  quarantine  regulations,  but  also  a  number  of  communicable 
diseases,  such  as  scarlet  fever,  typhoid,  measles,  whooping-cough,  polio- 
mj'elitis,  Eocky  Mountain  spotted  fever,  and  epidemic  cerebrospinal 
meningitis.^®  There  is  a  distinct  difference,  however,  between  maritime 
quarantine  and  interstate  quarantine.  The  provisions  of  the  United 
States  statutes  with  respect  to  the  former  give  to  the  quarantine  officer 
no  latitude.    Every  ship  entering  from  a  foreign  port  must  be  inspected 

^^^  Transferred  to  the   Federal  Government,  March.    1921. 

"This  list  has  been  extended  by  the  Regulation  of  July  30.  1918,  to  include: 
Plague,  cholera,  typhoid  fever,  pulmonary  tuberculosis,  yellow  fever,  smallpox, 
leprosy,  typhus  fever,  scarlet  fever,  diphtheria,  measles,  whooping  cough,  polio- 
myelitis. Rocky  Mountain  spotted  or  tick  fever,  anthrax  and  epidemic  cerebro- 
spinal meningitis. 


520    PUBLIC  HEALTH  MEASUEES  AND  METHODS 

and  the  quarantine  officer  must  certify  that  they  are  free  from  quaran- 
tinable  disease,  whereas,  with  respect  to  interstate  carriers  or  travel, 
quarantine  laws  and  regulations  are  enforceable  only  to  the  extent  that 
the  Federal  Government  may  provide  proper  agencies  for  such  enforce- 
ment. A  vessel  from  a  foreign  port  may  not  enter  a  port  of  the  United 
States  except  it  he  provided  with  a  certificate  of  discharge  from  quar- 
antine (free  practique),  but  a  common  carrier  is  not  barred  from  inter- 
state travel  because  of  the  lack  of  any  such  certificates.  The  interstate 
quarantine  regulations  impose  numerous  obligations  on  common  carriers, 
and  potential  restrictions  on  interstate  travel,  but  they  have  been  actively 
enforced  only  under  exceptional  conditions.  For  obvious  reasons,  inter- 
state travel  is  not  subjected  to  the  same  rigid  inspection  as  the  personnel 
of  vessels  at  seaboard  quarantine  stations. 

It  is  evident,  however,  that  interstate  sanitary  regulation  is  one  of 
the  important  phases  in  which  Government  activity  can  accomplish 
especial  good,  for  while  the  Government  has  limited  authority  within  a 
state,  it  has  practically  unlimited  authority  so  far  as  interstate  relations 
are  concerned.  In  the  control  of  diseases  by  local  authorities  coopera- 
tion of  the  Government  is  essential  since  it  is  evident  that  if  one  state 
should  rid  itself  of  typhoid  fever,  measles  or  tuberculosis,  it  would  speed- 
ily become  reinfected  from  the  neighboring  states  unless  such  reintroduc- 
tion  were  prevented  through  the  application  of  interstate  quarantine  re- 
strictions. Interstate  quarantine  regulations,  however,  sholild  be  en- 
forced with  the  same  appreciation  of  relative  values  as  applies  to  mari- 
time quarantine.  It  would  be  indefensible  to  impose  restrictions  on 
commerce  and  on  travel  for  the  purpose  of  excluding  measles  or  typhoid 
from  a  community  which  itself  was  doing  nothing  to  diminish  the 
prevalence  of  such  diseases.  On  the  other  hand,  if  sanitary  control  of 
local  conditions  by  state,  county  or  city  officials  ever  progresses  to  the 
extent  that  a  community  has  rid  itself  of  communicable  diseases,  it 
would  have  the  assistance  of  the  Federal  Government  in  remaining 
clean. 

By  application  of  the  provisions  of  interstate  quarantine  regulations, 
the  National  Government  has  wide  powers  in  influencing  local  sanitary 
reforms.  It  can  prevent  the  pollution  of  interstate  streams,  and  by 
means  of  a  proper  standard  for  purity  of  water  for  interstate  carriers, 
it  can  thus  indirectly  raise  the  standard  of  purity  of  local  supplies.  Fur- 
nished with  adequate  funds  and  facilities.  Federal  health  authorities  can 
exert  a  tremendous  influence,  through  the  enforcement  of  interstate  sani- 
tary regulations  toward  assisting  local  and  state  authorities  in  achieving 
sanitary  reforms. 


QUARANTINE  fi21 

COLLATERAL  READING 

{General  Subject  of  Preventive  Medicine) 

Sedgwick,  W.  T.:    "Prim-iples  of  Sanitary  Science  and  the  Public  Health," 

1902. 
Chapin,  C.  V. :     "Soureos  and  Modes  of  Infection,"  1912. 

:     "Municipal  Sanitation  in  the  United  States,"  1901. 

RUBNER,  M.,  Gruber,  M.  v.,  and  Ficker,  M.  :  Handbuch  der  Hygiene,  1911, 

Flugge,  Carl:     Gr^mdriss  der  Hygiene,  1908. 

Weyl,  Theodore  :    Handbuch  der  Hygiene,  Jena,  1895. 

Hemenway,  H.  B.  :     "Legal  Principles  of  Public  Health  Administration," 

1914. 
Newman,  Sir  George  :    An  Outline  of  the  Practice  of  Preventive  Medicine. 

His  Majesty's  Stationery  Office,  1919. 
The  Control  of  Communicable  Diseases.    Public  Health  Reports,  October 

12,  1919,  reprint  No.  436.    A  condensed  summary  of  the  essential  facts. 
MacNutt,  J.  S. :     "A  Manual  for  Health  Officers."     John  Wiley  &  Sons, 

1915. 
Overton,  F.,  and  Denno,  W.  J. :     "The  Health  Officer."    W.  B.  Saunders 

Co.,  1919. 
Paek,  Wm.  H.  :  "Public  Health  and  Hygiene."  Lea  and  Tebiger,  1920. 


■'J 


SECTION  IV 
IMMUNITY,  HEREDITY,  AND  EUGENICS 

CHAPTER  I 
IMMUNITY 

Infection  and  Immunity;  Definition  of  Terms. — Immunity  or  re- 
sistance to  disease  is  the  very  foundation  of  preventive  medicine.  It  is 
the  overshadowing  factor  in  hygiene.  In  this  sense  we  use  the  term 
"hygiene''  to  include  the  care  of  the  person,  in  contradistinction  to  "san- 
itation," which  deals  with  the  environment.  There  is  no  sharp  line  of 
demarcation — we  speak  of  hygiene  of  the  teeth,  of  sleep,  of  bathing,  of 
exercise,  of  food  and  drink,  and  of  those  conditions  which  are  more  or 
less  intimately  associated  with  the  body.  We  speak  of  the  sanitation  of 
the  home,  of  schools,  of  cities,  of  farms.  Sanitary  science  considers  the 
air,  soil,  climate,  and  our  surroundings  as  they  affect  health.  Sanitation, 
then,  is  largely  impersonal;  hygiene  is  personal,  and,  as  far  as  the  pre- 
vention of  disease  is  concerned,  one  of  the  most  important  factors  in 
hygiene  is  immunity. 

The  word  "immunity"  is  a  very  old  term — we  still  speak  of  immu- 
nity to  crime,^  but  it  is  only  of  late  years  that  we  are  beginning  to  un- 
derstand the  mechanism  by  which  the  body  protects  itself  against  in- 
fection. The  advances  have  been  so  rapid  that  these  studies  may  now  be 
grouped  into  a  separate  science  known  as  Immunology. 

Immunity  is  a  function  of  all  living  beings  (animals  and  plants), 
and  in  its  widest  form  is  one  of  the  fundamental  properties  of  life. 
Thus,  as  long  as  we  are  alive  the  colon  bacillus  in  our  intestinal  tract 
and  the  spores  of  the  hay  bacillus  on  our  skin  do  us  no  harm,  but  the 
moment  we  die,  and  ofttimes  shortly  before  death,^  these  and  other  bac- 
teria invade  our  tissues  and  disintegrate  them. 

Immunity  may  be  defined  as  the  power  which  certain  living  organ- 
isms possess  of  resisting  infections.  Susceptibility  is  the  contrary  condi- 
tion to  immunity.  Hypersusceptibility  is  a  special  state  of  an  exag- 
gerated power  of  reaction  and  is  synonymous  with  anaphylaxis.    A  llergie 

^  We  may  speak  of  immunity  "from"  a  disease,  "to"  a  disease,  and  "against" 
a  disease. 

'  Terminal  infections. 

523 


524  IMMUNITY 

is  an  altered  process  of  reaction,  often  used  as  a  synonym  for  anaphylaxis. 
The  word  resistance  has  practically  the  same  signification  as  immunity. 
The  term  tolerance  is  commonly  used  to  describe  a  limited  form  of 
immunity  usually  acquired  by  the  repeated  use  of  alkaloids,  alcohol,  and 
other  poisons  of  comparatively  simple  chemical  structure.  While  a  high 
degree  of  tolerance  may  be  acquired  to  such  substances,  a  true  immunity 
in  the  sense  in  which  the  term  is  now  used  is  never  produced.  In  the 
case  of  tolerance,  antibodies  are  not  found  in  the  blood.  For  the  most 
part  true  immunity  is  obtained  against  colloidal  substances,  while  tol- 
erance is  largely  limited  to  the  crystalloids ;  this  distinction,  however, ' 
is  not  absolute. 

There  are  all  gradations  and  various  kinds  of  immunity.  It  varies  in 
degree  from  the  weakest  appreciable  resistance  to  an  absolute  protection. 
It  also  varies  greatly  in  duration — from  the  briefest  period  to  a  life  span. 
Immunity,  therefore,  is  a  relative  term.  It  may  be  natural  or  acquired, 
active  or  passive,  local  or  general,  pure  or  mixed,  specific  or  non-specific, 
family  or  racial,  brief  or  lasting,  strong  or  weah,  etc. 

Antigens  are  all  substances  causing  changes  in  the  blood,  which 
thereby  acquires  specific  affinity  for  the  antigen.  All  known  proteins  act 
as  antigens  when  introduced  into  the  body  parenterally.  Antigens,  then, 
are  substances  capable  of  inducing  the  production  of  antibodies.' 

Antibodies  are  specific  properties  of  the  blood  and  other  body  fluids 
induced  by  antigens.  They  are  not  necessarily  "bodies,"  but  rather  col- 
loidal or  physical  states  of  the  blood  or  other  body  fluids.  Antibodies 
come  down  with  the  globulin  fraction.  Examples  of  antibodies  are  anti- 
toxin, agglutinin,  precipitin,  opsonin,  lysin,  etc.  Antibodies  are  also 
called  immune  bodies. 

A  parasite  is  a  plant  or  animal  living  in  or  with  some  other  living 
organism  (called  its  host),  at  whose  expense  it  obtains  food,  shelter,  or 
some  other  advantage.  Parasitism  is  probably  a  form'  of  specific  adapta- 
tion. Ectoparasites  or  external  parasites  live  upon  the  host,  as  fleas  and 
lice.  Endoparasites  or  internal  parasites  live  in  the  body  of  the  host,  as 
intestinal  worms,  anthrax  bacilli,  malarial  plasmodia,  etc. 

A  saprophyte  is  a  microscopic  being  that  lives  upon  dead  organic 
matter.  Saprophytes  and  parasites  belong  to  either  the  animal  or  plant 
kingdom;  thus,  the  malarial  plasmodium  is  an  animal  parasite,  the 
meningococcus  a  plant  parasite. 

Obligate  saprophytes  are  those  which  under  no  circumstances  can 
be  made  to  develop  within  the  living  tissues  of  a  given  animal.  Diph- 
theria and  tetanus  bacilli  come  close  to  being  strict  or  obligate  sapro- 
phytes, for  they  usually  develop  and  produce  toxins  on  a  localized  area 
of  dead  tissue.  Many  parasites  are  facultative,  in  that  while  they  thrive 
best  in  the  living  host,  they  may  also  be  made  to  grow  and  develop 
upon  dead  organic  matter. 


DEFINITIOJ^S  525 

Symbiosis  is  a  form  of  parasitism  in  which  two  dissimilar  organisms 
live  together  in  more  or  less  intimate  association,  to  the  advantage  of 
one  or  both,  and  not  harmful  to  either;  while  antibiosis  is  harmful  to 
host  or  parasite,  or  both. 

Animal  parasites  have  feeble  antigenic  properties;  that  is,  they  have 
feeble  or  no  power  of  stimulating  the  production  of  immune  bodies. 
Animal  parasites  therefore  lack  the  power  of  producing  lasting  or  high 
grade  immunity.  For  the  most  part,  they  produce  a  resistance  that  is 
effective  only  while  the  living  parasites  are  in  the  host.  One  attack  does 
not  confer  protection  against  subsequent  attacks,  as  in  syphilis,  malaria, 
leishmaniasis,  and  most  other  infections  due  to  animal  parasites.  On 
the  other  hand,  many  parasites  belonging  to  the  plant  kingdom,  such  as 
certain  bacteria,  are  particularly  active  in  stimulating  antibody  produc- 
tion, and  thereby  produce  a  high  grade  and  lasting  immunity.  There 
are  exceptions  to  this  general  rule ;  thus,  yellow  fever  produces  a  lasting 
immunity,  whereas  pneumonia  does  not. 

The  diseases  in  which  one  attack  conveys  a  lasting  immunity  are 
plague,  typhoid  fever,  cholera,  smallpox,  chickenpox,  scarlet  fever, 
measles,  yellow  fever,  typhus  fever  and  mumps. 

The  infections  which  do  not  confer  lasting  immunitv''  are  pyogenic 
cocci,  gonorrhea,  pneumonia,  influenza,  glanders,  dengue  fever,  relapsing 
fever,  erysipelas,  malaria  and  tuberculosis. 

An  infectious  disease  is  a  reaction  in  Ihe  host  caused  by  a  parasite. 
It  is  the  result  of  a  struggle  between  two  variable  factors — the  pathogenic 
powers  of  the  parasite  on  the  one  hand,  and  the  resistance  of  the  host  on 
the  other,  each  of  these  again  modified  by  variations  in  the  conditions 
under  which  the  struggle  takes  place.  An  infectious  disease,  then,  is  a 
reaction,  not  an  entity. 

Septicemia,  or  bacteremia^  is  a  condition  in  w^hich  microorganisms 
become  generalized  and  circulate  in  the  blood.  They  may  grow  in  the 
blood,  but  more  often  their  presence  in  the  circulating  blood  represents 
an  overflow  from  a  local  focus  or  organ  where  they  are  growing.  Toxemia 
refers  to  the  general  symptoms  produced  by  the  absorption  of  bacterial 
toxin.  Sapremia  is  a  febrile  condition  resulting  from  the  absorption 
of  putrefactive  products  (not  microorganisms)  caused  by  saprophytic 
bacteria. 

A  pathogenic  microorganism  is  one  that  harms  the  host.  There  are 
all.  degrees  of  pathogenicity.  A  non-pathogenic  parasite  does  not  harm 
the  host. 

The  invasive  poiuer  is  often  spoken  of  as  virulence,  in  contradistinc- 
tion to  toxicity.  Toxicity  implies  merely  the  ability  to  produce  poisons, 
and  is  not  necessarily  associated  with  the  power  to  invade.  Some  organ- 
isms, like  tubercle  bacilli  and  the  spirochetes  of  syphilis,  have  a  very 
slow,  gradual,  but  progressive  power  of  invasion  owang  to  the  lack  of 


526  IMMUNITY 

acute  physiological  reaction  on  the  part  of  the  host,  resulting  from  the 
presence  of  the  microorganisms.  Microorganisms  that  possess  active 
invasive  powers  produce  general  infections,  which  are  often  malignant, 
but  may  be  benign. 

Communicability  means  the  facility  with  which  parasites  pass  from 
one  host  to  infect  another.  The  degree  of  communicability  varies  enor- 
mously in  different  instances,  and  depends  upon  many  variable  factors, 
especially  the  mode  of  exit,  the  manner  of  transfer,  the  susceptibility, 
the  channel  of  entrance,  the  dose  necessary  to  cause  infection,  etc.  There 
is  no  relation  between  communicability  and  virulence.  Thus,  smallpox, 
chickenpox,  measles,  epidemic  influenza  and  common  colds  have  a  high 
degree  of  communicability;  diphtheria  and  scarlet  fever  are  much  less 
active  in  this  regard,  while  leprosy  is  spread  with  difficulty.  We  are 
ignorant  of  some  of  the  factors  concerned  in  the  transmission  of  disease. 

Inheritance  plays  an  important  role  in  immunity.  Infection  often 
takes  a  mild  course  among  those  races  in  which  it  has  long  been  endemic, 
whereas  the  same  disease  suddenly -introduced  among  a  new  people  is 
relatively  more  severe  and  spreads  more  rapidly.  Eesistance  as  well  as 
susceptibility  may  be  transmitted  from  parent  to  offspring.  In  the  case 
of  natural  immunity,  the  transmission  is  probably  an  instance  of  true 
inheritance,  but  in  acquired  immunity  it  is  probably  congenital.  Com- 
pare Heredity  and  hereditary  transmission  of  disease,  page  607. 

Koch's  laws  or  Koch's  postulates  are  now  stated  as  follows:  (1) 
A  specific  organism  must  always  be  associated  with  a  disease,  (2)  when 
isolated  in  pure  culture  (3)  and  inoculated  into  a  healthy  susceptible 
animal  it  must  always  produce  the  disease  and  (4)  should  be  obtained 
again  in  pure  culture. 

In  Koch's  first  paper  ^  on  infectious  bacteria,  presented  in  1878,  he 
states  that  "the  repeated  findings  of  microorganisms  in  traumatic  in- 
fections and  experimental  results  connected  with  these  findings  would 
indicate  that  these  diseases  are  of  parasitic  nature.  This  can  only  be 
proved,  however,  when  it  will  be  possible : 

(1)  To  find  the  parasitic  organisms  in  every  case  of  the  disease. 

(2)  To  find  them  in  such  numbers  and  so  distributed  that  all  the 

symptoms  can  be  ascribed  to  the  parasite. 

(3)  To  identify  morphologically  a  well  characterized  organism  with 

each  traumatic  infection." 

In  1885  Hueppe,  a  pupil  of  Koch,  wrote  a  text-book  of  bacteriology  * 
at  Koch's  suggestion.    This  book  was  written  in  the  midst  of  the  "spon- 

^  "Untersuchungen  iiber  die  Aetiologie  der  Wundinfeetionskrankheiten," 
Leipzig,  1878,  by  R.  Koch.     Centralblatt  f.  d.  med.  Wis^enschaften. 

^"The  Methods  of  Bacteriological  Investigation"  (1885),  by  F.  Hueppe,  p.  11. 
Trans,  by  H.  M.  Biggs  (1886),  Appleton. 


MECHANISM  OF  IMMUNITY  627 

taneous  generation"  controversy  which  circumstance  influenced  the  form 
in  which  Koch's  postuhites  are  given: 

1.  It  is  to  be  deterniincil  whether,  in  decomposition  or  disease,  bacteria 

are  present  or  not. 

2.  If  bacteria  are  present  it  is  to  be  determined  what  forms  they  possess. 

3.  Each  form  found   to  be  present  is  to   be  cultivated  by  itself,   free 

from  all  chemical  and  morphological  mixtures — "pure  cultures." 

4.  By  transfers  of  really  pure  cultures  to  decomposable  materials  or 

susceptible  animals,  it  is  to  be  determined  whether  the  bacteria 
found  are  the  cause  of  the  decomposition  or  disease. 

It  was  not  until  ISDO,^  however,  that  Koch  gave  a  clear  statement 
of  his  fundamental  concept  of  the  relation  of  bacteria  to  disease.  In 
discussing  the  view  held  by  some  at  that  time  that  bacteria  only  became 
pathogenic  under  the  influence  of  the  disease  process  he  argued  that : 

1.  If  the  parasite  is  found  in  every  case  of  a  disease  and  under  condi- 

tions which  conform  with  the  pathological  changes  and  clinical 
picture ; 

2.  If  it  is  not  found  in  any  other  disease  as  an  accidental  and  non- 

pathogenic parasite; 

3.  If  after  being  completely  isolated  from  the  body  and  repeatedly  trans- 

planted in  pure  culture  it  can  reproduce  the  disease  on  inocu- 
lation; then  it  cannot  have  an  accidental  relation  to  the  disease, 
but  the  parasite  must  be  the  cause  of  the  disease. 


MECHANISM  OF  IMMUNITY 

The  relation  between  seed  and  soil  is  often  used  to  explain  immunity, 
but  this  analogy  does  not  help  us  very  much  for  the  reason  that  the  soil 
does  not  react.  A  fertile  soil  may  be  considered  susceptible;  a  barren 
soil  immune.  The  seed  in  the  first  instance  may  be  pathogenic  or  non- 
pathogenic. The  host  is  able  to  resist  the  intrusion  and  growth  of  the 
non-pathogenic  microorganisms  and  protect  itself  against  harm  through 
its  mechanism  of  immunity.  If  the  protecting  devices  are  insufficient 
to  guard  against  attack,  the  germs  multiply,  produce  poisonous  sub- 
stances, or  harm  the  host  in  other  ways.  The  reason  that  the.  same 
microorganism  may  be  pathogenic  for  one  host  and  harmless  for  an- 
other depends  upon  the  presence  or  lack  of  immunity.  The  virulence 
of  a  microorganism  is  an  expression  of  the  intensity  of  the  reaction  be- 
tween the  seed  and  the  soil.  Virulence  may  be  strengthened  or  attenuated 

"  "Ueber  Bakteriologische  Forschung,"  by  R.  Koch.  1.  Allgemeinen  Sitzung 
des  X  Internationalen  Medicinischeii  Congresses,  am  4  August,  1890.     (Berlin.) 


528  IMMUNITY 

either  by  increasing  or  decreasing  the  resistance  of  the  host  or  by  in- 
creasing or  decreasing  the  resistance  of  the  parasite. 

Theories  of  Immunity. — It  is  now  quite  evident  that  the  mechanism 
of  immunity  varies  in  different  infections  and,  to  a  certain  extent,  even 
in  the  same  infection  under  different  conditions.  We  are  still  in  ignor- 
ance of  the  mechanism  by  which  the  body  protects  itself  against  many 
diseased  states. 

Historically  considered,  immunology  as  a  science  dates  back  scarcely 
30  years.  Many  primitive  people  attempted  to  immunize  themselves  in 
a  crude  sort  of  way,  but  with  methods  now  recognized  as  essentially 
sound.  Thus,  South  African  tribes  tried  to  protect  themselves  against 
snake  bites  by  using  a  mixture  of  snake  venom  and  gum;  the  Moors 
immunized  cattle  to  pleural  pneumonia  by  placing  some  of  the  virus 
under  the  skin  of  the  animal.  The  inoculation  against  smallpox  used 
from  time  immemorial,  and  vaccination  with  cowpox  introduced  by 
Jenner  in  1798,  are  examples  of  the  first  practical  use  of  specific  methods 
in  the  history  of  immunity. 

Pasteur  was  greatly  influenced  by  Jenner's  demonstration  that  a 
mild  form  of  a  disease  protects  against  the  severe  form.  Pasteur  ex- 
panded the  fact  taught  by  Jenner  into  a  general  principle.  Practically 
all  of  Pasteur's  work  in  immunity  that  bore  practical  fruit,  such  as 
vaccinations  against  chicken  cholera,  anthrax,  and  rabies,  is  based  upon 
this  guiding  principle. 

Pasteur  in  1888  expounded  his  "exhaustion"  theory,  which  was  the 
first  attempt  at  a  scientific  explanation  of  immunity.  Pasteur  was  a 
chemist  and  his  theory  was  a  simple  chemical  conception,  largely  based 
upon  his  work  upon  the  fermentation  of  sugar  with  yeast.  He  re- 
garded the  body  immune  because  its  food  supply  was  used  up  and  the 
microorganisms  could,  therefore,  no  longer  grow — just  as  yeasts  cease 
to  grow  when  the  sugar  is  used  up  in  a  culture  medium.  It  is  now  easy 
to  disprove  the  exhaustion  theory.  Bacteria  may  continue  to  grow 
after  recovery,  as  in  bacillus  carriers.  Further,  bacteria  may  grow 
well  enough  in  the  dead  tissues  and  fluids  of  immune  animals,  and, 
again,  immunity  may  be  induced  by  the  inoculation  of  dead  bacterial 
products,  substances  which  can  hardly  use  up  food  material.  Eecently 
Pasteur's  exhaustion  theory  has  been  revived  in  a  modified  form  by 
Ehrlich,  who  considers  that  there  is  sufficient  evidence  of  this  form  of 
immunity  in  certain  cases,  as  in  cancer.  Ehrlich  calls  it  "atreptic" 
immunity. 

Chaveau  proposed  the  "retention"  theory,  the  exact  opposite  of 
the  exhaustion  theory.  This  theory  is  also  based  upon  the  analogy  of  the 
behavior  of  bacterial  growth  in  vitro  compared  to  their  growth  within 
the  body.  It  soon  became  evident  that  bacterial  growth  ceases  even 
though  abundant  food  is  present,  and  that  this  inhibition  is  due  to  the 


MECHANISM  OF  nrMUNITY  529 

retention  of  products  oi'  iiu-taljolisni  oi'  bacterial  activity.  Chauvoau 
considers  that  such  substances  are  retained  within  the  body,  which  thus 
protects  itself  against  further  growtli  and  development  of  the  microor- 
ganisms and  thus  establishes  innnunity. 

The  above  theories  are  generalizations  which  have  now  little  more 
than  historical  interest.  We  now  know  that  no  one  mechanism  of  im- 
munity will  explain  all  cases.  In  some  instances  phagocytosis  plays  an 
important  part;  in  others  antibodies  of  various  sorts;  the  side-chain 
theory  appears  to  account  for  most  of  the  facts  in  antitoxic  immunity. 
In  some  cases  the  immunity  is  due  to  a  negative  property  in  that  there 
is  an  absence  of  specific  affinity  between  the  toxin  and  the  cells.  In 
others  it  is  a  positive  factor  and  is  due  to  the  presence  of  antibodies 
able  to  neutralize  the  toxic  action.  The  mechanism  of  immunity  in 
some  instances  resides  mainly  in  the  blood  and  fluids;  in  other  cases  it 
is  evidently  more  directly  associated  with  cellular  activity.  In  some 
instances  immunity  depends  upon  the  power  of  immediate  reaction  in 
the  sense  of  anaphylaxis.  In  all  cases  the  mechanism  is  probably  com- 
plex and  multiple. 

The  unsatisfactory  state  of  our  knowledge  in  certain  fields  of  im- 
munity is  well  illustrated  in  the  case  of  anthrax.  The  mechanism  of 
protection  is  not  at  all  understood  in  this  infection,  which  was  the  first 
and  classic  illustration  of  a  germ  disease.  The  mechanism  of  immunity 
in  common  colds  is  also  complex  and  obscure. 

Our  resistance  to  disease  is  in  many  cases  due  to  a  simple  mechani- 
cal or  chemical  protection  against  the  invasion  of  the  pathogenic  micro- 
organisms; that  is,  the  tissues  are  susceptible  enough,  but  are  guarded 
against  the  invasion  of  the  germs  of  disease.  Many  examples  may  be 
cited  in  this  category.  Thus,  one  of  the  important  functions  of  the 
skin  consists  in  this  mechanical  protection  of  the  tissues  underneath. 
There  is  but  a  single  layer  of  epithelium  between  us  and  death.  The 
smooth  conjunctiva  is  protected  by  the  constant  washing  of  the  tears  and 
the  motion  of  the  eyelids.  The  lungs  are  safeguarded  by  the  shape  of  the 
upper  respiratory  passages  and  the  moisture  of  the  mucous  membranes, 
which  act  as  a  mechanical  trap  for  many  bacteria.  Some  of  those  that 
pass  deeper  are  carried  back  by  the  mechanical  action  of  the  cilia.  The 
sensitive  and  susceptible  mucous  membrane  of  the  intestines  is  partly 
protected  through  the  acidity  of  the  gastric  juice,  which  may  be  suffi- 
cient to  destroy  cholera  vibrios  and  other  microorganisms  susceptible 
to  acid. 

Cellular  Immunity  and  Humoral  Theory. — Within  the  body  the 
mechanism  of  immunity  is  an  adaptation  of  cell  nutrition.  The 
mechanism  varies  with  different  infections  and  in  different  stages  of 
the  same  infection.  In  certain  diseases  the  immunity  seems  to  reside 
mainly  in  the  activity  of  the  cells.     In  other  diseases  the  immunity 


630  IMMUNITY 

is  due  chiefly  to  specific  properties  in  the  blood.  The  first  is  the  cellular 
and  the  second  the  humoral  theory.  As  we  shall  have  occasion  to  see, 
the  immune  bodies  in  the  blood  are  probably  in  all  cases  derived  from  the 
cells,  so  that  the  cells  play  the  fundamental  part  in  most  processes  of 
immunity.  However,  the  great  majority  of  the  studies  in  immunology 
have  been  focused  upon  the  changes  in  the  blood.  This  is  not  due  to  the 
fact  that  the  blood  alone  represents  these  changes,  but  that  it  best  repre- 
sents them,  and  thus  affords  the  readiest  method  of  attacking  the  prob- 
lem. 

The  hlood  is  the  most  fluid  and  most  cosmopolitan  of  all  the  tissues 
of  the  body,  visiting  every  part,  bearing  to  each  part  certain  substances, 
and  removing  from  each  part  certain  other  substances.  The  blood  is  a 
digestive  fluid,  and  in  so  far  as  immunity  is  concerned  is  even  more  im- 
portant than  the  digestive  fluids  of  the  gastro-intestinal  tract.  The 
blood  is  not  the  usual  handler  of  proteins.  Blood  ferments  usually  are 
not  in  an  active  state  like  trypsin  or  pepsin.  The  proteolytic  enzyme  in 
the  blood,  however,  is  of  trypsin-like  nature.  There  are,  in  addition, 
carbohydrates,  lipases,  etc.,  in  the  blood  which  doubtless  play  a  very  im- 
portant role  in  immunity.  There  is  at  the  same  time  an  anti-ferment 
present  which  under  normal  conditions  prevents  autodigestion  of  the 
blood  and  tissues.  It  is  evident  that  it  is  easy  to  study  the  blood  and  its 
changes,  as  some  of  it  may  readily  and  repeatedly  be  withdrawn  during 
life  in  order  to  observe  its  changes  without  in  any  way  harming  the 
animal. 

The  fundamental  processes  of  immunity  within  the  body  must  all 
depend  upon  some  chemical  or  physical  change,  but  we  know  very  little 
concerning  the  chemical  composition  of  the  substances  that  play  the  chief 
role  or  the  physical  nature  of  the  changes.  Great  advances  have  been 
made  in  immunology  despite  this  lack  of  chemical  knowledge;  for  these 
advances  we  are  indebted  to  experimental  biology,  through  which  we 
have  learned  the  results  of  many  effects  without  a  knowledge  of  their 
nature  or  the  intimate  processes  concerned. 

Natural  Immunity. — Natural  immunity  is  an  inherited  character 
possessed  in  common  by  all  individuals  of  a  given  species.  It  is  in- 
herent to  a  greater  or  less  extent  in  all  members  of  that  species.  It 
may  be  present  at  birth  or  develop  in  later  years.  There  are  very  many 
examples  of  natural  immunity.  Thus,  most  of  the  communicable  in- 
fections of  man  are  peculiar  to  man;  that  is,  the  lower  animals  have  a 
natural  immunity  to  such  diseases  as  measles,  mumps,  scarlet  fever, 
typhoid  fever,  cholera,  gonorrhea,  syphilis,  yellow  fever,  malaria,  leprosy, 
and  so  on  through  a  long  repertoire.®     Even  tuberculosis,  which  is  the 

*It  is  true  that  some  of  these  infections  may  be  conveyed  to  monkeys  or 
other  animals  by  artificially  introducing  large  amounts  of  the  virus,  but  these 
animals  do  not  contract  these  diseases  naturally  and  therefore  show  a  high  de- 
gree of  natural  immunity. 


MECHANISM  OF  IMMUNITY  531 

most  common  and  widespread  (jf  infections,  has  its  own  particular 
bacillus  to  which  man  is  especially  susceptible  and  to  which  the  lower 
animals  show  a  marked  degree  of  natural  immunity.  On  the  other 
hand,  man  shows  a  high  grade  of  natural  immunity  to  a  large  number 
of  infections  to  which  the  lower  animals  are  subject,  as  rinderpest, 
black  leg  (symptomatic  anthrax),  Texas  fever,  hog  cholera,  etc. 

The  monopoly  which  man  possesses  of  being  susceptible  to  infec- 
tions which  the  lower  animals  successfully  resist  is  not  confined  to  the 
bacteria  alone,  but  includes  many  protozoa  and  higher  animal  parasites. 
Thus,  the  hookworm  of  man  is  different  from  the  hookworm  of  the  horse, 
the  dog,  the  seal.  Each  host  has  its  own  species  of  hookworm  which, 
though  closely  allied,  are  not  interchangeable.  That  is,  the  horse  has  a 
natural  immunity  to  the  hookworm  that  is  parasitic  for  man,  and  vice 
versa. 

There  is  a  group  of  infections,  including  the  pyogenic  cocci,  anthrax, 
tetanus,  malignant  edema,  glanders,  actinomycosis,  rabies,  plague,  foot- 
and-mouth  disease,  malta  fever,  tuberculosis,  milk  sickness,  infections 
with  the  paratyphoid  bacillus,  ringworm,  and  many  higher  forms  of 
animal  parasites,  which  are  common  to  many  species  in  widely  dif- 
ferent genera.  Eabies  is  an  example  of  an  infection  common  to  all 
mammalian  species. 

There  are  certain  remarkable  facts  connected  with  natural  immu- 
nity. For  example,  white  mice  are  naturally  immune  to  glanders, 
whereas  the  field  mouse  possesses  a  high  degree  of  susceptibility.  When 
we  consider  how  slight  must  be  the  differences  in  the  structure,  the  func- 
tion, the  chemistry,  and  the  metabolism  in  the  white  mouse  when  com- 
pared with  its  gray  cousin,  we  begin  to  appreciate  the  subtle  differences 
and  perhaps  complex  factors  upon  which  immunity  depends.  If  we 
could  find  out,  for  example,  why  the  goat  is  resistant  to  tuberculosis 
while  domestic  cattle  are  particularly  susceptible,  we  would  have  the 
foundation  for  a  specific  preventive  and  cure  for  that  disease. 

Practically  all  the  individuals  of  a  certain  species  have  about  an 
equal  susceptibility  or  an  equal  immunity  to  a  given  infection.  These 
factors  are  more  constant  than  commonly  supposed.  Laboratory  ani- 
mals react  with  certainty  and  with  striking  uniformity  to  an  infection 
of  known  virulence,  provided  the  virus  is  brought  into  association  with 
certain  tissues.  Thus,  strikingly  uniform  results  are  obtained  from  a 
given  culture  of  plague  introduced  subcutaneously  into  the  guinea-pig, 
or  of  tuberculosis  into  the  peritoneal  cavity  of  the  monkey,  or  of  strep- 
tococci into  the  circulation  of  the  rabbit,  or  of  rabies  under  the  dura 
of  the  dog,  or  of  anthrax  into  the  mouse.  Pneumococcus  and  streptococ- 
cus cultures  can  be  measured  with  reasonable  accuracy  upon  white  mice 
of  approximately  uniform  weight.  Man  is  no  exception  to  this  general 
statement,  as  far  as  may  be  judged  from  the  data  at  hand.     Practically 


532  IMMUNITY 

all  persons  are  alike  susceptible  to  smallpox,  yellow  fever,  measles, 
tetanus,  and  many  other  infections.  In  epidemics  some  individuals 
escape.  In  other  epidemics  the  disease  varies  greatly  in  severity.  These 
apparent  exceptions  may  not  be  due  so  much  to  varying  degrees  of  im- 
munity but  rather  to  variation  in  the  dose  and  virulence  of  the  virus, 
the  channel  of  infection,  symbiosis,  and  other  factors. 

In  some  cases  the  immunity  is  so  weak  that  the  balance  between 
health  and  disease  is  quite  unstable.  This  appears  to  be  the  case  with 
tuberculosis  in  man.  We  ordinarily  possess  sufficient  natural  immunity 
to  tuberculosis  successfully  to  resist  small  amounts  of  infection,  but 
this  resistance  may  readily  be  broken  down  by  any  influences  which 
undermine  our  general  vitality. 

Natural  immunity  may  be  broken  down  by  various  means  that 
weaken  the  animal,  such  as  fasting,  the  production  of  an  experimental 
diabetes  with  phlorizin,  fatigue,  excessive  cooling  of  the  body,  as  the 
clipping  of  the  hair  of  thick-furred  animals,  etc.  Thus,  chickens  are 
ordinarily  naturally  immune  to  anthrax,  but  may  be  infected  if  their 
feet  are  kept  in  cold  water.  White  rats  are  resistant  to  anthrax,  but 
become  susceptible  if  the  hair  is  clipped. 

Acquired  Immunity. — By  acquired  immunity  is  meant  a  specific 
resistance  to  an  infection  that  is  not  naturally  inherent  in  all  the  in- 
dividuals of  a  species,  but,  as  the  term  indicates,  the  immunity  is  acquired 
during  the  lifetime  of  the  individual.  Immunity  may  be  acquired  either 
through  some  "natural"  event,  such  as  an  attack  of  a  disease,  or  may 
be  "artificially"  induced  by  the  introduction  of  some  substance,  such  as 
a  serum,  toxin,  vaccine,  or  a  virus. 

Acquired  immunity  may  be  either  active  or  passive.  Active  immu- 
nity is  induced  by  an  attack  of  a  disease  or  by  the  introduction  of  a 
virus  or  suitable  toxin  into  the  system.  Immunity  thus  acquired  is 
active  in  the  sense  that  it  depends  upon  a  direct  stimulation  of  the  pro- 
tecting mechanism  resulting  in  a  series  of  reactions  within  the  body. 
Passive  immunity,  or  transferred  immunity,  is  mainly  antitoxic  im- 
munity. Other  antibodies  also  have  the  power  of  conferring  passive 
protection,  but  in  a  lesser  degree  than  antitoxins.  Passive  immunity  is 
so  called  for  the  reason  that  the  antibodies  (antitoxin)  are  introduced 
into  the  body,  which,  therefore,  takes  no  part  in  their  formation.  The 
injection  of  diphtheria  toxin  into  the  horse  causes  an  active  immunity  in 
that  animal;  the  injection  of  some  of  the  antitoxin  contained  in  the 
horse's  serum  into  a  child  causes  a  passive  immunity  in  the  child. 
The  protection  against  smallpox  produced  by  vaccination  is  an  example  of 
active  immunity ;  so  also  is  the  immunity  produced  by  bacterial  vaccines. 

Non-specific  immunity  is  an  expression  of  natural  immunity.  The 
term  is  perhaps  a  misnomer — in  any  case,  so-called  "non-specific  immu- 
nity" is  slight  and  limited.    It  is  stimulated  by  the  parenteral  injection 


•    MECHANISM  OF  IMMUNITY  533 

of  a  foroi.irn  prdtoiii,  usually  directly  into  the  hlood  stream.  The 
mechanism  of  iiou-spociric  iinimmity  may  include  all  flic  natural  protect- 
ing mechanisms,  such  as  phagocytosis,  lysis,  agglutination,  and  even  ana- 
phylaxis. The  jiareiiteral  injection  of  a  foreign  ])r()tein  influences  chemi- 
cal reactions,  normal  physiologic  functions,  and  the  integrity  of  tissues. 
It  mohilizes  the  enzymes  in  the  sense  that  they  are  made  availahle  for 
the  reactions  of  immunity.  Ahderhalden  liolds  that  there  is  an  increased 
amount  of  specific  enzymes  brought  forth  hy  the  parenteral  injection  of 
non-specific  proteins.  Non-specific  immunity  hrought  about  in  this  way 
iinds  its  explanation  in  terms  of  anaphylaxis. 

At  best,  "non-specific  immunity"  has  very  limited  power  and  in  only 
a  few  infections — notably  gonococcic  arthritis.  The  non-specific  protein 
injected  is  usually  typhoid  vaccine  or  proteoses.  The  action  of  serum 
in  pneumonia  may  also  be  an  example  of  non-specific  immunity.  Just 
how  it  acts  is  not  clear,  but  probably  the  changes  in  the  physical  charac- 
ter of  the  blood  or  the  permeability  of  the  membranes  permits  mobiliza- 
tion of  the  enzymes  or  other  immunity  principles  where  they  can  exert 
their  beneficial  effects.  In  other  words,  non-specific  immunity  is  a  term 
used  to  indicate  the  stirring  up  of  forces  inactive,  but  normally  available 
for  the  defense  of  the  body  against  infection. 

Mixed  Immunity. — Mixed  immunity  is  a  combination  of  the  active 
and  passive.  This  is  used  practically  in  plague  prophylaxis  and  has 
been  proposed  for  other  infections.  It  consists  in  injecting  a  mixture 
of  antitoxic  serum  and  the  appropriate  bacterial  vaccine.  The  advantage 
of  this  procedure  consists  in  the  fact  that  the  passive  or  antitoxic  im- 
munity diminishes  the  severe  reactions  which  sometimes  follow  the  in- 
troduction of  a  bacterial  vaccine.  It  also  affords  an  immediate  protection 
and  thereby  guards  the  body  during  the  time  it  always  takes  for  the 
active  immunity  to  become  effective. 

The  toxin-antitoxin  mixture  used  against  diphtheria  is  an  example  of 
mixed  immunity.  In  this  case  only  enough  antitoxin  is  used  to  guard 
the  toxin. 

In  the  mixtures  known  as  sensitized  vaccines,  the  action  is  bac- 
teriolytic rather  than  antitoxic. 

How  Active  Immunity  May  Be  Acquired. — Immunity  may  be  ac- 
quired by: 

(a)  An  attack  of  a  disease. 

(b)  By  the  introduction  of  a  virus. 

(c)  By  the  introduction  of  a  vaccine. 

(d)  By  the  introduction  of  a  toxin,  or  other  product  of  bacterial 

activity. 

(a)  An  Attack  of  the  Disease. — Certain  diseases,  whether  acquired 
naturally  or  induced  artificially,  leave  an  immunity  which  varies  greatly 


534  IMMTJKITY 

in  degree  and  duration.  The  following  diseases  leave  a  definite  immu- 
nity of  high,  though  variable;,  grade:  smallpox,  yellow  fever,  measles, 
whooping-cough,  scarlet  fever,  cerebrospinal  meningitis,  infantile  paraly- 
sis, typhoid  fever,  typhus  fever,  chickenpox,  mumps.  Second  attacks  of 
smallpox,  measles,  typhoid  fever,  and  other  infections  in  this  list 
are  not  uncommon,  showing  that  the  immunity  is  rarely  if  ever  absolute. 

Some  diseases,  such  as  pneumonia,  erysipelas,  and  malaria,  seem  to 
predispose  to  subsequent  attacks,  that  is,  diminish  resistance.  Even  in 
this  class  of  infections  there  must  be  a  certain  amount  of  immunity, 
however  short,  else  the  patient  would  not  recover. 

(b)  By  tile  Introduction  of  a  Virus  into  the  System. — The  practice 
of  intentionally  inoculating  smallpox  was  the  first  example  in  prevent- 
ive medicine  in  which  use  was  made  of  the  fact  that  one  attack  of  a 
disease  confers  immunity  to  a  subsequent  attack  of  the  same  disease. 
The  present-day  vaccination  with  cowpox  (a  modified  smallpox)  may 
be  considered  as  belonging  to  this  category.  The  principle  is  used  to 
a  much  greater  extent  in  veterinary  practice  either  by  using  a  small 
amount  of  the  virus,  or  by  introducing  it  in  an  unusual  way  or  by 
inoculating  the  animals  at  a  time  when  they  are  found  to  be  least 
susceptible.  In  this  way  a  benign  form  of  the  disease  is  produced  which 
protects  against  the  severe  and  fatal  forms.  These  methods  are  used 
in  Texas  fever,  rinderpest,  pleuropneumonia,  anthrax,  etc. 

A  distinction  is  made  between  a  virus  and  a  vaccine.  If  the  material 
used  contains  the  living  active  principle  it  should  be  called  a  virus.  If 
the  virus  is  dead  it  should  be  called  a  vaccine.'^ 

The  highest  and  most  lasting  degrees  of  immunity  may  be  produced 
by  the  introduction  of  the  living  active  principle  into  the  system,  thus 
imitating  nature.  The  virus  may  be  diminished  in  virulence  as  m  an- 
thrax, vaccinia,  or  rabies.  A  high  grade  of  immunity  to  plague  and 
cholera  may  be  induced  in  man  by  the  injection  of  living  cultures.  In 
the  case  of  plague  the  cultures  must  be  greatly  diminished  in  virulence. 

In  the  case  of  cholera  virulent  strains  may  be  used,  as  this  disease  is 
neither  a  bacteremia  nor  septicemia,  and  there  is  very  much  less  danger 
in  introducing  the  cholera  vibrios  into  the  subcutaneous  tissue  than 
in  taking  them  by  the  mouth.  This  principle  of  introducing  the  virus 
into  a  resistant  tissue^  can  be  taken  advantage  of  in  various  infections, 
provided  the  virulence  of  the  disease  depends  largely  upon  the  channel 
of  infection.  The  virulence  of  the  virus  may  also  be  diminished  by 
certain  definite  processes,  such  as  growing  the  culture  at  an  unusually 
high  temperature,  as  in  the  case  of  anthrax;  or  by  prolonged  artificial 
cultivation,  as  in  the  classic  instance  of  chicken  cholera;  or  by  drying, 
as  in  rabies;  or  by  passage  through  animals,  as  in  smallpox  (cowpox) ; 

^Vaccine  {vacca,  a  cow)  is  not  a  good  term,  but  is  now  too  deeply  rooted  to 
change. 


BACTERIAL  VACCINES  536 

or  by  growing  on  uui'avorable  media;  by  the  use  of  very  small  amounts 
of  the  virus,  as  in  tuberculosis  and  many  other  infections;  or  by  the 
use  of  closely  related  strains,  such  as  the  human  tul^ercle  bacillus  for 
bovine  immunization.  Repeated  injections  of  a  virus  induce  a  much 
higher  and  more  lasting  immunity  than  single  inoculations. 

(c)  By  the  Introduction  of  a  Bacterial  Vaccine. — The  immunity 
produced  by  the  introduction  of  a  vaccine  into  the  body  corresponds 
precisely  to  the  immunity  acquired  by  the  introduction  of  a  virus,  the 
only  difference  being  that  the  living  virus  produces  a  more  lasting  and 
higher  degree  of  protection  than  that  produced  by  the  dead  vaccine. 
The  advantages  of  using  a  vaccine  instead  of  a  virus  are  obvious. 

BACTERIAL  VACCINES 

Dead  bacteria,  when  injected  into  the  tissues,  usually  produce  a  local 
reaction  at  the  site  of  inoculation  and  also  a  general  reaction.  The 
local  reaction  consists  of  swelling,  pain,  redness,  and  other  indications 
of  irritation  and  inflammation.  The  general  reaction  consists  of  fever, 
headache,  pains  in  the  muscles,  especially  in  the  back  and  legs,  malaise, 
and  sometimes  nausea.  The  reactions  usually  come  on  within  a  few 
hours  after  the  vaccine  has  been  introduced  and  rarely  last  longer  than 
2-i  to  48  hours.  It  is  customary  to  give  the  vaccines  in  the  afternoon, 
for  then  most  of  the  symptoms  have  passed  by  the  next  morning. 

The  vaccine  is  usually  prepared  from  a  fresh  twenty-four-hour  growth 
of  a  pure  culture  of  the  microorganism  upon  the  surface  of  agar.  In 
this  way  secondary  metabolic  products  in  the  medium  are  avoided  by 
simply  removing  the  surface  growth.  When  liquid  cultures  are  used 
the  foreign  substances  contained  in  the  medium  may  complicate  the  re- 
actions. The  cultures  are  usually  killed  by  exposure  to  heat  at  from  53° 
to  60°  C.  for  one  hour.  High  heat,  while  certain  to  kill  the  virus,  is 
undesirable,  for  the  reason  that  it  coagulates  the  albuminous  substances 
in  the  bacterial  cell  and  otherwise  alters  the  chemical  structure  of  the 
microorganism.  The  closer  the  vaccine  approaches  the  virus  the  better 
the  results,  so  far  as  immunity  is  concerned.  Therefore,  many  investi- 
gators prefer  to  kill  the  microorganisms  with  carbolic  acid,  chloroform, 
or  some  other  suitable  germicide. 

Preventive  inoculations  with  bacterial  vaccines  are  now  much  prac- 
ticed in  the  case  of  typhoid  fever,  plague,  and  cholera,  and  are  destined 
to  be  extended  to  other  infections.  The  dose  and  details  have  been  dis- 
cussed under  each  disease.  The  important  domain  of  vaccines  is  protec- 
tive, not  curative. 

Sensitized  vaccines  are  made  by  mixing  the  bacteria  with  its  specific 
antibody  and  then  washing  away  the  excess  of  antibody.  If,  for  example, 
typhoid  bacilli  are  injected  into  a  rabbit,  antibodies  appear  in  the  blood 


536  IMMUNITY 

serum  of  the  rabbit.  If  new  typhoid  bacilli  are  mixed  with  this  rabbit 
serum  (which  must  be  first  inactivated  by  heating  to  56°  C.  to  destroy 
complement),  the  bacilli  become  sensitized.  In  other  words,  the  bac- 
teria unite  with  the  specific  antibodies  present  in  the  rabbit's  serum. 
Sensitized  bacilli  may  be  used  dead  or  alive. 

The  advantages  of  sensitized  vaccines  have  been  advocated  by  Bes- 
redka,  Calmette,  Salembini,  Gay  and  others.  It  is  claimed  that  the 
protection  comes  quicker,  but  it  is  not  always  as  high  or  as  durable. 

Polyvalent  vaccines  consist  of  several  cultures  mixed  and  given  at 
the  same  time.  Thus,  a  tetravaccine,®  containing  typhoid,  paratyphoid 
A  and  B,  and  cholera,  was  used  in  Serbia. 

The  injections  are  always  given  subcutaneously.  Usually  three  or 
four  injections  are  given  at  intervals  of  about  five  to  ten  days.  Several 
injections  produce  an  immunity  of  much  higher  grade  and  longer  dura- 
tion. In  most  instances  the  acquired  immunity  lasts  from  two  to  five 
years,  and  may  be  renewed. 

Lipovaccines  consist  of  emulsions  of  the  bacteria  in  a  bland  neutral 
oil.  The  advantages  claimed  for  lipovaccines  are  that  they  diminish  local 
reaction,  because  absorption  is  retarded;  that  a  very  large  amount  can 
be  given  in  one  dose  without  toxicity;  that  a  focus  of  antigen  is  estab- 
lished which  acta  continuously.  The  oils  are  supposed  to  have  a  detoxi- 
cating  action.  All  these  theoretical  advantages  have  not  worked  out  in 
practice;  in  fact,  lipovaccines  give  only  about  half  the  protection  of 
saline  emulsions. 

Standardization  of  Bacterial  Vaccines. — Bacterial  vaccine  may  be 
standardized  by  several  methods  :^  Wright's  method  ^°  consists  in  com- 
paring the  number  of  bacteria  with  the  number  of  red  corpuscles  on  a 
stained  slide.  The  errors  in  this  method  are  numerous  and  may  vary 
from  50  per  cent,  to  100  per  cent,  if  counted  on  the  same  film  by  different 
observers. 

The  nephelometer  method  described  by  McFarland  ^^  consists  in  com- 
paring the  opacity  of  the  culture  with  a  series  of  standardized  tubes 
containing  a  fine  precipitate.  This  method  is  a  guess,  for  the  errors 
vary  from  25  per  cent,  to  200  per  cent.  Dunham  ^^  obtains  reasonably 
accurate  results  with  the  Kober  nephelometer.  This  method  only  takes 
10  minutes  and  is  practical. 

Wilson  and  Dickson  proceed  by  weighing  the  dried  culture  on  a  piece 
of  thin  platinum  foil.  The  method  has  not  been  used  on  account  of  the 
special  apparatus  necessary  for  its  application. 

*Castellani  and  Mendelson,  Brit.  Med.  Journal,  Nov.  13,  1915. 
»  Fitch   (review),  J.  A.  M.  A.,  Mar.  13,  1915,  LXIV,  11,  p.  893. 
1"  Wright,  A.  E. :      "On   Some  New  Procedures  for  the  Examination  of  the 
Blood  and  of  Bacterial  Cultures,"  Lancet,  London,  1901,  II,  11. 

"McFarland,  Joseph:    "The  Nephelometer,"  J.  A.  M.  A.,  Oct.  5,  1907,  p.  1176. 
^Journ.  Immunology,  Vol.  V,  No.  4,  July,  1920,  p.  337. 


BACTERIAL  VACCINES  537 

Tlie  plate-cultiiro  nictliod  consists  of  staiulardi/.iii;;  tlie  siisponsioM  by 
counting  the  colonii's  \\hi<h  (k'vclop.  The  defects  are  that  it  requires 
two  or  three  days  bol'orc  the  results  can  be  known;  that  the  colonies  may 
represent  the  growth  of  more  than  one  bacterium;  and  some  of  the  bac- 
teria may  not  grow.  The  plate  method  always  gives  low  counts  varying 
from  25  per  cent,  to  150  per  cent,  less  than  the  hcmocytometer. 

The  gravimetric  method  employed  by  Hopkins  '^  consists  in  the  use  of 
a  special  centrifuge  tube,  the  end  of  which  is  drawn  out  into  a  small  tip. 
This  Is  graduated  in  hundredths  of  a  cubic  centimeter.  The  amount  of 
centrifugalized  sediment  may  be  read  directly  upon  the  scale.  The 
method  gives  but  approximate  results. 

Mallory  and  Wright  ^*  first  used  the  hcmocytometer  for  counting  the 
number  of  bacteria  in  a  suspension.  The  chamber  used  is  made  for 
counting  blood  plates  by  the  Helbar  method.  A  method  which  actually 
counts  the  number  of  bacteria,  offers  the  most  accurate  technic  for 
standardizing  vaccines. 

Specificity. — ^lost  of  the  reactions  in  immunology  are  specific — not 
absolutely  so,  but  relatively;  that  is,  antibodies,  such  as  agglutinins, 
lysins.  precipitins,  or  opsonins,  usually  act  upon  the  corresponding  an- 
tigen with  much  greater  vigor  than  upon  any  other.  An  immunity  to 
one  disease,  no  matter  how  produced,  whether  natural  or  acquired,  af- 
fords no  protection  against  other  diseases.  There  is,  however,  no  abso- 
lute specificit}',  just  as  there  is  no  absolute  immunity. 

Certain  microorganisms  and  their  toxic  products  show  a  remarkable 
predilection  for  certain  cells  or  tissues.  In  this  sense  a  microparasite 
or  a  toxin  may  be  as  specific  in  its  action  as  a  qualitative  chemical  re- 
action. Thus,  there  is  a  specific  relation  between  tetanus  toxin  and 
nervous  matter,  while  the  poison  has  little  or  no  affinity  for  other  tis- 
sues. The  poison  of  infantile  paralysis  picks  out  certain  cells  in  tlie 
central  nervous  system  upon  which  it  acts  specifically.  Also  in  rabies 
the  brunt  of  the  lesions  falls  upon  the  cells  of  the  central  nervous  sys- 
tem. The  toxic  products  of  the  Bacillus  hotidinus  is  also  a  specific 
nerve  poison,  and  at  least  one  of  the  poisons  in  diphtheria  toxin  (toxon) 
acts  specifically  upon  the  nerves.  The  toxic  substances  may  also  react 
upon  less  important  or  indifferent  tissues,  but  such  action  is  often 
masked.  The  specific  action  of  toxins  explains  in  part  the  local  immu- 
nity enjoyed  by  some  tissues  and  further  explains  why  certain  viruses 
are  comparatively  harmless  when  introduced  into  the  body  through 
unaccustomed  channels.  We  have  already  seen  an  example  of  this  in 
a  case  of  cholera  when  introduced  into  the  subcutaneous  tissue.  In 
this  case  the  subcutaneous  tissue  is  resistant  to  the  invasion  of  the 

"Hopkins,  J.  G. :  "A  Method  for  Standardizing  Bacterial  Vaccines,"  J.  A. 
M.  A..  May  24.  1913.  p.  1615. 

"Mallory  and  Wright:  "Pathological  Technic,"  Ed.  4,  Philadelphia,  W.  B. 
Saunders  Company,  1910. 


538  IMMUNITY 

cholera  vibrio,  and  these  microorganisms  cannot  find  their  way  to  the 
intestinal  tract.  The  case  of  smallpox  is  instructive,  for  this  is  an  in- 
fection for  which  the  epithelial  structures  have  a  specific  susceptibility. 
It  is  practically  impossible  to  infect  a  susceptible  animal  with  cowpox 
when  the  virus  is  introduced  subcutaneously  or  directly  into  the  cir- 
culation. The  same  is  probably  true  of  smallpox.  When  smallpox 
virus  is  introduced  by  inoculation  upon  the  skin  the  disease  is  much 
milder  than  when  the  virus  is  introduced  naturally  by  way  of  the  respira- 
tory tract.  Evidently  the  skin  offers  greater  resistance  to  the  smallpox 
virus  than  is  offered  by  the  mucous  membranes.  On  the  other  hand, 
foot-and-mouth  disease  cannot  be  given  to  man  or  the  cow  when  rubbed 
upon  the  skin,  although  these  animals  are  very  susceptible  when  this 
virus  is  introduced  into  the  general  circulation  or  rubbed  upon  tbe  mu- 
cous membrane  of  the  mouth.  Every  worker  in  a  bacteriological  labora- 
tory is  familiar  with  the  difference  in  susceptibility  of  different  tissues 
and  Snows  the  importance  in  experimental  work  of  bringing  the  virus  in 
association  with  appropriate  structures. 

Certain  microorganisms,  such  as  B.  tuberculosis,  pus  cocci,  the  pneu- 
mococcus,  etc.,  have  the  power  of  affecting  almost  every  tissue  and  organ 
of  the  body.  No  part  of  the  body  is  immune  to  the  tubercle  bacillus, 
but  even  in  this  infectFon  some  tissues  are  more  susceptible  than  others. 
Thus,  tuberculosis  of  the  muscle  is  extremely  rare;  the  lungs  and  lymph 
nodes  are  especially  vulnerable. 

The  stomach  is  comparatively  rarely  attacked  by  infective  processes, 
although  constantly  exposed.  The  vaginal  mucous  membrane  in  the 
adult  and  the  bladder  are  resistant  to  gonorrheal  inflammations.  There 
are  many  similar  instances  of  specific  resistance  of  tissues. 

The  specific  action  of  toxins  gives  us  a  ready  reason  why  certain 
species  of  animals  are  immune  to  certain  infections.  In  this  case 
the  immunity  is  not  the  result  of  any  special  or  specific  reaction,  nor 
is  it  the  result  of  any  positive  character  possessed  or  acquired  by  the 
body,  but  is  a  negative  trait  entirely,  due  to  the  absence  of  specific 
chemical  affinity  between  the  cells  and  the  toxin.  The  turtle  is  im- 
mune to  tetanus  because  there  is  no  combining  affinity  between  the  nerve 
cells  of  the  turtle  and  tetanus  toxin.  The  immunity,  therefore,  depends 
upon  the  absence  of  the  appropriate  cell  receptors.  Eats  are  highly 
immune  to  diphtheria  toxin  and  hogs  to  snake  venom.  In  these  cases 
antitoxin  cannot  be  demonstrated  in  the  blood  of  the  rat  or  the  hog, 
and,  so  far  as  can  be  determined,  when  the  toxin  is  injected  into  these 
animals  it  is  not  neutralized  in  the  body.  The  simplest  conception  of 
the  mechanism  of  immunity  in  these  cases  is  to  regard  it  as  depending 
upon  a  negative  factor  resulting  upon  the  absence  of  suitable  receptors 
in  the  sense  of  Ehrlich's  side-chain  theory. 


BACTERTAL  VACCTNKS  639 

Local  and  General  Immunity. — Local  and  geueral  inmiuuity  depends 
upon  this  variation  in  siisccptihility  of  tlie  dilferent  tissues  to  differ- 
ent infections.  It  is  doulitliil  if  there  is  a  true  general  immunity 
in  any  case,  for  a  general  iiuniunity  is  in  almost  all  instances  based 
upon  a  local  resistance.  Even  antitoxic  immunity  in  diphtheria,  due 
to  the  antibodies  in  the  general  .circulating  blood,  is  the  result  of  a 
localized  neutralization  in  which  many  of  the  organs  and  tissues  of  the 
body  take  no  part.  There  are  many  examples  of  local  immunity. 
TnchineUa  spiralis  affects  especially  the  striped  muscles  and  never 
the  bones.  Diphtheria  seldom  extends  down  the  esophagus.  The  most 
marked  example,  perlia])s,  is  the  almost  perfect  local  immunity  of  the 
scalp  to  ringworm  in  adults,  which  contrasts  so  markedly  with  the  ab- 
solute susceptibility  of  children,  whereas  the  susceptibility  of  the  skin 
of  the  body  to  the  same  parasite  is,  if  anything,  greater  in  adults  than 
in  children  (Emery). 

j\Iany  remarkable  instances  of  local  immunity  are  shown  by  the  tissues 
and  must  be  familiar  to  all.  Thus,  erysipelas  does  not,  as  a  rule,  extend 
into  the  subcutaneous  tissues,  although  the  streptococcus  may  be  there; 
rarely  does  it  extend  back  into  the  area  of  the  skin  recently  affected. 

The  immunity  of  a  part  is  increased  or  diminished  by  the  presence 
or  absence  of  an  adequate  blood  supply.  As  a  rule,  very  vascular  struc- 
tures enjoy  a  comparative  immunity  to  infections  which  frequently 
attack  other  tissues  relatively  poor  in  blood  supply.  It  may  be  stated 
aa  a  general  rule  that  the  more  copious  the  supply  of  healthy  circulat- 
ing blood  the  greater  the  resistance  to  infection,  and  vice  versa.  This 
largely  accounts  for  the  local  immunity  enjoyed  by  the  mucous  mem- 
brane of  the  mouth  and  lips,  which  are  constantly  exposed  to  wound 
infections.  Herein  we  also  have  an  explanation  of  the  utility  of  fomen- 
tations and  other  hot  applications  in  the  initial  stages  of  an  infective 
lesion.  The  same  explanation  is  applied  in  Bier's  method  of  passive 
congestion,  in  which  an  excess  of  blood  is  made  to  flush  the  tissues. 
The  local  immunity  of  the  part  may  be  diminished  by  a  local  anemia 
from  any  cause,  by  the  presence  of  dead  or  injured  tissue,  by  the  action 
of  irritants,  trauma,  etc. 

Metchnikoff  has  pointed  out  that  in  many  infections  general  reaction 
is  in  inverse  ratio  to  the  local  reaction  at  the  site  of  introduction  of 
the  virus.  A  severe  and  prompt  local  inflammatory  reaction  indicates 
an  active  power  of  protection.  The  increased  volume  of  blood,  the"  cells, 
the  fluids  of  the  blood  and  tissues  are  concentrated  about  the  invading 
bacteria  to  wall  them  off  and  destroy  them,  that  is  the  immunity  of  the 
body  against  a  general  infection  frequently  depends  upon  the  promptness 
and  the  activity  of  the  local  power  of  reaction. 

Some  infections,  notably  streptococci,  plague,  or  organisms  belong- 
ing to  the  hemorrhagic-septicemic  group,  may  invade  the  body  with 


540  IMMUNITY 

little  or  no  local  inflammatory  reaction;  that  is,  little  or  no  barrier  is 
set  up  against  these  microorganisms:  they  may  invade  the  blood  and 
tissues  without  resistance  and  thus  cause  fatal  septicemias. 

Bacillus  Carriers. — Upon  recovery  from  an  infectious  process  the 
body  usually  rids  itself  completely  of  the  infecting  agent.  In  other 
words,  the  immunity  which  follows  an  attack  of  an  infectious  disease  is 
usually  associated  with  a  power  the  body  has  of  disinfecting  itself.  In 
most  cases  the  patient  is  convalescent  or  completely  restored  to  health 
before  the  cause  of  the  disease  has  disappeared  from  the  tissues.  This 
bespeaks  a  vigorous  protecting  mechanism,  but  when  this  resistance  is 
lowered  for  any  reason  a  relapse  may  ensue. 

In  many  instances  recovery  takes  place,  but  the  living  virulent 
microorganisms  continue  to  live  in  the  body.  This  constitutes  "immu- 
nity without  sterilization,"  a  term  introduced  by  Ehrlich,  though  a 
more  precise  expression  would  be  "immunity  without  disinfection." 
Such  persons  are  now  known  as  "carriers."  The  immunity  protects  the 
carrier  but  endangers  his  fellowmen.  Bacillus  carrying  is  common  in 
diphtheria,  typhoid  fever,  cholera,  pneumonia,  epidemic  cerebrospinal 
fever,  influenza,  and  many  other  bacterial  infections.  Protozoon  car- 
riers are  also  a  common  phenomenon.  The  best  examples  are  found 
in  malaria,  trypanosomiasis,  Texas  fever  in  cattle,  etc.  Analogous  in- 
stances are  also  found  in  the  higher  parasitic  worms  in  which  the  indi- 
vidual who  carries  the  parasite  is  not  affected.  Thus,  the  negro  and 
the  Filipino  show  a  relatively  high  degree  of  immunity  to  the  hookworm 
and  thus  endanger  their  more  susceptible  white  companion.  Lower  ani- 
mals, including  insects,  may  also  be  carriers. 

Convalescent  carriers  are  those  that  continue  to  harbor  the  micro- 
organisms during  recovery;  this  is  usually  a  matter  of  8  to  10  weeks 
or  less. 

Passive  carriers  are  those  who  harbor  the  microorganisms  without 
having  had  the  disease. 

Active  carriers  are  those  who  continue  to  harbor  the  microorganisms 
after  an  attack  of  the  disease. 

Acute,  transitory  or  temporary  carriers  harbor  the  microorganisms 
for  brief  periods  of  time;  chronic  or  permanent  carriers  for  months  and 
years.  Both  passive  and  active  carriers  may  be  either  temporary  or  per- 
manent. 

Intermittent  carriers  shed  the  microorganisms  from  time  to  time. 

Carriers  further  divide  themselves  into  three  groups:  (1)  intestinal 
and  urinary  carriers,  as  typhoid,  cholera,  dysentery,  etc.;  (2)  oral  car- 
riers, as  diphtheria,  pneumonia,  etc.;  (3)  blood  and  tissue  carriers,  as 
malaria. 

Bacillus  carriers  play  an  important  role  in  spreading  infections. 
They  explain  many  mysterious  facts  in  the  epidemiology  of  diphtheria, 


BACTEKIAL  VACCINES  541 

typhoid  fever,  cholera,  cerebrospinal  fever,  malaria,  etc.  The  bacillus 
carrier  is  sometimes  a  danger  to  himself.  This  is  seen  in  pneumonia, 
influenza,  streptococcal  and  other  infections. 

While  it  is  undoubtedly  true  that  bacillus  carriers  play  a  very  im- 
portant role  in  spreading  infection  from  man  to  man.  the  relative  im- 
portance compared  with  other  modes  of  transmission  cannot  be  stated 
in  percentage.  The  subject  is  still  too  young  for  definite  quantitative 
figures.  There  is  no  doubt  that  bacillus  carriers  are  more  important 
in  some  diseases  than  others  and  play  a  variable  role  under  different 
circumstances  in  the  same  disease.  In  our  studies  of  typhoid  fever  in 
Washington  one  carrier  was  discovered  in  the  examination  of  986 
healthy  individuals.  This  would  mean  approximately  300  t}'phoid 
bacillus  carriers  in  the  District  of  Columbia.  If  this  proportion  is  cor- 
rect, it  would  account  for  the  endemicity  of  typhoid  fever  in  Washing- 
ton. Perhaps  the  residual  typhoid  fever  in  many  places  is  largely  kept 
alive  through  bacillus  carrying.  Great  sanitary  reforms,  such  as  the 
change  from  polluted  to  pure  water,  causes  both  a  decline  in  the  amount 
of  the  fever  and  a  decrease  in  the  number  of  carriers.  It  now  seems 
evident  that  polluted  water  and  infected  milk  will  not  always  cause  the 
disease  directly  in  the  persons  drinking  these  fluids,  but  may  produce 
carriers  who  either  contract  the  disease  themselves  subsequently  or  give 
it  to  others  by  passing  the  virus  on  in  a  more  concentrated  and  virulent 
form,  or  to  more  susceptible  individuals. 

It  is  evident  from  the  nature  of  the  case  that  the  cure  and  control 
of  bacillus  carriers  is  one  of  the  vital  problems  in  preventive  medicine. 
It  is  not  only  largely  through  them  that  infection  is  spread,  but  the 
infections  themselves  are  kept  alive  in  these  carriers,  who  bridge  over 
the  interval  between  outbreaks.  It  is  quite  conceivable  that  with  our 
modern  methods  of  isolation  and  disinfection  certain  diseases  could 
readily  be  rendered  extinct  were  it  not  for  carriers. 

Immunity  is,  therefore,  a  double-edged  sword,  in  that  it  protects  the 
carrier  but  endangers  his  neighbor.  The  control  of  bacillus  carriers  is 
a  difficult  problem.  Such  unfortunate  persons  cannot  always  be  im- 
prisoned, nor  is  strict  isolation  always  necessary.  It  is  sufficient  in  the 
case  of  typhoid  fever  to  restrict  the  activity  of  the  carrier.  Thus,  a 
typhoid  carrier  should  not  cook,  prepare,  or  handle  food,  or  have  any- 
thing to  do  with  the  production  or  distribution  of  milk.  We  have  no 
satisfactory  cure  for  carriers — this  is  a  problem  for  the  future;  but 
their  number  may  be  lessened — this  is  a  problem  for  the  present. 

It  should  always  be  remembered  that  the  number  of  carriers  wiU 
diminish  proportionately  with  the  number  of  cases  of  certain  infections 
and  that  every  improvement  in  the  water  supply,  the  milk  supply,  the 
food  supply,  and  our  sanitary  conditions  generally  will  have  a  tendency 
sharply  to  diminish  the  number  of  carriers,  especially  of  intestinal  infec- 


543  IMMUNITY 

tions.  Therefore,  while  isolation,  disinfection,  and  other  methods  used  to 
control  the  spread  of  infection  will  never  be  completely  successful  as 
long  as  the  carrier  is  omitted,  nevertheless,  these  methods  are  entirely 
Justified  even  though  only  partially  useful.  It  is  the  duty  of  public 
health  officers  to  check  the  spread  of  infection  wherever  it  may  be 
found.  In  time  ready  methods  of  recognizing  bacillus  carriers  and 
means  of  neutralizing  their  potential  danger  will  be  more  effective 
than  is  now  possible. 

Latency  is  closely  allied  to  bacillus  carrying.  The  malarial  parasite 
may  remain  latent  in  the  spleen  and  other  internal  organs  for  years, 
during  which  time  the  person  remains  in  good  health.  But  when  the 
resistance  is  reduced  by  exposure,  fatigue,  starvation,  or  other  depressing 
influences  the  disease  again  breaks  out.  The  gonococcus  may  also  remain 
latent  for  years.  I  am  familiar  with  one  instance  in  which  the  tubercle 
bacillus  remained  latent  in  the  axillary  glands  for  10  years  and  then 
became  active  owing  to  a  condition  of  depressed  vitality.  Typhoid  osteitis 
may  develop  years  after  an  attack  of  typhoid  fever,  and  we  can  only 
assume  that  the  bacilli  have  remained  latent  in  the  tissues  all  that  time. 
The  phenomenon  of  latency  also  occurs  in  rabies,  tetanus,  and  other 
infections. 

Lowered  Resistance. — The  factors  which  lower  our  general  resist- 
ance to  disease  are  many  and  varied.  The  condition  known  as  depressed 
vitality,  lowered  tone,  general  debility,  weakened  constitution,  and  terms 
of  similar  import  imply  a  condition  in  which  immunity  is  lowered  in  a 
general  sense.  The  principal  causes  which  diminish  resistance  to  in- 
fection are:  wet  and  cold,  fatigue,  insufficient  or  unsuitable  food, 
vitiated  atmosphere,  insufficient  sleep  and  rest,  worry,  and  excesses  of 
aU  kinds.  The  mechanism  by  which  these  varying  conditions  lower 
our  immunity  must  receive  our  attention,  for  they  are  of  the  greatest 
importance  in  preventive  medicine.  It  is  a  matter  of  common  obser- 
vation that  exposure  to  wet  and  cold  or  sudden  changes  of  tempera- 
ture, overwork,  worry,  stale  air,  poor  food,  etc.,  make  us  more  liable  to 
contract  certain  diseases.  The  tuberculosis  propaganda  that  has  been 
spread  broadcast  with  such  energy  and  good  effect  has  taught  the  value 
of  fresh  air  and  sunshine,  good  food,  and  rest  in  increasing  our  resistance 
to  this  infection. 

There  is,  however,  a  wrong  impression  abroad  that,  because  a  low- 
ering of  the  general  vitality  favors  certain  diseases,  such  as  tuberculosis, 
common  colds,  pneumonia,  septic  and  other  infections,  it  plays  a  similar 
role  in  all  the  communicable  diseases.  Many  infections,  such  as  small- 
pox, measles,  yellow  fever,  tetanus,  whooping-cough,  typhoid  fever,  chol- 
era, plague,  scarlet  fever,  and  other  diseases,  have  no  particular  relation 
whatever  to  bodily  vigor.  These  diseases  often  strike  down  the  young 
and  vigorous  in  the  prime  of  life.    The  most  robust  will  succumb  quickly 


BACTERIAL  VACCINES  543 

to  tuberculosis  if  he  reoeives  a  sufficient  dose  of  the  virulent  microorgan- 
isms. A  good  physical  condition  does  not  always  temper  the  virulence  of 
the  disease;  on  the  contrary,  many  infections  run  a  particularly  severe 
course  in  strong  and  healthy  subjects,  and,  contrariwise,  may  be  mild 
and  benign  in  the  feeble.  Physical  weakness,  therefore,  is  not  necessarily 
synonymous  with  increased  susceptibility  to  all  infections,  although  true 
for  a  few  of  them.  In  other  words,  "general  debility"  lowers  resistance 
in  a  special,  rather  than  in  a  general,  sense. 

The  mechanism  by  which  the  various  causes  that  lower  vitality  and 
increase  susceptibility  act  is  in  most  cases  quite  obscure.  Here  is  a  field 
for  laboratory  research  in  immunology  that  offers  rich  reward  of  im- 
measurable practical  good.  Some  of  the  factors  concerned  will  be  briefly 
discussed. 

Exposure  to  wet  and  cold,  especially  in  combination,  is  a  frequent 
source  of  lowered  resistance.  The  exact  way  in  which  such  exposure 
acts  is  not  definitely  kno^vn,  but  laboratory  researches  offer  material 
for  a  number  of  suggestions.  Emery  ^^  sums  up  our  knowledge  upon 
this  subject  as  follows : 

"Immunity  is  to  a  very  large  extent  a  function  of  the  leukocytes, 
which  are  specialized  cells  to  which  the  defense  of  the  body  is  entrusted. 
Now,  the  functions  (movement  and  phagocytosis)  which  can  be  easily 
investigated  are  found  to  be  dependent  in  a  very  high  degree  on  tem- 
perature, acting  best  at  the  temperature  of  the  body,  or  slightly  above; 
and  it  is  highly  probable  that  the  more  subtle  functions  of  the  leuko- 
cytes may  be  similarly  depressed  by  a  low  temperature.  The  exposure 
of  the  skin  to  cold,  especially  if  the  animal  heat  be  abstracted  more 
quickly  by  evaporation  of  moisture  on  the  surface,  will  lead  to  a  cool- 
ing of  the  blood  wdiich  circulates  through  it,  and  hence  to  a  slight, 
though  appreciable,  cooling  of  the  whole  blood.  This,  it  is  true,  is 
soon  compensated  for,  and  no  great  amount  of  cooling  of  the  whole  body 
occurs;  but,  even  so,  it  is  quite  possible  that  the  periodical  chilling  of 
the  leukocytes  during  their  repeated  passages  through  the  cold  skin 
may  be  sufficient  to  diminish  greatly  their  functional  activity,  and  to 
lower  the  resistance  to  a  point  at  which  infection  may  occur,  and  when 
once  pathogenic  bacteria  have  gained  a  foothold  the  resistance  will  for 
a  time  tend  to  decrease.  There  is  also  some  evidence  going  to  show 
that  exposure  to  cold  may  lessen  the  production  of  the  defensive  sub- 
stances which  occur  in  the  blood  (alexin,  antibodies,  etc.),  though  this 
is  not  fully  proved.  It  is  worthy  of  note  that  the  loss  of  immunity  due 
to  the  action  of  cold  and  wet  on  one  part  of  the  body  (such  as  the 
feet)  is  a  general  one,  and  may  result  in  a  nasal  catarrh,  an  attack  of 
pneumonia,  acute  rheumatism,  etc.,  according  to  the  nature  of  the  in- 
fection at  hand.  It  is  not  necessarily  a  local  infection  of  the  chilled 
«  "Immunity  and  Specific  Therapy,"  1909,  p.  9. 


544  IMMUNITY 

region.  This  is  very  well  shown  experimentally.  Fowls  are  immune  to 
anthrax,  but  are  rendered  susceptible  if  they  are  kept  for  some  time 
standing  in  cold  water;  and  this  acquired  susceptibility  is  then  a  gen- 
eral one,  and  not  merely  of  the  feet. 

"Cold  and  wet,  as  is  well  known,  have  less  action  when  accompanied 
by  energetic  muscular  exercise,  so  long  as  this  does  not  reach  the  extent 
of  undue  fatigue.  This  is  not  because  less  heat  is  lost  during  exercise. 
The  reverse  is  the  case.  The  suggested  explanation  is  that  the  muscular 
metabolism  leads  to  an  increased  production  of  heat,  and  at  the  same 
time  the  cutaneous  capillaries  are  dilated  and  the  heart  accelerated,  or 
that  the  circulation  of  blood  through  the  skin  occurs  quickly;  further, 
the  internal  temperature  of  the  body  may  actually  be  raised  several  de- 
grees. The  result  is  that  the  temperature  of  any  given  leukocyte  never 
falls  m.uch  below  normal,  if  at  all,  since  it  comes  from  the  internal 
regions  where  the  temperature  is  raised,  passes  rapidly  through  the  skin, 
and  returns  again  to  the  interior  of  the  body." 

Trench  foot  is  a  good  example  of  lowered  resistance  due  to  the  local 
effects  of  cold  and  wet,  combined  with  muscular  inaction. 

The  effect  of  fatigue,  either  alone  or  in  conjunction  with  cold  and 
wet,  is  also  well  known,  and  is  one  reason  for  the  excessive  mortality 
from  disease  of  armies  in  the  field.  Cerebrospinal  fever  is  a  good  in- 
stance of  the  effect  of  fatigue  and  exposure.  The  war  has  again  taught 
the  lesson  that  to  make  the  soldier  too  rapidly  invites  disaster. 

Further,  fatigue  and  overexertion  involve  the  likelihood  of  inspira- 
tion of  the  secretions  of  the  nose  and  throat  into  the  trachea  and  even 
into  the  bronchi,  causing  inspirational  bronchitis  or  pneumonia.  It  is 
also  assumed  that  the  presence  in  the  blood  of  katabolic  products  of 
muscular  activity  have  an  injurious  action  on  the  cells  of  the  tissues  in 
general  and  on  the  leukocytes  and  antibodies  in  particular.  This  dimi- 
nution of  immunity  after  musciilar  fatigue  is  manifested  in  animals 
as  well  as  in  man.  White  rats  which  have  been  made  to  work  in  a 
revolving  cage  are  more  susceptible  to  anthrax  than  normal  white 
rats,  the  preexisting  immunity  being  broken  down.  There  is  experi- 
mental evidence  suggesting  that  fatigue  diminishes  the  amount  or  the 
activity  of  the  antibodies  in  the  blood ;  thus  there  seems  to  be  reductions 
of  lysins,  antitoxins,  agglutinins,  and  opsonins,  with  a  weakening  of  the 
defensive  powers  of  the  body. 

Insufficient  and  unsuitahle  food  is  a  prime  factor  in  undermining 
vitality  and  lowering  resistance.  The  influence  upon  health  of  food 
poor  in  quality  or  lacking  in  quantity  is  a  matter  of  common  experi- 
ence, but  the  scientific  explanation  of  the  way  in  which  this  result  is 
brought  about  is  not  at  all  clear.  First  of  all,  it  must  be  remembered 
that  starvation  or  improper  food  does  not  depress  immunity  to  all 
infections,  but  lowers  resistance  only  to  certain  infections.     It  was  for- 


BACTERIAL  VACCINES  545 

inerly  supposed  that  famine  was  the  direct  cause  of  pestilence.  In 
fact,  in  India  it  has  cominouly  Ijeen  stated  tliat  "plague  follows  famine 
with  some  regularity/'  but  we  know  now  that  plague  in  man  is  second- 
ary to  the  disease  in  rats  and  is  transmitted  through  the  flea.  Relaps- 
ing fever  was  formerly  called  famine  fever,  and  outbreaks  of  typhus 
fever  were  frequently  connected  with  famine,  but  we  know  now  that  the 
former  is  transmitted  by  the  tick  and  the  latter  by  the  louse.  It  is 
evident  that  famine  may  be  indirectly  a  cause  of  epidemic  outbursts 
without  necessarily  depressing  immunity,  for  it  is  accompanied  by  misery 
and  squalor  and  an  increase  of  vermin  and  other  factors  that  favor  the 
transmission  of  disease. 

Tuberculosis,  of  all  diseases,  is  favored  by  insufficient  and  unsuit- 
able food.  This  is  an  infection  in  which  poor  nourishment  lowers,  and 
good  nourishment  raises,  our  resistance.  Poor  and  insufficient  food, 
however,  is  usually  associated  with  poverty,  insufficient  clothing,  un- 
cleanly habits,  vitiated  atmosphere,  overwork,  insufficient  rest,  and  other 
depressing  influences,  so  that  it  is  difficult  to  assign  relative  importance 
to  any  one  of  these  factors.  For  this  reason  we  may  perhaps  be  led  to 
exaggerate  its  importance;  and,  while  it  is,  of  course,  true  that  semi- 
starvation,  in  common  with  other  weakening  influences,  does  pave  the 
way  for  infective  processes,  we  do  not  find  that  a  supply  of  food  restricted 
enough  to  cause  a  marked  reduction  of  the  bodily  strength  and  some 
degree  of  anemia  is  necessarily  associated  with  any  infectious  disease, 
though  the  patient  may  live  under  conditions  in  which  infective  material 
is  present  in  abundance.  This  is  well  seen  in  fasting  men,  in  hysterical 
anorexia,  and  in  patients  with  impermeable  esophageal  strictures.  The 
blood,  it  may  be  pointed  out,  is  not  one  of  the  tissues  that  suffers  first  in 
starvation,  and  its  importance  to  the  body  in  many  ways  is  so  great  that 
it  is  kept  in  good  functional  activity  while  other  tissues  waste  quickly. 
Unbalanced  diets  lead  directly  to  beriberi  and  pellagra,  and  are  associated 
with  scurvy,  rickets,  and  other  disorders  of  nutrition  (pages  674-67G). 
The  importance  of  a  well  balanced  and  generous  diet,  especially  for  grow- 
ing children,  cannot  be  overestimated. 

There  is  a  general  belief  that  exposure  to  infection  is  less  dangerous 
after  a  meal  than  upon  an  empty  stomach.  There  is  little  ground  for 
this  belief,  unless  we  take  into  consideration  the  notable  increase  in  the 
number  of  leukocytes  in  the  peripheral  blood  during  active  digestion. 
It  was  recognized  long  ago  that  wounds  inflicted  during  autopsies  are 
much  more  dangerous  when  received  while  fasting  than  during  the 
process  of  digestion,  and  it  is  possible  that  this  may  be  due  to  some 
extent  to  the  increased  number  of  leukocytes  which  occur  in  the  periph- 
eral blood  during  digestion.  Further,  infection  reaching  an  empty 
stomach  has  greater  chances  of  passing  into  the  small  intestines  than 
if  it  reaches  the  stomach  after  a  full  meal  when  acidity,  time,  and  tht 


546  IMMUNITY 

digestive  enzymes  have  a  chance  to  destroy  the  microorganisms.  This 
may  be  of  importance  in  cholera,  typhoid,  dysentery,  and  other  intestinal 
infections. 

Exposure  to  a  vitiated  atmosphere,  if  of  long  duration,  is  one  of 
the  potent  causes  of  breaking  down  resistance.  Here  again,  however, 
immunity  is  lowered  in  a  special  and  not  in  a  general  sense.  Thus, 
vitiated  air  renders  the  individual  more  susceptible  to  tuberculosis, 
pneumonia,  common  colds,  and  other  acute  respiratory  affections.  On 
the  other  hand,  it  has  little  influence  in  determining  the  infection  of 
most  of  the  communicable  diseases,  although  the  lowered  tone  of  the 
body  caused  by  vitiated  air  may  influence  the  severity  of  the  attack. 
The  mechanism  by  which  vitiated  air  increases  susceptibility  is  not 
understood.     The  subject  is  discussed  in  Chapter  IV  upon  Air. 

Excesses  of  all  kinds,  symbolized  by  Bacchus,  Venus,  and  Vulcan, 
are  mighty  factors  in  lowering  vitality  and  in  increasing  susceptibility 
to  certain  diseases.  In  this  category  are  also  found  worry,  overwork, 
loss  of  sleep,  and  fatigue. 

Certain  drugs,  of  which  the  most  important  is  alcohol,  have  an  im- 
portant action  in  lowering  resistance.  Emery  states:  "The  liability 
of  alcoholic  subjects  to  pneumonia  and  some  other  infective  diseases  is 
well  known,  and  in  them  the  prognosis  is  more  than  usually  unfavorable. 
We  have  but  little  knowledge  of  the  action  of  alcohol  in  this  respect. 
It  may  be  that  it  acts  as  a  direct  inhibitant  of  the  activity  of  the 
leukocytes,  and  it  is  known  to  destroy  certain  delicate  defensive  sub- 
stances (alexins  and  opsonins)  which  play  some  part  in  the  defense  of 
the  body  against  microbie  invasion,  but  it  is  not  known  whether  these 
effects  are  actually  manifested  in  the  circulating  blood.  It  is  also  pos- 
sible that  alcohol  tends  to  inhibit  the  formation  of  these  defensive  sub- 
stances. 

"Alcohol  tends  to  lower  the  temperature  of  the  body  by  increasing 
the  amount  of  heat  lost.  It  dilates  the  superficial  vessels  and  accelerates 
the  heart  action  in  a  way  somewhat  similar  to  muscular  exercise,  but 
does  not,  like  it,  raise  the  temperature  of  the  interior  of  the  body. 
Hence  the  effect  of  alcohol  in  conjunction  with  cold  and  wet  is  to  in- 
crease their  ill  effects.  More  blood  is  forced  through  the  chilled  skin 
and  more  heat  is  lost.  The  injurious  effect  of  alcohol  during  exposure 
to  cold  is  well  known." 

Relation  between  Host  and  Parasite. — Infectious  disease  is  not  an 
entity,  but  a  reaction  resulting  from  the  struggle  between  host  and  para- 
site. The  story  of  the  infectious  diseases  is  that  of  a  conflict  between 
these  two  beings.  In  one  sense  this  conflict,  though  less  obvious,  is  not 
essentially  different  from  the  conflict  between  a  rattlesnake  and  his  prey. 
The  battle  between  host  and  parasite  results  in  a  reaction  in  the  host,  and 
this  reaction  we  call  the  disease.     The  various  elements  which  make  up 


BACTERIAL  VACCINES  547 

this  conflict,  such  as  the  mode  of  attack  of  the  parasite  and  the  means  of 
defense  of  the  host,  arc  being  carefully  studied.  An  active  defense  on 
the  part  of  the  host  will  sharpen  the  claws  of  the  parasite  in  accordance 
with  the  laws  of  the  sur\  i\al  of  the  fittest,  and  thus  increase  the  reaction, 
i.  e.,  the  intensity,  of  the  disease.  If  the  parasite  is  unduly  aggressive 
and  virulent,  and  thus  kills  its  host  too  quickly,  it  defeats  its  own  object, 
for  the  parasite  is  in  the  position  of  the  rats  on  a  ship.  It  serves  small 
purpose  to  scuttle  the  ship  unless  there  is  some  means  of  passing  to  an- 
other ship.  The  mode  of  transference  of  the  parasite  is,  therefore,  of 
vital  importance  to  the  parasite,  and  of  great  practical  concern  to  the 
host.  The  infectious  diseases,  then,  represent  only  one  phase  in  a  com- 
plex series  of  events  in  which  parasite  and  host  are  interrelated  in  ways 
often  compared  to  seed  and  soil. 

The  invasion  of  the  parasite  and  the  reaction  which  occurs  in  the 
host  may  be  understood  by  comparing  an  individual  with  a  nation. 
A  nation  at  peace  with  the  world  and  in  a  state  of  healthy  progress, 
corresponds  to  an  individual  in  health.  Suppose  our  nation  is  visited 
by  an  alien  people,  say  the  inhabitants  of  Mars,  whom  we  will  take  to 
represent  the  parasite.  They  come  few  in  numbers,  are  looked  upon 
askance,  but,  being  an  unknown  factor,  no  special  measures  are  taken 
against  them;  meanwhile  they  grow  and  multiply.  This  is  the  period 
of  incubation.  In  time  they  become  numerous  enough  to  threaten  our 
homes  and  happiness.  Then  there  is  an  uprising  or  warfare.  The 
disease  begins,  it  is  a  fight  for  who  shall  have  possession  of  the  land, 
that  is,  the  host.  If  our  enemies  conquer,  the  disease  has  had  a  fatal 
termination,  but  if  we  conquer,  and  kill  or  drive  off  our  enemies,  com- 
plete recovery  takes  place.  If  a  few  of  the  enemy  remain,  we  are  in 
the  condition  of  a  bacillus  carrier,  subject  not  only  to  reinfecting  our- 
selves, but  endangering  the  peace  and  safety  of  the  neighboring  nations. 
After  the  battle  has  been  fought  and  won  it  leaves  us  immune,  in  other 
terms,  educated,  for  if  this  same  strange  race  should  again  come  to  our 
shores  they  would  at  once  be  met  wdth  an  immediate  reaction  and  not 
allowed  to  enter  our  body  politic. 

Ehrlich's  Side-chain  Theory  of  Immunity. — Ehrlich's  ^^  side-chain 
theory  is  a  chemical  conception  of  some  of  the  phenomena  concerned  in 
immunity.  In  one  sense  it  has  been  likened  to  Weigert's  teachings  of  in- 
flammation and  the  process  of  repair  in  so  far  that  cognizance  is  taken 
of  nature's  prodigality.  For  instance,  a  much  larger  amount  of  ma- 
terial is  thrown  out  than  necessary  to  repair  a  wound.     So,  too,  in  an- 

"Ehrlich:  "Die  Wertbemessung  des  Diphtherieheilserums  und  deren  theo- 
retische  Grundlagen."     Klin.  Jahrb.,  Jena,  VI    (2),  1897,  pp.  299-326. 

"Ueber  die  Constitution  des  Diphtheriegiftes."  Deut.  med.  Woch.,  Leip- 
zig, XXIV   (38),  1898,  pp.  597-600. 

Croonian  lecture.     "On  Immunity  with  Special  Reference  to  Cell  Life." 

Proc.  Roy.  Soc,  London,  LXVI,  pp.  424-448,  pis.  6-7. 


548  IMMUNITY 

titoxic  immunity  a  much  larger  amount  of  antitoxin  is  produced  than 
necessary  to'  neutralize  the  toxin. 

In  Ehrlich's  conception  the  fundamental  processes  of  immunity  re- 
side in  the  cells  of  the  body.  These  cells  are  attacked  by  the  poison, 
and  if  not  destroyed  are  stimulated  to  an  overproduction  of  "anti- 
bodies" capable  of  combining  with  and  neutralizing  the  poison. 

Just  what  cells  of  the  body  play  the  most  important  role  in  the 
production  of  this  form  of  immunity  is  not  exactly  clear.  It  may  be, 
as  Ehrlich  supposes,  that  this  power  resides  in  any  organ  or  tissue. 

According  to  Ehrlich,  the  hungry  protoplasm  of  any  cell,  with  its 
complicated  molecule,  having  side  chains  of  various  combining  affinities 
ready  to  unite  with  suitable  food  molecules  brought  to  it  by  the  blood 
and  body  juices,  lies  at  the  foundation  of  his  explanation  of  the  chemical 
production  of  the  antitoxin.  It  is  strange  that  the  same  combining 
affinity  should  exist  between  the  protoplasm  of  the  cell  and  the  proteid 
molecules  that  furnish  it  food,  as  between  the  cell  protoplasm  and  the 
toxins  of  the  bacterial  poison. 

In  considering  Ehrlich's  ^^  side-chain  theory  it  is  necessary  to  disre- 
gard the  microscopic  structure  of  the  cell  and  to  think  of  the  protoplasm 
as  consisting  of  living  molecules  of  extraordinary  chemical  complexity. 
The  molecule  of  protoplasm  has  a  central  "nucleus"  with  "  side  chains," 
"lateral  chains,"  or  "bonds"  of  varying  combining  capacities.  These 
"side  chains"  serve  to  bind  the  molecule  to  other  molecules  having  proper 
combining  affinities. 

This  arrangement  of  molecules  with  side  chains  is  a  well-known 
occurrence  in  organic  compounds.  The  benzol  ring  forms  one  of  the 
best  and  simplest  examples. 


H 
C 

HC         CH 
HC         CH 

v/ 

C 

H 

Benzol 

C^He 

(OH) 
C 

/\ 
HC         CH 

III 

(OH) 
C 

/\ 
HC         C  (OH) 

HC         C  (OH) 

C 

H 
Pvrogallic  acid 
■'CeH3  (OH) 3 

HC         C  (CH3) 

\/ 
C 
H 
jNIetacresol 
CeH,  (CH3)    (OH) 

By  replacing  one  of  the  H  atoms  in  the  benzol  ring  with  the  methyl 

radical   (CII3)   we  have  toluol;  by  replacing  one  of  the  H  atoms  with 

the  hydroxyl  group  (OH)  we  have  phenol;  by  substituting  two  hydroxy! 

groups  we  have  resorcin;  three,  pyrogallic  acid,  etc.;  by  substituting  one 

hydrogen   atom   of   the   ring   with   the   hydroxyl   radical    and   another 

one  with  the  methyl  radical  we  have  the  cresols. 

"  Ehrlich :      "Die  Wertbemessung  des  Diphtherieheilserums  und  deren  theo- 
retische  Grundlagen,"  Klin.  Jahrb.,  Jena,  VI    (2),  1897,  pp.  299-326. 


BACTERIAL  VACCINES 


549 


5 


Fia. 


i. — Till-:  CKf.L 
vvriii  Its  Various 
Combining 
Groups  or  Side 
Chains,  Known 
AS  Receptors.  Va- 
rious toxins  are 
shown  liaving  spe- 
cific affinity  for  the 
proper  shaped  re- 
ceptors. 


^roup 


<yroup 
! 


These  simple  illustrations  from  wdl-kiiDWii  orirtiDic  compdUTnls  illus- 
trate   the    central    molecular    mass    witli    ils    side 
chains    and     coml)iiiin<^    aninitics.    to     which     lh( 
'■moU't'uk'""  of  ])roto|)lasni  is  likened. 

In  applying-  this  analogy  to  the  nKdecule  of  \, 
jtrotoplasm  the  name  "receptor"  is  given  these  side 
chains,  or  secondary  atomic  complexes  of  the  mole- 
cular group.  Contrary  to  the  simple  analogies 
above  given,  each  molecule  of  protoplasm  has 
many  different  kinds  of  receptors,  as  shown  by  the 
schematic  diagram  in  Fig.  52.  These  receptors 
have  a  specific  atfinity  for  the  molecules  of  food, 
and  also  combine  with  the  toxic  molecules. 

The  toxin  molecule,  according  to  Ehrlich,  con- 
sists of  two  important  parts.  One  is  known  as 
the  toxophore  group,  the  other  as  the  haptophore 
group.     This  conception  is  theoretical. 

The  toxophore  group  of  the  toxin  is 
Tonophove  f^i^Q^f^  portion   of  the   molecule   which  ex- 
erts a   poisonous   effect   upon   the   proto- 
plasm  of   the   cell.      This   group    is    less 
stable  than  the  haptophore  group. 

The  haptophore  group   is  the  seizing 
or  combining  portion  of  the  toxin,  mole- 
cule   (ixTreLv,  to    Seize    or    attack).      The 
Fig.  53. — The  Toxin  Molecule -,     ,       ,      ,  p     ,i         ,      •         , 

Showing     the    Haptophore     haptophore     group     of    the     toxins    have 

(Combining)    Group,  and     specific    combining   aifinities    for    the    re- 
the    Toxophore     (Poison)  .  „  .    .  „  ,  .  ,      . 

Group.  ceptors    oi    certain    cells,    which   m    part 

explains    the    selective    action    of    these 

poisons. 

Toxines  such  as  diphtheria  toxine  gradually 
diminish  in  toxicity,  but  retain  the  same  power 
of  chemical  combination  with  the  antitoxin. 
This  phenomenon  explains  the  formation  of 
toxoids. 

Ehrlich  inferred  the  presence  of  the  toxoid 
from  the  following  simple  experiment:  He  had 
a  toxine  which  required  0.003  c.  c.  to  kill  a 
guinea-pig.  After  nine  months  this  poison 
weakened,  so  that  it  required  three  times  as 
much,  that  is,  0.009   c.   c,  to   kill  a  guinea-pig. 

Nevertheless,  the  combining  power  of  the  toxine  for  antitoxin  remained 
the  same. 

Toxoids  are  altered  toxins.     They  consist  of  the  toxic  molecule  in 


Fig.  54.— The  First 
Stage  of  .Anti- 
toxin Formation  : 
A  Toxin  Molecule 
Anchored  to  a  Re- 
ceptor. 


550 


IMMUKITT 


Fig.  55. — The  Second 
Stage:  Continued 
Stimulation  Causes 
A  Reproduction  o  f 
Receptobs. 


which  the  toxophore  group  has  been  weakened,  leaving  intact  the  hapto- 

phore  or  combining  group,  which,  while  able  to  satisfy  the  combining 

affinities  of  the  antitoxin,  is  no  longer  as  poisonous  to  the  protoplasm  of 

the  cell. 

The  diphtheria  bacillus,  during  the  process  of  its  growth  and  multi- 
plication in  the  body  or  in  an  artificial  culture  medium,  produces  several 
poisons,  one  of  which  is  known  as  diphtheria 
toxin  As  above  stated,  the  diphtheria  toxin 
consists  of  a  toxophore  and  haptophore  group. 
In  the  body  the  latter  unites  chemically  with 
the  receptors  of  the  cells.  When  this  takes 
place  one  or  two  consequences  may  result: 
either  (1)  the  cell  is  so  severely  poisoned  that 
it  dies,  or  (2)  the  living  molecule  of  proto- 
plasm is  stimulated  so  as  to  excite  a 'defensive 
action  by  the  reproduction  of  its  receptors. 
Continued  stimulation  produced  by  the  peri- 
odical injection  of  toxine  results  in  an  over- 
production of  receptors,  which  finally  loosen 
and   float   free    in   the   blood   serum   and   body 

juices.     Eeceptors   fixed   upon   the   cells   are   called   sessile,   and  those 

that  leave  the  cell  are  spoken  of  as  free  receptors. 

Antitoxin  consists  of  these  free  receptors  floating  in  the  blood  serum. 

If  we  now  introduce  toxin  into  the  blood,  it  is  immediately  neutralized 

by   combining  with  the  free  receptors  through  its  haptophore  group. 

All  the  combining  affinities  of  the  toxin  are  thus  satisfied  or  saturated,  so 

that  the  toxin  is  no  longer  able  to  unite  with 

the  receptors  still  attached  to  the  cell,  and  the 

poison  is  thus  rendered  harmless. 

It  is  by  no  means  a  necessary  corollary  of 

the  side-chain  theory,  as  is  often  supposed,  that 

the  receptors   are   found   only   in   those   organs 

upon   which   the    poisonous    effects    of    a    toxin 

are   particularly  manifested.      On  the  contrary, 

Ehrlich    and     Morgenroth  ^^     beheve    that    re- 
ceptors   capable    of    combining    with    the    toxin 

are   produced   in   many    different   parts    of   the 

body,   especially   in   tissues   and   organs   having 

the  power  of  anchoring  the  toxin  without  producing  serious  poisonous 

effects. 

The  connective  tissue  is  believed  to  be  specially  rich  in  receptors,  evi- 

"  Ehrlich,  P.,  and  Morgenroth,  J.:  Wirkung  und  Entstehung  der  aktiven 
Stoffe  im  Serum  nach  der  Seitenkettentheorie.  Handbuch  der  pathogenen 
Mikroorganismen,  W.  Kolle,  and  A.  Wassermann,  Jena,  1904. 


Fig.  56. — Third  Stage: 
THE  Receptors  B  e  - 
GINNING  TO  Leave 
THE    Cell. 


BACTERIAL  VACCINES 


551 


Fig.  57. — Fourth  Stage  : 
THE  Receptors  Have 
Left  the  Cell  axd 
Float  Free  ix  the 
Blood — Axtitoxin. 


\'iK 


dencecl  by  the  local  reaction  caused  by  the  subcutaneous  inoculation  of 
diphtheria  toxine,  ricin,  abrin,  and  similar 
poisons.  In  fact,  one  would  not  be  far  wrong 
in  assigning  a  particular  significance,  in  the 
production  of  receptors,  to  just  those  organs 
which  show  unimportant  vital  response,  be- 
cause in  such  tissues  the  injurious  effects  of 
the  toxophore  group  are  absent  or  of  such 
diminished  importance  that  the  regenerative 
powers  of  such  tissues  are  not  retarded. 

The  presence  or  absence  of  receptors  cap- 
able of  binding  the  toxine,  as  well  as  their 
number    and    distribution,    are    factors    which 

determine  the  susc-eptibility  of  different  species 
of  animals  to  the  various  toxines.  These  fact- 
ors also  determine  the  individual  variations  in 
the  susceptibility  to  poisons  and  further  ex- 
plain some  instances  of  natural  immunity  to 
toxins. 

An  example  is  given  by  Sachs,^^  who  stud- 
ied the  reaction  of  guinea-pig  blood  against 
arachnolysin,  a  toxin  found  in  spiders.  In 
this  case  the  complete  immunity  of  the  red 
A>-titoxix:.  the  Free  blood  cells  of  the  guinea-pig  against  arachnoly- 
Receptors  IX  the  gjj^  -^g  accounted  for  by  the  entire  absence  of 
Blood   Have   Lxited  "^  i  -i  ,  -i- 

WITH  the  ToxTx — An-  the    proper    receptors,    while    the    susceptibility 
TiToxiclMiiux-iTT.       ^f   ^j^g   ^cd   blood   cells   of   the   rabbit   to    very 
small  quantities  of  this  poison  is  accounted  for 
by   the   strong   combining   affinity    which    exists   between 
these  cells  of  the  rabbit  and  the   arachnolysin. 

The  union  between  the  receptor  of  the  cell  and  its 
poison  is  not  always  a  direct  one,  as  described  above, 
but  sometimes  takes  place  through  the  intervention  of 
an  intermediary  body,  kno"UTi  variously  as  the  ambo- 
ceptor, Zmschenkorper,  immune  body,  sensitizer,  fix- 
ative, preparative,  desmon,  etc. 

This  second  order  of  immunity  is  particularly 
evident  in  the  poisons  that  have  a  lytic  or  dissolving 
action  upon  bacteria  or  the  cells  of  the  body, 
such  as  the  bacteriolysins,  hemolysins,  and  other 
cytolysins.  The  poisonous  bodies  in  this  order  of 
immunity  are  usually  spoken  of  as  "complement," 
but  also  as  the  "alexin"  (Buchner)  or  "cytase"  (Metchnikoff) 
"Sachs,  Hans:     "Hofmeister'g  Beitr.."  Bd.  2,  H.  1-3. 


Fig.  58. — The  Xeuteal- 
izattox  of  a  Toxix  by 


*tJiLi';:'S--M? 


F  I  G  . .  5  9  .— 
Showing 
C  0  mple- 

ilEXT    AXD 
I  M  ilUNE 

Body. 


652  IMMUNITY 

It  became  necessary  for  Ehrlich  to  modify  and  extend  his  theory  in 
order  to  explain  phases  of  antibody-antigen  reactions  other  than  the 
simple  toxin-anti(oxin  combination.^"  For  this  purpose,  Ehrlich  con- 
ceived three  main  varieties  or  "orders"  of  receptors.  Of  these  the 
simplest  are  those  of  the  frst  order,  which  attach  to  the  toxins  and  by 
over-regeneration  appear  in  the  blood  stream  as  antitoxins.  Those  of  the 
second  order,  adapted  to  the  assimilation  of  more  formidable  protein 
molecules,  are  of  necessity  of  greater  structural  complexity  and  appear 
in  immunized  animals  as  the  agglutinins  and  precipitins.  Those  of  the 
third  order  are  dependent  upon  the  cooperation  of  complement  for 
proper  functioning  and  appear  as  the  cytotoxins  or  lysins. 

One  of  the  remarkable  facts  connected  with  the  phenomena  of  the 
lytic  poisons  is  that  the  poison  itself  (the  complement)  is  normally  pres- 
ent in  the  blood.  Complement  is  thermolabile,  that  is,  it  has  less  resist- 
ance to  heat  than  the  intermediary  body,  which  is  thermostabile.^  Accord- 
ing to  Ehrlich's  theory,  immunity  can  only  be 
obtained  by  means  of  the  intermediary  body, 
which  is  believed  to  be  specific. 

Ehrlich  compares  tlie  intermediary  body  with 
diazobenzaldehyd,  which  by  means  of  its  diazo 
group  is  capable  of  combining  with  a  series  of 
bodies,  such  as  aromatic  amins,  phenols,  keto- 
methyl  bodies,  etc.,  while  by  means  of  its  aldehyd 
group  it  may  combine  with  a  different  series, 
such  as  the  hydrazins,  ammonia  radicals,  and 
Fig.   60.  —  Showing     hydrocyanic   acid.      Phenol   and   hydrocyanic   acid 

AN  Immune  Body     ^^]j  ^^^  directly   combine,   but,   with   diazobenzal- 

Having    Two    Af-  -^ 

FiNiTiES.  dehyd  acting  as  an  mtermediary  body,  these  two 

substances     can     be     brought     into     combination. 

Pushing  this  comparison  further,  we  may  say  that  the  aromatic  body, 

or    the    phenol,    represents    a    constituent    of    the    blood    corpuscle. 

The   diazobenzaldehyd  is  the   intermediary  body,   while   the   poisonous 

hydrocyanic  acid  constitutes  the  complement.^^ 

Welch  ^^  very  ingeniously  extended  Ehrlich's  conception  of  immunity 
to  the  bacterial  cell.  According  to  Welch's  views,  the  bacterial  cell  has 
the  same  power  of  defensive  action  against  the  poisons  produced  by  the 
cells  of  higher  animals  that  they  have  against  the  toxic  products  of  the 
bacteria.  This  chemical  conception  of  immunity  has  been  helpful,  but 
doubtless  it  is  not  the  final  explanation,  for  we  now  think  of  the  mechan- 
ism of  immunity  more  in  terms  of  physical  states  of  a  colloidal  nature. 

^  For  every  phenomenon  it  has  been  necessary  for  Ehrlich  to  invent  a  phe- 
nomenine. 

^Vaughan  and  Novy:     "Cellular  Toxins,"  1902,  p.  131. 

^^  Welch,  William  H. :  "Huxley  lecture  on  recent  studies  of  immunity  with 
special  reference  for  their  bearing  on  pathology."  Bull.  Johns  Hopkins  Hasp., 
Baltimore,  XIII   (141),  Dec,  1902,  pp.  285-299. 


TOXINS  553 

In  other  words,  there  is  a  cheniital  battle.  Both  the  bacterial  cell 
and  the  body  cell  excrete  poisonous  substances  against  each  other,  and 
both  in  turn  are  building  uj)  a  chemical  defense  against  the  action  of 
these  respective  })oisons. 

Antitoxic  Immunity. — In  order  to  understand  antitoxic  immunity 
it  is  necessary  to  consider  the  nature  and  action  of  toxins,  the  forma- 
tion and  production  of  antitoxins,  and  the  reaction  between  toxins  and 
antitoxins. 

TOXINS 

Bacteria  produce  many  different  kinds  of  poisonous  substances,  but 
not  all  of  these  are  toxins  in  the  specific  sense  in  which  that  term  is 
now  used.  A  toxin  may  be  defined  as  a  specific  poison  elaborated  by 
bacterial  metabolism;  it  is  soluble  in  water;  poisonous  in  minute 
amounts;  reproduces  the  essential  symptoms  and  lesions  of  the  disease; 
acts  only  after  a  period  of  incubation ;  and  produces  antibodies,  namely, 
antitoxin.  The  toxins  are  thermolabile,  unstable,  and  have  a  complex 
chemical  structure. 

Toxins  are  known  only  by  their  effects  upon  animals;  they  cannot 
be  recognized  in  any  other  way.  Presumably  they  belong  to  the  higher 
proteins,  but  nothing  definite  can  be  stated  concerning  their  chemical 
structure.  They  have  never  been  isolated  in  pure  form;  they  are  not 
toxalbumins,  as  was  once  believed,  and  they  only  have  a  remote  analog}' 
to  the  enzymes.  Toxins  may  be  globulins,  at  least  they  come  down 
in  the  globulin  fraction.  They  may  readily  be  precipitated  with  am- 
monium sulphate,  for  example,  but  whether  they  are  mechanically  car- 
ried down  in  the  precipitate  is  not  known.  The  toxin  molecule  is  at 
least  small  enough  to  pass  readily  through  the  pores  of  the  finest  porce- 
lain filter,  and  large  enough  not  to  dialyze  through  a  membrane. 

There  are  three  well-known  toxins :  diphtheria,  tetanus,  and  botu- 
linus.  Toxins  are  also  produced  by  B.  perfringens  (Welchie)  and  other 
anaerobes.  A  number  of  bacteria,  such  as  cholera,  dysentery,  pyocyaneus, 
and  others,  produce  a  certain  amount  of  toxic  substances  soluble  in 
water,  but  it  is  very  doubtful  whether  they  are  true  toxins  in  accord- 
ance with  the  above  definition.  Bacteria  produce  many  poisonous  sub- 
stances other  than  the  true  toxins,  such  as  acids,  alkalies,  nitrites,  fer- 
ments, alcohol,  hydrogen  sulphid,  etc.  Some  of  these  substances  may 
play  a  part  in  the  pathogenesis  of  disease. 

Some  organisms  produce  both  endo-  and  exo-toxins;  thus,  two  toxic 
substances  have  been  demonstrated  by  Olitzky  and  Kligler  ^^  in  filtrates 
of  the  dysentery  bacillus;  (1)  an  exotoxin,  which  acts  especially  upon 
the  nerves  and  is  therefore  called  a  neurotoxin;  (2)  another,  which  is 
probably  an  endotoxin,  acts  upon  the  intestinal  tract  and  is  therefore  an 

»JoMrn.  Exp.  Med.,  Jan.  1,  1920,  XXXI,  1,  pp.  19-33. 


554  IMMUNITY 

enterotoxin.  Toxins  are  sometimes  divided  into  exotoxins  and  endotox- 
ins. The  former  are  the  true  or  soluble  toxins;  the  latter  are  insoluble 
under  ordinary  circumstances,  and  differ  markedly  from  the  true  exo- 
toxins.    The  endotoxins  will  be  considered  separately. 

The  tubercle  bacillus,  the  bacillus  of  glanders,  and  other  micro- 
organisms produce  soluble  toxic  substances  specific  in  nature  but  quite 
different  from  the  true  toxins,  in  that  they  are  harmless  to  a  normal 
animal,  but  poisonous  to  one  suffering  with  the  specific  disease.  Tuber- 
culin, mallein,  and  similar  so-called  "toxins"  are  very  stable,  resist  heat 
and  other  influences,  do  not  produce  the  specific  lesions  and  symptoms 
of  the  disease,  and  do  not  stimulate  antitoxin  formation.  They  are  not 
toxins. 

A  toxin  is  produced  as  a  result  of  bacterial  metabolism,  but  whether 
it  is  a  secretion,  an  excretion,  or  a  product  of  the  action  of  the  bacteria 
upon  the  medium  (as  alcohol  and  carbon  dioxid  are  produced  by 
yeasts)  is  not  known.  It  is  known,  however,  that  toxins  do  not  result 
simply  from  the  breaking  down  of  the  dead  bacterial  cells,  as  was  once 
stated. 

It  is  now  evident  that  different  groups  of  bacteria  produce  poisons 
that  differ  essentially  in  chemical  structure  as  well  as  in  physiological 
action,  just  as  different  species  of  higher  plants  produce  various  poisons 
that  differ  markedly  in  composition  and  physiologic  action.  Some  bac- 
teria produce  more  than  one  toxin ;  thus,  diphtheria  bacilli  produce  toxin 
and  toxon;  tetanus  produces  tetanospasmin  and  tetanolysin;  dysentery 
produces  an  enterotoxin  and  a  neurotoxin,  etc. 

Very  few  of  the  bacterial  poisons  are  injurious  when  taken  by  the 
mouth.  Diphtheria  and  tetanus  toxins  are  practically  inert,  being  de- 
stroyed largely  by  the  digestive  juices  and  not  being  absorbed  in  any 
harmful  amount.  Enormous  doses  of  these  toxins  may  be  administered 
by  the  mouth  to  susceptible  animals  without  appreciable  harm.  There 
is  one  notable  exception  in  the  case  of  the  toxin  of  the  Bacillus  iotulinus, 
for  this  poison  is  absorbed  by  the  digestive  mucosa,  and  it  is  in  this  way 
that  it  produces  its  harmful  effects  in  man. 

There  are  several  poisons  produced  by  higher  plants  that  resemble 
the  true  bacterial  toxins  in  all  important  respects.  Among  them  are: 
ricin  from  the  castor  bean,  and  abrin  from  the  jequirity  bean.  These 
toxins  of  vegetable  origin  are  known  as  phytotoxins.  They  are  soluble, 
act  only  after  a  period  of  incubation,  are  exceedingly  poisonous  in  small 
amounts,  are  destroyed  by  heating,  and  produce  specific  antibodies.  They 
are  probably  of  protein  nature,  according  to  Osborne,  Mendel,  and  Harris, 
who  obtained  ricin  in  very  pure  form.  These  poisonous  substances  of 
vegetable  origin  have  more  than  theoretical  interest,  for  it  was  through 
a  study  of  their  action  that  Ehrlich  first  obtained  a  deeper  insight  into 
the  nature  of  toxins  and  antitoxic  immunity. 


TOXINS  555 

There  are  poisons  in  the  animal  kingdom  which  closely  resemble  the 
toxins,  such  as  the  venom  of  snakes,  scorpions,  spiders,  wasps,  etc. 

True  toxins  are  unstable  and  arc  readily  affected  by  heat,  sunlight, 
acids,  and  various  chemicals.  They  are  much  more  unstable  in  solution 
than  in  dry  powdered  form.  Tetanus  toxin  is  more  labile  than  diph- 
theria toxin,  but  when  precipitated  with  ammonium  sulphate  and  pre- 
served as  a  dry  powder  in  a  vacuum  tube,  and  in  a  cool,  dark  place  it 
may  be  kept  without  deterioration  for  several  years.  Diphtheria  toxin, 
in  solution,  weakens  rapidly  at  first,  and  then  comes  to  a  stage  of  equi- 
librium which  it  maintains  indefinitely  if  preserved  in  a  cold,  dark  place 
and  protected  from  the  oxygen  of  the  air. 

The  poisonous  properties  of  toxins  of  diphtheria,  tetanus,  and  botu- 
linus  are  destroyed  at  once  by  boiling,  and  at  75°  C.  in  a  short  time. 
At  60°  C.  for  one  hour  they  lose  most  or  all  toxic  power. 

It  has  been  stated  that  one  of  the  characteristics  of  the  toxins  is 
that  they  are  poisonous  in  exceedingly  small  amounts.  Thus,  .000,000,05 
gram  of  a  partially  purified  tetanus  toxin  will  kill  a  mouse.  Diphtheria 
toxins  have  been  obtained  so  that  .0008  c.  c.  of  the  unconcentrated  fluid 
(crude  filtrate)  will  kill  a  guinea-pig. 

A  true  toxin  reproduces  the  true  symptoms  and  essential  lesions 
of  the  disease.  In  this  sense  they  have  a  specific  action.  The  symptoms 
produced  in  a  susceptible  animal  by  the  inoculation  of  tetanus  toxin 
cannot  be  distinguished  from  the  disease  naturally  contracted.  The 
symptoms  produced  by  the  injection  of  diphtheria  toxin  closely  resemble 
diphtheria,  including  coagulation  necrosis  at  the  site  of  the  injection, 
fever,  depression,  postdiphtheritic  paralysis,  etc.  The  symptoms  follow- 
ing the  ingestion  of  the  toxin  of  the  Bacillus  hotulinus  are  an  exact 
counterpart  of  the  disease.  This  specific  action  is  very  important,  and,  if 
it  were  more  generally  known,  would  save  many  mistakes  in  experimental 
biology  and  its  application  to  serum  therapy.  It  is  comparatively  easy 
to  obtain  useful  antitoxins  from  true  toxins.  On  the  other  hand,  it 
seems  to  be  impossible  to  obtain  antitoxins  of  any  therapeutic  potency 
from  other  bacterial  poisons.  Thus,  tuberculin  and  mallein  and  other 
so-called  '^toxins"  do  not  stimulate  production  of  antitoxin  and  the  sera 
thus  produced  have  no  protective  or  curative  value.  Certain  antigens,  as 
the  pneumococcus  and  meningococcus,  produce  antibodies  with  protective 
properties — but  these  antibodies  are  not  antitoxins.  It  must  not  be  for- 
gotten that  the  lesions  and  symptoms  of  but  a  few  infections  depend 
upon  true  toxins  and  may  be  prevented  or  cured  by  corresponding  anti- 
toxins. 

One  of  the  characteristics  of  the  true  toxins  is  that  they  act  only 
after  a  period  of  incubation.  In  this  respect  they  resemble  the  natural 
disease.  Simple  chemical  poisons  may  act  at  once,  but  the  toxins  produce 
no  apparent  effect  until  a  definite  time  elapses  after  they  have  been  intro- 


556  IMMUNITY 

duced  into  the  system — even  when  overpowering  doses  are  administered. 
Thus,  the  ordinary  period  of  incubation  when  tetanus  or  diphtheria  toxin 
is  injected  into  a  susceptible  animal  is  several  days.  When  enormous 
amounts  are  injected  this  may  be  reduced  to  about  8  or  12  hours,  but 
never  less.  In  botulism  the  symptoms  may  appear  in  a  few  hours.  The 
period  of  incubation  is  inversely  proportional  to  the  amount  of  poison 
injected.  The  longer  the  period  of  incubation  the  milder  the  symptoms ; 
when  the  period  of  incubation  is  short  the  result  is  almost  invariably 
fatal.  The  cause  of  the  period  of  incubation  is  not  well  understood.  A 
certain  length  of  time  is  required  for  the  toxin  to  reach  the  susceptible 
cells.  This  varies  especially  in  the  case  of  tetanus,  which  travels  up  the 
nerves.  After  the  poison  reaches  the  cells  further  time  is  required  to 
combine  chemically,  and  then  more  time  to  produce  the  injury.  On 
account  of  the  period  of  incubation  large  amounts  of  toxin  may  be 
present  in  the  circulating  blood  before  the  appearance  of  the  Symptoms. 
Thus,  in  horses  enough  tetanus  toxin  has  been  found  in  the  blood  two 
days  before  the  onset  of  symptoms  to  kill  a  guinea-pig,  when  only  0.1 
c.  c.  of  the  blood  serum  of  the  horse  was  injected  into  the  guinea-pig. 

The  distribution  of  the  toxins  in  the  body  is  unequal.  Most  of  the 
poison  unites  with  the  cells;  some  is  destroyed  and  some  neutralized  if 
antitoxin  is  present.  Most  of  it  probably  unites  with  the  cells,  as  it  soon 
disappears  from  the  blood.  Tetanus  toxin  may  remain  a  long  time  in 
the  blood  of  an  insusceptible  animal.  Thus,  Metchnikoff  could  demon- 
strate the  presence  of  tetanus  toxin  in  the  tortoise  four  months  after 
the  injection.  After  tetanus  toxin  is  injected  it  soon  disappears  from 
the  blood,  but  if  the  tissues  are  injected  into  a  susceptible  animal  tetanus 
is  produced,  for  it  is  now  known  that  this  poison  has  a  specific  affinity 
for  the  motor  nerve  endings.  In  the  case  of  fowls  it  seems  that  this  power 
of  combining  with  the  tetanus  toxin  is  most  marked  in  the  leukocytes. 
Toxins  will  not  combine  with  all  cells  indifferently.  They  have  a  specific 
combining  affinity  for  certain  cells.  Tetanus  toxin  has  a  special  affinity 
for  the  cells  of  the  central  nervous  system.  Diphtheria  toxin  also  acts 
specifically  upon  nervous  structures;  it  is  also  a  general  protoplasmic 
poison.  These  facts  are  of  immense  importance  in  the  prevention  and 
cure  of  certain  infections,  for  a  correct  understanding  of  the  chemical 
relation  between  the  poison  and  the  particular  cell  is  of  the  greatest  fun- 
damental and  practical  value.  A  realization  of  this  fact  has  stimulated 
studies  which  are  now  in  progress  upon  the  relation  between  the  chemi- 
cal constitution  and  the  physiological  action  of  various  substances — 
studies  which  have  already  borne  fruitful  and  useful  results. 

Tetanus  toxin  may  combine  with  certain  cells  without  apparently 
injuring  them.  Diphtheria  toxin  also  combines  with  indifferent  struc- 
tures, such  as  the  connective  tissue.  There  is  evidently  a  wide  difference 
between  the  power  to  combine  and  the  power  to  injure.     The  power  to 


ANTITOXINS  557 

injure,  however,  is  not  always  evident,  as  it  depends  upon  the  importance 
and  extent  of  the  cells  affected.  Thus,  tetanus  toxin  may  comhine  with 
the  leukocytes  in  such  a  way  as  to  prevent  phagocytosis.  This  may  be 
demonstrated  by  injecting  tetanus  spores  washed  free  of  toxin,  in  wliich 
case  the  spores  are  taken  up  by  the  leukocytes  and  their  development  is 
prevented.  If,  however,  a  sliglit  amount  of  toxin  is  injected  with  the 
spores,  the  poison  inhibits  pliagocytosis  and  permits  the  growth  and 
multiplication  of  the  tetanus  microorganisms  and  the  further  production 
of  toxin. 

From  one  standpoint  the  most  important  property  of  a  true  toxin 
is  its  power  to  produce  specific  antitoxins.  This  will  be  given  separate 
consideration. 

Ehrlich  conceives  the  toxin  to  be  a  complex  molecule  containing 
both  a  haptophore  and  a  toxophore  group.  The  haptophore,  or  seizing, 
group  is  that  part  of  the  molecular  structure  which  combines  in  a 
chemical  sense  with  the  antitoxin  or  with  the  receptors  of  the  cell. 
The  toxophore  group  is  the  poisonous  part  of  the  toxin  molecule.  This 
is  usually  represented  diagrammatically.     See  Fig.  53,  page  549. 

It  may  readily  be  demonstrated  by  simple  experiments  that  the 
toxophore  group  is  much  more  unstable  than  the  haptophore  group. 
The  toxin  may  degenerate  so  that  it  has  little  or  no  poisonous  prop- 
erties left;  however,  its  combining  properties  remain  unaltered.  Such 
a  degenerated  toxin  is  known  as  a  toxoid.  A  toxoid,  then,  is  an  altered 
toxin  which  possesses  the  combining  property  of  the  original  toxin,  but 
has  lost  its  poisonous  power.  Some  years  ago  I  proposed  to  draw  a 
distinction  between  the  terms  '^toxine"  and  "toxin."  The  toxine  is  the 
crude  filtered  culture  and  contains  several  poisonous  substances  as  well 
as  other  bodies.  The  toxin  is  the  specific  poison  in  the  toxine.  Thus, 
a  filtered  broth  culture  of  diphtheria  is  known  as  diphtheria  toxine. 
This  filtrate  contains  at  least  two  primary  metabolic  poisons :  toxin  and 
toxon.  The  toxin  produces  the  acute  symptoms  and  death;  the  toxon 
produces  the  late  paralysis.  A  filtered  broth  culture  of  tetanus  is  called 
the  tetanus  toxine.  The  filtrate  contains  at  least  two  primary  metabolic 
poisons :  tetanoplasmin  and  tetanolysin. 


ANTITOXINS 

An  antitoxin  is  an  antibody  formed  in  an  animal  through  the  stimu- 
lation of  a  specific  toxin.  The  usual  method  of  producing  an  antitoxin 
is  by  the  repeated  injections  of  increasing  amounts  of  toxine  into  a  sus- 
ceptible animal.  The  strongest  antitoxins  are  obtained  from  animals 
that  are  very  susceptible  to  the  toxine,  but  all  susceptible  animals  by 
no  means  produce  antitoxins,   although   repeatedly  injected   with   the 


558  IMMUNITY 

appropriate  poison.  Thus,  a  guinea-pig  which  is  very  susceptible  to 
diphtheria  will  not  form  diphtheria  antitoxin,  even  after  the  repeated 
administration  of  diphtheria  toxine.  Guinea-pigs  are  also  exceedingly- 
susceptible  to  tetanus  and  react  characteristically  and  violently  to  tet- 
anus toxine,  but  the  repeated  injections  of  subminimal  lethal  doses  of 
tetanus,  toxine  into  a  guinea-pig  do  not  immunize  that  animal,  nor  do 
they  induce  the  formation  of  antitoxin.  In  fact,  Knorr  and  also  Behring 
and  Kitashima  have  shown  that  guinea-pigs  develop  an  increasing  sensi- 
tiveness to  repeated  injections  of  tetanus  toxine  instead  of  an  increasing 
resistance.  In  other  words,  the  guinea-pig,  a  susceptible  animal,  lacks 
the  mechanism  of  antitoxin  formation  which  is  possessed  in  such  a  high 
degree  by  horses  and  other  animals.  Antitoxin  produced  by  the  horse 
or  other  animal  when  injected  into  the  guinea-pig  will  protect  it. 

On  the  other  hand,  insusceptible  animals,  as  a  rule,  do  not  produce 
antitoxin,  but  there  are  notable  exceptions  to  this  rule.  MetchnikofE 
has  shown  that  the  .  cayman,  an  animal  insusceptible  to  tetanus,  will, 
however,  produce  tetanus  antitoxin 'if  the  animal  is  kept  at  an  elevated 
temperature  (32°  to  37^  C),  but  not  if  kept  cold  (20°  C).  The 
mechanism  of  antitoxin  formation  is  not  understood,  and  the  only 
way  of  determining  whether  a  certain  species  of  animal  is  suitable  or 
not  is  by  experimental  trial.  There  is  a  very  great  difference  in  the 
ability  to  produce  antitoxin  even  among  different  individuals  of  a  suit- 
able species.  Thus,  some  horses  have  this  power  developed  to  such  an 
exquisite  degree  that  they  produce  a  high  grade  of  antitoxin  for  pro- 
longed periods — years.  Other  horses  make  comparatively  weak  antitoxin. 
This  difference  among  horses  is  well  known  to  manufacturers,  who  have 
no  means  of  knowing  beforehand  which  horses  will  be  profitable. 

There  are  several  reasons  for  selecting  the  horse  for  the  production 
of  immune  sera  for  human  use.  On  account  of  its  size  it  furnishes 
large  quantities  of  blood;  the  serum  of  the  horse  is  the  blandest  blood 
serum  of  any  known  species;  finally,  the  horse  furnishes  antitoxin  in 
higher  potency  than  any  other  known  animal. 

Just  how  and  by  what  cells  antitoxins  are  formed  in  the  body  is 
not  known.  They  are  not  formed  directly  from  the  toxines.  In  some 
way  the  toxine  excites  the  cell  to  the  formation  of  the  antibody.  The 
antibody  leaves  the  cell  and  becomes  "dissolved"  in  the  blood  and  tissue 
juices.  Perhaps  the  white  blood  cells  (Metchnikoff),  perhaps  the  con- 
nective tissue  cells  (Ehrlich),  are  chiefly  concerned.  Within  the  body 
most  of  the  antitoxin  is  found  in  the  blood,  but  it  also  exists  in  greater 
or  less  concentration  in  practically  all  the  fluids  of  the  body  and  may 
also  appear  in  the  excretions,  as  the  urine,  saliva,  milk,  and  bile. 

JSTothing  definite  can  be  stated  concerning  the  chemical  nature  of 
antitoxins.  Evidence  strongly  points  to  the  fact  that  they  belong  to 
the  higher  proteins.    In  all  probability  antitoxins  are  globulins,  at  least 


ANTITOXINS  559 

they  come  down  with  tlie  pseudo-glo])iiliii  rraction  from  whioh  they  have 
not  hcen  separated. 

Antitoxins  are  somewhat  more  stahlc  than  tlie  ioxines.  Further, 
the  toxines  liavc  a  nioic  ((Hiiijlex  eonstitution  than  the  antitoxins.  When 
the  toxines  deteriorate  Ihey  change  qualitatively  as  well  as  quantitatively. 
The  antitoxins  have  a  simpler  eonstitution  and  deteriorate  simply  hy  a 
loss  of  power. 

Antitoxins  are  destroyed  hy  heat,  aeids,  and  many  chemieals.  They 
gradually  deteriorate  spontaneously  when  in  solution.  Thus,  Anderson 
has  found  that  the  average  yearly  loss  of  the  potency  of  diphtheria  anti- 
toxin at  room  temperature  is  ahout  20  per  cent.;  at  15°  C.  it  loses 
about  10  per  cent.;  and  at  5°  C.  about  6  per  cent.  There  is  little  difference 
between  the  keeping  qualities  of  untreated  sera  and  concentrated  sera. 
Dried  diphtheria  antitoxin  kept  in  the  dark  at  5°  C.  retains  its  potency 
practically  unimpaired  for  at  least  by^  years.  Antitoxic  sera  should  always 
be  kept  in  a  cool,  dark  place.  While  antitoxin  loses  some  of  its  potency 
with  time,  and  while  recently  tested  sera  of  known  unit  value  are  always 
desirable,  there  is  absolutely  no  reason  why  a  serum,  however  old,  should 
not  be  employed  provided  a  fresh  supply  is  not  at  hand.  It  should  be 
remembered  that  antitoxins  deteriorate  quantitatively  only;  in  other 
words,  an  old  antitoxin  is  quite  as  useful  in  proportion  to  its  unit 
strength  as  a  fresh  serum;  in  fact,  antitoxic  sera  are  frequently  two 
years  old  when  placed  upon  the  market  by  manufacturers. 

Antitoxins  are  strictly  specific;  that  is,  they  neutralize  the  corre- 
sponding toxine  and  have  no  other  apparent  action  within  the  body. 
The  occasional  ill  effects,  such  as  the  serum  sickness,  following  the  injec- 
tion of  antitoxic  sera,  are  due  to  other  substances  (the  proteins  in  the 
serum)  and  not  to  the  antitoxins  themselves.  Tulloch  ^*  on  the  basis  of 
agglutination  tests  has  separated  tetanus  cultures  into  four  types.  For- 
tunately, any  one  of  the  four  antitoxins  will  neutralize  any  or  all  of  the 
four  toxins.  It  is,  however,  advisable  to  prepare  the  antitoxin  with 
the  four  different  types. 

Antitoxins  may  be  injected  subcutaneously,  intravenously,  into  the 
subarachnoid  space,  into  muscle,  into  the  brain  substance,  or  into  any 
of  the  body  cavities.  Antitoxins  are  practically  useless  when  given  by 
the  mouth,  as  very  little  is  absorbed.  Antitoxins  when  injected  into 
an  organism  disappear  rather  quickly.  Some  of  the  antitoxin  is  bound 
to  the  corresponding  toxine,  if  any  is  present,  some  combines  with  the 
cells,  but  the  greater  part  is  eliminated  as  antitoxin  in  the  urine,  bile, 
saliva,  etc.  The  antitoxin  produced  actively  by  the  body  as  a  result  of 
an  attack  of  disease,  or  stimulated  by  the  injection  of  toxine,  is  formed 
continuously  and  confers  an  immunity  for  an  indefinite  period.    Passive 

«Proc.  Eoyal  Soc,  Series  B,  April,  1918. 


560  IMMUNITY 

or  antitoxic  immunity  is,  on  the  other  hand,  transient;  it  cannot  be  de- 
pended upon  for  more  than  ten  days  or  two  weeks. 

Some  persons  have  sufficient  native  antitoxin  in  their  blood  to  pro- 
tect them  against  diphtheria.  This  has  been  demonstrated  through  the 
Schick  reaction  (see  page  201).  In  such  cases  the  antitoxin  is  pro- 
duced naturally  for  long  periods,  often  during  the  life-time  of  the  in- 
dividual. 

When  antitoxic  serum  is  injected  subcutaneously  the  antitoxin  is 
absorbed  slowly.  It  requires  about  48  hours  under  these  circumstances 
for  the  antitoxin  to  appear  in  the  blood  in  maximum  amount.  There- 
fore, when  very  prompt  action  is  desired,  the  antitoxic  serum  may  be 
introduced  directly  into  the  circulation  by  intravenous  injection. 

There  are  a  number  of  antibodies  that  are  either  true  antitoxins 
or  closely  resemble  these  antibodies.  Some  of  these  antibodies  neutralize 
the  true  bacterial  toxines,  others  the  poisons  of  animal  origin,  others 
the  poisons  of  plant  origin,  and  others  neutralize  the  activity  of  fer- 
ments. The  principal  antitoxins,  -according  to  this  classification,  are 
brought  together  as  follows: 

(1)  Bacterial  Antitoxins. — The  three  principal  and  most  potent  bac- 
terial antitoxins  are  those  of  diphtheria,  tetanus,  and  botulinus.  The 
followiug  are  also  considered  to  have  antitoxic  properties:  pyocyaneus, 
symptomatic  anthrax,  antileukocidin  and  antilysin  against  bacterial 
hemolysins. 

(2)  Animal  Antitoxins. — These  antitoxins  are  produced  by  animal 
poisons  belonging  to  the  venoms.  True  antibodies  are  obtained  against 
snake  venom  and  similar  poisons  in  spiders,  eels,  wasps,  scorpions,  fish, 
salamanders,  and  toads. 

(3)  Plant  Antitoxins. — These  are  antiricin,  antiabrin,  antirobin,  and 
anticrotin. 

(4)  Ferment  Antitoxins. — Antibodies  may  be  obtained  against  fer- 
ments, such  as  pepsin,  urease,  rosinase,  steapsin,  trypsin,  fibrin  ferment, 
lactase,  cyranase;  and  antibodies  may  also  be  obtained  against  the  en- 
zymes found  in  bacterial  cultures. 

There  are  comparatively  few  antitoxic  sera  of  practical  use  in  human 
therapy,  just  as  there  are  relatively  few  true  bacterial  toxines.  The 
best  known  antitoxins  are  those  of  diphtheria,  tetanus,  and  botulinus. 
Numerous  other  antitoxic  sera  are  found  upon  the  market  or  have  been 
described,  but  they  are  of  doubtful  value. 

Antitoxins  are  valuable  both  as  curative  and  immunizing  agents. 
Their  preventive  action  depends  upon  the  fact  that  they  meet  the  toxin, 
unite  with  and  neutralize  it,  thus  rendering  it  harmless.  As  already 
stated,  the  antitoxins  remain  in  the  body  a  brief  time  and  their  immuniz- 
ing power,  while  of  a  high  grade,  is  transitory.  They  disappear  in 
about  ten  days  or  two  weeks ;  the  immunity  must,  therefore,  be  renewed 


ANTITOXINS  5G1 

in  special  cases  by  ropcated  injections  of  llic  antiioxin  imtii  Iho  danger  is 
passed.  This  jiliase  of  the  subject  is  coiisidcnMJ  in  nioi'c  detail  under 
the  prevention  of  iliphtheria  and  tetanus.  'J'he  usual  innuunizing  dose 
for  diphtheria  is  1,000  units,  for  tetanus  1,500  units. 

As  a  cnrati\('  au'ent  antitoxin  must  be  administered  early  and  in 
sulliiient  amount  to  insure  success.  It  is  most  important  to  give  the 
antitoxin  early — before  tlie  (hiniage  is  done.  Too  great  emphasis  cannot 
bo  laid  upon  this  i)()int.  After  the  toxin  has  united  with  the  cells  it 
cannot  be  dislodged  by  the  antitoxin.  The  importance  of  giving  anti- 
toxin early  is  well  illustrated  in  the  case  of  diphtheria.  When  moder- 
ate amounts  (3,000  to  10,000  units)  are  injected  on  the  first  day  of  the 
disease  the  mortality  is  practically  nil.  The  mortality  increases  with 
each  hour's  delay. 

The  importance  of  giving  this  sovereign  remedy  early  is  also  illus- 
trated in  the  experiments  of  Eosenau  and  Anderson  "^^  upon  the  influ- 
ence of  antitoxin  upon  postdiphtheritic  paralysis.  It  was  found  that 
one  unit  of  antitoxin,  given  not  less  than  24  hours  after  a  fatal  dose 
of  diphtheria  toxine  in  a  guinea-pig,  greatly  modified  the  postdiph- 
theritic paralysis  and  saved  the  life  of  the  animal,  whereas  4,000  units 
given  48  hours  after  the  infection  did  not  modify  the  paralysis  or  save 
the  life  of  the  animal.  Four  thousand  units  of  antitoxin  is  an  enor- 
mous amount  for  a  guinea-pig  weighing  about  one-half  pound.  Weight 
for  weight,  it  corresponds  to  400,000  units  for  a  50-pound  child.  The 
fact  that  one  unit  of  antitoxin  saves  life  when  administered  timely, 
whereas  enormous  doses  fail  totally  when  delayed,  should  be  sufficient 
to  place  physicians  on  their  guard;  increased  dosage  cannot  atone  for 
delay.  When  cases  are  seen  late  in  the  progress  of  the  disease  it  is 
good  practice  to  give  the  serum  intravenously,  so  as  to  neutralize  the 
toxin  at  once  and  prevent  further  damage.  If  given  subcutaneously, 
further  delay  results  on  account  of  the  time  necessary  for  absorption. 
Tetanus  antitoxin  is  a  very  valuable  immunizing  agent,  but  is  of  less 
value  after  symptoms  have  appeared,  for  then  most  of  the  damage  has 
been  done. 

Preparation  of  Antitoxin. — The  antitoxin  used  in  human  therapy  is 
practically  always  contained  in  the  blood  serum  or  blood  plasma  of 
the  horse.  The  blood  is  drawn  from  the  jugular  vein  into  sterile  bottles. 
The  bleeding  should  never  be  done  until  a  week  or  more  has  elapsed  after 
the  last  injection  of  toxine,  so  as  to  allow  time  for  the  disappearance  of 
the  poison  from  the  circulation.  The  horses  are  given  no  food  for  about 
24  hours  preceding  the  bleeding,  so  that  the  blood  may  not  contain  the 
fresh  products  of  digestion  and  metabolism.  After  the  blood  is  drawn  it 
may  be  allowed  to  clot  spontaneously.  In  the  case  of  horse  blood  this 
takes  place  more  quickly  at  room  temperature  than  in  the  ice  chest. 

^Eyg.  Lai.  Bull,  No.  38,  1907. 


562  IMMUNITY 

The  clot  is  allowed  to  contract  for  a  few  days  and  the  serum  containing 
the  antitoxin  is  then  drawn  off  with  a  pipet  or  simply  decanted.  In 
this  way  a  clear  transparent  serum  is  obtained  which,  if  protected  against 
contamination  by  the  usual  bacteriological  precautions,  is  sterile  and 
may  be  preserved  indefinitely.  It  is  almost  a  universal  practice,  however, 
to  add  a  preservative;  either  chloroform  (0.3  per  cent.),  phenol  (0.5  per 
cent.),  or  cresol  (0.4  per  cent.).  These  preservatives  in  the  amounts 
named  are  harmless  when  injected  and  have  practically  no  effect  upon 
the  antitoxin  itself.  They  gradually  precipitate  the  albuminous  matter 
from  the  serum,  which  settles  as  a  white  amorphous  deposit  and  which 
may  be  disregarded,  as  it  is  harmless.  Chloroform  produces  a  better- 
looking  serum,  but  the  less  volatile  preservatives  are  usually  preferred 
on  account  of  their  stability  and,  hence,  gi'eater  reliability. 

By  the  method  of  allowing  the  blood  to  coagulate,  as  above  described, 
only  about  one-third  of  its  volume  is  recovered  as  antitoxic  serum.  A 
much  greater  yield  may  be  obtained  by  citrating  the  blood :  sodium 
citrate  prevents  the  clotting  of  blood.  A  solution  of  this  salt  is  placed 
in  the  bottle  which  is  to  receive  the  blood  directly  from  the  horse,  in 
sufficient  amount  to  be  present  in  1  per  cent,  of  the  whole  blood.  The 
corpuscles  soon  settle  to  the  bottom,  leaving  the  clear  supernatant  plasma, 
which  is  then  decanted  or  drawn  off  with  a  pipet.  In  this  way  the  yield 
of  antitoxic  fluid  is  about  90  per  cent,  of  the  volume  of  the  blood,  and  is, 
therefore,  preferred  to  the  less  economical  method  of  allowing  the  blood 
to  clot. 

The  citrated  plasma  may  further  be  "purified"  or  concentrated  by 
various  methods,  that  generally  used  being  a  modification  of  Gibson's  ^^ 
method,  based  upon  the  earlier  experiments  of  Atchinson. 

Ordinary  antitoxic  serum  contains  serum  globulins  (antitoxic),  serum 
globulins  (non-antitoxic),  serum  albumins  (non-antitoxic),  serum  nu- 
cleoproteids  (non-antitoxic),  cholesterin,  lecithin,  traces  of  bile  color- 
ing matter,  traces  of  bile  salts  and  acids,  traces  of  inorganic  blood 
salts,  and  other  non-proteid  compounds.  Eefined  serum  contains  serum 
globulins  (antitoxic),  traces  of  serum  globulins  (non-antitoxic)  dissolved 
in  dilute  saline  solution. 

Method  of  Concentrating  Diphtheria  Antitoxin. — The  Banzhaf 
modification  of  the  original  Gibson  method  for  concentrating  antitoxic 
serums  is  based  on  the  fact  that  the  antitoxin  is  contained  in  the  pseudo- 
globulin  fraction  of  the  serum,  and  has  as  its  purpose  the  isolation  of 
the  antitoxic  pseudoglobulin  from  the  non-antitoxic  euglobulin,  albumin 
and  other  serum  constituents.  Plasma,  instead  of  serum,  is  used  for 
reasons  of  convenience  and  economy.  By  adding  ammonium  sulphate 
to  the  diluted  plasma  up  to  about  30  per  cent,  saturation  and  heating  the 
mixture  to  60°  C,  the  euglobulin  and  converted  non-antitoxic  pseudo- 

"'Jour.  of  Biolog.  Chem.,  Vol.  I,  1906. 


ANTITOXINS  563 

globulin  are  precipitated,  and  removed  hy  filtration.  By  raising  the 
saturation  of  the  filtrate  to  about  50  per  cent,  with  ammonium  sul- 
pliate,  the  antitoxin  is  ]irecipifjit('d.  1'his  is  collected  on  fdters,  pressed, 
and  dialy/A^l  in  paiTliincnl  ha^s  until  all  the  aiiiiloxiii  is  in  solution  and 
free  from  anmioiiiinn  sulphate.  It  is  then  neutralized  and  brought  to 
isotonicity  M'ith  the  hlood  hy  sodium  chlorid,  and  a  preservative  added. 
It  is  filtered  first  through  pulp  and  finally  through  a  Berkefeld  filter. 

This  nu^tliod  entails  a  loss  of  about  25  per  cent,  of  the  antitoxic 
units,  l)ut  results  in  a  five-  or  six-fold  concentration  of  the  antitoxin. 
The  process  of  concentration  makes  it  possible  to  utilize  serum  of  low 
potency;  it  enables  one  to  give  large  doses  of  antitoxin  in  small  volume; 
and  eliminates  the  bulk  of  serum  proteins  responsible  for  reactions  and 
for  serum  sickness. 

Mode  of  Action. — The  mode  of  action  of  antitoxins  is  now  fairly  well 
understood.  One  thing  is  certain,  and  that  is  that  the  antitoxin  unites 
directly  with  the  toxin.  This  may  be  readily  demonstrated,  by  adding  a 
little  antitoxin  to  some  toxin  in  a  test  tube  and.  then  injecting  the 
mixture  into  a  susceptible  animal;  no  symptoms  result.  Diphtheria 
antitoxin  combines  with  diphtheria  toxin  more  quickly  than  tetanus  an- 
titoxin combines  with  its  toxin.  Thus,  in  the  case  of  diphtheria  the 
union  between  the  toxin  and  its  antibody  is  complete  in  less  than 
twenty  minutes  at  room  temperature,  while  in  the  case  of  tetanus  it 
requires  one  hour.  These  facts  are  of  practical  importance  in  the  work 
of  standardization,  in  which  case  the  toxines  and  antitoxins  are  mixed 
in  the  test  tube  and  the  combining  action  must  be  complete  before  the 
mixtures  are  injected  into  the  test  animals  in  order  to  insure  accurate 
results. 

Ehrlich  believes  and  strongly  defends  his  assumption  that  an  anti- 
toxin unites  with  a  toxin  just  as  an  acid  unites  with  an  alkali,  that  is, 
the  one  has  a  strong  chemical  affinity  for  the  other,  and  the  union  is 
simple  and  direct.  The  reaction  is  complicated  only  on  account  of  the 
complex  nature  of  toxine.  According  to  Ehrlich,  there  are  two  primary 
metabolic  poisons  in  a  filtrate  of  a  culture  of  B.  diphtheriae :  (1)  toxin, 
a  poison  which  produces  a  local  destruction  of  tissue  and  acute  death; 
and  (2)  toxon,  a  nerve  poison  that  produces  late  paralysis.  There  is 
also  a  modified  toxin,  known  as  toxoid.  Toxin  is  more  actively  poison- 
ous and  also  has  a  greater  affinity  for  antitoxin  than  toxon,  which  it  is 
able  to  displace  from  its  combination  with  antitoxin.  This  explains  in 
part  the  discrepancy  between  the  Lo  and  the  L+  doses.  Ehrlich  believed 
that  the  union  of  filtrate  with  antitoxin  seems  to  occur  in  multiple  pro- 
portions resembling  valancies. 

On  the  other  hand,  Arrhenius  and  Madsen  insist  that,  instead  of 
considering  the  toxine  as  a  complex  mixture  of  various  substances,  such 
as  a  toxin,  toxon,  etc.,  it  would  be  simpler  to  consider  it  as  a  single  (at 


664  IMMUNITY 

least  homogeneous)  substance  which  has  a  very  weak  affinity  for  the 
antitoxin  and  that  in  mixtures  containing  toxin  and  antitoxin  there 
are  always  both  free  toxin  and  free  antitoxin.  Arrhenius  draws  his 
analogy  from  known  facts  in  physical  chemistry,  particularly  from 
studies  upon  the  relation  between  solutions  of  boracic  acid  and  ammonia. 
These  two  substances  have  a  comparatively  weak  affinity  for  each  other, 
and  in  mixtures  all  the  boracic  acid  does  not  combine  with  all  the  am- 
monia, but  there  are  always  present  both  free  ammonia  and  free  boracic 
acid. 

When  ammonia  and  boracic  acid  are  brought  together  in  watery  solu- 
tion some  of  the  ammonia  at  once  unites  with  some  of  the  boracic  acid 
to  form  ammonium  borate.  This  reaction  starts  with  a  certain  velocity, 
but  as  the  mass  of  ammonium  borate  increases  the  velocity  of  the  reaction 
gradually  diminishes.  After  a  time  a  condition  is  reached  when  the 
ammonium  borate  has  a  maximum  value  and  does  not  further  i;acrease, 
no  matter  how  long  the  reaction  is  allowed  to  proceed  under  the  given 
conditions. 

When  this  condition  of  equilibrium  is  reached  the  mass  contains  a 
certain  quantity  of  water,  ammonia,  boracic  acid,  and  ammonium  borate ; 
but  these  substances  are  not  at  rest.  The  ammonia  and  boracic  acid  will 
always  react  when  in  the  presence  of  each  other,  whether  or  not  am- 
monium borate  is  present.  But,  as  the  appropriate  amount  of  ammonium 
borate  remains  constant,  it  is  understood  while  this  continuous  association 
between  the  ammonia  and  the  boracic  acid  is  going  on  there  is  at  the 
same  time  a  reversible  action — that  is,  a  dissociation  of  the  ammonium 
borate  to  re-form  ammonia  and  boracic  acid.  These  two  reactions  take 
place  simultaneously. 

Arrhenius  believes  that  the  diphtheria  poison  changes  slowly  accord- 
ing to  the  laws  of  monomolecular  reactions,  that  the  toxin  combines 
feebly  with  the  antitoxin,  the  equilibrium  constant  being  equal  for  both. 
The  claim,  however,  that  the  toxin  is  a  simple  substance  having  a  weak 
affinity  for  the  antitoxin  and  that  the  combination  of  toxin  and  antitoxin 
follows  the  Guldberg-Waage  law,  and  that  the  reaction  is,  therefore, 
reversible,  seems  untenable  in  the  light  of  the  evidence  brought  forward 
by  Ehrlich,  Nernst,  Michaelis,  and  others. 

Another  view  which  seems  to  be  gaining  ground,  as  the  analogy  be- 
tween reactions  of  immunity  and  those  of  colloids  in  general  is  being 
established  more  definitely,  is  that  of  Bordet.^''  According  to  this  author, 
the  toxin  does  not  combine  with  antitoxin  according  to  the  laws  of  pro- 
portions as  typical  for  chemical  reactions,  but  the  antitoxin  distributes 
itself  equally  upon  aU  the  molecules  of  toxin  present.  Thus,  if  the 
amount  of  antitoxin  present  is  not  sufficient  to  neutralize  all  of  the 
toxin,  all  of  the  molecules  of  toxin  become  partially  saturated  with  the 

«Aiiii.  Inst.  Pasteur,  1903,  Vol.  17. 


STANDAEDIZATION  OF  ANTITOXIC  SEEA  565 

antitoxin.  Accordingly,  thoro  can  be  any  number  of  degrees  of  satura- 
tion before  a  complete  neutralization  of  toxin  by  antitoxin  is  reached. 
This  process  can  be  likened,  according  to  Bordet,  to  the  saturation  of 
starch  with  iodin.  The  starch  particles  can  absorb  variable  amounts  of 
iodin  and  accordingly  will  present  different  intensities  of  color.  Bordet 
speaks  of  this  process  as  being  based  on  "adsorption"  and  not  on  chemical 
combination  between  toxin  and  antitoxin. 

ENDOTOXINS 

In  contradistinction  to  the  soluble  or  exotoxins,  there  is  a  group  of 
poisons  known  as  endotoxins.  The  existence  of  endotoxins  was  taken 
for  granted  before  they  were  actually  demonstrated.  As  soon  as  it  was 
found  that  only  some  bacteria  produce  soluble  specific  toxines  it  was 
at  once  assumed  that  the  other  bacteria  must  contain  similar  poisons, 
but  closely  bound  within  the  cell  and  insoluble  in  ordinary  culture  fluids. 
It  was  further  assumed  that  these  endotoxins- were  in  some  way  set  loose 
in  the  body  and  thereby  produced  the  lesions  and  symptoms  of  the  disease. 
The  endotoxins  are  conceived  to  be  poisons  very  closely  bound  up  with 
the  protein  contents  of  the  bacterial  cell,  and  are  liberated  in  the  body 
when  the  bacterial  cell  dies  and  disintegrates.  However,  it  by  no  means 
follows  that  these  endotoxins  are  poisons  similar  in  action  and  com- 
position to  the  soluble  true  toxines ;  in  fact,  there  is  evidence  to  indicate 
the  contrary.  It  is  true  that  some  bacteria,  such  as  the  dysentery  bacil- 
lus, cholera  vibrio,  and  a  few  other  microorganisms  that  produce  little 
or  no  soluble  toxine,  may  be  ground  up  so  that  the  bacterial  cells  are 
mechanically  ruptured,  thus  liberating  the  endotoxin.  It  is  doubtful 
whether  the  so-called  "endotoxins"  exist  as  such  in  the  bacterial  cells, 
or  whether  they  are  poisons  formed  by  the  methods  of  extraction.  The 
existence  of  endotoxin  is  an  assumption  based  on  scant  experimental  evi- 
dence. In  some  cases  of  so-called  endotoxic  action  the  reaction  of 
anaphylaxis  appears  to  be  the  best  explanation. 

STANDARDIZATION  OF  ANTITOXIC  SERA 

The  method  of  measuring  the  strength  of  diphtheria  and  tetanus 
antitoxins  is  exceedingly  accurate  and  satisfactory.  The  tests  are.  physi- 
ological, that  is,  depend  upon  animal  experimentation.  Guinea-pigs  are 
used  because  they  are  particularly  susceptible  to  both  tetanus  and  diph- 
theria toxines  and  react  to  these  poisons  so  uniformly  that  they  serve 
the  purpose  of  an  accurate  analytical  balance.  In  order  to  obtain  precise 
results  it  is  essential  that  all  the  conditions  of  the  test  be  uniform.  It  is, 
therefore,  advisable  to  follow  the  official  methods,  which  have  been  pre- 
scribed in  great  detail.     All  antitoxic  sera  upon  the  American  market 


566  IMMUNITY 

are  standardized  in  accordance  with  the  official  unit  dispensed  by  the 
federal  government.  This  work  is  done  in  the  Hygienic  Laboratory  of 
the  Public  Health  Service. 

The  Standardization  of  Diphtheria  Antitoxin. — The  immunity  unit 
for  measuring  the  strength  of  diphtheria  antitoxin  may  be  defined  as 
the  neutralizing  power  possessed  by  an  arbitrary  quantity  of  diphtheria 
antitoxic  serum  kept  under  special  conditions  to  prevent  deterioration 
in  an  authorized  laboratory. 

From  a  theoretical  viewpoint  the  unit  may  be  defined  as  that  quan- 
tity  of  diphtheria  antitoxic  serum  which  will  just  neutralize  200  mini- 
mal lethal  doses  of  a  pure  poison.  By  a  "pure"  poison  is  understood 
one  containing  only  toxin  and  no  toxoid,  toxon,  or  other  substance 
capable  of  uniting  with  the  antibodies. 

The  first  definition  may  be  compared  to  the  platino-iridium  bars  kept 
under  special  conditions  in  Paris  or  Washington  as  the  standard  yard  or 
meter.  If  all  the  meter  bars  or  yardsticks  were  lost  it  would  be  difficult, 
if  not  impossible,  to  reproduce  others  having  the  exact  lengths  of  the 
originals.  These  standard  measures  are,  therefore,  guarded  against  de- 
terioration just  as  the  standard  antitoxic  sera  are  preserved  under  strict 
conditions  of  light,  heat,  moisture,  etc.,  in  the  Hygienic  Laboratory  of  ■ 
the  Public  Health  Service  at  Washington.  From  time  to  time  duplicates 
of  this  serum  are  made  to  guard  against  deterioration  or  accident  to  the 
original. 

The  second  definition  may  be  compared  to  the  original  conception 
of  the  meter,  which  was  intended  to  be  one  ten-millionth  of  the  quad- 
rant of  a  great  circle  of  the  earth.  Theoretically,  therefore,  if  all  the 
meter  bars  were  lost  this  unit  of  measurement  could  be  reproduced  with 
approximate  fidelity.  In  the  same  way  it  is  theoretically  possible  to 
reproduce  the  diphtheria  antitoxic  unit  in  consideration  of  that  fact  that 
it  has  just  200  combining  units. 

The  test  by  which  the  strength  of  antitoxin  is  measured  is  a  physio- 
logical one,  and  depends  upon  the  neutralization  of  the  toxin  by  the 
antitoxin.  This  neutralization  can  only  be  determined  by  injecting  the 
toxine-antitoxin  mixtures  into  guinea-pigs  and  noting  the  results.  The 
unit  for  measuring  the  strength  of  diphtheria  antitoxin  is  a  measure  of 
physiologic  strength,  not  of  quantity. 

In  all  the  early  work  on  this  subject  the  toxine  was  used  as  a  basis 
for  measuring  the  strength  of  the  antitoxin,  but  as  the  toxine  is  a  much 
more  complex  substance  than  the  antitoxin,  and  as  it  is  less  stable,  ac- 
curate results  were  not  possible.  Ehrlich  showed  that  the  antitoxin 
under  certain  conditions  was  permanent  both  in  power  of  chemically 
combining  with  and  physiologically  neutralizing  the  toxine.  One  anti- 
toxin, however,  cannot  be  compared  with  another  antitoxin  directly. 
This  can  only  be  done  through  the  toxine. 


STANDARDIZATION  OF  ANTITOXIC  SERA 


5G7 


From  a  practical  standpoint,  ilw  loUowing  illustration  of  a  test  will 
give  a  clear  conception  as  to  how  the  unit  of  strength  of  a  serum  is 
determined. 

Example  of  a  Test. — It  is  first  necessary  to  obtain  our  ofhciai  yard- 
stick. This  may  be  done  by  applying  to  the  Hygienic  Laboratory  in 
Washington,  where  the  standard  serum  is  kept  in  a  dry,  powdered  form 
in  vacuum  tubes  under  the  influence  of  pentaphosphoric  acid  in  a  cold 
place  and  carefully  preserved  from  the  light.  This  powder  is  dissolved, 
carefully  tested,  and  sent  to  the  applicant  in  a  glycerinated  solution. 
Each  cubic  centimeter  of  a  certain  dilution  of  this  standard  serum 
contains  just  1  unit.  Before,  however,  we  can  measure  the  potency  of 
an  antitoxic  serum  of  unknown  strength  it  is  first  necessary  to  stan- 
dardize a  toxine.  This  is  done  by  mixing  one  unit  of  the  standard  anti- 
toxic serum  with  varying  quantities  of  the  toxine,  as  shown  in  table 
below. 

From  this  series  we  learned  that  one  unit  contains  just  sufficient  anti- 
toxin to  neutralize  0.16  c.  c.  of  the  toxine.  This  is  known  as  the  Lq 
dose.^^  By  the  Lo  dose,  then,  is  meant  that  quantity  of  toxine  which 
just  neutralizes  or  saturates  one  immunity  unit  as  shown  at  the  necropsy 
done  48  hours  after  the  subcutaneous  injection  of  the  mixture  into  the 
guinea-pig.  The  reaction  at  the  site  of  inoculation  at  this  examination 
must  be  hardly  noticeable. 


Mixtures  of  Antitoxic  Serum  and 

Toxine  Injected  Subcutaneously 

into  Guinea-Pigs. 


1  immunity  unit  +  0.14 
"     +0.15 
"     +0.16 

e.  c. 

11 

toxine 

a 
It 

(C 

a 
t( 

+  0.17 
+  0.18 
+  0.19 

u 
u 

<( 
u 

H 

« 

(C 

+  0.20 

u 

a 

« 

(( 

+  0.21 

a 

u 

« 

a 

+  0.22 

a 

li 

(I 

u 

+  0.23 

a 

(I 

Result. 


ISTo  reaction. 

Xo  reaction. 

Slight  congestion  at  site  of  injection. 
[This  is  the  Lo  dose.] 

Apparent  reaction  at  site  of  injection. 

Injection  and  edema  at  site. 

Injection  and  edema  at  site;  late  pa- 
ralysis. 

Sometimes  death  in  5  or  6  days,  some- 
times late  paralysis. 

Always  causes  acute  death  about  the 
fourth  day.   [This  is  the  L+  dose.] 

Acute  death  usually  on  second  or 
third  day. 

Acute  death  on  second  day. 


In  the  above  illustration  the  L""  dose  of  this  toxine  is  just  0.31  c.  c. 
By  the  L^.  dose  is  meant  the  smallest  quantity  of  poison  that  will  neu- 
tralize one  immunity  unit  plus  a  quantity  necessary  to  kill  the  animal 

^L  stands  for  Limit.  Lo  stands  for  the  limit  of  no  reaction,  and  L+  the 
limit  of  acute  death. 


568 


IMMUNITY 


on  the  fourth  day.    The  L_^  close  is  the  test  dose  which  is  used  to  deter- 
mine the  strength  of  our  unknown  antitoxic  serum,  as  follows : 


The  L+ 

(or  Test  Dose  of  Toxin)   -1-  Varying 

Amounts  of  Antitoxin  Injected 

into 

Eesults. 

Guinea-Pigs. 

0.21 

c.  c. 

toxine 

+  1/150  c.  c.  antitoxic  serum 

No  effect. 

+  1/175     " 

No  eSect. 

4-  1/200     " 

Late  paralysis. 

-i-  1/225     "            " 

Late  paralysis. 

+  1/250     " 

Dies  4th  day. 

+  1/2Y5     " 

Dies  3d  day. 

+  1/300     "            " 

Dies  2d  day. 

From  this  series  it  is  evident  that  1/850  c.  c.  of  the  serum  eontains 
that  amount  of  antitoxin  which  will  neutralize  the  toxin  in  the  test 
dose,  leaving  sufficient  free  poison  to  i:ill  the  animal  on  the  fourth  day. 
The  serum,  therefore,  contains  one  antitoxic  unit  in  1/250  c.  c.  of  serum. 
One  c.  c.  of  the  serum  would,  therefore,  contain  250  units.^^ 

Standardization  of  Tetanus  Antitoxin. — There  are  four  methods  of 
measuring  the  strength  of  tetanus  antitoxin:  (1)  the  German  method 
described  by  Behring;  (2)  the  French  method  described  by  Eoux;  (3) 
the  Italian  method  after  Tizzoni,  and  (4)  the  American  method  estab- 
lished by  Eosenau  and  Anderson.^"  '  European  standards  are  admitted  to 
be  unsatisfactory  and  for  the  most  part  not  accurate.  Further,  they 
are  complicated  and  difficult  to  carry  out.  The  American  method,  which 
has  been  made  the  official  government  standard  for  this  and  other  coun- 
tries, commends  itself  for  its  simplicity,  directness,  and  precision. 

The  tetanus  antitoxic  unit  is  based  upon  the  neutralizing  value  of  an 
arbitrary  quantity  of  antitoxic  serum  preserved  under  special  conditions 
to  prevent  deterioration  in  the  Hygienic  Laboratory  of  the  Public  Health 
Service.  This  arbitrary  quantity  now  contains  ten  times  the  amount  of 
tetanus  antitoxin  necessary  to  neutralize  somewhat  less  than  100  minimal 
lethal  doses  of  a  standard  toxine  for  a  350-gram  guinea-pig.  That  is, 
0.1  of  a  unit  mixed  with  100  minimal  lethal  doses  of  the  standard  toxine 
contains  just  enough  free  poison  in  the  mixture  to  kill  the  guinea-pig 
in  four  days  after  subcutaneous  injection. 

The  official  definition  of  a  tetanus  antitoxic  unit  is  the  following: 
The  immunity  unit  for  measuring  the  strength   of  tetanus  antitoxin 

="  For  the  details  for  carrying  out  these  tests  the  reader  is  referred  to  the 
Hygienic  Laboratory  Bulletin  No.  21  upon  "The  Immunity  Unit  for  Standard- 
izing Diphtheria  Antitoxin,"  by  M.  J.  Rosenau,  which  contains  the  official  de- 
scription and  details  of  the  process  and  its  theoretical  considerations. 

^"Hygienic  Laboratory  Bulletin  No.  J^S,  P.  H.  &  M.  H.  Service,  Washington, 
March,  1908. 


STANDARDIZATION  OF  ANTITOXIC  SERA  569 

shall  be  ten  times  the  least  quantity  of  antitetanic  serum  necessary  to 
save  the  life  of  a  .'?r)0-grnm  f]fuinoa-pig  for  9G  hours  against  the  official 
dose  of  a  standard  toxiue  furnished  by  the  Hygienic  T.aboratory  of  the 
Public  Health  and  IMarine  Hospital  Service. 

The  standardization  of  tetanus  antitoxin  docs  not  differ  radically 
from  the  standardization  of  diphtheria  antitoxin.  The  toxins  and  anti- 
toxins are  niixcMl  and  thc>  mixture  injected  into  guinea-pigs.  While,  how- 
ever, the  unit  is  based  upon  the  neutralizing  value  of  an  arbitrary  quan- 
tity of  antitoxic  scrum,  the  antitoxin  is  not  issued  for  a  basis  of  com- 
parison, as  in  the  case  of  diphtheria.  A  stable  precipitated  toxine,  the 
test  dose  of  which  has  been  carefully  determined,  is  issued  to  other  labora- 
tories for  the  purpose  of  testing. 

The  value  of  an  unknown  serum  is  measured  directly  from  this 
standard  precipitated  toxine,  the  L+  or  test  dose  of  which  is  stated. 
The  L+  or  test  dose  of  the  particular  toxine  now  dispensed  by  the  gov- 
ernment contains  just  100  minimal  lethal  doses  for  a  350-gram  guinea- 
pig.  This  particular  toxine  is  very  stable  and  has  not  changed  appre- 
ciably in  eight  years.  As  soon  as  it  alters  or  is  exhausted  the  next  toxine 
that  will  be  issued  may  contain  more  or  less  than  100  minimal  lethal 
doses,  but  the  test  dose  will  contain  precisely  the  same  neutralizing 
power. 

The  tetanus  antitoxic  unit  may  be  better  understood  from  an  exam- 
ple of  a  test. 

An  Example  of  a  Test. — Carefully  tare  a  weighing  bottle,  then 
add  approximately  20  to  50  mg.  of  the  dried  poison.  Again  carefully 
weigh.  Dissolve  the  toxine  in  the  weighing  bottle  with  salt  solution 
(0.85)  in  the  proportion  of  0.1  gram  of  the  dried  poison  to  166.66  c.  e. 
of  the  salt  solution.  This  proportion  is  used  for  the  reason  that  each 
cubic  centimeter  of  this  solution  will  represent  0.0006  gm.  of  the  orig- 
inal dried  poison  (=:  100  MLD's).  This  proportion  is  taken  because 
it  is  very  convenient  in  measuring  out  the  test  dose,  which  represents 
1  e.  c.  of  the  solution.    Thus: 

44.5692  gm.,  bottle  +  toxine. 
44.5300  gm.,  bottle. 


.0392  gm.,  toxine. 
0.1  gm.   :  166.66  c.  c.   :  :  0,0392   :  x. 
X  =  65.33  c.  c. 

In  other  words,  if  the  quantity  of  toxine  placed  in  the  weighing 
bottle  should  weigh,  as  in  this  instance,  just  0.0392  gm.,  carefully  deliver 
from  an  accurately  graduated  burette  just  65.33  c.  c.  salt  solution  into 
the  weighing  bottle;  and,  as  before  stated,  each  cubic  centimeter  of  this 
solution  will  be  the  L+    or  test  dose. 

Now  dilute  the  serum  of  unknown  value  in  accordance  with  the  table 


570 


IMMUNITY 


of  dilutions,  and  mix  aliquot  parts  of  the  serum  with  the  test  dose  of 
toxine,  as  follows: 


No.  of 

Weight  of 

guinea-pig 

(grams) 

Subcutaneous  injection  of  a 
mixture  of — 

Time  of  death 

guinea-pig 

Toxine  (test dose) 

Antitoxin 

1 

350 

350 
350 
350 
350 

Gram. 

0.0006 
.0006 
.0006 
.0006 
.0006 

C.   C. 

0.001     . 
.0015 
.002 
.0025 
.003 

2  days,  4  hours. 

2 

4  days,  1  hour. 

3 

Symptoms. 

4 

Slight  symptoms. 

5 

No  symptoms. 

According  to  this  series  the  guinea-pig  which  received  the  mixture 
containing  0.0015  c.  c.  of  the  serum  died  in  four  days  and  one  hour. 
Therefore,  0.0015  c.  c.  of  the  serum  contains  one-tenth  of  an  immunity 
unit,  as  the  unit  has  been  defined  as.  ten  times  the  least  amount  of  anti- 
tetanic  serum  necessary  to  save  the  life  of  a  350-gram  guinea-pig  96 
hours  against  the  official  test  dose.  This  serum  would,  therefore,  contain 
just  66  units  per  c.  c. 

In  order  to  obtain  reliable  and  comparable  results,  it  is  necessary 
to  take  into  account  all  the  factors  concerned— the  composition  of  the 
poisons,  their  concentration,  the  diluting  fluid,  length  of  time  the  mix- 
tures are  allowed  to  stand,  the  site  of  inoculation,  etc.,  in  accordance 
with  directions  in  the  official  methods. 


PHAGOCYTOSIS 


Metchnikoff  gave  us  the  first  physical  explanation  of  immunity 
through  his  brilliant  studies  upon  phagocytosis.  Metchnikoff  was  a  biol- 
ogist, and  as  a  result  of  his  stimulating  observations  upon  the  phago- 
cytes in  all  the  orders  of  the  animal  kingdom  he  contributed  much 
to  our  knowledge,  not  alone  of  immunity,  but  to  our  fundamental 
knowledge  of  nutrition  and  inflammation.  The  ingenuity  and  fertility 
of  his  views  caused  a  flood  of  work  from  others  upon  these  basic  subjects 
in  medical  biology. 

Phagocytosis  is  a  process  common  to  all  cells  having  amebic  motion 
and  also  to  some  fixed  cells.  A  phagocyte  is  any  cell  capable  of  absorb- 
ing particulate  matter  into  its  substance.  The  process  is  best  seen  with 
an  ameba  under  the  microscope. 

For  a  clear  understanding  of  phagocytosis  it  is  necessary  to  consider 
three  phases  of  the  process:  (1)  the  approach,  (2)  the  engulf ment,  and 
(3)  the  digestion. 


PHAGOCYTOSIS  571 

The  approach  or  cliemotaxis  is  a  phenomenon  which  is  displayed 
by  ahnost  all  motile,  iinicollnlar  ororanisnis,  whether  animal  or  vege- 
table, as  well  as  by  the  leukocytes.  It  manifests  itself  by  a  movement 
of  the  unicellular  organism  or  the  phagocytic  cell  toward  the  particle  and 
seems  to  be  a  resjioiise  to  a  chemical  stimulus.  Chemotaxis  is  said  to  be 
positive  when  the  leukocytes  are  quickly  and  energetically  attracted  to 
a  substance,  and  negatid'e  when  this  attraction  is  lacking.  There  is 
considerable  doubt  whether  there  is  true  negative  chemotaxis  in  the  sense 
of  repulsion.  The  degree  of  chemotaxis  possessed  by  any  substance  may 
readily  be  determined  by  placing  it  in  a  capillary  tube  closed  at  one  end 
and  then  inserting  the  open  end  of  the  tube  into  the  tissue  of  an  animal 
or  into  a  fluid  containing  active  phagocytes.  If  the  substance  has  posi- 
tive chemotactic  power  the  phagocytes  soon  approach  the  free  end  of  the 
capillary  tube,  which  they  enter;  if  the  substance  has  negative  chemo- 
tactic power  the  phagocytes  are  not  attracted  and  do  not  enter  the  capil- 
lary tube.  As  Emery  points  out,  the  leukocytes  are  in  many  cases  at- 
tracted into  an  infected  area  to  their  own  undoing,  and  it  must  not  be 
forgotten  that  "even  in  inflammatory  processes  which  are  .mild  in  nature 
and  favorable  in  result  the  number  of  leukoc}i;es  which  may  be  killed  in 
the  conflict  is  enormous.  The  leukocytes  are  not  independent  protozoa 
inhabiting  the  blood  and  tissues,  but  an  integral  part  of  the  organism. 
It  is  to  the  advantage  of  the  latter  that  the  former  should  be  attracted 
at  once  to  the  seat  of  invasion,  and  hence  the  processes  of  evolution  have 
led  to  the  development  of  this  function  in  the  nomadic  cells  of  the  body. 
These  are  extraordinarily  susceptible  to  chemotactic  mfluences.  They 
seem  to  be  attracted  by  any  deviation  from  the  normal  situation  of  the 
tissues  and  fluids — a  slight  injury,  a  hemorrhage,  the  presence  of  a 
poison,  or  a  foreign  body  of  any  sort,  or  any  dead  or  useless  tissue — and 
the  leukocytes  are  immediately  attracted  into  the  area  affected.  The 
more  we  regard  the  process  the  more  we  must  regard  it  as  one  of  the 
most  exquisite  examples  of  means  to  ends  met  with  in  the  animal 
economy." 

The  engulf ment  of  the  bacteria  may  readily  be  studied  in  amebae 
in  their  free  living  stage.  The  protoplasm  of  the  ameba  is  thrown  out 
in  the  form  of  pseudopodia ;  these  encircle  the  particle,  which  soon 
appears  within  the  substance  of  the  ameba.  The  engulfment  of  particles 
by  the  leukocytes  and  other  cells  is  precisely  the  same. 

The  digestion  within  the  cell  is  entirely  comparable  to  gastric  diges- 
tion in  higher  animals.  It  is  now  known  that  active  proteolytic  ferments 
dissolve  the  albuminous  particles,  and  that  this  takes  place  in  an  acid 
medium  may  be  demonstrated  by  the  use  of  delicate  indicators,  such  as 
neutral  red. 

The  phagocytes  may  take  up  and  digest  either  live  or  dead  bacteria ; 
they  are  not  simply  scavengers.    They  engulf  particles  of  all  kinds,  both 


573  IMMUNITY 

organic  and  inorganic.  Thus,  in  anthracosis  the  particles  of  coal  are 
mainly  carried  and  contained  in  the  phagocytic  cells.  The  phagocytes 
engulf  and  dispose  of  malarial  pigment,  the  granules  of  pigment  left 
after  a  hemorrhage,  and  other  foreign  particles  in  the  body.  Phagocytes 
are  also  enabled  to  absorb  colloidal  substances  and  fluids  as  well  as  par- 
ticulate matter.  They  are  enabled  to  dispose  of  a  comparatively  large 
mass  by  removing  it  piecemeal.  Thus,  the  "core"  of  a  boil  is  gradually 
removed,  mainly  by  the  phagocytes.  Catgut  and  silk  ligatures  are  simi- 
larly removed ;  the  absorption  of  the  tadpole's  tail  is  disposed  of  through 
the  same  process. 

Metchnikoff  divided  the  phagocytes  into  free  and  fixed,  macrophages 
and  microphages. 

The  free  phagocytes  are  the  leukocytes,  lymphocytes,  and  other  blood 
cells,  as  the  myelocytes  from  the  bone  marrow.  The  fixed  phagocytes 
are  the  connective  tissue  cells  and  endothelial  cells.  The  fr,ee  phago- 
cytes, according  to  Metchnikoff,  play  the  more  important  role. 

The  microphages,  or  microcytes,.  are  the  mononuclear  leukocytes,  the 
polymorphonuclear  leukocytes,  and  the  wandering  connective  tissue  cells. 
The  macrophages,  or  macrocytes,  are  the  large  lymphocytes,  the  mononu- 
clear pulp  cells  of  the  spleen  and  bone  marrow,  endothelial  cells  of  the 
large  vessels,  and  Kupfer's  stellate  cells  of  the  liver.  The  microphages 
play  an  active  part  in  all  acute  infections.  They  are  the  first  to  come 
in  the  field  and  for  the  most  part  are  vegetarians,  that  is,  they  take  up 
bacteria  especially.  The  macrophages,  on  the  other  hand,  are  carnivor- 
ous, engulfing  other  cells  and  protozoon  parasites,  and  are  especially  con- 
cerned in  chronic  inflammations,  such  as  tuberculosis  and  leprosy,  rather 
than  in  the  acute  processes.  These  distinctions  between  the  free  and  fixed 
phagocytes,  the  microphages  and  macrophages,  are  entirely  arbitrary. 
All  the  leukocytes  have  the  power  of  phagocytosis,  though  in  varying 
degree.  This  is  readily  seen  in  an  opsonic  preparation  or  in  an  examina- 
tion of  a  smear  of  gonorrheal  pus,  when  some  of  the  polymorphonuclear 
leukocytes  will  be  loaded  with  the  cocci  while  others  contain  few  or  none. 
The  small  phagocytes  (microcytes)  are  able  to  engulf  protozoa  and 
animal  cells  as  well  as  bacteria. 

Metchnikoff  has  insisted  since  the  beginning  of  his  studies  upon 
phagocytosis  that  this  process  plays  an  important,  if  not  the  sole,  role 
in  immunity.  He  conceives  that  a  true  battle  takes  place  between  the 
cells  and  the  invading  germs.  When  phagocytosis  is  active  and  suc- 
cessful, immunity  is  the  result.  If  phagocytosis  is  absent,  or  the  phago- 
cytes are  unsuccessful,  the  result  is  susceptibility  instead  of  immunity. 
Metchnikoff  fi.rst  studied  the  protective  power  of  the  phagocytes  in  a 
fresh  water  crustacean,  the  daphnia,  which,  from  its  transparency  and 
small  size,  is  a  very  suitable  creature  for  observation.  He  found  that  the 
daphnia  is  subject  to  a  disease  due  to  the  invasion  of  its  body  cavity  by 


PHAGOCYTOSIS  573 

the  spores  of  a  yeast  (Monospora),  and  that  if  these  spores  gain  access  in 
large  numbers  they  multiply,  form  into  mature  organisms,  and  finally  kill 
their  host.  When,  however,  a  few  spores  gain  access  lie  found  the  leuko- 
cytes of  the  daphnia  approacii  them,  form  a  wall  around  them,  and  finally 
digest  and  destroy  them.  It  is  obvious,  therefore,  that  the  immunity  of 
the  daphnia  to  this  infection  depends  upon  the  activity  of  its  leukocytes. 
Analogous  instances  are  found  in  many  other  animals,  including  man. 
In  the  streptococcus  infections  particularly  Metchnikoff  believed  their 
virulence  depended  upon  the  absence  of  phagocytic  action. 

It  soon  became  evident  to  Metchnikoff  himself  that  the  mechanism 
of  immunity  was  a  much  more  complicated  process  than  could  be  ac- 
counted for  simply  by  the  number  and  physical  activity  of  the  phago- 
cytes. The  simple  act  of  phagocytosis  alone  could  not  explain  all  the 
phenomena.  It,  therefore,  became  necessary  to  study  the  processes  of 
digestion  and  the  products  of  excretion  of  the  phagocytes.  It  soon  be- 
came evident  that  the  digestive  power  of  the  phagocytes  is  a  very  power- 
ful one,  and  substances  usually  deemed  entirely  insoluble  may  be  gradu- 
ally removed  by  their  action.  Metchnikoff  considered  two  of  these  sub- 
stances to  be  concerned  in  immunity:  the  microcytase  and  the  raacro- 
cytase. 

The  microcytase  is  a  ferment-like  substance  obtained  from  the  micro- 
cytes.  It  is  thermolabile  and  corresponds  in  all  essential  respects  to  the 
alexin  of  Buchner  or  the  complement  of  Ehrlich. 

The  macrocyfa-se  is  a  thermostable  substance  obtained  from  the  mac- 
rocytes.  It  is  concerned  with  specific  acquired  immunity.  The  macro- 
cyte  fastens  itself  to  the  bacteria,  hence  w^as  called  by  Metchnikoff  the 
fixator.  It  is  similar  in  all  essential  respects  to  the  "substance  sensi- 
bilitrice'''  of  Bordet,  or  the  amboceptor  of  Ehrlich. 

Buchner,  as  well  as  most  other  unprejudiced  students  in  immunol- 
ogy,  takes  the  middle  ground  between  the  doctrines  of  the  cellular  theory 
represented  by  Metchnikoff  and  his  school  and  the  doctrines  of  the  hu- 
moral theory  represented  by  Ehrlich,  It  now  seems  quite  evident  that 
both  the  cells  and  the  body  fluids  play  an  important  role  in  the  mechanism 
of  immunity.  It  is  also  equally  evident  that  the  mechanism  of  immunity 
differs  widely  with  different  infections;  in  some  phagocytosis  plays  a 
dominant  part ;  in  others  it  seems  that  the  fluids  of  the  body  are  chiefly 
concerned.  It  must  not  be  forgotten  that  even  where  the  fluids  of  the 
body  are  the  chief  actors  the  antibodies  are  probably  in  all  cases  derived 
from  the  cells.  Just  what  cells — whether  the  fixed  tissue  cells  or  the 
free  phagocytes — are  chiefly  concerned  in  the  production  of  these  anti- 
bodies is  not  quite  clear. 

All  observers  are  agreed  upon  one  fundamental  thought,  and  that  is, 
immunity  is  closely  allied  to  the  processes  of  cell  nutrition.  The  re- 
ceptors of  Ehrlich  are  the  mouths  of  the  cells  for  food.     The  phago- 


674  IMMUNITY 

cytosis  of  Metchnikoff  is  primarily  a  mechanism  by  which  cells  possess- 
ing amebic  motion  obtain  their  food.  Anaphylaxis,  which  offers  another 
explanation  of  immunity  to  certain  infections,  deals  with  the  funda- 
mental problems  of  protein  metabolism.  It  is,  therefore,  plain  that  any 
experimental  research  that  gives  a  deeper  insight  into  protein  metabolism 
as  well  as  the  more  direct  researches  in  immunology  has  a  fundamental 
bearing  upon  the  prevention  and  cure  of  disease. 


OPSONINS 

The  name  opsonin  {byj/wv'eoi,  I  cater  for,  I  prepare)  is  given  to  sub- 
stances which  occur  in  the  blood  and  which  have  the  power  of  preparing 
bacteria  and  other  ceUs  for  ingestion  by  the  leukocytes.  The  opsonins  com- 
bine with  the  bacteria  and  in  that  way  prepare  them  for  being  taken 
up  more  easily  by  the  phagocytic  cells.  In  the  absence  of  opsonins, 
phagocytosis  does  not  take  place,  and  their  great  importance  is,  therefore, 
at  once  manifest.  There  is  now  no  doubt  concerning  the  existence  of 
these  substances,  and  the  brilliant  work  of  Wright  has  stimulated  a  flood 
of  researches  which  have  thrown  much  light  upon  this  chapter  in  im- 
munology. According  to  Ehumbler,  opsonic  action  merely  shows  the 
presence  of  something  that  affects  the  surface  tension  of  the  bacteria. 

The  opsonins  are  normally  present  in  the  blood  or  may  be  increased 
or  diminished  in  amount  by  the  injection  of  bacteria  or  appropriate 
antigen.  The  opsonins  are  specific,  that  is,  the  blood  serum  may  contain 
opsonins  which  prepare  staphylococci  for  the  phagocytes,  but  may  contain 
no  suitable  substance  to  prepare  streptococci,  tubercle  bacilli,  or  some 
other  microorganism.  The  opsonins  are  probably  similar  to  the  bacterio- 
tropins;  their  chemical  nature,  however,  in  common  with  other  anti- 
bodies, is  not  understood. 

Tropins  are  simple  antibodies,  not  affected  by  the  usual  inactivating 
temperature,  56°  C.  They  act  without  the  aid  of  complement.  The 
opsonins  are  complex,  containing  thermolabile  complement  as  well  as  a 
more  stable  body.  They  are  inactivated  at  56°  C.  for  30  minutes,  or  by 
standing  at  ordinary  temperatures. 

The  Opsonic  Index. — Sir  Almroth  Wright  has  modified  Leishmann's 
method  for  measuring  the  opsonic  power  of  the  blood  serum,  but  the 
method  is  somewhat  complicated  and  gives  variable  results  even  in  the 
hands  of  trained  workers.  It  may  be  questioned  whether  any  of  the 
tests  now  in  use  are  a  true  index  of  the  amounts  of  opsonins  in  the  serum, 
although  they  may  be  taken  to  indicate  roughly  the  measure  of  their 
activity.  The  opsonic  index  has  been  especially  used  as  a  guide  to 
vaccine  therapy  rather  than  in  preventive  medicine.  If,  however,  we  had 
a  satisfactory  and  ready  method  by  which  the  specific  opsonins  of  the 


LYSINS  575 

blood  could  be  measured  so  that  deficiencies  could  be  readily  determined 
and  strengthened,  we  would  theoretically  at  least  have  a  valuable  addition 
to  prophylaxis. 

LYSINS 

Lysins  are  ''substances"  that  have  the  power  of  disintegrating  or  dis- 
solving cells  or  other  organized  structures.  Those  that  dissolve  bacteria 
are  known  as  the  hacteriolydns,  those  that  dissolve  red  blood  cells  are 
called  hemolysins,  those  that  dissolve  epithelial  or  other  body  cells  are 
called  cytoJysins  or  cytotoxins.  The  lysins  in  themselves  are  not  poison- 
ous, but  through  their  action  they  may  liberate  or  generate  toxic  sub- 
stances and  thus  play  an  important  role  not  only  in  the  pathogenesis  of 
many  infectious  diseases  and  diseased  states,  but  also  in  their  cure  and 
prevention. 

Normally  the  blood  possesses  bactericidal  properties,  and  it  is  be- 
lieved that  this  is  almost  entirely  due  to  its  power  of  dissolving  the  bac- 
terial cells.^^  The  bacteriolytic  property  of  normal  blood  serum  is  not 
specific,  w'hereas  the  bacteriolysins  induced  through  special  processes  by 
immunization  are  strictly  specific.  The  fact  that  the  blood  has  the  power 
of  resisting  decomposition  longer  than  other  animal  fluids  was  known  to 
Hunter  before  the  era  of  bacteriology.  It  was  also  early  known  that 
this  property  of  the  blood  diminishes  spontaneously  after  it  was  shed 
and  could  be  destroyed  by  heat — about  55°  C.  The  bacteriolytic  sub- 
stances in  the  blood  were  first  studied  by  Buchner  and  Nuttall,  who  called 
them  alexins.  When  it  was  discovered  that  the  blood  possesses  marked 
powers  of  destroying  bacteria  the  conclusion  was  naturally  drawn  that 
herein  lies  the  explanation  of  immunity.  It  was  soon  learned,  however, 
that,  though  the  blood  of  certain  animals  may  possess  marked  bactericidal 
properties,  nevertheless  they  are  very  susceptible;  and,  further,  that  the 
power  to  kill  bacteria  is  much  more  marked  in  the  serum  in  vitro,  than 
in  the  live  circulating  blood  in  the  animal.  Thus,  according  to  Lu- 
barsch,  16,000  virulent  bacilli  wall  kill  a  rabbit  if  injected  intraven- 
ously ;  that  is,  the  blood  within  the  body  has  not  the  power  of  killing  this 
number,  yet  1  c.  c.  of  fresh  blood  serum  will  destroy  this  number  or 
even  more  in  a  test  tube. 

Eabbits  are  very  susceptible  to  anthrax,  although  the  blood  serum 
of  these  animals  possesses  marked  bactericidal  properties  in  vitro,  for  the 
anthrax  bacillus ;  on  the  other  hand,  the  dog  is  very  resistant  to  anthrax, 
despite  the  fact  that  its  blood  serum  is  very  slightly  bactericidal. 

The  bacteriolysins  w^ere  discovered  by  Eichard  Pfeiffer  ^^  in  his  at- 
tempt actively  to  immunize  animals  against  cholera  by  the  injection 

^  Demonstrated  by  Nuttall,  in  1888. 

"^Zeit.  f.  Hyg.,  Vol.  XVIII,  and  Deutsche  med.  Woclien.,  1896,  pp.  97,  119. 


576  IMMUNITY 

of  live  cultures.  He  observed  that  the  cholera  organisms  were  disin- 
tegrated and  dissolved  in  the  peritoneal  cavity  of  the  immunized  animals. 
This  gave  rise  to  what  is  now  known  as  PfeifEer's  phenomenon,  which, 
on  account  of  its  importance,  must  be  considered. 

Pfeiffer's  Phenomenon. — Guinea-pigs  are  immunized  by  the  subcu- 
taneous injection  of  increasing  doses  of  a  cholera  culture  about  once  a 
week  until  they  are  able  to  withstand  large  amounts  of  a  fresh  viru- 
lent strain.  This  usually  required  at  least  tlrree  or  four  injections. 
Some  of  the  live  microorganisms  are  now  injected  into  the  peritoneal 
cavity  of  the  immunized  animal,  and  from  time  to  time  minute  drops 
of  this  injected  material  with  the  peritoneal  exudate  are  withdrawn  by 
means  of  capillary  tubes  and  examined  under  the  microscope.  It  will 
be  found  that  the  bacteria  previously  actively  motile  soon  lose  their 
power  of  motion  and  die.  They  then  become  somewhat  swollen  and 
agglutinate  into  balls  or  clumps,  which  gradually  become  paler  and 
paler.  The  disintegrating  bacterial  cells  become  granular  and  finally 
are  completely  dissolved  in  the  peritoneal  fluid.  This  process  usually 
takes  about  twenty  minutes,  provided  the  animal  has  been  sufficiently 
highly  immunized.  For  a  control,  a  like  quantity  of  the  cholera  culture 
is  injected  into  the  peritoneal  cavity  of  a  normal  guinea-pig.  In  this 
case  the  microorganisms  are  not  immobilized,  agglutinated,  or  dissolved. 
Further,  the  immunized  animal  remains  unaffected  while  the  control  ani- 
mal dies  as  a  result  of  the  infection.  This  reaction  is  specific,  that  is, 
a  guinea-pig  immunized  against  cholera  will  immobilize,  agglutinate,  and 
dissolve  only  the  cholera  vibrios;  a  guinea-pig  immunized  with  typhoid 
will  act  upon  typhoid  and  not  upon  cholera. 

It  was  soon  discovered  by  Bordet  that  this  reaction  takes  place  not 
only  in  the  peritoneal  cavity  of  the  immunized  animal,  but  will  occur 
in  the  test  tube  when  the  peritoneal  exudate  or  the  blood  serum  of 
the  immunized  animal  is  mixed  with  the  cholera  organisms.  It  was 
through  a  study  of  this  reaction  that  Pf eiffer  and  KoUe  and  later  Gruber 
and  then  Widal  discovered  and  described  the  ability  of  blood  serum  to 
clump  or  agglutinate  bacteria.  It  seems  evident  that  this  power  of  the 
blood  serum  or  the  peritoneal  exudate  of  the  immunized  guinea-pig  is  an 
important  factor  in  the  mechanism  of  its  immunity. 

Nature  of  Lysins. — Bacteriolysins  are  absolutely  distinct  from  anti- 
toxins and  agglutinins.  Even  when  these  three  substances  coexist  they 
may  be  distinguished  one  from  another  through  appropriate  tests. 
iSTothing  is  known  as  to  their  chemical  composition. 

Any  general  statement  concerning  the  thermal  death  point  or  other 
characters  of  the  lysins  must  be  misleading,  from  the  fact  that  we  now 
know  that  lytic  action  is  always  due  to  a  combination  of  tAvo  substances; 
one  stable,  the  other  unstable;  one  readily  destroyed  by  heat,  the  other 
quite  resistant  to  heat.    This  important  observation  was  made  by  Bordet, 


LYSTNS  577 

who  was  the  first  to  show  that  two  substances  are  necessary  for  the  phe- 
nomenon of  bacteriolysis.  He  considered  that  one  of  these  substances 
sensitized  the  bacteria,  and,  therefore,  called  it  the  "substance  sensibili- 
satriie'' ;  tliis  substance  is  thermostable.  The  other  substance,  which  is 
thermolabile,  he  continued  to  call  alexin.  Bordet  found  that  all  the 
essential  features  of  bacteriolysis  could  be  reproduced  exactly  if  red  blood 
corpuscles  were  substituted  for  the  bacteria.  It  was  this  analogy  between 
bacteriolysis  and  hemolysis  that  led  Ehrlich  to  an  investigation  of  the 
latter  phenomenon,  and  his  researches  led  to  furtlier  light  upon  the 
subject.  Ehrlich  introduced  new  names  for  the  substances  which  Bordet 
had  shown  to  be  necessary  for  the  phenomenon,  and  applied  his  side- 
chain  theory  to  explain  the  reaction. 

Many  names  have  been  given  to  the  two  substances  which  take  part 
in  lysis.  The  thermostable  substance  has  been  called  substance  sensibili- 
satrice,  or  simply  sensibilatrice,  immune  body,  amboceptor,  fixator,  in- 
termediary body,  interbody,  philocytase,  immunisin,  desmon,  copula  and 
preparator ;  while  the  thermolabile  substance  has  been  called  the  alexin, 
complement,  addiment,  and  cytase.  We  shall  speak  of  the  first  as  the 
immune  body  and  the  second  as  the  complement. 

One  of  the  remarkable  facts  connected  with  the  phenomenon  of  the 
lytic  poisons  is  that  the  poison  itself  (complement)  is  normally  pres- 
ent in  the  blood.  This  substance  is  a  fragile  "body,"  readily  destroyed  at 
a  moderate  temperature — 55°  C.  It  disappears  spontaneously  from  the 
scrum  when  kept  for  a  few  days ;  it  is  destroyed  by  acids  and  alkalies  and 
is  not  specific  in  its  action.  Complement  appears  to  be  formed  by  the 
breaking  down  of  the  leukocytes,  which  accounts  for  the  fact  that  blood 
serum  after  clotting  is  much  more  potent  than  the  whole  blood ;  further, 
complement  is  absent  from  fluids  containing  no  leukocytes,  such  as  the 
aqueous  humor.  Complement  exists  in  blood  while  it  is  physiologically 
alive.  It  may  not  be  a  "substance"  in  the  chemical  sense,  but  a  state  of 
colloidal  dispersion  of  the  proteins  of  the  serum. 

According  to  Ehrlich,  the  immune  body  has  two  combining  affinities, 
and,  therefore,  he  called  it  the  amboceptor.  It  unites  on  the  one  hand 
with  the  complement  and  on  the  other  vdth  the  receptor  of  the  cell. 
Bordet,  however,  considers  that  the  cell  unites  directly  but  separately 
with  both  the  complement  and  the  immune  body.  The  immune  body  is 
stable  and  specific ;  it  is  more  stable  than  the  agglutinins  or  even  the  anti- 
toxins. It  is  not  injured  by  heating  to  60°  C,  it  is  weakened  at  7-0°  C, 
and  finally  destroyed  by  prolonged  exposure  at  this  temperature.  •  It  is 
called  the  immune  body  because,  according  to  Ehrlich's  views,  immunity 
can  only  be  obtained  through  it  on  account  of  its  specific  reaction. 

In  bacteriolytic  immunity  it  is  the  immune  body  rather  than  the  com- 
plement that  is  increased. 

Just  what  service  the  lysins  are  in  the  mechanism  of  immunity  is 


578  IMMUNITY 

not  clear.  Recent  studies  indicate  that  they  may  at  times  be  harm- 
ful as  well  as  useful.  Thus,  by  dissolving  the  bacterial  cell  they  have 
the  power  of  releasing  "endotoxins." 

The  studies  upon  anaphylaxis  have  thrown  collateral  light  upon  the 
probable  action  of  the  bacteriolysins  in  the  pathogenesis,  cure,  and  pre- 
vention of  some  infections.  When  the  bacteria  are  dissolved  within  the 
body  the  protein  matter  which  they  contain  is  set  free.  This  may  not  be 
poisonous  in  itself,  that  is,  may  not  have  any  of  the  properties  ordinarily 
attributed  to  the  endotoxins.  This  foreign  bacterial  protein,  however, 
may  sensitize  the  organism  so  that  the  second  time  the  protein  is  lib- 
erated it  may  cause  a  reaction  which  may  account  for  some  of  the  patho- 
genic effects  and  symptoms  of  the  disease. 

Buxton  and  Coleman  explain  the  pathogenesis  of  typhoid  fever  as 
largely  due  to  a  solution  of  the  typhoid  bacilli  within  the  body,  and  it 
is  probable  that  in  pneumonia  and  other  infections  a  like  action  takes 
place.  x\n  organism  that  has  once  reacted  to  a  particular  bacterium 
remains  immune  so  long  as  it  possesses  an  altered  power  of  reaction, 
when  brought  in  association  with  the  microorganism  in  question.  Im- 
munity in  this  sense  is  an  example  of  allergie  and  is  discussed  more  in 
detail  under  anaphylaxis. 

HEMOLYSINS 

Hemolysins  are  substances  that  lake  the  blood;  that  is,  they  dis- 
solve the  hemoglobin  from  the  red  blood  corpuscle  and  set  it  free  in 
solution.  A  certain  part  of  the  stroma  of  the  red  corpuscle  is  also  de- 
stroyed in  complete  hemolysis.  Some  of  the  hemolysins  are  specific  and 
others  are  not.  Thus,  distilled  water  will  dissolve  the  hemoglobin  from 
the  red  corpuscles  of  almost  all  animals.  Other  known  non-specific 
hemolytic  substances  are  various  alkalies  and  acids ;  plant  poisons,  such 
as  ricin  and  abrin;  bacterial  poisons,  such  as  tetanolysin  and  staphyloly- 
sin ;  and  animal  poisons,  such  as  snake  venom,  scorpion  venom,  etc.  The 
specific  hemolysins  are  obtained  by  treating  (i.  e.,  immunizing)  one 
animal  species  with  the  blood  corpuscles  of  another.  For  example,  the 
blood  corpuscles  of  a  guinea-pig  are  injected  into  a  rabbit.  After  several 
such  injections  the  blood  serum  of  the  rabbit  will  contain  hemolytic 
substances  for  the  guinea-pig's  corpuscles.  The  corpuscles  used  for  im- 
munization are  obtained  by  drawing  the  blood  of  the  animal  into  isotonic 
salt  solution  (0.85  per  cent.)  containing  about  1  per  cent,  of  sodium 
citrate,  which  prevents  coagulation.  The  citrated.  blood  is  then  centrif- 
ugalized,  the  supernatant  fluid  drawn  off  and  replaced  with  isotonic  salt 
solution.  This  process  is  repeated  three  or  four  times  and  is  known  as 
washing  the  corpuscles.  The  object  is  to  remove  all  trace  of  serum  con- 
taining complement  and  other  substances.  If  this  is  not  done  the  results 
will  be  unnecessarily  complicated   and  misleading.     The  washed  cor- 


LYSmS  579 

puscles  are  injected  into  the  peritoneal  cavity  about  once  a  week  or  ten 
days  until  the  blood  contains  the  desired  hemolytic  action.  When  this 
point  is  readied  can  only  be  determined  by  withdrawing  small  quantities 
of  the  blood  and  testing  it. 

Hemolytic  tests  are  made  by  adding  together  the  complement  and 
the  immune  l)odies.  The  corpuscles  are  obtained  as  above  described, 
washed  three  or  lour  times,  and  suspended  in  isotonic  salt  solution,  so 
that  they  are  present  in  the  proportion  of  about  5  to  10  per  cent,  by 
volume  of  the  salt  solution.  One  c.  c.  of  this  suspension  is  placed  in  a 
small  test  tube.  To  this  is  then  added  the  immune  body  contained  in 
the  serum  of  the  animal  that  had  been  injected  with  the  corpuscles. 
This  immune  serum  is  first  heated  to  55°  or  56°  C.  for  half  an  hour  in 
order  to  destroy  the  complement.  This  degree  of  heat  does  not  destroy 
the  immune  body.^^  Uniform  amounts  of  the  complement  are  obtained 
by  adding  a  definite  quantity  (0.2  of  a  c.  c.)  of  fresh  serum  to  each  test 
tube..  Each  test  tube  then  contains  a  uniform  quantity  of  the  corpuscles 
to  be  tested,  a  uniform  quantity  of  complement  in  the  fresh  seriim,  and 
a  variable  quantity  of  heated  immune  serum  containing  the  immune 
body.  In  most  cases  normal  saline  solution  is  added  to  bring  the  whole 
up  to  a  definite  volume — say  5  c.  c. 

These  mixtures  are  now  incubated  at  37°  C.  for  two  hours,  being 
stirred  or  shaken  once  or  twice  in  the  meantime.  The  test  tubes  are 
now  removed  and  placed  in  a  vertical  position  in  the  ice  chest  from 
12  to  2-1  hours  and  then  examined.  If  no  hemolysis  has  taken  place 
the  supernatant  fluid  will  be  untinged  and  the  corpuscles  will  have 
settled  in  a  distinct  layer  at  the  bottom.  If  there  is  complete  hemol- 
ysis the  fluid  will  be  deeply  and  uniformly  colored  and  there  will  be 
no  sediment  or  only  a  minute  deposit  of  stromata.  If  the  reaction  is 
partial,  the  fluid  will  be  less  deeply  colored  and  there  will  be  more  or 
less  of  a  deposit  of  undissolved  corpuscles.  It  must  be  remembered 
that  many  bacteria  produce  hemolysis  and  that,  if  the  mixtures  of  cor- 
puscles and  sera  be  incubated  for  long  periods,  fallacies  may  arise  from 
such  contaminations. 

CY TO  TOXIN 8 

If  instead  of  red  blood  cells  an  animal  is  treated  with  the  body 
cells  or  glandular  cells  of  another  species,  it  develops  the  po.wer  to 
dissolve  the  cells  in  question.  This  power  is  contained  in  the  blood 
serum  and  is  brought  about  by  substances  known  as  cytotoxins,  which 
are  entirely  similar  to  the  bacteriolysins,  the  hemolysins,  and  other  lytic 
substances.  Cytotoxins  have  been  obtained  with  the  spleen  (leukocidin), 
with  the  sperm  (spermotoxin),  liver  cells  (hepatotoxin),  kidney  cells 
(nephrotoxin),  gastric  mucosa    (gastrotoxin),  placental  tissue   (syncy- 

^This  degree  of  heat  weakens  the  immune  body  about  25  to  30  per  cent. 


580  IMMUNITY 

tiolysin  or  placentolysin),  prostatic  tissue  (prostatolysin),  brain  (neuro- 
toxin), and  other  organs  and  tissues.  When  the  cytotoxins  were  discov- 
ered they  aroused  great  enthusiasm  in  the  hope  that  it  would  now  be 
possible  to  dissolve  and  destroy  such  foreign  cells  as  cancer  and  other 
tumors  and  pathological  processes  in  which  it  is  desirable  to  get  rid 
of  certain  cellular  elements.  The  practical  results  have  been  exceedingly 
disappointing,  as  further  investigations  have  shown  that  these  cytotoxins 
are  exceedingly  weak  and,  further,  are  not  very  specific. 


THE  BORDET-GENGOU  PHENOMENON— FIXATION  OF 
COMPLEMENT 

Bordet  and  Gengou  ^*  found  that  bacteria  and  also  red  blood  cells 
could  be  "sensitized'^  by  placing  them  in  heated  immune  serum.  The 
immune  serum  is  heated  to  55°  or  56°  C.  in  order  to  destroy  the. com- 
plement, leaving  only  the  thermostable  "substance  sensibilisatrice"  which 
unites  with  the. bacteria  or  the  red  blood  cells,  and  thus  prepares  or 
sensitizes  them  to  the  action  of  the  complement.  If,  now,  these  sen- 
sitized bacteria  or  red  corpuscles  are  added  to  fresh  serum,  all  the  com- 
plement contained  in  the  fresh  serum  is  removed  or  fixed  so  that  the 
fluid  will  no  longer  dissolve  bacteria  or  cells.  These  facts  are  of  very 
great  importance,  and  upon  them  are  based  the  Wassermann  reaction  for 
syphilis  and  other  practical  applications  in  immunology.  The  comple- 
ment fixation  test  is  also  used  in  the  diagnosis  of  gonococcus  infection, 
glanders  (page  399),  streptococcus  infections,  pertussis,  meningitis, 
typhoid  fever,  and  other  infections. 

The  reaction  of  fixation  based  upon  the  work  of  Bordet  and  Gengou 
has  many  useful  practical  applications  in  addition  to  the  Wassermann 
reaction  for  the  diagnosis  of  syphilis.  If  either  the  antigen  or  the  anti- 
body are  unknown,  their  presence  may  be  determined  through  the  re- 
action of  fixation,  because  it  is  strictly  specific.  The  problem  is  some- 
thing like  the  theorem  in  geometry  with  the  triangle;  two  sides  and  an 
angle  of  a  triangle  being  known,  the  other  side  and  angles  may  be 
determined. 

The  antigen  is  any  substance  which,  when  injected  into  a  suitable 
animal,  has  the  power  of  generating  an  antibody.  Practically  all  patho- 
genic bacteria  and  pathogenic  protozoa  act  as  antigens ;  many  albuminous 
bodies,  such  as  the  venoms,  the  enzymes,  and  bland  proteins,  may  also 
act  as  antigens.  As  the  reaction  is  specific,  it  is  possible  to  determine 
whether  a  particular  microorganism  is  the  true  cause  of  a  disease  or  not. 

^^  Bordet:  Ann.  de  I'Inst.  Pasteur,  Vol.  XIV,  1900,  p.  257;  Vol.  XV,  1901, 
p.  289. 

Gengou:     Ann.  de  I'Inst.  Pasteur,  Vol.  XVI,  1902,  p.  734. 

Bordet  and  Gengou:     Compte  rendu  Acad.,  Vol.  CXXXVII,  p.  351. 


THE  BORDET-GENGOU   IMIEXOMENOX  581 

Thus,  Bordet  was  enabled  to  satisfy  himself  that  the  Ijucilhis  which  he 
isolated  during  the  early  stages  of  whoopiiig-cougii  was  tlie  true  cause 
of  that  disease,  as  it  gave  tlie  reaction  of  fixation  with  a  specific  antibody. 
On  tlie  otlier  hand,  it"  the  antigen  is  known,  the  diagnosis  may  be  made 
througii  the  reaction  of  fixation,  as  in  tlie  case  of  sy])hilis  and  the  Wasser- 
mann  reaction.  Coniplenient  fixation  is  used  to  show  generic  differences 
between  bacteria,  whereas  agghitinins  at  most  show  specific  differences. 

Tlie  Wassermann  reaction  for  syphilis  is  a  special  method  of  applica- 
tion of  the  Hor(h't-(iengou  phenomenon. 

The  following  is  a  brief  description  of  llie  Wassermann  reaction  as 
carried  out  for  the  j\lassachusctts  State  Department  of  Health,  by  Dr.  W. 
A.  Hinton,  under  my  direction. 

Two  antigens  are  used :  one  is  an  alcoholic  extract  prepared  from 
liunian  heart  muscle  and  half  saturated  with  cholesterin  at  17°  C,  the 
other  is  prepared  in  like  manner  from  guinea-pig  hearts.  Each  of  these 
antigens  is  diluted  with  0.85  per  cent,  salt  solution  before  testing,  in 
the  proportion  of  -i  parts  of  the  antigen  extract  to  16  parts  of  0.85  per 
cent,  salt  solution.  The  amount  to  be  used — the  dosage — is  carefully 
determined  by  testing  each  antigen  against  a  large  number  of  known 
positive  and  known  negative  specimens  of  blood.  Any  antigen  which 
gives  a  positive  reaction  with  a  known  negative  specimen  of  blood  ("false 
positive")  is  unsuitable  for  testing  and  should  be  rejected.  Further,  it 
is  unsafe  to  employ  an  antigen  when  twice  its  dosage  inhibits  hemolysis 
when  incubated  for  1  hour  with  "the  hemolytic  system"  consisting  of 
complement,  and  the  hemolytic  mixture.^^  (See  Antigen  Control  in  table 
on  Wassermann  Test.)  Usually  0.1  c.  c.  to  0.2  c.  c.  of  the  diluted  antigen 
is  used.    Lecithin  and  other  lipoidal  substances  may  also  act  as  antigen.'^ 

Syphilitic  antibody  in  the  patient's  serum  to  be  tested  is  the  unknown 
quantity.  This  serum  is  heated  in  a  water  bath  at  55°  C.  for  30  minutes 
to  destroy  its  complement.  One-tenth  cubic  centimeter  of  the  patient's 
serum  is  used  in  the  test  and  0.2  cubic  centimeter  is  used  for  the  serum 
control.  The  serum  control  indicates  the  presence  or  absence  of  inhibit- 
ing (anticomplementary)   substance  other  than  specific  antibodies. 

The  complement  is  contained  in  the  serum  of  freshly  drawn  guinea- 
pig's  blood  which  has  been  kept  at  37°  C.  for  one  to  two  hours.  A  10 
per  cent,  solution  of  this  serum  in  salt  solution  constitutes  the  comple- 
ment. The  amount  used  in  the  test  is  twice  the  minimum  necessary 
to  hemolyze  a  definite  quantity  of  sensitized  cells.  Usually  this  is 
from  0.4  to  0.5  c.  c.  of  the  complement. 

Vt" ashed  corpuscles  are  prepared  from  freshly  obtained  defibrinated 

^°  Also  known  as  sensitized  red  blood  cells. 

^'In  routine  examinations  upon  a  large  number  of  specimens  it  is  better  to 
test  all  specimens  first  with  a  cholesterinized  alcoholic  extract  prepared  from 
guinea-pig  hearts  (this  antigen  being  more  sensitive  to  syphilitic  antibody),  and 
then  retest  the  positives  with  the  same  antigen  and  also  with  an  antigen  pre- 
pared from  a  cholesterinized  alcoholic  extract  of  human  heart  muscle. 


583 


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THE  NEISSER-WECHSBERa  PHEXOMENON  583 

sheep's  blood.  In  order  to  free  the  corpuscles  of  serum,  tlie  blood  is 
washed  three  times  witli  from  four  to  five  volumes  of  physiological  salt 
solution  at  eacb  \vasbin<T^.  Finally  the  volume  of  cells  and  salt  solution 
ds  made  equal  to  tiie  volume  of  deiibrinated  blood  originally  used.  Such 
a  suspension  is  called  washed  sheep's  corpuscles  from  which  the  5  per 
cent,  suspension  for  the  test  is  prepared. 

Immune  rahhil's  serum  is  prepared  by  injecting  washed  sheep's  cor- 
puscles into  the  peritoneal  cavity  of  a  raljbit  at  three-day  intervals, 
namely,  first  injection,  7  c.  c. ;  second,  14  c.  c. ;  third,  21  c.  c. ;  and 
finally,  28  c.  c.  The  rabbit  is  bled  on  the  9th  or  10th  day  after  the 
last  injection  and  the  clear  serum  obtained  from  its  blood  is  heated 
in  a  water  l)ath  at  55°  C.  for  ojfie-half  hour  to  destroy  complement.  This 
heated  raljbit's  serum  contains  the  amboceptor  and  is  diluted  with  0.85 
per  cent,  salt  solution,  so  that  0.25  c.  c.  will  liemolyze  0.5  c.  c.  of  a 
5  per  cent,  suspension  of  sheep's  corpuscles.  In  the  test  0.5  c.  c.  of  the 
diluted  amboeei)tor  is  used.  A  small  quantity  of  the  rabbit's  serum  is 
freshly  diluted  for  each  day's  test. 

The  liemolijtic  mixture,  or  sensitized  cells,  consists  of  equal  parts  of  a 
5  per  cent,  suspension  of  washed  sheep's  corpuscles  and  the  diluted 
amboceptor  which  have  been  incubated  together  in  a  water  bath  at  37°  C. 
for  one-half  hour  completely  to  sensitize  the  red  corpuscles.  One  c.  c. 
of  sensitized  cells  is  used  in  the  test. 

The  Test. — Mix  the  patient's  serum  or  spinal  fluid  with  the  antigen 
and  the  complement,  according  to  the  table  on  page  582.  The  tubes  are 
well  shaken  and  the  whole  is  incubated  at  37°  C.  for  40  minutes.  At  the 
end  of  this  time  all  of  the  complement  has  been  fixed  in  those  tubes 
which  contain  syphilitic  antibody,  antigen  and  complement.  Finally, 
1  c.  c.  of  sensitized  cells  is  added  to  each  tube  and  the  whole  again  in- 
cubated at  37°  C.  for  one  hour.  The  results  of  the  Wassermann  test 
are  then  read. 

The  absence  of  hemolysis  indicates  the  presence  of  syphilitic  anti- 
body in  the  patient's  serum,  and  therefore  a  positive  reaction.  The 
presence  of  hemolysis  indicates  the  absence  of  syphilitic  antibody  in  the 
patient's  serum,  and  therefore  a  negative  reaction.  Partial  hemolysis 
signifies  a  doubtful  reaction.  It  is  advisable  to  test  several  specimens 
from  such  a  case,  and  to  interpret  a  persistently  or  predominatingly 
doubtful  reaction  as  indicative  of  a  syphilitic  infection. 

THE  NEISSER-WECHSBERG  PHENOMENON  OR  DEVIATION 
OF  THE  COMPLEMENT 

Neisser  and  Wechsberg  in  1901  "  found  that,  although  the  addition 
of  a  small  amount  of  immune  serum  renders  normal  serum  more  bac- 
^^  Miinch.  med.  Wochenschr.,  1901,  No.  18. 


584 


IMMUNITY 


tericidal  or  increases  its  power  of  protection,  a  greater  addition  robi? 
it  of  most,  and  sometimes  of  all,  of  its  bactericidal  power.  In  other 
words,  the  solvent  effect  of  the  immune  body  on  cells  or  bacteria  in 
the  presence  of  complement  diminishes  as  an  excess  of  the  immune 
body  is  added.  This  particular  action  is  explained  by  Neisser  and 
Wechsberg  as  due  to  a  locking  up  or  deviation  ( Ahlenkung )  of  the  com- 
plement which  is  brought  about  by  an  excess  of  the  immune  body.    The 


Diagram    Illustrating  Deviation  of  Complemeint 

(Neisser  Wechsberg  Phenomenon) 

Test 

A 
BACTERIA 

5ame  number 
in  each  l&st. 

B 

Complement 

Same  amount 
in  each  Test 

c 

Amboceptor 

Variable  amount  of  tmnunc 
Serium  in  each  Test 

Combine 

A  Band  C 

Result 

I 

Hill 

vtixmixj 

P 

g\y\y\7t^ 

Few  or  no 
baderia  killed, 

E 

III 

Xl'^XltJtl 

CO  CO  CO  CO  CO 

Wfff 

All  bacteria 
killed. 

IE 

II    1 

V^\!Jt/t/ 

CO  CO  CO  CO  CO 
CO  CO  CO  CO  CO 

cpMcpB 

(jocpSSco 

Few  or  no 
bacteria  killed 
because  the 
Complement  is 
deviated  by  the 
excess  of 
.Amboceptor, 

Fig.  61. 

phenomenon  is  better  understood  from  a  study  of  an  example  given  by 
ITeisser : 

(1)  Bacteria+l  unit  immune  serum  ^^  4"Complement=:little  or  no 
destruction  of  the  bacteria. 

(2)  Bacteria+5  units  immune  serum -f- complement  ^complete  de- 
struction of  the  bacteria. 

(3)  Bacteria-|-10  units  immune  serum -[-complement=no  destruc- 
tion of  the  bacteria. 

''  Containing  amboceptor. 


PRECIPITINS  585 

III  ilu'  nbovc  c'Xpcn'iiiriii  i(  is  necessary  ilial  the  tiiinihcr  of  bacteria 
and  the  ainoiiiit  (if  coiiipleinent  shall  reinaiji  practically  the  same  in 
all  three  tests.  The  innnuiie  scrum  is  the  only  factor  that  should 
vary. 

In  (1),  few  or  no  bacteria  are  killed  because  there  arc  not  enough 
immune  bodies  (amboceptors)  to  unite  the  complement  to  the  bacteria. 

In  (2),  the  proper  proportion  of  amboceptors  and  complement  occurs 
so  that  all  the  bacteria  are  killed. 

In  (3),  few  or  no  bacteria  are  killed  for  the  reason  that  the  comple- 
ment is  deviated  by  the  excess  of  amboceptors. 

The  action,  therefore,  while  specific,  is  strictly  quantitative,  depend- 
ing upon  the  amount  of  amboceptors  present.  This  explains  why  an 
immune  serum  may  be  effective  in  certain  infections  if  the  proper  dose 
is  used,  but  large  amounts  of  immune  serum  may  be  ineffective  in  con- 
trolling the  course  of  the  disease. 

Isohemolysins  have  the  property  of  destroying  the  red  blood  cells  of 
the  same  species.  They  occur  naturally  in  certain  animals,  principally  in 
the  horse  and  in  man.  They  may  also  be  produced  experimentally  in 
certain  animals,  as  in  goats,  by  the  injection  of  the  blood  of  other  goats. 
There  is  further  the  possibility  that  autohemolysins  may  be  produced 
which  destroy  the  blood  cells  of  the  individual  himself.  These  have  not 
been  produced  artificially,  but  are  said  to  occur  in  paroxysms  of  hemo- 
globinuria. The  subject  of  isohemolysins  is  of  importance  in  trans- 
fusion. 

PRECIPITINS 

Another  class  of  immune  bodies  known  as  the  precipitins  may  readily 
be  produced  in  the  blood  serum  of  animals  by  the  injection  of  bacteria 
or  albuminous  substances  having  this  antigenic  property.  The  precipi- 
tating action  of  immune  sera  was  discovered  by  R,  Kraus  in  1897. 
When  the  clear  antiserum  is  added  to  the  clear  antigen  in  solution,  the 
mixture  of  the  two  fluids  becomes  opalescent,  then  opaque  from  the 
formation  of  a  precipitate,  and  after  a  time  this  settles  to  the  bottom 
of  the  test  tube,  leaving  a  clear  supernatant  fluid.  One  theory  of  pre- 
cipitins is  that  the  precipitate  consists  of  a  combination  of  two  sub- 
stances, one  of  which  is  present  in  the  immune  serum  and  the  other  in 
the  antigen.  A  more  likely  theory  is  that  the  precipitate  is  coriiposed 
of  the  globulin  of  the  immune  serum  which  comes  doAvn  due  to  a  change 
in  the  electric  charge.  This  insoluble  precipitate  is  known  as  the  pre- 
cipitum.  The  substance  in  the  antigen  is  known  as  the  precipitable 
substance  or  precipitinogen,  and  the  substance  in  the  antiserum  is  called 
the  precipitin.  Precipitums  are  doubtless  formed  within  as  well  as 
without  the  body  when  proper  conditions  of  antibody  and  antigen  are 


586  iMMTJKITY 

present.     The  reaction,  however,  may  not  be  massive  enough  to  cause  a 
visible  precipitum. 

The  precipitins  are  quite  analogous  to  the  agglutinins,  and  from  the 
standpoint  of  physical  chemistry  are  often  classified  with  them.  It  is 
now  known  that  proteins  do  not  form  true  solutions,  but  molecular  or 
colloidal  suspensions.  The  effect  of  the  addition  of  a  precipitin  is  to 
cause  the  agglutination  of  particles.  According  to  Emery,  the  laws  which 
govern  the  action  of  the  precipitins  and  agglutinins  are  entirely  similar, 
and  theoretically  it  would  probably  be  more  accurate  to  consider  them, 
under  one  head.  The  practical  applications  of  the  two  classes  of  anti- 
bodies are,  however,  very  different,  and  it  is  more  convenient  to  treat 
them  as  separate  phenomena. 

Precipitins  as  well  as  agglutinins  probably  act  by  change  of  surface 
tension  and  alteration  of  the  electric  charge  of  the  particles. 

The  bacterial  precipitins  were  those  first  discovered.  Kr^us  added 
some  typhoid  serum  to  a  filtered  culture  of  typhoid  bacilli  and  obtained 
a  precipitate  when  the  two  clear  solutions  were  brought  together.  The 
same  happens  with  cultures  of  cholera,  plague,  and  other  bacteria  with 
corresponding  antiserum.  Certain  bacteria,  however,  do  not  produce  a 
precipitable  substance.  This  is  notably  the  case  with  diphtheria.  Thus, 
when  diphtheria  antitoxin  is  added  to  diphtheria  toxin,  no  visible  reac- 
tion takes  place. 

Tsistowitch  in  1899  found  that  precipitins  may  be  produced  by 
injecting  albuminous  substances  into  suitable  animals.  Thus,  if  rabbits 
are  injected  with  horse  serum  or  with  eel's  blood,  the  blood  serum  of 
the  treated  rabbit  will  precipitate  the  blood  serum  of  the  horse  or  the 
eel's  blood  respectively.  This  reaction  is  used  in  forensic  medicine  for 
the  recognition  of  blood  stains,  which  will  presently  be  discussed.  The 
chemical  nature  of  the  precipitins  is  not  known.  They  come  down  with 
the  globulins.  In  the  terms  of  the  side-chain  theory  they  contain  two 
groups,  one  a  thermostable  haptophore  or  combining  group,  the  other  a 
thermolabile  functioning  group.  Precipitins  are  destroyed  by  heat 
(6Q°-70°  C),  light,  moisture,  and  other  external  influences  about  as 
readily  as  the  agglutinins.  Precipitating  sera  should,  therefore,  be  kept 
in  a  dry  state,  in  a  cool  place,  and  preserved  from  light.  A  proprecipi- 
toid  zone  entirely  analogous  to  the  proagglutinoid  zone  is  observed  under 
certain  conditions.  Precipitins,  like  agglutinins,  act  more  quickly  at  the 
body  temperature  and  require  the  presence  of  certain  salts  for  their  ac- 
tion. According  to  Priedemann,  the  amount  of  precipitum  formed 
depends  on  the  quantity  of  the  salts  present. 

The  relation  of  precipitins  to  immunity  is  not  entirely  clear.  There 
is  a  strong  suspicion  that,  like  all  antibodies,  they  play  some  part  in 
the  mechanism  of  immunity  in  certain  infections,  but  just  what  part 
is  obscure.     It  is  quite  evident  that  the  presence  of  precipitins  in  the 


PRECIPITINS  587 

blood  must  have  valuable  protective  properties  against  the  poisons  of 
certain  infections.  The  immunity  in  this  case  would  be  due  to  the  throw- 
ing out  of  "solution''  of  the  poison,  thus  rendering  it  insoluble  and  in- 
active. 

Nuttal  in  his  "Blood  Relationship'*  made  a  very  careful  study  of  the 
question  of  specificity  of  the  precipitins. 

He  showed  that  the  reaction  of  the  precipitins,  like  the  reaction  of 
other  similar  antibodies,  is  relatively  specific  or  quantitatively  specific. 
If  the  antiserum  is  powerful  enough  it  will  react  with  all  the  bloods 
of  animals  in  the  same  great  division  of  the  animal  kingdom.  Thus, 
a  strong  antihuman  serum,  that  is,  a  serum  obtained  by  injecting  human 
blood  into  rabbits,  will  give  a  precipitate  when  this  rabbit  serum  and 
human  serum  are  brought  together;  it  will  also  react  with  apes,  monkeys, 
etc.,  but  not  in  such  high  dilutions,  and  a  slight  trace  of  precipitum 
appears  after  a  long  period  even  when  mixed  with  the  serum  of  more 
remote  mammalia,  but  no  precipitate  occurs  with  the  blood  of  birds, 
fishes,  etc.  A  quite  similar  relationship  holds  with  lactosera  and  with  the 
precipitating  sera  for  muscle  proteids;  the  antisera  for  egg  proteids  are 
apparently  less  specific.  Precipitins,  then,  are  not  specific  as  regards  the 
animal  species  from  which  they  are  derived,  but  possess  that  partial 
specificity  seen  in  the  cytotoxins  and  in  the  group  reaction  of  the  agglu- 
tinins. According  to  Emer}^,  they  are  specific  as  regards  the  antibodies 
which  bring  them  into  existence,  irrespective  of  the  source  from  which 
the  antigen  is  derived.  For  medico-legal  purposes  the  specificity  of  the 
reaction  may  be  considered  satisfactory,  provided  the  tests  are  made 
quantitatively,  in  which  case  the  reaction  is  both  specific  and  delicate.  In 
fact,  the  delicacy  of  the  reaction  is  truly  astonishing.  Thus,  Ascoli  ob- 
tained an  anti-egg  albumin  serum  which  gave  a  precipitate  with  1- 
1,000,000  dilution  of  egg  albumin ;  and  Stern  an  antihuman  serum  which 
reacted  with  serum  at  a  dilution  of  1-50,000.  While  these  are  extreme 
figures,  it  is  not  unusual  to  obtain  precipitates  in  dilutions  of  1-5,000. 

The  practical  application  of  precipitins  is  limited.  The  test  is  es- 
pecially used  to  differentiate  t}^es  of  pneumococci.  It  is  also  used  to 
determine  the  presence  and  variety  of  bacterial  substances  in  excretions, 
exudates  and  lesions.  Thus,  in  lobar  pneumonia  considerable  soluble 
products  of  the  pneumococcus  are  found  in  the  lungs,  sputum,  blood  and 
urine.  Precipitins  are  also  of  practical  use  in  forensic  medicine  as  a 
test  for  blood,  meat  and  other  products. 

Tests  for  Blood. — In  carrying  out  the  precipitin  tests  for  the  recog- 
nition of  blood  stains,  as  suggested  by  Uhlenhuth  and  Wassermann,  it  is 
necessary  first  to  obtain  an  antiserum.  This  is  usually  gained  from  rab- 
bits, which  are  injected  intiavenously  or  intraperiloneally  at  intervals  of 
three  or  four  days  with  human  serum.  The  human  serum  may  readily 
be  obtained  by  puncturing  a  vein  at  the  bend  of  the  elbow,  or  from  the 


588  IMMUNITY 

placenta,  or  from  a  cadaver;  pleuritic  or  ascitic  fluid  may  also  be  used. 
The  amount  injected  rises  from  1  to  3  or  4  c.  c.  in  the  case  of  intravenous 
injections,  or  twice  as  much  or  even  more  into  the  peritoneum.  The 
course  of  treatment  lasts  three  or  four  months.  A  simpler  method  is  to 
give  larger  doses  up  to  10  c.  c.  or  more  intraperitoneally  at  intervals  of  a 
week.  The  intervals  should  not  be  longer  than  this,  for  danger  of 
complicating  anaphylactic  reactions.  The  blood  may  be  drawn  from  a 
vein  or  the  heart  of  the  rabbit  from  time  to  time  as  needed,  or  the  ani- 
mal may  be  chloroformed  and  exsanguinated  through  the  carotid  artery, 
or  as  much  blood  as  possible  may  be  collected  from  the  heart. 

The  blood  to  be  tested  is  usually  in  the  form  of  clots  or  stains,  usu- 
ally upon  linen,  or  pistols,  or  other  objects.  These  stains  are  macerated 
with  normal  saline  solution  or  with  1  per  cent,  sodium  hydrate.  In 
the  case  of  very  old  stains  Zienka  recommends  the  use  of  a  strong 
solution  of  potassium  cyanid  which  is  subsequently  neutrali'zed  with 
tartaric  acid.  The  fluid  is  then  examined  with  the  microscope  and 
tested  spectroscopically  to  determine  the  presence  of  blood  corpuscles 
and  pigments,  so  as  to  be  sure  we  are  really  dealing  with  blood.  The 
solution  is  then  filtered.  In  order  to  determine  the  approximate  strength 
of  the  solution  it  is  sufficient  to  bubble  air  through  the  fluid.  A  dilu- 
tion of  blood  serum  in  the  proportion  of  1-1,000  will  produce  a  stable 
foam.  If  a  stable  foam  is  not  produced  it  indicates  that  the  protein 
material  has  not  actually  passed  into  solution  or  is  too  dilute  to  be 
of  service  in  the  test.  Three  tests  are  made.  In  the  first  tube  one 
part  of  the  fluid  under  examination  is  mixed  with  tAvo  parts  of  the 
antiserum,  the  second  contains  the  fluid  alone,  and  the  third  antiserum 
plus  normal  saline  solution.  Further  controls  in  which  the  antiserum 
is  mixed  with  diluted  serum  from  animals  other  than  man  may  also 
be  made.  The  tubes  are  then  incubated  at  37°  C.  and  examined  from 
time  to  time.  A  positive  result  is  obtained  if  there  is  a  precipitate  in 
the  first  tube  and  not  in  the  others.  In  case  a  precipitate  is  obtained 
further  tests  are  then  made  with  greater  dilutions.  V7ith  a  powerful 
antiserum  a  reaction  may  usually  be  obtained  in  dilutions  so  high  that 
evidence  of  the  presence  of  proteids  is  barely  obtainable  by  ordinary 
chemical  means.  The  weak  point  in  the  method  is  that  it  is  never  possi- 
ble to  say  exactly  how  much  of  the  protein  matter  of  the  clot  has  been 
dissolved,  and  thus  it  is  not  possible  to  obtain  precise  quantitative  results. 
With  an  unknown  blood  serum,  unaltered,  and  in  the  fluid  state  the 
test  can  be  carried  out  with  almost  complete  certainty,  but  this  is  rarely 
if  ever  possible  in  medico-legal  cases. 

Another  test  for  blood  has  been  introduced  by  ISTeisser  and  Sachs  and 
based  on  the  Gengou  reaction  of  fixation  of  the  complement.  The 
test  is  extraordinarily  sensitive.  ISTeisser  and  Sachs  found  that  one- 
millionth  part  of  a  cubic  centimeter  of  human  serum  is  readily  demon- 


AGGLUTININS  589 

strable.  The  technie  is  (•oiii])Iif'at(.'(l,  and,  according'  to  Emery,  it 
appears,  moreover,  tliat  complement  may  be  extracted  in  an  altogether 
non-specific  manner  by  substances  other  than  the  combination  of  anti- 
gen and  antibody.  Another  serious  objection  is  that  a  similar  deviation 
of  the  comi)lement  may  be  brought  about  by  means  of  sweat,  so  that 
if  the  reaction  were  obtained  in  a  stain  on  body  linen  it  would  be  of 
doubtful  significance. 

The  precipitin  reaction  further  finds  practical  application  in  deter- 
mining the  nature  of  meat,  whether  fresh,  as  in  the  case  of  beef  sus- 
pected to  be  horse  flesh,  or  prepared,  as  in  sausages,  etc.  For  these 
tests  the  antiserum  is  prepared  by  injecting  rabbits  with  meat  juices 
or  an  unheated  watery  extract  of  the  meat,  and  the  test  is  carried 
out  on  lines  similar  to  those  described  above. 


AGGLUTININS 

Agglutinins  were  definitely  described  in  1896  by  Gruber  and  Dur- 
ham, and  a  few  days  later  by  Pfeiffer  and  Kolle.  Shortly  thereafter 
Widal  announced  the  fact  that  the  blood  serum  of  a  typhoid  patient 
will  agglutinate  the  typhoid  bacillus  in  high  dilutions.  The  phenom- 
enon of  agglutination  with  special  reference  to  typhoid  fever  is,  there- 
fore, often  called  the  Widal  reaction  or  the  Gruber  reaction.^^ 

Agglutination  consists  in  a  clumping  or  grouping  of  the  bacteria 
into  clusters,  just  as  though  they  were  iron  filings  drawn  about  a  mag- 
netic point.  Usually  they  are  immobilized  before  they  are  drawn  to- 
gether into  a  clump  or  cluster.  Theobald  Smith  has  shown  that  the 
first  phenomenon,  the  immobilization  of  bacteria,  may  be  due  to  a 
flagellar  agglutinin,  and  that  the  second  phenomenon,  the  clumping, 
may  be  due  to  a  cellular  agglutinin. 

The  agglutination  of  bacteria  apparently  does  little  harm  to  them 
other  than  rendering  them  motionless,  for  they  are  not  altered  in  ap- 
pearance, viability,  or  virulence.  Bacteria  that  have  been  agglutinated 
may  again  multiply  and  grow  vigorously;  in  fact,  agglutination  may  be 
an  important  source  of  error  in  counting  the  number  of  bacteria  in  any 
fluid.  A  cluster  will  develop  into  one  colony  and  thereby  give  misleading 
results.  The  apparent  diminution  in  the  number  of  bacteria  in  freshly 
drawn  milk,  judged  by  the  number  of  colonies  that  develop  upon  agar 
plates  and  known  as  the  germicidal  property  of  milk,  is  largely  a  phe- 
nomenon of  agglutination. 

'*  The  phenomenon  of  agglutination  had  been  previously  observed  by  Charrin 
and  Eoger  in  1899  in  the  case  of  the  Bacillus  prjocyaneus.  It  Avas  also  observed 
by  Metchnikoff  in  the  case  of  the  Yihrio  metchnikovi  in  1891.  Similar  appear- 
ance had  also  been  seen  by  Issaeff  in  1893. 


690  IMMUNITY 

Agglutination  may  occur  quickly  or  slowly,  depending  upon  the 
temperature,  the  dilution  of  the  serum  or  fluid  containing  the  agglu- 
tinin, and  upon  other  factors;  hence,  it  is  important  in  reporting  posi- 
tive or  negative  tests  in  the  diagnosis  of  typhoid  fever,  malta  fever, 
and  .other  infections  always  to  state  the  dilution,  the  time,  the  tem- 
perature, and  other  conditions  under  which  the  test  was  made.  The 
interpretation  of  the  results  may  depend  upon  these  factors. 

Macroscopic  Method. — Agglutination  may  readily  be  seen  by  the 
naked  eye.  A  uniform  suspension  of  bacteria  in  a  test  tube  under  the 
action  of  an  agglutinin  first  becomes  granular;  the  granules  increase  in 
size  and  flock  into  masses  with  intervening  clear  spaces.  Then  these 
flocculi  settle  to  the  bottom  as  a  precipitate,  leaving  the  supernatant  fluid 
clear. 

Microscopic  Method. — Under  the  microscope  the  bacteria  are  first 
seen  to  lose  their  motion,  then  to  be  drawn  together  into  irregulaj  clumps 
or  clusters,  which  increase  in  size.  The  macroscopic  method  gives  higher 
titers  in  testing  agglutinins  than  the  microscopic  method.  The  latter 
is  subject  to  several  sources  of  error,  and  the  end  point  is  not  as  sharply 
defined  as  in  the  macroscopic  method. 

Agglutination,  like  almost  all  chemical  processes,  takes  place  more 
quickly  when  warm  than  in  the  cold.  The  reaction  is  accelerated  by  heat 
up  to  56°  C.  The  clumping  usually  takes  place  more  slowly  with  the 
non-motile  bacteria.  Capsulated  bacteria  .  are  peculiarly  insusceptible 
to  the  ordinary  agglutinating  powers  of  immune  serum.  Certain  strains 
of  some  species  of  bacteria  agglutinate  more  reactily  than  others.  Thus, 
the  typhoid  bacillus  is  usually  agglutinated  readily  with  its  specific 
serum,  but  some  strains  are  agglutinated  with  considerable  difficulty; 
in  general,  when  first  isolated,  they  resist  agglutination.  This  resistance 
or  "immunity"  of  the  microorganism  usually  wears  ofl^  after  a  number 
of  subcultures.  A  very  interesting  phenomenon  in  agglutination  which 
has  considerable  practical  importance  is  the  so-called  proagglutinoid 
zone;  that  is,  bacteria  sometimes  will  not  agglutinate  in  a  stronger  di- 
lution, whereas  they  agglutinate  readily  in  a  weaker.  The  proagglu- 
tinoid zone  is  occasionally  found  with  the  typhoid  bacillus,  but  especially 
with  the  Micrococcus  melitensis.  Thus,  this  coccus  may  give  no  reaction 
in  a  dilution  between  1-10  and  1-100,  whereas  it  will  clump  strongly  at 
1-200  and  higher. 

Agglutinins  are  not  very  resistant  to  light,  putrefactive  processes, 
and  dryness.  They  are  very  active  at  a  temperature  of  55°  to  56°  C, 
but  are  destroyed  at  65°  to  70°  C.  They  are  very  sensitive  to  acids;  they 
are  partially  held  back  by  a  Pasteur-Chamberland  filter;  they  are  not 
dialyzable.  They  may  be  preserved  for  a  very  long  time  in  dried  serum 
protected  from  light  and  moisture. 

The  chemical  composition  of  the  agglutinins  is  not  known.     Like 


AGGLUTININS  591 

antitoxin  and  other  antibodies,  they  come  down  with  the  globulins  when 
procijiitated  witli  aninionium  sul])hato.  They  unite  directly  with  the 
bacteria  or  otlier  cells  and,  according  to  Ehrlich,  contain  both  a  hap- 
tophore  and  an  "agghitinophore"  group. 

Agglutination  is  not  a  vital  phenomenon  of  bacterial  activity.  The 
microcirganisnis  play  a  purely  passive  role.  Dead  bacteria  agglutinate 
readily.  l)()r(K't  showed  conclusively  that  agglutination  is  a  physical 
phenomenon,  and  that  the  combination  of  antigen  and  antibody  is  one 
phase  and  the  agglutination  another. 

Agglutinins  may  readily  be  produced  by  injecting  either  live  or 
dead  bacterial  cells  into  a  suitable  animal.  The  injections  may  be  given 
either  subcutaneously,  intravenously,  intraperitoneally  or  the  micro- 
organisms may  be  rubbed  upon  the  closely  shaven  skin.  Agglutinins 
may  even  be  produced  by  giving  the  microorganisms  by  the  mouth. 
Agglutinins  in  highest  concentration  may  be  obtained  by  repeated  in- 
jections, every  10  or  12  days,  continued  over  a  long  period  of  time. 
In  experimental  work  in  the  laboratory  rabbits  are  suitable.  Three 
or  four  injections  into  the  ear  vein  of  the  rabbit,  spaced  at  intervals 
of  8  or  10  days  with  cultures  of  cholera  or  typhoid,  will  develop  ag- 
glutinins in  the  blood  serum  when  diluted  as  high  as  1  to  5,000  or  1  to 
10,000.  Where  large  amounts  are  needed  the  horse  is  the  most  suitable 
animal.  Agglutinins  are  also  produced  in  man  by  the  inoculation  of 
bacterial  vaccines. 

Agglutinins  also  appear  spontaneously  in  attacks  of  certain  infec- 
tious diseases  and  continue  in  the  blood  for  some  time  after  convales- 
cence. In  typhoid  fever  they  appear  about  the  end  of  the  first  week. 
They  are  usually  weak  at  first,  clumping  the  typhoid  bacilli  in  a  dilu- 
tion of  1-30  in  one  hour  at  the  body  temperature,  and  increase  with 
the  progress  of  the  disease,  so  that  the  serum  may  agglutinate  in  dilu- 
tions of  1-1,000  or  more.  In  malta  fever  agglutinins  appear  about  the 
fifth  day  of  the  disease  and  may  develop  in  large  amount.  Thus,  the 
blood  serum  from  a  case  of  malta  fever  may  agglutinate  the  Micrococcus 
melitensis  in  dilutions  as  high  as  1-500,000.  Agglutinins  may  also  de- 
velop in  cholera,  dysentery  and  many  other  diseases.  The  reaction  of  ag- 
glutination is  not  only  practical  as  an  aid  to  diagnosis  of  disease,  but  is 
of  considerable  practical  use  as  an  aid  in  recognition  of  the  bacteria 
themselves.  Agglutination  is  usually  regarded  as  diagnostic  of  races  or 
strains  of  bacteria;  at  most  it  distinguishes  one  species  from  aiiother; 
while  complement  fixation  distinguishes  genera. 

The  reaction  of  agglutination  is  not  absolutely  specific ;  thus,  a  ty- 
phoid agglutinin  will  occasionally  clump  proteus  or  other  not  very 
closely  related  microorganisms.  Thus,  Frost  found  a  Psedomonas  protea 
in  the  Potomac  Eiver  water  that  showed  quite  constantly  the  char- 
acteristic  of  being   agglutinated   by   specific   typhoid   immune    serum. 


593  IMMUNITY 

However,  when  animals  were  injected  with  the  Ps.  protea  they  developed 
agglutinins  for  this  organism,  but  not  for  the  B.  typhosus.  Further, 
there  is  the  phenomenon  of  group  agglutination  or  group  reaction; 
that  is,  typhoid  serum  will  clump  the  colon  bacillus,  the  paratyphoid, 
the  paracolon  bacillus,  and  other  related  organisms.  However,  this 
occurs  only  in  slightly  diluted  serum.  The  reaction  is,  therefore,  specific 
in  a  quantitative  sense.  Thus,  a  strong  cholera  or  typhoid  serum  will 
agglutinate  these  organisms  in  dilutions  of  1-1,000  and  over,  whereas 
the  group  reactions  occur  in  dilutions  of  about  1-50  or  less.  It  is  very 
important  to  remove  the  group  agglutinins  by  absorption  before  giving 
a  judgment  concerning  the  specificity  of  any  given  reaction. 

The  difference  between  specific  and  group  agglutinins  may  be  ac- 
curately determined  by  Castellani's  method,  known  as  the  absorption  of 
agglutinins.  The  specific  agglutinins  may  be  absorbed  from  the  serum, 
leaving  the  group  agglutinins,  or  vice  versa.  The  specific  agglutinins 
can  only  be  absorbed  by  the  specific  antigen — therefore,  absorption  re- 
sults are  of  value  only  when  we  possess  the  specific  bacterium  in  ques- 
tion. In  this  country  Dochez  has  used  group  and  specific  agglutinins 
for  the  classification  of  pneumococci  and  Krumweide  for  the  study  of 
the  colon-typhoid  group. 

In  addition  to  the  bacteria,  the  red  blood  cells,  or  cells  of  any  sort, 
trypanosomes  and  other  protozoa  may  be  agglutinated.  The  agglutina- 
tion of  the  red  blood  cells  of  the  recipient  is  an  important  factor  in 
blood  transfusions,  etc. 

We  have  no  satisfactory  explanation  of  agglutination.  Analogous 
phenomena  occur  in  the  study  of  the  physical  chemistry  of  colloidal 
substances.  It  seems  that  in  agglutination  two  separate  phenomena  are 
involved :  the  approach  of  the  particles,  one  to  the  other,  and  their  ad- 
hesion subsequently.  The  phenomenon  may  be  imitated  by  coating 
match  sticks  with  soap,  floating  them  upon  the  surface  of  water,  in  a 
basin,  and  then  adding  sulphuric  acid.  The  agglutinins  affect  the  sur- 
face tension  between  the  bacteria  and  the  fluid  in  which  they  are  sus- 
pended in  some  way,  but  just  how  is  not  quite  clear.  The  probable 
explanation  of  agglutination  lies  in  an  alteration  in  the  electric  charge 
of  the  particles.  The  agglutinins  are  probably  formed  in  the  lymphoid 
organs,  red  marrow,  and  spleen ;  at  least,  Pf eiffer  and  Marx  found  them 
early  in  these  organs  after  injections  of  cholera  vibrios.  MetchnikofE 
found  that  the  peritoneal  exudate  may  be  richer  in  agglutinins  than  the 
blood,  and  believes  in  that  fluid  they  come  from  the  leukocytes  and 
endothelial  cells. 

The  part  played  by  the  agglutinins  in  immunity  is  not  clear.  Al- 
though the  bacteria  are  immobilized,  this  does  not  particularly  favor 
phagocytosis.  Large  clusters  of  bacteria  or  agglutinated  clumps  of 
closely  packed  cells  may  even  afl'ord  a  mechanical  protection  against  the 


ANAPHYLAXIS  593 

dissolving'  aetidii  of  (lie  lysins.  l)ull  '"  has  (Icinonst rated  that  the  power 
of  the  blood  to  cause  aij^glutiiialioii  (h'tcriuiiics,  in  hii-<;e  measure,  whether 
after  their  direi't  introdiu'tioii  in  an  experimental  way  the  baeteria  are 
to  be  removed  promptly  from  the  circulation  and  septicemia  avoided, 
or  whether  they  are  to  remain  there  and  ))rodiice  a  hlood  infection. 
When  the  baeteria  are  clumped  they  accumulate  in  the  organs,  in  which 
they  are  phagocyted. 

ANAPHYLAXIS 

Anaphylaxis  *^  (ana,  against,  and  phijlax,  guard,  or  phylaxis,  protec- 
tion), also  called  hypersusceptibility,  is  a  condition  of  unusual  or  exag- 
gerated susceptibility  of  the  organism  to  foreign  proteins.  In  other 
words,  anaphylaxis  is  an  altered  power  of  reaction  on  the  part  of  the 
body  to  foreign  proteins.  The  word  anaphylaxis  was  introduced  by 
Eichet  to  describe  a  condition  contrary  to  prophylaxis.  As  we  now 
regard  the  phenomenon,  the  word  is  a  misnomer,  for  we  look  upon  the 
condition  of  hypersusceptibility  as  a  distinct  benefit  and  advantage  to 
the  organism;  in  fact,  immunity  against  a  large  class  of  infectious 
diseases  probably  depends  upon  an  altered  power  of  reaction,  that  is, 
upon  hypersusceptibility  or  anaphylaxis. 

The  condition  of  anaphylaxis  may  be  congenital  or  acquired,  local  or 
general,  and  is  specific  in  nature.  It  may  be  brought  about  by  the  intro- 
duction of  any  strange  protein  into  the  body.  Hypersusceptibility  to 
proteins  that  are  non-poisonous  in  themselves  may  readily  be  induced 
in  certain  animals.  The  animal  may  be  in  a  condition  of  hypersuscepti- 
bility and  immunity  at  the  same  time.  The  two  conditions  are  closely 
interwoven.  The  latter  is  often  dependent  upon  the  former.  Von 
Pirquet  suggests  the  term  "allergie"  to  indicate  conditions  of  acquired 
immunity  associated  with  anaphylaxis.  Allergic,  as  the  word  indicates 
(alios,  change,  and  ergon,  action)  is  an  altered  power  of  the  organism 
to  react.  When  this  power  of  reaction  is  increased  we  say  the  body  is 
hypersusceptible,  or  in  a  state  of  anaphylaxis. 

Hypersendtiveness  may  be  defined  as  a  specific  or  particular  re- 
action with  characteristic  symptoms  due  to  the  administration  of,  or 
contact  wdth,  any  substance,  which,  in  the  majority  of  the  members  of  the 
same  species  of  animal,  causes  no  evident  disturbance.  According  to 
this  definition  hypersensitiveness  is  a  broad  conception,  including  both 
anaphylaxis  and  allergic.  Anaphylaxis  is  an  antigen-antibody  reaction, 
artificially  induced  by  immunologic  processes.  Allergie,  on  the  other 
hand,  is  used  to  express  a  natural  hypersensitiveness  of  the  individual 

""Journ.  Exp.  Med.,  1915,  XXII,  484;   1916,  XXIV,  2.5. 

■"The  present  status  of  the  problems  of  anaphylaxis  and  the  fundamental 
theories  involved  is  reviewed  by  Wells,  Physiological  Rev.,  Vol.  I,  No.  1,  Jan., 
1921. 


594  IMMUNITY 

not  produced  by  immunologic  processes,  as  the  exciting  agents  or  aller- 
gens are  in  many  cases  not  capable  of  producing  antibodies.  For  ex- 
ample, the  natural  hypersensitiveness  of  the  human  being  to  pollens,  the 
clinical  reaction  known  as  hay  fever,  is  admittedly  allergic. 

Examples  of  Anaphylaxis. — In  the  case  of  vaccinia,  the  reaction  to  a 
primary  "take"  appears  after  an  incubation  of  four  days.  In  a  secondary 
vaccination  the  period  of  incubation  is  shortened  and  the  clinical  reac- 
tion lessened.  In  other  words,  the  power  of  the  organism  to  react  is 
changed.  This  power  of  accelerated  or  immediate  reaction  protects  the 
individual.    Therefore,  the  prophylaxis  depending  upon  the  anaphylaxis. 

The  tuberculin  and  mallein  reactions  are  well-known  instances  of 
anaphylaxis.  These  substances  are  not  poisonous  when  introduced  into 
a  healthy  individual,  but  the  tuberculous  individual  is  anaphylactic  to 
tuberculin,  and  an  individual  suffering  from  glanders  is  in  a  state  of 
hypersusceptibility  to  mallein. 

A  clinical  instance  of  anaphylaxis  is  the  hypersusceptibility  of  some 
individuals  to  pollen — hay  fever.  Other  examples  are  food  "idiosyn- 
crasies," serum  sickness,  urticarial  and  other  skin  eruptions. 

Experimental  anaphylaxis  may  be  brought  about  in  various  ways, 
such  as  the  introduction  of  an  alien  protein  into  the  body. 

Experimental  Anaphylaxis. — The  essential  features  of  experimental 
anaphylaxis  are : 

(1)  The  first  injection,  consisting  of  a  bland  alien  protein  non- 
poisonous  in  itself,  which  sensitizes  the  animal ; 

(3)     An  interval  of  about  10  days; 

(3)  The  second  injection  of  the  same  protein  which  produces  a 
reaction  known  as  acute  anaphylactic  shock  or  other  manifestations. 

Horse  serum,  when  injected  into  normal  guinea-pigs,  causes  no 
symptoms.  As  much  as  20  c.  c.  may  be  injected  into  the  peritoneal 
cavity  of  a  guinea-pig  without  causing  any  apparent  inconvenience 
to  the  animal.  Small  amounts  of  horse  serum  may  even  be  injected 
directly  into  the  brain  without  causing  any  untoward  symptoms. 

Very  characteristic  symptoms,  however,  are  produced  by  horse  serum 
when  injected  into  a  susceptible  guinea-pig;  i.  e.,  one  that  has  received 
a  prior  injection  of  horse  serum.  In  five  or  ten  minutes  after  subcuta- 
neous injection  the  pig  becomes  restless  and  then  manifests  indications 
of  respiratory  embarrassment  by  scratching  at  the  mouth,  coughing,  and 
sometimes  by  spasmodic,  rapid,  or  irregular  breathing;  the  pig  becomes 
agitated  and  there  is  a  discharge  of  urine  and  feces.  This  stage  of  ex- 
hilaration is  soon  followed  by  one  of  paresis  or  complete  paralysis,  with 
spasmodic  and  difficult  breathing.  The  pig  is  unable  to  stand  or,  if  it 
attempts  to  move,  falls  upon  its  side;  when  taken  up  it  is  limp:  spas- 
modic, jerky,  and  convulsive  movements  now  supervene.     This  chain  of 


ANAPHYLAXIS  595 

symptoms  is  very  characteristic,  altliough  tliey  do  not  always  follow  in 
the  order  given.  Pigs  in  the  stage  of  complete  paralysis  may  fully  re- 
cover, but  usually  convulsions  appear,  and  are  almost  invariably  a  fore- 
runner of  death.  Symptoms  appear  about  ten  minutes  after  the  injec- 
tion has  been  given;  occasionally  in  pigs  not  very  susceptible  they  are 
delayed  thirty  to  forty-five  minutes.  Pigs  developing  late  symptoms 
are  not  very  susceptible  and  do  not  die.  Death  usually  occurs  within 
an  hour  and  frequently  in  less  than  thirty  minutes.  If  the  second  in- 
jection be  made  directly  into  the  brain  or  circulation,  the  symptoms  are 
manifested  with  explosive  violence,  the  animal  frequently  dying  within 
two  or  three  minutes. 

A  fall  in  temperature  occurs  w^hich  in  fatal  cases  may  be  as  great 
as  13°  C.  (Pfeiffer).  The  blood  during  anaphylactic  shock  shows  a 
leukopenia  and  a  diminution  in  complement.  The  blood  pressure  falls. 
When  the  chest  is  opened  the  lungs  show  a  striking  condition  resembling 
emphysema.  They  do  not  collapse  but  remain  fully  distended,  forming 
a  cast  of  the  pleural  cavities.  The  heart  continues  to  beat  long  after 
respiration  has  ceased.  Asphyxia,  due  to  inspiratory  immobilization  of 
the  lungs,  is,  therefore,  probably  the  immediate  cause  of  death. 

Judged  by  the  severity  of  the  symptoms  of  the  acute  anaphylactic 
reaction,  the  guinea-pig  is  apparently  the  most  susceptible  of  animals 
(being  400  times  more  sensitive  than  the  rabbit,  according  to  Doerr), 
but  probably  all  animals  may  be  sensitized  to  a  greater  or  less  degree, 
although  our  criteria  are  still  too  crude  to  admit  of  any  accurately  graded 
comparison.  White  mice  were  long  thought  to  be  non-responsive  on 
account  of  the  absence  of  anaphylactic  shock  and  death  from  asphyxia, 
so  striking  in  the  guinea-pig;  but  Schultz  and  Jordan  have  shown  that 
white  mice  do  react  toward  horse  serum  with  restlessness,  marked 
irritability  of  the  skin,  passage  of  urine  and  feces,  and  temperature  and 
blood  pressure  changes.  The  symptoms  vary  with  the  species  and  also 
to  some  degree  with  the  antigen. 

In  dogs,  according  to  Eichet,  the  principal  symptoms  are  gastro- 
intestinal. There  is  immediate  vomiting,  followed  by  tenesmus  and 
bloody  discharges  from  the  intestines.  Death  is  infrequent,  but  there 
may  develop  a  condition  of  hemorrhagic  inflammation  in  both  the  large 
and  the  small  intestine  which  is  called  by  Eichet  "chronic  anaphylaxis," 
and  by  Schittenhelm  and  Weichardt,  "enteritis  anaphylactia."  Another 
important  sign  is  the  rapid  fall  in  blood  pressure,  sometimes  80-100 
mm.;  on  account  of  the  relatively  enormous  amount  of  smooth  muscle 
in  the  hepatic  vein  of  the  dog,  there  is  a  rise  in  portal  pressure  and 
an  increased  flow  of  lymph ;  coagulation  of  the  blood  is  delayed.  Dyspnea 
is  not  marked,  but,  as  in  other  animals,  there  is  initial  restlessness  and 
skin  irritability;  there  may  be  paralysis  and  death. 

Eabbits  are  apt  to  react  to  a  reinjection  of  horse  serum  by  edema 


596  IMMUNITY 

and  even  necrosis  at  the  site  of  injection — the  "Arthus  phenomenon,'^  a 
local  anaphylaxis.  Arthus  also  described,  in  non-fatal  cases  in  rabbits, 
respiratory  disturbance,  general  prostration,  fall  in  blood  pressure,  and 
increased  peristalsis.  In  cases  of  acute  lethal  anaphylaxis  produced  in 
rabbits  highly  sensitized  by  repeated  minute  injections,  Auer  describes 
the  slow  respiration,  the  sudden  falling  of  the  animal  on  its  side  with  a 
short  chronic  convulsion,  stoppage  of  the  respiration,  weak  heart  beat, 
and  death  within  a  few  minutes. 

The  reaction  to  a  second  injection  of  serum  has  been  observed,  though 
not  studied  so  carefully,  in  numerous  other  animals,  e.  g.,  in  cows,  horses, 
goats,  sheep,  and  cats,  in  hens  and  pigeons,  and  in  certain  cold-blooded 
animals,  with  symptoms  varying  according  to  the  species. 

It  is  evident  that  no  one  symptom,  or  group  of  symptoms,  can  be 
taken  as  an  adequate  criterion  of  anaphylaxis  in  all  cases.  Different 
species  give  a  widely  differing  picture  with  the  same  protein  agent, 
because  the  same  organs  are  not  involved  to  the  same  degree.  An  ex- 
planation of  these  differences  from  the  physiological  point  of  view  has 
been  given  by  Schultz.  He  has  shown  that  serum  anaphylaxis  is  essen- 
tially a  matter  of  hypersensitization  of  smooth  muscle  in  general.  He 
concludes,  as  a  result  of  his  experiments,  that,  during  anaphylactic 
shock,  all  smooth  muscle  contracts.  This  is  fatal  to  the  guinea-pig, 
owing  to  the  peculiar  though  normal  anatomical  condition  of  its  bron- 
chial tree :  the  mucosal  layer  of  the  secondary  bronchi  is  relatively  thick 
in  comparison  with  the  lumen,  and  the  contraction  of  the  smooth  muscle 
throws  it  into  folds  which  completely  occlude  the  bronchi  (Schultz  and 
Jordan).  The  guinea-pig  dies  of  asphyxia,  the  cause  of  which  is  purely 
local  and  not  in  the  central  nervous  system,  as  the  first  investigators  be- 
lieved. The  bronchi  of  miice,  dogs,  and  rabbits,  however,  are  relatively 
poor  in  smooth  muscle,  which  accounts  for  the  almost  complete  ab- 
sence of  death  from  asphyxia.  In  the  dog  the  contraction  of  smooth 
muscle  sets  up  a  vigorous  intestinal  peristalsis  and  a  forced  emptying 
of  the  urinary  bladder;  the  characteristic  initial  rise  in  blood  pressure 
may  be  due  to  constriction  of  the  pulmonary,  coronary  and  systemic 
arteries,  and  according  to  Auer,  the  subsequent  marked  fall  to  direct 
action  on  the  heart  muscle  itself,  particularly  of  the  right  side,  causing 
a  venous  accumulation  of  blood,  an  effect  typified  most  strikingly  in 
the  rabbit.  This  provides  also  an  adequate  pharmacological  explanation 
of  the  action  of  atropin  and  the  anesthetics  in  alleviating  the  symptoms 
of  acute  anaphylaxis. 

Specificity. — The  anaphylactic  reaction  is  specific.  Thus,  a  guinea- 
pig  sensitized  with  horse  serum  does  not  react  to  a  subsequent  injection 
of  egg-white,  vegetable  protein,  or  milk.  The  sppnificity  extends  even 
further  than  this.  In  order  to  give  rise  to  anaphylactic  symptoms,  thr 
protein  material  given  at  the  first  and  second  injections  must  be  froLi 


ANAPHYLAXIS  597 

the  sniiu'  spcM'ips  or  from  sonio  closoly  relatod  species.  Thus  a  ^uiiiea- 
])ii:-  sensilizcd  with  cow's  milk  will  not  react  to  a  suhscquent  injection 
of  Avoman's  milk.  Cluinea-))i,!j,s  sensitized  with  the  alhiimcn  of  hen's 
eggs  will  not  react  to  a  suhsequent  injection  of  the  alhumen  of  the  eggs 
of  pigeons,  hut  do  react  mildly  to  duck  egg-white.  This  specificity  ac- 
cording to  species  is,  therefore, .  of  the  same  degree  as  that  of  certain 
immune  reactions,  notahly  the  precipitins;  that  is,  there  is  a  group 
reaction  in  tlie  proteins  of  allied  species,  but  no  reaction  between  the 
]iroteins  of  widely  difTerent  species  or  between  proteins  of  widely  dif- 
ferent origin.  The  maximum  effect  at  second  injection  is  obtained 
by  the  use  of  the  identical  protein  used  for  sensitization.  Certain 
sera  which  react  interchangeably  to  precipitins,  as,  for  example,  human 
and  ape,  horse  and  ass,  sheep  and  goat,  rat  and  mouse,  remain  indis- 
tinguishable also  by  the  anaphylactic  reaction.  The  same  specificity 
holds  with  respect  to  bacterial  proteins :  an  animal  sensitized  with  ty- 
phoid bacilli  will  react  strongly  toward  paratyphoid,  and  somewhat 
toward  colon  bacilli,  but  not  at  all  to  unrelated  genera. 

One  of  the  remarkable  facts  in  relation  to  the  specificity  of  anaphy- 
laxis is  that  guinea-pigs  may  be  in  a  condition  of  anaphylaxis  to  three 
protein  substances  at  the  same  time;  for  instance,  a  giiinea-pig  may  be 
sensitized  with  egg-white,  milk,  and  horse  serum,  and  subsequently  react 
separately  to  a  second  injection  of  each  one  of  these  substances.  The 
guinea-pig  may  be  sensitized  by  giving  these  strange  proteins  either  at 
the  same  time  or  different  times,  in  the  same  place  or  in  different  places, 
or  by  injecting  them  separately  or  mixed.  The  guinea-pig  differentiates 
each  anaphylactogenic  protein  in  a  perfectly  distinct  and  separate  man- 
ner. The  animal  is  susceptible  to  the  second  injection  of  each  one  of  the 
three  substances  in  the  same  sense  that  it  is  susceptible  to  three  sep- 
arate infectious  diseases. 

That  there  may  be  exceptions  to  the  rule  of  species-specificity  is  shown 
in  the  case  of  the  crystalline  lens.  A  guinea-pig  sensitized  to  the  lens- 
extract  of  one  species  of  animal  wall  react  to  the  lens-extract  of  widely 
different  species,  or  even  of  its  own  species,  but  not  to  other  tissues 
(Andrejew).  Here,  too,  there  is  an  exact  parallel  in  the  precipitin 
reaction  which  fails  to  distinguish  the  lens  of  one  species  from  that  of 
another  (Uhlenhuth).  This  is  an  example  of  organ-specificity.  In  the 
vegetable  world  Osborne  has  shown  that,  whereas  preparations  of  globu- 
lins from  hemp,  flax,  and  squash  do  not  react  with  each  other,  gliadin 
from  rye  reacts  strongly  with  gliadin  from  wheat,  a  result  in  accord 
with  the  fact  that  by  chemical  and  physical  means  no  differences  have 
been  detected  which  were  sufficient  to  indicate  that  these  gliadins  were 
different  substances. 

It  is  probable  that  only  proteins  which  have  a  complete  or  partial 
chemical  identity  of  structure  will  react  with  each  other.     Differences 


598  IMMUNITY 

too  small  to  be  detected  by  analytic  means  at  our  disposal  may  yet  pre- 
vent a-ny  tendency  toward  interaction,  and  the  anaphylactic  phenomenon 
is  therefore  used  to  determine  the  tine  relationships  of  proteins.  It  is 
evident  from  these  facts,  as  Osborne  concludes,  that  structural  differences 
exist  between  very  similar  proteins  of  different  origin,  and- that  chemi- 
cally identical  proteins  apparently  do  not  occur  in  animals  and  plants 
of  different  species  unless  they  are  biologically  very  closely  related. 

Sensitization  by  Feeding. — Guinea-pigs  may  be  sensitized  by  feeding 
them  meat  or  serum.  The  fact  that  guinea-pigs  may  be  rendered  sus- 
ceptible by  feeding  of  strange  protein  matter  opens  an  interesting 
question  as  to  whether  sensitive  guinea-pigs  may  also  be  poisoned  by 
feeding  with  the  same  protein  given  after  a  proper  interval  of  time.  If 
man  can  be  sensitized  in  a  similar  way  by  the  eating  of  certain  protein 
substances,  this  may  throw  light  on  those  interesting  and  obscure  cases 
in  which  the  eating  of  fish,  sea  food,  or  other  articles  of  diet  sometimes 
causes  sudden  and  often  serious  symptoms  resembling  those  of  anaphy^ 
laxis  in  all  essential  respects. 

Maternal  Transmission. — It  has  been  found  that  hypersusceptibilit}'' 
to  the  toxic  action  of  horse  serum  is  transmitted  from  the  mother 
guinea-pig  to  her  young.  This  function  is  solely  maternal;  the  male 
takes  no  part  whatever  in  the  transmission  of  these  acquired  properties. 
"Whether  this  maternal  transmission  is  hereditary  or  congenital  cannot 
be  definitely  stated. 

There  are  certain  analogies  between  the  action  of  tuberculosis  and 
anaphylaxis.  Both  produce  hypersensitiveness  and  also  a  certain  de- 
gree of  immunity.  Xow  that  it  has  been  proved  that  hypersensitive- 
ness or  anaphylactic  action  may  be  transmitted  in  guinea-pigs,  may  it 
not  throw  light  upon  the  fact  that  tuberculosis  "runs  in  families"? 
WTiile  there  are  several  recorded  instances  demonstrating  that  immunity 
to  certain  infectious  diseases  may  be  transmitted  from  a  mother  to  her 
young,  this  is,  so  far  as  is  known,  the  only  recorded  instance  in  which 
hypersensitiveness  or  a  tendency  to  a  pathologic  state  has  been  experi- 
mentally shown  to  be  transmitted  from  a  mother  to  her  young. 

Serum  Anaphylaxis  in  Man,  or  Serum  Sickness. — Serum  anaphylaxis 
in  man  is  met  with  most  frequently  following  the  use  of  antitoxic  sera, 
and  has  been  carefully  described  by  v.  Pirquet  and  Schick  (1905).^^ 
After  an  injection  of  serum  (usually  in  from  eight  to  twelve  days)  there 
is  apt  to  be  a  febrile  reaction,  now  generally  known  as  "serum  sickness," 
or  serum  disease.  The  common  symptoms  are  local  redness,  itching  and 
pain  at  the  point  of  injection,  swelling  of  the  lymph  nodes,  fever,  and 
a  general  urticaria  lasting  from  two  to  six  days.  In  more  severe  cases 
there  is  malaise,  albuminuria,  pronounced  joint  pains  and  even  effusions, 
swelling  of  the  mucous  membranes,  hoarseness  and  cough,  nausea  and 

*2  "Serum  Krankheit,"  Wien,  1905. 


ANAPHYLAXIS  599 

vomiting,  vertigo,  and  reniaikal)Ii'  skin  manifestations  varying  from 
hyperemias  and  erythemas  to  elllon'scences  resembling  measles  or  scar- 
latina, and  other  vasomotor  disturkinces.  There  is  a  striking  resem- 
blance between  serum  sickness  and  measles. 

Earely  there  may  be  subnormal  temperature,  a  weak  and  rapid  pulse, 
a  catarrhal  or  hemorrhagic  enteritis  and  extreme  weakness  approaching 
collapse.  These  results  are  independent  of  the  antitoxic  qualities  of 
the  serum,  for  Johannessen  obtained  the  same  symptoms  by  introducing 
normal  horse  serum  into  the  bodies  of  perfectly  healthy  human  beings. 
Indeed,  the  very  earliest  animal  experiments  were  particularly  concerned 
in  determining  whether  the  antitoxin  played  any  part  in  the  phenome- 
non, and  it  was  soon  conclusively  eliminated  as  a  factor. 

Both  the  incidence  and  the  severity  of  serum  sickness  are  propor- 
tional to  the  amount  injected  up  to  a  certain  point,  but  the  acute 
(sometimes  fatal)  reaction  in  man  is  more  dependent  upon  the  hyper- 
susceptibility  of  the  individual  than  upon  the  amount  of  serum  injected. 
If  the  serum  is  "concentrated"  (i.  e.,  serum-globulin),  the  reactions  are 
correspondingly  lessened  because  smaller  quantities  of  the  foreign  pro- 
tein are  injected,  and  the  albumins  and  certain  other  proteins  having 
been  eliminated  by  the  partial  purification. 

The  peculiarity  of  serum  sickness  in  man  is  that  it  may  follow 
the  first  injection  of  a  foreign  serum,  though  only  after  a  definite  incu- 
bation period  corresponding  to  the  time  required  to  sensitize  an  experi- 
mental animal.  There  is  no  proof  that  other  animals  do  not  develop 
a  reaction  to  the  first  dose  which  never  rises  to  the  threshold  of  clinical 
observation;  in  fact,  Ehrlich,  Francione,  and  others  have  observed  a 
temporary  diminution  of  complement  in  the  blood  of  guinea-pigs  10-12 
days  after  the  first  injection.  Just  how  man  becomes  sensitized  is  not 
always  clear.  It  may  be  by  a  previous  injection  of  horse  serum,  or  by 
eating  horse  meat,  or  by  the  introduction  of  small  amounts  of  horse 
protein  through  wounds  of  the  skin,  or  through  the  respiratory  tract; 
finally,  hereditary  transmission  may  account  for  the  susceptibility. 

Besides  the  typical  serum  sickness,  there  has  been  reported  since 
the  introduction  of  serum  therapy  a  certain  small  number  of  unforeseen 
and  fatal  catastrophes  attending  the  injection  of  horse  serum'  into 
human  beings.  The  following  case  published  by  H.  F.  Gillette  will 
serve  to  illustrate  them  all: 

"The  patient  was  a  man  of  53,  a  subject  of  asthma.  He  asked 
me  to  administer  diphtheria  antitoxin  to  him,  hoping  it  might  cure 
his  asthma.  I  administered  2,000  units  under  the  left  scapula  with 
the  usual  precautions.  He  had  about  completed  dressing  when  he  said 
he  had  a  pricking  sensation  in  the  neck  and  chest;  soon  he  sat  down 
and  said  he  could  not  breathe,  nor  did  he  breathe  again.  .  .  .  His 
pulse  at  the  wrist  remained  regular  and  full  for  some  time  after  respira- 


600  IMMUNITY 

tion  ceased.  He  had  a  mild  degree  of  cyanosis  and  edema  of  the  face. 
He  died  in  tonic  spasms  ten  minutes  after  injection.  Autopsy  revealed 
no  palpable  cause  of  death." 

The  same  author  collected  28  cases  of  collapse  or  death  after  serum 
injection,  of  which  15  died.  There  was  a  common  history  of  previous 
asthmatic  trouble  in  all  but  5  of  the  28,  and  all,  after  injection, 
showed  common  symptoms  of  sudden  intense  dyspnea,  a  sense  of  over- 
whelming anxiety,  edema  and  cyanosis  of  the  face,  a  sudden  massive 
urticaria,  tonic  muscular  spasms  and  continued  beating  of  the  heart 
long  after  the  ceasing  of  respiration.  Bosenau  and  Anderson  collected 
19  cases  and  were  able  to  examine  the  serum  used  in  two  of  them.  It 
was  found  to  be  no  more  toxic  to  sensitized  guinea-pigs  than  normal 
horse  serum.  These  cases  of  severe  anaphylactic  shock  seem  susceptible 
of  no  other  explanation  than  that  the  unfortunate  individuals  had  been 
in  some  manner,  at  a  previous  time,  sensitized  to  horse  protein.  They 
present  a  picture  which  is  almost  the  counterpart  of  typical  anaphylactic 
shock  in  guinea-pigs,  and  the  most  striking  thing  about  them  is  that 
practically  all  give  a  history  of  respiratory  trouble  in  the  past,  especially 
horse-asthma.  Schultz  and  Jordan  suggest  that  these  occasional  cases 
of  sudden  death  in  man  may  perhaps  be  due  to  an  abnormal  develop- 
ment of  the  mucous  membrane  and  smooth  muscle  of  the  bronchi  (as  in 
asthmatics),  and  that  the  smooth  muscle,  being  hypersuscej)tible,  pro- 
duces asphyxia  by  sudden  contraction.  There  is  evidence  ^^  indicat- 
ing that  the  protein  given  off  by  one  animal  may  be  absorbed  by  indi- 
viduals of  different  species  by  way  of  the  lungs.  One  thing  is  clear, 
that  these  immediate  and  sometimes  fatal  reactions  are  not  dependent 
upon  any  peculiar  property  in  the  serum,  but  to  an  altered  power  of  re- 
action of  the  individual  to  the  foreign  protein  injected.  The  anaphylac- 
tic reactions  following  the  injection  of  serum  in  man  may  be  summed  up 
briefly  as  follows : 

Reactions  following  first  injection: 

(a)  "Serum  sickness,"  incubation  8-12  days   (common). 

(b)  Acute  anaphylactic  shock,  with  collapse  or  death   (rare). 

Reaations  following  second  injectio7i: 

(a)  Interval  between  injections  less  than  8  days,  no  reaction. 

(b)  Interval  12-40  days,  immediate  reaction. 

(c)  Interval  15  days-6  mos.,  either  immediate  or  accelerated  reaction, 
or  both. 

(d)  Interval  over  6  mos.,  accelerated  reaction. 

The  above  table  represents  the  usual  course  of  events,  but  exceptions 
may  occur,  and  the  time  intervals  are  only  approximate.      Sometimes 

"Rosenau,  M.  J.,  and  Amoss,  H.  L.:  Jour,  of  Med.  Res.,  Sept.,  1911,  XXV, 
1,  pp.  35-84. 


ANAPHYLAXIS  601 

the  reactions  do  not  appear  unlil  the  third,  I'ourtli,  or  some  subsequent 
injection. 

The  followiiif^r  precautions  are  sufjfrested  in  serum  therapy: 

(1)  Except  in  nrg'ent  cases,  avoid  injecting  horse  serum  into  indi- 
vidiials  known  to  be  asthmatic,  especially  those  in  whom  symptoms 
are  brought  on  by  being  around  liorses. 

(2)  If  hypersensitiveness  is  suspected,  give  at  first  a  very  small 
amount  of  serum  subcutaneonsly,  following  it  in  an  hour  or  so  with  the 
rest,  injecting  it  exceedingly  slowly  and  avoiding  direct  injection  into 
the  circulation.  Sometimes  an  intradermal  injection  is  given  to  de- 
termine sensitization;  this  is  followed  by  small  desensitizing  doses  of  the 
serum  at  intervals  of  an  hour.  There  is  no  necessary  correlation  be- 
tween skin  hypersensitiveness  and  general  anaphylaxis. 

(3)  In  persons  known  or  suspected  of  being  hypersusceptible  to 
horse  serum,  l)ovine  antitoxin  may  be  used. 

Hypersusceptibility  and  Immunity  Produced  by  Bacterial  Proteins. 
— The  problem  of  hypersusceptibility  has  an  important  bearing  on  the 
question  of  immunity,  and  hence  the  opinion  has  been  expressed  that 
"resistance  to  disease  may  largely  be  gained  through  a  process  of  hyper- 
susceptibility. Whether  this  increased  susceptibility  is  an  essential  ele- 
ment or  only  one  stage  in  the  process  of  resistance  to  disease  must 
now  engage  our  attention."  It  is  now  clear  that  the  phenomenon  of 
hypersusceptibility  has  an  important  bearing  on  the  prevention  and  cure 
of  certain  infectious  processes. 

Hypersusceptibility  may  easily  be  induced  in  guinea-pigs  with  pro- 
tein extracts  obtained  from  the  bacterial  cell.  The  first  injection  of 
most  of  the  extract  seems  comparatively  harmless  to  the  animal.  A 
second  injection  of  the  same  extract  shows,  however,  that  profound 
physiologic  changes  have  taken  place.  A  definite  period  must  elapse 
between  the  first  and  the  second  injection.  The  symptoms  presented 
by  the  guinea-pigs  as  a  result  of  the  second  injection  resemble  those 
caused  by  other  proteins.  The  phenomenon  induced  by  a  second  injec- 
tion is  followed  (in  certain  cases)  by  an  immunity  to  the  correspond- 
ing infection. 

These  results  strengthen  the  belief  that  the  phenomenon  of  hyper- 
susceptibility has  a  practical  significance  in  the  prevention  and  cure 
of  certain  infectious  processes.  It  also  gives  a  possible  explanation  of 
the  period  of  incubation  of  some  of  the  communicable  diseases.  Is  it 
a  coincidence  that  the  period  of  incubation  of  a  number  of  infectious 
diseases  is  about  seven  to  fourteen  days,  which  corresponds  significantly 
with  the  time  required  to  sensitize  animals  with  a  strange  protein  ?  The 
mechanism  of  prevention  and  cure  of  tuberculosis  finds  its  readiest  ex- 
planation in  terms  of  anaphylaxis. 

In  certain  infectious  diseases,  such  as  pneumonia,  the  crisis  which 


602  IMMUNITY 

commonly  appears  about  the  tenth  day  may  find  a  somewhat  similar 
explanation.  It  is  evident  that  disease  processes  produced  by  soluble 
toxins,  such  as  diphtheria  and  tetanus,  do  not  belong  to  the  category 
now  under  consideration. 

Relation  of  Anaphylaxis  to  Protein  Metabolism. — The  whole  prob- 
lem of  protein  metal)olism  seems  to  be  an  adjustment  in  the  sense  of  a 
defense.  The  power  to  assimilate  and  use  foreign  proteins  is  not 
achieved  without  a  certain  amount  of  violence  to  the  body.  The  rela- 
tion between  the  fundamental  facts  of  protein  metabolism  and  immunity 
to  certain  diseases  becomes  clearer  in  the  light  of  observations  upon 
anaphylaxis.  A  deeper  insight  into  these  problems  will  throw  light  on 
the  fundamental  processes  concerned  in  both  protein  metabolism  and 
immunity. 

Relation  of  Anaphylaxis  to  Endotoxins. — The  fact  that  the  great 
majority  of  bacteria  do  not  produce  soluble  poisons,  such  as  diphtheria 
and  tetanus,  has  led  to  the  belief  that  in  such  cases  we  are  dealing  with 
an  "endotoxin."  The  endotoxin  has  long  been  regarded  as  a  poisonous 
substance  so  intimately  associated  with  the  cell  that  it  is  not  released 
until  the  microbic  cell  is  broken  up  in  the  body.  The  inability  to  dem- 
onstrate many  of  these  endotoxins  has  cast  a  doubt  on  their  existence  and 
increased  the  mystery  of  their  action.  It  now  seems  probable  that  the 
studies  on  anaphylaxis  may  throw  light  upon  this  question. 

When  bacteria  grow  in  the  body  they  are  dissolved  by  lytic  agencies 
and  the  foreign  protein  thus  released  may  sensitize  the  body  and  after- 
ward "poison"  it.  The  bacterial  proteins  may  not  be  poisonous  in  them- 
selves in  the  sense  of  an  "endotoxin."  We  have,  in  fact,  shown  that 
protein  extracts  of  bacterial  cells  at  the  second-  injection  may  produce 
characteristic  symptoms,  and  this  reaction  may  be  followed  by  an  im- 
munity to  the  corresponding  infection. 

The  Relation  of  Anaphylaxis  to  Tuberculosis. — The  tuberculin  reac- 
tion is  one  of  the  best  knoAvn  clinical  instances  of  anaphylaxis.  The 
reaction  may  be  general,  local  or  focal;  even  anaphylactic  shock  may 
occur.  The  general  reaction  is  manifested  by  fever  and  constitutional 
symptoms;  the  local  reaction  by  inflammation  of  the  skin  (von  Pirquet 
test) ;  the  focal  reaction  by  congestion  and  increased  functional  activity 
about  the  tuberculous  lesion.  Balwin  and  Krause  have  demonstrated 
that  the  general,  local  or  focal  reactions  occur  only  as  a  result  of  an 
anatomical  tubercle.  Following  a  local  infection  with  the  tubercle  ba- 
cillus the  tissues  generally  become  hypersusceptible  to  tuberculin.  It 
has  been  shown  that  a  local  hypersusceptibility  may  be  produced  by  the 
direct  application  of  tuberculin  to  certain  tissues  (conjunctiva).  The 
same  has  been  demonstrated  for  the  skin,  and  ^'s  probably  true  of  other 
tissues.  This  hypersusceptibility  of  the  tissues  immediately  surrounding 
a  tuberculous  focus  helps  to  encapsulate  and  limit  the  process.     Should 


ANAPHYLAXTS  603 

a  tubercle  baeilliis  Iodide  in  oi-  oii  a  tissue  in  a  stale  of  tul>ereulin  ana- 
phylaxis, the  result  is  tiiat  all  of  nature's  protecting  agencies  are  quickly 
concentrated  on  the  point  where  most  needed.  We  conceive  that  this 
active  power  of  reacting  quickly  is  not  only  an  important  factor  in  indi- 
vidual prophylaxis  against  tuberculosis,  but  is  an  important  agency  by 
which  the  spread  of  the  disease  after  it  has  obtained  a  lodgment  in  the 
body  is  prevented. 

The  normal  individual  does  not  react  to  tuberculin.  The  tuljcrcu- 
lous  individual  reacts  promptly,  except  in  the  final  stage  of  the  disease. 
The  difference  between  the  normal  individual  and  the  individual  in 
the  final  stage  of  tuberculosis  is  that  the  former  has  not  had  his  ana- 
phylactic powers  developed,  while  the  latter  has  had  them  developed  and 
disappear.**  A  tuberculous  individual  in  whom  the  specific  power  of 
hypersusceptibility  to  the  tubercle  bacillus  is  broken  down  presents  lit- 
tle or  no  resistance  agaijLst  the  advance  of  the  infection. 

We  may  adduce  a  practical  lesson  from  this.  When  tuberculin  is 
used  in  large  or  too  oft-repeated  doses  there  is  a  tendency  to  break 
down  or  to  exhaust  the  useful  and  beneficial  hypersusceptible  state  of 
the  tissues.  In  accordance  with  this  line  of  reasoning,  therefore,  tuber- 
culin would  be  of  benefit  in  tuberculosis  only  when  used  in  such  a  way 
as  to  develop  and  not  diminish  the  power  of  anaphylaxis  of  the  tissues. 
This  explanation  has  been  borne  out  in  the  use  of  tuberculin,  especially 
as  a  therapeutic  agent  in  bone,  gland  and  skin  tuberculosis,  when  the 
process  is  sluggish.  Hence,  for  therapeutic  purposes,  it  should  be  used 
chiefly  to  stimulate  a  chronic  sluggish  process — even  then  only  in  small 
amounts  at  infrequent  intervals,  and  only  when  autogenous  tuberculin 
is  not  secreted. 

Relation  of  Anaphylaxis  to  Vaccination. — When  the  virus  of  cowpos 
is  introduced  into  the  skin  we  implant  a  colony  of  microorganisms.  They 
grow  day  by  day,  and  on  the  eighth  day  there  is  an  enormous  number 
of  them.  The  contents  of  the  vesicle  will  start  new  colonies  on  thou- 
sands of  other  arms,  but  now  the  antibodies  appear  and  the  colony  is 
attacked  and  digested,  and  toxic  bodies  are  formed.  This  is  diffused 
in  the  neighborhood  and  we  get  an  intense  local  inflammation  called  the 
areola.  Some  of  the  toxic  bodies  enter  the  circulation  and  canse  fever, 
but  the  microorganisms  are  killed  and  we  can  no  longer  vaccinate  with 
the  contents  of  the  now  yellow  pustule;  two  or  three  days  more,  the 
struggle  is  over,  but  the  antibodies  remain  a  long  time.  Let  us  now 
revaccinate,  and  a  different  series  of  events  takes  place,  for  in  the  mean- 
time the  body  has  become  educated  and  instead  of  waiting  some  days 
before  attacking  the  colony  of  microorganisms  in  the  skin,  starts  the 
attack  at  once.     In  other  words,   there  is   an   immediate   reaction — a 

■"The  term  antianaphylaxis  is  now  used  to  describe  the  condition  when  a 
sensitized  animal  fails  to  respond. 


604  IMMtTKlTY 

changed  power  of  reaction  or  anaphylaxis.  In  brief,  the  first  vaccina- 
tion has  sensitized  the  tissues,  so  that  they  respond  at  once  upon  the 
second  vaccination. 

The  invading  microorganisms,  attacked  at  once,  are  soon  destroyed 
— they  are  given  no  chance  to  multiply,  and  little  toxin  is  formed. 
This  attractive  explanation  of  the  immunity  to  smallpox  or  cowpox,  de- 
veloped by  von  Pirquet,  shows  that  the  prophylaxis  depends  upon  the 
anaphylaxis.     See  Immediate  and  Accelerated  Eeactions,  page  18. 

Relation  of  Anaphylaxis  to  Food  "Idiosyncrasies." — Many  persons 
are  susceptible  to  some  particular  article  of  diet.  The  symptoms  pro- 
duced axe  vasomotor  disturbances,  skin  eruptions,  gastro-intestinal  dis- 
orders, and  respiratory  difficulty.  The  articles  of  diet  usually  responsible 
are  shell-fish,  fish,  strawberries,  tomatoes,  pork,  cereals,  eggs,  milk, — the 
list  is  very  long,  including  even  honey.  Fish,  tomatoes,  and  cheese  are 
apt  to  produce  urticarias ;  cereal,  pork  and  milk,  erythemas  and  eczemas ; 
eggs,  asthmatic  symptoms.  There  is,  however,  no  constancy  in  this  re- 
gard. Collapse  may  result  in  a  few  ihinutes  from  the  ingestion  of  a  very 
small  amount  of  the  particular  substance  to  which  a  person  is  hyper- 
susceptible. 

These  cases  of  food  "idiosyncrasies"  are  instances  of  local  and  general 
anaphylaxis.  Bronf enbrenner  *^  demonstrated  the  presence  of  specific 
antibodies  in  the  blood  of  a  young  girl,  17  years  old,  who  was  subject  to 
asthmatic  attacks  and  severe  gastro-intestinal  disturbances,  following  the 
ingestion  of  small  quantities  of  egg  protein.  In  most  cases  the  suscepti- 
bility is  clearly  inherited,  in  some  it  may  be  acquired.  When  there  is 
difficulty  in  determining  which  food  is  responsible,  the  skin  test  may  be 
employed.  This  consists  in  rubbing  a  drop  of  the  food  itself,  or  a  watery 
extract,  into  a  scratch  upon  the  skin.  The  reaction  comes  on  within 
thirty  minutes,  as  a  pink-red  papule,  and  declines  rapidly.  The  relation 
between  the  local  and  general  reactions  is  not  always  clear. 

Antianaphylaxis  to  this  condition  may  be  brought  about  by  "immu- 
nizing" the  subject  with  increasing  doses  of  the  responsible  antigen  given 
by  the  mouth.  Peptone,  0.4  to  0.5  gram,  by  the  mouth  before  eating  also 
acts  as  a  desensitizing  agent.  The  peptone  seems  to  be  polyvalent  for 
most  of  the  proteins  causing  the  anaphylaxis. 

Eczema. — Towle  and  Talbot  Avere  among  the  first  definitely  to  reveal 
that  a  goodly  proportion  of  eczematous  infants  were  passing  stools  con- 
taining an  excess  of  fats  and  starch.  A  correction  of  diet  will  relieve 
most  of  these  infants  in  a  few  weeks.  In  cases  where  eczematous  infants 
and  older  children  do  not  reveal  an  excess  of  starch  or  fat,  they  are 
usually  anaphylactic  to  egg  albumin,  milk,  oatmeal,  or  some  other  food 
containing  protein.  In  chronic  eczema,  the  great  majority  of  these  vic- 
tims exhibit  anaphylactic  reactions  to  one  or  more  types  of  food  sub- 

« JoMTO.  Exp.  Med.,  1915.  XXI,  Xo.  .3. 


ANAPHYLAXIS  605 

stances  Only  about  20  per  cent,  of  eczematous  individuals  do  not  ap- 
pear sensitized  to  any  of  the  coniinnn  food  types. 

Relation  of  Anaphylaxis  to  Hay  Fever. — Hay  fever  may  be  caused 
by  the  pollen  of  glasses  and  certain  plants,  such  as  ragweed,  goldenrod, 
etc.;  by  emanations  from  animals,  especially  horses  and  cats;  by  sugges- 
tion, as  in  nervous  coryza;  and  by  changes  in  chemical  reaction,  as  when 
hyperacidity  of  the  gastric  juice  causes  the  mucous  membranes  to  swell 
and  discharge  a  watery  secretion.  Hay  fever  is  a  characteristic  symptom- 
complex  that  depends  entirely  upon  an  inherited  predisposition  on  the 
part  of  the  respiratory  and  conjunctival  mucous  membranes,  and  not 
upon  the  influence  of  a  specific  agent. 

Persons  who  are  susceptible  to  pollen  represent  instances  of  local 
anaphylaxis  of  the  respiratory  mucosa.  The  symptoms  are  mainly  local, 
but  also  general.  The  particular  pollen  responsible  in  any  individual 
case  may  be  determined  by  placing  a  drop  of  a  watery  extract  upon  a 
scratch  on  the  skin.  A  positive  reaction  manifests  itself  in  five  or  ten 
minutes  as  an  elevation  with  a  hyperemic  border  and  itching.  Certain 
foods,  especially  eggs,  give  rise  to  respiratory  difficulty,  asthmatic  in 
nature. 

Rose  colds  are  associated  Math  pollen  from  roses,  timothy,  daisies, 
etc.  Usually  they  occur  early  and  are  mild.  Eose  colds  may  be  helped 
by  inoculations  with  their  respective  proteins.  The  problem  is  different 
with  hay  fever  due  to  ragweed,  for  the  pollen  of  ragweed  is  a  micro- 
scopic bur  with  penetrating  properties.  In  cases  due  to  ragweed,  it  is 
necessary  to  consider  massive  dosage,  also  secondary  infections  which 
follow  injury  to  the  mucosa. 

Relation  of  Anaphylaxis  to  Drugs;  Anaphylactoid  Reactions. — 
Most  of  the  persons  who  show  idiosyncrasies  to  certain  drugs  give  a  clear 
history  of  inherited  hypersensitiveness.  The  symptoms  of  drug  reaction 
are  the  same  as  those  that  occur  with  foods,  i.  e.,  coryza,  cough,  bron- 
chial spasm  with  urticaria  in  some  cases,  or  angioneuritic  edema,  and 
frequently  gastro-intestinal  manifestations,  with  pain,  vomiting  and 
diarrhea.  These  symptoms  are  quite  separate  and  apart  from  any  normal 
or  toxic  action  of  the  drug.  The  class  of  drugs  known  as  antipyretics 
occasionally  produce  chills  aTid  pyrexia,  sometimes  cardiac  collapse.  In 
practically  all  these  cases,  there  is  a  marked  eosinophilia,  from  10  to 
15  per  cent.  Symptoms  usually  appear  within  a  few  hours  after  the 
administration  of  the  drug,  but  are  sometimes  delayed  for  days. 

The  drugs  that  may  act  as  exciting  agents  are  many:  metals,  the 
halogens,  alkaloids,  methane  derivatives,  coal  tar  products,  benzol  deriva- 
tives, also  resins,  turpentine,  sandalwood  oil,  cubebs,  copaiba  balsam,  and 
others. 

Other  Practical  Relations  of  Anaphylaxis. — Other  conditions  which 
have  been  explained  in  whole  or  part  on  the  theory  of  anaphylaxis  are 


606  IMMUNITY 

puerperal  eclampsia,  sympathetic  ophthalmia,  the  onset  of  labor,  the 
crisis  in  pneumonia,  the  spasmophilic  diathesis,  the  symptoms  attendant 
on  the  rupture  of  the  cysts  in  echinococcus  disease,  etc.  The  anaphy- 
lactic reaction  is  also  used  in  diagnosis,  and  in  forensic  medicine  in  the 
identification  of  blood  stains,  and,  finall}^  may  be  used  as  a  scientific 
instrument  for  the  detection  of  minute  amounts  of  protein. 

REFERENCES  TO  IMMUNITY 

Emery's  book  upon  "Immunity  and  Specific  Therapy"  and  Zinsser's  book 
on  "Immunity"  are  recommended  to  the  reader  who  desires  a  more  ex- 
tended review  upon  the  subject.  Kolle  and  Wassermann's  "Handbucb 
der  Pathogenen  Mikroorganismen"  has  also  been  consulted,  as  well  as 
Kraus  and  Levaditi's  "Handbucb  der  Technik  und  Metbodik  der 
Immunitatsforschung."  These  vohmies  also  contain  selected  bibli- 
ograpbies. 

The  laboratory  methods  of  Innuunology  are  described  in  Kolmer's  "Practical 
text  book  of  Infection,  Immunity  and  Specific  Therapy." 

The  current  literature  upon  immunity  will  be  found  in  the  Journal  of  Im- 
munology and  Zeitschrift  fiir  Immunitdtsforschungen. 

For  those  who  desire  to  dip  deeper  into  the  subject  the  original  reference 
to  many  of  the  fundamental  studies  will  be  found  in  "Collected  Studies 
on  Immunity"  by  Ehrlicb,  translated  by  Bolduan;  "Studies  on  Im- 
munity" by  Bordet,  translated  by  Gay;  "Studies  in  Immunization"  by 
Wright;  "L'Immunite  dans  les  Maladies  Infestieuses"  by  Metchnikoff, 
translated  by  Binnie;  and  Eicketts,  H.  T. :  "Infection,  Immunity  and 
Serum  Therapy  in  Relation  to  the  Infectious  Diseases  Which  Attack 
Man,"  Chicago,  1906. 


CHAPTEE   II 
HEEEDITY  AND  EUGENICS 

Heredity  may  be  defined  as  the  genetic  relation  between  successive 
generations.  It  is  a  condition  of  all  organic  evolution.  Castle  defines 
heredity  as  organic  resemblance  based  on  descent. 

It  is  now  perfectly  evident  that  heredity  is  one  of  the  fundamental 
factors  in  preventive  luedicine — and  of  first  importance  in  sociology. 
It  is  well  known  to  students  of  biology  that  education  and  environ- 
ment have  but  a  limited  power  to  improve  imperfect  human  proto- 
plasm. 

One  of  the  best  protections  we  have  against  diseases  of  body  and 
mind  is  that  which  is  inherited  from  our  forebears.  The  whole  prob- 
lem of  improving  the  human  stock,  not  only  from  the  medical  view, 
but  from  the  broader  sociologic  standpoint,  is  based  upon  the  breed- 
ing of  the  fit  and  elimination  of  the  unfit.  The  science  of  eugenics 
(normal  genesis),  therefore,  assumes  especial  importance  in  preventive 
medicine.  The  physician,  as  well  as  the  sanitarian,  stands  impotent 
before  many  deplorable  conditions  both  in  the  individual  and  in  so- 
ciety at  large,  which  are  inherited  from  our  ancestors  and  are,  there- 
fore, incurable — but  largely  preventable.  We  are  interested  in  educat- 
ing the  present  generation  to  the  facts  of  eugenics  so  that  future  gen- 
erations may  have  that  best  of  all  birthrights — good  human  protoplasm. 

The  discoveries  of  Mendel  have  made  it  quite  clear  how  certain  char- 
acters are  inherited,  why  certain  characters  skip  a  generation  and  re- 
appear in  the  grandchildren,  and  why  it  is  that  certain  defects  are 
carried  from  generation  to  generation  through  many  centuries.^  The 
defects  transmitted  -  hereditarily  are  not  all  of  equal  practical  impor- 
tance. Thus,  it  makes  comparatively  little  difference  to  the  individual 
if  he  has  a  supernumerary  spleen,  an  extra  finger,  or  an  unusual  arrange- 
ment of  the  lobes  of  the  liver.  The  defects  which  are  of  especial  im- 
portance both  to  the  individual  and  to  succeeding  generations  are  the 
defects  of  the  nervous  system.  These  comprise  the  class  known  as 
defectives.  A  slight  defect  in  the  structure  of  the  brain  which  would 
be  unnoticed  in  the  lung,  bone,  or  musculature  may  render  the  individual 
vicious  instead  of  useful.     The  principal  factors  which  are  believed  to 

*  Mendel's  work  has  not  only  made  it  possible  for  us  to  predict  with  pre- 
cision whether  certain  good  or  bad  traits  will  or  will  not  appear  in  the  future 
offspring,  but  also  to  foretell  with  considerable  precision  in  what  proportion  cer- 
tain characters  will  appear  and  reappear. 

607 


608  HEREDITY  AND  EUGENICS 

start  a  line  of  defectives  are  inbreeding,  syphilis,  and  alcohol ;  also  nerv- 
ous or  physical  diseases,  mental  or  nervous  exhaustion,  and  excesses  and 
poisons  of  all  kinds.^ 

DEFECTIVES 

Mental  defectives  are  due  to  restricted  mental  development  and 
must  be  regarded  as  children,  and  whatever  their  age  must  be  treated 
as  children.  They  are  unmoral,  not  immoral.  They  need  treatment, 
not  punishment,  for  they  are  as  innocent  as  children,  not  naturally  bad, 
vicious  or  wicked. 

Recognition.- — The  supposition  that  mentally  defective  presons  may 
readily  be  recognized  by  their  physical  appearance,  or  by  some  outward 
expression,  such  as  the  movement  of  the  eyes,  is  a  mistake.  It  is  also 
important  not  to  confuse  illiteracy  with  mental  deficiency. 

The  defective  individual  is  very  easily  recognized  when  the  condi- 
tion is  well  marked.  The  mental  abnormality  is  usually  accompanied 
by  prominent  physical  defects  known  as  the  stigmata  of  degeneration 
(Lombroso  and  Weismann).  The  typical  degenerate  is  of  poor  bodily 
development;  the  brain  is  smaller  than  normal,  with  convolutions  less 
abundant,  and  less  fully  formed.  He  has  a  degraded  physiognomy,  lacks 
capacity  for  sustained  attention  or  for  prolonged  thought,  is  cunning 
rather  than  intelligent,  deficient  in  moral  sense — in  all  points  resembling 
the  stigmata  of  the  lower,  less  developed  races  of  our  species.  The  whole 
gives  the  impression  of  a  reversion  to  a  lower  type.  An  unfortunate  side 
to  this  problem  is  that  degenerates  and  defectives  generally  are  not  only 
irresponsible  morally,  but  are  very  prolific.  They  lack  self-control  and 
have  abnormal  sexual  appetites.  Defectives  beget  defectives,  and  thus 
insanity,  nervous  diseases,  moral  and  physical  degeneracy  are  propa- 
gated. 

Mongolianism. — The  Mongolian  ^  type  is  described  by  Shuttleworth 
as  follows:  '"The  skull  is  a  short  oval,  the  transverse  and  longitudinal 
diameters  approximating,  while  there  is  a  tendency  to  parallelism  of  the 
frontal  and  occipital  planes.  Children  of  this  type  have  a  skin  course 
in  epidermis,  if  not  f urf uraceous ;  many  have  sore  eyelids,  some  fissured 
lips ;  but  one  of  the  most  striking  peculiarities  is  the  state  of  the  tongue, 
which  is  transversely  fissured,  and  has  hypertrophied  papillae.  Dr.  John 
Thomson  states  that  in  the  early  weeks  of  life  the  tongue  is  normal :  be- 
tween the  third  and  ninth  months  the  papillae  get  enlarged,  while  during 
the  third  and  fourth  years  the  transverse  fissures  appear.     This  latter 

*  The  real  cause  or  method  of  origin  of  some  defective  characters  that  are 
transmitted  hereditarily  is  no  better  understood  than  the  origin  of  "sports"  or 
mutations. 

*  This  type  has  no  connection  with  the  Mongolian  race.  It  is  so  named  on 
account  of  the  resemblance  to  that  type  of  countenance. 


DEFECTIVES  609 

peculiarity  is  possibly  due  to  tongue  sucking,  which  is  so  common  in  this 
type  of  defective,  acting  on  an  abnormally  vulnerable  mucous  membrane. 
Many  of  them  have  almond-shaped  eyes,  obliquely  set,  and  this  feature, 
with  the  squat  nose,  epicaiithic  fold,  and  wiry  hair,  gives  the  Mongol 
aspect  from  which  they  derive  their  name.  The  hands  are  usually  broad 
and  the  lingers  short,  and  often  the  little  finger  is  incurved.  Tiie  feet 
also  are  characteristically  clumsy,  witli  a  marked  cleft  between  the  big 
toe  and  the  next  one.  Laxity  of  the  joints  is  a  marked  feature.  There 
is  no  reason  to  believe  that  they  are  essentially  unfinished  children,  and 
that  their  peculiar  appearance  is  really  that  of  a  phase  of  fetal  life." 

ilongolianism  is  definite  and  easily  recognized  and  should  be  diag- 
nosed early,  usually  before  the  sixth  or  eighth  month.  This  is  important 
for  the  sake  of  the  parents.  Goddard  .states  that  a  diagnosis  of  Mon- 
golianism  settles  the  following  points:  (1)  The  condition  is  not  hered- 
itary. (2)  It  is  more  frequent  in  the  better  families.  (3)  The  child  will 
never  develop  beyond  the  seven-year  mentality,  and  the  great  majority 
have  a  mentality  of  almost  exactly  four  years.  Consequently  (4)  they 
must  always  be  cared  for.  Unpleasant  as.  the  duty  is,  yet  in  the  long  run 
it  is  a  kindness  to  the  parents  to  inform  them  of  such  a  diagnosis. 

Feeble-minded — Idiots,  Imbeciles  and  Morons. — Feeble-minded  per- 
sons arc  now  commonly  divided  into  three  groups:  (1)  idiots^  which 
comprise  those  whose  mentality  does  not  advance  beyond  normal  children 
of  two  years;  (2)  imbeciles,  those  whose  minds  remain  at  about  the 
fourth-year  period;  and  (3)  morons  or  fools,  those  whose  mental  con- 
dition does  not  get  farther  than  about  the  twelve-year  age.  ilild  grade? 
are  called  psychopathic  inferiority..  All  grades  of  mental  inferiorit}' 
between  the  moron  aiid  the  normal  occur.  In  addition,  there  is  a  group 
above  the  moron  whose  conduct  shows  that  they  are  not  normal.  These 
are  sometimes  called  dull  normal,  or  backward.  Of  these  three  groups 
the  moron  is  perhaps  the  most  important  from  every  standpoint,  for 
this  is  the  group  of  defectives  that  propagates  itself,  and  the  crop  is 
large.  The  higli  grade  defective  or  moron  is  the  most  troublesome, 
partly  because  he  is  not  easily  recognized  as  defective,  and  partly  because 
he  has  sufficient  mentality  to  go  about  by  himself  and  get  into  all  kinds 
of  mischief,  either  on  his  own  account  or  led  on  by  someone  else.  The 
male  morons  grow  up  into  paupers,  drinkers,  hoboes  and  ne'er-do-wells 
and  fill  our  hospitals  and  asylums.  The  female  morons  grow  up  into 
irresponsible  women  who  replenish  the  ranks  of  the  prostitutes  and  other 
defectives. 

The  Eoyal  Commission  of  England  reports  that  in  that  country  the 
feeble-minded  are  increasing  at  twice  the  rate  of  the  general  population. 
Butler  of  Indiana  states  that  feeble-mindedness  produces  more  pauper- 
ism, degeneracy,  and  crime  than  any  other  source:  that  it  touches  every 
form  of  charitable  activity;  that  it  is  felt  in  every  part  of  the  state,  and 


610  HEREDITY  AND  EUGENICS 

affects,  in  some  way,  all  the  people,  and  that  its  cost  is  beyond  com- 
prehension. The  Committee  of  Visitors  of  the  State  Charities  of 
New  York  reported  that  there  are  in  that  state  32,000  feeble-minded 
persons  (1914).  Of  these,  1,900  are  provided  for  in  institutions  espe- 
cially designed  for  their  care,  and  1,500  in  other  institutions,  leaving  at 
large  22,600.  It  ha-s  been  estimated  that  of  the  32,000  feeble-minded, 
10,000  are  girls  and  Avomen  of  ehild-ljearing  age,  1,750  of  whom  are 
cared  for  in  institutions  designed  for  the  care  of  such  persons,  and  1,625 
are  confined  in  reformatories,  prisons,  and  almshouses,  leaving  about 
7,000  at  large  in  the  community.  Goddard  estimates  that  in  the  way 
of  spreading  disease,  iinmorality,  and  increasing  the  stock  of  the  feeble- 
minded, a  girl  or  a  woman  of  this  class,  of  child-bearing  age,  is  three 
times  as  great  a  menace  to  the  community  as  is  a  feeble-minded  boy  or 
man.  It  is  estimated  that  the  feeble-minded  constitute  25  to  50  per  cent. 
of  the  inmates  of  our  prisons,  15  to  30  per  cent,  of  the  almshouses,  and  a 
still  larger  percentage  of  prostitutes. 

Upwards  of  2  per  cent,  of  juveniles  are  so  defective  mentally  as  to 
be  incapable  of  self-support  and  self-direction,  and  are  largely  irre- 
sponsible. 

Mental  deficiency  can  be  acquired  in  persons  with  good  heredity. 
This  sometimes  occurs  as  a  result  of  injury  to  the  brain,  or  of  cerebral 
hemorrhages  occurring  in  the  course  of  acute  febrile  infections  of  child- 
hood. Other  causes  are : — Bacterial  toxins  which  may  permanently  in- 
jure the  brain  cells  and  prevent  their  development;  cerebrospinal  fever; 
local  meningitis,  resulting  from  middle  ear  disease;  or  serious  impair- 
ment of  the  special  senses,  etc. 

Intelligence  Quotient. — Albert  Binet  first  suggested  that  it  was  pos- 
sible to  take  the  mental  measure  of  normal  and  defective  mentality. 
He  devised  a  measure  scale  for  intelligence.  He  deduced  from  his  ex- 
perience the  following  formula :  "Children  who  are  under  nine  years 
of  age  and  show  a  backwardness  of  more  than  two  years,  are  probably 
mental  defectives  to  the  extent  of  being  actually  feeble-minded;  those 
who  are  nine  years  or  more  and  show  a  backwardness  of  more  than  three 
3'ears  are  also  feeble-minded."  Goddard  .states  that  Binet's  formula  is 
well  within  the  truth,  ilore  accurate  methods  of  measurement,  how- 
ever, have  been  devised,  and  specialists  use  the  "Intelligence  Quotient" 
(I.  Q.).  This  is  obtained  by  dividing  the  mental  age  by  the  age  in  years, 
which  gives  in  the  case  of  backward  children  a  fraction.  If  this  frac- 
tion is  less  than  0.75  there  is  a  very  high  degree  of  certainty  that  the 
person  is  feeble-minded.  If  the  fraction  is  greater  than  0.80,  the  per- 
son while  backward  or  dull  normal  is  not  feeble-minded.  If  the  I.  Q. 
is  between  0.75  and  0.80,  the  case  may  be  a  doubtful  one  and  is  frequently 
called  "border-line." 

The  general  mental  characteristics  that  can  be  determined  without 


DEFECTIVES  -  611 

special  psychological  tests  are  (1)  lack  of  control  of  emotions  and  im- 
pulses, (2)  inability  to  adapt  to  new  conditions,  (3)  inability  to  gen- 
eralize from  experiences  or  to  deal  with  abstractions,  (4)  general  lack 
of  good  judgment  and  good  sense. 

Prevention  of  Propagation  of  Defectives. — Four  methods  have  been 
proposed  to  prevent  the  proinigaliou  of  defectives:  (1)  education;  (2) 
legislation;   (3)   segregation;  (4)   surgery. 

Education. —  Education  directed  toward  the  defective  is  a  failure, 
for  he  is  incapable  of  profiting  by  the  lessons.  The  education  of  the 
better  class  of  the  community  is  indirectly  helpful  in  calling  attention 
to  the  situation  as  being  largely  preventable,  and  to  the  necessity  and 
means  for  controlling  it. 

Bestrictire  Legulation. — Eestrictive  legislation  is  a  praiseworthy 
effort,  but  has  signally  failed  as  a  preventive  measure,  for  the  evident 
reason  that  it  only  adds  illegitimacy  to  degeneracy,  and  thus  the  chil- 
dren enter  on  life's  battle  doubly  handicapped.  Minnesota  has  a  law 
providing  that  within  the  bounds  of  the  state  no  marriage  shall  be 
permitted,  either  party  to  which  is  epileptic,  imbecile,  feeble-minded, 
or  afflicted  with  insanitj^  unless  the  woman  be  over  forty-five,  Michigan, 
Delaware,  Connecticut,  Indiana,  Xew  Jersey,  and  ]^orth  Dakota  have 
also  passed  laws  for  the  purpose  of  jireventing  marriage  among  defectives. 

Segregation. — Segregation  would  be  an  ideal  and  humane  method 
of  isolating  those  who  are  incapable  of  having  normal  offspring,  but  the 
segregation  of  all  degenerates  and  defectives  would  be  an  enormous 
and  impractical  task.  Further,  the  great  difficulty  is  to  detect  the  un- 
fit individual  who  starts  a  strain  of  defectives  and  degenerates.  It  is 
evidently  a  hopeless  task  to  know  where  to  draw  the  line  between  the 
fit  and  the  unfit,  so  that  for  the  present  we  must  be  satisfied  to  enforce 
restrictive  measures  upon  only  those  who  are  evident  and  well-marked 
examples.  Insane  asylums,  homes  for  epileptics,  reformatory  schools, 
as  well  as  special  hospitals  and  institutions  for  advanced  cases  must  not 
be  regarded  as  preventive  measures  in  the  true  sense,  for  such  segrega- 
tion provides  care  and  comfort  as  a  terminal  measure;  that  is,  it  is 
usually  a  last  resort.  Frequently  defectives  propagate  their  kind  before 
and  sometimes  after  they  are  interned  in  such  institutions.  Preference, 
nevertheless,  should  be  given  to  women  of  child-bearing  age  in  institu- 
tional care. 

Although  segregation  of  all  persons  with  higher  types  of  mental 
defect  is  never  likely  to  be  accomplished,  there  is  hope  of  devising  a 
plan  of  registration  and  guardianship  in  the  community  which  will  pro- 
tect a  great  many  and  prevent  their  marriage.* 

*  Fernard,  "What  is  Practicable  in  the  Way  of  Prevention  of  Mental  Defect," 
a  pamphlet  distributed  by  the  National  Committee  for  Mental  Hygiene,  1915. 
Also,  Salmon,  "Outlines  of  a  State  Policy  for  Dealing  with  Mental  Deficiency," 
Medical  Record,  April  17,  1915. 


612  HEEEDITY  AND  EUGENICS 

Surgery. — Sterilization  has  been  proposed  as  a  means  of  controlling 
the  propagation  of  defectives.  This  is  done  either  by  severing  the 
vas  deferens  or  the  Fallopian  tube.  At  the  Indiana  Reformatory  Dr. 
Sharp  carries  out  the  law  ^  of  that  state  providing  for  the  sterilization 
of  defectives.  The  operation  of  vasectomy  consists  of  ligation  and  re- 
section of  a  small  portion  of  the  vas  deferens.  The  operation  is  very 
simple  and  easy  to  perform.  It  may  be  done  vpithout  an  anesthetic, 
either  local  or  general.  As  performed  by  Dr.  Sharp  it  requires  about 
three  minutes,  and  the  subject  returns  to  his  work  immediately,  suf- 
fering no  inconvenience  and  in  no  way  hampered  in  his  pursuit  of  life, 
liberty,  and  happiness,  but  is  effectively  sterilized.  In  456  cases  Dr. 
Sharp  has  had  no  unfavorable  symptoms.  The  operation  is  performed 
as  follows:  After  cleansing  the  scrotum  with  soap  and  water,  fol- 
lowed by  alcohol,  the  spermatic  cord  is  grasped  between  the  thumb  and 
index  finger  of  the  left  hand.  The  vas  deferens  is  detected,'  firmly 
held  and  fixed  with  a  pair  of  bullet  forceps.  It  is  then  exposed  by  a 
small  incision  and  drawn  through  the  scrotum  wound  by  means  of  a 
tenaculum.  It  is  stripped  of  all  membranes  and  the  accompanying  ar- 
tery, ligated  above  and  severed,  care  being  taken  to  cut  away  any  por- 
tion of  the  vas  deferens  that  may  have  been  damaged  in  the  manipula- 
tion. This  is  done  in  order  to  promote  absorption  from  the  interstitial 
cells  of  Leydig,  and  to  avoid  cystic  degeneration  of  the  testicle.  The 
retraction  of  the  muscle  closes  the  skin  wound  and  no  stitch,  collodion, 
or  adhesive  plaster  is  needed.  There  is  no  diminution  of  the  sexual 
power  or  pleasure.  The  discharge  at  the  orgasm  is  but  slightly  de- 
creased. 

The  operation  in  the  female  is  more  difficult,  but  if  carefully  done 
is   no  more   hazardous.      The   Fallopian   tubes   are  reached   through   a 

®  The  Indiana  law  reads  as  follows: 

Whereas,  Heredity  plays  a  most  important  part  in  the  transmission  of 
crime,  idiocy,  and  imbecility; 

Therefore,  Be  it  enacted  by  the  General  Assembly  of  the  State  of  Indiana, 
That  on  and  after  the  passage  of  this  act  it  shall  be  compulsory  for  each  and 
every  institution  in  the  State,  entrusted  with  the  care  of  confirmed  criminals, 
idiots,  rapists,  and  imbeciles,  to  appoint  upon  its  staff,  in  addition  to  the  regular 
institutional  physician,  two  (2)  skilled  surgeons  of  recognized  ability,  whose 
duty  it  shall  be,  in  conjunction  with  the  chief  physician  of  the  institution,  to 
examine  the  mental  and  physical  condition  of  such  inmates  as  are  recommended 
by  the  institutional  physician  and  board  of  managers.  If,  in  the  judgment  of 
this  committee  of  experts  and  the  board  of  managers,  procreation  is  inadvisable 
and  there  is  no  probability  of  improvement  of  the  mental  and  physical  condition 
of  the  inmate,  it  shall  be  lawful  for  the  surgeons  to  perform  such  operation  for 
the  prevention  of  procreation  as  shall  be  decided  safest  and  most  effective.  But 
this  operation  shaHl  not  be  performed  except  in  cases  that  have  been  pronounced 
unimprovable.  .  .  . 

Eleven  other  states  provide  for  the  sterilization  of  either  criminals  or  the 
feeble-minded,  viz.:  California,  Connecticut,  Iowa,  Kansas,  Michigan,  Nevada, 
North  Dakota,  New  York,  New  Jersey,  Washington,  and  Wisconsin.  The  con- 
stitutionality of  the  law  has  been  appealed  to  the  Supreme  Court  in  Iowa.  Bull, 
of  the  Univ.  of  Wisconsin,  No.  82,  1  May,  1914. 


l^KFECTTVES  C13 

niediiiu  incision  and  ligated  ni-ar  the  uUtiis  and  s<.'VL'r(Ml  beyond  the 
ligature. 

Opinions  vary  greatly  concerning  the  proper  use  of  sterilizing  crim- 
inals, insane,  degenerates,  and  detectives  generally.  There  is  no  douht 
concerning  its  effectiveness. 

Sterilization  is  a  measure  which  contains  great  potential  possibili- 
ties for  abuse  and  injustice.  It  probably  will  never  receive  general 
acceptance  on  account  of  the  difficulty  of  determining  upon  whom  the 
operation  shall  be  done.  Even  in  perfectly  clear  cases,  such  as  the  in- 
sane, the  epileptic,  or  the  high  grade  degenerate,  the  harm  has  often 
been  done  before  the  operation  is  decided  upon. 

Statistics .  of  Defectives. — The  large  number  of  defectives  and  unfit 
in  our  country  may  be  gleaned  from  the  following  figures  showing  the 
number  of  inmates  in  state  institutions  in  1913.® 

In  institutions  for — 

Feeble-minded 28,805* 

Insane   205,198**  . 

Criminalistic   (including  delinquent  and  wayward).  84,328 

Epileptic    7,313* 

Inebriate   463 

TnberculoiTS    5,995 

Blind  and  deaf   11.991 

Deformed   456 

Dependent    24,089 

Total   368,638 

*  As  of  January  1,  1916. 
**  As  of  June  30,  1914. 

The  last  census  report  for  the  United  States  gives  data  relative  to 
the  dependents  and  defectives  in  institutions;  the  number  not  in  in- 
stitutions can  only  be  guessed  at.  Kellicott  gives  the  following  ap- 
proximate numbers  in  our  country  in  1904 : 

Insane  and  feeble-minded,  at  least   200,000 

Blind   100,000 

Deaf  and  dumb  100,000 

Paupers  in  institutions   80,000 

Prisoners    100,000 

Juvenile  delinquents  in  institutions   23,000 

The  number  of  persons  cared  for  in  hospitals,  dispensaries,  and 
"homes"  of  various  kinds  in  the  year  1904  was  in  excess  of  two  million. 
All  these  are  not  defectives,  but  many  suffer  from  preventable  disabili- 
ties. 

Salmon  estimates  that  there  are  about  four  mentally  defectives  per 
1,000  of  population. 

"These  figures  were  compiled  by  the  Biu-eau  of  the  Census,  The  Eugenics 
Record  Office,  and  the  National  Committee  for  Mental  Hygiene. 


614  HEREDITY  AJ^D  EUGENICS 

Goddard  states  that  there  are  between  300,000  and  400,000  feeble- 
minded in  the  United  States.  Further,  that  two-thirds  of  them  owe 
their  condition  to  heredity,  and  that  they  are  propagating  their  kind  at 
a  rate,  two  to  six  times  as  fast  as  the  good  stock.  It  is  estimated  that 
the  feeble-minded  constitute  25  to  40  per  cent,  of  the  inmates  of  our 
prisons,  15  to  30  per  cent,  of  the  inmates  of  almshouses,  and  a  still 
larger  percentage  of  prostitutes. 

We  have  to  support  about  500,000  insane,  feeble-minded,  epi- 
leptic, blind,  and  deaf,  80,000  prisoners,  and  100,000  paupers,  at  a  cost 
of  $100,000,000  per  year.  A  new  plague  affecting  2  per  cent,  of  the 
population  and  costing  this  vast  treasure  would  instantly  attract  uni- 
versal attention.  One-sixth  of  the  total  appropriation  of  the  State  of 
Massachusetts  is  for  the  maintenance  of  insane  and  feeble-minded  in 
institutions.  We  have  become  so  used  to  crime,  disease,  and  d.egener- 
acy  that  we  take  them  as  necessary  evils.  "That  many  of  them  were  so 
in  the  world's- ignorance  is  granted ;  th-at  they  must  remain  so  is  denied." 
.Statistical  studies  seem  to  indicate  a  rapid  (at  least  an  unneces- 
sary) increase  of  the  unfit,  defective,  insane,  criminal,  and,  on  the 
other  hand,  a  slow  increase,  or  even  a  decrease  (?),  of  the  fit,  normal, 
or  gifted  stocks.  It  is  plain  to  the  student  of  eugenics  how  such  con- 
ditions account  for  the  rise  and  fall  of  nations. 

The  United  States  census  of  1880  reported  40,942  insane  in  hos- 
pitals and  51,017  not  in  hospitals;  a  total  of  91,959  known  insane.  In 
1903  it  was  estimated  that  there  was  a  total  of  180,000  in  the  United 
States.  Thus,  the  ratio  of  known  insane  in  the  total  population  was 
225  per  100,000  in  1903,  as  compared  with  183  per  100,000  in  1880. 
On  January  1st,  1920,  there  were  232,680  patients  with  mental  dis- 
ease in  hospitals  for  the  insane  in  this  country.  Including  those  on 
parole,  the  number  would  be  over  250,000  (see  page  422).  These 
figures  must  not  be  taken  as  an  index  of  the  increase  of  insanity 
in  the  population  at  large — for  institutional  care  has  been  growing 
much  more  popular  during  the  past  decade,  especially  since  more  hu- 
mane methods  have  been  adopted.  Further,  the  classification  of  insan- 
ity now  includes  many  cases  that  were  formerly  little  noticed.''  This  sub- 
ject is  fully  discussed  in  Section  II. 

'  A  special  census  of  the  insane  confined  in  institutions  was  taken  by  the 
Bureau  of  the  Census  in  1910,  and  it  was  found  that  187,454  patients  were  con- 
fined in  hospitals  for  the  insane  in  the  continental  United  States. 

While  the  population  of  the  United  States  increased  about  11  per  cent,  in 
the  interval  between  1904  and  1910,  the  population  in  insane  asylums  increased 
about  25  per  cent.  The  number  of  insane  in  asylums  per  100,000  population 
increased  from  186.2  in  1904  to  203.8  in  1910.  The  number  of  persons  annually 
committed  to  hospitals  for  the  insane  per  100,000  population  increased  from  61.5 
in  1904  to  65.9  in  1910.  If  these  ratios  are  accepted  as  representing  insanity 
rates,  it  would  appear  that  the  number  of  persons  becoming  insane,  in  a  com- 
munity comprising  100,000  persons,  was  greater  by  4.4  in  1910  than  it  was  in 
1904.    It  must  be  remembered,  however,  that  these  figures  include  only  the  insane 


in-:i'i-:("ri\'Ks  eis 

The  conijiaratively  large  and  increasing  numbers  ol  dei'eetives  and 
weaklings  among  the  civilized  races  compared  with  wild  animals  may 
be  accounted  for  by  the  fact  that  atavism  and  reversion  are  more  fre- 
quently met  with  in  artificially  cultivated  strains,  such  as  civilized 
man  ;  and  the  further  fact  that  our  charitable  and  philanthropic  efforts 
foster  and  even  favor  the  unfit. 

Degenerate  Families. — A  careful  study  has  been  made  of  the  records 
of  several  t'aniilies  in  which  the  mating  of  unfit  individuals  has  begotten 
a  swarm  of  unfit  descendants. 

One  of  the  best  known  families  of  this  type  is  the  so-called  Jukes 
family  of  Xew  York  State  investigated  by  Dugdale.  This  family  is 
traced  from  the  fi\e  (buigliters  of  a  lazy  and  irresponsible  fisherman 
born  in  lT"-^0.  In  five  generations  the  descendants  of  Jukes  numbered 
about  l."^00  persons^,  including  nearly  200  who  married  into  it.  The 
histories  of  540  of  these  are  well-known,  and  al)oiit  -jOO  more  are  partly 
known-.  Some  300  died  in  infancy.  Of  the  remaining  900,  310  were 
professional  paupers  living  in  almsliouses  (a  total  of  2,300  years)  ;  440 
were  physically  wrecked  by  their  own  diseased  wickedness;  more  than 
half  of  the  women  were  prostitutes;  130  were  convicted  criminals;  60 
were  habitual  thieves;  7  were  murderers.  Xot  one  had  even  a  common 
school  education;  only  20  learned  a  trade,  and  10  of  these  learned  it  in 
State's  prison.  The  descendants  of  Jukes  in  five  generations  have  cost 
XeAv  York  State  over  one  million  and  a  quarter  dollars,  and  the  cost  is 
still  going  on. 

Probably  the  most  complete  family  history  of  this  kind  ever  worked 
out  is  that  of  the  "Familie  Zero,"  a  Swiss  family  whose  pedigree  has  been 
studied  by  Jorger.  In  the  seventeenth  century  this  family  divided  into 
three  lines.  Two  of  these  have  ever  since  remained  valued  and  highly 
respected  families,  while  the  third  has  descended  to  the  depths.  This 
third  line  was  established  by  a  man  who  was  himself  the  result  of  two  gen- 
.  erations  of  intermarriage,  the  second  tainted  with  insanity.  He  was  of  a 
roving  disposition,  and  in  the  Alalia  Fontana  found  an  Italian  vagrant 
wife  of  vicious  character.  Their  son  inherited  fully  the  parental  traits 
and  himself  married  a  member  of  a  German  vagabond  family — Marcus. 
This  marriage  sealed  the  fate  of  their  hundreds  of  descendants.  The 
pair   had   seven   children,   all   characterized   by   vagabondage,   thievery, 

who  are  committed  to  hospitals.  As  to  the  number  of  cases  of  insanity  not 
resulting  in  commitments  to  hospitals  the  census  has  no  data.  It  is  entirely 
possible  that  the  increase  in  the  number  of  commitments  per  100.000  population 
is  not  due  to  any  considerable  degree  to  an  increased  prevalence  of  insanity,  but 
simply  to  the  extension  of  this  method  of  caring  for  the  insane.  It  is  a  change 
which  might  result  from  an  increase  in  the  number  of  institutions  of  this  class 
and  from  the  increasing  disposition  on  the  part  of  the  public  to  resort  to  such 
institutions.  In  this  connection  it  may  be  noted  that  the  number  of  institutions 
for  the  insane  reported  by  the  census  increased  from  328  in  1904  to  372  in 
1910,  an  increase  of  about  13  per  cent.  The  average  number  of  inmates  per 
institution  increased  from  458  in  1904  to  504  in  1910. 


616 


HEEEMTY  AND  EUGENICS 


& 


^ 


drunkenness,  menial  and  physical  defects,  and  immorality  (Kellicott). 
How  much  of  this  is  due  to  heredity  and  how  much  to  environment  will 
be  discussed  presently.  ^"h 

Another  interesting  example  of  ^? 

the  same  type  has  been  described  ^^  ^ 

by  Poellmann.  This  family  was 
established  by  two  daughters  of  a 
woman  drunkard  who  in  five  or 
six  generations  produced,  all  told, 
834  descendants.  The  histories  of 
709  of  these  are  known.  Of  the 
709,  107  were  of  illegitimate  birth, 

64  were  inmates  of  almshouses,  162  /   /    ^  . 

were  professional  beggars,  164  were 
prostitutes,  and  17  procurers,  76 
had  served  sentences  in  prison,  ag- 
gregating 116  years,  7  were  con- 
demned for  murder. 

Dr.    Henry  H.    Goddard «   ha^ 
investigated  and  compiled  the  re-         ^ 
suits  of  his  work  on  the  heredity 
of  a  most  remarkable  family,  the       ^-^ 
Kallikak  family.    During  the  Eevo-         ™ 
lutionary    days,    the    first   Martin 
Kallikak   (the  name  is  fictitious), 
descended  from  a  long  line  of  good 
English    ancestry,   took   advantage 
of  a  feeble-minded  girl.    The  result 
of  their  indulgence  was   a  feeble- 
minded son.     This  son  married  a 
normal  woman.    They  in  turn  pro- 
duced five  feeble-minded  and  two 

normal   children.      Practically   all  \  W 

of  the  descendants  of  these  defec- 
tives have  been  traced,  as  well  as 
those    of    the    two    normals.      The  |^ 

tragic  story  follows : 

From  both  normal  and   defec- 
tive descendants  of  this  union  came 

a  long  line  of  defective  stock.    There  were  480  in  all.     Of  these  36  were 
illegitimate,  33  sexually  immoral,  24  confirmed  alcoholics,  and  3  epilep- 
«"The   Kallikak   Family,   a   Study   in   the   Heredity   of   Feeble-mindedness," 
New  York,  Macmillan  Company,  1912. 

See  also   "The  Story   of  the  Dack   Family:      A   Study   in   Eugenics.        tm- 
layson,  Bull.  No.  15,  Eugenics  Eecord  Office. 


PEFECTTVES  617 

tics.  Eighty-two  died  in  infancy,  3  were  criminal,  8  kept  houses  of  ill 
fame,  and  143  were  distinctly  feeble-minded.  Only  40  were  found  who 
were  apparently  normal.  The  rest  are  unknown  or  doubtful.  But  the 
scion  of  the  good  fainily  who  started  this  long  line  of  delinquent  and 
defective  progeny  is  also  resixmsible  for  a  strain  of  an  entirely  different 
character.  After  the  Revolutionary  War  was  over,  lie  married  a  Quaker 
girl  of  good  ancestry  and  settled  down  to  live  a  respectable  life  after  the 
traditions  of  his  forefathers.  From  this  legal  union  with  a  normal 
woman  there  have  been  49G  descendants.  All  of  these  except  two  have 
been  of  normal  mentality.  The  exceptions  were  cases  of  insanity,  pre- 
sumably inherited  through  marriage  with  an  outside  strain  in  which 
there  was  a  constitutional  psychopathic  tendency.  In  all  the  49G  there 
is  not  an  instance  of  feeble-niiudedness.  The  offspring  descended  from 
this  side  of  the  house  have  universally  occupied  positions  in  the  upper 
walks  of  life.  They  have  never  been  criminals  or  ne'er-do-wells.  On  the 
other  hand,  there  has  not  been  a  single  instance  of  exceptional  ability 
among  the  descendants  of  the  first  ]\rartin  Kallikak  and  the  feeble- 
minded girl.  Most  of  these  descendants  have  failed  to  rise  above  the 
dead  level  of  mediocrity;  indeed,  most  of  them  have  fallen  far  below 
even  this  minimum  standard. 

The  fact  that  the  descendants  of  both  the  normal  and  the  feeble- 
minded mother  have  been  traced  and  studied  in  every  conceivable  en- 
vironment, and  that  the  respective  strains  have  always  been  true  to 
type,  tends  to  confirm  the  belief  that  heredity  has  been  the  determining 
factor  in  the  formation  of  their  respective  characters.  In  the  cities 
the  descendants  of  the  legal  marriage  with  the  normal  woman  are 
physicians,  lawyers,  and  prominent  business  men,  while  the  descendants 
of  the  feeble-minded  mother  are  almost  invariably  found  in  the  slums. 
In  the  rural  districts  the  descendants  of  the  normal  mother  and  her  con- 
sort are  wealthy  and  influential  farmers,  while  the  others  never  rise 
above  the  rank  of  farm  laborers  and  shiftless  men  and  women,  who  are 
unable  to  subsist  without  the  aid  of  charity.  Many  representatives  of 
the  defective  branch  are  inmates  of  almshouses,  while  there  are  no 
paupers  at  all  among  the  normal  descendants. 

In  many  ways  this  study  of  Goddard's  far  outweighs  in  importance 
the  famous  comparison  by  Dr.  ^Yinship  of  the  Jukes  and  Edwards  fam- 
ilies. In  that  case  the  simple  fact  was  demonstrated  that  a  good  family 
like  that  of  the  illustrious  Jonathan  Edwards  had  given  rise  to  innu- 
merable examples  of  the  highest  intellectual  and  moral  worth,  whereas 
the  criminal  Jukes  for  seven  generations  contributed  nothing  to  the 
common  good  and  cost  the  state  of  Xew  York  large  sums  of  money. 
But  the  Jukes  family  and  the  Edwards  family  had  no  ancestor  in 
common.     Their  environment  was  totally  different  and  they   lived  in 


618 


HEREDITY  AND  EUGENICS 


entirely  separate  communities.  Although  from  sociologic  and  economic 
points  of  view  the  history  of  the  Jukes  family  and  its  comparison  with 
that  of  the  family  of  Jonathan  Edwards  has  great  value,  it  is  of  but 
scant  scientific  importance  as  compared  with  that  of  the  Kallikak  family, 
for  here  a  natural  object-lesson  in  eugenics  shows  unmistakably  the 
manner  in  which  after-coming  generations  from  a  given  mating  receive 
the  characteristics  of  the  dominant  strain,  which  in  the  elder  (illegiti- 
mate) Kallikak  line  was  the  inferior  strain,  with  only  a  debased  and 
enfeebled  heritage  to  hand  on.^ 


DAPWfN 

Vt*t9 


LI 


C ALTON 


9=j=^ 


9t«' 


cr 


1 
® 


if 


^t9 


cf     cT      «r 


7 


^ 


1 


CT       ®     0 


r 


i 


1 


^  shows  a  man  of  scicnlific  ability  ;  ^  shows  a  man  of  scientific  ability,  who  is  also  a 
FcHow  of  ihc  Royal  Society  ;  Q^  shows  five  other  children,  and  so  on. 

Fig.  6.3. — History   (Condensed  and  Incomplete)   of  Thbee  Markedly  Able 
Families  (After  Wlientham)    (Kellicott). 

In  contrast  to  these  we  have  the  descendants  of  the  families  of 
Wedgwood,  Darwin,  and  Galton,  the  Edwards  family  and  the  \Yard 
family.  These  three  noted  families  contained  a  large  number  of  states- 
men, jurists,  professors,  physicians,  officers  in  the  army  and  navy,  prom- 
inent authors  and  writers,  and  occasionally  men  and  women  of  genius. 
They  show  a  long  line  of  usefulness  in  every  department  of  social  prog- 
ress, and  not  one  of  them  ever  has  been  convicted  of  a  crime. 

How  much  of  this  is  due  to  heredity  and  how  much  to  environment 
are  debatable  questions.  Students  of  biology  are  convinced  that  heredity 
plays  the  major  role  in  the  lives  of  the  individuals  in  the  above-men- 
tioned families.    In  how  far  such  extreme  instances  as  those  given  above 

«J.  A.  M.  A.,  Oct.  26,  1912,  LIX,  17,  p.  1545. 


EUGENICS  G19 

represent  tlie  rule  or  exceptions  it  will  r('(juir<'  luiicli  adiliiiiMiiil  il;it;i  iiiul 
long  years  of  study  to  determine  (see  pages  425  and  G38). 


EUGENICS 

The  science  of  eugenics  has  been  defined  as  "the  science  of  being 
well  born."  According  to  Galton,  "eugenics  is  the  study  of  the  agen- 
cies under  social  control  that  may  improve  or  impair  the  racial  quali- 
ties of  future  generations  either  physically  or  mentally." 

The  aim  of  eugenics  is  to  increase  the  number  of  best  specimens 
in  each  class;  that  done,  leave  them  to  work  out  their  common  civiliza- 
tion in  their  own  way.  It  also  aims  to  leave  a  good  heritage  to  the 
next  generation  and  to  repress  the  propagation  of  the  vicious  and  de- 
fective classes. 

The  success  of  eugenics  depends  almost  entirely  upon  our  knowl- 
edge of  heredity  and  sociology.  Therefore,  the  fundamental  principles 
of  heredity  should  be  familiar  to  all  students  of  preventive  medicine. 

The  present  movement  started  in  1865  when  Francis  Galton  showed 
that  mental  qualities  are  inherited,  just  as  are  physical  qualities,  and 
pointed  out  that  this  opened  a  way  to  an  improvement  of  the  race  in 
all  respects.  Galton's  work  on  "Hereditary  Genius,"  published  in  1869, 
again  emphasized  the  possibility  and  desirability  of  improving  the 
natural  qualities  of  the  human  race.  The  word  "eugenics"  was  coined 
in  1883  in  his  "Inquiries  Into  the  Human  Faculty." 

There  is  no  doubt  concerning  the  desirability  of  breeding  better 
human  stock,  but  how  this  may  be  accomplished  practically  is  a  diffi- 
cult question.  The  program  of  the  eugenist  is  perplexing  and  compli- 
cated: To  follow  the  theoretical  extremists  would  require  a  social  revo- 
lution-— a  change  from  the  present  method  of  haphazard  mating.  The 
threshold  of  the  subject  has  scarcely  been  passed,  and  we  must  bear 
in  mind  that  some  of  the  striking  men  of  genius  from  whom  the  world 
has  greatly  profited  have  been  individuals  whom  the  student  of  genetics 
would  regard  as  degenerates  or  defectives.  Eugenics  does  not  mean 
free  love,  nor  does  the  eugenist  recommend  Burbanking  the  human  race 
to  produce  great  physical  strength,  beauty,  endurance,  mental  or  moral 
power.  One  point  only  in  the  program  is  perfectly  clear,  and  that  is  that 
a  check  should  be  placed  upon  the  propagation  of  the  crop  of  defectives 
by  means  already  pointed  out. 

The  known  facts  of  heredity  and  the  study  of  eugenics  make  us 
examine  more  critically  some  of  the  directions  which  preventive  medi- 
cine, including  philanthropy  and  social  uplift,  has  taken.  We  must  now 
ask  ourselves  the  question  whether  it  would  not  be  better  for  the  future 
generations  if  we  helped  the  fit  instead  of  concentrating  all  our  attention 


620  HEREDITY  AXD  EUGEJ^ICS    . 

and  sympathies  upon  the  weakling  and  the  unlit.  These  are  problems 
raised  by  Galton,  who  questions  whether  some  of  our  philanthropic  efforts 
are  well  balanced  and  well  directed. 

It  is  important  to  recognize  that  many  diseases  are  due  to  defects  of 
society.  Sociology^  therefore,  must  come  to  the  aid  of  preventive  medi- 
cine. Crime  is  often  a  defect  that  needs  treatment  rather  than  punish- 
ment. Poverty  is  one  of  the  chief  causes  of  diseases,  and  ignorance  one 
of  its  first  allies.  Hence,  constructive  reforms  must  aim  for  social 
justice,  education,  and  the  teachings  of  eugenics. 

According  to  the  teachings  of  genetics,  all  men  are  not  created  free 
and  equal;  but  bound  by  their  protoplasmic  make-up  and  unequal  in 
their  powers  and  responsibilities. 

It  is  evidently  now  of  great  importance  to  collect  a  large  number 
of  pedigrees,  in  which  the  data  shall  be  stated  ^vith  scientific  exactness 
and  in  minute  detail.  Such  a  mass  of  facts  may  then  be  studied  in  the 
light  of  science  in  order  to  determine  in  how  far  the  laws  of  heredity 
apply  to  human  characters.  This  is  being  done  by  the  Eugenics  Eecord 
Office  at  Cold  Springs  Harbor,  Xew  York,  under  the  patronage  of  the 
Carnegie  Institution. 

Specifically,  the  Eecord  Office  seeks  pedigrees  of  families  in  which 
one  or  more  of  the  following  traits  appear :  short  stature,  tallness,  cor- 
pulency; special  talents  in  music,  art,  literature,  mechanics,  invention, 
and  mathematics;  rheumatism,  multiple  sclerosis,  hereditary  ataxy, 
Meniere's  disease,  chorea  of  all  forms,  eye  defects  of  all  forms,  otosclero- 
sis, peculiarities  of  hair,  skin,  and  nails  (especially  red  hair),  albinism, 
harelip  and  cleft  palate,  peculiarities  of  the  teeth,  cancer,  Thomsen's 
disease,  hemophilia,  exophthalmic  goiter,  diabetes,  alkaptonuria,  gout, 
peculiarities  of  the  hands  and  feet  and  of  other  parts  of  the  skeleton. 

In  brief,  then,  the  aim  of  eugenics  is  throiigh  heredity  to  give  the 
individual  the  greatest  of  all  birthrights,  good  human  protoplasm — and 
to  eliminate,  as  far  as  may  be  possible,  bad  human  protoplasm. 


PRINCIPLES  OF  HEREDITY 

For  a  clearer  understanding  of  the  hereditarv'  transmission  of  dis- 
ease, malformations,  and  defects,  it  is  necessary  to  have  an  miderstand- 
ing  of  the  principal  views  upon  organic  evolution  and  the  theories  of 
heredity.  The  student  of  preventive  medicine  should  especially  have 
a  clear  comprehension  of  Mendel's  work,  which  has  throAvn  a  flood  of 
light  upon  the  problems  before  us.  Mendel  has  opened  new  vistas  in 
biology',  which  have  a  practical  bearing  upon  public  health  work.  It 
is  evidently  impossible  in  a  short  space  to  do  justice  to  such  large  sub- 
jects as  evolution  and  heredity,  and  the  student  is,  therefore,  referred 


PRINCIPLES  OF  HEREDITY  G2l 

to  ilic  authorities  given  at  the  end  of  this  chapter,  which  will  repay 
careful  study. 

Variation. — It  has  been  a  matter  of  common  observation  that  like 
tends  to  Itegct  like  rather  than  "like  begels  like/'  for  there  is  a  ten- 
dency toward  new  departures. 

Two  distinct  sorts  of  divergences  may  appear  among  the  members 
of  a  single  family.  The  first  is  known  as  variation;  the  second  as 
mutation. 

By  variation  we  understand  those  slight  differences  which  invariably 
distinguish  all  the  members  of  every  family.  They  consist  of  individual 
differences  which  affect  every  part  and  every  character.  Sucli  dif- 
ferences are  also  know^n  as  fluctuating,  normal,  or  continuous  variations 
to  distinguish  them  from  abnormal,  definite,  or  discontinuous  varia- 
tions, which  are  more  properly  termed  mutations.  As  examples  of 
variation  in  man  we  may  cite  the  differences  in  size  or  stature,  color  of 
skin  and  eyes,  curliness  of  hair,  configuration  of  features,  etc. 

Darwin  lays  particular  emphasis  upon  the  importance  of  variation 
in  his  views  of  organic  evolution. 

Darwin's  Theory — The  Survival  of  the  Fittest. — Darwin's  views  ^^ 
of  heredity  form  tiie  basis  of  his  theory  of  organic  evolution.  Tw^o 
separate  factors  are  primarily  concerned:  (1)  the  fact  of  fluctuating 
variation,  that  is,  that  no  two  members  of  the  same  family  ever  resemble 
one  another  exactly;  and  (2)  the  occurrence  of  a  struggle  for  existence 
between  organisms,  owing  to  the  geometric  rate  of  increase  of  living 
things.  From  these  two  facts  it  foUow^s  that,  when  a  change  of  environ- 
ment takes  place,  certain  members  of  an  existing  species  will  be  some- 
what better  adapted  than  others  to  withstand  the  new^  conditions,  and 
the  former  will  tend  to  survive  to  the  exclusion  of  the  latter.  Darwin 
assumes  that  during  long  series  of  generations  this  process  will  result 
in  a  steady  change  in  the  character  of  the  species  in  the  direction  of 
better  adaptation  to  the  new-  conditions.  In  other  words,  Darwin 
considers  that  an  accumulation  of  a  series  of  small  changes  due  to  the 
influence  of  environment  are  transmitted  hereditarily  through  natural 
selection. 

The  remarkable  effects  produced  in  the  case  of  domestic  animals  and 
plants  by  the  action  of  artificial  selection  greatly  influenced  Darwin's 
views  upon  the  selective  influences  which  exist  in  nature.  Darwin  be- 
lieved in  the  hereditary  transmission  of  acquired  characters  and  re- 
garded organic  evolution  as  proceeding  by  a  slow,  gradual,  or  continuous 
process.  There  can  be  no  doubt  that  natural  and  sexual  selection  have 
a  great  influence,  but  whether  sufficient  to  originate  new  species  or 
even  new  specific  characters  is  a  question.  Xow  that  the  transmis- 
sion of  acquired  characters  is  denied  by  students  of  heredity,  and  the 

^"Darwin:    "The  Origin  of  Species,"  etc. 


622  HEREDITY  AND  EUGENICS 

fact  that  DeVries  has  actually  observed  new  species  arise  suddenly, 
this  portion  of  Darwin's  theory  of  organic  evolution  and  the  origin  of 
species  is  receiving  critical  examination. 

Darwin  firmly  believed  that  the  characters  of  organisms  can  be 
modified  by  selection,  and  he  made  this  the  foundation  stone  of  his 
theory  of  evolution.  The  brilliancy  of  the  mutation  theory  of  DeVries,. 
coupled  with  his  great  service  to  biology  in  rediscovering  the  Mendelian 
laws,  has  somewhat  dazzled  our  eyes.  Castle  believes,  after  ten  years 
of  continuous  work  in  selection,  that  much  may  be  accomplished  by 
this  means  quite  apart  from  the  process  of  mutation,  and  considers 
that  the  work  of  DeVries  himself  argues  strongly  in  favor  of  this  idea, 
although  his  interpretation  of  it  is  adverse  to  selection.  From  the  evi- 
dence at  hand  we  must  conclude  that  Darwin  was  right  in  assigning 
great  importance  to  selection  in  evolution,  that  progress  resul.ts  not 
merely  from  sorting  out  particular  combinations  by  large  and  striking 
unit  characters,  but  also  from  the  sele-ction  of  slight  difl^erences  in  the 
potentiality  of  gametes  representing  the  same  unit  character  combina- 
tions. 

Mutation. — Mutations  comprise  definite  differences,  usually  of  con- 
siderable magnitude — differences  that  indicate  specific  characters  or  the 
beginning  of  new  species.  Such  differences  are  also  known  as  abnormal, 
definite,  or  discontinuous  variations,  but  more  properly  they  are  termed 
mutations,  sometimes  "sports."  Mutations  may  be  either  useful  or 
harmful.  They  arise  "spontaneously"  and  are  transmitted  in  accordance 
with  Mendel's  law.  As  examples  of  mutations  in  man  we  may  cite  albin- 
ism, polydaetylism,  brachydactylism,  etc. 

DeVries,  Bateson,  and  the  "mutationists"  are  convinced  that  muta- 
tion is  a  much  more  important  factor  in  the  origin  of  species  than  varia- 
tion, as  understood  by  Darwin.  In  the  light  of  Mendel's  work  mutations 
appear  to  be  unit  characters  which  arise  "spontaneously" — in  some  in- 
stances they  represent  recessive  characters  that  have  remained  dormant 
for  many  generations. 

DeVries — Discontinuous  Evolution. — The  observations  of  DeVries 
upon  the  evening  primrose  (Oenothera  lamarcl-iana)  convinced  him  that 
species  may  arise  suddenly,  that  evolution  is  discontinuous  and  goes  by 
leaps  and  bounds  rather  than  by  the  slow  or  continuous  process  of  or- 
ganic evolution  described  by  Darwin. 

Mutation  is  the  term  applied  by  DeVries  to  express  the  process  of 
origination  of  a  new  species  or  a  new  specific  character,  when  this  takes 
place  by  the  discontinuous  method  at  a  single  step.  DeVries  believes 
that  this  is  the  most  important,  if  not  the  sole,  method  by  which  new 
species  or  specific  characters  arise.  To  those  who  are  convinced  that 
acquired  characters  are  not  inherited  the  explanations  of  Lamarck  and 
Darwin  have  always  been  incomplete.     Darwin  insisted  that  nature  does 


PETNCIPLES  OF  HEREDITY 


623 


not  make  junijis  and  that  new  species  arise  slowly  throui^di  tlu;  action 
of  natural  selection  on  minute  variations — a  fi^radual  or  continuous  evo- 
lution.^^ From  his  experiments  DeVries  concludes  that  when  selection 
is  really  efficient  the  full  possible  effects  of  this  process  are  exhausted  in 
quite  a  small  number  of  generations,  and  that  then  the  only  further 
effect  of  selection  is  to  keep  up  the  standard  already  arrived  at.  DeVries 
actually  observed  quite  a  number  of  new  types  of  plants  which  arose 
suddenly  and  naturally.  When  they  made  their  c 
appearance  the  majority  of  the  new  types  came 
true  to  seed.  With  regard  to  the  causes  of  muta- 
tion little  is  known,  unless  we  assume  that  they 
represent  unit  characters  which  have  long  re- 
mained recessive. 

Weismann's  Views. — Weismann's  ^^  views  are 
based  largely  upon  his  assumption  that  the  germ 
plasm  is  distinct  from  the  body  and  that  acquired 
characters  are  not  inherited.  The  parent  is  com- 
posed biologically  of  somatic,  or  body  cells,  which 
are  mortal,  and  reproduction  cells,  or  germ  plasm, 
which  are  distinct,  continuous,  immortal.  The 
germ  cells  undergo  the  least  modification  from 
their  original  condition.  Indeed,  Weismann  be- 
lieves that  there  is  no  reason  for  supposing  that 
they  have  undergone  any  modification  at  all. 
From  this  point  of  view  we  may  consider  the 
nature  of  a  given  series  of  animals  as  being  de- 
termined only  by  the  particular  series  of  cells 
which  constitute  the  direct  ancestry  of  the  germ 
cells  in  each  individual.  The  cells  which  make 
up  the  bodily  structure  may  be  regarded  as  the 
result  of  so  many  offshoots  which  come  to  an 
end  at  the  death  of  the  organism  and  have  no 
progeny  of  their  own. 

The  minute  study  of  the  germ  cells  taken  in  connection  with  modern 
experimental  work  on  the  methods  by  which  inheritance  takes  place 
shows  a  strong  tendency  to  confirm  Weismann's  views,  so  far  as  the 
inheritance  of  distinct  and  definite  characters  is  concerned. 

Wilson  ^^  has  expressed  Weismann's  theory  as  follows :  It  is  a  reversal 
of  the  true  point  of  view  to  regard  inheritance  as  taking  place  from  the 
body  of  the  parent  to  that  of  the  child.     The  child  inherits  from  the 

"  Darwin,  however,  recognized  the  facts  of  mutations  or  "sports"  as  he 
called  them  and  dwelt  upon  their  importance. 

"Weismann,  A.:  "Essays  upon  Heredity,"  1889,  and  "The  Evolution 
Theory,"  1906. 

'^  Wilson :    "The  Cell  in  Development  and  Inheritance,"  p.  13, 


Fig.  64. — Wilson's  The- 
ory OF  Inheritance 
Modified  by  Lock  ( G, 
germ  cells;  S,  somatic 
cells). 


634  HEEEDITY  AND  EUGENICS 

parent  germ  cell,  not  from  the  parent  body,  and  the  germ  cell  owes  its 
characters  not  to  the  body  which  bears  it,  but  to  its  descent  from  a  pre- 
existing germ  cell  of  the  same  kind.  Thus,  the  body  is,  as  it  were,  an 
offshoot  from  the  germ  cell.  As  far  as  inheritance  is  concerned,  the 
body  is  merely  the  carrier  of  the  germ  cells  which  are  held  in  trust  for 
coming  generations.  Fig.  64  illustrates  Wilson's  theory  of  inheritance 
as  modified  by  Lock. 

Mendel's  Law. — We  are  indebted  to  Mendel  ^*  for  one  of  the  most 
important  observations  of  biology — the  most  important,  in  fact,  with 
reference  to  heredity.  The  essential  factors  of  Mendel's  discovery  are: 
(1)  unit  characters,  (2)  dominance,  (3)  segregation.  By  a  unit  charac- 
ter is  understood  any  characteristic  of  an  individual  that  is  transmitted 
from  parent  to  offspring  through  successive  generations  and  which  con- 
forms to  the  following :  When  parents  with  complementary  unit  charac- 
ters unite,  it  is  found  that  one  character  predominates  over  the  other. 
This  is  known  as  dominance.  It  has  further  been  found  that  the  unit 
characters  contributed  by  the  respective  parents  do  not,  as  a  rule,  blend, 
but  remain  separate  or  distinct.  This  is  known  as  segregation.  The 
principles  of  segregation  and  dominance  have  been  found  to  apply  to  the 
inheritance  of  many  characters  in  animals  and  plants.  It  should  be  care- 
fully borne  in  mind  that  the  unit  characters  themselves  are  not  trans- 
mitted as  such  in  the  germ  cells.  Just  what  is  transmitted  is  not  defi- 
nitely known.  It  is  quite  sure  that  the  only  thing  that  is  inherited  in  the 
germ  cells  is  something  which  determines  the  development  of  the  unit 
character.    This  something  is  called  a  determiner. 

The  essence  of  this  great  discovery  was  published  by  Mendel  in  a 
short  paper  in  1866.  By  some  extraordinary  chance  Mendel's  observa- 
tions were  entirely  lost  sight  of  until  the  same  facts  were  independently 
rediscovered  in  1899  -by  DeVries,  working  in  Holland,  by  Correns  in 
Germany,  and  by  Tschermak  in  Austria. 

Mendel's  law  may  best  be  understood  from  a  concrete  illustration. 
One  of  the  simplest  cases  is  that  of  the  heredity  of  color  in  the  Andalu- 
sian  fowl,  which  has  been  so  clearly  described  by  Bateson. 

There  are  two  established  color  varieties  of  this  fowl :  one  with  a  great 
deal  of  black  and  one  that  is  white  with  some  black  markings  or  splashes. 

"Gregor  Johann  Mendel  was  born  July  22,  1822,  at  Heizendorf  in  Austrian 
Silesia.  In  1843  he  entered  the  Augustine  Convent  at  Altbrunn  as  a  novice, 
and  was  ordained  priest  in  1847.  Mendel  was  a  teacher  of  natural  science  in 
the  Brunn  Realschule  from  1853  to  1868,  when  he  was  appointed  abbot  of  his 
monastery. 

Mendel  published  only  the  results  of  his  work  upon  hybridization  with  peas 
and  a  few  of  his  experiments  with  Hieracium.  The  original  paper  on  "Hybridi- 
zation" was  published  in  the  Verh.  Naturf.  Ver.  in  Brunn,  Abhandlungen  IV, 
1865,  which  appeared  in  1866;  the  paper  on  "Hieracium"  appeared  in  the  same 
journal,  VIII,  1869.  The  student  is  advised  to  read  "Mendel's  Principles  of 
Heredity"  by  W.  Bateson,  1909,  in  which  he  will  find  a  translation  of  these  two 
important  papers.  A  clear  exposition  is  also  given  by  R.  C.  Punnett  in  hi3 
book  entitled  "Mendelism"    ('1911). 


I'lllXClPLES  OF  HEREDITY 


025 


A  Schematic  Representation  of  Mendel's  Law 

D  R.  .  .  .P' — great-g^randparental  generation 

D  R.  .  .  .P' — prandparental  generation. 

D  R.  . .  .P^ — iparental  generation. 

\  / 


\  / 


r)(R) 


F' — first  filial   (hybrid)   generation. 


2DD  2D(R)  IRR  F'— second   filial 

Pure  dominants  Impure  dominants  Pure  recessives         (inbred)  genera- 

tion. 


DD   IDD 


2D(R) 


IRR 


DD 


DD  IDD  2D(R)   IRR  RR 


RR 


RR 


F' — third  genera- 
tion. 


F^ — fourth  genera- 
tion. 


D  and  R  represent  complementary  unit  characters.  D  the  dominant  character, 
and  R  the  recessive  character.  D(R)  represents  a  dominant  with  the  recessive 
character  unexpressed  but  potentially  present.  DD  means  pure  dominants,  and 
RR  pure  recessives. 


For  convenience  we  may  refer  to  these  as  the  hlack  and  white  varieties 
respectively.  Each  of  these  breeds  true  by  itself.  Black  mated  with 
black  produce  none  but  black  offspring.  White  mated  with  white  pro- 
duce none  but  white  offspring.  Crossing  black  and  white,  however,  re- 
sults in  the  production  of  fowls  with  a  sort  of  grayish  color  called 
"blue"  by  the  fancier,  though  in  reality  it  is  a  fine  mixture  of  black  and 
white.  If  we  continue  to  breed  succeeding  generations  from  these 
blue  hybrid  fowls  we  get  three  different  colored  forms.  Some  will  be 
blue,  like  the  parents,  some  black,  like  one  grandparent,  some  white, 
like  the  other  grandparent.  Further,  these  different  colors  appear  in 
certain  definite  proportions  among  the  three  classes  of  descendants.  Of 
the  total  number  of  the  inmiediate  offspring  of  the  hybrid  blues,  ap- 
proximately one-half  will  be  blue,  like  the  parents,  approximately  one- 
fourth  black,  and  one-fourth  white,  like  each  of  the  grandparents.  Thus, 
black  bred  together  produce  only  blacks :  the  white  similarly  produce  only 
whites;  the  blues,  on  the  other  hand,  when  bred  together  produce  a 
progeny  sorting  into  three  classes,  and  in  the  same  proportion  as  that 
produced  by  the  blues  of  the  original  hybrid  generation.  The  fact  that 
the  black  grandchildren  and  the  white  grandchildren  respectively  breed 
true  is  a  very  important  fact.     In  this  illustration  no  race  of  the  hybrid 


626 


HEEEDITY  AND  EUGENICS 


blue  character  can  be  established,  for  the  blues  always  produce  blacks 
and  whites  as  well  as  blues  (see  Fig.  65). 

Another  instance  which  illustrates  the  phenomenon  of  dominant  and 
recessive  characters  as  well  as  segregation  is  here  given.    If  black  and 


^t?  t?^ 


Fig.  65. — Diagram  Showixg  the  Coi'k.se  of  Color  Heredity  in  the  Andalusian 
Fowl,  in  which  O.ne  Color  Does  Not  Completely  Dominate  Another.  P, 
parental  generation.  The  offspring  of  this  cross  constitute  F^,  the  first  filial 
or  hybrid  generation.  Fr,,  the  second  filial  generation.  Bottom  row,  third 
filial  generation.   (Kellicott.) 

white  varieties  of  guinea-pigs  are  crossed  the  offspring  are  all  black,  like 
one  parent ;  that  is,  when  black  and  white  characters  are  brought  together 
in  the  guinea-pig,  these  do  not  appear  to  blend  into  gray  or  "blue,"  as 
in  the  case  of  the  Andalusian  fowl,  but  one  character  alone  appears. 


CD 


r, 


CO  CDCO 


Fig.  66. — Diagram  Showing  the  Course  of  Color  Heredity  in  the  GtriNEA-PiG, 
IN  Which  One  Color  (Black)  Completely  Dominates  Another  (White). 
Reference  letters  as  in  Fig.  65.    (Kellicott.) 

The  black  seems  to  cover  up  or  wipe  out  the  white.  The  black  color  is, 
therefore,  said  to  be  dominant  and  the  white  recessive.  The  white  charac- 
ter, however,  has  not  disappeared,  for  when  the  black  offspring  are 
crossed  together  the  progeny  falls  into  two  groups :  some  black  and  some 


PRINCIPLES  OF  HEREDITY  627 

white.  Throe-fourths  of  the  progeny  are  black;  that  is,  they  resemble 
the  hybrid  form  and  at  tlie  same  time  one  of  the  grandparents,  while 
the  remaining  fourth  resemble  the  other  white  grandparent.  Some  of 
these  blacks  will  breed  true  and  are,  therefore,  known  as  homozygotes. 
Some  of  tiio  blacks  contain  a  mixture  of  the  black  and  white  characters 
and  are,  therefore,  known  as  heterozygotes.  The  hereditary  transmission 
of  the  color  character  in  these  two  illustrations  through  the  germ  cell  is 
shown  in  the  accompanying  diagram. 

Unit  characters  may  either  be  positive  or  negative;  that  is,  they  may 
be  due  to  the  presence  or  absence  of  "something"  in  the  germ  cell  or 
sperm  coll.  This  something,  known  as  a  determiner,  is  a  force,  a 
molecular  structure  or  an  enzyme  (?)  in  the  nuclear  matter  of  the  germ 
plasm.  Thus,  the  determiner  in  the  case  of  pigment  is  not  the  pig- 
ment itself,  but  something  that  activates  pigment  production.  These 
determiners  are  transmitted  in  the  germ  plasm  and  are  the  only  things 
that  are  truly  transmitted.  The  determiner  may  be  either  in  the  ovum 
or  the  sperm. 

An  hereditable  character  may  be  due  to  the  presence  or  absence  of 
a  determiner  in  the  germ  plasm  of  both  parents.  When  a  character  is 
due  to  the  presence  of  a  determiner  it  is  called  positive,  when  due  to 
the  absence  of  a  determiner,  negative.  Thus,  a  brown  eye  depends  on 
a  determiner  that  produces  the  brown-colored  pigment,  while  the  blue 
eye  depends  upon  the  absence  of  such  a  determiner.  It  is  not  always 
easy  to  anticipate  whether  a  given  character  is  positive  or  negative. 
For  instance,  long  hair  in  Angora  cats,  sheep,  or  guinea-pigs  is  ap- 
parently not  due  to  a  factor  added  to  short  hair,  but  rather  to  an 
absence  of  a  determiner  that  stops  growth  in  short-haired  animals. 

One  of  the  most  important  conclusions  from  Mendel's  observations 
is  that  the  different  inherited  traits  act  independently;  that  is,  they 
do  not  blend.  In  other  words,  the  definitely  hereditable  characters 
act  as  independent  units  that  are  without  any  apparent  relation  to  other 
peculiarities  of  the  individual  concern.  Furthermore,  these  units  do 
not  interfere  with  each  other.  It  follows  that  all  the  unit  characters 
of  an  individual  are  to  be  regarded  as  mutually  independent  assemblages. 
This  is  the  doctrine  of  unit  characters.  According  to  this  doctrine,  each 
individual  is  of  dual  origin,  paternal  and  maternal,  and  each  individual 
is  made  up  of  a  mosaic  of  inherited  characters,  some  of  which  may  be 
dominant,  others  recessive.  The  idea  of  unit  characters  capable  of 
being  inherited  independently  of  one  another  is  one  of  the  most  important 
conceptions  which  has  been  added  to  our  knowledge  of  heredity.  We 
now  know  from  the  phenomenon  of  segregation  what  constitutes  purity 
in  a  strain  of  animals  or  plants;  that  is,  purity  does  not  depend  upon 
the  length  of  time  during  which  a  race  has  exhibited  a  constant  character, 
for  a  strain  of  absolute  purity  may  arise  from  the  second  generation  of 


628  HEREDITY  AND  EUGENICS 

a  cross.  Mendel's  •  law  has  not  only  explained  many  facts  in  heredity, 
but  also  has  important  practical  bearing  in  the  improvement  of  the  breeds 
of  cultivated  plants  and  domestic  animals. 

Atavism  and  Reversion. — Atavism  (from  ataviis,  a  grandfather)  is 
the  inheritance  of  properties  not  manifest  in  either  parent,  but  pres- 
ent in  the  grandfather  or  some  relatively  remote  ancestor.  Mendel's 
observations  upon  recessive  characters  now  make  plain  some  of  the  phe- 
nomena known  as  atavism.  According  to  Castle,  atavism  or  reversion 
to  an  ancestral  condition  can  be  completely  explained  by  the  Mendelian 
principles.  It  is  nothing  more  or  less  than  the  reassertion  of  recessive 
unit  characters  that  have  long  been  overshadowed  by  dominant  characters. 
It  seems  that  recessive  characters  may  not  be  lost,  no  matter  how 
long  they  remain  latent  or  dormant. 

The  term  "atavism"  is  sometimes  employed  to  mean  any  reversion- 
ary condition,  whether  favorable  or  unfavorable,  while  the  term  "re- 
version" means  a  return  in  the  offspring  to  a  lower  type,  usually  -of 
some  remote  ancestor.  The  degenerations  which  run  in  families  may 
be  instances  either  of  atavism  or  reversion,  or  mutation. 

Darwin's  classical  experiment  illustrating  reversion  consisted  in  cross- 
ing a  barbed  fan-tail  female  pigeon  with  a  barbed  spot  male  and  produc- 
ing offspring  hardly  distinguishable  from  the  wild  Shetland  species  of 
blue-rock  pigeon  (Colomha  livia).  This  is  a  case  of  reversion,  in  which 
an  artificially  bred  and  highly  specialized  race  quickly  recovered  charac- 
ters which  had  been  lost  during  many  generations.  A  foal  is  sometimes 
born  with  a  few  stripes  on  its  forelegs,  as  if  reminding  us  of  striped 
wild  horses.  Highly  cultivated  and  specialized  flowers  and  vegetables 
have  a  tendency  to  revert,  and  sometimes  produce  forms  hardly  distin- 
guishable from  their  wild  progenitors. 

Reversion  is  due  to  the  reassertion  of  latent  ancestral  characters.  It 
is  an  impelling  hereditary  force  which  must  be  taken  into  account.  True 
reversion  may  arise  in  pure  bred  races,  but  is  much  more  frequent  as  the 
result  of  hybridization. 

The  facts  of  reversion  and  atavism  are  of  peculiar  interest  to  man, 
for  the  reason  that  the  human  species  has,  through  unconscious  selec- 
tion and  conscious  effort,  improved  the  race  to  its  present  point  of 
superiority.  Whether  civilized  man  to-day  is  superior  to  ancient  races 
may  be  doubted,  but  the  fact  is  plain  that  civilization  is  breeding  an 
artificial  and  highly  specialized  strain  that  shows  artificial  departures 
from  primitive  stock. 

It  is  well  known  that  the  high  bred  and  "fancy"  races  of  the  do- 
mesticated animals  show  a  marked  tendency  to  reversion  or  deteriora- 
tion of  type.  Likewise,  the  human  race  shows  the  same  tendency  to 
revert  to  types  resembling  its  forebears.  The  present  level  attained  by 
the  more  highly  civilized  races  can  only  be  maintained  by  a  continual- 


THE  CELL  IN  HEREDITY  629 

tion  of  that  struggle  for  iniproveineiit,  progress^  and  desire  for  per- 
fection whicli  is  an  inborn  charaeteristic  and  an  essential  element  of 
progress.  Owing  to  the  artificial  position  to  which  the  human  race 
has.  brought  itself,  it  becomes  necessary  to  continue  the  struggle — to 
stand  still  means  rapid  deterioration.  Some  of  the  stigmata  of  degen- 
eration and  hereditary  defects  may  he  accounted  for  by  this  natural 
tendency  on  the  part  of  an  artificially  nnrtuicd  standard  to  slip  back- 
ward. 

Galton's  Law  of  Filial  Regression. — Filial  regression  has  nothing  to 
do  with  reversion.  The  law  of  filial  regression  concretely  stated  is  that 
offspring  are  not  likely  to  differ  from  mediocrity  in  a  given  direction 
so  widely  as  their  parents  do  in  the  same  direction.  There  is  a  contin- 
ual tendency  to  sustain  a  specific  average  or  a  stock  average. 

Let  us  take  a  simple  instance  from  Professor  Karl  Pearson's  "Gram- 
mar of  Science."  Suppose  a  group  of  fathers  with  a  stature  of  72  in. ; 
the  mean  height  of  their  sons  is  70.8  in. — a  regression  toward  the  mean 
height  of  the  general  population.  On  the  other  hand,  fathers  with  a 
mean  height  of  66  in.  give  a  group  of  sons  a  mean  height  68.3  in! — 
again  nearer  the  mean  height  of  the  general  population.  The  "regres- 
sion" works  both  ways^there  is  a  leveling  up  as  well  as  a  leveling  down. 
"The  father  with  a  great  excess  of  the  character  contributes  sons  with 
an  excess,  but  a  less  excess  of  it;  the  father  with  a  great  defect  of  the 
character  contributes  sons  w4th  a  defect,  but  less  of  it"   (Thompson). 


THE  CELL  IN  HEREDITY 

Each  parent  (male  and  female)  is  composed  biologically  of  somatic 
or  body  cells,  which  are  mortal,  and  germ  plasm  which  is  distinct,  con- 
tinuous, immortal.  The  development  and  embryolog}^  of  the  germ  and 
sperm  cells  are  of  particular  interest  to  the  student  of  heredity. 

The  view  has  gained  ground  and  general  acceptance  that  the  nucleus 
is  the  chief  or  exclusive  bearer  of  the  hereditable  characters;  that  is, 
the  female  nuclear  material  transmits  the  characters  of  the  mother  and 
her  forebears  and  the  male  nucleus  those  of  the  father  and  his  forebears 
to  the  offspring. 

Cells  divide  and  multiply  in  two  ways:  (1)  by  direct  division  or 
amitosi&,  and  (2)  by  indirect  division  or  mitosis.  Direct  division  occurs 
more  frequently  than  is  usually  suspected.  The  process  appears  to 
be  a  very  simple  one;  the  nucleus  divides  without  any  preliminary 
arrangement  of  its  structure,  the  cytoplasm  is  constricted,  and  presently 
we  have  two  cells  in  place  of  one.  Indirect  division  or  mitosis  appears 
to  be  the  natural  mode  of  cell  development.  The  chromatin,  which  is 
the  deeply  staining  matter  in  the  nucleus^  rearranges,  itself  from  its 


630  HEREDITY  AND  EUGENICS 

"resting"  stage.  After  a  complicated  process  the  nuclear  matter  forms 
itself  into  a  long  cylindrical  thread  known  as  the  linene  thread.  This 
then  divides  into  links  or  chromosomes.^^  The  chromosomes  are  of  spe- 
cial interest,  for  they  are  believed  to  carry  the  "determiners." 

In  mitotic  division  each  chromosome  is  divided  in  half  longitu- 
dinally, as  a  stick  might  be  split  up  the  middle,  and  after  a  very  com- 
plex process  the  halves  of  each  split  chromosome  migrate  to  opposite 
poles.  Then  each  centrosome  attracts  a  group  of  chromosomes  con- 
sisting of  just  one-half  of  the  original  chromatin  material.  Each  group 
then,  in  orderly  fashion,  rounds  itself  into  a  new  nucleus,  and  the  body 
of  tlie  cell  (the  cytoplasm)  constricts  across  the  equatorial  plane,  and 
two  cells  are  formed. 

Every  species  of  plant  or  animal  has  a  fixed  and  characteristic 
number  of  chromosomes  which  regularly  recurs  in  the  division  of  all 
of  its  cells  and  in  all  forms  arising  by  sexual  reproduction  the  number 
is  even.  Thus,  in  some  of  the  sharks  the  number  of  chromosomes '  is 
36,  in  certain  gastrapodes  it  is  32;  in  the  mouse  and  salamander,  the 
trout,  the  lily,  24;  in  the  worm  Saggita,  18;  in  the  ox  and  guinea-pig, 
16;  in  man  the  number  was  formerly  stated  as  16,  now  24.  In  crus- 
taceans the  number  of  chromosomes  may  be  as  high  as.  168.  In  a  few 
insects  the  females  have  in  their  body  cells  one  chromosome  in  addition 
to  the  number  possessed  by  the  males.  This  has  been  interpreted  as 
bearing  upon  the  determination  of  sex. 

Van  Beneden  in  1885  discovered  the  important  fact  that  the  nucleus 
of  the  ovum  and  the  nucleus  of  the  spermatozoon  which  unite  in  fertiliza- 
tion contain  each  one-half  of  the  number  of  chromosomes  characteristic 
of  the  body  cells. 

As  both  the  germ  and  sperm  cells  contain  only  half  the  number  of 
chromosomes,  a  reduction  must  take  place  in  the  history  of  these  cells; 
in  fact,  alike  in  the  history  of  the  germ  cell  and  in  the  history  of  the 
sperm  cell,  there  is  a  parallel  reduction  in  the  number  of  chromosomes 
to  one-half.  This  reduction  appears  to  be  a  preparation  of  the  repro- 
duction cells  for  their  subsequent  union,  and  a  means  by  which  the  num- 
ber of  chromosomes  is  held  constant  in  the  species. 

In  sexual  reproduction  each  centrosome  attracts  a  group  of  chromo- 
somes, half  of  which  are  of  paternal  origin  and  half  of  maternal  origin. 
This  is  interpreted  as  meaning  that  the  paternal  and  maternal  chromo- 
somes that  unite  to  form  the  new  zygote  probably  carry  the  hereditable. 
characters. 

The  gist  and  meaning  of  the  whole  process  to  the  student  of  heredity 
is   the   precisely    equal   partition    of   the    maternal    and    paternal    con- 

^^  For  a  full  understanding  of  cell  division  the  student  is  referred  to  one  of 
the  standard  text-books  upon  Cytology,  or  Minot's  "Embryology";  also,  to  E.  B. 
Wilson's  "The  Cell  in  Development  and  Inheritance,"  2d  Ed.,  1900. 


STATISTICAL  METHODS  631 

tributionS;,  so  that  eat-li  of  tlie  zy<^ote  cells  that  is  to  form  a  new  individ- 
ual has  a  nucleus  halt'  from  the  mother  and  half  from  the  father. 

Although  the  u\  iini  is  much  larger  than  the  spermatozoon,  each  con- 
tributes equally  so  far  as  the  amount  of  nuclear  matter  is  concerned  ; 
the  new  individual  is  dual  in  its  origin,  and  the  offspring  is  a  double 
creature  and  retains  its  duality  to  its  dying  day,  and  transmits  it  to 
succeeding  generations. 

Professor  E.  B.  Wilson  states  the  generally  accepted  opinion  some- 
what as  follows :  As  the  ovum  is  much  larger  it  is  believed  to  furnish 
the  initial  capital — including,  it  may  be,  a  legacy  of  food  yolk — for  the 
early  development  of  the  embryo.  From  both  parents  alike  comes  the 
inherited  organization  which  has  its  seat  (according  to  most  biologists) 
in  the  readily  stainable  chromatin  rods  of  the  nuclei.  From  the  father 
comes  a  little  body,  the  centrosome,  which  organizes  the  machinery  of 
division  by  which  the  egg  splits  up  and  distributes  the  dual  inheritance 
equally  between  the  daughter  cells. 

The  ovum  may  be  stimulated  to  segmentation  without  the  sperm  cell 
(parthenogenesis).  When  this  happens  individuals  are  produced  similar 
to,  but  not  as  vigorous  as,  the  normal  types.  The  sperm  cell  similarly  is 
able  to  develop  without  the  nuclear  matter  of  the  egg.  In  other  words, 
the  ovum  and  the  sperm  each  contain  potential  factors  for  the  new 
individual.  As  we  have  already  seen,  in  accordance  with  Weismann's 
theory,  that  the  germ  plasm  is  independent  of  the  body  and  is  continu- 
ous; therefore,  acquired  characters  not  affecting  the  germ  plasm  are  not 
inherited  in  accordance  with  this  conception. 

Foreign  bodies  carried  along  by  either  the  germ  or  sperm  cells  are 
examples  of  congenital  transmission  and  not  instances  of  true  heredity; 
therefore,  in  the  present-day  conception  of  heredity  it  is  not  possible  for 
a  microbic  disease  to  be  transmitted  hereditarily,  even  though  the  micro- 
organism is  contained  in  either  the  germ  or  the  sperm.  Thus,  hens  may 
be  caused  to  lay  colored  -^ggs  by  feeding  the  hens  with  aniline  dyes. 
Anaphylaxis  is  an  example  of  a  transmitted  property,  but  the  "sub- 
stance," whatever  it  is,  seems  ta  be  carried  along  with  the  maternal  germ 
cell  as  a  foreign  body.  In  the  case  of  syphilis,  the  Treponema  pallidum 
may  be  carried  along  by  the  germ  or  sperm,  and  the  disease  is  said  to  be 
transmitted  hereditarily,  but,  strictly,  the  microorganism  is  carried  as 
a  foreign  body  and  not  as  a  unit  character  or  constituent  part  of  the 
nuclear  matter. 

STATISTICAL  METHODS 

[Vital  Statistics,  Section  IX} 

Statistical  methods  applied  to  biology  have  been  termed  biometry 
by  Professor  Karl  Pearson.     Francis   Galton's  book  on  "Natural  In- 


632 


HEREDITY  AND  EUGENICS 


heritance"  is  a  pioneer  in  the  subject,  and  embodies  a  lucid  introduction 
to  the  statistical  study  of  variation  and  inheritance.  The  health  offi- 
cer must  be  familiar  with  statistical  methods  not  only  in  their  applica- 
tion to  biolog}',  but  as  they  relate  to  vital  statistics.  The  health  officer 
who  lacks  the  quantitative  view  or  who  fails  to  grasp  the  statistical 
values  of  the  facts  and  factors  in  preventive  medicine  works  under  a 
decided  handicap.  The  sanitarian  who  is  ignorant  of  statistical  methods 
must  necessarily  grope  in  the  dark.     Efficiency  and  economy  in  public 


Fig.  67. — Model  to  Illustrate  the  Law  of  Probability  or  "Chaxce."  A,  Peas 
held  in  container  at  top  of  board.  B,  Peas  after  having  fallen  through  the 
obstructions  into  the  vertical  compartments  below.  The  curve  connecting 
the  tops  of  the  columns  of  peas  is  the  normal  probability  curve. 

health  work  depend  not  alone  upon  a  knowledge  of  the  biological  sciences, 
but  also  upon  a  correct  sense  of  proportion.  The  statistical  method  is  a 
strong  lever  which  makes  for  sane  administration,  economy  in  expendi- 
ture, efficiency  of  effort;  in  short,  successful  results. 

Statistics  deal  with  groups  rather  than  with  individuals.  It  must 
be  understood  that  the  average  of  a  group  may  represent  something 
quite  different  from  any  individual  which  the  group  contains.  Also  a 
group  may  contain  individuals  of  very  diverse  natures.  In  collecting 
statistical  material  the  data  must  be  gathered  without  any  preconceived 
ideas  and  without  neglecting  any  members.  In  this  respect  statistical 
methods  differ  from  biological  methods,  which  require  careful  discrimi- 
nation of  data. 


STATISTICAL  METHODS 


633 


The  quantitative  determination  of  a  character  may  i)e  made  hy  various 
methods,  as  hy  counting  or  hy  measurement. 

The  statistical  mctliod  may  he  illustrated  hy  a  simple  model,  such 
as  that  suggested  hy  CJalton.  This  is  a  modification  of  the  I'amiliar 
bagatelle  board  covered  with  glass  .and  arranged  as  shown  in  Fig.  67. 
A  funnel-shajied  container  at  the  top  of  the  hoard  is  filled  with  peas 
or  similar  objects.  Below  this  is  a  regular  series  of  obstacles  symmetri- 
cally arranged,  and  at  the  bottom  of  the  board  is  a  row  of  vertical  com- 
partments also  arranged  symmetrically  with  reference  to  the  chief  axis 
of  the  whole  system.  If  we  allow  the  peas  to  run  through  the  funnel 
and  fall  among  the  obstacles  into  the  compartments  below,  we  find  that 
their   distribution   will  follow   certain   laws   capable   of   precise   mathe- 


Q  M  Q 

Fig.  68. — Normal  Curve.     (Lock.) 


matical  description.  The  distribution  of  the  peas  may  be  predicted 
with  fair  accuracy.  The  middle  compartment  will  receive  the  most; 
the  compartments  next  the  middle  somewhat  fewer;  those  further  from 
the  middle  still  fewer ;  and  the  end  compartment  fewest.  If  we  connect 
the  top  of  each  column  of  peas  by  a  curved  line  we  get  a  curve  knoT\Ti 
as  the  "normal  frequency  curve."  A  curve  of  the  same  essential  char- 
acter would  result  from  plotting  the  dimensions  of  a  thousand  cobble- 
stones, the  deviation  from  the  bull's  eye  in  a  target  shooting  contest, 
or  by  plotting  the  variability  of  a  biologic  character,  such  as  the  s'tature 
or  strength  of  men,  the  spread  of  sparrows'  wings,  the  number  of  rays 
on  scallop  shells,  or  of  ray  flowers  of  daisies. 

While  from  the  above  law  of  probability  we  know  quite  definitely 
what  the  general  distribution  of  the  peas  mil  be,  we  do  not  know  at 
all  the  future  position  of  any  single  pea.  Of  this  we  can  speak  only  in 
terms  of  probability.  The  chances  are  very  high  that  it  will  fall  in 
one  of  the  three  middle  compartments,  very  low  that  it  will  be  in  one  of 


634  HEEEDITY  AXD  EUGENICS 

the  extreme  compartments.  The  chances  are  equal  that  any  individual 
pea  will  fall  above  or  below  the  average  or  middle  position.  We  there- 
fore see  that  in  any  group  there  are  many  more  individuals  near  the 
average  than  there  are  in  the  classes  removed  from  the  average,  and 
the  farther  the  removal  of  a  class  from  the  average  the  smaller  the 
number  of  individuals  in  that  class;  hence,  we  have  the  important  fact 
in  statistical  methods  that  an  individual  may  belong  to  a  group  with- 
out representing  it  fairly.  In  order  to  get  a  correct  idea  of  the  whole 
group  we  must  know  first  to  what  extent  deviation  in  each  direction 
occurs  above  and  below  the  group  average;  and,  second,  the  average 
amount  by  which  each  indi\idual  of  the  group  deviates  from  this  group 
average;  that  is,  we  must  know  the  amount  of  variability  as  well  as 
the  extent  of  the  greatest  divergence  from  the  average.  Hence,  we  have 
the  folloA^ang  definitions  and  corollaries : 

Definitions. — A  varmte,  or  variable,  is  one  of  the  separate  numerical 
values  from  which  a  curve  of  variability  can  be  constructed.  It  may 
be  defined  as  a  single  magnitude-determination  of  character.  Charac- 
ter may  be  defined  as  any  quality  common  to  a  number  of  individuals. 
The  accurac}'  of  the  statistical  method  is  usually  proportionate  to  the 
number  of  variates  out  of  which  the  curve  is  built.  The  biometrician 
usually  deals  with  some  such  number  as  100  or  more  variates.  The 
total  number  of  variates  is  represented  by  the  area  inclosed  by  the 
curve,  and  it  will  be  seen  that  half  the  total  number  of  variates  falls 
between  the  two  quartiles  and  half  outside  them. 

Variates  may  be  lines,  terms,  units,  events,  items,  etc.  If  of  the  same 
magnitude,  they  are  said  to  be  uniform.  If  the  series  is  made  up  of  dif- 
ferent magnitudes,  these  differ  from  each  other  (and  from  uniformity) 
by  deviations. 

A  class  may  be  defined  as  a  group  of  variates,  all  of  which  show  a 
particular  value  or  a  value  falling  between  certain  limits.  The  term  is 
also  used  to  express  quantities  that  cannot  be  measured  or  expressed  by 
figures ;  as  sex,  nationality,  etc. 

The  frequency  of  a  class  is  the  number  of  variates  which  it  contains. 

Groups  are  measurable  and  can  be  expressed  by  figures;  as  age, 
height,  weight,  etc. 

The  mean  is  the  average  of  all  the  values  from  which  the  curve  is 
constructed.  In  any  actual  case  obtained  by  practical  methods,  the  posi- 
tion of  the  mode,  the  median,  and  the  mean  will  only  be  approximately 
the  same  because  such  a  curve  is  never  perfectly  symmetrical. 

The  amount  of  variation  shown  by  a  particular  group  of  variates  is 
measured  by  the  degree  of  slope  of  the  curve.  A  steep  curve  indicates 
greater  variability  and  a  flat  curve  denotes  less  variability.  In  other 
words,  the  deviations  are  greater  when  the  curve  is  steeper,  and  vice 
versa. 


STATISTICAL  MF/riiODS  635 

The  rejection  ol'  v.vlnnne  variate.s  in  liratinir  statistical  series  is 
allowable  only  under  exceptional  circumstances.  In  many  physical 
measurements,  for  instance,  C'hauvenet's  or  some  other  mathematical 
criterion  shoukl  be  used  to  test  the  suspicion  that  single  extreme  variates 
should  be  rejected.  Even  then,  while  the  observations  might  be  excluded 
in  calculating,  they  should,  however,  be  published. 

In  any  series  of  variates,  the  quartile  is  the  middle  term  of  each 
half  of  a  series.  In  the  curve  representing  the  series,  quartiles  are  lines 
dividing  each  half  of  the  curve  area  into  two  equal  parts.  They  are 
shown  at  Q  and  Q'  (Fig.  68).^^  A  large  series  of  variates  can  have, 
similarly,  deeentiles,  percentiles,  etc.,  which  are  useful  to  show  the  dis- 
tribution of  groups. 

The  median  is  a  pcri)endicular  line  which  divides  the  area  of  the 
curve  into  two  equal  halves.  It  is  also  the  middle  variate.  This  implies, 
of  course,  that  the  variates  must  be  arranged  in  the  order  of  their  ascend- 
ing or  descending  magnitude,  which  is  not  necessary  in  the  mean  or 
average  determination.  If  the  series  is  made  up  of  an  even  number  of 
variates,  the  median  lies  half-way  between  the  two  middle  ones  (A,  Fig. 
69).  It  is,  then,  the  magnitude  above  which,  and  below  which,  50  per 
cent,  of  the  variates  occur.  The  median  is  like  the  mean  only  when 
the  series  of  variates,  or  the  curve  rej^resenting  that  series,  is  symmetrical. 
If  the  curve  has  a  decided  tendency  to  skewness  or  asymmetry,  the 
median  may  have  little  value.  It  may  be  determined  by  simple  graphic 
methods  outlined  above,  without  the  use  of  mathematics. 

The  mode  may  be  defined  as  the  class  with  the  greatest  frequency.  It 
is  necessary  to  distinguish  between  the  empirical  and  the  theoretical  mode. 

The  empirical  mode  is  found  by  inspection  of  the  seriated  data  and  is 
found  to  be  the  most  frequent  variate,  the  most  probahle  length,  the 
number  appearing  the  greatest  number  of  times,  etc.  It  is  then  possible 
for  the  mode  to  be  at  the  end  of  a  series;  moreover,  the  modal  value 
is  unaffected  by  any  values  at  the  extreme  ends  of  the  series. 

By  theoretical  mode  we  mean  the  mode  of  the  theoretical  curve 
most  closely  agreeing  with  the  observed  data.  In  a  normal  curve,  it  is 
the  longest  perpendicular  which  can  be  drawn  from  the  base  line  to 
meet  the  curve  itself  (M,  Fig.  68).  The  normal  curve  is  symmetrical 
on  either  side  of •  the  mode;  that  is  to  say,  two  j)erpendiculars  drawn 
from  the  base  to  the  curve  on  either  side  of  the  mode  and  at  the  same 
distance  from  it  will  be  equal  in  length. 

The  mean,  median,  and  mode  of  a  symmetrical  or  normal  curve 
therefore  coincide.  In  an  asymmetrical  curve,  the  mode  may  have 
greater  significance  than  the  mean  or  average.  In  this  case,  the  mode  lies 
on  the  opposite  side  of  the  median  from  the  mean;  and  the  abscissal 
distance  from  the  median  to  the  mode  is  double  the  distance  from  the 

"  And  p.t  B  and  C,  Fig.  69. 


636 


HEREDITY  AND  EUGENICS 


median  to  the  mean;  or  mode  =  mean  —  3  (mean  —  median).  That  is, 
it  is  significant  when  the  abscissa!  distance  from  the  median  to  the  mode 
is  double  the  distance  from  the  median  to  the  mean. 

The  standard  deviation  of  a  normal  curve  is  the  measure  of  varia- 
bility and  is  expressed  shortly  as  o.  The  value  of  a  is  found  by 
multiplying  the  square  of  the  deviation  of  each  class  from  the  mean 
(or  mode)  by  the  frequency  of  the  class,  adding  together  the  series  of 
products  so   obtained,   dividing  this  number  of  the  total  number  of 

80i 


70- 
60  < 
50 
40 
30 

zo 

10 


B  E 


Fig.  69. — Curve  Made  up  of  Variates.  Example  on  page  637.  A  =  position  of 
the  median ;  B,  that  of  the  lower  quartile,  and  C,  of  the  upper  quartile.  .  D 
represents  the  mode,  while  E  shows  the  position  of  the  mean. 

variates,  extracting  the  square  root  of  the  result,  and  multiplying  by 
the  number  of  units  in  the  class  arranged. 

In  the  curve,  the  standard  deviation  may  be  roughly  determined  by 
adding  the  distance  of  the  two  quartiles  from  the  median.  It  serves  to 
indicate  whether  or  not  the  departures  from  the  mean  are  small  or 
great.  The  closer  the  variates  group  themselves  around  the  mean,  the 
smaller  the  standard  deviation. 

The  coefficient  of  variability  is  a  purely  abstract  number  obtained 
by  dividing  the  standard  deviation  by  the  magnitude  of  the  mean  in 
any  particular  case  and  multiplying  the  result  by  100.  It  is  the  ratio 
of  the  standard  deviation  to  the  mean.  It  is  an  excellent  measure  of 
variability,  and  is  used  to  compare  this  quality  among  different  charac- 
ters, or  in  the  same  character  among  different  groups,  particularly  if 
the  means  differ  widely. 


STATISTICAL  METHODS 


637 


In  a  normal  distribntion,  the  probable  error  of  a  single  variate  in 
the  series  of  observations,  is  defined  as  that  departure  from  either  side 
of  the  mean  within  which  one-half  of  the  variates  are  found.  The  prob- 
able error  is  dealt  with  mostly  in  correlation.  Wb.en  the  difference  be- 
tween two  means  is  greater  than  three  times  the  probable  error,  the 
difference  is  significant.  The  proJ)able  error  of  the  standard  deviation, 
of  the  mean,  median,  etc.,  are  all  occasionally  useful. 

In  the  following  e.xample,  the  figures  represent  a  hypothetical  series. 

EXAMPLE 


GROUP  OF 
VAKIATES 

niFFERKNCE   BE- 
TWEEN   MEAN    AND 
VARIATES 

SQI'ARE   OF 
DIFFERENCE 

24 

—32.95 

10S5.7025 

37 

—19.95 

39S.0025 

45 

—11.95 

142.8025 

49 

—  7.95 

63.2025 

53 
B 

—  3.95 

15.6025 

A  —  Median  =  60 

55 
57 

—  1.95 

-f     .05 

3.8025 
.0025 

B  —  Lower  quartile  =  54 

58 
59 

-f   1.05 
2.05 

1.1025 
4.2025 

C  —  Upper  quartile  =^ 
61.5 

60 

3.05 

9.3025 

A 
60 

3.05 

9.3025 

J/of7e  =  61 

61 
61 

4.05 
4.05 

16.4025 
16.4025 

Mean  =  56.95 

61 

4.05 

16.4025 

a  =  ±  11.17 

61 

4.05 

16.4025 

C 
62 
63 

5.05 
6.05 

25.5025 
36.6025 

Coefficient  of  variability 
=  19.44 

67 
71 
75 

10.05 
14.05 

18.05 

101.0025 
197.4025 
325.8025 

Probable  error  of  single 
determination  =  ±  .45 

20)1139. 

157.40 

20)2494.9500 

56.95 

124.7475 

The  group  contains  20  vwrvates.  The  mean  is  the  average  of  the 
variates,  or  56.95.  The  median  in  this  series  lies  between  the  two  middle 
variates  and  is  therefore  60.  There  are  two  quartiles,  the  lower  being  54 
and  the  upper  61.5.  The  difference  in  magnitude  between  the  quartiles 
and  the  median  indicate  that  the  variates  are  not  grouped  closely  about 
the  median.  This  is  also  evident  on  inspection.  This  hypothetical  series 
w^as  chosen  to  illustrate  functions  and  terms.  Under  actual  experi- 
mental conditions,  the  data  collected  would  not  make  ordinarily  such  a 
uniform  series  of  figures. 

The  mean  and  the  median  do  not  coincide;  that  is,  the  curve  has 
skewness,  or  is  asymmetrical.  The  mode  or  most  frequently  appearing 
figure  is  61.    It  is  of  greater  significance  than  the  mean,  since  it  repre- 


638  HEKEDITY   AND  EUGEA'iCS 

sents  the  most  probable  event  because  of  the  number  of  times  it  was 
found. 

The  difference  betAveen  the  mode  (61)  and  the  median  (60)  is  1. 
This  is  less  than  twice  the  difference  between  the  median  (60)  and  the 
mean  (56.95),  which  is  3.05.  If  it  were  more  than  twice  3.05,  it  would 
indicate  that  the  variates  were  not  evenly  grouped  about  the  modal 
point,  a  fact  which  in  such  a  small  series  of  figures  would  be  also  evident 
upon  inspection. 

The  standard  deviation  is  found  by  obtaining  the  square  root  of  the 
quotient  obtained  by  dividing  the  sum  of  the  squares  of  the  variate  devia- 
tions from  the  mean  by  the  number  of  variates.  In  the  example  given, 
2494.25  -^  20  =  124.74,  the  square  root  of  which,  or   a,  is  ±  11.17. 

11  17 

The  coefjicient  of  variability  is  100  X  — '—;  =  19.44.      The  probable 

56.93 

error  of  a  single  variate  is  found  by  taking  the  square  root  of  thfe  figure 
obtained  by  dividing  the  sum  of  the  squares  of  the  deviations  by  the 
number  of  variates  minus  one,  and  multiplying  the  result  by  a  constant 

+  r7a^  i  /249ME 

For  a  further  consideration  of  the  mathematics  involved,  etc.,  the 
appended  bibliography  may  be  consulted. 

REFERENCES 

Bailey  and  Cummings:     "Statistics."     1917,  McClurg,  Chicago. 
Bowley:     "Elements  of  Statistics."     1907,   Chas.   Scribnei-'s  Sons. 
Davenport,  Chas.  B.  :     "Statistical  Methods,  with  Special  Eeference  to 

Biological  Variation,"  2nd  Edition.    jSTew  York,  1904,  John  Wiley  and 

Sons. 
Eldertok:     "Primer  of  Statistics."     New  York,  1912,  Macmillan  &  Co. 
Goodwin,  H.  "W.  :     "Precision  of  Measurements."     1909,   Mass.   Inst,   of 

Technology  Press. 
King  :     "Elements  of  Statistical  Methods."     1912,  Macmillan  &  Co. 
Newsholme  :■    "Elements  of  Vital  Statistics."     1899,  Macmillan  &  Co. 
Whipple:     "Vital  Statistics."     1919,  John  Wiley  &  Sons. 
Yule  :    "Introduction  to  the  Theory  of  Statistics."    1916,  J.  P.  Lippincott, 

Philadelphia. 

HEREDITY  VERSUS  ENVIRONMENT 

How  much  of  our  physical  and  mental  make-up  is  due  to  heredity 
(nature)  and  how  much  to  environment  (nurture)  is  one  of  the  much- 
discussed  problems.  It  seems  evident  to  students  of  biology  that  by 
far  the  overwhelming  factor  in  our  organization  is  set  and  definitely 
fixed  at  our  birth.     Heredity  appears  to  be  the  overshadowing  influence 


niMrXITY  CAIXFJ)  THllorcll    INllimrrAXC'E        G39 

of  first  and  prime  importance.  Herbert  Spencer  well  said  that  ""in- 
herited constitution  must  ever  be  the  chief  factor  in  determining  char- 
acter." Environment  may  influence  the  individual,  but  apparently  has 
.small  and  slow  power  of  propagating  itself  for  good;  great  and  rajiid 
power  for  evil.  That  is,  the  hereditary  transmission  of  acquired  char- 
acters is  denied,  but  the  transmission  of  defects  of  organization,  such 
as  insanity,  deaf  mutism,  the  consequences  of  syphili-s,  alcoholism,  and 
other  vices,  are  fully  recognized.  Atavism,  reversion,  and  mutations 
must  not  be  regarded  as  instances  of  the  hereditary  transmission  of 
acquired  characters  in  the  biological  sense.  The  tendency  of  the  artifi- 
cially bred  strains  of  the  civilized  human  races  to  revert  and  deteriorate 
has  already  been  emphasized. 

Despite  the  teachings  of  biology  we  are  convinced  that  life  is  in- 
exorably conditioned  by  its  environment.  The  environment  of  today 
is  the  heredity  of  tomorrow.  Jordan  states  that  "among  the  factors 
everywhere  and  inevitably  connected  with  the  course  of  descent  of  any 
species  variation,  heredity,  selection,  and  isolation  must  appear ;  the  first 
two  innate,  part  of  the  definition  of  organic  life;  the  last  two  extrinsic, 
arising  from  the  necessities  of  environment,  and  not  one  of  these  can 
find  leverage  without  the  presence  of  the  others."  In  the  present  state 
of  our  knowledge,  while  we  are  convinced  that  heredity  plays  the  major 
role,  we  are  by  no  means  prepared  to  deny  the  influence  of  environment. 


IMMUNITY  GAINED  THROUGH  INHERITANCE 

Immunity  to  disease  is  either  natural  or  acquired.  Natural  immu- 
nity is  inherited  through  successive  generations  of  a  species  or  a  race. 
Acquired  immunity,  like  other  acquired  characters,  is  not  inherited 
as  a  ''unit  character"  in  the  sense  of  Mendel.  Thus,  there  has  been 
little  variation  in  our  natural  power  to  resist  most  infections,  such 
as  tuberculosis,  yellow  fever,  plague,  smallpox,  cholera,  tetanus,  measles, 
scarlet  fever,  diphtheria,  and  so  on  through  a  long  list,  although  these 
diseases  have  doubtless  afflicted  the  human  species  through  untold  ages. 
The  fluctuating  virulence  of  some  infections  is  a  matter  of  common 
knowledge,  and  is  doubtless  due  to  many  variable  factors.  In  a  few  well- 
known  instances  a  certain  amount  of  tolerance  or  resistance  has  been 
gained  and  perhaps  transmitted  through  succeeding  generations  by  a 
process  of  the  survival  of  the  fittest.  Thus,  svi^hilis  is  much  less  virulent 
now  than  it  was  during  the  great  pandemic  of  the  sixteenth  century. 
The  resistance  which  the  natives  enjoy  to  malaria  in  badly  infected 
quarters  of  the  globe  is  largely  acquired  as  a  result  of  early  infections, 
and  this  increased  resistance  is  perhaps  partly  transmitted  by  a  weeding 
out  of  the  very  susceptible.     See  Section  IV,  Chapter  I. 


CHAPTEE  III 
THE  HEKEDITARY  TRANSMISSION  OF  DISEASE 

We  are  now  prepared  to  discuss  more  in  detail  the  hereditary  trans- 
mission of  disease.  The  question  whether  disease  is  ever  transmitted 
hereditarily  or  not  rests  somewhat  upon  our  conception  of  disease;  that 
is,  whether  it  is  an  entity,  a  reaction,  or  a  "unit  character."  The  process 
itself,  of  course,  cannot  be  transmitted,  but  the  potentiality  of  it  may 
be  involved  in  some  peculiarity  in  the  organization  of  the  germ  plasm. 
This  may  be,  and  often  is,  transmitted  through  successive  generations. 
In  the  limited  sense  in  which  the  word  "heredity"  is  used  in  biology 
and  in  the  limited  sense  in  which  the  word  "disease"  is  used  in  pathology, 
there  may  be  no  inherited  diseases,  but  this  appears  to  be  a  quibble  of 
words  or  a  matter  of  definitions.  While  we  are  not  familiar  with  the 
intimate  processes  concerned,  we  are  certain  that  many  abnormal  condi- 
tions of  mind  and  body  are  transmitted.  Some  of  them  follow  the  Men- 
delian  principles. 

Formerly  a  large  number  of  diseases  were  regarded  as  transmissible, 
but  the  list  has  been  revised  and  restricted  as  a  result  of  recent  studies. 
The  reappearance  of  a  diseased  condition  in  successive  generations  does 
not  prove  that  it  has  been  transmitted  or  even  that  it  is  transmissible. 
This  mistake  has  been  made  with  tuberculosis  and  other  infections. 

Lack  of  completeness  vitiates  most  of  the  statistics  bearing  on  heredity 
in  relation  to  human  diseases.  Even  in  the  case  of  clearly  inherited 
diseases  there  are  very  few  pedigrees  sufficiently  complete  for  the  study 
of  the  applicability  of  Mendelian  and  other  laws  of  heredity. 

Sometimes  the  disease  itself  is  not  transmitted,  but  a  tendency  to 
the  disease  is  transmitted.    This  will  be  discussed  again. 

Some  unit  characters  as  well  as  certain  diseases  are  transmitted 
hereditarily,  but  limited  to  one  sex ;  that  is,  the  disease  or  condition 
appears  in  one  sex  only,  although  transmitted  by  the  other.  This  re- 
markable sort  of  inheritance,  known  as  sex-linked  inheritance,  occurs 
when  the  male  parent  is  characterized  by  the  absence  of  some  character 
of  which  the  determiner  is  typically  lodged  in  the  sex  (x)  chromosome. 
A  striking  feature  of  this  sort  of  heredity  is  that  the  trait  appears 
only  in  males  of  the  family,  but  is  not  transmitted  by  them ;  it  is  trans- 
mitted, however,  through  normal  females  of  the  family.  Examples  of 
this  sort  of  heredity  are  hemophilia,  color-blindness,  also  multiple 
sclerosis,  atrophy  of  the  optic  nerve,  myopia,  ichthyosis,  and  muscular 

640 


TIIK  HKREDI  TAKV  TRANSMISSION  OF  DISEASE      641 

atrophy.  The  explanation  is  the  same  in  all  cases  of  sex-linked  heredity. 
The  abnormal  condition  is  due  to  the  absence  of  a  determiner  from  the 
male  sex  chromosome. 

The  diseases,  defects,  and  conditions  believed  to  be  transmitted 
hereditarily  are  discussed  in  the  following  pages.  Some  of  the.se  dis- 
eases, malformations,  and  defects  of  organization  follow  Mendel's  law. 
It  is  probable  that  other  diseases,  tendencies,  and  characters  are  trans- 
missible, but  the  .subject  has  only  recently  been  placed  upon  a  scientific 
basis,  and  it  will  require  careful  and  prolonged  observation  to  estab- 
lish the  facts.  It  is  often  difficult  to  determine  whether  the  disease 
itself  or  a  tendency  to  the  disease  has  been  transmitted  in  any  particular 
case,  and,  further,  it  is  often  difficult  to  decide  whether  an  individual  has 
inherited  or  acquired  his  affliction. 

The  transmissible  defects  which  are  of  principal  concern  to  the  human 
species  are  the  defects  of  organization  of  the  central  nervous  system. 
It  is  important  to  remember  that  the  defects  of  the  nervous  system  do 
not  necessarily  propagate  just  the  same  defects  in  the  succeeding  genera- 
tions. Thus,  an  epileptic  does  not  necessarily  beget  epileptics;  epilepsy, 
insanity,  degeneracy,  feeble-mindedness,  alcoholism,  drug  addiction,  and 
other  stigmata  may  arise  as  the  result  of  deficiencies  of  various  kinds 
of  forebears. 

Defects  such  as  harelip,  cleft  palate,  cervical  fistula,  spina  bifida, 
etc.,  are  not  true  instances  of  hereditary  transmission  of  specific  char- 
acters. They  rather  represent  an  inherited  deficiency  in  developmental 
vigor.  These  defects  for  the  most  part  represent  the  failure  of  parts 
to  unite  during  embryological  development;  in  other  words,  the  failure 
of  embryological  clefts  to  close  normally.  Such  deformities,  as  well  as 
clubfoot,  web  fingers,  and  other  acquired  or  congenital  deformities  or 
disfigurations,  are  not,  as  a  rule,  transmitted. 

Some  practical  problems  of  great  importance  arise  from  our  knowl- 
edge of  the  hereditary  transmission  of  disease  and  defects.  A  man  or 
woman  who  intends  marrying  is  now  more  than  justified  in  carefully 
examining  the  personal  and  medical  histories  of  the  family  of  his  or 
her  intended  mate.  It  is  not  only  possible  to  foretell  the  color  of  the 
eyes,  the  nature  of  the  hair,  and  other  Mendelian  characters  in  the 
future  offspring,  but  it  is  also  possible  to  foretell,  with  mathematical 
precision,  the  chances  of  transmitting  defects,  such  as  insanity,  epilepsy, 
degeneracy,  feeble-mindedness,  deaf-mutism,  color-blindness,  migraine, 
and  other  nervous  disorders,  as  well  as  hemophilia,  polydactylism,  brachy- 
dactylism,  albinism,  and  other  stigmata.  In  any  doubtful  case  it  may 
be  well  to  consult  a  student  of  heredity,  for  it  is  possible  to  foretell 
with  precision  in  certain  cases  which  characters  will  and  which  will  not 
be  transmitted. 


CA2      THE  HEREDITARY  TRANSMISSION  OF  DISEASE 

To  illustrate  the  precision  with  which  the  characters  of  offspring 
may  be  predicted  in  the  best  studied  cases,  we  need  only  refer  to  the 
color  of  the  eyes.  Two  parents  with  pure  blue  eyes  will  have  only  blue- 
eyed  offspring,  for  they  both  lack  the  brown  pigment  which  determines 
the  color  of  the  iris.  Similarly,  if  the  hair  of  parents  be  flaxen,  this  may 
be  taken  as  evidence  of  the  absence  of  a  hair-pigment-determiner  in  the 
germ  plasm,  and  the  offspring  will  have  flaxen  hair.  For  the  same 
reason  parents  with  lack  of  curliness  or  waviness  of  hair  will  have  only 
straight-haired  children.     See  table  on  the  following  page. 

In  determining  whether  transmissible  characters  are  apt  to  reappear 
in  successive  generations  or  not  we  must  know  whether  these  characters 
are  positive  or  negative,  that  is,  whether  they  are  due  to  the  presence 
or  absence  of  determiners.^ 

Inbreeding  may  be  hazardous  for  reasons  that  are  well  understood. 
The  marriage  of  cousins  will  be  evidently  hazardous  if  the  objection- 
able hereditary  characters  are  dominant,  for  in  this  case  the  danger  is 
plain;  if  the  characters  are  recessive  the  danger  is  specially  unfortunate, 
because  of  unexpected  outcroppings  in  the  offspring.  Inbreeding  tends 
,to  secure  homozygous  combinations,  and  this  brings  to  the  surface  latent 
or  hidden  recessive  characters.  Cross  breeding  brings  together  differen- 
tiated gametes  which,  reacting  on  each  other,  produce  offspring  of  greater 
vigor.  On  the  other  hand,  continued  cross  breeding  only  tends  to  hide 
inherent  defects,  not  to  exterminate  them ;  inbreeding  only  tends  to  bring 
them  to  the  surface,  not  to  create  them.  It  is  not,  therefore,  correct  to 
ascribe  to  inbreeding  by  intermarriage  the  creation  of  bad  racial  traits, 
but  only  their  manifestation.  Further,  a  racial  stock  which  maintains 
a  high  standard  of  excellence  under  inbreeding  is  certainly  one  of  great 
vigor  and  free  from  inherent  defects  (Castle). 

The  influence  of  isolation  and  the  results  of  consanguineous  marriage 
are  well  brought  out  when  we  study  certain  localities.  Thus,  consanguin- 
ity on  Martha's  Vineyard  results  in  11  per  cent,  deaf  mutes  and  a  number 
of  hermaphrodites ;  in  Point  Judith,  13  per  cent,  idiocy  and  7  per  cent, 
insanity;  in  an  island  off  the  Maine  coast  the  consequence  is  "intellec- 
tual dullness";  in  Block  Island,  loss  of  fecundity;  in  some  of  the  "Banks" 
off  the  coast  of  North  Carolina  suspiciousness  and  an  inability  to  pass 
beyond  the  third  or  fourth  grade  of  school;  in  a  peninsula  on  the  east 
coast  of  Chesapeake  Bay  the  defect  is  dwarfness  of  stature;  in  George 
Island  and  Abaco  (Bahama  Islands)  it  is  idiocy  and  blindness  (G.  A. 
Penrose,  1905).  There  is  thus  no  one  trait  that  results  from  the  mar- 
riage of  kin ;  the  result  is  determined  by  the  specific  defect  in  the  germ 
plasm  of  the  common  ancestor. 

^We  do  not  yet  know  all  the  unit  characters  in  man,  and  it  is  impossible 
to  foretell  which  of  them  are  due  to  positive  determiners  and  which  to  the 
absence  of  such. 


THE  HEKEDITARY  TRANSMISSION  OF  DISEASE      643 


INHERITED    CHABACTERS    IN    MAK 

From  Cnstlr — Omit  us  and  Eugenics 

1.     Blending' 

General   body  size,   stature,  weight,  sltin-oolor.  hair-form   (in  rross-section,  rorrelated 
with   straightness,   curliness,   etc.)    shape  of   head  and  proportions  of  its  parts  (features). 

2.     Mendelian 


Skin   and   hair 

Dominant 
'  Dark. 

Spotted  with   white. 
Tylosis  and  ichthyosis    (thick- 
ened or  scaly  skin). 

Recessive 

Blonde  or  albino    (probably  mul- 
tiple  allelomorphs). 
Uniformly  colored. 
Normal  skin. 

Epidermolysis     (excessive    for- 
mation of  blisters). 

Hair     beaded      (diameter     not 
uniform). 

Normal   skin. 
Normal  hair. 

Eyes 

■  Front    of   iris   pigmented    (eye 
black,  brown,  etc.). 
Hereditary   cataract, 
■s  Night-blindness     (when  not  sex 
linked). 
Normal. 

Only  back  of  iris  pigmented  (eye 

blue). 
Normal. 

Pigmentary    degeneration    of    re- 
tina. 

Skeleton 

'  Brachydactyly      (short      digits 
and   limbs). 

Polydactyly    (extra    digits). 

Syndactyly    (fused,   webbed,  or 
reduced  number  of  digits). 

Symphalangy    (fused   joints  of 
digits,   stiff  digits). 

Exostoses        (abnormal        out- 
growths of  long  bones). 
I  Hereditary    fragility   of   bones. 

Normal. 

Normal. 
Normal. 

Normal. 
Normal. 

Kidneys 

r  Diabetes    insipidus     (excessive 
J       production   of  urine). 
1  Normal. 

Normal. 

Alkaptonuria     (urine     black    on 
oxidation). 

Nervous    System 

f  Hungington's  chorea. 
\  Normal. 

Normal. 

Hereditary    feeble-mindedness. 

3.     SCendelian  and  Sex-Iiinked 

(Appearing  in  males  when  simplex,  but  in  females  only  when  duplex.) 


Dominant 
Normal. 
Normal. 
Normal. 

Normal. 


Recessive 

Gower's    muscular   atrophy. 

Hemophilia     (bleeding). 

Color-blindness  (inability  to  distin- 
guish   red    from   green). 

Night-blindness  (inability  to  see  in 
faint  light). 


4.     Probably   Mendelian    but   Dominance    Uncertain   or  Imperfect 

Defective  hair  and  teeth  or  teeth  alone,  extra  teeth,  a  double  set  of  permanent  teeth, 
harelip,  cryptorchism  and  hypospadias  (imperfectly  developed  male  organs),  tendency  to 
produce  twins  (in  some  families  determined  by  the  father,  in  others  by  the  mother), 
left-handedness,   otosclerosis    (hardness   of   hearing  owing  to  thickened  tympanum). 


5.     Subject  to  Heredity,  bnt  to  What  Extent  or  How  Inlierited  TTncertain 

General  mental  ability,  memory,  temperament,  musical  ability,  literary  ability,  ar- 
tistic ability,  mathematical  ability,  mechanical  ability,  congenital  deafness,  liability  to 
abdominal  hernia,  cretinism  (due  to  defective  or  diseased  thyroids),  defective  heart,  some 
forms   of  epilepsy   and   insanity,   longevity. 


644      THE  HEREDITARY  TRANSMISSIOxNT  OF  DISEASE 

The  Microbic  Diseases. — It  seems  a  confusion  of  thought  to  the 
student  of  heredity  to  speak  of  the  inheritance  of  any  microbic  disease. 
At  one  time  the  hereditary  transmission  of  microbic  diseases  was  gen- 
erally believed.  ,Now  we  know  that,  in  the  true  sense  of  the  term,  no 
infectious  disease  is  transmitted  hereditarily — for  even  in  the  case  of 
syphilis  the  Treponema  pallidum  is  carried  in  the  germ  or  sperm  as  a 
foreign  body.  Tuberculosis  at  one  time  was  considered  as  transmitted, 
but  we  now  know  that  this  occurs  so  seldom  that  the  popular  pamphlets 
are  entirely  justified  in  denying  it  entirely. 

Children  are  sometimes  born  with  smallpox,  measles,  and  other  in- 
fections ;  these  are  not  true  instances  of  heredity,  but  cases  of  congenital 
transmission. 

Congenital  Transmission. — Prenatal  infection  is  not  a  true  in- 
stance of  inheritance.  Microbic  diseases  may  be  acquired  by  infection 
through  the  placenta  during  the  fetal  period.  The  placenta  is  a  bet- 
ter filter  for  some  infections  than  for  others.  Thus,  anthrax  and  tuber- 
culosis of  the  mother  are  rarely  transmitted  to  the  fetus,  while  there 
is  great  liability  in  the  case  of  syphilis.  The  fetus  in  utero  may  take 
smallpox,  measles,  and  other  infections,,  but  these  instances  are  more 
properly  spoken  of  as  congenital  than  inherited. 

We  must  remember  that  to  be  inherited  on  the  part  of  the  offspring 
or  transmitted  on  the  part  of  the  parents,  biology  includes  only  those 
characters  or  their  physical  bases  which  were  contained  in  the  germ 
plasm  of  the  parental  sex  cells  (Martins)  ;  or,  as  Yerco  says,  "what 
operates  on  the  germ  after  the  fusion  of  the  sex  nuclei,  rnodifying  the 
embryo,  or  even  inducing  an  actual  deviation  in  the  development,  cannot 
be  spoken  of  as  inherited.  It  belongs  to  the  category  of  early  acquired 
deviations  which  are,  therefore,  frequently  congenital." 

Hereditary  Transmission  of  a  Tendency  to  a  Disease. — While  the 
disease  itself  may  not  be  transmitted,  a  tendency  to  a  disease,  known  as  a 
diathesis,  may  be  transmitted  through  successive  generations.  A  person 
may  inherit  a  small  bony  structure,  a  poor  musculature,  "weak"  lungs, 
susceptible  mucous  membranes,  or  an  abnormal  amount,  distribution,  or 
development  of  lymphoid  structures,  etc.  In  fact,  we  are  not  all  born 
equal,  and  most  persons  have  some  vulnerable  structure  or  organ  which 
is  commonly  spoken  of  as  their  "weak  point."  In  many  cases  this  locus 
minoris  resistentiae  is  transmitted  as  a  defect  in  structure  or  function. 

Davenport  has  collected  the  health  records  and  other  characteristics 
furnished  for  over  two  hundred  families  by  members  of  the  families 
concerned.  He  finds  certain  definite  facts  in  the  behavior  of  some  of 
the  commoner  diseases.  As  an  example  of  the  inheritance  of  a  gen- 
eral weakness  in  an  organ  he  cites  the  case  of  the  mucous  membranes. 
Thus,  in  one  family  the  principal  diseases  to  which  there  was  liability 
were  located  in  the  mucous  membranes  of  the  nose,  throat,  and  bronchi. 


THE  HEREDTTAHY  TIJAXSMTSSTOX  OF  DISEASE      645 

In  another  family  the  centtT  of  suscf'ptil)ility  was  moro  specific,  l)ein«; 
nearly  confined  to  the  nose  and  throat,  in  another  family  the  weak- 
ness was  in  the  ear;  in  another  the  lungs;  in  another  the  skin;  in  one 
family  the  kidneys  were  the  seat  of  incidence,  etc. 

The  examination  of  the  health  pedigrees  of  a  number  of  families 
impresses  one  by  the  fact  that  the  incidence  of  disease  is  not  always 
haphazard,  for  in  any  large  family  the  various  causes  of  death  do  not 
occur  in  the  proportions  given  in  the  census  table  for  the  population  as 
a  whole. 

Tuberculosis. — We  know  that  tuberculosis  is  never  transmitted 
hereditarily,  and  is  seldom  contracted  congenitally.  The  reason  that 
tuberculosis  runs  in  a  family  is  twofold:  (1)  an  inherited  predisposi- 
tion to  the  disease,  and  (2)  increased  chances  of  infection,  especially 
during  infancy.  Just  what  the  tendency  or  predisposition  is,  is  not  well 
understood.  We  do  know,  however,  that  the  predisposition  is  not  so  great 
but  that  it  may  be  overcome;  the  infection  may  be  avoided  and  the 
disease  prevented.     Xo  one  is  born  doomed  to  die  of  tuberculosis. 

It  is  now^  perfectly  plain  that  the  principal  reason  why  tuberculosis 
runs  in  families  is  the  close  association  between  the  infected  and  well 
members  of  the  family,  which  increases  the  chances  of  infection  and  re- 
infection. 

All  persons  inherit  the  power  of  resisting  tuberculosis  in  varying 
degree.  The  inborn  immunity  is  not  marked  in  any  case ;  in  some  indi- 
viduals it  is  quite  feeble.  The  border  line  between  immunity  and  sus- 
ceptibility to  tuberculosis  in  the  human  species  is  delicately  balanced  and 
may  readily  be  overturned   (see  page  177). 

Syphilis.— Syphilis  and  the  consequences  of  syphilis  are  transmitted 
from  parent  to  offspring — "even  unto  the  third  and  fourth  generation." 
The  transmission  of  the  infection  itself  is  congenital :  the  transmission  of 
the  consequences  of  syphilis,  such  as  defectives,  etc..  may  follow  the  laws 
of  heredity. 

The  methods  of  transmission  may  be  briefly  summarized  as  fol- 
lows: (a)  The  husband  has  syphilis.  He  infects  his  wife:  and  she 
infects  the  embrv'o.  Experience  indicates  that  this  is  the  usual  method 
of  transmission,  and  that  the  wife  is  often  infected  soon  after  marriage. 
The  treponemata  circulating  in  the  blood  stream  of  the  mother  appar- 
ently penetrate  the  placenta  with  ea.se,  and  enter  the  blood  stream  of 
the  child.  The  child  naturally  has  no  trace  of  a  chancre,  so  that  we 
have  here  another  indication  of  the  possibility  of  syphilis  d'emblee. 

It  is  now  generally  believed  that  paternal  transmission  directly  to 
the  fetus  is  impossible.  Treponemata  have  been  demonstrated  in  the 
seminal  fluid  of  syphilitics,  and  numerous  innocent  marital  infections 
have  been  transmitted  by  means  of  infected  spermatic  fluid  by  husbands 
who  thought  thev  were  healthv. 


646      THE  HEREDITAEY  TEANSMTSSION  OF  DISEASE 

(b)  The  wife  alone  has  syphilis  and  infects  the  child  in  the  same 
manner  as  in  (a).  It  is  fairly  obvious  that  in  any  case  of  congenital 
syphilis,  the  mother  is  certainly  infected,  and  the  father  is  usually,  but 
not  necessarily  infected. 

A  syphilitic  father  may  beget  an  apparently  healthy  child,  even  when 
the  disease  is  fresh  and  full-blown.  On  the  other  hand,  in  very  rare 
instances  a  man  may  have  syphilis  when  young,  undergo  treatment,  and 
for  years  present  no  signs  of  disease,  and  yet  his  first-born  may  show 
very  characteristic  lesions.  The  closer  the  begetting  to  the  primary  sore 
the  greater  the  chance  of  infection.  A  man  with  tertiary  lesions  may 
beget  healthy  children.  As  a  general  rule,  it  may  be  said  that  with 
judicious  treatment  the  transmissive  power  seldom  exceeds  three  or 
four  years. 

Colle's  and  Prof  etas  Laws. — Colle,  in  1837,  stated  that  apparently 
normal  women  bearing  syphilitic  children  do  not  contract  syphilis  when 
exposed  to  that  infection.  (This  is  also  called  Baumes'  law.)  Prof  eta's 
law  states  that  a  child  showing  no  taint  but  born  of  a  woman  suffering 
from  syphilis  will  not  become  infected  even  though  suckled  by  its  mother. 
Exceptions  to  both  Colle's  and  Profeta's  laws  are  recorded.  The  ex- 
planation of  these  so-called  laws  was  that  the  mother  was  immune  in 
Colle's  law  and  the  baby  in  Profeta's  law.  We  now  know,  however,  that 
both  the  mother  and  the  baby  under  these  circumstances  are  infected 
with  spirochetes  but  do  not  manifest  clinical  symptoms  of  the  disease. 
The  apparent  immunity  in  both  instances  is  due  to  the  fact  that  super- 
infection does  not  occur.     See  page  63. 

Concerning  the  results  of  congenital  syphilis,  we  have  the  following 
possibilities:  (1)  The  infection  causes  a  cessation  of  development  and 
abortion.  (2)  The  fetus  grows,  but  is  born  before  the  normal  expira- 
tion of  intra-uterine  life  (premature  births).  (3)  The  fetus  goes  to 
term,  but  is  born  dead  (stillbirths).  (4)  The  child  is  born  at  term 
living,  but  with  unmistakable  signs  of  syphilis,  and  dies  shortly.  (5) 
The  child  may  show  no  symptoms  of  syphilis  at  birth,  but  a  few  weeks 
later  develop  typical  symptoms.  It  may  die,  or  as  the  result  of  treat- 
ment, may  live.  Syphilis  causes  death  in  80  per  cent,  of  those  con- 
genitally  infected.  It  is  a  still  greater  tragedy  in  the  20  per  cent,  who 
survive.  (6)  The  child  shows  no  symptoms  of  syphilis  for  weeks,  months 
or  possibly  years,  the  disease  being  latent,  and  becomes  manifest  in  some 
cases  as  late  as  twenty-eight  years  in  the  tertiary  form  ( so-called  syphilis 
hereditaria  tarda).  (7)  The  child  may  be  puny,  weak,  susceptible  to 
infections,  underweight,  and  lack  stamina — in  short,  a  runt.  This  may 
occur  without  obvious  manifestations  of  the  disease. 

See  article  on  Syphilis,  pages  55  to  67. 

Cancer. — It  will  probably  be  a  long  time  before  the  final  word  can 
be  said  concerning  the  influence  of  heredity  in  cancer. 


THE  HKK'KDITAKV  TKANSM ISSION   OF   DISEASE      647 

Claude  She-  has  studied  the  question  (»f  inlicritaiKv  ol'  cancer  in  mice 
and  concludes  that  cancer  is  not  inherited,  hut  that  a  tendency  t^)  pnjduce 
cancer  under  the  right  stimuhis  is  transmitted  from  generation  to  genera- 
tion. The  stimulus  seems  to  he  over-irritation  at  the  point  where  the 
cancer  arises.  Cancer  can  he  hi-ed  in  and  out  of  strains  of  mice  at  will. 
Cancer  is  transmitted  rather  as  a  tendency  to  occur  from  a  given  provoca- 
tion, an  over-irrilation.  Tlie  elimination  of  over-irritation  in  one  of 
cancer  ancestry  should  materially  lower  the  rate.  Further,  the  eugenic 
control  of  mating  so  tliat  cancer  shall  not  he  potential  in  t)oth  parent*^ 
would  also  vt'ry  materially  decrease  the  incidence  of  human  cancer. 
Tyzzer  and  Little  have  also  shown  that  a  tendency  to  cancer  is  trans- 
mitted in  experimental  lahoratory  animals. 

It  seems  clearly  estahlished  that  certain  chronic  irritating  agencies 
may  induce  cancer,  at  least  in  susceptible  persons.  The  irritation  may 
he  actinic,  thermal,  chemical,  or  mechanical.  Thus  we  have  Rontgen  ray 
epitheliomas,  Kaugri  skin  cancer  of  India,  the  epitheliomas  on  the  arms 
of  paraffin  makers,  chimney-sweep's  cancer  of  England,  and  also  the 
brand  cancer  of  cattle.  Each  of  these  present  definite  and  distinct 
lesions;  each  has  a  constant  etiology,  clinical  course,  and  patholog}'.  To 
this  same  group  also  belongs  the  buyo  cheek  cancer  of  the  Philippine 
Islands  caused  by  chewing  buyo,  the  irritating  agent  of  which  appears 
to  be  lime. 

The  prevailing  misconception  that  cancer  is.  a  hopeless  and  incurable 
disease  is  not  entirely  correct.  Cancer  at  first  appears  to  be  a  local 
disease,  and  therefore  curable  if  detected  in  time  and  removed. 

Cancer  causes  upward  of  80,000  deaths  a  year  in  the  United  States. 
It  is  chiefly  a  disease  of  adult  life.  Eighty-three  per  cent,  of  deaths  from 
cancer  occur  at  the  age  of  forty-five  and  over.  In  the  United  States,  can- 
cer-causes one  death  in  every  eight  women,  and  one  in  every  fourteen  men 
over  forty  years  of  age.  The  excessive  mortality  from  cancer  in  women 
is  due  to  the  prevalence  of  cancer  of  the  breast  and  generative  organs. 

Cancer  may  be  inoculated  in  experimental  animals,  but  the  disease 
is  not  a  contagious  or  infectious  one,  in  the  sense  that  it  is  communicable 
under  natural  conditions  from  person  to  person.  The  supposed  "cancer 
houses,"  "villages,"  or  "streets"  do  not  bear  the  light  of  critical  examina- 
tion. The  "virus"  is  probably  not  a  microorganism,  but  the  cancer  cell 
itself,  which  undergoes  unrestrained  and  riotous  proliferation.  In  other 
words,  the  parasite  is  the  cancer  cell  itself,  and  the  cancer  cell  comes  from 
a  normal  preexisting  epithelial  cell. 

The  Commission  on  Cancer  of  the  Medical  Society  of  the  State  of 
Pennsylvania  found  that  39  per  cent,  of  the  superficial  cancers  and  40 
per  cent,  of  the  deep-seated  cancers  are  preceded  by  a  precancerous  condi- 
tion or  a  chronic  irritation.     In  other  words,  in  almost  one-half  of  the 

'Jour.  Med.  Res..  191.3.  Vol.  XXXII.  w.  168. 


648      THE  HEREDITARY  TRANSMISSION  OF  DISEASE 

patients  that  are  sent  to  the  surgeon  with  a  fully  developed  cancer  there 
has  been  a  previous  condition  which  might  have  been  removed  and  cancer 
might  not  have  developed.  Superficial  cancers  frequently  exist  for  a 
year  and  a  half  before  they  come  to  the  surgeon. 

Warthin,^  from  studies  of  a  long  series  of  cases,  believes  that  a  marked 
susceptibility  to  carcinoma  exists  in  the  case  of  certain  family  genera- 
tions and  family  groups.  This  susceptibility,  he  thinks,  is  frequently 
associated  with  a  marked  susceptibility  to  tuberculosis  and  also  with 
reduced  fertility.  The  multiple  occurrence  of  carcinoma  in  a  family 
generation  practically  always  means  its  occurrence  in  a  preceding  genera- 
tion. The  family  tendency  is  usually  more  marked  when  carcinoma 
occurs  in  both  maternal  and  paternal  lines.  Family  susceptibility  to 
carcinoma  is  shown  particularly  in  the  case  of  carcinoma  of  the  mouth, 
lip,  breast,  stomach,  intestines,  and  uterus.  In  a  family  showing  the 
occurrence  of  carcinoma  in  several  generations  there  is  a  decided  .tendency 
for  the  tumor  to  develop  in  the  breast  of  the  youngest  generations.  In 
this  case  the  tumors  often  show. an  increased  malignancy.  Levin's  study 
of  cancerous  fraternities  leads  him  to  believe  that  the  cancerous  members 
correspond  very  closely  to  the  Mendelian  percentage  of  members  with 
recessive  unit  characters  in  a  hybrid  generation.  Levin  concludes  that 
resistance  to  cancer  is  a  dominant  character  whose  absence  creates  a  sus- 
ceptibility to  cancer.  While  some  of  Warthin's  cases  show  a  family  his- 
tory suggesting  this  form  of  inheritance,  others  indicate  a  progressive 
degenerative  inheritance,  that  is,  the  running  out  of  a  family  line  through 
the  gradual  development  of  an  inferior  stock,  particularly  as  far  as 
resistance  to  tuberculosis  is  concerned. 

Statistical  studies  indicate  that  cancer  is  on  the  increase.*  This, 
however,  is  questioned.  At  least  it  is  necessary  to  know  the  age  distribu- 
tion and  many  other  factors  before  we  can  say  that  cancer  is  on  the 
increase.  The  death  rate  from  cancer  in  the  United  States  rose  from 
63  per  100,000  in  1900  to  81.6  in  1917.  These  are  census  figures  and 
may  not  represent  the  real  situation. 

Leprosy  was  formerly  regarded  as  one  of  the  inherited  infections, 
but  leprosy  is  not  transmitted.  The  children  of  lepers  born  out  of  leper 
districts,  in  England  or  the  United  States,  for  example,  never  inherit  it. 
The  disease  is  contracted  after  birth,  as  tuberculosis  and  other  microbic 
diseases  are  contracted. 

Deaf-mutism. — Deaf-mutism  is  due  to  a  great  variety  of  causes,  but 
in  different  individuals  of  the  same  family  the  chances  are  large  that  it  is 

^Warthin,  A.  S. :  Heredity  with  Reference  to  Cancer.  Arch.  Int.  Med., 
Chicago,  Nov.,  XII,  5,  pp.  485-612. 

*  Frederick  L.  Hoffmann,  ''The  Mortality  from  Cancer  Tluoughout  the 
World."  Also  Bull.  8.  Amer.  »S'oc.  foi-  the  Control  of  Cancer.  Cancer  Pamphlets 
I  to  X,  published  by  the  American  Medical  Association.  Popular  articles  on  the 
subject. 


'I'liK  iii:i{i-:i)!'rAK'v  tk.wsmission  ok  disease     ca\) 


(ItR'  io  i\\v  same  (IcIVcl.  'I'liis  dclVct  is  rr(M|ii('ntlv  roccssivc,  that  is,  liiddcii 
ill  the  luinnal  i  liildrcii.  'I'wd  smh  iKH'iiial  chiMrcii  who  are  cousins  but 
from  dear-iuute  stock  tend  to  liavc  alioui  (nic-lniirth  of  their  ofl'sprin^^ 
deaf-mutes.      The    propor-  , 

tiou  of  deaf  oif spring  is 
thrice  as  great  among 
cousin  luarriaii'es  as  among 
otliers.  'i'hf  coiuliisions 
of  Fay,  based  on  ivvtensive 
statistics,  deserve  to  be 
widely  known.  "Under  all 
circumstances  it  is  exceed- 
ingly dangerous  for  a  deaf 
person  to  marry  a  blood 
relative,  no  matter  whether 
tbe  relative  is  deaf  or  bear- 
ing, nor  whether  the  deaf- 
ness of  either  or  botb  or 
neither  of  the  partners  is 
congenital,  nor  whether 
either  or  l)ot]i  or  neither 
have  other  deaf  relatives 
besides  the  othpr  partner." 

Albinism.  • —  Albinism 
belongs  to  a  class  of  cases 
resulting  from  the  absence 
of  a  character  or  quality — 
in  this  instance  the  absence 
of  a  pigment  determiner. 
Two  all)ino  parents  have 
only  albino  children.  Nor- 
mal offspring  of  an  albino 
and  a  pigmented  parent 
may  transmit  tbe  albinic 
condition. 

Albinism  is  an  extreme 
case  of  blondeness,  all  pig- 
ment being  absent  from 
skin,  hair,  and  eyes.  The 
method  of  inheritance  re- 
sembles that  of  eye  color.  When  both  parents  lack  pigment,  all  off- 
spring are  likewise  devoid  of  pigment.  When  one  parent  only  is  an 
albino  and  the  other  is  unrelated,  then  the  children  are  all  pigmented. 
Whenever  pigmented  parents  have  albino   children,  the  proportion   of 


r;50      THE  HEEEDlTAPvY  TEANSMLSSIOX  OF  DISEASE 

the  albinos  approaches  the  ideal  and  expected  Mendelian  proportions — • 
25  per  cent.  Davenport  points  out  that  albinos  may  avoid  albinism 
in  their  offspring  by  marrying  unrelated  pigmented  persons.  Pigmented 
persons  belonging  to  albinic  strains  must  avoid  marrying  cousins,  even 
pigmented  ones,  because  both  parents  might,  in  that  case,  have  albinic 
germ  cells  and  produce  one  child  in  four  albinic.  Albino  communities, 
of  which  there  are  several  in  the  United  States,  are  inbred  communities, 
but  not  all  inbred  communities  contain  albinos. 

Color-blindness,  or  Daltonism. — Color-blindness,  or  daltonism,  is  a 
condition  probably  not  localized  in  the  eyes,  but  due  to  some  defect  in 
the  central  nervous  structure.  It  is  transmitted  hereditarily.  Color- 
blindness is  much  commoner  in  men  than  in  women.  A  color-blind  man, 
however,  does  not  transmit  color-blindness  to  his  sons;  the  daughters, 
also,  are  themselves  normal,  provided  the  mother  was,  yet  the  daughters 
transmit  color-blindness  to  half  their  sons.  A.  color-blind  daughter 
could  be  produced  apparently  only  by  the  marriage  of  a  color-blind  man 
with  a  vt^oman  who  transmits  color-blindness,  since  the  daughter,  to  be 
color-blind,  must  have  received  this  unit  character  from  both  parents, 
whereas  the  color-blind  son  receives  the  character  only  from  his  mother; 
that  is,  the  condition  is  sex-linked. 

Color-blindness  is  apparently  due  to  a  defect  in  the  germ  cell — 
absence  of  something'  normally  associated  there,  with  an  X-structure 
which  is  represented  twice  in  women,  once  in  men. 

The  following  interesting  family  history,  studied  by  Horner,  shows 
the  hereditary  persistence  of  color-blindness  and  its  transmission  to  male 
offspring  through  normal  females. 

M 


i 


M 


F 

i 


M 


M 


F 


F 

I 
M 


F 


M         M         M  FMMFFMMMF 


M  F 


F  F  F 


M  =  Male. 

F  =  Female. 

Bold-faced  type  =  Color-blind   subjects. 


THE  HEREDITAIJV  TIJAXSMISSIOX   OF  DISEASE      051 

The  fi)ll()\viii<;  pedigree  of  a  t'aiuily  containing  color-lilind   members 
was  worked  out  l)V  Dr.  Kivcr*;  among  the  Todas.  an  Indian  tril^e: 


M 


U  M  F  F  M     F     F  M  M  M 


F     F  M 


F   F      M   F   M   F,  F 


M  I^I  F      F  F      M  F  F      M  F  M  F,  F  MM      M  M  M   M   F 


Hemophilia. — Hemophilia  is  a  condition  in  which  the  blood  does 
not  coagulate  })roperly,  and  those  having  this  condition  may  bleed  to 
death  from  minute  wounds.  It  is  transmitted  hereditarily  and  is  largely 
confined  to  males,  although  transmitted  by  normal  females.  It  is  oi^e 
of  the  best  instances  of  an  hereditable  character,  sex-linked. 

M    F 


M  F  M  F  M  M 


F 


MF       FMMMFMMF      F        MMMFMFMMFMM 


M   F  M   F        M  F  M  F  M  F  F  M  F  M  F  F  M  F       M   F 

(Bold-faced  type  indicates   bleeders.) 

The  foregoing  case,  given  by  Klebbs,  is  instructive  in  showing  how 
the  tendency,  though  transmitted  through  daughters,  finds  expression 
only  in  the  males,  and  in  illustrating  first  a  diffusion  and  then  a  wan- 
ing of  the  peculiarity  (Thompson). 

Gout. — It  is  known  that  gout  runs  in  families,  but  just  what  the 
predisposition  is  that  favors  this  condition  of  deranged  metabolism  is 
not  known.  During  four  centuries  one  family  history  showed  that  out 
of  535  gouty  subjects  309  had  a  family  taint — about  60  per  cent.  In 
another  family  out  of  156  cases  140  had  a  family  taint,  about  90  per 
cent.  Statistics  show  that  in  from  50  to  60  per  cent,  of  all  cases  the 
disease  existed  in  the  parents  or  grandparents.  It  seems  clear  that  some 
predisposing  factor  may  be  transmitted  hereditarily,  but  in  any  individual 
case  it  is  not  always  plain  how  much  is  due  to  heredity  and  how  much 
is  acquired. 


652      THE  HEREDITARY  TRANSMISSION  OF  DISEASE 

Brachydactylism. — A  typical  example  of  an  abnormality  transmitted 
hereditarily  is  that  of  brachydactylism,  or  short-fingeredness,  a  condi- 
tion in  which  each  digit  comprises  only  two  phalanges — the  fingers  are 


all  thumbs.  This  condition  seems  to  be  due  to  an  inhibition  of  the 
normal  growth  process,  that  is,  normality  implies  entire  absence  of  the 
determiner  that  stops  the  growth  of  the  fingers  in  the  brachydactyl. 


THE  HEREDTTAK'V  TIJAXSMISSION  OF   DISKASK      r,53 

Tlius.  a  brachydactyl  person  married  even  to  a  normal  person  will 
beget  100  per  cent,  or  50  per  cent  abnormals,  according  to  circum- 
stances; but  two  parents  wlio,  though  derived  from  brachydact}'!  strains, 
altogether  lacking  the  determiner  which  inhibits  the  growth  of  the 
fingers  may  have  only  normal  children. 

According  to  Punnett,  brachydactylism  is  a  good  example  of  a  simple 
Mendelian  case.  It  behaves  as  a  simple  dominant  to  the  normal;  that 
is,  it  depends  upon  a  factor  which  the  normal  does  not  contain.  The 
recessive  normals  cannot  transmit  the  affected  condition  whatever  their 
ancestry.  Once  free,  they  always  remain  free,  and  can  marry  other  nor- 
mals with  full  confidence  that  none  of  their  children  will  show  the 
deformity. 

Polydactylism. — Tolydactylism  is  a  condition  in  which  there  are 
supernumerary  fingers  or  toes.  This  is  a  defect  which  may  be  trans- 
mitted through  successive  generations.  Other  defects  of  the  fingers  and 
toes  are  transmitted  in  accordance  with  the  Mendelian  expectation. 

Fragilitas  Ossium. — Fragilitas  ossium,  or  osteopsathyrosis,  a  weakness 
of  the  long  bones,  may  arise  from  a  number  of  pathological  conditions 
affecting  the  bones.  But  the  typical  fragilitas  ossium  or  brittle  bones 
runs  through  families.  Davenport  and  Conrad^  have  shown  that  the 
factor  which  determines  the  deficient  bone  formation  is  a  dominant  one. 
Different  degrees  of  the  condition  are  transmitted  true  to  type.  Thus  in 
some  families  the  slightest  pressure  results  in  fracture ;  in  other  families 
the  bones  are  fairly  resistant.  The  association  of  blue  sclerotics  with 
brittle  bones  has  often  been  pointed  out ;  the  condition  of  blue  sclerotics 
also  appears  to  be  a  dominant  trait. 

Myopia. — Myopia  can  hardly  be  called  a  disease  in  the  strict  sense, 
being  a  structural  defect  in  the  focusing  power  of  the  optical  apparatus. 
It  seems  that  the  structural  peculiarity  which  leads  to  short-sightedness 
is  transmitted. 

Cataract. — Bateson  and  others  have  collected  pedigrees  in  which 
cataracts  run  in  families.  Presenile  cataract  especially  appears  to  be 
transmitted  hereditarily.  The  transmission  is  as  a  rule  direct,  the  skip- 
ping of  a  generation  being  unusual.  Cataract  is  also  favored  by  various 
constitutional  diseases,  such  as  diabetes,  Bright's  disease,  and  diseases  of 
the  vascular  system.  Exposure  to  the  light  and  heat  ray  from  glowing 
coals,  or  flashes  of  electricity  produce  opacities  of  the  lens.  Injury,  and 
prolonged  eye  strain  are  responsible  for  many  cataracts. 

Retinitis  Pigmentosa. — Eetinitis  pigmentosa  is  a  degenerative  disease 
of  the  retina  which  is  transmitted  hereditarily.  Xormals  may  carry 
the  disease,  so  that  two  normal  cousins  from  retinitis  stock  may  have 

'Davenport,  C.  B.,  and  Conrad.  H.  S.:  "Hereditary  Fragility  of  Bone.'"  Proc. 
Nat.  Acad.  Sc,  1915,  i,  537. 


654      THE  HEREDITARY  TRANSMISSION  OF  DISEASE 

offspring  with  retinitis.     A  large  percentage  of  cases  of  retinitis  come 
from  consanguineous  marriages. 

Diabetes  Mellitus. — Hereditary  influences  seem  to  play  an  important 
role  in  diabetes  mellitus,  for  cases  are  on  record  of  its  occurrence  in  many 
members  of  the  same  family.  Thus,  out  of  104  cases  of  diabetes  mellitus 
22  had  a  family  taint— about  20  per  cent.  Naunyn  obtained  a  history  of 
diabetes  in  35  out  of  201  private  eases,  but  in  only  7  of  157  hospital 
cases. 

Orthostatic  Albuminuria. — Orthostatic  albuminuria  occurs  in  boys 
more  commonly  than  girls.  These  are  often  the  children  of  neurotic 
parents,  and  have  well-marked  vasomotor  instability.  Defects  or  pe- 
culiarities in  the  filtering  apparatus  in  the  kidneys  may  arise  as  a 
germinal  variation  and  be  handed  on  from  generation  to  generation. 
Under  conditions  which  may  mean  nothing  to  normal  subjects  this  defect 
in  the  kidney  may  find  expression  in  active  disease.  In  this  case,  as  in 
gout,  it  may  not  be  proper  to  speak  of  the  disease  itself  being  transmitted 
hereditarily,  but  the  tendency  to  deviate  is  so  transmitted. 

Alcoholism. — Alcohol  as  well  as  lead  and  other  poisons  can  damage 
the  germ  cell  of  the  male  in  such  a  way  as  to  express  itself  by  defective 
offspring  (Rauschkinder,  or  Jagchildren).  It  is  a  common  observation 
that  among  the  offspring  of  drunkards  are  many  cases  of  unhealthy,  in- 
sane, and  criminal  types.  The  disastrous  results  may  be  manifested  by 
nervous  disorders,  varying  from  hyperexcitability  to  dementia ;  or  as  de- 
.bility  and  lack  of  developmental  vigor  expressed,  for  instance,  in  infan- 
tilism, want  of  control,  imbecility,  or  as  structural  abnormalities,  espe- 
cially of  the  head  and  brain.  The  results  are  so  varied,  they  suggest  that 
what  is  inherited  is  general  rather  than  specific.  Thus,  the  offspring  of 
alcoholic  parents  are  not  necessarily  predisposed  in  any  one  particular 
direction,  except  that  the  nervous  system  is  most  liable  to  be  affected. 
They  may  be  epileptic,  idiotic,  insane,  etc.  On  the  other  hand,  it  is  neces- 
sary to  recognize  that  what  may  be  inherited  is  not  the  result  of  alcohol- 
ism, but  rather  the  predisposition  which  led  the  parent  to  become  alco- 
holic. This  is  clearly  illustrated  in  cases  where  the  parent  did  not  acquire 
the  alcoholic  habit  until  after  the  children  were  born,  Clouston  observes 
that  "it  is  not  the  craving  for  alcohol  that  was  inherited,  but  a  general 
psychopathic  constitution  in  which  the  alcoholic  stimulus  is  an  undue 
stimulus  and  the  mental  control  deficient."     See  page  430. 

Migraine. — That  migraine  is  transmitted  hereditarily  is  indicated 
from  the  family  histories  of  those  suffering  with  this  affection. 

Buchanan  '^  found  from  a  study  of  1,300  persons  suffering  with  mi- 
graine that  it  is  transmitted  in  the  Mendelian  ratio.     His  studies  estab- 
lish the  hereditary  nature  of  the  affection, 
'Med.  Record,  Nov.   13,   1920,  p.  807. 


TIIK   IIKRKDITAIJV  TKWXSMISSIOX  OF  DISEASE      055 

Anaphylaxis,  or  Food  Idiosyncrasies.— Ivxperiiiieiital  evidciK-e,  as 
well  a.s  I'amily  hisluries,  clearly  indicates  tiiat  hypersusceptibility  to 
certain  foods,  such  as  egg,  shellfish,  strawberries,  tomatoes,  etc.,  is  trans- 
mitted hereditarily  throiijjh  several  generations.  The  transmission  is 
sometimes  specific  and   limited  to  one  particular  food. 

Hay  fever  and  other  anaphylactic  conditions  such  as  asthma,  angio- 
neurotic edema,  etc.,  usually  show  a  family  history  of  "idiosyncrasies" 
of  various  sorts.     See  page  605. 

Epilepsy. — Brown-Sequard  showed  conclusively  that  artificially  in- 
duced epilepsy  in  the  guinea-pig  is  transmissible.  The  statistics  col- 
lected for  man  give  from  9  to  over  40  per  cent,  of  cases  in  which  heredity 
is  an  important  predisposing  cause.  Gowers  gives  35  per  cent,  for  his 
cases.  In  the  Elw3'n  cases  32  of  the  126  gave  a  family  history  of  nervous 
derangement  of  some  sort,  either  paralysis,  epilepsy,  marked  hysteria,  or 
insanity.  Thom's  ^  study  of  1,536  epileptics  at  the  Monson  State  Hos- 
pital (Mass.)  would  make  it  appear  that  epilepsy  is  transmitted  directly 
from  parents  to  offspring  less  frequently  than  we  have  heretofore  been 
led  to  believe. 

Chronic  alcoholism  in  the  parents  is  also  regarded  as  a  potent  pre- 
disposing factor  in  the  production  of  epilepsy.  Echeherria  has  analyzed 
572  cases  bearing  upon  this  point,  and  divided  them  into  three  classes,  of 
which  257  cases  could  be  traced  directly  to  alcohol  as  the  cause,  126 
cases  in  which  there  were  associated  conditions,  such  as  syphilis  and 
traumatism,  189  cases  in  which  alcoholism  was  probably  the  result  of 
the  epilepsy.  Figures  equally  strong  are  given  by  Martin,  who,  in  150 
insane  epileptics,  found  83  with  a  marked  history  of  paternal  intem- 
perance. Of  the  126  Elwyn  cases  in  which  the  family  history  of  this 
point  was  carefully  investigated,  a  definite  statement  was  found  in  only 
4  of  the  cases  (Osier). 

Huntingfton's  Chorea. — Huntington's  chorea  is  frequently  inherited. 
The  disease  is  kno'svTi  as  chronic  hereditary  chorea.  It  was  described  by 
Lyon  in  1863,  who  traced  the  disease  through  five  generations.  Hunt- 
ington in  1872  gave  the  three  salient  points  in  connection  with  the 
disease,  viz.:  (1)  its  hereditary  nature;  (2)  association  with  psychical 
troubles;  and  (3)  late  onset  between  the  thirtieth  and  fortieth  year. 

Huntington's  chorea  is  a  typical  dominant  trait.  The  normal  con- 
dition is  recessive;  in  other  words,  the  disease  is  due  to  some  positive 
determiner.  Persons  with  this  dire  disease  should  not  have  children, 
but  the  members  of  normal  branches  derived  from  the  affected  strain 
are  immune  from  the  disease.  This  disease  forms  a  striking  illustra- 
tion of  the  principle  that  many  of  the  rarer  diseases  of  this  country 
can  be  traced  back  to  a  few  foci,  even  to  a  single  focus ;  certainly  in  this 
case  many  of  the  older  families  with  Huntington's  chorea  trace  back  to 

'Boston  M.  and  S.  Journal,  CLXXIV,  16,  April  20,  1916,  p.  573. 


656      THE  HEREDITAEY  TRAXSMLSSIOX  OF  DISEASE 

the  New  Haven  colony  and  its  dependencies  and  subsequent  offshoots 
(Davenport).^ 


V  c 

o  I 

^  e 

^  2 


2  G 


d  i_j 


Friedreich's  Disease— Hereditary  Ataxia.— This  disease  resembles 
locomotor  ataxia,  although  differing  from  it  in  several  essential  par- 
ticulars.    It  begins  in  childhood- and  usually  occurs  in  a  family  having 

*Am.  Journ.  of  Insanity,  Oct.,  1916,  LXXIII,  No.  2,  p.   195. 


THK   IlKKKDrrAKV   TKANSM ISSIOX  OF  DISEASE      657 

other  iueniber.s  of  tlie  I'aniily  aU'ected  witli  the  same  disease.  There 
are  curious  forms  of  incoordination  and  loss  of  knee-jerk,  early  talipes 
equinus,  scoliosis,  nystagmus,  and  scanning  speech.     The  affection  lasts 


as   0) 

8-2 


S  s; 


cc 


e:    cj  — • 
o 

<      . 


.2  ■- 


for  many  years  and  is  incairable.  In  1861  Friedreich  reported  six  cases 
of  this  form  of  ataxia  in  one  family.  Since  then  it  has  usually  been 
observed  to  be  a  family  disease,  and  is,  therefore,  assumed  to  be  trans- 


658      THE  HEREDITAEY  TRAXSMISSIOX  OF  DISEASE 

mitted  hereditarily.  The  eugenic  teaching  in  this  affection,  according 
to  Davenport,  is  that  normal  members  of  the  affected  fraternities  should 
marry  only  outside  the  strain.  Whether  all  cases  of  ataxic  offspring  of 
one  normal  pareiit  are  derived  from  consanguineous  marriage  is  still  un- 
certain and  warrants  hesitation  in  advising  the  marriage  of  any  ataxic 
person. 

Mental  Deficiency. — This  term  includes  imbecility,  idiocy,  feeble- 
mindedness and  psychopathic  inferiority,  etc.  In  this  class  we  have  one 
of  the  best  examples  of  a  pathological  condition  transmitted  by  inheri- 
tance. Davenport  believes  .that  imbecility  is  due  to  the  absence  of  some 
definite  simple  factor,  on  account  of  the  simplicity  of  its  method  of  inher- 
itance. Two  imbecile  parents,  whether  related  or  not,  have  only  imbecile 
offspring.  Davenport  states  that  there  is  no  case  on  record  where  two 
imbecile  parents  have  produced  normal  children. 

Dr.  H.  H.  Goddard,  of  the  Training  School  for  Feeble-]\Iinded,  at 
Vineland,  X.  J.,  has  studied  the  ancestry  of  children  in  the  Yineland 
institution  and  has  found  almost  without  exception  a  history  of  feeble- 
mindedness for  several  generations.  Dr.  Goddard's  remarkable  study  of 
the  Kallikak  family  has  already  been  referred  to.  In  this  instance  he 
traced  the  ancestry  of  a  SS-year-old  girl  through  about  1,100  individuals 
as  far  back  as  the  Revolutionary  AYar.  Similar  studies  are  being  carried 
out  in  other  institutions  and  always  with  similar  results.  The  subject  is 
fully  discussed  on  pages  425  and  615. 

Insanity. — Insanity  is  a  general  term  comprising  many  different 
conditions.  Xo  general  statement  can,  therefore,  be  made  except  that 
certain  forms  of  psychoses  are  undoubtedly  transmitted  through  suc- 
cessive generations.  It  is  safe  to  say  that  heredity  is  responsible  for 
more  cases  of  mental  diseases  than  any  other  single  cause.  Mental  dis- 
eases are  rare  in  persons  free  from  ancestral  taint,  except  as  the  result  of 
vounds  or  toxic  influences. 

Practically  all  the  statistics  accumulated  on  insanity  have  limited 
value  to  the  student  of  heredity,  because  they  do  not  give  numerical 
records  of  the  sane  members  of  the  families  of  the  insane.  The  subject  is 
fully  discussed  in  Section  II,  page  421. 


REFERENCES 

Lock,  E.  H.  :     "Variation,  Heredity,  and  Evolution,"  1910. 

Huxley,  T.  H.  :     "Collected  Essays,"  Yol.  2,  1899. 

Lamarck,  J.  B. :    "Philosophie  Zoologique,"  1809 

Darwix,  Chas.  :     "The  Origin  of  Species,"  6th  Edition,  1872. 

Weismann,  a.  :     "Essays  Upon  Heredity,"  1889 ;  "The  Yariation  Theory," 

1906 ;  "The  Germ  Plasm :  A  Theory  of  Heredity"  (translated  by  W.  K 

Parker  and  H.  Eonnfeld,  1893). 


REFERENCES  G59 

Galto.v,  F.  :  "Natural  Inheritaiice,"  1SS9;  "Hereditary  Genius,"  1869; 
"■Enjjrlish  Men  of  Science,"  1S74;  "huiuiries  Into  Human  Faculty  and 
Its  Development,"  1883;  "Natural  Inheritance,"  ISSI);  "Kufj^enics :  Its 
Definition,  Scope,  and  Aims,"  1905. 

Davenport:  .  "Statistical  Methods,"  1904;  "Heredity  in  Relation  to  Eu- 
genics." 1911. 

Pearson,  K.:     "The  Grammar  of  Science,"  2d  Edition,  1900. 

Bateson,  W.  :  "Materials  for  the  Study  of  Variation,"  1S94;  "Mendel's 
Principles  of  Heredity."  1909. 

DeViues,  H.  :  "Die  ^lutationstheorie,"  1901;  "Species  and  Varieties:  Their 
Origin  hy  :^^utation,"  1905. 

Wilson,  E.  B.  :  "The  Cell  in  Development  and  Inheritance,"  2d  Edition, 
1900. 

TnoMPSux.  J.  A.:    "Heredity,"  1908. 

Castle.  Willlam  E.:     "Heredity,"  1911. 

Castle,  W.  E.  :     "Genetics  and  Eugenics."     Haxvard  Un.  Press,  1916. 

The  Proceedings  of  the  Roy.  Soc.  of  Medicine,  1909,  Vol.  II:  "The  Influ- 
ence of  Heredity  on  Disease,  with  Special  Reference  to  Tuberculosis, 
Cancer,  and  Diseases  of  the  Nervous  System." 

Punnett,  R.  C:    "Mendelism."  1911. 

See  also  references,  page  455,  "Mental  Hygiene." 


SECTION  V 
FOOD 

CHAPTER   I 
GENERAL  CONSIDERATIONS 

Foodstuffs  fall  naturally  into  two  great  divisions:  (1)  those  de- 
rived from  the  animal  kingdom,  and  (2)  from  the  plant  kingdom. 
The  animal  foods  are  much  more  apt  to  convey  infections  or  to  pos- 
sess injurious  properties  than  foods  derived  from  plant  life.  Of  the 
animal  foods  meat  and  milk  are  the  chief  offenders.  Water  ordinarily 
is  not  classed  as  a  food  because  it  passes  unchanged  through  the  body 
and  hence  does  not  furnish  energy.    Water  is  discussed  in  Section  VIII. 

It  is  often  said  that  there  is  "death  in  the  pot."  This  is  a  clever 
aphorism,  but  a  gross  exaggeration.  The  statement  is  misleading,  for 
it  implies  frequent  and  serious  injury  due  to  food,  whereas  food  poison- 
ing is  relatively  rare  and  seldom  fatal.  There  is  no  danger  in  clean 
food,  little  in  fresh  food,  and  still  less  in  thoroughly  cooked  food. 

The  hygienic  conscience  of  the  people  has  been  aroused,  and  a 
demand  is  being  established  for  clean,  fresh,  wholesome  foodstuffs. 
.The  separation  of  the  producer  and  the  consumer  and  the  demands  of 
large  cities  have  made  these  sanitary  reforms  eminently  necessary.  The 
pure  food  laws,  the  meat  inspection  act,  the  milk  ordinances,  and  the 
local  surveillance  over  markets,  provision  shops,  dairies,  food-handlers, 
etc.,  are  all  part  of  the  general  movement  to  obtain  a  reasonably  decent 
and  safe  food  supply. 

People  should  be  educated  to  demand  flesh  from  healthy  animals, 
cut  up  and  handled  in  a  careful  manner  by  butchers  free  from  dis- 
ease, and  to  demand  garden  truck  grown  in  clean  dirt  and  not  in  soil 
polluted  with  human  excrement.  Food  must  be  guarded  in  trans- 
portation and  purveyed  in  markets  and  shops  so  as  to  be  protected  from 
flies,  rats,  dust,  and  unnecessary  human  contact. 

The  prophylactic  and  therapeutic  uses  of  food  are  growing  subjects. 
It  is  only  necessary  to  point  out  the  importance  of  diet  in  the  preven- 
tion and  treatment  of  beriberi,  scurvy,  pellagra,  rickets,  tuberculosis, 
diabetes,  acidosis,  nephritis,  arteriosclerosis,  gout,  rheumatic  affections, 

661 


662  GENEEAL  COXSIDEEATIONS 

disorders  of  metabolism,  dyspepsia,  gastric  ulcer,  infantile  diarrheas, 
and  many  other  affections. 

The  proper  amount,  variety,  and  quality  of  food  is  one  of  our  most 
important  preventive  measures;  in  fact,  the  vigor  and  success  of  a 
nation  rest^  fundamentally  upon  its  diet.  Diet  is  influenced  by  many 
circumstances,  such  as  availability  of  foods,  economic  status,  habits  and 
prejudice,  knowledge  and  education,  etc.  Instinct  is  not  always  a 
safe  guide.  Finally,  diet  may  lower  the  standard  of  public  health  in 
subtle  ways,  for  there  are  probably  many  degrees  of  malnutrition  not 
recognizable  except  in  their  effects  on  the  individual  over  a  long  period 
of  time.     Diet  may  make  or  mar  public  health. 

How  Foods  May  Be  Injurious  to  Health. — Food  may  affect  health 
in  a  great  variety  of  ways : 

(1)  Natural  Poisons. — Foods  may  be  naturally  poisonous,  as  in  the 
case  of  certain  mushrooms,  some  fish,  or  the  alkaloids  in  various  species 
of  plants. 

(2)  Animal  Parasites. — Foods  may  convey  animal  parasites,  such 
as  trichina  and  tapeworms.  These  parasites,  as  a  rule,  occur  as  ante- 
mortem  infections  in  the  flesh  of  the  food  animal.  Plant  foods  too  may 
carry  the  eggs  or  larvae  of  various  animal  parasites,  some  of  which  are 
capable  of  developing  in  the  human  body. 

(3)  Plant  Parasites. — Foods  usually  contain  bacteria.  Both  animal 
and  vegetable  foods  may  convey  bacteria  pathogenic  for  man.  The  harm- 
ful varieties  are  more  often  found  in  animal  foods  than  upon  plant 
foods.  Milk  often  contains  tubercle  bacilli,  or  streptococci;  sometimes 
diphtheria  bacilli,  or  other  pathogenic  microorganisms.  Typhoid  bacilli 
may  be  conveyed  in  oysters,  or  on  celery,  water  cresses,  etc. 

The  common  cause  of  food  infection,  or  "food  poisoning"  as  it  is 
called,  is  the  Gaertner  bacillus  (B.  enteritidis)  or  one  of  the  other  closely 
allied  members  of  the  colon-typhoid  group    (pages  699,  700). 

(4)  Toxins. — Poisonous  substances  may  develop  in  the  food  as  a 
result  of  bacterial  activity.  The  only  example  we  have  in  this  class  is 
botulism. 

(5)  Putrefactive  Poisons. — This  includes  the  class  of  so-called 
ptomains,  or  decomposition  products  of  protein.  "Ptomain  poisoning" 
is  hypothetical,  and  has  not  been  demonstrated.  The  term  is  a  mis- 
nomer, and  its  popularity  unfortunate.  Infected  food  rather  than  de- 
composed food  is  apt  to  cause  acute  gastro-intestinal  attacks. 

(6)  Special  Poisons. — Foods  may  contain  special  poisons,  as,  for 
example,  solanin  in  sprouted  potatoes,  or  ergot  in  rye.  There  is  a 
substance  in  buckwheat,  actuated  by  light,  which  may  cause  serious 
injury  owing  to  photodynamic  action. 

(7)  Accidental  Poisons. — A  great  variety  of  substances  may  find 
their  way  into  food,  either  through  accident  or  intent,     They  include 


THE  USES  OF  FOOD  nr,3 

arsenic,    lead,    caustic    alkalies,    acids,    alkaloids,    adulterants,    insect 
powders,  etc. 

(8)  Amount. — Injury  is  caused  by  eating  too  much  or  too  little  food; 
thus,  an  excess  of  food  predisposes  to  ol)Csity  and  perhaps  to  arterioscler- 
osis and  degenerative  lesions  of  the  liver  and  kidneys;  an  insuflicient 
amount  undermines  Jiealth.  Undernutrition  in  children  is  common. 
War  edema  is  due  to  uiulerfeeding. 

(9)  Comjposition. — An  unl)alanced  diet  affects  growth,  vigor  and 
health.  Certain  faulty  diets  lead  to  beriberi,  scurvy,  rickets,  pellagra 
and  other  deficiency  diseases.  Goiter  is  due  to  lack  of  iodin  in  water, 
food,  or  both.  An  excessive  fatty  diet  in  infants  leads  to  acidosis.  An 
excess  of  protein  favors  putrefactive  changes.  An  excess  of  carbohydrate 
food  favors  fermentation.  Highly  spiced  and  stimulating  diets  are  irri- 
tating both  to  the  digestive  tube  and  organs  of  excretion ;  drinking  too 
little  water  is  a  common  dietetic  error. 

(10)  Digestion  and  Metabolism. — Foods  otherwise  wholesome  may 
be  injurious  on  account  of  faulty  digestion  or  disturbances  of  metabolism. 
The  common  causes  of  such  troubles  are  eating  too  fast,  improper  mas- 
tication, eating  when  fatigued  or  overheated,  injudicious  combinations, 
especially  unripe  fruits  or  vegetables,  containing  raw  or  partly  cooked 
starch,  etc. 

(11)  Anaplujlaxis. — Certain  persons  have  an  idiosyncrasy  to  par- 
ticular foods.  This  occurs  most  commonly  with  sea-food,  but  also  takes 
place  with  strawberries,  eggs,  tomatoes,  milk,  oatmeal,  and  a  great 
variety  of  substances.  Many  forms  of  protein  in  foods  produce  symptoms 
resembling  anaphylaxis  in  persons  who  are  sensitized;  whereas  the  foods 
themselves  may  be  entirely  wholesome. 


THE  USES  OF  FOOD 

The  two  ultimate  uses  of  all  food  are  to  supply  the  body,  (1)  with 
materials  for  growth  or  renewal,  and  (2)  with  energy  or  the  capacity 
for  doing  work.  The  potential  energy  received  in  a  latent  form  stored 
in  the  various  chemical  combinations  in  foods  is  liberated  as  kinetic 
or  active  energ}^  in  two  chief  forms,  heat  and  motion.  Force  is  the 
manifestation  of  energ)%  and  the  force  developed  by  a  healthy  niian  may 
be  measured  in  foot  pounds.  A  foot  paund  is  the  amount  of  energy- 
expended  or  force  required  to  lift  mechanically  a  weight  of  one  pound 
to  a  height  of  one  foot. 

The  work  of  an  average  man  is  calculated  at  about  2,000,000  foot 
pounds  per  diem.  This  may  exceptionally  be  increased  to  3,000.000  foot 
pounds.  Ordinarily  less  than  one-fifth  of  the  total  energy  of  the  body 
is  expended  in  motion,  and  more  than  four-fifths  in  heat  production. 


664  OEXERAL  OOXSIDEKATIDXS 

Caloric  Value  of  Food. — The  total  intake  of  energy  into  the  body 
is  derived  from  food  plus  the  oxygen  of  the  inspired  air.  The  total 
output  of  energ}^  is  computed  from:  (1)  the  heat  of  combustion  of  the 
unoxidized  ingredients  of  the  urine  and  feces;  (2)  the  energy  liberated 
as  body  heat;  and  (3)  the  energy  of  external  muscular  work,  or  the  work 
of  the  voluntary  muscles. 

^ATiether  alimentary  substances  are  burned  outside  of  the  body  or 
oxidized  within  the  body,  the  resulting  waste  products  are  similar.  Food 
is  good  fuel  if  it  fulfills  two  conditions,  viz. :  easy  assimilation  and 
complete  combustion. 

It  is  not  sufficient  to  know  merely  the  amount  and  calorie  value  of 
the  coal  fed  to  a  furnace,  and  subtract  therefrom  the  amount  of  uncon- 
sumed  ash.  We  must  know  how  much  of  the  heat  generated  has  been 
utilized.     The  food  must  burn  completely  and  without  smoking. 

The  ordinary  articles  of  diet  cannot  be  utilized  without  vitamins. 
The  importance  of  these  '^unknown  dietary  factors"  in  promoting  growth, 
as  well  as  in  the  utilization  of  foods  is  a  recent  discovery. 

Calorie  for  calorie  foods  are  not  interchangeable  so  far  as  nutritive 
value  is  concerned.  The  food  calorimeter  further  gives  no  indication  of 
digestibility.  Concentrated  calories  may  be  quite  as  worthless  for  human 
physiologic  purposes  as  a  piece  of  anthracite  coal. 

Two  methods  may  be  employed  to  study  the  energv'-producing  power 
of  food  in  the  body:  (1)  a  careful  and  prolonged  study  of  subjects  who 
are  allowed  to  follow  their  usual  vocations,  but  whose  food  and  excreta 
are  carefully  measured  and  analyzed;  (2)  the  shorter  method  of  enclos- 
ing a  man  for  a  brief  period,  not  exceeding  a  few  days,  in  a  cabinet 
known  as  a  calorimeter. 

The  unit  of  measurement  is  the  Calorie,  which  is  the  amount  of 
heat  required  to  raise  one  kilogram^  of  water  from  15°  to  16°  C.  This 
equals  3,100  foot  pounds,  or  approximately  the  heat  required  to  raise 
the  temperature  of  one  pound  of  water  4°  F.  Fuel  value  is  a  term 
denoting  the  total  number  of  Calories  derived  from  a  gram  or  pound 
of  any  given  food  substance  if  it  is  completely  combusted  within  the 
body.  The  fuel  values  are  calculated  for  a  given  food  by  the  factors 
of  Eubner  as  follows: 

4.1  Calories  per  gram  of  either  protein  or  carbohydrate, 
9.3  Calories  per  gram  of  fat. 

Atwater  and  Bryant  compute  the  food  factors  as  4  calories  per  gram 
for  proteins  and  carbohydrates  and  8.9  for  fats,  in  a  mixed  diet.    C.  F. 

^  This  is  the  large  Calorie.  The  small  Calorie  is  the  amount  of  heat  re- 
quired to  raise  one  gram,  instead  of  one  kilogram  of  water  from  15°  to  16°  C. 
The  large  Calorie  is  the  one  used  in  studies  of  food  and  metabolism. 


THE  USES  OF  FOOD  665 

Laiigworthy  gives  the  fuel  value  of  the  three  chief  elasses  of  nutrients 
as  follows : 

1  jK)uiid  of  proteiu  yields    1,860  Calories 

1  pound  of  fats   4,"^20  Calories 

1  pound  of  carbohydrates    1,860  Calories 

The  following  are  the  quantities  which  are  generally  accepted  at  the 
present  time  as  a  sufficient  daily  diet  for  a  man  of  average  weight,  doing 
a  moderate  amount  of  muscular  work : 


Weight  in 
Grams 

Weight  in  Oz. 

Energy  Value  in 
Calories 

Protein   

Fat   

Carbohydrates  .  . . 

100 

100 

500 

3.75 

3.75 
18.00 

400 

900 

2,000 

Total  energy  value,  3,300  Calories 

Of  course  the  energy  value  must  be  greater  if  more  work  is  done,  and 
conversely,  so  that  we  may  have  such  figures  as  these : 

Light  work 3,000  Calories 

^Moderate  Avork   3,500  Calories 

Heavy  work 4,000  or  more  Calories 

During  the  World  War  the  U.  S.  ration  in  the  field  was : 

Protein 158  grams 

Fat 200       " 

Carbohydrates 514       " 

Energ}'  value,  4,600  Calories. 

From  a  chemical  standpoint  foods  are  oxidized  or  burned  to  simpler 
compounds  during  the  process  of  digestion  and  metabolism  within  the 
body.  Food  is,  therefore,  fuel.  The  oxygen  to  feed  the  flame  is  mainly 
furnished  by  the  inspired  air.  Exercise  and  active  breathing  of  pure 
fresh  air  is  essential  and  one  of  the  best  stimuli  for  complete  metabolism. 
It  is  the  common  experience  of  all  persons  that  digestion  and  the 
utilization  of  foods  are  favorably  promoted  by  life  in  the  open  air. 

The  value  of  a  diet  does  not  depend  wholly  upon  its  caloric  value 
and  vitamin  content.  The  importance  of  flavors,  spices,  and  the  prep- 
aration of  food  depends  not  alone  upon  the  application  of  chemistry  and 
physics,  but  also  upon  physiology. 

Perhaps  the  greatest  use  of  the  art  of  cooking  is  in  tlie  preparation 
of  dishes  attractive  to  the  palate  and  other  senses.     Appetite  plays  a 


666  aEXEEAL  CONSIDEEATIONS 

ver}'  important  part  in  digestion,  stimulating  the  secretion  of  gastric 
juice,  which  is  produced  in  the  stomach  ready  for  the  reception  of  food. 


CLASSIFICATION  OF  FOODS 

Foods  are  classified  in  various  ways,  but  no  classification  is  complete. 
They  may  be  divided  into  groups,  according  to  their  physical  properties, 
their  source,  their  composition,  and  their  function,  or  the  role  which 
they  perform  in  the  animal  body,  and  their  biologic  properties. 

Physical  Properties. — Foods  are  classed  in  accordance  with  their 
general  physical  properties  first  into  solid,  semisolid,  and  liquid  foods; 
secondly,  into  fibrous,  gelatinous,  starchy,  oleaginous,  crystalline,  and 
albuminous  foods.  Foods  are  also  classed,  as  foods,  beverages,  and  con- 
diments.    Eoughage  is  cellulose  and  other  indigestible  residue. 

Sources. — Foods  may  be  classed  as  to  their  source  primarily  into  (a) 
animal,    (b)    plant,  and    (c)    mineral. 

Animal  foods  consist  of  meat,  fowl,  fish,  shellfish,  crustaceans,  in- 
sects and  their  products  (honey),  eggs,  milk  and  its  products,  animal 
fats,  gelatin. 

The  plant  foods  are  subdivided  into  seeds,  roots  and  tubes,  leaves; 
also  cereals,  vegetables  proper,  fruits,  sugar,  gums,  vegetable  oils 
and  fats. 

The  minerals  are  mainly  calcium,  potassium,  sodium,  chlorin,  fluorin, 
iodin,  magnesium,  phosphorus,  iron,  sulphur,  etc.  They  are  chiefiy 
taken  as  part  of  the  constituents  of  animal  and  plant  foods — except 
sodium  chlorid,  water  and  its  dissolved  salts. 

Chemical  Composition. — The  simplest  chemical  classification  possible 
is  that  ad-^ocated  by  Liebig,  who  was  the  first  to  suggest  a  really  scien- 
tific definition  of  foods.  He  grouped  all  foods  into  two  classes :  nitrogen- 
ous and  non-nitrogenous.  Each  of  these  classes  contains  food  materials 
from  both  the  animal  and  vegetable  kingdoms,  although  the  majority  of 
the  animal  substances  belong  to  the  nitrogenous  and  the  majority  of 
the  vegetable  preparations  to  the  non-nitrogenous  group. 

Nitrogenous  foods  contain  proteins  and  include  gelatinoids  and  albu- 
minoids, substances  which  resemble  albumin.  They  consist  chiefly  of 
the  four  elements:  carbon,  oxygen,  hydrogen,  and  nitrogen,  to  which  a 
small  proportion  of  sulphur  and  phosphorus  is  usually  joined.  The 
nitrogenous  foods  were  regarded  by  Liebig  as  containing  plastic  ele- 
ments; that  is,  they  are  essentially  tissue  builders  or  flesh  formers. 
The  non-nitrogenous  group  Liebig  called  respiratory  or  calorifacient 
foods,  because  their  function  in  the  body  is  largely  to  furnish  fuel  to 
maintain  animal  heat.  It  is  now  known  that  the  non-nitrogenous  foods 
supply  energy  for  muscular  action,   hence  they  are  also   called  force 


CLASSTFTCATIOX   OF  FOODS  667 

producers,  to  distinguish  tlu-in  fntni  the  iiitro;renous  or  tissue  builders. 
This  is  a  {oiivciiieut  distinction.  l)iit  it  must  not  l)e  licld  too  ahsohitely, 
for  tli(>  tissue  liuiMcis  ;iro  used  as  forco  and  heat  producers  as  well. 

Composition  and  Function. — Foods  are  now  ordinarily  classed  as: 
(1)  proteins,  (?)  carbohydrates,  (3)  fats,  (4)  condiments.  (5)  inor- 
ganic  salts,  and   (H)   vitamins. 

1.  I'roieins. — Proteins  build  tissue  and  repair  waste;  to  a  less 
extent  they  serve  as  fuel  to  yield  energy  in  the  forms  of  heat  and  mus- 
cular po'ver.  ^Feats,  milk,  esr^'s.  and  a  few  seeds  such  as  the  pea  and 
bean  are  verv  rich  in  protein,  the  cereal  grains  contain  less  of  this  food 
substance,  whereas  the  tubers  and  vegetables,  especially  in  the  fresh  con- 
dition, contain  but  very  little.  "We  now  know  that  proieins  are  nrA  all 
of  equal  food  value.  We  have  excellent,  good  or  poor  food  proteins  for 
the  formation  of  body  proteins  in  growth.  Hence,  the  qnality  as  well 
as  the  quantity  of  proteins  is  important. 

Soon  after  1900  the  researches  of  Emile  Fischer  revealed  the  great- 
variation  in  the  composition  of  proteins  from  different  sources.  Most 
proteins  can  be  resolved  into  about  17  simple  digestion  products  called 
amino-acids,  and  the  proportions  in.  whicli  these  are  present  in  the 
protein  molecule  varies  greatly  in  proteins  from  different  sources.  All 
or  nearly  all  of  these  digestion  products  appear  to  be  indispensable  con- 
stituents of  an  adequate  diet.  All  natural  foods  contain  several  proteins, 
as  the  extensive  and  valuable  studies  of  Osborne  have  shown.  The 
proteins  of  any  single  foodstuff  may  be  regarded  as  biologically  complete, 
but  their  nutritive  values  differ  greatly,  depending  upon  the  yield  of  the 
several  amino-acids  whicli  can  be  obtained  from  them.  Detinite  quan- 
tities of  at  lec-st  four  of  the  amino-acids — ^lysin,  cystin,  tryptophan  and 
tyrosin — are  essential  for  the  nutrition  of  rats. 

Casein  is  a  complete  protein  because  it  contains  all  of  the  17  or  18 
amino-acids  necessary  to  rebuild  human  protein:  hence,  milk  is  the 
best  source  of  protein.  Meat  protein  is  also  of  good  quality,  but  it  is 
not  an  economical  food.  The  cellular  organs  such  as  liver  and  pancreas 
are  good  sources  of  protein  :  this  is  also  true  of  the  leafy  plants,  although 
the  amount  is  comparatively  small.  Proteins  of  seeds  are  of  poor  quality 
because  they  contain  only  a  few  of  the  amino-acids  necessary  to  rebuild 
human  protein.  It  is  possible  by  combinations  of  incomplete  proteins 
to  obtain  satisfactory'  dietarv  results.  The  great  difference  in  the  b-iologic 
values  of  the  proteins  from  different  sources  is  one  of  the  outstanding 
results  of  modern  research  in  nutrition. 

Although  a  diet  containing  100  grams  of  protein  per  day  is  usually 
recognized  as  satisfactorj-  there  is  evidence  that,  for  healthy  individuals, 
this  quantity  may  be  unnecessarily  large.  Chittendon  has  long  advo- 
cated a  low  protein  diet.  On  the  other  hand.  Atwater's  standard  as  the 
minimum  protein  ration  is  1?5  grams. 


eeS  GENERAL  CONSTDEEATIONS 

2.  Carbohydrates. — The  starchy  or  carbohydrate  foods  are  repre- 
sented by  the  cereals,  the  tubers,  such  as  potatoes,  the  sugars  of  the 
cane,  beet,  fruits,  etc.,  and  glycogen  in  flesh. 

3.  Fats. — Fats  or  oily  foods  are  represented  by  butter,  olive  oil, 
cotton-seed  and  other  oils,  the  fat  of  meat,  the  oil  of  nuts  and  seeds. 
All  vegetables  contain  more  or  less  oily  substances.  The  fats  as  well  as 
the  carbohydrates  serve  as  fuel  to  yield  energy  in  the  form  of  heat  and 
muscular  power. 

Certain  fats  contain  a. vitamin  which  is  indispensable,  whereas  other 
jfats  do  not  contain  this  dietary  essential.  This  vitamin,  known  as  "fat- 
soluble  A,"  is  abundant  in  the  fat  of  milk,  eggs,  and  is  generally  found 
in  other  fats  of  animal  origin,  and  also  in  leafy  plants.  Little  or  none  is 
found  in  lard  and  oils  of  plant  origin  (page  G70).  Fats,  then,  do  not  all 
have  the  same  dietary  value. 

The  chief  worth  of  fat  lies  in  the  ease  with  which  it  is  stored, 
especially  in  the  connective  tissue.  Although  carbohydrate  is  also  stored, 
in  the  form  of  glycogen,  a  kind  of  starch,  in  the  liver  and  muscles,  this 
takes  place  only  to  a  limited  extent.  We  notice  that  both  these  food- 
stuffs, fat  and  carbohydrate,  enable  a  store  of  reserve  material  to  be 
kept  for  use  when  required  to  give  energy.  Fat  has  a  higher  energy 
value,  weight  for  weight,  than  carbohydrate. 

A  very  practical  value  of  fat  consists  in  its  use  in  cooking.  Very 
few  attractive  dishes  can  be  made  without  it,  and  it  is  a  physiologic 
principle  that  food  should  be  eaten  with  relish. 

4.  Condiments. — Among  the  condiments  are  classed :  spices,  such 
as  pepper,  mustard,  cinnamon,  cloves,  etc. ;  also  coffee,  tea,  and  alcoholic 
beverages. 

5.  Inorganic  Salts. — Mineral  matter  or  ash  performs  an  important 
service  in  forming  bone  and  assisting  in  digestion  and  metabolism. 
These  substances  are  ordinarily  not  classed  as  foods ;  however,  life  cannot 
be  maintained  without  them.     This  applies  also  to  the  vitamins. 

Common  organic  or  vegetable  acids,  such  as  citric  from  lemons  and 
oranges,  tartaric  from  grapes,  malic  from  apples,  etc.,  usually  exist  in 
combination  with  the  bases,  calcium,  sodium,  potassium,  etc.,  when 
derived  from  fresh  vegetables  and  fruits.  They  are  indispensable  articles 
of  food,  for  when  absorbed  they  form  carbonates,  which  aid  in  main- 
taining the  alkalinity  of  the  blood. 

If  calcium  phosphate  is  deficient  in  the  food  of  the  young,  growing 
infant,  the  bones  are  poorly  developed  and  so  soft  that  they  yield  to 
the  strain  of  the  weight  of  the  body  and  become  bent,  as  occurs  in 
rickets.  Of  all  foods,  milk  is  the  best  source  of  calcium,  as  it  contains 
this  element  in  abundance  and  in  utilizable  form.  Milk,  however,  is 
deficient  in  iron,  and  therefore  this  fact  must  be  taken  into  account 
when  used  as  a  sole  article  of  diet  for  groAving  children  or  adults. 


CLASSIFICATION   OK   FOODS  G69 

l.cifk  ut"  iodiii  ill  tliL'  (iii't  Icaiis  lo  goiter. 

Lack  of  inorgauif  salts  in  the  food  impoverishes  the  coloring  matter 
of  the  red  hiood  corpuscles  on  which  they  depend  for  their  power  of 
carrying  oxygen  to  the  tissues,  and  anemia  and  other  disorders  result. 
An  ash-free  diet  soon  causes  serious  symptoms. 

The  ordinary  American  diet,  consisting  of  cereals,  bread,  meat,  and 
potatoes  is  rather  lacking  in  mineral  constituents,  especially  calcium. 

Longworthy  gives  the  following  as  the  estimated  amount  of  mineral 
Oiatter  required  per  man  per  day: 

Phosphoric  acid  (PjOi) .^  to  5  grams 

Sulphuric  acid   (SO3) 2  to  3.5  " 

Potassium  oxid 2  to  3  " 

Sodium   oxid 4  to  6  " 

Calcium  oxid 0.7  to  1.0  " 

^fagnesium  oxid 0.;j  to  0.5  " 

Iron   0.0006  to  0.012  " 

Chlorid    6  to  8 

6.  Tifainins. — A'itamius  promote  growth  and  favor  the  utilization 
of  food.  On  account  of  their  importance,  a  brief  summary  of  our 
knowledge  on  this  subject  follows : 

VITAMINS 

Vitamins   are  "accessory   factors*'   in  the   diet   necessary  for  growth 

and  metabolism.     They  are  "unknown  dietary  factors"'  essential  to  life. 

Vitamins  are  remarkable  in   that   exceedingly  small   amounts  produce 

extraordinarih'  great  results — in  this  respect  resembling  enzymes.     Their 

chemical  nature  is  not  known.     Vitamins  are  produced  in  the  plant 

world  even  by  simple  unicellular  cells  such  as  yeast.     They  cannot  be 

elaborated  nor  stored  by  man  or  other  animals.     Gro\\i;h,  nutrition  and 

utilization  of  food  therefore  depend  upon  the  daily  intake  of  vitamins. 

In  this  sense,  we  live  a  hand-to-mouth  existence. 

Eyckman,^  in   1897,  showed  that  polyneuritis  could  be  induced  in 

fowls  by  restricting  them  to  a  diet  of  polished  rice,  and  that  a  diet  of 

undecorticated  rice  would  cur^  fowls  of  this  condition.     In  1907,  Fraser 

and  Stanton  ^  showed  that  the  alcohol  extracts  of  rice  polishings  would 

relieve  experimental  polyneuritis.    In  1911,  Funk*  took  up  the  problem 

and  showed  that  pressed  yeast,  hydrolyzed  with  20  per  cent,  sulphuric 

acid  for  21  hours  retained  its  property  of  curing  polyneuritis  when  given 

to  birds,  from  which  he  concluded  that  in  yeast  and  in  rice  polishings 

there  was  present  a  chemical  entity  of  a  nitrogenous  basic  nature  which 

"•Arch.  f.  path.  Anat.,   etc.,  Berl.,   1907.   148.   52.3;   Arch.  f.   Hxjg.,  Miinchen 
and  Berl..   1906,  58,  150. 

^Lancet,  London.  1910.  73.3:   Philippine  J.  .S'c.  Manila.   1910,  5,  B,  55. 
V.  Physiol,  1911.  43,  .395:  ./.  PhysioL,  1912.  45^  75. 


670  GEXEEAL  COXSIDEEATIOXS 

he  called  "vitamin.''  The  autineuritic  property  of  this  substance  was 
soon  confirmed,  but  its  chemical  nature  was  not  established. 

It  soon  became  evident  that  from  the  standpoint  of  chemical  nomen- 
clature, the  term  vitamin  was  in  some  respects  ill  chosen.  Hopkins  ^ 
suggested  the  term  "accessory  food  substances,"  and  later  McCol- 
lum^  suggested  the  specific  terms  "Fat-soluble  A"  and  "Water-soluble 
B"  to  identify  the  "unknown  dietary  factors." 

Despite  the  fact  that  subsequent  study  has  shown  vitamins  are  not 
amins,  the  term  is  now  established  by  usage. 

Osborne  and  Mendel,^  in  1911,  reported  a  series  of  experiments  in- 
volving the  study  of  the  effect  of  feeding  purified  proteins  and  mixtures 
thereof  with  other  purified  nutriments.  They  called  attention  to  the 
peculiar  effect  upon  growth  induced  by  "protein-free  milk."  A  little 
earlier,  Hopkins  had  called  attention  to  the  fact  that  the  addition  of 
milk  to  purified  food  mixtures  produced  results  out  of  all  'proportion 
to  the  caloric  value  of  the  milk.  In  1912,  McCollum  and  Davis  ^  showed 
that  butter  fat  and  egg  yolk  contain  something  that  stimulates  growth 
and  is  absent  in  lard  and  olive  oil.  Later,  McCollum  and  his  associates 
showed  that  this  principle  "Fat-soluble  A"  is  present  especially  in  milk, 
eggs  and  leafy  vegetables.  Drummond  ^  recently  suggested  that  the 
antiscorbutic  vitamin  be  classified  as  "Water-soluble  C." 

There  are  probably  a  large  number  of  vitamins,  but  only  three  are 
clearly  recognized: 

(1)  "Fat-Soluhle  A"  is  associated  with  certain  fats,  and  is  especially 
abundant  in  milk,  butter,  egg  yolk,  the  fat  of  glandular  organs,  such 
as  the  liver  and  kidneys,  cod  liver  oil,  and  also  in  the  leaves  of  plants. 
The  seeds  of  plants  contain  less,  and  products  derived  from  the  endo- 
sperm of  the  seed  are  very  poor  in  this  substance.  Thus,  such  foods 
as  bolted  flour,  degerminated  corn  meal,  polished  rice,  starch,  glucose 
and  the  sugars  from  milk,  cane  and  beet,  are  practically  free  of  this 
vitamin.  It  is  also  practically  absent  from  lard  and  the  fats  and  oils  of 
vegetable  origin  and  non-pigmented  fats  generally. 

Milk  and  the  green  leaves  of  plants  can  therefore  be  regarded  as 
"protective"  foods,  and  should  never  be  omitted  from  the  diet.  Milk 
is  a  better  protective  food  than  are  the  leaves,  because  it  contains  a 
larger  amount  of  this  vitamin. 

The  specific  result  of  a  lack  of  a  sufficient  amount  of  this  vitamin 
in  the  diet  is  the  development  of  xerophthalmia.  The  eyes  become 
swollen  so  badly  that  they  are  opened  with  difficulty  or  not  at  all.  The 
cornea  becomes  inflamed,   and  unless  the  missing  dietary  essential  is 

V.  Physiol.,  1912.  44,  425. 

"J.  Biol.  Chem.,  1915,  23,  2.31:  J.  Biol.  Chem..  1916,  24,  491. 

''Pub.  Carnegie  Inst.  Bull.,   1911.  Pt.  II.   156. 

V.  Biol.  Chem.,  1913.  15,  167. 

^Lancet,  London,  1918,  2,  482. 


CLASSTFICATIOX  OF   FOODS 


fi71 


TAIII.I';    (>|.     VITA.MI.N.S    IN    1  OOI).- 


Source 


Vitamins 


Fat      I    Water 
Soluble      Soluble 


Anti- 
scorbutic 


Alfalfa    

Animal  tissues. 


Apples     

Banana    

Barley     

Beans  (kidney) 
Beans  (navy).. 
Beans    (soy). .  . 

Blood    

Brain    

Bread  (wliite)  . 
Bread       (whole 

meal) 

Butter    

Cabbage  (fre?h) 
Cabbage  (dried) 

Carrots    

Cauliflower    . .  . 

Celery    

Clover    

Coconut 

Codflsh    

Cod   testes 

Corn      (see 

maize) 
Corn    (Kafir)  .. 
Cotton   seed. .  .  . 
Cream  (see  also 

millf) 

Egg    

Egg  yollc 

Fats,    beef 


+  .+    I     +  + 

Varies    with    the 

tissues 


Fat,    egg 

Fat,   fish 

Fat,   porlc 

Flax   seed  

Heart,    beef.... 

Heart,   pig 

Hemp   seed .... 

Herring 

Honey    

Horse  meat. ... 

Kidney    

Lard    

[-■ettuce    

Liver    

Maize    


+  + 
+  + 
+  + 


+  + 
+ 


+  + 

+  + 
+  +  + 
+  +  + 
present 
in  equal 

parts. 

T 
+  ■•' 
+  + 

+ 

+ 
+  + 

+ 


+  + 


+  + 

—  in 

white. 

+    in 

yellow. 


+  + 

+  4- 

+  +  + 

4-  +  + 

+  + 
+  ? 

+  4- 


+ 
+  + 
+  + 
+  + 
+  + 
+  + 


+  + 
4-  + 


+ 
+ 

4-~  + 

4- 

4- 
4-  + 

4- 
+  ? 

+ 
+  4- 


4-  + 

+  4- 


_        -1-4-4- 


-I-  ? 


-H  -h  -I- 


4- 


+  ? 


+ 


+  ? 
-I-  ? 

9 
-I-'? 


4-  ? 

4-  +"  -f 
+  ? 


Source 


Malt    extract. . . 

Milk    

Millet   seed .... 

Muscle    

Nasal  secretions 

Nectar   

Oats    

Oil,   almond..  . . 

Oil,   cod  liver.  .  | 

Oil,        cotton 
seed    ■ 

Oils,  fish  body. . 

Oil,   olive 

Oils,   vegetable. 

Oleomargarine,  j 
animal    

Oleomargarine, 
vegetable    ... 

Onions    ' 

Oranges    t 

Pancreas    

Parsnip    

Peanuts    

Peas,   dry ' 

Peas,    fresh .... 

Placenta     

Pollen  (corn) . .  j 

Potato    ' 

;  Rice,   polished. . 
j  Rice,       whole 

grain    

jRoe  fish 

I  Rutabaga    ' 

Rye    

Spinach    

Sunflower  seeds 

Suprarenals    ...  I 

Tallow    

Thymus    ! 

Timothy    

Tomato    I 

Wheat    kernel.. 

Wheat   embryo .  ' 

Wheat    endo-| 
sperm    I 

Wheat  bran..  . .  I 

Whey    I 

Yeast    

Yeast  extract . 


Vitamins 


Fat 

W 

ater 

Antl- 

Soluble 

Sol 

uble 

scorbutlc 

A 

B 

C 

•> 

+  -f 

+ 

4 

+ 

-1-  -1- 

-1- 

.t 

9 



+ 

-1- 

-f 

9 
9 

4-4  4 
4-~4- 

+ 
1 

T 


+ 


4- 
4- 

-i- 
-f-  4- 
4-  ? 


4-  -f- 

9 

4- 
4-  4- 


-I- 


4-  -f- 

14-  +  + 

+  + 

+  + 

4- 

-I- 

+  ? 

1    +  + 
4-  4- 


+  -I-  + 

-f  +   4- 

-f — 


4-  4   -(- 


+  4- 


4-  4- 

4-  + 

4- 

+  + 

9 

+  + 

+  + 

4-    4 

9 

9 

9 

4-  4- 

9 

4- 

+ 

-f-  4- 

+  4-  -H 

4- 

-I-  4- 

4-  -h  -I- 

4-4-4 


4- 


supplied,  blindness  speedily  results.  These  results  have  been  obtained  for 
the  most  part  in  rats  fed  upon  an  experimental  diet.  Mellanby's  obser- 
vations on  dogs  show  a  relation  between  Fat-soluble  A  and  rickets.  The 
results  are  accepted  by  the  Medical  Eesearch  Committee  of  Great  Britain, 
and  it  is  now  regarded  by  many  as  an  established  fact  that  the  fat- 
soluble  vitamin  is  synonymous  with  the  antirachitic  vitamin.  Hess 
and  linger  state  that  although  this  vitamin  may  be  a  factor  in  the  eti- 
ology, it  is  not  the  dominant  factor  in  its  pathogenesis. 

(2)   "Water-Soluble  B"  promotes  growth,  and  its  absence  induces 


673 


GENERAL  CONSIDEEATIONS 


polyneuritis  (beriberi).  This  vitamin  is  widely  distributed  in  all  forms 
of  natural  foods  and  can  be  isolated  in  a  concentrated,  but  not  in  a 
pure  form,  by  extraction  with  alcohol  or  water.  It  is  found  in  animals, 
seeds,  leaves  and  tubers,  but  it  is  never  associated  with  fats  or  oils  of 
either  animal  or  plant  origin.  Our  ordinary  foods  all  contain  several 
times  the  amount  of  "Water-soluble  B"  which  is  necessary  for  the  main- 
tenance of  growth  and  health  in  animals. 

(3)  "Water-Soluhle  C"  is  important  in  connection  with  scurvy.  Our 
knowledge  concerning  this  vitamin  is  still  incomplete. 

Whether  each  deficiency  disease,  such  as  pellagra,  rickets,  scurvy,  etc., 
is  caused  by  the  absence  or  lack  of  a  specific  vitamin,  is  not  yet  es- 
tablished. 

It  is  now  well  demonstrated  that  with  the  mixed  diets  ordinarily 
employed  in  Europe  and  America  there  is  no  such  thing  as  a -"vitamin" 
problem. 

The  table  on  page  671  shows  the  occurrence  of  vitamins  in  a  large 
number  of  substances. ^'^  In  the  absence  of  any  satisfactory  quantitative 
measurement  for  vitamin,  it  is  impossible  to  indicate  absolutely  the 
amounts  of  any  type  in  a  given  source.  The  system  adopted  aims  to 
show  the  relative  abundance.  (-| — h  +)  indicates  abundance;  (+  +) 
sufficient  to  require  no  supplement  in  feeding  experiments  where  the 
source  indicated  is  the  sole  supply;  (-]-)  present,  but  not  in  sufficient 
quantity  to  be  relied  upon  as  the  sole  source;  ( — )  means  absent  or  so 
little  as  to  be  negligible;  (?)  undetermined. 

The  question  of  the  effect  of' heat,  acid  and  alkali  upon  vitamins  is 
still  unsettled.  In  a  recent  article  ^^  Drummond  has  published  the  fol- 
lowing summary  of  our  present  knowledge  of  the  subject : 


Vitamin 

StablHty 

Fat-Soluble 
A 

Water-Soluble 
B 

Antiscorbutic 
C 

To  temperature 

To  alkaU 

Stable     at     100"     C. ; 
probably     stable    at 
140°  C. 

Stable    in    cold ;    pos- 
sibly  in    hot. 
Probably    stable. 

Comparatively      stable 
at    100°    C. ;    slowly 
destroyed      at      120" 
C.    and    above. 

Slowly      destroyed      in 
cold  ;  rapidly  in  hot. 

Comparatively  stable. 

Gradually        destroyed 
'  above  50°  C.  ;  rapid- 
ly   destroyed    above 
80"  C. 
Rapid  destruction  even 

To  acids    

in  cold. 
Comparatively      stable 

below  50°    C. 

Most  observers  agree  that  long  boiling  with  acids  does  not  harm 
"Water-soluble  B"  (antineuritic)  vitamin,  and  Osborne  and  Mendel, 
also  McCollum  and  others  hold  that  "Fat-soluble  A"  found  in  butter-fat 
will  sustain  the  temperature  of  live  steam  without  destruction.     On  the 

^'Absts.  Bacteriology,  III,  No.  6,  Dec,   1919,  p.  313. 
^^  Lancet,  London,  1918,  II,  482. 


THE  AMOUNT  OF  FOOD  G73 

other  liaiid.  alkalit's  sci-in  to  l)o  (k'stiiictivr  In  most  \itamiiis.  The  anli- 
scorbuiic  vitamin  (type  C)  is  much  inoic  heat  labile  than  the  "A"  or 
"B,"  and  is  ai)parently  (liminished  in  milk  and  in  snmo  fruits  and 
vegetables  by  drying. 

The  inevitable  sequence  to  the  discovery  of  the  vitamins  was  the 
tendency  to  attribute  to  them  specific  relationshi])  with  many  diseases 
of  unknown  origin.  Thus,  polyneuritis,  pellagra,  sprue,  marasmus, 
scurvy,  rickets,  disturbances  of  growth,  etc.,  presented  problems  which  it 
was  hoped  the  study  of  vitamins  might  solve.  Workers  in  each  field  have 
endeavored  to  secure  evidence  of  the  relation  of  vitamin  to  the  particular 
disease.  The  results  vary  with  the  disease  studied.  Pellagra  and  sprue, 
for  example,  have  not  yet  been  demonstrated  to  be  linked  definitely  with 
vitamin  activity.  Growth,  polyneuritis,  xerophthalmia  and  rickets  have 
been  shown  to  be  directly  related  to  the  activity  of  the  "A"  or  "B"  fac- 
tors. Marasmus  has  shown  some  evidence  of  connection  with  the  two 
vitamins  and  scurvy  has  been  linked  with  the  "C"  vitamin. 

Extensive  studies  on  the  nutritive  efficiency  of  various  diets  and  on 
the  specific  behavior  of  the  dietary  factors  "A"  and  "B"  have  shown 
that  both  are  essential  to  the  normal  growth  of  such  experimental  ani- 
mals as  rats,  swine,  fowls,  etc.,  and  by  analogy  or,  in  a  few  cases  by 
direct  experiment,  to  human  animals.  Hess  has  recently  questioned  the 
necessity  for  the  "A"  type  in  the  development  of  human  infants. 

Many  microscopic  organisms  require  or  utilize  vitamins  for  growth 
and  development,  such  as  yeasts,  meningococcus,  influenza  bacillus, 
typhoid  bacillus,  gonococcus,  pneumococcus  Type  I,  streptococcus  hemo- 
lyticus,  B.  diphtheriae,  B.  pertussis,  soil  organisms,  etc. 


THE  AMOUNT  OF  FOOD 

Excessive  Amounts. — The  amount  of  food  required  varies  greatly 
wath  conditions.  In  civilized  communities,  where  cooking  is  a  fine  art, 
the  number  and  variety  of  food  preparations  are  so  great  that  the  ap- 
petite is  often  stimulated  beyond  the  requirements  of  the  system,  and 
consequently  more  food  may  be  eaten  than  is  necessary  or  desirable  to 
maintain  the  best  bodily  health  and  vigor.  Gluttony  results  in  overde- 
velopment and  overwork  of  the  digestive  apparatus;  the  stomach  and 
bowels  become  enlarged;  the  liver  is  engorged,  and  a  predisposition  is 
established  to  degenerative  changes,  fatty  heart,  etc.  Overeating  is  also 
supposed  to  favor  high  blood  pressure  and  arteriosclerosis.  The  quan- 
tity of  food  required  to  maintain  the  body  in  vigor  varies  with  the 
climate  and  season,  clothing,  occupation,  work,  and  exercise,  the  state  of 
individual  health,  age,  sex,  and  body  weight. 

Both   overeating  and   overdrinking  may   be   temporary   or   chronic. 


674  GENERAL  CONSIDERATIONS 

When  chronic  it  may  lead  to  obesity,  gout,  lithemia,  oxaluria.  It  is 
very  certain  to  cause  congestion  of  the  liver  and  the  condition  known 
as  "biliousness,"  in  which  the  stomach  and  intestines  are  engorged,  con- 
stipation results,  the  tongue  is  heavily  coated,  the  bodily  secretions  are 
altered  in  composition,  the  urine  especially  becomes  overloaded  with 
salts,  the  liver  becomes  congested,  and,  finally,  the  nervous  and  muscular 
systems  are  affected,  which  result  in  the  production  of  headache  and 
feelings  of  fatigue,  lassitude,  drowsiness,  and  mental  stupor.  An  excess 
of  protein  favors  putrefactive  changes  in  the  intestinal  tract;  an  excess 
of  carbohydrates  tends  to  fermentation ;  an  excess  of  fat  leads  to  acidosis, 
especially  in  babies.  Excessive  starch  and  sugars  in  the  diet  may 
serve  as  an  exciting  cause  of  diabetes,  especially  in  persons  who  might 
otherwise  go  through  life  without  developing  the  disease. 

Insufficient  Food. — Starvation  or  asitia  is  a  term  which  technically 
applies  to  the  lack  of  sufficient  food  for  the  maintenance  of  the  body, 
while  inanition  means  the  lack  of  the  assimilation  of  food  by  the  tis- 
sues. When  food  is  completely  withheld,  life  cannot  be  prolonged  be- 
yond six  or  ten  days  in  the  majority  of  instances.  Professional  fasters 
have  gone  41  days  without  anything  but  water.  If  food  is  withheld 
suddenly,  the  sensation  of  hunger  gradually  increases,  becomes  extreme, 
lasts  for  two  or  three  days,  and  slowly  disappears.  It  is  accompanied 
by  a  gnawing  pain  in  the  epigastrium,  which  is  relieved  on  pressure. 
The  pain  may  disappear,  but  it  is  followed  by  a  sensation  of  extreme 
weakness  or  faintness,  which  is  both  local  in  the  stomach  and  general 
throughout  the  body.  Even  though  the  pain  disappears,  the  sensation 
of  hunger  may  occasionally  reassert  itself,  when  all  food  is  withheld, 
until  death,  or  until  the  subject  becomes  insane  or  unconscious. 

Hunger  is  not  always  a  reliable  guide  to  the  need  of  the  system 
for  food.  Some  dyspeptics  are  always  hungry  and  eat  more  than  they 
can  digest.  A  habit  of  rapid  eating  does  not  satisfy  the  sensation  of 
hunger.  More  food  may  be  taken  than  is  necessary,  because  it  has  not 
had  time  to  meet  the  needs  of  the  system  before  the  meal  is  over.  Can- 
non has  shown  that  the  sensations  of  hunger  come  and  go  rhythmically, 
appearing  synchronously  with  the  contractions  of  the  empty  stomach. 

A  reduced  diet  causes  a  lowering  of  basal  metabolism,  influences  the 
sex  instinct  and  its  manifestations.  There  results  a  lessening  of  sex 
interest  and  a   diminution   in  procreative   power.^^ 

Undernourishment. — Recent  studies  have  shown  that  a  large 
percentage  of  growing  children  are  underweight  for  their  height. 
Erom  15  to  40  per  cent.,  and  even  as  high  as  60  per  cent.,  of  school 
children  have  been  found  to  be  undernourished.  The  condition  is 
even  more  prevalent  among  the  children  of  the  well-to-do,  than  those 
of  the  poor.  The  causes  of  undernourishment  are  (1)  physical  de- 
^  Miles,  Jour,  of  Nerv.  and  Mental  Dis.,  49.3.     Mch.,  1919. 


THE  AMOUNT  OF  FOOD  675 

fects,  (2)  lack  of  lioiiic  coiilrol,  (3)  cliroiiic  over-fati^e,  (4)  im- 
proper health  habits,  and  (5)  improper  diet  and  food  habits.  To 
remetly  the  condition  often  recinires  the  cooperation  of  the  parent,  the 
teacher,  the  pbysician  and  tlic  child.     See  also  page  676. 

Famine  and  Pestilence. — The  statement  is  frequently  made  that, 
when  starvation  occurs  upon  a  large  scale,  affecting  a  community  with 
famine,  pestilence  is  sure  to  accompany  it.  Thus,  disease  has  often  been 
rampant  in  Ireland  wlien  the  potatoes  have  failed,  and  in  India  when 
the  grain  su))ply  lias  given  out.  i\ruch  of  the  illness  which  occurred  in 
the  early  history  of  the  Crimea  was  coincident  with  insufficient  food, 
and  it  is  stated  that  in  the  middle  ages  the  ravages  of  pestilential  diseases, 
such  as  typhus,  smallpox,  plague,  etc.,  were  always  worse  in  times  of  gen- 
eral starvation.  The  history  of  epochs  of  famine  in  siege  or  otherwise 
is  always  accompanied  by  outbreaks  of  violence,  for  hunger  begets  ill 
temper,  vice,  and  crime.  This  has  occurred  of  late  years,  notably  in 
Athens,  Florence,  and  London,  and  in  Paris  during  the  Commune. 
There  is,  hoAvever,  no  very  definite  relationship  between  famine  and 
epidemics.  The  "depressed  vitality"  caused  by  insufficient  food  is  not 
the  real  cause  of  epidemics  of  plague,  smallpox,  relapsing  fever,  typhus 
fever,  and  other  pestilential  diseases,  sometimes  called  famine  fevers. 
The  reasons  for  this  have  been  discussed  under  Immunity. 

War  Edema. — The  symptoms  of  war  edema  are  gravitational 
dropsy,  slow  pulse,  low  blood  pressure  and  polyuria.  The  condition 
is  associated  with  prolonged  undernutrition,  due  to  lack  of  calories 
over  a  long  period  of  time.  The  disease  is  therefore  aggravated  by 
cold  and  exertion  and  is  improved  by  rest  and  warmth.  Many  persons 
in  the  war  area  had  a  daily  ration  of  only  about  1400  calories,  con- 
sisting mainly  of  a  coarse  food,  chiefly  carbohydrates,  very  little  pro- 
tein, and  almost  no  fat.  All  the  symptoms  can  be  explained  by  lack 
of  function  of  the  thyroid  gland.  Clinically  the  condition  resembles 
myxedema. 

It  occurred  especially  in  Germany,  Eussia,  Eoumania,  but  also  in 
other  countries  during  the  Great  War.  When  advanced,  the  symptoms 
are  edema  of  legs,  thighs  and  genitalia,  with  some  puffiness  of  the  eye- 
lids. In  bad  cases  there  is  edema  also  of  the  chest  and  abdominal  walls. 
Patients  complain  of  general  weakness  and  pain  in  the  legs.  They  are 
usually  very  apathetic.  There  is  extreme  muscular  weakness  and  marked 
pallor.  The  w^hole  appearance  resembles  the  condition  found  in  chronic 
parenchymatous  nephritis.  Uncomplicated  cases  are  afebrile.  With 
rest  in  bed  and  a  better  ration,  improvement  slowly  takes  place. 

War  edema  is  clearly  the  result  of  underfeeding.  The  ration  respon- 
sible was  low  in  protein  and  almost  fat-free.  Thus,  in  Berlin  the  poorer 
classes  were  reduced  to  a  ration  containing  only  about  50  gi'ams  of 
protein  per  day,  which  is  about  half  the  standard  dietary  observed  in 


676  GENEEAL  COXSIDEEATIOXS 

most  civilized  countries.  The  fats  were  replaced  by  carbohydrates.  The 
ration  was  largely  vegetable  in  origin,  rich  in  cellulose,  devoid  of  stim- 
ulating properties,  and  limited  in  variety.  It  contained  only  about 
1400  calories. 

In  addition  to  war  edema,  other  results  were  traceable  to  the  re- 
stricted diet.  Hernias  and  displacements  of  internal  organs  were  a 
frequent  consequence  of  emaciation.  Lactation  was  unsatisfactory 
among  child-bearing  women.  Gastro-enteric  disorders,  rickets,  and 
other  deficiency  diseases  occurred,  and  delayed  growth  affected  the 
children.  Tuberculosis  increased  its  ravages,  and  decreased  resistance 
to  other  diseases  was  noted. 

TTnderfeeding-  and  Growth. — Failure  to  grow  according  to  normal 
expectations  may  result  from  underfeeding,  from  inappropriate  food, 
or  from  pathological  defects  either  inherited  or  acquired.  Inborn  errors 
of  growth  form  a  special  category  which  falls  outside  the  sphere  of 
nutrition.  Retardation  of  growth  due  to  diets  defective  in  quality  rather 
than  quantity  will  be  discussed  under  "deficiency  diseases.'^  Under- 
feeding per  se  will  retard  or  suppress  growth,  but  Osborne  and  Mendel  ^^ 
have  shown  that  the  capacity  to  grow  is  not  entirely  lost,  but  is  held 
in  reserve  until  it  is  exercised.  Even  when  the  period  of  stunting 
through  underfeeding  is  prolonged  beyond  the  time  when  growth  usually 
ceases,  the  institution  of  a  proper  diet  may  result  in  prompt  resumption 
of  growth  and  apparent  completion  of  its  usual  cycle. 


UNBALANCED  DIETS 

trnbalanced  Diets. — A  balanced  ration  is  one  that  furnishes  the 
optimum  condition  for  the  maintenance  of  vigor  and  the  characteristics 
of  youth;  it  must  promote  growth,  favor  utilization  of  food  and  provide 
for  normal  reproduction.  The  science  of  nutrition  has  emerged  from 
its  simpler  beginnings  into  a  complex  problem  of  great  intricacies.  At- 
tention was  first  called  to  the  importance  of  the  chemical  composition 
of  foods,  and  stress  was  placed  upon  the  importance  of  the  diet  containing 
protein,  carbohydrates  and  fats.  To  this  was  later  added  the  necessity 
of  certain  inorganic  salts.  Xow  we  know  that  not  all  proteins  are 
adequate  for  nutrition,  and  the  fats  also  have  different  dietetic  values. 
The  caloric  value  of  food  was  next  emphasized,  but  it  soon  became 
apparent  that  many  considerations  other  than  fuel  value  make  up  a 
balanced  ration.  Biologic  studies  then  revealed  the  vitamins,  necessary 
for  growth  and  nutrition. 

Some  of  the  factors  which  make  up  a  balanced  diet  are:  sufficient 
calories  to  furnish  heat  and   energy;   inorganic   salts,   especially   iron, 

^Journ.  Biol.  Chem.,  XXIII,  439,  1915. 


THE  DEFICIEN"CY  DISEASES  677 

phosphorus  and  calcium  and  iddiii;  altuiidaiit  quantity  and  variety  of 
foods  containing  all  the  necessary  vitaniins;  some  "ballast"  or  "rough- 
age," that  is,  undigestible  residue  such  as  cellulose.  Furthermore,  a 
balanced  diet  should  provide  approximately  the  same  fuel  value  each 
day.  In  other  words,  we  should  not  have  a  feast  and  upset  our  digestion 
by  overeating  today,  and  have  a  famine  tomorrow,  but  stoke  the  furnace 
regularly,  according  to  its  needs.  Certain  edible  plants  are  toxic  when 
used  in  too  large  abundance,  and  this  must  be  avoided  in  the  diet.  A 
balanced  diet  must  also  take  into  account  the  acid-base  equilibrium. 
Too  much  acid  in  the  diet  draws  on  alkali  reserve,  and  may  reduce  resist- 
ance to  infection  and  cause  injury  in  other  ways.  It  is  plain,  then,  that  a 
balanced  diet  depends  upon  many  factors,  some  of  them  exceedingly  com- 
plex. Our  only  safety  lies  in  a  generous  ration,  varied  as  possible.  A 
wide  variety  provides  a  factor  of  safety.  Growing  children  especially 
jihould  have  a  safe  margin  both  as  to  quantity  and  quality,  for  the  science 
of  nutrition  is  in  its  infancy. 

A  balanced  diet  furthermore  consists  not  only  of  a  liberal  consump- 
tion of  all  the  essential  constituents  of  a  normal  ration,  but  also  includes 
prompt  digestion  and  absorption;  also  normal  metabolism  and  evacua- 
tion of  the  undigested  residue.  Such  a  diet  can  be  attained  only  by 
supplementing  the  seed  products,  tubers,  roots  and  meats,  which  con- 
stitute the  bulk  of  the  diet  of  man,  with  milk  and  the  leafy  vegetables. 
]\rilk  and  the  leafy  vegetables  are  called  protective  foods,  because  they 
are  rich  in  vitamins,  especially  in  fat-soluble  A.  A  person  who  takes 
a  quart  of  milk  a  day  and  some  antiscorbutic  food  will  not  develop  a 
deficiency  disease.  Instinct  is  not  always  a  safe  guide  for  a  balanced 
ration. 

THE  DEFICIENCY  DISEASES 

Unbalanced  diets  give  rise  to  "deficiency  diseases."  Thus,  a  diet 
•  lacking  the  vitamin  known  as  "water-soluble  B"  gives  rise  to  beriberi ; 
xerophthalmia  is  brought  on  by  a  diet  lacking  "fat-soluble  A";  scurvy 
is  due  to  the  lack  of  another  specific  vitamin.  Pellagra  and  rickets 
are  due  to  dietetic  faults,  but  just  what  the  deficiency  consists  of  has  not 
yet  been  unraveled.  Endemic  goiter  is  caused  by  lack  of  iodin  in  the 
water  or  food,  or  both.  War  edema  is  brought  about  by  underfeeding, 
and  especially  by  a  lack  of  protein.  There  are  other  deficiency  diseases 
and  conditions  which  need  further  study. 

The  deficiency  diseases  are  mostly  chronic  and  often  have  a  prolonged 
"period  of  incubation."  In  partially  unbalanced  diets,  the  threshold 
of  clinical  symptoms  may  never  be  reached.  During  this  "prodromal" 
stage,  there  must  be  a  subtle  and  doubtless  serious  effect  on  health  and 
vigor,  resulting  perhaps  in  reduced  resistance  and  impaired  efficiency. 


678  GENEEAL  CONSIDEEATIONS 

BERIBERI 

(Polyneuritis) 

Our  knowledge  of  beriberi  ^*  is  now  sufficient  to  place  this  scourge 
of  the  tropics  among  the  preventable  diseases.  It  is  now  evident  that 
beriberi  is  a  disease  due  to  an  unbalanced  diet,  deficient  in  a  specific 
vitamin,  "water-soluble  B/'  It  is  our  best  known  example  of  a  defi- 
ciency disease.  Most  nations  where  beriberi  prevails  subsist  on  a. 
monotonous  and  one-sided  diet,  made  up  largely  of  polished  rice,  that 
is,  rice  without  the  pericarp.  The  disease  may  be  prevented  or  cured 
by  the  administration  of  rice  bran,  or  other  substances  containing  the 
specific  vitamin. 

The  particular  vitamin  associated  with  beriberi  is  known  as  "anti- 
neuritic  vitamin,^'  or  "water-soluble  B."  A  certain  amount  of  this  ac- 
cessory dietary  factor  must  be  in  the  ration  in  order  to  permit  normal 
growth  of  the  young  and  the  maintenance  of  weight  and  health  of  the 
adult  animal  and  man.  Its  absence  from  the  diet  causes  polyneuritis 
and  other  symptoms  of  beriberi.  This  vitamin  is  very  resistant  to  dry- 
ing, heat,  and  other  influences,  but  may  be  weakened  by  heating  in  the 
presence  of  an  alkali. 

Beriberi,  or  kakke,  is  a  specific  form  of  multiple  peripheral  neuritis 
occurring  endemically,  or  as  an  epidemic,  in  most  tropical  or  subtropical 
climates.  It  is  characterized  clinically  by  disturbances  of  motion,  sensa- 
tion, dropsy,  and  affection  of  the  heart.  The  symptoms  are  attributable 
to  degenerative  changes  in  many  of  the  peripheral  nerves,  being  a  toxic 
neuritis  similar  in  many  respects  to  that  produced  by  alcohol,  arsenic, 
and  other  poisons,  such  as  the  toxon  of  diphtheria.  Three. types  of  the 
disease  are  recognized:  (1)  the  paraplegic,  or  dry;  (2)  the  dropsical, 
or  wet;  and  (3)  the  mixed.  The  course  of  the  disease  is  uncertain;  sud- 
den death  owing  to  involvement  of  the  heart  is  a  common  termination. 
Recovery  is  frequent  and  may  be  complete;  it  is  promoted  by  change  of 
climate  and  improvement  in  the  sanitary  surroundings,  but  is  dependent 
upon  change  to  a  diet  containing  antineuritic  vitamin. 

Many  physicians  who  have  studied  the  subject  in  Japan,  Java,  the 
Philippines,  and  other  countries  have  long  regarded  rice  as  the  impor- 
tant cause  of  the  disease.  In  the  prisons  of  Java  the  proportion  of  cases 
was  1  to  39  when  rice  was  eaten  completely  shelled,  1  to  10,000  when 
the  grain  was  eaten  with  its  pericarp.  In  many  places  the  disease  has 
disappeared  when  the  unshelled  rice  has  been  substituted  for  the  shelled. 

Eijkman,  in  1897,  showed  that  a  disease  resembling  beriberi,  charac- 
terized by  degeneration  of  the  peripheral  nerves,  may  be  produced  in 

"  Vedder,  "Beriberi,"  Wm.  Wood  &  Son,  1913,  contains  a  complete  de- 
scription and  bibliography  of  the  disease. 


THE  DEFICIENCY  DISEASES  679 

fowl  l)y  feedin<j  tliciii  im  white  or  polisheO  rico.  These  results  were  later 
confirmed  hy  (irijiis  (]!)()())  and  HalshofT  Pol  (1004),  hut  a  great  im- 
petus was  iriven  to  the  study  of  the  disease  hy  Fraser  and  Stanton  '^  who, 
in  1!>()!I-11,  eleaily  (hnioiislrateil  that  the  disease  is  brought  about  by 
a  diet  of  wliite  or  polished  rice.  These  investigators  took  300  Japanese 
laborers  into  a  virgin  jungle,  where  they  occupied  new  and  sanitary 
quarters.  After  excluding  the  existence  of  beriberi  by  a  careful  exam- 
ination of  each  person,  they  were  divided  into  two  parties  of  equal  num- 
bers. One  party  received  polished  rice  as  the  staple  article  of  diet,  while 
the  other  party  received  undermilled  rice  with  pericarp.  In  three  months 
beriberi  appeared  among  the  members  of  the  party  receiving  polished 
rice.  When  a  certain  number  of  cases  had  been  noted,  polished  rice  was 
discontinued,  and  thereafter  no  cases  occurred.  .  No  sign  of  the  disease 
appeared  among  the  party  receiving  undermilled  rice.  The  condition- 
were  then  reversed.  The  party  hitherto  ©n  undermilled  rice  were 
given  polished  rice,  and  after  a  somewhat  longer  interval  beriberi 
broke  out  in  this  group  also.  This  outbreak  also  ceased  on  discontinu- 
ing the  issue  of  polished  rice.  Again  no  sign  of  the  disease  appeared 
among  the  control  party  receiving  undermilled  rice.  Place  infection  and 
communicability  were  excluded  by  transferring  individuals  suffering 
from  beriberi  from  one  group  to  the  other  from  time  to  time.  This 
experiment  was  later  repeated  by  Strong  and  Crowell  ^^  in  the  Philip- 
pines with  a  similar  result. 

The  same  changes  in  diet  which  avoid  or  cure  beriberi  in  man  act  in 
a  similar  manner  in  respect  to  polyneuritis  in  fowl.  It  has  now  been 
established  that  polished  rice  causes  beriberi  if  the  diet  is  based  almost 
exclusively  on  this  foodstuff,  but  that,  if  a  sufficient  amount  of  other 
things,  such  as  fresh  meat  and  vegetables,  are  taken  with  it,  the  disease  is 
not  produced.  In  the  polishing  of  rice  the  pericarp  or  cortical  portion 
of  the  grain  is  removed  and  the  embryo  is  discarded.  It  is  evident  that 
these  discarded  portions  contain  some  substance  (vitamin)  essential  to 
a  well-balanced  ration.  It  has  been  found  that  most  of  the  phosphorus 
is  contained  in  the  pericarp.  The  amount  of  phosphorus  is  a  good 
guide  in  the  selection  of  a  beriberi-preventing  rice.  In  the  East,  rice  is 
regarded  as  imsafe  if  it  contains  upon  analysis  a  content  of  less  than  0.35 
per  cent,  of  phosphorus  pentoxid.  It  is  not,  however,  the  absence  of 
the  phosphorus  which  induces  beriberi,  but  the  amount  of  phosphorus,  as 
phosphorus  pentoxid  (PoOg)  may  be  taken  as  an  index  of  the  degree 
to  which  the  rice  has  been  polished. 

Funk,^^  in  1911,  isolated  a  substance  from  rice  polishings  that  pre- 

"  "Studies  from  the  Inst,  of  Med.  Research,  Federated  Malay  States,"  1909, 
No.  10. 

"Philippine  Journ.  Sci..  1912.  VII.  271. 

^''  Jour,  of  Physiol.,  1911.  XLIII.  26:  also  Casimir  Funk.  Die  Yitamine,  Wies- 
baden, 1914. 


680  GENEEAL  CONSIDEEATIONS 

vents  and  cures  polyneuritis  gallinarum.  Funk  obtained  a  crystalline 
organic  base  (C17H20N2O7)  by  precipitation  with  phosphotungstic 
acid,  and  also  by  silver  nitrate  in  the  presence  of  baryta.  The  same  base 
was  subsequently  obtained  from  yeast  and  other  foods.  About  0.02 
gram- of  this  substance  to  pigeons  suffering  with  polyneuritis  affects  a 
rapid  cure.     Funk  calls  the  substance  in  question  "vitamin." 

The  work  of  Eraser  and  Aron,  Breaudat  and  Denier,  Dehaan,  Heiser, 
and  others  leaves  little  doubt  concerning  the  relation  of  polished  rice 
to  beriberi.  Heiser  ^^  reports  that,  prior  to  February,  1910,  polished 
rice  was  commonly  used  in  the  Culion  leper  colony.  The  deaths  from 
all  cases  between  February,  1909,  and  1910  were  898,  of  which  309  were 
due  to  beriberi.  From  February,  1910,  to  February,  1911,  unpolished 
rice  was  used,  and  there  were  369  deaths,  a  reduction  of  over  one-half 
the  death  rate  for  the  previous  year.  It  is  signiiicant  that  there  were 
no  deaths  from  beriberi  during  this  interval  following  the  use 'of  unpol- 
ished rice.  Heiser  further  reports  50  cases  of  beriberi  treated  by  giving 
daily  15  grams  of  rice  polishings.  Improvement  was  noticed  in  all  except 
two  very  advanced  cases.  These  results  have  been  so  striking  that  the 
Philippine  government  has  drafted  a  bill  providing  for  the  general  use 
of  unpolished  rice ;  that  is,  rice  containing  at  least  0.4  per  cent,  of  phos- 
phorus as  phosphorus  pentoxid,  and  the  levying  of  a  tax  upon  polished 
rice  which  makes  its  sale  practically  prohibitive.  Breaudat  and  Denier  ^^ 
at  Saigon,  in  Indo-China,  report  good  results  from  the  prophylactic  use 
of  rice  bran.  Forty  grams  are  administered  daily  in  the  ordinary  food. 
No  case  of  beriberi  developed  among  49  native  soldiers  who  took  bran, 
while  17.4  per  cent,  of  311  controls  developed  the  disease. 

The  prevention  of  beriberi  in  the  Philippine  Islands  based  upon  the 
rice  theory  is  little  short  of  marvelous.  The  disease  has  been  entirely 
eliminated  from  the  Philippine  native  scouts  owing  to  the  reduction  in 
the  amount  of  rice  from  20  to  16  ounces,  a  substitution  of  undermilled 
rice  for  the  polished  article,  and  the  addition  of  a  legume  to  the  dietary. 
In  1908  and  1909  there  were  600  cases  of  beriberi  annually.  In  the 
entire  17  months  since  the  alteration  in  the  ration  went  into  effect  there 
have  been  but  7  cases  of  the  disease;  occasional  cases  may  be  expected, 
owing  to  disobedience  of  instructions. 

Equally  good  results  of  this  character  are  reported  by  Van  Leent,^° 
Yorderman,^^  Fletcher,^^  Highet,^^  Theze,^*  Chamberlain,^^  and  others. 

"JoMr.  A.  M.  A.,  LI,  Apr.  29,  1911,  p.  1237;  PMlipp.  J.  Soi.,  1911,  VI,  1237. 

^A7in.  de  I'lnst.  Pasteur,  Feb.,  1911,  No.  2. 

^°Arch.  de  Med.  Nav.,  Oct.,  1867,  p.  241.  Cong.  Internat.  d.  Sc.  Med.,  Amst., 
1880,  VI,  170,  etc. 

^Onderzoek,  etc.,  of  Java  en  Madoera,  van  Beriberi,  Batavia,  1897. 

^^  Journ.  Trop.  Med.  and  Hyg.,  1909,  XII,  127 ;  also  Lancet,  London,  1907,  I, 
1776,  etc. 

"^PMlipp.  Journ.  Sci.,  1910,  V,  73. 

^Aw.  d'hyg.  et  de  Med.  col,  1910,  XIII,   16. 

''Philipp.  Journ.  Sci.,  1911,  VI,  133. 


THE  DEFICIENCY  DISEASES 


681 


Infantile  bi'riheri  is  also  coniniou  in  the  Pliilippiiics,  and  may  like- 
^vise  be  prevented  and  even  cured  with  rice  hran. 

Rice. — A  gvi\m  of  rice,  after  removal  from  the  husk,  consists  of  three 
parts:  (1)  an  outer  layer  called  the  pericarp,  which  is  a  very  thin  mem- 
hrane.  The  color  of  the  pericarp  varies  in  different  species  of  rice, 
from  white  to  yellow,  through  the  browns  and  reds,  to  almost  black; 
(2)  the  middle  layer,  called  the  subpericarpal  or  aleurone  layer,  which 
is  composed  of  cubical  cells  filled  with  aleurone  and  fat ;  it  contains  very 
few  starch  grains.  Practically  all  of  the  fat,  and  the  greater  part  of  the 
protein  of  the  grain  is  confined  to  this  middle  layer;  the  pericarp  and 


Fig.  74. — Sections  Through  Seeds  of  Eice  (I),  Wheat  (II),  and  Corn  (III), 
Showing  the  Protein  (P)  and  Starch  (S)  of  the  Seeds  and  Their 
Germ  (E)  ;  1,  2  and  3,  The  Seeds  as  Seen  From  the  Outside,  Natural 
Size. 

subpericarp  contain  practically  all  the  phosphorus,  and  also  all  the  vita- 
mins, and  organic  nitrogenous  bases.  (3)  The  bulk  of  the  grain,  which 
consists  of  the  innermost  portion,  is  filled  with  starch  granules.  The 
embryo  is  absent  in  milled  rice. 

Rice  is  first  husked  between  large  horizontal  revolving  stone  disks. 
The  chaff  is  winnowed  out.  This  part  of  the  process  chips  off  only 
a  small  part  of  the  pericarp.  The  grain  is  then  milled  by  means  of  a 
vertical,  revolving  conical  stone,  around  which  is  a  close  fitting  .metal 
gauze  case.  Friction  between  the  stone  and  the  case  rubs  off  the  pericarp 
and  the  aleurone  layer.  The  dust  escaping  is  called  rice  polishing  or 
rice  bran,  which  is  used  in  the  prevention  and  treatment  of  beriberi. 
In  the  so-called  "highly  milled  grades"  of  rice,  such  as  are  commonly 
&eeu  in  the  markets  of  the  world,  all  of  the  pericarp  and  most  of  the 
aleurone  layer  have  been  removed.  The  last  process  in  the  treatment 
of  rice  is  the  polishing  with  buffers  covered  with  long  wooled  sheep  skin. 


682  GENEEAL  CONSIDERATIONS 

This  removes  the  dust,  and  leaves  a  clean,  white  grain.  Talcum  and 
glucose  are  often  added  to  give  a  shiny  surface.  By  undermilled  rice  is  un- 
derstood rice  retaining  a  large  share  of  the  pericarp  and  aleurone  layers. 

Prevention. — The  prevention  of  beriberi  consists  in  substituting  the 
use  of  whole  rice  for  the  polished  grain ;  also  in  improving  the  general 
quality  of  the  food  and  in  providing  for  better  balanced  dietaries,  espe- 
cially adding  articles  containing  vitamins,  such  as  fresh  meat,  vegetables, 
milk,  eggs  and  fruit.  The  prophj^lactic  value  of  rice  polishings  added  to 
the  ordinary  native  diet  must  be  borne  in  mind. 

It  seems  a  simple  thing  to  substitute  undermilled  for  highly  milled 
or  polished  rice,  but  it  will  require  a  long  and  patient  campaign  to  make 
a  change  which  is  utterly  at  variance  with  the  economic  and  social  habits 
of  entire  nations  who  have  for  many  years  considered  the  polished  rice 
as  the  best  quality,  and  generally  purchase  it  by  preference.  Much  may 
be  accomplished  through  taxation  of  the  highly  milled  rice,  through 
education,  and  also,  in  part,  through  law. 

It  should  be  borne  in  mind  that  beriberi  may  be  produced  by  an 
unbalanced  diet  of  other  starchy  substances,  such  as  wheat  flour  (Little 
and  Strong).  Cases  have  occurred  on  the  coast  of  Labrador  from  a  re- 
stricted diet,  consisting  largely  of  wheat  flour.  Wellmann  and  Bass  ^® 
produced  polyneuritis  of  fowls  with  sago  in  20  days ;  boiled  white  pota- 
toes, 24  days;  boiled  milled  rice,  27  days;  cornstarch,  32  days;  white 
flour,  34  days;  corn  grits,  36  days;  oiled  sweet  potatoes,  38  days;  cream 
of  wheat,  39  days;  puffed  rice,  39  days;  macaroni,  40  days.  There  is  no 
danger  of  contracting  beriberi  with  the  varied  diet  customary  in  this 
country  and  Europe. 

There  are  certain  accessory  factors  believed  to  favor  beriberi:  The 
disease  occurs  especially  in  overcrowded  places,  such  as  ships,  jails,  and 
asylums;  during  the  hot  and  moist  seasons;  and  following  exposure  to 
wet.  These  are  to  be  avoided.  Europeans  living  under  good  hygienic 
conditions,  and  enjoying  a  well-balanced  diet,  do  not  contract  the  disease. 

REFERENCES 

Wiley:  "Foods  and  Their  Adulteration."     2nd  Ed.,  Philadelphia,  1911. 

Thompson:     "Practical  Dietetics,"  New  York,  1909. 

Richards  and  Woodman  :  "Air,  Water,  and  Pood  from  a  Sanitary  Stand- 
point."   3rd  Ed.    New  York,  1911. 

Leach:     "Food  Inspection  and  Analysis."     New  York,  1907. 

Parry:     "The   Analysis   of  Food   and   Drugs."     London,   1911. 

TiBBLES :  "Foods :  Their  Origin,  Composition  and  Manufacture."  Chi- 
cago, Med.  Book  Co.,  1912. 

Greenish:  "Microscopical  Examination  of  Foods  and  Drugs."  Philadel- 
phia, 1910. 

^"  Amer.  Jour.  Trop.  Dis.  and  Preventive  Med.,  Aug.  13,  I,  2,  p.  129. 


THE  DEFICIENCY  DISEASES  683 

SCURVY 

(Scorbutus) 

Scurvy  is  a  deficiency  disease  due  to  some  prolonged  error  in  diet, 
particularly  the  lack  of  fresh  food  in  the  ration.  It  is  characterized 
by  debility,  anemia,  a  spongy  condition  of  the  gums  and  a  tendency  to 
hemorrhages.  The  lesions  occur  especially  in  the  bones,  the  blood  vessels 
and  the  blood. 

Scurvy  is  undoubtedly  due  to  some  fault  in  the  diet,  but  just  what 
the  deficiency  consists  of  is  not  certain.  There  is  justification  to  regard 
it  as  due  to  the  lack  of  a  special  vitamin  in  the  diet,  known  as  "Water- 
soluble  C." 

The  disease  has  long  been  a  scourge  of  sailors  and  soldiers.  Fiftj'- 
five  of  the  143  epidemics  analyzed  by  Hirsch  were  during  hostilities.  It 
afi^ected  prisoners  and  troops  in  the  World  War,  especially  on  the 
eastern  front.  In  Mesopotamia  the  British  troops  suffered  owing  to  lack 
of  fresh  food.  The  extent  to  which  scurvy  prevailed  during  the  World 
War  is  summed  up  by  Hess."  It  also  occurs  in  the  civilian  population, 
sometimes  sporadically,  often  endemic.  It  is  still  found  in  Eussia, 
also  among  the  Hungarians,  Bohemians  and  Italians  in  the  mining 
districts  of  Pennsylvania.  Otherwise,  scurvy  is  a  rare  disease  in  the 
United  States,  except  the  infantile  form. 

It  was  discovered  by  Captain  Cook  (1776)  that,  in  order  to  preserve 
the  health  of  his  crew  on  long  voyages,  it  was  necessary  for  them  to 
take  every  opportunity  of  obtaining  fresh  food.  The  passage  in  which 
Captain  Cook  describes  his  experience  is  worth  c|uoting:  "We  came  to  a 
few  places  where  either  the  art  of  man  or  nature  did  not  afford  some 
sort  of  refreshment  or  other,  either  of  the  animal  or  vegetable  kind. 
It  was  my  first  care  to  procure  what  could  be  met  with  of  either  by 
every  means  in  my  power,  and  to  oblige  our  people  to  make  use  thereof, 
both  by  my  example  and  authority;  but  the  benefits  arising  from  such 
refreshments  soon  became  so  obvious  that  I  had  little  occasion  to  employ 
either  the  one  or  the  other.'^ 

Infantile  scurvy  (Barlow's  disease)  occurs  in  babies,  mostly  between 
the  sixth  and  tenth  month,  and  particularly  in  those  not  breast  fed. 
Every  infant  raised  on  sterilized  or  proprietary  foods  for  several  months, 
without  any  fresh  or  ^live"  food,  is  menaced  with  scurvy.  The  disease 
rarely  occurs  in  breast  fed  babies. 

It  has  been  demonstrated  that  there  may  be  pronounced  differ- 
ences in  the  value  of  fresh^  unheated  milks  in  their  antiscorbutic  value, 
depending  on  the  nature  of  the  diet  of  the  cow  or  lactating  woman. 

^  Int.  Jour.  Pub.  Health,  Nov.,  1920,  Vol.  I,  No.  3,  p.  302;  also  Scv/rvy^ 
Past  and  Present,  J.  B.  Lippincott  Cp„  1920, 


G84  GENERAL  COXSIDEEATIOXS 

The  antiscorbutic  substance  is  found  abundantly  in  potatoes,  fruits, 
vegetables,  green  grass  and  other  forage.  Cooked  foods,  with  certain 
exceptions  such  as  tomatoes,  are  of  little  value  and  the  milk  of  a 
mother  whose  diet  consists  largely  of  cooked  or  dried  or  preserved 
foods"  may  not  protect  her  infant  against  this  disease  unless  some  sub- 
stance rich  in  antiscorbutic  properties  be  included.  The  milk  of  ■ 
cows  is  more  effective  as  an  antiscorbutic  food  when  they  are  fed  green 
foods. 

Infantile  scurvy  is  characterized  by  painful  swellings  and  ecchymoses 
about  the  Joints,  especially  the  ankles  and  knees ;  hyperesthesia ;  pseudo- 
paralysis of  the  lower  extremities,  due  to  the  pain  and  hemorrhages; 
spongy,  bleeding  gums;  hemorrhages  from  the  nose,  and  occasionally 
other  mucous  membranes.  In  advanced  cases,  there  is  also  general  weak- 
ness and  marked  aneniia.  Infantile  scurvy  is  often  mistaken  for  rheu- 
matism, infantile  paralysis,  etc. 

When  we  reflect  that  it  usually,  requires  about  six  months  before  a 
case  of  scurvy  reaches  the  threshold  where  it  can  be  recognized  clinically, 
it  is  clear  that  during  this  phase  there  must  be  a  certain  undermining 
of  health.  This  same  condition  doubtless  occurs  in  the  preclinical 
period  of  other  deficiency  diseases.  All  babies  not  breast  fed-  should 
have  orange  juice,  tomato  juice,  or  some  other  antiscorbutic. 

Experimental  Scurvy. — The  classic  experiments  of  Hoist  and  Froe- 
lich  ^^  in  1912  demonstrated  the  symptoms  and  lesions  of  scurvy  in 
guinea-pigs  by  means  of  a  diet  of  cereal  grains.  These  observations 
have  been  repeated  by  Baumann,^''  Jackson,  and  many  others.  It  is  easy 
to  produce  or  prevent  scurvy  in  guinea-pigs,  and  to  cure  it  when  not 
too  far  advanced,  simply  by^the  use  of  antiscorbutic  food. 

While  it  seems  clear  that  scurvy  is  due  to  the  deficiency  in  the  diet 
of  a  specific  food  factor  of  the  vitamin  type,  other  explanations  of  the 
disease  need  consideration.  A  favorite  theory  is  that  the  faulty  diet 
undermines  health  and  thus  permits  infection.  Many  outbreaks  of  a 
disease  resembling  scurvy  during  the  World  War  seemed  to  have  an 
infectious  nature.  The  diagnosis  in  such  cases  is  not  clear,  for  every 
weakening  disease  with  a  tendency  to  hemorrhages  is  not  scurvy.  The 
theory  that  scurvy  is  an  auto-intoxication  will  not  die.  Thus,  McCol- 
lum  and  Pitz  '"  found  in  the  guinea-pigs  which  had  died  of  scurvy, 
that  the  cecum,  which  is  a  very  large  and  very  delicate  pouch  through 

^  Ztschr.  f.  Hyg.  u.    Infektionshrankh.,  1912,  72. 

Theobold  Smith  as  early  as  1895-96  noted  that  "When  guinea-pigs  are  fed 
with  cereals  (it  has  been  observed  for  some  years  in  this  laboratory),  with  bran 
and  oats  mixed,  without  any  grass,  clover  or  succulent  vegetables,  such  as  cab- 
bage, a  peculiar  disease,  chiefly  recognizable  by  subcutaneous  extravasation  of 
blood,  carries  them  off  in  from  four  to  eight  weeks."  "Bacilli  in  Swine  Disease," 
Bureau  of  Animal  Industry,  1898-6. 

"^  Am.  Journ.  Med.  Sci.,  1917,  153,  650. 

^°Journ.  Biol.  Chem.,   1917,  229. 


THE  DEFICIENCY  DISEASES  685 

which  the  food  must  pass  in  going  from  the  small  to  the  large  intestine, 
was  always  packed  with  putrefying  feces.  This  was  soon  disproved  by 
Gwens,  Hart,  Hess,  Mendel,  Stoenbock,  Chick,  Harden  and  others  who 
again  substantiated  the  earlier  view  that  the  disease  is  the  result  of  a 
deficiency  of  some  nutritive  factor  in  the  diet. 

Antiscorbutics. — Certain  foods  possess  the  property  of  preventing 
scurvy.  This  is  probably  due  to  a  special  vitamin.  The  amount  of  this 
unknown  dietary  principle  varies  greatly  in  different  foods. 

The  best  antiscorbutics  are  orange  and  lemon  juice,^^  tomato  juice, 
apples,  onions,  peas,  potato,  spinach,  cabbage,  lettuce  and  the  swede. 
(Table,  page  671.)  Drying  and  iieating  cause  a  certain  amount  of 
deterioration  of  the  antiscorbutic  principle  in  some  of  these  foods. 
Canned  tomatoes,  processed  at  a  high  temperature,  retain  their  prophy- 
lactic properties.     Orange  juice  may  be  boiled  without  injury. 

Cow's  milk  at  best  is  only  moderately  antiscorbutic,  and  this  property 
is  diminished  about  half  by  age,  by  drying,  or  by  pasteurization  (page 
759).     It  is  destroyed  by  oxidation. 

The  prevention  of  scurvy  is  plain,  and  may  be  summed  up  in  two 
words — fresh  food.  Arctic  explorers,  troops,  sailors,  infants  and  others 
on  limited  diets  may  avoid  scurvy  by  the  use  of  orange,  lemon  of  tomato 
juice.  The  antiscorbutic  value  of  cabbage,  lettuce,  the  swede,  onions, 
potatoes,  apples,  spinach  and  fresh  raw  milk  should  be  resorted  to  when 
attainable.  .  ■ 

RICKETS 

(Bliachitis) 

There  can  be  no  doubt  that  rickets  is  a  nutritional  disease,  but  the 
responsible  factors  are  diet  and  hygiene.  It  is  characterized  especially 
by  an  alteration  in  the  growth  of  the  bones.  These  become  enlarged 
at  the  extremities  and  so  soft  that  they  bend  under  the  weight  of  the 
body.  It  is  a  disease  of  the  first  two  years  of  life,  and  is  especially 
prevalent  in  children  in  whose  diet  milk  is  replaced  too  largely  by 
cereals  and  other  vegetable  foods  not  suited  to  the  delicate  digestive 
tract  of  the  young  child.  Predisposing  factors  in  many  cases  are  un- 
doubtedly tuberculosis  and  syphilis.  The  sj^mptoms  develop  gradually. 
Restlessness  and  perspiration  at  night,  great  sensitiveness  of  the  limbs, 
so  that  even  a  light  touch  is  extremely  painful,  are  characteristic  signs 
of  the  disease.  There  are  gastro-intestinal  disturbances,  especially  colic 
and   distention  of  the  intestine  with   gas,   so   that   the   abdomen   pro- 

"  Alice  Hamilton  Smith  of  the  Lister  Institute  has  upset  the  traditional 
faith  in  lime  juice.  It  appears  that  the  juice  used  with  ^ood  effects  in  the 
olden  days  was  in  reality  obtained  from  lemons  and  sweet  limes,  not  from  the 
West  Indian  sour  limes.  The  sour  lime  of  the  West  Indies  {Citrus  medica- 
acida)  has  only  one-quarter  the  antiscorbutic  value  of  the  lemon  (Citrus  medica- 
limonum).    Lancet,  2,  725,  Nov.  30,  1918. 


686  GENERAL  COIsrSIDEllATIONS 

trudes.  The  bones  become  thickened,  and  nodules  develop  at  the  junc- 
tures of  the  ribs  with  the  costal  cartilages,  forming  the  characteristic 
"beaded"  ribs.  There  is  defective  ossification  of  the  skull;  the  teeth 
appear  later  than  normal  and  in  unusual  order.  Various  deformities 
of  the  head,  spine,  chest  and  limbs  result  as  the  child  develops,  Ee- 
covery  with  deformity  is  of  frequent  occurrence. 

Eickets  is  a  national  public  health  problem  in  every  country.  It 
is  a  world  scourge  preventing  the  normal  development  of  the  young, 
leaving  them  damaged  not  only  in  their  bones,  but  also  in  their  mental 
and  moral  faculties.  It  is  particularly  marked  among  the  poor  of  large 
cities,  who  are  ill  fed  and  badly  housed. 

While  the  only  important  lesions  are  found  in  the  bones,  it  is  a 
very  complex  pathologic  process,  the  result  of  disturbed  metabolism, 
which  affects  nearly  all  the  structures  and  organs  of  the  body.  Eickets 
is  a  chronic  nutritional  disorder. 

The  cause  of  rickets  is  closely  related  to  lack  of  sunlight  and  bad 
hygienic  surroundings.  Artificially  fed  children  are  much  more  prone 
to  the  disease,  especially  those  with  faulty  feeding.  The  diet  of  chil- 
dren who  develop  rickets  is  most  frequently  deficient  in  fat  and  often 
at  the  same  time  in  protein,  while  it  is  apt  to  contain  an  excess  of  carbo- 
hydrate. Eickets  is  due  to  a  lack  of  Fat-soluble  A  and  to  bad  hygiene, 
especially  lack  of  sunlight  (ultra-violet  rays).  Both  these  factors  explain 
the  seasonal  prevalence  of  the  disease.  Cod-liver  oil  is  a  specific  preven- 
tive and  cure. 

PELLAGRA 

Pellagra  is  included  among  the  diseases  associated  with  food,  for 
the  evidence  indicates  that  it  is  caused  by  a  deficient  diet  of  some  sort. 
The  disease  was  long  regarded  as  an  example  of  a  food  intoxication 
caused  by  some  toxicogenic  saprophyte  growing  in  spoiled  corn.  Some 
investigators  still  look  upon  pellagra  as  an  infection;  and  insects 
{Simulium  and  Stomoxys)  have  been  accused  of  its  transmission. 

Pellagra  usually  runs  a  chronic  course,  with  acute  exacerbations, 
which  commonly  occur  in  the  spring  and  at  times  also  in  the  fall  of  the 
year.  The  disease  sometimes  runs  an  acute  and  rapidly  fatal  course. 
The  development  seems  to  be  more  rapid  and  grave  in  adults  than  in 
children.  The  "poison,"  whatever  its  nature,  produces  toxic  and  trophic 
manifestations.  The  triad  of  symptoms  are:  (1)  digestive  disturb- 
ances, (2)  erythema,  and  (3)  nervous  disturbances.  The  final  scene 
usually  includes  profound  cachexia,  great  muscular  weakness,  and  at 
times  insanity. 

Pellagra  is  a  preventable  disease  in  which  the  social  conditions  loom 
large;  it  is  especially  prevalent  where  faulty  diet  combined  with  pov- 


THE  DEFICIENCY  DISEASES  687 

erty,  overcrowd iiisj^,  and  misery  prevail.  It  occurs  both  sporadically  and 
endemically. 

The  disease  was  first  recognized  in  America  in  1804  by  Dr.  Gray, 
of  Utica,  New  York,  and  by  Dr.  Tyler,  of  Somerville,  Mass.,  who 
each  reported  a  case  of  probable  pellagra.  It  was  overlooked  until 
1906-1907,  when  Searcy  reported  an  epidemic  in  the  Alabama  Insane 
Asylum.  In  the  same  year  (1907)  Babcock's  article  on  the  cases  in  the 
State  Insane  Asylum  of  Columbia,  South  Carolina,  aroused  our  present 
revival  of  interest  in  the  disease.  In  1908  Wood  and  Lavinder  found 
four  cases  in  Wilmington.  North  Carolina.  Since  then  a  flood  of  cases 
have  come  to  light  all  over  the  country,  especially  in  the  south ;  out- 
breaks, however,  occur  as  far  north  as  Peoria,  Illinois,  where  258  well- 
marked  cases  out  of  2,200  inmates  were  discovered  in  the  State  Hos- 
pital for  the  Insane.  Lavinder  estimated  that  in  1910  there  were  be- 
tween 25,.000  and  50,000  pellagrins  in  the  United  States.  Goldberger 
estimates  that  in  1917  fully  125.000  people  were  attacked  with  pellagra 
in  the  states  south  of  the  Potomac  and  Ohio  rivers. 

The  disease  appeared  in  Italy  about  1750,  but  was  first  described 
there  in  1771  by  Frapolli,  of  Milan,  who  applied  the  name  "pellagra" 
(Italian  pelle,  skin,  and  agra,  rough).  Marzari  in  1810  first  called 
attention  to  the  relation  between  maize  and  pellagra.  In  ISi-t  Balar- 
dini  first  suggested  the  theory  that  the  disease  might  be  due  to  spoiled 
maize,  that  is,  maize  which  had  undergone  fermentative  change  by 
reason  of  the  growth  of  fungi  on  the  grain.  At  present  pellagra  is 
most  prevalent  in  northern  and  central  Italy  and  in  Eoumania.  Triiler 
states  that  in  1906  there  were  30,000  pellagrins  in  Eoumania;  in  cer- 
tain parts  of  Italy  as  much  as  30  to  50  per  cent,  of  the  population  have 
the  disease;  in  1899  there  were  nearly  73,000  sick  with  the  disease  in 
all  Italy,  this  being  upward  of  10  per  thousand  of  the  rural  population. 
The  disease  also  occurs  in  Spain,  Corfu,  Asia  Minor,  Austria,  Servia, 
Bulgaria,  Egj-pt,  and  occasionally  in  India,  Africa,  the  West  Indies, 
Mexico  and  South  America. 

As  preventive  measures  must  be  based,  entirely  upon  our  conception 
of  the  etiologj'  of  the  disease,  it  is  necessary  to  consider  briefly  some 
of  the  views  upon  this  subject.  Until  recently  most  students  of  the  dis- 
ease considered  pellagra  to  be  an  intoxication  due  to  using  Indian  corn 
(maize)  as  a  food,  which,  under  the  influence  of  some  parasitic-  growth 
(bacteria  or  fungus),  has  undergone  certain  changes  with  a  production 
of  one  or  more  toxic  substances.  Lombroso,  who  studied  this  subject 
for  years,  made  alcoholic  and  watery  extracts  from  spoiled  maize  and 
obtained  chemical  substances  of  an  undetermined  nature,  which  were 
given  to  men  and  animals  with  the  production  of  symptoms  analogous 
to  pellagra.  This  work  has  not  been  confirmed  and  furthermore  Lom- 
broso's  interpretation  is  doubtful. 


688  GENEEAL  COXSIDEEATIOJ^S 

With  regard  to  the  parasites  found  on  maize,  it  may  be  said  that 
the  varieties  are  numerous,  and  no  single  one  seems  to  be  constant  enough 
to  be  rated  as  the  definite  causative  agent.  Ceni  incriminated  the  Asper- 
gillus fumigatus  as  the  cause  of  the  maniacal  form  of  pellagra,  and  the 
Aspergillus  flavus  as  the  cause  of  the  depressive  form.  These  molds 
have  resisting  spores  which  withstand  heat,  hence  ordinary  cooking  is 
not  sufficient  to  destroy  them.  The  Bacterium  maydis  has  also  been  asso- 
ciated with  the  disease.  Lombroso,  as  a  result  of  his  studies,  maintained 
that  pellagra  is  due  to  a  poison  (toxin)  developed  in  maize  by  sapro- 
phytic microorganisms  (molds  or  bacteria),  in  themselves  harmless  to 
man. 

Other  views  concerning  the  nature  of  pellagra  are :  that  it  is  an  auto- 
intoxication, the  poisonous  substances  being  produced  in  the  bowels  as  a 
result  of  the  constant  and  almost  exclusive  diet  of  corn,  which  produces 
certain  changes  in  the  intestinal  flora,  and  the  production  of  poisonous 
substances.  A  somewhat  similar  view  is  that  the  disease  is  an  intestinal 
mycosis,  the  offending  microorganisms  being  eaten  with  corn  and  coloniz- 
ing in  the  intestinal  tract.  Others  regard  the  disease  as  of  an  infectious 
nature,  and  several  parasites  have  been  reported  in  the  blood  and  organs. 
In  France  especially  the  idea  has  been  brought  forward  that  pellagra  is 
not  a  definite  morbid  entity  at  all,  but  a  symptom-complex  sometimes 
observed  in  alcoholics  and  cachectic  states  of  diverse  origin,  the  erythema 
being  regarded  only  as  a  common  solar  erythema.  Sambon,  as  the  result 
of  epidemiological  studies,  brought  forward  (1905  and  again  recently) 
the  view  that  pellagra  is  an  insect-borne  disease,  and  incriminates  the 
Simulium  reptans. 

Eaubitschek  ^^  recently  brings  forward  evidence  that  pellagra  depends 
upon  some  noxious  substance  (noxe)  activated  by  the  action  of  sunlight. 
This  is  the  photodynamic  theory,  and  corresponds  to  the  action  of  light 
upon  a  photographic  negative.  It  is  suggestive  that  the  skin  lesions  in 
pellagra  are  mainly  confined  to  the  exposed  surfaces.  There  is  also  a  sub- 
stance in  buckwheat  poisoning  (fagopyrismus)  that  affects  animals 
exposed  to  the  light,  but  not  those  kept  in  the  dark. 

The  Thompson-^IcFadden  Pellagra  Commission,  consisting  of  Siler, 
Garrison  and  MacXeal,  believe  that  pellagra  is  a  communicable  infec- 
tion and  is  in  some  way  associated  with  unsanitary  methods  of  sewage 
disposal.  They  found  that  the  immediate  results  of  hygienic  and  dietetic 
treatment  in  adults  have  been  good,  but  after  returning  to  former  condi- 
tions of  environment  most  of  the  cases  have  recurred. 

Goldberger  ^^  on  the  other  hand  regards  pellagra  as  a  disease  due  to 
a  dietetic  fault.     Goldberger  insists  that  pellagra  is  not  a  communicable 

^Berliner  Jclin.  Wochensi,  Vol.  XXIII,  No.  26,  June,  1910. 

^Journal  American  Medical  Association,  February  12.  1916,  LXVI,  p.  471: 
also,  P.  E.  Reports,  October  23,  1914;  Xovember  12,  1915  -.  October  22,  191.5  :  ^^larch 
19.  1920 


THE  DEFICIENCY  DISEASES  •     689 

disease,  but  is  essentially  of  dietary  origin;  that  it  is  (Icpeiidoiit  on 
some  yet  iindeterniinod  fault  in  diet,  which  fault  may  Ije  (-•(•nvctcd  by 
the  addition,  in  suflicicnt  amount,  of  fresh  animal  protein  foods,  espe- 
cially milk.  Pellagra  never  develops  in  those  consuming  a  mixed,  well- 
balanced  and  varied  diet. 

Among  the  people  in  those  districts  where  there  is  a  high  incidence 
of  pellagra  in  the  spring  and  summer  months,  it  has  been  shown  that 
their  winter  diets  are  composed  largely  of  seeds  and  seed  products  and 
that  the  amounts  of  leafy  vegetables,  milk,  eggs  and  meat,  are  very 
small,  or  are  entirely  absent,  for  varying  periods. 

Goldberger  produced  pellagra  in  six  out  of  eleven  volunteer  con- 
victs in  a  camp  at  Jackson,  Mississippi,  as  a  result  of  a  one-sided  diet, 
consisting  mainly  of  carbohydrates  (cereals).  The  first  typical  derma- 
titis appeared  five  months  after  the  beginning  of  the  restricted  diet. 
Other  manifestations  included  nervous  and  gastric  symptoms.  Xone 
of  the  controls  became  pellagrous.  Still  more  striking  is  the  evidence 
ol)tained  by  Goldberger  in  preventing  the  recurrence  of  pellagra  in  or- 
phan asylums  and  in  groups  of  insane  pellagrins  in  an  institution  in 
the  south  by  introducing  a  varied  and  better  balanced  diet,  all  other 
conditions  remaining  the  same.  Furthermore,  a  number  of  clinicians 
report  that  pellagra,  if  not  too  far  advanced,  may  be  cured  upon  the 
assumption  that  it  is  produced  through  dietary  faults.  It  is  scarcely 
necessary  to  look  further  for  the  cause  of  a  disease  that  may  be  produced 
by  a  restricted  diet,  prevented  and  cured  by  a  proper  diet.  I  believe 
Goldberger  has  proved  his  case  and  that  his  work  stands  as  one  of 
the  achievements  in  preventive  medicine. 

Pellagra,   beriberi   and   scurvy  are  evidently  closely  allied   diseases. 

Corn. — In  Europe  pellagra  was  long  associated  with  the  consumption 
of  spoiled  maize  as  the  chief  article  of  diet,  but  it  is  now  known  that  the 
eating  of  this  grain  has  nothing  whatever  to  do  with  its  causation.  The 
fact  remains  that  it  constitutes  a  large  portion  of  the  faulty  dietary  of 
many  persons  who  develop  the  disease.  A  consideration  of  this  im- 
portant grain  is  here  given  on  account  of  its  public-health  importance. 

Maize  or  Indian  corn  is  a  native  of  the  Western  Hemisphere  and  was 
cultivated  by  most  of  the  northern  and  western  tribes  of  North  Ameri- 
can Indians  before  Columbus  reached  these  shores.  The  importance  of 
the  corn  crop  today  may  be  gathered  from  the  fact  that,  according  to 
the  census  of  1900,  almost  one-third  of  all  the  land  under  cultivation  in 
the  United  States  was  devoted  to  corn.  It  was  grown  on  88.6  per  cent, 
of  all  the  farms  in  the  country  in  the  crop  for  1889.  The  value  of  the 
annual  crop  now  exceeds  a  billion  dollars.  Corn  contains  24.7  per  cent, 
of  water.  The  water-free  material  consists  of  12.7  per  cent,  proteins, 
4.3  per  cent,  fat,  79.3  per  cent,  starch,  sugar,  etc.,  2  per  cent,  crude  fiber, 
and  1.7  per  cent,  of  mineral  matters.     The  several  nutrient  substances 


C90  GENEEAL  CONSIDERATIONS 

in  corn  and  other  common  cereals  are  much  the  same;  the  individual 
compounds,  however,  making  up  these  groups,  differ  considerably. 

The  kernel  (see  Fig.  74)  or  seed,  it  must  be  remembered,  is  not 
inert,  but  a  living  thing  which,  under  favorable  conditions,  will  develop 
into  a  new  plant,  and  each  part  of  it  is  made  up  of  cells  especially  fitted 
for  a  particular  role  in  this  process  of  reproduction.  Eoughly  speaking, 
a  seed  consists  of  three  divisions :  the  skin,  the  germ,  and  the  endosperm. 
It  is  a  well-known  fact  that  corn,  when  allowed  to  ripen  before  it  is 
taken  from  the  stalk,  keeps  much  better  than  immature  corn.  It  is 
certain  that  protective  substances  (antibodies)  are  developed  in  the 
kernel  which  retard  the  growth  of  bacteria  and  molds.  Moist  corn 
kept  warm  spoils  readily,  whereas  corn  once  thoroughly  dried  is  proof 
against  serious  fermentative  changes. 

The  prevalence  of  pellagra  in  our  Southern  States  has  been  at- 
tributed to  the  fact  that  during  the  past  decade  or  two  the  corn  belt 
has  gradually  been  pushed  farther  and  farther  north.  This  means  that 
it  is  often  harvested  before  it  is  mature,  and  the  chances  of  its  spoiling 
are  favored  in  transporting  it  to  our  southland  in  a  moist  condition,  A 
carload  of  corn  starting  from  the  Great  Lakes  may  ferment  and  become 
so  overheated  on  its  journey  south  that  occasionally  it  catches  fire  spon- 
taneously. These  facts  have  been  given  to  account  for  the  supposed 
increase  in  pellagra  in  our  southern  cities. 

The  tests  for  spoiled  corn  are  not  entirely  satisfactory.  They  may  be 
divided  into  physical,  biological,  and  chemical  tests.  The  physical  test 
consists  mainly  in  the  luster,  the  absence  of  molds,  the  odor,  and  the 
taste.  The  biological  test  consists  in  planting  the  corn ;  from  90  to  95 
per  cent,  should  germinate.  The  chemical  test  includes  among  other 
determinations  the  proportion  of  ash  after  burning,  and  Gosio's  phenolic 
reaction  with  ferric  chlorid.  A  green  purple  color  with  this  reagent 
indicates   fermentation,    with    the    production    of   phenolic    compounds. 

Spoiled  corn  may  be  renovated  by  polishing  and  then  heating,  to 
prevent  further  growth  of  molds.  It  is  difficult  to  detect  renovated 
corn  by  inspection  alone,  but  the  biological  test  will  disclose  whether 
or  not  it  has  been  heated.  The  practice  of  renovating  corn  should 
either  be  prohibited  or  be  placed  under  strict  official  control. 

Prevention  of  Pellagra. — The  line  along  which  pellagra  prophylaxis 
is  planned  depends  entirely  upon  our  conception  of  the  disease.  As 
pellagra  prevails  especially  among  the  poor,  but  particularly  the  igno- 
rant with  defective  dietaries,  it  at  once  becomes  evident  that  economic 
and  social  improvements  are  an  important  part  of  the  program.  Pro- 
phylaxis spells  prosperity  in  this  disease  as  in  others.  In  a  study  of 
cotton  mill  villages  during  1916,  Goldberger  ^*  found  that,  in  general, 
pellagra  incidence  varied  inversely  according  to  family  income. 

^PuUic  Health  Reports,  Nov.  12,  1920,  XXXV,  46,  p.  2673, 


THE  DEFICIENCY  DISEASES  691 

In  accordance  with  Goldberger's  views  pellagra  may  be  prevented 
and  even  eradicated  by  sii])stitiiting  a  mixed,  well-balanced,  varied  diet 
for  the  restricted,  one-sided  diet  so  common  in  pellagrous  communities. 
Emphasis  should  be  laid  upon  a  larger  proportion  of  the  fresh  animal 
protein  foods,  such  as  milk,  lean  meat,  eggs,  and  green  vegetables,  such 
as  snap  beans,  turnip  greens,  spinach  and  the  like. 

Goldberger  suggests  the  following  as  a  sample  of  a  minimum  pellagra- 
preventing  bill  of  fare  arranged  to  suit  the  dietary  habits  of  the  people 
among  whom  the  disease  is  most  prevalent  in  the  South  : 

PELLAGRA-PREVEXTING    BILL    OF    FARE 

Breakfast 
Sweet  milk,  daily. 

Boiled  oatmeal  with  butter  or  with  milk  every  other  day. 
Boiled  hominy  grits  or  mush  with  a  meat  gravy  or  with  milk  every 
other  day. 

Light  bread  or  biscuit  (one-fourth  soy-bean  meal),  with  butter,  daily. 

Dinner 

A  meat  dish  (beefstew.  hash,  or  pot  roast,  ham  or  shoulder  of  pork, 
boiled  or  roast  fowl,  boiled  or  fried  fish,  or  creamed  salmon  or  codfish 
cakes,  etc.),  at  least  every  other  day. 

Macaroni  with  cheese,  once  a  week. 

Dried  beans  (boiled  cowpeas  with  or  without  a  little  meat,  baked  or 
boiled  soya  beans  with  or  without  a  little  meat),  two  or  three  times  a 
week. 

Potatoes  (Irish  or  sweet),  four  or  five  times  a  week. 

Rice,  two  or  three  times  a  week,  on  days  with  the  meat  stew  or  the 
beans. 

Green  vegetables  (cabbage,  collards,  turnip  greens,  spinach,  snap 
beans  or  okra),  three  or  four  times  a  week. 

Corn  bread  (one-fifth  soy-bean  meal),  daily. 

Buttermilk,  daily. 

Supper 

Light  bread  or  biscuit  (one-fourth  soy-bean  meal),  daily. 

Butter,  daily. 

Milk  (sweet  or  buttermilk),  daily. 

Stewed  fruit  (apples,  peaches,  prunes,  apricots),  three  or  four  times 
a  week,  on  days  when  there  is  no  green  vegetable  for  dinner. 

Peanut  butter,  once  or  twice  a  week. 

Sirup,  once  or  twice  a  week. 

The  Italian  struggle  culminated  in  the  law  of  1902  for  "the  pre- 
vention and  cure  of  pellagra,''  which  was  inspired  by  Lombroso's  views. 


692  GENERAL  CONSIDERATIONS 

The  Italian  measures  may  be  summarized  as  follows:  those  aimed  at 
the  cure  of  the  disease  are  a  free  distribution  of  salt  (a  government 
monopoly  in  Italy),  the  distribution  of-  food  either  at  the  homes  of 
the  patients  or  through  sanitary  stations,  and  the  treatment  of  severe 
cases  in  hospitals  for  pellagrins  and  in  insane  asylums.  The  prophy- 
lactic measures  are  mainly  directed  against  the  use  of  spoiled  corn  as 
an  article  of  food.  They  comprise  a  census  of  the  disease  and  a  report 
of  all  cases;  the  exchange  of  good  corn  for  spoiled  corn;  desiccating 
plants;  cheap  cooperative  kitchens;  the  improvement  of  agriculture; 
and  the  education  of  the  people.  The  corn  is  inspected  by  experts  and  is 
submitted  to  certain  tests.  If  found  spoiled,  its  sale  for  food  is  pro- 
hibited. 

The  supposition  that  the  ingestion  of  good  or  spoiled  maize  is  an 
essential  cause  of  pellagra  is  not  supported  by  the  studies  of  the  Thomp- 
son-McFadden  Pellagra  Commission. ^^  They  believe  that  pellagra  is,  in 
all  probability,  a  specific  infectious. disease  communicable  from  person 
to  person  by  means  at  present  unknown.  The  Commission  discovered 
no  evidence  incriminating  flies  of  the  genus  Simulium,  and  state  that  if 
pellagra  is  distributed  by  a  blood-sucking  insect,  Stomoxys  calcitrans 
would  appear  to  be  the  most  probable  carrier.  The  Commission  is  in- 
clined to  regard  intimate  association  in  the  household,  and  the  con- 
tamination of  food  with  the  excretions  of  pellagrins  as  possible  modes 
of  distribution  of  the  disease.  They  claim  to  have  eradicated  pellagra 
from  a  milk  village  in  South  Carolina  by  substituting  a  water  carriage 
sewerage  system  for  surface  privies. 

In  my  opinion,  Goldberger's  views  of  pellagra  are  correct.  The 
disease  may  be  prevented,  produced,  and  even  cured,  if  not  too  far 
advanced,  in  accordance  with  the  view  that  it  is  caused  by  a  faulty 
dietary.  Before  pellagra  is  eradicated,  it  will  mean  general  education 
concerning  balanced  diets  and  general  prosperity  sufficient  to  purchase 
the  necessary  articles  making  up  such  a  diet. 


FOOD  POISONING  ^^ 

General  Considerations.— There  are  two  well  recognized  causes  of 
food  poisoning.  (1)  Food  infection,  caused  by  Bacillus  enteritidis,  or 
closely  allied  microorganisms.     Bacteria  other  than  the  Gaertner  group 

^=  Siler,  J.  F.,  Garrison,  P.  E.,  and  MacNeal,  W.  J. :  "Pellagra.  A  Summary 
of  the  First  Progress  Report  of  the  Thompson-McFadden  Pellagra  Commission." 
J.  A.  M.  A.,  Jan.  3,  1914,  LXII,  1,  p.  8. 

=^  Food  "poisoning"  is  not  a  good  term,  for  almost  all  cases  are  infections  or 
intoxications.  The  phrase  "food  poisoning"  includes  all  instances  of  acute  food 
injury  and  is  accepted  because  it  has  become  current  in  the  literature. 


FOOD  rOISONING  693 

of  bacilli  are  suspected  of  causing  food  poisoning,  but  the  relationship 
has  not  been  established. 

The  first  important  landmark  in  the  bacteriological  investigation  of 
food  poisoning  was  the  isolation  by  Gaertner  in  1888  of  Bacillus  enter- 
itidis  from  an  outbreak  at  Frankenhausen.  The  bacillus  was  isolated 
both  from  the  fatal  case  and  from  the  organs  of  the  cow,  killed  on 
account  of  enteritis,  the  consumption  of  whose  meat  caused  the  outbreak. 
(2)  Food  Intoxication  due  to  toxins  preformed  in  the  food.  Botu- 
lism is  the  only  known  example  in  this  class.  Other  bacteria  may  pro- 
duce toxins  in  food,  but  none  of  these  have  been  demonstrated  to  be 
poisonous  by  the  mouth. 

There  is  a  great  clinical  difference  between  these  two  classes  of 
food  poisoning.  Food  infection  is  an  acute  disease  characterized  by 
nausea,  vomiting,  cramps  and  diarrhea.,  and  fever.  Botulism  is  char- 
acterized by  nervous  symptoms,  paralysis,  constipation  and  no  fever. 
The  symptoms  vary  greatly  in  severity.  The  mortality  of  food  infec- 
tions is  rarely  over  1  per  cent. ;  botulism  is  fatal  in  from  50  to  100  per 
cent,  of  those  attacked. 

The  period  of  incubation  is  usually  8  to  28  hours,  often  longer. 
Frequently  several  meals  intervene  between  the  time  the  infected  food 
is  eaten  and  the  onset  of  the  disease.  Vomiting  is  often  the  first 
symptom  and  suspicion  at  once  points  to  the  food  vomited,  whereas  it 
may  have  been  due  to  something  eaten  a  day  or  two  before.  This 
mistake  is  common. 

Various  classifications  of  food  poisoning  have  been  attempted;  none 
are  satisfactory  except  those  based  on  etiology.  The  commonest  mistake 
is  to  classify  food  poisoning  according  to  the  food  responsible,  as  meat 
poisoning,  cheese  poisoning,  potato  poisoning,  milk  poisoning,  etc.,  etc. 
As  a  matter  of  fact,  food  infection  is  the  same  disease,  whether  the 
bacteria  are  conve3'ed  in  meat,  milk,  potatoes,  or  salad.  Botulism  is 
the  same  whether  it  comes  from  sausage,  brawn,  beans,  peas  or  olives. 

Most  instances  of  food  poisoning  are  from  food  that  is  prepared  or 
preserved  in  some  way.  There  is  little  danger  in  fresh  food.  The 
chief  offenders  are  chopped  meat,  sausage,  meat  pies,  salads,  brawn, 
and  other  food  that  is  pickled  or  preserved.  Food  that  is  prepared 
hours  before  it  is  eaten  gives  opportunity  for  the  growth  of  bacteria, 
especially  in  the  summertime. 

The  health  of  food  handlers  is  an  important  factor.  This  applies 
especially  to  those  who  handle  milk  and  milk  products.  Meat  and 
other  foods  may  be  infected  from  cases  or  carriers  of  disease.  Harris 
and  Dublin  ^''  examined  1,748  food  handlers  and  found  10  cases  of 
active  tuberculosis  and  41  with  evidence  of  syphilis,  of  which  37  occurred 
among  waiters. 

"  Mono.  Series,  No.  17,  N.  Y.  C.  Dept.  of  Health. 


694  GENERAL  CONSIDERATIONS 

There  is  a  common  opinion  that  food  poisoning  is  exceedingly  fre- 
quent. This  is  a  mistake,  certainly  in  this  country.  No  satisfactory 
figures  are  available.  Outbreaks  apparently  occur  much  more  frequently 
on  the  Continent  of  Europe  than  in  England,  and  more  frequently  in 
England  than  in  the  United  States.  Savage  tabulates  only  112  British 
outbreaks  of  bacterial  origin,  apart  from  botulism,  studied  from  1878 
to  1918. 

Mayer  presents  a  list  of  48  food  poisoning  outbreaks  which  occurred 
in  Germany  between  1888  and  1911,  and  which  were  attributed  to  B. 
enteritidis.  Bainbridge  states  that  in  Germany  between  1898  and  1908 
there  were  at  least  261  outbreaks  due  either  to  B.  suipestifer  or  B. 
enteritidis. 

Ostertag,  in  1902,  was  able  to  collect  records  of  but  85  epidemics 
in  the  period  1880-1900,  mostly  of  German  sources.  Very  few  out- 
breaks appear  in  the  literature  from  the  United  States.  If  the  affec- 
tion were  made  reportable,  it  would  facilitate  the  study  of  the  problem. 

The  number  of  persons  involved  in  outbreaks  varies  from  one  to 
several  hundred.  The  larger  outbreaks  are  almost  all  caused  by  infected 
milk.  Thus,  at  Newcastle-on-TynC)  in  October  and  November,  1913, 
523  persons  were  affected  by  milk  containing  B.  enteritidis,  and  a  similar 
outbreak  occurred  in  the  same  place  in  1914,  affecting  468  persons 
from  the  same  cause.  Usually  the  number  of  individuals  affected  is 
limited  to  one  or  two  families,  or  to  the  participants  of  a  meal  or 
banquet. 

Acute  attacks  with  gastro-enteric  symptoms  are  not  necessarily  due 
to  harmful  foods.  This  is  a  common  mistake  in  diagnosis.  Nausea, 
vomiting,  cramps  or  diarrhea  may  be  due  to  indigestion,  indiscretions  in 
diet,  eating  when  fatigued ;  also  to  exposure.  The  gastro-intestinal 
tract  is  exceedingly  sensitive  to  reflex  nervous  influences;  thus,  emotion 
may  cause  vomiting  or  diarrhea.  Nervous  exhaustion  is  a  frequent  cause 
of  gastro-enteric  disturbance.  Organic  diseases  of  the  heart  or  kidneys 
are  often  associated  with  gastric  symptoms.  Nausea  and  vomiting 
often  usher  in  acute  infectious  diseases,  especially  in  children.  In 
addition  to  the  above,  we  have  found  in  our  studies  at  Harvard  that 
"ptomain  poisoning"  has  been  mistaken  for  cerebrospinal  fever,  malig- 
nant tumor,  anaphylaxis,  dysentery,  etc. 

Food  infection  has  a  summer  prevalence,  similar  to  other  intestinal 
diseases,  such  as  typhoid  fever,  cholera,  and  dysentery.  Botulism  shows 
no  particular  relation  to  season. 

No  reliance  can  be  placed  upon  the  taste,  odor  or  appearance  of  food. 
On  the  other  hand,  food  showing  evidence  of  abnormal  fermentation 
or  any  putrefaction  should  not  be  eaten. 

B.  enteritidis  and  allied  intestinal  bacilli  cannot  be  detected  by  our 
unaided  senses.    The  toxin  of  botulism  is  usually  associated  with  spoiled 


FOOD  POISONING  695 

food,  but  the  evidence  of  spoilage  may  not  be  sufficient  to  attract 
attention. 

The  general  principles  of  prevention  consist  in  having  our  food 
as  fresh  and  clean  as  possible;  when  processed  the  methods  must  be 
satisfactory.  ]f  preserved  by  heat,  the  temperature  and  time  of 
processing  must  be  sufficient  to  render  the  food  sterile.  If  refrigerated, 
the  temperature  must  be  at  or  near  the  freezing  point.  If  pickled,  the 
brine  must  be  sufficiently  strong  to  prevent  bacterial  growth. 

Finally',  our  ultimate  safeguard  rests  with  cooking.  Both  B.  enter- 
itidis  and  the  toxin  of  botulism  are  comparatively  thermola'bile.  The 
cooking,  however,  must  be  thorough  in  order  that  the  heat  may  pene- 
trate throughout  the  mass.  Food  may  be  contaminated  after  cooking — 
even  sterile  canned  goods  may  be  infected  after  the  contents  of  the  can 
are  exposed.  The  bacilli  belonging  to  the  Gaertner  group  are  non- 
spore  bearing  bacteria  and  are  readily  killed  in  a  few  minutes  at  70°  C. 
This  temperature,  however,  is  frequently  not  reached  in  the  center  of  a 
joint  of  meat,  a  dish  of  vegetables,  or  a  pie.  Kiichenmeister  found 
that  joints  require  boiling  for  several  hours  for  the  interior  to  reach 
a  temperature  of  77°  to  80°  C.  Meat  is  a  poor  conductor  of  heat. 
Perroncito  placed  a  ham  of  about  6  kilos  weight  in  cold  water  which 
was  then  raised  to  the  boiling  point.  The  water  boiled  when  the 
interior  of  the  ham  was  only  25°  C.  After  35  minutes,  it  was  35-40° 
C.,  and  after  2  hours,  the  temperatures  in  different  parts  of  the  interior 
were  46°,  55°,  58°,  62°,  64°,  and  67°  C.  Eupprecht  found  that  boil- 
ing for  45  minutes  as  practiced  in  Saxony  did  not  produce  a  higher 
temperature  than  75°  C,  and  this  only  in  thin  pieces  of  meat.  He 
found  that  the  interior  temperature  of  a  rapidly  roasted  sausage  was 
only  28.7°  C. 

Delepine  and  Howarth  carried  out  experiments  upon  the  tempera- 
tures reached  in  baking  meat  pies.  They  noted  that  the  temperature 
of  the  center  of  the  pie,  said  to  be  underbaked,  but  having  all  the 
external  appearances  of  being  well  baked,  did  not  exceed  47.2°  C. 
The  center  of  a  pie  obviously  overbaked  and  acknowledged  to  be  so,  had 
not  reached  bej'ond  86.6°  C.  Delepine  points  out  that  pies  might  be 
so  cooked  that  bacteria  might  continue  to  grow  in  their  center  during 
the  greater  part  of  their  stay  in  the  oven,  and  the  bacteria  would  cer- 
tainly not  be  killed.  Sawyer  found  that  typhoid  bacilli  survived  in  a 
dish  of  spaghetti  cooked  until  the  surface  was  dark  brown   (page  115). 

Special  methods  of  prevention  are  discussed  in  detail  under  each 
form  of  food  poisoning. 


696  GENERAL  CONSIDERATIONS 

FOOD  INFECTIONS 

Food  infection  is  almost  always  associated  with  Gaertner's  bacillus 
(B.  enteritidis),  or  a  closely  allied  species.  This  form  of  food  infection 
is  also  called  food  poisoning,  and  commonly  miscalled  "ptomain  poi- 
soning." Since  meat  is  the  chief  vehicle  for  this  infection,  it  is  often 
called  "meat  poisoning,"  but  milk,  cheese  and  other  milk  products,  as 
well  as  vegetables,  may  become  infected  and  be  the  vehicles  of  these 
pathogenic  bacilli. 

Incubation  Period. — Usually  from  6  to  13  hours  elapse  between  the 
ingestion  of  the  food  and  the  onset  of  symptoms.  Occasionally  the 
period  of  incubation  is  4  hours  or  less,  and  may  be  72  hours  or  more. 
Not  only  does  the  incubation  period  vary  in  different  outbreaks,  but 
in  the  same  outbreak  widely  different  incubation  periods  have  been 
noted. 

Symptoms. — The  symptoms  are  essentially  those  of  an  acute  gastro- 
intestinal irritation,  namely,  nausea,  vomiting,  abdominal  pain  and 
diarrhea.  The  onset  is  usually  sudden.  The  attack  may  be  ushered  in 
with  headache  and  a  chill.  The  abdominal  pain  is  frequently  the  first 
symptom  and  may  be  gripping  and  severe.  The  diarrhea  usually  consists 
of  repeated  bowel  actions,  which  as  a  rule  are  offensive.  Later  in  the 
attack,  the  stools  become  more  watery  and  frequently  of  a  green  color. 
Faintness,  muscular  weakness  and  prostration  may  be  quite  marked. 
Thirst  is  always  present.  There  is  almost  always  a  rise  of  temperature, 
usually  to  about  102°-103°  P.  Various  nervous  manifestations,  such 
as  restlessness,  muscular  twitchings,  and  drowsiness  may  occur,  but 
these  symptoms  are  not  constant  or  marked.  Oliguria  is  often  present. 
Herpes  and  other  skin  rashes  have  been  noted. 

The  severity  of  the  symptoms  varies  greatly  in  different  outbreaks, 
and  even  in  the  same  outbreak.  All  degrees  are  met  with,  from  fulmi- 
nating cases,  fatal  within  24  hours,  to  those  of  slight  diarrhea  and 
malaise,  insufficient  to  keep  the  patient  from  work.  Usually  the  attack 
is  over  in  a  day  or  two,  with  prompt  recovery;  although  occasionally 
marked  prostration  may  persist.  The  severity  doubtless  depends  upon 
the  virulence  of  the  particular  strain  of  bacilli  concerned,  the  length 
of  time  it  had  to  grow  upon  the  incriminated  food  before  consumption, 
and  the  temperature  of  growth.  The  symptoms  vary  with  the  dose,  also 
with  the  susceptibility  of  the  individual  which  plays  .an  important  role 
in  this  as  in  other  infections. 

The  case  fatality  rate  varies  greatly  in  different  outbreaks.  In  the 
112  British  outbreaks  studied  by  Savage,  there  were  some  6,190  cases 
with  94  deaths,  a  case  fatality  rate  of  1.5  per  cent. 

The  age  and  sex  distribution  depends  entirely  upon  the  accidental 
age  and  sex  distribution  of  those  who  eat  the  infected  food. 


FOOD  POISONING  097 

Most  cases  ocriir  in  (he  suniinor  timo,  corresponding  to  the  sea- 
sonal prevalence  of  typhoid  fever,  cholera,  dysentery  and  other  intestinal 
infections.  The  bacilli  resitonsiblc  for  I'ood  infection  grow  in  the  food 
before  it  is  eaten,  and  therefore  temperature  is  a  very  important  factor. 
The  greater  nnilti})licati()n  of  these  bacteria  in  hot  weather  also  in- 
creases tlie  opportiuiiiies  for  transmission  of  infection  through  flics  and 
uihvv  nu'iins.  Secondary  infections  rarely  occur.  There  is  the  same 
potential  possibility  of  contact  infection  as  in  typhoid  fever,  but  the 
cases  of  food  infection  are  for  the  most  part  acute  and  of  short  dura- 
tion, so  that  there  is  little  opportunity  for  secondary  infection. 

An  outbreak  investigated  by  Savage  in  1908  serves  as  an  illus- 
tration : 

"On  Friday,  May  8,  1908,  in  Murrow,  a  village  in  Cambridge- 
shire, a  woman  purchased  some  pork  bones  from  a  local  butcher  and 
that  evening  used  them  to  make  some  brawn.  The  following  morning 
the  brawn  was  emptied  out  of  the  saucepan  in  which  it  had  been  made 
and,  without  cleansing  the  vessel,  potatoes  and  asparagus  were  cooked 
in  it.  These  vegetables  were  eaten  for  midday  dinner  by  four  persons 
and  all  were  subsequently  attacked  with  vomiting,  diarrhea,  and  the 
other  symptoms  of  food  poisoning,  two  in  the  night  and  two  the  next 
morning.  The  husband,  who  was  away  at  midday,  remained  well  and 
unaffected. 

"On  Monday,  two  days  later,  the  brawn  made  up  into  pork  cheeses 
(a  local  name  for  braM^n)  was  given  away  to  three  different  neighbors 
and  was  consumed  by  a  further  fourteen  persons,  all  of  whom  were 
attacked  with  similar  symptoms  after  an  incubation  period  varying 
from  twelve  to  forty-eight  hours.  Three  of  the  eighteen  attacked  died. 
No  one  eating  the  brawn  escaped. 

"None  of  the  brawn  was  available  for  examination,  but  from  the 
only  fatal  case  investigated  a  Gaertner  group  bacillus  (B.  aertrycTce) 
was  isolated  and  its  connection  with  the  outbreak  was  further  proved  - 
by  the  fact  that  it  was  agglutinated  in  high  dilution  by  the  serum  of 
three  survivors. 

"The  brawn  was  home  prepared,  and  the  materials  were  slowly 
heated  for  several  hours  with  a  short  boil  at  the  finish,  but  obviously 
actual  boiling  temperature  was  not  reached.  That  the  Gaertner  .bacilli 
were  present  before  preparation  and  survived  cooking  is  evident  from 
the  infection  imparted  to  the  vegetables  through  the  uncleansed  sauce- 
pan. Further  inquiries  elicited  that  the  pig  which  supplied  the  bones 
for  the  brawn  had  suffered  from  local  injury  or  disease  of  one  leg,  no 
doubt  due  to  infection  by  this  food  poisoning  bacillus. 

"Here  are  all  the  commonly  present  features  of  such  outbreaks. 
A  typical  group  of  symptoms,  a  number  of  cases  geographically  sep- 


698  GENEEAL  CONSIDEEATIONS 

aratecl  but  linked  by  a  j^articular  food  consumed  in  common,  a  special 
bacillus  demonstrated  to  be  tbe  pathological  cause,  and  lastly  (unlike 
most  outbreaks)  with  definite  evidence  connecting  it  with  disease  in 
the  animal  supplying  the  incriminated  food." 

Taste,  Odor  and  Appearance. — It  cannot  be  too  strongly  emphasized 
that  in  the  vast  majority  of  outbreaks  of  food  infection  the  food  af- 
fected is  not  noticeably  altered  in  either  appearance,  taste  or  smell.  The 
prevalent  idea  that  poisonous  food  must  be  "tainted"  still  persists, 
although  long  exploded.  Bacilli  belonging  to  the  Gaertner  bacillus 
group  cannot  be  detected  in  food  or  water,  any  more  than  typhoid 
bacilli,  dysentery  bacilli  or  cholera  vibrio  can  be  detected  with  our  un- 
aided senses. 

In  the  Ghent  outbreak,  investigated  by  van  Ermengen  in  1895,  a 
slaughterhouse  inspector  (a  veterinary  surgeon)  was  so  certain  that  the 
suspected  meat  (saveloy),  in  the  absence  of  any  abnormal  signs,  could 
have  no  connection  with  the  trouble,  that  he  ate  two  or  three  pieces  of  it 
to  demonstrate  its  harmlessness.  He  was  attacked  with  severe  cholera- 
like symptoms,  and  died  five  days  later,  the  Gaertner  bacillus  being  re- 
covered postmortem. 

In  a  few  of  the  outbreaks,  however,  minor  peculiarities  of  the  food 
have  been  noted,  such  as  objectionable  flavor,  heavy  odor,  moist  or 
soft  condition,  etc.  These,  however,  are  rare  exceptions  and  not 
the  rule. 

Kind  of  Food  Responsible. — The  great  majority  of  outbreaks  are 
due  to  meat  foods,  and  hence  this  form  of  food  infection  is  often 
called  meat  poisoning.  Of  the  112  British  outbreaks,  in  21  the  vehicle 
was  a  non-flesh  food ;  that  is,  milk,  1 ;  cream,  1 ;  ice  cream,  6 ;  potatoes, 
2;  pineapple  jelly,  1;  canned  peaches,  1;  rice  cooked  in  fat,  1.  The 
remaining  ninety  were  all  due  to  flesh  food,  mainly  brawn,  meat  pies, 
pork,  ham,  beef,  etc.  The  meat  of  the  pig  or  ox  accounts  for  68  per 
cent,  of  the  British  and  61  per  cent,  of  the  Continental  outbreaks.  The 
almost  complete  absence  of  outbreaks  due  to  the  meat  of  th-^  sheep  is 
striking.     The  number  of  cases  ascribed  to  fish  is  small. 

Most  outbreaks  are  due  to  some  form  of  prepared  meat  foods,  such 
as  brawn,  meat  pies,  sausage,  chopped  meat,  etc.  ^Yhen  the  nature  of 
the  infection  is  considered,  the  more  the  food  is  handled  and  the  longer 
it  lies  around,  the  greater  the  opportunity  for  it  to  become  contami- 
nated and  for  the  bacteria  to  grow  and  multiply. 

Diagnosis. — Diagnosis  of  food  infection  depends  upon :  history  of 
exposure  to  the  suspected  food;  symptoms  suggestive  of  food  poison- 
ing; isolation  of  the  infecting  organisms  from  the  suspected  food,  and 
also  from  the  blood,'  urine,  feces,  or  viscera  of  the  patient  (bacilli  be- 
longing to  the  Gaertner  group  disappear  from  the  feces  in  from  7  to  10 


FOOD  POISONING  699 

clays  after  the  onset  of  symptoms),  specific  identification  of  the  causa- 
tive organism  by  agglutination  tests;  demonstration  of  agglutinins  in 
the  blood  serum  of  patients.  A  positive  reaction  can  be  detected  0  or  S 
days  after  the  onset  of  symptoms.  Agglutination  in  comparatively  low 
dilutions  is  usually  accepted  as  diagnostic  owing  to  the  fact  that  it  is 
extremely  rare  to  find  a  positive  reaction  for  />'.  enterUidU  or  B.  suipes- 
tifer  in  normal  individuals. 

For  a  better  understanding  of  food  infection  and  its  prevention,  il 
is  necessary  to  know  the  habitat,  cultural  and  biological  properties,  as 
well  as  the  toxin  production,  of  the  Gaertner  group  of  bacilli  responsible 
for  this  disease.  The  Gaertner  group  is  a  subdivision  of  the  colon- 
typhoid  group. 

THE   COLON-TYPHOID   GROUP 

The  colon-typhoid  group  is  a  large  class  of  important  organisms 
which  has  the  typhoid  bacillus  at  one  end  and  the  colon  bacillus  at  the 
other.  The  intermediate  forms  in  this  group  comprise  the  paratyphoid 
bacilli,  the  dj'sentery  bacilli,  the  hog  cholera  bacilli,  the  Bacillus  psitta- 
cosis (a  disease  of  parrots  communicable  to  man),  the  Bacillus  icteroides 
(once  associated  with  yellow  fever),  the  Bacillus  typhi  murium  (the 
bacillus  of  mouse  typhoid,  the  type  of  the  bacterial  rat  viruses),  the 
Bacillus  enterUidis  of  Gaertner  (associated  with  food  infection  and 
diarrheal  diseases),  and  many  others. 

The  organisms  comprising  this  group  are  so  closely  related  that  it 
is  often  difficult  to  determine  where  specific  differences  begin  and  termi- 
nate. This  group  may  be  taken  as  a  beautiful  instance  of  missing  links, 
and  a  study  of  these  closely  related  organisms  excites  the  imagination  to 
the  belief  that  we  may  here  see  evolution  in  the  making  (see  table,  page 
700). 

The  differentiation  of  the  typhoid-colon  group  based  upon  fermenta- 
tion tests  is  shown  in  the  following  statement  from  Savage. ^^ 

THE  GAERTNER  GROUP 

The  Gaertner  group,  of  which  B.  enteritidis  is  the  type,  occupies  an 
intermediate  position  between  the  colon  bacillus  on  the  one  hand,  and 
the  typhoid  bacillus  on  the  other.  It  is  also  called  the  ''intermediate 
group/'  the  "hog  cholera  group/'  the  "enteritidis  group/'  the  "paraty- 
phoid group/'  and  the  "Sahnonella  group/' 

The  classification  of  the  members  of  this  group  is  quite  involved, 
and  there  is  still  a  lack  of  agreement  among  different  investigators  con- 
eernmg  some  of  the  details.     The  important  members  are  as  follows : 

B.  Enteritidis. — Gaertner,  in  1888,  brought  forth  the  first  definite 

®  "Food  Poisoning  and  Food  Infection,"  page  238. 


700 


GENERAL  CONSIDERATIONS 


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FOOD  POISONING 


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DIFFERENTIATION  OF  THE  TVPHOID-COLON  GROUP 
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evidence  which  incriminateci  bacteria  as  an  etiologic  factor  in  food 
poisoning.  At  Frankenhausen,  57  individuals  became  ill  after  eating 
the  flesh  of  a  cow  which  had  been  slaughtered  on  account  of  enteritis; 
one  case  resulted  fatally.  Gaertner  isolated  the  bacillus  from  the 
organs  of  the  cow  and  also  from  the  spleen  of  the  man  who  died.  He 
called  the  or^^anism  B.  enteritidis.  It  has  since  been  shown  to  be  the 
common  etiologic  factor  in  food  poisoning.    It  is  the  type  of  the  group. 

B.  moroificans  bovls  was  isolated  by  Basenau  in  1893  from  the 
muscles  and  viscera  of  a  cow  killed  on  account  of  puerperal  metritis. 
There  is  little  doubt  but  that  this  organism  is  identical  with  B.  en- 
t&ritidis  of  Gaertner. 

B.  suipestifer,  also  called  B.  cholera,  suis,  or  the  hog  cholera  bacillus, 
was  isolated  by  Salmon  and  Theobald  Smith  in  1885.  For  a  long  time 
this  was  believed  to  be  the  cause  of  hog  cholera,  but  it  is  now  known  to 
be  a  secondary  invader.  It  is  often  used  as  a  group  type.  Man  is  not 
susceptible  to  hog  cholera,  which  is  due  to  a  filtrable  virus.  There 
are  doubtless  many  strains  of  the  hog  cholera  bacillus,  only  some  of  which 
are  pathogenic  for  man.  for  no  relationship  has  been  found  between 
hog  cholera  and  food  poisoning  in  man;  in  fact,  pork  has  been  eaten 


702  GENEEAL  CONSIDERATIONS 

many  times  from  hogs  with  hog  cholera  without  ill  effect.     This  is  an 
illustration  of  the  difficulties  and  confusion  in  this  group  of  bacilli. 

B.  aertrycJce  was  isolated  in  1898  in  Hatton,  England,  and  by  De 
Nobele  in  Aertrycke,  Belgium.  This  organism  is  known  to  be  identical 
with  B.  suipestifer. 

B.  psittacosis  was  isolated  by  Nocard  in  .1893  from  the  bone  marrow 
of  parrots  which  had  died  en  route  from  Buenos  Aires  to  Paris.  It  is 
also  associated  with  a  highly  fatal,  pneumonia-like  disease  in  man  in 
Paris.  Bainbridge  regards  B.  psittacosis  as  identical  with  B.  suipesti- 
fer. The  organism  is  now  only  of  historical  interest,  because  there 
has  been  no  recurrence. 

B.  typhi  murium  was  isolated  by  Loeffler  in  1893  from  an  epizootic 
among  his  laboratory  mice.  This  organism  is  closely  related  to  B. 
suipestifer.  Bainbridge  pointed  out  that  the  name  M^as  applied  to  either 
pure  cultures  of  B.  enteritidis,  or  to  mixed  cultures  of  B.  enteritidis,  B. 
suipestifer,  and  B.  paratyphosus  (3.  Shibayama  reported  instances  of 
human  illness  resulting  from  infection  with  the  cultures  of  B.  Typhi 
murium  used  as  a  rat  virus. 

Danysz's  virus  consists  of  a  culture  of  a  bacillus  isolated  from  an 
epizootic  among  harvest  mice.  Bainbridge  has  shown  that  it  is  identical 
with  B.  enteritidis. 

B.  icteroides  was  isolated  by  Sanarelli  in  1898  from  yellow  fever 
patients,  and  believed  by  him  to  be  the  cause  of  the  disease.  Reed 
and  Carroll,  in  1899,  showed  that  it  was  culturally  identical  with  B. 
suipestifer,  and  it  has  now  only  historical  interest. 

B.  paratyphosus  (3  was  isolated  by  Acharde  and  Bensande  in  1896, 
but  carefully  studied  by  Schottmuller  in  1900.  Brion  and  Kayser,  in 
1902,  named  the  two  types  B.  paratyphosus  a  and  B.  paratyphosus  (3. 

In  England,  the  term  B.  paratyphosus  P  is  limited  to  those  strains 
which  are  identical,  by  culture,  agglutination  and  absorption  tests,  with 
the  original  strain  of  Schottmuller.  Such  a  restriction  is  not  yet  gen- 
erally accepted,  however,  and  consequently  considerable  confusion  has 
arisen.     See  also  paratyphoid  fever,  page  136. 

The  English,  due  chiefly  to  the  careful  observations  and  absorption 
tests  of  Bainbridge,  Bainbridge  and  O'Brien,  and  the  studies  of 
Savage,  believe  that  only  three  organisms  are  involved  in  cases  of 
food  infection :  namely,  B.  paratyphosus  ^,  B.  suipestifer  and  B. 
enteritidis.  The  Germans,  however,  regard  B.  paratyphosus  P  and  B. 
suipestifer  as  one  and  the  same  organism.  If  the  strain  comes  from 
an  animal  they  call  it  B.  suipestifer;  if  from  man,  B.  paratyphosus  p. 

It  is  evident  to  the  student  of  bacteriology  that  the  confusion  in  this 
and  other  groups  is  due  first  of  all  to  the  fact  that  we  have  no  clear- 
cut  criteria  of  genera,  species  and  strains  among  bacteria;  second,  to 
the  fact  that  we  are  dealing  with  biologic  variables.     Thus,  a  strain 


FOOD  POISONING  703 

may  be  cultivated  so  that  tt'itain  cullui-al  and  biologic  properties  are 
entirely  changed.  These  differences  are  probably  always  variants,  rarely 
if  ever  of  the  magnitude  of  mutants.  It  is  true  that  sometimes  the 
changes  thus  produced  seem  fixed  in  that  they  breed  true  to  type, 
but  usually  they  revert  wlien  ])]aced  under  proper  conditions. 

We  do  not  know  the  significance  of  the  differences  between  B.  enter- 
ilidis,  B.  cholera  siiis  and  II.  j.anili/pltosii.s  (3. 

Toxin  Production. — The  organisms  of  the  Gaertner  group  are  said 
to  produce  soluble  toxic  substances  which  are  heat  resistant.  This, 
however,  is  almost  entirely  theoretical.  Cathcart,  for  example,  as  well 
as  a  number  of  other  workers,  such  as  Brion  and  Kayser,  Kutcher  and 
Meinicke,  Levy  and  Fornet,  found  no  evidence  of  soluble  toxins,  while 
others,  such  as  Uhlenhuth,  Zwick  and  Weichel,  and  Vaughan  found 
evidence  of  toxic  bodies  in  the  filtrates.  A  review  of  the  literature  on 
this  subject  up  to  1917  is  given  by  Ecker  who  found  that  soluble  toxic 
substances  are  produced  within  '?4  hours  by  some  strains  of  li.  para- 
typhosus  (3. 

Aronovitch,  working  in  my  laboratory,  found  that  filtrates  of  broth 
cultures  of  some  strains  of  the  Gaertner  group  are  toxic  when  injected 
into  mice  or  guinea-pigs.  The  filtrates  of  young  (24-hour  old)  cul- 
tures are  destroyed  at  75°  C,  but  when  7  days  old,  are  destroyed  only 
at  100°  C.  in  from  one  to  two  hours.  There  is  no  evidence  whatever 
that  these  substances  are  poisonous  or  even  irritating  when  taken  by  the 
mouth.  The  symptoms  produced  when  these  filtrates  are  injected  into 
animals  have  no  resemblance  to  food  poisoning.  The  nature  of  the  poi- 
sonous substances  in  these  filtrates  is  problematical,  and  the  relation 
to  true  toxins  has  not  yet  been  established. 

Most  writers  on  the  subject  of  food  poisoning  state  that  when  the 
period  of  incubation  is  short  it  is  due  to  the  ingestion  of  toxins  pro- 
duced in  the  food  before  it  is  eaten.  This  is  entirely  conjectural.  Endo- 
toxins have  also  been  invented  to  account  for  the  facts.  How  micro- 
organisms, such  as  the  Gaertner  bacilli  group,  injure  the  tissues  of  the 
host  is  part  of  the  problem  of  the  pathogenesis  of  infectious  processes, 
which  is  still  far  from  solution. 

SOURCES  OF  INFECTION  WITH  THE  GAERTNER  GROUP 

Diseased  Animals — Aniemortem  Infection. — B.  enteritidis  and  its 
congeners  are  pathogenic  for  some  of  our  food  animals,  as  well  as  for 
man.  Cattle  suffering  during  life  from  puerperal  fever,  uterine  inflam- 
mations, navel  infection  (in  calves),  septicemia,  septic  pyemia,  diarrhea, 
and  local  suppurations  are  apt  to  furnish  meat  containing  the  Gaertner 
bacillus  or  closely  related  bacilli.  Such  meat  has  frequently  given  rise 
to  meat  poisoning.    Hence,  emergency  slaughter  (Nothschlacht)  unless 


704  GENEEAL  CONSIDERATIONS 

intelligently  supervised,  furnishes  meat  that  may  be  a  menace.  The 
meat  of  such  animals  presents  no  warning  signs  of  its  danger.  This 
fact  was  well  proved  by  the  meat  inspector  at  Ghent  who  lost  his  life 
because  he  was  so  sure  that  meat  must  be  tainted  to  be  harmful.  The 
story  of  this  tragedy  has  become  classic  (page  698). 

Postmortem  Infection.— The  meat  may  come  from  healthy  animals, 
but  become  infected  after  slaughter.  This  may  take  place  through  the 
hands  or  instruments  of  the  butcher  who  has  just  handled  a  diseased 
carcass.  There  are  other  possibilities,  such  as  human  carriers,  fecal 
contaminations,  etc. 

Human  Carriers. — Bainbridge  states  that  "infection  of  meat  by  hu- 
man carriers  of  B.  suipestifer  is  unknown."  Human  carriers  of  B. 
enteritidis  are  exceedingly  rare.  Human  carriers  of  B.  paratyphosus  (3 
are  occasionally  discovered,  but  these  also  are  infrequent.  ,  In  4,154 
specimens  of  human  feces  from  healthy  individuals  examined  in  my 
laboratory  in  1917-18,  not  a  single  carrier  of  any  of  these  non-lactose 
fermenters  was  found. 

The  English  observers  believe  that  all  cases  of  food  poisoning  traced 
to  human  carriers  are  in  reality  cases  of  paratyphoid  fever,  but  the 
Germans,  who  do  not  differentiate  between  B.  paraiyphosus  (3  and  B. 
suipestifer,  hold  that  the  latter  organism  also  occurs  in  normal,  healthy 
human  intestines,  and  may  thus  become  a  source  of  food  infection.  Such 
instances  must  be  exceedingly  rare  in  the  United  States,  for  in  our 
studies  of  the  subject  we  have  not  found  a  single  instance  in  three 
years. 

Rats  and  Mice. — The  common  gray  rat  and  mice  may  harbor  B. 
suipestifer  and  possibly  B.  enteritidis  as  carriers.  Zwick  and  Weichel 
examined  177  mice  and  found  that  28  were  acting  as  carriers  of  Gaertner 
group  bacilli.  Hence,  food  may  become  infected  by  contamination  with 
rat  or  mice  feces.  There  is  abundant  opportunity  for  such  contact  in 
the  slaughterhouse,  in  butcher  shops,  in  refrigerator  plants,  in  trans- 
portation, and  in  the  home. 

Rat  Viruses. — Food  has  occasionally  become  contaminated  by  con- 
tact with  bacterial  viruses  used  against  rats.  These  viruses  are  pure 
cultures  of  B.  typhi  murium,  closely  allied  to  B.  enteritidis.  Shibayama 
reported  instances  of  human  illness  resulting  from  the  free  use  of  such 
cultures. 

Contamination  with  Fecal  Bacteria. — This  source  of  infection  is 
highly  improbable,  for  if  it  were  true,  food  poisoning  would  be  exceed- 
ingly common,  so  great  is  the  ordinary  fecal  contamination  of  our  food. 
During  the  years  1917-18,  over  500  samples  of  food  were  examined  in 
my  laboratory  without  finding  a  single  pathogenic  member  of  the  colon- 
typhoid  group. 


FOOD  POISONING  705 

Food  Poisoning  of  Non-Specific  Bacterial  Origin. — A  number  of 
other  bacteria  have  been  associated  with  food  poisoning,  such  as  B.  pro- 
teus,  B.  fecalis  alkaligenes,  B.  prodigiosis,  and  even  the  colon  bacillus 
itself.  There  is  slight  evidence  that  any  of  these  are  ever  responsible  for 
the  trouble  in  question. 

Another  view  is  that  massive  infection  of  food  with  fecal  and  other 
bacteria  may  cause  symptoms  of  gastro-intestinal  irritation.  That  this 
is  unlikely,  or  at  least  unusual,  is  evidenced  by  the  enormous  numbers 
of  bacteria,  including  fecal  bacteria,  taken  with  milk,  cream,  butter  and 
other  milk  products;  also  in  cheese,  sauerkraut,  sausage,  etc.,  etc.  Food 
very  massively  infected  with  B.  coli  and  uther  intestinal  bacteria  and 
given  to  animals  to  eat  does  not  cause  infection  or  illness. 

All  the  evidence  points  to  the  cause  of  food  infection  as  due  to 
specific  organisms  belonging  to  the  Gaertner  group. 

The  prevention  of  food  infection  starts  with  the  meat  inspector. 
Animals  suffering  with  any  septic  or  pyemic  lesions,  whether  local  or 
generalized,  should  be  condemned  as  unfit  for  food  purposes,  unless 
bacteriologic  examination  excludes  the  Gaertner  group  bacilli.  These 
infections  may  be  discovered  either  antemortem  or  postmortem.  Food 
animals  suffering  with  puerperal  sepsis  or  enteritis  are  especially  sus- 
picious. The  greatest  care  should  be  taken  with  sick  animals  killed 
under  the  provisions  of  emergency  slaughter   (Xothschlacht). 

Pains  must  be  taken  to  disinfect  hands,  tools  and  surfaces  in  case 
such  an  animal  comes  to  the  slaughterhouse,  to  avoid  the  infection  of 
other  carcasses.  Cleanliness  must  be  exercised  in  butchering,  handling, 
storing  and  transporting  meat.  Every  care  must  be  exercised  to  guard 
it  against  contamination  with  rat  and  mice  feces. 

Food  should  not  be  handled  more  than  necessary.  The  health 
of  food  handlers  is  obviously  important.  It  is  especially  prepared 
foods,  such  as  chopped  meats,  sausage,  meat  pies,  and  brawn  that  cause 
trouble.  Such  fussy  and  fingered  foods  are  not  necessary  and  are  to 
be  avoided. 

It  should  be  remembered  that  articles  other  than  meat  are  some- 
times infected,  especially  milk,  cream,  ice  cream,  potato  salad — the  list  is 
long  and  comprehensive.     Cleanliness  and  freshness  are  the  watchwords. 

Food  infections  are  especially  apt  to  take  place  from  foodstuffs 
that  have  not  been  properly  refrigerated.  B.  enteritidis  may  grow  and 
multiply  at  temperatures  as  low  as  10°  C.  Foods  that  have  been  handled, 
chopped,  fixed  or  prepared  some  hours  before  the  meal  are  most  apt 
to  give  trouble;  hence,  the  frequency  with  which  food  poisoning  is  as- 
sociated with  picnic  lunches,  fraternity  dinners,  and  banquets. 

Cooking  is  our  great  safeguard.  These  non-spore  bearing  bacilli  are 
readily  killed.  The  cooking  must  be  thorough  and  should  be  recent, 
that  is,  just  before  serving.     See  page  749. 


706  GENERAL  CONSIDEEATIONS 

BOTULISM 
(Allantiasis) 

Botulism  is  a  specific  intoxication  caused  by  the  toxin  of  the  Bacil- 
Ins  botulinus  (Clostridium  hotulinum).  The  bacillus  grows  in  a  great 
variety  of  foodstuffs,  both  of  plant  and  animal  origin,  and  produces  its 
poison  in  the  food  before  it  is  eaten.  The  name  botulism  has  lost  its 
original  significance  (botulus,  a  sausage). 

Botulism  stands  alone  as  a  type  of  food  poisoning.  It  is  well  under- 
stood and  is  the  only  known  instance  in  its  class.  The  bacillus  itself  is 
essentially  a  saprophyte.  Botulism  further  difl'ers  from  the  usual  type 
of  food  poisoning  in  that  the  intoxication  chiefly  affects  the  central 
nervous  system.  Acute  gastro-intestinal  disturbances  usually  do  not 
occur.     There  is  no  fever. 

A  complete  history  of  the  condition  and  a  thorough  review  of  the 
literature  is  found  in  Dickson's  monograph. ^^ 

Prevalence. — Botulism  has  been  recognized  by  German  clinicians 
since  1735,  when  the  first  authenticated  case  was  recorded.  The  out- 
break which  first  attracted  the  attention  of  the  medical  profession  oc- 
curred in  1793  in  Wildbad  in  Wiirttemberg,  v/here  13  persons  became  ill 
and  6  died  after  eating  sausage  packed  in  the  stomach  of  a  hog,  and 
which  contained  a  great  deal  of  blood.  The  number  of  cases  reported 
in  Germany  are  as  follows : 

From  1793  to  1820  76  cases  37  deaths 

"     1820  "  1822  98    "  34     " 

"     1822  "  1886  238    "  94     " 

"     1886  "  1913  about  800    "    about  200     " 

Dickson  *°  was  able  to  tabulate,  during  the  twenty  years  prior  to 
1917,  22  outbreaks  of  botulism  in  the  United  States.  Of  these,  18 
occurred  on  the  Pacific  Coast — 17  in  California  and  1  in  Oregon. 
These  outbreaks  involved  81  individuals,  55  of  whom  died — a  mortality 
of  67.9  per  cent.  Since  then,  the  outbreaks  have  been  collected  by  Dr. 
Dwight  L.  Sisco,  while  working  on  the  subject  in  my  laboratory;*^  and 
tabulated  on  the  next  page. 

The  cause  of  botulism  was  demonstrated  by  van  Ermengem  *^  who 
studied  a  series  of  cases  which  occurred  at  Ellezelles,  in  Belgiuni,  in 
1895.     In  the  first  of  these  outbreaks,   23   persons  became  ill  and  3 

^Mono.  No.  8,  Eockefeller  Inst,  for  Med.  Research,  July  31,   1918. 

*'J.  A.  M.  A.,  Sept.  22,   1917,  LXIX,  p.  966. 

*^  To  this  must  be  added  several  recent  outbreaks  due  to  canned  spinach. 

^^Arch.  Pharmacod.,  1897,  iii,  21S yCentrl.  Bakt.,  Ite  Abt.,  1896,  xix,  442; 
Zeit.  Hyg.  u.  Infektionskrankh.,  1897,  xxvi,  1;  Kolle  u.  Wassermann,  "Handbuch 
der  pathogenen  Mikroorganismen,"  Jena,  2nd  ed.,  1912,  iv,  1909. 


FOOD  POISONING 


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708  GENERAL  COXSIDEEATIONS 

died  after  eating  ham  which  had  been  preserved  in  brine.  From  por- 
tions of  the  ham  and  from  the  spleen  and  intestinal  contents  of  one  of 
the  victims,  van  Ermengem  succeeded  in  isolating  a  gram  positive, 
spore-bearing  anaerobic  bacillus,  to  which  he  gave  the  name  Bacillus 
botulinus.  He  found  that  infusions  of  the  macerated  ham,  and  bou- 
illon cultures  of  Bacillus  hotulinu^s,  produced  the  typical  symptoms  of 
botulism  in  guinea-pigs,  rabbits,  cats,  pigeons  and  monkeys.  The  bacil- 
lus itself  he  believed  to  be  a  saprophyte,  and  the  poisoning  to  be  due 
to  a  toxin  which  is  formed  wlien  it  grows  in  food  under  anaerobic  con- 
ditions. 

Botulism  i?  much  more  common  in  Europe  than  in  this  country. 
Savage  states  that  not  a  single  outbreak  has  come  to  light  in  England, 
Scotland  or  Wales.  Botulism  is  a  rare  disease.  The  high  mortality, 
the  distressing  symptoms  and  the  relation  to  food  have  -  dramatic 
news  value,  and  the  disease  has  recently  caused  concern  and  alarm  out 
of  all  proportion  to  its  importance.-  A  disease  which,  during  a  period 
of  22  years,  has  made  only  about  150  people  ill  and  caused  the  death  of 
111  of  these,  among  approximately  100  millions  of  people,  cannot  be 
compared  in  magnitude  ^-ith  tuberculosis  and  other  public  health  prob- 
lems. 

Botulism  presents  no  particular  distribution  as- to  sex,  age,  season, 
or  social  condition. 

Botulism  is  one  of  the  causes  of  forage  poisoning  in  horses,  and  of 
limberneck  in  chickens  and  turkeys,  and  may  also  be  responsible  for 
various  types  of  paralysis  in  domestic  animals,  including  dogs. 

Symptoms. — The  symptoms  usually  appear  from  18  to  36  hours  after 
ingestion  of  the  poisonous  food.  However,  cases  are  on  record  in  which 
the  incubation  period  has  been  as  short  as  4  hours  or  as  long  as  6 
days.  The  period  of  incubation  probably  depends  upon  the  amount  and 
virulence  of  the  toxin  ingested. 

The  earliest  symptom  is  usually  a  peculiar  indefinite  indisposition, 
associated  with  a  feeling  of  fatigue,  sometimes  headache  and  dizziness, 
and  definite  muscular  weakness.  When  the  period  of  incubation  is  short, 
the  first  symptoms  may  be  gastric  distress,  nausea,  vomiting  and  occa- 
sionally diarrhea.  This  makes  the  diagnosis  questionable,  for  botulism 
differs  from  the  common  type  of  food  poisoning,-  in  that  there  are 
usually  no  indications  of  acute  gastro-intestinal  irritation.  Constipa- 
tion is  an  almost  constant  manifestation  of  the  condition. 

Disturbances  of  vision  occur  early.  Scintillation  and  dimness  of 
vision  progress  sometimes  to  blindness.  The  disturbances  of  vision  are 
due  to  impairment  of  both  the  extrinsic  and  intrinsic  muscles  of  the  eye. 
The  third  cranial  nerve  is  early  involved,  causing  blepharoptosis,  dila- 
tation of  the  pupils,  loss  of  reflex  to  light,  and  diplopia.  Loss  of  ac- 
commodation soon  becomes  complete.     Xystagmus,  strabismus,  and  ver- 


FOOD  POISONING  709 

tigo  and  sometimes  photophobia  occur,  The  opthalmoplegia  is  merely 
a  phase  of  the  more  general  paralysis,  but  may  be  conveniently  separated, 
owing  to  the  striking  character  of  its  manifestations. 

Coincident  with,  or  closely  following,  the  onset  of  disturbances  of 
vision,  the  patients  complain  of  difficulty  of  swallowing  and  talking,  and 
frequently  there  is  a  peculiar  sensation  of  contraction  of  the  throat. 
The  niouth  is  dry  and  attacks  of  strangling  occur.  Thick,  glairy  mucus, 
with  dryness  of  the  throat  leads  to  an  ineffectual  cough.  The  breath 
is  offensive  and  fetid.  Complete  paralysis  of  peristalsis  causes  the  stub- 
born constipation. 

A  striking  feature  is  the  progressive  muscular  weakness  which  in 
severe  cases  closely  simulates  paralysis.  Incoordination  of  muscular 
movement  is  common.  The  paralysis  is  in  a  general  way  an  ascending 
paralysis  manifesting  itself  first  in  the  intestines,  perhaps  due  to  in- 
volvement of  the  mesenteric  plexus,  then  gradually  passing  upward, 
progressively  involving  higher  centers,  until  the  medulla  is  reached.  The 
motor  areas  seem  almost  never  to  be  involved,  although  in  the  recent 
i\rontana  outbreak  paral5^sis  of  the  right  arm  and  leg  was  observed. 

The  loss  of  nervous  tone  manifests  itself  in  vague,  indefinite  indis- 
position, marked  fatigue,  dizziness,  headache,  restlessness,  indefinite  sen- 
sations of  chilliness,  incoordination  and  unsteadiness  in  walking  with 
a  tendency  to  a  "steppage"  gait,  great  muscular  weakness  and  sometimes 
urinary  incontinence.  The  ophthalmoplegia  may  be  partly  responsible 
for  some  of  the  above  symptoms. 

Botulism  is  characterized  by  an  almost  complete  absence  of  sensory 
disturbances.    It  is  unusual  to  suffer  pain,  and  the  mind  remains  clear. 

Inhibition  of  many  of  the  secretions,  especially  saliva,  sweat,  and 
tears,  is  an  almost  constant  manifestation  of  botulism.  Oliguria  has  been 
noted. 

The  pulse  is  usually  rapid,  and  the  temperature  subnormal.  Fever 
developing  late  in  the  poisoning  indicates  bronchopneumonia.  Respira- 
tion at  first  is  not  impaired  but  later  in  the  course  of  the  illness  dis- 
turbances of  respiration  become  very  severe.  Difficult  articulation  and 
perhaps  complete  aphonia,  accompanied  by  an  inability  to  swallow,  soon 
appear,  due  to  paralysis  of  the  laryngeal  and  pharyngeal  muscles.  In- 
creasing difficulty  in  breathing,  leading  eventually  to  death  due  to 
paralysis  of  the  respiratory  center,  brings  the  scene  to  a  close. 

The  general  appearance  of  the  patient  is  distressing:  the  muscular 
weakness,  the  anxiety  and  utter  helplessness,  the  difficulty  in  swallow- 
ing, the  attacks  of  strangling,  the  struggle  for  breath,  and  the  unsuc- 
cessful attempts  to  articulate  constitute  a  clinical  picture  which  once 
seen  can  never  be  forgotten. 

The  most  characteristic  symptoms  seem  to  be  dimness  of  vision,  dip- 
lopia, palpebral  ptosis,  fatigue,  progressive  muscular  weakness,  difficult 


no  GENERAL  CONSIDERATIONS 

articulation  and  swallowing,  and  respiratory  paralysis.  The  clinical  pic- 
ture is  essentially  that  of  a  bulbar  paralysis,  with  the  earliest  symptoms 
indicating  injury  high  up  in  the  brain  stem.  The  disease  must  be  differ- 
entiated from  other  causes  of  bulbar  paralysis  and  ophthalmoplegias, 
such  as  encephalitis  lethargica,  poliomyelitis,  cerebrospinal  syphilis; 
also  poisoning  from  belladonna,  gelsemium,  hyoscyamus  and  methyl 
alcohol. 

The  duration  varies  greatly.  Death  may  occur  in  48  hours  after 
eating  the  poisonous  food ;  as  a  rule,  it  occurs  in  from  4  to  8  days,  and 
few  die  after  10  days.  Dickson  reports  one  death  on  the  26th  day.  Death 
usually  is  due  primarily  to  respiratory  failure.  Convalescence  is  ex- 
tremely slow  and  tedious.  The  disturbances  of  vision  and  weakness  may 
last  for  months. 

The  mortality  of  botulism  has  varied  greatly  in  different  outbreaks, 
depending  upon  the  amount  and  virulence  of  the  toxin.  In  certain 
instances  it  has  been  extremely  high — in  some  100  per  cent. — but  in 
others  it  has  been  correspondingly  low.  Wosnitza  *^  recorded  a  series  of 
59  cases  of  which  only  4  died.  In  Kerner's  series  **  of  159  cases,  there 
were  84  deaths,  a  mortality  of  52.8  per  cent.,  and  in  Scholssberger's 
series  *^  of  400  cases  there  were  150  deaths,  a  mortality  of  37.5  per  cent. 
The  most  complete  collection  of  cases  is  that  of  Mayer,*^  in  1913,  in 
which  he  reports  812  cases  of  which  365  were  fatal,  a  mortality  of  44.9 
per  cent. 

Patholo^. — The  pathology  of  the  disease  has  been  but  little  studied. 
Wilbur  and  Ophuls  '''^  reported  hyperemia  of  the  viscera  and  widespread 
thromboses  in  the  blood  vessels  of  the  meninges  and  brain.  Dickson,^^ 
after  a  careful  review  of  the  literature  as  well  as  from  his  own  experi- 
ments, concludes  that  thromboses  in  the  blood  vessels  of  various  organs 
of  the  body  are  a  characteristic  lesion  of  the  disease.  The  only  constant 
finding  on  macroscopic  examination  of  the  bodies  of  victims  of  botulinus 
poisoning  is  the  marked  congestion  of  the  central  nervous  system,  and 
of  the  abdominal  and  thoracic  viscera.  Not  infrequently  there  are 
multiple  hemorrhages  around  the  base  of  the  brain  and  the  upper  part 
of  the  cord.     The  lungs  are  usually  extremely  hyperemic. 

The  Bacillus. —  The  Bacillus  botulinus  discovered  by  van  Ermengem 
in  1895  is  a  large,  slightly  motile  rod,  4  to  6      long,  0.9  to  1.2  ^  thick. 

^  "Inaugural   Dissertation,"  Leipzig,   1909. 

"  Neue  Beobachtungen  iiber  die  in  Wiirttemberg  so  haufig  vorfallenden  tod- 
liehen  Vergiftungen  durch  den  Genuss  geraueherter  Wiirste,  Tiibingen,  1820;  Das 
Fettgift,  Oder  die  Fettsaure,  und  ihre  WirJiungen  auf  den  tliierischen  Organismus. 
Ein  Beitrag  zur  Untersucliung  des  in  verdorbenen  Wiirsten  giftig  wirkenden 
Stoffes,  Stuttgart  and  Tiibingen,  1822. 

■"'Arch,  de  Physiol.  Heilk.,  1852,  XI,  709. 

*^Deutsch.  Vrtljschr.  off.  Gsndhtspflg.,  1913,  XIV,  8. 

"Arch.  Int.  Med.,  1914,  XIV,  589. 

•^Mono.  of  the  Rockefeller  Inst.,  X^q.  8,  July  31,  1918. 


FOOD  POISONING  711 

It  has  sliyhtl)-  i-ouikIimI  nuls;  I  to  8  flagellae,  generally  siiiprU. ;  rarely 
occurs  in  lilaments;  has  a  large  polar  spore;  stains  readily,  and  is  Grani- 
])ositivp.     Tlie  new  name  is  CIos(ri<fiiiiii  hoinJinnm. 

The  hacilliis  grows  well  at  room  temperature,  between  20°  and  30° 
C,  but  also  thrives  at  37°  C.  Contrary  to  previous  opinion,  it  may  gi'ow 
in  the  body.  It  is  an  anaerobe,  but  may  grow  under  imperfeet  anaer- 
obic conditions;  also  if  in  symbiosis  with  certain  aerobic  bacteria,  such 
as  a  wliite  Sareina  (van  Ermengem)  or  with  B.  subUlis  (Romer)  ;  and, 
according  to  Ilarrass  and  also  Tarozzi,  will  grow  in  freshly  prepared 
bouillon  under  aerobic  conditions  if  a  piece  of  sterile  flesh  or  potato  is 
l^laced  on  the  bottom  of  the  culture  tube.  The  addition  of  glucose  to 
the  culture  medium  greatly  increases  its  activity  in  growth  and  in 
toxin  formation.  In  a  medium  consisting  of  one  part  sheep's  brain  and 
two  parts  water  it  grows  well  and  produces  an  abundance  of  spores. 
The  strains  studied  by  van  Ermengem  produced  practically  no  change  in 
the  appearance  of  milk,  but  von  Hibler  and  others  find  that  milk  casein 
is  precipitated  and  peptonized.  It  is  strongly  proteolytic,  and  a  putre- 
factive odor  is  given  otf.  Gas  which  is  usually  formed  is  due  to  the  fer- 
mentation of  sugars  in  the  medium.  The  21  cultures  studied  in  my  lab- 
oratory show  minor  differences  in  cultural  characteristics;  only  ten  of 
these  strains  produce  toxin.  Atoxic  strains  must  be  differentiated 
from  B.  sporogenes. 

There  are  at  least  two  distinct  strains,  A  and  B,  which  produce 
specific  and  heterologous  toxins  and  antitoxins-;  that  is,  the  antitoxin  of 
strain  A  does  not  neutralize  the  toxin  of  strain  B,  and  the  antitoxin  of 
strain  B  does  not  neutralize  the  toxin  of  strain  A. 

The  habitat  of  B.  botulinus  in  nature  is  not  definitely  known.  It 
is  assumed  to  be  an  intestinal  and  soil  organism,  like  tetanus,  the  gas 
bacillus,  and  other  anaerobes.  Mrs.  Burke  "'^  has  recently  thrown  light 
upon  the  occurrence  of  B.  botulinus  in  nature.  In  five  different  locali- 
ties in  central  California  she  made  235  cultures  from  a  wide  range  of 
material.  Seven  of  the  cultures,  taken  from  bean  plants,  moldy  hay, 
bush  beans,  cherries  and  spiders,  contained  B.  botulinus.  Some  of  these 
things  were  contaminated  with  the  feces  of  insects  and  birds.  Graham 
encountered  B.  botulinus  in  relatively  large  numbers  in  animal  foods, 
including  ensilage,  oats,  hay,  corn  fodder  and  bran,  in  Kentucky  and 
Illinois.  Such  observations  demonstrate  the  possible  wide  distribution 
of  the  organism  and  the  fact  that  it  may  be  present  on  fruits  and  vege- 
tables before  they  are  picked.  It  also  suggests  that  insects  or  birds  may 
act  as  carriers,  a  possibility  which  is  rendered  more  probable  by  the 
discovery  of  B.  botulinus  in  forage  contaminated  with  chicken  feces. 

Evidence  is  increasing  that  Bacillus  botulinus  is  associated  with 
animal  manure  and  that  the  spores  are  widely  distributed  in  nature, 

^J.  Bact.,  IV,  541,  Sept.,  1919, 


712 


GENEEAL  CONSIDERATIONS 


in  dirt  and  dust.  They  appear  to  be  more  abundant  in  some  localities 
than  in  others.^" 

Thermal  Death  Point  of  the  Spore. — To  safeguard  against  botulism 
in  canned  foods,  the  thermal  death  point  of  the  spore  was  determined 
in  my  laboratory  by  Weiss.^^  The  various  factors,  such  as  age  of  the 
spore,  number  of  spores,  strain  differences,  hydrogen  ion  concentration, 
effect  of  desiccation,  etc.,  which  influenced  the  thermal  death  point  were 
also  determined. 

Weiss  found  that  suspended  in  water,  the  most  resistant  typ«s 
require  five  hours  at  boiling  temperature,  40  minutes  at  105°   C,  15 


ul20 

Q 

< 

a. 
o 

1- 
z 
u 

UII5 

if) 

U 

u 
cr 

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o 
u 

\ 

z 

\ 

u 
a 

\ 

\ 

a 

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UJ 

X 

■^ 

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) 

■^ 

V 

5 

TIME     IN    HOURS 

Fig.  75. — Cueve  I,  Showing  Thermal  Death  Point  of  Bacillus  Botulinus. 

minutes  at  110°  C,  and  6  minutes  at  120°  C.  These  represent  bath 
temperatures  and  include  the  time  necessary  to  heat  the  spore  itself 
to  the  temperatures  stated.  Weiss  further  found  that  young  spores 
are  more  resistant  than  old  spores;  that  dry  spores  are  much  harder 
to  kill  than  moist  spores;  and  that  acids,  alkalies  and  various  chemicals 
greatly  diminish  the  thermal  resistance. 

Toxin. —  The  bacillus  produces  a  soluble,  true  exotoxin  ^^  com-' 
parable  in  all  respects  to  the  poisons  produced  in  cultures  of  diphtheria 
or  tetanus.     The  botulinus  toxin  is  the  only  one  of  the  true  toxins  that 

'"Meyer,  K.  F. :     The  Distribution  of  the  Spores  of  B.  Botulinus  in  Nature. 
Public  Health  Reports,  .Jan.  7,  1921,  Vol.  XXXVI;  No.  1,  p.  4. 
^^Jour.  Infect.  Dis.,  28,  I,  .Jan.   1,  1921,  p.  70. 
'"  For  definition  of  a  true  toxin,  see  page  553,  et  seq. 


FOOD  POISONING  713 

is  poisonous  when  taken  l)y  the  niniith.  It  is  tlius  pathogenic  for  guinea- 
pigs,  mice,  and  nionkev!?,  as  well  as  fur  man.  One  or  two  drops  of  a  cul- 
ture placed  u})un  a  piece  of  hread  causes  death  in  a  few  days.  Toxins  of 
diphtheria   and   tetanus  are  not  poisonous  when   taken   hy   the  mouth. 

The  toxin  is  secreted  hy  the  hacillus  when  it  grows  upon  a  suitable 
medium,  under  anaerobic  conditions.  Some  strains  do  not  })ro(liue  toxin, 
and  the  property  may  be  lost  after  prolonged  artificial  cultivation.  Toxin 
production  takes  place  between  20°  and  30°  C,  but  best  at  37°  C. ; 
this  is  contrary  to  our  previous  conception.  It  has  always  been  believed 
that  B,  botulinus  is  strictly  saprophytic  and  will  not  develop  and  pro- 
duce its  toxin  in  the  body,  the  toxin  being  alw-ays  preformed  in  food- 
stuffs, but  the  recent  work  of  Orr  ^^  in  my  laboratory  shows  that 
guinea-pigs  and  mice  may  develop  botulism  when  fed  with  large  quan- 
tities of  toxin-free  spores.  The  significance  of  this  observation  to  human 
botulism  must  await  further  study.  • 

Botulinus  toxin  is  exceedingly  poisonous.  It  has  been  possible  to 
obtain  a  toxin  of  which  0.000001  c.c.  would  kill  a  '^oO-gram  guinea- 
pig  in  from  3  to  4  days.^*  In  the  Ellezelles  outbreak,^^  aljout  ?00  grams 
of  the  poisonous  ham  were  sufficient  to  cause  the  death  of  one  of  the  pa- 
tients; in  the  Darmstadt  outbreak,^"  a  piece  of  preserved  duck  the  size 
of  a  w^alnut  was  sufficient  to  cause  an  illness  which  lasted  for  8  weeks. 
In  Dickson's  series  of  cases,  one  patient  died  after  "nibbling"  a  portion 
of  a  pod  of  the  spoiled  string  beans,  one  died  after  tasting  a  small  spoon- 
ful of  the  spoiled  corn,  and  a  third  was  ill  after  tasting  a  pod  of  beans 
which  she  did  not  swallow. 

Strong  toxin  was  produced  by  Dickson  in  pork  and  beef  infusion, 
and  also  in  media  prepared  from  string  beans,  green  corn;  much  less 
virulent  toxins  were  obtained  in  media  prepared  from  asparagus,  arti- 
chokes, apricots,  and  crushed  apricot  stones.  The  most  powerful  poisons 
are  produced  in  glucose  broth.  The  toxin  is  not  formed  in  brine  con- 
taining over  8  per  cent,  of  sodium  chlorid.  This  is  of  practical  impor- 
tance in  pickling  foods. 

Van  Ermengem  ^'  showed  that  the  toxin  was  destroyed  by  heating  at 
80°  C.  for  one-half  hour,  and  many  later  workers  have  verified  this, 
showdng  in  fact  that  there  is  a  large  margin  of  safety  in  such  a  pro- 
cedure. Thom,  Edmondson  and  Giltner  ^*  showed  that  the  toxin  of 
the  Boise  strain  is  destroyed  at  some  point  between  70°  C.  and  73°  C. 
by  heating  for  10  minutes.     Orr  ^^  showed  that  the  most  resistant  of 

^Proc.  Soc.  Biol,  and  Med..  1919,  XVII.  p.  47. 

^  Deutsch.  med.  Woch..  1897,  XXIII,  521. 

^  Arch.  Pharmacod.,   1897.  Ill,  213. 

'^Detitsch.  med.  Woch..  1897.  XXIII,  521. 

"Arch,  pharm..  1897.  III.  213. 

=»./.  A.  M.  A..  Sept.  20,  1919,  LXXIII,  p.  907. 

^Jour.  Med.  Research,  Vol.  XLII,  Xos.  2  and  3,  Xov.,  1920,  and  Jan.,  1921. 


714 


GENERAL  CONSIDERATIONS 


the  ten  strains  of  toxin  studied  by  him  is  destroyed  when  exposed  to 
80"  C.  for  two  minutes,  72°  C.  for  ten  minutes,  and  65°  C.  for  85 
minutes.  The  toxins  of  most  strains  are  killed  at  65°  C.  in  thirty 
minutes.  Cooking  therefore  is  a  safeguard.  The  toxin  in  solution  is 
very  resistable  to  exposure  to  light  and  air.  It  is  not  affected  by 
drying  or  putrefaction. 

The  toxin  has  a  special  affinity  for  the  central  nervous  system ;  it  is 
almost  a  pure  neurotoxin.  It  also  acts  upon  the  blood  vessels,  causing 
dilatation,  thrombi  and  hemorrhages  in  various  portions  of  the  body. 


40  50  60 

TIME    IN    MINUTES 


Fig.    76. — Curve   II,    Showing    Rate   of    Destruction    of   Botuxinus    Toxin. 


Van  Ermengem  ^°  found  that  white  mice,  gumea-pigs,  rabbits,  cats, 

pigeons,  and  monkeys  are  susceptible  to  subcutaneous,  intraperitoneal, 

and  intravenous  injection,  and  that  white  rats,  dogs,  chickens,  frogs  and 

fish  are  highly  resistant.     In  his  feeding  experiments,  he  found  that 

mice,  guinea-pigs,   and  monkeys  are  especially  susceptible,  rabbits  are 

less   susceptible,   and  cats  must  be   given   enormous   quantities   of   the 

toxin  before  they  show  any  symptoms.     He  found  that  dogs,  rats,  and 

chickens  are  practically  unaffected,  the  only  result  of  feeding  very  large 

doses  being  vomiting,  diarrhea  and  emaciation.     It  is  surprising  that 

van  Ermengem  failed  to  obtain  positive  results  in  his  experiments  with 

dogs  and  chickens,  as  Dickson  and  others  have  found  that  botulism  may 

''"Arch.  Pharm.,  1897,  III,  213;  Z.  Eyg.  u.  Infektionskrankh.,  1807,  XXXVI, 
1 ;  "Handbuch  der  nathegenen  Mikroorganismen,"  Kolle  u.  Wassermann,  Jena,  2nd 
ed.,  1912,  IV,  909. 


FOOD  POISONING  715 

t'aiiso  Iinil)er  lUH'k  in  chickens  and  turkeys.  Horses,  goats  and  other  ani- 
mals are  susceptible. 

Kvcrv  strain  of  Bacilhis  hotulinus  does  not  produce  toxin.'''  Thus, 
Orr  found  only  10  of  21  strains  to  ])roduce  toxin.  FurthcrnKiif,  there 
are  at  least  two  distinct  toxins — each  of  wliicli  jn-oduces  a  specific 
antitoxin. 

Antitoxin. —  A  true  antitoxin  may  l)e  obtained  by  injecting  increas- 
ing amounts  into  susceptible  animals.  Kempner  first  obtained  the  anti- 
toxin in  goats.  It  is  now  made  by  injecting  horses.  The  hotulinus  anti- 
toxin has  both  protective  aiul  curative  virtues  'in  experimental  animals, 
even  when  given  24  hours  after  the  ingestion  of  the  poison,  hut  before 
the  onset  of  symptoms.  For  practical  purposes  at  least  two  antitoxins 
must  be  on  hand,  one  made  by  strain  A,  and  the  other  by  strain  B, 

Like  other  antitoxins,  the  hotulinus  antitoxin  must  be  given  very 
early  if  it  is  to  be  effective,  and  it  is  probable  that,  as  in  tetanus,  it 
is  too  late  when  the  symptoms  of  poisoning  are  established.  The  occur- 
rence of  limber  neck  in  domestic  fowl,  if  it  develops  after  they  have  eaten 
refuse  from  the  kitchen,  should  be  sufficient  reason  for  administering 
hotulinus  antitoxin  to  all  persons  who  have  eaten  any  of  the  suspected 
food.  The  presence  and  type  of  toxin  in  food  can  be  determined  in  a 
few  hours  by  injecting  mice  intraperitoneally.  Some  of  the  mice  should 
be  immunized  with  antitoxin  Type  A  and  some  with  Type  B.  Etheriza- 
tion delays  intoxication ;  alcohol  precipitates  the  toxin  in  vitro  and  in 
the  stomach. 

Food  Involved  in  Botulism. — It  was  originally  thought  that  B. 
hotulinus  would  grow  only  in  sausage  or  meat,  but  it  is  now  known 
that  the  presence  of  animal  protein  is  not  necessary  for  its  growth.  In 
Europe,  the  foods  involved  -in  outbreaks  have  been  mainly  meats,  such 
as  sausage  and  ham,  but  in  this  country  other  foods  have  been  involved, 
such  as  string  beans,  cottage  cheese,  corn,  asparagus  salad,  spinach  and 
ripe  olives.  Botulism  has  also  been  attributed  to  turkey,  beef,  chicken 
and  fish. 

Suspicion  often  falls  upon  the  wrong  food.  The  period  of  incuba- 
tion is  usually  from  18  to  36  hours,  and  the  first  symptom  may  be 
nausea  and  vomiting.  Several  meals  will  have  been  taken  between  the 
time  of  eating  the  toxic  food  and  the  onset  of  initial  symptoms.  The  food 
•vomited  is  naturally  accused.  This  mistake  was  made  in  the  Detroit 
outbreak,  where  corn  was  suspected  because  it  was  found  in  the  vomitus, 
whereas  the  trouble  really  came  from  ripe  olives  eaten  the  day  before. 

Most  cases  of  botulism  are  caused  by  food  that  has  received  some 
preliminary  treatment,  as  smoking,  canning  or  pickling,  and  not  in 
fresh  food.  Home  packed  foods  have  been  especially  responsible,  for 
the  reason  that  they  are  often  a  day  or  more  old  when  put  up,  and  the 

°  Non-toxic  strains  closely  resemble  B.  sporogenes. 


716  GENEEAL  CONSIDERATIONS 

temperature  of  processing  is  frequently  not  sufficient  to  kill  the  botulinus 
spores.  All  the  olive  cases  were  due  to  ripe  olives,  put  up  in  glass,  and 
improperly  processed. 

Van  Ermengem  found  that  the  outbreak  in  Ellezelles  was  caused  by 
eating  ham  which  had  been  preserved  in  brine.  Smoked  as  well  as 
pickled  ham  has  been  responsible.  In  Eussia  fish  has  conveyed  the 
poison.  Madsen  also  isolated  B.  botulinus  from  poisonous  fish.  A 
most  interesting  outbreak  occurred  in  Darmstadt  in  1904,  caused  by  a 
salad  prepared  from  home  canned  white  beans. 

Sausages  are  a  frequent  source  of  botulism  in  Germany.  The  sausages 
readily  become  infected  and  present  ideal  anaerobic  conditions  for  the 
growth  of  the  organism,  especially  as  they  are  rarely  refrigerated  and 
frequently  contain  old  and  contaminated  scraps.  The  disease  is,  there- 
fore, frequently  called  sausage  poisoning.  Certain  sausages,,  as,  for  ex- 
ample, the  blood  sausage  and  the  liver  sausage  prepared  in  Wii.rttem- 
berg  and  Baden,  are  especially  a-pt  to  be  infected.  Venison  and  old 
roasts  have  also  produced  the  intoxication. 

No  reliance  can  be  placed  upon  odor,  taste  or  appearance  to  detect 
the  toxin  of  botulism  in  food.  It  is  true  that  in  many  instances  a  his- 
tory is  obtained  that  the  responsible  food  looked  spoiled,  tasted  wrong, 
or  smelled  tainted.  Experts  can  detect  the  peculiar  butyric  acid  smell 
of  cultures  of  botulinus,  but  we  found  in  my  laboratory  that  some  strains 
produce  little  or  no  odor.  A  safe  rule  is  not  to  eat  food  that  is  soft, 
mushy,  and  shows  gas  with  a  spoiled  or  putrefactive  odor.  Canned  food 
that  shows  gas  formation  or  other  evidence  of  spoilage  should  not  be 
eaten,  especially  if  home  processed.  A  very  small  amount  of  the  toxin- 
containing  food  is  sufficient  to  cause  symptoms  and  death.  Merely  tast- 
ing the  contents,  or  just  "nibbling"  the  food  has  been  fatal. 

Prevention. — The  prevention  of  botulism  consists  in  greater  care 
and  cleanliness  in  the  handling  and  preservation  of  nitrogenous  food- 
stuffs. The  bacillus  will  grow  and  produce  toxin  only  in  foods  contain- 
ing protein.  There  is  no  danger  of  botulism  in  fresh  food.  In  all 
instances,  the  trouble  comes  from  food  that  has  been  pickled,  canned 
or  preserved  in  some  way,  such  as  pickled  ham,  home  processed  beans, 
sausages,  etc.  Home  canned  foods  are  often  at  fault.  It  is  therefore 
important  to  teach  safe  methods  of  home  canning,  especially  the  im- 
portance of  putting  up  only  fresh  and  clean  food,  heated  sufficiently  to 
kill  the  spores — 120°  C.  for  10  minutes.  Canned  foods  should  be 
processed  at  a  temperature  sufficient  to  kill  botulinus  spores,  and  to 
render  the  contents  of  the  can  sterile.     The  cans  should  be  tight. 

Food  that  is  allowed  to  stand  around  after  cooking  allows  bacterial 
growth,  unless  kept  in  the  ice  box,  with  a  temperature  at  or  near  freez- 
ing. The  importance  of  proper  refrigeration  to  prevent  botulism,  as 
well  as  other  bacterial  contamination,  is  evident. 


DECOMPOSED  FOODS  717 

Cooking  is  a  safeguard,  hut  it  must  Ijc  thorough  and  suHicient  to 
kill  the  toxin — 80°  C.  fur  10  minutes.  If  the  food  is  kept  at  ordinary 
temperatures  after  cooking,  hotulinus  and  other  organisms  may  grow 
and  may  cause  trouble.  To.xin  may  re-form  in  cooked  food  allowed  to 
stand  24  hours  at  room  temperature.  Home  canned  goods,  or  any 
other  processed  goods,  should  be  again  cooked  just  before  serving. 
Food  preserved  in  a  brine  of  8  per  cent,  or  greater  is  safe,  for  the 
toxin  does  not  form  in  salt  solution  of  this  concentration.  A  syrup  of 
at  least  50  per  cent,  glucose  has  been  found  necessary  to  inhibit 
growth. 

No  reliance  should  be  placed  upon  odor,  taste  or  appearance  of  tlie 
food;  on  the  other  hand,  no  food,  whether  canned  or  processed  in  any 
other  way,  should  be  consumed  if  it  shows  evidence  of  spoilage.  Edu- 
cation, therefore,  with  emphasis  upon  proper  methods  of  handling,  pre- 
serving, canning,  washing  and  cooking  food,  is  important. 

The  occurrence  of  limber  neck  in  domestic  fowl,  if  it  has  developed 
after  they  have  eaten  refuse  from  the  kitchen,  may  be  an  indication  for 
the  prophylactic  administration  of  the  botulinus  antitoxin  to  all  per- 
sons who  have  eaten  the  suspected  food. 

When  a  case  of  botulism  occurs,  other  persons  who  may  have  eaten 
the  suspected  food  should  receive  a  prophylactic  dose  of  botulinus  anti- 
toxin ;  both  strains  A  and  B  should  be  used.  The  serum  is  of  little  avail 
after  symptoms  have  begun. 


DECOMPOSED  FOODS 

Decomposition  is  defined  as  natural  decay.  In  this  sense  all  or- 
ganic substances,  both  animal  and  vegetable,  living  or  dead,  are  decom- 
posed, for  decomposition  and  recomposition  occur  as  a  constant  feature 
of  life's  processes.  At  the  moment  of  death  recomposition  ceases,  while 
decomposition  continues.  In  one  sense  the  hardest  rocks  decompose 
or  disintegrate;  bicarbonate  of  soda  decomposes  in  the  presence  of  an 
acid,  and  many  substances  decompose  in  the  presence  of  oxygen,  es- 
pecially when  heated.  In  other  words,  while  decomposition  is  usually 
the  result  of  bacterial  activity  in  organic  substances,  it  may  also  take 
place  as  the  result  of  physical,  chemical,  or  electrical  agencies."  The 
word  "decomposition"  is  not  used  in  this  technical  sense  in  the  Pure 
Food  and  Drugs  Act;  there  it  has  the  meaning  of  the  word  used  in 
ordinary,  every-day  parlance.  Just  where  technical  decomposition  ceases 
and  objectionable  decomposition  begins  is  often  difficult  to  determine. 
Decomposition  may  be  objectionable  either  to  the  senses  or  to  health. 
We  purpo.-ely  permit  many  of  our  foods  to  decompose  before  they  are 
used.     Thus,  meats  hang  three  days  or  longer  in  order  to  render  them 


718  GENERAL  CONSIDERATION'S 

more  tender  and  to  improve  their  flavors.  During  this  time  decom- 
position takes  place  with  the  production  of  acids.  Some  persons  prefer 
meats  when  highly  decomposed  or  gamy.  Bread,  cheese,  butter,  butter- 
milk, sauerkraut,  vinegar,  cider,  and  many  other  foods  are  products 
of  decomposition.  The  line  must,  therefore,  be  drawn  between  decom- 
position that  is  objectionable  and  decomposition  that  is  technical.  It  is 
difficult  to  draw  the  line  at  decomposition  that  is  objectionable  to  the 
senses,  for  a  cheese  regarded  as  a  delicacy  by  one  person  may  be  highly 
objectionable  to  another.  The  principal  point,  then,  for  consideration 
is  the  decomposition  that  is  harmful  to  health. 

Fermentation  and  Putrefaction. — The  question  is  further  compli- 
cated when  we  consider  that  there  are  very  many  kinds  of  decomposi- 
tion. Two  main  groups  are  recognized:  (1)  fermentative  decomposi- 
tion, and  (2)  putrefactive  decomposition. 

Fermentation  refers  to  the  breaking  down  of  carbohydrates  with  the 
formation  of  acids   (lactic,  acetic, -butyric),  alcohol,  carbon  dioxid,  etc. 

Putrefaction  (putrere,  to  be  rotten)  is  literally  a  process  of  rot- 
ting or  offensive  decay.  Putrefaction  is  generally  restricted  to  include 
only  those  processes  of  protein  disintegration  which  give  rise  to  foul- 
smelling  products.  For  practical  purposes,  it  consists  of  the  decompo- 
sition of  organic  matter,  usually  protein  in  character,  due  to  bacterial 
action. 

Pasteur  first  pointed  out  that  putrefaction  is  essentially  an  anaerobic 
process.  This  has  since  been  abundantly  confirmed.  Rettger  insists 
that  putrefaction  is  the  work  of  certain  obligate  anaerobes,  which  are 
able  to  initiate  and  carry  on  the  decomposition  of  native  protein.  B. 
putrificus,  B.  edematis  maligni,  and  B.  anthracis  symptomatici  are  the 
best  examples.  B.  tetani  does  not  have  a  place  in  this  group.  B.  per- 
fringens,  the  gas  bacillus  of  Welch,  has  only  a  limited  if  any  proteolytic 
action.  Certain  aerobes,  such  as  the  proteus  family,  the  colon  group, 
and  the  subtilis  group,  also  play  a  part,  although  they  cannot  initiate 
changes  in  protein. *^^ 

The  end  products  of  putrefaction  are  ammonia,  nitrates,  carbon 
dioxid,  sulphureted  hydrogen,  methane,  etc.,  all  simple,  stable,  inor- 
ganic compounds  which,  in  ordinary  concentration,  are  not  poisonous. 
It  is  then  the  intermediate  cleavage  products  of  putrefaction  and  the 
end  products  of  fermentation  that  may  be  poisonous.  The  question  of 
decomposition  is  still  further  complicated  by  the  fact  that  there  are 
very  many  different  kinds  of  fermentation  and  of  putrefaction.  Each 
particular  microorganism  breaks  down  organic  matter  in  a  specific  and 
limited  sense.  Ordinarily  these  processes  result  from  a  combination  of 
bacterial  action   (symbiosis),  in  which  aerobic  and  anaerobic  organisms 

"^  Bienstock,  Arch,  of  Eyg.,  XXXI,  p.  335,  1889,  and  XXXIX,  p.  390,  1901; 
also  Rettger,  Jowrn.  Biol.  Chem.,  II,  p.  71,  1906,  and  IV,  p.  5,  1908. 


DECOMPOSED  FOODS  719 

each  play  a  part.  As  a  riili>,  put  refaction  docs  not  take  place  in  the 
presence  of  fermentation.  In  this  sense  carbohydrates  protect  nitro- 
genous matter. 

Putrefactive  Changes  in  Proteins. — To  understand  clearly  the  deg- 
radation changes  in  proteins  as  a  result  of  putrefaction  it  is  necessary  to 
give  a  brief  account  of  the  composition  of  the  animal  proteins  and  their 
simpler  cleavage  products. 

The  proteins  are  highly  complex  compounds  of  C,  H,  0,  X  and  S, 
belonging  for  the  most  part  to  the  colloids.  The  protein  molecule  is 
a  very  large  one.  Some  fifty  or  so  natural  proteins  are  known,  occur- 
ring in  both  animals  and  plants,  and  they  are  classified  according  to  their 
origin,  solubility  in  solvents  such  as  water,  saline  solutions  and  alcohol, 
coagulability  on  heating  and  other  physical  characters. 

The  work  of  Emil  Fischer  and  his  pupils  has  confirmed  and  elabo- 
rated the  theory  originally  propounded  by  Hofmeister,  that  the  protein 
molecule  is  built  up  of  a  series  of  amino-acids  forming  a  class  of  prod- 
ucts which  have  been  designated  the  polypeptids  by  Fischer.  Such 
polypeptids  form  the  essential  part  of  the  structure  of  the  protein  mole- 
cule, but  it  may  contain  other  groups,  such  as  phosphoric  acid  and  pos- 
sibly also  carbohydrates  and  lipoids. 

The  amino-acids  are  bodies  in  which  a  XHj  group  (the  amino  group) 
is  substituted  for  a  hydrogen  atom  of  the  carbon  group  nearest  the  acid 
radical.  For  example,  acetic  acid  is  a  simple,  fattv'-  acid  with  the  for- 
mula CH3 — COOH,  while  CHjXHg — COOH  is  amino-acetic  acid  or 
gl)'cocoll.  The  aromatic  amino-acids  are  those  in  which  amino-acids  are 
united  to  the  benzene  ring.  Tyrosin  belongs  to  this  group.  The  gen- 
eral formula  of  the  monoamino  acids  may  be  stated  as  E  —  CH--,__^ 

—  JN  xlj 

where  E  may  be  of  very  simple  or  very  complicated  structure;  for  ex- 
ample, simple  chains  as  in  leucin,  members  of  the  aromatic  series  as 
in  tyrosin  or  tryptophan  or  sulphur-containing  bodies. 

In   the   diamino-acids  two   hydrogen   atoms   are   replaced   by    XH2 

groups  and  these  have  the  general  formula  E — C — COOH.     Lysin  and 

XXH2 
argiiiin  belong  to  this  group. 

Under  the  influence  of  chemical  agencies,  such  as  acids  or  alka- 
lies, physical  agencies,  such  as  superheated  steam,  the  action  of  digestive 
or  other  ferments  or  the  activities  of  bacteria,  the  protein  molecule  is 
decomposed  and  various  cleavage  products  form.  These  substances  may 
be  classed  as  primary  cleavage  products,  i.  e.,  those  which  exist  as 
radicals  within  the  molecule,  or  as  secondary  products,  i.  e.,  those  not 
existing  preformed  in  the  molecule  but  formed  by  transformation  of 
the  primary  products. 


720  GENERAL  CONSIDERATIONS 

"When  the  protein  molecule  is  broken  down  in  the  laboratory  by 
processes  similar  to  those  brought  about  by  the  digestive  enzymes  which 
occur  in  the  alimentary  canal,  the  essential  change  is  due  to  what  is 
called  hydrolysis:  that  is,  the  molecule  unites  with  the  water  and  then 
breaks  up  into  smaller  molecules.  The  first  cleavage  products,  which 
are  called  proteoses,  retain  many  of  the  characters  of  the  original  pro- 
tein; and  the  same  is  true,  though  to  a  less  degree,  of  the  peptones, 
which  come  next  in  order  of  formation.  The  peptones  in  their  turn 
are  decomposed  into  short  linkages  of  ami  no-acids  which  are  called 
polypeptids,  and  finally  the  individual  amino-acids  are  obtained  sep- 
arated from  each  other"  (Halliburton,  1916). 

It  is  important  to  realize  that  whatever  method  is  used  to  decompose 
the  protein  molecule  the  process  goes  through  all  these  stages  and  ap- 
proximately quantitatively  as  well  as  qualitatively.  DifferenJ;  agencies, 
however,  carry  the  process  to  difi^erent  stages  and  the  characteristic 
chemical  products  brought  about  .by  putrefactive  bacteria  are  due  to 
their  carrying  the  processes  further  and  causing  extensive  secondary 
cleavage  changes. 

The  conversions  into  proteoses,  peptones  and  amino-acids  are  there- 
fore changes  which  are  common  to  all  methods  by  which  the  protein 
molecule  is  decomposed,  and  chief  interest  centers  upon  the  further 
changes  in  the  amino-acids  brought  about  by  the  putrefactive  bacteria. 
Bacteria  (and  fungi)  are  peculiar  in  being  able  to  break  down  the 
amino-acids  into  bases  and  acids  which,  in  general,  have  not  been 
demonstrated  as  products  of  the  metabolism  of  animals  and  the  higher 
plants. 

As  long  ago  as  1902  Czapek,  and  also  Emmerling,  pointed  out  that 
the  amino-acids  furnish  bacteria  with  abundant  and  available  nutritive 
material.  The  amino-acids  are  non-toxic  bodies  and  include  substances 
such  as  glycin  (amino-acetic  acid),  alanin  (aminopropionic  acid), 
leucin  (iso-butjd-a-amino-acetic  acid),  tyrosin,  cystin,  aspartic  acid,  glu- 
tamic acid,  histidin  and  tryptophan. 

The  secondary  degradation  products  which  result  include  bodies 
such  as  indol,  skatol,  skatolcarboxylic  acid,  skatolacetic  acid,  phenyl- 
propionic  acid,  phenylacetic  acid,  /?-cresol  and  phenol.  In  addition  a 
number  of  simple  bodies,  such  as  ammonia,  methane,  carbon  dioxid, 
sulphureted  hydrogen,  hydrogen,  etc.,  are  formed  as  end  products. 

The  precise  chemical  bodies  which  will  be  formed  will  depend  upon 
a  number  of  factors,  such  as  the  character  of  the  bacteria  concerned, 
the  conditions  of  growth  (especially  as  regards  the  presence  or  absence 
of  oxygen),  the  available  sources  of  nutriment  other  than  the  amino- 
acids,  the  temperature  and  the  stage  of  the  process. 

Hopkins  and  Cole  (1903),  for  example,  studied  the  changes  pro- 
duced in  chemically  pure  tryptophan  by  putrefaction.     They  obtained 


DECOMPOSED  FOODS  721 

indol,  skatol,  and  skatolcarbonie  acid  by  the  action  of  aerobic  bacteria 
and  skatolacetic  acid  with  anaerobic  organism-?,  in  this  way  showing 
that  the  tryptophan  radical  is  the  precursor  of  these  substances  in  pu- 
trefaction. 

In  the  same  way  ty rosin  is  the  precursor  of  phenol,  paracresol,  para- 
oxyphcnylacetic  acid  and  other  bodies. 

Most,  if  not  all,  of  the  sulphur  in  the  protein  molecule  is  contained 
in  the  amino-acid  cystin  and  the  offensive  sulphur-containing  bodies, 
such  as  hydrogen  sulphid,  methyl  mercaptan  (CH3SH)  and  ethyl  mer- 
captan,  produced  during  putrefaction  are  due  to  the  breaking  down  of 
this  amino-acid. 

In  addition  to  these  numerous  products  a  very  definite  group  of 
bodies,  chemically  of  the  nature  of  amins,  are  formed  in  the  later 
stages  of  putrefaction,  and  to  these  bodies,  owing  to  the  toxicity  pos- 
sessed by  some  of  them,  the  very  greatest  importance  has  been  attached 
as  a  cause  of  bacterial  food  poisoning. 

A  very  characteristic  action  of  putrefactive  bacteria  generally  is 
their  power  to  split  off  carbon  dioxid  from  the  carboxyl  (COOH)  group 
of  the  amino-acids  with  the  production  of  amins  according  to  the  fol- 
lowing equation: 

XH2  —  E  —  COOH  :=  XH3  —  E  —  H  +  CO,. 

In  this  way  a  whole  series  of  bodies  is  formed  which  include  the 
ptomains  of  Selmi  and  Brieger  and  other  bases,  some  of  which  were 
claimed  to  exert  a  poisonous  action  on  man  and  animals.  This  de- 
carboxylation of  amino-acids  seems  to  be  a  general  reaction  of  a  good 
many  putrefactive  organisms. 

As  examples  of  such  changes  it  may  be  mentioned  that  diamino- 
valeric  acid  is  converted  into  putrescin,  diaminocaproic  acid  (lysin) 
into  cadaverin,  and  tyrosin  into  tyramin.  In  the  same  way  the  poi- 
sonous and  probably  important  body  B-imidazolethylamin  (histamin) 
is  the  amin  of  histidin.  The  decarboxylation  of  amino-acids  is  not 
necessarily  accompanied  by  a  putrefactive  odor  or  other  obvious  signs 
of  bacterial  action. 

"Ptomain"  Poisoning. — Ptomains  are  secondary  cleavage  products 
of  protein  putrefaction.  Yaughan  defines  a  ptomain  as  an  organic 
chemical  compound,  basic  in  character,  and  formed  by  the  action  of 
bacteria  on  nitrogenous  matter.  On  account  of  their  basic  properties 
ptomains  give  some  of  the  reactions  of  the  vegetable  alkaloids  and  have, 
therefore,  been  called  putrefactive  alkaloids.  They  are  sometimes  called 
"animaF'  alkaloids,  but  this  is  a  misnomer,  for  they  also  are  formed  in 
the  putrefaction  of  vegetable  protein. 

The  term  "leukomain"  is  used  to  cover  the  same  or  similar  basic 
substances  which  result  from  tissue  metabolism  within  the  body;  that 


723  GENEEAL  CONSIDERATIONS 

is,  leukomains  are  produced  in  the  living  body,  ptomains  in  dead  or- 
ganic matter. 

The  word  "ptomain"  was  coined  by  the  Italian  toxicologist  Selmi, 
in  1870,  from  ptoma,  a  corpse.  He  used  the  term  to  describe  basic 
poisonous  products  analogous  to  the  familiar  alkaloids  of  plant  origin. 
The  further  exploitation  of  the  expressive  word  "ptomain"  was  largely 
the  outcome  of  studies  by  Gautier  in  1872,  who  also  introduced  the  term 
"leukomains." 

The  great  majority  of  ptomains  are  not  poisonous  or  less  toxic 
than  the  corresponding  ammonia  compound.  Ptomains  include  sub- 
stances which  are  chemically  very  different.  The  classification  is  not 
a  scientific  one,  and  is  gradually  being  abandoned.  In  fact,  it  is  known 
that  cases  of  so-'=.alled  ptomain  poisoning  are  really  infections  with  mi- 
croorganisms belonging  to  the  Gaertner  bacilli. 

Chemically,  ptomains  are  ammonia  substitution  compounds ;  two- 
thirds  of  them  contain  only  carbon,  hydrogen,  and  nitrogen.  Those 
having  oxygen  in  their  composition  are  the  more  poisonous.  Most 
ptomains  are  inert  or  are  no  more  poisonous  than  the  corresponding 
ammonia  salts.  In  composition  they  show  a  predominance  of  the 
amin  radicle  (TsTHg).  Of  the  bases  containing  oxygen,  most  of  them 
are  trimethylamins  [(CH3)3]Sr].  It  was  Brieger  who  pointed  out  that 
a  certain  quantity  of  oxygen  is  necessary  for  the  formation  of  poison- 
ous bases.  These  poisonous  bases  appear  about  the  seventh  day  of  pu- 
trefaction and  then  disappear. 

It  is  important  to  remember  that  ptomains,  in  sharp  contradistinc- 
tion to  toxins,  are  non-specific,  that  is,  they  are  not  the  products  of  in- 
tracellular metabolism  characteristic  of  the  microorganisms  which  pro- 
duce them.  They  are  merely  degradation  products  of  the  protein  mole- 
cule and  are  elaborated  by  all  bacteria  that  are  capable  of  producing 
this  degree  of  protein  cleavage  when  grown  on  suitable  nutrient  me- 
dium and  under  favorable  conditions  of  growth.  They  may  be  produced 
by  bacteria  which  possess  no  pathogenic  power,  while  on  the  other 
hand  highly  pathogenic  bacteria  which  are  not  active  in  attacking  pro- 
tein may  produce  little  or  no  ptomains. 

The  term  "ptomain  poisoning"  is  a  misnomer.  A  study  of  this 
subject  for  over  three  years  has  convinced  me  that  there  is  no  such 
thing.  Savage  states  that  the  term  "ptomain  poisoning"  is  clearly  in- 
correct, and  Jordan  states  that  "ptomain  poisoning"  is  a  refuge  from 
etiologic  uncertainty.  Vaughan  agrees  with  Jordan  and  Savage  that 
the  term  "ptomain  poisoning"  is  incorrect  and  should  not  be  applied 
to  food  poisoning.  Novy  states  that  "the  rather  popular  expression 
'ptomain  poisoning'  is  a  survival  of  the  period  when  it  was  believed 
that  bacteria  produced  their  injurious  effects  by  means  of  basic  or 
alkaloid-like  products.     Long  ago  the  importance  of  ptomains  disap- 


DECOMPOSED  FOODS  723 

pearecl;,  due  in  tlie  llrst  i)I;ui'  to  the  discovery  of  toxins,  and  in  tlie 
second  place  to  the  fact  that  these  substances  are  not  secondary  products 
of  protein  cleavage."  Chapin  states  that  "ptomain  poisoning"  is  a 
good  term  to  forget.  Vaughan,  m  1895,  detected  in  poisonous  cheese 
an  active  agent  to  which  he  gave  the  name  tyrotoxicon.  However, 
he  afterwards  admitted  that  this  is  not  the  subject  most  commonly 
found  in  poisonous  cheese,  although  the  names  tyrotoxicon  and  pto- 
main poisoning  remain  in  popular  parlance.  Even  the  poisonous  pto- 
mains  arc  toxic  only  when  injected  into  animals  and  not  when  given  by 
the  mouth.  The  symptoms  produced  have  no  resemblance  to  cases  of 
food  poisoning. 

It  is  not  decomposed  but  infected  food  that  may  be  dangerous. 
•     Owing  to  the  importance  which  is  still  attached  by  some  to  these 
bodies   and   their   historical   interest,   particulars   of  a   few   are  given. 
See  Yaughan  and  Xovy's  book,  Cellular  Toxins  (1903). 

Metliylamin,  CHgjSTHg. — This  is  the  simplest  amin  and  has  been 
obtained  from  decomposing  herring,  haddock  and  other  fish.  It  does 
not  possess  any  toxic  action  and  very  similar  remarks  apply  to  di-  and  tri- 
ineth3damin  and  to  ethylamin. 

Sepsin. — The  best  known  poison  which  has  been  isolated  in  an  ap- 
proximately pure  state  from  decomposing  nitrogenous  material  is  sepsin. 
Much  work  has  been  done  upon  this  substance  by  Schmiedeberg  and 
recently  by  Faust,  who  obtained  sepsin  in  a  purified  state  in  sufficient 
quantities  carefully  to  study  its  action  and  composition.  Faust  obtained 
the  crystals  from  putrefied  yeast  and  blood;  25  milligrams  of  the  sul- 
phate introduced  intravenously  will  kill  a  large  dog  in  two  hours. 

Sepsin  has  the  following  chemical  structure : 

NH^  OH     OH     NH2 

I  III 

CH2-CH2— CH  —  CH  —  CH2 

Di-hydroxy-penta-methylene-diamin. 

Sepsin  is  very  unstable.  It  is  rendered  inactive  at  60°  C.  for  a 
short  time,  and  is  readily  converted  into  cadaverin  or  pentamethylene- 
diamin.     The  chemical  structure  of  cadaverin  is: 

NH,  NH2 

CH2— CH2-CH2-CH,— CH2 

Penta-methylene-diamin. 

Cadaverin  is  one  of  the  best  known  of  the  ptomain  group.  Its 
presence  indicates  that  the  putrefactive  process  at  one  time  contained 
sepsin  which,  by  reduction,  has  been  changed  into  cadaverin. 

Putrescin  is  another  diamin,  which  almost  invariably  occurs  together 


734  GENERAL  CONSIDERATIONS 

with  cadaverin,  to  which  it  is  closely  related.  It  was  first  described 
by  Brieger  in  1885,  and  has  been  obtained  from  putrefying  internal 
human  organs,  herring,  mussels,  etc.  '  It  is  recognizable  on  the  fourth 
day  of  putrefaction,  and  appreciable  quantities  appear  by  the  eleventh 
day.  It  is  still  present  after  two  or  three  weeks.  Baummann  in  1888 
showed  the  rational  formula  to  be: 

NH2  NH2 

I  I 

CH2-CH2-CH2-CH2 

Tetramethylenediamin. 

Putrescin  is- a  homolog  of  cadaverin  and  appears  in  putrefaction 
before  that  substance. 

Van  Slyke  and  Hart  (1903)  found  a  little  putrescin  in  ordinary 
Cheddar  cheese.  Once  formed  putrescin  and  cadaverin  appear  to  be 
very  resistant  to  bacterial  action. 

Putrescin  and  cadaverin  are  of  interest  because  they  have  been  found 
in  the  intestine,  derived  from  the  putrefactive  decomposition  of  pro- 
teins, and  sometimes  in  the  urine  in  cystinuria.  They  are  said  to  have 
some  physiological  properties,  setting  up,  according  to  Behring,  pois- 
onous symptoms  in  mice,  rabbits  and  guinea-pigs.  Udranszky  and  Beau- 
man,  however,  failed  to  obtain  any  evidence  of  intestinal  irritation  when 
dogs  were  fed  with  enormous  doses  of  cadaverin. 

The  cholin  group  of  ptomains  includes  cholin,  neurin,  muscarin  and 
betain  and  is  of  more  interest. 

Cholin  is  a  normal  constituent  of  every  cell,  forming  the  nitro- 
genous portion  of  the  lecithin  molecule.  It  is  only  very  moderately 
toxic,  but  the  closely  related  neurin  into  which  it  may  be  transformed 
is  highly  poisonous.  It  has  been  suggested  that  one  form  of  food  in- 
toxication is  due  to  the  cholin,  obtained  from  the  lecithin  in  the  food, 
being  converted  in  the  gastro-intestinal  tract  into  neurin.  While 
cholin  in  itself  is  not  very  toxic,  Hunt  has  shown  that  acetylcholin 
is  one  hundred  thousand  times  more  poisonous.  Cholin  is  a  base  widely 
distributed  in  nature;  it  is  found  in  the  yolk  of  eggs,  in  bile,  brain 
substance,  fat,  seeds,  and  other  substances.  It  can  also  be  prepared  from 
pure  lecithin,  which  is  a  fatty  body  normally  present  in  brain  substance, 
yolk  of  eggs,  and  perhaps  all  cells.  The  lecithin  may  be  readily  decom- 
posed by  bacterial  action  perhaps  to  cholin  and  cholin  salts.  While 
acetylcholin  has  never  been  demonstrated  in  food,  it  is  possible  that 
this  or  similar  poisons  may  be  produced  in  decomposing  foodstuffs. 

Brieger  obtained  neurin  in  the  putrefaction  products  of  horse,  beef 
and  human  blood  after  five  to  six  days'  action  in  summer. 

Muscarin  was  obtained,  accompanied  by  cholin,  by  Schmiedeberg  and 
Koppe  from  poisonous  mushrooms. 


ADULTERATION  OF  FOOD  725 

Both  neurin  and  uiuscarin  are  extremely  poisonous  and  very  similar 
in  their  action.  Subcutaneous  injection  of  but  1  to  3  mg.  of  muscarin 
in  man  produces  salivation,  rapid  pulse,  reddening  of  the  face,  weak- 
ness, depression,  profuse  sweating,  vomiting  and  diarrhea.  Neurin  acts 
very  similarly.  "The  toxicity  of  these  substances  is  so  great  that  not  a 
large  amount  would  need  to  be  formed  by  oxidation  of  cholin  to  pro- 
duce severe  symptoms,  although  it  is  not  known  that  this  occurs  actu- 
ally in  the  body.  When  introduced  by  the  mouth,  the  lethal  dose  of 
neurin  is  ten  times  as  great  as  when  injected  subcutaneouslj^,  indicating 
that  chemical  changes  in  the  gastro-intestinal  tract  offer  some  protec- 
tion against  intoxication  by  these  substances  when  taken  in  tainted  food. 
Cholin,  although  by  no  means  so  poisonous  as  neurin,  has  a  similar 
action  when  administered  in  sufficiently  large  doses.  According  to 
Brieger  it  is  about  one-tenth  to  one-twentieth  as  toxic  as  neurin" 
(Wells,  Chemical  Pathology). 

2[ytiloiorin  is  chiefly  of  interest  in  that  it  is  said  to  be  the  specific 
poison  in  connection  with  mussel  poisoning  and  was  obtained  by  Brieger 
in  1885  from  toxic  mussels.  He  was,  however,  unable  to  obtain  it  from 
ordinary  mussels  which  were  allowed  to  putrefy  for  sixteen  days.  Ac- 
cording to  Brieger  it  produces  all  the  characteristic  effects  seen  in  mus- 
sel poisoning.  Its  connection  with  mussel  poisoning  is  considered  on 
page  844. 

The  more  the  question  of  ptomains  is  studied  the  less  do  they  ap- 
pear concerned  in  cases  of  food  poisons.  It  is  now  clear  that  most,  if 
not  all,  cases  of  so-called  ptomain  poisoning  are  nothing  more  nor  less 
than  acute  infections  with  B.  enieritidis,  B.  cholerae  suiSj  and  other 
microorganisms  belonging  to  this  group. 


ADULTERATION  OF  FOOD 

Adulteration  of  food  consists  of  a  large  number  of  practices,  some 
of  which  are  fraudulent,  others  technical  in  nature.  Some  forms  of 
adulteration  are  injurious  to  health,  but  for  the  most  part  they  have 
an  economic  rather  than  a  sanitary  significance.  Foods  may  be  adul- 
terated in  a  variety  of  ways :  by  the  removal  of  nutritive  substances ; 
by  the  addition  of  injurious  substances;  by  the  fraudulent  substitution 
of  cheaper  articles;  by  misbranding;  or  by  the  sale  of  food  that  is  filthy, 
decomposed  or  putrid. 

Prior  to  the  passage  of  the  Pure  Food  and  Drugs  Act  in  1906  a  very 
large  percentage  of  the  food  sold  in  the  United  States  was  found  to 
be  "adulterated"  in  one  way  or  another.  Thus,  at  the  Agricultural  Ex- 
periment Station  in  Kentucky  40  per  cent,  of  727  samples  were  adul- 
terated; at  the  Connecticut  Agricultural  Experiment  Station  41.5  per 


726  GENERAL  CONSIDEEATIOXS 

cent,  of  574  samples  of  spices  were  found  adulterated,  and  oA'er  25  per 
cent,  of  coffee  samples  were  adulterated  (1899).^^ 

Among  the  common  adulterations  may  be  mentioned  the  following: 
cotton-seed  oil  is  sold  as  olive  oil;  honey  may  contain  glucose;  cocoa 
and  chocolate  are  frequently  mixed  with  both  starch  and  sugar;  coffee 
is  extensively  adulterated  with  caramel,  pea-meal,  chickory,  and  sac- 
charose extracts;  lard  is  mixed  with  cheaper  fats  or  cotton-seed  oil; 
saccharin  is  substituted  for  cane  sugar:  cereals  give  bulk  and  weight  to 
sausages;  gypsum  or  bran  is  added  to  flour;  barium  sulphate  to  powdered 
sugar,  flour  or  turmeric  or  corn  meal  to  mustard.  Oleomargarin  is  sold 
as  butter;  distilled  and  colored  vinegar  is  sold  as  cider  vinegar;  ground 
spices  are  adulterated  with  coconut  shells,  rice,  flour,  and  ashes;  water, 
sugar,  and  tartaric  is  sold  as  lemonade;  wines  and  liquors  are  some- 
times adulterated  with  alum,  baryta,  caustic  lime,  salicylic  acid,  wood 
alcohol,  and  hematoxylin.  Terra  alba,  kaolin,  and  various  pigments  are 
sometimes  added  to  candies ;  gum  drops  are  largely  made  with  petroleum 
parafBn  products ;  much  of  the  maple  sugar  formerly  sold  was  made  from 
glucose  and  coloring  matters. 

Definitions. — A  food  is  considered  adulterated  in  accordance  with 
the  Food  and  Drugs  Act  of  June  30.  1906:  (1)  "If  any  substance  has 
been  mixed  and  packed  with  it  so  as  to  reduce  or  lower  or  injuri- 
ously affect  its  quality  or  strength."  This  is  the  simplest  form  of  adul- 
teration, and  a  good  example  is  the  addition  of  water  to  milk.  Cocoa 
shells  are  sometimes  mixed  with  cocoa  or  chocolate.  Glucose  and  cara- 
mel are  added  to  maple  sugar;  talc  to  flour. 

(2)  "If  any  substance  has  been  substituted  wholly  or  in  part  for  the 
article."  As  illustrations  we  have  the  substitution  of  cotton-seed  oil 
or  corn  oil  for  olive  oil;  glucose  or  saccharin  for  sugar;  cereals,  which 
cost  much  less  than  meat,  in  sausage.  Apple  cores  and  parings  are  fre- 
quently used  as  a  substitute  for  currants  and  other  fruits  in  jellies. 

/  CO 

Saccharin     or     ortho-benzo-sulphaniid,     CgH^  \  NH,  is  made 

^SO/ 
from  toluene.    It  is  several  hundred  times  sweeter  than  sugar  and  com- 
paratively cheap.    It  has,  therefore,  been  used  as  a  substitute  for  sugar 
as  a  sweetening  agent  in  the  inferior  qualities  of  ginger  ale,  and  to  some 

'"  In  Massachusetts  the  State  Board  of  Health  began  to  examine  foods  for 
adulteration  in  1883.  It  was  then  found  that  between  60  and  70  per  cent,  of  aU 
foods  examined  were  adulterated.  As  a  result  of  official  surveillance  the  per- 
centages fell  in  a  few  years  to,  approximately,  15  per  cent,  and  have  remained 
between  10  and  20  per  cent,  since.  This  does  not  mean  that  from  10  to  20  per 
cent,  of  all  foods  found  on  the  market  are  adulterated,  for,  to  a  great  extent, 
samples  are  collected  from  suspicious  sources,  so  that  the  ratio  of  adulteration 
of  food  analyzed  in  the  laboratory  is  higher  than  that  of  the  same  foods  sold 
on  the  market. 


ADULTERATION  OF  FOOD  727 

extent  in  canned  corn,  peas,  etc.,  as  well  as  in  candies  and  other  articles. 
Saccharin  is  a  chemical  obtained  from  coal  tar  and  is  without  food 
value;  it  is  not  entirely  harmless.  The  Referee  Board  reports  that 
"the  continued  use  of  saccharin  for  a  long  time  in  quantities  over  0,3 
of  a  gram  per  day  is  liable  to  impair  digestion;  and  the  addition  of 
saccltarin  as  a  substitute  for  cane  sugar  reduces  the  food  value  of  the 
sweetened  product  and  hence  lowers  its  quality."  Saccharin-containing 
foods  are  therefore  regarded  as  adulterated  within  the  meaning  of  the 
Food  and  Drugs  Act. 

(3)  "If  any  valuable  constituent  of  the  article  has  been  wholly  or 
in  part  abstracted."  Skimming  milk  is  a  good  illustration  of  this  part 
of  the  law,  or  the  abstraction  of  cocoa  butter  from  chocolate.  There  is, 
however,  no  objection  to  abstracting  valuable  or  nutritive  substances 
provided  the  label  properly  announces  the  facts;  thus,  skimmed  milk 
or  cocoa  are  legitimate  foods.  So  also  the  caffein  may  be  taken  out  of 
coifee  and  sold  as  caffein-free  coffee.  The  essential  oils  are  sometimes 
extracted  from  cloves  or  other  spices,  which  are  subsequently  ground  and 
used  as  an  adulterant  with  unextracted  spice. 

(4)  "If  it  is  mixed,  colored,  powdered,  coated,  or  st-ained  in  any 
manner  whereby  damage  or  inferiority  is  concealed."  This  is  a  very 
frequent  form  of  adulteration,  and,  as  a  rule,  is  undesirable  and  some- 
times injurious.  Substances  used  to  color  foods  are  usually  considered 
in  three  classes:  (1)  mineral  dyes,  (2)  vegetable  dyes,  (3)  anilin  or 
coal-tar  dyes.  The  principal  mineral  dyes  are:  copper  sulphate,  oxid  of 
iron,  and  potassium  nitrate.  '  Copper  sulphate  is  used  to  give  a  green 
color  to  peas,  pickles,  and  similar  foods.  The  copper  probably  unites 
with  the  albuminous  matter  to  form  new  compounds  which  have  a  bright 
green  sickly  color.  The  oxid  of  iron  and  also  sulphites  are  used  upon 
meat  to  give  it  a  red  color;  potassium  nitrate  will  also  give  a  bright 
red  color  to  meat.  Many  vegetable  dyes  are  used,  such  as  annatto  (the 
juice  of  the  Bira  oreUana,  a  South  American  tree),  which  is  used  to  color 
butter.  Carrot  juice  is  also  used ;  turmeric  in  mustard ;  and  logwood  in 
wines.  The  coal-tar  dyes  have  largely  replaced  the  vegetable  and  min- 
eral pigments  in  foods,  on  account  of  their  brilliant  color  and  cheap- 
ness. They  are  used  in  sausages,  confectionery,  jellies  and  jams,  meats, 
flavoring  extracts,  etc. 

The  artificial  coloring  of  food  is  a  false  standard  and  serves  no 
useful  purpose.  When  the  coloring  matter  is  used  to  conceal  damage 
or  inferiority  the  practice  is  indefensible,  as  when  spoiled  meats  are 
made  to  look  bright  red  and  fresh,  or  when  oleomargarin  is  colored  in 
order  to  imitate  butter  and  sold  as  such.  Flour  may  be  bleached  with 
nitrogen  peroxid,  thus  giving  an  inferior  grade  the  appearance  of  first 
quality  flour.  The  XO,  is  produced  by  electric  action  and  nitrites  in 
appreciable  quantities  remain  in  the  flour.     Fruits  are  bleached  by  ex- 


728  GENERAL  CONSIDERATIONS 

posure  to  sulphur  fumes,  which  leaves  objectionable  sulphur  compounds. 
Candies  and  chocolate  are  often  coated  with  gum  benzoin  or  shellac. 

(5)  "If  it  contains  any  poisonous  or  other  added  deleterious  in- 
gredient which  may  render  such  article  injurious  to  health."  This 
section  of  the  law  is  intended  to  include  adulterants,  such  as  formal- 
dehyd,  sulphites,  arsenic,  hydrofluoric  acid,  lead,  salicylic  acid,  borax 
and  boracic  acid,  as  well  as  any  other  injurious  substance.  Most  of  the 
storm  center  of  the  opposition  to  the  Pure  Food  Law  is  centered  around 
this  paragraph,  owing  to  the  difficulty  of  deciding  in  certain  instances 
whether  small  amounts  of  benzoic  acid  or  benzoates,  boric  acid  or 
borates,  are  injurious  to  health  or  not.  These  substances  are  discussed 
more  in  detail  under  chemical  preservatives. 

(6)  "If  it  consists  in  whole  or  in  part  of  a  filthy,  decomposed,  or_ 
putrid  animal  or  vegetable  substance  or  any  portion  of  gin  animal 
iinfit  for  food,  whether  manufactured  or  not,  or  if  it  is  the  product  of 
a  diseased  animal  or  one  that  has  died  otherwise  than  by  slaughter." 
Examples :  oysters  contaminated  with  sewage ;  eggs  known  as  "rots  and 
spots";  animals  which  have  died  otherwise  than  by  slaughter;  figs  con- 
taining an  excessive  quantity  of  worms  and  worm  excrement.  This 
paragraph  of  the  law  has  caused  much  discussion,  especially  the  mean- 
ing of  the  word  "decomposed."  '  This  question  is  considered  more  in 
detail  under  the  paragraph  Decomposed  Foods. 

Mishrandi?ig. — The  term  "misbranding"  is  specifically  defined  in 
the  Food  and  Drugs  Act  and  provides  for  all  possible  conditions  of 
fraud,  mislabeling,  imitation,  substitution,  and  other  forms  of  decep- 
tion. Misbranding  is  regarded  as  a  form  of  adulteration  under  the 
Food  and  Drugs  Act.  The  practices  of  misbranding  under  any  cir- 
cumstances are  so  evidently  fraudulent  or  dishonest  that  they  cannot 
be  justified  on  any  score  and  are  wholly  condemned.  It  is  true  that 
many  instances  of  misbranding  do  not  directly  affect  health,  except  in 
so  far  as  they  deceive  the  consumer;  that  is,  he  is  purchasing  at  a  high 
price  an  article  which  contains  less  nutritive  value  than  claimed  for  it. 
An  honest  label  which  correctly  states  the  character,  origin,  amount,  and 
the  constituent  parts  of  an  article  is  as  much  a  desideratum  in  food 
products  as  it  is  in  commercial  articles  of  all  kinds.  Honest  labeling  is 
the  heart  and  soul  of  the  pure  food  movement. 


PRESERVATION  OF  FOODS 

The  preservation  of  meat,  milk,  vegetables,  and  other  perishable 
foods  is  one  of  the  most  important  questions  we  have  to  deal  with  in 
the  whole  range  of  hygiene.  Fermented  and  decayed  foods  must  be 
looked   upon   with   suspicion.      The    proper    preservation    of   foodstuffs 


PRESERVATION  OF  FOODS  729 

involves  not  tuilv  the  art  of  kc'i'|)iii<r  tliciu  "i'resh"  and  wholesome,  but 
also  koci)in<;-  them  so  that  they  will  not  lose  their  nutritive  value.  Fi- 
nally, foodstutl's  must  he  preserved  so  that  they  will  iK^t  acquire  injurious 
properties.  Tlie  preservatives  ordinarily  in  use  are:  cold,  dryiii<r,  salt- 
in<X.  smoking,  canning,  preserving,  and  chen)ic.d  treatment.  The  best 
arc  hcaf,  cold  and  (Iri/ing. 

Practically  all  these  methods  have  long  l)een  in  use.  The  only 
modern  innoNation  in  the  preservation  of  foods  is  in  the  perfection  of 
the  old  processes,  based  upon  our  knowledge  of  antiseptics  and  germi- 
cides. Heat  and  cold  represent  old  family  methods  which  have  been 
extended  and  improved  in  the  modern  canning  and  cold  storage  indus- 
tries. The  drying  of  fruits,  fish,  and  meats  is  a  practice  of  very  ancient 
origin.  The  use  of  salt  doubtless  antedates  all  historical  records.  Sugar 
either  alone  or  with  acetic  acid  in  the  form  of  vinegar  and  with  vari- 
ous spices  is  an  old  contrivance  and  well  known  everywhere.  The  ap- 
plication of  creosote  obtained  crudely  from  the  smoke  of  incompletely 
burned  wood  is  the  ancient  forerunner  of  some  of  the  modern  packing 
processes. 

Concerning  the  value  and  legitimacy  of  these  old  family  methods 
there  is  comparatively  little  difference  of  opinion;  salt  meat  is  not  as 
good  as  the  fresh  article ;  dry  apples  do  not  make  the  best  apple  pie ; 
chipped  beef  is  not  an  adequate  substitute  for  a  fresh  steak.  However, 
it  is  absolutely  necessary  to  preserve  food  in  some  way  in  order  to 
tide  over  the  winter  or  the  dry  seasons,  to  furnish  food  to  people  living 
and  working  in  desert  and  arid  regions,  and  to  feed  the  hordes  of  peo- 
ple massed  together  in  great  cities.  It  would  be  impossible  to  main- 
tain the  large  population  of  a  modern  metropolis  if  it  were  dependent 
upon  a  daily  supply  of  fresh  food  materials. 

The  art  of  preserving  foods  depends  upon  the  science  of  bacteriol- 
ogy. A  more  complete  knowledge  of  the  causes  of  decomposition  and 
methods  by  which  they  may  be  prevented  has  enabled  us  to  perfect 
the  crude  and  primitive  methods  that  have  been  in  use  from  time  im- 
memorial, so  that  it  is  now  possible  to  preserve  certain  foods  practi- 
cally indefinitely  without  in  any  way  injuring  their  nutritive  value  or 
seriously  interfering  with  their  appearance  and  taste. 

The  chief  harm  has  come  from  the  blind  use  of  chemical  germi- 
cides, without  regard  for  their  harmful  properties.  The  simplest  and 
cheapest  way  to  preserve  food  is  by  adding  one  of  these  chemicals,  and 
the  method  was,  therefore,  seized  upon  by  alert  men  whose  chief  in- 
terest was  of  the  pecuniary  kind.  The  question  was  to  find  the  small- 
est percentage  of  a  chemical  which  would  prevent  the  decay  of  some 
particular  food  product,  trusting  to  luck  that  the  preservative  used 
might  prove  harmless  to  the  consumer.  Often  these  chemicals  were 
added  with  a  liberal  hand;  further,  it 'was  soon  found  that  chemical 


730  GENERAL  CONSIDERATIONS 

preservatives  could  be  used  to  preserve  food  products  for  the  market 
from  materials  already  so  decayed  as  to  be  unsalable  in  their  original 
condition. 

The  National  Pure  Food  and  Drugs  Act  of  1906  was  passed  largely 
to  meet  this  situation.  This  law  considers  any  food  which  contains 
some  "added  poisons  or  other  deleterious  ingredient  which  may  render 
such  article  injurious  to  health"  as  adulterated.  To  Harvey  W.  Wiley 
belongs  the  credit  of  inducing  Congress  to  pass  this  legislation  against 
opposition  and  for  an  aggressive  administration  that  proved  useful  in 
bringing  the  whole  question  prominently  before  the  public. 

Cold. — Cold  must  be  regarded  by  the  sanitarian  as  an  antiseptic 
rather  than  a  germicide.  Low  temperatures  kill  few  bacteria,  but  pre- 
vent the  growth  and  multiplication  of  most  of  them.  Even  the  anti- 
septic properties  of  cold  are  not  as  marked  as  they  were  once  believed 
to  have  been.    Many  plants  and  even  frogs  may  survive  freezing. 

Some  bacteria  grow  and  multiply  at  low  temperatures,  even  at  0°  C. 
In  1871  Burdon-Sanderson  was  the  first  to  show  that  freezing  does  not 
kill  bacteria.  Yon  Frisch  demonstrated  that  subjecting  a  putrefying 
solution  to  a  temperature  of  —87°  C.  for  some  hours  did  not  afEect 
sterilization.  Leidy  in  1848  showed  that  water  derived  from  melted 
ice  contained  not  only  living  infusoria,  but  also  rotifers  and  worms. 
Pictet  and  Young  found  that  anthrax  and  symptomatic  anthrax  cul- 
tures were  not  killed  after  an  exposure  of  108  hours  to  —70°  C.  Later 
Macfadyen  proved  that  the  temperature  of  liquid  air  does  not  kill  bac- 
teria; he  subjected  cultures  to  temperatures  of  — 315°  F.  Ehrlich  has 
shown  that  cancer  cells  kept  cold  will  live  and  remain  virulent  for  at 
least  two  years. 

While  no  microorganism  pathogenic  for  man  will  grow  and  multiply 
at  the  low  temperatures  of  the  refrigerator,  there  are  a  number  of 
saprophytic  bacteria  and  molds  that  develop  abundantly  at  tempera- 
tures as  low  as  0°  C.  Milk,  meat,  eggs,  and  other  products  kept  in 
cold  storage  at  or  near  the  freezing  point  may  show  a  notable  increase 
in  the  number  of  bacteria.  A  number  of  tests  made  in  my  laboratory 
showed  that  in  the  case  of  milk  these  low-temperature  microorganisms 
belong  mainly  to  the  putrefying  and  proteolytic  group.  They  produce 
an  alkaline  reaction  in  the  milk  and  a  bitter  taste.  Whether  they  are 
capable  of  forming  poisonous  products  at  these  low  temperatures  is 
doubtful. 

For  the  most  part  pathogenic  bacteria  withstand  freezing  tempera- 
tures. They,  however,  suffer  a  quantitative  reduction  when  frozen  (see 
Ice  and  the  effects  of  freezing  upon  bacteria,  page  1185).  Most  animal 
parasites  die  in  cold  storage;  a  few,  however,  survive.  The  length  of 
time  the  material  has  been  refrigerated  is  an  important  factor.  Just  as 
infected  water  becomes  safer  by  storing  it,  so  with  foods.    Cold  storage 


PRESERVATION  OK  FOODS  ;;U 

renders  foods  safer,  Iml  caniKit  lie  cnliri'ly  i-clicil  upon  for  all  infections. 
Time  is  the  important  factor,  hut  tlie  dei^ree  of  refrisferation  also  in- 
fluences the  length  of  time  a  parasite  will  remain  alive.  Thus,  Trichinae 
die  at  or  below  5°  C.  in  twenty  days.  If  the  temperature  is  maintained 
at  15°  F.  or  below,  the  larvae  of  T.  saginaia  (the  beef  tapeworm)  are 
killed  within  6  days,  and  there  "are  indications  that  the  larvae  of  T. 
solium  (the  pork  tapeworm)  would  be  killed  in  a  similar  length  of  time 
at  the  same  temperature. 

Fortunately,  cold  causes  a  quantitative  reduction  in  the  number  of 
harmful  bacteria,  even  though  it  does  not  produce  complete  steriliza- 
tion. The  element  of  time  here  plays  an  important  role,  as  most  of 
the  surviving  pathogenic  microorganisms  soon  die.  From  a  sanitary 
standpoint  tiie  protection  afforded  by  refrigeration  is  reassuring,  although 
not  perfect.    Cold  acts  as  a  preservative  for  some  viruses. 

The  best  temperature  at  which  foodstuffs  may  be  kept  must  be  de- 
termined for  each  case.  Some  substances,  such  as  meat  and  poultry, 
are  better  preserved  when  actually  frozen  ;  others,  such  as  shell-eggs  or 
milk,  are  materially  injured  by  freezing.  Fish  are  usually  frozen.  They 
are  then  dipped  in  water  and  refrozen  in  order  that  they  may  be  .com- 
pletely encased  in  ice.  They  are  then  stored  at  a  temperature  of  — 16°  C. 
The  coating  of  ice,  which  is  renewed  as  occasion  requires,  prevents  loss 
of  water  due  to  surface  evaporation.  Under  these  circumstances  there  is 
no  evidence  whatever  of  any  depreciation  in  the  nutritive  value  or  any 
change  in  the  sanitary  character  of  the  fish  at  any  time  rluring  two  years 
of  cold  storage.^* 

In  any  event,  the  temperature  of  the  icebox  should  not  rise  above  7° 
C.  At  this  temperature  bacterial  gro^vth  does  not  entirely  cease,  although 
very  markedly  hindered.  Few  household  refrigerators  reach  this  tem- 
perature or  maintain  it  for  any  length  of  time — either  through  faulty 
construction  or  on  account  of  insuflBcient  ice.  Often  the  icebox  is  placed 
in  a  sunny  corner,  or,  for  convenience,  near  the  kitchen  stove.  The  doors 
of  the  ice  chest  frequently  do  not  fit  well,  which  results  in  needless  waste 
and  imperfect  refrigeration.  A  study  of  household  refrigerators  dis- 
closes the  fact  that  the  temperature  is  often  15°  C.  and  higher.  Such 
conditions  make  good  incubators,  favoring  bacterial  growth.  B.  en- 
teritidis  will  grow  at  10°  C.  The  necessity  for  scrupulous  cleanliness, 
aeration,  and  dryness  in  all  refrigerating  devices  needs  only  be  men- 
tioned. 

In  ordinary  refrigerating  plants  moisture  condenses  on  the  surface 
of  the  objects  exposed.  In  the  case  of  meat  this  moisture  dissolves 
some  of  the  proteins,  extractives,  and  salts,  and  makes  a  perfect  cul- 
ture medium  for  bacteria  and  molds.  In  the  case  of  meats  it  is,  there- 
fore, better  to  hang  them  in  a  current  of  dry,  clean  air,  in  order  to 
«  Smith,  C.  S.:     Biochem.  Bull.,  1913,  III,  54. 


733  GENERAL  CONSIDERATIONS 

desiccate  the  surface,  before  they  are  placed  in  the  refrigerator.  The 
dried  surface  delays  the  inward  growth  of  the  inevitable  bacterial  con- 
tamination upon  the  surface. 

Articles  of  food  may  be  kept  in  a  satisfactory  condition  in  cold 
storage  for  a  very  long  time.  The  time  varies  with  the  article  and 
its  condition  when  placed  in  storage,  also  with  the  temperature  and 
other  factors.  A  striking  illustration  of  the  great  preserving  power 
of  low  temperatures  occurred  several  years  ago  in  Northern  Siberia. 
In  consequence  of  a  great  landslide  on  the  banks  of  the  Kolyma,  the 
head  of  a  mammoth  became  exposed  and  was  so  well  preserved  that 
even  the  fleshy  trunk  remained.  It  is  said  that  famished  wolves  and 
half-starved  natives  began  to  eat  of  the  flesh.  Th€  Russian  government 
sent  Dr.  Hertz  to  rescue  what  remained.  The  mammoth  had  re- 
mained in  cold  storage  perhaps  thousands  of  years.  Some  of  the  soft 
parts  are  now  preserved  in  the  Museum  at  Petrograd.  This  must  not 
be  taken  as  justification  of  prolonged  storage  or  the  "cornering^'  of 
foods  for  economic  gain  in  mammoth  cold  storage  warehouses.  While 
meat,  poultry,  eggs,  and  vegetables  may  be  kept  in  a  satisfactory 
condition  for  months  and  transported  over  seas,  cold  storage  need  not 
be  unduly  prolonged.  In  any  case,  the  consumer  is  entitled  to  know 
whether  the  article  is  fresh  or  stored,  and  the  time  it  has  been  in  cold 
storage.    These  facts  should  be  stated  upon  the  label  or  stamp. 

The  question  of  cold  storage  poultry  was  investigated  by  the  Massa- 
chusetts State  Board  of  Health,  and  the  conclusion  was  reached  that 
it  made  practically  no  difference  whether  the  fowl  were  drawn  or  not, 
but  that  they  must  be  perfectly  fresh  when  placed  in  cold  storage. 
Poultry  is  kept  below  0°  C,  at  which  temperature  no  noticeable  change 
occurs.  It  was  found  that  cold  storage  fowl  are  even  less  contaminated 
with  bacteria  than  freshly  killed  birds  that  have  hung  for  a  few  days. 
However,  the  cold  storage  animals,  when  removed  from  the  refrigera- 
tor, decompose  more  quickly  than  the  fresh. 

Contrary  to  what  might  be  expected,  drawn  poultry  decomposes 
more  rapidly  after  removal  from  cold  storage  than  undrawn.  This  is 
because  in  the  process  of  drawing  the  intestines  are  broken  below  the 
gizzard  and  the  carcass  becomes  badly  contaminated  with  intestinal 
bacteria.  If  the  entire  alimentary  canal,  esophagus,  crop,  gizzard,  and 
intestines  are  removed  intact,  and  with  bacteriologic  care  to  prevent 
contamination,  the  bird  is  practically  safe  from  putrefaction. 

From  a  sanitary  standpoint,  then,  refrigeration  is  one  of  the  best 
methods  of  preserving  foodstuffs.  The  advantages  of  cold  as  a  preserva- 
tive are  that  it  neither  adds  any  constituent  to  the  food  nor  takes  away 
any  constituent  from  the  food.  Cold  imparts  no  new  taste,  nor  does  it 
seriously  alter  the  natural  flavor.  It  does  not  diminish  its  digestibility 
nor  cause  a  loss  of  nutritive  value.     The  material  is  left  in  approxi- 


PRESERVATION  OF  FOODS  733 

mately  its  original  condition.  Cold  may,  therefore,  be  regarded  as 
one  of  the  simplest  and  best  antiseptics  we  have  for  the  preservation 
of  foods.  It  is  now  almost  universally  applied  to  prevent  decomposition 
and  decay.  Tlic  housewife  uses  it  to  keep  food  in  cold  cellars,  deep 
wells,  and  the  like.  l)urin;j^  the  last  fifty  years  the  use  of  ice  for  the 
jiurpose  of  refrigeration  has  become  commonplace.  Fresh  and  whole- 
some food  may  now  be  transported  to  the  tropics,  and  the  sustenance 
of  large  communities  in  insular  and  arid  regions  is  made  possible  and 
pleasurable  through  the  preserving  use  of  cold. 

Drying. — Drying,  desiccation,  or  evaporation  is  a  favorite  and  primi- 
tive method  of  preserving  meats,  fruits,  vegetables,  and  various  food 
materials.  Dryness  furnishes  ideal  antiseptic  conditions.  j\Iicroorgan- 
isms  must  have  moisture  to  grow  and  multiply.  Most  pathogenic  micro- 
organisms soon  die  when  dried,  hence  the  process  has  a  decided  sani- 
tary advantage.  Further,  dried  fruits,  vegetables  or  meats  are  rarely 
eaten  raw,  and  the  cooking  is  a  further  sanitary  safeguard. 

Drying  has  two  principal  advantages:  (1)  it  reduces  the  weight 
and  thereby  simplifies  the  problem  of  handling  and  distribution;  (2) 
it  improves  the  keeping  qualities  of  the  food. 

The  effectiveness  of  drying  as  a  food  preservative  depends  upon 
the  thoroughness  with  which  the  process  is  carried  out.  It  is  not  so 
well  adapted  to  meats  as  to  vegetables  and  fruits.  Dried  meats  lose 
their  natural  flavor,  which  may  be  replaced  with  others  less  real.  All 
sorts  of  organic  foodstuffs,  even  the  most  decomposable,  such  as  milk, 
eggs,  fruit,  or  meat,  may  be  dried  and,  if  kept  dry,  will  keep  in  a  satis- 
factory state  almost  without  limit  of  time.  Drying  has  little  or  no 
influence  upon  the  vitamin  content  of  foods.  It  certainly  does  not 
diminish  the  activity  of  "water-soluble  B"  which  protects  against  beri- 
beri. Dried  leaves,  such  as  celery  tops  and  alfalfa  are  still  good  sources 
of  "fat-soluble  A,"  even  when  dried  in  the  sun,  or  by  artificial  heat 
in  a  current  of  air  after  preliminary  treatment  with  steam.  Dried 
milk  is  also  an  efficient  source  of  "fat-soluble  A."  On  the  other  hand, 
dr^'ing  may  diminish  the  antiscorbutic  value  of  food.  Thus,  dried 
milk  loses  about  half  its  antiscorbutic  properties. 

Theoretically,  dryness  is  not  a  complete  safeguard,  for  the  reason 
that  a  few  microorganisms  survive,  particularly  bacterial  spores.  Despite 
this  slight  limitation,  it  is  more  than  reasonably  safe  and  an  entirely 
satisfactory  procedure.  Practically  the  only  change  in  dried  foods 
is  the  loss  of  moisture,  which  may  readily  again  be  supplied.  Dryness 
has  the  great  advantage  in  that  no  added  chemical  or  added  preserva- 
tive process  is  necessary;  further,  dried  foods  are  quite  as  nutritious 
and  usually  quite  as  digestible  as  the  fresh  articles,  although  not  quite 
as  savory. 


734  GENERAL  CONSIDERATIONS 

Dried  Meat. — In  the  dry  climates  of  South  America  and  on  our 
western  plains  meat  is  cut  into  thin  strips,  suspended  in  the  air, 
and  exposed  to  direct  sunlight.  In  a  short  time  the  moisture  disap- 
pears and  the  hard,  dry  pieces  keep  indefinitely,  or  as  long  as  they  are 
kept  dry.  The  meat  retains  a  fair  degree  of  palatability  and  practi- 
cally all  of  its  nutrient  properties.    This  is  known  as  jerked  beef. 

Dried  beef  is  also  prepared  by  first  treating  the  meat  with  condi- 
ments and  then  drying  it  artificially.  Chipped  beef  or  dried  beef  is 
prepared  in  this  manner,  except  that  the  meats  are  often  smoked  as  well 
as  salted  and  desiccated,  so  that  in  their  method  of  preparation  more 
than  one  method  of  preservation  is  employed. 

Powdered  meats  are  prepared  by  complete  desiccation,  and  such 
products  are  found  upon  the  market  as  a  finely  ground  powder.  Meat 
powders  are  made  not  alone  from  fresh  meats  in  their  natural  state, 
but  are  also  prepared  after  more  or  less  artificial  digestion. 

Dried  Fruits. — Dried  apples  -are  taken  as  a  type  of  dried  fruits 
and  vegetables.  The  apples  may  be  dried  naturally  by  cutting  them 
into  convenient  sizes  and  exposing  them  to  the  action  of  the  sun.  This 
is  more  a  domestic  than  a  commercial  industry.  When  apples  are 
dried  by  this  simple  process  they  darken  and  become  unattractive  in 
appearance.  This  is  due  to  the  oxidizing  action  of  the  enzymes  when 
exposed  to  the  air.  When  properly  prepared  the  dried  apple  has  its 
moisture  content  reduced  to  apj)roximately  30  per  cent,  or  less. 

In  order  to  prevent  the  darkening  of  the  surface  during  the  long 
exposure  necessary  to  secure  the  proper  degree  of  evaporation,  apples 
are  usually  subjected  to  the  fumes  of  burning  sulphur.  The  sulphur 
dioxid  acts  as  a  bleaching  agent  and  the  sulphurous  and  sulphuric 
acids  retained  in  the  apple  act  as  preservatives.  Apples  treated  with 
sulphur  fumes  are  less  likely  to  decay  or  become  infected  with  molds 
than  a  similar  product  not  exposed  to  sulphur  fumes.  The  process 
is  objected  to  from  the  standpoint  of  health,  for  the  reason  that  the 
sulphurous  acids  and  sulphites  are  admittedly  injurious  to  health.  The 
Department  of  Agriculture  found  that  approximately  half  of  the  evapo- 
rated fruits  purchased  on  the  open  market  had  been  treated  with  sul- 
phur fumes.  In  order  to  obtain  a  satisfactory  dried  product  it  is  of 
some  importance  that  the  fruits  be  selected,  so  as  to  reject  all  imper- 
fect, rotten,  or  infected  specimens. 

Evaporated  apples  is  a  term  applied  to  apples  dried  artificially  in- 
stead of  being  exposed  to  the  sun's  heat.  The  process  is  rapid  and 
satisfactory,  and  has  no  sanitary  objections. 

Dried  Eggs. — Eggs  are  broken  out,  mixed  and  dried  by  spreading 
the  mass  in  a  thin  film  in  shallow  pans  or  upon  a  broad  revolving  belt ; 
the  water  is  abstracted  by  exposure  to  a  current  of  warm,  dry  air.  The 
egg  substance  may  also  be  dried  by  forcing  it  through  small  orifices 


PRESERVATION  OF  FOODS  735 

under  a  high  pressure  into  a  ilrviiig  cliaiulter  so  adjusted  as  to  tempera- 
ture and  size  as  to  secure  the  ilesieeation  oi'  the  minute  jiarticles  of  egg 
spray  hefore  they  fall  to  the  hottom.  Egg  substance  thoroughly  dried 
keeps  satisfactorily  in  alnu)st  any  climate.  It  retains  all  the  nutritive 
value  in  the  original  cgfj;. 

Dried  Milh. — j\lilk  must  be  dried  quickly  in  order  that  it  will  not 
spoil  during  llic  process,  and  the  temperature  must  not  be  high  enough 
to  coagulate  the  lactalbumin,  otherwise  the  addition  of  water  would  not 
restore  the  milk  to  its  former  homogeneous  state.  IMilk  may  be  dried 
in  a  very  thin  film  on  heated  and  revolving  metal  drums  or  on  belts 
in  a  current  of  dry,  warm  air;  or  in  vacuo.  In  this  way  the  milk  can 
be  reduced  to  a  dry  state  in  a  very  short  time  and  without  reaching  a 
temperature  sufficiently  high  to  produce  physical  changes.  A  favorite 
method  of  drying  milk  consists  in  atomizing  it  under  pressure  and 
projecting  it  into  a  warm  chamber,  the  temperature  of  which  is  so 
regulated  that  the  fine  particles  are  completely  deprived  of  their  water 
before  they  reach  the  bottom  of  the  cabinet.  The  milk  is  thus  reduced 
almost  at  once  to  a  fine  powder.  Dried  milk  when  mixed  with  water  is 
practically  restored  to  its  original  condition.  Milk  powder  should  be 
either  kept  in  a  cool  place  or  sealed  in  air-tight  packages  in  order  to 
prevent  the  fat  becoming  rancid.  Dry,  powdered  milk  properly  cared 
for  will  keep  almost  indefinitely.  Since  practically  88  per  cent,  of 
milk  is  water,  there  is  a  decided  economic  gain,  so  far  as  the  handling 
and  transportation  are  concerned.  Powdered  milk  should,  of  course, 
be  made  from  milk  derived  from  healthy  cows  handled  under  sanitary 
conditions  and  free  from  infection.  The  milk  should  be  pasteurized 
before  it  is  reduced  to  a  powder.  Powdered  milk  is  finding  an  increas- 
ing and  legitimate  field  of  usefulness  for  cooking,  household  purposes, 
as  a  beverage  for  adults  and  even  for  infant  feeding.  It  should,  how- 
ever, not  be  depended  upon  for  infant  feeding.  Dried  milk  seems 
to  retain  all  the  qualities  of  the  liquid  product,  except  that  it  has  lost 
some  (about  one-half)  of  its  antiscorbutic  properties. 

Salting  and  Pickling-. — The  preservation  of  meat  with  brine  or  com- 
mon salt  is  one  of  the  oldest  processes  known.  The  brine  should  con- 
tain from  18  to  25  per  cent,  of  salt.  For  red  meats  a  little  potassium 
nitrate  is  often  added;  this  salt  has  slight  antiseptic  properties,  but 
brings  out  the  red  color.  Haldane  has  shown  that  nitrite  is  formed 
from  the  nitrate,  and  that  some  nitrous-oxidhemoglobin  is  formed, 
which  gives  a  bright  red  color  to  the  meat.  In  the  processes  of  salting 
some  of  the  meat  protein,  bases,  and  extractives  are  dissolved  out  and 
the  fibers  become  hardened;  the  nutritive  value  and  digestibility,  there- 
fore, are  somewhat  diminished.  The  hrine  should  never  be  less  than  6 
per  cent.,  for  B.  botulinus  will  not  grow  and  produce  its  toxin  in  this 
concentration. 


736  GENERAL  CONSIDERATIONS 

Pickling  includes  preservation  of  food  in  brine,  vinegar,  weak  acids, 
and  the  like.  These  substances  have  antiseptic  and  also  feeble  germi- 
cidal  properties,   depending  upon  their  concentration. 

Pickled  meats  are  prepared  by  soaking  meat,  especially  pork,  in  a 
brine  made  of  common  salt,  though  other  substances,  such  as  sugar, 
vinegar,  and  spices,  are  often  added.  Chemical  preservatives  are  some- 
times added  to  the  brine.  Those  most  frequently  used  are  sulphite  of 
soda  or  boric  acid.  With  proper  methods  these  added  chemical  anti- 
septics are  not  necessary.  The  vinegar  which  is  employed,  or  acetic 
acid,  may  be  injected  into  the  carcass  before  it  is  cut  up.  When  the 
arteries  are  filled  with  vinegar  in  this  way  it  rapidly  permeates  to  all 
parts  of  the  meat  and  acts  as  an  excellent  and  unobjectionable  preserva- 
tive in  cases  where  an  acid  taste  is  desired.  It  is  stated  that  carcasses 
which  have  been  injected  with  vinegar  are  easily  preserved  and  require 
far  less  salt  and  other  condimental  substances  than  when  not  so  treated. 
The  process  has  no  sanitary  obje.ctions. 

Trichina  die  after  a  prolonged  period  of  pickling,  Cysticerci  die  a 
natural  death  in  21  days  following  the  death  of  the  host.  They  are 
killed  very  promptly  if  placed  in  brine  under  conditions  which  will 
permit  the  rapid  penetration  of  salt,  but  in  practice,  owing  to  varia- 
tions in  the  rapidity  of  the  penetration  of  salt  into  meat,  this  is  not 
taken  into  consideration  and  pickled  beef  from  affected  cattle  is  con- 
sidered free  from  viable  cysticerci  only  after  the  expiration  of  three 
weeks  following  slaughter.  Many  pathogenic  bacteria  die  in  brine  of 
this  concentration,  but  the  salt  must  be  looked  upon  as  an  antiseptic 
rather  than  a  germicide;  that  is,  it  prevents  growth  rather  than  kills 
the  bacteria  that  are  present.  From  a  sanitary  standpoint  there  is 
some,  though  slight,  danger  of  conveying  infection  in  foods  that  have 
been  improperly  salted  or  pickled.  Attention  is  called  to  the  fact 
that  the  first  cases  of  botulism  studied  by  van  Ermengem  were  caused 
by  ham  kept  in  brine  under  conditions  favoring  anaerobic  growth. 

Decomposition  may  also  be  arrested  by  the  use  of  syrups,  which  have 
an  entirely  similar  action  to  that  of  salt,  vinegar,  or  weak  acids;  that 
is,  a  strong  solution  of  sugar  will  prevent  growth,  but  cannot  be  de- 
pended upon  to  kill  parasites.  However,  most  pathogens  die  under 
such  conditions  in  the  course  of  time.  As  most  preserved  foodstuffs 
are  cooked  before  eaten,  there  is  small  danger  in  articles  prepared  by 
these  processes.  ^ 

Jellies  and  Preserves. — By  preserving  is  commonly  understood  the 
addition  of  a  large  amount  of  sugar.  The  principal  preserves  are  jel- 
lies, marmalades,  jams,  and  fruit  butters.  These  substances  are  en- 
tirely free  from  the  danger  of  conveying  infection,  not  only  on  account 
of  the  antiseptic  action  of  the  sugar,  but  for  the  further  reason  that 
they  are  always  cooked  in  preparation.     Jellies  are  frequently  adulter- 


rrjESEin^ATiON  of  foods  737 

atod  I)y  t1u»  siihstitutioii  of  ;i|i|ilc  slock.  A])plos  contain  a  lar;,'c  niiin- 
luT  of  pcclasc  hodics  wliicli  faxor  jt'lliCical  ion.  I'cctase  bodies  arc  car- 
boliA-dratos  (^',jHi„0.-,)''  similar  in  constrnction  lo  collnlosc.  When 
pectasc  bodies  arc  boiled  wilb  an  acid,  ihey  are  hydrolyzed  to  pectin 
bodies  wbich  take  the  jell  foini  on  coolino;-.  Jf  boiled  too  long,  complete 
hydrolysis  takes  place  and  the  pectin  bodies  are  converted  into  glucose 
and  glycosuric  acid. 

A  common  method  of  manufacturing  jelly  for  the  trade  has  been 
to  use  a  stock  of  apple  juice  or  cider,  or  a  preparation  made  from  the 
cores,  skins,  and  rejected  portions  of  the  apple  at  evaporating  factories, 
or  from  whole  rejected  apples.  This  stock  is  used  as  a  common  base 
for  the  manufacture  of  jellies  of  different  kinds.  Apple  juice  used  as  a 
substitute  for  other  fruit  juices  in  the  making  of  preserves  is  a  common 
fraud  and  an  adulteration,  according  to  the  Food  and  Drugs  Act,  ucless 
plainly  stated  upon  the  label.  Phosphoric  acids  and  other  acids  are 
added  to  jellies  to  enable  jellification  to  take  place  with  the  use  of  less 
fruit  and  more  water.  Jellies  are  also  adulterated  with  artificial  color- 
ing matter,  particularly  the  coal-tar  dyes.  Artificial  flavors  which  closely 
resemble  the  particular  flavor  desired  are  sometimes  employed.  The 
chemical  preservatives  most  frequently  added  to  jellies  and  preserved 
fruits  are  salic3dic  acid,  benzoic  acid,  or  benzoate  of  soda. 

Smoking. — The  smoking  of  fish,  beef,  hams,  and  other  food  products 
consist  mainly  in  rapid  drying  plus  the  germicidal  action  of  certain 
substances  in  the  smoke. *^^  The  meat  or  fish  is  exposed  to  the  smoke 
of  a  smoldering  wood  fire  of  oak,  maple,  or  hickory,  usually  after  a 
preliminary  salting.  The  articles  so  exposed  become  dry  and  impreg- 
nated with  pyroligneous  products — -acetic  acid  and  creosote,  formalde- 
hyd,  and  other  germicidal  substances.  The  penetration  is  only  par- 
tial. 

An  artificial  or  quick  method  of  smoking  meat  is  to  brush  the  pieces 
or  dip  them  in  pyrolignic  acid  at  definite  intervals,  and  finally  dry  in 
the  air.  The  effects  of  the  smoking  do  not  penetrate  very  far ;  therefore, 
in  sausages  of  generous  diameter  putrefaction  often  occurs  in  the  in- 
terior. Smoked  sausage  may,  therefore,  be  dangerous,  as  far  as  various 
parasites  and  the  products  of  decomposition  are  concerned,  and  the 
same  is  true  of  smoked  ham  and  other  meats  exposed  in  large  pieces. 
As  smoked  meats  are  often  eaten  raw,  the  occasional  survival  of  para- 
sites in  such  products  has  some  sanitary  significance. 

Canning, — The  process  of  canning  is  practically  synonymous  with 
sterilization  and  is,  therefore,  one  of  the  best  sanitary  safeguards  we 
have  against  parasites  and  the  injurious  products  of  putrefaction  in 
foodstuffs.     The  process  of  canning  was  discovered  by  the  confectioner, 

*^The  process  was  probably  accidentally  discovered  in  connectioa  with  crude 
attempts  to  use  artificial  heat  for  drying  purposes. 


738  GFAH^^EAI.  COXSl DERATIONS 

M.  Api)ert.  of  Paris,  in  1804-1S09,  long  before  the  days  of  bacteriology.'^" 
Appert  found  that  meats  and  other  foods  in  sealed  vessels  would  usually 
keep  indefinitely  if,  after  being  sealed,  they  were  kept  for  an  hour  in 
boiling  water.  He  improved  the  process  in  1810  by  introducing  a 
method  of  sealing  the  cans  after  the  heating  process  had  driven  out  the 
air  and  replaced  it  with  steam,  so  that  when  cool  a  vacuum  is  formed. 
For  all  practical  purposes  this  is  the  universal  method  of  canning  to-day. 

In  recent  years,  the  method  of  fractional  sterilization  has  been  used 
especially  in  home  canning  processes.  In  this  method  the  cans  are 
given  a  second,  and  even  a  third  heating  after  intervals  of  24  hours, 
in  order  to  permit  the  germination  of  spores. 

Spoilage  may  result  from  insufficient  processing,  defective  con- 
tainers, or  the  use  of  unfit  material.  These  losses  are  generally  classed 
under  the  heads  of  sicells,  fat  sours,  and  leaks.  The  ends  of- a  swelled 
can  bulge,  and  when  opened  there  is  evidence  of  gaseous  fermentation 
and  spoilage.  "Flat  sour"  is  a  term  applied  to  the  acid  decomposition 
without  the  formation  of  gas.  "Leaks"  are  usually  due  to  imperfect 
covers  or  to  pin  holes. 

If  we  analyze  the  different  factors  responsible  for  the  spoilage 
of  canned  fruits  and  vegetables,  we  will  find  that  the  most  important 
are:  (1)  use  of  unfit  raw  material;  (2)  use  of  unfit  cans  and  glass 
jars;  (3)  carelessness  in  the  matter  of  cleanliness;  (4)  overfilling  of 
the  cans;  (5)  carelessness  in  sealing  the  cans;  (6)  imperfect  methods 
of  processing.  No  can  that  shows  evidence  of  spoilage  should  be  used 
as  food. 

Emphasis  has  always  been  placed  upon  the  necessity  of  a  vacuum 
for  the  proper  preservation  of  canned  foods.  Bacteriologists,  however, 
have  shown  that  sterile  foods  may  be  kept  indefinitely  either  in  the 
presence  or  absence  of  air.  Sterility,  then,  is  the  great  desideratum, 
both  from  the  sanitary  and  economic  standpoints.  The  time  and  tem- 
perature of  processing  varies  with  the  food  and  its  condition  as  to 
freshness  and  cleanliness.  Allowing  foods  to  stand  before  processing 
permits  resisting  molds  and  spores  to  form  and  renders  sterilization 
unnecessarily  difficult. 

There  is  also  a  prevalent  notion  that  once  opened,  the  contents  of 
the  can  should  be  emptied  into  some  other  vessel.  It  is  generally  be- 
lieved that  food  kept  in  an  open  tin  can  acquires  injurious  properties. 

^^  Nicholas  Appert,  in  France,  first  preserved  food  in  glass  jars  by  sealing 
them  hermetically  and  heating,  in  1804.  He  published  "The  Art  of  Preserving 
Animal  and  Vegetable  Substances"  in  1810.  In  1810  Peter  Durand  obtained  a 
patent  in  England  for  preserving  fruits,  vegetables  and  fish  by  hermetically  seal- 
ing them  in  tin  and  glass  cans.  In  1820  William  Underwood  and  Charles 
Mitchell,  emigrant  employees  from  a  canning  factory  in  England,  opened  a  fac- 
tory in  Boston  where  they  canned  plums,  quinces,  cranberries  and  currants. 
Glass  was  used  exclusively  until  1825,  when  Thomas  Kensett  secured  a  patent 
for  use  of  tin  cans  and  commenced  to  use  them  in  his  factory. 


IMnvSPMv'WVriON  OK  FOODS  7:51) 

'^rhis  is  a  fiil)k',  like  tlu'  sduriiiii'  of  milk  i]\u'  tn  a  thiiiiderstonii.  On 
the  other  hand,  canned  food  may  become  contaminated  or  infected  after 
opening,  and  the  same  care  as  to  cleaidiness  and  refrigeration  is  neces- 
sary as  with  fresh  food  or  willi  rooked  l\)od. 

The  process  of  canning  fortunately  does  not  interfere  seriously  with 
most  vitamins.  It  is  now  well  known  that  these  "unknown  dietary 
factors"  are  for  the  most  ])art  not  destroyed  by  heat  in  an  acid  medium; 
practically  all  our  foodstuffs  have  an  acid  reaction.  McCollum  and 
Davis"'  have  pointed  out  that  wheat  germ  can  be  moistened  and  lieated 
in  an  autoclave  at  fifteen  i)ounds  pressure  for  an  hour  or  more  without 
any  extensive  destruction  of  tlie  "water-soluble  B,"  and  McCollum, 
Simmonds  and  Pitz  ^®  ha\e  subjected  soaked  navy  beans  to  similar 
treatment  without  causing  any  great  deterioration  with  respect  to  this 
dietary  factor.  This  treatment  is  comparable  to  that  to  which  fruits 
and  vegetables  are  subjected  when  processed  in  canning,  and  shows  that 
the  widespread  belief  that  canned  foods  have  lost  these  dietary  essentials 
is.  at  least,  generally  without  foundation. ^'^  Hess  has  shown  that  canned 
tomatoes  retain  their  antiscorbutic  properties.  Condensed  and  evap- 
orated milk  retain  their  "fat-soluble  A"'  and  antineuritic  vitamins.  The 
antiscorbutic  vitamin  is  the  most  susceptible  to  heat  and  is  injured  or 
destroyed  in  many  cooked  or  canned  foods.  (Effect  of  heat  on  vitamins, 
page  672.) 

The  objection  is  sometimes  raised  that  the  contents  of  the  can  are 
improperly  sterilized  and  that  the  surviving  spores  germinate  at  tjie  first 
opportunity  and  cause  decomposition.  Fortunately,  an  improperly  steril- 
ized can  of  food  tells  its  own  story,  and  the  gaseous  products  of  putre- 
faction may  even  burst  the  tin  or  leave  the  food  in  such  condition  that 
when  the  can  is  opened  it  vrould  be  so  offensive  to  the  sense  of  smell  tliat 
no  one  w^ould  use  it. 

The  process  of  canning  fortunately  does  away  with  the  necessity 
of  using  chemical  preservatives  of  any  kind.  The  proper  authorities 
should  be  authorized  to  prohibit  the  canning  of  foodstuffs  that  have 
already  undergone  perceptible  decomposition,  or,  if  not  injurious  to 
health,  they  should  be  labeled  "second  quality."'  The  law  should  re- 
quire that  the  quantity  contained  Avithin  the  can  and  the  date  on 
which  it  was  put  up  as  well  as  the  amount  should  be  stamped  in 
the  tin.  This  phase  of  tlie  question  is  perhaps  more  of  economic  than 
of  hygienic  importance,  but  will  be  required  in  time  as  surely  as  the 
present  law  now  requires  honest  labeling  in  other  particulars. 

Before  meats  are  canned  they  are  first  parboiled  for  eight  to  twenty 
minutes,  in  order  to  secure  the  shrinkage  before  the  meat  is  placed  in 

"Journ.  Biol.  Chenu.  1915,  247. 

^Ibid.,  1!)17,  .521. 

'^MfCoUum:     "The  Newer  Knnwledgc  of  Xutritiou,"  ^lacinillau  Cu.,  I'JIS. 


740  GENERAL  CONSIDERATIONS 

the  can.  In  the  parboiling  there  is  a  certain  loss  of  fat,  soluble  mineral 
matter,  meat  bases,  and  water.  However,  the  shrinking  of  the  meat  con- 
centrates it,  as  far  as  nutritive  value  is  concerned,  and,  therefore,  com- 
pensates for  the  loss.  The  parboiled  meat  is  then  placed  in  the  tin  and 
a  small  quantity  of  the  soup  liquor  added.  The  cans  are  closed  and 
then  placed  in  autoclaves  and  subjected  to  steam  under  pressure.  Usu- 
ally a  small  hole  is  left  in  the  can  in  order  to  permit  the  exit  of  air 
and  gases.  This  is  sealed  off  at  once  after  heating.  The  cans  are  then 
subjected  to  a  second  heating  at  225°  to  250°  F.  from  one  to  two  hours. 
A  modified  process  consists  in  placing  the  cans  upon  an  endless  con- 
veyor which  exposes  the  can  to  a  high  temperature  in  an  oil  bath  a  suf- 
ficient length  of  time  to  sterilize  the  contents  at  one  exposure. 

In  Germany  tuberculous  and  trichinous  meat  is  sterilized  and  sold  as 
second  quality  meat  in  accordance  with  the  third  class  or  "freibank" 
meat  system.  There  is  no  known  sanitary  objection  to  this  practice, 
provided  the  sterilization  is  complete  and  the  label  represents  the  true 
nature  of  the  product.  This  practice  has  recently  been  recognized 
under  our  meat  Inspection  Service  of  the  U.  S.  Bureau  of  Animal 
Industry. 

Canned  foods  are  sterile  foods  and,  therefore,  generally  safe.  Fresh 
foods,  of  course,  are  to  be  preferred  to  those  that  have  been  preserved, 
although  many  unsterilized  foods  are  more  dangerous  in  the  fresh 
state  than  after  they  have  been  exposed  to  a  high  temperature.  The 
process  of  canning  has  proved  of  inestimable  benefit  to  mankind.  It 
enables  nourishing  food  of  a  perishable  character  to  be  kept  and  trans- 
ported to  great  distances  and  to  be  used  in  localities  where  fresh  foods 
are  unobtainable.  Without  this  method  of  preserving  foods  the  pioneer 
and  the  explorer  would  be  seriously  handicapped.  Large  army  and 
navy  maneuvers  would  be  materially  impeded,  and  great  metropolitan 
cities  would  be  impossible.  Wiley  states  that  "the  winning  of  the  West 
has  been  marked  by  the  debris  of  the  rusty  can." 

Canned  foods  are  not  only  safe,  but  are  quite  as  nutritious  as  the 
original  articles.  The  process  permits  us  to  have  a  well-balanced  ration 
throughout  the  year — irrespective  of  season.  The  canning  industry  is 
growing  to  enormous  proportions,  and,  on  account  of  the  great  impor- 
tance of  the  process,  the  character  and  quality  of  foods  thus  preserved 
should  be  M^holly  above  suspicion,  and  no  adulteration  or  sophistication 
of  any  kind  permitted.  Every  can  should  be  plainly  stamped  with  the 
quantity  and  true  nature  of  its  contents  and  also  the  date  when  it  was 
first  sterilized. 

Concerning  the  character  of  the  container  Wiley  states :  "Much  in 
the  direction  of  securing  a  better  product  may  be  .accomplished  by  a 
more  careful  selection  of  the  container.  The  common  method  of  pre- 
serving canned  goods  is  in  tin.    This  material,  as  is  well  known,  is  placed 


PKESERVATIOX  OF  FOODS  711 

oil  the  surfaco  of  slicet  iron  and  slionld  bo  free  of  other  metals.  Lead 
especially  should  be  excluded  from  the  composition  of  the  tin  as  far  as 
possible.  In  spite  of  all  these  precautions,  however,  the  coating  of  the 
tin  is  sometimes  broken,  so  that  the  iron  itself  may  be  attacked,  perfora- 
tions result,  and  the  package  of  goods  be  spoiled.  More  frequently,  how- 
ever, the  erosion  of  the  tin  plate  occurs  over  widely  extended  areas,  in- 
troducing into  the  contents  of  the  package  a  considerable  quantity  of  tin 
salts,  ^riiis  may  be  prevented  to  a  certain  degree  by  coating  the  surface 
of  the  till  with  a  gum  or  varnish  which  is  not  acted  upon  by  the  contents 
of  the  ])ackage.  (J lass  is  also  coming  into  more  general  use,  and  if  it 
could  be  secured  of  a  character  to  avoid  breakage  it  would  be  possible  to 
replace  to  a  considerable  extent  the  tin  packages  now  in  such  common 
use,  and  thus  prevent  the  introduction  of  soluble  tin  salts  into  food.  In 
this  case  the  glass  itself  should  be  free  of  lead,  borax,  and  finorids." 

Practically  all  foods  canned  in  the  ordinary  way  contain  some  tin. 
The  amount  varies  with  the  acidity,  and  also  the  age  and  temperature 
of  the  package.  Meat  extracts,  on  account  of  their  acidity,  take  up  more 
tin  than  do  most  other  meat  products.  For  the  same  reason,  certain 
fruits  and  vegetables,  such  as  canned  peaches,  cherries,  pears,  apricots, 
pineapple,  tomatoes,  asparagus  and  tomato  soup  take  up  tin  from  the 
can.  Canned  lobster  and  shrimp  are  relatively  active  as  solvents  of  tin 
on  account  of  the  amino-acids  they  contain. 

Fortunately,  tin  is  not  very  toxic.  Cushny  states  that  chronic  poi- 
soning from  tin  is  unknown,  and  that  animals  present  no  symptoms 
when  subjected  to  prolonged  treatment  with  larger  quantities  of  tin 
than  are  contained  in  any  preserved  foods.  Schryver  found  no  indica- 
tions of  cumulative  action  when  as  much  as  2  grains  per  day  is  taken. 
There  is  a  general  agreement  that  tin  plays  no  part  of  importance  in 
connection  with  food  poisoning,  acute  or  chronic. 

All  told,  canned  foods  are  the  safest  foods  that  come  to  our  table. 

Chemical  Preservatives. — Chemical  preservatives  are  nothing  more 
nor  less  than  antiseptic  substances;  that  is,  substances  which  restrain 
the  growth  and  development  of  bacteria  and  molds.  Chemical  preserva- 
tives in  the  proportions  commonly  used  may  have  little  or  no  germicidal 
action.  Such  substances  as  sugar^,  salt,  vinegar,  vinegar  extract  of  spices, 
and  the  pyroligneous  products  in  wood-smoke  are  not  regarded  as  "chem- 
ical" preservatives,  but  as  "natural"  preservatives  or  condimental  sub- 
stances, although  their  mode  of  action  is  precisely  the  same  as  the  chem- 
ical preservatives.  There  is  a  great  prejudice  against  the  use  of  any 
preservative  for  our  foods  if  this  preservative  is  a  "chemical"  or  "drug,'* 
whereas  no  objection  is  raised  to  the  same  substance  if  derived  from 
"natural"  sources.  '  Thus,  foods  exposed  to  a  smoldering  wood-fire  be- 
come impregnated  with  pyroligneous  acid,  which  includes  creosote, 
acetic  acid,  and  probably  formaldeh3'd  and  other  substances  having  anti- 


742   .  GENEEAL  CONSTDERATIONS 

septic  properties.  This  method  of  food  preservation  is  not  only  counte- 
nanced by  the  law,  but  is  favored  on  account  of  the  savory  result  and 
the  antiquity  of  this  "natural"  process. 

The  great  increase  in  the  use  of  chemical  preservatives  in  foods  dur- 
ing the  last  fifty  years  is  owing  to  the  fact  that  this  is  the  cheapest  and 
surest  method  of  preservation,  thus  offering  a  convenient  method  of  sup- 
plying the  needs  of  large  communities  as  well  as  remote  places.  The 
qnestion,  however,  has  an  economic  side  that  cannot  be  disregarded.  ■ 
Here,  however,  we  must  confine  ourselvfes  to  the  health  aspect  of  the 
problem.  Fortunately  we  possess  two  efficient  and  wholly  unobjection- 
able processes  for  the  preservation  of  food,  viz.,  refrigeration  and  steril- 
ization by  heat,  which  for  the  most  part  make  it  unnecessary  to  resort 
to  the  use  of  chemical  preservatives.  One  of  the  most  objectionable  uses 
that  can  be  made  of  chemical  preservatives  or  any  other  method  of  food 
preservation  is  to  conserve  foods  which  are  so  decayed  as  to  be  unfit 
or  possibly  injurious  to  health  if  used  fresh.  The  law  cannot  be  too 
strictly  enforced  in  order  to  prohibit  the  use  of  chemical  preservatives 
and  condiments  used  to  disguise  such  foods,  which  may  then  be  sold  at 
high  prices  as  first  quality. 

Upon  general  principles  it  is  undesirable  to  add  a  chemical  sub- 
stance of  whatever  nature  to  food  for  the  purpose  of  preserving,  coloring, 
or  improving  its  appearance,  and  in  most  countries  this  practice  is  pro- 
hibited by  law.  There  are,  however,  a  few  instances  in  which  the  ad- 
dition of  some  chemical  preservatives  in  minimal  amount  seems  harmless, 
and  occasionally  even  desirable,  as,  for  example,  small  quantities  of 
benzoate  of  soda  in  catsup;  a  thin  film  of  gum  benzoin  as  a  protective 
coating  for  chocolate,  etc. 

No  sweeping  generalization  can  be  made  concerning  all  chemical  pre- 
servatives. Each  substance  must  be  considered  for  itself,  and  each  sub- 
stance must  further  be  considered  in  relation  to  the  particular  foodstuff 
for  which  it  is  proposed.  It  may,  however,  be  stated  as  a  general  rule 
that  any  chemical  which  is  poisonous  in  large  amounts  should  be  con- 
sidered as  poisonous  in  small  amounts  until  the  contrary  is  proved. 
In  other  words,  the  consumer  is  entitled  to  the  benefit  of  the  doubt. 
The  toxicology  of  various  food  preservatives  is  in  its  infancy  and  fre- 
quently presents  a  very  difficult  and^  complex  problem.  Thus,  lead  in 
one  large  dose  is  not  particularly  harmful.  The  older  practitioners 
frequently  gave  twenty,  thirty,  and  more  grains  of  sugar  of  lead  (ace- 
tate of  lead)  for  diarrheal  affections.  Only  a  minute  portion  of  the 
lead  taken  in  one  large  dose  is  absorbed;  the  rest  is  quickly  eliminated. 
However,  if  the  same  amount  of  lead  should  be  taken  in  small  sub- 
divided daily  doses,  enough  would  be  absorbed  and  retained  by  the  tissues 
so  that  serious  chronic  lead  intoxication  would  develop,  resulting  from 
the  cumulative  action.     On  the  other  hand,  hydrocyanic  acid,  one  of 


PKESKUXATIOX   OF  FOODS  743 

the  most  poisonous  clu'iuicals  known,  is  liannless  in  small  amounts, 
for  the  reason  that  when  intioduccd  into  the  hody  it  meets  tiie  avaiUihle 
sulphur  (H.S),  witii  which  it  unites  to  form  a  sulphoeyanid.  as  KSC'X, 
The  j)otassium  sulphoeyanid  is  not  poisonous,  and  it  has  been  shown 
experimentally  that  animals  are  ahic  to  willistand  Jari^cr  (jnaiditics  of 
liydroeyanie  acid  hy  first  fiivin,i(  them  suhstanees  which  increase  the 
a\ailable  amount  of  sulphur  to  form  this  eheinieal  eomhination.  Ben- 
zole aeid  in  large  amounts  is  irritating  and  ])roduees  widl-dcfincd  symp- 
toms of  poisoning:  small  amounts  of  henzoie  aeid  are  paired  in  the 
liver  and  eliminated  by  the  kidneys  as  hippuric  acid,  a  normal  and  harm- 
less constituent  6f  the  urine.  Hydrochloric  acid,  common  salt,  and  pos- 
sibly acetic  acid  and  alcohol  are  all  poisonous  in  large  amounts,  but 
they  may  he  regarded  as  harmless  if  the  amounts  taken  are  suttieientlv 
small.  Even  common  salt  in  sufficient  concentration  is  poisonous,  and 
this  affords  a  favorite  method  of  suicide  in  China. 

The  point  at  issue  now  is  to  determine  which  of  the  chemical  sub- 
stances are  injurious  to  health.  In  the  present  transitional  state  of  our 
knowledge  it  is  not  possible  to  make  a  final  statement  concerning  all  or 
perhaps  any  one  of  them.  It  is  well  known  that  the  most  serious  poisons 
may  be  taken  in  minute  amounts  without  apparent  injury.  In  fact, 
many  medicinal  substances  in  the  pharmacopeia  are  very  poisonous,  but 
in  therapeutic  doses  may  be  quite  beneficial.  The  effect  of  the  con- 
tinued use  of  chemical  substances  in  small  amounts  wnll  require  long 
and  patient  observation  to  determine  whether  or  not  they  should  be 
permitted  as  food  preservatives.  Of  all  the  substances  so  far  brought 
forward,  the  least  harmful  is  benzoic  acid  and  benzoate  of  soda.  Hydro- 
chloric acid,  sodium  chlorid,  and  possibly  acetic  acid,  as  well  as  benzoic 
acid  and  alcohol,  are  poisonous  in  large  amounts,  but  seem  to  be  harm- 
less if  the  amounts  taken  are  sufficiently  small.  There  can,  however, 
be  no  defense  for  the  use  of  formaldehyd,  salicylic  acid,  sulphites,  and 
a  host  of  other  chemicals.  So  far  as  we  know^,  the  human  organism 
possesses  no  natural  mechanism  for  rendering  them  harmless. 

There  can  be  no  defense  for  the  use  of  chemical  preservatives  to  hide 
inferiority.  This  is  well  illustrated  in  the  case  of  bleached  flour.  The 
only  purpose  of  the  bleaching  is  to  make  the  flour  from  a  dark  wheat 
look  as  white  as  the  best  patent  flour.  It  was  recently  discovered  that 
this  "artificial  aging"  of  flour  may  be  accomplished  by  adding  nitrogen 
peroxid.  The  flour  absorbs  this  poisonous  gas  as  a  sponge  absorbs  water 
and  instantly  becomes  Avhite.  Processes  of  this  kind  should  be  regarded 
as  a  common  fraud,  for  the  flour  is  not  imjjroved  in  any  way  except  in 
appearance,  which  is.  after  all,  a  deception.  The  silly  process  of  modi- 
fying the  natural  colors  of  food  is  illustrated  in  the  use  of  copper  sul- 
phate to  give  peas  a  bright  green  hue,  and  the  use  of  aniliji  dyes  in 
glucose,  jellies,  fruit  juices,  ices,  and  other  substances  to   imitate  the 


744  GENERAL  CONSIDERATIONS 

color  of  natural  iiavoring  extracts.  "JSiatural"  colors,  such  as  caramel 
and  vegetable  substances,  are  also  frequently  used.  The  substitution  of 
cheap  chemicals  for  high-priced  natural  flavoring  extracts,  the  substitu- 
tion of  acetic  acid  or  even  mineral  acids  for  genuine  vinegar,  the  sub- 
stitution of  saccharin  for  sugar,  the  paraffin  polishing  of  rice,  and  sim- 
ilar devices  are  nothing  but  common  frauds,  which  may  in  some  cases 
also  be  injurious  to  health. 

Benzoic  Acid  and  Benzoate  of  Soda.— Benzoic  acid  is  an  organic 
acid  contained  largely  (12  to  20  per  cent.)  in  gum  benzoin,  and  also 
in  balsam  of  Peru  and  balsam  of  Tolu.  It  is  obtained  from  gum  ben- 
zoin, from  the  urine  of  herbivorous  animals,  and  artificially  from  toluene, 
by  treating  it  with  chlorin  and  heating  with  water  to  150°  C. 

The  storm  center  of  the  question  of  chemical  preservatives  in  this 
country  has  raged  about  the  use  of  sodium  benzoate.  Wiley  conducted 
experiments  upon  a  number  of  healthy  individuals  known  as  the  ''poison 
squad."  These  men  were  given  rather  large  quantities  of  sodium  ben- 
zoate with  their  meals  and  the  result  seemed  to  be  an  impairment  of 
the  appetite,  disturbance  of  digestion,  and  other  injurious  effects  in 
certain  instances.  On  the  other  hand,  the  Referee  Board  appointed  by 
President  Roosevelt  and  consisting  of  Remsen,  Chittenden,  Long,  Taylor, 
and  Herter  found  that  moderate  quantities  over  a  period  of  four  months 
have  no  appreciable  influence  upon  health. 

The  reason  why  benzoic  acid  in  moderate  amounts  is  believed  to  be 
harmless  is  that  the  body  possesses  a  special  mechanism  for  taking  care 
of  this  substance.  Many  of  our  ordinary  foods  contain  substances  which 
are  transformed  in  the  body  into  benzoic  acid.  Some  foods,  such  as 
cranberries,  contain  this  acid  in  notable  amounts.  Benzoic  acid  meets 
glycocoll  (one  of  the  decomposition  products  of  protein)  in  the  liver. 
Benzoic  acid  and  glycocoll  form  hippuric  acid,  a  normal  and  harmless 
constituent  of  the  urine.  We  know,  therefore,  that  the  human  organism 
is  prepared  to  take  care  of  and  render  harmless  a  certain  amount  of 
benzoic  acid;  we  know  that  this  mechanism  is  a  very  efficient  one 
and  is  capable  of  taking  care  of  relatively  large  amounts  of  benzoic 
acid. 

There  can  be  no  serious  objection  from  the  standpoint  of  health  to 
the  addition  of  0.1  per  cent,  of  sodium  benzoate  to  catsup,  on  account 
of  the  small  quantity  of  this  article  consumed  at  any  one  time.  Further, 
on  account  of  the  long  time  a  bottle  of  catsup  is  usually  kept  after  it 
is  opened  in  the  household,  there  is,  thus,  the  added  economic  gain 
of  preserving  the  catsup  until  it  is  all  consumed.  The  same  object 
may  be  obtained  by  the  use  of  a  sufficiently  strong  vinegar  extract  of 
spices,  but  the  question  may  be  asked  whether  the  aromatic  and  pre- 
serving substances  in  the  vinegar  extract  of  spices  may  not  be  more 
irritating  than  the  sodium  benzoate. 


PRESERVATION^  OE  EOODS  7^^» 

llotrman  and  leans'"  have  sliowii  t'lat.  ^Miigcr,  l)la(k  |)('i)|)('r,  aii<l 
cayenne  pepper  fail  to  prevent  (lio  ^^nowtli  of  microorganisms.  Xulnict: 
niul  allspieo  have  sli<jht  antisojjtic  pr()])orties,  hut  only  for  a  very  few- 
clays.  Cinnamon,  cloves,  and  mustard,  on  the  other  hand,  have  very 
marked  antiseptic  powers  and  are  valuable  preservatives.  The  active 
antiseptic  constituents  of  mustard,  cinnamon,  and  cloves  are  the  aro- 
matic or  essential  oils  which  they  contain. 

No  one  would  advocate  the  promiscuous  use  of  sodium  benzoate  in 
foodstuffs  generally.  Its  use  in  such  foods  as  cider  or  tomato  soup  may 
lie  questioned  on  account  of  the  amounts  that  would  be  taken  in  such 
articles.  Further,  benzoate  of  soda  placed  in  an  acid  medium  becomes 
benzoic  acid.  It  is  dif!icult  to  know  where  to  draw  the  line,  and  the 
consumer  must  be  given  the  benefit  of  the  doubt,  but  the  evidence  seems 
fairly  well  established  that  in  the  case  of  benzoate  of  soda  small  amounts 
are  harmless. 

The  question  has  a  large  economic  significance  in  addition  to  its 
sanitary  aspect,  for  it  is  claimed  that  benzoates  as  well  as  other  chemical 
preservatives  permit  the  use  of  rotten  tomatoes,  skins,  and  undesirable 
food  which  otherwise  could  not  readily  be  preserved.  Benzoate  of  soda 
is  a  rather  feeble  germicide  at  best,  and  in  such  dilute  proportions  as 
0.1  per  cent,  has  feeble  antiseptic  power. 

Borax  and  Boric  Add. — Both  boric  acid  and  borax  are  only  mild 
antiseptics.  They  are  not  ver}^  potent  germicides.  They  are  generally 
used  together,  for  the  reason  that  the  combination  of  the  two  is  more 
efficient  than  either  one  alone.  Locally  boric  acid  is  not  very  irritating, 
and  for  this  reason  it  has  been  extensively  used  in  surgical  practice. 
To  some  skins,  however,  it  is  very  irritating,  and  cases  are  reported  of 
its  absorption  from  wounds  and  cavities  when  used  too  freely,  causing 
depression  and  eruptions,  such  as  erythema  and  urticaria.  Fatal  results 
have  been  reported  in  a  few  cases  from  injecting  the  solution  into  abscess 
sacs,  or  from  washing  out  the  stomach  with  it;  or  from  taking  a  very 
large  amount  by  mouth.'^^ 

Boric  acid  and  borax  are  used  for  preserving  meats,  milk,  butter, 
oysters,  clams,  fish,  sausage,  and  other  foods.  For  meat  it  is  often  mixed 
with  salicylic  acid  and  applied  externally.  For  milk  it  was  a  common 
practice  to  add  to  one  quart  of  milk  10  grains  of  a  mixture  of  equal  parts 
of  borax  and  boric  acid;  for  butter  the  amount  used  is  about  one-tenth 
of  an  ounce  to  the  pound. 

The  effect  of  small  amounts  of  boric  acid  and  borax  upon  healthy 
human  beings  has  been  extensively  studied  and  has  resulted  in  conflicting 
testimony. 

^"Journal  of  Industrial  and  Engineering  Chemistry,  Nov.,  1911    p.  835. 
"J.  A.  M.  A.,  Feb.  5,  1921,  LXXVI,  p.  378. 


746  GENERAL  OOXSTDEIUTIONS 

-1 
On  one  hand  we  have  the  researches  of  Chittenden  '^-  and  Liebreich  '" 

with  dogs  fed  upon  articles  containing  borax  and  boric  acid.  To  say 
the  least,  in  both  series  the  digestion  of  the  food  was  not  notably  im- 
paired and  the  animals  gained  in  weight.  The  same  result  followed 
the  experiment  made  by  Liebreich  upon  rabbits  and  guinea-pigs.  No 
injury  appears  to  have  followed  the  administration  of  boric  acid  to 
pigs,  calves,  and  children  by  the  British  Commission.^*  Tunnicliffe  " 
made  experiments  from  which  he  inferred  that  neither  borax  nor  boric 
acid  affected  the  health  of  the  children  experimented  on.  Vaughan  and 
Yeenboer  ^''  conclude  that  in  the  small  amounts  required  for  preserving 
cream  and  butter,  and  that  used  as  an  external  dust  on  hams  and  bacon, 
both  boric  acid  and  borax  are  unobjectionable  from  a  sanitary  stand- 
point. 

On  the  other  hand,  the  experiments  made  by  H.  E.  Annette  '^'  led 
him  to  an  opposite  conclusion.  He  found  boric  acid  injurious  to  kittens, 
and  naturally  assumed  that  the  use  of  milk  containing  it  might  be  hurt- 
ful to  young  infants.  Foster  and  Schlenker  ''^  found  that  albumin  diges- 
tion was  impaired  by  boric  acid,  which  also  produced  increased  desquama- 
tion of  the  intestinal  epitliGlium.  Doane  and  Price''-'  made  experiments 
on  calves  which  indicate  that  borax  and  boric  acid  in  milk  retard  diges- 
tion to  a  slight  extent. 

As  these  substances  are  not  normal  constituents  of  the  body,  nor 
are  they  normal  constituents  of  foods,  the  conservative  course  would  be 
to  avoid  their  use  until  satisfactory  evidence  has  been  adduced  that  they 
are  free  from  harm  in  the  amounts  commonly  used  for  preserving  food. 

Formaldehyd. — Formaldehyd  has  been  and  still  is  used  extensively 
as  a  preservative  for  milk  and  other  articles  of  food.  Concentrated 
solutions  of  formaldehyd  in  large  quantities  is  irritating,  and  death  in 
isolated  instances  has  been  reported  from  the  swallowing  of  amounte  of 
from  1  to  3  ounces.  There  has  been  much  discussion  as  to  the  effect  of 
the  small  quantities  ordinarily  used  as  a  food  preservative.  Bliss  and 
Novy  ^°  and  Halliburton  *^  have  shown  conclusively  that  small  quantities 
of  formaldehyd  greatly  delay  the  digestion  of  proteins  by  the  gastric  and 
pancreatic  juices,  the  digestion  of  starch  by  the  pancreatic  juice,  and  the 
curdling  of  milk  by  rennet.  It  is  also  known  that  some  individuals  are 
especially  susceptible  to  the  effect  of  formalin,  small  quantities  in  the 

'''^American  Jour,  of  Physiology,  18fl8. 

''^  Vierteljahresschrift  fiir  gericht.  Med.,  1909;  also  Lancet,  Jan.  6,  1900. 
'^  Vierteljahresschrift  fur  gericht.  Med.,  1901. 
''^Journal  of  Hygiene,  1901. 
''^American  Medicine,  March  13,  1902. 
'"Lancet,  Nov.  11,   1899. 

"  Quoted  in  report  of  Kober  on  "Milk  Preservatives,"  U.  S.  Senate  Commis- 
sion, 1902. 

''^Bulletin  No.   86,  Maryland  Agricultural  Experiment  Station,   Sept.,   1902. 
^"Jour.  of  Exp.  Medicine,  1899,  Vol.  IV,  p.  47. 
^^  British  Medical  Jour.,  1900,  Vol.  II,  p.   1. 


PRKSKlv' NATION   OF  FOODS  7^ 

food  causiiiu-  ilyspcpsia  aiul  oilier  (listurbaiK-cs  ol'  digestion.  Fornial- 
deliyd  unites  directly  with  inotciii  matter  to  form  new  compounds  ol" 
iin  undctrriniiicd  inifiii'c.  'i'liiis,  I'ormaldeliyd  ad<l('d  to  egg  albumin 
prc\en<s  its  i-oagidation  \)\  heat,  and  added  to  gelatin  prrvoiils  lirpicfac- 
tioii.  II  hardens  tissues,  so  tliat  it  will  render  fish  and  meat  touLili  and 
hriUlc,  ('\('ii  ill  |)i'ii|i(ii  t  idiis  as  dilute  as  1  to  .").()()(),  lieiice  it  is  not  geii- 
eralK  applicalile  ;is  a  food  pi'esei'\al  i\('.  In  small  amounls  it  delays 
(leciiuipdsiliiiii  :  in  large  amounts  it  is  an  active  germicide.  Its  use  iu 
milk  was  recently  ad\(icated  liv  no  less  an  authority  than  \(Ui  Px'liring, 
hut   this  \  iew  met   with  almost    unanimous  protest. 

There  can  he  only  one  opinion  concerning  the  .use  of  formaldehyd 
in  foods,  and  that  is  absolute  condemnation  of  the  ])ractice.  It  is  pro- 
hibited by  the  statutes  of  practically  all  nations  having  pure  food  laws. 

Salicylic  Acid. — Individuals  differ  greatly  in  their  susceptibility 
to  salicylic  acid.  In  mild  cases  of  poisoning  with  this  substance  there 
is  a  feeling  of  fullness  in  the  head  with  roaring  sounds  in  the  cars, 
dimness  of  vision,  profuse  perspiration,  confusion,  and  dullness.  Large 
doses  of  the  acid  cause  intense  irritation  of  the  throat  and  stomach, 
leading  to  vomiting  and  difficulty  in  swallowing.  Later  there  may  be 
diarrhea.  Eczema  and  other  skin  eruptions  may  appear,  and  dimness 
of  vision  and  deafness  may  continue  for  some  time.  The  long-continued 
use  of  salicylic  acid  and  its  salts  has  led  to  a  form  of  chronic  poisoning 
in  which  the  chief  symptoms  have  been  loss  of  appetite,  diarrhea  al- 
ternating with  constipation,  irritation  of  the  kidneys,  skin  eruptions, 
and  mental  depression.  Such  results  are  said  to  have  followed  the  use 
of  articles  of  diet  preserved  with  salicylic  acid.  The  use  of  such  foods 
may  be  objectionable  in  the  case  of  aged,  feeble,  and  susceptible  per- 
sons. Salicylic  acid  and  the  salicylates  are  more  efficient  antiseptics 
than  boric  acid  or  borax,  but  they  are  not  used  extensively  on  account 
of  the  taste,  or  rather  the  tendency  to  cause  unpleasant  flavors.  They 
are  for  the  most  part  used  in  jams,  fruit  juices,  soda  water  syrups,  cider, 
wines,  and  other  sweet  preparations.  The  objection  to  the  use  of  salicylic 
acid  in  food  is  practically  unanimous  and  well  founded. 

Sodium  Nitrate. — Sodium  nitrate  or  ])otassium  nitrate  (saltpeter) 
is  not  used  as  a  preservative,  but  as  an  indirect  coloring  matter.  It 
retains  and  accentuates  the  red  color  of  meat.  It  is  not  known  to  be 
harmful  in  the  small  quantities  in  which  it  is  commonly  employed,  hut 
must  be  regarded  as  a  fraud  when  used  to  make  stale  meat  look  fresh. 

Potassium  Permanganate  is  also  used  on  the  surface  of  meat  to 
destroy  the  surface  evidence  of  decomposition.  This  may  be  detected 
by  heating  a  knife  in  hot  water,  plunging  it  into  the  meat,  and  with- 
drawing it  quickly.  This  brings  out  the  hidden  odors  of  putrefactive 
changes. 


748  GENERAL  CONSIDERATIONS 

Sodium  Fluorid. — Sodium  fluorid  has  been  extensively  used  as  a 
preservative,  antiseptic,  and  insecticide.  It  has  considerable  antiseptic 
power,  putrefaction  being  delayed  by  the  addition  of  1  part  to  500;  and 
1  in  200  arrests  completely  the  growth  of  bacteria.  It  is  highly  poisonous 
to  nearly  all  the  lower  forms  of  life,  especially  to  microorganisms,  includ- 
ing algae.  It  does  not  coagulate  protoplasm  but  acts  as  a  general  proto- 
plasmic poison.  For  mammals,  sodium  fluorid  is  not  a  very  toxic  sub- 
stance, the  fatal  dose  by  the  mouth  being  0.5  gram  per  kilogram  of  body 
weight,  and  subcutaneously  0.15  gram  per  kilogram  of  body  weight.  The 
fluorids  on  administration  are  deposited  in  the  bones,  which  usually 
become  white  and  brittle,  and  contain  crystals  of  calcium  fluorid.  It  is 
well  to  call  attention  to  the  fact  that  fluorin,  in  very  small  traces,  is  a 
normal  constituent  of  bone,  teeth,  milk,  eggs,  etc.  In  large  amounts  and 
concentrated,  it  is  directly  irritating  to  the  mucous  membrane  and 
produces  vomiting,  diarrhea,  and  abdominal  pains.  Death  of  a  ten-year- 
old  girl  has  been  caused  by  the  ingestion  of  one  teaspoonful  in  a  little 
water,  given  in  mistake  for  Rochelle  salt.^^  Baldwin  *^  reports  a  number 
of  cases  of  sickness  and  death  resulting  from  the  accidental  ingestion  of 
sodiimi  fluorid,  usually  taken  in  mistake  for  baking  powder.  Recovery 
from  non-fatal  doses  is  usually  rapid  and  complete.  There  is  no  evidence 
that  small  quantities  ingested  daily  for  a  long  period  of  time  are  harmful. 

Sodium  fluorid  forms  the  basis  of  most  roach  powders  which  contain 
from  16  to  47  per  cent,  of  the  fluorid  finely  ground  up  and  intimately 
mixed  with  the  bait.    It  is  fatal  to  roaches  when  so  ingested. 

Hydrofluoric  Acid. — Schultz  ^'^  exposed  cats  for  four  days  to  con- 
centrated fumes  of  hydrofluoric  acid  without  serious  effects.  The  air 
was  so  impregnated  that  glass  held  at  some  distance  from  the  source 
was  etched.  Hydrofluoric  acid  is  much  used  in  breweries  for  disinfecting 
vats  and  tanks.     It  is  a  powerful  germicide. 

Sulphites. — Sulphites  act  as  antiseptics  and  also  preserve  the  red 
color  of  meats.  Sodium  sulphite  and  bisulphite  and  sulphurous  acid 
are  used  principally  upon  fresh  meats,  where  they  act  as  a  preservative 
and  as  a  retainer  of  color.  Sulphur  dioxid  is  also  much  employed  for 
the  bleaching  of  fruits.  Sulphites,  even  in  minute  amounts,  interfere 
with  the  action  of  ferments,  and  thus  influence  digestion.  Free  sulphur- 
ous acid  is  very  irritating.  Sodium  sulphite  is  very  poisonous  when 
injected  subcutaneously  or  intravenously.  Death  occurs  by  paralysis 
of  respiration.  Much  larger  quantities  are  tolerated  by  the  mouth,  the 
sulphite  being  slowly  absorbed.  The  greater  part  is  converted  to  the 
harmless  sulphate  during  and  after  absorption.  The  quantities  ordinarily 
used  in  preserved  food  cause  no  immediate  symptoms,  even  when  con- 

^^Hickev,  C.  H.:  Mass.  St.  Board  of  Health  Bull,  Dec,  1911.  Vol.  VI,  No. 
12.  p.  341. 

"'Baldwin,  H. :     Jour.  Am.  Ohem.  Soc.  1899.  Vol.  XXI.  p.  .517. 
'^Sclulltz,  K.:     Arch.  f.  Exp.  Path.,  1889. 


THE  PTfRPATJATTON  OF  FOOD  MO 

tiiiued  J'or  several  inuntlis.  11',  liowevci-,  I  lie  aiiiinals  are  killed  and  exam- 
ined, extensive  hemorrhagic  and  inflammatory  lesions  are  found  in 
various  organs."-''  These  lesions  are  prohably  due  to  destruction  of  red 
blood  cells  or  infarction.  Harrington  in  1904  also  described  nephritic; 
changes.  In  1898  the  Imperial  Board  of  Health  in  Germany  forbade 
the  use  of  sodium  sulphite  in  food  on  account  of  its  dangerous  properties, 
and  it  is  also  forbidden  by  our  Federal  Pure  Food  Act  of  190(). 

Sodium  Bicarbonate. — Sodium  bicarbonate  is  too  ineffective  as  a 
germicide  for  general  use  as  a  food  preservative.  It  is  sometimes  added 
to  milk  in  order  to  neutralize  the  excess  of  acid. 

Hydrogen  Pero.rid. — Hydrogen  peroxid  is  perliaps  one  of  the  least 
dangerous  of  the  chemical  preservatives,  and  is  considered  by  some  to 
exert  no  deleterious  effect  whatever  in  the  quantities  commonly  used,  ft  is 
used  for  the  preservation  of  wine,  beer,  and  fruit  juices,  and  also  in  milk. 

Arsenic. — Arsenic  in  food  comes  from  a  variety  of  sources.  Glu- 
cose is  apt  to  contain  it.  especially  if  impure  acid  is  used  to  hydrolyze 
starch  in  the  production  of  glucose.  This  was  the  source  of  the  arsenic 
in  the  beer  which  caused  the  epidemic  of  peripheral  neuritis  in  1900  in 
England.  Samples  of  tlie  glucose  contained  from  0.01  to  0.1  per  cent, 
of  arsenic.  The  finished  beer  contained  from  1  to  3  grains  of  arsenic 
per  gallon.  Arsenic  may  also  contaminate  certain  anilin  dyes  as  well 
as  shellac,^"  which  is  now  so  much  used  as  a  coating  for  some  kinds  of 
cheap  confectionery  and  bakers'  goods,  and  also  as  a  varnish  on  recep- 
tacles and  containers  of  various  kinds.  Another  source  of  arsenic  in 
food  is  from  insecticide  sprays  (page  279). 

In  England  liquid  food  is  considered  adulterated  if  it  contains  as 
much  as  0.01  grain  of  arsenic  per  gallon,  and  solid  foods  are  considered 
deleterious  if  they  contain  as  much  as  0.01  grain  per  pound. 

The  use  of  preservatives  containing  lead,  arsenic,  or  other  substances 
known  to  be  poisonous  finds  no  advocates. 


THE  PREPARATION  OF  FOOD 

Cooking. — Cooking  may  be  regarded  as  the  greatest  sanitary  inno- 
vation ever  introduced  by  man  to  protect  himself  against  infection. 
The  heat  required  for  thorough  cooking  kills  most  microorganisms  patho- 
genic for  man  and,  therefore,  renders  food  safe,  so  far  as  these  dangers 
are  concerned.  The  heat  also  kills  the  true  bacterial  toxins,  which  are 
destroyed  in  a  few  minutes  at  70°  C,  Foods  may  sometimes  contain 
heat-resisting  poisons.     Thus,  boiling  has  no  effect  upon  muscarin,   a 

'"Kionka  and  Ebstein,  1902. 

«« Smith.  B.  H.:  "The  Arsenic  Content  of  Shellac  and  the  Contamination  of 
Foods  from  This  Source,"  Cir.  91,  U.  S.  Dept.  Agr.,  Bureau  of  Chemistry, 
Washington,   1912. 


750  GENERAL  COXSTDETJATIONS 

poison  in  certain  toadstools.  Heat  also  does  not  destroy  a  principle 
sometimes  found  in  poisonous  mussels.  The  colon  bacillus  and  other 
microorganisms  produce  thermostable  substances  that  are  poisonous  when 
injected  into  the  lower  animals,  but  the  relation  of  these  heat-resisting 
toxic  substances  to  food  poisoning  in  man  is  conjectural.  It  is  highly 
improbable  that  foods  contain  heat-resisting  poisons  resulting  from  bac- 
terial decomposition  that  are  injurious  when  taken  by  the  mouth. 

Tricliinae.  according  to  some  authorities,  die  at  65°  C,  but  the 
Bureau  of  Animal  Industry  after  repeated  experiments  places  the 
thermal  death  point  at  a  temperature  of  55°  C;  some  writers  state  that 
cysticerci,  or  the  larval  stage  of  tapeworms,  die  at  52°  C. ;  the  non- 
sporulating  bacteria  are  for  the  most  part  destroyed  at  60°  C.  Food 
thoroughly  cooked  throughout  will  always  reach  these  temperatures, 
but  much  meat  and  many  vegetable  food  substances  are  preferred  rare 
or  underdone,  and,  while  the  outside  of  a  large  piece  of  meat  may  be 
thoroughly  cooked  or  even  charred,  -the  interior  may  be  practically  raw 
or  at  least  not  have  reached  the  temperature  necessary  to  destroy  para- 
sites. A  dish  of  spaghetti,  charred  on  the  outside,  may  not  kill  typhoid 
bacilli  in  the  center  of  the  mass   (page  115). 

Meat  that  is  well  cooked  throughout  always  reaches  from  60°-70°  C. 
on  the  inside.  It  should  be  remembered  that  heat  penetrates  a  large 
piece  of  meat  slowly.  For  example,  it  requires  1%  hours  in  boiling 
water,  for  the  temperature  to  reach  62°  C.  in  the  interior  of  a  piece 
of  meat  weighing  3%  pounds.  Meat  placed  in  a  quick  oven  or  broiled 
soon  forms  a  hard,  coagulated  and  insulated  coating  that  retains  the 
juices,  but  retards  the  peiietration  of  the  heat.     See  also  page  695. 

.  Cooking  softens  the  connective  tissue  and  renders  meat  more  ten- 
der. The  bundles  of  fibrillae  are  loosened  from  each  other,  the  albumin 
is  coagulated,  the  flavors  are  improved,  and  new  flavors  are  developed, 
all  of  which  enhance  its  digestibility. 

Metchnikoff  in  his  "new''  hygiene  dwells  upon  the  great  sanitary 
value  of  cooking.  Perhaps  no  other  single  factor  in  preventive  medi- 
cine protects  us  to  an  equal  degree  against  infection.  Metchnikoff  be- 
lieves that  we  should  eat  nothing  in  its  raw  state.  This  seem  almost  as 
extreme  as  the  cult  which  proclaims  the  contrary.  If  for  any  reason 
cooking  were  to  cease,  there  would  be  such  a  great  increase  of  infections 
as  to  amount  to  a  calamity. 

One  of  the  important  functions  in  the  preparation  of  food  is  to 
render  it  savory,  tender,  and  appetizing.  Foods  that  appear  inviting 
aid  digestion  by  stimulating  the  secretion  and  flow  of  the  digestive 
juices.  Foods  that  are  rendered  soft  and  tender  are  more  readily  di- 
gested, but  it  should  not  be  forgotten  that  the  teeth  need  exercise  to 
keep  them  in  good  condition.  Tough  meats  may  be  pounded  to  separate 
the  connective  tissue  bundles,  or  may  be  chopped  or  minced  as  an  arti- 


Till-:  I'1m:i'ai;a  rio.x  ok  food  751 

ficial  aid  to  inasticatiuii,  or  may  be  stecpt'd  for  .several  liours  in  fresh 
milk  or  sour  milk,  in  which  case  the  fibers  are  softened  throufih  the 
action  of  the  bacteria  and  their  enzymes.  In  the  case  of  vegetables, 
cookin<r  breaks  open  and  softens  the  cellulose  envelopes  and  fibers;  the 
starch  <rrains  swell  and  burst,  and  the  insoluble  starch  is  converted  into 
soluble  starch  or  dextrin. 

Cooking  has  a  few  minor  di.sadvantages — there  is  a  hjss  of  mineral 
salts,  and  .some  of  the  nutritive  constituents,  also  a  diminution  in  the 
antiscorbutic  property  of  food  generally. 

Fermentation  is  of  great  use  in  the  preparation  oi  foods.  The  best 
example  is  the  leavening  of  bread.  The  yeast  ferments  the  carbohydrates 
in  the  flour  with  the  production  of  carbon  dioxid  and  alcohol.  The 
carbon  dioxid  renders  the  bread  porous;  the  gas  is  held  within  the  loaf 
on  account  of  the  glutinous  property  of  the  protein  (gluten)  in  the 
flour.  Fermentation  is  an  adjunct  in  the  preparation  of  many  other 
foods  and  beverages,  such  as  cheese,  sauerkraut,  vinegar,  beer,  wine, 
cider,  etc. 

The  observations  of  Becker,  Grove,  and  others  concerning  the  heat 
of  cooking  are  practical  and  important  in  the  preparation  of  food.  Ex- 
posure to  moist  heat  at  60°  to  70°  C.  for  a  long  time  has  the  advantage  of 
cooking  foods  thoroughly  throughout.  This  treatment  prevents  burning 
or  the  results  of  overheating;  the  juices  are  retained.  The  process 
requires  little  or  no  attention.  ]\Ieat  is  thereby  rendered  tender  and 
juicy,  vegetables  thoroughly  soft,  and  the  starch  grains  are  all  opened. 
A  modification  of  this  method  is  found  in  the  tireless  cookers  now  offered 
for  sale  in  various  forms.  These  devices  consist  simply  of  a  well- 
insulated  box.  The  food  is  first  heated,  then  placed  in  suitable  compart- 
ments, and  a  temperature  above  70°  C.  maintained  for  many  hours. 

Certain  precautions  are  advisable  in  the  choice  of  pots  and  pans 
used  in  cooking.  Brass  and  copper  are  not  advisable,  and  if  used  must 
be  kept  scrupulously  clean.  Copper  acetate  (verdigris)  which  sometimes 
forms  in  copper  food  containers,  is  greatly  feared  but  is  not  very  toxic. 
Acid  foods  should  not  be  cooked  in  copper  vessels,  and  milk  and  saccharin 
substances  should  not  be  kept  in  copper  containers  on  account  of  the 
possibility  of  the  organic  acids  dissolving  the  copper.  Tin,  nickel,  and 
aluminum  ware  are  least  objectionable.  Enameled  ware  is  entirely 
satisfactory,  provided  it  does  not  contain  lead. 

Methods  of  Cooking. — ^Nluch  depends  upon  the  method  of  cooking. 
The  principal  -methods  in  ordinary  use  are :  roasting,  broiling,  boiling, 
frying,  and  stewing, 

Ro(i.sting  or  hroiling  causes  considerable  shrinking,  due  mainly  to 
loss  of  water.  The  heat  coagulates  the  exterior  of  the  meat  and  thus 
prevents  the  further  loss  of  juices  and  drying  up.  In  order  to  obtain 
adequate  heating  of  the  meat  throughout  a  large  joint  without  burning 


752  GENEEAL  CONSIDERATIONS 

and  drying  the  exterior,  it  is  necessary  to  baste  it  from  time  to  time 
with  hot  melted  fat.     This  also  helps  to  form  a  protective  coating. 

In  boiling  the  meat  is  placed  either  in  hot  or  cold  water,  depending 
upon  the  object  desired.  If  it  is  desired  to  maintain  the  flavors  within 
the  mass,  the  meat  should  be  plunged  into  boiling  water.  This  quickly 
coagulates  the  albumins  at  the  surface.  If  a  rich  broth  is  desired  the 
meat  should  be  placed  in  cold  water  and  gradually  heated.  In  this 
way  the  soluble  proteins  and  extractives  pass  out  into  the  surrounding 
Avater.  The  albumin  of  meat  begins  to  coagulate  at  134°  F.  (56°  C.)  ; 
the  connective  tissue  is  changed  to  gelatin  and  dissolved  above  160°  F. 
(72°  C).    Long  boiling  makes  meat  fibers  tough. 

Frying  consists  in  placing  meat  or  other  substances  into  very  hot 
fat,  lard,  or  vegetable  oil.  This  causes  a  speedy  coagulation  of  the 
surface  similar  in  all  respects  to  that  brought  about  in  the  first  men- 
tioned process  of  boiling.  The  flavors  and  juices  are  thereby  retained. 
If  the  fat  is  not  very  hot  it  will  penetrate  the  tissues  and  cause  the 
meat  or  other  substance  to  become  greasy  and  unpalatable.  Fried  sub- 
stances are  apt  to  be  indigestible  on  account  of  the  large  amount  of 
grease  that  adheres  to  and  penetrates  into  them.  It  is,  therefore,  better 
to  plunge  food  into  deep  fat,  piping  hot. 

In  stewing  the  meat  is  cut  into  small  pieces  and  placed  in  cold 
water,  which  then  is  heated  slowly  to  about  180°  F.  (81°  C),  at  which 
the  whole  is  kept  for  several  hours.  If  heated  above  180°  F.  the  meat 
becomes  tough,  stringy,  unpalatable,  and  of  diminished  digestibility. 


CHAPTER    II 
ANIMAL  FOODS:    MILK 

The  animal  foods  used  by  man  are  not  of  great  variety  and  source. 
They  include  the  flesh  and  various  organs  of  the  herbivorous  animals, 
swine,  domestic  and  wild  fowl,  eggs,  fish,  shellfish,  insects  and  their 
products  (honey),  milk,  and  milk  products.  The  flesh  of  carnivorous 
animals,  except  that  of  fish,  is  unpalatable  and,  therefore,  undesirable 
as  a  food. 

The  most  important  animal  foods  from  the  standpoint  of  the  sani- 
tarian are  milk  and  meat. 

MILK 

Milk  is  our  most  important  food.  It  is  the  best  single  food.  The 
exceptional  value  of  milk  is  due  to  the  fact  that  it  contains  all  the 
essentials  of  a  balanced  diet ;  it  is  rich  in  vitamins,  the  quality  of  its 
protein  is  especially  high,  the  fat  favors  growth,  and  it  has  a  high 
calcium  content  in  readily  usable  form.  Milk,  furthermore,  is  palatable, 
readily  digestible,  and  is  subject  to  a  great  variety  of  modifications. 
Even  at  present  prices,  it  is  one  of  the  cheapest  of  the  standard  articles 
of  diet,  and  the  most  economical  source  of  protein.  Milk  is  a  protective 
food,  in  that  it  guards  against  deficiency  diseases  when  used  in  com- 
bination with  other  foodstuffs  of  either  animal  or  vegetable  origin, 

"Those  peoples  who  have  employed  the  leaf  of  the  plant  as  their 
sole  protective  food  are  characterized  by  small  stature,  relatively  short 
span  of  life,  high  infant  mortality,  and  by  contended  adherence  to  the 
employment  of  the  simple  mechanical  inventions  of  their  forefathers. 
The  peoples  who  have  made  liberal  use  of  milk  as  a  food,  have,  in 
contrast,  attained  greater  size,  greater  longevity,  and  have  been  much 
more  successful  in  the  rearing  of  their  young.  They  have  been. more 
aggressive  than  the  non-milk  using  peoples,  and  have  achieved  much 
greater  advancement  in  literature,  science  and  art.  They  have  de- 
veloped in  a  higher  degree  educational  and  political  systems  which  offer 
the  greatest  opportunity  for  the  individual  to  develop  his  powers.  Such 
development  has  a  physiological  basis,  and  there  seems  every  reason  to 
believe  that  it  is  fundamentally  related  to  nutrition."  ^     (McCollum.) 

*"The  Newer  Knowledge  of  Nutrition,"     The  Macmillan  Co.,  1918. 

753 


.754  ANIMAL  FOODS:    MILK 

The  sanitarian  therefore  has  every  reason  to  encourage  the  use  of 
milk,  and  to  insist  upon  the  supply  being  fresh,  clean  and  safe.  Chil- 
dren should  drink  a  quart  of  milk  a  day,  adults  a  pint. 

The  total  milk  production  in  the  -United  States  in  1919  was  ten 
billion  gallons.  One-quarter  of  this  is  consumed  as  milk  and  the  re- 
maining three-quarters  is  used  for  butter  and  cheese.  The  average  per 
capita  consumption  of  milk  in  the  United  States  is  about  0.6  of  a  pint 
daily.  IMore  milk  is  used  in  the  Xorth  than  in  the  South;  very  little  in 
the  troj^ics,  and  practically  none  at  all  in  China,  Japan,  and  some  other 
countries.  About  16  per  cent,  of  the  average  dietary  in  the  United 
States  consists  of  milk  and  milk  products. 

Milk  has  certain  disadvantages  that  must  be  taken  into  account. 
As  the  sole  article  of  diet  for  adults,  it  lacks  iron  ^  and  roughage;  it 
tends  to  produce  constipation  and  because  of  its  high  protein  content 
may  lead  to  putrefactive  changes  in  the  intestines. 

Milk  is  probably  responsible  for  more  sickness  and  deaths  than  per- 
haps all  other  foods  combined.  There  are  several  reasons  for  this:  (1) 
Milk  conveys  a  greater  variety  of  infections  than  any  other  food.  Bacteria 
grow  well  in  milk;  therefore,  a  very  slight  infection  may  produce  wide- 
spread and  serious  results;  (2)  of  all  foodstuffs  milk  is  the  most  diffi- 
cult to  obtain,  handle,  transport,  and  deliver  in  a  clean,  fresh,  and 
satisfactory  condition;  (3)  it  is  the  most  readily  decomposable  of  all 
our  foods;  (4)  finally,  milk  is  the  only  standard  article  of  diet  obtained 
from  animal  sources  consumed  in  its  raw  state. 

Fresh  milk  products  may  be  quite  as  dangerous  as  the  milk  from 
which  they  are  made.  Milk  laws  which  ignore  milk  products  are  in- 
complete from  the  sanitary  side,  and  will  fail  to  accomplish  their  pur' 
pose  from  the -economic  side. 

Milk  is  a  perfect  food  for  the  suckling.  It  is  the  best  single  food 
to  promote  growth  and  nutrition  in  growing  children.  It  contains  all 
the  essential  elements  of  a  well  balanced  diet  for  the  adult.  As  a 
sole  article  of  diet,  it  lacks  iron  and  roughage.  At  prevailing  prices  it 
is  one  of  the  cheapest  of  the  standard  articles  of  diet.  Furthermore, 
it  is  readily  digestible,  and  is  capable  of  a  great  variety  of  modifica- 
tions. The  sanitarian  therefore  has  every  reason  to  encourage  the  use 
of  pure  milk,  as  well  as  to  discourage  the  use  of  poor  milk. 

Composition. — Milk  is  the  secretion  of  the  mammary  gland.  In 
composition  it  is  exceedingly  complex,  consisting  chiefly  of  water;  several 
proteins  in  colloidal  suspension ;  fats  in  emulsion ;  sugar,  and  a  number 
of  inorganic  salts  in  solution ;  also  vitamins,  phosphatids,  enzymes,  as 

^Milk  is  deficient  in  iron.  It  has  long  been  known  that  there  is  depositt'd 
in  the  spleen  of  the  nev.'-born  animal  a  reserve  supply  of  iron,  which  ordinarily 
suffices  to  tide  it  over  the  suckling  period.  Ordinary  drinking  water  almost 
always  contains  small  amounts  of  ii'on,  and  this  doubtless  aids  in  some  degree 
in  preventing  iron  starvation   in  the  infant. 


^IILK  755 

well  as  antibodies,  cells,  gases,  and  other  substances.  Milk  Ironi  all 
species  of  animals  shows  a  general  agreement  in  /physical  properties  and 
composition,  containing  essentially  the  same  ingredients,  but  exhibiting 
differences  in  the  relative  amounts  of  the  several  constituents. 

In  the  fresh  state  milk  is  a  yellowish  white,  opaque  fluid.  Cow's 
milk  has  a  specific  gravity  of  1.027  to  1.035;  it  freezes  at  a  temperature 
somewhat  lower  than  the  freezing  point  of  water  ( — 0.554°  C.)  ;  the 
electrii-al  conductivity  is  43.8X10—'  for  cow's  milk,  and  22A\X'i-^^'' 
for  human  milk.  In  other  words,  58  per  cent,  of  the  molecules  in  cow's 
milk  and  ".Hi  per  cent,  in  human  milk  are  dissociated.  The  specific 
heat  of  milk  containing  3.17  per  cent,  of  fat  is  0.9457.  The  coefficient 
of  expansion  is  greater  than  that  of  water.  ]\Iilk  shows  no  maximum  of 
density  above  1°  C. 

Freshly  drawn  milk  of  carnivorous  animals  is,  as  a  rule,  acid  in 
reaction.  This  is  probably  due  to  CO2  and  acid  phosphates.  Human 
milk  and  that  of  most  of  the  herbivora  are  slightly  alkaline;  cow's  milk 
has  been  described  as  amphoteric.  Fresh  coVs  milk  is  slightly  acid  to 
phenolphthalein ;  but  strongly  alkaline  to  methyl  orange,  indicating  that 
the  acidity  is  due  in  part  to  the  acid  phosphates.  The  pH  values  of 
fresh  cow's  milk  range  between  6.50  and  6.8 ;  fresh  mother's  milk 
varies  between  7.1  and  7.6. 

Under  the  microscope  milk  is  found  to  contain  fat  globules  and  cells, 
as  well  as  bacteria,  debris,  and  other  objects. 

The  gases  dissolved  in  milk  ^  are  oxygen,  nitrogen,  and  carbon  dioxid 
(3  to  4  per  cent,  by  volume).  Oxygen  and  nitrogen  are  carried  into  milk 
mechanically  from  the  air  in  the  process  of  milking.  Other  substances 
found  in  milk,  but  in  small  quantities,  are  lecithin,  cholesterin,  citric 
acid,  lactosin,  orotic  acid,  and  ammonia. 

The  composition  of  cow's  milk  may  be  understood  from  the  schemes 
prepared  by  Lucius  L.  Van  Slyke  and  S.  M.  Babcock,  given  on  page  757. 

Van  Slyke  and  Bosworth  *  suggest  the  following  as  representing  the 
principal  constituents  of  milk  more  closely  than  previous  statements. 
The  amounts  are  based  on  milk  of  average  composition : 

Per  Cent. 

Fat    3.90 

Milk  sugar   4.90 

•    Proteins  combined  with  calcium   3.20 

Dicalcium  phosphate   (CaHP04)    0.175      " 

Calcium  chlorid  (CaCL)  0.119 

Monomagnesium  phosphate  (MgHiPzOs) 0.103 

Sodium  citrate  (XaaCeHsOT)    0.222 

Potassium  citrate  (KsCeHsOT) 0.052 

Dipotassium  phosphate  (KoHPOO   0.230 

Total  solids , 12.901 

^  ^Yhen  not  otherwise  specified  in  this  section  milk  refers  to  cows  milk. 
Vo«r.  Biol  Chem..  XX.  2,  Feb.,   1915. 


756  ANIMAL  FOODS:    MILK 

Milk  is  the  best  source  of  calcium  in  the  dietary,  both  on  account 
of  the  quantity  and  the  usable  form  in  which  it  exists. 

Proteins. — The  three  proteins  constantly  found  in  milk  are  casein, 
laetalbumin,  and  lactoglobulin.  A  trace  of  fibrin,  mucin,  and  other  pro- 
teins sometimes  occurs. 

The  proteins  in  milk  of  a  given  species  are  quite  constant  both  in 
composition  and  amount;  it  is,  therefore,  not  necessary,  as  a  rule,  to 
make  a  special  analysis  for  them.  They  may  be  estimated  by  subtract- 
ing the  fat,  sugar,  and  ash  from  the  total  solids. 

Casern  is  a  highly  specialized  protein  found  in  the  secretion  of  the 
milk  glands  of  all  mammals,  but  nowhere  else  in  nature;  it  is  a  nucleo- 
albumin,  and  as  such  contains  phosphorus.  Casein  is  a  complete  protein 
— that  is,  it  contains  all  of  the  17  or  18  amino-acids  necessary  to  re- 
build human  protein.  It  is  insoluble  in  water,  but  by  viTtue  of  its 
property  as  an  acid  it  forms  soluble  salts  with  alkalies.  There  are  two 
series  of  casein  salts,  basic  and  neutral;  solutions  of  the  latter  have  a 
milky  appearance.  In  milk,  casein  is  found  dissolved  in  the  form  of  a 
neutral  calcium  salt,  which  accounts  in  part  for  the  white  opalescent 
appearance  of  milk.  Casein  really  exists  in  milk  in  the  form  of  casein- 
ogen,  that  is,  casein  in  combination  with  calcium  phosphate.  The 
caseinogen  is  held  in  solution  by  the  calcium  phosphate.  It  is  not  coagu- 
lated by  heat,  but  is  precipitated  by  acids,  for  the  reason  that  acids 
take  the  calcium  from  the  calcium  phosphate,  and  thus  throw  the  casein 
out  of  solution  as  a  curd.  This  flaky  or  lumpy  precipitate  i&  again 
soluble  in  limewater  and  dilute  alkalies.  Casein  is  also  precipitated 
by  rennin. 

Lactalhumin  is  very  similar  to  the  serum  albumin  of  the  blood,  but 
it  appears  to  difPer  from  this  in  some  particulars.  It  coagulates  by 
heating  to  70°  C,  but  not  with  dilute  acids,  and  is  precipitated  by  a 
saturated  solution  of  ammonium  sulphate,  but,  like  all  other  albumins, 
is  not  precipitated  in  a  neutral  solution  of  sodium  chlorid  and  mag- 
nesium sulphate.  Laetalbumin  contains  sulphur  but  no  phosphorus. 
It  is  present  in  amounts  varying  from  0.2  to  0.8  per  cent.,  but  is  much 
more  abundant  in  colostrum. 

Lacioglohulin  occurs  in  milk  merely  in  traces,  while  colostrum  is 
comparatively  rich  in  this  protein.  It  coagulates  at  75°  C,  it  is  pre- 
cipitated in  the  same  way  as  serum-globulin,  and,  like  serum-globulin, 
is  insoluble  in  water,  but  is  soluble  to  some  extent  in  weak  salt  solution. 
Fat. — The  fat  is  suspended  in  the  milk  serum  in  the  form  of  an 
emulsion.  The  droplets  or  globules  vary  in  size.  On  the  average  they 
are  smaller  in  milk  from  Holstein  than  from  Jersey,  Guernsey,  or  short- 
horned  breeds.  Under  the  microscope  some  of  the  fat  globules  seem  to 
have  an  albuminous  membrane,  but  this  interpretation  is  questioned. 
The  fat  droplets  are  lighter  than  the  milk  serum,  therefore  they  rise 


MILK 


75^ 


, 


00         =: 


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758  ANIMAL  FOODS:    MILK 

on  standing  (gravity  cream),  or  else  they  may  readily  be  separated  by 
centrifugal  force  (centrifugal  cream).  Cream,  or  top  milk,  does  not 
consist  of  fat  alone,  but  contains  all  the  constituents  of  the  milk;  it  is 
simply  milk  rich  in  fat.  Upon  shaking  the  fat  globules  gradually  co- 
alesce into  larger  drops  and  lumps  to  form  butter. 

The  first  milk  drawn  from  the  udder  is  commonly  poor  in  fat.  This 
is  known  as  "fore"  milk.  The  middle  portion  contains  about  the  average 
percentage,  and  the  last,  known  as  "strippings,"  is  always  the  richest 
in  fat.     The  strippings  may  contain  as  much  as  9  or  10  per  cent. 

Heat  increases  the  viscosity  of  milk,  and  hence  hinders  the  rising 
of  the  fat  drops;  68°  C.  is  the  critical  temperature;  if  heated  above  this 
point  for  any  length  of  time  the  formation  of  the  cream  line  is  retarded 
or  prevented.  For  this  and  other  reasons  the  richness  of  milk,  there- 
fore, cannot  always  be  judged  by  the  depth  of  the  cream  layer. 

Milk  fat  consists  of  a  mixture  of  different  neutral  fats,  the  principal 
of  which  are  olein,  palmitin,  and  stearin.  These  are  neutral  triglycerids 
of  the  corresponding  fatty  acids.  Besides  these  are  found  the  triglycerids 
of  myristic,  butyric,  and  caprylic  acids.  The  last  two  are  volatile  and 
give  to  butter  its  characteristic  odor  and  flavor.  Crowther  and  Hynd  ^ 
state  that  the  only  acids  present  in  more  than  minimal  proportions  are 
the  unsaturated  acid,  oleic  acid,  and  the  eight  saturated  acids  of  the 
acetic  series  (C^  to  C^g),  namely,  butyric,  caproic,  caprylic,  capric, 
lauric,  myristic,  palmitic  and  stearic  acids.  The  composition  of  the 
fat  is  subject  to  variation,  depending  upon  racial  or  individual  peculiari- 
ties, also  upon  the  character  of  the  food  and  other  conditions. 

Milk  fat  is  rich  in  "fat-soluble  A.^'  This  vitamin  promotes  growth; 
its  absence  induces  xerophthalmia  and  serious  disturbances  of  nutrition. 
Osborne  and  Mendel  ^  have  shown  that  butter  fat  may  have  a  blast  of 
steam  passed  through  it  for  two  hours  and  still  retain  its  peculiar 
growth-promoting  properties.  This  observation  is  in  harmony  with 
those  of  McCollum  and  Davis,  that  heating  butter  fat  to  the  tempera- 
ture of  boiling  water  does  not  affect  its  peculiar  dietary  value.  It  is 
apparent,  therefore,  that  any  conditions  to  which  milk  fats  are  liable 
to  be  subjected  during  the  cooking  of  foods  will  not  greatly  alter  its 
value  as  a  source  of  "fat-soluble  A."  Evaporated  and  dried  milk  also 
retains  the  virtues  of  this  vitamin. 

It  is  now  clear  that  milk  fat  has  no  superior  in  dietetic  or  nutritional 
value. 

The  percentage  of  butter  fat  in  milk  has  long  been  one  of  the  stand- 
ards by  which  milk  is  tested.  The  richness  of  milk  gauged  by  the 
amount  of  fat  it  contains  is  more  of  an  economic  than  a  sanitary  ques- 
tion. Milk  with  a  lower  percentage  of  fat  from  Holstein  cows  is  rela- 
tively just  as  nutritious  a  food  as  richer  milk  from  Jersey  and  Guern- 

^Biochem.  Joiirn.,  1917,  II,  139. 


MILK  r5i) 

sey  cows;  even  .skiinnu'd  milk  (•(Hitainin<,^  little  or  no  I'at  is  a  valuable 
food.  The  problem  is  one  of  honest  labeling-  and  the  marketing  of 
various  grades  at  prices  corresponding  to  their  nutritive  contents.  When 
the  standard  for  butter  fat  in  milk  is  relatively  low,  say  3.25  per  cent., 
it  is  a  temptation  for  dairy  men  to  standardize  or  adjust.  A  high  fat 
standard  encourages  the  breeding  of  better  cows;  requires  caution  in 
their  feeding  and  care,  and  puts  a  premium  upon  good  dairy  methods. 

In  normal  milk  the  larger  proportion  of  fat  droplets  agglutinate 
into  tiny  clusters  or  masses.  At  a  temperature  of  65°  C.  or  above  these 
clusters  are  broken  up  and  the  globules  are  more  homogeneously  dis- 
tributed throughout  the  liquid.  When  milk  is  sprayed  or  atomized  at  a 
pressure  of  about  3,000  pounds  at  a  temperature  of  about  75°  C.  the 
individual  fat  globules  are  broken  up  into  fine  particles,  which  remain 
as  a  uniform  and  permanent  emulsion  known  as  "homogenized  milk." 
This  process  applied  to  cream  increases  its  volume  and  viscosity,  so  that 
cream  containing  20  per  cent,  butter  fat  appears  to  have  the  body  and 
richness  of  a  30  per  cent,  cream. 

Eesearches  of  Heubncr.  Keller,  and  Czerny  show  that  the  fats  and 
not  the  proteins  are  the  cause  of  much  of  the  digestive  disturbances  in 
infants.  When  the  fat  is  excessive  in  amount  the  infant  at  first  seems 
to  thrive,  but  sooner  or  later  loses  weiglit  and  appetite,  and  shows  other 
symptoms,  associated  with  stools  composed  largely  of  fat  soaps  and  of 
a  pale  gray,  hard,  and  dry  constituency.  The  alkaline  bases  are  so 
largely  dra^vn  upon  from  the  body  to  saponify  the  excessive  amount  of 
fat  in  the  intestines,  that  a  condition  resembling  acidosis  may  appear; 
furthermore,  fermentative  changes  take  place  in  the  intestines  and  the 
"catastrophe''  ensues. 

Fat  is  the  most  variable  constituent  in  milk.  The  amount  varies 
with  different  animals,  and  even  in  the  same  animal  from  time  to  time. 

Milk  Sugar,  or  Lactose. — Milk  sugar,  or  lactose  (CjoHooOn),  is 
peculiar  to  milk;'  it  is  found  nowhere  else  in  nature.  Commercially, 
milk  sugar  is  obtained  from  whey  as  hard  rhombic  crystals,  which  have 
a  slightly  sweet  taste  and  are  soluble  in  six  parts  of  cold  water.  Lactose 
is  readily  acted  upon  by  microorganisms  and  reduced  to  glucose  and 
galactose;  the  glucose  is  further  changed  to  lactic  acid.  This  is  the 
common  cause  of  sour  milk  (see  The  Fermentation  of  Milk,  page  769). 

Lactose,  like  glucose,  reduces  Fehling's  solution  when  heated ;.  it  is 
dextrorotary.  When  heated  above  the  boiling  point  of  water  it  changes 
to  a  brownish  color  as  a  result  of  the  formation  of  lactocaramel. 

The  amount  of  lactose  in  milk  of  any  given  species  is  remarkably 
constant. 

Vitamins. — ^lilk  is  rich  iji  "fat-soluble  A,"  "water-soluble  B.*'  and 
fresh  milk  has  a  moderate  antiscorbutic  property  ("water-soluble  C"). 
The  first  two  resist  heating,  drying,  and  age,  but  the  last  named  deteri- 


760  ANIMAL  FOODS:    MILK 

orates  in  time,  and  is  injured  by  heat  and  drying.  It  is  therefore  es- 
sential to  give  orange  juice  or  other  antiscorbutic  to  infants  fed  on 
cow's  milk,  especially  if  stale,  heated  or  dried.     See  also  page  685. 

Ferments  or  "Life"  in  Milk. — Milk  contains  a  large  number  of  very 
active  ferments  or  enzymes.  These  substances  are  the  nearest  approach 
to  "life"  that  we  know  of  in  milk.  Milk  also  possesses  certain  other 
properties  common  to  blood  and  living  tissues,  but,  while  milk  may 
properly  be  regarded  as  a  vital  fluid,  it  possesses  none  of  the  funda- 
mental properties  of  life.  In  fact,  milk  begins  to  decay  the  moment 
it  is  dra'rni;  ofttimes  decomposition  begins  while  the  milk  is  still  within 
the  udder.  It  would,  therefore,  be  more  proper  to  regard  milk  as  a 
dead  fluid,  in  the  same  sense  that  shed  blood  is  dead. 

The  ferments  are  believed  to  be  important  to  the  infant,  and  this 
importance  has  been  emphasized  especially  since  the  intrqduction  of 
pasteurization,  for  the  reason  that  a  high  degree  of  heat  destroys  them. 
Some  of  the  ferments  in  milk  are -normal  constituents  of  that  secretion, 
while  others  are  produced  by  bacteria.  Many  tests  have  been  devised 
to  determine  the  kinds  and  activity  of  the  ferments  in  milk.  The  tests 
most  frequently  and  successfully  used  are  those  for  catalases  and  re- 
ductases. The  absence  of  certain  ferments  in  milk  indicates  that  it  has 
been  heated.  The  presence  of  certain  ferments  gives  an  indication  of 
the  age  of  the  milk,  and  the  number  of  bacteria  it  contains,  and  also 
helps  to  distinguish  between  fresh  normal  milk  and  pathologically 
changed  milk.  See  Tests  for  Enzymes,  page  808. 
The  enzymes  in  milk  are  the  following: 

Galadase. — Galactase  is  a  proteolytic  ferment,  similar  to  trypsin. 
It  was  found  by  Babcock  and  Eussell  to  be  abundant  in  separator  slime. 
Ordinarily  galactase  by  itself  acts  too  slowly  to  cause  any  material 
change  in  the  proteins  in  the  short  intervals  which  elapse  between  the 
withdrawal  of  the  milk  from  the  animal  and  its  consumption  as  food. 
Snyder  claims  that  this  enzyme  probably  assists  digestion,  in  that  when 
milk  is  used  in  a  mixed  diet  the  proteins  have  been  found  to  be  from 
4  to  5  per  cent,  more  digestible  than  when  milk  is  omitted  from  the 
diet. 

LadoTcinase. — Hougardy  has  shown  that  milk  contains  a  ferment 
or  a  kinase  similar  to  enterokinase.  Lactokinase  has  been  found  to  ac- 
celerate the  digestion  of  proteins  by  pancreatic  juice.  This  property  is 
destroyed  by  heating  the  milk  at  73°  to  75°  C. 

Lipase. — This  fat-splitting  ferment  was  found  in  milk  by  Marfan 
and  Gillet.  Human  milk  exhibits  -this  property  to  a  higher  degree  than 
cow's  milk.  The  former  has  a  lipolytic  activity  of  from  20  to  30  on 
Harriot's  scale,  while  cow's  milk  shows  an  activity  of  only  6  to  8. 
Lipase  withstands  cold,  but  is  destroyed  by  heating  to  65°  C;  it  is  non- 


MILK  761 

(lialyzable  and  is  held  hack  l)y  a  porcelain  filter.  It  probably  hydrolyzes 
the  higher  fats  of  milk,  at  least  to  some  extent,  and  may  possibly 
account  for  a  small  part  of  the  acidity  of  some  milk. 

Cata](h'<e. — ^lilk  contains  no  true  oxidases  or  oxidizing  ferments 
proper  (Kastle).  It  decomposes  hydrogen  peroxid  and  has  the  power 
of  effecting  the  oxidation  of  a  considerable  number  of  easily  oxidizable 
substances  in  the  presence  of  hydrogen  peroxid  or  ozonized  oil  of  tur- 
pentine. In  other  words,  milk  contains  catalase  and  peroxidase.  Cata- 
lase  is  widely  distributed  among  animals  and  plants;  in  milk  it  is  prolj- 
ably  of  bacterial  origin.  Jolles  has  pointed  out  that  human  milk  decom- 
poses five  or  six  times  as  much  hydrogen  peroxid  as  cow's  milk.  Consid- 
erable importance  has  been  at f ached  to  this  difference,  which  has  also 
been  used  to  distinguish  human  milk  from  cow's  milk.  Little  is  known 
of  the  function  of  catalase.  Hydrogen  peroxid  is  probably  formed  in 
both  animal  and  vegetable  tissues  during  vital  activities.  The  catalase 
would  destroy  it  and  thus  prevent  its  accumulation  in  the  cell,  which 
otherwise  would  destroy  its  life. 

Peroxidase. — Milk  contains  substances  capable  of  inducing  the  oxida- 
tion of  guaiacum  and  other  readily  oxidizable  substances  by  means  of 
hydrogen  peroxid  or  ozonized  oil  of  turpentine.  These  substances  are 
known  as  peroxidases.  The  peroxidases  are  destroyed  when  milk  is  heated 
to  80°  C.  The  color  reactions  for  these  ferments  are  a  convenient  test 
to  determine  whether  milk  has  been  heated  beyond  a  certain  temperature 
or  not.  The  interpretation  of  this  reaction  must,  however,  be  guarded,  as 
Gillet  and  Kastle  found  that  even  normal  fresh  milks  vary  in  the  amount 
of  peroxidases  which  they  contain. 

Reductase. — Baw  milk  possesses  reducing  properties ;  for  example,  it 
reduces  Schardinger's  reagent,  which  consists  of  a  solution  of  methylene 
blue  containing  small  amounts  of  formaldehyd.  The  reductases  in  milk 
are  probably  of  bacterial  origin.  On  account  of  the  bacterial  origin  of 
both  the  catalases  and  reductases  in  milk,  the  detection  of  these  enzymes 
has  a  sanitary  significance. 

Diastase  (Amylase). — Bechamp  in  1882  isolated  from  milk  a  fer- 
ment which  liquefies  starch  and  converts  it  into  sugar  as  readily  as 
diastase.  These  observations  have  not  been  confirmed  by  other  inves- 
tigators (Mora,  Tan  De  Telde,  and  Landtsheer,  or  Kastle). 

Thermal  Death  Point  of  Milk  Enzymes. — The  influence  of  tem- 
perature on  the  activity  of  milk  enzymes  is  very  much  like  enzymes  from 
other  sources.  All  of  this  great  group  of  substances  stand  in  such  in- 
timate and  close  relation  to  the  vital  activities  of  the  cell  that  all  those 
conditions  and  influences  which  tend  to  destroy  the  one  tend  also  to 
destroy  the  other.  All  of  the  bacteria  in  milk  cannot  he  destroyed  with- 
out rendering  the  ferments  in  milk  inactive :  but  the  non-spore-bearing 
bacteria  can  be  killed  without  appreciable  harm  to  the  ferments,  for  in 


763 


ANIMAL  FOODS:    MILK 


ENZYMES  IN   MILK  AND  THEIR  THERMAL  DEATH  POINTS  * 


Gaiactase — Proteolytic  ferment 

70°   for   10   minutes  retards   its   action. 
76°  for  10  minutes  destroys  its  diges- 
tive power.      (Babcock   and  Russell.) 
Not  weakened   at   60°    for   one  hour, 
(von  Freudenreich.)      Withstands  65° 
for  half  an  hour.      (Hippius.) 

Lactokinase — Accelerates  pancreatic   di- 
gestion  

Destroyed  at  73°  to  75°  C.  for  half  an 
hour.  Enfeebled  at  75°  for  20  min- 
utes.    ( Hongardy. ) 

Lipase — Fat-splitting  ferment 

Destroyed  at  70°  C.  (Harriet.)  De- 
stroyed at  65°  to  70°  C.  (Kastle  and 
Loewenhart. )  Withstands  60°  for  one 
hour.    (Hippius.) 

Catalase — Decomposes  H:;02,  etc 

1 

Peroxidase — Oxidizes  giiaiacum,  etc.  .  .  . 

Destroyed  at  79°  C.  (Marfan.)  De- 
stroyed at  76°  C.    (Hippius.) 

Reductase — A  reducing  ferment 

Existence  is  doubtful  in  Milk. 

Diastase — Converts  starch  into  sugar.  .  . 

Probably  does  not  exist  in  Milk.  Dia- 
stase in  saliva  destroved  at  65°  to  70° 
C. 

Compiled  from  Kastle. 


general  the  ferments  have  a  higher  thermal  death  point  than  such  bac- 
teria. The  activity  of  ferments  begins  to  be  influenced  at  60°  C,  and  is 
seriously  affected  at  70°  C. ;  at  80°  C.  they  are  destroyed.  The  non- 
spore-bearing  bacteria  are  destroyed  at  60°  C.  It  is,  therefore,  possible 
to  destroy  all  the  serious  infections  in  milk,  so  far  as  man  is  concerned, 
without  influencing  its  "life,"  so  far  as  the  ferments  are  concerned.  In 
fact,  it  has  been  shown  that  milk  heated  to  60°  C.  increases  the  activity 
of  some  of  the  ferments,  notably  the  peroxidases. 

"Leukocytes"  in  Milk. — A  large  number  of  cells  are  normally  present 
in  milk.  These  are  not  to  be  regarded  as  the  result  of  inflammation, 
unless  they  have  the  characteristics  of  "pus"  cells.  Those  found  in 
normal  milk  are  leukocytes  and  degenerated  epithelial  cells.  The 
number  of  cells  in  milk  is  greatly  increased  in  the  presence  of  garget; 
toward  the  end  of  lactation ;  on  approaching  calving  time ;  during  periods 
of  excitement,  and  various  other  factors.  A  leukocytic  content  of  500,000 
or  over  to  the  cubic  centimeter,  especially  in  a  mixed  milk,  is  regarded 
by  the  Boston  Board  of  Health  as  suggestive  of  some  inflammatory  con- 
dition of  the  udder,  more  particularly  if  associated  with  streptococci. 
Such  milk  is  excluded  until  after  satisfactory  veterinary  inspection  of  the 
herd. 

Various  methods  have  been  proposed  to  count  the  number  of  cells 
in  milk.     See  Microscopic  Exam.ination,  page  797. 


MT1;K  7(\:^ 

The  Excretion  of  Drugs  in  Milk. — 'I'lic  I'dlldwiiii:  ilru.irs  1;il<<'ii  hv  ilic 
iiioiilli  li;i\('  ixHMi  foiiiKl  ill  tlio  milk  (if  niirsiiii,^  women:  ;is]»iriii,  iodin. 
moreiiry  (caloinel).  arsoiious  acid,  potassium  hromid,  and  probably  also 
lu'xametiiylcnainin.  salicylic  acid,  and  salicylates,  ether,  aiitijjyrin,  bro- 
niids,  and  many  others:  the  list  is  very  long.  It  is  probable  that  opium, 
all  volatile  oils,  ])uriiative  salts,  and  rhubarb  are  excreted  to  a  certain 
extent  in  the  milk.  It  is  well  knowti  bow  readily  the  flavor  of  cow's 
milk  is  aU'ecled  hv  tiinii]is.  u-arlic.  wihl  onidiis,  moldy  hay  and  f^rain, 
or  damaged  ensilag'e.  Fermented  distillery  waste  gives  a  bad  flavor 
and  may  also  cause  the  .secretion  of  small  quantities  of  alcohol  in  the 
milk.  The  importance  of  these  facts  is  self-evident.  Cows  in  pa.stures 
.sometimes  feed  on  poisonous  weeds,  and  these  poi.sons  may  pass  into  the 
milk.  In  the  production  of  certified  milk,  cow^s  are  never  allowed  to 
graze,  but  are  given  carefully  selected  feed.  Certain  .substances,  as  en- 
silage, when  fed  to  cows,  cause  a  laxative  property  to  appear  in  the  milk, 
and  thus  it  is  possible  to  afPect  the  baby  through  the  feed  of  the  cow. 

The  Differences  between  Cow's  Milk  and  Woman's  Milk. — The  table 
(])age  T()4)  from  Tiotch  summarizes  the  principal  points  of  differences 
l)etween  cow's  milk  and  human  milk. 

The  difPerenccs  between  these  two  milks  are  greater  than  the  table 
iiulicates.  While  cow's  milk  may  be  modified  to  approximate  woman's 
milk  in  composition,  it  can  never  be  just  the  same  or  just  as  good  for 
infants. 

Cow's  milk  is  more  opaque  than  woman's  milk,  although  the  latter 
may  contain  a  greater  percentage  of  fat.  This  is  due  to  the  opacity  of 
the  calcium-casein,  which  is  present  in. greater  proportion  in  cow's  milk. 
Cow's  milk  is  faintly  acid  or  amphoteric  when  freshly  drawn,  but  ordi- 
narily is  distinctly  acid  in  reaction  when  consumed.  "Woman's  milk  is 
amphoteric  or  alkaline. 

There  is  three  times  as  much  protein  in  cow's  milk  as  in  woman's 
milk.  The  reason  for  this  is  obvious,  when  we  recall  that  the  ratio  of 
the  growth  of  the  calf  to  that  of  the  infant  is  about  as  two  to  one. 
Furthermore,  the  protein  in  cow's  milk  consists  chiefly  of  casein  (3.02 
per  cent.)  and  little  lactalbumin  (0.53  per  cent.),  while  w^oman's  milk 
contains  0..j9  per  cent,  of  casein  and  1.23  per  cent,  lactalbumin.  The 
sugar  in  the  two  milks  varies  greatly  in  amount,  but  not  in  kind.  Cow's 
milk  contains  almost  four  times  the  amount  of  inorganic  salts  com- 
pared to  woman's  milk.  Of  more  importance,  the  salts  in  cow's  milk 
consist  mainly  of  the  calcium  and  magnesium,  while  those  in  woman's 
milk  consist  mainly  of  potassium  and  sodium  bases.  These  differences 
have  an  important  bearing  upon  infant  metabolism.  '  There  is  no  great 
difference  in  the  a-vcrage  amount  of  fat  in  the  two  milks:  however,  both 
in  woman's  milk  and  in  cow's  milk  the  fat  is  the  most  variable  con- 
stituent. 


'i'64 


ANIMAL  FOODS:    MILK 


THE  DIFFERENCES  BETWEEN  WOMAN'S  MILK  AND  COW'S   MILK 


Woman's  Milk  Directly  from  the  Breast 
Reaction,  amphoteric  (more  alkaline  than  acid) 

pH  Values,  7.1  to  7.6 

Water,  87  to  88  per  cent 

Mineral  matter,  0.20  per  cent 

Total  solids,  13  to  12  per  cent 

Fats,  4.00  per  cent,  (relatively  poor  in  volatile 
glycerids )....'. 

Milk  sugar,  7.00  per  cent 

Proteids,  1.50  per  cent 

Caseinogen,  %  to  14  of  the  total  proteids 

Whey-products,  %  to  ^/2  of  the  total  proteids .  .  . 

Coagulable  proteids,  small  proportionately 

Coagulation  of  proteids  by  acids  and  salts,  with 
greater  difficulty.   Curds  small  and  fiocculent. 

Coagulation  of  proteids  by  rennet,  does  not  co- 
agulate readily 

Action  of  gastric  juice,  proteids  precipitated  but 
easily  dissolved  in  excess  of  the  gastric  juice. 


Cow's    Milk,    Freshly    Milked 


Amphoteric  (more  acid  than  al- 
kaline) . 

pH  Values,  6.-5  to  6.8. 

86  to  87  per  cent. 

0.70  per  cent. 

14  to  13  per  cent. 

4.00  per  cent,  (relatively  rich  in 
volatile  glycerids). 

4.75  per  cent. 

3.50  per  cent. 

2.66  per  cent. 

0.84  per  cent. 

Large  proportionately. 

With  less  difficulty.  Curds  large 
and  tenacious.   ' 

Coagulates  readily. 
Proteids    precipitated    but    dis- 
solved less  readily. 


The  curd  from  cow's  milk  is  usually  tougher  and  in  larger  masses 
than  that  in  woman's  milk.  There  are  also  differences  in  the  antibodies, 
ferments,  etc. 

Milk  Standards.*' — The  word  "standard"  used  in  this  connection  is 
not  intended  to  imply  excellence,  but  simply  to  express  the  lowest  pos- 
sible limit  that  the  law  permits  for  a  pure  or  normal  milk.  There  are 
at  least  four  standards  by  which  milk  should  be  judged:  (1)  physical 
standards;  specific  gravity,  temperature,  taste,  odor,  etc.;  (2)  chemical 
standards;  especially  the  percentage  of  fat  and  total  solids;  (3)  bacterio- 
logical standards;  the  number  of  bacteria  per  cubic  centimeter  and 
absence  of  pathogens;  (4)  sanitary  standards  deteriuined  by  inspection. 
Standards  have  also  been  established  for  pasteurization,  prodviction,  trans- 
portation and  handling.  All  are  necessary  for  the  satisfactory  control 
of  a  milk  supply. 

Cow's  milk  should  not  contain  less  than  8.5  per  cent,  of  solids  not 
fat,  and  not  less  than  3.25  per  cent,  of  milk  fat.'^ 

It  has  been  found  an  advantage  to  keep  the  butter-fat  standard  rela- 
tively high  and  the  total  solids  at  a  minimum  of  12  per  cent.  This 
allows  8.5  per  cent,  for  solids  not  fat,  such  as  the  proteins,  milk,  sugar, 
and  inorganic  salts.  A  3.25  per  cent,  butter-fat  and  a  12  per  cent,  total 
solids  is  the  minimum  that  should  be  allowed. 

'The  subject  is  fully  discussed  in  tlie  Reports  of  the  Commission  on  Milk 
Standards  of  the  N.  Y.  Milk  Committee,  U.  S.  Public  Health  Reports,  May  10, 
1912,  and  Feb.  16,  1917. 

'  Recommendation  of  the  Official  Agricultural  Chemists,  and  the  Commission 
on  Milk  Standards,  and  adopted  by  the  U.  S.  Department  of  Agriculture  and  a 
number  of  states  and  cities. 


MTLK 


705 


If  the  law  roooo^nizes  a  low  standard  I'nv  total  solids,  it  pennits 
manipulation  of  the  milk,  sncii,  for  c'\ani|ii(',  as  adding  water.  It  also 
encourages  the  ])rodiu'tio]i  of  milk  from  inferior  cows.  High  standards 
encourage  good  dairy  methods,  require  good  feed,  and  place  a  ])remiuni 
\\]H)U  (he  hcttci'  hrcfdiiig  of  milch  cows. 

The  deti'rmination  oi'  fats  and  total  solids  is  used  to  detect  skim- 
ming or  watering:  however,  it  is  possihle  to  skim  milk  or  water  it,  within 
limits,  without  the  possibility  of  detecting  it  through  the  fats  and  total 
solids. 

If  dej)enden(e  is  placed  upon  tlu^  total  solids,  mistakes  may  also 
occur.     The  total  solids  re])resent  the  proteins,  fats,  sugar,  and  inorganic 


Fig.  77. — Unsanitary  Surroundings  of  a  Cow  Barn. 


salts.  They  may  readily  be  tampered  with.  Thus  sugar  may  be  added 
to  replace  the  cream  that  is  taken  off. 

Bacteriological  standards  usually  adopted  are:  Certified  milk,  not 
more  than  10,000  bacteria  per  cubic  centimeter;  grade  A  milk  (raw) 
should  not  have  more  than  10,000  bacteria  per  cubic  centimeter;  grade 
A  (pasteurized)  should  not  have  more  than  200,000  before  pasteuriza- 
tion and  less  than  10,000  after  pasteurization;  market  milk  (grade  B) 
should  have  not  more  than  1,000,000  per  cubic  centimeter  before  pasteuri- 
zation, and  less  than  50,000  per  cubic  centimeter  after  pasteurization, 
and  should  not  contain  B.  coli  in  1  cubic  centimeter. 

Grades  of  Milk. — Milk  varies  greatly  in  sanitary  quality  and  in  nu- 
tritive value.  These  differences  are  not  obvious  to  our  unaided  senses. 
Milk  should  therefore  be  graded  just  as  other  commodities,  such  as 
wheat,  beef,  fruit,  coal,  etc.,  are  graded. 


766  ANIMAL  FOODS:    MILK 

The  grades  of  milk  recommended  Ijy  the  Commission  on  Milk  Stand- 
ards of  the  New  York  Milk  Committee  are: 

Grade  A 

Raw  Milk. — Milk  of  this  class  shall  come  from  cows  free  from  dis- 
ease as  determined  by  tuberculin  tests  and  physical  examinations  by  a 
qualified  veterinarian,  and  shall  be  produced  and  handled  by  employees 
free  from  disease  as  determined  by  medical  inspection  of  a  qualified  phy- 
sician, under  sanitary  conditions,  such  that  the  bacterial  count  shall 
not  exceed  10,000  per  cubic  centimeter  at  the  time  of  delivery  to  the 
consumer.  It  is  recommended  that  dairies  from  which  this  supply  is 
obtained  shall  score  at  least  80  on  the  United  States  Bureau  of  Animal 
Industry  score  card. 

Pasteurized  Milk. — Milk  of  this  class  shall  come  from  cows  free 
from  disease  as  determined  by  physical  examinations  by  a  qualified  vet- 
erinarian, and  shall  be  produced  and  handled  under  sanitary  conditions, 
such  that  the  bacteria  count  at  no  time  exceeds  200,000  per  cubic  centi- 
meter. All  milk  of  this  class  shall  be  pasteurized  under  official  super- 
vision, and  the  bacteria  count  shall  not  exceed  10,000  per  cubic  centi- 
meter at  the  time  of  delivery  to  the  consumer.  It  is  recommended  that 
dairies  from  which  this  supply  is  obtained  shall  score  at  least  65  on  the 
United  States  Bureau  of  Animal  Industry  score  card. 

Grade  B 

Milk  of  this  class  shall  come  from  cows  free  from  disease  as  deter- 
mined by  physical  examinations,  of  which  one  each  year  shall  be  by  a 
qualified  veterinarian,  and  shall  be  produced  and  handled  under  sani- 
tary conditions,  such  that  the  bacteria  count  at  no  time  exceeds  1,000,- 
000  per  cubic  centimeter.  All  milk  of  this  class  shall  be  pasteurized 
under  official  supervision,  and  the  bacterial  count  shall  not  exceed  50,000 
per  cubic  centimeter  when  delivered  to  the  consumer. 

It  is  recommended  that  dairies  producing  grade  B  milk  should  he 
scored,  and  that  the  health  departments  or  the  controlling  departments, 
whatever  they  may  be,  strive  to  bring  these  sources  up  as  rapidly  as 
possible. 

Grade  C 

Milk  of  this  class  shall  come  from  cows  free  from  disease,  as  deter- 
mined by  physical  examinations,  and  shall  include  all  milk  that  is  pro- 
duced under  conditions  such  that  the  bacteria  count  is  in  excess  of  1,000,- 
000  per  cubic  centimeter. 

All  milk  of  this  class  shall  be  pasteurized,  or  heated  to  a  higher  tem- 
perature, and  shall  contain  less  than  50,000  bacteria  per  cubic  centimeter 
when  delivered  to  the  consumer. 


MTLK  re: 

Wliotiovcr  ji'i^'  Ini'u'c  city  oi-  coiimuiiiily  lim]s  ii  iieccsf^an',  on  account 
of  the  leii<j:tli  (if  iiaiil  or  ddicr  |H'culiar  coiidilioiis,  to  allow  tho  sale  of 
grade  C  milk,  its  sale  shall  be  surrounded  by  safeguards  such  as  to 
insure  the  restrietioii  of  its  use  to  cooking  and  manufacturing  purposes. 

These  grades  are  gradually  being  adopted.  Other  grades  are  used, 
such  as  cci'tiflcd  milk,  inspected  milk,  market  milk,  etc. 

There  is  a  growing  tendency  to  classify  all  milk  into  raw  and  pas- 
teurized. This  is  the  most  significant  classification  from  a  sanitary 
standpoint. 

The  grading  of  milk  in  accordance  with  a  simple  classification,  such 
as  rei-ommended  by  the  Commission  on  Standards  of  the  Xew  York  ]\Iilk 
(Vmimitlee  lias  great  economic  and  sanitary  importance.  Such  a  sys- 
tem furnishes  the  purchaser  with  a  ready  method  of  knowing  just  what 
he  is  buying,  and  furthermore  helps  the  farmer  get  a  better  price  for  a 
superior  product. 

Certified  Milk. — The  term  "certified  milk,"  then,  is  milk  of  the  high- 
est quality,  of  uniform  composition,  obtained  by  cleanly  methods  from 
healthy  cows  under  the  special  supervision  of  a  medical  milk  commis- 
sion. It  is  fresh,  clean  and  unaltered.  The  term  "certified  milk"  w'as 
coined  by  Dr.  Henry  L.  Coit  of  Xewark,  X.  J.,  wdio  in  1892,  needing 
good  milk  for  his  own  baby,  formulated  a  plan  for  the  production  of 
clean,  fresh,  pure  milk  under  the  auspices  of  a  medical  milk  commission. 

The  use  of  the  term  "^certified  milk"  should  be  limited  to  milk  pro- 
duced in  accordance  with  the  requirements  of  the  American  Association 
of  ^ledical  Milk  Commissions.^  .  The  first  requisite  in  the  production  of 
certified  milk  is  to  enlist  the  cooperation  of  a  trustworthy  dairyman 
who  is  willing  to  enter  into  a  contract  with  the  medical  milk  commis- 
sion. In  accordance  with  the  terms  of  this  contract,  the  dairyman  binds 
himself  to  comply  with  the  specifications  set  forth  and  in  return  his 
milk  is  certified. 

The  dairies  are  subjected  to  periodic  inspections,  and  the  milk  to 
frequent  analyses.  The  cows  producing  certified  milk  must  be  free  from 
tuberculosis,  as  shown  by  the  tuberculin  test  and  physical  examination 
by  a  qualified  veterinarian,  and  from  all  other  communicable  disease,  and 
from  all  diseases  and  conditions  wdiatsoever  likely  to  deteriorate  the  milk. 
They  must  be  housed  in  clean,  properly  ventilated  stables  of  sanitary 
construction,  and  must  be  kept  clean  and  properly  fed  and  cared  for. 
All  persons  who  come  in  contact  with  the  milk  must  exercise  scrupulous 
cleanliness,  and  must  not  harbor  the  germs  of  typhoid  fever,  tuberculosis, 
diphtheria,  or  other  infections  liable  to  be  conveyed  to  the  milk.  Milk 
must  be  drawn  under  all  precautions  necessary  to  avoid  contamination, 
and  must  be  immediately  cooled  to  45°  F.,  placed  in  sterilized  bottles, 

*  See  annual  reports  of  this  Association,  also  Public  Health  Reports.  No.  85, 
Mav  1.  1912. 


7G8  ANIMAL  FOODS:    MILK 

and  kept  at  a  temperature  between  35°  and  45°  F.  until  delivered  to 
the  consumer.  Pure  water,  as  determined  by  chemical  and  bacteriological 
examination,  is  to  be  provided  for  use  throughout  the  dairy  farm  and 
dairy.  Certified  milk  should  not  contain  more  than  10,000  bacteria  per 
cubic  centimeter,  and  should  not  be  more  than  thirty-six  hours  old 
when  delivered. 

Certified  milk  is  raw  milk  and,  therefore,  may  convey  the  infec- 
tious agents  of  disease;  in  fact,  this  has  happened.  Such  occasional 
danger  may  be  guarded  against  by  pasteurization. 

"Standardized"  or  Adjusted  Milk. — The  process  of  adjusting  or 
standardizing  milk  consists  in  removing  some  of  the  cream  or  adding 
skim  milk,  with  the  object  of  purveying  a  product  that  shall  contain 
just  about  the  legal  limit  of  butter  fat  and  total  solids.  The  method 
usually  consists  in  separating  the  cream  and  recombining  all  or  part 
with  the  addition  of  skim  milk.  The  ratio  of  the  fat  to  the  solids  not 
fat  is  changed  so  slightly  by  this  adjustment  that  it  is  difficult  to  detect. 

Such  manipulation  of  milk  is  generally  practiced  by  almost  all  large 
dealers.  Sanitarians  have  always  looked  askance  upon  the  practice.  The 
process  should  be  controlled  and  such  milk  distinctly  labeled  as  to  its 
modifications. 

Reconstructed  Milk. — Eeconstructed  milk  is  also  called  remade 
milk;  sometimes  "synthetic"  milk.  A  better  name  is  recombined  milk, 
or  reconstituted  milk,  for  it  consists  of  combining  powdered  whole 
milk  or  skim  milk  powder,  condensed  or  evaporated  whole  milk  or 
skim  milk,  with  butter  or  milk  fat  and  water.  Machines  may  now 
be  had  for  mixing,  recombining  or  emulsifying  these  materials  for  the 
production  of  manufactured  milk  or  cream.  If  such  products  are 
made  entirely  from  milk  constituents,  they  may  be  labeled  "recom- 
bined," or  "reconstructed"  milk,  but  if  any  other  fat  is  substituted  in 
whole  or  in  part  for  milk  fat,  then  the  product  should  be  labeled  "arti- 
ficial milk"  or  "milk  substitute." 

There  is  a  legitimate  field  for  remade  milk.  Thus,  during  the 
World  War  it  became  necessary  to  find  a  milk  supply  for  the  new  city 
of  Mtro,  West  Virginia,  with  25,000  and  more  inhabitants.  The  city 
was  established  in  a  section  unsuited  for  dairying  and  no  available 
supply  of  fresh  milk  could  be  found.  The  Government  solved  the 
problem  by  reconstructing  milk  by  homogenizing  butter  fat  and  mix- 
ing this  into  skim  milk  powder  and  water. 

The  importance  of  sanitary  control  and  proper  labeling  of  these 
products  is  obvious. 

The  Decomposition  of  Milk.— Milk  spoils  in  various  ways  as  the 
result  of  bacterial  growth;  the  kind  of  decomposition  depending  upon 
the  kind  of  bacteria  which  predominate.  Milk,  as  a  rule,  ferments,  but 
sometimes  it  putrefies.    In  the  former  case  the  main  change  takes  place 


MILK  769 

in  the  carbohydrates;  in  tlie  latter  the  proteins  are  broken  down.  'I'lie 
fermentation,  known  as  tlie  souring  of  milk,  is  accompanied  by  an  acid 
reaction  and  a  precipitation  of  the  casein.  Putrid  milk  turns  alkaline 
and  bitter,  owing  to  the  formation  of  peptones.  Sour  milk  is  regarded 
as  the  "normal''  form  of  decomposition,  because  it  is  the  usual  change 
and  is  not  harmful.  Putrid  milk  is  believed  at  times  to  contain  toxic 
substances ;  it  is  at  least  suspicious. 

Sour  Milk — Lactic  Acid  Fernieniaiioii.—'Siilk  curdles  or  sours 
when  the  soluble  caseinogen  is  thrown  out  of  solution  and  precipitated 
as  casein.  The  caseinogen  exists  in  milk  as  a  complex  molecule  con- 
taining calcium  phosphate  loosely  bound  to  it;  it  also  contains  calcium 
as  part  of  the  molecular  complex.    The  formula  may  be  expressed  thus : 

Ca3(P0j2  (C'a.  Caseinogen) 

The  casein  is  held  in  solution  (colloidal  suspension)  by  the  calcium 
phosphate  and  other  soluble  salts  of  calcium.  Any  chemical  reaction 
that  removes  the  calcium  phosphate  from  this  combination  causes  a 
precipitation  of  the  caseinogen  as  casein.  The  casein  may  be  precipi- 
tated by  various  substances,  such  as  rennin  or  acids.  In  the  normal 
curdling  or  souring  of  milk  the  casein  is  precipitated  by  lactic  acid 
produced  through  the  action  of  bacteria  upon  lactose.  The  lactic  acid 
results  from  hydrolysis  of  the  lactose  as  follows : 

C,  A,0,,+H,0  =CeH,,0e+CeH,30e 

Iactose=:gaIactose +glucose 

CeH,,0,=2C3He03 

glucose^lactic  acid 

The  bacteria  usually  concerned  in  the  souring  of  milk  are:  B.  acidi 
lactici  of  Hueppe,  B.  lactic  acidi  of  Leichmann.  Streptococcus  lactis  of 
Kruse,  B.  hulgaricus  of  ^letchnikoff,  B.  coJi,  and  a  great  number  of  other 
microorganisms  capable  of  fermenting  sugar  with  the  production  of  acid. 
Sour  milk,  obtained  from  clean  milk,  is  a  beneficial  food. 

Sour  Milk  and  Intestinal  Flora. —  Sour  milk  contains  myriads  of 
lactic  acid  bacteria.  Metchnikoff  called  attention  to  the  importance 
of  a  normal  lactic  acid  flora  in  the  large  intestines,  which  inhibits  pu- 
trefactive processes  and  thereby  stands  guard  against  "auto-intoxication.^' 
He  recommended  the  use  of  certain  bacteria  in  sour  milk,  especially  B. 
hulgaricus.  It  is  a  fallacy,  however,  to  suppose  that  the  flora  of  the 
intestines  may  be  influenced  through  ingestion  of  these  bacteria  by  the 
mouth,  even  when  taken  in  enormous  numbers,  as  in  sour  milk.  A  sour 
milk  diet  is  uncertain  in  its  effects  and  often  disappointing  in  its  re- 
sults. 

Contrary  to  widespread  belief,  the  bacterial  flora  of  the  alimentary 
tract  is  not  a  replica  of  that  of  the  food  we  eat.     Of  the  many  varieties 


770  ANIMAL  FOODS:    MILK 

of  microorganisms  gaining  entrance  into  the  alimentary  tract,  feu- 
succeed  in  establishing  themselves.  The  diet  of  early  infancy  is  rich 
in  carbohydrates  in  the  form  of  lactose.  The  Bacillus  hifidus  then  estab- 
lishes itself  in  the  intestines.  As  the  diet  changes  with  age,  the  colon 
group  of  bacteria  begins  to  assert  itself,  not  because  these  organisms 
dominate  in  the  diet,  but  because  they,  above  all  others,  thrive  as  well 
in  a  medium  from  which  carbohydrates  are  absent,  as  in  one  contain- 
ing them.  B.  coli  and  related  bacilli  constitute  nearly  60  per  cent,  of 
the  viable  fecal  flora. 

No  implantation  of  bacilli  in  the  alimentary  tract  will  prove  per- 
manent unless  the  diet  affords  a  suitable  pabulum  for  the  maintenance 
of  the  varieties  introduced.  In  other  words,  the  best  way  to  influence 
the  bacterial  flora  of  the  digestive  tube  is  through  diet.  A  carbohy- 
drate diet  favors  the  fermentative  types  and  a  protein  diet  *the  putre- 
factive types  of  bacteria.  Kendall,  in  his  work  on  intestinal  bacteri- 
ology, has  shown  that  carbohydrates  spare  proteins;  that  is,  bacteria  do 
not  ordinarily  break  down  protein  in  the  presence  of  carbohydrates. 

Herter  and  Kendall  ^  were  the  first  clearly  to  establish  the  fact  that  the 
chemical  character  of  the  food  ingested,  under  normal  physiologic  con- 
ditions, is  the  fundamental  factor  controlling  the  types  of  bacteria  vege- 
tating in  the  intestinal  tract.  Secondary  factors  of  almost  equal  weight 
are  the  rate  and  degree  of  digestion  and  absorption  of  food  and  the 
character  of  the  end  products  of  the  digestive  process.  It  has  -been 
demonstrated  experimentally  in  Torrey's  ^^  investigation  with  dogs  that, 
on  the  one  hand,  not  all  carbohydrates  have  an  equal  tendency  to  estab- 
lish a  purely  fermentative  intestinal  flora,  and,  on  the  other  hand,  not 
all  protein  foods  encourage  putrefactive  conditions  in  a  like  degree. 
When  taken  as  the  sole  food  supply  by  the  adult,  milk  is  very  liable  to 
produce  constipation,  and  because  of  its  high  protein  content  may  lead 
to  the  excessive  development  of  putrefactive  bacteria  in  the  intestine. 
McCollum  states  that  the  cages  of  rats  fed  solely  on  milk  develop  an 
.offensive  odor.  The  addition  of  carbohydrates,  such  as  starch  or  cer- 
tain of  the  sugars,  tends  to  cause  the  disappearance  of  the  obnoxious  flora 
from  the  alimentary  tract,  and  favors  the  development  instead  of  types 
which  do  not  produce  decomposition  products  in  their  action  on  pro- 
teins. 

Putrid  Milk— Alkaline  Putrefaction. — When  boiled  milk  is  al- 
lowed to  stand  at  room  temperature,  it  gradually  acquires  an  alkaline 
reaction,"  a  bitter  taste,  and  finally  curdles,  yielding  a  soft,  slimy  curd. 
On  further  standing  this  curd  is  peptonized  to  form  a  somewhat  clear 
fluid,  and  if  these  putrefactive  changes  are  allowed  to  proceed  for  a 

\Journ.  Biological  Chem.,  1910,  VII,  203. 
^"Journ.  Med.  Research,  Jan.,  1919,  pp.  415-447. 

"Schorer  found  that  such  milk  becomes  less  acid  but  seldom  becomes  actually 
alkaline  in  reaction. 


MILK  771 

sufficient  length  of  time  a  semi-transparent  liquid  is  obtained,  having  no 
resemblance  to  milk.  In  this  form  of  decomposition  the  main  change 
occurs  in  the  protein  constituent  of  the  milk.  The  putrefactive  changes 
of  milk  are  undesirable  and  are  believed  sometimes  to  be  dangerous,  in 
that  toxic  substances  may  be  produced.  The  principal  cause  of  putre- 
faction in  milk  is  tlie  spore-bearing  group  of  bacilli,  belonging  to  and 
resembling  the  hay  bacillus  and  also  the  anaerobes. 

Slimy  or  Ropy  Milk. — Tender  some  circumstances  certain  muci- 
laginous substances  develop  in  milk  through  abnormal  fermentation. 
Slimy  milk  has  been  obtained  of  such  viscosity  that  it  could  be  drawn 
out  into  threads  ten  feet  in  length,  and  of  such  thinness  as  to  be  scarcely 
visible.  In  Xorway  such  milk  is  esteemed  a  delicacy;  in  this  country, 
however,  it  is  objectionable.  From  a  health  standpoint  ropy  milk  is 
not  injurious  unless  it  is  slimy  as  a  result  of  mucopurulent  materials 
caused  by  diseased  conditions  'in  the  mammary  glands.  The  bacteria 
which  produce  roj^y  milk  are  widely  distributed  in  nature.  Of  these 
B.  lactis  viscosi  (Adametz)  is  the  commonest  organism  found  in  Eu- 
rope, and  a  similar  organism  occurs  in  this  country.  B.  lactis  viscosi 
is  very  hardy;  it  may  find  its  way  into  the  milk  through  the  water 
supply  of  the  dairy,  and  then  becomes  widely  diffused  and  difficult  to 
trace.  It  is  sometimes  very  troublesome,  but  may  be  eradicated  through 
cleanliness.  Sometimes  it  is  necessary  to  resort  to  disinfection.  Other 
organisms  producing  sliminess  in  milk  are  the  Micrococcus  freuden- 
reicliii,  two  forms  of  streptococci,  and  certain  of  the  lactic  acid  bacteria. 

Alcoholic  Fermentation  of  Milk. — This  is  an  unusual  fermentation 
which  sometimes  occurs  as  a  result  of  yeasts,  aided  in  their  action  by 
certain  species  of  bacteria.  Alcoholic  fermentation  of  milk  seldom  oc- 
curs spontaneously,  but  may  be  induced  by  direct  inoculations  with  cer- 
tain ferments,  such  as  those  employed  in  the  production  of  kumyss  and 
kefir. 

Kumyss  was  originally  made  from  mare's  milk ;  it  is  now  made  from 
cow's  milk  by  the  addition  of  cane  sugar  and  yeast.  Kefir  is  a  similar 
beverage,  originating  in  the  Caucasus,  where  the  fermentation  is  carried 
out  in  leather  bottles  and  is  started  by  means  of  "kefir  grains''  which 
contain  yeast  and  various  microorganisms. 

Bitter  Milk. — Freshly  dravrn  milk  sometimes  has  a  bitter  taste ;  in 
other  instances  milk  acquires  such  a  taste  on  standing  a  few  hours. 
The  former  is  due  to  improperly  feeding  the  cow  with  such  herbs  as 
lupines,  wormwood,  raw  Swedish  turnips,  cabbages,  etc.  The  latter  case 
is  due  to  the  growth  of  certain  bacteria  in  the  milk  after  it  is  drawn. 
The  condition  is  undesirable,  and  sometimes  causes  much  trouble  for  the 
dairyman,  but  it  has  no  particular  sanitary  significance.  According  to 
Conn,  it  is  a  micrococcus,  and  according  to  Weigmann  a  bacillus,  that 
has  the  power  of  ruining  the  taste  of  freshly  drawn  milk  in  a  few  hours. 


772  ANIMAL  FOODS  :    MILK 

This  condition  should  be  distinguished  from  the  bitter  taste  of  putrid 
milk  above  noted. 

Colored  Milk.— Blue  milk  is  usually  due  to  the  Bacillus  cyanogmus. 
Such  milk  is  apparently  harmless.  Eed  milk  may  be  due  to  the  pres- 
ence of  blood  coming  from  an  injury,  or  acute  infection  of  the  udder. 
Sometimes  it  results  from  the  feeding  of  the  cow  on  plants  containing 
red  pigment,  such  as  the  madder  root.  A  red  color  may  also  be  pro- 
duced by  the  Bacillus  ery  thro  genes,  B.  prodigiosus  and  sarcinae.  Eed 
milk  caused  through  the  agency  of  bacteria  is  not  known  to  be  harmful. 

Adulterations  of  Milk — SUmming. — The  removal  of  part  or  all  of 
the  cream  and  selling  the  remaining  fluid  as  whole  milk  is  an  economic 
fraud,  and  has  no  reference  to  health,  except  that  the  milk  is  cor- 
respondingly lowered  in  nutritive  value.  Adding  skim  milk  is  also  a 
form  of  adulteration  difficult  to  detect. 

Watering. — The  practice  of  watering'  is  not  nearly  so.  frequent  as 
formerly.  If  the  water  be  pure  it  must  be  regarded  more  as  a  fraud 
than  a  health,  problem.  The  addition  of  water  to  milk  lowers  its  specific 
gravity,  raises  its  freezing  point,  and  lowers  its  index  of  refraction  and 
also  its  viscosity. 

Thickening  agents,  such  as  chalk,  calves'  brains,  and  glycerin,  have 
never  been  common  practices.  Gelatin  or  lime  is  sometimes  used 
to  thicken  cream.  Cream  may  also  be  thickened  by  homogenizing  it. 
Coloring  matter  is  sometimes  added  with  the  object  of  concealing  skim- 
ming or  watering  or  to  make  the  milk  look  richer.  Annatto,  a  vege- 
table dye,  is  most  commonly  used;  orange  and  yellow  azo  coal-tar  are 
also  used.  Alkalies,,  such  as  sodium,  carbonate  or  bicarbonate,  are 
occasionally  added  to  milk  to  reduce  its  acidity  or  to  improve  its  taste 
or  to  delay  curdling.  Siveet  substances,  such  as  saccharin  or  sugar, 
are  occasionally  added  to  milk,  either  to  raise  the  specific  gravity  and 
thus  disguise  watering,  or  to  disguise  the  sour  taste  of  milk  just  on 
the  turn. 

Chemical  Preservatives. — Chemical  preservatives,  such  as  borax  and 
boric  acid,  salicylic  acid,  benzoic  acid  and  benzoates,  potassium  bichro- 
mate, peroxid  of  hydrogen,  fluorids,  formaldehyd,  and  others,  have  from 
time  to  time  been  used  in  milk.  The  practice  of  adding  any  chemical 
preservative  to  milk  meets  with  the  unqualified  disapproval  of  the  sani- 
tarian. Almost  all  countries  prohibit  the  use  of  such  foreign  substances. 
The  only  proper  preservatives  for  milk  are  cleanliness  and  cold. 

Dirty  Milk;  The  Dirt  Test. — Practically  all  milk  contains  more  or 
less  dirt.  For  the  most  part,  this  dirt  consists  of  cow  feces.  The  pres- 
ence of  dirt  may  best  be  determined  by  filtering  a  pint  of  milk  through 
a  little  disk  of  absorbent  cotton.  This  produces  a  stain  varying  in  inten- 
sity from  a  yellowish  to  a  brownish  or  black  spot.  A  Gooch  crucible, 
a  Lorenz  apparatus,  or  simply  an  ordinary  funnel  may  be  used  to  filter 


MTLK 


77.1 


the  milk.  Wanii  milk  filters  miu-li  more  readily  than  eold  milk.  Tiiis 
simple  test  is  one  of  the  most  ])ractieal  of  the  routine  tests  used  for  the 
puhlic  health  control  of  milk  supplies.  The  intensity  of  tlic  stain  and 
the  amount  of  deposit  upon  the  cotton  is  a  tell-tale  which  appeals  strongly 
to  farmers  ami  dairymen,  as  well  as  to  consumers.  It  is  a  good  practice 
to  send  these  disks  of  cotton,  with  a  letter,  to  the  farmer,  showing  him 
the  amount  of  dirt  contained  in  his  milk.  The  disks  may  be  dried  and 
kept  with  the  records  of  the  health  office. 

It   should   be   remembered   that   milk   that   has   been    "clarified"   or 
strained  will  not  show  the  dirt  test. 


Fig.  78. — Conditions  under  Which  It  Is  Difficult  to  Cleanse  and  Disinfect 
jVIilk  Bottles  and  Milk  Pails. 


Clarification. — Clarification  is  mechanical  straining  by  the  use  of 
centrifugal  force.  Clarifiers  whirl  the  milk  with  sufficient  force  to 
remove  heavy  substances,  but  not  sufficiently  to  separate  the  cream.  Milk 
so  treated,  therefore,  will  not  deposit  a  sediment  on  standing.  The  ma- 
terial thrown  out  by  this  method  of  clarification  is  called  "separator 
slime,"  and  consists  of  dirt,  foreign  particles  of  all  sorts,  bacteria,  pus, 
blood,  mucus,  and  also  substances  normally  present  in  milk.-  The 
exact  nature  of  the  material  removed  is  not  yet  fully  understood. 

The  only  advantages  of  clarification  are  that  it  removes  visible  dirt 
and  performs  the  work  of  a  strainer  in  a  much  more  efficient  manner. 
Against  clarification  are  the  facts  that  it  does  not  remove  pathogenic 
microorganisms,  and  hence  may  mislead  as  to  the  real  purity  of  the  milk; 
it  does  not  remove  urine  or  soluble  portions  of  feces:  nevertheless, 
the  milk  appears  clean.  It  adds  another  process  in  handling  the  milk 
and  hence  complicates  the  situation;   it  largely  destroys  the  value  of 


11 A  ANIMAL  FOODS:    MILK 

the  dirt  test,  although  not  more  so  than  good  straining;  it  breaks  up 
clumps  of  bacteria  and  distributes  them  through  the  milk.     Owing  to 
•  exaggerated  claims,  clarification  may  give  a  false  sense  of  security. 

The  bacterial  content  of  milk  is  apparently  increased  by  clarifica- 
tion. This  is  due  to  the  breaking  up  of  bacterial  clusters,  which  thereby 
increase  the  number  of  colonies  on  a  plate.  If  the  machine  is  not  kept 
clean,  contamination  may  take  place  and  there  may  be  an  actual  in- 
crease of  the  bacteria  in  clarified  milk. 

Clarification  and  straining  have  no  sanitary  advantages  and  the 
process  should  be  controlled  and  inspected. 

Bacteria  in  Milk. — As  a  rule,  milk  contains  relatively  and  actually 
more  bacteria  than  any  other  article  of  diet.  Milk  may,  in  fact,  con- 
tain more  bacteria  than  any  other  known  substance;  it  frequently  con- 
tains many  more  bacteria  than  are  found  in  sewage.  Mer6  numbers, 
however,  need  not  alarm  us,  for  it  is  the  kind  that  most  concerns  us. 
By  universal  consent,  however,  niilk  containing  an  excessive  number 
of  miscellaneous  bacteria  is  not  suitable  for  infant  feeding.  Were  milk 
a  transparent  food  the  enormous  growth  of  microorganisms  present  in 
average  market  milk  would  be  plainly  visible  to  the  naked  eye. 

The  bacteria  get  into  the  milk  from  a  number  of  different  sources. 
Some  of  them  are  in  the  milk  before  it  leaves  the  udder.  They  grow 
up  the  milk  ducts  into  the  milk  cistern;  hence,  the  fore-milk  contains 
more  than  the  mid-milk  or  strippings.  It  is  practically  impossible  to 
obtain  sterile  milk  directly  from  the  teat  in  any  large  quantity.  As 
soon  as  the  milk  leaves  the  teat  it  receives  additional  contamination 
from  all  objects  with  which  it  comes  in  contact,  as  the  hands,  the  pail, 
the  dust  in  the  air,  etc.  Most  bacteria  get  into  milk  with  the  dirt  chat 
falls  from  the  belly  and  udder  of  the  cow  during  milking. 

The  most  important  factors  to  obtain  milk  with  a  low  bacterial 
count  are:  sterilized  utensils;  clean,  healthy  cows  with  clean  udders 
and  teats;  and  the  use  of  the  small  top  milk  pail.  To  keep  the  counts 
low,  it  is  necessary  to  chill  the  milk  at  once  and  to  hold  it  at  about 
40°  C. 

Judged  by  the  number  of  colonies  on  Petri  plates,  the  number  of 
bacteria  in  milk  increases  every  time  it  is  handled  or  exposed  in  any 
way.  Separator  milk  contains  more  bacteria  than  the  original  milk. 
The  same  is  true  of  filtered  milk.  This  is  due  to  the  fact  that  while 
some  of  the  visible  dirt  in  the  milk  is  taken  out,  the  particles  are 
broken  up  and  the  bacteria  dispersed  throughout  the  fluid. 

Garget,  or  inflammation  of  the  udder,  is  a  very  common  affection  of 
cows,  and  is  associated  with  streptococci,  staphylococci,  lactic  acid  and 
colon  bacilli,  etc.  Milk  from  a  gargety  udder  will  contain  enormous 
numbers  of  the  corresponding  microorganisms. 

For  the  most  part  bacteria  do  not  pass  a  healthy  udder.     However, 


MILK 


775 


we  can  place  no  trust  in  the  filtering  ability  of  the  mammary  gland.  It 
is  known  that  the  virus  of  foot-and-mouth  disease,  which  is  ultramicro- 
scopic,  and  the  virus  of  malta  fever  ( M icrococcu.'i  melilensis),  and  also 
the  virus  of  milk  sickness  are  almost  constantly  found  in  the  milk  of 
affected  animals.  On  the  other  hand,  tubercle,  anthrax  and  other  large 
bacilli  do  not  pass  the  mammary  gland  unless  there  is  a  lesion  of  the 
udder. 

There  is  occasional  danger  to  human  beings  from  infected  udders 
of  dairy  cows  when  the  udder  infection  is  due  to  pathogenic  bacteria 
of  human  origin.     The  danger  from  udder  infection  when  the  bacteria 


Fig.  79. — ^A  Dark,  Poorly  Ve>'^tilated  Cow  Shed,  Difficult  to  Keep  Clean. 


are  of  bovine  origin  has  not  yet  been  determined  and  is  uncertain,  with 
the  exception  of  infections  from  bovine  tuberculosis  which  are  known 
to  be  dangerous  to  human  beings.  Every  effort  should  be  made  to 
exclude  udder  infections  from  dairy  herds.  Pasteurization  is  a  pro- 
tection because  it  destroys  the  bacteria  of  udder  infections  in  milk. 
The  bacteria  in  milk  are  not  equally  distributed  throughout  the 
fluid.  There  are  more  bacteria  in  cream  than  in  the  underlying-  skim 
milk — particularly  in  gravity  cream.  As  the  cream  rises  it  mechanically 
carries  the  bacteria  along  with  it,  very  much  as  a  snowstorm  sweeps  the 
atmosphere.  Milk  formulae  for  infant  feeding  are  often  made  of  top 
milk,  which,  however,  may  contain  from  o  to  100  times  the  number  of 
bacteria  per  cubic  centimeter  found  in  the  whole  milk.  In  twenty-six 
samples  of  milk  Anderson  found  the  gravity  cream  contained  about  four 
times  as  many  bacteria  as  the  sediment  layer,  and  about  one-third  as 
many  as  the  whole  milk.    Schorer  found  that  the  cream  from  milk  of  high 


776  ANIMAL  FOODS:    MILK 

bacterial  count  contained  several  thousand  times  as  many  bacteria  as 
the  underlying  skim  milk. 

Certified  milk  should  not  contain  over  10,000  bacteria  per  cubic 
centimeter;  grade  A  not  over  200,000  before,  and  not  over  10,000  after 
pasteurization;  inspected  milk  not  over  100,000,  and  market  milk  not 
over  500,000.  New  York  has  placed  the  limit  at  1,000,000  per  cubic 
centimeter.  Even  this  standard,  however,  has  not  been  rigidly  en- 
forced.    Boston  has  a  standard  of  500,000;  Eochester  100,000. 

In  Washington  in  1908  the  average  bacterial  count  of  the  market 
milk  was  22,000,000  per  cubic  centimeter,  as  found  in  many  hundreds 
of  samples  of  the  city  supply^*  In  1909  the  average  was  reduced  to 
11,000,000. 

Excessive  numbers  of  bacteria  in  milk  indicate  that  it  is  (^irty,  old, 
or  warm.  Any  one  or  any  combination  of  these  factors  favors  a  rapid 
growth  and  multiplication  of  the  bacteria  in  milk.  , 

The  number  of  bacteria  in  milk  is  the  best  single  index  we  have  of  its 
general  sanitary  character. 

Methods  for  determining  the  number  and  kind  of  bacteria  in  milk 
will  be  found  on  page  794. 

The  G-ermicidal  Property  of  Milk. — The  so-called  germicidal  prop- 
erty of  milk  has  been  much  misunderstood.  Judged  by  the  number  of 
colonies  that  develop  upon  agar  plates,  the  bacteria  in  milk  first  di- 
minish, then  increase  in  number.  This  occurs  only  in  raw  milk  during 
the  first  8  or  12  hours  after  it  is  drawn.  Although  the  bacteria  seem- 
ingly decrease  in  numbers,  they  never  entirely  disappear.  After  this 
initial  decrease  there  is  a  continuous  and  rapid  increase,  until  the  milk 
contains  almost  infinite  numbers  in  each  cubic  centimeter.  This  power 
of  milk  to  restrain  the  development  of  bacteria  lasts  from  6  to  24  hours, 
depending  upon  the  temperature  at  which  the  milk  is  kept.  When 
the  milk  is  kept  warm,  37°  C,  the  decrease  is  pronounced  within  the 
first  8  or  10  hours;  after  this  the  milk  has  entirely  lost  its  restraining 
action.  When  the  milk  is  kept  cool,  15°  C,  the  decrease  is  less  marked 
but  more  prolonged. 

The  decrease  in  the  number  of  bacteria  is  largely  apparent,  being 

due,  at  least  in  part,  to  agglutination  ^^ ;  that  is,  the  bacteria  are  not  killed, 

they  are  simply  grouped  in  clusters ;  this  is  proved  by  the  fact  that  these 

clusters  may  be   shaken   asunder.      The   germicidal   action   of  milk   is 

specific;  at  most,  is  feeble,  and  is  destroyed  if  the  milk  is  heated  above 

80°  C.     It  varies  in  different  animals,  and  in  the  milk  from  the  same 

animal  at  different  times.    It  cannot  take  the  place  of  cleanliness  and  ice, 

but  may  be  taken  advantage  of  in  good  dairy  methods.     It  is  true  that 

^Chalmers  {Jour,  of  Bacteriology,  Y,  6,  Nov.,  1920)  finds  no  common  rela- 
tion between  agglutination  and  bacterial  inhibition  in  milk,  and  that  there  is  a 
real  germicidal  property  in  milk  which  is  destroyed  between  80°  and  90°  C. 
for  two  minutes. 


MILK 


777 


bacteria  develop  more  quickly  in  hfaU'd  milk  than  raw  milk,  provided  the 
raw  milk  is  fresh ;  it  should  he  remembered,  however,  that  milk  that  is 
a  day  old  no  longer  possesses  this  restraining  action.  The  germicidal 
property  is,  therefore,  ordinarily  absent  in  market  milk. 

Diseases  Spread  by  Milk. — Tlu'  diseases  conveyed  through  milk  are: 
tuberculosis,  tyjihoid  and  ])araty])hoid  fevers,  diphtheria,  scarlet  fever, 
septic  sore  throat,  malta  fever,  foot-and-mouth  disease,  and  milk  sickness, 
also  some  of  the  summer  complaints  of  children,  and  the  diarrheal  and 
dysenteric  diseases  of  adults,  which  are  often  referable  to  infected  milk. 

As  a  rule,  milk  becomes  infected  from  human  sources,  sometimes 
on  the  farm,  sometimes  at  the  dairy,  sometimes  in  transportation,  and 
occasionally  in  the  household,  ililk-borne  epidemics  are  due  to  human 
sources  of  infection.  Sometimes  the  milk  becomes  infected  as  a  result 
of  disease  of  the  animal,  as  in  the  case  of  bovine  tuberculosis,  malta  fever, 
foot-and-mouth  disease,  streptococcal  garget,  etc. 

When  all  the  facts  are  brought  together  they  make  a  strong  indict- 
ment against  milk.  Thus,  during  the  five  years,  1907-11,  there  were 
five  milk-borne  outbreaks  in  Boston,  causing  a  total  of  over  4,000 
cases  of  sickness. 


Year 


1907 
1907 
1908 
1910 
1911 


Milk-borne  BFidemics   in    Greater   Boston 

Diphtheria 

Scarlet   fever 

Typhoid  fever,  about 

Scarlet  fever,  over 

'•'Septic  sore  throat,"  over 


Cases 


72 

717 

400 

842 

2,065 


4,096 


In  addition  to  the  specific  diseases,  milk  may  be  injurious  as  a  result 
of  other  causes.  Thus,  Le  Blanc  has  pointed  out  that  the  milk  of  cows 
in  heat  may  cause  gastro-intestinal  disturbances.  The  toxic  effects  of  milk 
and  milk  products  of  nymphomanous  cows  are  even  more  marked.  Milk 
should  not  be  used  within  fifteen  days  of  parturition.  The  require- 
ment for  certified  milk  is  placed  at  thirty  days  before  and  fifteen  days 
after.  Such  milk  is  apt  to  produce  diarrhea,  colic,  and  other  diges- 
tive disturbances.  Milk  may  further  be  harmful  as  a  result  of  such 
diseases  as  mastitis  or  garget,  gastro-enteritis,  septic  and  febrite  con- 
ditions of  the  cow.  Eecently  it  has  been  shown  that  contagious  abor- 
tion of  cows  is  due  to  the  Bacillus  abortus,  which  may  contaminate 
milk;  it  is  pathogenic  for  many  animals,  but  there  is  no  evidence  that 
it  is  harmful  to  man.  Schroeder  and  Cotton  found  this  bacillus  in  8 
out  of  27  samples  of  market  milk  tested. 

Tuberculosis. — Bovine  tubercle  bacilli  get  into  milk  either  directly 
as  a  result  of  tuberculosis  of  the  udder,  which  occurs  in  from  1  to  2 


778  ANIMAL  FOODS:    MILK 

per  cent,  of  all  tubercular  cows,  or  indirectly  through  cow  manure.  In 
the  latter  case  the  tubercle  bacilli  are  coughed  up,  swallowed,  and  passed 
in  the  feces.  Practically  all  market  milk  contains  cow  feces.  Occasion- 
ally milk  contains  tubercle  bacilli  of  the  human  type  from  human  sources. 
Tuberculosis  in  cattle  is  very  prevalent.  In  Holland  nearly  one-tenth  of 
all  cattle  killed  for  food  are  tuberculous;  in  Berlin  16  per  cent.;  in  Sax- 
ony 30  per  cent. ;  in  Pennsylvania  from  2  to  3  per  cent.  The  "milk" 
from  a  tuberculous  udder,  when  examined  under  the  microscope,  may 
contain  as  many  tubercle  bacilli  as  are  ordinarily  found  in  tuberculous 
sputum.  The  milk  from  a  tuberculous  udder  of  one  cow  may  contain 
sufficient  bacilli  seriously  to  infect  the  mixed  milk  of  25  or  30  cows. 
In  one  case  Ostertag  found  that  0.001  c.c.  of  the  secretion  from  a 
tuberculous  udder  was  sufficient  to  cause  tuberculosis  in  a  guinea-pig. 
In  such  a  case  a  child  would  receive  an  enormous  dose  in  a  gill. 

Tonney  examined  the  market  milk  of  Chicago  in  1910  for  the  presence 
of  tubercle  bacilli.  In  10.5  per  cent,  of  144  samples  of  raw  milk  he 
found  tubercle  bacilli  in  sufficient  numbers  to  infect  guinea-pigs.  Of 
19  samples  of  pasteurized  milk  examined  none  contained  tubercle  bacilli. 

Hess  in  1909  examined  107  samples  of  market  milk  in  New  York 
City,  with  the  result  that  17  of  them,  or  16  per  cent.,  were  found  to 
contain  tubercle  bacilli. 

Anderson  examined  223  samples  taken  in  the  city  of  Washington, 
and  reported  16,  or  6.72  per  cent.,  as  positive.  The  tests  made  by  the 
Bureau  of  Animal  Industry  of  the  milk  in  Washington  disclosed  7.7 
per  cent,  infected.  Goler  reports  about  5  per  cent,  of  the  milk  supply 
of  Eochester,  N.  Y.,  infected. 

To  sum  up,  we  have  evidence  from  four  typical  American  cities. 
A  total  of  551  samples  of  milk  have  been  examined,  in  which  tubercle 
bacilli  were  found  in  46,  making  a  percentage  of  8.3.  This  may  be 
taken  as  the  average  percentage  for  the  entire  country. 

Sheridan  Delepine  ^^  reports  that  the  mixed  milk  of  Manchester, 
Eng.,  collected  at  railway  stations  or  other  places  than  the  farm,  con- 
tained tubercle  bacilli,  as  follows  in  the  samples  examined  from 

1897  to    1899 17.2  per  cent. 

1900  'to    1904 10.3  per  cent. 

1905  to    1909 6.8  per  cent. 

1910  to    1913 9.0  per  cent. 

(years  are  inclusive) 

Wherever  these  investigations  have  been  carried  out  similar  and  some- 
times higher  results  have  been  obtained,  both  in  Europe  and  in  this 
country.     It  is  believed  that  the  figures  are  an  underestimate,  for  the 

^Jour.  of  State  Med.  Rep.,  November  and  December,  1914. 


MILK  779 

methods  used  in  the  laboratory  are  not  sufficiently  delicate  to  detect 
a  few  tubercle  bacilli  in  milk.  Unless  these  microorganisms  are  pres- 
ent in  considerable  numbers,  they  are  apt  to  escape  detection.  In  any 
event,  it  is  clear  that  the  common  market  milk  furnished  all  large  cities 
and  probably  most  small  towns  very  often  contains  tubercle  bacilli. 

Mohler,  Washburn,  and  Doane  found  tubercle  bacilli  to  live  a  year 
and  more  in  cheese  "220  days  old.  In  these  experiments  the  cheese  was 
purposely  infected  and  fed  or  inoculated  into  guinea-pigs  at  various 
times.  Tubercle  bacilli  are  frequently  found  in  butter  and  other  milk 
products,  especially  if  the  milk  or  cream  of  which  they  are  made  has 
not  been  pasteurized  (page  785). 

The  relation  of  bovine  tuberculosis  to  man  is  considered  on  page  166. 

Method  of  Detecting  Tubercle  Bacilli  in  Milk. — It  is  not  a  simple 
matter  to  discover  tubercle  bacilli  in  milk,  butter,  and  similar  products. 
Direct  microscopic  examination  for  acid-fast  bacilli  is  not  satisfactory, 
because  ordinarily  there  are  comparatively  few  tubercle  bacilli  in  mixed 
market  milk,  and  furthermore,  many  acid-fast  microorganisms  other  than 
tubercle  bacilli  may  occur  in  milk. 

It  is  not  an  easy  task  to  isolate  tubercle  bacilli  in  pure  culture,  be- 
cause the  enormous  number  of  other  saprophytic  microorganisms  over- 
grow the  cultures. 

It  therefore  becomes  necessary  to  resort  to  animal  experimentation 
in  order  to  detect  and  isolate  tubercle  bacilli.  The  guinea-pig  is  the 
most  susceptible  and  suitable  animal  for  this  purpose.  The  material 
under  examination  may  be  injected  subcutaneously  or  intraperitoneally. 
A  number  of  animals  should  be  inoculated  with  the  sample  in  question 
for  the  reason  that  a  certain  proportion  of  them  will  succumb  to  acute 
infections,  especially  streptococci  or  members  of  the  hemorrhagic  sep- 
ticemic group,  which  are  often  found  in  milk.  For  this  reason,  it  is 
advisable  to  inject  variable  amounts  for  the  purposes  of  the  test.  Less 
will  be  required  if  the  sample  is  the  milk  from  one-quarter  of  a  cow  than 
from  the  mLxed  milk  of  a  herd. 

The  tubercle  bacilli  in  milk  may  be  first  concentrated  by  centrifuga- 
tion.  Some  of  them  will  fall  to  the  bottom  with  the  sediment,  others 
will  rise  with  the  cream,  being  enmeshe»d  and  carried  by  the  fat  globules. 
The  cream  and  sediment  may  then  be  injected  into  guinea-pigs,  either 
separately  or  mixed.  It  should  be  remembered  that  this  process  not 
only  concentrates  the  tubercle  bacilli,  but  other  microorganisms  that 
may  be  in  the  milk. 

The  sediment  may  first  be  treated  with  antiformin,  which  destroys 
many  of  the  frailer  cocci  and  bacilli,  but  spares  the  tubercle  bacilli. 
Antiformin  is  a  strong  alkaline  solution  of  chlorinated  soda  (see  page 
1421). 

The  guinea-pigs  that  survive  the  early  pathogenic  infections  that 


780  ANIMAL  FOODS:    MILK 

contaminate  the  milk  should  be  watched  for  symptoms  of  tuberculosis — 
enlarged  glands,  loss  of  weight  and  fever.  Those  that  do  not  die  in  two 
months  should  be  tested  with  tuberculin.  Inject  2  c.c,  subcutaneously, 
of  Koch's  old  tuberculin.  This  must  be  diluted  back  to  the  original 
strength  of  the  bouillon  culture.  If  the  guinea-pig  is  tuberculous  it  will 
die  within  twenty-four  hours — usually  in  from  8  to  16 — with  character- 
istic lesions  of  reaction  about  the  tuberculous  foci. 

Typhoid  Fever. — Of  milk-borne  epidemics,  typhoid  fever  takes  the 
lead.  Typhoid  bacilli  may  swarm  in  milk  without  altering  its  taste, 
odor,  or  appearance.  In  Washington  10  per  cent,  of  all  the  cases  of 
typhoid  fever  during  the  four  years  1907-10  were  traced  to  milk.  The 
milk  may  become  infected  by  a  convalescent,  a  carrier,  or  a  missed  case. 

Bolduan  estimates  that  from  300  to  400  cases  of  typhoid  fever  each 
year  come  in  contact  with  the  milk  supplied  New  York  City.  He  fur- 
ther states  that  "the  startling  total  of  90  to  120  typhoid  carriers  now 
probably  menace  the  milk  supply  of  this  city."  This  estimate  is  based 
upon  the  fact  that  about  200,000  persons  come  into  more  or  less  con- 
tact with  the  milk  from  over  40,000  dairy  farms.  See  Typhoid  Fever, 
page  121. 

Typhoid  fever  has  also  been  traced  to  cream,  ice  cream,  and  other 
milk  products. 

Milk-borne  outbreaks  of  paratyphoid  fever  have  been  described  by 
Levin  and  Elberson  ^*  and  others. 

Scarlet  Fever. — Milk-borne  outbreaks  of  scarlet  fever  are  sometimes 
extensive  and  serious.  The  milk  is  practically  always  infected  from 
human  sources.  There  is  a  suspicion,  however,  that  some  streptococcal 
infections  of  the  cow  may  reproduce  a  disease  resembling  scarlet  fever 
in  man.     See  Scarlet  Fever,  page  222. 

Diphtheria. — Diphtheria  bacilli  in  milk  usually  come  from  human 
sources,  either  cases  or  carriers.  In  a  few  instances  ulcers  upon  the 
teat  of  the  cow  have  become  infected  with  diphtheria,  and  the  bacilli 
are  thus  transferred  to  the  milk.  Such  an  occurrence,  however,  is  un- 
usual. As  a  rule,  diphtheria  outbreaks  caused  by  infected  milk  are  more 
limited  both  as  to  numbers  and  area  than  milk-borne  outbreaks  of 
typhoid  or  scarlet  fever.     See  Diphtheria,  page  195. 

Septic  Sore  Throat. — The  first  milk-borne  outbreak  of  "septic  sore 
throat"  recognized  in  this  country  occurred  in  and  about  Boston  in 
May,  1911.  Since  then  similar  outbreaks  have  occurred  in  Baltimore, 
Concord,  N.  H.,  Chicago,  and  elsewhere.  The  infection  is  spreading. 
The  Boston  outbreak  was  carefully  studied  by  Winslow  and  is  so  in- 
structive that  a  brief  account  of  it  is  given  below. 

Septic  sore  throat  due  to  infected  milk  has  been  well  known  in 
Great  Britain  for  thirty  years.     Swithinbank  and  Newman  state  that  a 

^*Jour.  Infect.  Dis.,  Feb.,  1916,  Vol.  18,  No.  2,  p.  143. 


MILK  781 

year  never  goes  by  in  which  there  are  not  outbreaks  of  sore  throat  or 
tonsillitis  due  to  milk  or  ereani.  These  infections  appear  to  be  due  to  a 
streptococcus,  several  varieties  having  been  isolated  both  from  the  milk 
and  the  throats  of  the  patients.  It  is  assumed  that  the  infection  usually 
gets  into  the  milk  from  human  sources,  although  it  is  suspected  that 
streptococci  eliminated  by  diseased  udders  may  be  responsible  for  some 
outbreaks. 

Theobald  Smith  and  J.  H.  Brown  ^^  have  shown  that  there 
is  a  ditferenee  between  bovine  and  h\iman  streptococci.  The  bovine 
streptococci  produce  garget  in  cows  but  do  not  cause  tonsillitis  in  men ; 
on  the  other  hand,  the  human  streptococci  produce  sore  throat  in  man 
but  have  slight  pathogenicity  for  cows.  The  human  streptococci  are 
alike  in  two  characteristics:  (1)  the  colonies  produce  immediately 
around  them  a  clear  hemolyzed.  zone  on  blood  agar  plates  (horse  blood)  ; 
(2)  these  organisms  ferment  salicin  but  not  raffinose  or  inulin.  Further 
they  are  pathogenic  when  injected  into  rabbits.  These  organisms  are 
called  by  Smith  and  Brown  the  Beta  type. 

Smith  and  Brown  studied  the  streptococci  from  five  milk-borne 
epidemics  at  first  hand,  together  with  cultures  from  the  big  epidemics 
of  Chicago,  Baltimore  and  Boston.  From  this  work  it  is  now  clear  that 
septic  sore  throat  in  man  is  of  human  origin,  even  when  the  disease  is 
contracted  through  milk  infected  in  the  udder,  for  it  was  found  that 
while  the- human  streptococcus  is  but  slightly  pathogenic  for  cows,  this 
organism  may  become  implanted  in  the  udder.  This  may  take  place 
through  milking,  wiping  with  infected  cloths,  through  passing  quills  up 
the  milk  ducts  and  in  similar  ways.  When  this  takes  place,  garget  does 
not  ensue  but  the  streptococcus  becomes  seeded  in  the  udder  and  may 
remain  for  six  weeks  or  longer.  In  other  words  the  cow  may  become  a 
"carrier''  of  the  human  streptococcus,  thus  explaining  why  milk-borne 
outbreaks  of  septic  sore  throat  are  sometimes  long  drawn  out. 

The  disease  often  presents  a  severe  clinical  type  and  may  result  in 
death.  Apparently  it  is  not  readily  communicable  from  person  to  person. 
The  inflammation  and  swelling  of  the  lymphoid  structures  of  the  throat 
and  of  the  mucous  membranes  are  more  severe  than  ordinarily;  edema 
is  a  feature,  and  many  cases  present  pseudomembranous  formation  and 
other  indications  of  a  virulent  infection.  There  is  a  sharp  febrile  re- 
action, prostration,  and  sometimes  delirium.  The  duration  of  the  dis- 
ease may  be  prolonged,  and  complications  occur  in  about  one-quarter  of 
the  cases.  These  consist  mostly  of  enlarged  regional  lymph  nodes,  which 
may  suppurate;  abscesses,  arthritis,  endocarditis,  peritonitis,  erysipelas, 
pneumonia,  pyemia,'  acute  nephritis,  otitis,  and  other  sequelae  indicating 
the  invasion  of  the  blood  with  a  virulent  streptococcus. 

"  Jowr.  of  Med.  Res.,  1915,  XXXI,  p.  455.  Also  W.  G.  Smillie,  ".On  the  Strep- 
tococcus of  Theobald  Smith,"  Jour.  Infect  Dis.,  Jan.,  1917,  Vol.  21,  No.  1,  p.  45. 


783  ANIMAL  FOODS:   MILK 

The  Boston  outbreak  in  1911  was  characterized  by  its  extraordinary 
virulence  and  comparative  immunity  of  children,  and  high  mortality 
among  the  aged  and  infirm.  In  this  outbreak  there  were  over  2,000 
cases  with  about  48  deaths.  One  of  the  features  of  special  interest  was 
that  the  milk  incriminated  had  always  been  a  particularly  clean,  fresh, 
and  satisfactory  supply.  It  was  obtained  from  tuberculin-tested  cows 
under  veterinary  supervision,  and  the  milk  itself  subjected  to  frequent 
chemical  and  bacteriological  tests.  The  milk  was  bottled  at  the  dairy, 
the  bottles  were  sterilized,  and  many  extra  precautions  were  taken  to 
ensure  its  cleanliness.  For  28  years  not  a  breath  of  suspicion  was  at- 
tached to  this  milk  until  this  catastrophe  occurred.  It  emphasizes  the 
lesson  that  raw  milk  is  apt  to  be  dangerous  milk,  and  our  only  protec- 
tion against  these  particular  dangers  is  through  pasteurization.^® 

Milk  Sickness. — Slows  or  trembles  is  a  peculiar  disease  formerly 
prevalent  in  the  central  part  of  the  United  States.  As  forests  are  cleared 
and  pastures  fenced  the  disease  becomes  less  frequent.  It  is  still  ex- 
ceptionally met  with  in  the  valley  of  the  Pecos  Eiver,  New  Mexico,  in 
parts  of  Tennessee  and  North  Carolina.  The  virus  is  communicated 
to  man  and  is  frequently  fatal.  Nancy  Hanks,  the  mother  of  Lincoln, 
died  from  the  disease  in  1818  after  an  illness  of  a  week.  Little  is  known 
of  the  cause  of  milk  sickness.  Jordan  and  Harris  have  found  a  bacillus 
associated  with  the  disease  which  they  have  called  the  Bacillus  lactis 
morbi.     The  cause  of  the  disease  is  not  known. 

Milk  sickness  is  an  acute  non-febrile  disease  due  to  the  ingestion  of 
milk,  milk  products,  or  the  flesh  of  animals  suffering  from  a  disease 
known  as  trembles.  The  disease  is  characterized  by  great  depression, 
persistent  vomiting,   obstinate   constipation,   and  high   mortality. 

Malta  Fever. — Malta  fever  is  a  disease  primarily  of  goats;  sec- 
ondarily of  man.  The  infection  is  transmitted  from  goats  to  man 
through  raw  milk  containing  the  Micrococcus  melit&nsis.     See  page  407. 

Foot-and-Mouth  Disease. — Foot-and-mouth  disease  is  an  infection 
primarily  of  cattle  and  secondarily  of  man.  It  is  caused  by  a  filtrable 
virus,  and  is  noteworthy  for  being  the  first  ultramicroscopic  virus  dis- 
covered by  Loeffler  and  Frosch  in  1898,  The  infection  is  transmitted  to 
man  through  the  ingestion  of  raw  milk,  buttermilk,  cheese,  or  whey 
from  diseased  cows.  Children  are  not  infrequently  infected  by  drinking 
unboiled  milk  when  the  disease  is  prevalent  in  the  neighborhood.  In 
man  the  disease  is  mild;  the  symptoms  resemble  those  observed  in 
animals;  there  is  fever,  sometimes  vomiting,  painful  swallowing,  heat 
and  dryness  of  the  mouth,  followed  by  an  eruption  of  vesicles  in  the 
buccal  and  mucous  membranes,  and  very  rarely  by  similar  ones  on  the 
fingers.     The  vesicles  are  about  the  size  of  a  pea ;  they  soon  break, 

"  For  a  more  detailed  study  of  this  and  other  milk-borne  outbreaks  see 
"The  Milk  Question,"  by  M.  J.  Rosenau. 


MILK  783 

leaving  small  erosions,  whith  rapidly  heal.  The  disease  is  seldom  fatal 
except  oi'casioiially  in  very  weak  childroii.     See  page  405. 

Food  Infections. — Bacillus  cntcritidis  and  all  other  ])atho(i:enic 
members  of  this  group  grow  well  in  milk,  and  may  thus  be  the  cause  of 
food  pi)isoning  outlircaks  (jiage  701). 

Dysentery. — This  has  been  traced  to  milk  in  a  few  instances.  Milk 
is  apparently  too  acid  for  the  \il)ri(»  of  cholera. 

Infantile  Diarrheas. — One  of  the  chief  causes  of  the  high  infant 
mortality  is  summer  diarrheas,  but  even  these  are  not  all  due  to  stale, 
dirty,  and  bacteria-laden  milk.  Many  of  the  diarrheal  diseases  of 
infancy  are  true  cases  of  bacillary  dysentery,  which  is  transmitted  in  a 
great  variety  of  ways.  However,  the  improvement  in  the  milk  supply 
for  babies  has  directly,  and  in  large  part  indirectly,  resulted  in  a 
decrease  in  infant  mortality  in  recent  years.  In  other  words,  improve- 
ment in  infant  mortality  is  almost  wholly  attributable  to  lessened 
diarrheal  diseases  in  the  summer  months.  Little  impression  has  yet 
been  made  npon  the  other  causes  of  infant  mortality. 

All  the  above  infections  may  also  be  conveyed  in  fresh  milk  products. 

The  Character  of  Milk-borne  Epidemics. — Milk-borne  epidemics 
usually  have  an  explosive  onset,  rise  to  a  peak,  and  decline  gradually. 
The  character  of  the  curve  depends  upon  the  amount  of  infection  in 
the  milk,  and  the  manner  of  its  distribution,  the  number  of  persons  who 
drink  it,  and  other  factors.  If  the  infection  in  the  milk  is  dilute  or 
attenuated,  the  disease  crops  out  among  a  few  susceptible  persons  who 
drink  it.  If  the  infection  is  concentrated  and  the  milk  is  widely  used, 
the  curve  of  the  outbreak  will  have  the  steeple-like  character  of  a  water- 
borne  epidemic.  The  length  of  the  epidemic  varies  with  the  period  of 
incubation  of  the  disease  and  with  the  length  of  time  the  milk  is  infected. 
The  number  of  people  involved  may  vary  from  a  few  to  a  hundred  or 
several  thousand.  Only  a  single  bottle  of  milk  may  be  infected,  and 
thus  convey  the  disease  to  only  one  person;  on  the  other  hand,  many 
gallons  of  mixed  dairy  milk  may  become  infected  and  produce  disease 
in  many  hundred  persons.  As  a  rule,  milk  outbreaks  last  a  comparatively 
short  time,  and  extend  over  a  circumscribed  area,  as  the  disease  follows 
the  milk  route.  At  first  the  disease  occurs  almost  exclusively  among 
users  of  the  infected  milk.     Afterward  secondary  cases  may  occur.  • 

The  disease  shows  a  special  incidence  among  milk  drinkers.  It  is 
interesting  to  note  that  sometimes  only  one  person  of  a  number  living 
in  the  same  house  is  attacked,  and  such  a  one  is  a  person  who  drinks 
the  milk  raw. 

Milk-borne  diseases  attack  those  living  under  the  best  sanitary  con- 
ditions. The  reason  for  this  is  that  such  people  drink  milk  more  freely 
than  the  poor.  Milk  outbreaks  among  the  well-to-do  are  unnecessary 
tragedies  to  the  sanitarian, 


784  ANIMAL  FOODS:    MILK 

Most  milk  outbreaks  show  a  greater  incidence  of  the  disease  among 
women  and  children,  who  are  usually  credited  with  drinking  more  milk 
than  men.  There  is  apt  to  be  a  short  period  of  incubation,  probably 
on  account  of  the  concentration  and  large  amount  of  the  infection; 
however,  the  disease  often  runs  a  mild  course.  Multiple  cases  occur 
simultaneously  in  the  same  house.  Such  an  occurrence  is  very  suggestive 
to  the  epidemiologist,  and  frequently  gives  him  the  first  hint  of  an  im- 
pending milk  epidemic. 

MILK  PRODUCTS 

Condensed  and  evaporated  milks  are  concentrated  by  partial  drying. 
The  first  really  practical  method  was  devised  by  Mr.  Gail  Borden,  of 
White  Plains,  New  York,  who  successfully  evaporated  milk  under  re- 
duced pressure,  and  in  1865  obtained  a  patent  for  his  process. 

Condensed  milk  is  not  sterilized  because  it  is  preserved  with  sugar, 
and  therefore  contains  great  numbers  of  bacteria — often  millions  per 
cubic  centimeter.  Evaporated  milk  is  unsweetened  and  must  be  proc- 
essed in  order  to  preserve  it ;  it  is  therefore  sterile,  or  nearly  so. 

Condensed  and  evaporated  milks  may  be  made  from  whole  milk, 
skimmed,  or  partly  skimmed  milk.  These  are  all  useful  and  legitimate 
products,  but  they  should  be  labeled  as  to  the  grade  of  the  milk  used, 
the  amount  of  butter  fat,  etc.  Inspection  should  be  maintained  to  ensure 
quality  and  cleanliness.  Condensed  and  evaporated  milks  at  prevailing 
prices  are  relatively  expensive  when  compared  to  fresh  milk.  Babies 
raised  on  these  products  are  apt  to  develop  scurvy  unless  given  'orange 
juice,  tomato  juice,  or  other  antiscorbutic. 

Dried  Milk  (MilTc  Powder).— WiW  may  be  dried  in  vacuo  at  moder- 
ate temperatures,  or  on  revolving  belts  or  drums  in  the  presence  of 
hot  dry  air.  The  presence  of  the  fat  has  interposed  the  greatest  difficulty 
to  the  complete  drying  of  milk.  In  the  Ekenberg  process  the  milk  is 
sprayed  under  constant  pressure  on  the  inner  surface  of  a  rotating  steam- 
heated  cylinder.  The  milk  is  thus  dried  in  partial  vacuum  at  a  com- 
paratively low  temperature.  A  more  frequently  employed  process  com- 
mon in  the  production  of  cheaper  grades  consists  in  spra3Qng  the  previ- 
ously concentrated  milk  on  the  exterior  highly  polished  surface  of  revolv- 
ing steel  drums.  Here  it  is  almost  instantaneously  dried  at  a  tempera- 
ture of  230°  F.  and  then  scraped  off  by  sharp  knife  blades.  In  the 
Benevot-de-Neveu  process  the  milk  is  first  concentrated  in  a  vacuum 
and  then  sprayed  under  great  pressure  into  a  large  drying  chamber  where 
the  cloud  of  finely  atomized  particles  is  surrounded  by  a  current  of  hot 
air,  and  thereby  instantly  dried.  The  result  is  a  powder  in  which  most  of 
the  physical  and  chemical  properties  of  the  original  milk  are  retained. 

The  process  has  been  improved  in  recent  years  to  sach  an  extent  that 


MTT.K  PT^OTnTTS  785 

when  milk  powder  of  good  quality  is  mixed  with  water  it  makes  a 
product  that  resembles  milk  in  all  essential  particulars. 

Dried  milk  powder  may  be  made  from  skim  milk,  from  partly 
skinmied  milk,  or  from  whole  milk,  rich  in  cream.  The  product  keep- 
well.  It  has  practically  all  the  nutritive  value  of  the  original  milk. 
The  "fat-soluble  A"  and  "water-soluble  B"  are  not  materially  affected, 
but  the  antiscorbutic  properties  are  diminished  about  one-half  that  of 
fresh  raw  milk.  In  other  words,  drying,  pasteurizing  and  age  have 
about  the  same  effect  on  this  vitamin  in  milk.  For  general  cooking 
and  food  purposes,  it  is  about  the  equal  of  liquid  milk. 

Dried  milk  has  all  the  uses  of  milk.  It  is  used  as  a  basis  of  certain 
proprietary  infant  foods;  it  is  employed  in  admixture  with  cocoa  and 
sugar;  with  egg  powder  and  sugar  as  a  custard  powder,  and  in  various 
other  food  combinations.  It  is  extensively  used  in  the  baking  and  con- 
fectionery trades.  It  is  convenient  in  the  household  and  economical 
so  far  as  waste  is  concerned. 

Babies  have  been  fed  on  dried  milk  exclusively  with  good  results, 
but  not  all  methods  of  drying  have  yet  been  tested.  The  answer  to 
this  question  must  await  a  number  of  years  of  patient  observation.  In 
any  case,  antiscorbutic  accessories,  as  orange  Juice,  should  be  used. 
Dried  milk  powder  makes  a  good  food  for  growing  children  and  adults. 

The  possibiKties  of  dried  milk  promise  a  revolution  in  the  milk 
industry.  It  permits  milk  to  be  produced  in  parts  of  the  world  where 
it  can  be  made  to  best  advantage.  It  saves  the  surplus  at  the  spring 
flush.  It  simplifies  the  present  cumbersome  distribution  to  the  house- 
holder, and  stabilizes  the  supply  for  large  cities.  Transportation  diffi- 
culties are  swept  away.  Sanitary  control  of  production,  and  honest 
labeling  are  therefore  doubly  important. 

Fresh  Milk  Products. — Cream,  butter,  buttermilk,  ice  cream,  sour 
milk,  fresh  cheese,  and  other  milk  products  may  convey  all  the  infec- 
tions contained  in  the  original  milk  from  which  they  are  prepared.  It  is 
known  that  tubercle  bacilli  pass  into  butter  and  may  live  there  for 
months.  It  has  also  been  demonstrated  that  infected  cream  may  be 
the  cause  of  typhoid  fever,  septic  sore  throat,  and  without  doubt  diph- 
theria, scarlet  fever,  and  other  milk-borne  diseases. 

^lilk  products  are  often  made  from  milk  that  is  left  over  or  otherwise 
unsalable.    This  should  be  controlled  by  an  efficient  system  of  inspection. 

The  infections  in  fresh  milk  products  may  be  guarded  against  by 
pasteurization.  It  is  comparatively  easy  to  pasteurize  cream,  for  the 
reason  that  it  may  be  heated  to  a  higher  temperature  than  is  the  case 
with  milk  without  materially  altering  its  physical  properties. 

Butter. — Butter  is  made  by  churning  "gravity"  cream  or  "separator" 
cream.  The  cream  may  be  fresh,  but  is  usually  ripened,  that  is,  partially 
sour  before  it  is  made  into  butter.     Special  cultures  of  microorganisms 


786  ANIMAL  FOODS:    MILK 

("starters")  are  sometimes  added  to  ripen  the  cream  for  the  purpose 
of  giving  the  butter  a  particular  flavor.  Butter  is  also  made  from 
homogenized  milk  fat. 

.  Butter  is  usually  "scored"  in  accordance  with  a  score  card  proposed 
by  Woll  in  which  45  points  are  allowed  for  flavor,  25  for  grain  (body), 
15  for  color,  10  for  salt,  and  5  for  packing.  The  amount  of  fat  con- 
tained in  butter  may  be  determined  by  the  Doran  method  which  is 
accurate  to  within  one-half  per  cent.  Warm  the  butter  to  40°  C,  stir 
thoroughly,  add  about  10  c.c.  of  the  sample  into  a  graduated  sedimenta- 
tion tube,  and  whirl  in  the  centrifuge  for  a  few  seconds;  measure,  and 
record.  Now  add  about  5  c.c.  of  gasoline;  mix,  and  whirl  again  for 
15  or  20  seconds.  The  gasoline  dissolves  the  fat  which  rises.  The  non- 
fat portion  sinks  to  the  bottom.  The  latter  is  measured  and  the  differ- 
ence represents  the  amount  of  fat.  The  United  States  regulations  re- 
quire that  butter  shall  not  contain  less  than  82.5  per  cent,  of  milk- 
fat,  and  a  renovated  butter  shall  not  contain  more  than  16  per  cent, 
of  moisture. 

Natural  butter  has  a  refractometer  index  at  40°  C,  ranging  from 
1.4531  to  1.4562,  usually  about  1.4553.  The  presence  of  other  fats  that 
have  been  mixed  with  the  butter  may  readily  be  determined  by  a  higher 
refractometer  reading.  Coloring  matter  is  often  added  to  butter.  The 
presence  of  coloring  matter  may  be  detected  by  dissolving  the  fat  in 
ether  and  adding  to  separate  portions  dilute  hydrochloric  acid  and 
sodium  hydroxid.  The  first  demonstrates  the  presejice  of  the  azo  dyes, 
the  second,  the  vegetable  dyes. 

Butter  turns  acid  and  rancid  in  time,  owing  to  the  conversion  of  the 
fat  into  fatty  acids.  Eancid  butter  may  be  renovated  by  washing  it  with 
skim  milk  or  with  water  to  which  bicarbonate  of  soda  or  lime  is  some- 
times added  to  neutralize  the  acidity.  There  is  no  particular  health  objec- 
tion to  these  processes  provided  such  butter  is  sold  as  renovated  butter. 

Fresh  butter  contains  a  great  number  of  microorganisms  (millions 
per  gram).  The  total  bacterial  count  diminishes  with  time.  There 
may  be  a  reduction  of  85  per  cent,  in  two  weeks,  and  93  per  cent,  in 
four  weeks.  Butter  may  contain  tubercle  bacilli,  typhoid,  and  other 
pathogenic  bacilli.  Of  21  samples  of  market  butter  examined  in.  Bos- 
ton,^^  two  of  them  were  found  to  contain  tubercle  bacilli,  being  9.5  per 
cent,  of  the  samples  examined.  On  account  of  this  danger  butter  should 
always  be  made  from  pasteurized  cream  and  labeled  "butter  made  from 
pasteurized  cream,"  not  "pasteurized  butter." 

Petri  examined  102  samples  of  butter  at  Berlin,  using  408  animals  for 
inoculation;  16.7  per  cent,  contained  tubercle  bacilli.  Korn  found  23.5 
per  cent,  of  17  samples  of  butter  at  Freiberg  to  contain  tubercle  bacilli. 

"Rosenau,  Frost  and  Bryant,  Jour,  of  Med.  Res.,  XXX,  No.  1,  p.  69,  March, 
1914. 


.MII,K    I'K'ODrCTS  787 

The  frequency  witli  which  tubercle  bacilli  are  found  iii  butter  is 
shown  in  a  table  collected  by  Swithinbank  and  Newman.^*"  Of  498  sam- 
ples tested  from  different  sources,  7G,  or  15.2  per  cent.,  contained  tubercle 
bacilli. 

Schroeder  and  Cotton  ^^  have  found  that  living  tubercle  bacilli  will 
retain  their  infective  properties  for  at  least  160  days  in  salted  butter 
when  kept  without  ice  in  a  house  cellar. 

Butter  may  also  convey  typhoid  bacilli  and  other  pathogenic  micro- 
organisms. 

Oleomargarine  is  a  mixture  of  various  animal  and  vegetable  fats 
and  oils  otherwise  used  as  food  products,  therefore  the  o1)jections  to  the 
use  of  oleomargarine  are  more  on  the  grounds  of  fraud  and  deception 
than  in  regard  to  nutritive  value  or  sanitary  significance.  The  fraud 
consists  in  selling  oleomargarine  as  butter. 

Oleomargarine  made  of  vegetable  oils  does  not  contain  growth  pro- 
moting vitamins,  whereas  most  animal  fats,  except  lard,  do.  The  better 
grades  of  oleomargarine  contain  some  milk  fat. 

In  the  United  States  the  manufacture  of  oleomargarine  can  take  place 
only  under  the  supervision  of  the  internal  revenue  bureau :  all  oleomar- 
garine artificially  colored  to  resemble  butter  pays  an  internal  revenue 
tax  of  10  cents  per  pound;  uncolored,  14  of  a  cent  per  pound.  During 
the  fiscal  year  ending  June  30,  1910,  the  quantity  of  colored  oleomar- 
garine manufactured  in  United  States  amounted  to  3,491,978  pounds; 
and  uncolored,  85,164,655  pounds.  For  coloring  matter  anilin  dyes 
are  usually  preferred  to  annatto  or  saffron. 

Oleomargarine  consists  of  a  mixture  of  neutral  lard,  beef  fat,  and 
cotton-seed  oil  which  are  usually  churned  with  milk  in  order  to  give  a 
flavor  of  butter  to  the  product.  The  yolk  of  eggs  and  other  substances 
are  sometimes  added.  In  the  manufacture  of  oleomargarine,  fat  from 
the  mesentery  and  mediastinum  is  said  to  be  sometimes  employed,  and 
this  fat  often  contains  tuberculous  glands.  The  milk  used  may  also 
contain  tubercle  bacilli.  Morgenroth  examined  20  samples  of  oleomar- 
garine, some  of  which  were  of  the  cheap  variety  and  some  expensive. 
In  9  specimens  tubercle  bacilli  were  found. 

Test  to  Distingimli  Butter  from  Oleomargarine. — Place  a  piece  of 
the  sample,  about  the  size  of  a  small  chestnut,  in  an  ordinary  tablespoon. 
In  the  laboratory  a  small  dish  or  test  tube  may  be  used.  Heat  over  a 
flame,  first  melting  the  sample  to  be  tested,  hastening  the  process  by 
stirring  with  a  splinter  of  wood  (a  match-stick).  AMien  melted,  increase 
the  heat,  bring  to  a  brisk  boil,  and  after  the  boiling  has  begun  stir 
thoroughly,  not  neglecting  the  outer  edges. 

Oleomargarine  and  renovated   butter  boil  noisily,   sputter  more  or 

^^"Bacteriology  of  Milk,"  p.  221. 

^Bureau  of  Animal  Industry  Cir.  Xo.  153,  p.  38. 


788  ANIMAL  FOODS :    MILK 

less  like  a  mixture  of  grease  and  water  when  boiling,  and  produce  no 
foam,  or  very  little.  Renovated  butter  produces  usually  a  very  small 
amount.  On  the  other  hand,  genuine  butter  boils  usually  with  less  noise 
and  produces  an  abundance  of  foam. 

The  refractometer  reading  gives  a  more  accurate  test.     See  page  805. 

Inspection. — An  efficient  inspection  service  is  a  preventive  measure 
that  strikes  at  the  root  of  the  milk  problem.  A  good  inspection  service 
is  expensive,  but  is  worth  its  cost  in  providing  cleaner  and  better  milk. 
Inspection  has  its  limitations,  for  it  cannot  see  bacillus  carriers,  mild 
cases  of  disease,  and  cannot  be  on  hand  at  all  places  at  all  times.  No 
system  of  inspection  can  be  so  perfect  as  to  insure  milk  free  from  in- 
fection. 

A  competent  system  of  inspection  will  hel]?  the  farmer  very  much 
with  his  problems,  and  the  educational  value  of  such  a  system  is  one 
of  its  best  features.  The  score-card  system  is  an  essential  element  in 
a  successful  inspection  service. 

The  score  card  should  be  used  in  inspecting  dairies,  but  dairy 
scores  may  not  correspond  to  milk  grades  as  determined  by  bacteriologic 
tests.  The  score  card  has  advantages  and  limitations.  It  scores  clean- 
liness and  decency,  but  cannot  score  intelligence  and  conscientiousness. 
It  should  take  equipment  as  well  as  methods  into  account.  The  system 
of  scoring  is  instructive.  It  may  serve  as  a  basis  of  grading  and 
licensing. 

Inspection  is  particularly  helpful  in  tracing  the  source  of  infected 
milk  and  preventing  recurrences.  Another  important  element  in  any 
inspection  system  is  the  license  or  permit.  All  persons  producing  or 
handling  milk  should  obtain  a  license,  which  should  be  issued  only 
after  the  person  has  demonstrated  his  capacity  to  handle  milk  in  a  safe 
and  cleanly  manner.  The  license  should  be  renewed  at  least  once 
every  year. 

Pasteurization. — Pasteurization  as  applied  to  milk  consists  in  heating 
it  for  a  short  period  of  time  at  a  temperatvire  below  the  boiling  point, 
followed  by  rapid  chilling.  In  the  language  of  the  kitchen,  pasteuriza- 
tion means  parboiling.  To  the  sanitarian  pasteurization  has  but  one 
object,  viz.,  the  destruction  of  pathogenic  bacteria. 

Milk  heated  to  60°  C.  and  held  at  that  temperature  for  20  minutes 
will  kill  the  viruses  of  tuberculosis,  typhoid  fever,  scarlet  fever,  diph- 
theria, malta  fever,  dysentery,  foot-and-mouth  disease;  this  time  and 
temperature  will  also  kill  streptococci,  staphylococci,  and  practically  all 
non-spore-bearing  microorganisms  pathogenic  for  man.^"  To  provide  a 
factor  of  safety  it  is  advisable  in  commercial  practice  to  heat  milk  to 

^°De  Jong  and  De  Graef  (quoted  by  Eullman,  CentralU.  f.  Bakteriol.,  Part 
2,  1914,  XLI,  269)  have  described  seven  strains  of  B.  coli  which  survive  65° 
to  67°  C.  for  30  minutes  in  milk  or  broth.  These  strains  would  not  be  killed 
by  the  degree  of  heat  commonly  used  in  pasteurization  and  in  consequence  the 


MILK  PRODrCTS  789 

65°    C.    for    a    period    of    30    or    45    minutes.      The    Commission    on 
Milk  Standards  of  the  Xew  York  Milk  Committee  recommend : 

''That  pasteurization  of  milk  should  be  between  the  limits  of  140°  F. 
and  155°  F.  At  140°  F.  the  minimum  exposure  should  be  20  minutes. 
For  every  degree  above  140°  F.  the  time  may  be  reduced  by  1  minute. 
In  no  case  should  the  exposure  be  for  less  than  5  minutes." 

In  order  to  allow  a  margin  of  safety  under  commercial  conditions; 
the  commission  recommends  that  the  minimum  temperature  during 
the  period  of  holding  should  be  made  145°  F.  and  the  holding  tiftie 
20  minutes. 

Heating  milk  to  this  temperature  does  not  alter  its  taste,  odor,  or 
digestibility,  does  not  interfere  with  its  food  value,  and  has  the  great 
advantage  of  jireveuting  much  sickness  and  saving  many  lives. 

Pasteurization  is  not  the  ideal,  but  only  an  expedient.  It  is  the 
simplest,  cheapest,  least  objectionable,  and  most  trustworthy  method  of 
rendering  infected  milk  safe.  Pasteurization,  however,  cannot  atone 
for  filth  and  should  not  be  used  as  a  redemption  process.  A  pure  milk 
is  better  than  a  purified  milk;  however,  no  one  should  drink  raw  milk 
that  cannot  be  guaranteed  b}'  the  health  officer  as  safe  and  free  from 
danger.  Only  certified  milk  or  milk  of  equally  high  character  can  be 
regarded  as  reasonably  safe  without  pasteurization.  Less  than  1  per 
cent,  of  all  the  milk  found  upon  the  market  comes  within  the  honor  class. 
Furthermore,  even  certified  milk  has  been  responsible  for  outbreaks 
of  diphtheria,  etc. 

Pasteurized  milk  must  be  handled  at  least  as  carefully  as  raw  milk. 
It  should  be  bottled  by  machinery  immediately  following  the  process, 
kept  cold,  and  delivered  promptly.  Pasteurized  milk  sours  as  a  result 
of  acid  fermentation,  just  as  raw  milk  does.  In  other  words,  the  tem- 
peratures recommended  do  not  destroy  ''^nature's  danger  signal" — the 
lactic  acid  bacteria. ^^ 

Pasteurization  is  not  proposed  as  a  substitute  for  inspection,  but 
as  an  adjunct  to  inspection.  Inspection  gives  us  cleaner  and  better,  but 
not  necessarily  safe,  milk.  Pasteurization  destroys  the  dangers  inspec- 
tion cannot  see.  The  combination  of  inspection  and  pasteurization 
corresponds  in  all  respects  to  modern  methods  of  obtaining  a  safe  water 
supply  for  a  large  city.  The  watershed,  through  inspection,  is  kept 
clean,  but  the  water  is  filtered  or  purified  before  it  is  given  to  the  con- 
sumer. 

There  can  he  no  more  objection  to  the  heating  of  milk  for  the  use 

of  adults  and  children  above  the  age  of  three  years  than  there  is  to  the 

presence  of  B.  coli  in  pasteurized  milk  can  no  longer  be  taken  as  an  index  of 
improper  pasteurization  or  subsequent  contamination. 

^Nature  has  no  danger  signal  for  infected  milk.  Pathogenic  microorgan- 
isms do  not  alter  the  taste,  odor  or  appearance  of  milk. 


790 


ANIMAL  FOODS:    MILK 


cooking  of  meat.  Infants  should  receive  breast  milk.  When  this  is 
not  possible  they  should  have  the  best,  freshest  cow's  milk  that  can  be 
obtained.  Whether  such  milk  is  to  be  pasteurized,  modified,  or  other- 
wise treated  will  vary  with  circumstances. 

Much  has  been  said  concerning  the  relation  of  scurvy  and  rickets 
to  pasteurized  milk.  Fresh  raw  milk  has  antiscorbutic  properties, 
which,  however,  are  not  very  active.  The  amount  of  antiscorbutic 
vitamin  in  milk  varies  with  the  feed  of  the  cow    (page  672).     This.. 

vitamin  deteriorates  with 
age,  with  heating,  and 
with  drying.  The  temper- 
ature of  pasteurization 
reduces  the  antiscorbutic 
property  of  fresh  milk 
about  half.  Pasteuriza- 
tion probably  has  less  in- 
fluence than  staleness.  In 
any  case,  babies  raised  on 
cow's  milk  should  have  an 
antiscorbutic  accessory,  as 
orange  juice.  The  disease 
is  readily  preventable. 
Rickets  is  a  disease  of 
defective  alimentation, 
which  cannot  be  laid  to 
the  door  of  pasteurization. 
Pediatricians  now  almost 
unanimously  recommend 
pasteurization,  particu- 
larly in  the  summer  time, 
especially  for  those  in- 
fants who  must  depend  upon  ordinary  market  milk  or  milk  of  un- 
known quality. 

Pasteurization  is  too  important  a  public  health  measure  to  leave  to 
individual  caprice.  The  process  should  be  under  official  supervision. 
Further,  pasteurized  milk  should  be  labeled  as  such  or  simply  "Iieated 
milk,"  stating  the  degree  of  heat  and  the  length  of  time,  and  the  date 
on  which  the  process  was  done. 

Pasteurization  is  sometimes  objected  to  because  it  does  not  destroy 
heat-resisting  toxins  which  are  supposed  to  be  in  milk.  The  occurrence 
of  such  poisons  is  a  mere  assumption.  Even  if  they  exist  in  milk  they 
would  be  in  the  raw  milk  as  Avell  as  in  the  heated  milk.  The  true  exo- 
toxins are  all  killed  at  60°  C.  for  20  minutes. 

Theoretically  the  best  place  to  pasteiirize  milk  is  in  the  home.    Prac- 


FiG.   80. — Automatic   Tehpebature    Recordeb 
FOB  Pasteurizers. 


MILK  iM.'oDrcrs  :;)! 

iicallv  the  best  ])l;ic('  is  at  soiiu'  central   slalioii,  wlici'c  it   may  Ijc'  done 
scientificalh'  umlei-  ollieial  sni'veillaiice. 

Methods  of  i'asleurization. — 'I'here  are  tlireo  well-known  methods 
by  which  milk  may  be  pasteurized:  (1)  the  flash  method;  (2)  the 
holding  method;  {'A)  in  the  final  container. 

The  fash  melltod  consists  of  heating  the  milk  momentarily  to  a 
temperature  of  about  178°  F.  (81°  C.)  and  chilling  at  onc6.  This 
method  is  sometimes  incorrectly  called  "commercial"  pasteurization.  It 
does  not  give  uniform  results,  is  not  entirely  reliable,  and  does  not  meet 
with  the  approval  of  the  sanitarian.  The  method,  however,  is  rapid 
and  cheap. 

The  holding  method  consists  in  heating  the  milk  to  the  desired 
temperature,  say  65°  C,  and  then  holding  it  in  a  suitable  tank  or  series 
of  tanks  at  that  temperature  for  a  given  period  of  time,  say  30  or  45 
minutes.  This  method  has  proved  satisfactory  in  practice  under  com- 
mercial conditions. 

Pasteurization  in  the  final  container  is  the  perfection  of  the  art.  It 
is  the  ideal  method,  because  the  danger,  how^ever  slight,  of  recontamina- 
tion  is  entirely  eliminated.  In  order  to  pasteurize  milk  in  bottles  the 
bottles  must  be  well  sealed  with  a  tight  cork  and  cap,  or  equally  effective 
stopper.  The  bottles  containing  the  milk  may  either  be  immersed  in 
a  water  batl/,  brought  to  the  proper  temperature,  held  there  a  sufficient 
length  of  time,  and  then  chilled ;  or  the  methods  used  in  beer  pasteuriza- 
tion, such  as  the  Loew  pasteurizers,  may  be  used.  In  this  case  the 
bottles  are  subjected  to  a  spray  or  shower  of  heated  water. 

Pasteurization  in  the  bottle  is  especially  applicable  to  small  dealers 
who  cannot  afford  automatic  bottling  and  capping  machines. 

Freeman's  pasteurizer  for  heating  milk  in  individual  feeding  bottles 
in  the  home  is  most  serviceable.  The  modification  of  ]\Ir.  Xathan  Straus 
is  shown  in  Fig.  81.     It  is  used  as  follow's: 

After  the  bottles  have  been  thoroughly  cleaned  they  are  placed  in 
the  tray  (A)  and  filled  with  the  milk  or  mixture  used  for  one  feeding. 
Then  put  on  the  corks  or  patented  stoppers  without  fastening  them 
tightly. 

The  pot  (B)  is  now^  placed  on  the  wooden  surface  of  the  table  or 
floor  and  filled  to  the  supports  (C)  with  boiling  water.  Place  the  tray 
(A)  with  filled  bottles  into  the  pot  (B)  so  that  the  bottom  of  the  tray 
rests  on  the  supports  (C),  and  put  cover  (D)  on  quickly. 

After  the  bottles  have  been  warmed  up  by  the  steam  for  five  minutes, 
remove  the  cover  quickly,  turn  the  tray  so  that  it  drops  into  the  water, 
replace  the  cover  immediately.  This  manipulation  is  to  be  made  as 
rapidly  as  possible  to  avoid  loss  of  heat.  Thus  it  remains  for  twenty- 
five  minutes. 

ISTow  take  the  tray  out  of  the  water  and  fasten  the  corks  or  stop- 


792 


ANIMAL  FOODS:    MILK 


pers  air-tight.  Cool  the  bottles  with  cold  water  and  ice  as  quickly  as 
possible,  and  keep  them  at  this  low  temperature  until  used. 

Use  the  milk  from  the  bottles  and  by  no  means  pour  it  into  an- 
other vessel. 

The  milk  should  not  be '  used  for  children  later  than  twenty-four 
hours  after  pasteurization. 

Emphasis  is  laid  on  the  fact  that  only  fresh,  clean  milk,  which  has 
been  kept  cold,  should  be  used. 

The  Effect  of  Heat  upon  Milk. — The  changes  produced  in  milk  by 
heating  depend  upon  the  degree  of  heat  and  the  length  of  exposure. 


Fig.  81. — Straus  Home  Pasteurizer. 


Milk  heated  at  62.8°  C.  for  30  minutes  does  not  undergo  any  appreciable 
chemical  and  physical  change.  The  boiling  of  milk,  however,  pro- 
duces pronounced  changes.  In  the  main,  these  consist  of  a  partial  de- 
composition, of  the  proteins  and  other  complex  nitrogenous  derivatives; 
diminution  of  the  organic  phosphorus  and  an  increase  of  inorganic  phos- 
phorus ;  precipitation  of  the  calcium  and  magnesium  salts  and  the  greater 
part  of  the  phosphates;  expulsion  of  the  greater  part  of  the  carbon 
dioxid ;  caramelization  or  burning  of  a  certain  portion  of  the  milk  sugar, 
causing  the  brownish  color;  partial  disarrangement  of  the  normal  emul- 
sion, and  coalescence  of  some  of  the  fat  globules;  coagulation  of  the 
serum  albumin,  which  begins  at  75°  C. ;  the  ferments  are  killed. 

Boiled  milk  has  a  cooked  taste  which  appears  at  about  70°  C.  This 
is  due  perhaps  to  the  decomposition  of  certain  of  the  proteins  in  the 
milk.    The  loss  of  certain  gases  also  alters  the  taste,  so  that  milk  heated 


MII.K    IMiM)I)r(TS  793 

in  closed  vessels  has  a   li'ss   pniiioniiccd    llavor  than   if  healed    in   ojxmi 
vessels. 

Milk  heated  in  th<>  open  air  I'onns  a  pellieh'  whii-ji  renews  if  it  is 
ronioYod.  'i'liis  scum  forms  \\hen  iiiilk  reaches  ahoiit  (10°  ('.  It  con- 
sists of: 

Casein  and  albuminoid 50.80  per  cent. 

Fatty   matter 45.42  per  cent. 

Ash    3.72  per  cent. 

Milk  heated  in  closed  vessels  does  not  form  a  pellicle,  even  when 
the  temperature  reaches  the  boiling  point.  It  seems  that  this  pellicle 
is  due  mainly  to  the  drying  of  the  upper  layer  of  the  liquid. 

After  milk  has  been  heated  to  68°  C.  or  over  for  half  an  hour,  the 
cream  does  not  rise  well,  if  at  all,  owing  to  the  increase  in  the  vis- 
cosity of  the  fluid  in  which  it  is  emulsified.  The  clusters  of  fat  drop- 
lets which  are  agglutinated  into  masses  in  normal  milk  are  broken  down 
by  heating,  and  the  globules  are  more  homogeneously  distributed 
throughout  the  fluid. 

It  has  been  observed  that  cooked  milk  coagulates  with  rennin  more 
slowly  than  raw  milk.  This  effect  is  noted  often  at  temperatures  of 
80°  to  90°  C,  but  has  not  been  observed  in  milk  heated  to  60°  C.  for 
20  minutes.  The  curd  produced  by  rennin  coagulation  in  cooked  milk 
is  softer,  less  tough,  and  more  flocculent  than  that  produced  by  rennin 
coagulation  in  raw  milk.  This  is  believed  to  be  an  advantage  favor- 
ing the  digestibility  of  heated  milk.  Cooked  milk  is  said  to  be  con- 
stipating. This  is  explained  by  the  fact  that  cooked  milk  contains 
comparatively  few  bacteria  and  is,  therefore,  less  irritating  than  raw 
milk. 

Methods  for  detecting  heated  milk  see  page  808. 

The  Essential  Requirements  for  a  Safe  and  Satisfactory  Milk  Sup- 
ply.— 1.  Cows  should  be  healthy  and  free  especially  from  communica- 
ble infections,  or  any  febrile  disease,  or  inflammatory  condition  of  the 
udder. 

2.  All  persons  who  in  any  way  come  in  contact  with  the  milk  or 
milk  apparatus  should  be  free  from  communicable  diseases  and  not  be 
carriers.     A  minimum  of  human  contact  should  be  insisted  upon. 

3.  The  milking  should  be  done  in  clean  rooms,  the  udders  washed; 
the  hands  of  the  milker  should  be  clean  and  dry. 

4.  The  milk  should  be  received  into  clean,  sterilized  pails,  with  a 
small  mouth  so  as  to  keep  out  dust  and  dirt  which  falls  from  the  udder 
and  belly  of  the  cow.  If  strainers  are  used  they  should  be  cleaned  or 
boiled  morning  and  evening.  Cans  and  pails  should  be  cleaned  with 
washing  soda  or  alkaline  powder  (not  soap),  rinsed  in  clean  water,  and 
then  steamed  or  boiled. 


794  ANIMAL  FOODS:    MILK 

5.  The  milk  should  be  chilled  to  50°  F.  or  under  at  once,  and  kept 
protected  from  flies,  dust,  odors,  and  contamination,  in  a  clean  milk 
house  until  collected.  A  wooden  paddle  should  not  be  used  to  stir  the 
milk.     If  stirred  a  metal  paddle  is  preferable. 

6.  The  milk  should  likewise  be  kept  protected  and  cold,  not  higher 
than  50°  F.,  in  transit  to  the  city,  and  protected  against  tampering  en 
route.  The  lower  the  temperature  the  easier  it  will  be  to  keep  the 
bacterial  count  down. 

7.  All  apparatus  at  the  city  dairy,  such  as  tanks,  clarifiers,  separa- 
tors, pasteurizers,  and  bottling  machines,  should  be  kept  scrupulously 
clean  and  sterilized  by  steam. 

8.  Pasteurization  at  not  less  than  60°  for  20  minutes,  followed  by 
rapid  chilling,  and  the  milk  kept  below  50°  F.  until  delivered  to  the 
consumer. 

9.  The  pasteurized  milk  to  be  bottled  by  machinery  in  sterilized  bot- 
tles, well  sealed;  and  delivered  promptly  to  the  consumer. 

10.  All  bottles  and  cans,  after  use  in  city  delivery,  should  be  washed 
and  sterilized  before  being  returned  to  the  producer  in  order  to  prevent 
the  conveyance  of  infection  to  the  dairy  or  country  farm. 

11.  The  milk  must  be  graded.  In  this  way  the  producer  is  paid 
for  care  and  cleanliness  and  the  consumer  has  a  ready  means  of  knowing 
the  sanitary  character  of  the  milk  he  purchases.  The  health  ofl&cer 
should  make  frequent  bacterial  counts,  and  also  sanitary  surveys,  for 
the  purpose  of  grading. 

12.  A  sanitary  code  based  upon  good  milk  laws.  The  system  should 
include  milk  products. 

13.  A  system  of  licensure  and  inspection  to  insure  the  above  re- 
quirements. 


THE  BACTERIOLOGICAL  EXAMINATION  OF  MILK 

The  Number  of  Bacteria. — No  known  method  can  give  an  enumera- 
tion of  all  the  bacteria  in  milk.  Some  are  aerobes,  others  anaerobes ; 
some  require  alkaline,  others  acid  media;  some  grow  best  at  room  tem- 
perature, others  only  at  blood  temperature;  and  some  grow  slowly  or 
not  at  all  upon  ordinary  media.  The  methods  in  use,  therefore,  are 
those  which  have  been  shown  by  experiments  to  give  the  highest  counts 
and  the  maximum  information  under  ordinary  conditions. 

For  the  sake  of  uniformity  methods  should  follow  the  report  of 
the  Committee  on  Standard  Methods  of  Bacterial  Milk  Analysis  of  the 
American  Public  Health  Association.^^ 

The  samples  must  be  collected  and  kept  in  such  a  manner  as  to 

^^  American  Journal  of  Public  Health,  Vol.  VI,  No.  12,  Dec,  1916. 


THE  BAOTERIOUHUOAL  EXAMIXATTON  OF  MILK    795 

prevent  eitlicr  any  addition  ol"  liactt'riu  Troin  \vitli(jut  or  multiplication 
of  the  bacteria  originally  present.  Whenever  possible,  and  especially 
in  the  selection  of  certified  milk  samples,  an  original  package  should  be 
taken,  placed  in  a  suitably  iced  case,  and  brought  at'  once  to  the  labora- 
tory. Samples  of  market  milk  may  be  collected  in  the  same  manner  as 
water  samples,  in  sterile,  wide-mouthed,  glass-stoppered  four-ounce  bot- 
tles. Care  should  be  taken  to  secure  a  sample  which  is  thoroughly  repre- 
sentative of  the  milk  to  be  examined.  This  may  be  done  by  pouring  the 
milk  back  and  forth  into  a  sterile  receptacle,  or  shaking  the  milk  thor- 
oughly with  the  receptacle  turned  upside  down.  In  taking  samples 
from  tanks  it  is  allowable  to  stir  thoroughly  with  a  long-handled  dipper. 
Generally  speaking,  the  shorter  the  time  between  collection  and  examina- 
tion of  milk  samples  the  more  accurate  will  be  the  results.  Eor  routine 
work  the  attempts  should  be  made  to  plate  within  four  hours  of  the 
time  of  collection.  Too  much  stress  cannot  be  laid  on  the  importance 
of  keeping  the  samples  properly  iced  during  this  interval.  They  should 
be  kept  below  40°  F..  but  care  should  be  taken  that  they  are  not  frozen. 

The  standard  medium  for  routine  enumeration  of  bacteria  in  milk 
is  Standard  Beef  extract  agar  -^  adjusted  according  to  Fuller's  scale. 
The  reaction  is  not  to  be  changed  if  it  falls  between  +0.5  and  +1.0  per 
cent.  Milk  should  always  be  diluted  before  plating,  for  the  reason  that 
whole  milk  produces  a  turbidity  of  the  agar,  and  because  the  bacteria 
cannot  well  be  dispersed  without  diluting,  and  the  resulting  colonies 
are  so  close  that  they  interfere  with  each  other.  The  milk  is  diluted 
in  the  proportion  of  1-10,  1-100,  1-1,000,  1-10,000,  1-100,000  or 
1-1,000,000.  For  certified  milk  1-100  dilution  should  be  used.  Or- 
dinary potable  water,  sterilized,  may  be  used  for  dilutions.  The  number 
of  bacteria  present  may  be  estimated  approximately  before  dilutions 
are  made  by  direct  microscopic  examination  of  a  properly  prepared 
sediment.  Otherwise  it  is  necessary  to  make  a  range  of  dilutions  there- 
from, selecting  for  record  the  count  obtained  on  that  plate  which 
yields  between  30  and  300  colonies.  A  plate  containing  more  or  less 
than  these  numbers  will  not  give  reliable  results.  Porous,  earthenware 
Petri  dish  covers  are  recommended  as  superior  to  glass,  since  they 
absorb  the  excess  of  moisture  and  thus  help  to  prevent  spreaders.  An- 
other method  of  preventing  spreaders  is  to  invert  the  dishes  and  place 
in  the  glass  cover  of  each  a  strip  of  sterile  filter  paper  moistened  with 
one  large  drop  of  glycerin. 

The  plating  should  always  be  checked  by  duplicate  controls,  and 
a  blank  plate  should  be  made  with  each  series  for  control  of  the  steril- 
ity of  the  agar,  water,  air,  Petri  dishes,  pipettes,  and  methods.  The 
plates  should  be  incubated  at  37°  C.  for  48  hours,  or  may  be  grown  at 

^^sculin  bile  salt  agar,  lactose  litmus  agar,  and  whey  agar  may  also 
be  used. 


796  ANIMAL  FOODS:    MILK 

21°  C.  for  five  days.  Only  those  colonies  should  be  counted  which  are 
visible  to  the  naked  eye  or  may  be  seen  readily  by  a  low  power  lens.^* 
The  result  should  always  be  expressed  in  round  numbers.  It  is  mis- 
leading to  state  that  a  milk  contains  2,140,672  bacteria  per  cubic 
centimeter.  This  gives  a  false  and  exaggerated  notion  of  the  accuracy 
of  the  method.  At  best  the  results  are  only  an  average  approxima- 
tion. Eestlts  should  be  expressed  in  accordance  with  the  recommenda- 
tions of  the  Commission  on  Standards  of  the  New  York  Milk  Com- 
mittee.^^ 

The  number  of  bacteria  is  the  best  single  index  we  have  of  the 
general  character  of  milk. 

The  Kinds  of  Bacteria. — We  still  lack  satisfactory  routine  methods 
for  determining  the  kinds  of  bacteria  found  in  milk.  If  the  plates  are 
made  with  gelatin  it  will  give  the  relative  proportion  of  liquefiers.  By 
the  use  of  Endo's  medium  or  lactose  litmus  agar  the  number  of  acid- 
producing  bacteria  may  be  determined. 

To  determine  the  number  of  proteolytic  bacteria  in  milk  place  1  c.c. 
of  sterile  skim  milk  into  a  Petri  dish,  then  add  the  proper  dilution  of 
milk  in  question,  and  finally  pour  in  molten  sugar-free  agar.  Incubate 
48  hours,  and  then  wash  the  surface  with  a  dilute  solution  of  acetic  acid. 
Count  the  number  of  colonies  surrounded  by  a  clear  zone,  which  is  taken 
to  represent  proteolysis  or  breaking  down  of  the  protein.-*' 

Typhoid  bacilli  may  be  isolated  on  Endo's  medium,  and  diphtheria 
upon  Loeffler's  blood  serum.  Other  pathogens  require  special  technic 
applicable  to  each  case.  The  number  of  streptococci  in  milk  may  be 
estimated  by  the  direct  examination  of  stained  smears.  The  chains  are 
more  readily  counted  if  the  milk  is  first  incubated"  at  37°  C.  for  6  or  8 
hours.  In  the  estimation  of  streptococci  only  the  longer  chains  are  con- 
sidered. The  presence  of  streptococci  and  an  approximation  as  to  their 
number  may  also  be  determined  by  planting  the  milk  upon  the  surface 
of  blood  agar  and  studying  the  fine  dewdrop-like  colonies. 

A  few  streptococci  will  be  found  in  most  sediments  from  milk.  They 
are  seldom  found  to  any  great 'extent  by  direct  microscopic  examination 
of  clean  milk.  Occasionally  a  sample  will  be  found  crowded  with  long 
chains.  More  often  streptococci,  if  present,  are  in  the  form  of  diplococci 
or  very  short  chains.  The  common  interpretation  is  to  regard  the  short 
chain  varieties  as  probably  harmless,  while  long  chains  are  regarded  as 
more  apt  to  indicate  inflammatory  reactions.  This  is  a  serious  mis- 
take.    There  is  no  relation  between  length  of  chains  and  pathogenicity. 

Euediger  points  out  that  Streptococcus  Jacticus  can  be  differentiated 
from  Streptococcus  pyogenes  by  means  of  blood  agar  plates.     Strepto- 

^  Magnifying  2V:>  diameters. 

^'Public  Health  Reports,  Vol.  XXVII,  19,  May  10,  1912. 

''Hastings:     Cent.  f.  Bakt.  u.  Parasitenk.,  Abt.  II,  Bd.  X,  p.  384. 


MICROSCOPIC  EXAMINATION  797 

coccus  pyogenes  produces  small  colonies  surrounded  by  a  large  zone  of 
hemolysis,  whereas  Streptococcus  lacticus  produces  green  or  grayish  colo- 
nies with  very  little  or  no  hemolysis. 

Streptococcus  lacticus  has  no  sanitary  significance,  as  it  is  found  in 
nearly  all  samples  of  clean,  soured,  or  fresh  milk,  and  very  often  in 
the  healthy  milk  ducts.  Streptococcus  pyogenes,  on  the  other  hand, 
seems  to  occur  but  rarely  in  milk,  and  is  indicative  of  the  existence  of 
an  inflamed  condition  of  the  udder  of  the  cow  furnishing  the  milk. 

The  Beta  type  of  hemolytic  streptococci  described  by  Smith  and 
Brown  may  be  isolated  from  milk  by  the  method  described  on  page  781. 

The  presence  of  Bacillus  Welchii,  or  the  gas  bacillus,  may  be  de- 
termined by  heating  some  of  the  milk  to  80°  C.  for  one  hour  in  deep 
anaerobic  tubes  and  then  incubating  the  sample  at  37°  C.  If  the  sample 
contains  this  microorganism  it  will  show  "stormy  fermentation"  with 
gas  production  within  2-i  hours  (sometimes  as  soon  as  6  hours),  with 
coagulation  and  breaking  up  of  the  curd,  some  of  which  may  be  forced 
above  the  cream  line,  and  with  the  development  of  an  odor  of  butyric 
acid. 

The  demonstration  of  tubercle  bacilli  in  milk  depends  upon  animal 
experimentation.     See  page  779. 


MICROSCOPIC  EXAMINATION 

There  are  three  methods  of  making  a  microscopic  examination  of 
milk  in  current  use.  These  are  convenient  and  practical  methods  of 
roughly  but  quickly  determining  the  sanitary  quality  of  milk,  based 
upon  its  bacterial  content. 

(1)  The  Stewart-Slack  Method.— Two  c.c.  of  milk  are  placed  in 
a  glass  tube  closed  at  both  ends  with  a  rubber  stopper.  This  is  cen- 
trifuged  for  10  minutes  at  a  speed  of  from  2.000  to  3,000  revolutions 
per  minute.  The  sediment  upon  the  rubber  stopper  of  the  distal  end 
of  the  tube  is  mixed  with  a  drop  or  two  of  water  and  spread  upon  a 
slide  in  a  thiu;  even  layer,  covering  a  space  of  about  four  square  centi- 
meters. This  is  dried  and  stained  with  methylene  blue.  The  micro- 
scopic examination  reveals  the  character  of  the  milk  as  judged  from 
the  approximate  number  of  pus  cells  and  presence  of  streptococci  in 
long  chains.  It  has  been  found  that  the  number  of  cocci,  bacilli,  or 
chains  in  the  1/12  oil  immersion  field,  multiplied  by  10,000,  gives  a 
rough  approximation  of  the  number  of  bacteria  in  a  cubic  centimeter 
of  the  whole  milk. 

The  results  of  this  method  vary  considerably  with  details  of  indi- 
vidual manipulation,  with  the  speed  of  the  centrifugal  machine,  with 
the  time  allowed  for  centrifugation,  and  other  factors. 


798  ANIMAL  FOODS:    MILK 

(2)  The  Doane-Buckley  Method. — In  this  method  the  number  of 
leukocytes  are  counted  in  the  chamber  of  the  Zeiss  blood  counter,  which 
contains  just  0.0001  c.c.  Ten  c.c.  of  milk  is  centrifuged  at  2,000  revo- 
lutions per  minute  for  four  minutes.  The  fat  is  removed  with  a  cotton 
swab  and  again  centrifuged  for  one  minute.  The  fat  is  again  carefully 
removed,  for  any  appreciable  amount  of  fat  will  interfere  with  the  count- 
ing. The  supernatant  fluid  is  now  pipetted  off  and  two  drops  of  a  satu- 
rated alcoholic  solution  of  methylene  blue  are  added  to  the  sediment, 
which  is  thoroughly  mixed  and  warmed  in  boiling  water  for  two  or 
three  minutes,  which  favors  the  staining  of  the  cells.  The  sediment  is 
now  diluted  to  the  1  c.c.  mark  with  water.  Some  of  this  is  transferred 
to  the  counting  chamber  and  the  number  of  cells  counted  with  a  dry 
lens.  The  number  of  cells  in  the  counting  chamber  multiplied  by  1,000 
gives  the  number  per  cubic  centimeter  in  the  milk. 

(3)  The  Prescott-Breed  Method. — Special  pipettes  graduated  to 
hold  0.01  c.c.  of  milk  may  be  obtained  for  use  under  this  method. 
After  a  thorough  mixing  of  the  milk,  0.01  c.c.  is  removed  with  the 
pipette  and  spread  uniformly  over  a  square  centimeter  on  an  ordinary 
microscopic  slide.  It  is  allowed  to  dry  and  is  fixed  with  methyl  alcohol, 
after  which  the  fat  is  dissolved  from  it  by  the  use  of  xylol.  The  smear 
is  then  stained  either  with  methylene  blue  or  preferably  with  one  of  the 
blood  stains,  the  Jenner  stain  or  Wright  stain  being  useful  for  this 
purpose.  If  the  staining  is  so  deep  as  to  make  the  specimen  too  opaque 
for  proper  study,  it  is  slightly  decolorized  with  alcohol,  which  removes 
the  stain  from  the  general  sediment  more  readily  than  it  does  from 
the  bacteria  of  the  tissue  cells.  The  stained  smear  is  studied  under  a 
1/12  inch  immersion  lens.  The  draw  tube  is  adjusted  so  that  the 
field  of  the  microscope  covers  exactly  15  millimeters,  and  under  these 
circumstances  the  number  of  bacteria  present  in  the  0.01  c.c.  is  exactly 
5,000  times  the  number  found  in  a  microscopic  field.  The  counting  of  a 
large  number  of  fields  (100  fields)  and  averaging  the  results  multiplied 
by  this  number  will,  therefore,  give  approximiitely  the  number  of  cells 
or  bacteria  contained  in  0.01  c.c.  of  milk. 


CHEMICAL  ANALYSIS  OF  MILK 

Total  Solids.— The  total  solids  in  milk  consist  chiefly  of  the  fats, 
sugar,  proteins,  and  inorganic  salts.  The  United  States  standard  re- 
quires 12  per  cent,  of  the  milk  to  consist  of  total  solids,  8.5  per  cent, 
of  which  shall  be  solids  not  fat,  and  3.25  per  cent.  fat.  In  some  states 
the  requirement  for  total  solids  is  as  high  as  13  per  cent.,  in  others 
11.5  per  cent. 


CHEMICAL  ANALYSIS  OF  MILK  799 

Determination  of  Total  Solids. — The  total  solids  may  be  determined 
either  by : 

(1)     The  use  of  Richmond's  slide  rule. 

{'i)     The  Babcock  asbestos  method. 

(3)     By  evaporation  and  direct  weighing. 

Richmond's  Slide  Bule. — This  is  a  device  by  which  the  total  solids 
may  be  determined  fairly  accurately  by  the  use  of  the  formula  of  Hehner 
and  Eichmond.  It  is  necessary  to  know  the  correct  specific  gravity  and 
the  amount  of  fat.  From  this  the  total  solids  is  determined  by  the  fol- 
lowing formula  : 

n 

T  S=(— )+1.2  F+.U 
4 

in  which  T  S  equals  total  solids,  G  the  last  two  units  of  the  specific 
gravity  and  any  decimal.  Thus,  if  the  specific  gravity  is  1.0295,  G=: 
29.5.  F  represents  the  percentage  of  fat.  In  using  the  slide  rule  the 
operation  is  conducted  in  two  stages.  First,  the  lactometer  reading  is 
corrected  for  temperature.  The  observed  lactometer  reading  is  brought 
opposite  the  60°  mark  and  the  correct  specific  gravity  read  opposite  the 
observed  temperature.  Second,  the  arrow  of  the  slide  is  set  opposite 
the  observed  percentage  of  fat,  and  the  total  solids  are  read  off  opposite 
the  corrected  specific  gravity  reading  on  the  scale  marked  "specific 
gravity."  The  results  obtained  by  the  use  of  Eichmond's  slide  rule 
agree  quite  closely  with  those  obtained  by  direct  weighing. 

This  formula  may  also  be  used  to  determine  the  percentage  of  fat 
provided  the  specific  gravity  and  total  solids  are  known. 

Tlie  Babcocl-  Asbestos  Method. — The  milk  is  placed  upon  a  filter 
paper  cartridge  filled  loosely  with  freshly  ignited  woolly  asbestos,  sub- 
jected to  a  temperature  of  100°  C.  until  weight  is  constant,  and  then 
cooled  and  weighed.  The  gain  in  weight  represents  the  total  solids  of 
the  amount  of  milk  taken.  The  advantage  in  this  method  is  that  the 
cartridge  may  then  be  slipped  into  the  Soxhlet  extraction  apparatus  and 
used  for  the  determination  of  fat. 

Weighing. — About  5  c.c.  of  milk  are  weighed  in  a  tared  platinum 
dish,  evaporated  exactly  two  hours  on  a  steam  bath,  the  outside  wiped 
dry,  and  then  cooled  to  constant  weight  in  a  desiccator.  The  weight  of 
the  residue  represents  the  total  solids  of  the  milk. 

Determination  of  Ai^h. — The  platinum  dish  containing  the  total 
solid  residue  is  carefully  heated  in  the  flame,  avoiding  spattering  and 
heating  above  a  dull  red  glow.  When  the  residue  has  become  white,  or 
nearly  so,  it  is  cooled  in  a  desiccator  and  again  weighed;  the  difference 
between  the  final  weight  and  the  original  weight  of  the  empty  dish 
represents  the  amount  of  mineral  matter  in  the  amount  of  milk  taken. 


800  ANIMAL  FOODS:    MILK 

The  ash  is  saved  for  the  tests  for  boron  compounds,  carbonates,  and 
other  non-volatile  mineral  preservatives. 

Determination  of  Fats. — The  determination  of  the  quantity  of  butter 
fat  contained  in  milk  is  of  considerable  economic  importance  and  is 
included  as  a  routine  in  all  milk  laboratories.  There  are  several  methods 
by  which  the  fat  in  milk  may  be  accurately  determined. 

(1)  BabcocJc  Method. — The  Babcock  method  is  the  most  conven- 
ient and  is  sufficiently  accurate  for  ordinary  purposes.  It  cannot  be 
carried  out  without  considerable  special  apparatus,  including  a  cen- 
trifuge, special  graduated  flasks  and  pipettes.  The  method  consists  in 
separating  the  fat  by  the  addition  of  sulphuric  acid.  The  mixture  is 
centrifugalized  so  that  the  fat  rises  into  the  neck  of  the  specially 
graduated  flask,  and  the  percentage  may  be  read  off  directly.  The 
sample  should  be  well  mixed  by  pouring  back  and  forth  gust  before 
the  test.     The  method  is  carried  out  as  follows : 

In  the  special  graduated  flask'are  mixed: 

17.6  c.c.  milk. 

17.6  c.c.  of  sulphuric  acid   (specific  gravity  1.82-1.83). 

The  acid  must  be  run  slowly  down  the  side  of  the  flask  under  the 
imilk  and  the  whole  mixed  at  once,  without  splashing,  by  imparting  a 
rotary  motion  to  the  contents  of  the  bottle.  The  mixture  is  centrifugal- 
ized for  5  minutes;  boiling  water  is  then  added  until  the  liquid  rises  to 
the  bottom  of  the  neck  of  the  flask,  and  the  centrifugalization  is  repeated 
for  3  minutes.  Again  add  boiling  water  until  the  top  of  the  column  is 
near  but  safely  under  the  top  of  the  scale,  and  centrifugalize  a  third 
time  for  1  minute.  By  this  time  the  fat  in  the  neck  of  the  bottle  should 
be  clear,  yellow,  and  liquid.  The  length  of  the  column  of  fat  is  con- 
sidered as  extending  from  the  bottom  of  the  line  of  contact  with  the 
liquid  below  to  the  top  of  the  meniscus  above.  The  length  of  the  column 
of  fat  is  measured  by  means  of  a  pair  of  dividers,  which  are  first  ad- 
justed to  the  length  of  the  column,  then  the  percentage  is  read  by  touch- 
ing one  point  of  the  dividers  to  the  zero  mark  on  the  scale,  when 
the  upper  point  will  indicate  the  percentage  of  fat  in  the  milk.  The 
mixing  of  sulphuric  acid  with  the  milk  generates  considerable  heat, 
which  should  be  maintained,  so  that  at  the  time  of  taking  the  reading 
the  contents  of  the  bottle  register  between  55°-60°  C.  Care  should  be 
taken  to  use  none  but  authoritatively  tested  and  guaranteed  bottles. 
The  flasks  should  be  emptied  before  the  fat  cools  and  hardens. 

(2)  The  Werner-Schmidt  Method. — This  method  is  sloM^er  than 
the  Babcock,  especially  when  many  samples  are  to  be  analyzed,  but  it 
can  be  done  with  improvised  apparatus  and  readily  procurable  materials. 
Ten  c.c.  of  milk  are  added  to  10  c.c.  of  concentrated  hydrochloric  acid 


CHEMICAL  ANALYSIS  OF  MILK  801 

ill  a  50-e.c.  test  tube,  shaken,  and  boiled  until  dark  Ijrown  in  color.  The 
mixture  is  then  cooled  in  water  and  30  c.c.  of  wa.^hed  ether  added,  the 
stopper  inserted,  and  thoroughly  agitated.  When  the  two  layers  have 
separated  the  upper  layer,  containing  the  ether  and  dissolved  fat,  may  be 
withdrawn  by  means  of  a  pipette,  or  blown  out  with  the  assistance  of  a 
double  tube,  such  as  is  used  in  wash-bottles,  the  delivery  tube  extending 
into  the  ether  layer  almost  to  the  line  of  demarcation  between  the  ether 
and  the  acid-milk  mixture.  The  ether  containing  the  extracted  fat  is 
transferred  to  a  weighing  flask.  The  extraction  is  repeated  with  several 
fresh,  smaller  portions  of  ether  (about  10  c.c),  and  the  whole  of  the 
ether  used  is  collected  in  the  weighed  flask.  The  ether  is  then  distilled 
off  or  permitted  to  evaporate  at  a  low  temperature.  The  residuum  of  fat 
is  heated  to  constant  weight  in  an  air  bath,  cooled,  and  weighed.  Since 
the  milk  is  measured  and  not  weighed,  a  correction  must  be  made 
accordingly. 

Example. — Amount  of  milk  used  equals  10  c.c.  Specific  gravity  of 
sample  equals  1.029.  Weight  of  milk  used,  therefore,  equals  1.029X10, 
w^hich  equals  10,29  grams.  The  weight  of  the  fat  found  equals  0.386 
gram.  Percentage  of  the  fat  in  the  original  milk  is  determined  from 
the  following  equation : 

10.20:0.386  ::100:x 

X  =  3.75,  or  the  percentage  of  fat  in  the  original  milk. 

(3)  The  Soxhlet  Extraction  Method. — This  is  the  most  accu- 
rate method  for  determining  fats  in  milk  and  other  substances.  The 
principle  consists  in  the  complete  extraction  of  all  the  fat  by  con- 
tinuous washing  with  ether.  The  only  error  in  this  method  arises  from 
the  fact  that  substances  other  than  fats  are  soluble  in  ether  and  are  in- 
cluded in  the  weight.  This  error  in  milk  is  negligible.  The  process 
requires  a  coil  of  thick  filter  paper  free  from  substances  soluble  in  ether 
and  alcohol,  and  a  Soxhlet  extraction  apparatus.  Instead  of  the  coil 
of  filter  paper  a  specially  prepared  cartridge  of  filter  paper  which  fits 
loosely  within  the  cylinder  of  the  Soxhlet  apparatus  may  be  used.  When 
the  cartridge  is  used  it  is  best  to  plug  its  open  end  with  absorbent  cotton, 
in  order  to  prevent  the  escape  of  fine  particles  of  the  contained  sub- 
stance. 

A  definite  weight  of  milk,  about  5  grams,  is  applied  to  the  coil  of 
filter  paper  or  cartridge,  in  one  of  two  ways.  A  small  beaker  containing 
the  required  amount  is  weighed  and  the  coil  is  placed  in  it  and  kept 
there  until  nearly  the  whole  has  been  absorbed.  The  coil  is  then  care- 
fully withdrawn  and  placed,  dry  edge  downward,  upon  a  sheet  of  glass. 
The  beaker  is  then  weighed  again,  and  the  loss  in  weight,  which  repre- 
sents the  amount  of  milk  absorbed,  is  noted.     Another  method  is  to 


803  ANIMAL  FOODS:  MILK 

weigh  the  beaker  containing  the  milk  and  a  small  pipette.  The  neces- 
sary amount  of  milk  is  then  transferred  to  the  coil  with  the  pipette, 
after  which  the  weight  of  the  beaker  and  pipette  containing  the  re- 
maining milk  is  noted.  The  difference  represents  the  weight  of  the 
milk  absorbed.  The  coil  or  cartridge  is  then  dried  in  an  air  bath  at 
100°  C.  for  an  hour  or  more,  when  it  is  ready  for  insertion  into  the 
extractor. 

The  three  separate  parts  of  the  Soxhlet  extraction  apparatus,  con- 
sisting of  the  flask,  the  cylinder,  and  the  condenser,  are  joined  together 
and  mounted  upon  a  water  bath  or  an  electrically  heated  plate.  Before 
the  operation  is  begun  the  exact  weight  of  the  flask  must  be  determined. 
The  ether  is  then  added,  and  as  it  volatilizes  the  vapor  passes  upward 
through  the  side  tube  into  the  extractor,  and  thence  to  the  condenser, 
where  it  falls  upon  the  substance  to  be  extracted.  As  the  process  con- 
tinues the  condensed  liquid  accumulates  in  the  cylinder  and  gradually 
rises  until  it  reaches  the  bend  of  the  siphon  in  the  cylinder  part  of  the 
apparatus.  When  full  the  siphon  acts  and  discharges  back  into  the 
flask,  until  the  entire  liquid  is  returned  to  its  starting  point.  During 
its  accumulation  in  the  cylinder  it  dissolves  the  fats  or  other  ether 
soluble  substances  which  are  carried  in  solution  into  the  flask.  The 
process  is  continued  until  this  siphoning  action  repeats  itself  again  and 
again  as  long  as  is  necessary,  so  that  the  whole  of  the  extracted  matter 
is  finally  within  the  flask.  The  fat,  being  non-volatile,  remains  in  the 
flask  while  the  ether  is  revolatilized  and  sent  continually  on  its  errand. 
On  the  completion  of  the  process  the  ether  is  permitted  to  collect  in  the 
cylinder,  but  before  it  reaches  the  level  of  the  siphon  the  flask  is  dis- 
joined. The  remaining  ether  is  expelled  cautiously  and  the  flask  with  its 
contents  is  placed  in  an  air  bath  maintained  at  100°  C.  and  dried  to 
constant  weight.  The  increase  in  the  weight  of  the  flask  represents  the 
amount  of  matter  extracted. 

Example. — The  weight  of  milk  absorbed  by  the  filter  paper  was 
5.160  grams.  The  increase  in  the  weight  of  the  flask  was  0.161  gram, 
The  amount  of  fat  present  in  the  sample  is  then  obtained  by  the  fol- 
lowing equation: 

5.16:0.161::100:x 

X  =  3.12,  or  the  percentage  of  fat  in  the  milk. 

Determination  of  Milk  Sugar. — The  amount  of  lactose  in  milk  may 
be  determined  chemically  by  the  reduction  of  copper  sulphate  in  Fehling 
solution,  or  optically  by  means  of  the  polariscope. 

(1)  Method  hy  FeMing's  Solution. — To  35  grams  of  milk  add 
0.5  c.c.  of  30  per  cent,  acetic  acid;  shake;  let  stand  3  minutes;  then 
add  100  c.c.  of  boiling  water;  again  shake;  add  35  c.c.  of  alumina 


CHEMICAL  ANALYSIS  OF  MILK  803 

cream;  again  shake,  and  lei  stand  for  10  minutes;  filter  through  a  wet 
pleated  paper  filter  and  wash  the  residue  until  the  washings  and  filtrate 
total  250  C.C.,  representing  a  dilution  of  one-tenth  of  the  original  milk; 
this  dilutes  the  sugar  content  of  the  liquid  to  somewhat  less  than  0.5 
per  cent.  This  is  then  titrated  with  Fehling's  solution  in  the  usual 
manner,  namely:  fill  a  burette  with  sugar-containing  liquid,  place  10 
c.c.  of  Fehling's  solution  (representing  0.067  gram  of  milk  sugar)  in 
a  flask,  and  hoat  to  boiling.  l\un  in  the  liquid  i'rom  the  burette  in  small 
proportions,  maintaining  tlic  contents  of  the  flask  at  boiling  point  until 
the  liquid  in  the  flask  loses  its  original  blue  color,  which  marks  the 
end  point  of  the  reaction. 

Fehling's  solution  is  made  up  in  two  solutions:  1.  Dissolve  34.639 
grams  of  CuSO^.SHoO  in  distilled  water  and  dilute  it  to  a  liter. 
2.  Dissolve  173  grams  of  potassium  sodium  tartrate  (Eochelle  salt) 
in  distilled  water,  add  100  c.c.  of  sodium  hydrate  solution  of  1.393 
specific  gravity,  and  dilute  the  mixture  with  distilled  water  to  a  liter. 
Equal  parts  of  solution  1  and  2  are  mixed  in  a  boiling  flask  of  about 
300  c.c.  capacity.  The  amount  of  copper  contained  in  10  c.c.  of  equal 
parts  of  solution  1  and  2  requires  for  its  reduction  0.050  gram  of  dex- 
trose, or  0.067  gram  of  lactose. 

(2)  Polariscope  Method. — The  polariscope,  the  quantities  used,  and 
the  factors  employed  in  the  polariscope  method  vary  with  different  types 
of  instruments.  Perhaps  the  most  satisfactory  is  the  Schmidt  and 
Haenzsch  half-shadow  type.  This  possesses  the  advantage  of  doing 
away  M-ith  the  matching  of  colors,  and  hence  may  be  used  by  those  who 
are  color-blind,  and  even  with  those  having  normal  color  vision  it  gives 
the  most  satisfactory  results. 

To  70.65  grams  of  milk  add  an  excess  (3  c.c.)  of  an  acid  nitrate  of 
mercury  solution  and  mix  thoroughly  by  shaking.  The  acid  nitrate  of 
mercury  solution  is  made  by  adding  one  part  of  weight  of  mercury  to  two 
parts  of  nitric  acid,  S.  G.  1.42,  and,  after  the  reaction  has  ceased,  adding 
an  equal  volume  of  distilled  water.  The  object  of  adding  the  acid  nitrate 
of  mercury  to  the  milk  is  to  remove  the  albumin  and  fat  in  the  form 
of  a  curd,  leaving  the  sugar  as  the  only  optically  active  constituent  of 
the  clear  serum.  The  milk  containing  the  acid  is  now  diluted  to  102.5 
c.c.  with  distilled  water  and  again  thoroughly  mixed.  Filter  through  a 
dry  pleated  filter  and  take  the  polarimeter  reading  without  delay  in  a 
200-mm.  tube.  When  an  excess  of  acid  nitrate  of  mercury  is  added  to 
the  sugar-containing  liquid  the  latter  quickly  begins  to  decompose,  with 
the  evolution  of  gas;  on  the  other  hand,  an  excess  must  be  present  in 
order  to  obtain  a  clear,  easily  filtered  liquid. 

The  percentage  of  lactose  is  the  product  of  the  factor  0.0209  (this 
factor  is  applicable  to  these  conditions  only)  multiplied  by  the  number 
of  minutes  of  dextrorotation.     The  definite  directions  for  this  particu- 


804  ANIMAL  FOODS:  MILK 

lar  kind  of  work  do  not  accompany  the  instrument  used.  The  factor 
should  be  determined  or  confirmed  by  comparing  with  lactose  solution 
of  known  strength.  Some  polarimeters  are  graduated  directly  in  sugar 
percentages  instead  of  degrees  and  minutes,  in  which  case  care  must 
be  taken  that  the  graduations  correspond  to  the  particular  form  of 
sugar  under  investigation,  or,  if  not,  that  a  suitable  correction  is 
made. 

Determination  of  Proteins. — It  is  not  usual  to  estimate  the  proteins 
in  a  sanitary  analysis  of  milk,  since  different  specimens  of  milk  vary 
but  little  in  this  regard,  and  since  there  is  little  inducement  for  sophis- 
tication, as  far  as  the  proteins  are  concerned. 

(1)  Method  by  Difference.- — If  we  know  the  weight  of  total  solids 
in  milk  and  subtract  therefrom  the  weight  of  the  fat,  ash,  and  sugar, 
the  difference  will  represent  the  proteins.  This  method  is  sufficient  for 
ordinary  purposes.  To  estimate  the  nature  of  the  various  proteins  re- 
quires special  skill  in  organic  analysis. 

(2)  Kjeldalil  Method. — The  milk  is  mixed  with  sulphuric  acid 
(using  mercury  as  a  catalyzer)  and  digested  in  a  flask  until  it  is  com- 
pletely charred  and  becomes  clear  again.  The  residue  will  then  contain 
all  of  the  nitrogen  in  the  form  of  ammonium  sulphate,  which  is  de- 
termined in  the  usual  way.  The  total  nitrogen  multiplied  by  the 
factor  6.38  gives  the  total  protein.  The  method  is  carried  out  as 
follows : 

Gunning  Modification. — An  accurately  weighed  amount  (about  5 
grams)  of  milk  is  placed  in  a  500-c.c.  Kjeldahl  digestion  flask  and 
digested  with  10  grams  of  potassium  sulphate  and  15  c.c.  of  concen- 
trated nitrogen-free  sulphuric  acid.  The  digestion  is  carried  out  over 
a  free  flame,  using  care  to  heat  gradually  at  first;  the  process  is  con- 
sidered complete  when  the  liquid  becomes  clear  (about  2  hours).  The 
contents  of  the  flask  are  cooled  and  200  c.c.  of  water  and  sufficient 
saturated  sodium  hydroxid  solution  to  neutralize  the  acid  and  to  make 
the  solution  strongly  alkaline  are  added.  The  nitrogen,  which  has  been 
converted  into  ammonium  hydroxide  is  now  distilled  through  a  block 
tin  tube  into  a  definite  amount  of  standard  acid,  and  the  acid  titrated 
back  with  standard  alkali,  using  cochineal  or  alizarin  as  indicator.  The 
amount  of  nitrogen  can  be  calculated  from  the  results.  Total  nitrogen 
multiplied  by  6.38  gives  total  protein. 

Calculation. — The  number  of  c.c.  of  N/10  acid  multiplied  by  0.0014, 
divided  by  the  weight  of  the  sample  of  milk  times  100  gives  the  per- 
centage of  nitrogen.  1  c.c.  of  N/10  acid  equals  0.0014  gram  of  N.  As 
the  reagents  always  contain  a  certain  amount  of  nitrogen  the  value  of  a 
blank  determination  should  always  be  subtracted  from  the  acid  reading. 

The  percentage  of  nitrogen  multiplied  by  the  factor  6.38  gives  the 
percentage  of  protein  in  the  sample  of  milk. 


CHKMTOAL  ANALYSIS  OK  MILK  805 

Exam  PL  k: 

50.5 — Xo.  cc.  of  N/IO  acid   orii^iiially    in   rccci\  iiii;  fia.sk. 
18.8 — No.  c.c.  ot"  N/10  alkali   w^rd    in   titration. 


31.7 

.3 — Value  .from  Llaiik  del crini nation. 


31.4— Total  No.  c.c.  N/10  acid  used. 
.0014 


.044 — Wt.  of  nitrogen. 
.044 
X100=.437.     Percentage  of  nitrogen. 


10.3 

.427X6.38=2.72.     Percentage  of  protein. 

Note. — The  factor  10.3  in  the  above  formula  is  the  weight  of  the 
sample  of  milk  used,  i.  e.,  the  volume  (10  c.c.)  times  the  specific  gravity 
of  the  milk. 

Water. — Milk  is  still  frequently  sophisticated  by  the  addition  of 
water.  A  watered  milk  may  be  suspected  from  a  low  specific  gravity,  or 
may  be  detected  unerringly  by  the  index  of  refraction  of  the  milk 
serum. 

Refractometer  Beading. — This  test  depends  upon  the  fact  that 
the  salts  dissolved  in  undiluted  milk  in  the  concentration  in  which  they 
exist  in  the  milk  serum,  as  prepared  under  standard  conditions,  give 
a  reading  of  not  less  than  39  upon  the  scale  of  a  Zeiss  refractometer 
at  a  temperature  of  17.5°  C.  Distilled  water  gives  with  the  same  in- 
strument a  reading  of  15.  Milk  reading  below  39  is  certainly  watered; 
.below  40  is  suspicious. 

Refractometer  reading  is  obtained  as  follows : 

The  milk  serum  is  prepared  by  adding  2  c.c.  of  a  25  per  cent, 
acetic  acid  (S.  G.  1.035)  to  100  c.c.  of  milk  at  about  20°  C.  and  mixing 
well.  Heat  the  mixture  in  a  beaker  covered  with  a  watch  glass  to  70°  C. 
Maintain  this  temperature  for  20  minutes.  Cool  quickly  to  room  temper- 
ature by  means  of  cold  water,  and  filter  until  nearly  or  quite  clear.  Do 
not  discard  the  curd,  as  it  can  be  used  to  test  for  the  presence  of  artificial 
colors.  The  refractometer  reading  is  taken  with  the  filtrate  at  17.5°  C, 
this  temperature  being  maintained  by  means  of  a  large  body  of  water  at 
the  same  temperature  surrounding  the  milk  container. 

If  a  refractometer  is  not  at  hand  practically  the  same  information 
can  be  obtained  from  the  milk  serum  by  taking  its  specific  gravity  with 
a  Westphal  balance  or  a  pycnometer. 


806  ANIMAL  FOODS:    MILK 

The  specific  gravity  of  the  se^-um  from  normal  milk  is  never  below 
1.027  and  only  rarely  below  1.029.  The  addition  of  each  10  per  cent, 
of  water  lowers  the  specific  gravity  by  0.0010  to  0.0035. 

Reaction. — The  acidity  of  milk  is  determined  by  titration  with  a 
solution  of  sodium  hydroxid,  using  phenolphthalein  as  the  indicator. 

Take  50  c.c.  of  milk  and  add  a  few  drops  of  alcoholic  phenolphtha- 
lein solution.  From  a  burette  run  in  0.1  normal  sodium  hydroxid  solu- 
tion with  constant  stirring  until  the  pink  color  in  the  milk  persists  about 
15  seconds.  The  carbon  dioxid  in  the  atmosphere  fades  out  the  phenol- 
phthalein color  by  converting  the  sodium  hydroxid  into  sodium  bicar- 
bonate, hence  the  determination  must  be  made  rapidly,  and  a  rather  faint 
but  not  very  permanent  pink  color  marks  the  end  point. 

The  acidity  of  milk  is  usually  expressed  in  terms  of  lactic  acid,  al- 
though when  fresh  it  is  caused  by  other  organic  acids.  To  convert  the 
amount  of  X/10  sodium  hydroxid  solution  necessary  to  neutralize  the 
acidity  in  50  c.c.  of  milk  into  percentages  of  lactic  acid,  multiply  the 
number  of  cubic  centimeters  of  X/10  XaOH  by  0.018. 

The  results  of  these  titrations  are  recorded  in  three  different  ways: 
(1)  In  this  country  the  calculations  are  reduced  to  terms  of  lactic  acid. 
Thus,  1  c.c.  of  X/10  XaOH  neutralizes  0.009  gram  of  lactic  acid;  (2)  in 
degrees  of  acidit}^  by  which  is  meant  the  number  of  cubic  centimeters  of 
X/10  XaOH  required  to  neutralize  100  c.c.  of  milk;  (3)  in  German  de- 
grees of  acidity,  meaning  the  number  of  cubic  centimeters  of  X/4  XaOH 
per  100  c.c.  of  milk.  For  transposition  j)urposes  the  following  equiva- 
lents are  given : 

1  degree  (U.  S.)  of  acidity 0.009     per  cent,  lactic  acid 

1  degree  (German)  of  acidity. .  .   0.0225  per  cent,  lactic  acid 
1  degree  (German)  of  acidity.  .  .  2.5°      (TJ.  S.)  acidity 

Eiihm  -'  has  recommended  the  follo^^dng  test  for  detection  of  begin- 
ning acidification  in  mixed  milks  of  two  or  more  cows :  Ten  c.c.  of 
68  per  cent,  alcohol  is  added  to  10  c.c.  of  the  milk  to  be  tested.  If 
there  is  immediate  coagulation  the  acidity  is  above  8°.  More  advanced 
acidity  may  be  detected  by  boiling  a  small  amount  of  milk  for  a  few 
moments  in  a  test  tube.  Coagulation  appears  if  the  acidit}'  is  above 
10°.     These  are  convenient  tests  that  may  be  applied  at  the  dairy. 

The  accurate  way  to  determine  reaction  is  to  measure  the  hydrogen 
ion  concentration  by  means  of  indicators,  or  better,  by  the  gas-chain 
and  potentiometer.  The  pH  values  of  fresh  cow's  milk  range  between 
6.5  to  6.8;  fresh  mother's  milk  varies  between  7.1  and  7.6. 

Milk  has  a  variable  acidity  when  it  coagulates;  that  is,  when  it 
throws  its  casein   out  of   solution.     Milk  containing  about   0.225  per 

*'Rulim:     Zeitschr.  f.  Fleisch  u.  ililch-hyg.,  Vol.  XX,  1910. 


CHEMICAL  AI^ALYSIS  OF  MILK  807 

cent,  of  acid  will  t-oagulaio  \i])()n  lioatin^'.  This  may  be  prevented  by 
first  neutralizing  with  an  alkali,  such  as  sodium  carbonate.  The  amount 
of  acidity  in  a  particular  sample  of  milk  is  no  safe  criterion  as  to 
whether  it  will  coagulate  or  not  during  pasteurization.  This  can  only 
be  determined  with  certainty  by  first  testing  a  small  portion. 

Specific  Gravity. — The  specific  gravity  of  milk  is  taken  either  (1) 
with  the  lactodensimeter,  (2)  with  the  Westphal  balance,  or  (3)  upon 
an  ordinary  chemical  balance,  with  a  pycnometer. 

The  Quevenne  laciodensimeter  is  recommended  for  the  determi- 
nation of  the  specific  gravity.  It  is  made  like  an  ordinary  aerometer 
and  divided  into  degrees  which  correspond  to  a  specific  gravity  from 
1.014  to  1.040,  or  only  from  1.022  to  1.038,  since  by  the  latter  division 
a  greater  space  is  gained  between  the  different  degrees  without  unduly 
lengthening  the  instrument.  From  such  a  lactodensimeter  one  can  easily 
read  off  four  decimal  places. 

The  milk,  the  specific  gravity  of  which  is  to  be  determined,  is  well 
shaken  and  poured  into  a  high-class  cylinder  of  suitable  diameter;  the 
lactodensimeter  is  dropped  in  slowly,  in  order  to  prevent  its  bobbing 
up  and  down.  (The  bulb  should  be  free  from  adhering  air  bubbles.) 
The  figures  on  the  stem  are  the  second  and  third  decimals  of  the  num- 
bers of  the  specific  gravity,  so  that  34  is  to  be  read  1.034.  For  this 
examination  the  temperature  of  the  milk  must  be  15°  C.  (60°  F.)  ;  if 
it  is  not,  the  specific  gravity  of  the  milk  at  15°  C.  must  be  calculated 
from  the  specific  gravity  found  and  from  the  temperature,  for  in  milk 
inspection  and  analysis  this  is  the  standard. 

WestpJial  Balance. — This  instrument  is  more  accurate  than  the 
lactometer.  It  is  in  equilibrium  when  the  sum  of  the  weights  equals 
the  specific  gravity  of  the  liquid. 

To  use  this  instrument,  dry  the  plummet  and  balance  the  arm  in  the 
air;  then  fill  the  cylinder  with  the  sample.  Xow  place  the  plummet  in 
the  milk  and  balance  the  w^eights.  The  large  w^eights  represent  the 
first  decimal  place ;  the  second  size,  the  second  decimal  place ;  the  third 
size,  the  third  decimal  place;  and  the  fourth  size,  the  fourth  decimal 
place.  The  specific  gravity  is  the  sum  total,  as  shown  by  the  notches  on 
the  arm  of  the  balance. 

Example  : 

Notch       Value 

Largest  size  weights 9  .9 

Largest  size        "       1  .1 

Second  size         "       3  .03 

Third  size  "       2  .002 

Fourth  size         "       4  .0004 

1.0324  =  Specific  Gravity 


808  ANIMAL  FOODS:  MILK 

Correct  for  temperature  by  means  of  the  following  table: 

Table  for  correcting  the  specific  gravity  of  milk  according  to  temperor 
ture.     (Adapted  from  the  table  of  Vieth.) 


Specific 
Gravity 

10° 

11° 

12° 

13° 

14° 

15° 

16° 

17° 

18° 

19° 

20° 

1.027 

26.1 

26.2 

26.4 

26.5 

26.7 

26.9 

27.1 

27.4 

27.5 

27.7 

28.0 

28 

27.0 

27.2 

27.4 

27.5 

27.7 

27.9 

28.1 

28.4 

28.5 

28.7 

29.0 

29 

28.0 

28.2 

28.4 

28.5 

28.7 

28.9 

29.1 

29.4 

29.5 

29.8 

30.1 

30 

29.0 

29.1 

29.3 

29.5 

29.7 

29.9 

30.1 

30.4 

30.5 

30.8 

31.1 

31 

29.9 

30.1 

30.3 

30.4 

30.6 

30.9 

31.2 

31.4 

31.5 

31.8 

32.2 

32 

30.9 

31.1 

31.3 

31.4 

31.6 

31.9 

32.2 

32.4 

32.6 

32.9 

33.2 

33 

31.8 

32.0 

32.3 

32.4 

32.6 

32.9 

33.2 

33.4 

33.6 

33.9 

34.2 

Directions  :  Find  the  observed  specific  gravity  in  the  left-hand  column.  Then  in 
the  same  line,  and  under  the  observed  temperature,  will  be  found  the  corrected  reading. 

Taking  the  specific  gravity  of  the  whole  milk  does  not  of  itself  de- 
tect either  watering  or  skimmings  since,  if  these  practices  are  done 
artfully,  the  specific  gravity  of  the  milk  may  remain  unaltered.  The 
specific  gravity  of  normal  milk  serum  is  about  1.0287. 

Field  Tests. — There  are  several  rough  and  ready  milk  tests  useful 
in  the  field:  (1)  The  Wisconsin  curd  test,  for  flavors,  odors  and  dirti- 
ness; (2)  the  dirt  test,  for  visible  dirt;  (3)  the  bacterial  count,  by 
microscopic  examination;  (4)  the  Farrington  quick  acid  test  for  reac- 
tion;  (5)   specific  gravity;  (6)  temperature. 

Heated  Milk.— Milk  that  has  been  heated  above  79°  or  80°  C.  may 
be  detected  by  the  fact  that  the  enzymes  are  killed.  Several  methods 
are  used;  the  most  convenient,  perhaps,  is  Dupouy's  method.  A  few 
drops  of  a  freshly  prepared  solution  of  diamidobenzene  in  water  (1-4) 
and  a  little  hydrogen  dioxid  are  added  to  5  c.c.  of  milk.  "With  raw 
milk  a  coloration  appears,  while  with  milk  that  has  been  heated  to  79° 
C  or  over  no  color  is  produced.  Other  tests,  such  as  the  Storch  method 
or  Arnold's  guaiac  method,  are  described  below  under  "Tests  for 
Enzymes." 

A  test  for  heated  milk  has  recently  been  devised  by  Frost  who  finds 
that  the  leukocytes  in  raw  milk  do  not  stain  with  methylene  blue, 
whereas  these  cells  in  heated  milk  stain  well,  especially  the  nuclei,  and 
are  smaller.^^ 

Van  Slyke  has  shown  that  heated  milk  contains  little  CO2,  as  com- 
pared to  unheated  samples.  Milk  from  the  cow  contains  4  to  5  per 
cent.  CO2,  seldom  less  than  3.5  per  cent.  After  pasteurization,  the 
amount  drops  to  2  per  cent.,  and  is  never  over  2.5  per  cent. 

Tests  for  Enzymes,  and  Their  Significance. — The  following  tests  are 
those  most  frequently  used : 

Catalase  Test. — Ten   c.c.   of  the  milk  to  be  tested   is  mixed  with 

»V.  A.  M.  A.,  March  6,  1915,  also. 


CHEMICAI;  ANALYSIS  OF  MILK  809 

10  c'.c.  of  a  3  i)c'r  cent,  (by  volume)  hydrogen  peroxid.  The  mixture 
is  placed  in  a  Lobeck  tube  and  the  stopper  tightly  inserted.  Then  the 
tube  for  measuring  the  liberated  oxygen  is  filled  with  water  and  inserted 
into  the  perforated  stopper,  pushing  out  the  small  hard  rubber  button. 
The  mixture  of  milk  and  hydrogen  peroxid  is  immersed  up  to  the  stop- 
per in  a  water  bath  at  37°  C.  and  left  there  for  two  hours.  The  oxygen 
that  is  lilicrated  replaces  the  water  in  the  graduated  tube  on  which  the 
readings  are  made.  Larger  quantities  of  milk  (15  c.c.)  and  less  hydro- 
gen peroxid  (3  c.c.)  give  more  satisfactory  readings  for  pasteurized 
milk. 

•  According  to  Auzinger,  the  liberation  of  much  gas  by  this  test  oc- 
curs (1)  with  physiologically  changed  milk,  as  is  the  case  with  colos- 
trum and  with  milk  from  old  milkers;  (2)  in  the  case  of  pathologically 
changed  milk,  as  in  mastitis  and  other  febrile  diseases;  or  (3)  in  milk 
containing  a  large  number  of  bacteria. 

The  test  for  catalase,  therefore,  is  of  assistance  in  detecting  old, 
bacteria-laden,  or  abnormal  milk. 

Bedudnse  Test. —  (1)  Schmidt-Muller  or  Slow  Eeductase  Test. — 
The  reagent  is  made  by  adding  195  c.c.  of  distilled  water  to  5  c.c.  of 
a  saturated  alcoholic  solution  of  methylene  blue  (zinc  chlorid  double 
salt).  This  reagent  should  be  boiled  every  day  before  using.  The 
test  is  made  by  adding  to  20  c.c.  of  milk  in  a  test  tube  1  c.c.  of  the 
reagent,  mixing,  sealing  with  melted  paraffin,  and  then  incubating  at 
45°  C.  in  a  water  bath.  According  to  Eiihm,-^  fresh  milk  remains  blue 
for  13  hours  or  more,  and  '"infected"  milk  decolorizes  in  less  than  one 
hour.  Eeductases,  according  to  Eiihm,  are  increased  by  acid-forming 
bacteria,  but  not  by  alkaline  producers.  Auzinger,^°  who  uses  0.5  c.c. 
of  the  reagent  in  20  c.c.  of  milk,  states  that^  on  holding  the  mixture 
at  38°  to  40°  C,  milk  not  decolorizing  in  seven  hours  contains  less 
than  100,000  bacteria  per  c.c;  that  which  decolorizes  in  2  to  7  hours 
contains  100,000  to  300,000;  and  that  which  decolorizes  in  %  to  2 
hours  contains  300,000  to  20,000,000  bacteria  per  c.c. 

(2)  Schardinger  or  Hastened  Eeductase  Test. — The  reagent  is  made 
by  adding  5  c.c.  of  40  formaldehyd,  5  c.c.  of  saturated  alcoholic  solution 
of  methylene  blue  (zinc  chlorid  double  salt)  to  190  c.c.  of  distilled 
water. 

The  test  is  made  by  adding  to  10  c.c.  of  milk,  2  c.c.  of  the  reagent 
in  a  test  tube,  mixing  well,  sealing  with  melted  paraffin,  and  holding 
at  37^  C.  in  a  water  bath.  By  the  test,  according  to  Auzinger,^"  good 
milk  reduces  the  color  in  8  to  12  minutes,  milk  rich  in  bacteria  reduces 
in  5  minutes  or  less,  and  when  colostrum  is  present  two  or  more  hours 
are  required. 

^Riihin:     Zeit.  f.  Fl.  u.  Milch-hyg.,  Vol.  XX.  1910. 
^Auzinger:     Ibid.,  Vol.  XX,  1910. 


810  ANIMAL  FOODS:    MILK 

To  test  for  heated  milk:  add  20  c.e.  of  the  milk  to  1  c.c.  of  the 
reagent;  seal  with  liquid  petroleum,  and  incubate  at  45°  to  50°  C.  Raw 
milk  will  decolorize  this  reagent  in  less  than  20  minutes;  pasteurized 
milk  will  take  a  longer  time. 

Of  the  two  reductase  tests,  according  to  Schardinger,^^  reduction  by 
the  slow  method  is  due  to  ferments  produced  by  bacteria,  while  by  the 
hastened  method  reduction  is  due  to  the  natural  ferments  of  milk. 

The  slow  reductase  test  is  of  assistance  in  detecting  old  milk,  and 
the  hastened  reductase  test  offers  a  convenient  and  reliable  method  for 
detecting  and  testing  the  efficiency  of  pasteurization. 

Storch  Test. — To  about  5  c.c.  of  milk  in  a  test  tube  add  a  drop  of^ 
0.2  per  cent,  solution  of  hydrogen  peroxid  containing  0.1  per  cent,  sul- 
phuric acid,  and  2  drops  of  a  2  per  cent,  aqueous  solution  of  parapheny- 
lendiamin  hydrochlorid.  Mix.  A  positive  reaction  consists  in  the  rapid 
production  of  a  blue  or  dark-violet  color.  The  paraphenylendiamin  hy- 
drochlorid does  not  keep  well  and  should  be  recently  prepared.  If  the 
milk  is  sour  it  must  first  be  made  alkaline  with  limewater.  Eaw  milk 
gives  a  positive  reaction  at  once;  milk  that  has  been  heated  to  boiling 
gives  no  reaction. 

Peroxidase  Reaction. —  (1)  Eothenfusser's  Test:^^  Dissolve  1 
gram  of  /^-phenylendiamin  hydrochlorid  in  15  c.c.  of  water.  Dissolve  2 
grams  of  crystallized  guaiacol  in  135  c.c.  of  96  per  cent,  alcohol.  Mix 
the  solutions  and  keep  in  an  amber-colored  bottle.  To  10  c.c.  of  milk 
add  0.5  c.c.  of  the  above  reagent  and  3  drops  of  3  per  cent,  hydrogen 
dioxid.  A  blue-violet  coloration  is  developed  in  raw  milk  and  if  the  milk 
has  been  heated  to  a  sufficiently  high  temperature  no  color  is  produced. 
This  reaction  is  scarcely  delicate  enough  to  detect  commercially  pasteur- 
ized milk. 

(2)  The  Benzidin  Test:  ^^  Dissolve  4  grams  of  benzidin  in  100  c.c. 
of  96  per  cent,  alcohol.  To  10  c.c.  of  milk  add  1  c.c.  of  this  reagent, 
3  drops  of  30  per  cent,  acetic  acid  and  2  c.c.  of  3  per  cent,  hydrogen 
dioxid;  a  blue  coloration  is  produced  with  raw  milk  and  none  with  milk 
heated  to  a  sufficiently  high  temperature. 

Bellei  Test. — The  test  is  made  by  adding  to  10  c.c.  of  milk  3 
drops  of  1.5  per  cent,  aqueous  solution  of  ortol  and  two  drops  of  3 
per  cent.  HgOg. 

TESTS  FOR  THE  ADULTERATION   OF  MILK 

Coloring^  Matter.— To  150  c.c.  of  milk,  add  5  c.c.  of  25  per  cent, 
acetic  acid  in  a  large  porcelain  casserole  and  curdle  over  the  Bunsen 

^^  Schardinger :     Arch.  f.  Kinderheilk.,  Bd.  58,  H.  5-6. 
'"  MilchioirtscM.  Zentr.,  VI,  468. 
^^Z.  Nahr.  Oenussm.,  XYJ,  172. 


CHEMICAL  ANALYSIS  OF  MILK 


811 


flame  with  the  stirring  rod.  The  curd  can  nearly  always  be  gathered 
in  one  mass  which  is  much  the  easier  method  of  separation,  the  whey 
being  simply  poured  ofl".  If,  however,  the  curds  are  too  finely  divided  in 
the  whey,  the  separation  is  eft'ected  by  straining  through  a  sieve  or 
collander.  All  of  the  annatto  or  "coal  tar  dye  present  in  the  milk  treated 
will  be  found  in  the  curd,  also  part  of  the  caramel.  The  curd  pressed 
free  from  the  adhering  fluid  is  picked  apart  if  necessary  and  shaken 
in  a  tightly  corked  flask  with  about  50  c.c.  of  ether,  in  which  it  is 
allowed  to  soak  for  several  hours  or  over  night,  or  until  the  fat  has 
been  extracted  and  with  it  the  annatto. 

If  the  milk  is  uncolored  or  has  been  colored  with  annatto,  on  pour- 
ing off  the  ether  the  curd  should  be  left  perfectly  white.  If,  on  the 
other  hand,  anilin  orange  or  caramel  have  been  used,  after  pouring  off 
the  ether  the  curd  will  be  colored  more  or  less  deeply,  depending  on 
the  amount  of  color  employed.  In  other  words,  the  annatto  is  ex- 
tracted by  ether,  caramel  and  anilin  orange  are  not. 


Ether  Extract: 


Evaporate  off  the  ether  on  the  wa- 
ter bath,  make  the  residue  alkaline 
with  ISTaOH  and  pour  on  a  wet  filter. 
After  the  solution  has  passed  through, 
wash  off  the  fat  and  dry  the  filter, 
which,  if  colored  orange,  indicates 
the  presence  of  annatto.  Confirm 
with  SnCL2  which  will  give  a  pink 
color. 


Extracted  Curd: 


1, — ^If  colorless  indicates  the  pres- 
ence of  no  foreign  coloring  matter 
other  than  that  in  the  ether  extract, 

2, — If  orange  or  brownish,  indicates 
the  presence  of  anilin  orange  or  cara- 
mel. Shake  the  curd  in  a  test  tube 
with  cone.  HCl. 


If  the  solution 
gradually  turns 
blue  means  Cara- 
mel, Test  whey 
of  original  milk 
and  confirm. 


If  orange  and 
immediately  turns 
pink,  it  is  Anilin- 
orange. 


Formaldehyd. — HCl  Test. — Commercial  HCl  (sp,  gr.  1,3)  con- 
taining 2  c,c,  of  10  per  cent.  Fe.^Clg  per  1.,  is  used  as  a  reagent.  Add 
10  c.c.  of  this  acid  reagent  to  an  equal  volume  of  milk  in  a  porcelain 
casserole,  and  heat  slowly  over  a  free  flame  nearly  to  boiling,  holding  the 
casserole  by  the  handle  and  giving  it  a  rotary  motion  to  break  up  the 
curd.  The  presence  of  formaldehyd  is  indicated  by  a  violet  coloration, 
varying  in  amount  and  depth  with  the  amount  of  preservative  present. 
By  this  test,  formaldehyd  can  be  detected  readily  in  as  high  dilution 
as  one  part  in  250,000  parts  of  milk. 

NaoCO,  and  the  Carbonates. — For  0.1  per  cent,  or  more,  take  10  c.c. 
of  milk  and  mix  with  an  equal  volume  of  alcohol.     To  this  add  a  few 


812  ANIMAL  FOODS:    MILK 

drops  of  a  1  per  cent,  solution  of  rosolic  acid.  A  rose  red  color  proves 
the  presence  of  carbonates,  while  pure  milk  gives  a  brownish-yellow 
color. 

The  addition  of  acid  to  the  residue  or  ash,  if  it  causes  an  efferves- 
cence, proves  the  presence  of  carbonates. 

Benzoic  Acid. — Shake  5  c.c.  of  HCl  with  50  c.c.  of  milk  in  a  flask 
until  it  is  well  curdled.  Add  150  c.c.  of  ether,  cork  the  flask  tightly 
and  shake  well.  Extract  the  emulsion  which  forms  by  means  of  the  cen- 
trifuge or  extract  the  curdled  milk  by  gently  shaking  with  successive 
portions  of  ether,  avoiding  forming  an  emulsion.  A  volume  of  ether 
largely  in  excess  of  that  of  the  curdled  milk  has  been  found  to  be 
less  apt  to  emulsionize.  Transfer  the  ether  extract  to  a  funnel  and 
extract  the  benzoic  acid  from  the  fat  by  shaking  out  with  dilute  NH^OH 
which  takes  out  the  former  as  ammonium  benzoate.  Evaporate'  the  am- 
monia solution  over  the  water  bath  until  all  free  ammonia  has  volatilized, 
but  before  getting  to  dryness  add  a  few  drops  of  the  EeaClg  reagent. 
The  characteristic  flesh-colored  precipitate  indicates  benzoic  acid.  Care 
should  be  taken  not  to  add  the  FeaClg  until  all  the  ammonia  has  been 
driven  off,  as  otherwise  a  precipitate  of  Fe2(0H)e  is  formed. 

Salicylic  Acid. — The  procedure  is  the  same  as  for  benzoic  acid, 
except  that  the  addition  of  Fe^Clg  gives  a  violet  color. 

Boric  Acid  and  the  Borates. — To  100  g.  of  the  milk  sample,  add  1 
or  3  g.  of  NaOH  and  evaporate  to  dryness  on  the  water  bath.  Char 
the  residue  thoroughly  and  boil  with  20  c.c.  of  water,  adding  HCl 
drop  by  drop  until  all  but  the  carbon  is  dissolved,  and  then  add  1  c.c. 
in  excess.  Moisten  a  piece  ot  delicate  turmeric  paper  in  the  solution. 
If  borax  or  boric  acid  is  present,  the  paper  on  drying  will  acquire  a 
peculiar  red  color  which  is  changed  to  a  dark  blue-green  by  NH^OH, 
but  is  restored  by  acid. 

Simple  Modification:  In  a  porcelain  dish,  mix  1  drop  of  milk,  2 
drops  of  cone.  HCl,  and  2  drops  of  sat.  tr.  of  turmeric.  Dry  in  the 
water  bath,  cool  and  add  1  drop  of  NH^OH  by  means  of  a  glass  rod.  A 
slaty  blue  color  is  produced  if  borax  is  present. 

Cane  Sugar. — 1.  Boil  5  to  10  c.c.  of  the  sample  with  about  0.1  g.  of 
resorcin  and  a  few  drops  of  HCl  for  a  few  minutes.  A  rose  red  color 
shows  the  presence  of  cane  sugar.     Or : 

2.  Mix  in  the  test  tube,  10  c.c.  of  the  suspected  milk  with  0.5 
g.  of  powdered  ammonium  molybdate.  Ten  c.c.  of  milk  of  a  known 
purity  or  10  c.c.  of  a  6  per  cent,  lactose  solution  are  treated  in  a 
similar  way  for  comparison.  Both  tubes  are  placed  in  the  water  bath 
and  the  temperature  gradually  raised  to  80°  C.  An  intense  blue  color 
shows  the  presence  of  cane  sugar.  If  the  temperature  is  raised  to  boil- 
ing, the  pure  milk  or  the  sugar  solution  may  turn  a  blue  color. 

Starch.— A  small  quantity  of  milk  is  heated  in  a  test  tube  to  boiling. 


CHEMICAL  ANALYSIS  OF  MII.K  813 

cooled,  and  a  drop  of  laiii^ors  yulutioii  is  added.     Blue  discoloration 
shows  the  presence  of  starch. 

REFERENCES 

SoMMERFELD,  Paul  :  "Handbuch  der  Milchkunde,"  J.  F.  Bergmann,  Wies- 
baden, 1909. 

SwiTHiNBANK,  Harold,  and  Newman,  George  :  "Bacteriology  of  Milk,"  E 
P.  Button  &  Co.,  1903. 

"Milk  and  Its  Relation  to  the  Public  Health,"  Hycj.  Lab.  Bull.  No.  56, 
U.  S.  P.  H.  &  M.  H.  S.    Various  authors. 

RosENAU,  M.  J. :    "The  Milk  Question,"  Houghton,  Mifflin  &  Co.,  1912. 

Savage,  Wm.  G.:  "Milk  and  the  Public  Health,"  Macmillan  &  Co.,  Ltd., 
London,  1912. 

Report  of  the  Commission  on  Milk  Standards,  N.  Y.  Milk  Committee,  Pub- 
lic Health  Reports,  U.  S.  P.  H.  &  M.  H.  S.,  xxvii,  19,  May  10,  1912. 

Barthel,  Chr.  :  "Die  Methoden  zur  Untersuchung  von  Milch  und  Mol- 
kereiprodukten."  Leipzig,  1911.  English  edition  translated  by  Good- 
win. 

Jensen:  "Essentials  of  Milk  Hygiene."  Translated  by  Leonard  Pearson. 
J.  P.  Lippincott  Co.,  1907. 

Farrington  and  Woll:  "Testing  Milk  and  Its  Products,"  21st  edition, 
Mendata  Book  Co.,  Madison,  Wis.,  1912. 

Heinemann,  Paul  G  . :  "Milk."    W.  B.  Saunders  Company,  1919. 

MacNutt,  J.  Scott:  "The  Modern  Milk  Problem  in  Sanitation,  Eco- 
nomics and  Agriculture."     The  Macmillan  Company,  New  York,  1917. 

North,  Charles  Edward  :  "Farmers'  Clean  Milk  Book."  John  Wiley  and 
Sons,  Inc.,  New  York,  1918. 

Race,  Joseph  :  "The  Examination  of  Milk  for  Public  Health  Purposes." 
John  Wiley  and  Sons,  Inc.,  New  York,  1918. 


CHAPTER  III 
ANIMAL  FOODS :  MEAT,  FISH,  EGGS,  ETC. 

MEAT 


TLe  "universal  consumption  of  fresh  meat  as  a  daily  article  of  diet  by 
civilized  man  is  of  more  recent  origin  than  is  generally  supposed. 
McCulloch  ^  states  that  "so  late  as  1763  the  slaughter  of  buflocks  for 
the  supply  of  the  public  markets  was  a  thing  wholly  unknown,  even  in 
Glasgow,  though  the  city  then  had'  a  population  of  30,000."  In  the 
past  decade  or  two  the  consumption  of  meat  has  increased  enormously, 
especially  in  the  United  States  and  England,  owing  to  the  development 
of  efficient  refrigerator  processes,  canning,  and  improved  facilities  of 
transportation.  The  annual  per  capita  consumption  of  meat  has  almost 
doubled  during  the  past  half  century.^ 

Per  capita  and  proportional  consumption  of  dressed  meat  in  United  States,  United 
Kingdom,,  Germany,  and  France 

[The  Twenty-eighth  Annual  Report  of  the  Bureau  of  Animal   Industry,   1911] 


Kind  of  Meat 

United  States 
(1909) 

United  Kingdom 

(Average.  1906- 

1908) 

Germany  (1909)* 

France  (1904) 

Beef    

Veal    

Mutton  and 
lamb    

Pork  (includ- 
ing lard)  .  . 

Pounds 
80 

71/2 

61/2 
78 

Per  Cent. 
47 

4 

4 
45 

Pounds 
56 

4 

26 
33 

Per  Cent. 
47 
3 

22 

28 

Pounds 
36 

71/2 

21/2 
67 

Per  Cent. 
32 
7 

2 

59 

Pounds 
37 
8 

9 

26 

Per  Cent. 
46 
10 

11 

33 

Total    ... 

172 

100 

119 

100 

113 

100 

80 

100 

*  The  farm  slaughter   in   Germany  is  for  1907. 

Structure  and  Composition  of  Meats. — Meat  is  composed  of  muscular 
fibers,  and  the  structures  intimately  associated  with  them,  such  as  con- 
nective tissue,  blood  vessels,  nerves,  lymphatic  vessels,  and  more  or  less 
adipose  tissue. 

The  toughness  of  meat  is  due  to  the  thickness  of  the  walls  of  the 
muscle  tubes  and  excess  of  connective  tissue  which  binds  them  together, 

^  "Statistical  Account  of  the  British  Empire,"  Vol.  II,  p.  502. 
^Thompson:     "Practical  Dietetics." 

814 


MEAT  815 

hence  tlie  flesli  of  young  domesticated  animals  is  usually  more  tender 
than  that  of  old  or  wild  animals. 

1'he  flavor  of  meat  varies  Avitli  the  animal's  age,  its  food,  breed,  and 
condition  -when  killed.  The  meat  of  male  animals  is  usually  more  highly 
flavored  than  that  of  females.  The  flesh  of  service  boars  and  of  sexually 
mature  buck  goats  is  so  highly  flavored  as  to  be  unfit  for  food. 

The  muscle  tissue  of  an  animal  consists  of  highly  specialized  tis- 
sue, whose  chief  function  is  to  produce  mechanical  work  through  con- 
traction. It  is  in  addition  a  storage  organ  in  which  glycogen,  a  form 
of  starch,  and  also  fats  are  stored  as  reserve  foods.  It  contains  but 
little  of  cellular  structures  in  the  sense  that  the  glandular  organs,  such 
as  the  liver,  kidney,  pancreas,  etc.,  do.  Chemical  analysis  shows  the 
muscle  to  consist,  aside  from  the  reserve  foodstuffs,  principally  of  water, 
protein  and  salts.  The  glandular  organs  yield  a  high  content  of  nucleic 
acid,  while  the  muscle  tissue  yields  but  little  in  proportion  to  its 
weight.  The  inorganic  content  of  the  muscle  tissue  resembles  that  of 
the  seed  of  the  plant,  rather  than  the  leaf,  both  in  amount  and  in  rela- 
tive proportions  among  the  elements  (McCollum). 

Meat  contains  albuminoids  and  gelatinoids;  the  latter  through  ac- 
tion of  hot  water  or  steam  are  converted  into  gelatin.  In  addition  meat 
contains  the  following  nitrogenous  substances :  syntonin,  myosin,  muscle 
albumin,  serum  albumin,  and  numerous  extractives,  such  as  creatin, 
creatinin,  santhin,  hypoxanthin,  lactic  acid;  and  small  quantities  of 
inosite  and  glycogen. 

Meat  at  once  after  slaughter  has  an  alkaline  reaction,  is  tough,  and 
possesses  a  sweetish  and  rather  unpleasant  flavor.  Rigor  mortis  soon 
sets  in,  accompanied  by  the  following  changes:  the  reaction  of  the  me  it 
turns  acid,  owing  to  the  development  of  sarcolactic  acid;  the  connective 
tissue  and  fibers  are  softened  as  the  result  of  autolytic  enzymes  and  also 
as  a  result  of  bacterial  action.  While  the  meat  becomes  more  tender,  it 
also  develops  pleasant  flavors.  It  is,  therefore,  not  advisable  to  use  meat 
at  once  after  slaughter,  but  it  should  be  allowed  to  hang  two  or  three 
weeks  under  adequate  refrigeration.  It  is  important  during  this  time 
to  preserve  the  meat  from  contamination  with  pathogenic  microorganisms 
and  to  retard  the  growth  of  the  saprophytes. 

Nutritive  Value  of  Meat. — The  nutritive  value  of  meat  depends 
mainly  upon  the  presence  of  proteins  and  fats.  Nitrogenous  extractive 
matters,  such  as  creatin,  xanthin,  etc.,  sometimes  called  meat  bases, 
are  formed  by  cleavage  of  the  proteins,  but  are  of  little  value  as  foods. 
These  nitrogenous  extractives  are  present  in  about  the  same  amount 
in  both  red  and  white  meats,  with  the  single  exception  of  venison,  which 
contains  the  smallest  amount. 

Corresponding  with  the  specialized  function  and  the  peculiarities  in 
composition  of  muscle,  we  find  that  the  dietary  properties  of  meat  are 


816  ANIMAL  FOODS:    MEAT,  FISH,  EGGS,  ETC. 

comparable  with  the  seed  rather  than  the  leaf  of  plants;  in  fact,  muscle 
tissue  diif ers  markedly  from  the  seed  in  only  one  respect  when  con- 
sidered as  a  foodstuff,  namely,  in  the  quality  of  its  proteins.  The  pro- 
teins of-  meat  are  complete,  those  of  seeds  incomplete.  Both  meats  and 
seeds  are  poor  in  inorganic  salts,  which  are  necessary  in  the  diet.  Both 
muscle  and  seeds  are  relatively  poor  in  "fat-soluble  A"  as  compared  with 
such  foods  as  milk,  egg  yolk,  and  the  leaves  of  plants.  Meat  is  an  ad- 
mirable source  of  protein  of  good  quality,  but  it  is  not  an  economical 
food.  It  is  appetizing,  satisfying  and  stimulating.  The  condimental 
value  of  meat  is  very  high.  A  very  common  dietetic  error  is  to  eat  too 
much  meat. 

Carnivora  maintain  a  good  state  of  nutrition  because  they  suck 
blood  from  the.  large  veins  of  the  neck  and  their  second  choice  is  the 
liver  and  other  glandular  organs.  Muscle  tissue  is  only  eaten  after 
these  have  been  consumed.  Calcium  is  obtained  through  gnawing  off 
the  softer  parts  of  the  extremities  of  the  bones. 

Beef  extracts  are  nothing  more  or  less  than  a  soup  or  soup  stock 
specially  prepared  from  beef.  They  first  became  generally  known  through 
the  researches  of  Liebig,  and  are  now  an  important  article  in  commerce. 
The  composition  of  the  ordinary  beef  extract  of  commerce  contains  from 
15  to  20  per  cent,  of  moisture,  from  17  to  23  per  cent,  ash,  and  from  50 
to  60  per  cent,  of  meat  bases.  These  meat  bases  are  the  soluble  nitro- 
genous contents  of  meat.  They  contain  only  a  trace  of  soluble  albumin, 
albumoses,  and  peptone.  The  chief  meat  bases  which  form  the  principal 
part  of  the  substance  are  creatin,  creatinin,  xanthin,  carnin,  and  carnic 
acid.  It  is,  therefore,  evident  that  meat  extracts  contain  little  nutritive 
matter,  although  this,  being  in  a  state  of  solution,  is  probably  more  readily 
absorbed  than  a  similar  amount  of  other  nutritives  in  the  form  of  ordi- 
nary meat.  Wiley  properly  points  out  that  the  claim  made  by  manufac- 
turers that  one  pound  of  extract  contains  the  nutritive  properties  of 
many  pounds  of  meat  is  misleading.  Such  a  statement  is  absurd  upon  its 
face,  and  should  not  be  allowed  to  go  unchallenged.  These  extracts  may 
be  useful  as  stim-ulants  or  as  condiments,  or  as  a  means  of  speedily  intro- 
ducing a  soluble  nutriment  in  the  case  of  disease,  where  it  is  extremely 
important  that  even  small  amounts  of  nutritious  material  should  enter 
the  body. 

A  distinction  should  be  made  between  beef  extract  and  beef  juice. 
Beef  juice  is  obtained  by  strong  pressure  and  is  concentrated  in  vacuo 
to  the  proper  consistence,  or  it  may  be  freshly  prepared  in  the  house- 
hold. Beef  juice  contains  much  more  albuminous  nutrient  material  than 
beef  extract,  provided  it  is  not  coagulated  by  heat  and  separated  out. 

Sources  of  Meat. — The  principal  source  of  meat  is  from  cattle,  sheep, 
and  swine.  In  many  places  the  flesh  of  horses,  dogs,  and  cats  is  eaten. 
In  Germany  horses  and  dogs  are  slaughtered  and  regularly  inspected 


MEAT  817 

for  Ininian  food,  'riic  meal  of  these  aiiiiiiiils  is  also  used  in  other  coun- 
tries tliat  liave  long  heen  iK'sh  huii,ij:rv.  'I'here  is  no  sanitary  objection 
to  the  use  of  such  meat.  Horse  meat,  when  eaten  in  ignorance  of  its  true 
character,  makes  no  unpleasant  impression.  In  i'aris,  Vienna,  and  other 
cities  large  quantities  of  horses,  mules,  and  donkeys  are  slaughtered  for 
food.  It  was  formerly  diiticult  to  distinguish  horse  meat,  but  the  meat 
of  any  species  can  now  be  readily  diagnosed  by  means  of  the  specific  pre- 
cipitins.    For  this  test  see  page  589. 

The  flesh  of  fish  is  ordinarily  not  classed  as  meat,  but  it  has  the 
same  muscular  structure,  and  similar  chemical  composition  and  nutri- 
tive value  (page  839).  The  different  kinds  of  meat  may  be  detected  by 
ph3'sical,  microscopical,  chemical,  or  biological  tests.  Ordinarily  meats 
from  different  animals  may  be  distinguished  by  their  odor  or  taste. 
Microscopically  the  fibers  resemble  each  other  so  closely  that  this  test  is 
not  to  he  relied  upon.  Meat  varies  somewhat  in  chemical  composition 
from  different  species,  from  different  animals  of  the  same  species,  and 
even  from  different  muscles  in  the  same  animal.  The  principal  differ- 
ence in  the  chemical  composition  of  meats  from  animals  of  different 
species  consists  in  the  glycogen  and  fat  content.  Thus,  horse  meat  con- 
tains considerably  more  glycogen  than  beef.  The  glycogen  test,  how- 
ever, is  not  reliable  because  it  may  be  changed  as  a  result  of  bacterial 
action. 

The  fats  of  different  animals  have  different  physical  and  chemical 
characteristics.  The  fats  crystallize  in  different  forms  and  have  dif- 
ferent melting  points;  also  the  fatty  acids  derived  therefrom.  A  care- 
ful examination  of  the  fat,  therefore,  will  lead  to  an  approximate  de- 
gree of  knowledge  concerning  the  character  of  the  flesh  from  which  it 
has  been  derived.  For  instance,  lard  and  beef  fat  are  easily  distinguished 
from  each  other. 

The  Recognition  of  Spoiled  Meat.^ — The  recognition  of  spoiled  meat 
that  is  also  injurious  to  health  is  a  very  difficult  task.  Meat  that  is 
decomposed,  putrid,  or  offensive,  and  thus  objectionable  to  the  senses, 
needs  no  further  condemnation.  The  most  serious  infections  and  poi- 
sons in  meat,  however,  do  not,  as  a  rule,  affect  its  appearance,  odor,  or 
taste.  Infections  with  B.  enteritidis  or  other  bacilli  in  this  group  do  not 
alter  the  appearance  of  the  meat.  Certain  putrefactive  changes  brought 
about  by  bacterial  action,  which  givd  the  high  or  gamy  taste  so  much 
prized  by  epicures,  appear  not  to  be  injurious.  Dogs  and  other  carnivora 
prefer  putrid  flesh. 

Meat  inspectors  are  usually  instructed  to  condemn  meat  that  has 
not  a  red,  fresh  appearance,  especially  if  it  has  become  brownish  or 
greenish.  The  meat  is  to  be  condemned  if,  upon  pressure,  much  fluid 
of  abnormal  color  or  of  alkaline  reaction  exudes ;  if  the  fat  is  not  3'ellow 

^See  "Meat  Industry  and  Meat  Inspection,"  Leighton  and  Douglas. 


818  ANIMAL  POODS:    MEAT,  FISH,  EGGS,  ETC. 

and  firm,  especially  if  soft  and  gelatinous;  if  the  marrow  of  the  :?emur 
is  not  firm  and  rose-colored  and  has  become  soft  and  brownish.  Spoiled 
meat  under  the  microscope  shows  obscurity  of  the  cross  striations  of 
the  muscle  fibers  and  numerous  bacteria.  For  a  further  discussion  of 
this  subject  see  Meat  Inspection,  and  also  the  various  diseases  which 
render  meat  unsuitable  or  injurious  as  food. 

Prevention. — The  prevention  of  infections  and  poisoning  from  meat 
and  meat  products  depends,  first  of  all,  upon  the  health  of  the  animal, 
next  upon  the  mode  of  death,  and  finally  upon  the  methods  of  butchering, 
preserving  and  handling  the  flesh.  Careful  attention  to  every  detail 
is  necessary  all  along  the  line.  Cleanliness  approaching  surgical  methods 
on  the  part  of  the  butcher  during  the  preparation,  transportation,  and 
handling  of  the  meat  is  called  for.  A  careful  system  of  meat  inspec- 
tion is  a  sanitary  safeguard.  Thorough  cooking  is  the  most  important 
protection  we  have  against  infection. 

Meat  should  not  be  eaten  raw,  even  where  there  is  a  carefully  con- 
ducted inspection  by  trained  experts.  Individual  cysticerci  (tapeworm 
larvae)  are  very  easily  overlooked,  and  one  is  enough  to  bring  forth  a 
tapeworm.  It  is  also  not  possible  to  examine  all  hogs,  particularly  those 
slaughtered  in  country  districts,  for  trichina,  and  even  where  this  is 
done  with  care  the  method  does  not  afford  complete  protection.  It  is 
again  emphasized  that  some  of  the  more  serious  bacterial  infections  do 
not  alter  the  color,  taste,  or  appearance  of  the  meat  in  any  way.  Eaw 
meat  does  not  have  a  higher  nutritive  value  than  cooked  meat,  but  may 
be  more  easily  digested. 

Special  measures  of  prevention  will  be  discussed  under  each  in- 
fection. 

Meat  Preservatives. — The  regulations  of  the  U.  S.  Department  of 
Agriculture  permit  the  addition  to  meat  or  meat  food  products  of  the 
following  substances:  common  salt,  sugar,  wood  smoke,  vinegar,  pure 
spices,  saltpeter,  and  benzoate  of  soda,  which  must  be  declared  on  the 
label.  Only  such  coloring  matters  as  may  be  designated  by  the  Secretary 
of  Agriculture  may  be  used. 

The  adulterants  most  commonly  used  in  meats  are  saltpeter,  boracic 
acid,  borax,  sulphite  of  soda,  and  benzoic  acid  (page  741). 

MEAT  INSPECTION' 

The  purpose  of  meat  inspection  is  to  eliminate  diseased  or  other- 
wise bad  meat  from  the  food  supply;  to  see  that  the  preparation  of 
meats  and  meat  products  is  cleanly;  to  guard  against  the  use  of  harm- 

*  Collateral  reading:  Edlemann,  "Meat  Hygiene."  Translated  by  Mohler 
and  Eichhorn,  Lea  &  Febiger,  1911.  Ostertag,  "Handbuch  der  Fleischbeschau," 
Stuttgart,  8th  Edition,  1914. 


MEAT  819 

ful  dyes,  preservatives,  chemicals,  or  other  deleterious  ingredients;  to 
prevent  the  use  of  false  and  misleading  names  or  statements  on  labels: 
in  short,  to  protect  the  health  and  the  rights  of  the  consumer.  Sanitary 
and  economic  principles  arc  the  underlying  factors  in  sound  food  in- 
spection service.  The  necessity  for  this  inspection  is  accentuated  by 
the  fact  that  the  producer  and  consumer  are  often  separated  by  great 
distances,  and  further  there  are  often  several  middlemen  between  the 
two.  A  good  system  of  food  inspection  is  doubly  necessary  in  the  case 
of  meat  and  milk,  because  of  all  foods  they  are  most  apt  to  carry  in- 
fections and  are  so  readily  decomposable. 

An  efficient  meat  inspection  system  is  not  only  of  advantage  to  man, 
but  is  the  means  of  detecting  and  preventing  disease  among  cattle,  sheep, 
and  swine.  A  sharp  outlook  at  the  slaughter  house  will  discover  the 
first  appearance  of  rinderpest,  foot-and-mouth  disease,  Texas  fever,  or 
other  epizootic,  which  may  then  be  quickly  traced  to  its  origin  and 
nipped  in  the  bud.  Foci  of  herd  diseases,  such  as  tuberculosis,  actino- 
mycosis, and  hog  cholera  may  thus  be  located.  A  meat  inspection  service 
is  therefore  of  great  economic  importance  and  an  effective  agency  in 
eradicating  dangerous  diseases  from  the  food  herds  of  the  country. 

The  border  line  between  health  and  disease  is  ill-defined.  It  is 
doubtful  whether  any  animal  slaughtered  for  food  is  wholly  sound. 
Parasitic  infections  among  the  lower  animals  are  exceedingly  common. 
Anyone  may  convince  himself  of  this  fact  by  a  visit  to  a  slaughter 
house,  for  there  he  will  see  that  many  hogs  have  a  handful  of  round 
worms  in  the  intestinal  tract;  most  animals  have  one  or  more  species 
of  intestinal  worms,  such  as  hookworms,  tapeworms,  and  many  protozoa, 
but,  fortunatel)^,  these  are  for  the  most  part  not  dangerous  to  man. 
Almost  every  hog  or  beef  that  is  killed  contains  Sarcosporidia,  small  para- 
sites that  inhabit  the  muscles  of  these  animals;  they  are  harmless  to 
man.  Meat  inspection  aims  to  eliminate  those  diseases  which  are  in- 
jurious to  man  and  those  diseases  and  conditions  which  render  the  meat 
of  inferior  quality  or  otherwise  unfit  for  use.  In  establishing  correct 
principles  to  guide  a  meat  inspection  service  sentiment  must  give  way 
to  science.  The  killing  of  animals  and  dressing  of  the  carcasses  is  not 
a  kid-glove  business.  It  involves  more  or  less  blood  and  dirt.  In  our 
country  much  good  meat  has  been  condemned  and  destroyed  according 
to  law  as  a  result  of  supersensitiveness.  As  meat  becomes  scarcer  and 
prices  higher,  this  waste  will  be  checked  by  closer  adherence  to  a  sound 
application  of  pathology. 

The  practices  of  meat  inspection  vary  in  different  countries,  de- 
pending upon  the  local  conditions.  Thus,  in  some  countries,  which  have 
long  had  a  scarcity  of  meat,  and  the  people  are,  therefore,  flesh  hungry, 
much  meat  is  passed  for  food  that  would  here  be  condemned.  In  coun- 
tries where  meat  is  not  very  abundant  it  is  even  necessary  for  the 


820  AKIMAL  FOODS:    MEAT,  FISH,  EGGS,  ETC. 

officials  to  keep  a  sharp  watch  to  prevent  the  people  from  eating  meat 
known  to  be  injurious.  In  America  the  attitude  is  very  different,  for 
we  have  a  repugnance  even  against  meat  known  to  contain  a  harmless 
parasite.  The  need  of  conservation,  especially  since  the  World  War,  has 
placed  our  meat  inspection  service  on  a  more  practical  basis,  without 
sacrificing  good  standards. 

The  Federal  Meat  Inspection  System  depends  for  its  authority  upon 
the  interstate  and  foreign  commerce  clause  of  the  Constitution  of  the 
United  States,  and  this  inspection  is  therefore  limited  to  the  products 
of  establishments  that  are  engaged  in  interstate  or  foreign  commerce. 
The  Federal  Government  is  powerless  to  exercise  any  supervision  over 
an  establishment,  the  meat  of  which  is  slaughtered,  prepared,  sold  and 
consumed  entirely  within  a  single  state.  It  is  therefore  the  duty  of 
each  state  or  municipality  to  supplement  the  Federal  Inspection  Service 
with  an  efficient  local  inspection  system  to  cover  the  intra-state  supply. 

A  meat  inspection,  service  should  have  for  its  object  first  of  all  the 
protection  of  the  consumer  against  diseased  or  other  injurious  qual- 
ities contained  in  the  meat.  This  should  be  accomplished  with  as  little 
waste  of  food  products  as  practicable,  and,  finally,  the  meat  should  be 
honestly  labeled  so  that  the  consumer  may  know  just  what  he  is  buying. 

The  Abattoir. — So  long  as  animals  are  permitted  to  be  slaughtered 
in  any  barn  or  cellar  it  is  impossible  to  exercise  a  proper  control  over 
meat  and  meat  products,  and  conditions  which  endanger  the  public  health 
will  prevail.  The  first  essential  of  a  good  meat  inspection  service  is 
to  concentrate  all  slaughtering  in  large  central  sanitary  abattoirs.  This 
simplifies  the  inspection  and  sanitary  control,  and  is  a  needed  measure 
to  protect  the  consumer.  In  Germany  and  England  public  abattoirs 
have  been  established  which  belong  to  the  city.  These  structures  are 
built  thoroughly  of  brick  and  concrete  and  are  well  protected  against 
rats.  They  are  situated  near  a  railroad,  so  as  to  facilitate  transporta- 
tion, and  are  so  constructed  that  they  may  be  kept  clean.  Each  person 
who  wishes  to  slaughter  must  obtain  a  permit  and  pay  rent.  In  the 
entire  city  of  Paris  there  are  only  three  slaughter  houses.  The  erection 
and  maintenance  of  well  controlled,  modern  slaughter  houses  is  one 
of  the  needs  of  our  country,  especially  in  the  smaller  towns,  and  until 
this  reform  is  accomplished  we  shall  never  have  a  satisfactory  solution 
of  the  meat  problem. 

An  abattoir  must  be  especially  well  constructed  and  kept  clean.  The 
same  may  be  said  of  the  trucks,  drays,  and  all  objects  that  come  in 
contact  with  the  meat.  Slaughtering  and  butchering  involves  more  or 
less  blood  and  dirt,  hence  the  necessity  of  frequent  and  repeated  clean- 
ing. The  water-closets,  toilet  rooms,  and  dressing  rooms  should  be  en- 
tirely separated  from  the  departments  in  which  the  carcasses  are  dressed 
or  meat   products  handled   or   prepared.      Attention   must   be  paid   to 


MEAT  821 

eliminate  all  sources  of  odor  that  may  contaminate  the  meat,  and  every 
effort  must  be  made  to  keep  out  flies  and  other  vermin,  especially  rats 
and  mice.  Dogs  should  not  be  allowed  around  slaughter  houses  on  ac- 
count of  the  danger  of  spreading  the  echinococcus  and  other  parasites. 
The  feeding  of  hogs  on  the  uncooked  refuse  of  slaughter  houses  should 
not  be  permitted. 

The  employees  themselves  must  be  cleanly  and  should  wear  clean 
outer  clothes  that  may  be  readily  laundered.  The  federal  regulations 
even  prescribe  that  employees  shall  pay  particular  attention  to  the  clean- 
liness of  their  boots  and  shoes.  It  is  just  as  important  to  wash  the  hands 
before  beginning  work,  and  to  be  particular  after  each  visit  to  the  toilet 
in  the  slaughter  house  or  butcher  shops,  as  it  is  in  the  milk  industry. 
Persons  with  tuberculosis  or  other  communicable  disease  should  not  be 
permitted  in  any  department  of  the  work  where  the  meat  or  meat  products 
are  handled  or  prepared  in  any  way.  It  is  important  that  butchers  who 
handle  a  diseased  carcass  should  thoroughly  cleanse  their  hands  of  all 
grease  and  then  immerse  them  in  a  good  disinfecting  solution.  Butchers' 
implements  used  on  diseased  carcasses  should  be  sterilized  in  boiling  water 
or  strong  carbolic  acid  or  formalin  solution  and  thoroughly  cleansed 
before  they  are  again  used.  The  federal  meat  inspectors  are  required  to 
furnish  their  own  implements  for  their  own  dissection  or  examination  of 
diseased  carcasses  or  unsound  parts.  The  precautions  required  in  an 
abattoir  and  butcher  shop  are  based  on  the  same  principles  as  those  in 
a  surgical  clinic.  Meat  that  falls  upon  the  floor  or  otherwise  becomes 
soiled  is  required  to  be  removed  and  condemned.  Inflation  by  air  from 
the  mouth  should  not  be  permitted,  inflation  by  mechanical  means  is 
also  prohibited  by  the  Department  of  Agriculture.  Only  good,  clean, 
and  wholesome  water  and  ice  should  be  used  in  the  preparation  of  the 
carcasses,  and  the  wagons  and  cars  and  all  surfaces  with  which  the 
meat  comes  in  contact  should  be  kept  clean  and  in  good  sanitary  con- 
dition. There  is  no  objection  to  the  use  of  the  skin  and  hoofs  of  animals 
condemned  on  account  of  tuberculosis  and  other  diseases  (except  an- 
thrax) communicable  to  man,  provided  they  are  disinfected.  Each  skin 
and  hide  must  be  immersed  for  not  less  than  five  minutes  in  a  5  per 
cent,  solution  of  liquor  cresolis  compositus  or  a  5  per  cent,  solution  of 
carbolic  acid  or  a  1-1,000  solution  of  bichlorid  of  mercury. 

Every  complete  abattoir  must  be  provided  with  a  retaining  room  or 
place,  a  condemned  room,  and  a  tank  room.  The  retaining  room  or 
place  is  set  apart.for  the  final  inspection  of  all  carcasses  and  parts  which 
the  inspector  desires  to  examine  more  carefully  at  his  leisure.  The  re- 
taining room  must  be  large  enough  to  have  carcasses  hang  separately, 
furnished  with  abundant  light,  and  provided  with  sanitary  tables  and 
other  necessary  apparatus.  The  condemned  room  must  be  securely  rat- 
proof  and  be  under  the  lock  and  seal  of  the  inspector.     The  object  of 


822  ANIMAL  FOODS:    MEAT,  FISH,  EGGS,  ETC. 

this  room  is  to  contain  all  carcasses  and  parts  of  carcasses  until  they  can 
be  tanked  or  disposed  of  in  accordance  with  instructions. 

All  condemned  carcasses  or  parts  of  carcasses  are  tanked  under  special 
requirements  in  an  official  abattoir.  Tanking  consists  in  exposing  the 
carcasses  to  steam  under  a  pressure  of  not  less  than  40  pounds,  having  a 
temperature  of  288°  F.,  and  maintained  not  less  than  six  hours.  This 
effectively  renders  the  contents  of  the  tank  unfit  for  food  purposes.  In 
the  absence  of  tanking  facilities  the  condemned  meat  may  be  slashed 
with  a  knife  and  then  denatured  with  crude  carbolic  acid,  kerosene,  or 
other  agent,  when  it  may  be  removed  to  some  other  establishment  having 
proper  tanking  facilities. 

Qualifications  of  a  Meat  Inspector. — A  corps  of  thoroughly  trained 
meat  inspectors  is  one  of  the  most  important  links  in  the  chain  of  an 
efficient  meat  inspection  system.  A  meat  inspector  should  be  a  quali- 
fied veterinarian  having  special  experience  and  training  for  his  specialty. 
He  must  know  the  anatomy  of  the  various  food-producing  animals, 
especially  cattle,  horses,  swine,  sheep,  and  also  fowl,  and  must  be  ac- 
quainted with  the  normal  parts  of  each.  He  must  be  able  to  distinguish 
between  the  various  organs  of  the  various  species,  so  that  he  cannot  be 
imposed  upon  by  those  who  would  like  to  substitute  one  for  another. 
He  must  know  how  to  examine  animals  during  life,  in  order  to  deter- 
mine whether  they  are  healthy.  He  must  know  the  character  of  all 
the  infectious  diseases  which  are  likely  to  pass  through  the  district  where 
he  is  situated.  The  government  recognizes  that  it  requires  a  high  degree 
of  skill  to  conduct  this  work,  and  it  has,  therefore,  placed  the  meat  in- 
spection service  under  the  Civil  Service,  and,  further,  will  admit  veter- 
inarians only  if  graduates  of  recognized  veterinary  colleges.  In  addition 
they  are  required  to  pass  a  Civil  Service  examination.^ 

The  Freibank  or  Three-Class  Meat  System. — In  Germany  and  certain 
other  European  countries  meats  are  divided  into  three  classes,  viz.,  a 
first  class,  including  meats  which  are  passed  for  unrestricted  trade;  a 
second  class,  or  Freibank  meats,  which  are  allowed  on  the  market  under 
certain  restrictions;  and  a  third  class,  meats  which  are  condemned  and 
thus  excluded  from  the  food  supply. 

The  federal  meat  inspection  system  of  our  country  has  been  a  two- 
class  meat  system,  that  is,  meats  coming  to  inspection  are  either  passed 
for  unrestricted  trade  or  they  are  condemned  and  thus  excluded  from 
use  as  a  food.  However,  a  third  class  was  recognized  during  the  World 
War,  and  the  amount  of  such  meat  passed  after  it  is  sterilized  by  steam 
now  carries  us  well  towards  the  three-class  system. 

The  following  carcasses  or  parts  of  carcasses  may  be  rendered  into 

"There  is  also  a  large  force  of  "Lay  Inspectors"  experienced  in  curing,  can- 
ning, packing  and  otherwise  preparing  of  meats  and  experienced  in  the  inspection 
of  products. 


MEAT  823 

lard  or  tallow  or  passed  for  food  after  sterilization,  provided  tiie  disease 
is  moderate  and  limited,  and  then  oidy  after  the  lesions  and  surround- 
ing parts  are  removed  and  condenuied :  Cysticercus  bovis  (beef  tape 
worm);  cysticercus  cellulosae  in  hogs;  cysticercus  ovis  in  sheep;  case- 
ous lymphadenitis;  tuberculosis;  hog  cholera  and  swine  plague;  icterus, 
if  not  the  result  of  infection  or  intoxication  and  provided  discoloration 
disappears  on  chilling;  advanced  pregnancy  showing  signs  of  parturi- 
tion, also  carcasses  showing  signs  of  having  given  birth  to  young  Avithin 
10  days,  and  in  which  there  is  no  evidence  of  septic  infection.  (See  Bu- 
reau Animal  Industry  Order  211.)  Any  of  the  above  must  be  plainly 
labeled  to  show  that  the  product  is  second-class  grade  or  quality.  The 
carcass  or  the  part,  as  well  as  the  can  or  container,  must  be  plainly  and 
conspicuously  labeled  "PREPARED  FROM  MEAT  PASSED  FOR 
STERILIZATION." 

The  system  of  the  German  Fi-eihank  and  the  compulsory  declaration 
of  the  condition  of  inferior  meats  are  very  old.  The  municipal  laws  of 
Augsburg  as  long  ago  as  1276  prescribed  that  inferior  meat  could  not 
be  sold  without  giving  notice  as  to  its  quality.  In  1404  the  municipal 
laws  of  Wimpfen  provided  that  the  Freibanh  (from  the  German  frei, 
free,  here  in  the  sense  of  unconnected  or  separate,  and  hanh,  a  counter 
or  stall)  should  be  situated  three  paces  away  from  the  regular  counters. 
The  Freihanh  is,  therefore,  a  counter  which  is  free  or  separate  from 
the  counters  on  which  the  first  class  meats  are  sold.  The  term  "Finnen- 
tank"  is  sometimes  used  for  these  special  meat  stalls  because  measly 
meat  or  ''finneges  Fleiscli"  especially  is  sold  at  these  places.  This  sys- 
tem of  the  Freihanh  has  been  extended  quite  generally  in  Germany  and 
is  rapidly  extending  in  France,  Belgium,  Italy,  and  other  European 
countries.  Meat  from  tuberculous  animals,  from  animals  containing 
cysticerci  (the  larval  stage  of  tapeworms),  trichinous  meat,  and  meat 
that  would  otherwise  be  injurious  if  eaten  raw,  but  is  entirely  safe 
as  far  as  these  infections  are  concerned  wdien  thoroughly  cooked,  is  first 
sterilized  by  steam  before  it  is  placed  upon  the  Freihanh.  It  has  been 
the  more  or  less  general  experience  that  the  introduction  of  the  Freihanh 
system  has  at  first  been  met  with  by  prejudice  from  various  sides,  but 
it  is  also  the  experience  that  this  prejudice  gradually  wears  off,  and  that 
in  some  places  the  demand  for  this  meat  becomes  greater  than  the  supply. 
In  any  event,  no  large  quantity  of  such  meat  should  be  sold  to  any  one 
purchaser,  so  as  to  prevent  its  being  used  to  any  great  extent  in  boarding 
houses  and  restaurants. 

Emerg-ency  Slaughter. — In  Germany  the  system  known  as  emergency 
slaughter  or  Kothscldachtung  has  developed  to  large  proportions.  Ani- 
mals that  are  sick  or  injured  are  killed,  examined,  and,  if  suitable  for 
food,  are  labeled,  inspected,  and  passed.  In  this  way  much  valuable 
foodstuff  is  saved  that  would  otherwise  be  lost.     It  is  said  that  over 


824  ANIMAL  FOODS:    MEAT,  FISH,  EGGS,  ETC. 

1  per  cent,  of  the  animals  killed  for  food  in  Germany  come  under  this 
emergency  rule.  The  meat  of  animals  killed  under  the  emergency  laws 
is  so  labeled  and  sold  as  second  quality.  There  is  also  a  certain  amount 
of  what  may  be  termed  emergency  slaughter  going  on  in  the  local  un- 
inspected slaughter  houses  of  America,  but  it  is  not  countenanced  by  law, 
and  is,  therefore,  done  in  secrecy.  Since  1914  emergency  slaughter  has 
been  permitted  under  our  Federal  Meat  Inspection  Service,  subject, 
however,  to  carefully  stated  restrictions. 

Methods  of  Slaughter, — In  slaughtering,  the  principal  indications 
are:  (1)  a  sudden  and  painless  death;  (2)  an  immediate  withdrawal 
of  the  blood;  (3)  removal  of  intestines  and  hair  or  hide;  (4)  immediate 
cooling.  Animals  should  be  kept  without  food  for  at  least  12  hours 
before  slaughter.  Sheep  and  hogs  are  usually  hung  by  the  hind  feet  and 
the  large  vessels  of  the  neck  dexterously  cut  with  a  shar.p  knife  and 
with  a  single  motion  of  the  hand.  Cattle  are  usually  first  stunned  by  a 
blow  upon  the  head,  then  hung  up  by  the  hind  legs  and  bled. 

The  Jewish  method  of  slaughtering  is  regarded  by  many  as  superior 
to  any  other.  It  consists  in  cutting  all  the  large  vessels  of  the  neck  with 
one  cut  of  a  long,  keen  knife.  The  method  is  part  of  a  ritual  which 
includes  an  inspection  of  the  animal  and  its  organs  for  evidence  of  dis- 
ease, according  to  the  Mosaic  laws.  This  is  the  oldest  system  of  meat 
inspection.  According  to  Dembo  **  it  is  the  most  rational  from  a  hygienic 
standpoint,  since  the  animal  is  bled  rapidly  and  completely,  and  the 
convulsive  movements  cause  the  meat  to  be  more  tender  and  of  more 
attractive  appearance.  Eigor  mortis  comes  on  more  quickly,  and  the 
meat  is,  therefore,  more  quickly  available  for  use,  and  also  will  keep 
several  days  longer  than  ordinarily. 

A  process  of  slaughtering  originating  in  Denmark  appears  to  have 
borne  the  test  of  trial  in  a  very  satisfactory  manner,  and  recommends 
itself  for  adoption  in  the  tropics,  where  meats  decompose  with  exceed- 
ing rapidity.  The  animal  is  shot  in  the  forehead  and  killed,  or  stunned, 
and  as  it  falls  an  incision  is  made  over  the  heart  and  the  ventricle 
is  opened  for  two  purposes :  to  allow  the  blood  to  escape  and  to  admit 
of  the  injection  of  a  solution  of  salt  through  the  blood  vessels  by  the 
aid  of  a  powerful  syringe.  The  process  requires  but  a  few  minutes, 
and  the  carcass  may  be  cut  up  at  once. 

The  common  methods  of  killing  fowl  intended  for  the  market  are 
either  by  bleeding,  by  dislocation  of  the  neck,  or  by  chopping  off  the 
head.  When  the  neck  is  stretched  and  dislocated  the  skin  •  remains 
unbroken  and  no  bruised  effect  is  produced,  but  most  of  the  blood  in  the 
body  drains  into  the  neck  and  remains  there.  In  killing  a  fowl  by  bleed- 
ing the  common  procedure  is  to  string  it  up  by  the  legs  with  the  head 

^Deutsche  Yierteljahresschrift  filr  offentliche  Gesundheitspflege,  XXVI, 
p.  688. 


MEAT  825 

hanging  downward.  The  operator  then  gives  it  a  shar})  hl(jw  with  a 
stick  on  the  hack  of  the  head,  and  when  he  has  stunned  it  hy  this  means 
he  inserts  a  sharp  knife  into  the  roof  of  the  mouth,  penetrating  the 
brain.  He  also  severs  the  large  vessels  of  the  throat  ])y  rotating  the 
knife,  and  the  hird  ra]ii(IIy  l)lccds  to  death. 

The  United  States  Meat  Inspection  Law. — The  Federal  Meat  Inspec- 
tion Law,  approved  June  30,  1906,  provides  for  the  inspection  of  cattle, 
sheep,  goats,  and  swine,  the  meats  or  meat  food  products,  w'hich  are 
to  enter  into  interstate  or  export  trade.  It  is  administered  by  the  Bureau 
of  Animal  Industry  under  the  direction  of  the  Secretary  of  Agriculture. 
It  should  be  remembered  that  the  Federal  Meat  Inspection  Law  applies 
only  to  meat  and  meat  products  sold  in  interstate  commerce  or  for  export 
trade,  and  does  not  apply  to  meats  butchered,  dressed,  and  sold  within 
the  state.  In  accordance  with  our  dual  form  of  government,  the 
inspection  of  meat  that  is  slaughtered,  dressed,  and  sold  within  the 
borders  of  a  single  state  is  left  entirely  to  the  authority  of  that  state.  It 
is  not  until  some  of  this  meat  passes  the  state  line  that  it  enters  inter- 
state traffic  and  comes  under  the  provisions  of  the  federal  law.  Some 
of  the  states  have  passed  laws  similar  to  the  federal  law  to  protect 
their  own  citizens.  In  this  way  a  more  or  less  uniform  method  of  meat 
inspection  is  gradually  extending  throughout  the  country. 

The  Federal  Meat  Inspection  Law  provides  for  inspection  of  animals 
before  and  after  they  are  slaughtered ;  also  inspection  of  all  the  meat  and 
products  processed,  prepared  or  stored  in  the  plant.  It  exercises  super- 
vision and  control  in  respect  to  the  kinds  of  preservatives  used  and  over 
the  marking  and.  labeling  of  products,  including  the  special  marking  of 
carcasses  and  meats  which  are  held  for  further  inspection,  and  of  those 
condemned.  Custody  is  maintained  of  all  condemned  carcasses  and  prod- 
ucts, and  their  destruction  supervised.  Eegulations  for  the  maintenance 
of  sanitary  condition  throughout  the  plant  and  for  the  cleanly  handling 
of  meats  and  products  are  prescribed  and  enforced.  The  regulations 
prescribe  an  inspection  substantially  the  same  for  meats  which  are  im- 
ported.'^ 

Ante-mortem  Inspection. — A  careful  ante-mortem  examination  or  at 
least  an  inspection  of  all  cattle,  sheep,  swine,  goats,  etc.,  about  to  be 
slaughtered  should  be  made  by  a  competent  veterinarian.  Any  animal 
showing  symptoms  of  or  suspected  of  being  infected  with  a  disease  or 
condition  which  would  probably  cause  its  condemnation  when  slaugh- 
tered should  be  set  aside.  These  animals  should  then  be  slaughtered 
separately  in  a  place  provided  for  this  special  purpose.  If  necessary 
tlie  temperature  of  the  animal  may  be  taken  in  the  ante-mortem  examina- 
tion, although  due  allowance  must  be  made  for  rise  in  temperature  due 

'  Xevertheless  an  immense  amount  of  meat  slaughtered,  shipped,  sold  and 
consumed  wholly  within  a  single  state  comes  under  Federal  inspection. 


826  ANIMAL  FOODS:    MEAT,  FISH,  EGGS,  ETC. 

to  excitement  and  undue  exertion,  especially  in  hogs.  Animals  com- 
monly termed  "downers"  or  crippled  animals  are  set  aside  and  slaugh- 
tered separately. 

Post-mortem  Inspection. — The  post-mortem  inspection  is  nothing 
more  or  less  than  a  well-conducted  autopsy.  The  head,  tongue,  tail, 
thymus  gland,  and  all  viscera,  and  also  the  blood  and  all  parts  used 
in  the  preparation  of  food  and  medicinal  products  should  be  retained 
in  such  a  manner  as  to  preserve  their  identity  until  the  post-mortem 
examination  is  completed.  It  is,  of  course,  impracticable  to  formulate 
rules  to  cover  all  conditions  and  diseases,  and  much  must,  therefore,  be 
left  to  the  judgment,  experience,  and  training  of  the  veterinary  inspector 
in  charge.  Carcasses  or  parts  of  carcasses  with  the  following  diseases 
or  conditions  are  condemned,  depending  upon  circumstances :  anthrax, 
pyemia  and  septicemia,  vaccinia,  rabies,  tetanus,  malignant  epizootic 
catarrh,  hog  cholera  and  swine  plague,  actinomycosis,  caseous  lympha- 
denitis, tuberculosis,  Texas  fever,'  parasitic  icterus,  hematuria,  mange 
or  scab,  trichinosis,  tapeworms,  infections  that  may  cause  meat  poison- 
ing, icterus,  uremia,  and  sexual  odor,  urticaria,  melanosis,  tumors, 
bruises,  abscesses,  liver  flukes,  and  other  parasites,  emaciation  from 
anemia,  immaturity,  milk  fever,  and  railroad  sickness.  A  few  of  these 
diseases  deserve  brief  mention. 

Tuberculosis. — Tuberculosis  is  exceedingly  common  in  cattle  and 
is  becoming  more  and  more  prevalent  among  hogs.  A  preponderating 
percentage  of  all  carcasses  condemned  as  unfit  for  food  is  so  condemned 
on  account  of  tuberculosis.  Thus,  under  Federal  meat  inspection,  40,- 
793  cattle,  or  0.372  per  cent.,  and  59,74:0  swine,  or  0.168  per  cent.,  were 
condemned  on  account  of  tuberculosis  in  the  fiscal  year  1918.  In  the 
same  year  10,586  cattle  and  88,915  swine  affected  with  localized  or 
limited  tuberculosis  were  passed  for  sterilization  after  removal  of  all 
affected  parts.  Tuberculosis  is  important,  not  alone  because  so  many 
food  animals  are  infected  with  it,  but  because  it  presents  a  peculiarly 
difficult  problem  for  the  meat  inspector.  The  fundamental  thought  in 
determining  whether  to  pass  or  condemn  meat  of  a  tuberculous  animal 
is  that  it  should  not  contain  tubercle  bacilli,  and  should  not  be  im- 
pregnated with  toxic  substances  of  tuberculosis  or  associated  with  septic 
infection.  If  the  lesions  are  localized  and  not  numerous,  if  there  is 
no  evidence  of  distribution  of  tubercle  bacilli  throughout  the  blood,  and 
if  the  animals  are  well  nourished  and  in  good  condition,  there  is  no 
reason  to  suspect  that  the  flesh  is  unwholesome,  and  it  is  permitted 
to  be  used  after  the  removal  of  the  infected  portions.  Just  when  tu- 
berculosis should  be  considered  localized  or  generalized,  from  the  stand- 
point of  meat  inspection,  is  frequently  a  difficult  question  to  determine. 
Fortunately,  the  danger  from  this  source  is  not  very  great,  as  tuberculosis 
of  muscle  is  exceedingly  rare,  and  the  further  safeguard  of  cooking  is 


MEAT  827 

sufficient  to  kill  the  tubercle  bacilli,  provided  the  meat  is  thoroughly 
cooked  throughout.  The  relation  of  bovine  tuberculosis  to  human  tuber- 
culosis has  been  discussed  on  page  IGG. 

Tuberculosis  of  cattle  shows  itself  in  four  primary  lesions:  (1)  the 
retropharyngeal  lymph  nodes,  (2)  the  lungs  and  associated  lymph  nodes, 
(3)  the  mesenteric  lymph  nodes,  and  (4)  the  liver.  From  the  retro- 
pharyngeal nodes  the  process  extends  to  the  cervical  lymph  nodes  and 
also  to  the  anterior  mediastinal  lymph  nodes.  When  this  group  of 
glands  alone  is  infected  the  disease  may  be  considered  as  localized. 
From  the  mesenteric  lymph  nodes  the  infection  frequently  reaches  the 
peritoneum,  and  from  the  bronchial  lymph  nodes  the  pleura.  The  newly 
formed  growth  in  the  peritoneal  or  pleural  cavities  may  be  enormous 
in  amount.  It  is  often  suspended  from  the  omentum  in  great  grape-like 
masses  (Perlsucht),  or  the  intestines  may  be  plastered  with  tubercles. 
In  these  cases  the  animal  otherwise  may  be  in  good  condition ;  that  is, 
the  disease  is  still  outside  the  vital  organs  and  the  tubercle  bacilli 
have  not  invaded  the  blood  stream.  In  Germany  it  is. permitted  to  cut 
off  such  growth  and  allow  the  meat  to  go  into  consumption.  In  our 
country  the  meat  of  such  animals  is  rejected. 

For  practical  purposes  it  is  necessary  to  formulate  definite  rules 
for  the  guidance  of  the  veterinary  inspector,  and  this  is  done  with  minute 
particularity  in  the  regulations  of  the  Bureau  of  Animal  Industry  in  the 
case  of  tuberculosis.  In  general,  if  the  tuberculous  lesions  are  limited 
to  a  single  part  or  organ  of  the  body  without  evidence  of  recent  invasion 
of  tubercle  bacilli  into  the  general  circulation,  the  diseased  parts  are 
removed  and  the  remainder  of  the  carcass  is  passed  for  use.  If  the 
animal  suffered  from  fever  before  it  was  killed  or  is  cachetic,  anemic, 
and  emaciated,  or  if  the  lesions  are  generalized,  especially  if  the}^  exist 
in  two  or  more  body  cavities,  or  if  the  lesions  are  found  in  the  muscles, 
intermuscular  tissues,  bones,  or  joints,  or  if  the  lesions  are  multiple, 
acute,  and  actively  progressive,  the  carcass  is  condemned.  Carcasses 
which  reveal  lesions  more  severe  or  more  numerous  than  those  de- 
scribed for  carcasses  to  be  passed,  but  not  so  severe  or  numerous  as  the 
lesions  described  for  carcasses  to  be  condemned,  may  be  rendered  into 
lard  or  tallow  or  otherwise  sterilized  in  accordance  with  the  regulations, 
when  the  distribution  of  lesions  is  such  that  all  parts  containing  tubercu- 
lous lesions  can  be  removed. 

Anthrax. — All  carcasses  showing  lesions  of  anthrax,  regardless  of 
the  extent  of  the  disease,  are  condemned  and  immediately  incinerated. 
This  includes  the  hide,  hoofs,  horns,  viscera,  fat,  blood,  and  all  portions 
of  the  animal.  The  killing  bed  upon  which  the  animal  was  slaughtered 
must  then  be  disinfected  with  a  10  per  cent,  solution  of  formalin,  and 
all  knives,  saws,  and  other  instruments  that  have  come  in  contact  with 
the  infection  must  be  boiled  or  otherwise  disinfected. 


828  ANIMAL  FOODS:    MEAT,  FISH,  EGGS,  ETC. 

Hog  Cholera  and  Swine  Plague. — Carcasses  showing  well-marked 
and  progressive  lesions  of  these  diseases  in  any  organ  or  tissue  are 
condemned.  If  the  lesions  are  slight  and  limited  they  may  be  passed 
for  sterilization.     Man  is  not  susceptible  to  hog  cholera. 

Actinomycosis. — If  the  animal  is  in  a  well-nourished  condition  and 
the  disease  has  not  extended  from  a  primary  area  of  infection  in  the 
head,  the  head,  including  the  tongue,  is  condemned  and  the  remaining 
part  of  the  carcass  may  be  used,  but  if  the  disease  is  generalized  the 
entire  carcass  is  considered  uniit  for  human  use  and  condemned. 

Tapeworm  Cysts. — Carcasses  of  animals  affected  with  tapeworm 
cysts,  known  as  Cysticercus  hovis,  are  condemned  if  the  infestation  is 
excessive  or  if  the  meat  is  watery  or  discolored.  Carcasses  showing  a 
slight  infestation  may  be  passed  for  food  after  removal  and  condemna- 
tion of  the  cysts,  provided  the  carcasses  are  then  held  in  cold  storage 
or  pickle  for  not  less  than  21  days;  the  time  in  storage  may  be  reduced 
to  6  days  if  the  temperature  does  not  exceed  15°  F.  Calves  under  6 
weeks  old  are  not  subject  to  Cysticercus  bovis.  As  an  alternative  to  re- 
tention in  cold  storage  or  pickle,  such  carcasses  may  be  passed  for  sterili- 
zation. 

Carcasses  or  parts  of  carcasses  found  infected  with  hydatid  cysts 
(echinococcus)  may  be  passed  after  condemnation  of  the  infected  part 
or  organ. 

Septic  and  Pyemic  Conditions. — All  carcasses  of  animals  so  in- 
fected that  consumption  of  the  meat  or  meat  food  products  thereof  may 
give  rise  to  meat  poisoning  should  be  condemned.  For  the  information 
of  the  inspector  the  following  conditions  are  specified:  (1)  acute  inflam- 
mation of  the  lungs,  pleura,  peritoneum,  pericardium,  or  meninges; 
(2)  septicemia  or  pyemia,  whether  puerperal  or  traumatic  or  without 
any  evident  cause;  (3)  severe  hemorrhagic  or  gangrenous  enteritis  or 
gastritis;  (4)  acute  diffuse  metritis  or  mammitis;  (5)  polyarthritis; 
(6)  phlebitis  of  the  umbilical  veins;  (7)  traumatic  pericarditis;  (8) 
any  other  inflammation,  abscess,  or  suppurating  sore  if  associated  with 
acute  nephritis,  fatty  and  degenerated  liver,  swollen  soft  spleen,  marked 
pulmonary  hyperemia,  general  swelling  of  the  lymphatic  glands,  and 
diffuse  redness  of  the  skin,  either  singly  or  in  combination. 

It  is  required  that,  immediately  after  the  slaughter  of  any  animal 
so  diseased  as  to  require  its  condemnation,  the  premises  and  implements 
used  must  be  thoroughly  disinfected.  The  part  of  any  carcass  coming 
in  contact  with  the  carcass  of  any  diseased  animal  or  with  the  place 
where  such  animal  was  slaughtered,  or  with  the  implements  used  in 
the  slaughter,  before  thorough  disinfection  has  been  accomplished,  should 
also  be  condemned. 

Meat  poisoning  is  not  a  poisoning  at  all,  but  an  acute  infection, 
caused  in  the  majority  of  cases  by  B.  enteritidis  or  closely  allied  bacillus 


MEAT 


829 


Diseases  and  conditions  for  uyhich  condcinnatioyis  were  made  on  post-mortem  in- 
spection, fiscal  }iear  tiUl 

Heport  of  the  Chief  of  the  Bureau  of  Animal  Industry,  Annual  Report,  Dept.  of  Agriculture,  1918* 


Cattle 

Calves 

Sheep 

Goats 

Swine 

Cause  of  condemnation 

Car- 
casses 

Parts 

Car- 
casses 

Parts 

Car- 
casses 

Parts 

Car- 
casses 

Parts 

Car- 
casses 

Parts 

391 

114,571 

1 

21 

1,578 

1 

1 
13 

3 

14 

1 
4 

21 

6 

"  "23 

U 

13 

7 

861 

7 

35 

7 

1 

13 

4 

2 
1,566 

1 

43 

3 

Caseous  lymphadenitis 
Cellulitis 

31 

2 
24 

217 
435 

58 
544 

174 

IS 

4 

306 

25 

12,492 

'  "l'.433 
794 

1 

2 

36 

3 

2,041 

"    "34 

8 

9 
1 

no 

18 
4,979 

1 

19 

8 

1,666 

7 

Dropsical  diseases 



297 

7 
25 

1,037 

22 

20,967 

12 

2,109 

4 

1 

75 

106 

7 

16 

5 

Hemorrhagic  septi- 

1 

3 

1 

Icterus 

40 

57 
1,749 

762 

8 
4 

9 

775 

2 

12 

Injuries,  bruises,  etc. . . 

2,950 

437 

31 

14 

19 

2 

5 

402 

14 

16 

5 

96 
3 

"  "io 

2 

278 

11 

9 

18 

1 

8 

130 

10 

698 

128 

57 

41 

3 

5,973 

4 

1 

688 

8 

i 

131 
1,678 

2 

1 

122 

Pneumonia,  peritonitis, 
metritis,   enteritis, 
pleurisy,  etc 

Pregnancy  and  recent 
parturition 

Septicemia,    pyemia, 
uremia 

6,575 

47 

2,529 

4,000 

23 

638 

45 
6 
6 

15,363 
24 

8,773 

1 

879 

8 

588 
14 

1 

503 

477 

52 

510 

40,792 

732 

'  58,209 
2,415 

362 
210 

1 
2 

59,740 
1,158 

332,834 

Tumors  and  abscesses. 

98 

37 

6,311 

Total 

68,156 

178,940 

8,109 

2,308 

12,564 

227 

419 

1 

113,079 

347,006 

*  Regulations  of  the  Bureau  of  Animal  Industry,  Department  of  Agriculture.  A  Condensed 
Epitome  of  the  Principles  and  Practice  of  Meat  Inspection. 

Edlemaxn:  "Meat  Hj'giene."  Translated  by  Mohler  and  Eichhorn,  Lea  &  Febiger,  1911;  4th 
edition,  1919. 

O.stertag:     "Handbuch    der   Fleischbesehau."     Stuttgart,    8th    Edition,    1914. 

in  the  colon-typhoid  group.  The  subject  is  fully  discussed  on 
page  692. 

The  food  an  animal  eats  produces  distinctive  odors  or  tastes  in  its 
flesh.  Poisonous  substances  ingested  by  an  animal  may  be  deposited  in 
its  tissues  in  amounts  sufficient  to  be  poisonous  to  man.  Chickens  may 
be  accustomed  to  strychnin  in  such  large  amounts  that  this  method  is 
used  in  the  south  to  kill  the  hawks  that  prey  upon  them. 

Partridge  poisoning,  M'hich  was  apparently  quite  common  in  the  first 


830  ANIMAL  FOODS:    MEAT,  FISH,  EGGS,  ETC. 

half  of  the  eighteenth  century,  was  probably  due  to  mountain  laurel 
(Kalmia  latifolia),  which  is  eaten  by  grouse  in  the  winter  time.  The 
poisonous  principle  is  known  as  andromedotoxin,  and  Chestnut  was  able 
to  show  that  partridges  may  eat  enough  of  the  laurel  with  impunity  to 
themselves  to  render  their  flesh  poisonous. 

Miscellaneous. — In  addition  to  the  infections  noted,  the  following 
diseases  are  sometimes  transferred  from  the  flesh  or  organs  of  lower 
animals,  or  by  contact  with  the  lower  animals  in  various  ways :  tuber- 
culosis, anthrax,  glanders,  rabies,  actinomycosis,  foot-and-mouth  disease, 
cowpox,  ringworm,  and  various  pyogenic  and  septic  infections. 

Meat  may  occasionally  be  injurious  to  health  from  a  variety  of 
miscellaneous  causes.  Thus,  an  animal  that  has  died  of  arsenic  or  other 
poisonous  substance  may  contain  sufficient  of  the  poison  in  the  tissues 
to  afi'ect  the  person  who  eats  part  of  the  flesh. 

The  belief  that  sickness  in  man  can  follow  the  consumption  of  the 
flesh  or  milk  of  animals  which  have  previously  fed  upon  poisonous  plants 
is  not  unfounded.  Chestnut^  states  that  as  much  as  three  grains  per 
liter  of  formic  acid  may  be  present  in  honey,  and  that  poisons  from 
various  plants  have  been  isolated  from  honey.  Pammel  ®  furthermore 
states  that  garlic,  chicory,  cabbage  or  turnips,  when  eaten  by  cows,  im- 
part a  bad  taste  to  the  milk  and  cites  instances  of  poisoning  in  man  and 
animal  due  to  ingestion  of  the  milk  from  animals  which  had  eaten 
colcliicum,  mandrake,  and  the  death  camas  (Zygadenus  venenosns). 

ANIMAL  PARASITES 

Trichinosis. — TricJimella  spiralis,  formerly  Trichina  spiralis,  com- 
monly known  as  trichina,  is  a  round  worm  which  passes  its  entire  life 
cycle  in  man,  rat,  or  hog.  Many  other  animals,  such  as  mice,  foxes, 
guinea-pigs,  rabbits,  cats,  dogs,  etc.,  are  susceptible.  This  parasite  dif- 
fers from  many  other  animal  parasites  in  affecting  several  genera  and 
in  passing  its  entire  life  cycle  in  each  host.  Trichinosis  is  rare  in  ani- 
mals which  do  not  eat  meat. 

Trichiniasis  (usually  called  trichinosis)  is  not  a  mere  medical  curi- 
osity. It  is  a  common  and  important  disease,  readily  preventable.  The 
average  mortality  is  about  half  that  of  typhoid  fever,  in  some  epidemics, 
however,  rising  to  16  or  even  30  per  cent.,  as  in  the  Hedersleben  epi- 
demic ^°  in  1865.  The  parasites  are  found  in  from  0.5  to  2  per  cent, 
of  all  necropsy  subjects.^^  About  1  to  2  per  cent,  of  American  swine 
and  a  larger  per  cent,  of  American  rats  are  infected. 

"Science,  XV,  1902,  1016. 
'  Manual  of  Poisonous  Plants,  Vol.  I,  p.  65. 
^°  Cited  by  Staubli,  Trichinosis,  Wiesbaden,  1909,  p.  16. 

"Williams  found  evidence  of  infection  in  5.3  per  cent,  of  505  consecutive 
autopsies  in  Buffalo,  N.  Y. 


MEAT  831 

The  larvae  are  imbedded  in  the  muscles.  When  the  trichinous  meat 
is  taken  the  capsules  are  dissolved  in  the  stomach,  the  larvae  set  free; 
the  freed  larvae  enter  the  intestine,  where  they  find  conditions  favorable, 
and  where  in  about  two  days  they  grow  into  the  full  mature  worm.  The 
female  produces  upward  of  five  hundred  young,  and  as  she  is  partially 
imbedded  in  the  wall  of  the  intestine  is  able  to  deposit  her  embryos 
directly  in  the  lymph  spaces  in  the  intestinal  mucosa.  The  embryos 
get  into  the  blood  stream  and  are  thus  distributed  to  the  muscles. 
They  may  be  found  in  large  numbers  in  the  circulating  blood,  between 
the  eighth  and  twenty-fifth  days  after  infection.  After  settling 
down  in  the  muscles,  the  young 
parasites  increase  rapidly  in  size, 
reaching  a  length  of  about  1  mm., 
assume  their  characteristic  spiral 
form,  and  become  encysted,  the 
formation  of  the  cyst  beginning 
about  a  month  after  infection. 
The  adult  worms  usually  disap- 
pear from  the  intestines  in  5  or 
6  weeks,  or  even  sooner  if  the  pa-      ^„  ^^swine 

tient    has    diarrhea.      Calcification         t7       do     rr.  o      .    „ 

Fig.    82. — Teichinella    Spiralis. 

of    the    capsules    surrounding    the  Entire  Life  Cycle  in  Each  Host, 

encysted    larvae    in    the    muscles 

may  begin  as  early  as  six  months  after  infection.  The  parasites  may 
remain  alive  for  many  years  in  calcified  capsules,  but  sooner  or  later 
if  the  host  remains  alive  the  parasites  die  or  are  absorbed  or  themselves 
become  calcified. 

Some  authorities  consider  rats  to  be  the  normal  or  common  host  of 
TrichmeUa  spiralis,  others  believe  that  the  hog  is  the  only  important 
reservoir  of  the  parasite,  and  that  in  the  absence  of  hogs  the  parasite 
would  be  unable  to  perpetuate  itself  among  rats.  It  is  a  well  known 
fact  that  rats  about  slaughter  houses,  and  butcher  shops  are  commonly 
infested  with  trichinae,  and  though  it  is  questionable  to  what  extent 
rats  are  responsible  for  the  spread  of  infection  to  hogs,  the  possibility 
of  their  importance  in  this  respect  cannot  be  disregarded.  Clearly  im- 
portant sources  of  infection  for  hogs  are  the  carcasses  of  dead  hogs,  oft'al 
from  slaughter  houses,  and  refuse  or  garbage  containing  pork  scraps. 
(Infection  through  feces  has  never  been  proved,  and  it  is  quite  unusual 
if  it  ever  occurs.)  Man  receives  the  infection  by  eating  trichinous  pork 
(occasionally  dog,  cat,  or  bear  meat).  The  country  slaughter  houses, 
where  hogs  are  fed  on  human  feces  and  the  offal  of  slaughtered  animals 
and  where  rats  abound,  are  the  most  important  factors  in  the  propaga- 
tion of  the  infection. 

JSTot  all  persons  who  eat  trichinous  flesh  have  the  disease.     A  limited 


833  ANIMAL  FOODS:    MEAT,  FISH,  EGGS,  ETC. 

number  of  the  embryos  do  not  cause  noticeable  symptoms.  The  number 
of  encysted  larvae  that  may  be  present  in  severe  infestations  is  very  large. 
As  many  as  1,20(J  have  been  counted  in  a  piece  of  muscle  weighing  1 
gram,  which  would  make  about  500,000  in  a  pound.  The  number  of 
encysted  larvae  present  in  the  bodies  of  persons  who  have  died  from 
trichinosis  has  been  estimated,  in  various  cases,  at  from  5,000,000  to 
100,000,000.  The  severity  of  the  disease  depends  upon  the  number  of 
live  embryos  swallowed.  In  man  the  disease  is  well  characterized  in  two 
stages:  (1)  gastro-intestinal,  (2)  general  infection.  The  symptoms  of 
the  second  stage  are  fever,^^  intense  pain  in  the  muscles  caused  by  the 
migration  of  the  parasites,  edema,  and  leukocytosis.  The  count  of  the 
white  cells  may  reach  30,000  with  distinct  eosinophilia.  One  attack  of 
trichinosis  does  not  confer  an  immunity.  Schwartz  ^^  has  shown  that 
experimental  animals  infected  and  harboring  trichinae  in  th^eir  muscles 
are  not  immune  to  further  infection  when  fed  trichinous  meat. 

The  recognition  of  trichinosis  as  a  distinct  infection  is  recent  (1860). 
The  parasite  was  named  by  Richard  Owen  (1835)  and  was  long  re- 
garded as  harmless  and  as  a  curiosity.  The  infection  was  mistaken 
for  typhoid  fever,  rheumatism,  acute  miliary  tuberculosis,  and  other 
diseases  of  common  occurrence.  The  particular  case  which  finally  re- 
vealed the  parasite  as  being  capable  of  harm  was  that  of  a  young  woman 
admitted  to  the  hospital  at  Dresden  suffering  from  a  disease  diagnosed 
as  typhoid  fever.  The  patient  had  agonizing  pains  in  the  muscles,  and  the 
autopsy  revealed  the  parasite  imbedded  in  vast  numbers  in  the  muscular 
fibers.  Leidy  in  1846  had  announced  the  discovery  of  trichinae  in 
pork  and  in  the  present  case  an  investigation  included  the  examination 
of  some  pork  of  which  the  patient  had  eaten  four  days  before  the  first 
symptoms  appeared,  with  the  result  that  the  same  parasites  were  found. 
Since  then  many  local  outbreaks  have  been  described,  more  particularly 
in  Germany,  where  the  custom, prevails  of  eating  raw  or  underdone  pork, 
especially  in  sausage. 

As  an  indication  of  the  prevalence  of  trichinae  it  may  be  noted  that 
microscopists  of  the  U.  S.  Department  of  x^griculture  found  living 
trichinae  in  115,812  hogs  out  of  8,257,928  examined  during  the  period 
1898-1906,  or  1.41  per  cent.,  from  which  it  would  appear  that  from  1 
to  3  per  cent,  of  the  hogs  in  this  country  are  trichinous.  The  disease 
in  man  is  probably  more  prevalent  than  the  figures  of  the  clinicians  in- 
dicate. Careful  search  at  autopsy  showed  that  many  persons  have  been 
infected  but  have  recovered.  Thus,  Williams,^*  of  Buffalo,  examined 
505  cadavers  (largely  from  almshouses  and  insane  hospitals  so  his  ma- 
terial cannot  be  considered  to  represent  a  fair  average  of  the  population) 

'^  Trichinella  spiralis  is  the  only  metazoic  parasite  that,  infecting  man, 
causes  fever  with  constancy. 

"J.  A.  M.  A.,  Sept.  15,  1917. 

^*  Journal  Medical  Research,  July,  1901,  VI,  No.  1,  p.  64. 


MEAT  833 

and  found  the  jtanisitcs  present  in  "^'7,  or  5.34  per  cent.  Osier  states 
that  al)out  one-half  to  Iwo  per  cent,  of  all  hodies  at  autopsy  contain 
trichinae. 

Preveniiun. — The  disease  is  practically  never  recognized  in  swine 
during  life.  The  protection  rendered  by  the  inspection  of  meat  is  quite 
unsatisfactory.  This  inspection  consists  in  compressing  small  fragments 
of  the  muscle  (diaphragm,  tongue,  etc.)  between  two  glass  plates,  which 
are  then  examined  with  a  low  power  of  the  microscope  for  the  encysted 
larvae.  That  this  examination  is  not  an  entirely  satisfactory  safeguard, 
even  in  cases  where  it  is  done  with  care  and  precision,  is  shown  by  the 
fact  that  in  Germany,  for  example,  the  disease  is  still  very  common. 
Of  the  6,329  cases  of  trichinosis  occurring  in  Germany  between  1881  and 
1898,  over  32  per  cent.  (2,042  cases)  were  traced  by  Stiles  to  meat  which 
had  been  inspected  and  passed  as  free  from  trichinae.  The  microscopic 
inspection  of  every  carcass  for  trichina  is  expensive  and  open  to  several 
practical  sources  of  error.  It;  therefore,  gives  a  false  sense  of  security 
and  is  impractical  in  country  slaughter  houses. 

Our  federal  meat  inspection  regulations  no  longer  require  a  micro- 
scopic examination  of  pork  for  trichina.  Until  recently  all  the  pork 
dressed  for  export  was  examined  by  the  microscopic  method,  but  this 
has  also  been  discontinued. 

The  Y.  S.  Bureau  of  Animal  Industry  issues  the  following  warning: 

"Xo  method  of  inspection  has  yet  been  devised  by  which  the  pres- 
ence or  absence  of  trichinae  in  pork  can  be  determined  with  certainty, 
and  the  Government  meat  inspection  does  not  include  inspection  for  this, 
parasite.  All  persons  are  accordingly  v^arned  not  to  eat  pork,  or  sausage 
containing  pork,  whether  it  has  been  officially  inspected  or  not,  until 
after  it  has  been  properly  cooked. 

"A  temperature  of  about  160°  F.  kills  the  parasite,  therefore  pork 
when  properly  cooked  may  be  eaten  without  danger  of  infection.  Fresh 
pork  should  be  cooked  until  it  becomes  white  and  is  no  longer  red  in 
color  in  all  portions  of  the  piece,  at  the  center  as  well  as  near  the  surface. 
Dry-salt  pork,  pickled  pork,  and  smoked  pork  previously  salted  or 
pickled,  provided  the  curing  is  thorough,  are  practically  safe  so  far 
as  trichinosis  is  concerned,  but  as  the  thoroughness  of  the  curing  is  not 
always  certain,  such  meat  should  also  be  cooked  before  it  is  eaten." 

The  trichinae  are  not  particularly  resistant.  The  thermal  death 
point  of  trichina  larvae  is  55°  C.^^  As  a  factor  of  safety,  the  Bureau 
of  Animal  Industry  requires  137°  F.  (58.33°  C.)  as  the  minimum 
temperature  to  which  pork  and  products  containing  pork  are  required 
to  be  heated  when  cooked   in  establishments   operating  under   Federal 

"Ransom  and  Schwartz:  Journ.  Agricul.  Research.  XVII.  5,  Au».  15.  1919. 
Ransom.  B.  H.,  Schwartz,  B..  and  Raffensberger,  H.  B.:  EflFects  of  Pork-Curing 
Processes  on  Trichinae.    Bull.  Xo.  880,  U.   <b'.  Dept.  of  Agriculture.  Sept.  1(1.  1920. 


834  ANIMAL  FOODS:    MEAT,  FISH,  EGGS,  ETC. 

meat  inspection.     The  requirement  refers  to  the  temperature  actually 
reached  in  the  interior  of  the  meat  (pages  695  and  750). 

Trichina  larvae  die  in  less  than  20  days  at  a  temperature  not  higher 
than  5°  F.  Eansom  ^^  disproved  the  notion  formerly  held  that  the  larvae 
of  Tnchinella  spiralis  are  very  resistant  to  cold.  He  recommends  that 
meat  should  be  refrigerated  at  a  temperature  not  higher  than  5°  F.  for 
not  less  than  30  days,  a  period  which  allows  a  probable  margin  of 
safety  of  10  days.  Whether  temperatures  higher  than  5°  F.  may  be 
safely  employed  by  lengthening  the  period  of  refrigeration,  remains 
to  be  determined.  It  is,  therefore,  evident  that  refrigeration  and  time 
are  better  safeguards  than  microscopic  examination,  although  there  are 

various  practical  diffi- 
Man  (Tenia  Solium)  ^^^j^lgg  ^^  ^  Universal 

refrigeration  of  pork 
at  the  low  tempera- 
ture required  to  kill 
trichinae.  The  com- 
bination of  refrigera- 
tion and  thorough 
cooking  would  protect 
Man  man  against  trichino- 

Swine  (Cystieereut  Ctlluloaae)      gjg 

(Cyatleereua  Oelluloaae) 

The    rat    and    the 
Fig.  83. — Taenia  Solium,  the  Pork  or  Measly         , 

Tapeworm.  hog      should      be      re- 

mote that  man  may  infect  liimself.  garded  as  the  common 

reservoir  of  trichinae; 
a  persistent  warfare  should  be  made  against  rats  in  slaughter  houses, 
butcher  shops,  markets,  and  places  where  hogs  are  kept  (see  page 
328),  Hogs  should  not  be  fed  uncooked  offal  from  slaughter  houses, 
and  on  the  farms  should  not  be  allowed  to  eat  the  carcasses  of  dead  hogs. 
The  Pork  or  Measly  Tapeworm  {Taenia  Solium). — Taenia  solium 
passes  the  larval  stage  of  its  life  history  in  the  flesh  of  pork.  These 
encysted  larvae  are  known  as  bladder  worms  or  Cysticercus  cellulosae; 
they  are  commonly  called  pork  measles.  Man  eats  these  encysted  larvae 
which  develop  into  adult  tapeworms  in  the  intestinal  tract. 

Infection  with  this  tapeworm  may  be  particularly  dangerous,  be- 
cause the  cysticerci  may  occur  in  man  as  well  as  in  the  hog.  When  the 
cysticerci  develop  in  important  parts,  such. as  the  eye,  brain,  etc.,  death 
or  serious  consequences  may  ensue.  The  infection  with  this  particular 
tapeworm  is  fortunately  rare  in  the  United  States  and  Canada,  but  is 
more  frequently  met  with  in  the  old  world.  ^  The  adult  tapeworm  occurs 
only  in  man ;  the  larva  is  found  especially  in  hogs  and  occasionally  in 

"Science,  New  York,  January  30,  1914,  Vol.  XXXIX,  p.  181,  and  The  Journal 
of  Agricultural  Research,  Vol.  V,  No.  18,  January  31,  1916. 


MEAT  835 

man.  Tliis  parasite  is  smaller  than  the  beef  tapeworm.  The  head  is 
armed  with  a  double  row  of  hooks,  with  which  it  maintains  its  hold  to 
the  mucous  membrane.  Each  link  contains  a  uterus  with  lateral 
branches,  and  the  genital  pore  is  marginal  and  irregularly  alternate. 

The  source  of  infection  in  man  is  practically  always  the  larvae  in 
undercooked  or  raw  pork.  Occasionally  the  cysticerci  develop  in  man  ; 
in  this  case,  the  iiircctiOii  is  contracted  from  another  ])erson  through 
the  eggs  in  the  feces.  Auto-infection  also  occurs.  Hogs  become  in- 
fected from  eating  human  feces  containing  the  eggs,  or  from  food  and 
drink  contaniinaled  ^\  ilh  them.  To  build  a  privy  over  the  pig  pen^  as  one 
sometimes  sees  in  the  country,  means  the  formation  of  an  endless 
chain  in  the  biology  of  this  worm. 

Taenia  solium  produces  less  anemia  than  the  fish  tapeworm  ( Dibo- 
ihrioceplialus  latus) ,  but  may  be  dangerous  because  of  cysticercus  forma- 
tion in  man.  This  is  the  only  tapeworm  in  which  tliis  occurs.  A  person 
infected  with  Taenia  solium  may  reinfect  himself  through  dirty  finger 
nails,  imwashed  hands,  or  other  uncleanly  habits,  and  it  is  also  compara- 
tively easy  to  infect  others  through  the  feces. 

In  prevention  one  must  first  consider  the  disposal  of  feces.  Hogs 
heavily  infected  should  be  destroyed ;  those  having  a  light  infection  may 
be  thoroughly  cooked  and  the  meat  eaten.  As  the  larvae  of  Taenia 
solium  appear  to  be  more  tenacious  of  life  than  those  of  Taenia  saginata 
and  survive  longer  after  the  death  of  their  host,  the  holding  of  meat 
for  a  period  of  21  days  in  refrigeration  or  in  brine  as  practiced  in  the 
case  of  beef  slightly  infested  with  Taenia  saginata  larvae  is  a  method 
that  cannot  be  utilized  for  destroying  vitality  of  the  larvae  of  Taenia 
solium  in  pork. 

Taenia  Saginata. — Taenia  saginata,  also  called  T.  mediocan-ellata,  oc- 
curs only  in  cattle  and  man.  The  tapeworm  is  rather  common  in  our 
country,  but  is  not  dangerous,  like  Taenia  solium,  though  at  times  it  pro- 
duces a  certain  degree  of  anemia  and  other  symptoms.  It  is  often  difficult 
to  expel,  despite  the  fact  that  it  has  no  hooks.  In  geographical  distri- 
bution it  is  cosmopolitan.  The  adult  worm  occurs  in  man;  the  larva 
is  found  imbedded  in  beef  and  is  known  as  the  Cysticercus  hovis.  The 
uterus  has  15  to  35  slender  dichotomous  branches  on  each  side.  The 
genital  pore  is  marginal  and  irregularly  alternate. 

Eansom  ^^  concludes  that  if  measly  beef  carcasses  are  exposed  6  days 
to  a  temperature  not  exceeding  15°  F.  the  parasites  die.  Ostertag,^^  also 
Eansom,  have  found  that  cysticerci  from  beef  carcasses  held  in  cold  stor- 
age or  in  pickle  for  21  days  are  no  longer  viable. 

Man  becomes  infected  by  eating  raw  or  underdone  beef.  The  larvae 
are  most  frequently  detected  in  the  heart,  diaphragm,  and  muscles  of 

"Jour,  of  Parasitology,  Sept.  1,  1914,  No.  1. 

^^Zeitschr.  f.  Flcisch.  u.  Milchhyg.,  v.  7,  pp.  127-132,  1S97. 


836  ANIMAL  FOODS:    MEAT,  FISH,  EGGS,  ETC. 

mastication,  but  occur  throughout  the  voluntary  musculature.  Cattle 
become  infected  through  the  eggs  passed  in  human  feces,  which  con- 
taminate their  food  or  water. 

Prevention. — The  prevention  depends  first  upon  proper  disposal 
of  human  excrement  and  an  efficient  system  of  meat  inspection.  The 
cysticerci  die  in  three  weeks  after  killing,  hence  meat  that  has  been  pre- 
served 21  days  may  be  regarded  as  safe.  Proper  cooking  and  thorough 
salting  also  kill  the  larvae  of  this  tapeworm. 

Echinococcus  Disease.^ "^ The  larvae  of  a  cestode.  Taenia  echinococ- 
cus,  frequently  infests  man.  The  larvae  are  hydatids  of  a  minute  tapeworm 
of  the  dog.     The  adult  worm  in  the  intestinal  tract  of  the  dog  is  not 

more  than  four  or  five  millimeters  long 

Man    {Tenia  Sagtnatta)  „  „ 

and  consists  of  three  or  four  segments 
of  which  the  terminal  one  alone  -is  mature. 
The  head  is  small  and  provided  with 
four 'sucking  disks,  and  a  rostellum  with 
a  double  row  of  booklets.  The  terminal 
or  mature  segment  contains  about  5,000 
eggs.  The  eggs  are  passed  in  the  feces 
and  then  infest  various  animals,  particu- 
larly  the  hog   and    ox,   more   rarely   the 

Cattle  J  b  >  J 

(Cystieercus  Bouis)  horse    and    sheep.      The   egg   hatches    in 

YiG.  84. Beef  Tapeworm.         ^he  digestive  tube,  liberating  an  embryo 

which  pierces  the  mucosa  and  lodges  in 
the  ^'arious  tissues  and  organs  of  the  body,  where  it  develops  into  the 
larval  or  cystic  stage  (hydatids). 

The  disease  prevails  especially  in  those  countries  where  man  is 
brought  in  close  contact  with  the  dog,  but  more  especially  when,  as  in 
Australia,  the  dogs  are  used  to  herd  sheep.  The  dog  gets  the  larvae 
from  the  sheep.  In  the  dog  the  tapeworm  reaches  maturity  in  the 
intestinal  canal,  and  the  eggs  are  passed  in  the  feces  to  infect  sheep, 
man,  and  other  animals.  In  this  country  Taenia  ecliinococcus  is  rarely 
found  in  the  dog,  but  it  is  not  a  very  rare  parasite,  as  its  cystic  stage 
is  rather  frequently  encountered  in  the  liver  of  hogs  by  Federal  meat 
inspectors.  The  larva  imbeds  itself  in  the  tissues  and  there  develops 
a  cyst— the  hydatid  cyst.  This  may  occur  in  the  liver,  lungs,  abdominal 
organs,  nervous  system,  in  fact  in  almost  any  part  of  the  body.  The 
cysts  grow  in  size  as  the  larvae  multiply,  forming  daughter  cysts  and 
grand-daughter  cysts. 

The  first  essential  in  prophylaxis  is  to  protect  the  dog  against  infec- 
tion. This  resolves  itself  into  a  good  system  of  meat  inspection,  sani- 
tary slaughter  houses,  proper  disposal  of  offal,  and  the  keeping  of  dogs 

"  Echinococcus  disease  is  not  contracted  by  man  from  meat — but  is  con- 
veniently considered  in  this  chapter  with  the  other  tapeworms. 


FISH  837 

away  from  slaui;litor  liousi-s,  luitrlicr  slnips.  iciidoring  plants,  and  the 
like.  ]f  olTal  is  iisdl  as  food  for  dotrs.  hoi^s  ami  otlior  animals  it  slioiild 
first  be  thoro uglily  boilod. 

The  eggs  of  the  worm  reach  the  mouth  of  man  directly  and  indirectly 
from  the  dog  in  various  ways — through  drinking  water,  through  food 
soiled  with  dog  feces,  through  dirty  hands.  Dogs  lick  their  anal  region 
and  also  lick  fcial  matter,  and  hence  may  directly  transmit  the  eggs 
to  man  through  licking  and  fondJing.  In  an  infested  region,  drinking 
water  should  bo  ))()iled  ;  likewise  all  vegetables.  Fruits  and  berries,  espe- 
ciall}'  those  from  near  the  ground,  should  be  thoroughly  washed  before 
being  eaten.  Sheep  and  other  herbivora  become  infected  from  dogs  in 
ways  entirely  similar  to  those  of  man,  and  the  principle  of  prophylaxis 
is  the  same. 

The  number  of  dogs  should  be  diminished,  especially  stray  dogs, 
which  show  a  high  percentage  of  infection.  The  control  of  the  number 
of  dogs  and  their  habits  would  also  help  with  the  rabies  problem.  The 
better  management  of  slaughter  houses  would  not  only  help  control 
echinococcus  disease,  but  also  trichinosis  through  rats. 


FISH 

In  nutritive  properties,  there  is  little  difference  between  the  muscle 
of  fish  and  that  of  beef.  In  other  words,  fish  is  meat  although  ordinarily 
not  so  regarded,  Drummond  -^  found  that  the  coagulable  proteins  of 
muscle  tissue  of  the  cod,  herring  and  canned  salmon  have  a  nutritive 
value  as  high  as  those  derived  from  beef;  in  fact,  many  fish  contain  con- 
siderable quantities  of  fat  distributed  throughout  their  muscle  tissue, 
and  thus  probably  serve  as  a  valuable  source  of  the  "unknown  dietary 
factor" — "fat-soluble  A."  The  herring  and  also  cod  liver  oil  are  rich 
in  this  vitamin.  Fish  resem.bles  "meat"  in  that  both  are  poor  in  "water- 
soluble  B."  There  is,  then,  no  essential  difference  in  nutritive  value  be- 
tween fish  and  the  flesh  of  food  mammals. 

Fish  poisoning  or  ichthyotoxismus  is  most  frequent  in  Eussia.  Japan, 
and  the  West  Indies,  and  other  seacoast  countries  in  which  fish  forms 
a  large  part  of  the  diet.    It  occurs  especially  in  warm  countries. 

Physiological  Fish  Poisoning.— Some  fish  are  always  poisonoiis,  that 
is,  normally  contain  a  substance  toxic  to  man ;  usually  the  poison  is  de- 
veloped only  during  the  spawning  season.  Various  species  of  the  tefrodon 
and  diodon,  which  includes  the  puffers,  balloon  fish  and  globe  fish,  fre- 
quently cause  serious  and  fatal  poisoning  in  Japan.  The  most  poisonous 
is  perhaps  the  fugu.  In  Tokio  alone  680  fatal  cases  out  of  93.3  were 
reported  occurring  in  1885-1892  from  the  so-called  "fugu."  In  China 
^Joxirn.  Physiol,  52,  95,  1918. 


838  ANIMAL  FOODS:    MEAT,  FISH,  EGGS,  ETC. 

and  Japan  such  fish  are  sometimes  taken  for  suicidal  purposes.  The 
active  principle  in  fugu  poisoning  resembles  curara.  The  poison  is  found 
.mainly  in  the  head,  liver  and  ovaries,  and  called  '''fugin."  It  is  not  de- 
stroyed by  boiling.  Its  chemical  nature  has  not  been  determined.  The 
symptoms  produced  are:  dyspnea,  cyanosis,  dilatation  of  the  pupils,  re- 
laxation of  the  sphincters,  paralysis  of  speech,  dizziness,  salivation,  and 
vomiting.     Death  may  result  in  one  or  two  hours. 

Few  fish  containing  physiological  poisons  are  found  outside  of  the 
tropics.  Some  fish,  such  as  shad  and  smelts,  are  preferred  during 
spawning  season.  However,  during  spawning  season  the  roe  of  differ- 
ent members  of  the  sturgeon  family,  of  the  pike,  and  the  barbel  have 
been  said  to  cause  pronounced  and  even  fatal  intoxication;  the  symp- 
toms resemble  those  of  gastro-enteritis.  x\nchovy  belassa  and  the  mel- 
tite  of  the  Indian  Ocean  are  both  said  to  be  poisonous,  the  former  caus- 
ing death  when  only  small  amounts  are  taken,  the  latter  causing  violent 
vomiting.  The  Greenland  shark  causes  an  intoxication  in  dogs  similar 
to  that  caused  by  alcohol.  A  certain  degree  of  tolerance  can  be  produced 
by  feeding  graded  amounts.  The  roe  of  the  European  barbel  produces 
the  so-called  "barbel  cholera,'^  while  the  roe  of  the  pike  is  said  to  be 
poisonous  during  the  spawning  season.  The  toxic  symptoms  are  said 
by  Pozzi-Escot  to  occur  in  not  less  than  24  hours  after  ingestion.  The 
smooth  puffer  (Lagocephalus  levigatus)  is  considered  by  fishermen  to 
be  the  most  poisonous  of  the  fishes  of  Brazil.  Very  little  is  known  con- 
cerning the  nature  of  physiological  fish  poisons. 

Bacterial  Poisons. — Bacterial  poisoning  from  fish  occurs.  The  fish 
may  be  diseased,  or  when  caught  may  be  healthy,  but  the  bacteria  gain 
access  and  grow  throughout  the  meat  as  the  result  of  contamination 
or  imperfect  preservation.  Bacterial  diseases  among  fish  are  rather 
common  and  often  occur  as  epizootics.  In  almost  all  the  reported 
instances  of  injurious  action  resulting  from  bacteria  the  fish  has  been 
eaten  raw.  Bacteria  may  form  poisonous  substances  in  fish  closely 
resembling  botulism.  Fish  caught  by  the  gills  in  nets  die  slowly  and 
decompose  rapidly.  They  are  of  inferior  flavor  and  value  and  are  more 
liable  to  be  injurious  than  fish  taken  from  the  water  and  killed  at  once ; 
under  such  circumstances  they  remain  firm  and  retain  their  flavor  longer 
than  those  that  die  slowly.  In  some  parts  of  the  world  live  fish  in  tanks 
are  offered  for  sale  in  the  markets.  This  procedure  cannot  be  com- 
mended from  a  sanitary  standpoint,  for  the  tanks  are  apt  to  become 
dirty  and  the  fish  liable  to  sicken  and  die  slowly,  so  that  the  object  of 
purveying  only  live,  fresh,  and  wholesome  fish  is  largely  defeated.  It  is 
well  known  that  fish  decompose  readily  and  should,  therefore,  be  handled 
in  a  cleanly  manner  and  used  as  fresh  as  possible.  When  refrigerated 
the  temperature  should  be  low  (page  731). 

"Fish  poisoning"  is  doubtless  sometimes  due  to  a  toxin  produced 


FISTT 


839 


^->3     - 


V 


/^^ 


Ay 


by  BjU'illus  botiilinus,  or  a  similar  anar-robe.  Konstansoff-^  isolated  an 
anai'Tobic  organism  from  fisb  which  liad  caused  poisoiiino:,  and  which 
he  called  B.  ichthyisttii.  This  organism  produced  a  strong  toxin  which 
affects  chiefly  the  nervous  system.  When  administered  to  white  mice 
per  OS,  subcutaneously,  intravenously  or  intraperitoneally,  it  gives  rise 
to  the  same  symptoms  and  produces  the  same  pathologic  lesions  as 
result  from  ingestion  of  the  poisonous  fish.  This  organism  is  quite 
similar  to  B,  botulinus,  but  Konstansoff  concludes,  after  a  careful  com- 
parison of  the  two  organisms,  that  B,  ichthyismi  is  a  distinct  entity. 
The  symptoms  caused  in  mice  are 
diminution  of  secretions  and  excre- 
tions, dilation  of  the  pupils,  oph- 
thalmoplegia, clonic  and  tonic  mus- 
cular spasms,  retention  of  urine  and 
feces,  and  motor  paralysis,  which 
spreads  gradually  over  the  entire 
body,  death  resulting  from  respira- 
tory paralysis.  The  heart  is  re- 
sistant to  the  action  of  the  poison, 
being  only  slightly  decreased  in 
rate.  There  is,  therefore,  marked 
similarity  betwen  botulism  and  this 
form  of  ichthyotoxismus.  Poison- 
ing from  fish  contaminated  with 
B.  enteritidis  or  one  of  the  closely 
allied  members  of  the  colon-typhoid 

group  is  very  seldom  recorded.     Hypersensitiveness  to  fish,  in  the  sense 
of  anaphylaxis,  is  rather  common. 

The  Fish  Tapeworm.^The  principal  animal  parasite  conveyed 
through  fish  is  the  tapeworm,  Dibothriocephalus  latus,  which  infects 
man  wherever  fresh  fish  forms  a  large  part  of  the  diet.  The  larval 
stage  or  pleroc^rcoid  is  found  in  the  muscles  and  organs  of  various  fresh 
water  fish,  particularly  pike,  perch,  and  several  members  of  the  salmon 
family,  and  when  partaken  of  by  man  develops  into  the  adult  tapeworm 
in  the  intestines.  The  adult  worm  is  also  found  in  cats  and  dogs  that 
feed  upon  fish. 

The  fish  tajiewomi  produces  a  severe  anemia  resembling  pernicious 
anemia.  The  head  of  the  DihotliriocepliaJus  latus  is  armed  with  hooks 
and  attaches  itself  to  tlie  mucous  membrane  of  the  bowels.  Faust  aiul 
Tallqvist  have  shown  that  the  anemia  is  due  to  an  hemolytic  action 
caused  by  oleic  acid  found  in  tlie  head  of  the  fish  tapeworm.  Each 
link  of  the  fish  tapeworm  has  a  rosette-shaped  uterus  in  the  median  line 
and  a  special  uterine  pore  from  which  eggs  are  constantly  discharged 

^  Vestnik  Obshtshestwennoy  Hygieni,  1915,  51,  1,  p.  766. 


(larvae''^' 


Fig.  85. — Dibotheiocephalus  Latus, 
THE  Fish  TAPEwoRii. 

Produces  serious  anemia. 


840  ANIMAL  FOODS:    MEAT,  FISH,  EGGS,  ETC. 

and  may  readily  be  found  in  the  feces.  It  is  through  the  pollution  of  the 
streams  with  sewage  containing  the  eggs  that  the  fish  become  infected, 
but  the  larvae  that  hatch  from  the  eggi^,  however,  first  have  to  pass 
through  a  procercoid  stage  in  small  Crustacea  (Cyclops),  and  the 
infected  Crustacea  is  then  ingested  by  the  fish. 

The  prevention  of  infestation  with  the  fish  tapeworm  consists  in 
proper  disposal  of  feces,  so  as  to  prevent  the  contamination  of  fresh 
water  streams,  and  the  proper  cooking  of  fish. 

Paragonimus  ivestermanii,  a  fluke  (distome)  common  in  Japan  and 
other  countries,  produces  very  serious  lesions  in  the  lungs,  clinically 
resembling  tuberculosis.  The  parasite  is  contracted  through  fresh 
Avater  crabs.-" 

SHELLFISH 

Shellfish  include  mollusks,  as  oysters,  clams,  mussels,  and  crustace- 
ans, as  lobsters,  crabs,  and  shrimp.  The  conditions  which  render  such 
food  injurious  are  much  the  same  as  those  discussed  in  connection  with 
fish.  Shellfish  may  be  diseased  when  taken  from  the  water,  but  little 
is  known  of  the  diseases  of  shellfish  that  influence  men.  Shellflsh  may 
be  perfectly  good  and  wholesome  when  fresh,  but  may  become  con- 
taminated and  poisonous  on  keeping,  especially  if  not  kept  cold.  Shell 
fish  have  a  bad  reputation,  whereas  it  is  very  seldom  that  they  are 
responsible  for  illness.  Hypersusceptibility  of  these  foods  is  rather 
common,  but  in  this  case  the  trouble  is  not  with  the  food,  but  with  the 
person  who  eats  it. 

On  being  transferred  to  fresh,  clean  water  they  may  lose  these  in- 
jurious characteristics.  Man  has  made  shellfish  a  danger  to  himself 
by  polluting  the  water  in  which  they  live.  It  is  claimed  by  some 
observers  that  6  days,  by  others  that  16  days,  in  clean  water  are  suf- 
ficient for  mollusks  to  purge  themselves  of  typhoid  infection. 

It  is  now  well  known  that  oysters,  and  doubtless  other  mollusks, 
while  in  polluted  water,  may  take  up  large  numbers  of  different  kinds 
of  bacteria,  and  that  these  remain  alive  and  virulent  for  a  long  time. 
Herdman  and  Boyce  found  17,000  colonies  from  an  oyster  obtained 
from  the  neighborhood  of  a  drain  pipe.  Ordinarily  oysters  from  open 
waters  contain  less  than  100  colonies.  Oysters  contain  fewer  bacteria 
during  the  winter  months  (December  to  March),  when  they  probably 
hibernate.  Oysters  placed  in  polluted  waters  may  retain  the  typhoid 
bacillus  as  long  as  14  days  after  they  become  infected.  Klein  found 
typhoid  to  persist  in  oysters  from  2  to  3  weeks.  At  times  the  oysters 
clean  themselves  in  a  week ;  this  is  facilitated  by  clear,  clean,  running 
water.     Eecently,  it  has  been  shown  that  oysters  may  be  purified  in  24 

*^Nakagawa,  Jour.  Parasitology,  1916,  II,  3,  p.  111. 


S]I1:LLKIS1[  841 

hours  by  iuldiii.ir  MfMtli  lu  the  wnlcr  in  Mhii  h  Ihcy  aru  lloaicil.  1Mk'1])S 
fouml  (hat.  two  ilays  was  sulliriciit  to  cleanse  the  oysters.-'  The  proicss 
by  wliieli  tlio  oyster  rids  itself  of  bacteria  is  ]ierhaps  both  mechanical 
and   bioloii:ical. 

Gorham  -'  has  sliown  that  during  cold  weather  (40°  to  45°  F.) 
oysters  rest  oi-  hibernate;  the  ciliary  movement  ceases,  and  feeding  does 
not  occur;  and  tlie  oysters  become  practically  free  from  sewage  organisms 
even  when  lying  in  sewage-polluted  beds. 

Oysters  reflect  the  bacteriology  of  the  water  in  which  they  live  and 
grow.  The  l)acteria  are  found  both  in  the  oyster  and  in  the  oyster 
liquid.  Oysters  from  clean  water  contain  few^  bacteria  and  no  B.  coli; 
oysters  from  polluted  water  contain  many  bacteria  and  numerous 
B.  coli.  The  number  of  B.  coli  is  expressed  by  a  "score"  in  accordance 
with  the  method  of  the  American  Public  Health  Association,^'"'  as 
follows : 

The  presence  of  B.  coli  in  each  oyster  of  five  examined  is  given  the 
following  values,  which  represent  the  reciprocals  of  the  greatest  dilutions 
in  which  the  test  for  7?.  coli  is  positive: 

If  present  in  1  c.c.  but  not  in  0.1  c.c,  the  value  of  1. 

If  present  in   n.l   cc.,  but  not  in  0.01  c.c,  the  value  of   10. 

If  present  in  0.01  c.c,  but  not  in  0.001  c.c,  the  value  of  100,  etc 

The  addition  of  these  values  for  five  oysters  would  give  the  total 
numerical  ^■aUle  for  the  sample  and  this  figure  would  be  the  score  for 
B.  coli. 

Oysters  scoring  less  than  50  are  usually  passed  as  satisfactory, 
whereas  those,  scoring  over  140  are  regarded  as  polluted  by  sanitary 
authorities. 

Both  typhoid  and  cholera  have  been  convincingly  traced  to  infected 
oysters.  The  oysters  may  become  infected  where  they  grow  or  during 
the  process  of  ''fattening''  or  "floating,"  which  consists  in  soaking  them 
in  fresh  water  for  the  purpose  of  making  them  more  plump  and  increas- 
ing their  size.  In  the  language  of  the  fishermen,  this  is  called  "float- 
ing," "plumping,"  "drinking,"  or  "laying  out."  On  account  of  the 
difference  in  osmotic  pressure  the  water  enters  the  cells  of  the  oysters 
and  certain  mineral  salts  pass  out.  ^Vhile  the  oyster  increases  in  size 
and  weight  it  is  at  the  expense  of  the  natural  salt,  mostly  sodium  chlorid, 
which  the  oyster  contains.  Floating  is  practiced  by  the  majority  of 
oyster  growers,  partly  from  necessity,  for  purchasers  do  not  seem  to 
realize  that  an  oyster  in  its  natural  condition  is  never  very  thick  and 
has  a  slightly  greenish  color. 

It  may  be  stated,  as  a  general  rule,   that  oysters  and  other  shell- 

"^  Public  Health  Reports,  July  14.  1916;  also,  Carmelia,  ibid..  XXXtl;  16, 
April  22.  1921. 

"Gorham,  F.  P.:     Am.  Jour.  Pub.  Health.  1912,  II,  24. 
"  J.TO.  Jour,  of  Public  Health,  II,  1912,  34. 


842  ANIMAL  FOODS:    MEAT,  FISH,  EGGS,  ETC. 

fish  should  }iot  be  used  when  taken  from  water  which,  upon  bacteri- 
ological examination,  would  render  it  unfit  if  used  for  drinking  pur- 
poses. 

Outbreaks  of  Typhoid  Fever  Traced  to  Oysters. — At  Middletown, 
Connecticut,  Professor  Conn  ^^  showed  that  the  outbreak  of  typhoid 
fever  at  Wesleyan  University  during  1894  was  due  to  raw  oysters 
eaten  at  fraternity  banquets. 

The  increased  prevalence  of  typhoid  fever  in  Atlantic  City,  N.  J., 
during  the  summer  and  autumn  of  1902  was  traced  by  Pennington  ^^ 
and  others  to  the  use  of  oysters  and  clams  floated  in  Penrose  Canal, 
which  was  highly  polluted  w^ith  sewage. 

Dr.  Bulstrode  -^  during  1903  reported  21  cases  of  typhoid  fever  and 
118  cases  of  gastro-enteritis  from  a  total  number  of  267  guests  who 
had  eaten  raw  oysters  at  the  mayoralty  banquets  at  Winchiester  and 
Southampton,  England,  on  November  10th  of  that  year.  The  oysters 
in  question  were  imported  from  France  and  "laid  down"  or  floated 
for  a  few  days  in  sewage-polluted  "drinking"  grounds  at  Emsworth. 
One  patient  who  developed  a  fatal  case  of  typhoid  ate  only  one  infected 
oyster,  w^hile  others  ate  only  two  or  three  of  these  oysters. 

During  the  period  from  1894  to  1902,  inclusive.  Dr.  Newsholme,  of 
Brighton,  England,  investigated  241  cases  of  typhoid  fever  which  he 
ascribed  to  eating  infected  shellfish.-^ 

During  the  year  1902,  Thresh  and  Wood  ^°  reported  in  the  county  of 
Essex,  England,  4  cases  of  typhoid  fever  and  21  cases  of  illness  due 
to  eating  Portuguese  oysters  sold  on  x\ugust  14  and  21  of  that  year. 

Soper,^^  1905,  showed  that  21  out  of  31  cases  of  typhoid  fever  at 
Lawrence,  Long  Island,  N.  Y.,  could  be  traced  to  eating  oysters  and 
clams  which  had  been  floated  or  grown  in  Jamaica  Bay,  near  Inwood, 
Long  Island. 

Netter  ^^  reported  33  cases  of  typhoid  fever  due  to  eating  oysters 
from  Cette  in  1907.  The  cases  were  very  virulent  in  character,  7  of 
the  33  resulting  fatally. 

Stiles  ^^  investigated  an  outbreak  following  the  Minisink  banquet, 
held  at  Goshen,  N.  Y.,  on  October  5,  1911,  and  showed  conclusively  that 
the  "Eockaway"  oysters  served  on  that  occasion  were  responsible.  There 
were  17  well-defined  cases  of  typhoid  fever,  with  one  death,  and  83 
cases   of  gastro-enteritis    (diarrhea)    traced   directly   to   eating   "Eock- 

^'''Conn.  State  Board  of  Health  Eeport,  1894,  pp.  243-264. 

"Philadelphia  Medical  Journal,  Nov.  1,  1902,  pp.  634-635. 

=«' Local  Government  Board,  England.  32nd  Ann.  Report,  1902-3.  Supl. 
App.  A,  pp.  129-189. 

^Brit.  Med.  Journal,  Aug.  8,  1903,  2:  295-297. 

""The  Lancet,  Dec.  6,  1902,  2:  1567-1569. 

"^Med.  Neios,  Feb.  11,  1905,  86:  241-253. 

'^The  Lancet,  Feb.  23,  1907,  1 :  551. 

"^  U.  8.  Dept.  of  Agriculture,  Bureau  of  Chemistry,  Bulletin  No.  156,  Sept. 
21,  1912. 


SnKI>LFISTT  8i;? 

away"  oysters  from  Jamaica  Bay,  floated  at  Indian  Creek,  near  Canarsie, 
Long  Island,  N.  Y. 

Fuller  ^*  reviewed  the  literature  on  this  subject  which  covered  more 
than  20  separate  outbreaks  due  to  infected  shellfish  up  to  1904. 

In  Great  Britain  more  than  in  other  European  countries,  shellfish 
transmission  of  typhoid  fever  is  regarded  as  quite  frequent.  In  189(5, 
Newsholme,  then  health  officer  in  Brighton,  published  careful  studies 
showing  that  30  per  cent,  of  the  typhoid  infections  occurring  in  that 
city  were  due  to  oysters  and  other  shellfish.  For  Belfast,  the  investiga- 
tions of  Mair  showed  that  the  extensive  increase  of  typhoid  fever  from 
1897  to  1909  was  due  in  a  large  measure  to  infection  from  cockles 
gatliered  along  a  shore  not  far  from  the  main  sewer  outlet  (page  124). 

The  prevention  of  typhoid  and  similar  infections  through  oysters, 
clams,  and  other  shellfish  consists  in  regulating  the  location  of  the  beds 
and  in  transferring  doubtful  oysters  to  a  clean  situation  in  clear  sea 
water  until  the  bacteria  have  perished  or  have  been  washed  away.  How 
long  this  may  take  is  somewhat  doubtful ;  perliaps  a  week,  or,  better,  16 
days,  should  be  allowed.  "Floating"  in  water  of  doubtful  character 
should  be  prohibited.  Thorough  cooking  will  kill  all  these  non-spore- 
bearing  bacteria. 

Mussel  Poisoning. — Mytilus  edulis,  the  common  mussel,  is  a  source 
of  poisoning  in  England  and  on  the  Continent.  Mussel  poisoning  is  a 
comparatively  rare  occurrence.  Savage  ^^  has  summarized  the  cases 
reported  in  Great  Britain,  finding  that  from  1827  to  1909  there  were  61 
cases,  8  of  which  were  fatal — a  case  mortality  of  13  per  cent.  Figures 
for  the  Continent  and  America  do  not  seem  to  be  available,  but  in  alf 
probability  they  do  not  exceed  those  of  Great  Britain. 

The  cause  of  "mussel  poisoning"  is  not  known.  It  is  highly  probable 
that  the  trouble  comes  from  bacteria  of  intestinal  origin,  for  all  the 
mussels  which  have  caused  illness  have  invariably  come  from  sewage 
polluted  waters. 

Three  clinical  types  have  been  described:  (1)  An  erythematous 
type,  which  is  doubtless  anaphylactic  and  not  an  instance  of  actual  "poi- 
soning"; (2)  a  gastro-enteric  or  intestinal  type;  (3)  a  paralytic 
type.  The  difference  in  the  last  two  types  of  poisoning  is  one  of  degree, 
the  symptoms  apparently  varying  with  the  virulence  and  amount  of  the 
poison  and  the  susceptibility  of  the  individual. 

The  chief  symptoms  observed  ^^  have  been  referable  to  the  central 
nervous  system,  suggestive  of  a  powerful  neurotoxin  such  as  found  in 

^  U.  S.  Bureau  of  Fisheries  Rept.,  1904,  pp.  189-238. 

'^  Rep.  to  the  Loc.  Govt.  Bd.  on  Public  Health  and  Medical  Subjects,  Xo.  77, 
1913,  p.  5. 

^° Savage,  ibid.;  Osier:  "Principles  and  Practice  of  Medicine,"  1918,  p.  409; 
Thesen:  Arch.  f.  Exp.  Path.  u.  Pharmak.,  Bd.  XLVII,  Hefte  5  u.  6;  Rolfe: 
Lancet,  Aug.  27,  1904. 


844   •         AXIMAL  FOODS:    MEAT,  FISH,  EGGS,  ETC. 

botulism  and  possibly  in  iehthyotoxismus.  The  onset  of  symptoms  iisnany 
comes  shortly  after  ingestion  of  the  mussels,  but  is  sometimes  delayed 
18  to  24  hours.  The  common  symptoms  of  food  poisoning — nausea, 
vomiting,  abdominal  pain  and  diarrhea — are  usually  present,  though  they 
may  not  always  be.  Giddiness,  vertigo,  a  tingling  prickly  sensation  in 
the  hands  and  feet,  a  sense  of  constriction  and  dryness  of  the  mouth  and 
throat,  difficulty  in  speaking  and  swallowing,  a  feeling  of  numbness  about 
the  mouth,  gradually  spreading  to  the  arms,  and  great  muscular  weak- 
ness are  reported.  There  is  usually  no  fever.  The  pupils  are  dilated, 
but  react  to  light.  There  may  be  mental  excitement  very  similar  to  that 
of  the  early  stages  of  alcoholic  intoxication.  The  heart  is  not  involved, 
the  pulse  is  full  and  bounding,  but  usually  rapid.  Dyspnea,  difficult 
breathing,  swelling  of  the  face,  lack  of  muscular  coordination  and  mus- 
cular spasms  may  be  present.  Sudden  syncope  is  not  uncommon  and 
usually  immediately  precedes  death.  Death  may  occur  in  1  or  3  hours 
accompanied  by  all  the  symptoms  of  collapse. 

The  paralytic  type  suggests  curare.  This  is  less  frequent  and  more 
dangerous  than  the  gastro-enteric  types.  It  may  be  compared  with  botu- 
lism, but  differs  in  rapidity  of  onset,  the  nature  of  the  symptoms,  and 
in  the  fact  that  boiling  does  not  destroy  the  poison.  Death  has  occurred 
in  15  minutes  after  eating  boiled  mussels.  A  notable  example  of  mussel 
poisoning  occurred  at  Wilhelmshaven  in  1885.  A  large  number  of  dock 
laborers  and  their  families  were  poisoned  shortly  after  eating  cooked 
mussels;  three  died.  The  mussels  were  examined  by  Brieger  and  Sal- 
kowski,  who  isolated  several  basic  substances  or  "ptomains,''  one  of 
Avhich,  mytilotoxin,  was  poisonous  to  animals,  causing  similar  symp- 
toms. 

Mytilotoxin  (CgHjgiSI'Oa)  is  said  to  produce  the  same  symptoms  in 
animals  which  result  from  "mussel  poisoning"  in  man.  JSTovy  considers 
this  a  true  instance  of  a  heat-resisting  alkaloidal-like  poison  or  ptomain 
in  a  sense  analogous  to  mushroom  poisoning.  Cats  and  dogs  eating 
poisonous  mussels  are  said  to  suffer  with  symptoms  similar  to  those 
seen  in  man,  namely,  paralysis,  coma,  and  death.  Eabbits  have  been 
poisoned  by  giving  them  the  water  in  which  the  mussels  have  been 
cooked. 

Thesen  •"  isolated  from  mussels  taken  from  the  harbor  of  Christiania 
a  toxic  substance  which  resembles  mytilotoxin  in  some  ways.  He  has, 
however,  not  been  able  to  convince  himself  that  the  two  substances  are 
identical.  He  believes  that  the  poisonous  quality  of  the  mussels  is  not 
the  result  of  bacterial  action  or  of  pathological  metabolic  processes 
within  the  mussel,  but  rather  is  due  to  the  absorption  of  poisonous  sub- 
stances from  the  water.  He  bases  his  belief  upon  the  fact  that  clean 
mussels  when  placed  in  clean  water  to  which  has  been  added  curare, 

"Arc/i..  /.  Exp.  Path.  u.  Pharmak.,  Bd.  XLVII,  Hefte  5  u.  6. 


SHELLFISH  845 

strychnin  or  an  extract  from  jtdisoiiniis  iiiusst']s,  acquire  the  poisonous 
quality  of  the  water. 

Savage  is  impressed  with  the  incompleteness  of  our  knowledge  con- 
cerning mussel  poisoning  and  concludes  that :  ^® 

"j\Iany  explanations  have  been  advanced  to  account  for  the  causation 
of  mussel  poisoning.  These  are  carefully  reviewed  by  Bulstrode  in  his 
report  (1894-95)  to  the  Local  Government  Board  on  'Oyster  Culture  in 
Relation  to  Disease.'  The  earlier  views  ascribing  the  pathogenic  prop- 
erties to  copper  poisoning,  star-fish  spawn,  mussels  eaten  during  the 
spawning  season,  mussels  eaten  in  a  stale  or  dead  condition,  may  be 
dismissed  as  untrue  or  inadequate  as  explanations  generally  applicable 
although  metallic  poisoning  cannot  be  excluded  as  a  possible  cause  of 
illness  in  individual  cases  or  even  in  small  outbreaks. 

"The  rapidity  of  onset  and  (when  fatal)  rapidly  fatal  result  make 
it  evident  that  the  symptoms  are  due  to  a  chemical  poison,  while  the 
peculiar  symptoms  differentiate  this  type  from  the  ordinary  food  poison- 
ing outbreaks. 

"The  most  probable  view  is  that  mussels  become  poisonous  from  the 
production  in  them  of  chemical  poisons  elaborated  by  the  vital  activity 
of  bacteria  derived  from  their  sewage-contaminated  surroundings,  but 
we  are  ignorant  of  the  special  bacteria  concerned,  the  conditions  which 
cause  the  production  of  these  poisons,  and  whether  the  toxic  properties 
are  due  to  mytilotoxin  or  to  some  other  bacterial  poisons. 

"Very  few  outbreaks  appear  to  have  been  reported  in  recent  years, 
but  it  is  desirable  that  the  whole  subject  should  be  reinvestigated  by 
modern  methods."  . 

The  prevention  of  mussel  poisoning,  on  the  basis  of  present  informa- 
tion, rests  primarily  upon  the  prevention  of  sewage  pollution  of  waters 
in  which  the  mussels  grow.  Cooking  does  not  seem  to  render  them  safe. 
Rolfe  ^^  reports  two  cases,  one  of  which  was  fatal,  from  mussels  which 
had  been  carefully  washed  and  then  thoroughly  cooked  in  several  changes 
of  water.  Poisonous  mussels  *°  are  said  to  produce  a  sweetish,  nauseat- 
ing, bouillon  odor.  They  are  less  pigmented  and  their  shells  are  more 
easily  broken  than  those  of  non-poisonous  mussels.  Their  livers  are 
larger  and  more  mellow.  The  water  in  which  they  are  boiled  appears 
bluish,  while  that  of  healthy  mussels  is  light  in  color.  The  meat  of 
poisonous  mussels  is  yellow,  that  of  healthy  mussels,  whitish.  Healthy 
mussels  produce  almost  no  change  in  alcohol,  but  the  poisonous  mussels 
cause  the  appearance  of  a  deep  golden  yellow  color.  In  spite  of  these 
differences  between  healthy  and  poisonous  mussels,  there  seems  to  be 

^"Food  Poisoning  and  Food  Infections,"  Cambridge,  England.  1920,  pp. 
132-33. 

^Lancet,  Aug.  27,  1904. 

^'Edlemann,  ]\roliler,  and  Eichlinrn :  "Aleat  Hvgiene."  Lea  &.  lebiger,  1911, 
p.  350. 


846  A^MAL  FOODS:    MEAT,  FISH,  EGGS,  ETC. 

no  ready  means  by  which  the  consumer  can  tell  whether  or  not  the 
mussels  are  toxic. 

Of  interest  in  connection  with  mussel  poisoning  is  the  so-called  S7iail 
poisoning,  which  has  come  to  be  associated  with  a  certain  marine  snail 
(Murex  uradatus).  It  is  not  known  whether  this  snail,  which  is  some- 
times used  for  food,  contains,  under  certain  conditions,  a  substance 
which  is  poisonous  to  man,  w^hether  pathogenic  bacteria  are  present,  or 
whether  preformed  bacterial  toxins  are  the  cause  of  the  symptoms 
in  man. 

"BOB-VEAL" 

"Bob-veal"  is  the  flesh  of  immature  calves,  that  is,  animals  less  than 
two  or  three  weeks  old.  "Bob-veal"  is  objectionable  only  from*  humani- 
tarian and  esthetic  grounds,  not  from  a  health  standpoint.  The  preju- 
dice against  "bob-veal"  is  illogical.  The  meat  is  flabby,  edematous,  soft. 
The  connective  tissue  is  gelatinous  and  is  present  in  greater  quantity 
than  in  mature  ^.nimals.  The  fat  is  reddish-gray  and  soapy,  the  meat 
less  nutritious  in  value,  as  it  contains  a  large  proportion  of  water.  The 
digestibility  of  the  protein  of  "bob-veal"  is  the  same  as  market  veal, 
namely,  93  per  cent.  On  account  of  its  moist  and  soft  condition  "bob- 
veal"  has  a  greater  tendency  to  spoil  than  the  flesh  of  mature  animals. 
Young  calves  are  highly  susceptible  to  a  number  of  infections,  par- 
ticularly diarrheal  diseases  and  infections  which  enter  through  the  navel. 
Trouble,  however,  has  seldom  been  traced  to  "bob-veal." 

Ostertag  states :  "Putrefactive  and  pathogenic  microbes  find  ready 
media  for  luxuriant  growth  m  'bob-veal'  carcasses.  In  Switzerland 
27  persons  became  ill  from  eating  veal  of  a  calf  five  days  old,  which  had 
yellow  water  in  the  joints;  one  patient  died." 

Bollinger  recites :  "At  Berminstorf  8  people  died  from  eating  veal 
from  a  calf  four  days  old.  At  Morselle,  Belgium,  80  people  became  sick 
from  eating  veal  of  two  calves  with  diarrhea." 

It  is  a  well-known  fact  that  calves  under  three  weeks  old  have  umbili- 
cal wounds  which  are  liable  to  become  infected.  All  young  animals  are 
subject  to  such  infections,  since  nature  is  left  to  effect  the  healing  of  the 
wound.  The  weight  of  the  calf  is  often  taken  as  an  indication  of  its 
age.  Thus  a  calf  weighing  40  pounds  or  more  is  considered  mature, 
but  the  weight  is  a  poor  index  of  age.  The  condition  of  the  umbilical 
wound  usually  tells  the  tale.  There  are  no  sanitary  objections  to  the 
use  of  "bob-veal" ;  infections  may  be  guarded  against  by  care,  inspection 
and  finally  by  thorough  cooking. 


EGGS  847 

EGGS 

Perhaps  no  article  of  diet  of  animal  origin  is  more  commonly  eaten 
in  all  countries  and  served  in  a  greater  variety  of  ways  than  eggs. 
Eggs  are  used  in  nearly  every  household  in  some  form  or  other.  It 
has  been  calculated  that  on  an  average  they  furnish  3  ])er  cent,  of  the 
total  food^  5.9  per  cent,  of  the  total  protein,  and  4.3  per  cent,  of  the 
total  fat  Wf^vd  j)er  man  per  day.  When  we  speak  of  eggs  we  ordinarily 
mean  hen's  eggs,  but  the  eggs  of  dncks,  geese,  and  guinea  fowls  are 
used  to  a  greater  or  less  extent;  more  rarely  turkey's  eggs  and  some- 
times those  of  wild  birds.  Plover  eggs  are  prized  in  England  and 
Germany,  while  in  this  country  the  eggs  of  sea  birds,  such  as  gulls, 
terns,  herons,  and  murres,  have  long  been  gathered  for  food.  Other 
eggs  besides  those  of  birds  are  sometimes  eaten.  Turtle's  eggs  are  highly 
prized  in  most  countries  where  they  are  abundant.  The  eggs  of  the 
terrapin  are  usually  served  with  the  flesh  in  some  of  the  ways  of  prepar- 
ing it  for  the  table.  Fish  eggs,  especially  those  of  the  sturgeon,  are 
jDreserved  in  salt  under  the  name  of  caviar.  Shad  roe  is  also  a  familiar 
example  of  the  use  of  fish  eggs  as  food.  The  eggs  of  alligators,  lizards, 
serpents,  and  some  insects  are  eaten  by  races  who  lack  the  prejudices 
of  western  nations. 

Very  large  quantities  of  eggs  are  now  broken  out,  mixed,  frozen,  or 
dried.  These  products  are  largely  employed  by  bakers  and  others  who 
use  eggs  in  quantities. 

Hen's  eggs  vary  considerably  in  size  and  appearance.  The  shell 
constitutes  about  11  per  cent.,  the  yolk  32  per  cent,,  and  the  white 
57  per  cent,  of  the  total  weight  of  the  egg.  The  egg-shell  consists  mainly 
of  carbonate  of  lime,  and  when  freshly  laid  is  covered  by  a  mucous  coat- 
ing. The  egg-white  consists  of  86.2  per  cent,  of  water,  12.3  per  cent, 
nitrogenous  matter,  0.2  per  cent,  fat,  and  0.06  per  cent  ash.  The  yolk 
consists  of  49.5  per  cent,  water,  15.7  per  cent,  nitrogenous  matter,  33.3 
per  cent,  fat,  and  1.1  per  cent,  ash.*^  These  are  averages;  different  eggs 
vary  somewhat  in  composition  from  each  other.  It  is  noteworthy  that 
eggs  contain  practically  no  carbohydrates. 

Nutritive  Value. — The  egg  contains  all  the  chemical  complexes 
necessary  for  the  formation  of  the  chick  during  incubation.  Eggs  there- 
fore furnish  everything  needed  for  the  nutrition  of  a  mammal.  The 
egg  is  indeed  a  complete  food,  but  not  one  which  produces  the  optimum 
results  when  employed  as  the  sole  source  of  nutriment.  Aside  from  the 
calcium  content  of  the  white  and  yolk  of  the  egg.  which  is  much  lower 
than  that  of  milk,  the  contents  of  the  egg  resemble  milk  in  a  general 
way  in  nutritional  value.     The  high  content  of  milk  sugar  in  the  latter, 

"  Pennington:  "A  Chemical  and  Bacteriological  Study  of  Fresh  Eggs,"  Jour. 
Biol.  Chem.,  Vol.  VII,  No.  2,  Jan.,  1910,  p.  110. 


848  ANIMAL  FOODS:    MEAT,  FISH,  EGGS,  ETC. 

and  the  almost  complete  absence  of  carbohydrate  from  the  egg,  cause 
them  to  differ  considerably  in  the  physiological  results  which  they  pro- 
duce on  animals  when  each  is  fed  as  the  sole  source  of  nutriment.  Egg, 
Avhen  fed  alone,  encourages  much  more  than  milk  the  development  of 
putrefactive  organisms  in  the  alimentary  tract.  The  shell  of  the  egg 
consists  principally  of  calcium  carbonate,  and  during  incubation  this 
is  to  some  extent  dissolved  and  absorbed  for  the  formation  of  the  chick. 
When  eggs  serve  as  human  food  the  shells  are  discarded.  These  are 
distinct  differences  in  the  chemical  natures  of  the  constituents  of  eggs' 
as  contrasted  with  milk.  The  principal  protein  of  egg  yolk,  like  that  of 
milk,  contains  phosphorus,  but  the  fats  of  milk  are  phosphorus  free, 
whereas  phosphorized  fats  (that  is,  lecithins)  are  very  abundant  in  egg 
fats.  There  is  an  abundance  of  lactose  in  milk,  whereas  the  egg  contains 
but  a  trace  of  sugar.  These  differences  have  little,  if  any  significance. 
The  yolk  is  especially  rich  in  both  the  "fat-soluble  A"  and  ''water- 
soluble  B."     (McCollum.) 

Classification. — In  addition  to  fresh  and  refrigerated,  eggs  are  clas- 
sified in  the  trade  as  "rots,"  "spots,"  "checks,"  "ringers,"  "chickens," 
"dirty  shells,"  "heated,"  or  "incubated,"  etc.  Eggs  are  assorted  by  in- 
spection and  candling.  Candling  consists  in  holding  them  before  a 
bright  light ;  the  egg  is  translucent  and  the  movable  yolk  may  clearly 
be  discerned,  as  well  as  the  air  space  which  is  always  at  the  larger  end. 
A  practiced  eye  quickly  detects  eggs  that  are  not  first  quality.  Eotten 
eggs  are  distinguished  as  "red  rots"  and  "black  rots,"  depending  upon 
the  kind  of  putrefaction.  By  "spots"  are  understood  eggs  that  contain 
opaque  spots  under  the  light.  These  spots  usually  consist  of  local 
growths  of  mold  that  have  penetrated  a  crack  in  the  shell,  although  they 
may  be  due  to  coccidia,  embryos,  or  foreign  bodies.  "Checked"  eggs 
are  those  which  have  slight  cracks  or  nicks  in  the  shell.  "Eingers"  con- 
tain small  embryos  of  about  two  days'  growth,  which  are  fiat,  disk-like, 
and  reddish  in  appearance.  "Chickens"  contain  embryos  of  larger 
growth.  Eggs  with  dirty  shells  are  undesirable  more  from  esthetic  than 
other  reasons.  The  dirt  usually  consists  of  hen  excrement.  A  "heated" 
egg  is  a  shrunken  egg,  that  is,  an  egg  that  has  been  exposed  to  the  sum- 
mer temperature  for  several  days.  Some  water  is  lost  by  evaporation 
through  the  porous  shell,  the  air  sac  on  the  end  has  increased  consid- 
erably in  volume,  and  in  many  instances  the  embryo  is  partly  developed ; 
therefore,  heated  eggs  are  also  known  as  incubated  eggs.  Many  of  the 
eggs  gathered  during  the  hot  months  of  summer,  especially  in  July  and 
August,  belong  to  this  category.  These  eggs  are  much  less  desirable  than 
the  spring  and  fall  layings.  Eggs  are  also  graded  as  to  size,  the  very 
small  eggs  being  undesirable,  commanding  a  lower  figure  in  the  market. 
Further,  eggs  are  classified  as  strong-  or  weak-bodied,  depending  upon 
how  they  "stand  up"  when  broken  out. 


PLANT   FOODS  849 

Bacteria  in  Eggs. — Ki,',i2:s  as  thoy  coiiio  t'loiii  tlic  hen  frequently  con- 
tain hactoria,  worms,  pjravel,  blood  clots,  and  forci^^rii  bodies  of  various 
kinds.  Practically  all  e^^s  contain  bact(>ria,  altbon^di  nuniorous  ob- 
servers report  occasionally  (bat  an  c.u'i,'-  is  s1(M-ilc.  As  ;i  rnic,  tliesc  ob- 
servations are  based  upon  planting'  a  small  |)arl  of  tbo  v^'^.  if  tbo  entire 
egg  is  planted  a  (^rowtli  is  ahnost-.,  invarial)ly  obtained.  Tbus,  in 
eighteen  frcsbly  laid  Cii'.U's  wbicli  I  cxaniinod  cNcry  one  oC  tbcm  con- 
tained bacteria  in  tbe  yolk;  two  ol'  tlicm  contained  B.  coli.  Curiously 
enou,i]:b,  tbere  arc  practically  always  more  bacteria  in  the  yolk  than  in 
the  wliilc;  ilic  while  contains  some  bactericidal  pro])crty,  probably  sim- 
ilar to  that  possessed  by  fresh  blood.  The  bacteria  doul)tless  gain  en- 
trance to  the  Qgg  while  in  the  oviduct.  Pernot  ■*"  examined  the  Qgga 
from  over  the  size  of  a  pea  to  the  perfect  egg  and  found  bacteria  at 
every  stage.  It  is  well  known  that  the  bacteria  may  also  get  into  an 
egg  through  the  shell,  as  it. is  porous  and  permeable.  When  the  shell 
is  moist  and  dirty  the  chances  of  growth  and  mold  piercing  it  are 
increased.  Eggs  laid  in  the  summer  time  (July  and  August)  contain 
many  more  bacteria  than  those  laid  in  the  spring,  fall,  and  colder 
months.  It  is  w^ell  known  that  summer  eggs  do  not  keep  as  well  as 
winter  and  spring  eggs. 

Eggs  and  Disease. — Of  all  foods,  so  far  as  known,  eggs  are  less  liable 
to  convey  disease  or  contain  harmful  properties  than  any  other  single 
food  of  animal  origin.  The  literature  is  singularly  free  of  instances  of 
sickness  attributed  to  eggs.  There  is  no  known  infection  of  the  hen 
transmissible  to  man  through  its  egg.  Eggs  do  not  agree  with  some 
people,  who  have  an  "idiosyncrasy,"  so  that  a  very  small  quantity  will 
bring  on  symptoms  resembling  anaphylaxis.  This  condition  is  doubtless 
an  instance  of  specific  hypersusccptibility  to  egg  protein.  There  are 
several  cases  on  record  in  which  this  hypersusceptibility  has  been  cured  by 
the  administration  of  pills  or  candy  containing  at  first  infinitesimal 
amounts  of  egg-white,  gradually  increasing  the  amount.  The  entire 
treatment  should  extend  over  a  period  of  months.  In  .  this  way  an 
"immunity"  may  be  established  in  man  precisely  analogous  to  the  de- 
sensitization  which  may  be  established  by  repeated  injections  of  an 
alien  protein  into  guinea-pigs. 

PLANT  FOODS 

Man  is  still  a  parasite  living  on  the  plant  kingdom.     The  vegetable 

world  furnishes   us   our  chief   source   of   energy.      The   animals   which 

furnish  food  to  man  function  as  expensive  converters  of  the  energy  of 

plants  into  a  forn.i  directly  available  for  our  uses.     A  cow  eats  a  liberal 

""Investigation  of  the  :Mortality  of  Incubator  Chicks,"  IJiill.  103,  Oregon 
Agr.  College  Exp.  Station. 


850  PLANT  FOODS 

plant  ration   daily   during  several  years  before  the  nutrient   products 
which  she  furnishes  are  ready  for  the  market. 

For  purposes  of  nutrition,  plant  foods  are  classified  as  seeds;  roots 
and  tubers;  and  leafy  vegetables.  Each  class  has  distinct  dietetic 
qualities. 

THE  NUTRITIVE  VALUE  OF  PLANTS 

Seeds. — Seeds  are  storage  organs  and  can  be  classed  together  so  far 
as  their  food  value  is  concerned.  The  proteins  of  seeds  are  incomplete, 
because  they  contain  only  a  few  of  the  17  or  18  amino-acids  necessary 
to  rebuild  human  protein.  Seeds  are  also  poor  in  mineral  elements, 
especially  calcium,  sodium,  and  chlorin,  McCollum  examined  wheat, 
corn,  rice,  oats,  barley,  rye,  Kaffir  com,  millet  seed,  flaxseed,  pea,  and 
both  navy  and  soy  beans.  All,  with  the  exception  of  millet  seed,  were 
below  the  optimum  in  their  content  of  the  dietary  factor  "^fat-soluble  A." 
Seeds  are  also  deficient  in  "water-soluble  B"  and  in  antiscorbutic  prop- 
erties. When  seeds  alone  are  used  as  the  sole  source  of  nutriment,  it  is 
not  possible  to  secure  appreciable  growth  in  young  animals. 

The  Leaf. — The  leaf  is  very  different  from  seeds,  roots  and  tubers 
from  a  dietary  standpoint.  The  leaf  of  the  plant  is  very  rich  in  cells, 
and  in  most  cases  contains  but  little  reserve  food  material.  It  is  the 
synthetic  laboratory  of  the  plant.  It  builds  up  proteins,  starch,  sugars 
and  fats,  through  the  action  of  chlorophyl  and  sunlight  upon  CO2,  which 
is  absorbed  from  the  air,  together  with  water  and  mineral  salts  which 
are  absorbed  from  the  soil  through  the  roots.  The  surfaces  of  the  leaf 
are  a  mosaic  of  living  cells.  They  contain  all  the  chemical  complexes 
which  are  necessary  for  the  nutrition  of  the  animal  cells,  and  are  quali- 
tatively complete  foods.  The  freer  a  leaf  is  from  the  function  of  a 
storage  tissue,  the  more  intensified  will  be  its  leaf  properties  as  a  food. 
The  fleshy  leaves  tend  to  have  in  some  degree  the  dietary  properties 
of  the  seed,  and  stand  intermediate  between  leaves  which  are  thin,  and 
dry  easily,  and  the  seed  in  this  respect.  In  general,  leaves  are  analogous 
to  cellular  organs  of  animals,  such  as  liver,  pancreas  and  kidneys,  in 
dietary  properties. 

The  dry  leaf  usually  contains  from  three  to  five  times  as  much  total 
ash  constituents  as  does  the  seed,  and  is  always  especially  rich  in  calcium, 
sodium,  and  chlorin,  in  which  the  seed  is  poor.  It  follows,  therefore, 
that  the  leaf  supplements  the  inorganic  deficiencies  of  the  seed.  The 
leaf,  in  most  cases,  contains  much  more  of  the  dietary  essential,  "fat- 
soluble  A,^'  than  is  found  in  any  seed,  so  that  combinations  of  leaf  and 
seed  prove  more  satisfactory  for  the  nutrition  of  an  animal  than  do 
mixtures  of  seeds  alone.  The  leaf  as  well  as  the  seed  contains  protein 
and  amino-acids,  which  result  from  the  digestion  of  proteins.  The 
amount  varies  from  8  per  cent,  of  protein    (nitrogenX6.38)    in  such 


RELATION  TO  HEALTH  851 

fleshy  leaves  as  the  cabbage,  after  drying,  to  more  than  15  per  cent,  in 
the  dry  alfalfa  or  clover  leaf.  The  seeds  vary  in  their  content  of 
protein  from  about  10  to  25  per  cent.  The  leaf  proteins  ajjpear.  from 
the  data  available,  to  supplement  and  ('iiliaiue  in  some  degree  the  value 
of  the  seed  proteins  witli  which  they  are  combined.  The  leaf  supple- 
ments, therefore,  all  the  nutritive  deficiencies  of  the  seed,  but  not  neces- 
sarily in  a  highly  satisfactory  nuinner.''^ 

l*eoples  who  have  employed  the  leaf  of  the  })lant  as  tlieir  sole 
protective  food  are  characterized  by  small  stature,  relatively  short  span 
of  life,  higli  infant  mortality,  and  by  contended  adherence  to  the  em- 
ployment of  the  simple  mechanical  inventions  of  their  forefathers. 
Contrast  with  ^lilk,  page  753, 

Tubers. — After  the  seeds,  the  tubers  of  certain  plants  constitute  one 
of  the -most  important  classes  of  energv'-yielding  foods.  The  potato 
and  sweet  potato  are  by  far  the  most  important  representatives  in  this 
group  in  Europe  and  America,  but  several  other  kinds  of  tubers  are 
widely  used  as  human  food  in  the  Orient. 

Roots. — Eoots  are  tubers;  like  the  tubers,  there  is  a  cellular  layer  at 
the  periphery,  and  the  interior  is  loaded  with  reserve  foodstuffs.  Feed- 
ing tests  have  shown  that  the  properties  of  the  beet  resemble  those  of 
the  seed  and  tuber  rather  than  those  of  the  leaf.  The  fleshy  roots 
and  the  potato  and  the  sweet  potato  have  an  inorganic  content  which 
resembles  that  of  the  seed  in  a  general  way. 

Fruits. — The  chief  uses  of  fruits  in  the  diet  depend  upon  their 
salt  content,  their  laxative  properties,  and  their  antiscorbutic  value. 
Fruits  do  not  rank  high  as  sources  of  energy  to  the  body ;  that  is,  their 
caloric  values  are  rather  low  in  comparison  with  most  of  the  common 
food  products.  Fruits  are  almost  without  exception  devoid  of  fats  and 
are  poor  in  protein.  They  are  good  sources  of  mineral  salts.  Some  of 
them  contain  carbohydrate,  such  as  the  sugars  in  the  orange  and  the 
banana.  They  all  have  a  high  percentage  of  water.  The  citrus  fruits 
are  rich  in  organic  acids.  They  are  highly  palatable  and  exert  a  favor- 
able influenc-e  on  the  excretory  processes  of  the  kidneys  and  the  intestine. 
Many  of  them  are  rich  in  "water-soluble  B"  and  antiscorbutic  vitamins. 
The  liberal  use  of  fruits  in  the  diet  should  be  encouraged. 

Carbohydrate  Food  Preparations. — Carbohydrate  foods,  such  as  flour, 
sugar,  starches,  and  most  cereal  preparations,  are  rich  as  sources  of 
energy,  but  poor  in  vitamins. 

HOW  PLANTS  MAY  INJURE  HEALTH 

Poisonous  Plants. — Many  plants  contain  a  physiological  poison,  such, 

for  example,  as  aconite,  strychnin,  ricin,  abrin,  muscarin,  and  a  long  list 

"McCollum.  E.  v.:  "The  Xewer  Knowledge  of  Nutrition."  The  ^racmillan 
Co.,  1918. 


852  PLANT  FOODS 

of  other  substances  normally  present.  According  to  Chestnut,**  there 
are  about  500  species  of  plants  in  North  America  which  arc  said  to  be 
poisonous.  Most  of  these  are  rare  specimens,  and  never  eaten  by  man ; 
some  are  poisonous  only  during  certain  seasons  of  the  year;  others  are 
poisonous  only  when  introduced  parenterally  into  the  human  body;  still 
others,  such  as  the  poison  ivy,  are  injurious  only  to  susceptible  indi- 
viduals, while  many  of  them  are  known  to  be  poisonous  only  to  domestic 
animals.  Of  these  latter,  the  larkspur  (Delphinntm),  the  w^ater  hemlock 
(Cicuta  maculaia),  the  lupines,  the  laurels,  and  the  death  camus 
(Zygadenus)  are  prominent  examples. 

Chestnut  estimates  that  in  the  United  States  there  are  only  about 
30  species  of  plants  which  have  been  associated  with  poisoning  in  man, 
and  furthermore  most  of  such  cases  must  be  considered  as  extremely 
rare  accidents.  Instances  of  such  accidents  have  been  recorded  by 
Jordan,*^  who  cites  the  mistaking  of  the  American  false  hellebore  (Verat- 
rum  viride)  for  the  iiiarsh-marigold ;  the  use  of  the  fruit  of  the  Ken- 
tucky coffee  tree  ( Gymnocladus  dioica)  in  mistake  for  that  of  the  honey 
locust ;  the  use  of  daffodil  bulbs  for  food ;  the  substitution  of  the  moun- 
tain laurel  (Kalmia  latifolia)  for  wintergreen,  and  the  mistaking  of 
the  water  hemlock  {Cicuta  maculata)  for  other  edible  roots.  Jordan  feels 
that  poisoning  from  the  latter  cause  is  probably  more  frequent  than 
supposed,  saying  that  in  one  year,  in  New  Jersey  alone,  ten  cases,  two 
of  which  were  fatal,  occurred.  Ford  *^  reports  accidental  poisoning  in 
man  following  ingestion  of  the  tutu  plant,  one  of  the  Eoriariae,  found 
chiefly  in  New  Zealand.  Eoberto  and  Jelmoni  "  record  an  instance  of 
poisoning  following  the  ingestion  of  the  berries  of  Taxis  baccata,  the 
European  yew  tree.  Guerrero,  de  la  Paz  and  Guerrero  *^  report  cases  of 
poisoning  from  the  use  of  a  decoction  of  "Sanki,"  the  fruit  of  IlUcium 
religiosum,  Siebold ;  they  call  attention  to  the  great  similarity  between 
Illicium  religiosum  and  lUicium,  anisatum,  which,  they  say,  is  extensively 
used  by  the  Filipinos  as  a  stimulant,  stomachic  and  carminative. 
The  manuals  on  poisonous  plants  cite  many  other  instances  of  accidental 
poisoning,  due  to  the  substitution,  usually  by  children  and  the  ignorant, 
of  poisonous  plants  for  similar  food  plants. 

There  is  a  great  variation  in  the  toxicity  of  plants,  and  tropical 
plants  are  more  often  poisonous  than  those  of  cooler  climates,  as  is  the 
case  with  fish,  insects,  snakes,  and  other  animals. 

Mineral  substances  in  plants  rarely  cause  poisoning.  Lead,  in  grass, 
has  been  shown  to  be  the  cause  of  symptoms  of  lead  poisoning  in  cows, 
and  plants  manured  Avith  superphosphates  which  contain  arsenic  may 

**  Science,  XV,  1902,  1916. 

^^"Food  Poisoning,"  Univ.  of  Chicago  Press.  1917,  p.  4. 

"^Journ.  Fharm.  and  Exp.  Ther.,  II,  No.  1,  Aug.,  1910. 

^'Chem.  Zentr.,  1916,  I,  1088:  Chem.  Abst.,  II,  20.  1917,  p.  2829. 

^Philippine  Jour.  Sci.,  Sept.,  1916,  XI,  p.  203. 


KELATION  TO  HEALTH  853 

absorl)  enoiiiili  ;ii's('iiic  (o  cause  sickness^'*"  Similarly,  tlicrc  is  jjossihility 
of  poisoning-  duo  to  tlie  use  of  insocticidal  sprays,  washes  and  powders, 
on  vegetables  and  fruits.     See  page  279. 

Acids  arc  of  more  coininon  oecurrence.  J'russic  acid  occurs  free  in 
some  plants,  as  a  glucosid  in  some  others,  especially  in  tluj'^e  of  the 
rose  and  ai)ple  family.  The  bitter  cassava  (Manihoi  ulilisaiina),  from 
whieh  ordinary  tapioca  is  derived,  contains  prussic  acid  in  considerable 
amount,  and  cannot  be  eaten  in  the  fresh  state.  The  prussic  acid  is 
dissipated  by  heat.     Cases  of  poisoning  due  to  this  cause  are  not  known. 

Oxalic  acid  is  quite  common  in  many  plants,  and  illustrative  of 
its  poisonous  qualities  is  the  outbreak  of  so-called  "ptomain  poisoning" 
reported  in  New  York,^''"  which  was  shoM-n  to  be  due  to  soup  prepared 
from  "Schav"'  or  "Szchav"  leaves,  more  commonly  known  as  sour 
grass — a  species  of  sorrel.  Two  grains  of  oxalic  acid  were  found  in 
each  ounce  of  the  leaves,  and  four  grains  in  each  ounce  of  the  stems  of 
this  plant.  The  soup  which  was  eaten  contained  about  ten  grains  of 
oxalic  acid  per  pint.  Robb  ^^  report?  a  fatal  case  of  oxalic  acid  poisoning 
due  to  eating  fried  rhubarb  leaves.  Marked  exhaustion,  hemoptysis, 
early  cardiac  failure,  and  greatly  delayed  coagulation  time  of  the  blood 
were  the  prominent  symptoms  observed  in  this  case.  The  oxalic  acid 
content  (as  oxalates)  of  the  stalks  of  rhubarb  varies  from  1.5  per  cent. 
to  40  per  cent.,^-  but  there  seems  to  he  no  figure  available  for  the  amount 
in  the  leaves.  Arbenz  ^^  found  that  rhubarb  contains  3.2  grams  of 
oxalic  acid  per  kilogram.  Many  other  foods  contain  oxalic  acid,  but  in 
harmless  amounts.  The  poisonous  qualities  of  the  loco  weed  (Astragalus 
molHssimiis) ,  common  to  the  western  states,  have  been  attributed  to  an 
acid  present  in  the  plant,  called  by  some  "loco"  acid. 

Oils. — Some  of  the  common  vegetable  oils,  such  as  the  oils  of 
chamomile,  cloves,  cinnamon,  sassafras,  etc.,  may  be  poisonous  in  exces- 
sive amounts.  Chestniit  ^^  cites  an  instance  of  the  death  of  a  child 
following  the  ingestion  of  two  nutmegs,  while  Jordan  ^^  calls  attention 
to  an  outbreak  of  sickness  in  Germany  in  1911  due  to  the  inclusion 
of  maratti-oil  (from  the  tropical  plant  Hydrocarpus)  in  a  commercial 
substitute. 

Carotinemia.^''' — A  diet  rich  in  carotin,  which  is  the  coloring  mat- 
ter contained  in  carrots,  spinach,  egg  yolk,  and  oranges,  may  produce 
a  yellow   discoloration   of  the   skin,   which   resembles   jaundice,  "except 

*^>^cience,  XV,  1902,  p.  1016. 

"^Weekly  Bull.,  N.  Y.  C.  Dept.  of  Health,  Sept.  16,  1916. 
"J.  A.  M.  A.,  Vol.  LXXIII,  No.  8,  Aug.  23,  1919,  p.  627. 
'■  U.  R.  Dispensatory. 
'^Chem.  Ahst.,  1917".  II,  p.  2374. 
^Scie)ice.  XV,   1902,  p.   1010. 

""Food  Poisoning,"  Chicago  Univ.  Press,  1917,  p.  16. 

'"Hess,  A.  F.,  and  Kvers,  V.  C. :  Carotineniia :  A  New  Clinical  Picture, 
J.  A.  M.  A.,  Dee.  6,  1919,  LXXIII,  1743. 


854  PL)VNT  FOODS 

that  the  sclera  are  not  involved.  The  carotin  and  xauthophyll  pig- 
ments derived  from  food  are  this  sources  of  the  coloring  matters  of 
milk  fats  and  body  fats,  of  egg  yolk,  of  the  corpus  luteum,  nerve  cells, 
and  other  structures. ^^ 

Parasites.- — Certain  vegetables,  such  as  lettuce,  celery,  water  cress, 
radishes,  and  similar  plants,  eaten  raw  may  convey  typhoid  fever, 
cholera,  dysentery,  both  amebic  and  bacillary,  the  eggs  and  larvae  of 
animal  parasites,  and  other  agents  of  infection.  This  usually  occurs 
from  the  use  of  night-soil  as  fertilizer,  or  from  infected  water  from  a 
foul  source. 

All  vegetables  which  are  eaten  raw  should  be  washed  thoroughly 
beforehand,  otherwise  they  may  be  contaminated  with  manure  and  other 
impurities  or  the  excrement  of  domestic  animals  which  have  been  roam- 
ing in  the  garden.  The  larvae  of  worms  have  been  transmitted  to  man 
in  this  manner. 

A  fungus  developing  in  rye  is  Tesponsible  for  ergotism.  Molds  and 
smuts  which  grow  on  plants  used  by  man  for  food  may  give  rise  to 
serious  difficulty  due  largely  to  mechanical  obstruction,  although  there 
is  some  reason  to  believe  that  poisonous  substances  may  be  formed,  for 
example,  the  sulphocyanic  acid  formed  by  Aspergillus  niger}^  Ernst ''^ 
reports  a  case  of  mucor  infection,  suggestive  of  pulmonary  tuberculosis, 
in  which  the  source  of  the  mucor  was  probably  corn. 

Toxins. — Bacteria  growing  in  plants  may  develop  toxins.  Botulism 
is  the  only  known  example  in  this  category.  This  poison  may  form  in 
beans,  corn,  peas,  asparagus,  beets,  olives,  and  a  variety  of  other  plant 
foods  containing  protein. 

Susceptibility,  Idiosyncrasy,  Anaphylaxis. — A  number  of  plant  foods, 
such  as  strawberries,  tomatoes,  oatmeal,  etc.,  cause  urticarial  eruptions 
and  other  manifestations  of  anaphylaxis  in  susceptible  individuals.  Hay 
fever  is  another  instance  of  hypersusceptibility,  brought  on  by  the  pollen 
of  various  plants.  These  conditions  are  discussed  under  the  chapter  on 
Anaphylaxis,  page  593. 

Rhus  Poisoning. — Rhus  poisoning,  also  known  as  Bhus  dermatitis,  or 
Dermatitis  venenata,  is  caused  lay  an  irritating  resinous  substance  in  the 
sap  of  numerous  plants.  The  various  plants  which  may  provoke  such 
irritation  in  susceptible  subjects  are  at  least  60  or  70  in  number.  The 
most  common  and  best  known  of  this  group  belong  to  the  genus  Rhus. 
Bhus  toxicodendron,  or  poison  ivy,  is  distinguished  from  other  sus- 
pected creepers  of  a  similar  appearance  by  its  possession  of  three  leaflets 
instead  of  five.    Bhus  diversiloha,  or  poison  oak,  which  grows  especially 

"Palmer,  L.  S.,  and  Eckles,  C.  H.,  Jour.  Biol.  Chem.,  XVII,  191,  211,  223,  237, 
245,  March,  .1914;  also  Palmer,  L.  S.:  Ibid.,  XXIII,  261,  Nov.,  1915;  XXVII,  27, 
Oct.,  1916. 

'"  Science,  XV,  1902,  p.  1016. 

"^Journ.  Med.  Research,  Nov.,    1918,  XXXIX,  No.  2,  p.  143. 


RELATION  TO  HEALTH  855 

in  the  western  part  of  tlie  United  States,  is  a  shrub  or  small  tree.  lUius 
venenata,  known  as  poison  sumac,  poison  dog^vood,  and  poison  elder,  is  a 
shrub  or  small  tree,  growing  in  swampy  places  in  the  TTnited  States  and 
Canada  as  well  as  in  Japan. 

Of  the  six  varieties  of  the  rhus  family  that  grow  wild  in  Japan,  7?/im.<? 
iojuode  11(1  run  and  Bhus  verm icif era  are  the  most  injurious.  Among 
the  plants  which  less  frequently  cause  dermatitis  are  the  nettle  (Urlica 
iloica),  the  primrose  (Primula  ohconica),  cowhage  (Macuna  pi'uriens), 
smartweed  (Polygomnn  pnnctatumj  balm  of  Gilead  (Podophi/llum, 
Balsaniuni   (/Ueaden^sc).  oleander  (Neriuni  Oleander),  and  rue  (Ruta). 

The  part  of  these  plants  to  be  feared  is  the  resinous  sap.  This  sticky 
sap,  exuding  from  all  parts  of  an  injured  plant,  when  it  comes  in  contact 
w4th  the  skin,  causes  intense  irritation,  which  is  characterized  by  its 
acute  character,  frequently  beginning  between  the  fingers,  associated 
with  swelling,  and  often  large  vesicles  and  blebs,  the  exudate  from 
which  is  non-toxic.  The  dermatitis  occurs  in  sharply  defined  patches, 
elongated  streaks,  and  other  irregular  shapes,  corresponding  with  the 
original  area  of  contact.  It  does  not  follow  the  nerve  trunks.  It  sel- 
dom attacks  the  scalp  or  the  inside  of  the  hands.  The  original  areas  of 
contact  are  most  affected  and  the  parts  of  the  skin  to  which  the  poison 
has  been  conveyed  from  the  original  sites  of  contact  are  usually  less 
severely  affected.  Together  w'ith  the  local  lesions,  there  is  a  leukocytosis 
and  constitutional  disturbances,  such  as  fever,  coated  tongue,  loss  of 
appetite,  constipation,  and  a  trace  of  albumin  in  the  urine.""  The  attack 
may  subside  in  from  four  to  six  days,  depending  on  the  amount  of  the 
irritant  and  the  sensitiveness  of  the  skin.  Idiosyncrasy  plays  an  im- 
portant part.  Persons  affected  are  believed  to  be  more  susceptible. 
It  is  now  quite  certain  that  the  toxic  principle  in  Rhus  poisoning 
is  not  volatile,  as  was  once  supposed ;  in  other  words,  contact  is  necessary, 
although  not  actual  contact  with  the  plant  itself,  for  the  sap  may  be 
carried  indirectly  by  clothing,  tools,  insects,  smoke,  etc.,  to  the  skin  of 
persons  far  from  the  actual  neighborhood  of  the  plant,  thus  explaining 
those  mysterious  "recurrent"  cases  of  rhus  poisoning.  Sap  thus  carried 
loses  its  toxic  properties  by  oxidation,  the  loss  being  more  rapid  at  body 
temperature  and  moist  atmosphere. 

Japanese  lacquered  ware  when  new  has  caused  a  dermatitis  in  a 
large  number  of  people.  The  sap  of  the  lacquer  tree  produces  typical 
rhus  poisoning.  Susceptible  individuals  may  be  affected  by  passing 
under  a  lacquer  tree,  or  by  simply  going  by  a  lacquer-ware  shop.  This 
does  not  mean  that  the  poison  is  volatile,  for  in  such  instances  the  sap 
is  transferred  in  some  mechanical  way. 

*M!cNair,  J.  B. :  "The  Transmission  of  Rhus  Poison  from  Plant  to  Person," 
/oi/r.  Infect.  Dis.,  1916.  XIX,  429;  "The  Pathology  of  Dermatitis  Venenata  from 
Rhus  Diversiloba,"  ibid.,  1916,  XIX. 


856  PLANT  FOODS 

McNair  ^^  has  sliowii  that  smoke  i'nnn  tlie  licated  leaves  of  poison  oak 
causes  dermatitis  if  blown  on  the  Avrist.  If^  however,  the  smoke  is 
filtered  through  glass  wool,  it  is  no  longer  irritating,  showing  that  the 
smoke  is  only  a  mechanical  carrier  of  the  poison,  thus  confirming  the 
oft-repeated  observation  that  poisoning  may  result  from  exposure  to 
smoke  of  camp  fires,  etc.  The  exact  nature  of  the  chemical  substance 
is  not  known,  but  it  is  now  clear  that  it  is  non-volatile  and  resinous  in 
nature,  and  that  it  is  absent  from  the  pollen  and  plant  hairs.  The  toxic 
substances  in  the  several  plants  are  identical  or  very  closely  related. 
Pfaff  ^^  isolated  a  fixed  oil,  toxicodendrol ,  of  which  1/1,000  milligram  in 
two  drops  of  oil  will  set  up  localized  edema  and  vesication. 

The  dermatitis  may  sometimes  be  averted,  even  after  handling  these 
plants,  by  the  free  use  of  an  alkaline  soap  and  water,  or  alcohol,  contain- 
ing a  little  dissolved  sodium  hydroxid.  The  poison  is  soluble  in  alcohol 
and  alkalies.  Gasoline  may  also  be  used.  An  aqueous  solution  of 
sodium  bicarbonate  is  less  effective.  The  application  must  be  prompt 
and  thorough  or  else  it  will  only  tend  to  spread  the  irritating  poison. 


POISONING   FROM   PLANT   FOODS 

Ergotism. — Ergotism  is  a  form  of  food  poisoning  brought  on  by  pro- 
longed use  of  meal  made  from  grain  contaminated  with  the  Claviceps 
jm7-pwea.  The  fungus  develops  in  the  flowers  of  rye  and  other  grains. 
The  chief  source  of  the  poisoning  in  man  is  from  rye,  in  which  case 
the  fungus  may  entirely  replace  the  grain.  Ergotism  is  practically 
unknown  in  this  country,  but  in  Europe  it  is  still  occasionally  met  with, 
although  not  to  the  same  extent  as  in  former  times.  From  ergot  Kobert 
was  able  to  isolate  three  poisonous  substances,  sphacelinic  acid,  cornutin, 
and  ergotin.  Sphacelinic  acid  is  a  non-nitrogenous,  unstable  body  and 
is  believed  to  be  the  active  agent  in  contracting  the  blood  vessels.  Cornu- 
tin is  also  an  active  alkaloid  and  produces  vasomotor  contraction. 
According  to  Novy,  more  recent  investigations  have  made  it  probable 
that  there  are  other  substances  present  which  constitute  the  real  toxic 
agent.  Thus,  Jacoby  obtained  a  non -nitrogenous  resin  sphacelotoxin 
and  Barger,  parahydroxyphenylethylamin,  which  they  regard  as  the 
specific  poisons.  It  is  now  believed  that  histamin  is  the  most  im- 
portant constituent  of  ergot,  for  in  minute  doses  it  produces  tonic 
contraction  of  the  uterus. ''•'' 

The  intoxication  may  have  an  acute  or  chronic  course,  and  in  either 

"McNair,  J.  B.:     Jour.  Am.  Chem.  Soc,  1916,  XXXVIII,  1417. 

^Jmir.  Exp.  Med.,  1897,  II,  p.  181. 

"Barger  and  Dale:  Jour,  of  Physiol.,  XL,  38,  1910;  Kutscher:  Centralbl.  f. 
Physiol.,  XXIV,  163,  1910;  Ackermann  and  Kutscher:  Ztschr.  f.  Biol.,  LIV,  387, 
1910. 


roisoNors  I'L.wrs  s,-)-? 

type  the  syinptonis  may  he  nervous  or  coinulsivc,  or  else  lliey  inav  1m' 
trophic  or  .gangrenous  in  character. 

The  ])resence  of  the  sclerotiuni  may  l)c  siispcdrd  Irom  the  color  of 
the  meal,  which  is  grayer  than  usual  and  often  shows  violet-colored 
specks.  The  addition  of  ])otassium  hydroxid  with  heat  produces  an 
odor  of  trinu^thylann'n  resulting  from  the  hreaking  up  (d'  the  grain  con- 
taining chinolin.  l'"urther,  the  grain  contains  a  dye  which  is  soluble 
in  alcohol  or  ether.  To  10  grams  of  the  meal  add  10  c.c.  of  ether  and 
20  drops  of  dilute  sulphuric  acid.  Shake  well  and  filter  after  half  an 
hour.  Then  add  several  drops  of  a  saturated  solution  of  sodium  bicar- 
bonate, which  dissolves  out  all  the  coloring  matter. 

Lathyrism. — Lathyrism  or  vetch  poisoning  is  a  rather  rare  condition 
met  with  in  some  parts  of  Europe,  notably  Austria  and  Italy,  in  north- 
ern Africa,  and  in  India.  The  vetch  seed  is  ground  in  the  form  of 
meal  and  used  as  a  partial  substitute  for  that  of  wheat.  The  seed  is 
popularly  known  as  chick-pea.  The  vetch  seeds  are  obtained  chiefly 
from  Lathyrus  sativus  and  Lathyrus  cicera.  The  eating  of  bread  pre- 
pared from  meal  containing  the  seeds  of  the  lathyrus  is  followed  by 
sudden  and  severe  pains  in  the  lumbar  region,  girdle  sensation,  motor 
paralysis  of  the  lower  extremities,  tremor,  and  fever.  The  nature  of 
the  poison  is  not  known,  but  it  is  probably  of  the  nature  of  a  toxalbumose, 
of  which  ricin  and  abrin,  the  poisons  of  the  castor  bean  and  the  jequirity 
bean  respectively,  are  well-known  examples. 

Favism. — Favism  (fava,  bean)  is  the  name  applied  to  a  disease  which 
has  been  reported  only  in  Italy.  It  is  attributed  to  the  use  of  beans  as 
food,  or  even  just  smelling  the  blossoms  of  the  bean  plants.  Pammel  "^ 
cites  instances  of  individuals  who  cannot  inhale  the  odor  of  morphin, 
turpentine,  tobacco,  the  flowers  of  the  common  bird  cherry,  the  haw  or 
the  tuijerose,  without  becoming  ill.  (iasharrini  ''■'  quotes  the  work  of 
Germi  and  concludes  with  him  that  the  disease  is  the  result  of  an  acute, 
toxic  hemolysis.  It  is  said  to  occur  only  where  beans  are  cultivated 
on  a  large  scale,  and  then  usually  only  during  the  spring  of  the  year. 
Of  1211  cases  which  were  studied  by  Fermi  in  Sardinia,  752  were 
ascribed  to  ingestion  of  the  beans,  and  459  to  inhalation  of  the  odor 
or  pollen  of  the  bean  plants.  The  onset  of  symptoms  occurs  a  day  or  so 
after  ingestion  or  from  2  to  6  hours  following  inhalation.  It  is  dis- 
tinguished by  acute,  febrile  anemia  with  jaundice  and  hemoglobinuria, 
but  there  may  also  be  abdominal  pain,  nausea,  vomiting  and  diarrhea. 
Fermi  noted  an  hereditary  tendency  in  about  20  per  cent,  of  his  cases, 
which  in  some  instances  could  be  traced  through  several  generations. 
This  hereditary  predisposition  to  the  disease  is  said  not  to  become 
apparent  in  some  cases  until  adult  life.     It  is  also  stated  that  in  some 

^  Manual  of  Poisonous  I'lantft.  Part  I,  1010,  p.  7. 
^Policlinicu,  Nov.  14, .191.5;  abst.  J.  A.  J/.  A.,  191.5,  p.  22'6-i. 


858  PLAXT  FOODS 

instances  one  exposure  seems  to  confer  a  permanent  immunity  but 
others  suffer  at  each  exposure.  The  cause  of  the  disease  is  unknown. 
Bacterial  activity  and  fungi  have  been  held  responsible  but  no  proof  of 
either  hypothesis  has  been  brought  forward.  The  reported  seasonal 
prevalence,  the  incidence  foUoAving  inhalation  of  the  bean  pollen,  the 
hereditary  predisposition,  and  the  possible  immunity  following  one 
attack  are  suggestive  of  sensitization  and  anaphylactic  reaction. 

Mushroom  Poisoning. — The  ill  effects  from  eating  mushrooms  are 
usually  due  to  mistaking  the  poisonous  for  the  edible  species,  and  in 
America  this  is  usually  done  by  children,  immigrants  or  the  ignorant. 

The  number  of  species  of  poisonous  mushrooms  which  are  capable  of 
causing  death  is  not  very  great,  perhaps  "20  or  30.  Amanita  and  volvaria 
are  the  most  poisonous  genera,  and  are  the  ones  usually  involved  in  the 
fatal  accidents. 

Ford  '^'^  estimates  that  from  12  to  15  deaths  occur  annually  in  the 
United  States  from  Amanita  poisoning.  In  September,  1911,  in  the 
vicinity  of  iXew  York,  following  heavy  rains,  22  deaths  were  reported. 
Jordan  '^'^  believes  that  mushroom  poisoning  is  probably  increasing  in 
this  country  due  to  an  increasing  use  of  mushrooms  for  food,  and  also 
due  to  increased  immigration  from  countries  where  mushrooms  are 
more  commonly  eaten  than  here. 

Amanita  pJialloides  and  Amanita  muscaria  are  exceedingly  poison- 
ous, dangerous  and  seductive  species,  responsible  for  most  of  the  deaths 
from  toadstool  eating.  Amanita  pTialloides,  because  of  its  white  color, 
is  mistaken  for  the  common  mushroom,  Agaricus  campestris.  Agaricus 
cam,pestris  does  not  grow  in  the  woods,  neither  has  it  white  gills,  nor 
white  spores,  nor  a  volva  at  the  base  of  the  stem.  Xo  dependence,  how- 
ever, should  be  placed  upon  color,  size,  shape  or  general  appearance.  It 
requires  a  trained  mycologist  to  distinguish  one  species  from  another."^ 

The  first  historic  instance  of  mushroom  poisoning  occurred  in  the 
family  of  the  Greek  poet,  Euripides,  who  lost,  in  one  day,  wife,  daughter 
and  two  sons.  Among  others  whose  lives  have  been  sacrificed  through 
ignorance  may  be  mentioned  Pope  Clement  YII,  the  Emperor  Jovia, 
Emperor  Charles  YI,  Berronill  of  Xaples,  the  widow  of  Tsar  Alexis, 
and  the  Princess  of  Conti.  Poisonous  fungi  have  figured  prominently 
in  many  of  the  accidental  and  craftily  malicious  tragedies  of  history. 

Poisonous  mushrooms  contain  at  least  four  classes  of  poison:  (1)  a 
"toxin"  represented  by  amanitotoxin :  "^^  (2)  muscarin,  an  alkaloidal- 
like  substance,  resembling  pilor-arpin;  (3)  a  hemolytic  poison;  and  (4) 
a  number  of  poisons  more  or  less  ill  defined,  such  as  the  Pilcz-toxin  of 

"^Joiirn.  Inf.  Bis.,  Ill,  2,  Apr..  1906,  p.  191. 
"  "'Food  Poisoning,"   Chicago  Univ.  Press.   1917,  p.    18. 

"*  The  subject  has  been  discussed  since  1886  in  the  Bulletin  de  la  Societe 
ilycologique  de  France. 

^MVm.  H.  Ford:     Jour.  Exp.  Med.,  May  26,  1906,  VIII,  3,  p.  437. 


POISONOUS  PLANTS  859 

Harmsen.  These  poisons  do  not  all  occur  in  any  one  species,  l)ut  are 
found  sinu'ly  and  in  various  coniliinat  ions  in  llic  ililVcrcut  genera  and 
species. 

Ainanilii  phit/luidcs,  the  "while  or  (h'adly  anianita,'  is  the  cause  of 
tlie  greatest  nund>tM-  of  eases  of  mushroom  j)oisoiiing,  if  we  include  in 
this  group  .1.  renui,  A.  hulbosa,  A.  alba,  A.  virescens,  A.  mappa,  and 
many  other  species  known  hy  various  names  in  different  localities.  Fatal 
poisoning  takes  ])hice  when  the  fungi  are  eaten  raw  or  cooked.  Two 
or  three  deailly  anianitas  ai'e  sufficient  to  cause  profound  iUness  with 
fatal  outcome  in  an  adult.  Plowright  reports  the  death  of  a  child  of 
twelve  from  eating  a  third  of  the  pileus  of  a  small  raw  plant. 

In  1891  Ivohert  isolated  from  Amanita  plialloides  a  substance  hav- 
ing a  powerful  hemolytic  action  which  he  called  phallin.  For  some 
time  it  was  believed  that  phallin  was  the  essential  poison  of  Amanita 
pliallouJeft.  but  Ford  '"  showed  that  there  is  another  substance  present 
which  is  much  more  toxic,  ar.d  to  which  most  of  the  symptoms  can 
probably  be  traced.  This  is  supported  by  tlie  fact  that  boiling  Amanita 
plialloides  mushrooms  destroys  its  hemolytic  power,  but  fails  to  neu- 
tralize its  toxic  action.  This  substance  Ford  has  called  "Amanitotoxin" 
and  states  that  it  has  no  hemolytic  action,  but  rather  produces  hemor- 
rhage and  causes  necrosis  and  fatty  degeneration  of  the  parenchymatous 
organs.  He  also  succeeded  in  producing  an  antihemolysin  which  com- 
pletely neutralizes  the  blood-laking  properties  of  phallin,  Clark, 
^farshall  and  Rountree  ^^  found  that  in  cases  of  Amanita  phalloidi's 
poisoning,  the  pathological  lesions  consist  chiefly  of  central  necrosis  of 
the  liver,  epithelial  necrosis  of  the  kidney,  acute  enteritis  and  colitis, 
the  kidneys  being  the  seat  of  the  most  marked  changes.  They  conclude 
that  nervous  and  mental  changes  observed  are  probably  uremic  in  char- 
acter, and  not  due  to  some  peculiar  "neurotoxin," 

The  symptoms  of  poisoning  by  Amanita  plialJoxdes  usually  do  not 
develop  for  from  6  to  15  hours  after  ingestion,  the  onset  being  marked 
by  very  sudden,  severe  abdominal  pain,  intense  thirst,  nausea,  retching, 
vomiting  and  very  profuse  water  evacuations,  sometimes  containing 
blood  and  mucus.  A  state  of  collapse  may  soon  develop.  There  is 
usually  a  rapid  loss  of  strength  and  flesh,  and  the  patient  develops  a 
peculiar  yellow  color.  The  pupils  are  usually  contracted:  the  breath 
is  quite  fetid  and  the  mucous  membranes  dry  and  glazed,  and  -there 
may  be  bleeding  from  the  gums.  Visual  disturbances  leading  to  con- 
fusion, delirium  and  convulsions  may  develop,  but  convulsions  are 
usually  due  to  a  mixed  intoxication,  which  in  turn  is  due  to  Amanita 
muscaria  being  mixed  with  Amanita  phaUoides.  After  3  or  4  days  in 
children,  and  usually  6  or  8  in  adults,  the  patients  sink  into  a  profound 

'"Jouryi.  Inf.  Dis.,  Ill,  2.  Apr..   1906,  p.   191, 
"J,  A.  M.  A.,  LXIV,  1915,  p.  1230. 


860  PLANT  FOODS 

coma  from  wliich  they  do  not  often  aw^ake.  Ford  ^^  states  that  the  case 
fatality  rate  of  Amanita  phalloides  poisoning  js  from  60  to  100  per  cent. 
The  danger  is  much  less  in  the  case  of  Amanita  muscaria. 

Muscarin  is  the  active  poisonous  principle  of  Amanita  muscaria 
(Agaricus  muscarius,  "fly"  amanita).  Muscarin  (CH3)3N0H.CH20H 
is  a  syrupy,  alkaloidal-like  substance  obtainable  in  crystallizable  form 
as  a  hydrochlorid.  It  was  first  isolated  by  Schmiedeberg  and  Ivoppe 
in  1869.  Chemically  it  evidently  is  an  ammonia  substitution  compound 
and  is  classed  with  the  ammonia  bases.  It  may  be  prepared  syn- 
thetically by  the  oxidation  of  cholin. 

The  physiological  action  of  muscarin  resembles  pilocarpin  very 
closel3^  It  stimulates  the  myoneural  junctions  between  the  nerves 
and  epithelial  cells.  Atropiu  is  an  almost  perfect  physiological  antidote 
for  muscarin,  paralyzing  the  myoneural  juiictions,  and  is-  used  with 
more  or  less  success  in  mushroom  poisoning. 

The  symptoms  of  muscarin  poisoning  come  on  quickly,  often  within 
15  minutes  after  eating  the  mushroom  (Amanita  muscaria).  They 
consist  of  salivation,  excessive  perspiration,  a  flow  of  tears,  nausea, 
retching  and  vomiting,  pain  in  the  abdomen,  and  violent  movement  of  the 
intestines,  causing  profuse  watery  evacuations.  The  pulse  is  sometimes 
quickened,  sometimes  very  slow  and  irregular.  The  pupil  is  contracted, 
respiration  often  quickened,  and  dyspneic.  Dizziness  and  confusion 
of  ideas  are  often  complained  of,  but  mental  symptoms  are  not  so  con- 
spicuous as  those  from  the  peripheral  organs.  Mental  symptoms,  such 
as  hallucinations,  delirium  and  convulsions  are  attributed  to  the  Pilcz- 
toxin  of  Harmsen.  Eventually  the  respiration  becomes  slower,  great 
muscular  weakness  supervenes,  but  consciousness  remains  more  or  less 
clear  until  the  breathing  ceases. 

The  peasants  of  the  Caucasus  prepare  an  intoxicating  beverage  from 
A.  muscaria  which  produces  wildly  riotous  drunkenness.  Death  from 
muscarin  orgies  is  not  uncommon  in  this  part  of  Kussia.  Similar  spe- 
cies in  ISTortheastern  Asia  are  also  used  as  an  intoxicant.  The  poison 
is  excreted  in  the  urine  which  is  sometimes  later  consumed  for  its  intoxi- 
cating effect.  It  is  probable  that  a  sort  of  tolerance  to  muscarin  is 
developed  among  the  habitual  users  of  the  muscaria  decoction. 

The  alkaloid  is  soluble  in  water  and  poisoning  may  be  prevented 
by  soaking  the  mushrooms  in  water  slightly  acidulated  with  vinegar 
before  they  are  cooked. 

Hemolysin. — Kobert  in  1891  obtained  a  hemolytic  substance  by  alco- 
holic precipitation  from  .4.  phalloides.  This  substance  he  named  plial- 
lin;  it  is  an  extremely  complicated  substance,  having  the  nature  of 
a  glucose;  that' is,  it  contains  sugar  in  its  molecule.  It  is  not  always 
present  in  A.  phalloides  and  is  probably  not  an  essential  poison  in  this 

"  Journ.  Inf.  Bis.,  Ill,  2,  Apr.,  1906,  p.  191. 


roiSONors    IM.ANTS  861 

mushroom,  for  its  activity  is  dcst roved  at  70°  ('.  and  also  hy  tlic 
action  of  the  gastric  juice.  A  liii;li  i^rade  iiiiiiiuiiity  can  he  estab- 
lished in  animals  to  the  lieinolytic  suhstaiice.  I'nid  olttaiiied  an  anti- 
hemolysin  ■which  coiii]iletcly  neutralizes  the  hlood-lakiug'  properties  of 
this  poison. 

The  hemolysin  probal)ly  i)lays  a  small  role,  if  any,  in  human  intoxi- 
cation. .1.  rubescens,  considered  by  the  majority  of  mycologists  to  be 
an  edible  mushroom,  contains  a  powerful  hemolysin.  On  the  other  hand, 
a  hemolytic  poison  is  found  in  TlelreUa  or  Gijroiiii/lra  esculenla  which 
occurs  rarely  in  this  country.  The  active  principle  is  helvellic  acid 
(Boehm  and  Kiilz)  which  produces  in  dogs  all  the  signs  of  hemolytic 
intoxication  similar  to  those  sometimes  found  in  man. 

-Morner  gives  eight  pages  of  references  to  mushroom  poisoning.'''* 

Potato  Poisoning". — Outbreaks  of  poisoning  attrilnitod  to  potatoes 
have  occurred  largely  among  troops.  Schmiedeberg  '*  reports  out- 
breaks invoking  357,  90,  125  and  101  men,  respectively,  and  Pfuhl'''" 
records  an  outbreak  involving  56  soldiers.  In  all  cases,  the  outbreaks 
Avere  attributed  to  potatoes,  sometimes  new,  sometimes  old  sprouting 
ones,  and  sometimes  potato  salad. 

The  onset  of  symptoms  occurs  usually  only  a  few  hours  after  eating 
the  potatoes.  Symptoms  reported  have  been  headache,  abdominal  pains,* 
nausea,  vomiting,  diarrhea,  prostration,  dizziness,  drowsiness,  and  slight 
delirium.  Fever  has  usually  been  absent.  In  some  cases,  dilatation  of 
the  pupils  is  reported.  The  symptoms  only  very  rarely  become  threat- 
ening and  practically  all  the  victims  recover  rapidly. 

These  cases  were  long  regarded  as  solanin  poisoning,'  but  it  is  now 
plain  that  this  does  not  account  for  most  outbreaks,  some  of  which  at 
least  are  bacterial  in  origin. 

Solanin  (C^oH-gOi^lSr^)  is  a  glucosidal  alkaloid  closely  resembling 
the  saponins  in  reaction,  and  found  in  many  species  of  Solanum,  such 
as  S.  nigrum  (black  nightshade),  8.  dulcamara  (bitter  sweet),  and  S. 
tuberosum  (potato).  The  solanin  content  is  highest  in  the  potato  peel, 
decreasing  towards  the  center  of  the  potato.  It  has  also  been  held  to 
occur  chiefly  in  immature,  sprouting  or  diseased  potato  parts  which 
ordinarily  are  discarded  before  cooking. 

Toxicologic  tests  on  man  have  demonstrated  that  0.2  gram  of 
isolated  solanin  may  provoke  untoward  symptoms.  Seldom  would  that 
amount  occur  in  the  quantity  of  potatoes  which  an  adult  might  con- 
sume in  the  course  of  a  day.  Owing  to  variations  in  purity,  it  is  not 
possible  to  state  how  much  solanin  would  be  necessary  to  cause  poi- 
soning. 

"  T'psaJa  Lakarefornings  Forkandhnqar.  Jan.  20,  1914,  XXIV,  Xos.  1  ami  2. 
'Mrc/i.  /.  Exp.  Path.  u.  Pharm..  Vol.  XXXVI.   1895. 
''  Deutsch.  med.  Wochenschr..  1899. 


863  PLANT  FOODS 

Meyer  ^^  showed  that  the  solanin  content  of  potatoes  varied  with 
the  season,  ranging  from  0.04  gram  per  kilo  during  the  winter  to  0.116 
gram  during  the  summer.  In  vigorously  sprouting  and  diseased  pota- 
toes, he  found  as  much  as  1.34  grams  of  solanin  per  kilo.  Wintgen  ''' 
also  found  a  fluctuating  solanin  content  in  sound  potatoes  (0.017  to  0.08 
gram  per  kilo),  hut  the  quantity  was  always  small.  Even  in  sprouted 
potatoes,  he  observed  no  increase  in  the  solanin  content,  provided  the 
sprouts  were  carefully  removed.  He  was  unable  to  find  an  increased 
amount  in  diseased  potatoes.  AVintgen  was  also  unable  to  confirm  the 
statement  of  Weil  "'^  that  the  solanin  in  potatoes  was  increased  by  the 
activity  of  two  organisms  (bacterium  soJaniferum  non-colorahile  and 
laclerium  soJaniferum  colorahile).  Harris  and  Cockburn,'^  in  an  out- 
break in  Glasgow  involving  61  people,  showed  that  the  incriminated 
potatoes  contained  0.41  gram  per  kihj  of  solanin,  an  amount  which  they 
interpret  as  being  five  or  six  times  the  normal  content. 

Eothe  ®°  studied  a  recent  outbreak  in  Leipzig.  The  symptoms  were 
abdominal  pain,  vomiting  and  diarrhea.  An  analysis  of  the  same  lot  of 
tubers  disclosed  0.43  gram  of  solanin  per  kilogram,  which  is  about  ten 
times  the  quantity  found  ordinarily  in  potatoes.  The  conclusion  is 
drawn  that  the  possibility  of  solanin  poisoning  must  be  reckoned  with, 
especially  when  potatoes  prematurely  harvested  are  used  as  food. 

It  now  appears  probable  that  most  instances  of  potato  poisoning  are 
not  due  to  solanin,  but  axe  bacterial  infections.  Thus,  Dieudonne  *^  re- 
ports an  outbreak  of  poisoning  attributed  to  potato  salad,  in  which  the 
solanin  content  was  only  0.021  gram  per  kilo.  The  symptoms  were 
identical  with  those  usually  attributed  to  potato  poisoning.  Bacillus 
proteus  was  present  in  considerable  numbers  in  the  potato  salad,  and 
when  grown  on  sterile  potato  medium,  a  highly  poisonous  culture  was 
obtained  which  was  fatal  to  mice  in  twenty-four  hours.  In  most  of  the 
reported  cases,  the  potatoes  were  prepared  at  least  several  hours  before 
they  were  eaten,  and  had  been  left  in  places,  favorable  to  bacterial  infec- 
tion. Potatoes  make  an  excellent  nutrient  culture  medium.  Typhoid, 
paratyphoid,  B.  enteritidis  and  many  other  pathogenic  microorganisms 
grow  well  on  potato. 

'"Arc/i  /.  Ewp.  Path.  u.  I'liarm.,  Vol.  XXXVI.  1805. 

''''  Zeitschr.  fur  Vntersuchung  der  'Xahrunqs  und  Genussniittel.  Vol.  XII,  1906, 

'^Arch.  f.  Hyg..  Vol.  XXXVIII,  1900. 

'^Analyst,  4.3,  133,  7,  1918;  Chem.  Ahst.,  Vol.  XII,  No.  13,  p.  1403. 

^Deutsch.  f.  Hyg.,  88,   1,  1919. 

"  Deutsch.  militarzth,  Zeitsch/r.,  1904. 


TJEFKIJEXCES  8G3 


REFERENCES 


Bavliss,  W.  M.  :     "The  Physioloi-y  of  Food  and  Efonoiny  in  Diet."     Long- 
mans, Green  and  Co.,  London,  1917. 
Edlemaxn,  R.,  MoHLKR,  J.  R.,  and  Eichhorn,  A.:     ''Meat  Hygiene."    Lea 

and  Fibiger,  Xew  York,  1919. 
JoRDAX,  Emvix    O. :     "Food  Poisoning."     Univ.  of  Chicago  Press,  Chicago, 

1917. 
LusK,  Graham:     "The  Elements  of  the  Science  of  Nutrition."     W.  B. 

Saunders  and  Co.,  3rd  Ed.,  1919. 
LuSK,  Graham:     "The  Fundamental  Basis  of  Nutrition."     New  Haven, 

1914. 
McCoLLUM,  E.  Y. :    "The  Newer  Knowledge  of  Nutrition."    The  Macmillan 

Co.,  New  York,  1918. 
S-WAGE,  Willia:^!  G.  :    "Food  Poisoning  and  Food  Infections."    Cambridge 

LTniversity  Press,  1920. 


SECTION  VI 
AIR 

CHAPTER  I 
COMPOSITION  OF  THE  AIR 

The  air  constitutes  a  gaseous  ocean  in  which  we  live;  it  consists  of 
a  vast  volume  of  gases  at  least  one  hundred  miles  high.^  Ordinarily  we 
speak  of  this  gaseous  envelope  of  the  earth  as  the  atmosphere,  and  the 
water  resting  upon  the  surface  of  the  earth  as  the  aquasphere,  while  the 
solid  structure  of  the  earth  is  called  the  petrosphere.  Between  the 
atmosphere  on  the  one  hand  and  the  petrosphere  and  aquasphere  on  the 
other  hand  is  the  region  of  most  ahundant  life,  and  this  is  spoken  of  as 
tlie  rivospliere. 

Tlie  importance  of  fresh  air  was  almost  completely  ignored  in  prac- 
tical life  until  recently — thanks  to  the  tuberculosis  propaganda.  While 
recent  studies  have  shown  that  the  air  is  not  to  be  feared  as  a  frequent 
medium  for  conveying  specific  infections,  it  has  been  demonstrated  that 
an  abundant  supply  of  fresh  air  is  necessary  to  perfect  well-being.  Sta- 
tistical studies  seem  to  prove  that,  of  the  predisposing  causes  to  sick- 
ness Avhich  are  usually  in  action,  impurities  of  the  air  are  perhaps  the 
most  important.  This  has  been  stated  over  and  over  again  in  the  case 
of  horses,  cattle,  and  dogs,  as  well  as  of  men  confined  in  badly  ventilated 
barracks,  jails,  and  other  places. 

Many  other  factors  are  now  known  to  be  a  greater  menace  to  health 
than  the  ''bad"  air  of  crowded  places;  sanitariians,  however,  have  come 
to  regard  an  abundant  supply  of  pure  fresh  air,  well  conditioned,  as 
one  of  the  real  essentials  for  health  and  maximum  efficiency.  Many 
of  the  ill  effects  attributed  to  bad  air  are  really  due  to  crowding.  Crowd- 
ing forces  the  occupants  into  close  personal  contact  and  thus  favors 
the  spread  of  infections.  It  is  a  well  recognized  principle  in  military 
hygiene  that  in  a  crowded  barracks,  with  good  or  bad  air,  there  will  l>e 
an  excessive  amount  of  pneumonia,  sore  throats,  colds  and  other  inflam- 
matory affections  of  the  upper  respiratory  passages — which  at  times 
become  epidemic. 

'  Forty-five  or  fifty  miles  is  its  practical  limit,  and  anything  beyond  that 
distance  is  in  an  extremely  tenuous  state. 


866  COMPOSITION  OF  THE  AIR 

While  fresh  air  is  so  necessary  to  perfect  well-being,  nevertheless 
some  people  get  along  with  surprisingly  little,  and  that  often  vitiated. 
Many  people  sleep  huddled  up,  with  their  faces  completely  covered  as 
though  they  w^ould  suffocate.  In  Holland  many  people  sleep  in  an  ar- 
rangement not  unlike  a  closet,  and  yet  retain  rugged  health.  Dogs, 
sheep,  and  animals  sleep  huddled  up,  with  their  faces  completely  cov- 
ered, sometimes  in  caves  or  dens  where  the  air  must  be  very  bad.  It  is 
evident  that  the  factor  of  safety  must  be  very  large,  also  that  the  ques- 
tion of  habit  plays  a  conspicuous  role,  for  persons  accustomed  to  good 
fresh  air  are  rendered  truly  miserable  when  confined  to  a  close,  stuffy 
room. 

The  two  chief  functions  of  the  air  that  are  especially  concerned  with 
health  are  (1)  interchange  of  gases  in  respiration,  and  (2)  regulation  of 
bodily  temperature.  Further,  it  should  be  remembered  that  the  com- 
bustion of  the  food  we  eat  depends  upon  the  oxygen  of  the  air  we  breathe, 
and  that  digestion  and  metabolism  are  stimulated  and  improved  by  an 
abundant  supply  of  fresh  air  or  rendered  sluggish  and  retarded  by  pro- 
longed exposure  to  vitiated  air. 

The  atmosphere  is  now  known  to  contain  the  following  gases  in  the 
following  approximate  proportions  measured  at  0°  C.  and  at  760  mm. 
pressure : 

Yolumes        Weight 
Per  Cent.     Per  Cent. 

Oxygen 20.93  23.2 

Nitrogen 78.10  76.8 

Carbon   dioxid 0.03 

Argon 0.94 

Helium,  krypton,  neon,  xenon,  hydrogen, 

hydrogen  peroxid,  ammonia,  ozone traces 

"Pure"  air,  in  addition,  contains  water  vapor  in  varying  amounts, 
dust,  radioactive  substances,  etc. 

The  air  is  a  mixture  of  gases  and  not  a  chemical  compound.  The 
proofs  of  this  are  manifold :  ( 1 )  the  gases  do  not  exist  in  the  air  in 
the  proportion  of  their  combining  weights  or  any  multiple  of  them; 
(2)  on  mixing  the  gases  in  atmospheric  proportions  there  is  no  heat 
evolved;  (3)  the  composition  of  air  within  limits  is  variable;  (4)  when 
water  dissolves  air  it  dissolves  each  gas  according  to  its  partial  pres- 
sure and  its  own  proper  coefficient  of  solubility.  Thus,  air  contains 
more  nitrogen  than  oxygen,  but,  oxygen  being  more  soluble,  water  takes 
up  1.87  parts  of  oxygen  to  1  part  of  nitrogen. 

Jean  Mayow  in  1669  first  proved  that  air  was  not  an  element,  but  a 
mixture  of  gases,  and  later  Lavoisier  discovered  the  two  gases  which 
about  100  years  afterwards  were  separated  by  Priestley  and  Sheele. 

The  composition  of  the  air  shows  wonderful  uniformity  all  over  the 
earth's  surface  wherever  examined.    This  is  due  to  the  enormous  amount 


N 

CO: 

79.04 

.0;^ 

79. 

5,0 

()XV(iKN  867 

*» 
of  atiiiosplK'ii'  and   tlic  inixiiii;-  iiilluciict's  of  air  cuiTciils.      llowevt'i',  in 

confined  spaces  where  tlie  air  is  not  in  motion,  especially  where  decom- 
])osition  of  organic  matter  is  taking  ])hice  or  where  active  combustion  is 
going  on,  or  in  the  presence  of  animal  life,  the  comi)osition  of  the  air 
varies  considerably. 

The  ditTorencc  in  compofition  betweeii  inspir(>(l  and  ex))ircd  air,  ex- 
pressed as  volumes  })er  cent,  at  0°  C.  and  7(50  nnn.,  is  as  follows: 

O 

Inspired    air 20.93 

Expired   air IG. 

The  expired  air  is  also  warmer,  is  increased  in  volume,  and  contains 
more  moisture,  but  fewer  particles,  such  as  dust  and  bacteria.  Under 
normal  conditions  of  quiet  respiration  the  expired  breath  contains  no 
bacteria. 

OXYGEN 

About  one-fifth  (20.94  per  cent,  by  volume^  23.2  per  cent,  by  weight) 
of  the  atmosphere  consists  of  oxygen,  which  in  many  respects  is  its 
most  important  element.  Slight  difi^erences  are  noted;  thus,  the  air  of 
towns  contains  somewhat  less  (20.87  per  cent,  by  volume)  than  in  mid- 
ocean.  The  slight  differences  that  have  been  noted  in  the  percentage  of 
oxygen  are  of  no  special  importance.  It  may  drop  to  15  per  cent,  or 
may  rise  to  50  per  cent,  or  even  higher  without  any  very  apparent  altera- 
tion in  the  vital  functions.  An  atmosphere  containing  only  11  to  12  per 
cent,  of  oxygen  becomes  dangerous,  and  7.2  per  cent,  results  in  death. 
In  submarines,  16  per  cent,  is  the  signal  to  replenish  oxygen  from  the 
tank.  A  candle  goes  out  at  16  per  cent.,  and  an  acetylene  fiame  at  121/^ 
per  cent. 

Haldene  -  and  his  collaborators  have  shown  that  oxygen  deficiency 
(anoxemia)  increases  the  rate  of  respiration,  whereas  accumulating  car- 
bon dioxid  increases  the  depth  of  respiration  without  essentially  altering 
the  rate.  On  the  other  hand,  long  exposures  to  an  atmosphere  contain- 
ing a  great  excess  of  oxygen  may  act  as  an  irritant.  Karsner  and  Ash  ^ 
found  that  rabbits  show  little  effect  when  exposed  for  eleven  days  to  an 
atmosphere  containing  oxygen  between  60  and  70  per  cent.,  but  above 
this  point  irritation  of  the  lungs  and  pneumonia  supervene. 

The  amount  of  oxygen  absorbed  depends  rather  upon  the  needs  of 
the  body  than  upon  the  amount  in  the  air.  About  5  per  cent,  of  the 
oxygen  in  the  air  is  removed  by  respiration. 

Alveolar  air  normally  contains  about  16  per  cent,  of  oxygen,  and 

j         'Journ.  Physiol.,  32,  225.  1905;  also  "52,  420,  1919. 
Vowrn.  L06.  flHcZ  C«?i.  J/cf^.,  II,  No.  4,  Jan.,  1917. 


868  COMPOSITION  OF  THE  AIR 

the  Ted  blood  cells,  as  they  leave  the  lungs,  are  practically  saturated  with 
it.  The  amount  taken  up  on  their  next  trip  through  the  lungs  depends 
on  how  much  they  have  given  up  to  the  tissues  in  the  meantime,  not 
upon  how  much  is  available  for  their  use.  The  normal  16  per  cent,  of 
oxygen  in  the  alveolar  air  is  automatically  maintained  by  the  action  of 
the  COo  on  the  respiratory  center,  but  on  account  of  the  chemical  affinity 
of  the  hemoglobin  for  oxygen  the  blood  cells  may  still  take  pr^actically 
their  full  capacity  of  oxygen  when  it  is  reduced  to  18  per  cent,  or  less 
in  the  alveolar  air.  In  other  words,  a  large  excess  of  oxygen  is  con- 
stantly maintained  in  the  air  of  the  lungs.  While  it  is  one  of  the  chief 
functions  of  respiration  to  supply  oxygen  to  the  body,  neither  a  surplus 
nor  a  deficiency  of  it  in  the  air,  unless  the  alteration  is  extreme,  has 
any  effect  on  the  respiratory  movements.  Breathing  will  not  be  lessened 
nor  more  oxygen  taken  up  because  more  of  it  is  supplied  to-  the  lungs ; 
nor  will  the  oxidation  processes  in  the  body  be  affected  in  any  way,  unless 
other  influences  are  simultaneously  brought  into  play.  Indeed,  Hender- 
son reminds  us  that  it  is  necessary  to  go  only  a  short  distance  up  into 
the  mountains  to  come  under  an  atmospheric  pressure  such  as  to  reduce 
the  oxygen  supply  considerably.  Yet  mountain  air  is  especially  health- 
ful. Except  in  extreme  conditions  the  amount  of  oxygen  in  the  closest 
halls  crowded  with  people  practically  never  falls  below  20  per  cent.  The 
amount  of  oxygen  in  the  air  apparently  has  little  or  nothing  to  do  with 
the  stimulating  or  depressing  properties  of  the  atmosphere  breathed  in 
ordinary  life. 

The  constant  percentage  of  oxygen  is  due  in  part  to  the  enormous 
amount  of  it.  Flligge  estimates  that  at  the  present  rate  at  which  the 
oxygen  is  used  by  respiration  and  combustion  it  would  take  eighteen 
thousand  years  to  reduce  it  by  one  per  cent.,  even  if.  not  replaced  by 
vegetation.  The  lungs,  of  course,  at  no  time  after  the  first  breath 
contain  air  with  the  full  percentage  of  oxygen.  This  is  owing  to  the 
fact  that  the  lungs  do  not  completely  empty  themselves,  and  the  resid- 
ual air  remaining  in  the  lungs  accumulates  carbon  dioxid  and  loses 
oxygen. 

Oxygen  is  the  element  in  the  air  that  sustains  all  life.  It  is  ab- 
sorbed by  the  lungs,  passes  into  the  blood,  combines  loosely  with  the 
hemoglobin  of  the  red  blood  corpuscles,  and  is  thus  carried  to  all  the 
tissues  and  cells  of  the  body.  Oxygen  in  combination  with  the  hemo- 
globin forms  an  unstable  compound — oxyhemoglobin — which  gives  the 
bright  red  color  to  arterial  blood.  The  oxygen  bound  with  the  hemo- 
globin in  arterial  blood  consists  of  from  22  to  25  per  cent,  of  the  volume 
of  the  blood.  The  amount  of  oxygen  absorbed  varies  with  the  age,  con- 
dition of  health,  and  activity.  According  to  Professor  Foster,  the  aver- 
age person  inhales  in  24  hours  about  34  pounds  of  air,  which  corre- 
sponds to  a  little  over  7  pounds  of  oxygen.     As  the  lungs  absorb  about 


OZONE  8G9 

one-fourth  of  the  oxygen  inhaled,  it  appears  that  the  average  amount 
of  oxygon  ahsorbed  daily  is  nearly  two  ))<)\in(ls.  Oxygen  also  exists  in 
its  gaseous  form  in  blood,  saliva,  bile,  urine,  and  otbor  fluids  of  the 
body,  biii  only  in  niiinitc  junouiits. 

The  amount  of  oxygen  in  the  air  may  readily  be  measured  in  the 
Petterson-l'almquist  or  Haldane  aiij^aratus.  The  oxygen  is  absorbed 
by  10  per  cent,  pyrogallic  acid  in  a  saturated  solution  of  KOH  (sp.  gr. 
l.OoS)  ;  the  difference  in  volume  before  and  after  absorption  represents 
the  amount  of  oxygen   (jtages  .STS-H.SO), 

Determinations  of  the  amount  of  oxygen  of  tlie  atmosphere  have 
no  particular  hygienic  significance. 


NITROGEN 

The  nitrogen  in  the  air  may  be  regarded  as  a  diluent,  and  as  inert 
so  far  as  its  direct  action  upon  man  is  concerned.  There  is  no  appre- 
ciable difference  in  the  amount  of  nitrogen  contained  in  inspired  and 
expired  air.  Xitrogen  does  not  "dilute"  the  oxygen,  and  thus  regulate 
respiration  in  the  same  way  that  it  controls  the  rate  of  combustion  of 
substances  in  the  air.  Xitrogen  is  of  more  direct  importance  to  plants, 
as  certain  genera  are  able  to  fix  some  of  the  atmospheric  nitrogen 
through  the  action  of  bacteria,  as  B.  radicicola,  in  the  root  nodules  of  le- 
gumes. While  nitrogen  in  the  atmosphere  seems  to  be  an  indifferent  ele- 
ment and  has  no  hygienic  significance,  it  is  a  constant  and  important 
constituent  of  all  protein  matter.  The  amount  of  nitrogen  dissolved 
as  a  gas  in  the  blood  and  body  juices  increases  proportionately  with  the 
pressure  (P.  Bert),  and  may  lead  to  gas  emboli,  as  in  caisson  disease. 


ARGON 

Argon,  discovered  in  1894  by  Lord  Bayleigh  and  Professor  Eamsey, 
is  quite  inert  chemically;  that  is,  it  has  not  been  made  to  combine  with 
any  other  element.  It  comprises  from  0.75  to  1  per  cent,  of  the  atmos- 
phere. Argon  has  not  been  demonstrated  in  the  body;  it  is  apparently 
indifferent,  and.  so  far  as  our  present  knowledge  goes,  has  no  hygienic 
significance. 

OZONE 

Ozone,  described  by  Schonbein  in  1840,  is  rarely  found  in  the  air 
in  greater  proportions  than  mere  traces,  but  it  is  so  potent  chemically 
that  even  small  quantities  may  be  of  importance.  At  ^Montsouris,  after 
years  of  observation,  the  largest  quantity  of  ozone  found  in  outside  air 


870  COMPOSITTOX  OF  THE  AIR. 

was  1  part  in  700.000.  Ozone  may  be  regarded  as  a  normal  constituent. 
though  by  no  means  constant  in  air.  It  is  generally  absent  in  the  air 
of  large  towns  and  cities,  and  almost  never  present  in  the  air  of  in- 
habited rooms.     It  is  most  abundant  at  sea  and  near  woods. 

Atmospheric  ozone  is  formed  iii  nature  during  electric  discharges,  by 
the  oxidation  of  phosphorescent  substances;  and  perhaps  by  the  respira- 
tion of  plants;  also  by  friction  of  large  masses  of  water,  such  as  the 
sea  against  the  air. 

Ozone  consists  of  three  atoms  of  oxygen  instead  of  two,  compressed 
into  a  molecule,  thus:  3  Oo^='i  0^.  It  is  one  of  the  most  powerful  oxidiz- 
ing agents  knowii.  and  in  small  amounts  is  exceedingly  irritating:  in 
large  amounts  it  is  fatal  to  life.  Ozone  is  one  of  our  most  active  bleach- 
ing agents,  and  in  proper  concentration  is  one  of  the  most  potent  germi- 
cides known,  and  is  used  to  sterilize  water,  to  disinfect  bandages,  and 
for  other  purposes. 

It  requires  at  least  13  parts  of  ozone  per  million  in  the  atmosphere 
to  influence  bacteria.  Such  large  proportions  are  never  present  under 
natural  conditions.  Comparatively  small  amounts  are  irritating  to  the 
respiratory  mucous  membrane.  Thus.  Hill  and  Flack  *  have  studied 
the  action  of  pure  ozone  (free  of  contaminating  oxids  of  nitrogen),  and 
find  it  irritating  in  the  proportion  of  one  part  per  million.  Exposure 
for  two  hours  to  a  concentration  of  15  to  20  parts  per  million  endan- 
gers life.  Hill  and  Flack  conclude  that  there  is  no  harm  in  breath- 
ing weak  concentrations  of  ozone,  such  as  can  scarcely  be  perceived  by 
a  keen  sense  of  smell. 

Bohr  and  Maar  found  that  any  considerable  concentration  (even 
less  than  1  part  per  million)  diminishes  the  oxygen  intake  and  the  car- 
bon dioxid  output.  The  symptoms  produced  by  exposure  to  ozone  in 
addition  to  irritation  of  the  mucosa,  are  headache,  restlessness,  drowsi- 
ness, depression  and  coma. 

Since  ozone  in  concentration  of  one  part  per  million  parts  of  air  is 
certainly  injurious,  and  since  this  amount  of  ozone  will  not  destroy 
odors  nor  kill  bacteria,  nor  purify  organic  matter,  it  has  no  hygienic 
value  and  should  not  be  used  as  a  substitute  for  room  ventilation  or  to 
purify  air  in  offices,  schools,  and  other  occupied  spaces. 

Ohlmiiller  ^  demonstrated  that  ozone  in  considerable  strength  was 
incapable  of  killing  dry  bacteria  within  the  time  limits  of  his  tests. 
Jordan  and  Carlson  ®  and  also  Konrich  '  found  that  ozone  ranging  from 

"^  Proceed.  Royal  Society,  London,  B,  1911,  LXXXIV,  404. 

^ 'T'eber  die  Einwirkung  des  Ozons  auf  Bakterien."  Arh.  a.  d.  k.  Gesundheits- 
umfe,  1893.  VIII,  229. 

^Jordan,  E.  0.,  and  Carlson,  A.  J.:  "Ozone:  Its  Bactericidal,  Physiologic 
and  Deodorizing  Action,"  J.  A.  M.  A.,  Sept.  27,  191.3.  LXI.  Xo.  13,  Part  1, 
p.   1007. 

'Konrich:  "Ziir  Verwendung  der  Ozons  in  der  Liiftimg,"  Ztschr.  f.  Byg., 
1913,  LXXIII,  443. 


HYDROGEN  PEKOXIl)   (UJ),)  871 

3  to  4.0  parts  per  iiiilliun  oxcrts  iiu  surely  germicidal  action,  and  that 
the  alle^anl  etlects  of  uzonc  on  the  ordinary  air  bacteria,  if  it  occurs  at 
all,  is  slight  and  irregular  even  when  amounts  of  ozone  far  beyond  the 
limit  of  human  physiologic  tolerance  are  employed. 

Iluman  beings  are  injuriously  affected  by  amounts  of  ozone  far  less 
than  are  necessary  to  produce  even  a  slight  bactericidal  effect.  Ozone, 
tiierefore,  has  no  place  in  practical  disinfection  of  occupied  places. 

The  exaggerated  claims  of  the  deodorizing  properties  of  ozone  are 
not  justified.  Ozone  masks  disagreeable  odors  without  destroying  them. 
In  this  way  ozonizing  machines  can  conceal  faults  in  ventilation  while 
not  correcting  tliem.  These  conclusions  have  been  reached  by  Jordan 
and  Carlson,  p]rlandsen  and  Schwarz.  Hill  and  Flack,  and  Konrich, 
Sawyer,  and  others.  The  Xew  York  State  Commission  on  Ventilation 
found  that  ozone  failed  to  destroy  body  odors  in  the  recirculated  air 
of  a  school, 

Eecently  ozonizers  have  been  placed  upon  the  market  for  the  pur- 
pose of  purifying  the  air  of  rooms;  these  must  not  be  regarded  as  sub- 
stitutes for  ventilation.  Xot  only  may  the  ozone  itself  be  harmful,  but 
the  higher  oxids  of  nitrogen  may  be  formed  when  the  electric  current 
acts  upon  moist  air.  Ozone  is  a  poison  rather  than  a  purifier.^  See 
also  pages  1129  and  1401:. 

The  tests  for  ozone  depend  upon  the  fact  that  it  oxidizes  the  color 
of  tincture  of  guaiac,  causing  it  to  turn  blue.  It  also  acts  upon  potassium 
iodid,  which  turns  starch  a  blue  color  due  to  the  presence  of  free  iodin : 
2KI+H,0+0=2KOH+l2. 

Method  for  determining  the  amount  of  ozone  in  air  is  that  recom- 
mended by  Baumert  modified  by  Hill  and  Flack. ^ 

Ten  liters  of  ozonized  air  are  drawn  through  a  bottle  containing  50 
c.c.  of  1  per  cent,  solution  of  potassium  iodid  acidified  by  5  c.c.  of  10 
per  cent,  solution  of  sulphuric  acid;  1  c.c.  of  1  per  cent,  solution  of 
boiled  starch  added,  and  titrated  with  hyposulphite  solution.  The  hypo- 
sulphite solution  is  made  up  to  contain  0.222  gm.  per  liter,  so  that  1  c.c. 
of  the  solution  represents  1  part  of  ozone  per  million  parts  of  air  when 
10-liter  air  samples  are  used. 


HYDROGEN  PEROXID   (H.O,) 

Hydrogen  peroxid  nuiy  be  found  in  appreciable  traces  in  rain  and 
snow.     One  liter  of  rain  or  snow  water   contains  about  0.1S2  mg.   of 

"Sawyer,  W.  A..  lit-ckAvilh.  Helen  L..  and  Skutield.  Esther  .M. :  --The  Alleged 
Purification  of  Air  bv  the  Ozone  Machine."  J.  A.  M.  A..  Sept.  27,  1913.  LXI,  13, 
p.  1013. 

"Hill  and  Flack:  Proc.  Roif.  Soc,  1911.  LXXXII.  404;  Jour.  Roi/.  Soc. 
Arts.  1912.  LX.  344, 


872  COMPOSITIOX  OF  THE  AIR 

hydrogen  })eroxid.  This  higher  oxid  gives  many  of  the  reactions  of 
ozone,  being  a  very  active  oxidizing  agent,  and  care  must  be  exercised 
not  to  confuse  them. 

AMMONIA 

The  ammonia  in  the  air  comes  largely  from  the  decomposition  of 
organic  matter.  It  is  produced  in  sufficient  quantities  in  a  manure 
heap  to  be  perceptible  to  the  senses.  Ammonia  may  be  regarded  as  one 
of  the  normal  constituents  of  the  atmosphere,  as  it  is  constantly  pres- 
ent in  slight  traces;  it  varies  in  distribution,  more  being  found  in  the 
lower  stratum  of  air  near  the  soil.  It  exists  both  in  the  free  state  and" 
also  combined  as  nitrate  and  carbonate.  Daily  analysis  of  the  air  at 
the  observatory  at  Montsouris  for  five  years  gave,  as  a  mean  for  am- 
monia, 2.2  mg.  per  100  cu.  m.  There  is  less  after  rain,  because  it  is 
absorbed  by  the  water  during  its  passage  through  the  atmosphere. 

Albuminoid  ammonia,  according  to  Angus  Smith,  is  a  measure  of 
the  sewage  of  the  air;  that  is,  the  amount  of  organic  impurities,  both 
living  and  dead. 

MINERAL  ACIDS 

The  atmosphere  at  times  contains  nitric,  sulphuric,  and  other  acids. 
These  are  derived  from  electric  discharges,  but  mainly  from  the  com- 
bustion of  coal  and  from  industrial  processes.  Sulphuric  acid  or  sul- 
phates in  the  air,  according  to  Angus  Smith,  is  a  measure  of  manu- 
facturing activity  and  also  of  decomposition.  In  other  words,  it  is 
part  of  the  oxidized  and.  therefore,  purified  sewage  of  the  air.  Traces 
of  sulphuric  and  sulphurous  acids  exist  in  the  air.  The  sulphates  and 
sulphites  are  usually  present  as  ammonia  salts.  These  substances  are 
usually  present  in  such  small  amounts  that  they  are  appreciable  only 
when  washed  into  rain  or  snow.  A  liter  of  rain  water  may  contain 
from  0.7  to  2.99  mg.  of  sulphuric  acid.  More  of  this  acid  is  found 
in  the  air  about  industrial  centers  than  in  the  air  over  country  or  sea. 
The  sulphuric  acid  in  the  air  comes  mainly  from  the  sulphur  in  coal. 


CARBON  DIOXID 

Carbon  dioxid  (COo)  is  a  very  important  constituent  of  the  atmos- 
phere. The  amount  of  this  gas  in  the  air  is  relatively  small — normally 
about  0.03  per  cent.,  usually  expressed  as  3  parts  in  10,000.  When  we 
consider  the  great  bulk  of  the  atmosphere  the  total  amount  of  carbon 
dioxid  is  verv  great.     It  is  estimated  that  there  is  more  carbon  in  the 


CAHBON  DIOXID  873 

form  of  carbon  dioxid  in  the  air  tiian  tliere  is  in  all  other  forms  on  the 
earth.  Formerly  tlie  amount  of  carbon  dioxid  in  Ibe  air  was  stated  as  4 
parts  in  10, 000.  hut  rcpcali'd  analyses  with  inipioxcMl  nictiiods  have 
shown  that  the  correct  amount  is  3  parts  or  slightly  more.'"  There  is 
apt  to  be  more  carbon  dioxid  in  the  air  just  above  the  soil  than  at  a 
height  of  8  or  10  feet.  This  is  not  because  the  carbon  dioxid  is  heavy 
and  settles,  but  because  the  soil  air  usually  contains  more  of  this  gas. 
Air  collected  at  great  heights  by  balloons  has  just  the  same  percentage 
of  CO,  as  air  at  sea  level.  The  air  over  the  sea  contains  somewhat  less 
than  air  over  the  land.  Carbon  dioxid  in  the  air  comes  from  the  oxida- 
tion of  organic  matter,  from  respiration,  from  fermentation,  from 
chemical  action  in  the  soil,  and  from  mineral  springs.  The  exhaled 
breath  contains  about  5  per  cent,  of  CO2. 

Even  a  small  alteration  in  the  percentage  of  carbon  dioxid,  either 
up  or  down,  would  throw^  out  of  adjustment  a  long-established  balance. 
and  this  would  alter  the  climate  of  the  earth  and  might  cause  the  death 
of  all  living  beings.  The  carbon  dioxid  in  the  air  is  the  source  from 
which  gr^en  plants  with  the  assistance  of  sunlight  obtain  their  carbon, 
and  is  thus  indirectly  the  source  of  the  carbon  in  the  bodies  of  animals. 
The  normal  variations  in  the  carbon  dioxid  of  air  in  the  open  are  too 
small  to  be  of  sanitary  importance,  and  it  is  only  when  stagnant  or 
inclosed  air  is  polluted  by  combustion  and  respiration  that  we  find  accu- 
mulations which  may  have  a  bearing  upon  health.  In  narrow  courts 
and  in  smoky  air  the  free  atmosphere  may  contain  0.7  to  0.8  per  cent. 
In  moving  picture  theaters  the  CO2  may  rise  to  42  and  even  72  parts 
in  10.000.  AYorkshops  may  contain  from  32  to  53  parts  of  carbon 
dioxid  per  10,000,  and  breweries  as  much  as  5  per  cent  and  more.  Its 
significance  varies  with  its  source.  Enormous  volumes  of  carbon  dioxid 
are  constantly  being  poured  into  the  atmosphere.  Manchester  adds 
8,000,000  cubic  meters  of  CO2  a  day  from  the  chimneys  of  industrial 
establishments.  Even  then  the  air  of  the  city  averages  only  0.0385  per 
cent.  CO2,  W'hile  the  air  of  the  country  averages  0.0318  per  cent. — a  very 
slight  difference.  It  is  estimated  that  from  all  sources  500,000,000  tons 
are  discharged  annually  into  the  atmosphere.  The  reason  that  the  car- 
bon dioxid  does  not  accumulate  and  increase  is  that  it  is  constantly  re- 
moved, especially  by  growing  vegetation.  Plants  absorb  enormous 
amounts  under  the  influence  of  light  and  chlorophyl  to  build  carbohy- 
drates. It  has  been  estimated  that  an  acre  of  tree  land  withdraws  in  one 
season  about  4I/2  tons  of  CO2.  Much  of  the  gas  is  also  absorbed  by 
water,  which  at  ordinary  temperatures  takes  up  its  own  volume.  The 
ocean  acts  as  a  great  regulator  to  keep  the  amount  of  CO,  in  the 
air  constant. 

"Average  of  manv  analvses  by  F.  G.  Benedict  is  0.031.  Carnegie  Puhlica- 
Hons  No.  166,  1912. 


874  COMPOSITTOX  OF  THE  ATE 

The  amount  of  carbon  dioxid  produced  by  respiration  varies  with 
the  vitality,  size,  and  activity  of  the  individual.  During  violent  exer- 
cise almost  ten  times  as  much  carbon  dioxid  may  be  discharged  as  dur- 
ing sleep.  On  the  average  a  man  discharges  about  0.6  of  a  cubic  foot 
of  carbon  dioxid  per  hour  and  a  woman  about  0.4  of  a  cubic  foot.  Dur- 
ing ordinary  activity  a  man  produces,  in  round  numbers,  one  cubic  foot 
per  hour.  An  ordinary  gas  jet  burns  about  6  cubic  feet  of  gas  per  hour 
and  produces  about  3  cubic  feet  of  carbon  dioxid.  Therefore,  so  far  as 
CO2  is  concerned,  a  man  vitiates  the  air  less  than  a  gas  jet. 

The  Amount  and  Function  of  CO,  in  Alveolar  Air. — Haldane  and 
Priestley  ^^  have  shown  that  the  regulation  of  breathing  is  largely  de- 
pendent on  the  concentration  of  CO^  in  the  air  cells  of  the  lungs,  that  is, 
the  alveolar  air.  The  concentration  of  COg  in  the  arterial  blood  is  deter- 
mined by  the  proportion  of  this  gas  in  the  air  cells.  The  nerve  cells  in 
the  respiratory  center  are  stimulated  by  the  CO2  in  the  blood.  Fixed 
acids  will  also  stimulate  respiration.  Thus,  beta  oxybutyric  acid  is  the 
cause  of  dyspnea  in  diabetic  acidosis.  In  fact,  the  true  stimulant  of  the 
respiratory  center  is  the  hydrogen  ion  concentration  of  the  blood;  any 
fixed  acid  which  accumulates,  or  any  excess  of  carbon  dioxid,  will  vary 
the  hydrogen  ion  concentration  and  thus  stimulate  the  respiratory 
center.  Ordinarily,  this  stimulation  is  largely  due  to  the  acid  base 
equilibrium  of  the  blood  plasma.  The  carbon  dioxid  is  largely  carried 
by  the  hemoglo])in  which  absorbs  the  carljon  dioxid  as  oxygen  is  given 
off  in  the  tissues,  and  the  process  is  reversed  in  the  lungs. ^-  The  sodium 
bicarbonate  of  the  blood  plasma  acts  as  a  stabilizer  of  the  hydrogen  ion 
concentration  of  the  blood. 

The  COo  which  is  being  constantly  formed  in  the  body  is  carried 
to  the  lungs  by  the  venous  blood.  It  escapes  from  the  blood  into  the 
air  cells  of  the  lumgs  and  its  escape  is  impeded  or  accelerated  accord- 
ing to  the  resistance  it  meets  in  them.  This  resistance  depends  on  the 
proportion  of  COo  in  the  alveolar  air,  since  the  tension  of  this  gas  in 
the  blood  can  only  fall  as  low  as  it  is  on  the  other  side  of  the  membrane 
separating  the  blood  stream  from  the  air  cell.  The  arterial  blood  leaves 
the  lungs  with  essentially  the  same  pressure  of  CO,  that  is  found  in 
the  alveolar  air.  In  this  way  the  alveolar  CO2  regulates  the  CO,  ten- 
sion in  the  blood  and  so  controls  the  respiratory  movements.  This  is 
true  under  normal  conditions,  but  Haldane,  Meakens  and  Priestley  ^^  have 
shown  that  if  the  oxygen  in  the  air  breathed  falls  to  about  11  per  cent., 
then  the  low  percentage  of  oxygen  stimulates  the  respiratory  center  to 
rapid,  shallow  breathing  with  increased  pulmonary  ventilation.     Even 

"  Haldane  and  Priestley :  "The  Regulation  of  the  Lung  Ventilation,"  Jour. 
Physiol.,  1905,  XXXII,  225' 

^Buckmaster:    Journ.  Physiol.,  Vol.  LI,  pp.  105-110;   also  pp.  164-175.        -      ' 
"  Journ.  Physiology,  1918,  LII,  420-432. 


CARBOX  DlOXTl)  875 

at  an  tjxygen  U'lision  of  ix.l  prr  cent.,  l"]llis  found  tlie  respiratory  volume 
increased.^* 

The  bronthin<2;  is  so  regulated  as  to  maintain  the  percentage  of 
CO^  in  the  alvoohir  air  at  a  jiressure  of  about  5  per  cent.  (5.13  to  ().3  per 
cent.)  of  an  atmos])here.  If  the  pressure  falls  helow  this,  in  the  normal 
individual  rcs])iration  is  lessened  or  stopped  until  the  loss  is  regained. 
If  it  goes  above  5  per  cent,  respiration  is  increased  until  the  normal 
is  restored.  ' 

Normally,  the  carbon  dioxid  tension  of  the  alveolar  air  varies  between 
38  and  45  millimeters  of  mercury  or  5.3  to  6.3  per  cent.  If  abnormal 
acids  are  present  in  the  blood,  carbon  dioxid  is  driven  off  from  the 
plasma  and  as  the  tension  falls  in  the  blood  it  falls  likewise  in  the 
alveolar  air.  A  low  carbon  dioxid  tension  in  the  alveolar  air  during  rest 
therefore  indicates  an  accumulation  of  fixed  acids  in  the  blood,  a  so- 
called  ''acidosis.*'  If  the  carbon  dioxid  tension  lies  between  32  and  28 
millimeters  of  mercury,  a  mild  acidosis  is  present  and  below  25  milli- 
meters of  mercury  the  acidosis  is  severe. 

Haldane  and  Douglas  ^^  found  that  from  lying  in  bed  to  walking  five 
miles  per  hour  the  COg  in  the  alveolar  air  was  increased  twelve  times, 
and  that  the  alveolar  ventilation  was  likewise  increased  twelve  times, 
so  that  the  percentage  of  CO,  in  the  alveolar  air  remained  practically 
constant.  Henderson  ^'^  found  no  material  change  in  the  composition 
of  the  alveolar  air  on  going  from  rest  to  strenuous  exercise.  The 
increased  production  of  CO2  was  perfectly  compensated  for  by  increased 
breathing. 

There  can  be  no  doubt  that  there  is  a  wide  range  of  physiologic  re- 
sponse on  the  part  of  the  respiratory  function  to  meet  changing  external 
as  well  as  internal  amounts  of  CO2.  Thus,  when  more  CO,  is  formed 
in  the  body  the  respiration  is  automatically  increased  in  like  proportion, 
and  in  this  way  the  alveolar  CO2  is  kept  at  a  uniform  level  of  about  5 
per  cent.  The  same  thing  happens  when  we  breathe  an  atmosphere  con- 
taining an  excess  of  COg.  The  volume  of  air  breathed  is  then  increased 
in  such  a  degree  as,  if  possible,  to  keep  the  CO,  in  the  alveolar  air 
normal.  Haldane  and  Priestley  ^"  found  that  with  2  per  cent,  of  CO,  in 
the  inspired  air  the  pulmonary  ventilation  is  increased  50  per  cent. ; 
with  3  per  cent,  it  is  increased  about  100  per  cent. ;  with  4  per  cent., 
about  200  per  cent.;  with  5  per  cent.,  about  300  per  cent.;  and  with  6 
per  cent.,  500  per  cent.  With  the  last  the  alveolar  tension  of  CO,  is, 
of  course,  above  the  normal,  and  this  fact  is  signified  by  severe  pant- 

^*Am.  Journ.  of  Plujsiology,  1919,  L,  pp.  267-279. 

"Douglas  and  Haldane:  "The  Dead  Space  of  the  Respiratorv  Passages," 
Jour.  Pln/sioL,  1912.  Abst.  in  Brit.  Med.  Jour..  Xov.  16,  1912.  p.  Ul'l. 

"Henderson  and  Russell:  "A  Simple  Method  for  Determining  the  Carbon 
Dioxide  Content  of  the  Alveolar  Air,"  Am.  Jour.  Physiol.,  1912,  XXIX,  436. 

"Haldane  and  Priestlev:  "The  Regulation  of  the  Lung  Ventilation,"  Jour, 
Physiol,  1905,  XXXII,  225". 


876  COMPOSITIOX  OF  THE  AIR 

ing;  but  up  to  3  per  cent,  in  the  inspired  air  the  increase  of  breathing 
is  scarcely  noticed,  unless  muscular  work  is  done,  when  the  increased 
internal  production  of  CO2  calls  for  a  still  greater  increase  of  the  pul- 
monary ventilation.  The  adjustments  are  automatic  and  go  on  without 
our  consciousness,  unless  an  excessive  increase  of  breathing  is  demanded. 

Since  even  under  the  most  favorable  conditions  we  cannot  avoid 
drawing  back  into  the  lungs  some  of  the  air  that  has  Just  breathed  out, 
not  much  hygienic  importance  can  be  attached  to  the  slight  varia- 
tions in  CO,  content  which  ordinarily  occur  in  the  air  of  rooms.  See 
pages  957  and  963. 

CO2  as  an  Index  of  Vitiation. — For  years  the  amount  of  COg  in  the 

'air  has  been  generally  adopted  as  the  most  convenient  index  of  the  total 

conditions  which  are  usually  prejudicial  to  health  and  comfort.     The 

efficiency  of  ventilation  also  for  years  was  usually  determined  by  an 

estimation  of  COg. 

COo  in  itself  is  not  irritating '  or  poisonous.  Large  volumes  may 
be  taken  in  beverages  or  inhaled  without  noticeable  effects.  Effects  are 
scarcely  felt  on  the  human  system  when  the  CO^  reaches  2  or  3  per  cent. 
The  result  of  a  concentration  of  2  per  cent.  CO,  is  simply  to  cause  an 
automatic  increase  of  50  per  cent,  in  depth  of  breathing,  such  as  occurs 
in  moderate  exercise.  Respirations  increase  with  the  percentage,  in  depth 
only,  until  about  5  per  cent.,  when  there  is  distinct  panting,  and  at  7  ar  8 
per  cent,  the  dyspnea  becomes  distressing;  and  headache,  nausea,  and 
chilliness  may  be  noted.  Observations  made  by  Professor  W.  G.  Ander- 
son in  my  laboratory  show  that  these  symptoms  are  more  acute  when 
the  carbon  dioxid  is  added  to  the  air  rapidly.  Tolerance  or  second  wind 
may  be  obtained  in  atmospheres  containing  even  as  much  as  10  per  cent. 
Animals  soon  die  when  the  percentage  reaches  35  or  45  per  cent,  in  an 
artificial  atmosphere.  Man  soon  becomes  unconscious  and  suffocates  in 
an  atmosphere  containing  30  per  cent,  of  CO,. 

Benedict  and  Milner  ^^  observed  seventeen  subjects  kept  for  varying 
periods  from  two  hours  to  thirteen  days  in  a  small  chamber  with  a 
capacity  of  189  cubic  feet,  in  which  the  air  was  recirculated,  but  con- 
trolled chemically  and  physically.  The  CO,  was  usually  over  8  to  9 
times  normal  (over  35  parts  per  10,000),  often  over  100  parts,  and 
sometimes  240  parts  per  10,000,  and  yet  there  was  no  discomfort  so  long 
as  the  chamber  was  kept  cool. 

Pettenkoffer  in  1858  proposed  10  volumes  of  CO2  in  10,000  volumes 
of  air  as  the  limit  for  inhabited  rooms.  De  Chaumont  (1875)  found 
that  an  unpleasant  odor  becomes  perceptible  in  air  containing  6  volumes 
of  CO,  in  10,000,  and  fixed  this  as  the  limit,  which  for  many  years 
has  been  accepted  by  sanitarians.  It  was  soon  learned,  however,  that 
the  percentage  of  CO,  may  rise  much  higher  before  ill  effects  become 

^^Biill.  ^^o.  175,  U.  S.  Deot.  of  Agriculture,  1907. 


CAKHOX  1)10X11)  877 

perceptible.  Carnelly,  Aiulcrson  and  llaldanc  in  1887  concludod  that 
for  the  very  crowded  cicmciitarv  scliools  a  lower  limit  than  ^'^  voliiiiH's 
was  not  practical,  llaldaiic  and  Otsboriic  in  I'.Mi-j  roconiinon(l<'(l  a  limit 
of  12  volumes  lor  i'actorjos  and  worksho])s  at  tlic  breathin^^  level,  and 
that  Avhen  gas  or  oil  is  used  for  lighting  the  pro{)ortioii  should  not  ex- 
ceed 20  volumes.  The  general  consensus  of  opinion  to-day  is  that  10 
volumes  in  10,000  is  well  upon  the  safe  side,  although,  so  far  as  CO, 
itself  is  concerned,  more  might  be  permitted  without  fear.  Carbon 
dioxid  is  by  no  means  the  most  mischievous  of  the  (onstituents  of 
vitiated  air.  It  is  not  merely  a  waste  product.  It  is  one  of  the  inifjor- 
tant  hormones  of  the  body.  It  helps  to  regulate  the  action  of  the  heart, 
influences  the  tonus  of  blood  vessels,  aiul  stimulates  the  respiratory 
center. 

It  is  certainly  erroneous  and  unscientific  to  rely  upon  determinations 
of  CO2  in  the  air  of  a  room  as  the  sole  measure  of  its  conditions  for 
respiration.  Carbon  dioxid  never  accumulates  sufficiently  in  any  ordi- 
nary room  to  become  in  itself  serious;  further,  the  amount  of  COo 
in  the  air  of  a  room  gives  no  indication  whatever  of  the  moisture, 
the  temperature,  or  the  motion  of  the  air  of  that  room.  While  the 
amount  of  CO.,  then,  gives  us  a  rough  index  of  the  degree  of  vitia- 
tion of  the  air,  it  affords  no  information  concerning  its  physical  con- 
ditions, which  are  of  special  importance. 

The  significance  of  carbon  dioxid  upon  health  is  further  discussed 
on  page  957. 

Methods  of  Determining  Carbon  Dioxid. — For  the  ordinary  purposes 
of  a  sanitary  analysis  it  is  not  necessary  to  make  an  accurate  analysis 
of  the  carbon  dioxid  in  air,  such  as  the  chemical  analyst  or  the  student 
of  metabolism  would  make  in  scientific  research.  As  the  carbon  dioxid 
in  itself  is  not  poisonous  and  is  only  an  imperfect  index  of  other  im- 
purities, and  as  its  significance  varies  with  its  source,  sufficient  informa- 
tion may  be  gleaned  for  sanitary  purposes  from  methods  that  give 
results  relatively  comparable. 

The  most  accurate  method  of  determining  CO2  in  the  air  is  that 
described  by  Petterson,  and  used  in  the  Petterson-Palmquist,  the  Sonden 
or  the  Haldane  apparatus.  Both  the  Petterson-Palmquist  and  the  Hal- 
dane  methods  are  convenient,  practical,  and  sufficiently  accurate  for 
all  ordinary  purposes.  The  method  of  Cohen  and  Appleyard  is  reason- 
ably accurate  and  very  convenient.  The  methods  of  Wolpert  and  Fitz 
give  only  rough  estimates. 

Collection  of  Samples. — The  collection  of  the  samples  of  air  to 
be  analyzed  is  fully  as  important  as  the  actual  test.  The  following 
methods  may  be  used : 

The  water  siphon  method,  which  consists  of  two  bottles  (diameter 
one-third  the  height),  volume  about  one-half  liter,  of  nearly  equal  ca- 


8^8  COMPOSITION  OF  THE  AIR 

paeity,  fitted  with  rubber  stoppers  carrying  small  glass  tubing  connected 
by  several  feet  of  rubber  tubing  with  clamps.  Fill  one  bottle  com- 
pletely with  water,  nearly  free  from  carbon  dioxid. 

The  pair  of  bottles  is  taken  to  the  place  from  which  the  air  is  to 
be  collected.  The  inlet  or  collecting  tube  may  be  long,  so  as  to  reach 
nearly  to  the  ceiling,  or  short ;  if  long,  the  first  siphoning  should  be 
rejected  to  insure  filling  the  inlet  tube  with  the  air  desired.  The  stop- 
pers are  then  exchanged  and  the  sample  taken.  The  air-filled  bottle 
should  be  stoppered  and  taken  to  the  laboratory;  or  the  test  solution 
may  at  once  be  added,  and  the  bottle  stoppered  and  shaken,  noting  min- 
utes and  seconds  in  the  Cohen-Appleyard  method.  One  bottle  of  water 
with  a  small  reserve  will  serve  for  a  number  of  takings  before  absorbing 
a  sufficient  amount  of  COg  materially  to  influence  the  results.  If  the 
water  is  acidulated  it  will  take  up  less  COg. 

The  steam  vacuum  method  may  be  used  as  an  alternative  in  less 
accurate  work.  The  bottles  should  be  of  about  150  c.  c.  capacity,  made 
for  a  ground-glass  stopper,  but  fitted  with  a  rubber  stopper.  These 
are  filled  with  steam  from  water  first  freed  of  CO2  and  air  by  boiling 
for  5  minutes.  The  bottles  are  inverted  and  a  steam  jet  having  suffi- 
cient pressure  to  throw  the  vaporized  steam  at  least  one  foot  is  allowed 
to  fill  the  bottle  for  3  minutes.  Meanwhile  a  thin  coating  of  vaselin 
is  applied  halfway  up  the  sides  of  the  stopper.  This  not  only  makes 
a  tight  joint,  but  facilitates  removing  the  stopper.  As  soon  as  the 
collecting  bottle  is  removed  from  the  steam  jet  the  stopper  is  instantly 
inserted  and  securely  pushed  in  while  the  bottle  is  still  in  the  inverted 
position.  To  test  the  method  for  completeness  of  vacuum  hold  the 
bottle  in  an  inverted  position  under  water  at  70°  F.  and  remove  the 
stopper. 

Samplers  consisting  of  special  glass  tubes  provided  with  a  glass 
stopcock  at  both  ends  may  be  used  to  collect  samples  of  air,  particularly 
for  the  Sonden,  Petterson-Palmquist,  or  Haldane  apparatus.  These 
samplers  have  a  capacity  of  about  100  c.  c. ;  some  of  them  hold  about  200 
c.  c.  They  must  be  clean  and  absolutely  dry.  The  samplers  are  filled 
by  means  of  a  bulb  from  a  Davidson  syringe.  Care  must  be  taken  that 
enough  of  the  air  to  be  examined  is  drawn  through  the  sampler  to  force 
out  all  the  original  air  it  contains.  Samples  may  be  collected  in  dupli- 
cate, and  duplicate  analyses  are  always  advisable. 

The  Ilaldane  Apparatus. — This  apparatus,  shown  in  Fig.  86,  was 
introduced  for  the  determination  of  carbon  dioxid  in  the  case  of  ordi- 
nary rooms,  schools,  factories,  etc.  As  the  apparatus  is  portable,  the 
analysis  can  be  made  directly  on  the  spot  and  the  carrying  to  and  fro 
of  samples  is  thus  avoided,  if  desired.  If  the  buret  is  allowed  to  fill 
while  the  apparatus  is  carried  across  the  room,  a  good  average  sample 
is  obtained.    As  it  takes  some  seconds  for  the  mercury  to  run  down,  this 


CAKBON  DIOXID 


87!J 


nic'tliud  of  taking  the  yainplo  can  (.'asily  be  adopted,  or  a  saini)ler  con- 
taiiiiiii;"  tlie  air  to  be  examined  can  be  connected  directly  by  means  of 
rubber  tubinii;  to  the  gas  buret.  In  this  case  it  is  advisable  to  discard  the 
lirst  lining  of  llie  gas  buret  A  in  order  to  get  rid  of  the  air  in  the  rubber 
tubing  and  coinu'ctioiis.  About  I  minutes  are  required  for  an  analysis. 
The  accuracy  is  about  1  part  in  10,000, 

The  air  buret  A,  which  is  enclosed  in  a  water  jacket  0,  consists  of 


Fig.   86. — Portable  Haldane  Apparatus  for  Small  Percentages  of  Carbon 

DiOXID. 


a  wide,  ungraduated  and  a  very  narrow  graduated  portion.  This  is 
divided  into  100  divisions,  each  of  which  corresponds  to  1  part  in"  10,000. 
The  lowest  division  is  marked  0  and  the  numbering  is  upward  from  this 
point.  Any  difference  between  a  reading  at  or  near  zero  and  a  second 
reading  is  thus  shown  by  the  scale  in  volumes  per  10.000,  there  being 
no  calculations  or  corrections. 

The  absorjition  pipet  I)  is  filled  to  the  mark  E  with  a  "-iO  per  cent, 
solution  of  caustic  potash  through  reservoir  I.  The  control  tube  G  en- 
closed in  the  water  jacket  is  used  to  correct  for  variations  in  the  tempera- 


880  COMPOSITIOX  OF  THE  AIR 

ture  of  the  sample  during  the  analysis.  It  is  connected  with  the  potash 
pipet  D  by  the  tube  H,  which  has  a  mark  K.  ■  The  pressures  under 
which  the  readings  are  made  are  maintained  constant  by  adjusting  the 
levels  of  the  potash  solution  to  the  marks  E  and  K.  To  compensate  for 
variations  of  temperature  of  the  water  jacket  0,  air  is  blown  through 
the  tube  N,  thus  agitating  the  contained  water. 

The  technic  of  an  analysis  is  summarized  as  follows : 

(1)  Open  the  3-way  cock  B  to  the  air  to  be  examined  and  raise 
the  mercury  bulb  C  to  expel  the  air  in  the  buret  A.  Lower  the  mer- 
cury bulb  and  hang  on  the  adjustable  rack  F  so  that  the  sample  is 
drawn  in  and  the  level  of  the  mercury  falls  to  near  the  zero  mark. 

(2)  Open  the  cock  M  to  the  air  for  a  moment  and  then  turn  it 
so  as  to  connect  the  control  tube  with  the  potash  solution  in  the  tube  H. 

(3)  Turn  the  cock  B  so  as  to  connect  the  sample  with  the  potash 
pipet  D. 

(4)  Squeeze  the  rubber  tube-  of  the  potash  reservoir  I  so  as  to 
raise  the  potash  level  about  an  inch  above  the  marks  E  and  K,  and  see 
that  the  level  of  the  potash  alters  sharply  and  about  equally  in  the 
two  tubes. 

(5)  Blow  air  through  the  water  jacket  0. 

(6)  Raise  or  lower  the  potash  reservoir  I  till  the  potash  is  exactly 
at  the  mark  K  in  the  tube  H. 

(7)  Raise  or  lower  the  mercury  bulb  C  by  means  of  the  arrange- 
ment F  till  the  potash  is  exactly  at  the  mark  E. 

(8)  Read  off  the  mercury  level  on  the  scale  of  the  buret  to  0.2 
of  a  division.     (First  reading.) 

(9)  Raise  the  mercury  bulb,  so  as  to  drive  the  air  into  the  potash 
pipet  D;  then  lower  it  a  little  and  raise  it  twice  again  so  as  to  wash 
any  carbonic  acid  in  the  connecting  tubing  into  the  pipet. 

(10)  Return  the  air  to  the  buret  A. 

(11)  Again  blow  air  through  the  water  jacket. 

(12)  Squeeze  the  rubber  tubing  and  adjust  the  two  potash  levels 
at  K  and  E,  as  before,  and  again  read  off  the  mercury  level.  The  first 
reading  subtracted  from  the  second  gives  the  amount  of  COo  in  volumes 
per  10,000. 

(13)  After  the  analysis  open  G  to  the  outside  air  through  cock  M 
and  shut  off  A  and  D  by  turning  cock  B.  This  will  prevent  fouling  of 
the  apparatus  by  the  sucking  up  of  the  potash  solution. 

The  Petterson-Palmquist  Method. — This  is  a  simplified  Sonden 
apparatus  by  which  the  volume  of  CO^  in  the  air  may  be  determined 
directly  in  hundredths  of  a  per  cent,  by  volume.  The  method  is  accu- 
rate to  one  part  in  20,000  of  air,  provided  care  is  taken  with  the  tests. 

The  principle  is  essentially  the  same  as  that  found  in  the  Haldane  or 
the  Sonden  apparatus.    A  measured  amount  of  air  is  collected  in  a  gas 


CARBOX  DIOXIJ) 


881 


buret.  'J'his  volume  of  air  is  then  transferred  to  an  Orsat  tube  con- 
taining a  strong  solution  (30  per  cent.)  of  potash,  which  aI)sorhs  the 
COo.     The  air  is  then   returned   to  (he  gas   hiirct    and   remeasured  for 


Fig.  87. — Petterson-Palmquist  Apparatus. 

loss  in  volume.  Great  care  must,  of  course,  be  exercised  that  the  pres- 
sure and  temperature  are  precisely  the  same  before  and  after  absorp- 
tion. The  gas  buret  A,  Fig.  87,  is  first  filled  with  mercury  by  raising 
the  reservoir  E.    The  sample  to  be  analyzed  is  then  drawn  into  A  by  low- 


882  COMPOSITIOX  OF  THE  AIR 

ering  E.  There  must  always  be  a  drop  of  water  on  the  surface  of  the 
mercury  and  also  in  the  compensating  cylinder  C.  In  this  way  the 
air  sample  is  kept  saturated  with  moisture.  In  reading  the  volumes 
the  meniscus  of  the  mercury  is  each  time  so  adjusted  that  the  pressure 
in  A  is  exactly  the  same  as  the  pressure  of  the  air  in  the  compensating 
cylinder  C.  This  is  accomplished  through  a  differential  manometer 
containing  a  drop  of  colored  liquid  (petroleum,  in  which  azobenzol  is 
dissolved).  This  manometer  is  connected  by  capillary  glass  tubes  on 
one  side  with  A  and  on  the  other  side  with  C.  After  the  gas  pipet  A 
is  filled  with  the  sample  of  air  to  be  tested,  close  the  stopcocks  d,  i,  c, 
and  g  and  adjust  the  level  of  the  mercury  in  A,  so  that  the  drop  of  liquid 
in  the  manometer  stands  at  zero  on  the  scale.  This  adjustment  is  accom- 
plished through  the  set  screw  E.  In  this  way  the  air  in  A  may  always 
be  brought  to  the  same  pressure  as  that  prevailing  in  the  compensator 
C.  Since  the  air  in  both  compensator  and  pipet  is,  from  the  begin- 
ning of  the  experiment,  separated  from  the  external  atmosphere  by  clos- 
ing the  stopcocks  f,  g,  and  c,  variations  in  the  external  atmosphere 
have  no  effect.  The  temperature  is  regulated  by  filling  the  jar  with 
water  and  keeping  it  agitated,  preferably  with  bubbles  of  compressed 
air. 

Each  analysis  consists  of  three  operations : 

(1)  The  air  is  drawn  in  from  the  outside  and  is  measured,  the 
level  of  the  mercury  in  the  graduated  tube  being  brought  to  the  zero 
mark.  The  upper  and  narrower  part  of  the  scale,  where  each  division 
denotes  1/10,000  of  the  volume  of  the  pipet,  is  used  in  analysis  of 
atmospheric  air,  or  the  ordinary  air  of  rooms,  where  the  per  cent,  of 
carbon  dioxid  is  at  the  most  not  higher  than  0.4  per  cent.  In  the  analy- 
sis of  very  impure  air  the  lower  part  of  the  graduated  tube  is  used,  each 
dirision  here  corresponding  to  1/1,000  of  the  whole  volume.  In  meas- 
uring the  volume  of  the  stopcocks  f,  g,  b,  c,  and  d  must  be  closed. 

(2)  The  stopcocks  d  and  b  are  opened,  a  is  closed,  and  the  air 
is  passed  from  A  to  B.  After  one  or  two  minutes  the  carbon  dioxid 
is  absorbed  and  the  air  may  be  brought  back  into  A;  b  is  then  closed 
and  a  is  opened. 

(3)  The  mercury  level  in  A  is  so  adjusted  that  the  index  again 
takes  its  normal  position.  The  decrease  in  volume  is  then  read  off  on 
the  scale. 

Acidulated  water  may  be  used  to  expel  the  air  from  samplers  into 
the  buret  of  the  gas  analysis  apparatus,  if  the  operation  is  quickly 
done.  If  a  refinement  of  accuracy  is  desired  mercury  is  preferable,  for 
even  acidulated  water  will  take  up  some  CO2. 

Method  of  Cohen  and  Apphyard.— This  method  is  based  upon 
the  fact  that,  if  a  dilute  solution  of  lime  water  slightly  colored  with 
phenolphthalein  is  brought  in  contact  with  a  sample  of  air  containing 


CAKBON  DIOXID 


883 


more  than  onoui^li  CO.  lo  coiiiliiiic  with  all  Ihc  liino  present,  the  solu- 
iion  will  yTaduaily  he  decoKtri/A'd.  The  lime  neeessary  to  discharge  the 
eolor  dcpiMids  upon  the  aniounl  of  CO.  ])resent.  The  amount  of  lime 
water  and  tlu>  Noliimc  of  air  heing  constant,  the  rate  of  decoloration 
varies  inversely  with  the  amount  of  CO^. 

Colleet  samples  of  air  in  clean,  clear  glass-stoi)})ered  bottles  of  lialf 
liter  capacity.  The  sample  may  be  collected  by  exhausting  the  air  from 
a  bottle  with  a  pair  of  bellows  or  by  completely  filling  the  bottle  Avitli 
Mater  and  then  emptying  it  at  the  point  where  the  sample  is  to  be  taken, 
liun  in  (luickly  10  c  c  of  the  standard  lime  water  (see  below).  Re- 
place the  stopper;  note  time.  Shake  the  bottle  vigorously  until  the 
pink  color  disappears;  again  note  time,  and  ascertain  the  correspond- 
ing amount  of  COo  from  the  following  table: 


Time  in  Minutes  to  De- 
colorize the  Solution 


1% 
1% 

2 

2% 


COo  per  10,000 


16.0 
13.8 
12.8 
12.0 
11.5 
8.6 
7.7 


Time  in  Minutes  to  De 
colorize  ttie  Solution 

314 : 

4     

414 

5     

51/4 

614 

71/2 


COo  per  10,000 


7.0 
5.3 
5.1 
4.6 
4.4 
4.2 
3.5 


Standard  Lime  Water  for  Testing  COo- — The  solution  used  is 
a  dilute  solution  of  lime  water  colored  with  phenolphthalein.  To  freshly 
slaked  lime  add  twenty  times  its  weight  of  water  in  a  bottle  of  such 
size  that  it  is  not  more  than  two-thirds  full.  Shake  the  mixture  con- 
tinuously for  20  minutes,  and  then  allow  it  to  settle  over  night  or 
until  perfectly  clear.  The  resulting  solution  is  the  stock  lime  solution, 
or  "saturated  lime  water."  If  made  in  the  manner  indicated,  each 
cubic  centimeter  of  it  will  be  very  nearly  equivalent  to  1  milligram  of 
carbon  dioxid. 

If,  however,  it  is  desired  to  know  the  streugih  of  it  more  exactly, 
it  may  be  determined  by  titrating  with  a  standard  acid. 

To  a  liter  of  distilled  water  add  2.5  c,  c.  of  phenolphthalein  (made  by 
dissolving  0.7  gram  of  phenolphthalein  in  50  c.  c.  of  alcohol,  and  adding 
an  equal  volume  of  water).  Stand  the  bottle  of  water  on  a  piece  of 
white  paper  and  add,  drop  by  drop,  saturated  lime  water  till  a  faint  color 
persists  for  a  full  minute.  ,Xow  add  6.3  c.  c.  of  saturated  lime  water, 
quickly  cork  the  bottle,  and  avoid  contact  with  the  CO.  of  the  air. 

For  accuracy  in  testing  air  which  is  high  in  carbon  dioxid,  it  is 
found  advantageous  to  use  a  solution  twice  as  strong  as  the  above.  This 
double  solution  is  prepared  in  precisely  the  same  way,  using  5.0  c.  c.  of 
the  phenolphthalein  solution  and  12.6  c,  c,  of  the  "saturated  lime  water.^' 

While  this  procedure  does  not  give  an  exact  volume  of  solution,  it  is 


884 


COMPOSITION^  OF  THE  ATE 


CCIT 


50- 


believed  to  be  the  best  for  the  jDreparation  of  this  dilute  test  solution, 
since  it  obviates  the  necessity  for  pouring  the  prepared  solution  from 
the  measuring-flask  into  the  bottle  in  which  it 
is  kept;  12. G  c.  c.  of  the  stock  lime  solution  is 
added  rather  than  10  c.  c,  in  order  to  keep  the 
values  obtained  with  the  resulting  solution  more 
nearly  comparable  with  the  older  values  cal- 
culated on  the  supposition  that  10  c.  c.  of 
'^saturated  lime  water"  was  equivalent  to  13.6 
milligrams  of  carbon  dioxid.  (Eichards  and 
Woodman). 

Methods  of  Wolpert  and  Fitz. — These  are 
rough  mctliods  for  determining  carbon  dioxid, 
and  while  not  quite  as  accurate  as  jthe  Cohen 
and  Appleyard  method,  are  useful  because  of 
their  simplicity  and  convenience.  The  Wolpert 
tester  gives  better  results  than  that  of  Fitz. 

The  volume  of  air  that  must  be  brought  into 
contact  with  a  definite  quantity  of  lime  water 
in  order  to  neutralize  all  the  lime  is  taken  as  a 
measure  of  the  COo  in  the  air.  The  quantity 
of  lime  water  and  the  time  of  reaction  remain- 
ing constant,  the  amount  of  CO,  varies  in- 
versely as  the  volume  of  air.  The  apparatus 
consists  of  graduated  shakers  (see  illustration), 
and  a  pipet  for  measuring  10  c.  c.  of  the  standard 
'ime  Avater  solution.     See  page  883. 

In  using  both  the  Wolpert  and  the  Fitz 
apparatus  care  should  be  taken  that  the  finger 
used  to  close  the  end  of  the  tube  is  clean,  since 
on  a  warm  day  the  free  acid  in  the  perspiration 
might  vitiate  the  results.  This  error  may  be 
obviated  by  using  a  rubber  stopper  or  cap. 

The  Wolpert  Air  Tester.- — In  using  this  ap- 
paratus first  remove  the  plunger  and  introduce 
10   c.    c.    of  the   standard   lime    Avater   solution 
(see    page    883)    into    the    graduated    cylinder. 
Immediately  insert  the  plunger  and  press  it  to 
the  surface  of  the  lime  water.     Xext,  withdraw 
the  plunger  to  the   50   c.   c.   mark.      Place  the 
finger  or  rubber  cap  over  the  end  of  the  piston 
and  shake  vigorously  for  30  seconds.     Eemove  finger  or  cap;  press  the 
plunger  again  to  the  surface  of  the  liquid,  Avithdraw  it  to  the  50  c.  c. 
mark,  and  shake,  continuing  this  process  imtil  the  color  is  discharged. 


Fig 


88. — Wolpert  Air 
Tester. 


CAKHON    niOXll) 


885 


Air  In  c.  c.  Used 

COj  per  10,000 

Air  In  c.  c.  Used 

COa  per  10,000 

30. 
36 

2S 
22 
18 
14 
12 
10 

01 

103 

0 

8 

dO 

117 

7 

58. 
60 

138 

165 

82. 

207 

4 

Each  witlulrawal  of  the  phingt-r  admits  ](i  c  c  ol'  air  to  the 
cylinder,  and  from  the  total  volume  of  air  thus  admitted  the  ap- 
proximate amount  of  air  necessary  to  discharge  the  color  is  deter- 
mined. A  more  accurate  estimation  of  the  amount  of  air  neces- 
sary to  decolorize  the  lime  solution  can  be  obtained  by  repeating  the 
process  and  admitting  a  smaller  amount  of  air  to 
the  cylinder  the  last  time  the  plunger  is  Avitli- 
drawn.  From  the  total  amount  of  air  used  in 
the  second  test,  the  amount  of  COg  can  be  de- 
termined from  the  above  table. 

A  mor?  convenient  but  less  accurate  method  of 
using  this  apparatus  is  to  put  2  c.  c.  of  the  lime 
water  into  the  cylinder,  insert  the  plunger  to  the 
line  marked  "•extremely  bad'"'  (4  per  cent.)  and 
shake  for  one  minute.  Then  if  the  color  is  not 
discharged  withdraw  the  piston  a  little  farther 
and  shake  again,  and  so  on  until  the  position  of 
the  plunger,  when  the  color  is  gone,  can  be  de- 
termined. From  this  the  percentage  of  COo  can 
be  read  off  directly  from  the  figures  on  the  left 
of  the  cylinder. 

Fitz  Air  Tester. — This  apparatus  consists  of 
a  tube  closed  at  one  end,  and  graduated  for  a 
distance  of  20  c.  c.  Another  tube  smaller  in  size 
and  open  at  both  ends,  slides  within  the  graduated 
tube  by  means  of  a  rubber  collar.  This  ruljber 
collar  should  be  moistened  in  order  that  the 
inner  tube  may  slide  readily. 

Press  the  inner  tube  down  to  the  bottom  of  the  larger  one  and 
measure  into  the  apparatus  10  c.  c.  of  the  standard  lime  water  solution 
(page  S83).  Withdraw  the  inner  tulje  up  to  the  "tare  mark"  (T)  which 
corresponds  to  the  5  c.  c.  mark.  Tlie  bottom  of  the  inner  tube  serves  as 
the  index.  Xow  quickly  close  the  end  of  the  smaller  tube  with  the 
finger;  hold  the  apparatus  horizontally,  and  shake  it  vigorously  for  30 
seconds. 

The  amount  of  air  that  has  thus  been  brought  in  contact  with  the 


looa 

Fig.   so. — FiTz   Air 
Tester. 


886  COMPOSITION  OF  THE  AIR 

solution  is  30  c.  c.  Eemove  the  finger,  again  press  down  the  small  tube 
to  the  bottom  of  the  larger,  and  draw  it  to  the  20  c.  c,  mark.  Shake  the 
apparatus  again  for  30  seconds.  The  additional  amount  of  air  brought 
in  contact  with  the  solution  is  20  c.  c.  Eepeat  the  shaking,  using  20  c.  c. 
of  fresh  air  each  time  until  the  pink  color  is  discharged.  A  slight 
trace  of  color  may  be  ignored.  The  amount  of  CO,  corresponding  to 
the  total  number  of  c.  c.  of  air  used  will  be  found  in  the  table  on  page 
885. 


CHAPTER   II 
PRESRTTRE,  TE:\rPERATTTRE,  AND  HUMIDITY 

PRESSURE 

Normal  Atmospheric  Pressure. — The  pressure  of  the  atmosphere  at 
sea  level  is  1.")  pouiuls  to  the  square  inch,  or,  as  indicated  in  the  barom- 
eter, it  will  maintain  a  column  of  mercury  30  inches  or  760  millimeters. 
A  man  of  average  size  living  at  sea  level  is  exposed  to  a  total  pressure 
of  about  34,000  pounds — more  than  15  tons.  This  great  pressure  must 
evidently  have  physiological  importance.  All  the  tissues  and  fluids  of 
the  body  are  sulijected  to  this  pressure  and  are  in  equilibrium  with  it. 
The  interchange  of  gases  on  which  life  depends  is  largely  a  phenomenon 
of  atmospheric  pressure.  The  pressure  of  the  air  also  keeps  the  heads 
of  the  bones  in  their  sockets  without  muscular  action,  and  doubtless 
performs  other  functions  less  obvious.  The  small  variations  in  pres- 
sure such  as  occur  day  by  day  at  sea  level  have  no  evident  physiological 
effects. 

Diminished  Atmospheric  Pressure. — A  diminution  in  atmospheric 
pressure  is  equivalent  to  breathing  rarefied  or  diluted  air.  This  is  met 
with  mainly  in  aviation.  The  symptoms  are  due  to  the  low  partial  ten- 
sion of  the  oxygen.  If  oxygen  gas  is  added  to  the  inspired  air  at  low 
barometric  pressures,  no  discomfort  is  experienced.  The  dangers  of 
rarefied  air  are  those  of  oxv'gen  deficiency.  Acidosis  attends  the  severer 
stages.  An  adaptation  response  takes  place  under  these  conditions ;  thus, 
the  acidosis  increases  the  rate  of  breathing;  and  the  number  of  red 
blood  cells  increases,  thus  increasing  the  oxygen  carrying  capacity  of 
the  blood.  The  most  important  physiological  effects  of  diminished  at- 
mospheric pressure  are  due  to  a  diminution  in  the  amount  of  oxygen 
absorbed,  hence  the  breathing  is  deeper  and  the  pulse  rate  quickened. 
As  the  altitude  increases  there  is  a  lowered  tension  of  oxygen  in  the 
alveolar  air  and  a  diminished  tension  of  carbon  dioxid.  Wliile  the  rate 
of  respiration  may  be  variously  influenced  in  different  circumstances, 
the  depth  of  respiration  is  almost  invariably  increased.  This  of  itself 
not  only  facilitates  the  oxygen  supply,  but  also  increases  the  elimination 
of  carbon  dioxid. 

Formerly  a  great  compensatory  increase  in  the  number  of  red  blood 
cells  was  believed  to  take  place  as  a  result  of  prolonged  residence  in  high 

887 


888  PRESSUEE,  TEMPEEATURE,  AND  HUMIDITY 

altitudes.     Tims,  assuming  the  average  number  of  red  blood  cells  per 

cubic  millimeter  at  sea  level  to  be  about  5,000,000,  at  Davos  (elevation 

1,560   meters)    the   number   of   red   blood    cells   averages    5,500,000   to 

6,500,000.     At  Cordilleras  (altitude  4,393  meters)   the  average  number 

of  red  corpuscles  is  8,000,000.     A  similar  change  in  the  blood  has  been 

produced  by  keeping  rabbits  and  guinea-pigs  in  rarefied  air  at  sea  level. 

According  to  Biirker,  only  a  comparatively  small  increase  takes  place, 

amounting  to  4  or  5  per  cent.,  at  altitudes  of  five  or  six  thousand  feet. 

The  same  moderate  results  have  likewise  been  noted  lately  for  much 

higher  altitudes.      Gregg,   Lutz  and    Schneider  ^  recently   showed   that 

where  barometer  pressure  is  rapidly  reduced,  as  in  aviation,  there  is  a 

response  by  increased  hemoglobin  in  the  blood  usually  within  twenty 

minutes. 

At  a  height  of  18,000  feet  the  pressure  of  the  atmosphere  is  only 

half  the  pressure  at  sea  level,  thus : 

Height  of 

Altitude                                            -  Barometer 

0  foot 30  inches 

910  feet 29  " 

1,850    "      28  " 

2,820    "      27  " 

3,820    "      26  " 

4,850    "      25  " 

5,910    "      24  " 

7,010    ''■      23  " 

8,150    "      22 

9,330    "      21 

10,550    "      20  " 

13,170    "      18  " 

16,000    "      10  "■ 

18,000    "      15  " 

"The  highest  dwelling  place  continuously  occupied  is  the  Observa- 
tory El  Mirti,  in  the  Andes,  at  5,880  m.  The  Observatory  at  Arequipa 
is  at  6,100  m.  Thok  djalung  is  a  village  in  the  Himalayas  at  4,980  m. 
In  Peru,  Bolivia,  and  ISTorthern  Chili  a  very  large  part  of  the  population 
live  above  3,000  m.  Potosi,  which  has  numbered  100,000  inhabitants, 
is  at  4,165  m.,  Cerro  de  Pasco  at  4,350  m.,  the  mines  of  Villacota  at 
5,042  m.,  the  railway  from  Callao  to  Oroya  culminates  in  a  tunnel  at 
4,760  m.,  almost  the  height  of  Mont  Blanc.  An  annual  fair  is  held 
at  Gartok,  at  4,598  m.,  in  the  Himalayas,  to  which  thousands  annually 
come.^'  ^ 

It  is  evident  that  man  may  become  adapted  to  breathing  a  rarefied 
air  at  great  heights,  which  would  overcome  persons  if  the  change  were 
made  suddenly  from  sea  level.  Linhard  actually  resided  for  26  days  in 
a  pneumatic  cabinet,  becoming  "acclimated^'  gradually  to  a  reduced 
barometric  pressure  of  450  mm.  at  which  he  lived  for  two  weeks. 

*  Gregg,  H.  W.,  Lutz,  B.  R.,  and  Schneider,  E.  C:     "Compensatory  Eeaction 
to  Low  Oxygen."    Am.  Jour.  Physiol.,  1919,  pp.  302-325. 
''Leonard  Hill:     "Recent  Advances  in  Physiology." 


PKESSIK'K  889 

Mountain  Sulin('.'<s. — The  syniploins  iirodmcd  Ijy  a  inarkod  (liiiiiiui- 
tion  in  atuios|)li('ric  pressure'  vary  with  (•ircuiu??taiices.  Tlic  ctVcct' 
are  increased  by  culd,  active  muscular  exertion,  or  inii)roper  clothing, 
riie  noticeable  syni|)tonis  ai'c  increased  (h'|)th  and  lapidity  of  respira- 
tion and  acceleration  of  the  pulse,  noises  in  the  head  and  dizziness, 
impairniont  of  the  senses  of  sight,  hearing,  and  touchy  dullness  of  the 
intellectual  faculties,  and  a  strong  desire  to  sleep.  Sudden  changes  to 
rarefied  atmosphere  cause  syncoi)e,  weakness,  (lysj)nca,  dizziness,  and 
nausea.  These  threatening  syni])tonis  sometimes  go  by  the  name  of 
mountain  sickness.  Bert  and  Journet  believe  this  condition  is  (]\\c  t(j 
lack  of  oxygen  and  the  sym])toms  may,  in  fact,  be  relieved  by  adding 
oxygen  to  the  air  inspired.  It  is  now  clear  that  it  is  not  the  reduced 
barometer  but  the  reduced  partial  tension  of  the  oxygen  which  causes 
the  symptoms. 

Bert  kept  a  bird  alive  in  oxygenated  air,  even  though  the  pressure 
was  reduced  to  less  than  0.1  of  an  atmosphere.  Kronecker  concludes  that 
mountain  sickness  is  caused  by  a  congestion  of  the  lungs,  impeding  the 
flow  of  blood  through  them.  ]\Iosso  and  his  followers  attribute  the 
physical  disturbances  of  a  reduced  atmospheric  pressure  to  the  fact  that 
the  blood  loses  carbon  dioxid  more  quickly  than  it  loses  oxygen,  and 
attributes  mountain  sickness  to  this  decrease  of  carbon  dioxid  in  the 
blood  (acapnia).  Cohnheim  believes  there  is  a  concentration  of  the 
blood  at  high  altitudes;  in  fact,  insignificant  increases  have  been  found 
by  competent  observers.  The  climate  in  high  altitudes  is  always  dry 
and  evaporation  proceeds  rapidly.  As  a  result  individuals  lose  water 
more  readily  than  at  lower  levels.  If  this  explanation  is  tenable,  an  in- 
crease in  corpuscles  and  hemoglobin  content  are  in  no  wise  the  expres- 
sion of  a  lack  of  oxygen,  but  are  rather  the  outcome  of  the  increased 
evaporation  under  the  altered  conditions  of  climate.  The  increased 
number  of  red  blood  cells  in  the  peripheral  circulation  probably  repre- 
sents an  outpouring  from  blood  forming  tissues. 

Douglas,  Haklane  and  Henderson  '  showed  that  "acclimatization" 
occurred  in  a  few  weeks  on  Pike's  Peak,  and  believed  that  at  least 
three  factors  operated  in  this  adaptation :  The  cells  of  the  alveoli  of 
the  lungs  acquired  the  power  of  exchanging  oxygen  and  CO,  more 
vigorously  for  the  same  gaseous  pressures  tiian  ordinarily;  the  alkalin- 
ity of  the  blood  had  changed  so  as  to  stimulate  the  respiratory  center 
wath  a  less  amount  of  CO. ;  and  the  hemoglobin  had  increased  so  as  to 
supply  the  tissues  more  readily  Avitli  the  needed  oxygen. 

The  limit  at  which  life  may  be  sustained  is  about  2G,000  feet,  at 
which  height  consciousness  is  lost.*     At  this  height  the  barometric  pres- 

^Phil.  Trans,  of  tlie  Roy.  Soc.  of  London.  IflLS.  Ser.  B..  CCIII,   18.>. 
*The  aviators,  Fleming  and  Steyer,  in  June.   1011,  attained  an  elevation  of 
8,910  meters,  but  experienced  grave  symptoms  wliicli  urgently  called  for  the  use 


890         PEESSUKE,  TEMPERATUEE,  AND  HUMIDITY 

sure  of  the  air  is  251  mm.,  which  represents  a  pressure  of  oxygen  of  52, 
which  is  the  equivalent  of  6.8  per  cent,  oxygen  at  sea  level,  P,  Bert  re- 
mained 20  minutes  in  a  pneumatic  chamber  with  a  pressure  of  only  248 
mm,  without  serious  inconvenience. 

Increased  Atmospheric  Pressure. — While  man  is  often  exposed  to 
rarefied  air,  he  is  seldom  subjected  to  increased  pressure  except  under 
artificial  conditions,  such  as  in  diving  bells,  diving  suits,  and  caissons. 
The  increase  in  atmospheric  pressure  in  the  deepest  mines  has  little 
physiological  significance.  Divers  and  workers  in  caissons  are  not  sub- 
jected to  more  than  about  41/2  atmospheres,  and  work  under  such  pres- 
sure for  only  a  few  hours  at  a  time.  When  a  diving  bell  is  lowered  10 
meters  into  the  water  the  air  contained  in  it  is  compressed  to  one-half 
its  original  bulk,  and  the  pressure  of  the  air  is  accordingly  doubled.  Each 
10  meters'  depth  means  an  additional  pressure  of  one  atmosphere.  At 
a  depth  of  30  meters,  about  100  feet,  a  diver  is  exposed  to  a  pressure 
of  4  atmospheres  or  about  60  pounds  per  square  inch.  Bert  exposed 
dogs  to  a  pressure  of  10  atmospheres,  and  then  slowly  released  them 
without  harm. 

The  physiological  effects  of  an  increased  atmospheric  pressure  are 
mainly  due  to  an  increase  in  the  amount  of  atmospheric  gases  (espe- 
cially nitrogen)  which  are  taken  up  by  the  blood,  and  also  an  increase 
in  the  chemical  absorption  of  oxygen  by  the  blood.  The  serious  conse- 
quences usually  result  from  too  rapid  decompression.  The  nitrogen  is 
absorbed  by  the  tissues,  especially  by  fat  and  lipoid  tissues  contained  in 
the  nervous  system.  As  the  pressure  is  released  gas  bubbles  form. 
Hence  corpulent  persons  are  more  liable  to  suffer  than  lean;  those  with 
sluggish  circulation  suffer  most.  Gradual  decompression  gives  a  chance 
for  the  gas  to  escape  from  the  lungs  and  be  expelled  without  the  produc- 
tion of  gas  bubbles. 

Caisson  Disease. — The  effects  produced  by  compressed  air  in  cais- 
sons are:  (1)  those  caused  when  the  men  are  undergoing  pressure,  and 
(2)   during  or  after  decompression. 

The  symptoms  produced  by  an  increase  of  atmospheric  pressure  ^re 
a  slowing  of  the  respiration,  which  is  evidently  compensatory,  but  on 
account  of  compression  of  intestinal  gases  the  respirations  are  deeper; 
the  pulse  is  slower,  and  evaporation  of  water-vapor  hindered.  The  voice 
may  be  altered ;  pains  in  the  ear  are  common,  due  to  pressure  upon  the 
drum,  and  may  be  obviated  by  swallowing  air  and  thus  passing  it  up 
the  eustachian  tube  into  the  middle  ear.  Sometimes  the  ear  drum  rup- 
tures; headache  and  dizziness  may  also  occur.  During  compression  the 
blood  keeps  absorbing  the  gases  of  the  air  until  the  tension  of  the  gases 

of  oxygen  inlialations.  With  the  aid  of  oxygen  aviators  have  flown  above  30,000 
feet — nearly  six  miles.  Major  R.  W.  Schroeder  in  1918  reached  an  altitude 
of  36,020  feet. 


^roVK^IF.XTl^  OF  TTIK  ATMOSPTTFrJK  fiOl 

in  the  blood  Irtoiucs  equal  to  that  in  the  compressed  air.  As  soon 
as  tliis  equihl)riiim  has  been  attained  relief  from  immediate  troubles 
is  secured. 

It  is  during  and  after  decompression  that  the  greatest  danger  to 
health  and  even  risk  of  life  occur.  The  most  frequent  .symptom  is 
excruciating  pains  in  the  muscles  and  joints,  called  by  the  workmen 
''bends."  These  pains  may  continue  for  a  few  hours  or  for  two  or 
three  days.  Occasionally  there  is  bleeding  at  the  nose;  al.<o  severe  aljdom- 
inal  pain,  and  vomiting,  nausea,  vertigo,  dyspnea,  and  unconsciousness. 
Death  may  result  from  internal  hemorrhage,  or  paralysis  may  ensue — 
the  so-called  diver's  palsy. 

The  effects  of  increased  atmospheric  pressure  and  too  rapid  decom- 
pression were  carefully  studied  by  I'aul  Bert  in  1^"'^.  wlio  showed  that 
the  lesions  are  caused  by  the  escape  of  gases  of  the  atmosphere  which 
have  been  taken  up  in  excessive  amounts,  and  are  released  in  the  blood 
and  tissues  when  the  pressure  is  diminished.  The  blood  vessels  may 
contain  gas  emboli,  which  may  lodge  in  vital  parts  and  cause  sudden 
death,  or  the  delicate  capillaries  may  break,  leading  to  hemorrhages  with 
resulting  paralysis.  Air  emboli  may  be  distressing  or  dangerous  if 
they  occur  in  the  labyrinth  of  the  ear,  in  the  spinal  cord,  in  the  brain, 
or  in  the  heart  or  other  vital  parts. 

The  prevention  of  caisson  disease  consists  in  gradual  decompres- 
sion. Sometimes  the  symptoms  come  on  several  hours  after  the  work- 
man has  left  the  caisson.  As  soon  as  symptoms  come  on  the  workman 
should  at  once  be  hurried  back  into  the  compression  chamber  until 
equilibrium  between  the  internal  and  external  pressures  is  restored. 
He  may  then  be  allowed  to  pass  through  the  decompression  chambers, 
but  very  gradually.  A  medical  air-lock  should  be  provided  at  the 
works,  well  heated,  and  furnished  with  bunks  and  emergency  supplies. 

Barometers. — The  pressure  of  the  air  is  measured  by  means  of 
barometers,  the  principles  of  construction  and  use  of  which  are  so  well 
known  that  they  do  not  require  special  description. 


MOVEMENTS  OF  THE  ATMOSPHERE 

Moving  air  is  necessary  for  the  maintenance  of  health  and  is  a 
prime  requisite  of  good  ventilation.  The  motion  of  the  air  serves  the 
twofold  purpose  of  bringing  us  a  fresh  supply  and  taking  away  the 
sewage-polluted  air  from  our  immediate  vicinity.  Moving  air  also  favors 
evaporation  and  helps  to  prevent  heat  stagnation  by  keeping  the  tem- 
perature within  normal  limits.  Paul,  Heymann,  and  Erclentz,  in 
Fliigge's  laboratory,  and  also  Leonard  Hill  in  England,  emphasized  the 
importance  of  moving  air  in  assisting  the  heat  regulation  of  our  body. 


892  PRESSURE,  TEMPERATURE,  AND  HUMIDITY 

They  believe  that  this  is  a  much  more  important  function  of  moving  air 
than  simply  the  bringing  of  fresh  air  or  the  carrying  away  of  the  prod- 
ucts of  respiration.  In  still  air  the  body  soon  becomes  surrounded  by  a 
warm,  moist  aerial  envelope  which  causes  an  overheating  of  the  surface 
of  the  body  and  results  in  the  familiar  symptoms  of  "crowd  poisoning." 
In  a  still  atmosphere  we  are  soon  surrounded  by  a  blanket  of  stagnant 
and  impure  air,  whether  indoors  or  outdoors. 

Much  of  the  benefit  of  mountain,  seaside,  and  other  health  resorts  is 
attributable  to  the  breezes  that  blow  almost  continuously  at  such  places. 
The  health  of  large  cities  located  upon  the  seacoast  or  the  shores  of 
great  lakes  is  favored  by  the  quantities  of  moving  air  with  which  they 
are  frequently  flushed.  A  healthful  climate  is  always  a  breezy  climate — 
within  reasonable  limits.  Much  of  the  benefit  of  driving,  of  fanning,  and 
of  rocking-chairs  is  due  to  the  motion  of  the  air  thus  engendered. 

If  the  air  in  a  poorly  ventilated  room  can  be  kept  in  motion,  say 
with  an  electric  fan,  many  of  the  ill  efl'ects  of  a  vitiated  atmosphere  are 
avoided,  for  the  products  of  respiration  are  diluted,  and  evaporation  and 
heat  interchange  are  favored.  Thus,  Leonard  Hill  placed  eight  stu- 
dents in  a  small  sealed  chamber  which  held  about  three  cubic  meters. 
He  states  that  "at  the  end  of  half  an  hour  they  had  ceased  laughing 
and  joking  and  their  faces  were  congested.  The  carbon  dioxid  had  gone 
up  to  4  or  5  per  cent.  Three  electric  fans  were  then  turned  on,  which 
merely  whirled  the  air  about  just  as  it  was.  The  effect  was  like  magic; 
the  students  at  once  felt  perfectly  comfortable,  but  immediately  the 
fans  were  stopped  they  again  felt  as  bad  as  before."  The  relation  of 
moving  air  to  temperature  and  moisture,  with  reference  to  ventilation, 
is  further  discussed  on  page  960. 

In  nature  the  atmosphere  is  kept  in  almost  constant  motion  as  a 
result  of  differences  in  temperature.  Thus,  the  hotter  air  in  the  tropics 
rises  and  divides  into  two  currents,  which  flow  toward  the  north  and 
south,  while  heavier,  colder  air  rushes  along  a  lower  level  from  the 
north  and  south  to  take  the  place  of  the  lighter  currents.  The  cold 
currents  from  the  poles  are  known  as  the  trade  winds,  and  the  upper, 
warmer  currents  to  the  poles  as  the  antitrades.  The  upper  currents  to 
the  poles  run  northwest  and  southwest;  while  the  lower  currents  from 
the  poles  run  northeast  and  southeast. 

The  chief  cause  of  periodic  winds,  such  as  daily  sea  breezes  and 
monsoons,  is  the  difference  in  the  heating  of  the  air  above  land  and 
above  sea.  On  a  small  scale  the  same  principle  is  seen  at  play  in 
theaters,  churches,  cathedrals,  and  public  buildings.  The  great  mass  of 
people  crowded  together  heats  the  air  about  them  and  it  ascends;  cool 
air  rushes  in  from  the  aisles  to  take  its  place,  hence  the  almost  unavoid- 
able drafts  in  such  places. 

The  velocity  of  air  currents  is  customarily  measured  by  means  of 


TEMPKHATURE  OF  TUK  AIR  89:? 

recording  aiu'iiioiuetcrs.  These  iiistruineiits  recjuire  a  ('onsi{Ieral)Ie  veloe- 
ity  of  air  and  should  never  he  used  without  a  carefully  prepared  table 
of  corrections  wher(M)y  their  readings  may  bo  adjusted. 

It  often  hiM(uncs  (h'sii-ahl(>  in  sanitary  iuNcsli^rations,  particularly 
in  studies  of  ventilation,  to  determine  the  strength  and  direction  of 
currents  of  air  whicli  are  too  delicate  to  ho  m(>asurcd  hy  means  of 
anemometers.  Liglit'T  candles  -will  show  the  direction  of  slight  air 
currents,  the  flame  being  deflected  in  the  direction  in  Mhich  tlie  cur- 
rent is  moving.  ^lore  delicate  than  this  is  the  method  of  noting  the 
course  taken  by  smoke  from  a  joss-stick,  cigarette,  or  cigar. "^ 

When  a  current  of  air  at  the  temperature  of  55°  to  60°  F.  moves  at 
a  rate  of  one  mile  per  hour,  there  is  no  perceptible  draft.  'IMie  rate  of 
movement  in  relation  to  our  perception  is  as  follows : 

Air  moving  at  1.5  feet  per  second— 1.0  mile  an  hour — imperi'eptible. 
Air  moving  at  2.5  feet  per  second — 1.7  miles  an  hour — barely  perceptible. 
Air  moving  at  3.0  feet  per  second — 2.0  miles  an  hour — perceptible. 
Air  moving  at  3.5  feet  per  second — 2.3  miles  an  hour — draft. 

The  movement  of  warm  air  is  less  perceptible  than  the  movement 
of  cool  air.® 

TEMPERATURE  OF  THE  AIR 

The  temperature  of  the  air  depends  mainly  upon  solar  and  ter- 
restrial radiation.  The  air  absorbs  vast  quantities  of  heat  from  the 
sun,  and  as  the  heat  of  the  earth  is  radiated  into  space  a  certain  amount 
is  again  absorbed  by  the  atmosphere.  Accordingly,  the  air  both  keeps 
the  heat  out  and  keeps  it  in.  It  makes  the  days  cooler  and  the  nights 
warmer.  "It  is  a  parasol  at  noon  and  a  blanket  at  night."  Except  for 
it  there  would  be  much  more  violent  changes  in  temperature  (Macfie). 

The  power  of  the  air  to  absorb  heat  and  to  store  heat  depends 
largely  on  its  humidity;  that  is.  on  the  amount  of  water  vapor  it  con- 
tains, for  water  vapor  is  opaque  to  heat  rays.  The  water  vapor  is  also 
a  great  reservoir  of  latent  heat.  When  water  evaporates  a  tremendous 
amount  of  latent  heat  is  carried  up  into  the  atmosphere  with  it  and 
again  becomes  actual  heat  when  the  vapor  condenses.  The  quantity 
of  heat  thus  stored  up  in  water  vapor  is  almost  incredibly  great.    . 

Air  expands  1^  of  its  volume  for  each  degree  rise  of  temperature; 
air  at  32°  F.  and  30  inches  barometric  pressure  is  usually  taken  for 
unit  of  volume.  A  cubic  foot  of  dry  air  at  32°  F.  and  30  inches  barom- 
eter weighs  566.86  grains;  at  any  other  temperature,  therefore,  its 
weight  can  be  ascertained  by  dividing  by  its  increased  volume. 

^  For  a  further  discussion  of  this  subject  see  "Air  Currents  and  the  Laws 
of  Ventilation,"  by  W.  N.  Shaw. 
'  For  Drafts  see  page  248. 


894         PRESSUEE,  TEMPEEATUEE,  AXD  HUMIDITY 

The  temperature  of  the  air  has  a  very  important  bearing  upon 
health.  Man  has  an  almost  incredible  power  of  adapting  himself  to 
wide  variations  of  temperature.  Workers  in  foundries  have  sometimes 
to  endure  a  heat  of  250°  F.  and  even  higher  for  short  periods  of  time. 
Temperatures  of  — 75°  F.  are  met  with  in  polar  expeditions.  This  is 
a  range  of  at  least  325°  F.  The  reason  that  man,  as  well  as  other 
animals,  is  able  to  maintain  a  constant  body  temperature  when  exposed 
to  such  great  variations  of  atmospheric  temperature,  is  due  not  only 
to  the  physiological  mechanism  which  regulates  heat  production  and 
elimination,  but  to  the  layers  of  air  immediately  in  contact  with  the 
skin.  We  wear  clothes  to  protect  ourselves  from  external  heat  or  cold, 
but  still  more  do  we  wear  air  for  that  purpose.  That  is  why  very  high 
temperatures  are  better  borne  Avhen  the  air  is  in  motion,  which  facili- 
tates evaporation,  than  when  the  air  is  still,  Avhile  extremes  of  cold 
are  better  borne  when  the  air  is  still,  for  then  we  become  clothed  in  a 
warm  blanket  of  air.  The  effect  'of  heat  upon  health,  however,  cannot 
be  considered  alone,  for  it  dejDends  on  the  humidity  as  well  as  on  the 
movement  of  the  air.  Extremes  of  heat  and  cold  are  much  more  trying 
when  the  air  is  humid  than  when  the  air  is  dry. 

The  direct  action  of  heat  alone  as  a  cause  of  infant  mortality  has  been 
greatly  underestimated.  The  harmful  effects  of  heat  must  not  be  meas- 
ured so  much  by  the  maximum  or  even  the  mean  temperatures  of  the  out- 
side air,  but  by  the  indoor  temperatures.  Indoor  temperatures  may 
continue  high  in  spite  of  remissions  in  the  temperature  of  the  external 
air.  The  lethal  effects  of  heat  upon  infants,  and  adults,  too,  are  in- 
creased by  the  still,  moist  air  found  in  overcrowded,  narrow  streets,  and 
poor  ventilation  of  houses. 

Exposure  of  the  body  to  dry,  cold  air  has  an  effect  similar  to  a  cold 
bath,  that  is,  there  is  an  increased  loss  of  bodily  heat,  followed  by  a 
demand  for  more.  This  demand  is  met  by  increased  oxidation  of  tissue, 
metabolic  processes  become  more  active,  and  there  is  improvement  in 
nutrition.  It  stimulates  the  chemical  mechanism  of  the  body  for  the 
regulation  of  bodily  heat.    In  this  way  cold  acts  as  a  stimulant  and  tonic. 

It  is  of  first  importance  that  the  arrangements  for  heating  rooms, 
offices,  schools,  etc.,  should  be  so  regulated  that  the  temperature  never 
exceeds  21°  C.  (70°  F.)  ;  especially  should  this  control  be  exercised  in 
public  rooms,  such  as  schools,  etc.  As  a  rule,  the  temperature  of  heated 
rooms  should  be  17°  to  20°  C.  (62.6°  to  68.2°  F.)  or  under.  Periodic 
variations  of  temperature  are  as  desirable  inside  of  buildings  as  in  the 
outside  temperature.  The  temperature  of  the  air  influences  the  tempera- 
ture of  the  body,  and  also  the  general  status  of  the  vasomotor  mechan- 
ism. Experiments  clearly  indicate  that  in  the  daily  life  of  the  school 
and  factory  the  overheating  of  air  seriously  affects  both  health  and 
efficiency.     The  atmospheric  temperature  also  has  a   direct  effect  on 


TEMPERATURE  OF  THE  AIR  895 

diseases  of  the  resjjiratorv  trad.  Hill  and  Muecke/  in  England,  and 
the  Xew  York  State  Commission  on  Ventilation  ^  have  shown  that  in 
going  from  a  hot  room  to  a  eold  room,  the  memhranes  of  the  nose 
became  paler  and  less  moist,  while  the  inferior  turbinates  contract. 
Such  ail  action  may  in  part  account  for  the  well  known  seasojial  prev- 
alence of  infections  of  the  respiratory  tract  in  the  winter  weather. 

The  effect  of  temperature  upon  health  is  so  closely  interwoven  with 
humidity  that  this  relationship  is  discussed  on  page  904. 

Methods  of  Recording  Temperature. — Mercurial  or  bimetallic  iher- 
mometers  are  best  suited  to  take  the  temperature  of  the  air.  The  most 
accurate  mercurial  thermometers  for  this  purpose  have  an  elongated  bulb 
of  mercury  at  one  end  and  a  ring  at  the  other,  through  which  a  cord 
can  be  tied ;  the  scale  should  be  etched  upon  the  glass.  A  good  ther- 
mometer of  this  type  generally  is  accurate  to  about  one-half  to  one-fifth 
of  a  degree.  .  Thermometers  placed  upon  a  backing  of  metal,  card,  or 
wood,  with  the  scale  painted  upon  the  backing,  are  more  ornamental 
than  accurate.  They  usually  possess  a  decided  lag  and  are,  therefore, 
not  trustworthy.  Thermometers  should  be  suspended  freely  in  the 
atmosphere  or  at  least  placed  in  a  current  of  air  sufficient  to  insure  good 
ventilation  about  the  mercury  column. 

Eegistering  thermometers  are  of  two  principal  types:  those  which 
record  maximum  and  minimum  temperatures,  and  those  which  make 
a  continuous  record  of  the  changes  of  temperature  that  occur. 

The  maximum  and  minimum  temperatures  furnish  but  limited  in- 
formation, and,  as  such  self-recording  thermometers  are  almost  invari- 
ably mounted  upon  a  backing,  they  consequently  have  a  considerable 
lag.  They  are  only  dependable  where  fluctuations  in  temperature  are 
not  rapid.  Under  these  circumstances  they  may  be  used  to  record 
the  highest  and  lowest  temperatures. 

For  an  intelligent  understanding  of  the  sanitary  condition  of  any 
room  or  inclosed  space  neither  single  determinations  nor  maximum  and 
minimum  records  are  sufflcient.  Recording  thermometers  should  be 
placed  at  various  selected  points  and  records  should  be  obtained  cov- 
ering a  period  of  several  days.  The  best  type  of  recording  thermom- 
eters depend  upon  the  movements  of  bimetallic  bars,  so  arranged  that 
as  they  contract  and  expand  they  cause  a  penpoint  to  bear  upon  a  mov- 
ing paper  scale,  and  so  leave  an  ink  trace.  The  clockwork  is  gen- 
erally wound  up  for  a  week,  for  which  period  the  paper  scale  is  also 
adapted. 

The  temperature  of  the  wet  bulb  thermometer  should  always  be  taken 

'Lancet,  1913,  CLXXXIV.  1291. 

*Tr.  Am.  Climatol.  and  Clin.  Assn.,  1915;  also  Josephine  Baker.  Am.  Joiim. 
Public  Health,  1918,  YIII,  19;  also  Mudd,  S.,  and  Grant,  S.  B.,  Jour.  Med.  Re- 
search, XL,  1,  May,  1919,  p.  53. 


896         PRESSUEE,  TEMPERATURE,  AND  HUMIDITY 

to  determine  the  drying  and  cooling  (Psychrometer  and  Kata-ther- 
mometer).  Methods  of  recording  temperatures  Avith  the  Kata-ther- 
mometer,  see  page  907. 

HUMIDITY 

Aqueous  Vapor. — Water  in  its  gaseous  state  is  always  present  in  the 
atmosphere.  Water  vapor  is  the  most  variable  of  the  normal  constitu- 
ents of  air,  and  also  one  of  the  most  important,  on  account  of  its  influ- 
ence upon  health.  It  is  usual  to  consider  water  vapor  apart  from  the 
other  gases  of  the  atmosphere,  although  it  is  just  as  much  a  gas  as 
oxygen  or  nitrogen,  and  conforms  to  the  general  laws  that  govern  the 
behavior  of  gases.  Unlike  other  gases  present  in  the  air,  water  vapor 
condenses  at  comparatively  low  temperatures.  As  water  vapor  weighs 
only  about  three-fifths  as  much  as  air,  dry  air  is  heavier  than  moist 
air  under  equal  conditions  of  temperature,  pressure,  etc.  It  is  cus- 
tomary to  speak  of  air  "holding"  water  vapor.  As  a  matter  of  fact, 
the  air  has  nothing  to  do  with  it,  for  it  should  always  be  clearly  ob- 
served that  the  presence  of  water  vapor  in  any  given  space  is  inde- 
pendent of  the  presence  or  absence  of  air  in  the  same  space.  The 
amount  of  aqueous  vapor  which  a  space  contains  depends  entirely  upon 
the  temperature  and  not  upon  the  presence  of  the  pressure  ^  of  the  air. 
At  32°  F.,  for  instance,  the  air  can  "hold"  1/160  of  its  weight  of 
water  vapor,  at  59°  F.  1/80  of  its  weight,  at  86°  F.  1/40  of  its  weight. 
Roughly,  every  27°  F.  increase  of  temperature  doubles  the  amount  of 
water  vapor  the  air  can  hold  in  proportion  to  its  weight.  In  this  way 
the  heat  of  the  atmosphere  is  self-protective,  for  it  loads  the  air  with 
water  vapor,  which  in  turn  absorbs  much  of  the  heat.  The  latent  heat 
is  again  given  off  on  condensation.  The  actual  amount  of  water  vapor 
which  the  air  can  hold  at  difi'erent  temperatures  is  shown  in  the  follow- 
ing table : 

A  cubic  foot  of  air  can  hold  at 

10°  r 1.1  grains 

20°  "    1.5       " 

30°  "    2.1       " 

40°  "    3.0       " 

50°  " 4.2       " 

60°  "    5.8       " 

70°  "    7.9       " 

80°  "    10.0      " 

90°  "    14.3       " 

100°  "    19.1       " 

'  A  high  barometer  retards  evaporation,  while  a  low  atmospheric  pressure 
accelerates  it.  All  volatile  liquids  evaporate  instantly  in  a  vacuum.  The  rate 
of  evaporation  varies  with  temperature  and  pressure,  but  a  given  space  will  ulti- 
mately hold  the  same  amount  of  gas  independent  of  the  presence  and  pressure 
of  other  gases. 


HUMIDITY  897 

As  the  temperature  rises  iu  arithmetical  progression  the  power  to 

retain  vai)or  increases  with   the  rapidity  of  a  geometric  series  having 
a  ratio  of  two. 


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Fig.    90. — Diagram    Showing   Absolute    Humidity   in    Grains    at   Different 

Temperatures. 


The  amount  of  water  vapor  iu  the  air  may  be  expressed  either  by : 
(1)  its  vapor  tension.  The  tension  of  the  water  vapor  in  the  air  is 
expressed  in  inches  or  millimeters  of  mercury.  If  a  drop  of  water  is 
placed  in  a  vacuum,  say  in  a  barometer  tube,  some  of  the  water  vaporizes 


898         PEESSUEE,  TEMPEEATUEE,  AND  HUMIDITY 

and  the  mercury  is  depressed,  owing  to  the  tension  of  the  water  vapor. 
The  amount  that  evaporates,  as  well  as  the  tension,  depends  upon  the 
temperature.  (2)  Its  weight  per  unit  volume  of  air,  i.  e.,  the  absolute 
humidity;  and  (3)  the  ratio  of  the  amount  of  water  vapor  in  the  atmos- 
phere to  the  amount  it  could  hold  at  the  temperature  in  question  if 
saturated ;  that  is,  the  relative  humidity.  Complete  saturation  of  the  air 
with  moisture  is  stated  at  100,  and  lesser  amounts  by  percentages. 
(4)  The  amount  of  water  vapor  in  the  air  may  also  be  found  from  its 
dew-point.  The  dew-point  for  any  temperature  and  humidity  is  the  tem- 
perature to  which  the  air  may  be  cooled  when  precipitation  takes  place. 

The  vapor  tension  or  the  absolute  humidity  indicates  how  much 
water  vapor  the  air  contains,  while  the  relative  humidity  is  an  ex- 
pression of  how  much  vapor  it  might  contain.  The  amount  of  water 
vapor  which  air  can  hold  when  saturated  at  different  temperatures  has 
been  calculated  and  recorded  in  Glaisher^s  hygrometric  tables.^"  It  is, 
therefore,  very  easy,  by  referring -to  these  or  to  the  tables  in  the  U.  S. 
Weather  Bureau — Bulletin  No.  235 — to  calculate  tha  relative  humid- 
ity if  we  know  the  actual  humidity  or  the  dew-point  or  vice  versa. 

The  amount  of  moisture  which  out-of-door  air  ordinarily  contains 
varies  from  about  30  per  cent,  or  less  to  saturation. 

In  meteorological  tables,  giving  climatic  particulars  of  any  town  or 
locality,  the  relative  humidity  is  usually  stated;  but  it  should  be  noticed 
that  the  relative  humidity  bears  no  constant  relationship  to  the  abso- 
lute humidity.  As  the  relative  humidity  varies  greatly  throughout 
the  day,  and  as  the  readings  are  not  always  taken  at  the  same  time  of 
day  in  different  localities,  it  at  once  becomes  evident  that  comparisons 
are  not  reliable.  In  fact,  a  moist  or  dry  climate  cannot  be  predicted 
from  the  relative  humidity.  Thus,  the  mean  relative  humidity  of 
Davos  is  as  high  as  79  per  cent.,  whereas  it  is  generally  known  that  the. 
climate  at  Davos  is  dry.  On  the  other  hand,  in  Egypt  the  average  rela- 
tive humidity  is  very  low,  although  this  country  is  known  to  have 
a  moist  climate.  This  is  for  the  reason  that  the  humidity  readings 
in  Egypt  are  taken  from  10  A.  M.  to  6  P.  M.,  and  vary  from  30.5  per 
cent,  at  Assouan  to  51.7  per  cent,  at  Menahouse.  As  a  matter  of  fact, 
the  relative  humidity  in  Egypt  decreases  from  100  per  cent,  at  dawn 
to  32  per  cent,  at  noon,  and  may  be  quickly  altered  to  the  extent  of  50 
per  cent,  by  a  warm  wind.  The  humidity,  therefore,  through  the  hot, 
sunny  daytime  is  not  a  measure  of  the  climate,  so  far  as  moisture  and 
dryness  are  concerned. 

In  England  the  relative  humidity  averages  75  per  cent.  In  Cali- 
fornia it  drops  from  100  per  cent,  at  dawn  to  22  per  cent,  at  noon.     A 

*"  The  standard  hygrometrical  tables  in  use  the  world  over  are  those  pre- 
pared by  Mr.  James  Glaisher,  F.  E.  S.,  of  the  Eoyal  Observatory,  Greenwich, 
England. 


HUMIDITY 


899 


hot  wind,  by  incrca.'^iii^-  tlic  caiiaiity  of  the  air  for  moisture,  may  also 
lower  the  relative  humidity  very  quickly.  Tiius,  the  Fohn  wind  when  it 
reaches  the  IJiviera  lowers  the  relati\e  humidity  50  to  GO  per  cent,  in 
an  hour  or  twt).  The  mean  reialiNc  liuinidity  of  Denver  for  the  year 
is  only  42  per  cent.,  at  San  Diego,  on  the  coast,  72.9,  at  Los  Angeles, 
a  few  miles  inland,  6G.6.  In  the  heart  of  the  Libyan  desert  the  rela- 
tive humidity  may  be  as  low  as  9  per  cent.  At  the  seaside  daily  varia- 
tions in  humidity  are  less  than  inland  (Macfie).  The  air  in  forests  is 
10  or  20  per  cent,  more  humid  than  air  in  the  open.  There  may  be  a 
very  great  difference  in  the  relative  humidity  of  outside  cool  air  and  of 
air  in  a  closed  heated  room,  in  that  the  latter  may  be  very  much  drier. 
So  far  as  the  effect  of  humidity  upon  health  is  concerned  Dr.  Hug- 
gard  well  states :  "The  really  essential  point  is  not  the  amount  of 
moisture,  relative  or  absolute,  that  is  present,  but  the  amount  that  can 
still  be  taken  up.  This  varies  enormously  with  the  same  degree  of 
relative  humidity  at  different  temperatures,  as  the  following  table  from 
Eenk  will  show : 

Amount  of  vapor  that  cam,  still  be  taken  up  at  different  temperatures  and  the 

same  relative  humidity 


Temperature 

Relative  Humidity 

Absolute  Humidity 
Grams  per  Cubic  Meter 

Grams  of  Vapor  That 
Can  Still  be  Taken  Up 

-20°   C 

Per  Cent. 
60 
60 
60 
60 
60 
60 

0.638 
1.380 
2.924 
5.623 
10.298 
18.083 

0.426 

-10°   C 

0.920 

0°   C 

1.950 

10°  C 

3.749 

20°  C 

6.866 

30°  C 

12.056 

We  see  by  this  table  that  the  same  expression,  60  per  cent,  relative 
humidity,  might  be  applied  to  air  capable  of  taking  up  0.426  gram  or 
12.056  grams  of  vapor,  and  thus  the  expression  as  a  measure  of  the 
drying  capacity  of  the  air  is  obviously  misleading. 

Dr.  Huggard  gives  a  second  very  instructive  table,  the  obverse  of 
the  above : 


Relative  Humidity 

Vapor  :    Grams  per  Cubic  Meter 

Temperature 

Present 

Capable  of  Still"  Being 
Taken  Up 

3°  C 

Per  Cent. 
0 
36 
53 
65 
73 
80 

0 

3.4 

6.8 

11.2 

16.9 

24.1 

6 

10°  C 

6 

15°  C 

6 

20°  C 

6 

25°  C 

6 

30°  C 

6 

900         PEESSUEE,  TEMPEEATUEE,  AND  HUMIDITY 

"We  see  from  this  second  table  that  air  with  relative  humidities  of 
0,  36,  53,  65,  73,  and  80  per  cent.,  and  containing  quantities  of  water 
vapor  varying  between  0  and  24.1  grams  per  cubic  meter,  are  all  capable 
of  further  taking  up  exactly  the  same  amount  of  vapor.  Again  the 
expression  of  relative  humidity  is  misleading. 

When  the  relative  humidity  reaches  80  to  85  per  cent.,  moisture  con- 
denses and  begins  to  show  upon  objects  in  rooms.  This  influences  natural 
ventilation  through  porous  building  materials. 

There  may  be  a  very  marked  difference  between  the  humidity  of 
indoor  and  outdoor  air,  owing  in  part  to  the  condensation  of  moisture, 
especially  in  winter,  upon  the  cold  walls  and  windows. 

The  difference  between  external  and  internal  humidities  depends 
largely  upon  the  temperature  of  the  surfaces  in  the  room.  These  sur- 
faces, though  apparently  dry,  may,  in  fact,  hold  moisture  in  large 
quantities;  the  walls  and  ceilings  may  contain  more  water  than  all  the 
air  in  the  room.  Ordinarily  there  is  a  continual  exchange  of  moisture 
between  the  air  and  the  room  surfaces.  In  this  way  the  walls  serve 
as  a  compensating  reservoir  to  help  maintain  the  humidity  of  the  air 
approximately  constant.  Cold  walls,  cold  windows,  and  cold  surfaces 
generally  condense  the  moisture  from  the  air  so  rapidly  that  great  diffi- 
culty is  experienced  in  raising  the  relative  humidity  of  the  air  of  a  room 
under  these  circumstances. 

The  humidity  in  the  air  is  influenced  by  altitude.  The  higher  we 
go  the  colder  and  rarer  the  air  becomes,  therefore,  it  contains  less 
moisture.  Its  absolute  humidity,  therefore,  decreases.  Half  of  the 
total  water  vapor  of  the  atmosphere  is  below  2,000  meters.  On  the 
other  hand,  the  relative  humidity  shows  no  regular  change  with  change 
of  altitude.  Clouds  do  not  necessarily  imply  high  relative  or  absolute 
humidity  of  the  lower  atmosphere.  Eainfall  also  gives  only  a  very  gen- 
eral indication  of  the  humidity  of  the  atmosphere.  A  place  with  high 
rainfall  may  have  low  absolute  and  relative  humidity,  and  vice  versa; 
that  is,  a  rainy  district  is  not  necessarily  a  damp  district,  so  far  as  the 
atmosphere  is  concerned. 

Dew  also  bears  no  constant  relationship  to  the  humidity  of  the  atmos- 
phere, for  a  clear  sky  and  a  dry  atmosphere  favor  its  formation.  Air 
containing  mist  is  obviously  moist. 

Methods  of  Determining  Humidity  in  the  Air. — The  amount  of  water 
vapor  in  the  air  may  be  determined  either  by  (1)  weighing,  (2)  psy- 
chrometers  or  hygrometers,  (3)  the  dew-point. 

Weighing. — The  amount  of  moisture  in  the  air  may  be  determined 
by  passing  a  given  volume  of  air  through  a  tube  or  flask  containing  an 
hygroscopic  substance,  such  as  calcium  chlorid  or  sulphuric  acid.  If 
sulphuric  acid  is  used  small  flasks  are  filled  with  pieces  of  pumice  which 
have  been  heated  to  a  high  temperature  over  a  Bunsen  burner,  and 


HUMIDITY 


901 


dropped  white  hot  in  concentrated  sulphuric  acid ;  re- 
moved, and  quickly  drained. 

The  increase  in  weiglit  represents  the  amount  of 
moisture  in  the  volume  of  air  passed  through  the  flasks, 
or  the  absolute  humidity.  Knowing  the  temperature 
of  the  air,  it  is  then  easy  to  determine  the  relative 
humidity  by  reference  to  tables  of  maximum  water 
capacity  for  certain  volumes  of  air  at  varying  degrees 
of  temperature. 

Psycliroineters. — The  most  convenient  of  all 
methods  for  measuring  atmospheric  moisture  is  to 
observe  the  temperature  of  evaporation,  that  is,  the 
difference  between  the  temperatures  indicated  by  wet 
and  dry  bulb  thermometers.  The  United  States 
Weather  Bureau  regards  the  sling  psychrometer  as  the 
most  reliable  instrument  for  this  purpose.  In  special 
cases  rotary  fans  or  other  means  may  be  employed  to 
move  the  air  rapidly  over  stationary  thermometer 
bulbs. 

The  sling  psycliro meter  consists  of  a  pair  of  ther- 
mometers provided  with  a  handle,  which  permits  them 
to  be  whirled  rapidly  (see  Fig.  91).  The  bulb  of  the 
lower  of  the  two  thermometers  is  covered  with  thin 
muslin,  which  is  wet  at  the  time  an  observation  is 
made.  This  muslin  covering  should  be  kept  in  good 
condition  and  should  be  frequently  renewed.  It  is  also 
desirable  to  use  pure  water.  The  so-called  wet  bulb 
is  thoroughly  saturated  by  dipping  it  into  distilled 
water.  The  thermometers  are  then  whirled  rapidly 
for  15  or  20  seconds,  stopped,  and  quickly  read,  the 
wet  bulb  first.  This  reading  is  kept  in  mind,  the 
psychrometers  immediately  whirled  again  and  a  second 
reading  taken.  This  is  repeated  three  or  four  times 
or  more,  if  necessary,  until  at  least  two  successive  read- 
ings of  the  wet  bulb  are  found  to  agree  very  closely, 
thereby  showing  that  it  has  reached  its  lowest  tempera- 
ture. A  minute  or  more  is  generally  required  to 
secure  a  correct  reading.  The  psychrometer  should 
not  be  whirled  in  the  direct  rays  of  the  sun,  and  if 
used  out  of  doors  the  observer  should  face  the  wind. 
It  is  a  good  plan,  while  whirling  the  instrument,  to 
step  back  and  forth  a  few  steps  further  to  prevent  the 
presence  of  the  observer's  body  from  giving  rise  to 
erroneous  observations. 


to 


Fig.  91. — Sling 

PsVCHBOil- 
ETEB. 


903         PRESSUEE,  TEMPEEATUEE    AND  HUMIDITY 


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HUMIDITY 


903 


In  correcting  psychrometric  observations  the  atmospheric  pressure 
at  the  time  must  be  obtained,  and  the  results  deduced  from  the  tables 
based  on  a  pressure  nearest  that  observed.  The  difference  in  the  tem- 
perature between  the  wet  and  the  dry  bulb  is  computed  to  the  nearest 
tenth  of  a  de^ii'ree.  Ilavinj]^  the  temperature  and  the  pressure  of  the  air 
and  the  ih^pression  of  the  wet  bulb,  it  is  only  necessary  to  read  directly 
from  the  tables  the  dew-point,  the  vapor  pressure,  and  the  relative  humid- 
ity. These  tables  will  be  found  in  Bulletin  No.  235  of  the  United  States 
Weather  Bureau.     A  condensed  table  is  given  in  Fig.  92. 

The  Hair  Hygrometer. — This  apparatus  depends  upon  the  expan- 
sion and  contraction  of  a  suitably  prepared  hair  under  the  influence  of 
moisture.  It  can  be  made  a  reason- 
ably accurate  instrument,  and  some 
types  are  arranged  for  continuous 
record.  One  of  the  principal  diffi- 
culties "with  hair  hygrometers  is 
that  a  sufficient  current  of  air  does 
not  always  come  in  contact  with 
them. 

The  Dew-point. — The  dew-point 
may  be  obtained  by  direct  obser- 
vation from  Regiiault's  apparatus, 
shown  in  Fig.  93.  This  instru- 
ment consists  essentially  of  a  thin 
polished  silver  tube  a,  cemented 
upon  the  lower  end  of  a  long  glass 
tube,  as  shown.  The  stopper  clos- 
ing the  upper  end  of  the  glass  tube 
is  fitted  with  two  lateral  tubes  of 
hard  rubber  h  and  c,  and  also  car- 
ries a  delicate  thermometer,  the 
bulb    of   which    is   placed   near   the 

center  of  the  silver  tube.  The  tube  &  extends  to  the  bottom  of  the 
silver  tube;  c  projects  but  a  short  distance  through  the  cork.  A 
rubber  aspirating  apparatus,  as  shown,  is  connected  with  the  tube  h, 
and  a  long  tube  joined  to  c  serves  to  carry  off  the  fumes.  The  apparatus 
is  held  in  ^  clamp  faced  with  cork  or  other  non-conducting  substance. 

Observations  are  made  by  filling  the  silver  cup  with  ether  or  similar 
volatile  liquid,  which  is  caused  to  evaporate  and  cool  the  silver  cup 
by  manipulating  the  aspirating  bulb.  At  the  proper  point  of  cooling 
a  deposit  of  dew  is  seen  to  form  on  the  polished  silver  surface.  The 
object  is  to  ascertain  accurately  the  temperature  at  which  the  dew  vrill 
just  deposit.  It  is  necessary  that  the  temperature  be  lowered  very  slowly 
at  the  critical  point,  also  that  there  be  plenty  of  liquid  in  the  cup,  and 


Fig.   93  — Dew-poim  Apparatus. 


904         PKESSUEE,  TEMPEEATUEE,  AND  HUMIDITY 

that  it  be  agitated  sufficiently  to  have  a  uniform  temperature  throughout, 
and,  finally,  the  surface  of  the  silver  must  be  perfectly  clean  and  in  a 
favorable  light,  so  that  the  faintest  deposit  of  dew  is  at  once  visible.  The 
temperature  shown  by  the  thermometer  at  this  moment  may  be  regarded 
as  the  temperature  of  the  dew-point.  Knowing  the  dew-point,  the  humid- 
ity of  the  air  may  be  found  by  reference  to  the  above-mentioned  tables. 

Relation  of  Humidity  and  Temperature  to  Health. — The  physiolog- 
ical significance  of  moisture  in  the  air  varies  with  many  factors,  but 
especially  with  temperature.  In  a  general  way  it  may  be  said  that  moist 
air  is  depressing  and  enervating,  while  dry  air  is  tonic  and  stimulating; 
also  that  cold  air  is  tonic,  while  warm  air  is  depressing.  Metabolism 
is  slowed  in  warm  ^^  air,  quickened  in  cold  air.  The  human  body  can 
adapt  itself  to  wide  variations  in  heat  and  humidity,  and  by  means  of 
suitable  clothing  and  food  the  range  may  be  greatly  increased-  Certain 
combinations  of  heat  and  humidity  are  trying  or  even  hurtful;  the  most' 
mischievous  combinations  are  cold,  damp  air  and  icarm  moist  air,  also 
an  excessively  dry  air,  especially  when  artificially  warmed.  Many 
climates  in  which  people  are  reasonably  healthy  have  a  relatively  high 
humidity,  and  some  regions  famed  for  their  salubrity  are  notoriously 
dry  and  arid.  The  frequently  changing  temperatures  and  variable 
amounts  of  water  vapor  of  most  climates  are  beneficial  in  stimulat- 
ing the  heat-regulating  mechanism. 

The  vasomotor  mechanism  and  the  nervous  control  of  perspiration 
are  stimulated  and  made  vigorous  and  efficient  through  moderate  cool 
moving  air,  especially  through  changes  in  the  temperature  and  motion 
of  the  air;  through  well-adapted  clothing;  cold  baths  within  the  limits 
of  reaction;  assisted  by  exercise,  normal  rest,  proper  diet,  and  other 
factors  in  personal  hygiene  that  favor  good  nervous  control. 

The  temperature  and  humidity  of  the  air  affect  health  mainly  by 
influencing  the  heat-regulating  mechanism  of  the  body.  More  heat  is  pro- 
duced within  the  body  than  is  required,  hence  heat  must  be  lost,  else  heat 
stagnation  or  heat  stroke  will  result.  The  temperature  of  the  air,  but  still 
more  its  humidity,  influences  heat  loss.  A  stay  of  about  three  hours  in 
an  atmosphere  at  40.4°  C.  (104.7°  F.)  and  95  per  cent,  relative  humidity 
may  produce  a  rise  of  several  degrees  in  the  body  temperature  of  an 
adult  man.  It  will,  therefore,  be  necessary  briefly  to  review  the  mecha- 
nism by  which  the  constant  temperature  of  the  body  is  maintained. 

Excessive  moisture  makes  hot  air  feel  hotter  and  cold  air  colder — the 
first  by  hindering  evaporation  and  the  second  by  favoring  conduction. 

The  chief  source  of  the  body  heat  comes  from  the  food  we  eat.^^    Ap- 

"  Metabolism  is  quickened  as  soon  as  the  air  becomes  warm  enough  to  raise 
the  body  temperature,  but  at  this  point  symptoms  supervene. 

^An  increase  of  heat  production  in  a  normal  individual  is  due  to  the  tak- 
ing of  food,  the  doing  of  muscular  work,  and  the  exposure  to  cold.  Fever, 
a,cidosis,  and  certain  disturbances  in  internal  secretions  may  also  cause  a  rise. 


HUMIDITY  905 

proximately  80  per  cent,  of  the  food  we  eat  is  used  to  furnish  heat 
to  maintain  the  body  temperature,  while  only  about  20  per  cent,  fur- 
nishes energy  in  the  form  of  motion.  Heat  is  lost  from  the  body 
chiefly  in  two  ways:  (1)  by  heat  transfer,  or  loss  by  radiation,  con- 
duction, and  convection;  controlled  almost  entirely  by  changes  in  the 
dilatation  and  contraction  of  the  blood  vessels  of  the  skin;  (2)  by 
evaporation,  chiefly  by  the  evaporation  of  the  water  of  perspiration; 
controlled  by  the  varying  activity  of  the  sweat  glands.  Pettenkofer 
and  Voit  estimated  the  loss  of  water  by  the  lungs  at  286  grams,  and 
from  the  skin  at  from  500  to  1,700  grams  daily.  This  will  give  some 
idea  of  the  magnitude  of  the  effects  here  concerned.  The  loss  by  heat 
transfer  diminishes  as  the  temperature  of  the  surrounding  air  rises. 
The  temperature  of  the  body  would  rise  when  the  atmospheric  tempera- 
ture goes  above  70°  F.  were  not  perspiration  then  secreted.  So  long 
as  the  perspiration  can  evaporate  freely  the  heat  production  and  heat 
loss  are  balanced.  With  a  high  humidity  evaporation  is  lessened  and 
the  balance  is  maintained  by  rushing  blood  to  the  skin,  which  causes 
an  elevation  of  the  temperature  of  the  surface,  and  thus  the  loss  of 
heat  by  radiation,  conduction,  and  convection  is  facilitated. 

Humidity  influences  the  output  of  heat  from  the  body  in  two  ways : 
(1)  it  increases  the  conductivity  of  atmosphere  for  heat — a  cooling 
influence — hence  cold  moist  air  is  chilling;  (2)  it  interferes  with  evap- 
oration of  perspiration — a  heating  influence — hence  warm  moist  air  is 
enervating.  There  is  a  neutral  zone,  around  68°  F.,  at  which  humidity 
has  comparatively  little  effect.  Hence,  if  the  temperature  of  a  room 
is  kept  just  right  and  the  occupants  are  sitting  still,  it  -makes  little 
difference  w^hether  the  air  is  humid  or  dry.  However,  a  difference  of 
a  few  degrees  above  or  below  this  temperature  will  have  a  marked  influ- 
ence. 

The  so-called  "comfort  zone"  has  a  maximum  temperature,  70°  F.,  a 
minimum  humidity,  30  per  cent. ;  a  minimum  temperature,  55°  to  60°  F., 
and  a  maximum  humidity,  55  per  cent.  This  is  the  range  which  most 
people  in  temperate  climates  find  agreeable.  However,  large  numbers 
of  people  remain  comfortable  and  well  in  climates  that  would  be  trying 
if  the  change  were  made  suddenly.  The  body  possesses  great  powers 
of  adaptability  in  this  regard,  which  is  one  of  the  factors  in  accli- 
matization. 

Eubner  and  his  coworkers  showed  that  the  evaporation  of  water 
from  the  body  cannot  be  regarded  as  being  dependent  merely  on  the 
percentage  humidity  of  the  atmosphere.  The  temperature  of  the  layer 
of  air  in  contact  with  the  body  is  the  factor  of  great  importance.  Thin 
clothes  and  still  air,  under  certain  conditions  of  external  temperature, 
may  favor  evaporation,  while  nakedness  and  moving  air  favor  conduction 
and  radiation.     The' heat-losing  mechanisms  of  the  body  are  adjustable 


906         PEESSUEE,  TEMPEEATUEE,  AND  HUMIDITY 

to  varying  conditions  within  wide  limitations,  so  that  diminished  loss  by 
evaporation  is  compensated  for  by  increased  loss  by  conduction  and 
radiation. 

According  to  Haldane/^  soldiers  marching  in  uniform  are  liable 
to  Tieat  stroke  at  wet-bulb  temperatures  of  under  21°  C. ;  that,  at 
26.7°  wet  bulb  a  marked  rise  of  body  temperature  is  noted  with  muscular 
exercise,  and  hard  and  continuous  work  is  impracticable  even  when  the 
subject  is  stripped  to  the  waist;  while  at  31°-32°  wet  bulb  "in  fairly 
still  air  the  body  temperature  begins  to  rise,  even  in  the  case  of  persons 
stripped  to  the  waist  and  doing  no  work ;  and  when  once  started  this  rise 
continues  until  symptoms  of  heat  stroke  arise,  unless  the  person  leaves 
the  warm  air." 

The  extensive  investigations  of  the  New  York  State  Commission 
on  Ventilation  have  thrown  some  new  light  upon  the  general  problem. 
These  experiments  dealt  with  the  effect  upon  a  large  number  of  sub- 
jects of  three  atmospheric  conditions:  20°  C.  with  50  per  cent,  rela- 
tive humidity  (13°  wet  bulb) ;  24°  C.  with  50  per  cent,  relative  humidity 
(16°  wet  bulb)  ;  and  30°  C.  with  80  per  cent,  relative  humidity  (27° 
wet  bulb).  At  24°  wet  bulb  the  average  rectal  body  temperature  of 
the  subjects  was  2  per  cent,  higher  and  at  30°  it  was  5  per  cent,  higher 
than  at  20°,  showing  that  the  homoiothermy  of  the  human  body  is 
after  all  relative  and  not  absolute,  even  within  a  moderate  range  of 
atmospheric  temperature.  A  somewhat  surprising  observation  was  the 
close  relation  between  the  rectal  body  temperature  at  9  A.  M.  and  the 
mean  air  temperature  for  the  twelve  hours  preceding.  The  curves 
were  so  perfectly  parallel  as  to  leave  no  reasonable  doubt  of  the  direct 
relation  of  cause  and  effect.  There  have  been  conflicting  results  re- 
ported by  various  observers  who  have  compared  body  temperatures  in 
the  tropics  and  in  the  temperate  zone ;  and  it  may  be  that  after  a  pro- 
longed sojourn  in  a  warm  climate  a  compensating  mechanism  is  de- 
veloped which  maintains  a  lower  body  temperature  with  a  given  at- 
mosphere outside. 

The  New  York  State  Commission  on  Ventilation  found  that  in 
addition  to  a  direct  effect  upon  body  temperature,  atmospheric  heat 
exerts  a  profound  influence  upon  the  general  status  of  the  vasomotor 
machinery  as  determined  by  the  Crampton  value.  The  Crampton 
value  is  an  arbitrary  index  of  the  general  tone  of  the  vasomotor  system, 
obtained  from  the  relation  between  the  changes  in  blood  pressure  and 
heart  rate  on  passing  from  a  reclining  to  a  standing  posture. 

The  amount  of  moisture  in  the  air  conducive  to  health  and  well- 
being  is  often  stated  to  be  somewhere  between  50  and  75  per  cent, 
relative  humidity.  These  figures  may  be  very  misleading.  There  is 
no  such  thing  as  a  normal  humidity,  for  the  amount  of  moisture  in 

"  Eng.  Dept.  Com.  on  Humidity  and  Ven.  in  Cotton  Weaving  Sheds,  1910-1911. 


HUMIDITY  907 

relation  to  health  depends  upon  the  temperature,  cloth inf]^,  motion  of 
the  air;  also  upon  diet  and  muscular  activity  aud  other  factors.  Neither 
the  relative  humidity  nor  the  absolute  huniiility  nor  the  temperature  of 
the  air  alone  is  a  satisfactory  guide  as  to  its  condition  in  relation  to 
health.  One  factor  alone  gives  the  sanitarian  scant  information ;  how- 
ever, the  temperature  as  registered  upon  the  wet-bulb  thermometer  is 
most  significant. 

Importance  of  the  Wet-bulb  Temperature. — The  individual  sus- 
ceptibility to  temperatures  depends  entirely  on  the  temperature  re- 
corded by  the  wet-bulb  thermometer/*  no  matter  what  the  dry  bulb  regis- 
ters. Hill,  Rubner,  Pembrey,  Boycott,  Cadman,  Nagel,  and  practically 
all  authorities  agree  with  Haldane  that  the  air  of  workrooms  should 
not  exceed  70°  F.  by  the  wet-bulb  thermometer.  Haldane  places  the 
maximum  comfort  for  men  at  68°  wet  bulb,  while  actual  symptoms  occur 
at  78°  wet  bulb. 

Leonard  Hill  ^^  used  the  Kata-thermometer,  which  consists  of  special 
wet-  and  dry-bulb  alcoholic  thermometers,  and  importance  is  laid  upon 
the  time  required  to  cool  the  wet-bulb  thermometer  from  100°  to  95°  F. 
In  this  way,  the  cooling  power  of  the  air  may  be  determined  and  ex- 
pressed as  a  factor. 

THE  KATA-THERMOMETER 

Dr.  W.  Heberden  ^*'  nearly  100  years  ago  pointed  out  that  the 
actual  temperature  of  the  air  is  only  one  factor  in  determining  the 
effect  of  atmospheric  conditions  upon  the  temperature  of  the  body.  The 
humidity  of  the  air,  and  particularly  the  movement  of  the  air  influence 
heat  loss  and  body  temperature.  The  cooling  power  of  the  air  depends 
upon  the  temperature,  humidity,  and  movement,  and  the  Kata-ther- 
mometer is  a  measure  of  these  three  factors.  Studies  made  with  this 
instrument  show  that  a  temperature  of  26°  C.  outdoors,  with  a  mod- 
erate breeze  blowing,  may  be  more  cooling  in  its  effects  and  hence 
more  comfortable  than  a  temperature  of  32°  C.  indoors  with  still 
air.  For  the  same  reason,  an  overheated  room  with  still  air  in  winter 
is  much  more  uncomfortable  than  a  hotter  day  outdoors  with  moving  air 
in  summer. 

The  Kata-thermometer  outfit  as  first  proposed  by  Hill  consisted 
of  two  specially  constructed  thermometers  with  large  bulbs  and  "stems 
graduated  from  86°  to  110°  F.,  one  to  be  used  as  a  dry  and  the  other 

"One  of  the  thermometers  of  a  psychrometer  is  known  as  the  wet  bulb. 
See  page  901. 

"  The  science  of  ventilation  and  the  open  air  treatment.  Special  Eeport 
Series  No.  32.  National  Health  Insurance,  Medical  Research  Com.,  H.  M.  Sta- 
tionery Office,  1919. 

"""An  Account  of  the  Heat  of  July,  1825;  together  with  Some  Remarks  upon 
Sensible  Cold."     Trans.  Roy.  Soc,  London,  1826,  Part  II,  p.  69. 


908         PEESSUKE,  TEMPEEATUEE,  AND  HUMIDITY 


as  a  wet  bulb  thermometer.  The  bulbs  are  heated  to  about  110°  and 
then  placed  in  clips  which  hold  them  in  horizontal  position,  after 
drying  the  bare  bulb  on  a  clean  cloth  and  jerking  excess  moisture  off 
the  silk  covered  one.  The  time  taken  to  fall  from  100°  to  90°  F.  is  then 
noted,  best  by  the  use  of  a  stop-watch. 

The  rate  of  fall  of  both  thermometers  will  obviously  be  affected  by 
air  movement  and  radiant  heat  as  well  as  by  air  temperature,  and  that 
of  the  wet  bulb  by  the  humidity  of  the  air  as  well.  Dr.  Hill  believes 
that  the  combined  influence  of  these  factors  will  affect  the  Kata-ther- 
mometers  very  much  as  it  does  the  human  body,  and  suggests  a  45  to 
60  second  period  for  the  wet  bulb  and  a  150  to  180  second  period  for 

the  dry  bulb  as  limits  for 
comfortable  atmospheric  con- 
ditions. Eecent  ^  studies  ^'^ 
have  indicated  that  the  lower 
of  the  limits  set  corresponds 
very  closely  to  the  average 
"^  vote  of  a  number  of  Ameri- 
can observers  as  to  bodily 
comfort.  The  lower  limits 
may  be  shorter  with  advan- 
tage, but  should  not  be  ex- 
ceeded. 

Further  readings  may  be 
taken  with  the  thermometers 
(1)  exposed  to,  or  screened 
from,  a  source  of  radiant 
heat;  (2)  exposed  to,  or 
screened  from,  wind  or 
draught;  (3)  with  a  thick  knitted  finger-stall  placed  over  the  bulb  to 
imitate  the  effect  of  clothes.  When  this  finger-stall  is  dampened,  its 
efficiency  is  greatly  diminished.  Thus  the  cooling  effect  of  damp 
clothes  may  be  demonstrated.  The  effect  of  the  color  and  texture  of 
clothes  may  also  be  demonstrated.  A  white  finger-stall  allows  the  in- 
strument to  cool,  when  exposed  to  sunlight,  much  quicker  than  a  dark 
finger-stall.  The  latter  absorbs  the  light  rays  and  converts  them  into 
heat  rays. 

Hill,  Griffith  and  Flack  ^«  have  recently  presented  a  detailed  study 
of  the  physical  problems   involved,   in   which   the  heat  loss   from  the 

"Winslow,  C.  E.  A.:  "The  Kata-Thermometer  as  a  Measure  of  the  Effect 
of  Atmospheric  Conditions  upon  Bodily  Comfort."  Science,  N.  S.,  1916,  XLII 
716.  '  .  ,  , 

"  "The  Measurement  of  the  Rate  of  Heat  Loss  at  Body  Temperature  by  Con- 
vection, Radiation  and  Evaporation,"  Phil,  Trans.  Roy.  Soc,  London,  Series  B, 
1916,  CCVII,  183. 


Fig.  94. — Thf  Kata-thermometee. 


HmriDITY  909 

Kata-thermometer  is  calculated  iu  a  more  exact  manner  in  millicalories 
per  square  centimeter  per  second,  and  tlie  Siebe  Gorman  Company  are 
now  putting  out  instruments  whose  factors  as  compared  with  a  labora- 
tory standard  have  been  determined.  These  new  bulbs  are  graduated 
only  from  95°  to  100°  F.  The  factor  divided  by  the  number  of  seconds 
it  takes  to  make  this  five-degree  drop  gives  the  rate  of  cooling  at  body 
temperature  iu  millicalories  per  square  centimeter  per  second.  The  wet 
Kata-thermometer  gives  the  rate  of  cooling  by  radiation,  convection 
and  evaporation.  The  dry  Kata-thermometer  gives  the  rate  of  cooling 
by  radiation  and  convection. 

This  instrument  is  a  distinct  improvement  over  the  earlier  patterns 
in  that  results  from  different  instruments  are  now  directly  comparable. 

Professor  E.  B.  Phelps,  of  the  United  States  Public  Health  Service, 
has  devised  an  instrument  based  on  the  same  principle,  which  has  the 
great  advantage  of  permitting  of  continuous  records  of  heat  loss.  It 
consists  of  a  wet  bulb  thermometer  heated  by  an  electrical  coil  and 
constant  current  of  such  a  strength  that  in  a  saturated  atmosphere  the 
thermometer  registers  8°  higher  than  an  unheated  bulb. 

Such  instruments  as  these,  which  give  us  information  as  to  the 
actual  heat  loss  from  the  body  surface  as  a  result  of  the  whole  complex 
of  atmospheric  conditions,  promise  to  be  of  the  greatest  service  in  the 
ventilation  studies  of  the  future  (Winslow). 

Rubner  states  that  an  untrained  man  can  be  in  comfort  in  a  tem- 
perature of  75°  F.  and  80  per  cent,  humidit}-  (wet  bulb  about  70°  F.) 
only  when  he  is  quiet.  At  73.4°  F.  and  60  per  cent,  humidity  he  found 
a  resting  man  lost  by  evaporation  75  grams  of  water  per  hour,  and  at 
84  per  cent,  humidity  (wet  bulb  70°  F.)  only  19  grams.  These  figures 
show  that  three-quarters  of  the  heat  loss  may  be  maintained  by  con- 
duction and  radiation  when  the  wet  bulb  reaches  70°  F. 

Cadman  concludes  that  at : 

72°F.  wet  bulb ..  Inconvenience  is  experienced^  iinless  heavy  clothing  is  removed 

and  light  clothing  worn. 
78°     "       "...  .Little  inconvenience  is   felt   if   considerable  bare  body  surface 

is  exposed.     Hard  work  is  much  facilitated  if  a  perceptible 

current  is  passing  over  the  body. 
82°     "       "    ....If   clothes   be   removed,    and   maximima   body    surface   exposed, 

work  can  be  done  providing  current  of  air  is  available. 
85°     "        "    ....Body   temperature   becomes    affected,    and   only   light   work    is 

possible. 

Boycott  made  the  following  significant  observations  upon  himself: 
"At  rest  and  stripped  I  found  that  my  body  temperature  rose  rap- 
idly if  the  wet  bulb  exceeded  88°  or  90°  F.  with  a  drv-  bulb  of  about 
100°  F.,  though  no  rise  occurred  with  a  dry  bulb  of  110°  F.  and  wet  bulb 
of  less  than  85°  F.  I  have  on  many  occasions  spent  periods  of  about  an 
hour  in  doing  ordinary  laboratory  work  in  air  with  the  dry  bulb  at 


910         PRESSTTEE,  TEMPEEATUEE,  AND  HUMIDITY 

95°  F.  and  the  wet  bulb  at  about  65°  E.  without  any  material  discomfort. 
If,  however,  the  wet  bulb  rises  to  88°  or  90°  F.,  one's  body  temperature 
begins  to  go  up,  even  when  completely  at  rest,  and  one  becomes  exceed- 
ingly uncomfortable  and  on  occasions  feels  very  ill.  These  sensations  can 
be,  to  some  extent,  remedied  by  local  cooling  of  the  skin  (e.  g.,  cold  water 
on  the  head),  but  the  rise  of  body  temperature  is  progressive  and  must 
eventually  end  in  heat-stroke.'^ 

A  man  is  much  less  efficient  in  a  warm  moist  atmosphere;  hence  it 
is  an  advantage  to  both  employer  and  employee  that  work  be  performed 
at  temperatures  below  70°  F.  by  the  wet  bulb.  At  the  lower  tempera- 
tures work  is  done  faster,  more  efficiently,  and  with  less  fatigue,  dis- 
comfort, and  injury  to  health.  To  work  in  a  warm  moist  atmosphere 
increases  the  temperature,  pulse,  and  loss  of  moisture  out  of  propor- 
tion to  the  work  done.  It  is  the  master's  pockets  which  suffer  under 
such  conditions,  for  the  workers  instinctively  avoid  the  discomfort  of 
overheating  themselves  through  lessened  exertion. 

The  Xew  York  State  Commission  on  Ventilation  clearly  showed  the 
effects  of  high  atmospheric  temperatures  upon  the  working  power — 
or  more  properly  upon  the  actual  performance  of  the  working  organ- 
ism. Under  a  strong  stimulus  the  power  to  do  mental  or  physical  work 
for  a  short  time  is  not  diminished  even  at  30°  C.  with  80  per  cent, 
relative  humidity.  "It  is  a  matter  of  common  experience  that  even  a 
highly  uncomfortable  degree  of  heat  is  no  hindrance  to  absorbing  in- 
tellectual work  and  no  bar  to  a  good  game  of  tennis"  (Winslow).  The 
disinclination  to  do  active  work  at  a  moderately  high  atmospheric 
temperature  may  be  interpreted  as  a  conservative  and  protective  process 
on  the  part  of  nature. 

Effects  of  Warm  Moist  Air. — In  a  hot  moist  atmosphere  an  undue 
amount  of  blood  is  brought  to  the  surface  of  the  body,  mental  and  physi- 
cal activity  is  reduced,  a  feeling  of  depression  is  felt,  and  the  resulting 
rise  in  temperature  of  the  body  influences  the  entire  nervous  and  circu- 
lating systems.  There  is  a  disinclination  to  make  a  physical  or  mental 
effort, — in  other  words,  the  effect  is  enervating.  When  air  above  88°  F. 
becomes  saturated  evaporation  can  no  longer  compensate  for  decrease  in 
radiation,  and  the  body  temperature  accordingly  rises  and  heat-stroke 
may  ensue.  The  injurious  effects  of  the  summer  heat  are  practically 
always  the  result  of  combined  heat  and  humidity. 

According  to  Eubner  and  Lewaschew,  when  the  air  is  very  humid 
the  heat  loss  by  evaporation  is  very  much  lessened,  and,  accordingly,  at 
80  per  cent,  humidity  and  temperature  of  24°  C.  (75.2°  F.)  becomes 
after  a  time  insupportable  to  a  man  unaccustomed  to  it,  and  exposure 
to  it  is  only  possible  with  complete  muscular  rest.  If,  however,  the 
air  is  very  dry  a  temperature  of  24°  to  29°  C.  (75.2°  to  84.2°  F.) 
can  be  usually  endured.     These  temperatures  are  often  exceeded  in  the 


HUMIDITY  911 

summer  time  in  America.  By  practice  a  certain  amount  of  accom- 
modation to  the  elTects  of  a  liot  moist  climate  may  be  acquired. 

Tliere  is  no  kiidwji  serious  injury  to  health  caused  by  working  in  a 
warm  moist  air,  provided  that  a  considerable  rise  of  body  temperature 
is  avoided.  The  etfects  of  heat  and  moisture  may  be  diminished  by  light 
clothing,  bare  legs  and  arms,  whereby  the  loss  of  heat  from  the  skin 
is  increased. 

"Working  in  moist,  overheated  rooms  has  the  further  disadvantage 
of  wetting  the  clothes  with  perspiration,  which  causes  discomfort, 
dirt,  and  untidiness,  and  liability  to  chilling  the  surface  on  going  out- 
doors. 

The  effect  on  efficiency  is  not  diminished  power,  but  loss  of  desire  to 
work.  Winslow  found  that  37  per  cent,  more  work  was  done  at  68°  F, 
than  at  86°  F. 

A  poorly  ventilated  room  in  which  the  air  becomes  vitiated  is  usually 
a  warm  moist  atmosphere,  and  the  ill  effects  of  a  vitiated  atmosphere 
are  mainly  caused  by  the  heat  and  moisture.  One  of  the  most  mis- 
chievous effects  of  a  warm  moist  atmosphere  is  disinclination  to  mental 
and  physical  effort  and  loss  of  appetite. 

Effects  of  Cold  Damp  Air. — Cold  damp  air  causes  a  rapid  loss  of 
heat  and  chilling  of  the  body.  When  such  air  is  injurious  the  victim  is 
usually  underclad,  improperly  fed,  or  has  been  living  an  indoor  life. 
In  certain  cases  cold  damp  must  always  be  injurious,  as,  for  instance, 
where  the  vital  forces  are  at  a  low  ebb  and  where  there  is  restricted 
capacity  for  making  heat,  such  as  infancy  or  old  age ;  in  cases  of  kidney 
disease,  where  hindrance  of  evaporation  and  increased  metabolism  means 
extra  work  for  the  kidneys;  also  in  cases  where  there  is  a  tendency  to 
rheumatism  or  disorders  of  metabolism.  The  effects  of  cold  damp  air 
may  be  neutralized  by  proper  clothing,  by  muscular  activity,  and,  to  a 
limited  extent,  by  diet. 

Just  how  cold  damp  air  influences  health  is  not  well  understood. 
It  throws  an  added  load  upon  the  heat-producing  mechanism  to  main- 
tain the  body  temperature;  the  strain  falls  especially  upon  digestion, 
and  metabolism,  and  also  upon  the  circulation  and  the  kidneys,  and 
indirectly  upon  the  nervous  system.  Dr.  H.  I.  Bowditch  in  1862  formu- 
lated the  law  of  soil  moisture,  and  believed  that  tuberculosis  was  more 
common  over  moist  soils  than  dry  ones.  According  to  our  present  con- 
ception, the  relation  between  dampness  or  moist  soil  and  tuberculosis  is 
quite  indirect;  if  there  is  any  connection  it  is  due  merely  to  the  fact 
that  the  combination  of  cold  and  dampness  depresses  vitality  and  thereby 
lowers  resistance. 

A  person  will  shiver  and  the  lips  turn  blue  on  a  very  cold  misty 
day,  especially  when  facing  the  wind.  This  is  due  to  the  fact  that  under 
such  conditions  the  respiration  is  shallow,  probably  as  the  result  of  a 


912         PEESSUEE,  TEMPEEATUEE,  AND  HUMIDITY 

protective  mechanism;  and  the  interchange  of  gases  in  the  lungs  is 
slowed,  for  moisture  interferes  with  diffusion. 

A  healthy  man  may. daily  move  in  and  breathe  cold  damp  air  with- 
out suffering  in  health  to  any  appreciable  extent;  however,  it  is  gener- 
ally believed  that  a  cold  damp  air  predisposes  to  affections  of  the  re- 
spiratory passages,  to  rheumatism,  and  neuralgias. 

Effects  of  Warm  Dry  Air. — A  relatively  dry  air  feels  better  than 
moist  air  at  most  temperatures.  The  stimulating  and  pleasant  effects  of 
a  dry  climate  can  only  be  appreciated  by  one  who  has  visited  an  arid 
region — such  as  our  southwestern  plateau.  However,  when  air  is  ab- 
normally dry,  especially  if  warm,  the  evaporation  from  the  body  is 
greatly  increased.  Thus,  Eubner  and  Lewaschew  found  that  a  man 
weighing  58  kilograms  gave  off  the  following  amounts  of  carbon  dioxid 
and  moisture  in  one  hour  at  different  temperatures  in  dry  and  moist 
air: 


Dry  Air 

Moist  Air 

Temperature 

Relative 

Humidity 

of  Air 

CO2 

H2O  ' 

Relative 

Humidity 

of  Air 

CO2 

H2O 

15°  C 

20°   C 

25°  C 

29°  C 

8% 
5% 
6% 
6% 

32.2  gm. 
30.0  gm. 
31.7  gm. 
32.4  gm. 

36.3  gm. 
54.1  gm. 

75.4  gm. 
103.3  gm. 

.   89% 
82% 
81% 

34.9  gm. 

28.3  gm. 

31.4  gm. 

9.0  gm. 
15.3  gm. 
23.9  gm. 

Air  that  is  warm  and  at  the  same  time  abnormally  dry,  such  as  that 
produced  by  furnace  heat,^^  causes  an  excessive  loss  of  moisture  and  con- 
centration of  the  fluids  in  the  tissues  and  organs  of  the  body.  Man 
consists  of  58.5  per  cent,  of  water.  A  very  small  percentage  of  loss 
may  be  serious;  when  the  percentage  reaches  21  per  cent,  death  results. 
The  warmed  and  dried  atmosphere  of  our  overheated  houses  gives  a 
sense  of  chilliness,  owing  to  excessive  evaporation,  and  favors  irritation 
and  infection  of  the  respiratory  mucous  membranes.  If  a  room  at  68° 
F.  is  not  warm  enough  for  a  healthy  person,  we  may  be  sure  that  it  is 
because  the  humidity  is  too  low. 

The  problem  of  constructing  buildings  in  such  a  way  as  to  keep  the 
interior  up  to  a  fair  degree  of  humidity  is  a  large  one.  So  far  engineers 
have  made  little  practical  progress  toward  its  solution.  Satisfactory 
devices  may  be  had  to  improve  the  moisture  in  large  public  buildings, 
but  these  devices  have  so  far  proved  too  expensive  for  private  dwellings, 
offices,  or  schoolrooms. 

The  humidity  in  living  rooms  may  be  improved  by  setting  about 
growing  plants  and  porous  dishes,  such  as  flower  pots  full  of  water.    If 

"  See  page  986- 


HUMIDITY  913 


such  receptacles  are  set  near  electric  fans   evaporation  is  facilitated. 
Pans  or  pots  of  water  may  also  be  placed  upon  the  radiator. 

A  cool  dry  air  is  bracing.  All  the  body  functions  are  more  active, 
breathing  is  deeper  and  more  frequent,  the  circulation  of  the  blood  is 
increased;  digestion,  assimilation,  and  metabolism  are  stimulated. 


CHAPTEE   III 

MISCELLANEOUS 

ODORS 

People  have  ahvays  believed,  and  still  naturally  cling  to  the  notion, 
that  anything  that  smells  bad  must  be  detrimental  to  health.  Sci- 
ence has  demonstrated  that  our  sense  of  smell  is  a  poor  sanitary  guide. 
Smell  is  not  primarily  a  protective  sense.  Its  chief  function  among 
animals  is  to  find  food  and  mates.  While  disagreeable  odors  may  not  be 
harmful,  they  should  be  eliminated  for  esthetic  and  psychological  rea- 
sons, as  well  as  for  decency  and  cleanliness. 

The  viruses  of  most  diseases  have  no  odor  whatever.  Some  diseases, 
as  smallpox,  are  associated  with  a  disagreeable  odor.  In  no  case  is  the 
odor  diagnostic.  Infections  in  water,  milk  or  food  cannot  be  sensed 
by  smell. 

Odors  in  a  living  room  come  mostly  from  human  sources.  The 
sources  of  these  odors  are :  foul  breath,  decaying  teeth,  unclean  mouths, 
nasal  catarrh,  sudoriferous  glands,  especially  those  of  the  pubes,  feet, 
and  axillae,  also  gases  from  the  stomach  and  bowels.  The  decomposi- 
tion of  matter  on  the  skin  and  also  in  the  clothes  adds  a  very  disagree- 
able odor,  accentuated  in  a  warm  moist  atmosphere.  The  peculiar  odor 
in  some  rooms,  especially  sick  rooms,  seems  to  be  none  of  these;  just 
what  constitutes  the  somewhat  characteristic  man-smell  is  not  known. 

While  odors  may  be  very  unpleasant,  they  are  not  known  seriously  to 
influence  health;  contrary  to  common  opinion,  they  are  not  by  any 
means  a  reliable  sign  of  danger.  The  presence  of  bacteria  or  dust  in 
the  atmosphere  has  no  special  relation  to  odors.  Some  poisonous  gases, 
such  as  carbon  monoxid;,  are  practically  inodorous. 

The  air  of  inhabited  rooms  ordinarily  must  be  quite  full  of  various 
scents  which  we  do  not  appreciate^  either  because  our  sense  of  smell 
is  not  keen  enough,  or  because  we  have  become  so  accustomed  to  them 
that  they  are  not  noticed.  An  atmosphere  that  does  not  appear  to  be 
unpleasant  while  remaining  in  a  room  may  seem  intolerable  upon  re- 
turning to  it  after  a  period  in  the  fresh  outdoor  air.  ]\Ian's  sense  of 
smell  is  not  keen  when  compared  to  that  of  some  of  the  lower  animals ; 
nevertheless  it  is  extremely  sensitive  to   certain  odors.     Thus,  it  can 

914 


ODORS  915 

determine  0.000,000,5  milligram  of  tiiRtiire  of  musk.  The  acuteness 
of  the  sense  of  smell  varies  markedly  in  dilferent  individuals. 

Odorous  molecules  detach  themselves  from  the  surface  of  solids 
and  liquids  by  simple  evaporation,  by  oxidation  and  by  hydrolytic  de- 
composition. Currents  of  air  will  carry  odors  as  they  carry  dust  along 
with  them  to  quite  a  distance.  All  odorous  substances  are  freely 
soluble  in  oil. 

It  is  well-known  that  we  can  perceive  odors  much  more  readily  when 
the  air  is  moist  than  when  it  is  dry.  It  is  also  known  that  the  mucous 
membrane  of  the  nose  must  be  moist  in  order  that  an  odor  be  perceived. 
IMost  fishes  have  a  well-developed  sense  of  smell. 

Passy  determined  the  least  amounts  of  odorous  matter  that  can  be 
perceived  by  us.  He  gives  the  following  figures  per  liter  of  air  in 
which  certain  substances  are  dissolved  and  can  be  perceived. 

Camphor   0.005       milligram  per  liter  of  air 

Ether  0.004  to  0.005     "        "       "       "     " 

Sulphureted  hydrogen 0.0005  "        "       "       "     " 

Mercaptan    0.000,000,04       "        "       "       "     " 

The  olfactory  nerves  soon  tire  of  most  odors,  and  after  a  certain 
time,  fail  to  respond.  While  in  this  condition  they  can  at  once  perceive 
the  sudden  appearance  of  other  odors.  For  example:  Aronson  found 
that  persons  having  become  insensible  to  the  odor  of  iodin  from  continu- 
ous use  found  their  perception  to  the  odor  of  ether  at  once  perfect. 
Ordinary  ventilation  does  not  remove  the  vapors  which  are  held  on 
solid  surfaces  by  absorption.  A  jet  of  compressed  air  frequently  played 
against  the  interior  surfaces  of  buildings  and  against  the  clothing  will 
remove  this  source  of  odors.  Hence,  the  value  of  opening  windows 
and  thoroughly  flushing  out  rooms  from  time  to  time, 

Wlien  a  room  smells  stuffy  and  close  it  may  be  taken  as  a  fairly 
reliable  index  that  the  air  is  vitiated;  this  is  especially  true  in  a  clean 
room  not  complicated  with  odors  from  clothing  and  sources  other  than 
man.  In  fact,  the  odors  observed  upon  entering  a  room  from  the  out- 
side fresh  air  often  furnish  better  evidence  of  imperfect  ventilation  or 
lack  of  cleanliness  than  laboratory  tests. 

De  Chaumont  made  accurate  observations  and  found  that  when  the 
CO,  amounts  to  6  parts  per  10,000  in  an  inhabited  room,  the  atmosphere 
begins  to  smell  close  and  stuffy.  Pettenkoffer  found  air  containing  7.5 
parts  of  CO2  per  10,000  from  the  expired  breath  to  have  a  marked  odor, 
and  10  parts  a  very  unpleasant  odor.  With  a  little  practice  various 
grades  of  vitiated  air  can  be  detected  up  to  10  or  12  parts  of  CO2  per 
10,000. 

The  odors  from  marshes  and  from  decomposing. organic  matter  are 
not  apparently  hurtful.     One  of  the  most  famous  stenches  that  ha3 


916  MISCELLANEOUS 

been  recorded,  if  not  the  most  famous,  was  that  which  arose  in  1858 
and  1859  from  the  Thames,  which  at  that  time  was  grossly  polluted 
with  the  sewage  of  London  (Sedgwick).  Dr.  Budd  insisted  that  no 
very  serious  results  followed.  After  giving  his  proof  Budd  ^  states : 
"Before  these  inexorable  figures  the  illusion  of  half  a  century  van- 
ished in  a  moment."  We  now  know  that  odors  in  the  air  bear  no 
reference  to  contagion  or  infection  and,  however  unpleasant,  need  not 
be  feared  as  such.     Sewer  "gas"  is  discussed  on  page  949. 

Winslow  and  Palmer  ^  found  that  "odors"  (?)  of  vitiated  air  have 
an  unfavorable  influence  upon  appetite. 

The  effect  of  odors  upon  health  is  not  well  understood.  When  we 
sense  a  pleasant  smell  we  involuntarily  take  deeper  breaths;  on  the 
other  hand,  unpleasant  odors  diminish  the  respiratory  exchange.  The 
latter  are  accordingly  harmful  to  that  extent  and  the  forme-r  stimulat- 
ing. Odors  influence  the  nervous  system  in  various  ways;  some  stim- 
ulate, others  depress  psychic  activity;  some  odors  have  a  well-known 
influence  upon  sexuality.  Occasionally  odors  are  so  disagreeable  that 
they  induce  nausea,  even  vomiting.  It  is  remarkable  how  quickly  we 
may  become  accustomed  to  odors,  but  because  our  sense  of  smell  has 
been  dulled  is  no  guarantee  that  the  cause  of  the  odors  may  not  con- 
tinue to  produce  its  effects.  Leonard  Hill  thinks  that  it  is  very  doubt- 
ful if  the  unpleasant  smelling,  exhalations  of  the  bodies  of  men  have 
any  ill  effects  on  men  accustomed  to  them,  and  not  of  esthetic  tem- 
perament. 

Odors  in  a  confined  space  may  be  largely  removed  by  washing  the  air 
through  a  spray  of  water.  The  water  absorbs  the  odors  so  that  the  wash- 
water  smells  like  a  stuffy  room.  The  odors  may  also  be  neutralized  or 
concealed  with  ozone,  formaldehyd,  and  other  substances,  but  the  best 
deodorants  are  cleanliness  and  ventilation. 


LIGHT— OCULAR  HYGIENE 

All  the  rays  of  the  sun  pass  through  the  atmosphere  before  they 
reach  the  earth.^  The  air  acts  as  a  differential  filter,  holding  back 
many  rays,  especially  those  of  shorter  wave  length;  that  is,  the  ultra- 
violet end  of  the  spectrum.  These  rays  have  marked  chemical  and  photo- 
dynamic  action.     We  have  already  seen  that  some  of  the  heat  rays  are 

^Dr.  William  Budd:  "Typhoid  Fever:  Its  Nature,  Mode  of  Spreading,  and 
Prevention,"  pp.  148-151.  London,  1873.  This  is  a  remarkable  contribution 
which  the  student  is  advised  to  read. 

^^  Proceed.  Soc.  Exp.  Biol,  and  Med.,  1915;  XII,  141. 

^The  waves  of  light  are  not  waves  of  the  atmosphere,  but  of  the  ether; 
however,  they  are  absorbed,  reflected  or  refracted  by  the  dust  and  moisture 
contained  in  the  air:  It  is  convenient  to  consider  light,  as  well  as  electricity 
and  radio-activity;  at  this  point. 


LIGHT— OCULAR  HYGIENE  917 

also  absorbed  by  the  atmosphere.  "More  heat  and  we  might  be  roasted, 
more  light  and  we  might  be  blinded,  more  chemical  cnerg}^  and  we 
might  be  slain  like  the  microbes." 

The  air  as  a  filter  of  the  sun's  rays  bears  a  very  important  but  little 
understood  relation  to  life.  It  is  now  well  known  that  some  of  the  sun's 
rays  have  intense  chemical  and  "vital"  power.  We  know  something 
about  the  chemical  rays,  the  luminous  rays,  and  the  calorific  rays,  but 
there  are  doubtless  vibrations  of  which  we  know  nothing.  Macfie  spec- 
ulates that,  "even,  indeed,  as  the  crops  of  the  northern  zone  outstrip 
the  crops  in  the  south  of  France,  so  at  certain  times  may  the  activity 
of  nations  be  stimulated  or  depressed  by  atmospheric  variations  affecting 
the  composition  of  solar  radiation." 

Light  prevents  the  growth  of  bacteria  and  fungi  and  retards  other 
living  processes  which  ordinarily  occur  in  the  dark,  such  as  the  develop- 
ment of  seeds  and  the  roots  of  plants.  On  the  other  hand,  light  promotes 
the  development  of  algae  and  the  higher  forms  of  plants  and  animals. 

Life  on  the  earth  depends  upon  the  radiant  energy  from  the  sun. 
Heat,  sunshine,  and  other  forms  of  light,  such  as  X-rays,  are  physically 
of  the  same  general  nature,  and  differ  from  each  other  only  in  the 
degree  of  intensity  of  their  action.  Light  induces  or  Imstens  most 
chemical  reactions  just  cus  heat  does.  The  debilitating  effect  of  tropical 
cKmates  may  not  be  entirely  due  to  the  heat, ,  but  in  large  part  to  the 
actinic  rays  of  the  sun's  spectrum. 

The  physiologic  action  of  light  is  just  beginning  to  receive  the  serious 
attention  it  deserves.  We  are  all  familiar  with  the  calming  effect  of  the 
dim  religious  light  of  churches  and  the  stimulating  effect  of  the  glare 
of  the  "Great  White  Way."  The  intense  light  of  the  tropics  and  of  high 
altitudes  is  believed  in  some  way  to  bring  on  nervous  disorders,  but  the 
relation  is  but  vaguely  understood.  Some  of  the  ill  effects  attributed  to 
bad  air  and  poor  ventilation  are  due  in  part  to  the  overstimulations  of 
excessive  illumination.* 

Sunlight  has  an  important  bearing  upon  health  which  is  highly 
beneficial.  Excessive  exposures  to  sunlight  may  be  harmful,  especially 
in  the  tropics;  on  the  other  hand,  we  have  snow  blindness  in  the  arctic 
zone,  and  sunburn  in  any  climate.  The  radiant  energy  of  the  sun  in 
outdoor  life  has  a  most  important  influence  on  the  surface  temperature 
of  the  skin  and  our  feeling  of  comfort. 

Aschenheim  ^  found  that  after  an  hour^s  exposure  of  the  body  to  the 
direct  action  of  sunlight  there  was  a  general  leukocytosis  in  the  periph- 
eral blood  with  a  relative  increase  in  the  lymphocytes  and  a  decrease 

*An  illuminating  discugsion  of  the  physiologic  action  of  light  will  be  found 
in  W.  M.  Bayliss'  "Principles  of  General  Physiology,"  London,  1915,  a  book 
which  should  be  studied  by  all  students. 

''Aschenheim,  E.:  "EflFect  of  the  Sun's  Rays  on  the  Leucocyte  Count," 
Zeitschr.  f.  KinderTieiVkunde,  Berlin,  IX,  2. 


918  MISCELLANEOUS 

in  polymorphonuclear  leukocytes  in  80  per  cent,  of  the  cases.  Lympho- 
cytes are  regarded  as  one  of  the  body's  defenses  against  tuberculosis,,  and 
Aschenheim  suggests  that  this  may  account  for  the  favorable  effect  of 
sunlight  on  tuberculosis.  Prolonged  exposure  of  the  body  to  bright  sun- 
light in  those  who  haA'e  not  been  accustomed  to  its  rays  may  be  delete- 
rious and  even  dangerous.  The  damage  is  more  than  the  sunburn  result- 
ing, for  it  may  even  lead  to  serous  meningitis.^ 

In  northern  climates,  heliotherapy  has  received  considerable  atten- 
tion, and  its  value  has  been  somewhat  exaggerated,  whereas  in  America 
this  form  of  treatment  has  been  largely  neglected. 

In  1898,  Eaab  ^  discovered  that  the  effect  of  sunlight  may  be  greatly 
reenforced  by  the  action  of  many  fluorescent  dyes.  Thus,  a  culture  of 
paramecia  was  uninjured  by  acridin  (1  to  20,000)  in  the  dark,  but  in 
direct  sunlight  death  occurred  in  six  minutes.  In  the  absence  of  acridin, 
sunlight  exerted  but  little  detrimental  influence.  All  bacteriologists 
know  the  germicidal  power  of  sunlight  on  bacteria,  which  is  due  to  the 
rays  of  short  wave  length  beyond  the  violet  end  of  the  spectrum. 

Sellards  *  states  that  direct  sunlight  of  the  tropics  (Colombia) 
exerts  no  deleterious  effect  on  cultures  of  malarial  parasites,  but  is  mod- 
erately deleterious  to  cultures  of  Entamoeba  histolytica.  Bilirubin  was 
found  to  exert  a  pronounced  effect  upon  the  clotting  of  blood  in  vitro 
in  the  presence  of  sunlight.  A  small  amount  of  bilirubin  in  oxalated 
plasma  exposed  to  sunlight  completely  prevented  clotting  when  serum 
was  added.    Controls  kept  in  the  dark  clotted  readily. 

Bovie  ®  points  out  that  the  red  color  of  the  blood  protects  our  bodies 
from  the  actinic  solar  rays  quite  as  efficiently  as  we  protect  our  photo- 
graphic plates  by  using  a  ruby  light.  The  pigments  of  the  skin  also  serve 
a  protective  purpose.  Blondes  are  more  susceptible  to  sunburn  than 
brunettes,  who  also  stand  tropical  climates  better  than  the  former. 

Snow  Blindness. — The  dazzling  reflection  of  the  rays  from  snow  and 
ice  fields  is  often  a  source  of  great  annoyance  and  even  danger  to 
mountaineers  and  arctic  explorers.  The  damage  is  due  to  the  excess 
of  ultraviolet  rays  rather  than  to  the  intensity  and  direction  of 
the  light.  The  excessive  amount  of  ultraviolet  rays  burns  the  con- 
junctiva and  even  the  cornea,  and  may  cause  serious  inflammation.  The 
same  effects  occur  in  electric  welding.  The  best  protection  is  afforded 
by  mussel-shaped  smoked  or  tinted  glasses  in  a  common  spectacle 
frame. 

intraviolet  Light. — The  greater  number  of  the  constituents  of  living 

cells  are  colorless,  that  is,  they  do  not  absorb  rays  of  the  wave  length 

of  visible  light.     Many  of  them,  however,  absorb   ultraviolet  light   so 

^Romer:     Deutsch.  med.  Wcluischr.,  July  8,  1915.  p.  8.32. 
'  Ztschr.  f.  Biol.,  1900.  XXXIX.  .524.     Ibid.,  190.3,  XLIV,  16. 
^Journ.  Med.  Res.,  Vol.  XXXVIII.  3.  .Julv,  1918. 
8  Ibid. 


LIGHT— OCULAR  HYGIENE  919 

that  radiation  of  this  kiixl  has  a  powcrt'iil  cUVct  on  livin<(  cells.  The 
effects  of  radium  and  X-rays  on  living  tissue  are  similar  to  those  of 
intense  ultraviolet  light. 

Ultraviolet  light  and  other  rays  of  short  wave  lengths  have  chemical 
and  photodynamic  powers  which  must  have  an  important  relation  to 
health.  They  are  the  most  potent  and  probably  the  most  important  rays 
from  the  sun  and  other  sources  of  light.  These  rays  act  upon  photo- 
graphic negatives;  hasten  the  hatching  of  flies'  eggs  and  frogs'  eggs; 
they  sunburn  the  skin  and  produce  freckles;  they  kill  many  bacteria, 
including  the  tubercle  bacilli;  they  cause  heliotropism ;  they  combine 
chlorin  and  hydrogen  into  hydrochloric  acid;  they  cause  the  oxidation  of 
oxalic  acid  and  other  chemical  reactions ;  they  blacken  silver  salts. 

It  has  long  been  known  that  various  small  animals  such  as  tiny  Crus- 
tacea found  in  fresh  water,  flee  from  places  "illumined"  by  ultraviolet 
light.  The  effect  of  ultraviolet  rays  is  independent  of  temperature, 
showing  that  the  reaction  is  photochemical. 

The  bactericidal  action  of  sunlight  is  due  entirely  to  the  ultraviolet 
rays.  These  rays  of  short  wave  length  are  further  considered  throughout 
this  section,  and  also  on  pages  918,  1144  and  1375. 

Photodynamic  Action. — Familiar  examples  of  photodynamic  reactions 
are  the  chlorophyll  system,  retinal  processes,  and  the  action  of  ultra- 
violet light;  also  photographic  methods  and  wireless  telegraphy.  The 
phenomenon  is  also  considered  under  the  term  photochemical  reaction, 
sometimes  photosensitization. 

Sunlight  in  the  presence  of  certain  fluorescent  substances  ^°  may  be- 
come surprisingly  active,  approaching  in  its  deleterious  effects  on  living 
cells,  the  order  of  magnitude  of  the  effects  of  X-rays  and  similar  short 
radiations. 

The  most  important  of  all  photochemical  reactions  is  that  by  means 
of  which  the  chlorophyll  of  green  plants  stores  up  light  energy,  and  in 
the  process  gives  oxygen  to  the  atmosphere  in  return  for  carbon  dioxid 
absorbed.  Chlorophyll  absorbs  chiefly  the  red  end  of  the  spectrum  and 
therefore  is  most  active  during  the  day. 

The  combined  action  of  light  and  certain  fluorescent  substances  may 
cause  skin  rashes  and  serious  disorders  terminating  in  death.  Thus, 
buckwheat  when  fed  to  sheep  and  swine  for  the  most  part  produces  no 
untoward  effect,  especially  in  the  dark  days  of  winter,  when  the  animals 
are  kept  under  cover  in  stalls.  But  if  the  animals  are  white,  or  have 
white  spots  exposed  to  bright  light,  then  serious  symptoms  frequently 
develop  (fagopyrismus).  The  symptoms,  if  not  too  far  advanced,  sub- 
side when  the  animals  are  returned  to  darkened  buildings,  or  even  if 

^^  Phosphorescence  and  fluorescence  represent  photochemical  reactions  with 
storage  of  light  energy.  H.  v.  Tappeiner  und  A.  Jodlbauer :  Die  sensibilisierende 
Wirkung  fluorescierender  Substanzen.    Leipzig,  1907. 


920  MISCELLANEOUS 

the  hair  is  artificially  colored.    Under  the  same  conditions  of  light  and 
food,  animals  that  are  dark  in  color  remain  well, 

Eaab  ^^  was  the  first  to  demonstrate  that  toxic  effects  can  be  obtained 
in  small  animals,  white  in  color,  by  eosin,  chlorophyll  and  by  the 
derivatives  of  hemoglobin.  Hausmann  ^^  injected  white  mice  with  hema- 
toporphyrin.  Those  animals  which  were  kept  in  the  dark  developed 
no  symptoms,  while  those  exposed  to  direct  sunlight  developed  lesions 
resembling  sunburn  at  the  most  exposed  parts,  such  as  the  tips  of  the 
ears,  nose  and  tail.  Death  subsequently  resulted.  Exposure  to  bright 
diffused  light  produced  marked  symptoms. 

The  eruptions  on  the  exposed  surfaces  in  pellagra  and  other  diseases 
have  been  explained  upon  the  principles  of  photosensitization. 

The  action  of  light  in  the  presence  of  fluorescing  substances  upon  red 
blood  corpuscles  and  immune  bodies  has  been  studied  by  Sellards,  Bovie 
and  Brooks. ^^  The  agglutinating  action  of  ricin,  the  hemolytic  action 
of  crotin,  the  poisonous  action  of  -diphtheria  and  tetanus  toxin,  and  the 
protective  effects  of  tetanus  antitoxin  are  injured  or  destroyed  by  photo- 
dynamic  action.  Many  enzymes  are  susceptible  to  light  alone,  but  this 
effect  is  usually  increased  by  the  presence  of  a  fluorescent  body. 

Lighting. — Better  lighting,  especially  daylight,  improves  health  and 
comfort,  makes  work  and  play  more  agreeable,  increases  production, 
and  diminishes  the  chances  of  accidents.  There  is  no  light  equal  to  day- 
light. The  general  rule  is  to  have  at  least  one  square  foot  of  window  to 
every  five  square  feet  of  floor  space.  This  will  vary  with  the  location, 
size,  shape  and  purpose  of  the  room.  In  tropical  countries  buildings 
have  large  wall  spaces  and  small  window  openings,  while  in  high  lati- 
tudes the  converse  has  been  found  desirable.  The  importance  and 
economy  of  plenty  of  daylight  has  caused  a  fundamental  change  in  the 
architectural  design  of  buildings  through  the  invention  of  the  steel  sash. 
Prismatic  glass  is  useful  in  giving  rooms  more  natural  light.  Skylights 
are  practical  and  should  be  used  more  than  they  are.  Sharp  contrasts 
must  be  avoided.  A  light  viewed  against  the  bright  sky  in  day  time  is 
scarcely  noticed,  whereas  the  same  light  against  a  black  background  is 
unbearable.  Glare  from  any  source  is  to  be  avoided.  A  well  illumined 
room  will  have  both  direct  and  indirect  lighting.  Direct  light  gives 
sharply  defined  shadows ;  diffused  light  gives  indefinite  and  soft  shadows, 
or  none  at  all.  The  light  should  be  of  such  a  character  as  to  relieve 
the  background  of  gloom.  The  light  must  shine  on  the  object  of  interest 
and  not  in  the  eyes  of  the  observer.  All  shades,  globes,  reflectors,  etc., 
should  have  this  simple  object  constantly  in  view.  The  best  direction 
of  light  for  close  work  is  from  the  rear,  over  the  left  shoulder.     A  safe 

^Zeitschr.  f.  Biol.,  1900,  XXXIX,  524.     Ihid.,  1903,  XLIV,  16. 
■"■"Wien.  klin.  Wochnschrft.,  1910,  XXIII,  963,  1820. 

^  This  article  also  contains  a  good  discussion  and  bibliography  of  the  sub- 
ject.    Journ.  Med.  Research,  XXXVIII,  3,  July,   1918. 


LIGHT— OCULAR  HYGIENE  921 

rule  is  that  there  should  be  enough  diffused  light  from  illumined  walls 
and  ceiling  so  that  all  parts  of  the  room  can  be  clearly  seen.  To  this 
add  directed  light  at  the  poiiils  of  interest — the  work  table,  piano,  or 
book  page. 

Good  artificial  lighting  is  not  a  question  of  the  kind  of  illumination, 
but  of  how  the  illuminant  is  used.  Oil,  gas,  and  electricity  produce  satis- 
factory lighting,  hut  each  can  be  abused.  Neither  ordinary  daylight  nor 
ordinary  sources  of  artificial  light  contain  radiations  which  are  injurious 
to  the  healthy  eye.  Electric  lighting  is  clean  and  does  not  vitiate  the 
air,  and  is  therefore  hygienically  superior  to  gas  or  oil. 

Proper  lighting  has  a  direct  bearing  on  the  economic  running  of  a 
factory,"  and  also  on  the  efficiency  of  the  men  and  the  safety  of  the 
workpeople.  The  light  must  be  directed  onto  the  work  in  such  a  way 
that  the  greatest  intensity  will  be  where  it  is  wanted.  Under  no  con- 
ditions must  the  source  of  the  light  fall  directly  in  the  eyes  nor  should 
there  be  any  surfaces  which  will  reflect  a  strong  light  into  the  eyes  of 
ihe  workmen.  Flickering  lights  should  always  be  avoided.  Good 
illumination  can  only  be  prescribed  where  the  uses  to  which  the  light  is 
to  be  put  are  known.     See  also  pages  1335-1342. 

Method  for  Measuring  Xllumination. — The  amount  of  illumination 
IS  measured  by  candle  meters  or  candle  feet;  that  is,  the  illumination 
afforded  by  a  standard  candle  at  a  distance  of  one  meter  or  one  foot. 
Shaw  ^^  believes  that  the  illumination  should  provide  at  least  50  candle 
meters  in  the  most  unfavorable  part  of  the  room.  The  maximum 
hygienic  value  for  illuminants  has  been  found  to  be  about  2^  candles 
for  each  square  inch  of  illuminated  surface. 

The  method  which  is  recommended  as  a  standard  procedure  depends 
on  the  use  of  photosensitive  paper,  such  as  can  be  obtained  from  any 
dealer  in  photographic  materials.  By  exposing  the  sensitized  paper 
through  a  slot  in  a  cardboard  for  a  sufficient  period  of  time,  and  noting 
the  number  of  seconds  or  minutes  consumed  to  match  in  depth  a  stand- 
ard shade  or  color,  the  intensity  of  light  can  be  determined  with  ac- 
curacy. If  a  fresh  piece  of  paper  is  exposed  to  the  direct  rays  of  the 
sun  for  three  seconds  it  will  assume  a  shade  which  can  be  used  as  a 
standard  for  a  given  series  of  tests.  The  intensity  of  light  at  other  points 
may  be  compared  with  this  by  noting  the  number  of  seconds  required  to 
color  a  fresh  piece  of  paper  from  the  same  lot  to  the  same  shade. 

This  method  is  inferior  to  photometers,  several  patterns  of  which 
are  in  use.  It  is  not  sufficient  for  the  purposes  of  ocular  hygiene  to 
know  the  intensity  of  the  light  at  any  particular  point.  We  must 
know  the  color  and  the  amount  of  light  that  enters  the  eye;  this  amount 

"  Code  of  Lighting  for  Factories,  Mills  and  Other  Work  Places.     Welfare 
Work  Series,  No.  3,  Adv.  Com.,  Com.  on  Labor.  Conn.  Nat.  Defense,  Jan.,  1918. 
"Shaw,  E.  R.:     "School  Hygiene."     The  Macmillan  Co.,  N.  Y.,  1902. 


922  MISCELLANEOUS 

is  governed  by  the  size  of  the  pupil,  which  in  turn  is  governed  by  the 
direction  of  the  light,  and  many  other  factors.  There  is  therefore  no 
single  method  for  testing  illumination  with  reference  to  ocular  hygiene. 

Errors  of  Refraction. — Myopia  or  near-sightedness  is  an  error  of  re- 
fraction in  which  the  eyeball  is  too  long  and  rays  of  light  coming  from 
a  distance  are  brought  to  a  focus  in  front  of  the  retina.  Myopia  of 
moderate  degree  is  usually  not  progressive  and  therefore  not  a  serious 
condition,  but  progressive  (malignant)  myopia  is  a  frequent  cause  of 
partial  or  complete  blindness.  Myopia  commonly  develops  about  thie 
eighth  or  tenth  year,  and  is  usually  due  to  hereditary  influence.  Pro- 
longed near  work  of  all  kinds  is  believed  to  favor  its  development.  It 
is  also  believed  that  the  full  correction  of  myopia  by  glasses  may  check 
its  progress.  The  eyes  may  apparently  tolerate  years  of  abuse,  but  by 
middle  life  the  unfortunates  may  be  forced  to  be  sparing  of  their  use 
at  a  time  when  physical  limitations  curtail  the  enjoyment  of  outdoor 
life.  When  there  is  a  tendency  towards  myopia,  parents  and  those  en- 
gaged in  the  education  of  the  young  should  realize  the  dangers  of  ex- 
cessive reading  and  the  prolonged  use  of  the  eyes  in  all  kinds  of  fine 
near  work. 

Hypermetropia  or  far-sightedness  is  a  condition  in  which  parallel 
rays  of  light  are  brought  io  a  focus  behind  the  retina.  Under  such 
conditions  clear  vision  is  possible  only  when  this  defect  is  counteracted 
by  contraction  of  the  ciliary  muscle,  which  shortens  the  eye  focus.  This 
constant  and  unnatural  demand  upon  the  ciliary  muscle  sooner  or  later 
results  in  fatigue,  and  may  cause  reflex  symptoms  such  as  headache, 
nervousness,  or  hyperemia  of  the  conjunctiva  or  eyelids.  It  may  also 
cause  strabismus  or  other  muscular  errors. 

Astigmatism  is  an  error  of  refraction  caused  by  an  irregularity  in 
curvature  in  one  of  the  refracting  surfaces,  usually  the  cornea.  It 
may  cause  great  impairment  of  vision.  Children  supposed  to  be  "back- 
ward" at  school  often  may  be  greatly  improved  by  correcting  astig- 
matism, or  other  errors  of  refraction. 

Presbyopia  is  the  loss  of  the  power  of  accommodation  due  to  ad- 
vancing years,  caused  by  an  increasing  hardness  of  the  crystalline  lens. 
It  usually  makes  itself  manifest  between  40  and  50  years,  and  increases 
until  55  or  60  years  of  age. 

Color  blindness  was  first  accurately  described  in  1774  by  Dalton, 
an  English  chemist,  who  himself  was  color  blind.  Color  blindness  may 
be  partial  or  total,  congenital  or  acquired.  To  those  who  are  totally 
color  blind,  the  world  appears  as  though  it  were  tinted  with  different 
shades  of  gray.  In  normal  color  perception,  six  colors  are  seen  in  the 
spectrum:  red,  orange,  yellow,  green,  blue,  and  violet.  Even  in  normal 
cases,  with  a  diminution  in  the  intensity  of  light,  the  orange,  blue  and 
yellow  may  be  missed.     Those  who  see  only  three  colors — red,  green 


LIGHT— OCULAR  HYGIENE  923 

and  violet — are  markedly  color  hliiid;  those  who  see  only  two  colors — 
yellow  and  hlue — are  especially  dangerous,  because  they  cannot  dis- 
tinguish red  from  green. 

Total  color  blindness  is  rare,  but  congenital  partial  color  defect  is 
common,  occurring  in  about  4  per  cent,  of  all  males,  but  only  in  about 
0.2  per  cent,  of  females.  The  percentage  is  higher  among  Quakers, 
Color  blindness  of  a  degree  dangerous  in  occupations  requiring  recog- 
nition of  colored  signal  lights,  occurs  in  about  3.1  per  cent,  of  men  and 
in  about  0.7  per  cent,  of  women.  In  total  color  blindness,  consanguinity 
in  the  parents  has  been  traced  in  12.5  per  cent,  of  the  cases.  The  con- 
dition is  usually  inherited  (page  650).  The  most  common  cause  of 
acquired  color  blindness  is  the  immoderate  use  of  tobacco  and  alcohol 
(page  !t4). 

The  occupations  in  which  the  color  sense  is  important  are:  All 
naval  and  marine  officers,  pilots  and  certain  classes  of  seamen,  loco- 
motive engineers,  and  all  occupations  in  the  arts  requiring  mixing  pig- 
ments or  matching  colors. 

The  Holmgren  test  consists  in  matching  various  colors  from  a  con- 
fused mass  of  skeins  of  colored  yarns.  The  three  chief  test  colors  are 
pale  green,  light  pink  and  bright  red.  The  Jennings  self-recording 
worsted  test  is  an  improved  modification  of  this  skein  test,  but  results 
in  the  rejection  of  a  large  percentage  of  subjects  who  should  be  accepted 
for  sailors  or  trainmen,  and  it  therefore  should  be  supplemented  with 
the  Eldridge-Green,  or  the  Williams  lantern  test." 

Eye  Strain. — Any  decided  derangement  in  the  build  of  the  eyes  or 
in  the  proper  balance  of  the  ocular  muscles  may  exert  a  profound  influ- 
ence upon  the  general  system.  It  is  rare  that  these  reflex  symptoms 
arise  in  other  than  workers  who  employ  many  hours  daily  in  close  use 
of  the  eyes.  The  most  common  symptom  caused  by  eye  strain  is  head- 
ache. The  eyes  themselves  may  present  nothing  abnormal  in  the  way 
of  congestion.  Other  symptoms  are  print  blurring,  restricted  distant 
vision,  occasional  double  vision,  in  fine,  those  symptoms  usually  described 
under  the  term  asthenopia.  There  may  be  digestive  disturbances,  ver- 
tigo, car  sickness,  choreic  twitchings,  faulty  positions  and  spasmodic 
movements  of  the  head,  and  a  great  variety  of  other  manifestations. 
The  prevention  of  eye  strain  requires  proper  correction  of  refraction, 
care  to  secure  the  right  kind  of  illumination,  and  in  some  cas&s  by 
systematical  resting  of  the  eyes. 

Care  of  the  Eyes. — Short  periods  of  rest  should  interrupt  all  kinds 
of  close  work,  during  which  the  eyes  should  be  directed  on  distant 
objects.  This  relaxes  the  muscles  of  accommodation.  Reading  in  a 
recumbent  posture  should  be  avoided,  and  reading  should  never  be  per- 
sisted in  when  drowsy  or  physically  tired.    Books  printed  in  very  small 

"Collins,  G.  L.:     "Color  Blindness."     U.  S.  P.  H.  Bull.  'So.  93,  1918. 


924  MISCELLANEOUS 

type  or  on  poor  paper  should  be  avoided  (page  1343).     Automobiling 
and  moving  pictures  are  somewhat  harmful  to  the  eyes. 

If  the  eyes  feel  hot  and  uncomfortable  after  exposure  to  irritants  or 
undue  strain,  they  may  be  washed  with  a  saturated  solution  of  boric 
acid.  Bathing  the  closed  lids  with  either  very  warm  or  cold  water  is 
refreshing  and  beneficial. 

After  measles  and  other  fevers  the  softening  and  congestion  of  the 
ocular  tissues  requires  a  long  period  during  which  the  eyes  should  be 
used  but  little  at  close  work.  The  health  of  the  eyes  is  dependent  in 
large  measure  upon  the  health  of  the  body.  ' 

Children  should  be  taught  as  early  as  possible  never  to  gaze  long 
upon  any  near  object  brightly  illuminated.  ISTote  must  be  taken  of  the 
harmful  practice  of  riding  babies  in  coaches  with  the  full  glare  of  the 
sun  directly  upon  their  faces.  Children  should  be  protected  from  all 
toys  and  articles  with  sharp  edges  or  points  which  can  injure  the  eyes. 
Workpeople  also  require  protection' against  flying  particles  (page  94). 
When  twilight  supervenes,  artificial  lights  should  go  on,  unless  the 
parent  wisely  utilizes  this  witching  hour  with  amusement  or  instruction 
that  rests  the  eyes. 

For  the  purposes  of  ocular  hygiene  the  direction,  source,  power 
and  color  of  artificial  illumination  are  all  important.  The  amount  of 
illumination  should  not  be  judged  by  the  brightness  of  the  lamps, 
but  by  the  amount  of  light  at  the  place  it  is  needed.  This  varies;  thus 
more  light  is  needed  for  sewing  on  black  cloth  than  on  white  cloth. 
The  light  should  be  steady.  A  flickering  light  tires  the  muscles  that 
govern  accommodation  and  leads  to  fatigue  and  pain.  Eeading  in  rail- 
way trains  causes  similar  strain :  the  eye  muscles  tire  of  trying  to  follow 
the  shaking  page.  It  is  contrary  to  the  principles  of  ocular  hygiene 
to  face  a  glaring  light,  especially  when  reading,  writing,  or  any  other 
work  requiring  close  application.  Even  though  the  light  may  come 
from  above,  glaring  reflections  from  polished  metal  or  brass,  from 
brightly  varnished  surfaces,  or  even  from  glossy  white  paper  may  be  very 
trying  because  a  bright  light  from  below  falls  on  the  part  of  the  retina 
which  commonly  gets  light  only  from  grass  or  dark  surfaces.  For  the 
same  reason  glare  from  snow  and  sand  is  not  only  disagreeable  on  ac- 
count of  its  intensity,  but  because  of  the  unusual  direction  from  which 
it  comes. 

Vision  should  be  tested  by  competent  persons  at  regular  intervals — 
frequently,  during  the  period  of  growth  and  again  at  the  presbyopic 
age,  40  to  60  years.     See  also  pages  1334  and  1342. 

The  eyes  are  a  more  frequent  portal  of  entry  to  infections  than 
we  have  suspected.  The  conjunctivae  communicate,  through  the  lach- 
rymal ducts  with  the  nose,  and  there  is  a  constant  flow  of  tear  secretion 
in  this  direction.     Microorganisms  introduced  into  the  conjunctival  sac 


RADIO-ACTIVITY  925 

may  be  isolated  from  the  nose  in  five  minutes,  from  the  throat  in  fifteen 
minutes,  and  from  the  stool  in  twonty-four  hours."  Thus,  diphtheria, 
common  colds,  influenza,  pneumonia,  and  other  respiratory  infections 
and  even  intestinal  diseases  may  be  contracted.  Face  masks  that  do 
not  protect  the  eyes  are  therefore  inadequate.^® 


ELECTRICITY 

The  question  of  electricity  is  also  a  question  of  vibrations,  not  of 
the  air,  but  of  ether,  and  one  shrouded  in  much  obscurity.  The 
electric  potential  of  the  air  varies  considerably.  It  is  highest  in 
winter  and  lowest  in  summer,  and  shows  diurnal  variations.  It  is  in- 
creased by  winds  and  is  especially  increased  by  the  condensation  of 
vapor.     It  also  increases  as  we  ascend. 

It  is  assumed  that  electric  changes  in  the  air  and  in  other  objects 
surrounding  us  exercise  an  influence  on  health  and  vitality,  but  the  in- 
fluence is  obscure  and  mainly  a  matter  of  conjecture. 


RADIO-ACTIVITY 

Soon  after  the  discovery  of  radium  by  the  Curies  it  was  proved, 
chiefly  through  the  investigations  of  Elster  and  Geitel,  that  the  air 
and  soil  and  certain  mineral  springs  contained  radio-active  substances. 
Newly  fallen  rain  and  snow  are  also  radio-active.  Air  drawn  from 
the  soil  by  means  of  a  pipe,  or  air  shut  up  in  underground  cellars  and 
caverns,  is  especially  radio-active,  as  is  also  the  air  on  mountain  tops. 
The  air  in  clear  weather  has  greater  radio-activity  than  in  dull  weather. 

Certainly  radio-active  substances  have  important  physiological,  physi- 
cal, and  chemical  effects.  They  ionize  the  air,  rendering  it  a  conductor 
of  electricity;  they  cause  a  fluorescence  of  certain  chemical  substances; 
they  produce  a  sensation  of  light  if  they  strike  the  eye;  applied  to  the 
body  in  sufficient  "dosage,"  radium,  a,  )3,  7  and  X-rays  cause,  de- 
struction of  tissue,  changes  in  the  blood,  and  general  constitutional 
symptoms.  Local  destruction  of  tissue  is  not  speciflc,  except  perhaps 
for  lymphoid  structures,  as  in  Hodgkin's  disease.  See  Ultraviolet  Rays, 
page  918. 

"  Maxcy,  K.  F. :  The  Transmission  of  Infection  Through  the  Eye.  J.  A.  M. 
A.,  Mar.  1,  1919,  Vol.  LXXII,  No.  9,  p.  636.  Posey,  A.  C:  "Hygiene  of  the  Eye." 
J.  P.  Lippincott  Co.,  1918. 

^Conservation  of  Vision  Pamphlets,  I  to  XX,  published  by  the  American 
Medical  Association.  A  series  of  popular  articles  oh  the  care  and  preservation 
of  good  eyesight,  prepared  by  the  Committee  on  Conservation  of  Vision  and 
issued  by  ithe  Council  on  Health  and  Public  Instruction. 


926 


MISCELLANEOUS 


SMOKE 

Smoke  is  a  product  of  combustion  and  consists  of  a  mixture  of 
gases  containing  solid  particles/''  Ordinary  smoke  consists  largely 
of  unburned  carbon  particles,  hydrocarbons,  and  other  pyroligneous 
products;  gases,  some  of  them  poisonous,  such  as  carbon  monoxid;  also 
mineral  acids,  etc.  Angus  Smith  give  the  following  analysis  of  smoke 
from  a  common  house  fire: 

Smoke  from  a  common  house  fire 


Gas  from  chimney  4  feet  above  the 
fireplace 

Gas  from  the  middle  of  a  good  fire. 
A  great  mass  of  coal  over  the  fire, 
the  gas  taken  from  below  the  glow- 
ing mass 

A  heap  of  glowing  coal,  gas  taken  close 
to  spot  where  carbonic  oxid  was 
burning 

Gas  from  clear  fire  below 

Gas  from  the  same  fire  at  upper  part, 
1  inch  below  the  surface 


Carbon 
Dioxid 


0.35 
1.65 


19.46 
20.90 
17.50 

17.44 


15.43 
18.17 


16.10 
17.21 
18.20 


Carbon 
Monoxid 


0.38 


0.09 
0.10 


3.49 

2.48 


0.99 


Oxygen 


16.93 
19.29 


0.60 
0.39 


0.96 


4.95 
4.25 


Nitrogen 


80.02 
78.68 


80.45 
79.00 
80.04 
82.17 


80.12 
79.35 


78.95 
78.54 
78.21 


Dr.  Cohen  of  the  Manchester  Air  Analysis  Committee  gives  the 
following  analysis  of  soot  collected  from  the  roofs  of  glass  houses  in 
Kew  and  Chelsea: 


Carbon 

Hydrocarbons 

Organic  bases   (pyridine,  etc.) 

Sulphuric  acid 

Hydrochloric  acid 

Ammonia 

Metallic  iron  and  magnetic  oxid  of  iron 

Mineral  matter   (chiefly  silica  and  ferric  oxid) 
Water  not  determined   (say  difi'erence) 


Chelsea 

Kew 

Per  Cent. 

Per  Cent. 

39.0 

42.5 

12.3 

4.8 

2.0 

4.3 

4.0 

1.4 

0.8 

1.4 

1.1 

2.6 

31.2 

41.5 

5.8 

5.3 

Large  manufacturing  chimneys  are  the  chief  offenders.  There  are 
two  main  causes  of  smoky  chimneys:  (1)  insufficient  boiler  capacity, 
and  (2)  improper  stoking.  The  cure  of  the  smoke  nuisance  consists 
in  the  installation  of  boilers  of  sufficient  power  so  that  they  need  not 

**  Smoke  consists  largely  of  solid  particles  suspended  in  the  air;  fog,  of 
liquid  particles. 


SMOKE  927 

be  forced,  ami  llic  use  of  mechanical  stokers.  The  electrification  of 
railroads  aiul  the  more  general  use  of  electric  power  generated  from 
water  pressure  help  materially  to  lessen  the  amount  of  smoke  in 
cities. 

The  London  County  Council  permits  black  smoke  for  five  minutes 
after  the  lighting  of  furnaces.  Other  towns  allow  as  much  as  15  min- 
utes. jMost  laws  distinguish  between  black  smoke  and  white  smoke, 
although  the  one  is  about  as  pernicious  as  the  other. 

In  Boston  the  density  of  the  smoke  is  graded  into  four  classes,  in 
accordance  with  Ringelmann's  chart.  This  is  a  rather  complicated 
system,  depending  upon  the  character  of  the  stack,  the  density  of  the 
smoke,  and  the  time,  as  shown  in  Fig.  95.^° 

The  amount  of  smoke  in  some  manufacturing  centers  is  almost  in- 
credible. Dr.  W.  N.  Shaw  estimates  that  London  gives  to  the  atmos- 
phere every  day  about  7,000,000  tons  of  smoky  air  containing  over  400 
tons  of  soot,  and  he  calculates  that  smoke  deprives  London  of  about  one- 
sixth  its  possible  sunlight  and  daylight  in  summer  and  about  one-half 
its  possible  sunlight  and  daylight  in  winter. 

The  injurious  eifect  of  smoke  on  health  has  perhaps  been  overesti- 
mated. It  acts  directly  and  indirectly.  Directly  it  irritates  the  mucous 
membranes  of  the  upper  respiratory  passages,  and  Asher  and  also 
Eubner  believe  that  it  increases  the  mortality  from  acute  pulmonary 
diseases.  They  state  that  smoke  and  soot  predispose  to  acute  pulmonary 
tuberculosis.  Indirectly  smoke  is  a  source  of  dirt  and  general  nuisance 
and  leads  to  depression  of  the  spirits.  It  shuts  out  the  light,  soils 
with  soot,  and  deters  the  opening  of  windows  in  order  to  let  in  fresh 
air.  The  presence  of  mineral  acids  in  the  air  has  a  corrosive  influence 
upon  inorganic  substances,  and  doubtless  acts  injuriously  upon  plant 
and  animal  life.  The  economic  losses  from  the  soiling  action  of  soot 
are  enormous.  Even  if  it  were  not  injurious  to  healthy  smoke  is  so  evi- 
dent a  nuisance  that  communities  are  justified  in  every  effort  to  check 
and  prevent  this  growing  abomination. 

Klotz  -^  characterizes  pulmonary  anthracosis  as  a  community  disease. 
He  found  as  much  as  1.2  to  5.3  grams  of  carbon  in  the  lungs  of  per- 
sons living  in  Pittsburgh,  while  only  0.14  and  0.4  gram  in  the  lungs  of 
two  residents  in  Ann  Arbor,  Mich.  Anthracosis  then  affects  city  dwell- 
ers in  proportion  to  the  amount  of  smoke  in  the  air.  The  amount  of 
carbon  in  the  lungs  is  dependent  upon  the  amount  inhaled.  Carbon  in 
the  lungs  causes  a  loss  of  elasticity  of  the  tissue;  structural  changes, 
especially  fibrosis,  about  the  anthracotic  deposits;  the  air  spaces  are 
encroached  upon,  resulting  in  compensatory  emphysema.     When  anthra- 

^°  For  construction  of  Ringelmann's  smoke  chart  and  methods  of  taking  smoke 
readings:     Smoke  Investigation  Bulletin  No.  8,  p.   191,  Mellon  Institute. 
^^Amer.  Jour,  Public  Health,  1914,  IV,  p.  887. 


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928 


DUST  n?9 

cosis  is  well  marked  it  seriously  impairs  the  function  of  tiie  lungs. 
Pleural  adhesions  do  not  develop  as  a  result  of  the  deposit  (page  i)31). 
Smoke  polluted  with  poisonous  chemical  vapors  may  be  quite  serious. 
Thus,  hydrogen  sul])hid,  found  in  large  quantities  in  the  smoke  gener- 
ated in  sulphate  of  ammonia  and. tar  works  and  from  alkali  wastes,  is 
a  poisonous  gas.  The  arsenical  vapors  given  off  chiefly  from  lead  and 
copper  smelters  kill  vegetation  for  wide  areas  around. 


FOG 

Fogs  are  caused  by  the  condensation  of  water  vapor  on  particles 
of  dust.  Dust  particles  have  a  varying  capacity  for  condensing  and  at- 
tracting moisture,  depending  upon  their  power  of  radiating  heat  and  on 
their  affinity  for  water.  Carbon  dust  is  hygroscopic  and,  therefore,  en- 
courages fogs.  The  ammonia  and  sulphuric  acid  in  smoky  air  also 
occasion  and  aggravate  fog.  The  air  of  manufacturing  cities,  therefore, 
possesses  all  the  elements  to  form  a  fine  persistent  fog  which  forms 
a  "chemical  pall"  between  the  city  and  the  sky. 

The  more  carbon  a  fog  contains  the  blacker  it  is.  The  general  re- 
sult of  a  fog  is  to  shut  out  sunlight  and  fresh  air  and  to  "partially 
suffocate  unfortunate  citizens  in  clouds  of  noxious  chemicals."  F02 
contains  all  the  irritating  properties  of  smoke  in  a  concentrated  form, 
and  it  also  in  a  measure  prevents  the  escape  of  the  city-made  carbon 
dioxid.  The  CO2  in  the  city  air  during  a  fog  may  rise  to  10  parts  per 
10,000.  If  smoke  is  bad  fog  is  ten  times  worse.  It  has  been  shown 
that  during  city  fogs  sickness  increases  and  the  death  rate  rises.  From 
the  economic  standpoint  fog  causes  greater  financial  losses  than  smoke. 
Russell  calculates  the  annual  loss  to  the  people  of  London  from  fog  to 
total  about  $9,000,000  a  3'ear.  The  main  items  in  this  loss  consist  in 
extra  washing,  including  extra  soap,  the  damage  to  dresses,  curtains, 
carpets,  and  textile  fabrics,  the  replacing  of  wall-papers,  and  the  paint- 
ing of  houses,  the  restoring  of  gilt  and  metal  work,  the  slow  destruction 
of  granite,  marble,  and  stonework  of  buildings,  the  extra  cost  of  arti- 
ficial illumination,  etc.  This  estimate  does  not  include  the  losses  re- 
sulting from  its  action  on  health. 


DUST 

Dust  is  not  only  a  nuisance,  but  under  certain  conditions  is  known 
to  be  prejudicial  to  health.  Dust  is  in  reality  a  normal  and  very  im- 
portant constituent  of  the  air;  it  exists  everywhere  in  the  atmosphere 
and  profoundly  affects  some  of  the  physical  conditions  of  our  environ- 


930  MISCELLANEOUS 

ment.  One  of  the  most  important  functions  of  dust  is  to  limit  the 
humidity  of  the  air  by  causing  the  precipitation  of  moisture  in  the  form 
of  rain,  and  to  help  control  temperature  by  the  formation  of  clouds, 
mists,  and  fogs.  Aitken,  who  has  made  a  special  study  of  this  subject, 
says  that  without  dust  "every  blade  of  grass  and  every  branch  of  tree 
would  drip  with  moisture  deposited  by  the  passing  air;  our  dresses 
would  become  wet  and  dripping,  and  umbrellas  useless ;  but  our  miseries 
would  not  end  here.  The  insides  of  our  houses  would  become  wet; 
the  walls  and  every  object  in  the  room  would  run  with  moisture." 
Without  dust  there  would  be  no  rain,  no  clouds,  no  mist,  for  the  water 
vapor  which  condenses  upon  each  particle  of  dust  forms  the  nucleus 
of  a  raindrop. 

Dust  disperses  the  light  and  decreases  the  transparency  of  the  at- 
mosphere, especially  if  the  atmosphere  be  also  humid.  What  is  known 
as  haze  is  really  dust  carrying  a  minute  amount  of  moisture. 

Although  dust  particles  are  universally  present  in  the  known  at- 
mosphere, they  are  very  irregularly  distributed.  Organic  dust  exists 
only  in  the  lower  strata,  while  inorganic  particles  are  found  wherever 
the  air  has  been  examined.  Ordinarily  there  is  more  dust  indoors  than 
in  outdoor  air.  The  size  of  the  dust  particles  varies  enormously,  from 
gross  masses  to  microscopic  and  ultramicroscopic  particles.  The  vast 
numbers  and  universal  presence  of  these  particles  may  be  realized  by 
examining  a  sunbeam.  Air  free  of  dust  is  an  artificial  product  obtained 
only  with  special  care  in  small  amounts  in  the  laboratory. 

Most  of  the  dust  is  torn  from  the  earth  by  the  winds;  much  of  it 
comes  from  the  carbon  and  other  particles  in  smoke;  considerable 
amounts  consist  of  minute  grains  of  salt  derived  from  sea  spray;  and 
great  quantities  are  added  by  volcanoes.  Finally,  the  air  contains  in- 
terplanetary particles  which  fall  through  it  in  a  constant  shower. 

The  spectrum  shows  the  bands  of  sodium  everywhere  in  the  atmos- 
phere. This  is  lifted  into  the  air  by  the  wind  from  the  sea  spray. 
The  water  evaporates,  leaving  the  salt  particles  to  float  about  at  the 
will  of  the  wind. 

Organic  dust  consists  of  the  dry  and  disintegrated  particles  which 
are  blown  into  the  air  from  the  animal  and  plant  kingdoms.  They 
consist  of  epithelial  scales,  seed,  spores,  bacteria,  pollen,  plant  cells, 
fluff  of  various  kinds,  bits  of  insects,  starch,  pus  cells,  algae,  rotifers, 
fragments  of  hair,  feathers,  and  bits  of  tissue,  fibers  of  cotton,  etc. 

The  inorganic  dust,  which  is  derived  mostly  from  the  soil,  from 
the  sea,  and  from  interplanetary  space,  consists  chiefly  of  silica,  alumin- 
ium silicate,  calcium  carbonate,  calcium  phosphate,  magnesia,  iron  oxid, 
sodium  chloride  etc. 

Modern  cities  are  dust  producers.  Whipple  found  the  number  of 
dust  particles  visible  with  a  magnification  of  100  diameters,  at  the  air 


DUST  !»:n 

inlets  of  some  of  the  commercial  buildings  in  Boston,  as  cloterniined  by 
microscopical  counts,  to  ran<je  from  100,000  to  nearly  1,000,000  per 
cubic  foot. 

The  number  of  particles  vary  from  one  per  cubic  centimeter  on 
mountain  tops  on  exceptionally  clear  days  to  millions  per  cubic  centimeter 
in  ordinary  indoor  air.  ('oiisidi-riiii^  only  particles  of  hy<.,n('nic  im- 
portance, nnnu'ly.  iliosc  liaxiiii;-  a  diniuctcr  of  ii.nodj  s(|iiari'  niiiliinctcr 
or  over,  recent  analyses  sliow  1)00  particles  per  liter,  or  0.11  f^am  per 
million  liters  of  country  air  on  a  clear  day.  At  the  other  extreme,  760 
grams  per  liter  or  24,000,(iO<)  ])arti(lcs  per  liter,  have  been  found  in  the 
air  of  an  abrasive  factory. 

The  number  of  dust  particles  in  a  room  is  inversely  proportioned 
to  the  amount  of  fresh  air  supplied.  Ordinary  air  washers  remove 
from  20  per  cent,  to  70  per  cent,  of  the  dust. 

Dust  particles  may  be  carried  enormous  distances  by  the  winds. 
Ehrenberg  detected  organisms  belonging  to  Africa  in  the  air  of  Ber- 
lin; and  fragments  of  infusoria  belonging  to  the  plains  of  America 
in  the  air  of  Portugal.  The  smoke  of  the  burning  of  Chicago  reached 
to  the  Pacific  coast.  The  volcanic  dust  of  Krakatoa,  consisting  chiefly 
of  glassy  pumice,  was  found  for  years  in  our  atmosphere,  and  it  is 
assumed  that  some  of  it  may  have  traveled  several  times  around  the 
world.  Macfie  has  seen  in  the  Canary  Island's  clouds  of  dust  sufficient 
to  obscure  the  sun,  though  the  dust  had  come  all  the  way  from  the 
African  mainland.  All  of  us  living  on  the  Atlantic  seaboard  have 
seen  the  yellow  days  caused  by  forest  fires  several  thousands  of  miles 
away. 

Dust  and  Disease. — "Normal"  atmospheric  dust,  free  from  bacteria, 
causes  no  appreciable  irritation  to  the  healthy  respiratory  mucous  mem- 
branes. Dust  becomes  injurious  when  excessive  in  amount  or  when  irri- 
tating in  character,  or  when  it  contains  injurious  microorganisms;  the 
injury  also  depends  upon  the  constancy  of  its  presence  and  somewhat 
upon  the  susceptibility  of  the  individual. 

Dust  may  act  indirectly  as  a  predisposing  cause  of  many  infections, 
as  well  as  directly  irritating  and  inflaming  the  respiratory  passages. 
The  statement  that  dust  opens  the  door  to  tuberculosis  and  other  infec- 
tions of  the  air  passages,  such  as  common  colds,  influenza,  pneumonia, 
etc.,  can  no  longer  be  questioned.  We  must  first  limit  ourselves  to  a 
consideration  of  the  effect  of  dust  free  of  noxious  bacteria;  in  the  next 
section  we  will  discuss  the  question  of  bacteria  in  the  air. 

The  general  effect  of  mineral  dust  breathed  for  a  long  period  of  time 
is  to  cause  an  irritation  of  the  mucous  membranes  and  an  inflammatory 
condition  of  the  lung  tissue.  The  term  pneumonohoniosis  is  a  general 
name  for  affections  of  this  kind.  The  term  is  modified  according  to 
the  various  kinds  of  dust.     Thus,  anthracosis  is  caused  by  coal  dust; 


933  MISCELLANEOUS 

siderosis  by  iron  or  steel  dust;  silicosis  or  chalicosis  by  stone  dust; 
hyssinosis  by  cotton  particles  or  vegetable  fiber  dust. 

In  certain  cases  the  dust  is  retained  as  deposits  in  the  lungs  and 
neighboring  lymph  glands  without  further  damage.  The  lungs  and 
bronchial  glands  of  all  adults  are  more  or  less  discolored  from  particles, 
which  are  constantly  inhaled.  The  particles  are  taken  up  by  the  phago- 
cytes and  deposited  in  the  lymphatic  spaces  of  the  lung  or  carried  to  the 
neighboring  lymph  glands,  where  they  are  enmeshed.  Under  certain 
circumstances  the  dust  irritates  the  delicate  structures  and  leads  to  in- 
fections and  destruction  of  tissue.  Thus,  we  hear  of  stone  mason's 
phthisis,  steel  grinder's  phthisis,  and  potter's  rot.  It  is  not  always  easy 
to  distinguish  between  the  fibrosis  resulting  from  tuberculosis  and 
pneumonokoniosis,  except  by  repeated  sputum  examinations,  some- 
times extending  over  a  number  of  years.^^  Among  the  dusty  trades 
may  be  mentioned  pottery  and  earthenware  manufacture,  cutlery  and 
file-making,  certain  departments  of  glass-making,  copper,  iron,  lead, 
and  steel  manufacturing,  stone-cutting,  chimney-sweeping,  textile  trades, 
etc.  Oliver  ("Disease  of  Occupation")  examined  the  atmosphere  in 
which  the  brushers-ofi",  the  finishers,  and  the  porcelain-makers  generally 
work,  and  found  it  to  contain  640  million  particles  of  dust  per  cubic 
meter  of  air,  while  several  of  the  finishers,  i.  e.,  the  persons  whose  work 
consists  in  removing  the  excess  of  the  dried  glaze  on  the  ware,  are 
often  breathing  an  atmosphere  containing  680  million  particles  of  dust 
to  the  cubic  meter.  It  is  little  wonder  that  bronchitis  and  phthisis  are 
common.^^ 

Winslow  and  Kligler  ^*  report  an  average  of  49,200,000  microbes 
per  gram  in  New  York  street  dust,  and  between  3,000,000  and  5,000,000 
per  gram  in  indoor  dust.  Street  dust  includes  the  colon  bacilli  and  acid- 
forming  streptococci. 

Dust  consisting  of  inorganic  particles  is  more  harmful  than  dust 

consisting  of  organic  particles,  because  the  former  are  sharper  and  more 

irritating.     House  dust  is  more  harmful  than  outside  dust,  not  only 

because  there  is  more  of  it,  especially  in  badly  ventilated  and  ill-kept 

rooms,  but  because  it  is  more  apt  to  contain  living  pathogenic  bacteria. 

House  dust  may  be  kept  down  by  cleanliness  and  avoidance  of  dry  dusting 

and  sweeping;  by  the  use  of  vacuum  cleaning;  and  by  free  ventilation. 

Much  house  dust  is  blown  in  from  the  outside,  and  some  of  it  comes 

in  on  dirty  shoes.     In  buildings  ventilated  with  a  mechanical  system 

the  air  may  be  filtered  through  bags  or  passed  through  a  water  curtain, 

which  will  eliminate  much  dust.     Oiling  floors  with  a  wax  or  paraffin 

mixture  helps  to  keep  down  indoor  dust.     Carpets  tacked  down  are 

'"Journal  Ind.  Hyg.,  July,  1919,  1,  No.  3,  p.  366. 

^'  For  a  discussion  of  the  dusty  trades,  see  chapter  on  Industrial  Hygiene. 
Anthracosis  is  considertd  on  page  927. 

^^Am.  Jour.  -Public  Health,  1912,  II,  663. 


DUST  933 

sanitary  abominations  and  slioul<l  be  replaci'd  witb  ni^rs  that  permit 
outdoor  cleaning  and  sunnin'r. 

Street  dust  contains  coal  dust,  metallic  dust  from  the  operation  of 
trolley  cars,  material  swept  from  houses  and  from  shaking  rugs  from 
windows,  the  grinding  up  of  roadbeds  by  vehicles,  ashes,  and  other  ma- 
terials blown  from  barrels  and  teams;  the  bacteria  are  derived  from 
dried  fecal  matter  from  horses  and  other  animals,  dried  sputum,  the 
soil,  and  a  variety  of  other  sources.  Street  dust  may  contain  pathogenic 
organisms,  such  as  the  tubercle  bacillus,  many  varieties  of  cocci,  the 
colon  bacillus,  Bacillus  aerogenes  capsulatus,  and  possibly,  under  spe- 
cial conditions,  tetanus,  malignant  edema,  and  occasionally  other  path- 
ogenic microorganisms.  Street  dust,  therefore,  becomes  more  than  a 
nuisance,  for  it  is  not  only  irritating,  but  may  be  a  source  of  infection. 

To  keep  down  street  dust  requires,  first  of  all,  a  well-constructed 
road  with  a  good  surface,  oiled  or  properly  cared  for;  the  control  of 
animals;  the  covering  of  ash  barrels  and  carts  hauling  dusty  loads; 
the  use  of  automobile  vacuum  cleaners  to  replace  the  old  or  the  pres- 
ent-day methods  of  dry  sweeping.  Attention  must  also  be  given  to 
spitting  on  sidewalks  and  streets,  the  enforcement  of  smoke  ordinances, 
the  more  extensive  flushing  of  streets,  and  general  attention  to  cleanli- 
ness. 

When  dust  is  violently  stirred  up  by  dry  sweeping  or  beating 
carpets,  or  still  more  by  a  March  wind  in  a  dry,  dirty  street,  the  quan- 
tity inhaled  with  attached  microorganisms  has  a  real  sanitary  sig- 
nificance. 

The  pollen  of  certain  plants  flying  in  the  air  as  dust  leads  to  hay 
fever  in  susceptible  individuals.^''.     See  Anaphylaxis,  page  593. 

Methods  for  Examining^  Dust. — Impaciion  Methods. — The  air  is 
forcibly  blown  against  surfaces  specially  prepared  with  sticky  substances, 
such  as  gum  acacia,  glycerin,  silicate  of  soda  or  resin,  held  by  porcelain 
or  glass  plates,  glass  tubes  or  paper.  The  dust  may  be  allowed  to  settle 
upon  a  Petri  dish.  Particles  are  then  examined  under  the  microscope  or 
weighed.  The  well  known  effect  of  dust  upon  a  photographic  plate  can 
be  used  to  register  the  number  and  size  of  the  larger  particles. 

Electrostatic    Method. — The     electrostatic     precipitation     of     dust 

^°  For  data  in  regard  to  the  influence  of  dust  upon  disease,  see:  .Gohoe, 
B.  A.:  The  Relation  of  Atmospheric  Smoke  and  Health.  Bull.  Xo.  9,  Smoke 
Investigation,  Mellon  Inst,  of  Indus.  Research  and  Sch.  of  Spec.  Ind.,  Pittsburgh, 
1914.  p.  7.  Haythorn,  S.  R.:  Some  Histological  Evidences  of  the  Disease  Im- 
portance of  Pulmonary  Antliracosis,  Jour.  Med.  Research.  1913,  XXIX,  259. 
HoflFman,  F.  L. :  The  Mortality  from  Consumption  in  Dustv  Trades.  Bull.  Xo. 
79,  U.  S.  Bureau  of  Labor,  Xov.,  1909,  p.  63.3.  Klotz.  0.:  Pulmonary  Anthra- 
cosis,  a  Community  Disease.  Am.  Jour.  Pub.  Health,  1914,  IV,  887.  White, 
W.  C,  and  Shuey,  P.:  The  Influence  of  Smoke  on  Acute  and  Chronic  Lung 
Infections.  Trans.  Am.  Climatol.  Assn.,  1913;  also  Bull.  Xo.  9.  Smoke  Investi- 
gation, Mellon  Inst,  of  Indus.  Research  and  Sch.  of  Spec.  Ind.,  Pittsburgh,  1913, 
164. 


934 


MISCELLANEOUS 


particles  depends  upon  the  ionization  of  finely  divided  substances  in  an 
electric  field.  This  method  is  based  upon  the  laws  of  electrically 
charged  bodies,  and  has  recently  been  applied  commercially  to  the 
recovery  of  valuable  dusts.  Its  use  for  the  sanitary  analysis  of  air  was 
studied  by  Bill.^e 

Filtration  Methods. — Dust  may  be  collected  from  the  air  by  pass- 
ing it  through  cotton,  sugar,  extraction  thimbles,  resorcinol,  fine  mesh 

wire,  cloth,  water,  filter  paper, 
collodion,  wool,  cheese  cloth, 
canton  flannel,  etc. 

The  Palmer  Water  Spray 
Apparatus,^''  as  worked  out  by 
Palmer,  Coleman  and  Ward, 
is  the  most  generally  useful 
method;  it  is  as  follows:  In 
air  not  visibly  very  dusty  200 
to  400  cubic  feet  of  air  should 
be  passed  through  the  washer, 
while  in  more  dusty  air  100 
to  200  cubic  feet  will  suffice. 
About  40  c.  c.  of  distilled 
water  is  placed  in  the  trap 
and  about  once  in  five  or  ten 
minutes  (depending  on  the 
temperature  and  humidity  of 
the  atmosphere)  water  is 
added  to  make  up  the  loss 
from  evaporation.  After  the 
run  is  completed  the  water 
with  its  suspended  dust  is 
drained  into  a  bottle,  the  bulb  is  rinsed  several  times  with  distilled 
water,  and  the  original  water  plus  the  washings  are  made  up  to  100 
c.  c.  One  c.  c.  of  this  suspension  after  thorough  shaking  is  trans- 
ferred to  a  Sedgwick-Eafter  cell  and  five  fields,  at  the  center  and  four 
corners,  counted  under  a  two-thirds  inch  objective.  Where  both  light 
and  heavy  dusts  are  present  this  procedure  must  be  repeated  for  the  top 
and  the  bottom  of  the  cell.  A  second  c.  c.  is  then  placed  in  the  cell  and 
counted  in  the  same  way.  The  dust  particles  may  conveniently  be 
grouped  in  five  classes,  according  to  size,  as  follows : 

1.  Large  masses  about  100  standard  units  (.04  sq.  mm.). 

2.  About  25  standard  units  (.01  sq.  mm.). 

3.  About  1  standard  unit   (.0004  sq.  mm.). 

"'Journ.  Ind.  Hyg.,  I,  7,  Nov.,  1919,  p.  323. 

'"Am.  Journ.  Public  Health,  Jan.,   1916,  VI,  p.  54. 


Fig.   96. — The   Palmer   Water-Spray   Ap- 
paratus  FOR  THE   COLLECTIOX    OF  AeRIAL 

Dust. 

New   York   State   Commission   on   Venti- 
lation. 


DUST  935 

4.  About  J  standard  unit  (.0001  sq.  mm.). 

5.  Du.^it  too  fine  to  cuunl, — presence  indicateil  by  a  plus  pif?n. 

A  control  count  sbould  always  be  made  using  tlie  same  slide  and 
the  same  batch  of  distilled  walci-;  .ind  the  average  of  tlic  fwe  field 
counts  obtained  subtracted  frniu  the  a\'erage  ol"  tiie  ten  field  counts 
of  the  suspension  of  dust. 

The  renuiinder  of  the  suspension  should  be  filtered  through  a 
weighed  Gooch  crucible,  the  crucible  and  contents  dried  for  one  hour  at 
approximately  100°  C.  and  weighed  to  0.1  mg. 

Condensation  Methods. — Condensation  methods  depend  upon  the 
condensation  of  water  vapor  al)out  dust  particles  in  a  rarefied  atmos- 
phere. 

The  koniscope,  inveiited  by  Professor  John  Aitken,  consists  of  two 
brass  tubes  connected  at  right  angles  and  suitably  fitted  with  stopcocks 
and  a  small  air  pump.  By  exhausting  the  air  from  one  of  the  tubes, 
allowing  the  space  to  become  saturated  with  water  ^■apo^  by  evaporation 
from  ^vet  blotting  paper  within,  and  then  allowing  this  moisture  to 
condense  upon  the  dusty  atmosphere  under  examination,  clouds  of 
different  degrees  of  density  will  form  inside  the  tube.  The  approximate 
density  of  the  clouds  can  be  measured  by  looking  through  the  tubes, 
windows  being  provided  for  this  purpose.  A  table  is  supplied  with 
the  instrument  to  give  the  approximate  number  of  dust  particles  cor- 
responding to  clouds  of  different  degrees  of  density.  This  method  has 
limited  usefulness,  because  it  makes  apparent  exceedingly  minute  par- 
ticles that  have  little  sanitary  significance. 

All  the  methods  for  examining  dust  in  the  air  are  faulty  in  one 
or  more  respects;  none  of  them  accounts  for  all  the  dust. 


CHAPTER  IV 
BACTERIA  AND  POISONOUS  GASES  IN  THE  AIR 

BACTERIA  IN  THE  AIR 

The  number  of  bacteria  in  the  air  ordinarily  has  a  direct  relation 
to  the  amount  of  dust;  in  fact,  many  of  the  bacteria  in  the  air  are 
attached  to  dust  particles.  Bacteria  in  the  air  are  commonly  consid- 
ered as  one  kind  of  dust,  but  on  account  of  their  significahce  they  are 
given  separate  consideration. 

Bacteria  are  not  found  everywhere  in  the  air;  uninhabited  places 
are  quite  free;  and  the  number  diminishes  as  we  ascend. 

Bacteria  do  not  multiply  in  the  air;  in  fact,  most  of  them  soon 
die,  especially  when  exposed  in  dry  air  to  sunshine.  For  the  most  part, 
the  bacteria  in  the  air  belong  to  the  harmless  varieties,  although  the 
number  and  kind  vary  greatly  with  circumstances.  They  come  chiefly 
from  the  soil  and  are  carried  into  the  air  by  the  wind  and  traffic  move- 
ments; that  is,  bacteria  in  the  air  are  derived  from  practically  the  same 
sources  as  dust.  The  dangerous  bacteria  in  the  air,  however,  come 
directly  or  indirectly  from  man  and  some  of  the  lower  animals. 

The  number  of  bacteria  differs  greatly  with  the  local  conditions. 
There  are  more  in  the  air  of  towns  than  in  the  open  country;  few 
in  high  mountains,  desert  places,  or  at  sea;  more  in  windy  weather 
than  calm  air;  more  indoors  than  in  outside  air;  more  in  dry  air  than 
in  moist  air;  more  before  than  after  rain.  The  air  of  badly  ventilated 
rooms,  especially  if  not  kept  clean,  contains  very  many  bacteria,  and 
more  when  occupied,  as  the  movements  of  the  occupants  stir  up  the 
dust. 

Miquel  of  the  Observatory  of  Montsouris  studied  the  number  of 
bacteria  in  the  air  of  various  localities.  He  found  about  150  per  cubic 
foot  in  the  air  of  Paris,  but  only  6  after  rain;  on  the  top  of  the  Pan- 
theon he  found  l^;  in  the  streets  about  13  per  cubic  foot;  in  a  neg- 
lected hospital  3,170;  in  a  gram  of  laboratory  dust  75,000  and  in  a 
gram  of  house  dust  2,100,000. 

Fliigge  considers  that  on  the  average  there  are  about  one  hundred 
microorganisms  to  a  cubic  meter  of  city  air^ — an  average  evidently  be- 
low that  of  Paris. 

Dr.  Jean  Binot  did  not  find  a  single  bacterium  in  100  liters  of 

936 


BACTERIA  IN  THE  ATR  937 

outside  air  taken  at  the  suimuit  of  Muiit  JiJanc;  and  lie  found  a  pro- 
gressive decrease  in  the  number  as  the  height  increased.  Thus,  he 
found : 

At  Montanvert    49 

At  the  Mer  de  Glace 23 

At  the  Place  de  rAlguille  14 

At  the  Grand  Mn]ot   8 

At  the  Grand  Plateau    6 

On  the  summit  0 

Again,  Graham  Smith  found  at  the  top  of  the  Clock  Tower  of  the 
Houses  of  Parliament  in  London  only  one-third  of  the  number  at 
ground  level. 

Whipple  found  1,330  bacteria  per  cubic  feet  in  the  air,  at  the  street 
level,  while  at  the  tenth  story  of  the  John  Hancock  building  in  Boston 
the  air  contained  330. 

Speaking  broadly,  from  two  to  three  hundred  times  as  many  par- 
ticles of  dust  as  bacteria  are  found  in  the  outside  air  of  cities, 

Haldane  found  256  bacteria  per  cubic  foot  of  air  in  an  unventilated 
room  compared  to  practically  none  in  a  ventilated  room. 

Pasteur,  in  experiments  that  will  ever  remain  classic,  exposed  or- 
ganic infusions  in  flasks  to  the  air  of  various  places,  and  used  the  re- 
sults thus  obtained  to  prove  the  presence  or  absence  of  bacteria  in  the 
air  and  to  dispel  the  illusion  of  spontaneous  generation.  Of  20  such 
flasks  exposed  to  the  air  of  the  Mer  de  Glace  19  showed  no  contamina- 
tion. About  the  same  time  (1875)  Tyndall  exposed  27  flasks  contain- 
ing an  infusion  to  the  air  of  the  Aletsch  glacier  (8,000  feet)  ;  none 
showed  putrefaction,  while  90  per  cent,  of  the  flasks  opened  in  a 
hayloft  were  "smitten." 

It  is  estimated  that  a  person  living  in  London  breathes  about  300,- 
000  microbes  in  the  inspired  air  each  day.  Winslow  and  Brown  ^  ex- 
amined 1,037  samples  of  air,  both  indoors  and  outdoors,  with  counts 
varying  from  two  to  5,200  per  cubit  foot. 

The  expired  air,  during  normal  respirations,  is  practically  bacteria- 
free,  no  matter  how  many  may  be  contained  in  the  inspired  air.  The 
moist  mucous  membranes  of  the  upper  respiratory  passages  act  as  a 
bacterial  trap.  When  the  expired  air  contains  bacteria  it  is  only  as  a 
result  of  coughing,  sneezing,  talking,  or  other  forced  expiratory  efforts 
(see  Droplet  Infection). 

The  number  of  bacteria  in  the  air  is  seldom  a  factor  of  sanitary 
significance,  except  under  special  circumstances,  such  as  dairy  conditions 
or  studies  in  droplet  infection. 

The  harmful  bacteria  in  the  air  and  the  danger  of  contracting  dis- 
ease through  air-borne  infection  are  considered  below, 

"^  Monthly  Weather  Rev.,  1914,  XLII,  452, 


938     BACTEEIA  AND  POISONOUS  GASES  IN  THE  AIE 


Fig.  97. — Magnus  Aspi 

RATOR. 


Method  for  Detennining  Bacteria  in  the  Air. — A  rough  idea  of  the 
bacterial  population  of  the  air  may  be  obtained  by  exposing  suitable 
culture  media  in  Petri  plates  for  various  periods  of  time,  and  counting 
the  colonies  which  develop  from  the  germs  falling  upon  them. 

A  large  number  of  different  devices  have 
been  described  for  a  more  accurate  determina- 
tion of  the  number  of  bacteria  in  the  air.  These 
are  all  adaptations  of  the  three  general  methods : 
(1)  filtration  of  air;  (2)  bubbling  air  through 
some  liquid  medium;  (3)  precipitating  the 
bacteria  from  a  given  volume  of  air.  Each  of 
these  methods  can  be  made  to  give  fairly  satis- 
factory results  in  the  hands  of  competent  work- 
ers, but  the  Committee  of  the  Amerifcan  Public 
Health  Association  recommend  the  following 
method  of  Petri- on  account  of  its  simplicity  and 
general  applicability : 

Filtration  Method  of  Petri.— The  filter  tubes 
are  glass  tubes  1^  cm.  in  diameter  and  10  cm. 
long.  In  the  end  of  each  is  placed  a  per- 
forated cork  stopper,  through  which  a  glass  tube  6  mm.  in  diameter  is 
passed.  The  filtering  material  consists  of  sand  which  has  been  passed 
through  a  100-mesh  sieve.  The  sand  in  the  filter  tube  is  1  cm.  deep  and 
supported  by  a  layer  of  bolting  cloth  covering  the  cork.  Two  filter  tubes 
are  connected  in  tandem,  and  a  measured  volume 
of  air,  10  liters  or  more,  is  drawn  through  at  a 
constant  rate  by  suction.  The  suction  is  applied 
by  means  of  an  aspirator  of  known  volume,  prefer- 
ably one  of  the  double  or  continuous  type.  Either 
the  Magnus  aspirator  (Fig.  97)  or  the  double 
aspirator  (Fig.  98)  are  suitable  for  this  purpose. 
Before  using  a  pair  of  filter  tubes  a  test  for  pos- 
sible leakage  is  made  by  placing  the  thumb  over  the 
cotton  stopper  and  applying  the  aspirator;  if  the 
suction  is  weak  or  absent  the  corks  must  be  tightened 
or  the  tubes  discarded.  All  corks  should  be  tightened 
and  connections  wired  and  the  apparatus  sterilized 
before  using  the  filters.  The  collection  of  the  sample 
should  take  from  1  to  2  minutes  per  liter. 

After  filtering  a  definite  volume  through  the 
tubes  the  sand  is  poured  into  10  c.  c.  of  sterile  water,  thoroughly  shaken, 
and  aliquot  portions  plated  in  ordinary  nutrient  agar,  all  plates  being 
made  in  duplicate.  The  plates  are  incubated  at  room  temperature  for 
five  days,  when  final  counts  are  made. 


Fig.    98. — Double 
Aspirator. 


BACTERIA  IN  THE  AIR  939 

Reltger's  Method. — An  ini])r()ve(l  method  of  onumerating  air 
bacteria  lias  been  de>Jcribe(l  l)y  Rettger,-  which  coninu'iid.s  itself  as  the 
best  method  yet  devised.  The  method  consists  of  bubbling  a  given 
quantity  of  air  through  salt  solution.  The  bacteria  in  the  air  are  trapped 
in  the  salt  solution,  which  may  then  be  planted  in  the  usual  way  and 
tJie  number  of  colonies  counted. 

Air  and  Infection. — The  air  was  long  regarded  as  the  vehicle  and 
even  the  source  of  the  communicable  diseases.  Theories,  such  as  nox- 
ious effluvia,  poisonous  emanations,  and  infectious  miasms,  gave  way 
with  the  advent  of  bacteriology.  When  the  early  classical  researches 
of  Pasteur,  Tyndall,  and  others  showed  that  bacteria  exist  in  the  air 
almost  everywhere  in  greater  or  in  lesser  numbers,  the  conclusion  was 
jumped  at  that  the  air  must  be  particularly  dangerous.  Within  recent 
years,  however,  we  have  learned  that  the  air  is  not  very  much  to  be 
feared  on  account  of  the  bacteria  it  may  carry,  except  under  occa- 
sional circumstances.  This  change  in  our  views  during  recent  times 
is  nowhere  better  illustrated  than  in  the  relation  of  the  air  to  surgery. 
During  the  early  days  of  antiseptic  surgery  so  much  fear  was  enter- 
tained for  the  bacteria  in  the  air  that  Lister  attempted  to  neutralize 
the  danger  with  carbolic  sprays  and  other  means;  now  the  surgeon 
pays  little  heed  to  the  air  of  a  well-kept  operating  room.  Instead  he 
ties  several  layers  of  sterile  gauze  over  his  mouth  and  nostrils  and  over 
his  head  to  guard  against  particles  falling  from  these  sources. 

It  was  one  of  the  great  surprises  when  bacteriologists  demonstrated 
that  the  expired  breath  under  normal  conditions  of  respiration  is 
sterile. 

At  one  time  many,  if  not  most,  of  the  contagious  diseases  were 
believed  to  be  air-borne;  many  observations  are  on  record  purporting 
to  prove  that  contagium  may  be  carried  long  distances  through  the 
air.  With  the  increase  of  our  knowledge  concerning  the  modes  of  trans- 
mission of  infection  the  list  of  air -borne  diseases  has  steadily  dwindled. 
The  theory  is  reluctantly  given  up,  for  it  is  the  easiest  method  of  ex- 
plaining the  spread  of  the  readily  communicable  diseases.  There  are 
only  two  diseases  of  man,  viz.,  smallpox  and  measles,  which  may  pos- 
sibly be  air-borne,  in  the  sense  that  this  term  is  generally  used.  Both 
these  diseases  are  so  readily  communicable  that  the  virus  seems  to  be 
"volatile";  it  is  assumed  that  the  active  principle  is  contained  in  the 
expired  breath;  however,  there  is  no  proof  of  this  assumption,  and  some 
evidence  to  the  contrary.  Further,  it  is  noteworthy  that  we  are  still 
ignorant  of  the  causes  and  the  precise  mode  of  entrance  of  the  con- 
tagium in  both  measles  and  smallpox.  Even  in  these  two  diseases  the 
radius  of  danger  is  much  more  limited  than  was  once  supposed  to  be 
the  case. 

'Jour,  of  Med.  Res.,  June,  1910,  XXII,  3,  pp.  461-468. 


940     BACTERIA  AND  POISONOUS  GASES  IN  THE  ATE 

The  more  the  transmission  of  the  communicable  diseases  is  studied 
the  less  the  air  is  implicated.  The  fact  that  malaria  (bad  air),  yellow 
fever,  and  other  diseases  are  conveyed  by  mosquitoes  has  robbed  the  air 
itself  of  false  accusations,  and  given  a  death  blow  to  miasms,  effluvia, 
and  intangible  theories,  Pettenkoffer  insisted  that  the  air  became  con- 
taminated with  poisons  that  were  generated  in  a  polluted  soil,  and  he 
believed  that  these  emanations  were  responsible  in  part  for  typhoid  fever 
and  cholera.  Some  association  between  soil,  air,  and  disease  still  per- 
sists in  both  medical  and  lay  minds,  but  with  a  more  precise  knowledge 
of  the  causes  and  modes  of  transmission  of  infections,  such  as  typhoid 
fever  and  cholera,  the  air  becomes  a  negligible  factor.  Out-of-door  air 
contains  relatively  few  bacteria ;  further,  the  dilution  is  enormous.  Most 
microorganisms  pathogenic  for  man  soon  die  when  dried  or  when  ex- 
posed to  sunlight.  Whatever  danger,  then,  resides  in  the  air,  so  far  as 
living  principles  of  disease  are  concerned,  is  found  rather  in  indoor 
air,  and  especially  in  the  air  of  badly .  ventilated,  dusty,  and  crowded 
places.  Here  the  danger  may  be  either  from  the  bacteria-laden  dust  or 
from  droplet  infection.  In  a  crowded  and  stuffy  street  car,  in  a  poorly 
ventilated  office,  or  in  a  closed,  close  sickroom  it  would  be  very  easy 
for  the  microorganisms  of  diphtheria,  scarlet  fever,  whooping-cough, 
measles,  pneumonia,  influenza,  common  colds,  tuberculosis,  pneumonic 
form  of  plague,  and  other  infections  contained  in  the  secretions  from 
the  nose  and  mouth  to  be  held  in  the  air  in  sufficient  numbers  so  that 
exposed  persons  may  contract  the  disease.  This  probably  occurs  more 
frequently  than  we  are  at  present  inclined  to  admit. 

The  radius  of  danger  through  droplet  infection  is  quite  limited. 
It  is  difficult  to  conceive  that  infection  may  be  carried  long  distances 
in  the  air  and  still  be  dangerous.  My  own  experience  indicates  that 
there  is  practically  no  hazard  in  establishing  a  hospital  for  contagious 
diseases  upon  the  high  road  or  even  in  a  thickly  inhabited  part  of  the 
city.  In  fact,  the  communicable  diseases  are  not  conveyed  in  the  air 
from  ward  to  ward  or  even  from  bed  to  bed  in  well-managed  hospitals. 

Hutchinson  found  that  prodigiosus  bacilli  in  sputum  droplets  may 
be  carried  almost  2,000  feet  when  the  temperature  is  low.  It  therefore 
seems  probable  that  diphtheria  bacilli  would  persist  longer  and  carry 
farther  in  droplet  infection  in  cold  weather  than  in  warm  weather. 
This  explanation  has  been  given  to  account  for  the  seasonal  prevalence 
of  plague,  diphtheria,  etc.  The  two  chief  ways  in  which  bacteria  are 
transferred  through  the  air  are  (1)  by  droplet  infection,  and  (2)  by 
dust.     Mouth  spray  is  really  a  form  of  contact  infection. 

Chapin  states  that  many  contagious  hospitals  have  been  maintained 
for  years  with  no  increase  of  the  disease  in  the  vicinity,  as,  for  instance, 
at  Boston  and  Providence,  E.  I.  At.  the  Kingston  Avenue  Hospital 
in  Brooklyn  various  diseases,,  as  smallpox,  measles,  scarlet  fever,  and 


POISONOUS  GASES  IN  THE  AIR  941 

diphtheria,  are  treated  in  wards  only  a  few  feet  apart,  with  no  evidence 
of  aerial  transference.  At  North  Brother's  Island  the  tuberculosis 
ward  is  only  about  25  feet  from  the  diplitheria  ward,  but  the  tubercu- 
lous patients  do  not  contract  diphtheria.  A  number  of  hospitals  for 
communicable  diseases  have  recently  been  built  with  entire  disregard 
of  aerial  infection.  At  the  li()s])ital  of  the  Pasteur  Institute,  Paris, 
the  patients  are  cared  for  each  in  a  separate  ward  opening  into  a  com- 
mon hall.  The  same  nurses  go  from  case  to  case.  In  2i/^  years  after 
it  was  opened  in  1900  there  Avere  treated  2,000  persons,  of  whom  524 
had  smallpox,  443  diphtheria,  12G  measles,  163  erysipelas,  92  scarlet 
fever,  and  16G  non-diphtheritic  sore  throat.  The  only  evidence  of  the 
transfer  of  infection  was  the  development  of  four  cases  of  smallpox  and 
two  of  erysipelas.  In  the  Hopital  des  Infants  Malades  in  Paris  the 
beds,  instead  of  being  in  separate  rooms,  are  separated  by  partitions. 
Of  5,017  cases  there  were  only  7  cross  infections,  G  of  measles  and  1 
of  diphtheria.  » These  were  attributed  to  lapses  in  aseptic  precautions. 
Dr.  Moizard  thinks  that  this  experience  proves  that  even  measles  is  not 
air-borne.  Dr.  Grancher  in  another  Paris  hospital  has  two  wards  in 
which  there  are  no  partitions,  but  only  wire  screens  around  the  beds, 
simply  as  a  reminder  for  the  nurses.  He  also  insists  that  measles  is 
probably  not  an  air-borne  disease,  and  that  adjacent  patients  do  not 
necessarily  infect  one  another.  At  various  English  hospitals  similar 
methods  have  been  tried  with  success.^ 

While  the  air  plays  a  minor  role  in  the  spread  of  the  infections, 
bad  air  plays  an  important  part  in  reducing  vitality  and  predisposing 
to  disease.    This  will  be  discussed  presently. 


POISONOUS  GASES  IN  THE  AIR 

Some  of  the  poisonous  gases  of  the  air  come  from  natural  sources, 
as  marshes,  mines,  or  decomposing  organic  matter,  but  those  that  con- 
cern the  sanitarian  particularly  are  the  gases  which  arise  from  the 
works  of  man.  These  gases  are  carbon  monoxid,  ammoniacal  vapors, 
hydrochloric  acid,  carbon  bisulphid,  carbureted  hydrogen,  hydrogen 
sulphid,  etc. 

Carbon  Monoxid. — Carbon  monoxid  (CO)  is  a  frequent  and  serious 
cause  of  acute  poisoning  and  also  of  chronic  ill  health.  It  has  become 
one  of  the  commonest  forms  of  gas  poisoning.  Deaths  from  carbon 
monoxid  in  large  cities  now  exceed  those  from  any  other  poison.*  It 
is  usually  found  associated  with  other  gases,  especially  from  the  incom- 

'Chapin:     Jour.  Am.  Med.  Asm.,  Dec.  12,  1908,  Vol.  LI,  pp.  2048-2051. 

••The  total  number  of  cases  of  gas  poisoning  in  Cook  County,  Illinois,  for 
1916  was  501, — nearly  8  per  cent,  of  the  entire  number  of  coroner's  cases.  (J.  A. 
M.  A.,  July  27,  1918,  p.  257.) 


942     BACTERIA  AND  POISONOUS  GASES  IN  THE  AIR 

plete  combustion  of  coal  or  wood.  It  is  also  one  of  the  ingredients 
of  illuminating  gas,  and  is  one  of  the  constituents  of  the  gases  of  coal 
mines.  Burning  charcoal  gives  CO  in  great  abundance,  and  it  is  also 
given  off  from  red  hot  cast-iron  stoves;  further,  it  is  found  about  lime 
kilns  and  where  open  coke  fires  and  braziers  are  used  in  confined  spaces ; 
also  from  iron  and  copper  furnaces,  the  exhaust  of  gas  engines  and  from 
many  manufacturing  processes. 

The  gases  from  stoves  or  furnaces  contain  79.7  per  cent,  nitrogen, 
10  to  13  per  cent,  oxygen,  0.6  per  cent.  CO2,  and  0.3  to  0.5  per  cent. 
CO  when  formed  by  the  incomplete  combustion  of  wood  or  coal  in  closed 
spaces,  that  is,  with  the  damper  closed.  Illuminating  gas  from  coal 
contains  from  6  to  10  per  cent.  CO;  from  wood  62  per  cent.;  water  gas, 
30  per  cent,  and  more.  Gases  in  coal  mines  contain  from  4  to  10  per 
cent.  CO,  from  0.6  to  1  per  cent.  HgS,  and  53  per  cent.  COg.  Gases 
from  smokeless  powder  and  gun  cotton  contain  high  quantities  of  CO 
and  are  quite  dangerous. 

For  public  health  purposes  the  chief  sources  of  CO  are  leaky  gas 
fixtures,  open  coal  fires,  the  premature  closing  of  dampers  of  stoves  and 
furnaces,  or  defects  in  apparatus  burning  coal,  spent  gases  from  auto- 
mobiles and  explosives  in  technical  pursuits. 

Air  containing  0.4  per  cent,  .of  carbon  monoxid  may,  in  one  hour, 
prove  fatal.  In  higher  concentration  a  person  may  be  overcome  at  once 
and  death  soon  ensues.  Kinnicutt  ^  states  that  breathing  an  atmos- 
phere containing  0.3  per  cent,  of  carbon  monoxid,  for  any  considerable 
period,  is  fatal,  and  the  presence  of  0.2  per  cent,  is  capable  of  destroy- 
ing life  (Haldane).  Grehant  found  that  inhalation  of  an  atmosphere 
containing  1  part  of  CO  to  275  parts  of  air  was  fatal  to  a  dog,  and  that 
1  in  70  killed  a  rabbit.  Less  than  a  gram  of  CO  may  kill  a  man. 
Breathing  an  atmosphere  containing  0.05  per  cent,  of  CO  may  cause 
unpleasant,  even  serious  symptoms  (Oliver).  Even  as  little  as  0.07  to 
0.12  per  cent  for  half  an  hour  will  render  one  quarter  of  the  red  cor- 
puscles incapable  of  uniting  with  the  oxygen.  Chronic  poisoning  with 
smaller  amounts  may  lead  to  anemia,  depression,  psychoneuroses,  and 
other  symptoms. 

A  chiM  having  relatively  large  respiratory  exchange  for  its  size  is 
overcome  more  quickly  than  an  adult.  On  this  account,  small  animals, 
such  as  birds  and  mice,  are  overcome  more  quickly  than  men.  Canaries 
are  always  carried  by  the  rescue  crews  of  the  Bureau  of  Mines  when 
carbon  monoxid  is  suspected. 

Carbon  monoxid  or  carbonic  oxid  is  a  colorless,  tasteless  and  prac- 
tically odorless  gas;  it  burns  with  a  pale  blue  flame.  Its  poisonous  ac- 
tion depends  upon  the  fact  that  it  combines  with  the  hemoglobin  of  the 
red    blood    corpuscles    to    form   carbon-monoxid-hemoglobin.      This    is 

Wour.  Am.  Cliem.  Boo.,  1900,  Vol.  XXII,  p.  14. 


POISONOUS  GASES  TX  TTTE  ATT?  943 

a  stable  compound  which,  therefore,  prevents  the  hemoglobin  giving 
up  its  oxygen  to  the  tissues.  When  present  in  only  small  amounts  and 
for  long  periods  of  time,  the  effects  of  CO  may  be  compensated  for  by 
a  polycythemia — an  increased  number  of  corpuscles  taking  the  place  of 
those  disa))led.  It  is  commonly  stated  that  CO  has  a  direct  destructive 
action  upon  the  cells  of  the  central  nervous  system,  causing  paralysis  in 
acute  cases  and  psychoneuroses  in  chronic  cases.  Yandell  Henderson, 
however,  denies  any  direct  action  because  tissue  cultures  will  grow  in 
vitro  in  a  concentrated  atmosphere  of  CO. 

The  symptoms  depend  upon  the  presence  of  CO  in  the  air  breathed, 
the  rapidity  of  breathing,  the  presence  of  other  gases,  and  the  age 
of  the  individual.  The  quantity  of  CO  present  in  the  air  is  of  more 
importance  than  the  length  of  exposure  to  it. 

Acute  Poisoning. — The  individual  feels  dizzy  and  complains  of 
headache,  noises  in  the  ears,  throbbing  in  the  temples,  and  the  feeling 
of  sleepiness  and  sense  of  fatigue.  There  may  be  vomiting  and  a  sense 
of  oppression  at  the  chest,  palpitation,  and  an  inability  to  stand  or  walk 
straight.  Convulsions  may  or  may  not  come  on;  pupils  are  dilated  and 
react  slowly  to  light ;  the  face  is  red ;  consciousness  is  gradually  lost, 
but  owing  to  the  great  loss  of  motor  power  the  individual,  though  aware 
of  the  danger,  is  often  unable  to  escape  from  it.  In  animals  the  heart 
beat  at  first  is  slow,  while  the  blood  pressure  is  high;  in  man  the  action 
of  the  heart  is  frequently  violent  even  during  the  stupor.  When  a  man 
has  recovered  from  the  acute  effects  of  carbon  monoxid  his  life  is  still 
imperiled  for  some  days  to  come.  He  runs  the  risk  of  dying  as  late 
as  8  days  after  the  accident  and  then  he  has  still  to  face  the  risk  of  gly- 
cosuria, or  other  serious  sequelae. 

When  a  person  is  removed  from  the  poisonous  atmosphere  there  is 
slow  return  to  consciousness,  but  headache,  nausea  and  weakness  per- 
sist for  a  long  time.  In  case  of  continued  inhalation  of  the  poison 
there  is  a  marked  dilatation  of  the  peripheral  vessels,  causing  extensive 
red  spots  on  the  skin. 

Death  occurs  from  paralysis  of  the  respiratory  apparatus.  If  a  case 
does  not  terminate  fatally,  there  may  be  serious  sequelae,  such  as 
apoplexy  followed  by  softening  of  the  brain,  or  blisters,  decubitus,  or 
paralysis  may  develop,  also  chorea,  idiocy,  or  minor  grades  of  psy- 
choneurosis. 

The  post-mortem  appearance,  following  acute  intoxication  with  car- 
bon monoxid,  shows  the  following:  Features  placid,  face  and  skin  bright 
ruddy  color,  both  arterial  and  venous  blood  bright  cherry  red,  and  show- 
ing the  spectrum  of  carbon-monoxid-hemoglobin.  The  muscles,  brain,  and 
all  organs  are  more  pink  than  usual.  Lungs  may  be  emphysematous, 
and  red  patches  may  be  observed  on  the  surface  of  the  abdominal  vis- 
cera; occasional  submucous  hemorrhages  in  the  stomach  and  intestines. 


944     BACTERIA  AND  POISONOUS  GASES  IN  THE  AIE 

Tests. — The  presence  of  carbon  monoxid  in  air  may  be  determined 
with  considerable  accuracy  with  a  solution  of  blood.  A  few  cubic  centi- 
meters of  normal  blood  solution  are  shaken  to  saturation  with  the  sample 
of  air.  A  dilute  blood  solution  is  yellow;  it  becomes  pink  when  treated 
with  traces  of  carbon  monoxid.  By  comparing  the  color  with  carmin 
this  method  will  serve  for  quantitative  purposes.®  More  accurate  de- 
terminations may  be  made  by  the  iodin  pentoxid  method  of  Seidell.'^ 

Illuminating  G-as. — Illuminating  gas  may  be  harmful  either  from  the 
products  of  its  combustion  or,  more  so,  when  the  unconsumed  gas  escapes 
in  the  household.  The  two  principal  illuminating  gases  used  are  coal 
gas  and  water  gas.  The  poisonous  effects  of  both  are  due  mainly  to 
the  carbon  monoxid  which  they  contain. 

Coal  gas  is  made  by  the  destructive  distillation  of  coal.  It  contains 
hydrogen,  marsh  gas,  and  carbon  monoxid,  occasionally  also  ethene, 
acetylene,  and  carbon  dioxid.  A  cubic  foot  of  coal  gas  completely  burned 
gives  to  the  atmosphere  about  one-half  a  cubic  foot  of  CO,  and  about 
1.34  cubic  feet  of  water  vapor.  An  ordinary  gas  jet  burns  about  6  cubic 
feet  of  gas  per  hour,  and  thus  produces  about  3  cubic  feet  of  CO,. 

Water  gas  is  made  by  blowing  a  current  of  steam  through  incan- 
descent coke  or  coal.  The  water  is  decomposed  into  hydrogen  and 
oxygen.  The  hydrogen  passes  on  and  the  oxygen  unites  with  the  carbon 
to  form  carbon  monoxid.  Water  gas  so  produced  burns  only  with  a 
pale  blue  flame.  It  is,  therefore,  enriched  in  a  carburetor  with  vapor- 
ized petroleum;  this  furnishes  the  hydrocarbons  necessary  to  give  a 
luminous  flame.  Water  gas  contains  about  30  per  cent,  of  carbon 
monoxid. 

One  of  the  most  common  sources  of  carbon  monoxid  ^  in  the  house- 
hold is  from  illuminating  gas.  Illuminating  gas  may  pass  from  a 
broken  gas  main  through  the  soil  into  the  cellar  and  thence  permeate 
a  dwelling;  this  is  aided  by  the  suction  and  pumping  action  of  the 
heating  apparatus  in  the  cellar.  In  passing  through  the  soil  illuminat- 
ing gas  may  be  robbed  of  its  characteristic  odor,  thus  rendering  it  so 
much  more  dangerous  because  not  perceived.  The  danger  from  this 
source  is  further  increased  in  the  winter  time  and  in  cities  with  as- 
phaltum  and  concrete  pavements,  because  under  these  circumstances  the 
escape  of  gas  into  the  air  is  hindered  and  the  chance  of  more  of  it 
reaching  the  house  through  the  cellar  is  favored.     An  occasional  source 

*  For  methods  for  determining  carbon  monoxid  and  other  gases  in  the  air, 
see:  Haldane,  J.  S. :  "Methods  of  Air  Analysis,"  J.  P.  Lippincott  and  Co., 
1912.  Dennis:  "Gas  Analysis,"  New  York,  1913.  Melzel,  A.:  "Ueber  den 
Nachweis  des  Kohlenoxydhiimoglobins,"  Verhandlungen  der  PhysiKaL-Med. 
Gesellschaft  zu  Wiirzburg.  Neue  Folge.  Vol.  23,  p.  47.  Miiller,  F. :  "Bio- 
logische  Gasanalyse."  Handbuch  der  Biochemischen  Arbeitsmethodep.  Ill,  2. 
Berlin,  1910. 

''Jour.  Ind.  and  Eng.  Chem.,  VI,  321, 

'  See  also  page  1308, 


POISONOUS  GASES  IN  THE  AIE 


945 


of  CO  in  the  air  of  houses  is  throu^^h  hot-water  heaters,  using  illuminat- 
ing gas  as  fuel.  The  soot  gradually  collects  in  these  devices  and  may 
become  incandescent,  thus  furnishing  ideal  conditions  for  the  produc- 
tion of  carbon  monoxid.  In  the  arts  CO  is  formed  by  passing  water 
vapor  over  incandescent  carbon.  I  know  of  one  case  in  Washington 
where  CO  from  a  water  heater  collected  in  a  kitchenette  in  such  con- 
centration that  three  persons  were  overcome  upon  entering  the  room 
and  died. 

Most  coal  contains  sulphur,  which  appears  in  coal  gas  as  sulphuric 
acid,  which  is  irritating  and  poisonous.  Most  of  the  sulphur  compounds 
in  coal  gas  are  removed  by  processes  of  purification  during  manufac- 
ture, but,  owing  to  the  difficulty  of  complete  removal,  20  grains  of  sul- 
phur in  every  hundred  cubic  feet  are  generally  allowed  by  law.  The 
sulphur  restrictions  have  recently,  but  unwisely,  been  removed  in  Eng- 
land. In  Massachusetts  the  legal  limit  has  been  raised  to  30  grains 
per  hundred  cubic  feet.  These  changes  were  brought  about  by  the 
claims  of  gas  companies  that  it  is  much  more  difficult  than  formerly 
to  procure  coals  low  in  sulphur,  so  that  the  processes  for  the  removal  of 
the  sulphur  have  become  costly  and  burdensome. 

Illuminating  gas  is  required  by  law,  in  Massachusetts  and  in  many 
other  places,  to  be  free  from  ammonia  as  well  as  sulphurated  hydrogen, 
but  this  is  more  because  of  injury  to  fixtures  than  because  of  danger  to 
health. 

The  effect  of  these  carbonaceous  illuminants  is  to  elevate  the  tem- 
perature and  increase  the  moisture  of  a  room.  They  also  add  carbon 
monoxid,  carbon  dioxid,  nitric  and  nitrous  acids,  compounds  of  ammonia 
and  sulphur,  marsh  gas,  carbon  particles  (soot),  acids  of  the  fatty  group 
in  small  but  variable  amounts.  The  following  instructive  table  gives 
the  comparative  candle  power  and  also  the  gases  and  heat  produced  by 
the  usual  forms  of  illuminants: 


TaUow   candles 

Sperm   candles 

Paraffin    oil   lamp 

Kerosene  oil  lamp 

('oal  gas,  No.  5  Bats- 
wing  burner 

Coal  gas,  Argand  burner 

Coal  gas,  regenerative 
burner 

Coal  gas,  Welsbach  in- 
candescent   

Electric  incandescent 
light 


Quantity 
Consumed 


grains 

2,200 

1,740 

992 

909 

cu.  ft. 

5.5 

4.8 

S.2 

3.5 

lb.  coal 

0.3 


Candle- 
power 


16 
16 
16 
16 

16 
16 

32 

50 

16 


rnrhnn                          Heat  Vitia 

Oxygen     Vii",^    'Moisture  Calories  tion 

Removed  pV'h,,pp,i  Produced      Pro-  Equal 

, Produced  ^^^^^  ^^^jj 


cu.  ft. 

10.7 

9.6 

6.2 

5.9 

6.5 
5.8 

3.6 

4.1 

0.0 


cu.  ft. 
7.3 
6.5 
4.5 
4.1 

2.8 
2.6 

1.7 

1.8 

0.0 


cu.  ft 
8.2 
6.5 
S.5 


1,400 
1.137 


s.s 

1,030 

7.3 
6.4 

1,194 
1.240 

4.2 

760 

4.7 

763 

0.0 

37 

12.0 

11.0 

7.5 

.  "^0 

5.0 
4.3 

2.8 

3.0 

0.0 


Water  gas  is  cheaper  than  coal  gas,  and  is,  therefore,  preferred  by 
gas  companies.     Usually  a  mixture  of  the  two  gases  is  supplied.     Ex- 


946     BACTEEIA  AND  POISOXOUS  GASES  IN  THE  AIE 

perience  shows  that  if  water  gas  is  properly  diluted  with  coal  gas  the 
danger  is  greatly  lessened.  Illuminating  gas  containing  6  per  cent,  of 
carbon  monoxid  is  not  hazardous.  Most  cities  limit  the  amount  to  10 
per  cent.  In  1890  the  10  per  cent,  statute  was  repealed  in  Massachu- 
setts, and  it  is  since  then  that  the  marked  increase  in  illuminating  gas 
poisoning  has  occurred.  There  were  1,231  deaths  caused  by  illuminating 
gas  in  Massachusetts  during  the  years  1886  to  1909.  About  one-half  of 
these  deaths  were  suicidal.  This  only  represents  the  fatalities,  and  does 
not  take  into  account  the  many  cases  of  chronic  poisoning  which  occur 
in  the  home  and  in  the  industries  where  much  illuminating  gas  is  used. 

Sedgwick  and  Schneider  ®  state  that  the  death  rate  from  poisoning 
by  illuminating  gas  in  Massachusetts  and  Ehode  Island  has  become 
nearly  equal  to  that  of  scarlet  fever  or  measles. 

Gas  pipes  in  a  dwelling  should  be  tested  from  time  to  time  with 
a  pressure  gauge,  and  minor  leaks  from  faulty  stopcocks,  from  "rubber" 
tubing  used  for  droplights,  etc.,  should  be  carefully  searched  for  and 
corrected.  A  flaring  gas  burner  is  not  only  wasteful,  since  it  implies 
the  escape  of  unburned  gas,  but  is  also  harmful  to  health.  A  gas  jet 
should  burn  steadily  without  jumping  and  flaring. 

Methane  (CH^),  also  called  "marsh  gas,"  "flre  damp"  or  "light  car- 
bureted hydrogen,"  is  found  in  nature  as  "natural  gas"  in  and  about 
coal  and  oil  regions.  Methane  is  very  light  compared  to  air  (specific 
gravity  0.5596),  and  forms  an  explosive  mixture  as  soon  as  it  amounts 
to  l/18th  of  the  volume  of  the  air.  Fortunately,  the  mixture  does  not 
ignite  readily,  but  is  nevertheless  the  cause  of  many  accidents  in  mines. 
The  gas  has  no  odor,  is  slightly  soluble  in  water,  burns  with  a  pale 
smokeless  flame,  yielding  watery  vapor  and  carbon  dioxid — "after  damp." 
Methane  forms  a  large  proportion  of  illuminating  gas.  It  is  usually  re- 
garded as  an  indifferent  gas,  but  it  probably  has  slight  toxic  properties. 
Haldane  found  that  5.5  per  cent,  of  methane  had  no  effect  on  man;  45 
per  cent,  causes  slower  and  deeper  breathing,  and  70  per  cent,  endangers 
life.  With  70  per  cent,  the  oxygen  is  reduced  to  only  6.3  per  cent,  and 
the  nitrogen  to  23.7  per  cent. 

Methane  is  also  given  off  in  large  quantities  from  decomposing  mat- 
ter in  swamps,  sewers  and  septic  tanks.  Methane  may  constitute  70 
to  80  per  cent,  of  the  gases  found  in  a  septic  tank.  The  gases  from  an 
Imhoff  tank  may  be  used  for  illumination  and  heating. 

The  table  on  the  following  page  shows  the  percentage  composition  of 
illuminating  gases,  with  the  gases  of  an  Imhoff  tank,  for  comparison. 

Other  Gases  in  the  Air — Ammoniacal  Vapors. — Ammoniacal  vapors 
irritate  the  conjunctiva,  but  have  no  other  evident  effect  on  health 
in  the  amounts  ordinarily  found  in  the  air. 

Hydrochloric    Acid    Vapors. — Hydrochloric    acid    vapors    in    large 

'Jour.  of.  Infect.  Dis.,  Vol.  IX,  No.  3,  1911. 


POISONOUS  GASES  IN  THE  AIR 


947 


Illuminating  Gases:     Composition  in  Percentage" 


Imhof!  Tank 

Natural  Gas 

Water  Gas 

Coal  Gas 

H 

8.6 

84.1 

4.6 

3.1 

.4 

1.31 

87.75 

6.6 

4.34 

30 
24 

2.5 
29 
.2 

1.5 
12.5 

47  49 

CH^ 

38  67 

CO, 

1  04 

N 

.85 

CO 

6.74 

0 

H,S 

C,H4 

5.21 

quantities  are  very  irritating  to  the  conjunctiva  and  respiratory  mucous 
membranes.  In  the  alkali  manufactures  they  are  sometimes  poured 
into  the  air  in  sufficient  quantity  to  destroy  vegetation.  When  in  suffi- 
cient concentration  they  may  induce  bronchitis,  pneumonia,  and  even 
destruction  of  hmg  tissue,  as  well  as  inflammation  of  the  eyes. 

Carbon  Bisulphid. — Carbon  bisulphid  is  given  off  in  the  vulcan- 
izing of  India  rubber.  It  produces  headache,  vertigo,  pains  in  the  limbs, 
formication,  sleeplessness,  nervous  depression,  and  loss  of  appetite; 
sometimes  deafness,  dyspnea,  cough,  febrile  attacks,  and  even  para- 
plegia. The  effects  seem  due  to  a  direct  anesthetic  action  on  the  nervous 
tissue. 

Hydrogen  Sulpliid. — Hydrogen  sulphid  is  a  colorless,  transparent 
poisonous  gas  possessing  the  smell  of  rotten  eggs.  It  is  a  product  of  the 
putrefaction  of  organic  substances,  containing  sulphur,  and  therefore 
found  where  vegetable  or  animal  matter  is  undergoing  decay.  It  is  also 
generated  by  the  decomposition  of  organic  matter  by  anaerobic  bacteria 
in  deep  lakes  and  ponds,  tainting  the  water,  in  which  it  is  soluble,  or 
coming  to  the  surface  and  tainting  the  atmosphere  where  its  presence 
is  indicated  by  the  discoloration  caused  to  neighboring  dwellings  painted 
with  white  lead.  Small  sluggish  streams  receiving  the  sewage  of  towns 
become  defiled  with  this  gas  from  which  source  it  may  be  discharged 
in  noticeable  quantities  as  it  is  carried  by  the  wind  in  different  direc- 
tions. Hydrogen  sulphid  is  formed  spontaneously  whenever  a  soluble 
sulphate  remains  in  contact  with  decaying  organic  matter  with  deficiency 
of  air.  It  is  also  formed  directly  by  the  union  of  sulphur  and  hydrogen, 
and  indirectly  by  the  action  of  acids  on  sulphids ;  it  is  found  in  the  gases 
contained  in  some  ground  waters;  further,  in  some  mining,  smelting, 
and  other  industrial  processes;  and  in  illuminating  gas,  which  contains 
traces.  Its  intense  odor  enables  it  to  be  recognized  when  present  in 
minute  quantities,  1  part  in  10,000  being  easily  noted.  It  is  slightly 
heavier  than  air — specific  gravity,  1.1912. 

Toxic  Action. — As  a  toxic  agent,  hydrogen  sulphid  stands  between 
hydrocyanic  acid  and  carbon  monoxid.     Appreciable  quantities  in  the 

'^Engineering  Record,  Febr.  5,  1916. 


948     BACTEEIA  AND  POISONOUS  GASES  IN  THE  AIR 

air  may  have  a  toxic  action,  which  is  due,  in  part,  to  the  formation  of 
sulphmethemoglobin,  but  mainly  to  a  direct  action  upon  the  nervous 
system.  The  susceptibility  of  man  to  this  gas  varies.  Its  dangerous 
nature  is  fully  recognized  in  all  chemical  laboratories.  The  effects  of 
small  amounts  are  not  well  understood;  Thackrah  could  find  no  bad 
effects.  On  the  other  hand,  Hirt  believed  it  produced  chronic  poison- 
ing, the  symptoms  being  chiefly  weakness,  depression,  anorexia,  slow 
pulse,  furred  tongue,  and  marked  pallor. 

According  to  Lehman  an  atmosphere  which  contains  0.7  to  0.8  of 
HgS  per  1,000  liters  of  air  is  dangerous  to  human  life,  while  air  con- 
taining 1  to  1.5  per  1,000  destroys  life- rapidly.  Vivian  Lewes  states 
that  man  is  killed  in  one  and  one-half  minutes  after  breathing  air 
containing  0.2  per  cent,  of  HgS.  The  sudden  death  of  men  when 
working  in  sewers  is  sometimes  supposed  to  be  due  to  sulphurated 
hydrogen. 

The  sjonptoms  caused  by  exposure  to  considerable  amounts  of  hydro- 
gen sulphid  are  redness  and  pain  of  the  eyes,  nasal  catarrh,  and  irrita- 
tion of  the  mucous  membrane  and  bronchi,  dyspnea,  cough,  rapid  beat- 
ing of  the  heart,  dizziness,  headache,  numbness,  and  cold  perspiration. 
Sudden  exposure  to  large  volumes  of  the  gas  causes  death  with  striking 
rapidity;  respiration  stops  before  the  heart.  Death  results  from  com- 
plete paralysis  of  the  central  nervous  system,  and  even  though  persons 
are  rescued,  they  may  subsequently  succumb  from  bronchopneumonia, 
caused  by  the  irritating  nature  of  the  gas. 

Autopsies  performed  immediately  after  rapid  death  disclose  no 
changes,  not  even  in  the  blood.  In  case  of  slow  death  edema  of  the 
lungs  or  pneumonia  will  be  present,  and  the  body  has  the  characteristic 
odor  of  hydrogen  sulphid.  If  death  comes  more  slowly  asphyxia  is 
added  to  the  nervous  symptoms;  the  blood  is  dark  and  its  hemoglobin 
may  be  altered,  while  the  urine  may  contain  albumin  or  sugar. 

Hydrogen  Sulphid  in  Seivers. — Workmen  in  excavations  are  some- 
times overcome  by  HgS,  when  a  spring  containing  this  gas  is  tapped. 
Workmen  are  also  occasionally  overcome  in  the  dead  ends  of  sewers,  in 
gate  chambers  or  manholes,  and  in  these  cases  II2S  is  sometimes  said  to 
be  the  cause  of  the  accident. 

Hydrogen  sulphid  is  formed  from  sewage  by  the  breaking  down  of 
protein  and  also  by  bacterial  action  upon  inorganic  sulphates. 

In  America,  and,  so  far  as  known,  in  Europe,  there  are  no  data 
indicating  that  this  gas  ordinarily  is  present  in  measurable  quantities 
in  sewers.  At  Worcester  it  is  stated  that  careful  examination  of  large 
volumes  of  sewer  air  failed  to  show  the  presence  of  either  hydrogen  sul- 
phid or  carbon  monoxid.  At  Lawrence  it  is  also  stated  that  hydrogen 
sulphid  has  never  been  detected  in  measurable  amounts  in  the  gas  of 
any  of  the  septic  tanks. 


SEWER  GAS  949 

On  the  other  hand,  it  is  known  that  hydrogen  sulphid  makes  its 
presence  known  around  a  number  of  septic  tanks  by  the  discoloration 
of  lead  paint,  and  even  from  the  odor  of  the  gas,  as  well  as  its  disinte- 
grating effects  upon  masonry.  Mr,  W.  Thwaites  ^^  records  from  0.2 
to  1.1  per  cent,  of  free  hydrogen  sulphid  per  volume  and  0.2  to  0.9  per 
cent,  of  combined  hydrogen  sulphid  in  the  sewerage  system  of  Melbourne, 
Australia.  The  sewage  of  this  city  flows  for  a  distance  of  about  18  to 
25  miles  and  is  applied  to  sewage  farms.  Hydrogen  sulphid  combines 
readily  with  basic  constituents  of  sewage  and  thus  differs  from  methane, 
nitrogen,  hydrogen,  and  other  gases  arising  from  decomposition. 

The  spent  liquors  from  tannery  wastes  sometimes  contain  calcium 
sulphid,  which  is  used  to  remove  the  hair  from  the  hides,  and  also  sul- 
phuric acid  which  is  used  in  one  of  the  processes  of  tanning.  When 
the  acid  meets  the  calcium  sulphid,  hydrogen  sulphid  is  evolved,  en- 
dangering those  in  the  sewers  or  along  the  trunk  lines.  Two  fatalities 
which  were  attributed  to  this  cause  occurred  in  Stoneham,  Massachu- 
setts. 

The  amount  of  hydrogen  sulphid  ordinarily  found  in  "sewer  gas" 
which  may  escape  into  houses  as  a  result  of  defective  plumbing,  is  so 
small  and  so  dilute  as  to  produce  no  known  s}Tnptoms.  Hydrogen  sul- 
phid is  by  no  means  the  only  malodorous  product  of  the  decomposi- 
tion of  sewage;  indol,  skatol,  cadaverin,  mercaptan  and  other  ill-defined 
products  are  even  more  offensive  than  hydrogen  sulphid. 

Sulphur  Dioxid. — Sulphur 'dioxid  is  extremely  irritating  and  causes 
bronchitis.  Those  exposed  to  the  fumes  in  the  bleaching  of  cotton  and 
worsted  goods  are  frequently  sallow  and  anemic. 

SEWER  GAS 

Sewer  gas,  once  a  hygienic  bugaboo,  is  now  not  seriously  regarded 
by  sanitarians.  Sewer  gas  became  the  residual  legatee  of  Murchinson's 
pythogenic  theory,  namely,  that  typhoid  fever  was  "produced  by  emana- 
tions from  decaying  organic  matter."  People  naturally  cling  to  the 
notion  that  anything  that  smells  bad  must  be  detrimental  to  health; 
sanitarians  know  however  that  our  sense  of  smell  is  a  very  poor  sanitary 
guide. 

Sewer  "gas"  is  nothing  more  or  less  than  air  containing  the  volatile 
products  of  organic  decay  coming  from  sewers  and  drains.  Sewer  gas 
is  a  variable  mixture  both  as  to  composition  and  concentration.  Some 
of  these  gases  are  more  or  less  poisonous,  but  not  in  the  great  dilution 
ordinarily  found  in  sewer  air.  As  a  matter  of  fact,  the  air  of  sewers  is 
ordinarily  freer  of  dust  and  bacteria  than   the  corresponding  outside 

"Thwaites,  W.:     Tr.  Am.  Soc.  of  Civil  Eng.,  Vol.  LIV,  Part  E,  pp.  214-30. 


950     BACTERIA  AND  POISONOUS  GASES  IN  THE  AIE 

air,  although  it  may  be  a  little  higher  in  carbon  dioxid — 10  to  30  volumes 
per  10,000.  It  is  absurd  to  regard  sewer  gas  as  the  cause  of  diphtheria, 
typhoid  fever,  scarlet  fever,  and  other  communicable  diseases.  So  far 
as  unpleasant  odors  are  concerned,  they  are  more  apt  to  come  from 
defective  drains  or  unclean  and  unventilated  house  plumbing  than  from 
a  well-constructed  sewer.  The  subject  of  putrid  odors  from  sewers  is 
a  highly  complicated  one.  Odors  are  due,  in  most  part,  to  decomposi- 
tion products,  such  as  hydrogen  sulphid,  ammonia,  indol,  skatol,  phos- 
phin,  mercaptan,  phenol,  and  various  acids,  such  as  acetic,  butyric,  vale- 
rianic and  other  compounds.  Workmen  employed  in  sewers  and  about 
sewage  ordinarily  remain  hale  and  healthy.  "Sewer  gas"  as  a  rule  is 
no  more  hurtful  than  the  gases  and  odors  a  farmer  subjects  himself  to 
on  the  manure  pile. 

Winslow  and  Greenberg  ^^  exposed  guinea-pigs  to  strong  odors  and 
gases  from  putrefying  feces,  and  found  that  there  was  a  reduction  in 
the  rate  of  growth  during  the  first  week,  but  the  animals  soon  be- 
came accustomed  to  the  odor  and  attained  after  two  weeks  a  normal 
growth. 

Delepine  ^^  could  not  detect  any  influence  of  sewer  air  either 
upon  the  growth  curve  of  cats,  rabbits,  and  guinea-pigs,  or  upon  their 
susceptibility  to  a  spontaneous  epidemic  due  to  infected  food. 

Bacteria  in  Sewer  Air. — When  it  was  found  that  there  are  no  danger- 
ous volatile  poisons  in  sewer  air  attention  was  focused  upon  the  bac- 
teria; however,  Nageli  as  long  ago  as  1877  showed  that  putrescent  liquids 
kept  in  the  same  sealed  vessel  for  over  two  years  did  not  infect  each 
other.  Sir  Edward  Erankland  then  showed  that  lithium  carbonate  in 
solution  did  not  contaminate  the  air,  but  that  when  effervescence  was 
produced  the  breaking  of  the  bubbles  on  the  surface  of  the  liquid  carried 
the  lithium  a  distance  of  21  feet  up  a  vertical  tube.  The  inference  was 
that  sewage  through  fermentation  or  splashing  may  send  bacteria  into 
the  air.  Pumpelly  in  1881  and  others  since  have  shown  that  bacteria 
are  not  given  off  from  a  liquid  if  the  surface  remains .  unbroken,  even 
though  the  air  may  blow  over  it.  In  1893  Miquel  began  a  monumental 
work  upon  bacteria  of  the  air.  He  made  routine  observations  at  the 
Montsouris  Observatory,  and  for  four  years  compared  the  bacteria  in 
the  air  of  a  Paris  street  with  the  air  of  sewers.  He  found  sewer  air  rela- 
tively pure  from  a  bacteriological  standpoint.  Carnelly  and  Haldane 
in  1877  found  fewer  bacteria  in  the  sewers  under  the  House  of  Parlia- 
ment and  other  places  than  in  the  air  of  adjacent  streets.  The  number 
of  bacteria  was  largest  in  the  best-ventilated  sewers,  because  these  brought 
the  street  bacteria  along  with  them.     Abbott  in  1894  showed  that  cul- 

"  Proceed.  Soc.  Exp.  Biol,  and  Med.,  May  15,  1918. 

"  Report  of  Sewer  Ventilation  Committee  upon  the  Effects  on  Health  of  the 
Air  of  the  High  Street  Sewer  in  Mianchester,  1909. 


SEW  EI?  (iAfci  951 

tures  of  B.  prodigiosus  are  not  carried  over  in  bubbles  produced  by 
natural  ferniontation  (yeast  in  a  carbohydrate  medium),  but  may  be 
carried  a  short  distance  by  blowing  air  at  considerable  velocity  through 
the  culture.  He  concluded  that  the  danger  of  bacteria  being  trans- 
mitted from  sewage  into  the  air  under  ordinary  circumstances  is  prac- 
tically negligible.  In  1907  Horrocks  revived  this  question  by  placing 
B.  prodigwsiis  in  the  water-closets  of  a  large  military  hospital  in  Gibral- 
tar, and  recovering  them  on  plates  suspended  on  top  of  the  soil  pipes  and 
in  manhole  openings.  His  work  gave  countenance  to  the  views  of  a  num- 
ber of  English  sanitarians,  who  maintain  the  reality  of  the  danger  from 
this  source.  Winslow  repeated  Horrocks'  experiments  in  1909,  using 
the  ordinary  sewage  of  Boston,  and  by  using  quantitative  methods  threw 
a  different  light  upon  Horrocks'  conclusions.  He  found  that  a  vigorous 
foaming  produced  very  slight  bacterial  infection  of  the  air — only  five 
prodigiosus  colonies  in  30  liters  of  air.  Further,  the  infection  always 
remained  localized.  Generally  he  found  the  air  of  house  drains  singu- 
larly free  from  bacteria.  It,  therefore,  seems  theoretically  possible,  but 
very  improbable,  that  infection  may  take  place  in  this  way.  Practically 
the  question  seems  to  have  little  importance.  Thus,  out  of  a  series 
of  examinations  of  plumbing  systems  in  actual  use,  Winslow  found 
intestinal  bacteria  only  four  times  in  200  liters  of  air,  and  these  directly 
at  the  point  of  local  splashing. 

If  there  is  any  danger  of  sewage  bacteria  coming  into  our  houses, 
it  is  rather  that  they  are  dragged  in  by  rats,  roaches,  water  bugs,  and 
other  vermin  that  use  sewers  and  drains  as  highways. 

Accidents  in  Sewers. — Workmen  who  enter  parts  of  a  sewerage  system 
are  sometimes  overcome.  Practical  sewermen  know  that  the  danger  is 
found  in  the  dead  ends,  gate  chambers,  manholes,  and  similar  places 
where  the  gases  can  accumulate;  also  in  suddenly  relieving  an  obstruc- 
tion in  a  sewer,  thus  permitting  a  blast  of  gases.  There  are  no  such 
dangers  in  a  well-ventilated  sewer.  Stagnant  sewage  and  sludge,  com- 
bined with  lack  of  ventilation,  form  conditions  resembling  a  septic  tank, 
and  it  is  this  combination  that  menaces  the  workers.  A  free  flow  of  sew- 
age promotes  ventilation  and  diminishes  the  chances  of  gases  accumu- 
lating. 

The  principal  gases  given  off  from  sewers  are  methane,  carbon 
dioxid,  hydrogen,  ammonia,  and  sometimes  hydrogen  sulphid.  None 
of  these  gases  is  particularly  poisonous,  excepting  the  last.  When 
carbon  monoxid  is  found  in  sewer  air  it  does  not  come  from  the  decom- 
position of  the  sewage,  but  from  illuminating  gas  which  leaks  in.  Many 
analyses  of  sewer  air  in  many  different  places  show  that  hydrogen  sul- 
phid is  usually  absent. 

The  following  table  gives  the  percentage  of  gases  found  in  settling 
tanks  in  various  cities  of  the  United  States : 


952     BACTEEIA  AND  POISONOUS  GASES  IN"  THE  AIR 


Settling  Tank  Gases:      Pebcentage  of  Constituents" 


Methane 

Nitrogen 

COa 

0 

H 

Atlanta 

84.1 

3.1 

4.6 

.4 

8.6 

Chicago 

84.9 

6.2 

8.6 

Urbana 

81 

6.1 

12.3 

.13 

Columbus 

83.5 

9.3 

8.1 

Worcester 

57.7 

32.5 

8.2 

1.2 

Lawrence 

78.9 

16.3 

3.4 

.5 

Manchester 

73 

16 

6 



5 

The  danger  in  entering  manholes,  gate  chambers,  or  dead  ends  of 
sewers  is  from:  (1)  illuminating  gas  which  has  leaked  in;  (2)  as- 
phyxia on  account  of  an  accumulation  of  carbon  dioxid  and  methane; 
(3)  trade  wastes  containing  volatile  substances,  such  as  petroleum  prod- 
ucts from  garages,  dry  cleaning  establishments,  oil  works,  or  gases  caused 
by  spent  liquors  from  tanneries,  chemical  works,  etc.;  (4)  poisonous 
gases,  as  hydrogen  sulphid,  which  are  said  sometimes  to  accumulate  in 
appreciable  amounts. 

Explosions  in  sewers  are  due  to  illuminating  gas  from  leaks ;  benzin, 
naphtha,  and  gasolene  from  garages,  dyeing  and  cleaning  works,  and 
also  from  lithographic  works;  hydrocarbon  oils  used  by  railroads  to 
prevent  freezing  of  switches,  and  other  inflammable  and  explosive  sub- 
stances. The  gases  may  be  fired  by  open  lights  carried  by  workmen,  by 
the  sparks  from  trolley  cars  or  fire  engines  passing  over  manholes,  or 
by  lightning.  The  prevention  is  constant  ventilation;  traps  for  catch 
basins,  and  furnishing  workmen  with  electric  lights  or  safety  lamps 
to  replace  ordinary  lanterns. 

ILLUSTRATIVE  CASES  OF  DEATH  BY  SEWER  GAS 

Case  No.  1. — The  main  sewer  of  the  town  of  Eevere,  Mass.,  discharges 
into  the  sea  near  the  southerly  end  of  Eevere  Beach.  In  order  that 
the  sewage  might  not  discharge  on  the  incoming  tide,  a  covered  tank 
was  built  near  the  seashore  into  which  the  sewage  collected,  and  the  tank 
was  constructed  of  such  capacity  that  the  sewage  would  not  rise  as 
fast  as  the  tide.  On  the  other  hand,  the  bottom  of  the  tank  was  some- 
what above  low  tide.  In  consequence,  the  flow  of  the  sewage  was  shut  oflE 
by  a  tide  gate  when  the  tide  was  high  for  several  hours  and  subsequently 
discharged  automatically  as  the  tide  went  down  and  the  sea  had  fallen 
below  half  tide.  Two  men  were  sent  to  clean  the  tank,  which  was  done 
by  stirring  up  the  sediment  Avith  a  stream  from  a  2i/2-inch  fire  hose 
at  about  the  time  the  tank  would  discharge.     It  appears  that  trouble 

^*  Engineering  Record,  Febr.  5.  1915. 


SEWER  GAS  953 

had  been  previously  experienced  by  gases  in  the  tank  chamber  at  such 
times,  and  the  man  in  charge  was  warned  of  this,  but  he  neglected  to 
warn  his  helper  whom  he  sent  down  into  the  tank;  the  helper  was  over- 
come and  drowned.  In  the  lawsuit  the  main  question  raised  was  whether 
the  town  agents  exercised  due  care  in  the  matter,  and  the  Jury  decided 
that  they  did  not,  and  awarded  full  damages  to  the  plaintiff.  No  evi- 
dence was  presented  to  show  the  character  of  the  gas  which  doubtless 
caused  the  accident  except  that  the  evidence  showed  that  the  gas  was 
odorless.  It  was  generally  believed  by  those  interested  in  the  case  that 
the  gas  was  COo. 

Case  No.  2. — On  August  fith  Henry  G.  Parker,^''  an  able  and  valued 
member  of  tiie  staff  of  tlie  Engineering  Department  of  Los  Angeles,  lo.st 
his  life  while  inspecting  a  weir  chamber  of  the  outfall  sewer  connecting 
the  Los  Angeles  sewer  system  with  the  Pacific  Ocean.  Mr.  Parker 
and  j\Ir.  Derby  eiiterod  the  chamber  to  test  the  working  of  the  gate, 
which  was  raised  and  lowered  by  means  of  a  hand-wheel  and  screw.  In 
attempting  to  raise  the  gate  they  were  overcome  with  the  foul  air  and 
were  required  to  retreat  to  the  surface  three  separate  times.  The  third 
time  Mr.  Parker  suddenly  fell  a  distance  of  twenty  feet,  and  the  body 
slipped  from  the  sluiceway  and  was  sucked  into  the  sewer  before  rescue 
could  be  accomplished.  Death  was  doubtless  due  in  large  part  to  the 
effect  of  the  gases  and  the  fall  of  twenty  feet,  and  not  to  drowning,  as 
very  little  water  was  found  in  the  lungs.  Just  what  gases  were  present 
is  not  stated. 

Case  No.  3. — During  the  pumping  out  of  a  manhole  in  Charleston, 
S.  C,  in  May,  1911,  a  small  boy  was  sent  down  to  remove  some  chips 
which  threatened  to  obstruct  the  suction  pipe.  He  succumbed  almost 
immediately.  One  of  the  workmen  went  down  to  rescue  him;  he  also 
became  unconscious.  A  third  party,  with  a  rope  tied  around  him,  went 
to  the  rescue  of  the  two.  When  taken  from  the  manhole,  the  small  boy 
was  dead,  and  the  second  man  was  unconscious.  The  symptoms  reported 
by  Dr.  Jager  and  Dr.  Jerdey  were  those  of  hydrogen  sulphid  poisoning. 
A  qualitative  analysis  of  the  air  of  the  manhole  made  at  a  later  time 
showed  the  presence  of  hydrogen  sulphid  and  no  appreciable  quantities 
of  carbon'  monoxid.  It  is  assumed  in  this  case  that  the  hydrogen  sulphid 
in  the  manhole  probably  accumulated  and  became  concentrated  in  the 
bottom  of  the  manhole,  although  it  was  recognized  that  other  .gases 
may  have  contributed  to  the  gravity  of  the  condition. 

Case  No.  Jf. — A  laborer  went  into  an  intercepting  sewer  on  Market 
Street  in  Lynn,  Mass.,  to  inspect  it,  and  after  he  had  proceeded  into  the 
sewer  about  250  feet  his  lantern  exploded,  covering  him  with  blazing 
oil.  The  cause  was  assumed  to  be  illuminating  gas  that  had  leaked  into 
the  sewer  from  some  unknown  place.  The  man  had  his  hair  singed  and 
^Engineering  Record,  Aug.  28,  1909,  LX,  9,  p.  252, 


954     BACTEKIA  AND  POISONOUS  GASES  IN  THE  AIR 

his  face  badly  blistered,  and  was  partly  overcome.  The  sewer  was  not 
ventilated,  nearby  manholes  having  been  closed. 

Prevention  of  Accidents  in  Sewers. — To  prevent  accidents  in  man- 
holes, and  other  parts  of  the  system  where  sewer  gases  may  collect, 
it  is  advisable  for  men  always  to  work  in  pairs,  and  to  be  ready  with 
rope,  tackle  and  tripod  in  case  of  emergency.  Accidents  may  be  pre- 
vented by  clearing  out  cul-de-sacs  where  sewer  gases  are  likely  to  collect, 
before  the  men  enter  sucli  places.  This  may  be  done  by  an  air  blast, 
but  as  this  is  usually  not  at  hand  the  same  purpose  may  be  accomplished 
by  a  water  spray  having  a  good  head  and  volume.  This  stirs  up  the  air 
and  ventilates  the  pocket. 

Other  precautions  to  determine  the  presence  of  dangerous  or  irre- 
spirable  gases  consist  in  lowering  a  candle,  a  safety  lamp,  or  small 
animals  (canary  or  mouse)  in  a  cage. 

Ventilation  of  Sewers. — Sewers  cannot  be  constructed  airtight  on 
account  of  the  numerous  openings  into  them.  The  tension  of  the  air 
in  sewers  is  generally  not  very  different  from  that  of  the  atmosphere 
outside.  The  movement  of  the  air  is  generally  in  the  direction  of  the 
flow  of  the  current.  The  simplest  plan  of  ventilation  is  by  means  of 
a  shaft  from  the  top  of  the  sewer  to  the  surface  of  the  street  or  road 
above,  where  the  opening  of  the  shaft  should  be  covered  by  an  iron 
grating.  These  openings  are  usually  placed  at  intervals  of  100  yards 
or  so.  This  system,  which  is  in  common  use,  has  been  much  criticized, 
mainly  on  account  of  the  fact  that  the  objectionable  gases  are  discharged 
more  or  less  immediately  under  the  noses  of  passers-by.  To  meet  this 
objection  it  has  been  proposed,  and  actually  come  about  in  some  places, 
to  locate  tall  iron  shafts  at  suitable  inteivals  to  permit  the  discharge 
of  air  and  gases  at  a  level  well  above  the  roofs  of  houses.  As  a  mat- 
ter of  fact,  if  sewers  are  well  constructed,  have  sufficient  fall  and  flow 
of  water,  there  will  be  no  accumulation  of  foul  gases.  One  of  the  main 
causes  of  decomposition  is  due  to  dead  ends.  These  should  not  be 
tolerated  by  the  engineer  in  charge  of  the  sewage  department.  Eecently 
an  agitation  has  been  started  to  solve  this  question  of  sewage  ventilation 
by  advocating  the  abolition  of  the  intercepting  traps  on  the  house  drains 
between  the  sewer  and  the  house,  thus  converting  every  house  drain 
and  every  soil  pipe  into  so  many  sewer  ventilators.  There  are  many 
objections  to  this  plan,  as  it  would  destroy  the  drain  isolation  between 
the  houses,  which  is  now  possible  from  the  sewer,  and  from  the  neigh- 
boring houses  of  the  district. 


CHAPTER  V 
FRESH  AND  VITIATED  AIR 

THE  BENEFITS  OF  FRESH  AIR 

Fresh  air  is  nature's  tonic.  It  stimulates  digestion,  promotes  as- 
similation, improves  metabolism,  strengthens  the  nervous  system,  and 
increases  our  resistance  against  some  diseases.  It  is  a  common  ex- 
perience that  fresh  air  gives  us  a  general  feeling  of  well-being.  Much 
of  the  benefit  of  an  outdoor  life  comes  also  from  the  exercise,  diversion, 
sunshine,  and  other  factors.  The  stimulating  effect  of  outdoor  air 
varies  considerably  with  the  temperature  and  movements  of  the  air. 
The  ceaseless  variations  in  the  rate  of  cooling,  evaporation  and  absorp- 
tion of  radiant  energy,  in  outdoor  conditions,  relieve  us  of  monotony 
and  stimulate  tone  and  metabolism.  Cold  air  is  especially  stimulating, 
and  much  of  the  good  of  sleeping  out  of  doors  is  perhaps  secondarily 
due  to  the  tonic  action  of  cold.  Sleeping  out  of  doors  or  with  open 
windows  atones  for  much  bad  air  during  the  daytime.  However,  the 
good  results  of  fresh  air  may  be  neutralized  by  undue  exposure  to  cold, 
especially  in  the  young,  the  aged,  and  the  feeble — or  even  in  robust  indi- 
viduals not  properly  protected. 

"We  may  write  and  talk  as  much  as  we  please  about  the  horrors 
of  bad  air  and  the  importance  of  fresh  air,  but  we  should  never  in- 
duce people  to  sit  in  cold  drafts  and  shiver  for  the  sake  of  pure  air, 
and,  in  fact,  we  would  not  want  to  do  it  ourselves"  (Macfie).  Extremes 
in  this  as  in  all  matters  hygienic  are  to  be  avoided.  It  is  important  that 
those  who  sleep  out  of  doors  or  sit  out  should  be  warmly  clad  and 
suflQciently  fed. 

THE  EFFECTS  OF  VITIATED  AIR 

The  effects  produced  by  an  atmosphere  vitiated  by  the  breath  and 
other  exhalations  from  human  beings  may  be  divided  into  acute  and 
chronic.  The  acute  effects  are  usually  lassitude,  headache,  vertigo, 
nausea,  vomiting,  and  even  collapse.  In  extreme  cases  death  may  en- 
sue. The  chronic  effects,  so  far  as  is  known,  include  anemia,  debility, 
and  disturbances  of  digestion.  Prolonged  exposure  to  vitiated  atmos- 
pheres also  influences  nutrition  and  metabolism,  depresses  vitality,  and 

955 


956  FEESH  AND  VITIATED  AIR 

lowers  the  resistance  to  certain  infections,  especially  to  the  pyogenic 
cocci,  the  tubercle  bacillus,  the  pneumococcus,  and  to  the  microorgan- 
isms causing  common  colds.  It  is  often  difficult,  especially  in  the  poorer 
classes,  to  know  how  much  is  due  to  bad  air  and  how  much  to  crowding, 
poor  food,  overwork,  loss  of  sleep  and  rest,  worry,  and  other  inflictions 
of  poverty.  There  is  plenty  of  evidence  to  show  that  men  living  in  insuf- 
ficiently ventilated  barracks  and  other  habitations  have  a  high  death  rate. 
The  lower  animals  under  like  conditions  in  crowded  and  poorly  venti- 
lated stables  also  have  a  high  mortality.  The  statistical  evidence  of 
the  English  Barrack  and  Hospital  Commission,  published  as  long  ago  as 
1861,  shows  that  men  living  a  considerable  portion  of  their  time  in 
badly  ventilated  rooms  have  a  higher  death  rate  than  those  having  well- 
ventilated  rooms,  other  conditions  being  about  the  same. 

The  high  morbidity  and  mortality  in  crowded  places  are  due,  in  part 
at  least,  to  the  favorable  conditions  for  the  spread  of  the  communicable 
diseases,  and  must  not  be  laid  entirely  to  the  effects  of  vitiated  atmos- 
pheres. 

Some  Extreme  Cases. — The  acute  and  fatal  effects  caused  by  breath- 
ing a  seriously  vitiated  atmosphere,  under  unusually  severe  conditions, 
are  well  illustrated  by  the  three  following  instances : 

After  the  battle  of  Austerlitz  300  Austrian  prisoners  were  shut  into 
a  prison  in  a  small  cellar,  and  260  were  killed  by  the  impure  air  in  a 
few  hours. 

In  the  tragedy  known  as  the  Black  Hole  of  Calcutta,  the  military 
prison  of  Fort  William,  January  18,  1756,  146  adults  were  shut  into  a 
room  only  18  feet  square  and  with  but  two  small  windows  on  one  side 
to  ventilate  it.  They  were  shut  in  at  8  P.  M.,  and  wathin  an  hour  some 
were  dead,  and  when  the  door  was  opened  at  6.20  next  morning  only 
23  were  found  to  be  alive.  One  of  the  survivors  gives  the  following 
description  of  the  horrors  of  the  night:  "At  this  period  so  strong  a 
flavor  came  from  the  prison  that  I  was  not  able  to  turn  my  head  that 
way  for  more  than  a  few  seconds  at  a  time.  Everybody  except  those 
at  the  windows  now  grew  outrageous  and  many  delirious.  By  eleven 
o'clock  greater  numbers  were  dead  or  dying,  and  those  living  were  in  an 
outrageous  delirium  and  others  quite  ungovernable.  A  steam  now  arose 
from  the  living  and  the  dead,  which  most  awfully  affected  those  who 
were  still  alive.  At  six  o'clock  next  morning  it  came  to  the  ears  of  the 
Indian  governor  the  havoc  death  had  made  in  this  fearful  place,  and  he 
ordered  their  release.  At  6.20  there  came  out  of  this  living  grave  23  half- 
dead  creatures,  being  all  that  remained  of  the  146  souls  who  had  entered 
the  Black  Hole  prison,  and  these  were  in  such  a  condition  that  it  seemed 
very  doubtful  whether  they  would  see  the  morning  of  another  day.  Many 
of  the  survivors  developed  putrid  fever  and  boils.  The  remaining  23 
were  poisoned  by  exhalations  from  their  own  lungs  and  bodies." 


THE  EFFECTS  OF  VrriATKI)  AIR  957 

An  almost  equally  terrible  tragedy  took  place  on  the  steamer  Lorir- 
donderry,  going  between  Sligo  and  Liverpool.  The  episode  is  thus 
described  by  G.  Henry  Lewes  ("Physiolog}^  of  Common  Life'')  : 

"On  Friday,  December  2,  1848,  she  left  for  Liverpool  with  two  hun- 
dred passengers  on  board,  inostly  emigrants.  Stormy  weather  came  on, 
and  the  captain  ordered  every  one  below.  The  cabin  for  the  steerage 
passengers  was  only  18  feet  long,  11  feet  wide,  and  7  feet  high.  Into 
this  small  space  the  passengers  were  crowded;  they  would  only  have 
suffered  inconveniences  if  the  hatches  had  been  left  open ;  but  the  captain 
ordered  these  to  be  closed,  and — for  some  reason  not  explained — he 
ordered  a  tarpaulin  to  be  thrown  over  the  entrance  to  the  cabin  and 
fastened  down.  The  wretched  passengers  were  now  condemned  to 
breathe  over  and  over  again  the  same  air.  This  soon  became  intolerable. 
Then  occurred  a  horrible  scene  of  frenzy  and  violence,  amid  the  groans 
of  the  expiring  and  the  curses  of  the  more  robust;  this  was  stopped 
only  by  one  of  the  men  contriving  to  force  his  way  on  deck,  and  to 
alarm  the  mate,  who  was  called  to  a  fearful  spectacle :  seventy-two  were 
already  dead,  and  many  were  dying;  their  bodies  were  convulsed,  the 
blood  starting  from  their  eyes,  nostrils,  and  ears." 

The  foregoing  instances  are  exceptional,  and  for  practical  purposes 
may  be  regarded  simply  as  the  results  of  suffocation.  The  usual  con- 
ditions never  approach  such  extremes,  but  are,  nevertheless,  important, 
for  they  may  be  serious.  We  must  first  consider  the  question  why  an 
atmosphere  vitiated  by  the  presence  of  human  beings  produces  ill  effects. 

Three  explanations  have  been  offered:  (1)  increase  of  carbon  dioxid 
and  diminution  of  oxygen;  (2)  poisons  in  the  expired  breath;  (3) 
physical  changes  of  the  air.  Each  of  these  explanations  will  be  consid- 
ered separately. 

The  Effects  of  Increased  Carbon  Dioxid  and  Diminished  Oxygen. — 
According  to  the  older  theories,  the  sensations  of  discomfort,  arising 
in  inclosed  places,  had  their  origin  either  in  an  excess  of  carbon  dioxid 
or  an  insufficiency  of  oxygen.  Thus,  in  the  early  experiments  of  Claude 
Bernard  (1857)  animals  were  confined  in  atmospheric  air  and  in  mix- 
tures both  richer  and  poorer  in  oxygen  than  atmospheric  air.  He  ex- 
plained the  poisonous  effects  of  carbonic  acid  when  respired  to  be  due 
to  the  fact  that  it  deprived  the  animal  of  oxygen.  Similar  results  were 
reported  by  Valentin  and  by  Paul  Bert.  Eichardson  in  1860-61  found 
that  a  temperature  much  higher  or  lower  than  20°  C.  had  the  effect  of 
shortening  very  considerably  the  lives  of  animals  confined  in  an  unventi- 
lated  jar.  Pettenkoffer  in  1860-63  cast  the  first  serious  doubt  on  the 
correctness  of  these  theories.  He  believed  that  the  symptoms  observed 
in  crowded,  ill-ventilated  places  were  not  produced  by  the  excess  of  car- 
bonic acid  nor  by  a  decrease  in  the  proportion  of  oxygen  in  the  air.  He 
further  did  not  believe  that  the  impure  air  of  dwellings  was  directly 


958  FEESH  AND  VITIATED  ATE 

capable  of  originating  specific  diseases,  or  that  it  was  really  a  poison 
in  the  ordinary  sense  of  the  term,  but  that  it  diminished  the '  resistance 
on  the  part  of  those  continually  breathing  such  air. 

Hermans  ^  showed  that  an  atmosphere  containing  only  15  per  cent, 
of  oxygen  and  as  much  as  2  to  4  per  cent.*  of  carbon  dioxid  may  not 
be  harmful.  On  removing  the  carbon  dioxid  there  was  no  great  discom- 
fort, even  when  the  oxygen  was  reduced  to  10  per  cent.  The  air  of  cer- 
tain>  breweries  examined  by  Lehmann  ^  contained  1.5  to  2.5  per  cent, 
of  carbon  dioxid,  and  men  worked  continuously  in  this  for  years  with- 
out any  ill  effects.  The  CO2  occasionally  rose  to  6  per  cent,  and  more, 
but  this  amount  produces  panting  and  distress.  It  is  now  generally 
admitted,  upon  the  testimony  of  numerous  experimenters,  that  an  atmos- 
phere containing  as  much  as  3  per  cent,  of  carbon  dioxid  and  as  little 
as  15  per  cent,  of  oxygen  has  no  toxic  effects  and  produces  no  disturb- 
ing symptoms.  In  the  most  poorly  ventilated  rooms  the  carbon  dioxid 
never  reaches  this  amount,  especially  when  produced  by  respiration  alone. 
It  is  unusual  to  find  0.5  per  cent.  In  the  most  crowded  rooms  the  oxygen 
rarely  reaches  as  low  as  20  per  cent.  In  mines  the  oxygen  is  often 
deliberately  kept  down  to  17  per  cent,  with  the  object  of  avoiding  dust 
explosions.  It  is,  therefore,  plain  that  we  must  look  to  other  causes 
for  the  effects  of  vitiated  air.     See  also  pages  867  and  872. 

Poisons  in  the  Expired  Breath. — In  1863  Hammond  believed  he 
demonstrated  the  presence  of  organic  matter,  because  when  vitiated 
air  is  passed  through  potassium  permanganate,  it  decolorizes  that  strong 
oxidizing  agent.  Hammond  confined  a  mouse  under  a  jar  in  which  the 
CO2  was  taken  up  by  baryta  water  as  fast  as  it  was  formed  and  the 
moisture  absorbed  by  calcium  chlorid.  ISTevertheless,  the  mouse  died  in 
40  minutes.  The  observation  was  repeated  a  number  of  times,  and 
death  ensued  invariably  in  less  than  one  hour.  Brown-Sequard  and 
D'Arsonval  in  1888-9  claimed  to  be  the  first  to  demonstrate  poisonous 
bodies  in  the  expired  breath.  They  condensed  the  moisture  in  the  ex- 
haled breath,  which  was  injected  into  the  veins  of  rabbits.  Death  usually 
took  place  in  a  few  days,  sometimes  in  a  few  weeks.  They  believed 
from  this  that  they  had  discovered  a  volatile  organic  poison  of  the  nature 
of  an  alkaloid,  similar  to  Brieger's  ptomains.  These  experiments  were 
repeated  with  variable  results,  but  in  1889  they  reported  ingenious  ex- 
periments in  which  they  obtained  additional  evidence  in  support  of  their 
former  statements.  Babbits  were  confined  in  a  series  of  jars  connected 
with  rubber  tubing,  permitting  a  constant  current  of  air  to  be  passed. 
The  animal  in  the  last  jar  received  the  air  from  the  lungs  of  the  animals 
in  the  other  jars.     This  animal  died  after  an  interval  of  some  hours, 

^Hermans:  "Ausschaltung  organischer  Substanzen  durch  den  Menschen," 
Archiv  f.  Eyg.,  1883,  I,  1. 

''Lehmann:  "Untersuchung  iiber  die  langdauernde  Wirkung  mittlerer  Kohl- 
eneauredosen  auf  den  Menschen,"  Arch.  f.  Eyg.,  1899,  XXXIV,  335. 


THE  EFFECTS  OF  VITIATED  AIR  959 

and  the  animal  in  the  next  jar  was  the  next  to  die.  The  first  and  second 
animals  usually  remained  alive.  When  absorption  tubes  containing 
concentrated  sulphuric  acid  were  placed  between  the  last  two  jars,  the 
animal  in  the  last  jar  remained  alive  while  the  one  in  the  jar  just 
before  was  the  first  to  die.  These  results  confirmed  their  belief  in  the 
existence  of  a  volatile  poison  absorbed  by  the  sulphuric  acid.  Haldane 
and  Smith  repeated  the  experiments  of  Brown-Sequard  and  D'Arsonval, 
using  five  bottled  mice.  They  continued  the  exposure  for  53  hours  with- 
out ill  effects  to  the  mice.  Beu  in  1893  also  repeated  these  experiments, 
and  came  to  the  conclusion  that  acute  poisoning  through  the  organic 
matters  contained  in  the  expired  air  was  not  possible,  and  that  the 
death  of  the  animals  was  due  to  changes  of  temperature  and  accumu- 
lation of  moisture  in  the  jars.  Rauer  in  1893,  also  Liibberd  and  Peters, 
concluded  from  similar  experiments  that  there  are  no  organic  poisons 
in  the  expired  air.  In  fact,  Merkel  stands  almost  the  only  sponsor  for 
the  correctness  of  the  conclusions  of  Brown-Sequard  and  D'Arsonval, 
and  with  some  slight  changes  of  technic  he  was  unable  to  get  uniform 
results. 

Lehmann  and  Jessen  in  1890  collected  from  15  to  20  c.  c.  of  con- 
densed fluid  per  hour  from  the  breath  of  a  person  exhaling  through 
a  glass  spiral  laid  in  ice.  This  fluid  was  always  clear,  odorless,  neutral 
in  reaction,  and  contained  slight  traces  of  ammonia  with  good  teeth; 
more  with  poor  teeth.  Inoculation  of  this  condensed  fluid  into  animals 
gave  negative  results.  Many  other  experiments,  including  von  Hoffman- 
Wellenhof,  Lehmann  and  Jessen,  Haldane  and  Smith,  Billings,  Weir 
Mitchell,  and  Bergey,  have  shown  that  the  fluid  condensed  from  the 
breath  is  no  more  toxic  than  distilled  water,  when  injected  into  animals. 
This  has  strengthened  the  general  belief  that  poisonous  bodies  are  not 
present. 

In  1894  Brown-Sequard  and  Davis  reported  further  experiments  in 
which  they  inoculated  over  one  hundred  animals  with  the  condensed 
fluid  of  respiration,  and  not  only  confirmed  their  former  statements, 
but  were  unable  to  understand  the  failure  of  other  experimenters,  and 
emphatically  reaffirmed  that  the  breath  contains  a  volatile  poison  and 
that  the  death  of  animals  under  experimental  conditions  is  not  due  to 
an  excess  of  carbon  dioxid  nor  a  deficiency  of  oxygen.  These  experiments 
were  repeated  by  Billings,  Mitchell,  and  Bergey  ^  in  1895,  who  came 
to  the  conclusion  that  the  ill  effects  of  vitiated  atmosphere  depend  almost 
entirely  upon  increased  temperature  and  moisture,  and  not  on  an 
excess  of  carbon  dioxid  or  bacteria  or  dust  of  any  kind.  They 
admit  that  the  cause  of  the  musty  odor  in  unventilated  rooms  is  un- 
known. 

'Published  by  Smithsonian  Institution,  1895.  Contains  a  summary  of  the 
literature  to  date,  with  references  to  authorities. 


960  FRESH  AND  VITIATED  AIR 

In  addition  to  reducing  potassium  permanganate,  it  has  been  shown 
that  the  breath  contains  traces  of  ammonia  and  traces  of  hydrochloric 
acid.  These  have  their  origin  in  decaying  teeth  and  decomposing  par- 
ticles of  food  or  other  putrefactive  or  pathological  changes  occurring 
in  the  upper  respiratory  passages.  The  ammonia  and  hydrochloric 
acid  exist  in  such  small  quantities  that  they  have  no  practical  bearing 
upon  the  question  under  consideration. 

Weichardt*  calls  attention  to  the  fact  that  putrefactive  processes 
go  on  in  the  excretory  products  of  the  respiratory  tract,  especially  in 
older  persons.  He  states  that  the  bronchial  mucus  of  corpses  contains 
a  poison  resembling  kenotoxin  (the  toxin  of  fatigue).  When  injected 
into  laboratory  animals  it  produces  a  lowering  of  temperature,  a  slow- 
ing of  respiration,  and  death.  According  to  Weichardt,  fluids  condensed 
from  the  expired  air  and  then  concentrated,  when  injected  into  mice, 
produce  like  results.  This  investigator  also  evaporated  some  of  the 
condensed  moisture  from  the  expired  breath  and  obtained  a  weighable 
residue  (9  milligrams  from  10  c.  c).  This  he  regards  as  partly  or- 
ganic matter.  As  further  proof  that  the  organic  matter  in  the  expired 
breath  is  active,  he  obtained  from  the  expired  breath  of  a  tired  old  man 
the  condensed  fluid  which  he  then  concentrated.  This  concentrated 
fluid  has  a  distinct  inhibitory  effect  upon  the  oxidizing  power  of  the 
ferments  in  blood,  as  shown  by  the  guaiac  indicator.  Also  by  means 
of  the  epiphanin  reaction  Weichardt  considers  that  he  has  demonstrated 
protein-split  products  in  the  vitiated  air  of  a  room.  He  concludes  that 
substances  having  such  important  biological  power  should  not  be  longer 
overlooked.  These  results  lack  confirmation,  and  the  methods  are 
open  to  criticism. 

Rosenau  and  Amoss  ^  demonstrated  the  presence  of  minute  traces 
of  non-poisonous  protein  matter  in  the  expired  breath  through  the 
reaction  of  anaphylaxis.  The  first  injection  into  guinea-pigs  of  the 
fluid,  obtained  by  condensing  the  moisture  of  expiration,  is  harmless, 
but  the  animals  become  sensitized,  so  that  they  react  to  an  injection  of 
human  blood  serum  after  an  interval  of  several  weeks.  These  results 
lack  confirmation,  in  fact  Weisman  and  also  Winslow  obtained  nega- 
tive results.  In  any  event  there  is  no  evidence  that  the  expired  breath 
contains  a  poisonous  substance. 

Physical  Changes  in  the  Air. — Ovsdng  to  the  failure  of  chemistry  to 
demonstrate  the  cause  of  the  ill  efi^eets  produced  by  a  vitiated  atmos- 
phere, attention  has  recently  been  focused  upon  the  physical  changes, 
such  as  the  increase  in  temperature,  increase  in  humidity,  and  the  still- 
ness of  the  air  in  a  poorly  ventilated  room.     Hermann  in  1883  first 

■*  Weichardt:  "Ueber  Eiweifsspaltprodukte  in  der  Ausatmenluft,"  Arch.  f. 
Hyg.,  1911,  74  Bd.,  Heft  5. 

"■'Organic  Matters  in  the  Expired  Breath,"  Jour,  of  Med.  Researcli,  Vol. 
XXV,  No.  1,  Sept.,  1911,  p.  35. 


TITK  EFFECTS  OF  VITIATFT)  ATH  9fil 

pointed  out  that  heat  and  moisture  were  probably  the  factors  that  pro- 
duced the  harmful  cfl'octs  of  bad  air  rather  than  its  chemical  com- 
position. Important  e.\j)erimonts  were  carried  out  about  live  years  ago 
in  the  Institute  of  Hygiene  in  Breslau  by  Heymann,  Paul,  and 
Erclentz.  Fliigge,"  who  was  then  the  director  of  the  institute,  has 
admirably   sumnuirized    and   interpreted   the   results   as   follows: 

Paul  placed  healthy  individuals  in  a  cabinet  of  3  cubic  meters' 
capacity,  where  they  were  kept  for  a  variable  time  up  to  four  hours, 
and  until  the  carbon  dioxid  had  risen  to  100  or  150  parts  in  10,000 — 
an  accumulation  of  gaseous  excretion  practically  never  developed  un- 
der ordinary  conditions.  In  these  experiments  no  symptoms  of  illness 
or  discomfort  developed  so  long  as  the  temperature  and  moisture  were 
kept  low.  Tests  of  the  psychic  fatigue  of  these  individuals  by  means 
of  the  esthesiometer  and  ergograph,  or  by  means  of  compatations,  gave 
negative  results  throughout,  under  similar  conditions  of  temperature  and 
moisture.  Tests  in  a  crowded  schoolroom  were  similarly  negative.  Er- 
clentz made  the  same  observations  on  diseased  persons.  Those  suffering 
from  emphysema,  heart  diseases,  kidney  diseases,  etc.,  with  the  excep- 
tion of  a  few  peculiarly  susceptible  anemic  and  scrofulous  school  chil- 
dren, bore  the  highly  vitiated  air  for  hours  without  any  evidence  of 
bodily  or  mental  depression. 

The  results  were  very  different,  however,  when  the  temperature  and 
moisture  of  the  air  -of  the  cabinet  were  allowed  to  increase.  At  80°  F. 
with  moderate  humidity,  or  at  from  70°  to  73.5°  F.  with  high  humid- 
ity, practically  all  persons  began  to  show  depression,  headache,  dizziness, 
or  a  tendency  to  nausea.  The  susceptibility  was  not  alike  for  all. 
School  children  reacted  slightly  and  emphysematics  slightly,  while  those 
with  heart  troubles  were  most  susceptible.  By  means  of  certain  ob- 
jective signs  of  heat  stagnation — the  surface  temperature  of  the  fore- 
head and  the  temperature  and  moisture  of  the  clothed  parts  of  the 
body — it  was  determined  that  subjective  symptoms  appeared  only  when 
the  surface  temperature  reached  a  certain  height.  This  was,  for  healthy 
people,  93°  F.  to  95°  F.  on  the  forehead;  for  the  more  susceptible  and 
diseased,  89.5°  to  91.5°;  and  with  the  moisture  of  the  skin  increased 
by  20  or  30  per  cent.  Under  these  conditions  the  normal  dissipation 
of  body  heat  is  interfered  with,  and  it  is  under  these  conditions  that 

'Fliigge:  ZtscTir.  f.  Hyg.,  1905,  XLIX,  363.  Crowder:  Archived  of  In- 
ternal Medicine,  Jan.,  1911,  Vol.  VII,  pp.  85-133.  Contains  an  admirable  sum- 
mary and  references  to  the  literature  upon  the  subject.  More  recent  references 
will  be  found  in  Crowder's  article.  Arch,  of  Int.  Med.,  Oct.,  1913,  p.  420.  Winslow, 
C.-E.  A.,  and  Palmer,  G.  T.:  The  Effect  upon  Appetite  of  the  Chemical  Con- 
stituents of  the  Air  of  Occupied  Rooms.  Proceed.  Soc.  Exp.  Biol,  and  Med., 
1915,  XII,  141.  Hill,  L.,  Flack,  M.,  Mcintosh,  J.,  Rowlands,  R.  A.,  and  Walker, 
H.  B.:  The  Influence  of  the  Atmosphere  on  Our  Health  and  Comfort  in  Con- 
fined and  Crowded  Spaces,  Smithsonian  Miscel.  Col.,  1913,  No.  20,  LX.  Hen- 
derson, Y. :  The  Unknown  Factors  in  the  111  Effects  of  Bad  Ventilation,  Trans. 
15th  Inter.  Cong,  on  Hyg.  and  Demog.,  Washington,   1913,  II,  622. 


962  FRESH  AND  VITIATED  AIR 

symptoms  appear  which  are  in  every  way  similar  to  those  developed 
in  overfilled  and  "stuffy'^  rooms. 

:N^ow,  \\heii  these  people  in  the  cabinet  suffering  from  such  symp- 
toms were  allowed  to  breathe  the  fresh  outside  air  through  a  tube,  such 
air  being  raised  to  the  temperature  and  relative  humidity  of  that  within, 
it  gave  them  no  relief  whatever ;  nor  did  the  internal  air  produce  any 
symptoms  when  breathed  through  a  "tube  by  one  outside  of  the  cabinet. 
But  the  symptoms  of  discomfort  and  illness  experienced  by  the  person 
within  could  be  almost  immediately  relieved  either  by  drying  the  air 
of  the  cabinet  or  by  cooling  it,  or  by  putting  it  in  rapid  motion  by  means 
of  a  fan,  without  any  chemical  change  being  made  in  the  air.  The 
effect  of  these  measures  is  simply  by  purely  mechanical  means  to  enable 
the  body  to  throw  off  its  heat  more  rapidly,  and  thereby  all  symptoms 
disappear;  heat  stagnation  is  the  cause  of  the  discomfort. 

From  the  long  series  of  experiments,  carried  out  with  great  care  as 
to  all  the  details  of  observation  and  control,  it  is  concluded  that  all  of 
the  symptoms  arising  in  the  so-called  vitiated  atmosphere  of  crowded 
rooms  are  dependent  on  heat  stagnation  in  the  body,  and  that  the  ther- 
mic conditions  of  the  atmosphere,  its  moisture,  and  its  stillness  are 
responsible  for  the  effects.  To  change  any  one  of  these  elements  is  to 
change  the  rapidity  of  the  loss  of  heat.  If  the  change  is  such  as  to 
increase  this  loss,  comfort  is  restored.  It  is  also  considered  proved 
beyond  any  reasonable  doubt,  by  their  own  as  well  as  by  previous  re- 
search, that  there  is  no  gaseous  excretion  into  the  surrounding  air,  either 
from  the  breath  or  from  other  sources,  deserving  of  the  name  of  poison. 

Angelici,'^  working  independently  at  about  the  same  time,  concurs  in 
these  opinions ;  and  Reichenbach  and  Heymann  ^  later  determined  that 
objective  evidence  of  heat  stagnation  in  the  body  always  precedes  the 
development  of  subjective  symptoms  of  discomfort  under  natural  con- 
ditions, in  the  same  way  it  does  under  the  artificial  conditions  of 
the  cabinet. 

Leonard  Hill  ^  of  England  also  has  confirmed  these  general  results 
and  conclusions. 

The  New  York  Commission  on  Ventilation  ^"  found  that  the  power 
to  do  mental  or  physical  work,  measured  by  the  quantity  and  quality 
of  the  product  by  subjects  doing  their  utmost,  is  not  at  all  diminished 
by  a  room  temperature  of  86°  F.,  with  80  per  cent,  relative  humidity,  but 
the  inclination  to  do  physical  work  is  diminished  by  high  temperatures. 

^Angelici:  Quoted  by  Eeichenbach  and  Heymann,  Ztsclir.  f.  Hyg.,  1907, 
LVII,  23. 

'Reichenbach  and  Heymann:  "Untersuchungen  iiber  die  Wirkungen  klima- 
tischer  Factoren  auf  den  Menschen."  Ztschr.  f.  Hyg.,  1907,   LVII,  23. 

»Hill,  Leonard,  Rowland,  R.  A.,  and  Walker,  H.  R.:  "The  Relative  Influ- 
ence of  the  Heat  and  Chemical  Impurity  of  Close  Air,"  London  Hosp.  Med.  Col., 
Journal  of  Physiology,  LXI,  1911. 

^  Amer.  Jour,  of  Public  Health,  Vol.  V,  February,  1915,  No.  2,  p.  85. 


THE  EFFECTS  OF  VITIATKI)  AlK'  963 

The  only  eftect  of  stagnant  air,  even  when  it  contains  twenty  or  more 
parts  of  carbon  dioxid,  is  slightly  to  diminish  the  appetite. 

The  experiments  seem  to  indicate  that  overheated  rooms  are  not 
only  uncomfortable,  but  produce  well  marked  effects  upon  the  heat  regu- 
lating and  circulatory  systems  of  the  body  and  materially  reduce  the 
iiicliiKitioii  (if  occupants  to  do  physical  work.  The  most  important 
effects  of  even  a  slightly  elevated  room  temperature,  such  as  75°  F., 
are  sufTiciently  clear  and  important  to  warrant  careful  precautions 
against  overheating.  A  warm  atmosphere,  especially  if  moist  and  still, 
causes  a  rise  in  bodily  temperature  and  this  in  turn  disturbs  metabolism, 
decreases  working  power,  and  causes  early  onset  of  fatigue.  It  is  now 
clear  that  most  of  the  symptoms  caused  by  poorly  ventilated  rooms  are 
due  to  the  prevention  of  heat  loss  owing  to  the  physical  conditions  of 
the  air.     See  also  ]iages  9()4-Dlli. 

Reinspiration  of  Expired  Air. — By  tliis  phenomenon  is  meant  the 
immediate  reinspiration  of  a  portion  of  our  expired  breatti.  This  occurs 
quite  commonly,  in  fact  may  almost  be  regarded  as  a  normal  accom- 
paniment of  respiration  during  the  major  part  of  our  lives.  Lehmann  ^^ 
and  also  Heymann  ^^  determined  the  CO2  of  the  inspired  air,  compared 
this  with  the  COo  of  the  surrounding  air,  and  from  the  difference  com- 
puted the  proportion  of  the  breath  which  was  reinspired.  They  found 
this  proportion  to  vary  greatly.  It  was  sometimes  more  than  6  per 
cent.,  but  dropped  to  zero  in  the  open  air,  and  in  a  breeze  of  3  meters 
per  second.  Crowder  ^^  confirms  these  observations  and  extends  them 
'much  further.  He  shows  that  under  many  conditions  the  air  about  the 
face  contains  much  more  COg  than  the  surrounding  air.  The  path  of 
the  expired  air  maj^  roughly  be  seen  by  watching  the  course  of  smoke 
blown  from  the  nostrils.  The  expired  air  leaves  in  a  cone-shaped  expan- 
sion, part  of  which  lies  quite  close  to  the  body,  and  then  rises  slowly  by 
convection  currents.  Inspiration  follows  expiration  immediately,  there- 
fore every  chance  is  offered  for  some  of  the  expired  air  to  be  again 
drawn  in,  except  when  facing  a  breeze  of  from  200  to  300  feet  per 
minute,  or  when  walking,  riding,  or  fanning.  "When  the  back  is  turned 
to  a  breeze  a  little  of  the  expired  air  is  often  reinhaled  in  spite  of  the 
current. 

The  position  of  the  head  influences  the  amount  of  air  rebreathed. 
Thus  Crowder  has  shown  that  while  sitting  upright  the  reinspiration 
was  2.3  per  cent.;  lying  down  with  a  pillow  tilting  the  head  forward, 
1.3  per  cent. ;  lying  flat,  head  thrown  back,  none  at  all.  In  the  ordinary 
position  in  bed,  with  the  head  on  the  side  and  flexed,  with  pockets  or 

"  Lehmann :  "Der  Kohlensauregehalt  der  Inspirationsluft  im  Freien  und  im 
Zimmer,"  Arch.  f.  Eyg.,  1899,  XXXIV,  315. 

"  Heymann :  "Ueber  den  Einfluss  wieder  eingeathmeter  Expirationsluft  auf 
die  Kohlensaure-Abgabe,"  Ztschr.  f.  Eyg.,  1905,  XLIX,  388. 

''Crowder:     Archives  of  Internal  Med.,  Oct.,  1913,  Vol.  XII,  pp.  420-451. 


964  FKESH  AND  VITIATED  AIR 

dead  spaces  for  the  air  to  stagnate,  there  will  be  a  greater  retention  of 
expired  air.  This  occurs  especially  when  the  head  sinks  into  a  soft 
pillow. 

It  may  be  concluded  that  when  one  lives  indoors  and  remains  quiet 
he  will  immediately  rebreathe  from  1  to  2  per  cent,  of  his  own  expired 
air;  in  bed  it  will  be  more,  from  1  to  5  per  cent.,  and  even  10  to  18 
per  cent.,  depending  on  the  position  in  which  he  lies.  Nor  does  sleep- 
ing in  the  open  insure  "pure"  air,  for  breathing,  especially  when  one 
buries  his  head  between  pillows  and  bedclothes  for  the  sake  of  warmth. 
On  the  other  hand,  it  is  plain  that  "a  little  extension  of  the  dead  space 
beyond  the  tip  of  the  nose  is  of  no  consequence." 


SUMMARY 

It  is  now  perfectly  plain  that  the  ill  effects  resulting  from  a  vitiated 
atmosphere  are  not  due  to  an  increase  of  carbon  dioxid  nor  to  a  diminu- 
tion in  oxygen.  Upon  this  point  all  are  agreed.  The  general  con- 
sensus of  opinion  also  excludes  poisonous  bodies  in  the  expired  breath 
as  a  factor. 

Sanitarians  are  satisfied,  with  the  evidence  presented,  that  most  of 
the  discomfort  is  due  to  physical  changes  only.  If  a  normal  heat  inter- 
change can  be  maintained  between  the  body  and  the  air  the  symptoms 
which  are  commonly  attributed  to  poor  ventilation  do  not  develop.  Ac- 
cording to  this  view  the  vital  element  of  the  ventilation  problem  becomes 
that  of  regulating  the  temperature,  moisture,  and  motion  of  the  air. 
When  the  air  is  still  we  are  surrounded  by  an  "aerial  envelope"  with 
a  temperature  and  moisture  resembling  the  open  air  on  a  hot  and  humid 
day.  The  symptoms  caused  by  crowd  poisoning,  such  as  oppression, 
malaise,  headache,  vertigo,  nausea,  vomiting,  and  even  collapse,  indeed 
resemble  those  of  heat  exhaustion. 

Metabolism  is  refiexly  retarded  by  a  warm  aerial  envelope,  and  stimu- 
lated by  cool  moving  air,  the  consumption  of  oxygen  by  the  tissues  and 
the  production  of  CO2  by  them  being  much  less  in  warm  air  than  in 
cold  air. 

Even  those  who  look  upon  the  physical  changes  in  the  air  as  the 
sole  cause  of  the  discomfort  rather  than  the  possibility  of  chemical 
changes  admit  that  a  certain  amount  of  fresh  air  must  be  supplied. 
Eliigge  himself  urges  that  life  in  the  open  should  be  more  and  more 
resorted  to,  but  he  would  have  the  motive  correctly  understood,  not 
that  the  chemical  condition  of  inside  air  is  harmful,  but  that  it  is  the 
overheating  of  rooms  that  causes  disturbances  of  health.  Fliigge  states 
that  one  should  go  into  the  open  not  because  he  may  breathe  chemically 
purer  air,  but  because  its  almost  constant  motion  carries  away  the  body 


SUMMARY  9Go 

heat  and  causes  a  beneficial  stimulation  of  the  skin  and  reflexly  brings 
about  a  boi,ij:ht('ncd  cell  activity  that  aids  in  the  development  of  sturdy 
health.  The  chemistry  of  air  and  "crowd  poisons"  have  little  or  no 
part  to  play  in  the  explanation  of  outdoor  benefits  or  of  indoor  discom- 
forts. These  are  both  dependent  upon  physical  conditions,  and  their 
explanation  rests  with  the  physics  of  heat  interchange  between  the  body 
and  its  surrounding  medium. 

There  is  some  danger  in  regarding  the  ill  effects  of  poor  ventilation 
as  due  to  thermal  and  other  physical  factors  alone.  According  to  this 
theory  it  is  only  necessary  to  keep  the  temperature  and  moisture  down 
and  keep  the  air  in  motion;  a  closed  office  with  an  electric  fan  would 
take  the  place  of  any  system  of  ventilation.  There  is  already  a  clamor 
against  tlie  laws  requiring  fresh  air  in  workrooms,  based  upon  Fliigge's 
views.  This  is  a  natural  corollary  of  Fiiigge's  views.  If  rebreathing 
tlie  same  air  is  not  hurtful,  the  ventilation  of  living  rooms  mav  be  greatly 
simplified  by  simply  keeping  the  physical  conditions  of  the  air  within 
the  limits  of  comfort.  Furthermore,  a  great  economy  would  be  effected. 
It  is,  however,  not  scientific  to  insist  that  the  chemical  changes  in  a 
vitiated  atmosphere  may  be  disregarded,  because  Ave  cannot  at  present 
demonstrate  immediate  relationship  between  cause  and  effect;  neither 
is  it  safe  to  deny  dogmatically  the  existence  of  injurious  substances  in  a 
vitiated  atmosphere  simply  because  in  the  present  state  of  our  knowledge 
chemistry  has  failed  to  demonstrate  them,  and  because  most  of  the  symp- 
toms may  be  explained  upon  disturbances  of  thermic  interchange.^* 

Furthermore,  most  of  the  observations  have  been  based  upon  short 
exposures;  it  is  very  probable  that  a  decrease  in  mental  and  physical 
efficiency  would  result  from  a  prolonged  exposure  to  a  vitiated  atmos- 
phere, even  though  it  were  kept  dry  and  cool.  The  improvement  in 
appetite,  nerve  vigor,  blood  quality,  and  muscular  tone  which  follows 
open  air  treatment,  even  in  the  rich  and  well-fed,  shows  the  paramount 
importance  of  fresh  air. 

"See  also  Sewall,  Interstate  Med.  Jour.,  XXIII,  Jan.  1,  1916. 


CHAPTER  VI 
VENTILATION  AND  HEATING 

VENTILATION 

The  problem  of  ventilation  is  apparently  a  very  simple  one;  all 
that  is  required  is  to  furnish  a  never-ending  stream  of  fresh  air  from 
the  inexhaustible  supply  without  to  replace  that  which  is  constantly 
being  vitiated.  To  do  this  under  the  artificial  conditions  of  house 
and  factory  life  is  often  extremely  difficult,  and  under  certain  circum- 
stances practically  impossible.  Further,  the  problem  of  ventilation 
must  take  into  account  not  only  the  quantity  of  air,  but  its  physical 
condition,  in  order  that  the  human  machine  may  operate  at  the  highest 
level  of  health  and  efficiency. 

Ventilation  must  serve  a  number  of  purposes  and  comply  with  a 
number  of  conditions  before  it  can  be  considered  satisfactory:  (1)  it 
must  bring  pure  air  from  without  in  order  to  dilute  and  remove  the 
products  of  respiration,  as  well  as  other  sources  of  vitiation;  (2)  it 
must  maintain  the  air  within  the  room  at  a  proper  temperature  and 
humidity,  and,  further,  must  keep  the  air  of  the  room  in  gentle  and 
continuous  motion;  (3)  it  must  remove  the  gases,  odors,  bacteria,  dust, 
and  other  substances  that  contaminate  the  air  of  inclosed  spaces;  (4) 
it  must  dilute  and  remove  the  impurities  produced  by  the  burning  of 
gas,  candles,  lamps,  and  other  sources. 

The  problem  of  ventilation  is  physical  rather  than  chemical,  cutane- 
ous rather  than  respiratory. 

The  purpose  of  ventilation  is  not  to  bring  outdoor  conditions  in- 
doors; the  art  of  ventilation  consists  in  adapting  indoor  conditions  to 
indoor  life.  Indoor  life  is  necessary  in  order  to  perform  the  delicate 
manipulations  which  cannot,  as  a  rule,  be  effectively  conducted  outdoors. 
Indoor  life,  then,  involves  quiet  and  protection  from  sudden  changes 
or  extremes. 

It  is  a  simple  mechanical  problem  to  condition  the  air  of  an  apart- 
ment. The  ventilating  engineer  finds  no  difficulty  in  regulating  the 
temperature  and  humidity  within  narrow  limits,  and  in  furnishing 
definite  quantities  of  fresh,  moving  air.  To  maintain  these  conditions, 
however,  the  doors  and  windows  must  be  kept  shut.     Herein  arises  the 

966 


VENTILATION  967 

first  dilTiculty  between  the  theory  and  the  practice  of  ventilation,  for 
it  is  plain  that  the  simplest  and  often  the  best  way  to  ventilate  a  room 
is  throntrh  open  windows.  The  second  difficnlty  arises  from  the  fact 
that  the  conditions  within  and  withont  the  room  to  bo  ventilated  are 
not  constant.  The  principal  factors  here  concerned  are  the  force  and 
direction  of  the  Mind,  chan.f^cs  of  outdoor  temperatnre.  and.  to  a  less 
decrree,  movements  within  the  room.  It  is.  therefore,  much  easier  to 
maintain  constant  air  conditions  in  a  sub-basement  than  in  a  room 
exposed  to  wind  and  weather.  Air  conditioning  is  now  an  established 
engineerinfr  science,  and  the  engineer  is  prepared  to  supply  any  kind 
of  air  that  is  desired. 

The  efficiency  of  any  system  of  ventilation  must  be  measured  by 
the  results  obtained  at  the  breathing  zone.  It  matters  little  what  the 
composition  or  the  condition  of  the  air  is  near  the  ceiling,  provided  the 
heated,  moistened,  and  vitiated  aerial  blanket  which  surrounds  us  is 
constantly  removed  and  replaced  with  a  fresh  supply  properly  condi- 
tioned. 

Ventilation  is  far  from  satisfactory  if  the  air  brought  into  the  room 
is  smoky,  dusty,  or  bacteria-laden,  or  if  it  is  contaminated  with  gases 
or  odors  from  cellars  or  surroundings.  Attention  should,  therefore,  be 
given  to  the  sources  of  the  air,  and  it  is  alw^ays  an  advantage  to  wash  or 
filter  it.  There  is  a  practical  limit  to  the  amount  of  fresh  air  that  may 
profitably  be  forced  into  a  room,  especially  warmed  air  in  the  winter 
time.  Ventilation  and  heating  naturally  go  hand  in  hand. 

The  belief  is  growing  that  it  is  not  dangerous  to  rebreathe  air,  and 
the  view  is  spreading  that  the  hygienic  value  of  ventilation  for  the  pur- 
pose of  maintaining  a  chemically  pure  atmosphere  in  dwellings,  schools, 
and  hospitals  is  not  so  great  as  is  commonly  supposed.  According  to 
this  view  it  is  more  important  to  ventilate  in  the  interest  of  the  heat 
economy  of  the  body,  by  the  establishment  of  a  suitable  temperature  and 
air  movement,  and  by  the  regulation  of  the  humidity  in  the  atmosphere. 
The  established  facts,  that  the  principal  causes  of  the  ill  etfects  of  viti- 
ated air  are  due  more  to  the  heat  and  humidity  and  stillness  of  the  air 
than  to  changes  in  its  chemical  composition,  have  led  some  hygienists  to 
recommend  rebreathing  the  air,  provided  the  physical  conditions  are 
kept  favorable. 

Satisfactory  ventilation  should  not  only  take  into  account  the  physi- 
cal conditions  of  the  air,  but  also  demands  a  generous  supply  of  fresh 
air  in  order  to  keep  the  chemical  composition  within  reasonably  normal 
limits.  Clean  air  in  motion  and  of  proper  temperature  and  humidity 
is  necessary  to  indoor  comfort. 

The  rigor  of  a  cold  climate  makes  of  its  inhabitants  a  house-dwelling 
race.  Under  these  conditions  houses  are  commonly  overheated,  if  not 
by  fire  and  steam,  then  by  the  heat  of  the  inhabitants'  bodies.     When 


968  VENTILATION"  AND  HEATING 

people  do  this  they  complain  of  poor  ventilation,  regardless  of  whether 
the  air  supply  is  large  or  small. 

The  problem  of  ventilation  is  immediately  related  to  clothing,  bath- 
ing, diet,  exercise  and  other  factors  in  personal  hygiene  that  stimulate 
the  vasomotor  mechanism  and  make  it  vigorous  and  effective.  In  other 
words,  the  problem  of  ventilation  concerns  itself  chiefly  in  conditioning 
the  air  so  as  to  favor  the  heat  regulating  mechanism  of  the  body. 

Dwelling  houses  are  usually  constructed  with  little  regard  for  ven- 
tilation. It ,  is  desirable  that  adequate  provision  should  be  made  for 
the  ventilation  of  every  house  that  is  built.  This  requires  just  as  much 
care  and  forethought  as  the  system  of  heating  the  house,  or  furnishing 
it  with  water,  gas,  electricity,  plumbing  for  the  disposal  of  wastes,  and 
other  household  conveniences.  Whatever  system  of  ventilation  may  be 
adopted,  it  is  wise  to  flush  rooms  frequently  with  fresh  air*  and  flood 
them  with  sunshine.  This  helps  to  blow  out  the  accumulated  dust  and 
bacteria,  to  oxidize  organic  matter  that  collects  as  a  film  on  all  surfaces, 
to  diminish  odors,  and  generally  to  purify  the  apartment. 

In  all  systems  of  ventilation  the  factor  of  faithful  and  intelligent 
operation  is  essential  to  success.  No  method  is  fool  proof  and  no  method 
will  work  by  itself.  Even  window  ventilation  requires  watchful  atten- 
tion of  those  in  charge  of  individual  rooms.  "Constant  vigilance  is  the 
price  of  pleasant  and  wholesome  air  conditions"   (Winslow). 

Air  Washing. — The  process  of  air  washing  consists  of  passing  the  air 
horizontally  through  a  chamber  in  which  water  is  falling  in  drops  as 
rain,  or  into  which  it  is  sprayed.  The  sprays  are  obtained  by  forcing  the 
water  out  of  perforated  pipes  or  through  nozzles  placed  across  ducts. 
When  the  sprays  intersect  they  are  said  to  form  a  "curtain."  The  object 
is  to  bring  the  air  and  water  into  intimate  contact.  Besides  the  washing 
chamber  there  are  heating  or  tempering  coils  in  the  ducts,  or  in  a  sepa- 
rate chamber,  and  devices  for  controlling  the  temperature.  The  water 
used  for  washing  is  circulated  by  means  of  a  pump  so  that  it  may  be 
used  over  and  over  in  the  spray  chamber  for  a  considerable  time. 

The  New  York  State  Commission  on  Ventilation  found  that  air 
washing  does  not  remove  body  odors. 

Washing  takes  out  many  of  the  impurities  in  the  air,  as  bacteria, 
molds,  dust,  epithelial  scales,  particles  of  various  descriptions,  also  some 
odors  and  gases,  but  not  CO,.  Washing  is  the  best  way  to  cleanse  the 
air  as  it  imitates  nature's  process  through  a  rain  shower.  If  desired, 
the  water  may  be  cooled  in  the  summer  time  so  as  to  influence  the 
temperature  of  the  air.  Se\eral  forms  of  air  washers  are  on  the  market, 
essentially  similar  in  principles,  but  differing  in  details  of  construction. 

Recirculation. — The  cost  of  heating  large  volijmes  of  cold  air  has 
naturally  stood  in  the  way  of  efficient  ventilation  of  schools  and  factories 
during  the  cold  weather.     x\nother  question  has  been  the  low  indoor 


VENTILATION  9G9 

relative  Iniinidify  produced  by  heatint;  outdoor  air  to  a  com  fori  al)l(' 
room  tciupcraturc.  Wasiiiii",'-  and  recirculating  the  air  overcomes  both 
of  these  objections  because  it  lurnishes  an  ami)le  supply  of  conditioned 
air  in  motion.  The  method  has  attracted  favorable  attention.  Naturally 
there  must  be  a  limit  to  the  continued  use  of  the  same  air,  but  ordinary 
leakage  and  the  use  of  a  certain  percentage  of  outside  air  prevent  the 
concentration  of  any  substances  not  removed  by  the  washer. 

'I'iu'  only  advantage  of  washing  and  recirculating  the  air  lies  in  the 
great  saving  of  fuel  in  cold  weather.  At  the  gymnasium  of  the  Inter- 
national V.  ^r.  ('.  A.  College  at  Springfield,  it  was  estimated  that  a 
saving  of  from  4U  to  50  per  cent,  of  coal  resulted  from  recirculating 
the  air.  The  success  with  the  method  at  Springfield  was  probably  due 
to  the  enormous  air  supply  of  the  gymnasium.  The  method  has  many 
objections  for  schools  and  workshops.  The  New  York  Committee  on 
Ventilation  was  quite  unable  to  wash  the  air  enough  to  remove  body 
odor.  There  are  factors  still  imperfectly  understood. 

Eecirculated  air  is  not  equal  to  outside  air  washed.  The  great  ob- 
jection is  that  washing  the  air  does  not  remove  odors;  it  is  therefore 
not  very  practical.  Eecirculation  may  be  subject  to  abuse,  and  if  used 
must  be  carefully  watched. 

"Vitiation  by  Respiration. — An  adult  individual  at  rest  breathes  at 
the  rate  of  about  seventeen  respirations  a  minute.  At  each  respiration 
about  500  c.  c.  (30.5  cu.  in.)  of  air  pass  in  and  out  of  his  lungs.  The 
air  in  the  lungs  loses  about  4  per  cent,  of  oxygen  and  gains  3.5  to  4 
per  cent.  CO,.  The  nitrogen  remains  unchanged.  In  addition  the 
expired  air  is  raised  in  temperature  to  nearly  that  of  the  blood,  98.4°  F. ; 
it  also  contains  much  aqueous  vapor. 

The  amount  of  CO,  which  is  given  off  by  an  adult  male  person  at 
rest  can  be  calculated  from  the  above  figures,  and  will  be  found  to  be 
0.71  cubic  foot  in  one  hour.     Thus: — 

17   X   30  X   60  _   ^^      , 

"VPTTS — 17.  i   cubic  feet  breathed  per  hour. 

1/28 

4  per  cent,  of  17.Y  =  0.71  cubic  foot  per  hour  of  CO2. 

From  actual  experiment  it  has  been  determined  that  an  average 
adult  gives  off  0.9  of  a  cubic  foot  of  CO2  during  gentle  exertion,  and 
possibly  as  much  as  1.8  during  hard  work.  The  adult  female  gives  off 
about  one-fifth  less  under  similar  circumstances,  and  an  infant  is  said 
to  give  off  about  0.5  cubic  foot  of  CO2  per  hour.  In  a  mixed  assembly 
at  rest,  including  male  and  female  adults  and  children,  the  CO2  given  off 
per  head  is,  therefore,  taken  as  0.6  of  a  cubic  foot. 

Vital  Capacity  of  the  Lungs. — The  volume  of  air  inspired  and  ex- 
pired depends  on  the  rate  and  extent  of  the  respiratory  movement, 
but  in  an  adult  man  of  average  size  and  vigor  about  500  cubic  ccnti- 


970  VENTILATIOX  A^B  HEATING 

meters  of  air  are  inspired  and  expired  during  quiet  breathing.  This 
volume  of  air  is  known  as  the  tidal  air,  and  since  the  total  volume  of 
air  in  the  lungs  is  about  3,500  c.  c.,  it  is  evident  that  in  normal  breath- 
ing a  large  amount  of  air — 3,000  c.  c. — remains  in  the  lungs  at  the 
end  of  expiration.  The  air  which  remains  behind  is  known  as  stationary 
air. 

By  forced  expiration  about  half  of  the  stationary  air,  i.  e.,  1,500 
c.  c,  can  be  expired,  and  this  portion  of  the  stationary  air  is  known 
as  the  supplemental  or  reserve  air,  while  the  final  1,500  c.  c,  which  no 
effort  can  expel,  is  known  as  the  residual  air.  The  total  of  3,500  c.  c. 
of  air  in  the  chest,  then,  at  the  end  of  ordinary  inspiration  is  made 
up  as  follows : 

Tidal  air 500  c.  c.    ' 

<~,^  ^.  .     [Supplemental  or  reserve 1,500  c.  c. 

Stationary  air  JR^gidual  air 1,500  'c.  c. 

3,500  c.  c. 

"When,  however,  inspiration  is  forced,  another  1,500  c.  c.  of  air,  known 
as  complemental  air,  can  be  inspired,  making  altogether  5,000  e.  c. 

The  total  amount  of  air  (complemental,  tidal,  supplemental)  which 
can  be  inspired  after  forced  expiration  is  known  as  the  ''respiratory 
capacity"  or  "vital  capacity"  or  "extreme  differential  capacity,"  and  the 
amount  varies  considerably  according  to  height,  weight,  vigor,  age,  etc. 

Peabody  and  "Wentworth  ^  furnish  the  following  standards  for  the 
vital  capacity  of  the  lungs  of  normal  men :  For  men  over  6  feet  tall, 
5,100  c.  c. ;  between  5  feet  Sy^  inches  and  6  feet,  4,800  c.  c. ;  between 
5  feet  3  inches  and  5  feet  814  inches,  4,000  c.  c.  In  women  of  the 
same  height,  it  is  about  one-fifth  less. 

■  Vital   capacity   is    a   good   index   of   vigor,    endurance   and   reserve 
power. 

Dead-space  Air. — AVitli  each  breath,  we  take  back  into  the  lungs  the 
air  contained  in  the  nose  and  larger  bronchi — the  "dead-space"  air. 
This  dead-space  air  constitutes  about  one-third  of  the  whole  volume  of 
quiet  inspiration,  and  not  less  than  one-tenth  of  deep  breathing.  To  all 
intents  and  purposes  it  is  expired  air  which  is  constantly  reinspired. 
Eebreathing  of  the  ordinary  dead-space  air  is  a  normal  and  conserva- 
tive process ;  it  prevents  pure  cold  air  from  entering  the  lungs  and  reduc- 
ing the  CO,  below  the  amount  required  for  stimulating  the  respiratory 
center;  it  makes  of  breathing  a  regular  and  continuous  rather  than 
an  irregular  and  interrupted  function.  Douglas  and  Haldane  have  re- 
cently shown  that  the  volume  of  the  dead-space,  instead  of  being  a  fixed 
quantity,  is  automatically  altered  so  as  to  give  greater  or  less  resistance 
to  the  air-flow  to  and  from  the  lungs  with  changing  exertion.    They  go 

^Arch.  Int.  Med.,  Sept.,  1917,  pp.  433  and  443. 


VENTILATION  971 

so  far  as  to  state  that  rather  marked  variations  may  occur;  and,  while 
tlie  mechanism  is  not  fully  understood,  they  think  the  regulation  is  as 
perfect  as  is  that  of  the  vasomotor  mociianism  for  controlling  the  blood 
flow. 

Factor  of  Safety. —  Bernard  and  ^lantoux  '^  have  shown  that  the  lungs 
are  capable  of  performing  the  respiratory  function  even  when  the  capac- 
ity is  reduced  to  one-sixth  of  (he  iKirnial.  Furtberniore,  we  should 
remember  that  the  possibility  of  increase  in  the  depth  of  inspiration  is 
400  to  500  per  cent.,  and  that  by  changing  the  rate  and  the  complete- 
ness of  expiration  the  alveolar  ventilation  may  be  increased  considerably 
more  than  1,000  per  cent.  From  this  great  margin  of  safety  it  is  easy 
to  understand  why  a  slight  increase  of  CO,  in  the  inspired  air  falls  far 
below  the  limits  of  our  conscious  effort.  From  the  experiments  of  Hal- 
dane  and  Priestley^  an  actual  increase  of  100  per  cent,  in  the  pulmonary 
ventilation  passes  almost  unnoticed.  The  factor  of  safety  which  Meltzer  * 
has  so  well  described  as  belonging  to  all  well  understood  physiologic 
processes,  is  here  a  very  generous  one. 

The  Amount  of  Air  Required.^ — Omitting  from  consideration  the 
question  of  temperature  and  moisture,  a  certain  amount  of  pure  air  is 
necessary  for  good  ventilation.  This  amount  is  determined  from  the 
amount  of  carbon  dioxid  taken  as  ah  index  of  the  impurities  from 
respiration  and  combustion,  and  may  be  ascertained  either  by  direct  ob- 
servation or  from  physiological  data.  The  accepted  amount  of  pure  air 
required  per  person  per  hour  is  from  2,000  to  3,000  cubic  feet.  The 
external  air  contains  3  parts  of  COg  per  10,000  (0.03  per  cent.),  and 
the  permissible  limit  for  indoor  air  is  placed  at  from  6  to  10  parts.  The 
volume  of  air  in  itself  is  not  as  important  a  factor  in  ventilation  as 
the  necessity  for  the  maintenance  of  air  movement  to  facilitate  evapora- 
tion and  the  elimination  of  heat.  It  is  interesting  to  note  that  it  re- 
quires just  about  as  much  air  to  regulate  heat  interchange  as  to  dilute 
the  CO2  to  permissible  limits.  The  amounts  necessarv'  to  remove  odors 
and  dust  are  about  the  same  as  that  required  to  keep  the  CO,  within 

*  Bernard  and  Mantoux:  "Capacite  pulmonaire  minima  compatible  avec  la 
vie,"  Jour,  de  Physiol.  Exper.,  1913.  XV,  16  (Ed.  Abstr.  in  Jour.  A7n.  Med. 
Assn.,  1913,  LX,  1794). 

^Haldane  and  Priestlev:  "The  Regulation  of  the  Lung  Ventilation,"  Jour. 
Physiol..  1905,  XXXII,  225*. 

^Meltzer:  "Factors  of  Safety  in  Animal  Structure  and  Animal  Economy," 
Harvey  Lectures,  New  York,   1907-8,  p.  139. 

^  Methods  of  Testing  Ventilation  Equipment. — Final  Report  of  the  Committee 
on  Standard  Methods  for  the  Examination  of  Air  of  the  Laboratory  Section  of 
the  American  Public  Health  Association.  Am.  Jour.  Public  IJealth,  1917,  No.  1, 
Vol.  VII.  Kimball,  D.  D.,  Lyle,  J.  I.,  and  Ohmes,  A.  K. :  The  Testing  of  At- 
mospheric Conditions  and  Heating  and  Ventilation  Equipment.  Am.  Hoc.  of 
Heating  and  Ventilating  Engineers,  Chicago,  July  18,  1917:  reissued  by  the 
Society  October  1,  1917.  Report  of  a  Committee  on  Standardization  of  the  L'se 
of  the  Pitot  Tube.  Trans.  Am.  Soc.  of  Heating  and  Ventilating  Engineers,  1914, 
XX,  210-215. 


972  VENTILATION^  AND  HEATING 

reasonable  limits.  The  amount  of  air  needed  in  good  ventilation, 
therefore,  remains  about  the  same  as  formerly,  but  our  reasons  for 
supplying  it  have  changed. 

It  has  been  found  from  actual  observation  that  an  adult  in  an  air- 
tight compartment  will  vitiate  the  air  as  follows: 

In  a  room  3,000  cubic  feet  CO2  =  0.06  per  cent,  in  1  hour 

u  u      i(      o  000      "         "       "     ^^^  0  07    "        "      "    "     " 
"  "      "       l',500      "         "       "     =  0.08    "        "      "    "     " 

"  "      "      1,'000      "         "       "     =  0.10    "        "      "    "     " 

The  same  results  may  be  obtained  from  physiological  data.  Thus, 
the  average  adult  expires  0.6  cubic  foot  of  CO2  per  hour.  The  differ- 
ence between  the  permissible  limit,  0.06  per  cent.,  and  the  amount  of 
carbon  dioxid  in  the  air,  0.03  per  cent.,  is  0.03.  It  follows  that  the 
amount  of  fresh  air  required  per  hour  by  an  adult  to  keep  the  CO2  down 
to  0.06  per  cent,  may  be  determined  from  the  following  equation : 

0.03  :  0.6    : :  100  :  x 

X  =  2,000  cubic  feet 

If  the  normal  amount  of  carbon  dioxid  in  the  air  is  taken  as  0.04 
instead  of  0.03,  the  result  is  3,000  cubic  feet,  the  amount  generally 
accepted,  which,  however,  is  somewhat  in  excess — as  it  should  be.  This 
does  not  mean  that  there  should  be  3,000  cubic  feet  for  each  person 
in  an  inhabited  room,  for  it  is  sufficient  if  the  air-space  is  1,000  cubic 
feet,  provided,  of  course,  the  air  is  changed  three  times  an  hour. 

The  same  results  may  be  obtained  by  using  the  formula: 

E 

—  =  D 
-      P 

E=the  amount  of  carbon  dioxid  exhaled  by  one  person  in  one 
hour;  the  general  average  for  an  adult  being  0.6  cubic  foot. 

P=the  amount  of  added  CO,  permitted,  stated  in  cubic  feet;  or 
0.06—0.03=0.03  per  cent.,  or  0.000,3  cubic  foot. 

D=the  required  delivery  of  fresh  air  in  cubic  feet  per  hour. 

E  0.6 

—  =  D,  or ■  =  2,000  cubic  feet. 

P  0.0003 

The  primary  value  of  E  in  this  equation  varies  with  different  con- 
ditions. 

A  male  adult  (160  pounds)  exhales  0.72  cubic  foot  of  CO2  per  hour 
A  female  adult  (120  pounds)  exhales  0.60  cubic  foot  of  CO2  per  hour 
A  child  (  80  pounds)  exhales  0.40  cubic  foot  of  COa  per  hour 

Average  -  0.60 


VENTILATION  973 

These  values  vary  also  with  rest  or  work.  Thus,  factories  or  work- 
shops wliere  men  are  actively  employed  need  more  air  j)roportionat('ly. 
In  light  work  a  man  weighing  KiO  pounds  exhales  0,95  cubic  foot,  while 
at  hard  work  1.8-1  cubic  feet,  of  COg  per  hour. 

A 

The  formula  suggested  by  DeChauraont  is  D  = 

B-C 

A=:quantity  of  CO,  given  off  per  hour  per  person=:0,G  cu.  ft. 

B=:proposed  permissible  maximum  quantity  of  C'O^  per  1,000  cu. 
ft.=O.G  per  1,000. 

C=:amount  of  CO,  present  in  1,000  cu.  ft.  of  fresh  air  (0.3  cu.  fl. 
per  1,000  cu.  ft.). 

D=:amount  of  fresh  air  required  per  head  each  hour  to  maintain 
the  standard  B  expressed  in  thousands  of  cu.  ft. 

A  0.6  0.6 

Then  D  = or = =  2,000  cu.  ft. 

B-C  I      0.6-0.3  0.3 

of  air  needed  per  head  per  hour. 

In  case  of  individuals  doing  light  work  and  giving  off  0.95  cu,  ft. 
COo  per  hour,  then 

0,95 

D  = =  3,166  cu,  ft. 

0.6  -0.3 

This  is  a  convenient  formula,  for  it  may  be  used  not  only  to  deter- 
mine the  amount  of  fresh  air  required,  but,  knowing  the  other  factors, 
the  amount  of  cubic  feet  of  fresh  air  that  has  been  admitted  to  a  room 
per  head  may  be  determined.  Further,  probable  conditions  of  the  at- 
mosphere of  a  room  into  which  a  known  amount  of  fresh  air  has  been 
supplied  can  be  determined  by  finding  the  value  of  B,  thus: 

A 

B  =  — -f  C 

D 

Standards  of  Purity — Efficiency  of  Ventilation. — There  is  no  single 
standard  by  which  the  purity  of  the  air  or  the  efficiency  of  ventilation 
can  be  determined.  We  must  know  at  least  five  factors:  (1)  the  tem- 
perature; (2)  the  humidity;  (3)  the  movements  of  the  air;  (4)  the 
amount  of  CO,  it  contains;  (5)  dust,  bacteria,  gases,  etc.  In  a  general 
way  it  may  be  stated  that  the  best  results  are  obtained  when  the  tem-. 
perature  is  between  62°  and  68°  F, ;  the  moisture  not  above  50  per  cent, 
relative  humidity  (the  wet  bulb  under  70°  F,)  ;  the  movement  gentle, 
without  draft;  CO,  not  in  excess  of  6  parts  per  10,000;  and,  finally, 
freedom  from  excessive  dust,  bacteria,  gases,  etc.     Even  where  all  these 


974  VENTILATION  AND  HEATING 

factors  are  found  satisfactory  there  is  still  one  test  that  must  be  made 
in  order  to  be  sure  that  our  ventilating  system  is  nowhere  at  fault — that 
is  the  clinical  test.  Persons  occupying  the  room  should  suffer  from 
none  of  the  well-known  effects  produced  by  air  in  poor  condition.  The 
room  should  be  free  from  unpleasant  odors.  If  our  tests  seem  right,  but 
the  air  seems  close,  something  must  be  wrong  with  the  tests.  The  evi- 
dence of  our  senses  and  clinical  experience  cannot  be  disregarded. 

Where  any  ventilating  device  is  installed  it  is  readily  possible  to 
measure,  by  means  of  the  anemometer,  the  amount  of  air  passing  through 
inlets  or  outlets,  but  it  is  often  difficult  to  trace  the  course  of  the  air  in 
the  room.  The  measured  volume  of  air  passing  through  inlets  and  out- 
lets does  not  necessarily  determine  the  efficiency  of  ventilation  in  main- 
taining a  continuous  renewal  of  the  air  at  the  breathing  zone. 

The  volume  of  fresh  air  entering  the  breathing  zone  may  be  esti- 
mated with  considerable  accuracy  by  determining  the  proportion  of 
CO2  which  this  zone  contains.  The  air  supplied  is  inversely  as  the 
respiratory  contamination.  It  may  be  computed  from  the  following 
equation : 

vp 
A  = 

x-N 

v=the  CO2  produced  by  one  person;  that  is,  0.6  cubic  foot  per  hour. 

p=:the  number  of  people  in  the  room. 

x:=the  proportion  of  CO2  per  cu.  ft.  in  the  inside  air. 

N=the  proportion  of  CO2  per  cu.  ft.  in  the  outside  air  (0.0003). 

A=the  air  suppHed  to  the  room  in  cubic  feet  per  hour. 

0.6  p 
A  = 


X -0.0003 

It  will  be  seen  in  this  equation  that  vp  represents  the  CO2  produced 
by  occupants  and  x — N  represents  the  respiratory  contamination. 

In  such  computations,  as  also  in  the  direct  measurement  of  air  sup- 
plies, it  is  the  averages  which  are  most  important.  From  average  con- 
tamination we  may  find  average  air  supplies.  Erroneous  conclusions 
are  very  likely  to  be  drawn  from  single  determinations. 

Another  method  of  determining  the  efficiency  of  ventilation  is  in- 
tentionally to  vitiate  the  air  of  a  room,  and  then,  after  a  lapse  of  a 
certain  time,  find  how  far  ventilation  has  removed  the  carbon  dioxid. 
The  amount  of  air  which  has  entered  the  room  may  be  found  by  the 
formula : 

Pi  — a 

C  =  2.303  m  log 


VENTILATION  975 

C=amoimt  of  air  which  has  entered;  2.303  is  a  constant. 
ni=capacity  of  the  room, 

Pj=:the  amount  of  carbon  dioxid  orifjiiially  present  (found  by  experi- 
ment). 

P,=amount  of  carbon  dioxid  present  after  vitiation. 
a=amonnt  of  carbon  dioxid  in  the  ontsirle  air. 

The  Size  and  Shape  of  the  Room. — These  are  exceedingly  important 
factors  in  any  system  of  ventilation.  It  at  once  becomes  evident  that 
a  man  in  a  diving  suit  with  a  good  circulation  of  fresh  air  is  better 
off  than  occupants  of  a  spacious  but  poorly  ventilated  apartment  in 
which  the  air  has  become  vitiated  through  long  occupancy.  The  air  in 
a  small  cabin  on  a  steamship  may  be  infinitely  Ijetter  than  the  air  in 
a  large  room  of  a  country  home.  A  rathskeller  in  the  sub-basement  may, 
with  a  modern  system  of  ventilation,  have  much  better  air  than  that 
found  in  a  department  store  with  acres  of  floor  space  and  high  ceilings. 
In  other  words,  a  small  space  is  sufficient  if  properly  ventilated;  a  large 
space  inadequate  if  improperly  ventilated. 

The  size  of  rooms  for  dwellings  and  workshops  is  somewhat  of  an 
economic  question,  but  they  should  be  large  enough  to  allow  the  air 
to  be  replaced  two  or  three  times  an  hour  without  causing  perceptible 
drafts..  The  minimal  space,  in  accordance  with  this  standard,  is  about 
one-third  the  quantity  of  air  required  per  hour;  that  is,  from  700  to 
1,000  cu.  ft.  per  person.  The  amount  of  space  naturally  varies  with 
dwellings,  factories,  schools,  theaters,  prisons,  hospitals;  also  with  the 
length  of  time  the  room  is  occupied  and  the  nature  of  the  work  there 
carried  on.  Thus,  in  hospitals  where  ordinary  cases  are  cared  for,  from 
1,800  to  2,000  cu.  ft.  of  air  is  desirable  for  each  patient,  while  no  less 
than.  2,500  cu.  ft.  should  be  allowed  for  each  fever  patient.  Soldiers 
in  barracks  are  allowed  600  cu.  ft.  per  head,  and  the  limit  for  lodging 
houses  is  usually  fixed  at  from  300  to  500  cu.  ft.  The  U.  S.  Emigration 
Law  requires  500  cu.  ft.  per  head  in  the  steerage.  In  figuring  the 
amount  of  air  space  in  a  room  allowance  should  be  made  for  furniture, 
projecting  surfaces,  and  other  objects  which  diminish  the  available  space. 
The  table  on  page  976  from  Parkes  and  Kenwood  shows  the  attempts 
made  by  Great  Britain  to  fix  the  minimum  space  allowed  per  head  by 
legislation. 

A  little  consideration,  however,  will  show  that  such  regulation  of 
space  is  by  itself  of  little  value.  L'nless  there  be  movement  of  air, 
space  alone  is  futile.  However  large  the  space  may  be.  the  air  will  be- 
come impure  unless  fresh  air  circulates  through  it,  and  however  small 
the  space  the  air  may  be  kept  pure  by  sufficient  circulation. 

As  the  result  of  many  analyses  that  have  been  made  by  Haldane 
and  Osborne,  they  found  that  the  carbon  dioxid  bears  no  relation  to 


976 


VENTILATION  AXD  HEATIXG 


Minimum  Space 
per  Head 
in  Cu.  Ft. 

uthority 

Common    lodgmg    houses     ( sleep- 
rooms  j  

300 

400 
300 
250 

400 
500 

400 

between  9  p.  m. 

and   6   a.  m. 

600 

1,200 

80 

130 

60 

40 

72 
800 

Local      Government     Board 

Registered  lodging  houses — 

Rooms  occupied  by  day  and  night 
Rooms  occupied  by  night  only.  . . 

Xon-textile  workrooms 

(Model  By-Laws). 

Ditto. 
Ditto. 
Factory  Act,   1901. 

Ditto. 

Order    under    Factory    Act, 

Xon-textile  workrooms  during  over- 
time  

Underground  bakehouses 

Above-ground     bakehouses     where 
night  work  is  carried  on  by  arti- 
ficial  light   other    than   electric 
light 

Armv  Barracks 

1901 

■ 

Ditto. 

British  Army  Regulations. 

Army  hospital  wards 

Public  elementary  schools 

London  County  Council  Schools..  .  . 

Canal     boats      (persons     over     12 

years)  

Ditto. 

Educational  Department. 

London  County  Council. 

Local     Government     Board, 

Canal    boats     (persons    under    12 
Tears ) 

Regulations      imder      the 
Canal    Boat    Act,    1877. 

Seamen's   cabins 

:Merchant  Shipping  Act. 

Local  Government  Board, 
Model  Regulations  under 
the  Dairies,  Cowsheds, 
and  Milk-shops  Order. 

Cows  in  cowsheds 

the  amount  of  air  space  under  practical  conditions.  In  fact,  the  most 
highly  vitiated  air  found  was  in  a  room  with  an  air  space  of  about 
10,000  cu.  ft.  per  person. 

It  is  not  alone  the  air  space  but  the  shape  of  the  room  that  influences 
ventilation.  It  is  a  mistake  to  suppose  that  a  lofty  room  is,  therefore, 
an  airy  room,  for  a  stratum  of  warm  vitiated  air  soon  occupies  the  upper 
portion  of  such  a  space,  and,  so  far  as  good  air  is  concerned,  has  the 
effect  of  lowering  the  effective  height  of  the  ceiling  to  the  top  of  the  door 
or  nearest  outlet.  Anyone  may  convince  himself  of  this  fact  by  getting 
up  on  a  stepladder  in  a  room  with  a  high  ceiling,  improperly  ventilated, 
and  occupied  for  some  hours.  The  upper  stratum  of  air  in  such  rooms 
is  frequently  stifling.  Ordinarily  12  feet  is  high  enough  for  the  ceiling 
of  school  rooms,  museums,  hospitals,  etc.,  and  9  feet  for  the  rooms  of 
private  dwelling  houses.  TMiere  there  is  little  or  no  movement  of  the 
air  it  soon  becomes  offensive,  no  matter  -wliat  the  height  of  the  ceiling. 

Floor  space  is  more  important  than  lieight.  The  necessity  for  an 
abundant  floor  space  is  sho^-n  by  the  fact  that  a  small  inclosure-  with 
four  high  walls  and  without  a  roof,  if  crowded,  speedily  becomes  oppres- 
sive.    In  fact,  the  four  walls  are  not  necessary  to  demonstrate  this,  for 


VENTILATION  977 

"crowd  poisoning^'  in  the  open  air  npon  a  still,  warm  day  is  a  common 
experience.  Accordin<T  to  Harrington,  when  the  allowance  is  only  500 
cubic  feet  per  inhabitant,  the  floor  s|)ace  should  be  4"^  square  feet  {SYoX 
5^2).  Ill  the  English  barracks  the  soldiers  are  allowed  50  square  feet 
of  floor  space.  For  school  rooms  the  British  Educational  Code  requires 
120  cubic  feet  per  child  in  average  attendance  and  a  floor  space  of  10 
square  feet. 

Inlets  and  Outlets.— Whether  a  room  is  to  be  vcntilatiMl  by  natural  or 
mechanical  means,  proper  inlets  for  the  fresh  air  and  outlets  for  the 
vitiated  air  must  be  provided.  No  general  statement  as  to  the  best 
size  and  position  of  these  openings  will  apply  under  all  circumstances. 

Knowing  the  velocity  of  the  incoming  air,  the  area  of  the  inlets 
may  be  proportioned  so  as  to  permit  the  movement  of  the  necessary 
amount  of  air.  The  size  of  the  openings  under  specified  conditions  is, 
therefore,  a  matter  of  simple  arithmetic.  In  measuring  the  effective  area 
of  inlet  and  ouflet  tubes  allowance  must  be  made  for  friction  and  for 
the  guards  or  fretwork  which  protect  the  openings.  These  often  di- 
minish the  effective  area  about  one-half. 

In  order  to  provide  the  air  supply  of  30  cubic  feet  per  minute,  the 
inlet  registers  in  any  room  should  have  a  total  area  equal  to  0.1  square 
foot  per  capita.  The  air  ducts  must  be  so  constructed  as  to  lead  tho 
air  evenly  to  the  different  parts  of  the  building.  Each  room  should  be 
controlled  independently  by  individual  ducts  and  dampers. 

It  is  usually  better  to  admit  the  incoming  air  into  a  large  apart- 
ment through  a  number  of  openings  rather  than  through  one  large  one ; 
the  same  holds  true  of  outlets.  Outlets  should  be  about  the  same  size 
as  inlets  and  should  be  placed  wdth  reference  to  them. 

All  air  ducts  tend  to  become  soiled  with  dust  and  soot  and  should, 
therefore,  be  guarded  with  wire  gratings,  or  other  protecting  devices, 
and  they  should  also  be  cleaned  periodically;  further,  it  should  be  borne 
in  mind  that  ventilating  ducts  are  favorable  highways  for  mice,  roaches, 
and  vermin.  Inlets  opening  upon  the  floor  are  objectionable,  as  they 
collect  unusual  amounts  of  dirt  and  dust,  which  are  then  blown  into 
the  room. 

Whether  the  air  is  to  be  admitted  near  the  floor  and  taken  out  near 
the  ceiling  or  vice  versa  is  a  question  much  discussed  among  ventilating 
engineers.  Various  possibilities  are  shown  in  the  diagram.  Fig.  99. 
The  natural  course  of  the  warmed  vitiated  air  is  upward,  and  it  would 
seem  that  the  upward  system  has  advantages  over  the  downward  system. 
However,  a  little  study  wall  soon  convince  one  that  if  the  incoming  air 
is  warm  it  will  rise  at  once,  and  the  maximum  eflfieiency  will  be  lost 
at  the  breathing  line,  Avhich,  after  all,  is  the  essential  stratum  of  air 
in  the  room.  A  good  arrangement  under  certain  circumstances  is  to 
have  the  inlet  above  and  the  outlet  below — both  upon  the  same  side  of 


978 


VENTILATION^  AND  HEATING 


an  inner  wall.  For  crowded  spaces  the  best  system  is  doubtless  the 
upward  plan,  which  takes  advantage  of  the  natural  currents.  When 
this  plan  is  used,  the  air  should  be  admitted  to  various  parts  of  the 
room;  in  theaters,  under  each  seat. 

Outlet  ventilation  may  be  arranged  by  placing  a  bell  cover  or  glass 
globe  over  the  gas  lights  and  conveying  the  heated  air  thence  to  the 
outer  air  by  means  of  ascending  tubes.  This  not  only  removes  the 
products  of  combustion,  but,  if  the  outlet  tubes  have  a  sufficient  area, 


Fig.  99. — The  PosITIo^-  of  Inlets  and  Outlets,  and  theie  Relation  to  the 
Air  Currents  in  a  Room. 


affords  a  very  good  system  of  ventilation.  An  automatic  system  of 
taking  the  air  out  of  a  room  may  also  be  provided  by  placing  a  shaft 
either  around  the  chimney  flue  or  against  one  side  of  it.  The  column 
of  heated  air  in  the  ventilating  duct  will  rise  and  draw  the  vitiated 
air  out  of  the  room  with  which  it  is  connected.  The  same  may  be 
accomplished  by  placing  a  steam  Jet  or  a  gas  burner  within  the  ventilat- 
ing duct  to  create  a  draft. 

Ventilating  ducts  usually  extend  up  the  walls  of  the  Ijuilding  through 
the  roof,  and  should  be  in  as  direct  a  line  as  practicable.  The  openings 
upon  the  roof  may  be  protected,  by  an  umbrella-like  covering  against 
rain,  or  they  may  be  cowled  to  prevent  down  drafts.     It  appears  that 


VENTILATION 


979 


none  of  the  exhaust  cowls  cause  a  more  rapid  current  nf  air  than  prevails 
in  an  ojien  j)ii)e  under  similar  circumstances. 

Too  little  attention  has  hecn  paid  in  the  past  to  tlie  cleanliness  of 
the  air  supplied  to  our  buildings.  Fresh  air  inlets  are  often  located 
with  the  grossest  disregard  for  the  quality  of  the  incoming  air.  It  is 
not  uncommon  to  see  them  placed  on  the  sidewalk  level ;  or  facing  a 
vacant  piece  of  ground  that  is  swept  by  clouds  of  dust;  or  where  smoke, 
the  spent  gases  from  automobiles,  or  objectionable  odors  may  be  taken  in. 

Crowded  buildings  and  dusty  city  streets  will  often  render  it  im- 
possible to  secure  clean  air  from  the  outside  atmosi)here  without  re- 
sorting to  artificial  purification. 

External  Ventilation. — ]\Iodel  city  planning  should  provide  streets 
of  sufficient  widtii.  and  should  regulate  the  height  of  buildings  and  also 
limit   the    extent    upon 


which  the  land  may  be 
built,  so  as  to  allow  a 
free   circulation   of   air 
about  all  structures  and 
admit   a    flood    of   sun- 
shine for  at  least  a  few 
hours   during   the   day. 
Some  of  our  metropoli- 
tan     streets      resemble 
canyons  rather  than  city 
thoroughfares.  Crowded 
tenements,  facing  upon 
narrow      streets      with 

shafts  for  courts  and  backing  almost  directly  upon  the  houses  in  the 
rear,  and  further  surrounded  by  tall  buildings  which  prevent  the  free 
movements  of  the  outer  air,  and  shut  out  the  sunshine,  should  be 
prohibited,  w^hether  used  as  dwellings  or  workshops.  In  such  places 
the  ground  stays  moist,  the  air  becomes  stagnant,  natural  ventilation 
is  greatly  retarded,  and  the  conditions  upon  a  hot,  still,  moist  day  in 
summer  become  almost  intolerable. 

Generous  parks,  which  are  the  lungs  of  a  great  city,  should  be  scat- 
tered throughout  the  residential  and  business  sections;  playgrounds, 
boulevards,  and  small  open  areas  treated  as  parkings  not  only  beautify 
but  help  to  ventilate  a  city  and  add  to  the  comfort,  happiness,  and  health 
of  its  inhabitants. 

Natural  Ventilation, — Natural  ventilation  depends  upon  openings, 
such  as  doors  and  windows,  also  upon  the  air  that  comes  through  the 
pores  of  plaster,  brick,  and  stone  and  through  floors  and  ceilings  and 
through  the  cracks  and  crevices  about  window  frames,  etc. 

Natural  ventilation  depends  mainly  upon   three  principal  factors : 


Fig.   100. 


-^yI?{Dow  Ventilator. 


980 


VE"N"TILATIOT^  AND  HEATING 


(1)  perflation  and  aspiration;  (2)  gravity  or  thermal  circulation;  (3) 
diffusion  of  gases.  These  factors  constantl}'  operate,  whether  in  the 
presence  or  absence  of  any  mechanical  system.  In  fact,  most  schemes 
for  mechanical  ventilation  are  simply  an  application  of  these  natural 
forces. 

Perflation  is  simply  the  blowing  of  the  air  into  the  room  as  a  result 
of  the  movement  of  natural  air  currents.  Aspiration  is  the  sucking 
action  of  the  wind  which  draws  air  out  of  a  space  that  it  is  blowing 


Fig.  101. — DiAGKAMMATic  Sketch  of  Various  Pkovisio>'S  for  Vets' til  ation. 
A,  Sash  window  with  Hinckes-Bird's  arrangement.  B,  Hopper  sash-light 
falling  inwards.  C,  Louvred  outlets.  D,  McKinnell's  ventilator.  E,  Sheringham's 
valve.  F,  Tobin's  tube  (showing  valve  open).  G,  Ellison's  conical  bricks.  H  and 
I,  Grid  ventilators  below  floor  joists.  (From  "Hygiene  and  Public  Health,"  by 
Drs.  L.  C.  Parkes  and  H.  R.  Kenwood,  London.  H.  K.  Lewis,  Philadelphia,  Blakis- 
ton,  1911.) 


across.  Thus,  a  wind  blowing  across  an  open  tube  carries  along  with 
it  some  of  the  air  in  the  upper  part  of  that  tube.  This  causes  an  up- 
ward movement  of  the  air  in  the  tube.  The  same  phenomenon  takes 
place  when  wind  blows  by  a  window.  The  aspirating  action  of  air 
is  well  demonstrated  in  the  construction  of  an  ordinary  atomizer. 

The  air  is  kept  in  almost  constant  motion  through  changes  in  tem- 
perature. Warm  air  expands,  is  therefore  lighter,  and  rises.  This  is 
a  familiar  phenomenon  in  the  hot-air  balloon.  Thermal  circulation, 
though  often  imperceptible,  is  constantly  in  operation,  especially  in  oc- 
cupied rooms.     Even  in  calm  weather  there  is  considerable  ventilation 


VENTILATION  !)S1 

owing  (o  dirt'ereiiL'C's  in  temperature,  aud  hence  differeiites  in  pressure  be- 
tween the  air  of  the  room  and  the  outside. 

More  air  than  is  commonly  supposed  enters  or  Jca\es  a  ruuni  tlirtaigh 
the  cracks  about  doors  and  windows  and  other  crevices.  From  the 
standpoint  of  natural  ventilation  it  is,  therefore,  not  advisable  to  have 
windows  fit  too  snugly.  The  use  of  weather-strips,  tongue  and  grooved 
metal  strips,  and  similar  devices  to  keep  out  the  cold  air  saves  coal 
bills,  but  is  a  considerable  hindrance  to  natural  ventilation. 

Under  certain  conditions  very  considerable  amounts  of  air  pass 
through  the  building  materials  used  in  the  construction  of  walls,  floors, 
and  ceilings.  Ordinary  mortar  is  most  permeable,  then  comes  brick, 
then  sandstone,  next  plaster  of  Paris,  while  enamel  and  tile  are  im- 
pervious. Under  a  pressure  of  108  millimeters  of  water  the  following 
amounts  of  air  pass  in  one  hour  through  one  square  meter  of : 

Mortar    3,264  liters 

Plaster  of  Paris 146 

Bricks    312-1,396       " 

Sandstone 426-    496 

A  pressure  of  108  millimeters  of  water  is  equivalent  to  the  pressure 
of  a  strong  wind.  The  amount  of  air  that  Avill  pass  through  porous 
materials  varies,  of  course,  with  the  temperature,  moisture,  and  other 
factors. 

Marker  and  Schultze,  in  their  researches  on  the  spontaneous  ventila- 
tion of  stables,  found  that  the  following  interchange  of  air,  occurred 
per  hour  over  one  square  yard  of  free  wall  at  9.5°  F.  difference  of 
temperature : 

With  walls  of  sandstone 4.7  cu.  ft. 

Quarried   limestone ._ 6.5    "     " 

Brick    ' .     7.9    "     " 

Tufaceous   limestone 10.1    "     " 

Mud    14.4    "     " 

It  is  possible  to  force  sufficient  air  through  an  ordinary  brick  to 
deflect  the  flame  of  a  candle  on  the  other  side.  This  demonstration 
is  usually  accomplished  by  coating  the  edges  and  exposed  portions  of 
the  brick  with  sealing-wax  and  arranging  glass  funnels  on  either  side. 
Air  forced  with  a  bellows  through  one  funnel  may  be  measured  either 
as  to  its  amount  or  velocity  as  it  comes  out  of  the  opposed  funnel-. 

•  Natural  ventilation  is  better  in  winter  than  in  summer,  owing  to 
greater  differences  in  temperature.  It  may  be  almost  nil  on  a  hot 
calm  day.  Too  much  moisture  in  the  air  of  a  room  settles  upon  the 
surfaces  and  thus  stops  the  pores  of  building  materials,  and  also  prevents 
the  escape  of  carbon  dioxid.  Eain  has  a  similar  effect  on  the  outside. 
An  ordinary  brick  w411  soak  up  a  pint  of  water.  Ventilation  through 
the  walls  is  also  hindered  by  oil  and  enamel  paints  and  by  wall-paper. 


982  VENTILATION  AND  HEATING 

Outside  obstacles,  such  as  excessive  foliage  and  narrow  streets,  are  also 
considerable  factors. 

Natural  ventilation  may  be  greatly  favored  by  simple  devices.  This 
may  be  demonstrated  by  placing  a  lighted  candle  in  a  bottle  with  a 
narrow  neck.  The  flame  soon  dies  out,  but  by  placing  a  partition  in 
the  neck  of  the  bottle,  so  that  the  products  of  combustion  will  escape 
on  one  side  and  the  fresh  air  enter  upon  the  other,  natural  ventilation 
proceeds  so  that  the  candle  remains  lighted.  There  are  numerous  simple 
devices  that  may  be  placed  at  the  top  or  bottom  of  windows  Avhich  favor 
the  entrance  of  fresh  air  or  the  exit  of  vitiated  air.  An  arrangement 
shown  in  Fig.  100  gives  very  satisfactory  results.  One  of  the  upper 
window  panes  may  be  valved  or  fitted  with  a  fan  to  permit  the  entrance 
of  fresh  air  or  the  exit  of  vitiated  air.  A  somewhat  similar  arrangement 
used  at  Fairfield,  Conn.,  is  shown  in  Fig.  102.  Openings  in  ceilings, 
ridged  ventilators,  Sheringham's  valves,  Ellison's  bricks,  Tobin's  tubes, 
and  Stevens'  drawer-ventilator  are  all. useful  accessory  devices  to  aid 
natural  ventilation. 

Ellison's  bricks  are  bricks  with  conical  perforations,  the  widened 
end  of  the  conical  opening  debouching  on  the  interior  of  the  wall.  The 
holes  through  the  bricks  are  about  2/10  inch  in  diameter  externally 
and  114  inches  internally. 

Tobin's  tube  consists  of  a  large  upright  tube,  about  5  or  6  feet  high, 
which  conducts  outside  air  into  the  room  through  the  wall. 

The  pheringham  valve  is  a  small  vertical  flap  door  in  the  wall  near 
the  ceiling,  balanced  by  a  counterpoise,  and  hinged  so  as  to  fall  forward 
toward  the  room;  it  is  cased  in  at  the  sides  and  front,  so  that  the 
current  can  only  pass  upward. 

Stevens'  drawer  ventilator  is  like  a  drawer  lacking  its  back.  It  is 
made  to  fit  into  a  hole  in  the  wall  in  such  a  way  that  when  the  drawer 
is  shut  the  hole  is  airtight,  and  when  the  draAver  is  open  air  can  enter. 

Hinckes-Bird  ventilator  is  made  of  the  opening  between  two  ordi- 
nary window  sashes  when  the  louver  is  raised,  and  the  lower  opening 
closed  by  means  of  a  specially  high  sill  or  by  an  accurately  fitting  block 
of  wood. 

These  various  devices  should  be  protected  with  valves  so  that  they 
may  be  regulated.  Sometimes  it  is  advisable  to  provide  gauze  or  cot- 
tion  filters  to  keep  out  the  dust. 

Natural  ventilation  is  greatly  aided  by  means  of  warming  the  air 
in  the  outlet  duct.  The  best  example  of  this  is  the  open  fireplace,  or 
other  devices  for  warming  the  air  in  outlet  tubes  already  referred  to. 

In  dwelling  houses,  where  there  is  no  overcrowding,  natural  ventila- 
tion through  cracks  and  crevices,  through  walls  and  windows,  is  or- 
dinarily sufficient  for  practical  purposes. 

Wherever  possible,  open  windows  are  the  best  and  simplest  means 


A^ENTTLATfOX 


983 


of  ventilating  a  room.  Any  system  of  mechanical  ventilation  at  best 
is  ccstly  and  frequently  unsatisi'aetory.  Open  windows  arc  cheap  and 
adequate,  hut  the  limitations  and  disadvantages  of  natural  ventilation 
are  obvio\is,  and,  therefore,  we  are  frequently  rccpiired  to  resort  to 
mechanical  means. 

The  Fairfield  Sj/.sfein. — An  ingeniinis  and  simple  sy .-tem  of  modi- 
fied window  ventilation,  devised  by  ^Ir.  S.  H.  \Mieeler  of  Bridgeport, 
Conn.,  and  first  installed  at  the  Sherman  School.  Fairfield,  Conn., 
eliminates  the  disadvantages  of  the 
ordinary  natural  ventilation  while  re- 
taining some  of  its  peculiar  advan- 
tages. According  to  this  plan  fresh 
air  is  admitted  through  the  windows, 
but  direct  drafts  are  prevented  by 
placing  slanting  window  boards  on  the 
sashes  so  that  the  incoming  air  is  de- 
flected upward  and  mixed  with  the 
general  gocxl  air  of  the  room.  This 
incoming  current  is  furthermore  tem- 
pered by  placing  the  radiators  used 
for  direct  heating  under  the  windows 
and  by  making  these  radiators  large 
enough  to  extend  over  the  entire 
width  of  all  the  windows.  Finally,  a 
duct  is  provided  for  the  egress  of 
warm,  vitiated  air  passing  from  near 
the  ceiling  of  each  room  to  the  outer 
air,  the  upw^ard  current  in  this  duct 
being  maintained  by  the  temperature 
difference  between  the  outdoor  and  in- 
door air. 

In  industrial  establishments  where 
crowding  is  not  great  the  same  general  principle  has  been  applied  by 
providing  special  air  inlets  to  individual  rooms  with  heating  coils  placed 
directly  in  front  of  them. 

The  King  System. — An  interesting  system  of  ventilation,  known 
as  the  King  system,  is  in  use  in  cow  stables,  which  secures  much  better 
air  conditions  than  those  to  wliicli  human  beings  are  frequently  ex- 
posed. Louvred  openings  at  the  ridge  pole  furnish  an  exit  for  the  warm, 
vitiated  air,  while  fresh  air  is  admitted  through  ducts  in  the  walls. 
These  ducts  open  to  the  outside  at  the  bottom  of  the  wall  and  to  the 
inside  of  the  stable  four  or  five  feet  above  the  floor,  the  inflowing  cur- 
rent of  air  being  induced  by  the  difference  in  temperature  between  the 
stable  and  the  outer  air. 


Fig.  102. — Fairfield  System 
Window  Vextilatiox. 


984  VENTILATION  AND  HEATING 

Mechanical  Ventilation. — All  "artificial"  systems  of  ventilation  de- 
pend upon  one  of  three  methods:  (1)  plenum  system,  which  consists 
in  the  mechanical  propulsion  of  air  into  the  room;  (2)  the  vacuum 
system,  which  consists  of  the  mechanical  extraction  of  the  air  out  of 
the  room;  (3)  a  combination  of  the  plenum  and  vacuum  systems. 

Air  may  be  propelled  into  a  room  either  by  means  of  a  warming 
apparatus  or  by  mechanically  propelling  the  air  by  means  of  rotary  fans. 
Every  heating  apparatus  is  secondarily  a  ventilating  device,  especially 
hot-air  furnaces,  and  the  direct-indirect  systems  in  use  with  hot-water 
or  steam  pipes.  Stoves,  open  fireplaces,  and  similar  heating  arrange- 
ments are  also  good  ventilating  devices  in  that,  if  well  constructed,  they 
take  out  large  quantities  of  air  from  the  room. 

For  the  mechanical  propulsion  of  air  either  fans  or  "blowers"  are 
used.  These  may  be  run  by  electricity,  gas,  or  steam  power.  The  air 
is  forcibly  driven  through  ducts  to  where  it  is  wanted.  Without  this 
system  of  mechanical  ventilation  the  great  office  buildings,  basement 
restaurants,  large  passenger  steamships,  and  other  modern  structures 
would  not  be  habitable. 

If  dependence  is  placed  solely  upon  drawing  the  vitiated  air  out  of 
a  room  we  are  leaving  to  chance  where  the  fresh  air  is  coming  from 
to  replace  it.  In  other  words,  it  is  impossible  when  the  so-called  vacuum 
system  alone  is  used  to  control  the  source  of  the  fresh  air  and  insure 
its  purity.  Exhaust  systems  of  ventilation  are  therefore  of  value  only 
in  connection  with  a  positive  air  supply.  As  a  rule,  all  well-ventilated 
structures  depend  neither  upon  the  plenum  nor  the  vacuum  systems 
alone,  but  combine  the  two. 

A  complete  plenum  system  consists  of  (1)  screens  which  strain  out 
dust  and  large  particles,  (2)  a  fan  to  force  the  air  through  the  system, 
(3)  tempering  coils  to  heat  the  air  to  a  moderate  degree — 50°  to  70° 
F.,  (4)  spray  chambers  to  himiidify  and  wash  the  air,"  (5)  baffle  plates 
to  remove  excess  moisture,  finally  ( 6 )  heating  coils  to  bring  the  tem- 
perature of  the  air  to  the  final  point  desired. 

The  disadvantages  of  the  mechanical  systems  of  ventilation  are  that 
they  are  expensive  as  to  first  installation  and  as  to  maintenance ;  further- 
more, they  are  most  effective  when  the  doors  and  windows  of  the  room 
are  kept  closed.  The  advantages  are  that  they  are  effective  in  all  kinds 
of  weather,  and  require  less  space  for  the  air  ducts  than  natural  ven- 
tilation. 

HEATING 

Heating  and  ventilation  go  hand  in  hand.  A  large  share  of  the 
cost  of  heating  is  chargeable  to  ventilation,  hence,  if  ventilation  is 
overdone,    it   is   an   unnecessary   expense.      The   artificial   warming   of 


HEATINCt  985 

houses  has  a  similar  at-tion  to  clothing.  "Burning  fuel  in  the  furnace 
saves  fuel  in  the  human  machine/'  It  especially  saves  the  strain  upon 
the  metabolism  of  the  young,  the  old,  and  the  feeble.  The  tendency 
in  winter  is  to  wear  too  much  clothing  indoors.  This  results  in  coddling 
— that  is,  loss  of  vasomotor  tone  of  our  peripheral  capillary  circulation, 
from  the  constant  bathing  of  the  skin  in  a  still,  Avarm,  moist  layer  of  air. 
This  in  turn  results  in  susceptibility  to  drafts  and  liability  to  colds.  It 
is  quite  unnecessary  to  wear  heavy  winter  clothing  in  rooms  and  offices 
properly  heated  and  ventilated.  Dependence  should  be  placed  on  warm 
overcoats  when  going  out  of  doors. 

Most  of  our  American  houses  are  overheated  with  abnormally  dry 
air  in  the  winter  time.  This  is  a  mischievous  combination.  It  causes 
excessive  evaporation  from  the  skin  and  mucous  membranes,  which  gives 
rise  to  a  feeling  of  chilliness.  It  also  causes  dryness  of  the  skin  and 
mucous  membranes,  irritation  of  the  throat,  and  thus  predisposes  to 
colds  and  respiratory  infections.  Warm  dry  air  does  not  give  the  same 
sense  of  warmth  and  comfort  afforded  by  a  cooler  moist  air.  Thus,  air 
at  62°  to  65°  F.  and  a  relative  humidity  of  70  per  cent,  feels  warmer 
than  air  at  70°  to  72°  F.  and  a  relative  humidity  of  50  per  cent,  or 
less.  Furnace  heat,  hot-water,  and  steam  pipes  tend  to  dry  the  air, 
and  thus  it  becomes  necessary  to  overheat  our  offices  and  houses  be- 
fore they  become  comfortable. 

Heat  is  measured  by  the  British  iliermal  unit  (B.  T.  V.),  which  is 
the  quantity  of  heat  required  to  raise  the  temperature  of  a  pound  of  pure 
water  one  degree  at  its  point  of  maximum  density,  39°  F.  The  French 
thermal  nmt  is  the  Calorie  and  is  the  amount  of  heat  required,  to  raise 
one  kilogram  of  water  one  degree  centigrade  at  corresponding  tempera- 
ture (4°  C).    One  calorie  equals  3.968  B.  T.  U. 

Heat  travels  by  radiation;  conduction,  and  convection.  All  three 
routes  are  constantly  in  operation  in  any  system  of  heating.  Thus,  with 
an  open  fireplace  the  heat  radiates  in  straight  lines  to  the  nearest 
objects,  where  they  are  absorbed  or  reflected,  just  as  light  passes  through 
space  independent  of  the  atmosphere.  That  is  why  our  face  toasts  and 
our  back  freezes  before  an  open  fireplace.  The  heat  absorbed  by  any 
object  passes  through  that  object  from  particle  to  particle  by  conduc- 
tion. Most  metals  are  good  conductors;  air  is  a  very  poor  conductor 
of  heat.  Convection  is  the  process  by  which  heat  is  communicated 
through  gases  and  liquids  as  a  result  of  their  mobility.  Thus,  the  air 
is  warmed  by  our  bodies,  by  liot-water  pipes,  and  by  all  lieated.  objects, 
and  therefore  rises  and  establislies  convection  currents. 

There  are  frve  main  metliods  of  heating:  (1)  open  fires;  (2)  stoves; 
(3)  hot  air  furnaces;  (4)  hot-water  or  steam  pipes;  (5)  electricity. 
The  control  of  the  temperature  of  a  building  is  more  a  question  of  man- 
agement than  of  the  svstcm  used. 


986  VENTILATION  AND  HEATING 

Open  Fires. — The  open  fireplace  heats  mainly  through  direct  radia- 
tion. It  has  the  advantage  of  being  cheerful  and  a  good  ventilator. 
It  has  the  disadvantage  of  being  wasteful  and  very  unequal  if  depended 
upon  as  the  chief  source  of  heat. 

Parkes  and  Kenwood  estimate  that,  in  an  ordinary  medium-sized  sit- 
ting room  Avith  an  ordinary  fire,  from  10,000  to  15,000  cu.  ft.  of  air 
are  drawn  up  the  chimney  in  an  hour,  the  current  being  generally 
from  3  to  6  ft.  a  second.  "As  ventilating  agents,"  say  Notter  and 
Eirth,  "the  best  types  of  open  fireplace  cause  some  2,600  cu.  ft.  of  air 
to  pass  up  the  flue  per  pound  of  coal  consumed,  or  the  passage  of  about 
18,000  cu.  ft.  up  the  cliimney  per  hour."  A  fireplace  will  change  the 
air  of  an  ordinary  room  in  one  or  two  hours. 

Franklin  Stoves. — Franklin  stoves  consist  of  coal  fires  in  a  cast-iron 
stove,  the  products  of  combustion  being  carried  off  through  a  stove- 
pipe. Such  stoves,  standing  free  in  the  room,  are  very  efficient,  so  far 
as  heating  is  concerned,  and  also  favor  ventilation  through  the  circu- 
lation of  air,  which  is  drawn  into  the  stove  to  support  the  burning  of 
the  fuel.  The  heating  of  the  room  is  unequal,  as  it  depends  largely 
upon  radiation  and  somewhat  upon  convection.  Such  stoves  are  apt 
to  become  red-hot,  in  which  case  it  is  believed  they  allow  carbon 
monoxid  to  pass  through  the  cast  iron.  The  organic  dust  in  the  air 
falling  upon  the  hot  stove  is  burned  and  produces  an  unpleasant  smell. 

Open  Gas  and  Oil  Heaters. — Open  gas  and  oil  heaters  without  flues 
to  carry  off  the  products  of  combustion  are  objectionable,  from  a  sanitary 
standpoint.  These  heaters  consist  of  a  variety  of  designs.  The  heat  is 
imparted  to  the  room  by  convection  and  also  by  radiation.  Such  devices 
may  contaminate  the  air  with  carbon  monoxid  from  leakage  or  from 
unconsumed  gas,  or  from  the  formation  of  soot,  which  becomes  in- 
candescent. Such  heaters  also  contaminate  the  room  with  COg  and  other 
products  of  combustion.  The  "rubber"  tube  feeding  these  gas  heaters 
often  leaks,  and  there  is  frequently  a  perceptible  odor  of  gas  in  rooms 
where  these  devices  are  used.  Open  heaters  burning  oil  are  less  objec- 
tionable than  those  using  gas. 

Hot-air  Furnaces. — A  hot-air  furnace  consists  of  a  coal  fire  which 
heats  a  series  of  tubes  or  plates  in  the  dome  of  the  furnace.  The  air, 
which  is  usually  taken  from  the  outside  through  a  duct,  flows  into  this 
dome,  where  it  comes  in  contact  with  very  hot  surfaces,  and  is  thus 
conducted  by  thermal  circulation  through  a  series  of  ducts  into  the 
rooms  of  the  house.  A  hot-air  furnace  of  this  kind  constantly  pumps 
fresh  air  into  the  house  and  is,  therefore,  a  vejy  efficient  system  of 
ventilation.  The  objection  to  the  hot-air  furnace  is  that  the  air  is  ex- 
cessively dry  and  often  partly  "burned"  in  passing  over  the  heated 
surfaces  in  the  dome.  The  odor  caused  by  the  burning  of  the  organic 
particles  in  the  air  may  frequently  be  noticed  in  houses  heated  with  a 


HEATING  987 

hot-air  furnace.  Tlie  heated  air  entering  the  rooms  is  usually  allowed 
to  escape  as  it  will.  In  order  to  overcome  the  disadvantage  of  the  dry- 
ness of  the  air  furnished  by  the  hot-air  furnace,  water  pans  are  always 
provided,  from  which  the  water  is  supposed  to  evaporate.  These  pans 
are  ridiculously  small  and  cannot  possibly  furnish  sufficient  moisture 
for  the  great  volume  of  air  constantly  passing  through  one  of  these 
furnaces.  For  instance,  according  to  Harrington,  air  at  25°  F.  satu- 
rated with  moisture  and  then  heated  to  70°  F.  would  need  lialf  a  pint 
in  every  thousand  cubic  feet  to  give  it  a  humidity  to  05  per  cent.  In- 
gersoll  calculates  that  a  house  containing  17,000  cu.  ft.  of  space  would 
require  for  a  relative  humidity  of  40  per  cent,  at  70°  F.  in  the  air  already 
containing  20  per  cent,  humidity  and  changed  once  an  hour,  about  15 
gallons  of  water  a  day.  The  little  water  pockets  in  the  average  hot  air 
furnace  are  insignificant  and  inadequate. 

The  air  from  a  hot-air  furnace  is  drier  than  that  furnished  by 
any  other  system  of  heating  or  ventilation.  Thus,  an  out-of-door  air 
in  winter  at  a  temperature  of  0°  F.,  with  a  relative  humidity  of 
50  per  cent.,  when  heated  to  70°  F,,  will  have  a  relative  humidity  of  only 
3  per  cent.  This  is  drier  than  the  air  of  the  driest  climate  known, 
which  is  seldom  less  than  30  per  cent.  The  average  relative  humidity 
in  Death  Valley,  Calif.,  is  23  per  cent.;  at  Yuma,  Arizona,  it  is  35  per 
cent,  during  the  driest  month  of  the  year;  at  Santa  Fe,  Xew  Mexico, 
it  is  29  per  cent.;  and  at  Pueblo.  Colorado,  it  is  38  per  cent.  It  is  not 
unusual  for  the  excessively  dry  air  of  a  furnace-heated  house  to  cause 
the  woodwork  to  shrink  and  fall  apart,  the  bindings  of  books  to  crack, 
etc.  Living  in  such  an  atmosphere  is  not  normal  and  must  be  harmful 
(page  nr?). 

Hot-water  and  Steam  Pipes. — This  is  a  very  simple  and  effective 
system  of  heating  buildings.  The  hot-water  system  is  especially  appli- 
cable to  small  buildings  and  steam  pipes  to  large  buildings.  The  hot 
water  is  more  readily  controllable  than  steam,  which  has  a  tendency 
to  overheat.  Special  furnaces  are  found  on  the  market  to  heat  the 
water  or  to  generate  the  steam,  which  then  circulates  through  pipes  to 
the  rooms  where  wanted.  If  the  hot-water  radiators  or  steam  coils 
are  exposed  directly  in  the  room,  the  system  is  known  as  the  "direct." 
In  the  indirect  system  the  hot-water  pipes  or  steam  coils  are  placed 
in  a  special  box  where  the  air  from  the  outside  is  heated,  and-  this 
heated  air  flows  by  thermal  circulation  through  ducts  into  the  rooms 
Avhere  wanted.  The  best  practice  uses  a  combination,  namely,  the  direct- 
indirect  system.  In  the  direct  system  the  air  of  the  room  is  simply 
heated  and  reheated  over  again,  while  in  the  direct-indirect  system  the 
fresh  warmed  air  is  constantly  pumped  into  the  building  and  it  is, 
therefore,  an  efficient  method  of  ventilation.  In  both  these  systems 
the  air  is  abnormally  dried,  just  as  it  is  in  the  hot-air  furnace,  though 


988  VENTILATION  AND  HEATING 

not  to  the  same  degree.  Actual  tests  during  the  winter  time  of  the  air 
of  a  steamheated  office  in  a  modern  building  at  Topeka,  Kansas,  showed 
the  average  indoor  relative  humidity  to  be  23  per  cent.,  with  an  average 
temperature  of  72°  F.  The  outdoor  humidity  at  the  same  time  aver- 
aged 82  per  cent. 

Electric  Heating. — Electric  heating  is  clean,  easily  regulated,  but 
expensive.  It  has  the  disadvantage  of  being  insufficient  as  a  ventilat- 
ing device,  unless  special  inlets  and  outlets  are  provided.  Electric 
heaters  consist  simply  of  resistance  coils  which  heat  the  room  mainly 
through  radiation  and  convection. 

The  Cooling  of  Rooms. — Much  attention  has  been  given,  through 
necessity,  to  the  heating  of  rooms  in  winter  time,  but  heretofore  little 
attention  has  been  given  to  the  cooling  of  rooms  in  the  hot  season. 
It  is  quite  as  practicable  to  cool  rooms  as  it  is  to  heat  them,  and  some- 
times quite  as  important  to  health. 

The  principle  of  practically  all  cooling  devices  depends  upon  the 
fact  that  when  a  fluid  evaporates  to  its  gaseous  state  it  absorbs  a  con- 
siderable amount  of  heat — latent  heat.  *  This  heat  is  taken  from  the 
surrounding  objects  which,  therefore,  become  correspondingly  cold.  Cold 
may  also  be  produced  by  the  expansion  of  air.  This  was  pointed  out  in 
1845  by  Joule.  Thus,  if  a  jet  of  air  at  60°  F.  were  blown  into  a  room 
under  pressure  of  10  inches  of  mercury  above  the  ordinary  barometric 
pressure,  the  sudden  expansion  of  this  compressed  air  would  reduce 
it  to  a  theoretical  temperature  of  13.3°  F.  below  freezing.  This  prin- 
ciple of  dynamic  cooling  has  been  applied  to  refrigerators. 

Ammonia  gas  is  now  almost  universally  employed  in  freezing  ma- 
chines. This  gas  is  readily  condensed  into  a  liquid.  The  compressed 
gas  is  allowed  to  expand  into  tubes,  and  the  cold  thus  produced  utilized 
directly;  more  frequently  an  indirect  method  is  used  by  which  the  ex- 
panding gas  first  cools  a  freezing  mixture  consisting  of  a  saturated  solu- 
tion of  calcium  chlorid;  this  chilled  brine  is  then  pumped  through  a 
series  of  pipes  to  the  refrigerator  or  apartment  where  it  is  desired. 
Humidifiers  and  air  washers  are. also  used  to  cool  rooms  and  buildings. 

A  simple  method  of  cooling  a  room  is  by  the  rapid  evaporation  of 
water.  Dr.  Manning  was  able  satisfactorily  to  cool  a  large  room  in  the 
Government  Printing  Office  at  Washington  by  blowing  air  by  means 
of  an  electric  fan  over  a  moist  sheet.  This  sheet,  about  a  yard  wide, 
was  hung  near  the  ceiling,  and  constantly  wetted  by  a  stream  of  water 
flowing  over  it. 

The  Mt.  Sinai  Hospital  in  New  York  provides  a  specially  cooled 
room  for  babies  with  summer  complaint,  in  view  of  the  direct  relation 
between  heat  and  infant  mortality. 


REFERENCES  989 


BEFEBENCES 


Ward,  R.  D.  :  "Climate,  Considered  Especially  in  Relation  to  Man."  Put- 
nam, N.  Y.,  1908. 

Richards,  E.  H..  and  Woodman,  A.  G. :  "Air,  Water  and  Food."  Wiley  & 
Sons,  N.  Y..  1900. 

Moore,  W.  L.  :  "Descriptive  Meteorology."     D.  Applcton  &  Co.,  N.  Y.,  1911. 

Macfie,  D.  C.  :    "Air  and  Health."    E.  P.  Button  &  Co.,  1909. 

Carpenter.  R.  C.  :     "Heating  and  Ventilation  of  Buildings,"  1915. 

Hoffman,  J .  D.,  and  Raber,  B.  F.  :  "Handbook  for  Heating  and  Ventilat- 
ing Engineers,"  1913. 

Report  of  Com.  on  Standard  Methods  for  the  Examination  of  Air.  Jour. 
Am.  Public  Health  Assn.,  VII,  1,  Jan.,  1917. 


SECTION  VII 
SOIL 

CHAPTER   I 
GENEEAL  CONSIDERATIONS 

The  upper  layer  of  the  earth's  crust,  known  as  the  soil,  is  derived 
from  the  disintegration  of  rocks  and  the  decay  of  animal  and  vegetable 
matter  of  all  kinds.  It  varies  from  a  few  inches  in  depth  to  several 
feet.  The  sub-soil  also  varies  from  a  few  feet  to  hundreds  of  feet  in 
depth,  to  hard  pan  or  an  impermeable  stratum. 

From  a  sanitary  standpoint  the  soil  must  be  regarded  as  our  friend 
rather  than  our  enemy.  Enormous  quantities  of  organic  matter  and 
infections  of  all  kinds  find  their  final  resting  place  in  the  soil  and 
are  there  disposed  of  and  rendered  harmless  by  nature's  beneficent  proc- 
esses. In  fact,  a  closer  study  of  the  functions  of  the  superficial  layer 
of  the  soil  shows  that  it  is  not  only  the  organ  of  digestion  and  respira- 
tion of  the  earth,  but,  like  the  liver,  it  is  the  great  organ  in  which  toxic 
substances  of  all  kinds  are  neutralized  or  destroyed. 

The  sanitarian  does  not  look  upon  the  soil  as  dead  and  inert,  but 
rather  as  a  living  being,  for  it  presents  many  of  the  vital  phenomena 
that  characterize  life:  digestion,  metabolism,  assimilation,  growth,  res- 
piration, motion,  and  even  reproduction.  The  soil  breathes,  it  absorbs 
ox3'gen  and  exhales  carbon  dioxid;  it  is  capable  of  digesting  and  as- 
similating vast  amounts  of  organic  matter  by  a  complex  process  of 
metabolism;  the  waste  products  are  excreted.  If  these  wastes  are  re- 
tained the  soil  may  be  choked  or  killed  by  an  accumulation  of  its  own 
poison — a  sort  of  auto-intoxication.  The  soil,  like  all  li^ang  things,  de- 
mands water,  but  it  may  be  drowned  by  an  excess.  A  water-logged  soil 
dies  in  very  much  the  same  sense  that  an  individual  dies  who  has  sup- 
pression of  urine.  Sedgwick  speaks  of  the  "living  earth"  in  the  sense 
that  it  is  teeming  with  life;  bacteria,  molds,  amebae,  and  many  of 
the  primitive  forms  of  the  animal  kingdom,  as  well  as  worms,  insects, 
snakes,  birds,  rodents,  and  many  other  animals,  make  their  temporary  or 
permanent  homes  in  the  upper  layers  of  the  earth.  Earthworms  by 
their  plowing  action,  so  beautifully  shown  by  Darwin  in  1881,  constantly 
turn  over  the  upper  layers  of  the  earth.     The  soil,  therefore,  is  in  con- 

991 


992  GENERAL  CONSIDEEATIONS 

stant  peristalsis,  which  helps  its  digestive  functions.  The  rise  and  fall 
of  the  ground  water  is  analogous  to  the  movements  of  the  diaphragm  and 
assists  the  respiratory  functions  of  the  soil. 

Classification  of  Soils. — Soils  are  variously  classified,  depending  upon 
the  amount  of  sand,  gravel,  clay,  loam,  humus,  peat,  muck,  rock,  alkali, 
etc.,  which  they  contain.  The  difference  between  a  sandy  and  gravelly 
soil  depends  mainly  upon  the  size  of  the  particles.  These  soils  interest 
the  sanitarians  because  hookworms  live  and  flourish  in  them  better  than 
they  do  upon  clay  or  rock  formation. 

Clay  exists  in  particles  of  the  smallest  possible  size.  It  is  very 
cohesive,  possesses  a  high  degree  of  plasticity,  and  plays  a  very  im- 
portant part  in  determining  the  fertility  of  soils,  their  texture,  and 
their  capacity  for  holding  water.  Its  plasticity  is  due  to  the  presence 
of  a  small  proportion  of  hydrated  silicate,  and  is  modified  very  greatly 
by  the  addition  of  less  than  a  hundredth  part  of  caustic  lime.  It  is 
exceedingly  impermeable  to  water,  and  when  wet  dries  with  great  slow- 
ness. Clay  may  be  regarded  as  a  plastic  colloid,  but  its  special  proper- 
ties are  only  seen  when  a  certain  amount  of  water  is  present.  The 
separate  particles  of  clay  are  so  small  that,  when  placed  in  water,  they 
assume  a  state  of  Brownian  movement  and  sink  only  very  slowly  in 
spite  of  their  high  specific  gravity.  Traces  of  electrolytes  have  a  pro- 
found effect  on  these  properties;  small  quantities  of  acids  or  salts  cause 
the  temporary  loss  of  plasticity,  impermeability,  and  the  property  of 
remaining  long  suspended  in  water  without  settling;  the  clay  is  now 
said  to  be  flocculated.  The  change  can  be  watched  if  a  small  quantity 
of  any  flocculating  substance  is  added  to  the  turbid  liquid  obtained  by 
shaking  clay  with  water;  the  minute  particles  are  then  seen  to  unite 
with  larger  aggregates  which  settle,  leaving  the  liquid  clear.  There  is, 
however,  no  permanent  change;  deflocculation  takes  place  and  the  orig- 
inal properties  return  as  soon  as  the  flocculating  agent  is  washed  away. 
Alkalies  (caustic  soda,  caustic  potash,  ammonia,  and  their  carbonates) 
deflocculate  clay,  causing  it  to  remain  suspended  in  water  for  long 
periods.  Clay  is  thus  an  electro-negative  colloid,  its  reaction  probably 
being  conditioned  by  a  trace  of  potash  liberated  by  hydrolysis.  It 
shows  the  general  properties  of  electro-negative  colloids  as  elucidated 
by  Schultz  and  by  Hardy;  thus,  it  is  flocculated  only  by  a  solution 
containing  ions  or  particles  of  opposite  electrical  sign,  and  the  extent 
of  flocculation  increases  rapidly  with  the  valency  and  concentration  of 
the  ion. 

Loam  consists  of  a  mixture  of  sand,  clay,  and  humus.  If  the  sand 
predominates  the  soil  is  said  to  be  light ;  if  the  clay  predominates,  heavy. 
A  rich  soil  contains  an  abundance  of  humus. 

By  humus  is  meant  the  products  of  vegetable  decomposition  in  their 
various  intermediate  stages  of  decay.     It  is  the  essential  element  of 


GENERAL  CONSIDERATIONS  993 

voi;"('t;il)lr  iiKilil.  mill  is  iicccssMrily  of  iiidsl  complex  t(iiii]i(isit  ion.  It  is 
coniposod  of  ii  <;r('a(  iiimilxM'  of  closely  related  (loliiiitc'  chemical  com- 
pounds/ Humus  contains  a  high  percentage  of  nitrogen,  especially 
marked  in  some  of  our  prairie  soils  and  in  the  "black  soil"  found  in 
the  provinces  of  the  Ural  Mountains,  which,  according  to  voji  ITenscn, 
contains  as  much  as  from  5  to  12  per  cent,  of  organic  matter. 

Surface  Configuration. — Geodesy,  or  surface  configuration,  has  an 
important  relation  to  health.  Low  and  swampy  ground  is  a  ])reeding 
])lace  for  the  malarial  mosquito.  Highlands  are  apt  to  be  drier  and 
more  healthful  than  lowlands.  A  slope  affords  better  drainage  than 
flat  lands,  and  thus  diminishes  the  dangers  from  soil  pollution,  but  in- 
creases the  risk  of  infection  being  washed  down  from  those  living  above. 
In  narrow  valleys  the  air  stagnates,  the  moisture  is  excessive  in  both 
the  soil  and  the  air,  and  there  is  an  unpleasant  blanket  of  cold  layers 
of  air  at  night.  Mountain  sides  are  notoriously  windy.  High  plateaux 
suffer  from  extremes  of  temperature.  Thus,  at  Mexico  City  (about 
8,000  feet  above  sea  level)  there  is  a  sharp  contrast  between  the  tem- 
perature during  the  day  and  night,  and  even  during  the  daytime  be- 
tween the  sunshine  and  the  shade.  At  Quito,  which  is  9,350  feet  above 
the  sea  level,  the  daily  variation  of  temperature  at  some  periods  of  the 
year  is  no  less  than  34°  F.  Northern  exposures  do  not  get  enough  sun- 
shine, and  southern  exposures  sometimes  too  much. 

The  relation  of  the  surface  configuration  of  the  land  to  health  is 
intimately  interwoven  with  the  whole  question  of  climate,  and  must 
take  into  consideration  temperature,  air  movements,  humidity,  sun- 
shine, barometric  pressure,  precipitation,  and  the  seasons  with  their 
endless  varieties  from  tropical  to  arctic. 

Composition  of  the  Soil. — Much  attention  was  formerly  given  to  the 
hygienic  importance  of  the  chemical  constituents  of  the  soil.  The  pres- 
ence of  organic  substances  was  regarded  not  only  with  suspicion,  but  even 
as  a  serious  menace  to  health.  It  was  claimed  that  organic  pollution 
of  the  soil  made  a  good  culture  medium  for  the  germs  of  infectious 
diseases.  The  gaseous  products  of  decomposing  organic  matter  in  the 
soil  have  long  been  looked  upon  as  particularly  injurious.  These  gases, 
with  other  ill-defined  but  unknown  volatile  substances,  are  spoken  of 
as  miasma  or  effluvia. 

We  now  know  that  very  few,  if  any,  of  the  bacteria  pathogenic  for 
man  grow  and  multiply  in  the  soil  under  natural  conditions.  The  spores 
of  tetanus,  malignant  edema,  and  anthrax  may  live  in  garden  earth  for 
many  years,  but  it  is  doubtful  whether  these  microorganisms,  especially 
the  anaerobes,  ever  find  conditions  favorable  for  growth  and  multiplica- 
tion in  the  soil.  Ordinarily  typhoid,  dysentery,  and  cholera  bacilli  do 
not  flourish  in  the  soil ;  on  the  contrary,  they  soon  die  there.  It  has 
'  See  Bulletins  of  the  Bureau  of  Soils,  Dept.  of  Agriculture. 


994  GENERAL  CONSIDERATION'S 

been  shown  that  cities  built  upon  polluted  soils  have  sometimes  suffered 
relatively  less  from  typhoid  and  cholera  than  cities  built  upon  rocky 
or  virgin  soil.  In  some  cities  (as  Budapest)  it  has  been  pointed  out 
that  the  greatest  morbidity  and  mortality  rate  was  in  that  part  of  the 
city  built  upon  made  ground  filled  in  with  trash  and  much  organic 
waste.  These  instances  have  been  largely  coincidences,  for,  as  a  rule, 
the  low-lying,  polluted  soil  happened  to  be  the  poor,  crowded  tenement 
district.  A  sanitarian  does  not  recommend  polluted  soils  for  building 
sites,  but  it  seems  that  their  influence  upon  health  has  been  overstated, 
especially  where  cellars  are  properly  constructed.  While  a  polluted  soil 
may  not  be  hazardous  in  the  ways  just  indicated,  it  may  be  dangerous 
so  far  as  hookworms  and  other  parasites  are  concerned,  or  indirectly  it 
may  lead  to  contamination  of  drinking  water^  food,  etc.  See  Pollution 
of  the  Soil,  page  1004. 

Mineral  Matters  in  the  Soil. — By  far  the  most  abundant  element 
in  the  soil  is  oxygen.  According  to.  various  estimates,  from  33  to 
50  per  cent,  of  the  solid  crust  of  the  earth  consists  of  oxygen.  The  other 
elements  found  in  abundance  in  the  soil  are:  silicon,  carbon,  sulphur, 
hydrogen,  chlorin,  phosphorus,  fluorin,  aluminium,  calcium,  magnesium, 
potassium,  sodium,  iron,  manganese,  and  barium.  Aluminium  silicate 
or  clay  makes  up  perhaps  two-thirds  of  the  inorganic  components  of  soils. 
Other  compounds  are  lime  and  magnesia  carbonates  (limestone)  and  nu- 
merous chlorids,  sulphates,  phosphates,  oxids,  etc.,  of  the  various  bases. 

Iron  is  universally  present  and  gives  the  red  color  to  soils.  Nitrogen 
exists  in  soils  in  three  distinct  forms:  (1)  protein  and  its  split  products, 
(2)  ammonia  and  its  salts,  and  (3)  nitric  acid  and  nitrates  or  nitrous 
acids  and  nitrites. 

Vegetable  Matter  in  the  Soil. — The  vegetable  matter  exists  in 
the  soil  in  various  stages  of  decomposition.  One  result  of  the  decay 
of  vegetable  substances  is  the  formation  of  organic  acids,  which  have 
considerable  power  to  dissolve  mineral  substances,  accounting  in  part  for 
the  plumbisolvent  action  of  acid-reacting  surface  waters  from  swampy 
lands. 

Peat  or  muck  results  from  the  incomplete  decay  of  vegetable  matter 
under  water. 

Animal  Matter  in  the  Soil. — Organic  matter  of  animal  origin  in 
soils  results  chiefly  from  the  decomposition  of  carcasses  or  from  con- 
tamination with  the  excreta  of  animals.  As  a  rule,  animal  matter  is 
neither  so  abundant  nor  so  widely  distributed  in  the  soil  as  vegetable 
matter.  From  a  sanitary  standpoint  soils  polluted  with  organic  matter 
of  animal  origin  present  a  greater  danger  than  soils  polluted  with  vege- 
table matter. 

Physical  Properties.— In  general  it  may  be  said  that  the  physical 
properties  of  a  soil  are  more  important,  from  the  standpoint  of  health, 


GENERAL  CONSIDERATIONS  995 

than  its  choniii'.il  coiupositioii.  li  is  a  spongy  mass,  radio-active  and 
contains  numerous  colloidal  bodies. 

Porodtif. — By  the  i)orosity,  or  pore  volume,  of  a  soil  is  meant  the 
volume  of  the  interstices  l)etween  the  particles,  which  may  be  filled  with 
water  or  air,  or  l)oth  ;  in  other  words,  the  power  to  absorb  water.  Poros- 
ity is  expressed  as  a  ]iercentage  of  the  whole  mass.  Ordinarily  the  pore 
volume  in  soil  amounts  to  about  forty  per  cent. ;  some  apparently  com- 
pact masses,  such  as  sandstone,  have  as  much  as  thirty  per  cent.  The 
pore  volume  of  the  soil  is  independent  of  the  size  of  the  individual 
grains. 

Permeability. — The  permeability  of  a  soil  is  its  ability  to  allow 
the  passage  of  water ;  it  does  not  depend  upon  the  pore  volume,  but  upon 
the  size  of  the  individual  pores.  Rocks  may  have  a  high  porosity,  but 
slight  permeability,  due  to  the  extreme  fineness  of  the  pores.  Clay  has 
a  high  porosity,  but  its  permeability  is  slight,  owing  to  the  extremely 
small  size  of  the  pores,  although  their  aggregate  capacity  is  rather  large. 
The  presence  of  fissures  and  Joints  in  the  rock  will  greatly  increase  its 
transmitting  power. 

^Vater  Capacity. — The  water  capacity  of  the  soil  is  the  amount 
of  water  held  in  the  interstices  of  the  soil  when  saturated,  while  the 
ivater-retaining  capacity  is  the  amount  of  water  held  back  after  a  satu- 
rated soil  is  drained. 

Soil  Temperature. — The  sun  is  the  principal  source  of  the  soil 
temperature.  Some  heat  is  produced  from  chemical  changes,  but  not 
in  considerable  amounts.  The  original  heat  of  the  earth's  interior  fur- 
nishes a  constant  source  of  heat  that  is  of  much  importance. 

The  heat  absorbed  and  given  off  by  the  soil  has  a  notable  influence 
upon  the  atmospheric  temperature.  Some  soils  and  moist  surfaces  absorb 
heat  from  the  sun  and  give  it  ofE  agaiij  when  the  sun  has  set.  The  most 
heat-absorbent  soils  are  sandy  soils.  The  sand  of  the  desert  may  be 
heated  to  200°  F.,  and  when  this  hot  sand  is  raised  by  simoons  the  tem- 
perature of  the  air  in  the  shade  may  reach  125°  F.  or  more.  The  power 
of  absorbing  or  reflecting  solar  heat  also  depends  upon  the  color  of 
the  soil. 

Adsorption. — The  soil  has,  to  a  remarkable  extent,  the  property  of 
adsorbing  odors  and  gases,  and  ordinarily  it  is  very  hygroscopic.  The 
soil  is  also  capable  of  holding  toxins^  colors,  and  other  substances 
through  the  physico-chemical  property  of  adsorption.  In  this  respect 
it  acts  like  charcoal.  Illuminating  gas  from  leaky  mains  may  be  divested 
of  its  odorous  constituents  in  its  passage  through  the  soil,  so  that  its 
presence  in  houses  may  be  undetected,  thereby  greatly  increasing  the 
danger.  In  the  experiments  made  by  Abba,  Orlandi,  and  Rondelli 
about  the  filtering  galleries  of  the  Turin  water  supply  the  property  of 
the  soil  to  hold  back  substances  in  solution  was  shown.     Cultures  of 


996    .  GENERAL  CONSIDERATIONS 

Bacillus  prodigiosus  in  large  volumes  of  water  poured  into  the  ground 
at  various  points  made  their  appearance  200  meters  away  in  42  hours, 
whereas  dyes,  such  as  methyleosin  and  uranin,  could  not  be  detected 
until  after  75  hours. 

Soil  Air.— Air  is  present  in  all  soils,  even  in  the  hardest  rocks.  Sand- 
stone may  contain  from  20  to  40  per  cent.,  sand  from  40  to  50  per  cent., 
and  humus  as  much  as  2  to  10  times  its  own  bulk.  The  soil  air  differs 
markedly  in  composition  from  that  of  the  atmosphere.  It  is  usually 
very  moist  and  contains  various  gases,  especially  carbon  dioxid,  result- 
ing from  the  decomposition  of  organic  matter.  For  the  same  reason 
soil  air  contains  less  oxygen  than  the  free  atmosphere.  The  soil  air 
varies  greatly,  according  to  the  character  of  the  soil,  the  climate,  the 
season,  and  rainfall.  There  is  a  continual  interchange  between  the  air 
of  the  soil  and  the  air  of  the  atmosphere.  This  interchange  is  influ- 
enced by  differences  in  temperature,  by  rainfall,  and  by  the  movements 
of  the  ground  water  and  by  barometric  i)ressure.  Rain  chokes  the 
pores  and  checks  soil  ventilation.  The  soil  air  is  in  constant 
motion. 

Following  the  teachings  of  Pettenkofer,  the  amount  of  carbon  dioxid 
in  the  soil  air  was  for  years  taken  as  an  index  of  the  amount  of  soil 
pollution.  It  is  now  well  known,  however,  that  this  is  not  a  reliable 
index,  for  the  reason  that  many  conditions  influence  the  amount  of  CO^ 
in  soil  air.  A  soil  recently  manured  may  contain  from  2  to  5  or  even  10 
parts  of  CO2  per  thousand.  In  a  gravelly  soil  the  proportion  may  be 
as  high  as  80  parts  per  thousand. 

Soil  air  may  influence  health  when  contaminated  with  poisonous 
gases,  such  as  carbon  monoxid.  This  occasionally  happens.  In  the  open 
these  gases  would  be  so  greatly  diluted  that  they  could  scarcely  exert 
a  deleterious  influence,  but  when  concentrated,  as  they  sometimes  are 
in  dwellings,  and  breathed  for  a  long  period  of  time  they  may  be  re- 
sponsible for  anemia,  headache,  and  other  symptoms.  Soil  air  contain- 
ing carbon  monoxid  may  be  sucked  into  a  dwelling  from  long  distances 
in  a  lateral  direction.  Leaky  gas  pipes  may  thus  render  the  air  of  a 
dwelling  impure  if  the  cellar  is  permeable.  This  is  favored  by  the 
pumping  action  of  the  furnace,  especially  when  the  surface  of  the  ground 
is  frozen. 

Soil  air  is  practically  sterile;  that  is,  under  ordinary  conditions  it 
contains  few  bacteria.  Odors  sometimes  contained  in  the  air  from  a 
polluted  soil  have  no  known  injurious  effect. 

Soil  Water. — The  passage  of  water  through  the  soil  is  essential  to 
•  soil  activity.  The  moisture  favors  the  bacterial  growth  by  which  soils 
purify  themselves  and  favors  vegetation.  Nitrates,  chlorids,  and  other 
soluble  substances  are  dissolved  in  the  water  and  pass  into  the  sub- 
soil, or  furnish  food  to  the  roots  of  plants.     A  soil  absolutely  dry,  as. 


GENEl^AL  CONSIDEl^ATTONS  997 

a  desert  soil,  is  lifeless.  A  soil  with  an  cxiiess  of  moisture,  (Iiat  is, 
one  in  which  tlu-  i^roinid  wnlcr  level  is  at  or  near  the  surface,  delays  and 
alters  the  natural  decomposition  of  organic  matter.  In  the  deeper  layers 
of  the  soil,  where  no  bacterial  action  takes  place,  vegetable  matter  may 
remain  almost  permanently  without  (•han<rc.  Thus,  wooden  piles  are 
not  attacked  after  centuries. 

Water  exists  in  the  soil  in  two  princi])al  forms:  (1)  soil  tnoistnre, 
which  comprises  the  water  present  in  the  interstices  of  the  uj)per 
{jartly  saturated  layer,  as  well  as  the  watery  vapor  contained  in  the 
soil  air;  and  (2)  ground  water,  or  subsoil  water,  in  which  case  the  in- 
terstices of  the  soil  are  completely  filled. 

The  soil  moisture  is  estimated  by  determining  the  loss  of  weight  by 
drying  10  grams  of  soil  at  100°  C.  to  constant  weight.  The  dry  sample 
may  then  be  exposed  to  air  saturated  with  moisture  under  a  bell  jar 
and  again  weighed.  The  increase  in  weight  indicates  the  absorptive 
power  of  the  soil. 

Water  may  also  be  regarded  as  existing  in  the  soil  under  three 
conditions,  viz.,  hygroscopic,  capillary,  and  gravitation.  The  hygro- 
scopic water  is  that  which  adheres  to  the  surface  of  the  soil  particles 
in  the  presence  of  air.  The  capillary  moisture  is  that  which  is  held 
within  the  spaces  that  are  capillary  in  their  nature.  The  gravitation 
water  is  that  which  drains  through  the  soil  and  accumulates  in  the  sub- 
soil over  an  impermeable  stratum.  For  a  discussion  of  ground  w^ater 
see  chapter  on  Water. 

It  is  generally  stated  that  a  persistently  low  ground  water  level, 
viz.,  15  to  20  feet,  is  healthful,  and  that  a  persistently  high  ground 
water  level,  viz.,  3  to  5  feet,  is  unhealthful.  and  that  a  ground  water 
level  that  fluctuates  suddenly  is  still  more  unhealthful.  Pettenkofer 
found  that  typhoid  fever  was  more  likely  to  occur  at  Munich,  Berlin, 
and  Leipzig  Avhen  the  ground  w^ater  level  was  at  its  lowest.  His  ex- 
planations to  account  for  this  were  ingenious,  but  we  now  know  that 
the  relation  was  only  a  coincidence,  for  the  same  does  not  hold  in  other 
places. 

Subsoil  drainage  is  usually  considered  more  of  an  agricultural  neces- 
sity than  a  public  health  question.  Large  tracts  of  our  land  in  the 
Middle  West  and  in  other  parts  of  the  world  have  normally  a  high 
ground  water  level,  and  it  is  necessary  to  bring  this  down  in  order  to 
increase  the  fertility  of  the  soil.  This  is  done  by  draining  the  subsoil, 
which  also  abolishes  marsny  and  swampy  lands,  and  thus  puts  a  check 
upon  malaria. 

One  of  the  principal  influences  of  the  soil  upon  general  health  is 
through  soil  moisture.  Dampness  in  or  near  the  surface  of  the  soil 
may  affect  the  health  of  those  dwelling  nearby.  Such  a  soil  is  cold, 
and  the  atmosphere  immediately  above  it  is  liable  to  be  damp,  and  this 


998  GENERAL  COA^SIDERATIONS 

appears  to  conduce  to  rheumatism,  neuralgia,  and  diseases  of  the  res- 
piratory tract.  Investigations  seem  to  indicate  that  the  general  health 
of  those  dwelling  on  damp  soils  is  inferior  to  that  of  those  more  favor- 
ably circumstanced  in  that  regard. 

The  Nitrogen  Cycle. — The  most  interesting  of  the  vital  phenomena 
taking  place  in  the  soil  is  the  disposal  and  utilization  of  organic  mat- 
ter. This  may  best  be  illustrated  by  the  nitrogen  cycle,  which  must  be 
understood  in  order  to  have  a  clear  conception  of  soil  pollution,  water 
purification,  and  sewage  disposal. 

The  nitrogen  cycle  is  a  complex  series  of  events  which  protein  mat- 
ter undergoes,  in  which  it  is  reduced  to  simple  and  stable  inorganic 
compounds,  and  then  returns  through  plant  life  to  the  animal  kingdom. 
One  phase  of  the  cycle,  namely,  the  breaking  down  of  animal  and 
vegetable  matter,  is  due  almost  entirely  to  bacterial  action.  The 
other  phase,  namely,  the  building  up  of  complex  living  organic  matter 
from  simpler  compounds  and  elements,-  is  mainly  a  function  of  living 
plants. 

The  nitrogen  cycle  is  a  process  in  which  the  anabolism.  or  synthesis 
occurs  in  plants,  while  the  catabolism  or  analysis  is  brought  about 
chiefly  through  bacterial  action.  Hence  the  series  of  events  constituting 
the  nitrogen  cycle  largely  depends  upon  the  plant  kingdom.  The  im- 
portant phases  of  the  cycle  occur  upon  the  soil  and  in  its  superficial 
layer.  It  will  presently  be  seen  that  this  cycle  has  a  fundamental  im- 
portance in  sanitary  science,  and  has  a  special  significance  in  prevent- 
ing soil  pollution,  in  the  purification  of  water,  and  in  the  disposal  of 
sewage.  It  is  evident  that  any  permanent  break  in  this  cycle  would 
result  in  the  cessation  of  life  upon  the  earth. 

As  soon  as  an  animal  or  plant  dies  its  protein  constituents  are  at 
once  attacked  by  putrefactive  bacteria.  The  proteolytic  microorganisms 
(aided  by  the  larvae  of  insects)  growing  in  and  upon  the  nitrogenous 
matter  break  it  up  into  secondary  and  simpler  ])roducts,  which  have 
a  striking  resemblance  to  the  cleavage  products  of  gastric  and  pancreatic 
digestion.  Some  of  the  putrefactive  bacteria,  of  which  the  Bacillus 
suhtilis  and  the  Bacillus  proteus  are  important  types,  liquefy  protein 
matter  during  the  process  of  putrefaction.  Other  bacteria,  of  which  the 
colon  bacillus  is  a  type,  break  down  organic  matter  without  evident 
liquefaction.  Very  many  other  species  of  bacteria  take  part  in  this 
stage  of  the  cycle.  For  the  most  part  the  microorganisms  pathogenic 
for  man  are  killed  during  the  process  of  putrefaction ;  they  die  in  the 
struggle  for  existence.  The  processes  of  decomposition  are  essentially 
the  same,  whether  the  organic  matter  is  the  carcass  of  an  elephant,  a 
beetle,  a  tree,  or  a  leaf,  provided  that  the  necessary  moisture,  warmth, 
and  other  conditions  for  bacterial  growth  are  present.  The  breaking 
down  of  vegetable  matter  is  slower  and  more  difficult  than  the  break- 


GENERAL  CONSIDERATIONS 


999 


down  of  animal  niattt-r.  'I'liis  is  duo  in  part  to  tho  Tact  that  the  latter 
contains  larger  percentages  of  putrescihle  protein  and  also  usually  con- 
tains more  moisture,  which  favors  bacterial  activity. 

The  breaking  down  of  the  complex  protein  molecules  to  simpler 
and  stabler  compounds  is  usually  spoken  of  as  mineralization,  and  may 
be  regarded  as  a  series  of  oxidations.  According  to  our  present  chemi- 
cal conception,  it  is  really  a  series  of  hydrolyses.  The  complicated 
molecular  structure  of  protein  matter  is  analyzed  into  amino  com- 
pounds of  simpler  and  simpler  composition,  until  nitrogen  finally  ap- 


r 


V. 


[^Kinetic  Energy] 

Fig.  103. — The  Xitrogex  Cycle. 


pears  in  the  form  of  ammonia.  We  know  little  of  the  chemistry  of  the 
early  stages  of  protein  decomposition.  The  process  seems  hopelessly 
complicated  from  the  intricate  structure  of  the  molecule.  Eventually 
from  the  seething  caldron  of  molecular  disintegration  there  appear 
simpler  substances,  such  as  proteoses,  peptone,  ptomains,  amins,  leucin, 
and  tyrosin,  and  other  amino  substances,  as  well  as  organic  acids,  indol, 
skatol,  phenol,  and  finally  sulphurated  hydrogen,  mercaptan,  carbonic 
acid,  and  ammonia.  One  of  the  final  products  of  the  process  is  carbon 
dioxid,  part  of  which  passes  into  the  atmosphere  and  part  of  which  is 
retained  in  the  soil  as  carbonates  of  alkalies  or  alkaline  bases.  The 
ammonia,  as  .such,  cannot  be  used  by  plants.  Some  of  it  may  escape 
into  the  atmosphere,  but  for  the  most  part  it  is  retained  in  the  soil 
as  ammoniimi'  chlorid  or  ammonium  carbonate.  In  the  soil  the  am- 
monia is  oxidized  by  the  action  of  nitrifying  bacteria  into  nitrates.    This 


1000  GENERAL  COXSIDEEATIONS 

nitrifying  action  of  bacteria,  elucidated  by  Winogradsky  ^  in  1888,  was 
one  of  the  brilliant  discoveries  in  bacteriolog}'.  Through  his  ingenious 
work  and  that  of  later  workers,  it  is  now  known  that  this  process  is 
usually  accomplished  in  two  distinct  steps.  The  ammonia  is  changed 
to  carbonate,  which  is  rapidly  oxidized  by  nitromonas  into  nitrite,  and 
this  by  nitrobacter  into  nitrate. 

These  nitrous  or  nitrite  bacteria  were  called  by  Winogradsky  nitro- 
monas and  nitrococcus.  This  action  is  very  specific.  The  ammonia  is 
changed  to  ammonium  carbonate  which  is  rapidly  oxidized  by  nitro- 
monas into  nitrite.     Nitromonas  occur  in  several  forms,  mostly  oval  or 


^ 


^'^h^iT^r-^^^ 


Putrefaction   —  Danger  Zone 

Nitrification  -  NO  s-  KUhn  Zont 
NOt 


Final  Mineralization  NO  3- Safe  Zone 
{Absence  of  NO2  and  NH3) 


lirfund^^Waier 


Fig.  104. — The  Nitbogen  Cycle  in  Diagrammatic  Vertical  Section. 


coccus-shaped;  a  zoogleal  stage  is  also  found.     It  is  spore-free,  requires 
an  alkaline  medium,  aerobic,  and  widely  distributed. 

The  nitrites  exist  in  the  soil  probably  as  salts  of  potassium  and 
sodium.  They  remain  as  the  lower  oxid  a  very  short  time  and,  there- 
fore, never  accumulate,  and  are  never  found  in  any  large  amount  for 
they  are  unstable  and  readily  oxidized  to  nitrates.  The  special  nitric 
or  nitrate  bacteria  (nitrobacter)  were  first  accurately  described  by 
Winogradsky.  Nitrobacter  is  also  very  specific  in  its  action.  It  is 
rod-shaped,  aerobic,  spore-free,  requires  an  alkaline  medium,  and  is 
widely  distributed.  No  other  organism  is  known  with  certainty  to 
produce  nitrates  in  soil.  The  nitrates  are  stable  and  represent  the  final 
stage  of  the  mineralization  of  nitrogenous  matter.  In  certain  arid  parts 
of  "the  world  large  deposits  of  nitrates  (KNO3,  saltpeter)  are  found 
as  the  result  of  the  nitrification  of  bird  excrement  (guano),  which  is 

2  Winogradsky.  S.:     Ann.  de  VInst.  Pasteur,  1890,  IV,  pp.  27-5  and  760;  also 
Arch.,  des  Sci.  Biol,  St.  Petersburg,  1895,  III,  297. 


GENERAL  CONSTDERATTONS  1001 

ricli  in  available  nitrogen.  'I'hosc  collections,  however,  do  not  occur  in 
l^laccs  where  there  is  enou^^di  rain  to  carry  away  the  readily  soluble 
nitrates. 

Ordinarily  the  nitrates  go  into  solution  in  the  ground  water  and  are 
either  taken  up  by  the  roots  of  plants  or  are  washed  away  in  the  ground 
water.  In  a  sanitary  analysis  of  water  taken  from  the  soil  the  presence 
of  nitrates  and  nitrites,  therefore,  has  a  special  significance.  If  nitrites 
are  found  in  soil  water  it  indicates  pollution  and  signifies  active  bacterial 
action  and  the  presence  of  organic  matter.  Nitrates  in  soil  water,  with- 
out nitrites,  are  an  index  of  past  pollution  (see  Water  Analysis). 

In  1886  Gayon  and  Dupetit  described  two  organisms,  B.  denitrificans 
a  and  /S,  capable  of  completely  reducing  nitrates.  Many  bacteria  have 
this  power  of  denitrification,  a  sort  of  reversible  process  by  which  nitrates 
are  reduced  to  nitrites,  and  then  to  ammonia,  and  further  to  gaseous 
nitrogen.  This  is  characteristic  of  very  many  of  the  well-known  micro- 
organisms, such  as  the  colon  group,  pyocyaneus,  subtilis.  and  other  soil 
bacteria.  Maasen  found  this  action  in  85  of  109  kinds  of  microorgan- 
isms studied.  Denitrification,  however,  does  not  occur  in  a  well-ventil- 
ated soil,  for  it  requires  lack  of  air,  presence  of  much  decomposable 
organic  matter  and  of  nitrates, — a  combination  rarely  found  in  nature. 

In  plant  metabolism  the  nitrates  are  used  to  build  up  new  protein. 
Certain  plants  get  some  of  their  nitrogen  through  the  bacterial  tubercles 
on  their  roots,  which  have  the  power  of  fixing  the  free  nitrogen  of  the 
air.  These  small  nodules  are  abundant  on  the  roots  of  various  legumi- 
nous plants  (peas,  clover,  etc.).  Pure  cultures  of  the  legume  or  nitrogen 
fixing  bacteria,  such  as  BadlJus  radidcola  of  Bejerinck,^  may  be  obtained 
from  these  root  tubercles.  Bacterial  inoculation  of  soils  to  replace 
nitrogenous  manuring  is  a  fascinating  possibility,  but  has  not  been 
realized  in  practice. 

It  should  be  noted  also  that  certain  bacteria  (azobacter)  have  the 
ability  to  fix  the  free  nitrogen  of  the  air  independently  of  plant  life  and 
may  grow  under  either  aerobic  or  anaerobic  conditions.  One  of  the 
first  known  of  this  group  was  an  anaerobe  described  by  Winogradsky  in 
1895  and  named  by  him  Clostndium  paslorianus. 

It  will  be  noted  that  in  the  nitrogen  cycle  all  the  essential  steps, 
from  proteolysis  to  mineralization  of  the  organic  matter,  nitrification, 
oxidation,  and  reduction,  as  well  as  the  fixation  of  free  nitrogen  from 
the  atmosphere,  are  all  the  result  of  bacterial  action.  Each  stage  of 
the  complex  process  is  specific,  in  the  sense  that  it  requires  a  particular 
species  or  group  of  bacteria  to  effect  the  result,  and  also  specific  in  the 
sense  that  special  conditions  of  environment  are  necessary  for  its  action 

^  Bejerinck,  Botan.  Ztg.  1888,  xlvi,  725. 

Upon  special  media,  colonies  of  B.  radicicola  yield  rods  1  to  5^  long,  some  of 
which  show  signs  of  bacterial  formation  and  "swarmers,"  so  small  that  they  will 
pass  a  porcelain  filter. 


1002  GENERAL  CONSIDERATIONS 

to  take  place.  Nitromonas  will  oxidize  ammonium  carbonate  and 
nothing  else;  it  will  not  touch  nitrites,  urea,  or  the  substituted  ammonias. 
Nitrobacter  is  equally  specific. 

It  is  important  to  remember  that  practically  the  entire  cycle  takes 
place  upon  the  surface  and  in  the  upper  layers  of  the  soil.  A  few 
feet  below  the  surface  of  an  undisturbed  area  the  soil  contains  few  or 
no  bacteria.  Carcasses  buried  deep,  or  sewage  placed  too  far  below 
the  surface,  do  not  profit  by  the  nitrogen  cycle  in  its  entirety,  and  under 
such  circumstances  incomplete  nitrification  takes  place.  Nature's  method 
of  disposing  of  dead  wastes  is  thereby  defeated,  and  pollution  of  the  soil 
and  infection  of  the  ground  water  may  result. 

The  Carbon  Cycle. — Carbohydrates,  such  as  cellulose,  starch,  sugars, 
and  similar  constituents  of  vegetable  and  animal  matter,  are  fermented, 
with  the  formation  of  carbon  dioxid,  alcohol,  and  various  organic  acids. 
The  carbon  in  carbohydrates  passes  through  a  series  of  changes,  which 
may  be  regarded  as  the  carbon  cycle.  The  carbon  dioxid  resulting  from 
fermentation  unites  with  water  in  the  plant  life,  and  under  the  action 
of  chlorophyll  and  sunlight  is  again  synthetized  to  starch  and  sugars. 

The  fermentation  of  the  carbohydrates  is  also  due  to  the  action 
of  microorganisms.  In  a  mixture  containing  both  carbohydrates  and 
protein,  as  a  rule,  the  microorganisms  act  upon  the  carbohydrates  first. 
In  other  words,  the  putrefaction  of  protein  is  delayed  or  hindered  by  the 
presence  of  fermentable  carbohydrates.  For  this  reason  sewage  contain- 
ing wastes  from  breweries  always  presents  difficulties  at  disposal  plants. 

Fats  are  also  attacked  by  bacteria,  with  the  consequent  production 
of  acids.  The  hydrocarbons  are  broken  down  with  more  difficulty  than 
either  the  carbohydrates  or  protein.  An  excessive  amount  of  fat  in 
sewage  always  gives  trouble  on  a  filter.  For  instance,  the  drainage  from 
a  wool-scouring  mill  containing  lanolin  and  the  discharges  from  slaugh- 
ter houses  and  the  wastes  from  creameries,  laundries,  and  cheese  fac- 
tories containing  animal  fat  present  special  problems  in  sewage  dis- 
posal. 

The  nitrogen  cycle,  as  well  as  the  carbon,  sulphur,  and  phosphorus 
cycles  are  all  processes  of  oxidation — at  least  the  terminal  products  are 
nitrates,  carbonates,  sulphates,  and  phosphates. 

REFERENCES 

EussELL,  Edward  J, :    "Soil  Conditions  and  Plant  Growth,"  London,  1915. 


CHAPTER  II 
THE  SOIL  AND  ITS  RELATION  TO  DISEASE 

Bacteria  in  SoiL — Countless  millions  of  bacteria  occur  in  the  upper 
few  inches  of  the  soil.  The  enormous  overgrowth  of  bacteria  in  the 
upper  layers  of  the  soil  gives  it  the  sticky,  moist  feeling  which  rich 
soils  possess.  The  odor  of  the  soil,  such  as  that  which  is  particularly 
noticed  after  a  rainstorm,  is  due  in  large  part  to  Cladothrix  odorifera 
and  other  organisms  which  are  commonly  found  in  the  soil.  Few  bac- 
teria are  found  in  an  undisturbed  soil  below  a  depth  of  4  to  6  feet.  A 
sand  bed  used  for  filtering  sewage  shows  a  similar  vertical  distribution 
of  bacteria.  Below  six  feet  the  statement  is  made  that  the  soil  is  usually 
sterile.  This  is  not  strictly  true,  but  the  numbers  are  much  diminished 
and  bacterial  activity  has  practically  ceased.  As  a  rule,  living  bacteria 
are  not  obtained  from  samples  of  soil  obtained  10  to  13  feet  below  the 
surface,  except  in  soils  with  large  pores  or  crevices,  or  in  cases  where 
the  bacteria  have  been  carried  by  burrowing  animals.  It  is  exceedingly 
difficult  to  determine  the  number  of  bacteria  in  the  soil,  as  so  many  of 
them  are  anaerobes  and  vast  hordes  belong  to  the  nitrifying  groups, 
which  grow  only  upon  selective  media.  The  soil  is  also  the  home  of 
other  species,  requiring  special  conditions  for  growth  in  artificial  culture 
media. 

Of  the  ordinary  bacteria  that  grow  upon  the  usual  laboratory  media 
Houston  found  an  average  of  100,000  per  gram  in  an  uncultivated 
sandy  soil,  1,500,000  per  gram  in  a  garden  soil,  and  115,000,000  per 
gram  in  a  sewage  soil.  Peaty  soils  have  smaller  numbers.  The  actual 
numbers  must  be  vastly  greater,  for  many  microorganisms  in  the  soil 
do  not  grow  upon  the  common  media.  In  fact,  the  soil  is  the  home 
of  the  greatest  number  and  variety  of  bacteria  found  anywhere.  It  is 
the  bacteria  in  the  upper  layers  of  the  soil  that  make  it  resemble  a  living 
gland.  Each  particle  of  earth  is  coated  with  a  zoogleal  envelope.  The 
sand  and  mineral  particles  form  the  supporting  structures,  the  coat- 
ing of  bacteria  corresponds  to  the  glandular  epithelium,  and  the  in- 
terspaces between  the  particles  are  the  capillary  and  lymph  channels. 

Most  of  the  bacteria  in  the  soil  are  saprophytes.  The  microorgan- 
isms pathogenic  for  man  do  not  find  conditions  favorable  for  growth 
and  development  in  the  soil.  For  the  most  part  the  temperature  is  too 
low ;  further,  they  are  crowded  out  by  the  overgrowth  of  the  saprophytes. 
Koch  has  demonstrated   that  anthrax  and  other  pathogenic   bacteria 

1003 


1004        THE  SOIL  AND  ITS  EELATION  TO  DISEASE 

may  be  grown  in  sterile  soil,  but  cannot  be  grown  in  unsterilijed  soil, 
that  is,  in  living  soil.  They  die  in  the  struggle  for  existence.  Experi- 
ments have  shown  that  the  soil  of  graveyards  contains  no  more  bacteria 
than  the  corresponding  soil  in  the  same  locality,  and  is  noticeable  by 
the  absence  of  pathogenic  microorganisms.  The  soil  often  contains  the 
bacteria  (or  their  spores)  of  certain  wound  infections,  such  as  malig- 
nant edema,  anthrax,  B.  aerogenes  capsulatus,  and  tetanus.-  The  rela- 
tion of  the  soil  to  typhoid,  cholera,  dysentery,  hookworm  disease,  Cochin- 
China  diarrhea,  and  other  infections  will  be  discussed  presently. 

The  function  of  the  bacteria  in  the  soil  may  best  be  understood  by 
studying  the  fate  of  organic  matter  polluting  the  soil  and  the  processes 
Avhich  accomplish  its  purification.     See  Nitrogen  Cycle,  page  998. 

Pollution  of  the  Soil. — The  soil  is  capable  of  disposing  of  great  quan- 
tities of  organic  matter.  However,  if  it  is  overburdened  it  remains  pol- 
luted and  may  endanger  health  through  contamination  of  the  drink- 
ing water  and  in  other  ways.  It  is  not  only  the  amount  but  the  kind 
of  pollution,  and  also  the  manner  of  its  disposal,  that  plays  a  very 
important  part.  It  must  first  of  all  be  remembered  that  the  purify- 
ing action  of  the  soil  is  largely  dependent  upon  bacteria,  and  that  this 
action  takes  place  almost  solely  in  the  upper  layers.  If  carcasses  are 
buried  deeply,  or  if  sewage  is  allowed  to  enter  the  soil  at  several 
feet  below  the  surface,  the  process  of  purification  is  long  delayed 
or  checked.  A  leaky  cesspool  or  broken  drain  which  discharges  its 
contents  into  the  soil  at  a  depth  of  5  feet  or  more  may  seriously  pol- 
lute the  ground  water,  whereas  the  same  material  placed  upon  or  just 
beneath  the  surface  may  be  entirely  mineralized  and  all  infection  de- 
stroyed before  it  reaches  the  depth  of  5  feet.  Vegetable  matter  in  a 
water-logged  soil  undergoes  a  partial  and  unusual  decomposition  into 
muck  or  peat.  Trees  buried  deeply,  where  bacterial  action  is  practically 
absent,  remain  for  many  hundreds  of  years  practically  unchanged. 
Many  factors  retard  the  purifying  action  of  the  soil.  Among  these  the 
temperature  and  moisture  and  absence  of  oxygen  predominate. 

When  organic  matter  falls  upon  the  soil  it  is  consumed  and  di- 
gested by  the  hungry  earth.  Without  this  property  the  surface  of  the 
earth  would  long  ago  have  become  clogged  with  vegetable  and  animal 
matter.  Albuminous  substances  are  dissolved  by  the  action  of  the  pro- 
teolytic bacteria,  and  converted  into  simpler  chemical  compounds.  The 
intermediate  products  of  protein  putrefaction  are  exceedingly  complex. 
For  our  present  purposes  it  is  sufficient  to  know  that  ultimately  the 
nitrogen  is  largely  converted  into  ammonia  and  the  carbon  into  carbon 
dioxid.  The  ammonia  is  then  oxidized  by  the  action  of  nitrifying 
bacteria  to  nitrites,  and  the  nitrites  again  oxidized  to  nitrates.  The 
nitrates  are  the  final  products  of  the  mineralization  of  organic  matter. 
Most  of  the  nitrates  pass  into  solution  and  are  carried  down  into  the 


THE  SOIL  AND  ITS  RELATION  TO  DISEASE        lOOn 

deeper  Invers  of  the  soil  or  siihsoil :  some  of  it  is  taken  nj)  iliroui^h  tlie 
roots  of  plants,  ^Phe  carbon  dioxid  passes  off  into  the  air  as  a  gas, 
remains  in  the  soil  moisture  in  solution,  or  is  converted  into  carbonates. 

Pathogenic  bacteria  that  may  be  thrown  upon  the  soil  in  feces  or 
otherwise  are  usually  detained  in  the  upper  layers  and  finally  destroyed 
there.  Under  ordinary  conditions  pathogenic  microorganisms  are  caught 
in  the  upper  layers  of  the  soil,  just  as  they  are  caught  upon  the 
"schmutzdecke"  of  a  slow  sand  filter.  The  soil  does  not  act  simply  as  a 
mechanical  trap.  The  bacteria  are  detained  and  destroyed  by  a  com- 
bination of  physical,  chemical,  and  vital  processes  taking  place  in  the 
upper  layers  of  the  soil. 

All  polluted  soils  are  not  equally  dangerous.  Soils  polluted  with 
human  feces  and  urine  present  the  greatest  hazard  to  man.  The  special 
menace  of  soils  polluted  with  human  excreta  is  from  typhoid  bacilli, 
hookworms,  and  other  infections  discharged  in  the  feces  or  urine.  Hook- 
worm infection  is  usually  contracted  directly  from  soils  polluted  with 
human  feces,  and  the  eradication  of  hookworm  disease  depends  pri- 
marily upon  preventing  pollution  of  the  soil.  The  danger  in  the  case 
of  typhoid,  dysentery,  cholera,  and  other  bacterial  infections  is  usually 
indirect  through  infection  of  drinking  water  or  occasionally  through 
flies  or  other  mechanical  means  of  transference.  A  soil  polluted  with 
typhoid  may  endanger  either  the  surface  water  or  the  ground  water, 
particularly  in  limestone  formations.  Pathogenic  microorganisms  in  a 
polluted  soil  maA'  also  find  their  way  back  to  man  upon  vegetables. 
Tapeworms  and  other  intestinal  parasiies  pass  part  of  their  life  cycle 
on  or  in  the  soil,  and  may  infect  man  directly  or  indirectly  in  various 
ways.  The  question  of  soil  pollution  and  the  particular  ways  in  which 
it  is  related  to  health  have  been  discussed  separately  under  each  disease 
concerned. 

Dirt. — The  soil  is  often  spoken  of  as  dirt.  The  soil  in  the  field  is 
''earth,"  but  in  the  parlor  or  on  our  hands  it  becomes  dirt:  that  is, 
matter  out  of  place.  The  word  "dirt"  is  from  the  old  Saxon  "drit." 
meaning  excrement.  Dirt  in  the  ordinary  sense  becomes  a  potential 
danger,  especially  when  containing  human  excretions  or  soil  bacteria 
associated  with  wound  infections. 

To  the  sanitarian  dirt  includes  rubbish,  manure,  and  organic  wastes 
of  all  kinds.  It  may  be  the  vehicle,  but  not  the  source,  of  infection. 
It  breeds  and  harbors  flies,  fleas,  lice,  rats,  mice,  and  vermin  of  all 
sorts  that  act  as  intermediate  hosts  or  carriers  of  infection.  While  dirt 
cannot  originate  typhoid  fever  or  other  infections,  it  favors  conditions 
which  encourage  the  spread  of  such  diseases.  Eubbish  in  vacant  lots, 
in  backyards,  in  alleys,  in  cellars,  garrets,  and  other  places  may  be 
taken  as  an  index  of  the  failure  to  appreciate  the  modern  teachings  of 
hygiene  and  sanitation.     It  was  once  the  chief  duty,  and  still  an  ira- 


1006        THE  SOIL  AND  ITS  RELATION  TO  DISEASE 

portant  one,  of  the  health  officer  to  insist  upon  cleanliness  of  premises 
and  surroundings,  both  in  country  and  city. 

Cleanliness. — Cleanliness  is  the  heart  and  soul  of  sanitation.  We 
are  inclined  to  place  it  even  before  godliness,  for  cleanliness  of  body, 
cleanliness  of  mind  and  soul,  and  cleanliness  of  our  surroundings  are 
essential  to  a  full  appreciation  of  the  spiritual  virtues.  Our  conception 
of  cleanliness  has  greatly  changed  with  our  advance  in  knowledge  of  the 
Tvinds  of  dirt,  the  degrees  of  dirtiness,  and  the  nature  of  these  dangers. 
We  can  no  longer  be  satisfied  with  physical  or  esthetic  cleanliness,  but 
must  insist  upon  biological  cleanliness.  A  tetanus  spore  upon  the  shin- 
ing blade  of  a  surgeon's  knife  makes  that  instrument  filthy,  whereas 
many  such  spores  on  the  skin  of  a  chicken  may  be  harmless  when  in- 
gested. We  cannot  see  the  infection  upon  the  common  drinking  cup, 
upon  the  roller  towel,  upon  the  point  of  a  pencil  that  has  -just  been 
moistened  with  saliva,  or  in  water,  milk,  or  food,  although  we  well 
know  the  danger  of  such  invisible  "dirt'-'  that  these  objects  may  harbor. 

It  requires  a  bacteriologist  to  tell  the  difference  between  clean  dirt 
and  dirty  dirt.  We  lack  a  sixth  sense,  or  microscopic  eye,  to  see  and 
distinguish  the  harmful  germs.  We,  therefore,  must  practice  scrupu- 
lous cleanliness  and  educate  the  people  to  the  biological  meaning  of 
this  term.  Long  experience  has  taught  the  lesson  that  cleanliness  offers 
a  protection  against  disease;  that  clean  surroundings  are  apt  to  be  free 
of  infection ;  and  that  clean  food  is  apt  to  be  safe  food. 

Cleanliness  of  person  and  environment  results  in  the  diminution  of 
the  number  and  perhaps  the  virulence  of  many  pathogenic  microorgan- 
isms, such  as  streptococci  and  staphylococci.  Cleanliness  of  the  type 
that  approaches  asepsis  would  prevent  much  sickness  and  save  many 
lives  through  diminishing  the  risk  of  infections.  Hill  believes  that  the 
mildness  of  modern  infectious  diseases  is  due  to  the  lessened  virulence, 
smaller  stock,  and  reduced  distribution  of  the  streptococci  and  staphy- 
lococci formerly  bred  in  hospitals  and  in  wounds  promiscuously.  The 
public  health  officer  should,  therefore,  campaign  for  personal  and  com- 
munal asepsis. 

Many  houses,  especially  in  poorer  sections  of  cities,  lack  proper  facili- 
ties for  laundry  work.  Public  laundries,  such  as  are  provided  in  many 
European  countries,  would  materially  help  in  the  campaign  for  general 
cleanliness. 

At  one  time  the  theory  of  the  filth  diseases  reached  the  dignity  of 
a  special  name — the  pythogenic  theory,  first  propounded  by  Murchin- 
son  in  1858.^     Typhoid  fever  was  long  regarded  as  the  type  of  a  filth 

'  "I  shall  bring  forward  what  I  consider  positive  proof  that  this  fever 
(typhoid)  is  produced  by  emanations  from  decaying  organic  matter;  and  I 
would  therefore  suggest  for  it  the  appellation  of  'pythogenic  fever'!"  "Con- 
tributions to  the  etiology  of  Continued  Fever,"  p.  219.  "Medico-Chirurgical 
Transactions,"  London,  1858,  Vol.  XLI,  p.  221. 


THE  SOIL  AND  ITS  KELATION  TO  DISEASE         1007 

disease,  ami,  while  we  are  now  dropping  that  term,  we  should  not 
forget  that  t}])h()i(l  fever  is  really  a  filthy  disease,  Tor  each  case  means 
that  a  short  circuit  has  been  established  between  the  discharges  from  one 
person  and  the  mouth  of  another. 

The  Influence  of  the  Soil  upon  Health. — The  soil  was  formerly 
accused  of  being  one  of  the  largest  and  most  important  factors  in  the 
spread  of  the  communical'le  diseases.  It  was  once  regarded  as  the 
cause,  if  not  the  nesting  place,  of  infections  of  all  kinds;  tuberculo- 
sis, malaria,  typhoid  fever,  plague,  yellow  fever,  cholera,  dysentery,  and 
many  other  diseases  were  directly  associated  with  the  soil.  We  now 
know  that  coni])aratively  few  of  the  microorganisms  pathogenic  for 
man  live  in  the  soil,  and  practically  none  of  them  grow  and  multiply 
there. 

The  soil  contains  a  number  of  bacteria  that  may  be  serious  when 
introduced  into  wounds,  as  tetanus,  malignant  edema,  anthrax,  B.  aero- 
genes  capsidatus;  ofttimes  organisms  belonging  to  the  hemorrhagic  sep- 
ticemic group ;  sometimes  staphylococci  and  streptococci. 

A  soil  polluted  with  human  excrement  presents  the  possibility  of 
danger  of  intestinal  infections  of  all  kinds.  Thus,  bacterial  infections, 
such  as  typhoid,  cholera,  and  dysentery,  or  protozoal  infections,  such 
as  amebic  dysentery,  or  the  higher  worms,  such  as  hookworms,  may  all 
more  or  less  be  associated  with  polluted  soils. 

Soils  containing  much  organic  matter  and  presenting  other  favor- 
able conditions  afford  resting  and  nesting  places  for  a  number  of  in- 
sects, such  as  flies,  ticks,  etc.,  which  may  carry  infections. 

Vegetables  grown  in  polluted  soils  may  transfer  bacteria,  protozoa, 
or  the  eggs  of  worms  in  a  mechanical  way  from  the  ground  to  the 
mouth.  This  applies  particularly  to  vegetables  eaten  raw,  such  as 
radishes,  lettuce,  etc. 

Practically  all  the  water  used  for  drinking  and  other  purposes  has 
either  rested  upon  the  soil  or  has  percolated  through  it  into  the  ground. 
The  soil  materially  affects  the  character  of  the  water.  In  this  way  the 
soil  indirectly  influences  health  variously  and  sometimes  seriously.  The 
relation  of  water  to  health  is  a  subject  in  itself,  and  is  discussed  in 
a  separate  chapter. 

The  physical  conditions  of  the  soil  which  have  special  reference  to 
health  are  those  which  influence  the  temperature  and  moisture  of  hu- 
man habitations.  Persons  working  about  cold  and  damp  soils  are  sub- 
ject to  rheumatic,  neuralgic,  and  respiratory  affections. 

Diseases  Associated  with  the  Soil. — Tetanus. —  Spores  of  the  tetanus 
bacillus  commonly  occur  in  the  soil  of  inhabited  regions.  They  have 
been  found  not  only  in  the  superficial  layers,  but  sometimes  at  a  depth 
of  several  feet.  The  normal  habitat  and  the  great  reservoir  of  tetanus 
are  the  intestines  of  the  herbivora.     It  may  also  be  found  in  the  intes- 


1008        THE  SOIL  AND  ITS  RELATION  TO  DISEASE 

tinal  contents  of  man  and  other  animals.  Certain  savages  in  the  New 
Hebrides  used  to  smear  their  arrow  heads  with  dirt  from  crab  holes 
in  the  swamp,  which  they  knew  by  experience  to  be  poisonous.  We 
now  know. that  this  material  contained  tetanus  spores. 

Tetanus  increases  as  we  approach  the  tropics,  where  puerperal  tet- 
anus and  tetanus  of  the  newborn  are  relatively  frequent.  Tetanus  spores 
are  much  more  abundant  in  certain  localities  than  others.  For  ex- 
ample, certain  parts  of  Long  Island  and  New  Jersey  have  become  no- 
table for  the  number  of  cases  of  tetanus  caused  by  small  wounds. 

The  tetanus  bacillus  probably  does  not  grow  and  multiply  in  the 
i-oil.  It  cannot  there  hnd  the  necessary  anaerobic  conditions,  tempera- 
ture, and  other  factors  necessary  for  multiplication.  The  resistance 
of  the  spores  accounts  for  the  persistence  of  the  infection. 

The  prevention  of  tetanus  has  been  discussed  on  page  95.- 

Anthrax. — Like  tetanus,  anthrax  does  not  grow  in  the  soil  under 
natural  conditions.  Its  persistence  is  -accounted  for  by  its  resistant 
endospore.  Anthrax  spores  have  been  found- in  pastures  where  infected 
animals  have  been  confined. 

The  anthrax  bacillus  requires  oxygen  in  order  to  sporulate;  the 
spores,  therefore,  do  not  form  in  the  blood,  and  it  is  very  important 
not  to  open  the  carcass  of  a  sheep  or  cow  dead  of  this  disease  before 
it  is  buried.  The  classic  researches  of  Pasteur  on  anthrax  should  be 
studied  in  this  connection.  Pasteur  examined  the  field  where  animals 
dead  of  anthrax  had  been  buried  twelve  years  previously.  He  found 
the  specific  bacillus  in  the  soil  and  demonstrated  its  virulence  by 
inoculations  into  guinea-pigs.  Pasteur  thought  that  the  spores  were 
brought  to  the  surface  of  the  soil  by  earthworms,  and  proved  the  pos- 
sibility of  this  by  sowing  virulent  cultures  in  soil  and  recovering  the 
bacillus  from  worm  casts.  It  seems,  however,  in  the  light  of  subse- 
quent investigations  that  the  danger  from  this  source  is  negligible,  so 
that  anthrax,  with  a  few  exceptions,  can  hardly  be  called  a  soil  in- 
fection. This  is  the  case  at  least  with  man,  for  there  is  no  instance 
on  record  in  which  human  anthrax  has  been  contracted  from  contact 
with  the  soil. 

Malignant  Edema. — The  bacillus  of  malignant  edema  is  found  in 
the  superficial  layers  of  the  soil.  It  is  very  widely  distributed.  This 
organism  is  also  found  in  putrefying  substances,  in  foul  water,  and  in 
the  intestinal  tract  of  various  animals.  In  1877  Pasteur  first  recog- 
nized an  organism  belonging  to  this  group  by  injecting  animals  with 
putrefying  liquids.  He  called  the  organism  the  vibrion  septique,  recog- 
nized its  anaerobic  nature,  but  did  not  obtain  it  in  jjure  culture.  Koch 
and  Gaft'ky  in  1881  studied  it  carefully  and  renamed  it  the  bacillus  of 
malignant  edema.  The  bacillus  has  lateral  flagella,  an  oval  spore,  and 
is  a  strict  anaerobe.     It  is  very  pathogenic  for  almost  all  animals,  caus- 


THE  SOIL  AND  ITS  KELATION  TO  DISK  ASK         1009 

ing  extensive  hemorrhagic  edema  without  the  ])ro(Iu(tion  of  gas,  whicli 
distiiigiiishes  it  from  the  gas  haeilhis  of  Welch.  Wound  infections  with 
malignant  edema  occur,  especially  with  deep  punctured  or  lacerated 
wounds,  Mhirh  favor  anaerobic  growth.  Belore  the  days  of  antisepsis 
this  complication  was  frequent,  especially  during  wars. 

BariUii.^  l\'rfringcn.'<  (also  known  as  Welch's  Gas  Bacillus  and  li. 
aerogcnes  mpsulaius). — This  organism  is  a  member  of  a  populous  and 
widely  distributed  species  of  bacteria,  which  have  in  common  the  ability 
to  ferment  sugars  with  the  production  of  butyric  acid.  B.  \Yelchii  is  a 
large  rod,  gram-positive,  and  usually  grows  singly  or  in  pairs.  Spore 
formation  is  inconstant  and  occurs  only  in  alkaline  media,  never  in  pure 
cultures  in  media  containing  a  fermentable  sugar  or  free  acid.  It  causes 
stormy  fermentation  of  milk;  that  is,  the  milk  is  quickly  coagulated  and 
gas  formation  is  so  abundant  as  to  break  up  the  curd  and  even  to  force 
parts  of  it  above  the  cream  ring.  A  rabbit  injected  intravenously  with 
this  organism,  killed  within  two  or  three  minutes  and  incubated,  pre- 
sents in  twenty-four  hours  a  body  enormously  distended  with  gas  which 
will  burn  with  a  pale  blue  flame. ^ 

This  bacillus  is  found  in  the  intestinal  canal  of  man  and  animals, 
in  soil  and  dust  which  distributes  it  widely.  When  introduced  in  wounds 
it  causes  a  serious  infection  with  the  production  of  gas.  In  the  present 
war  many  wounds  contaminated  with  the  soil  of  the  trenches  have 
been  complicated  with  this  infection.  A  serum  has  been  prepared  by 
Bull  and  Pritchett,  which  prevents,  but  does  not  cure  this  infection 
in  man. 

Many  other  microorganisms,  especially  those  belonging  to  the  hemor- 
rhagic septicemic  group,  occur  in  the  soil  and  occasionally  complicate 
wounds. 

Typhoid  Fever. — There  is  a  widespread  belief,  even  among  sani- 
tarians, that  this  disease  is  frequently  connected  with  soil  pollution. 
This  belief  was  given  scientific  confirmation  by  Pettenkofer,  who  pro- 
pounded the  theory  that  the  poison,  whatever  it  may  be,  is  introduced 
into  the  soil  where,  under  proper  condition  of  organic  filth,  tempera- 
ture, moisture,  etc.,  a  special  fermentation  takes  places.  Pettenkofer 
believed  that  the  gases  or  effluvia  thus  produced  rise,  and  in  some  way 
were  capable  of  provoking  disease.  Pettenkofer's  views  of  typhoid  in 
relation  to  the  height  of  the  ground  water  have  already  been  mentioned. 

Typhoid  bacilli  frequently  find  their  way  upon  and  into  the  soil 
along  with  luiman  excreta.  Multiplication,  however,  rarely  takes  place 
there.  As  a  rule,  the  typhoid  bacillus  scarcely  lives  a  month,  possibly 
two  or  thTee  months,  in  the  soil.     When'  frozen  they  may  live  and  re- 

^  "Studies  in  B.  Wek-hii,  with  Special  Reference  to  Classification  and  to  Its 
Relation  to  Diarrhea,"  J.  P.  Simonds,  Monographs  of  the  Rockefeller  Institute, 
No.  5,  September  27,  1915. 


1010        THE  SOIL  AND  ITS  EELATION  TO  DISEASE 

main  virulent  for  several  months,  as  in  the  case  of  the  Plymouth  epi- 
sode and  the  New  Haven  epidemic.  While  typhoid  fever  in  cities  and 
towns  has  no  evident  direct  relation  to  soil  pollution,  it  is  possible 
to  conceive  an  indirect  relation  in  many  cases,  especially  in  camps  and 
in  rural  districts. 

There  are  numerous  ways  by  which  typhoid  bacilli  may  be  returned 
from  the  soil  to  the  mouth  of  a  susceptible  person.  It  is  possible,  though 
not  likely,  for  this  to  occur  directly.  So  far  as  typhoid  is  concerned, 
perhaps  the  greatest  danger  from  a  polluted  soil  consists  in  infection 
of  the  drinking  water.  The  ways  in  which  this  may  occur  are  dis- 
cussed in  the  chapter  on  water.  The  transfer  of  typhoid  bacilli  from 
the  soil  to  the  mouth  may  also  occur  mechanically  by  means  of  flies, 
dust,  and  dirt.  Vegetables  grown  in  a  polluted  soil  may  carry  typhoid 
bacilli  to  the  very  tips  of  their  leaves. 

The  pollution  of  soil  with  human  feces  is  always  a  danger  and 
should  be  prevented.  The  worst  offense  in  this  particular  occurs  in 
country  districts,  where  the  potential  danger  is  greater  than  in  the  city. 

Goiter. — The  soil  and  its  underlying  rocky  strata  have  long  been 
associated  with  endemic  goiter,  in  some  indirect  way,  either  through 
chemical  constituents  or  bacterial  contamination  of  drinking  water 
coming  in  contact  with  certain  geological  formations.  Goiter  is  most 
prevalent  in  the  regions  underlaid  by  the  Silurian,  Carboniferous,  and 
Permian  systems;  while  those  over  the  eruptive  or  crystalline  rocks  of 
the  Archean  group,  the  sediment  of  Jurassic,  Cretaceous,  and  post  ter- 
tiary seas,  as  well  as  all  fresh-water  deposits,  are  comparatively  free 
from  the  affection. 

In  some  cases  goiter  does  appear  in  localities  over  the  second  group, 
but  in  these  places  the  underlying  strata  are  thin  and  ground  water 
penetrates  to  lower  groups.  It  is  observed  also  that  the  influence  of  the 
first  group  is  weakened  or  lost  by  superimpositions  of  the  fresh-water 
strata. 

Baillarger,  in  a  review  of  this  subject  in  1873,  concluded  that  "it 
had  not  been  shown  that  goiter  prevailed  exclusively  on  any  particular 
soil,  but  that  it  seemed  to  prove  that  the  endemic  is  extremely  common 
on  the  dolomite  formations  and  rare  on  others." 

The  relation  of  goiter  to  the  soil  is  doubtful,  except  as  it  may  be 
deficient  in  iodin,  for  simple  goiter  is  due  to  a  lack  of  iodin  in  the  water, 
food,  or  both.     For  discussion  on  this  subject  see  page  1150. 

Cholera. — There  is  every  reason  to  believe  that  the  cholera  vibrio 
dies  quickly  when  deposited  upon  or  in  the  soil  under  natural  condi- 
tions. The  cholera  vibrio  may  be  transferred  from  the  soil  to  the  mouth 
in  the  ways  mentioned  above  in  the  .case  of  typhoid.  Formerly  cholera 
was  believed  to  be  associated  with  polluted  soils,  but  it  now  appears  that 
the  disease  is  rarely  contracted  from  the  soil,  and  that  the  physical  and 


THE  SOIL  ANr>  ITS  DELATION  TO  DISEASE        1011 

chemical  conditions  of  (lie  <:^r()iui(l   play   little,   if  any,  role   in  Iho  e]n- 
demiology  of  this  disease. 

Tuberculusi^  (nuJ  Oilier  Diseases. —  In  18(i2  Dr.  II.  I.  IJowditch 
formulated  the  law  of  soil  moisture  from  studies  which  seemed  to  indi- 
cate that  tuhereulosis  was  more  common  in  Massachusetts  over  moist 
soils  than  dry  ones.  If  there  is  any  connection  hetween  tuhereulosis 
and  the  soil,  the  relation  must  be  indirect.  Exposure  to  cold  and  damp 
depresses  vitality  and  lowers  resistance  to  tuberculosis.  It  does  not 
necessarily  follow  that  habitations  or  workshops  are  cold  and  damp 
because  the  ground  on  which  these  houses  are  built  is  wet  and  cold. 

The  soil  was  formerly  accused  of  being  responsible  for  plague, 
malaria,  yellow  fever,  and  a  long  list  of  other  diseases.  The  impor- 
tance of  the  soil  with  reference  to  the  communicable  diseases  diminishes 
with  our  increase  in  knowledge.  The  number  of  infections  directly 
associated  with  the  ground  are  very  few,  and  the  indirect  influences 
are  less  than  formerly  supposed. 

Apart  from  the  one  real  danger,  viz.,  soil  pollution  with  human  ex- 
crement, the  sanitarian  is  now  inclined  to  belittle  the  influence  of  the 
soil  upon  health. 

Dampness  and  cold  may  favor  rheumatic  and  neuralgic  conditions, 
and  also  predispose  to  respiratory  infections.  In  this  way  association 
with  a  cold,  damp  soil  may  be  prejudicial  to  health.  Clay  soils  are 
apt  to  be  damp;  sand  and  gravel  soils  are  readily  drained  and  may 
be  kept  dry  by  means  of  simple  devices.  Such  soils,  therefore,  make 
the  best  building  sites  for  habitations.  As  a  rule,  the  foundation  of  a 
house  should  be  at  least  two  or  three  feet  above  the  level  of  the  ground 
water. 

The  soil  greatly  influences  the  character  of  the  water  which  rests 
upon  it  and  which  passes  through  it.  This  will  be  discussed  in  the  sec- 
tion on  water. 

Hoolcworm  Disease. — Hookworm  disease  is  closely  associated  with 
the  soil.  It  may  fairly  be  considered  an  infection  dependent  upon  soil 
pollution.  It  occurs  especially  in  moist  sandy  soils  rather  than  on 
clay  or  rocky  soils.  This  is  due  to  the  fact  that  hookworm  eggs,  when 
deposited  in  fecal  matter,  soon  dry  up  and  die  upon  hard  rocky  or 
clay  surfaces,  whereas  they  find  favorable  conditions'  for  development 
upon  moist  sand  or  loam.  Under  these  conditions  the  larvae  develop 
as  far  as  the  second  ecdysis,  which  have  the  power  of  penetrating  the 
skin.     See  page  153. 

Other  Animal  Parasites. — In  a  somewhat  similar  sense  many  of 
the  animal  parasites  of  man  are  deposited  on  the  soil  and  reinfect  man 
during  one  of  the  stages  of  their  cycle  of  development.  Most  of  the 
intestinal  parasites  of  man  are  deposited  on  the  soil,  and,  after  a  vary- 
ing journey,  sometimes  through  an  intermediate  host,  again  find  lodg- 


1012        THE  SOIL  AND  ITS  RELATION  TO  DISEASE 

ment  in  man.  In  the  case  of  Taenia  solium,  for  instance,  man  pollutes 
the  soil  with  feces  containing  the  eggs.  Hogs  devour  this  infection  and 
return  the  disease  to  man.  Soil  pollution  likewise  results  in  the  infec- 
tion of  cattle  with  the  eggs  of  another  tapeworm  of  man,  Taenia  saginata. 
Various  parasitic  protozoa  have  resistant  stages  that  may  remain  in  the 
soil  for  long  periods  of  time  following  their  introduction  by  fecal 
contamination. 

Ascaris  lumhricoides  and  Tricliuris  trk-liiura,  two  worms  commonly 
inhabiting  the  intestinal  tract  of  man,  have  very  resistant  thick  shelled 
eggs  that  have  been  kept  alive  for  as  long  as  five  years,  so  that  soil  once 

List  of  animal  parasites  of  man  toMch  may  he  spread  by  soil  pollution 


Direct :  without  intermediate 
Host 


Indirect :   with   intermedi- 
ate host 


III 
Requires    further    study.    Prob- 
ably I  or  II  as  marked 


PROTOZOA 


Entamoeba  coli 

Entameba 

tropicalis 

"           histolytica 

" 

nndnlans 

"           buccalis 

(f 

phagocvtoides 

Parameba  hominis 

(C 

nippcnica 

ChlamydophiYS  enchelys 

" 

brasiliensis 

Trichomonae  vaginalis 

<( 

hartmanni 

Prowazekia  asiatica 

ii 

blitschlii 

Tetramitiis  mesnili 

Cercomonas  hominis 

Trichomonas  vaginalis 

Prowazekia 

crnzi 

"             hominis  (or  in- 

a 

nrinaria 

testinalis) 

ti 

Weinberg! 

Eimeria  hominis 

Monas  pvophila 

Isospora  bigemina 

"       lens 

Balantidinm  coli 

Heteromita 

zevlanica 

Lamblia  (Giardia) 

Trichomonas  dvsenteriae 

'ntestinalis 

" 

pulmonalis 

Rhinospori 

dium  seeberi 

Balantidinm  minntum 

Nictotherns  faba 

" 

giganteus 

i( 

africanns 

TREMATODA— FLUKES 


Fasciola  hepatica 

Fasciola  gigantica 

II 

Opisthorchis  felineus 

Watsonius  watsoni 

II 

Clonorchis   endemicns 

Gastrodiscns  hominis 

II 

Clonorchis  sinensis 

Fasciolopsis  bnski 

II 

Paragonimus  ringeri 

"             fiilleborni 

II 

Schistosoma  japonicum 

"             rathonsi 

II 

Schistosoma     haemato- 

"             goddardi 

II 

binm 

Echinostoma  ilocannm 

II 

Schistosoma  mansoni 

"             malavannm 

II 

^Metagonimns      yokoga- 

Opisthorchis   noverca 

II 

wai 

Heterophves  heterophyes 

II 

Dicrocoelinm  lanceatnm 

II 

'nil-:  SOIL  AND  ITS  KKLATIOX  TO   DISKASE         1013 

List  of  animal  para.silcs  of  man — coiitiniicd 


I  I  II  I  III 

Direct:   without  intermediate      Indirect:    witli    intermedl-   [Icquires    furllier    study.    I'rob- 
host  '  j  ate  host  {  ably  I  or  II  as  markod 


CESTODA— TAPEWORMS 


Diliotlirioccplialus 

latiis 

Dil)()thri()(ephalus  parvus    II 

])ih()tliri()ci'j)]uilus 

cur- 

Diplogonoporus  grand  is      ii 

(iatus 

"               brauni        ii 

Dipylidium  caniimm 

Hymenalepis  nana                  i 

Hviiionalcpis  diniiii 

iita 

Davaineamadagascariensisii 

Hvmenalcpis  lanceolata 

"         asiatica                   ii 

Taenia  .solium 

Taenia  afrirana                    ii 

"        saginata 

"        honiinis                     ii 
"        pliilippina                 ii 
"        confusa                     n 
"        bremneri                    ii 
Braunia  jayensis                  ii 
Bertiella  satyri                     ii 

NEMATODA— ROUNDWORMS 


Leptodera  pellio 

Dracunculus  medinensis 

Physaloptera  caucasia         i 

Strongvloides  stercoralis 

"             mordens           I 

Ascaris  lumbricoides 

Gnathostoma  spinigerum 

Toxascaris  can  is 

Ascaris  maritima                   l 

limbata 

"        texana                        i 

Belascaris  mvstax 

Tridontophorus  diminutus    i 

Lagocheilascaris  minor 

Oesophagostomum      apiosto- 

Oxviiris  vermicularis 

mum                                      I 

Haenionchus  contortus 

Oesophagostomum  brumpti  l 

Ancvlostoma  duodenale 

"                    stephan- 

A.  cevlonicum 

ostomum  thomasi               l 

Necator  aniericanus 

INIetastrongvliis  apri              i 

Trichuris  trichiura 

Nematodirus  gibsoni  i 
Trichostrongylus   colubrifor- 

mis  I 
Trichostrongylus       probulu- 

rns  I 
Trichostrong;s'lus  vitrinus  I 
Dioctophyme  renale  li 
Mecistocirrus  fordi  1 
Ternidens  deminutus             l 

ACANTHOCEPPIALA— THORX-HEADED  WORMS 


Macrancathorhynchus 
hirudinacens 
moniliformis 


contaminated  with  tliese  parasites  may  continue  to  serve  as  a  source  of 
infection  for  considerable  periods  of  time.  Several  weeks  or  more, 
according  to  conditions  of  temperature  and  moisture,  are  required  for 
the  development  of  the  eggs  of  these  parasites  to  the  infective  stage 


1014        THE  SOIL  AND  ITS  EELATION  TO  DISEASE 

following  their  passage  from  the  intestines.  If  fresh  eggs  of  these  tv/o 
worms  are  ingested,  they  pass  through  the  intestinal  tract  without 
hatching. 

The  above  table  ^  (pages  1012,  1013)  gives  a  list  of  animal  parasites 
having  a  relation  to  the  soil  during  some  part  of  their  life  history,  and 
may,  therefore,  be  more  or  less  associated  with  soil  pollution.  It  will  be 
noticed  that  for  the  most  part  Protozoa  and  Nematoda  are  contracted  di- 
rectly, whereas  Trematoda,  Cestoda  and  Acanthocephala  are  contracted 
indirectly  and  through  an  intermediate  host. 

^This  table  was  prepared  by  Ch.  Wardell  Stiles, 


SECTION  VIII 
WATER 

CHAPTER    1 
GENERAL  COXSIDERATIOXS 

"The  greatest  influence  on  health  is  exerted  by  those  things  which  we  most 
freely  and  frequently  require  for  our  existence,  and  this  is  especially  true  of  water 
and  air"   (Aristotle). 

"While  water  is  not  technically  classed  as  a  food,  it  is  an  essential 
article  of  diet.  In  nature  water  comes  in  contact  with  many  surfaces 
and  substances  and.  therefore,  is  particularly  liable  to  contain  impuri- 
ties, especially  as  it  is  the  most  universal  solvent  known.  Water  is 
also  a  frequent  medium  for  the  transmission  of  infection. 

From  the  remotest  antiquity  the  highest  value  has  been  placed 
upon  an  abundant  and  pure  water  supply.  Centers  of  population  sprang 
up  in  ancient  times  around  those  points  where  it  was  most  readily 
available,  and  great  expenditures  of  labor  and  treasure  "were  made  to 
carry  it  to  places  where  it  was  not  naturally  plentiful.^ 

Water  is  a  prime  necessity  of  life — not  only  as  an  article  of  diet, 
but  also  for  the  proper  cleanliness  of  person,  clothing,  and  things. 

It  is  interesting  to  note  that  the  number  of  towns  in  this  country 
before  1800  having  a  public  water  supply  was  only  16,  supplying  about 
2.8  per  cent,  of  the  existing  population  at  that  time.  In  1850  there 
were  only  83  public  water  works,  supplying  about  10.6  per  cent,  of  the 
census  population.  In  1897  the  total  number  was  3,196,  supplying 
about  41.6  per  cent,  of  the  population.  Since  then  the  number  has 
greatly  increased,  but  exact  information  is  not  available.^ 


COMPOSITION 

At  the  close  of  the  eighteenth  century  water  was  regarded  as  an 
elementary   substance.     In  1781   Cavendish   discovered  that,  when   an 

*The  date  of  construction  of  the  Appian  aqueduct  carrying  water  to  Rome 
is  placed  at  312  B.  C.  Eighteen  other  aqueducts  were  constructed  at  various 
times  until  226  A.  D.  The  one  commenced  bv  Emperor  Ckius  and  completed  by 
Claudius,  according  to  Plinv,  cost  350.000,000  sesterces,  or  ajbout  .$12,700,000.  ' 

==  Baker,  M.  X.:     "Manual  of  American  Water  Works,"  1891  and  1897. 

1015 


1016  GENERAL  CONSIDEEATIONS 

electric  spark  is  passed  through  a  mixture  of  2  parts  of  hydrogen  to 
1   part   of   oxygen,   these   gases    combine  to   form   water.      Since   then 
water  has  been  made  synthetically,  and  separated  analytically  into  its 
component  constituents  by  various  methods. 
The  composition  of  pure  water  (HgO)  is: 

By  Volume  By  Weight 

Oxygen    1  part  8  parts 

Hydrogen    2  parts  1  part 

Pure  water  is  a  chemical  curiosity;  it  does  not  exist  in  nature. 
All  water  in  nature  contains  impurities,  in  solution  and  in  suspension. 
Some  of  these  impurities  are  organic  and  some  are  inorganic.  They 
consist  of  various  gases,  fluids,  and  solid  substances. 


CLASSIFICATION  OF  WATER 

From  a  sanitary  standpoint  water  is  either  good  or  bad.  Commonly 
waters  are  classified  as  pure  or  impure.  It  is  not  possible,  however; 
in  the  present  state  of  our  knowledge,  to  draw  a  sharp  line  of  distinc- 
tion. In  the  classical  reports  of  the  Massachusetts  State  Board  of 
Health  waters  are  spoken  of  as  normal  or  polluted.  A  normal  water 
is  free  from  direct  or  indirect  pollution  by  waste  products  from  human 
life  or  industries.  The  difficulty  with  this  classification  is  that  normal 
M^aters  may  differ  widely  in  color,  taste,  odor,  and  composition,  and  may, 
therefore,  be  unfit  for  household  or  manufacturing  purposes. 

Water  is  considered  pure  from  a  sanitary  point  when  it  contains  no 
evidences  of  pollution  from  the  wastes  of  man  or  animal,  and  is  con- 
sidered pure  by  the  engineer  when  it  contains  no  lime  or  salt  to  form 
boiler  scale,  or  organic  matter  in  sufficient  amount  to  cause  foaming. 

A  practical  classification  of  water  is  as  follows:  (1)  good,  (3) 
polluted,  (3)  infected.  A  good  water  may  be  defined  as  one  of  good 
sanitary  quality,  as  determined  by  physical  inspection,  bacteriological 
and  chemical  analyses,  a  sanitary  survey  of  the  watershed,  and,  finally, 
by  practical  experience.  A  polluted  water  is  one  containing  organic 
waste  of  either  animal  or  vegetable  origin.  A  polluted  ^  water  is  a 
suspicious  water.  An  infected  water  contains  the  specific  microorgan- 
isms of  human  diseases.* 

In  Europe  waters  are  frequently  classified  as  potable  or  non-potable. 
Many  cities  on  the  Continent  have  a  double  water  supply  with  faucets 
plainly  labeled  "potable"  or  "non-potable,"  the  first  being  suitable  for 
drinking  and  cooking  purposes  and  personal  use,  while  the  second  is 
intended  for  miscellaneous  household  and  industrial  uses. 

"  Sometimes  spoken  of  as  contaminated  water. 

*  Chemical  poisons  such  as  lead  are  not  included  in  this  classification. 


THE  USES  OF  WATER  IN  TIIM  BODY  1017 

According  to   location,   waters   are  considered    under  three  classes, 
viz.,  rain  water,  surface  water,  or  ground  water. 


PROPERTIES  OF  WATER 

Water  is  a  clear,  transparent,  tasteless,  and  odorless  fluid;  colorless 
in  small  quantities;  pale  blue  through  a  deep  column.  It  freezes  at 
0°  C.  and  boils  at  100°  C.  under  a  barometric  pressure  of  7G0  mm.  It 
is  practically  incompressible;  has  its  greatest  density  at  4°  C. ;  is  a 
remarkable  solvent.  The  latent  heat  of  water  and  other  properties 
that  have  a  sanitary  bearing  will  be  considered  in  the  succeeding  pages. 

AVater  is  tlie  most  widely  distributed  substance.  The  hardest  crystals 
and  the  driest  rocks  contain  appreciable  quantities;  in  fact,  crystals 
could  not  form  Avcre  it  not  for  the  action  of  water. 

Practically  all  substances  yield  to  water;  it  is  the  most  universal 
solvent  known.  It  dissolves  gases;  in  fact,  one  of  the  most  important 
constituents  of  all  natural  waters  is  carbonic  acid.  Carbon  dioxid  is 
always  present  in  the  air,  and  all  rain  waters  contain  some  of  it.  Still 
more  is  taken  up  by  the  water  as  it  percolates  through  ground  covered 
with  vegetation.  The  presence  of  this  gas  increases  the  solvent  powers 
of  the  M'ater,  enabling  it  especially  to  dissolve  limestone  and  many  other 
substances. 

THE  USES  OF  WATER  IN  THE  BODY 

As  a  rule,  water  is  not  considered  a  food,  for  it  may  be  said  to 
have  little  or  no  value  w^hen  estimated  as  a  force  producer  within  the 
body.  Much  of  the  water  which  is  either  drunk  or  ingested  as  a  part 
of  other  foods  passes  through  the  body  unchanged,  but  some  of  it  is 
undoubtedly  altered  or  split  up  into  elements  which  unite  with  other 
compounds.  The  nature  of  these  processes  is  obscure,  and  as  yet  very 
little  understood.  Water  is  entitled  to  rank  as  a  food  because  it  enters 
into  the  structural  composition  of  all  foods  as  well  as  all  the  tissues  of 
the  body;  it  is  an  essential  element  of  diet,  even  though  it  cannot  of 
itself  build  tissue,  repair  waste,  or  produce  heat  or  energy. 

Water  composes  about  70  per  cent,  of  the  entire  body  weight,  and 
its  importance  to  the  system,  therefore,  cannot  be  overrated.  "  The 
elasticity  or  pliability  of  muscles,  cartilages,  tendons,  and  even  bones 
is  in  a  great  part  due  to  the  water  which  these  tissues  contain.  "The 
cells  of  the  body  are  aquatic  in  their  habits.''  The  amount  of  -water 
required  by  a  he-aithy  man  in  '^.M  hours  is,  on  the  average,  between 
1,800  and  2,100  c.  c,  besides  aliout  GOO  c.  c.  taken  in  as  an  ingredient 
of  solid  foods,'-  thus  making  a  total  of  2,400-2,700  c.  c.     Twenty-eight 

"  Fully  five-sixths  of  the  food  in  an  ordinary  diet  consists  of  water. 


1018  GENERAL  CONSIDERATIONS 

per  cent,  of  the  loss  of  water  from  the  body  takes  place  through  the 
skin,  twenty  per  cent,  through  the  lungs,  fifty  per  cent,  through  the 
kidneys,  and  two  per  cent,  through  other  secretions  and  the  feces. 

The  use  of  water  in  the  body  may  be  summarized  as  follows:  It 
enters  into  chemical  composition  of  the  tissues;  it  forms  the  chief  in- 
gredient of  all  the  fluids  of  the  body  and  maintains  their  proper  de- 
gree of  dilution,  and  thus  favors  metabolism;  by  moistening  various 
surfaces  of  the  body,  such  as  mucous  and  serous  membranes,  it  prevents 
friction;  it  furnishes  in  the  blood  and  lymph  a  fluid  medium  by  which 
food  may  be  taken  to  remote  parts  of  the  body  and  the  waste  material 
removed,  thus  promoting  rapid  tissue  changes;  it  serves  as  a  distributor 
of  body  heat;  it  regulates  the  body  temperature  by  the  physical  process 
of  absorption  and  evaporation. 

One  of  the  most  universal  dietetic  faults  is  neglect  to  take  enough 
water  into  the  system.  Water  may  be  taken  with  meals,  but  never  to 
wash  down  food;  in  other  words,  water  must  not  be  used  to  take  the 
place  of  thorough  mastication. 

THE  AMOUNT  OF  WATER  USED  AND  WASTED 

From  a  sanitary  standpoint  our  aim  should  be  to  encourage  a  gen- 
erous use  of  water,  but  to  discourage  waste.  The  conservation  of  pure 
water  and  the  economic  use  of  a  purified  water  are  pressing  problems 
that  a  growing  and  expanding  country  must  meet  and  solve  as  a  matter 
of  self-interest  if  not  of  self-preservation. 

It  is  possible  to  get  along  with  a  surprisingly  small  amount  of 
water.  Thresh  found  that  in  a  number  of  country  places  the  amount 
used  in  cottages  did  not  greatly  exceed  one  gallon  per  person  per 
day.  This  is  not  sufficient  for  modern  requirements  of  cleanliness  and 
health. 

On  the  other  hand,  where  the  supply  is  abundant  and  easy  of  access 
large  quantities  of  water  are  heedlessly  wasted. 

The  average  amount  of  water  required  per  capita  for  domestic  pur- 
poses is  usually  stated  at  about  17  gallons  a  day.  Rankine  considers 
10  gallons  sufficient.  Parkes  found  that  the  average  amount  used  by 
a  man  in  the  middle  class,  who  may  be  taken  as  a  fair  type  of  a  cleanly 
man  belonging  to  a  fairly  clean  household,  is  12  gallons  per  day.  This 
includes  the  amount  used  in  cooking,  drinking,  ablution,  utensil  and 
house  washing,  and  laundry.  Davies'  estimate  of  17  gallons  a  day  is 
divided  as  follows. 

Drinking,  3  pints ;  cooking,  5  pints 1  gal. 

Ablution  (including  sponge  bath,  2%  gals.) 5     " 

Washing  (laundry,  3;  hovise,  etc.,  3)  .  . . 6     " 

Water  cloaeta 5     " 

l7     " 


THE  AMOUNT  OF  WATER  USED  AND  WASTED      1019 

The  actual  per  capita  daily  eonsiiini)ti()n  of  water  in  some  cities  is, 
in  fact,  not  much  above  this  figure.  Thus,  Manchester  uses  20  gallons 
and  Berlin  22  gallons  a  day  for  each  individual.  Some  small  English 
towns,  as  Saffron  Walden  (population  G,108),  use  11  gallons  per  cap- 
ita per  day,  and  Melrose  (population  1,300)  uses  13  gallons.  As  a 
contrast  to  these  low  figures  most  cities  in  America  are  furnished  with 
an  extravagant  quantity — Pittsburgh,  250  gallons  per  capita  daily,  Buf- 
falo, 233,  Philadelphia,  227,  Washington,  218.«  The  small  amount  of 
water  used  by  some  European  cities  is  not  an  ideal  to  strive  for  under 
American  coiulilions.  The  European  figures  are  steadily  Increasing, 
even  where  all  water  is  sold  by  meter.  Tn  towns  having  a  metered  sup- 
ply the  per  capita  consumption  varies  from  G.G  gallons  daily  for  the 
lowest  class  of  dwellings,  to  59  gallons  for  the  highest  class  of  dwell- 
ings. 

The  following  tables  give  the  per  capita  consumption  in  some  Ameri- 
can cities,  contrasted  with  similar  figures  abroad. 

The  quantities  of  water  supplied  in  a  number  of  American  cities 


Gals. 

Percent- 

Gals. 

Percent- 

Gals. 

Percent- 

Place 

Year* 

per 
Capita 

age  of 
Services 

Yeart 

per 
Capita 

age  of 
Service? 

Yeart 

per 
Capita 

age  of 
Services 

Daily 

Metered 

Daily 

Metered 

Daily 

Metered 

Pittsburgh 

1905 

250 

1 

1912 

236 

20 

1914 

240 

20 

Buffalo 

1900 

233 

2 

1915 

312 

5 

1918 

260 

5 

Philadelphia  ... 

1905 

227 

1913 

178 

1916 

182 

15 

Washington  .  . . 

1906 

218 

3 

1915 

130 

70 

1916 

136 

77 

Chicago 

1900 

190 

3 

1913 

218 

1917 

259 

22 

Detroit 

1905 

190 

29 

1912 

185 

, 

1918 

152 

62.5 

Boston 

1905 

151 

6 

1915 

104 

60 

1917 

106 

59 

Cleveland 

1905 

137 

68 

1915 

137 

79 

1917 

113 

98.4 

New  York 

1902 

129 

35 

1915 

66 

1916 

101 

26.8 

Newark 

1900 

94 

21 

1915 

122 

55 

1916 

119 

Milwaukee 

1905 

91 

94 

1915 

127 

99 

1917 

118 

99 

Minneapolis  .  . . 

1904 

82 

42 

1915 

79 

90 

1916 

84 

98 

Worcester 

1900 

70 

94 

1915 

84 

1916 

79 

73.5 

Providence .... 

1905 

68 

86 

1914 

75 

1916 

66 

93 

St.  Paul 

1900 

67 

28 

1915 

61 

64 

1916 

69 

64.1 

Hartford 

1906 

63 

100 

1915 

101 

98' 

1916 

65 

98.5 

Lowell 

1905 

52 

69 

1915 

57 

78 

1916 

56 

Fall  River 

1905 

37 

97 

1915 

53 

100 

1916 

48 

100 

*From  Hazen's  "Clean  Water  and  How  to  Get  It." 
t  Prom  ofBcial    sources   compiled   by   Dr.  .1.   P.  Bill. 


The  quantities  of  ivater  supplied  in  a  few  foreign  cities 


Place 

Year 

U.  S.  Gallons 

per  Capita 

Daily 

Place 

Year 

U.  S.  Gallons 

per  Capita 

Daily 

London 

1912 
1911 
1913 
1905 
1905 
1905 

36 
36 
69 
37 
63 
39 

Berlin 

1913 
1905 
1905 
1913 
1906 

24 

Liverpool 

Paris.        

Hamburg 

Dresden 

Copenhagen 

Brisbane 

44 
26 

Amsterdam 

^lelboiirne 

Svdnev 

32 
58 

These  figures  include  industrial  uses. 


1020  GENERAL  CONSIDERATIONS 

The  amount  of  water  expressed  by  the  per  capita  consumption 
of  a  community  is  very  misleading  for  purposes  of  comparison.  The 
figures  are  usually  obtained  by  dividing  the  total  theoretical  amount 
of  water  pumped,  by  the  population.  The  result,  therefore,  does  not 
take  into  account  many  factors,  for  the  actual  amount  of  water  pumped 
does  not  equal  the  theoretical  possibilities;  corrections  for  slip  and  other 
factors  should  be  made.  The  figures  also  do  not  take  into  account  the 
amount  of  water  lost  through  broken  pipes,  leaky  joints,  etc.  It  is  esti- 
mated that  in  some  places  almost  half  the  water  pumped  is  wasted  in 
this  way.  According  to  Whipple,  the  water  lost  and  unaccounted  for 
with  metered  supplies  amounts  to  from  15  to  50  gallons  per  day  per 
capita.  Further,  there  are  great  discrepancies  when  contrasting  differ- 
ent cities  in  the  amount  of  water  used  for  business  purposes.  The 
amount  of  water  used  in  trades  and  manufactures  varies  enormously. 
Certain  industries,  such  as  mining,  tanneries,  coal  washing,  paper  mills, 
breweries,  wool  scouring,  etc.,  require  great  quantities.  It  is  estimated 
that  in  the  iron,  coal,  and  steel  regions  of  Pennsylvania  a  quantity  of 
water  representing  the  entire  flow  of  the  Allegheny  River  passes  through 
the  large  steel,  iron,  and  other  mills  along  its  bank  several  times  before 
it  reaches  the  city  of  Pittsburgh.  Therefore,  unless  the  per  capita  con- 
sumption is  based  upon  the  amount  of  water  actually  measured  by  meter 
for  domestic  purposes,  the  figures  of  one  city  cannot  be  properly  com- 
pared with  those  of  another. 

Causes  of  Water  Waste. — Few  persons  realize  the  immense  amount 
of  water  that  is  wasted  in  almost  every  town.  Taking  it  right  through, 
probably  one-half  of  the  water  supply  of  American  cities  is  wantonly 
wasted.  \Aliile  some  of  this  is  unavoidable,  the  greater  part  of  it  could 
be  stopped.  There  are  three  principal  causes  of  this  waste:  (1)  leakage 
from  faulty  mains  and  service  pipes;  (2)  waste  from  defective  house 
fittings;  (3)  waste  resulting  from  an  unmetered  or  unmeasured  service. 
The  first  cause  includes  leaks  from  faulty  mains  and  service  pipes 
and  all  other  hidden  defects  where  the  water  escapes  unperceived  into 
drains  and  sewers  or  into  the  subsoil.  It  is  possible  to  check  a  large 
part  of  this  waste  by  the  use  of  instruments  known  as  detectors.  With 
these  instruments  leaks  may  be  located.  The  detectors  are  of  two  sorts : 
(1)  aquaphones,  instruments  resembling  a  large  stethoscope,  by  which 
a  trained  ear  may  locate  murmurs;  (2)  pitometers,  instruments  which 
measure  the  rate  of  flow  in  branch  lines  during  the  small  hours  of  the 
night,  when  practically  no  water  is  used.  In  this  way  leaks,  defective 
taps,  and  open  stopcocks  may  be  discovered.  It  requires  but  a  moment's 
calculation  to  figure  out  the  great  number  of  gallons  wasted  by  for- 
getting to  close  a  stopcock.  In  some  cities,  such  as  Washington,  in  the 
winter  time  the  water  in  many  houses  is  allowed  to  run  continuously 


DUAL  WATKR  SUPPLY  10:31 

from  the  cold  water  faucet,  in  order  to  prevent  freezing.''  The  waste 
from  this  cause  is  enormous,  and  may  be  corrected  by  properly  placing 
the  service  pipes  so  as  to  avoid  the  danger  of  freezing. 

Water  Meters. —  It  lias  been  the  universal  experience  that  nnub 
water  is  thoughtlessly  wasted  where  the  service  is  not  metered.  The 
only  objection  to  a  metered  service  is  the  prejudice  common  to  all 
innovations,  but  the  advantages  are  soon  realized  and  the  saving  is 
very  considerable.  The  introduction  of  meters  in  the  city  of  Wash- 
ington during  the  past  few  years  has  resulted  in  checking  the  waste 
by  reducing  the  total  amount  of  water  consumed  one-third,  making 
a  saving  of  from  '^0  to  30  million  gallons  of  water  a  day  without  an- 
noyance or  inconvenience  to  any  one.  This  great  saving  did  not  all 
result  from  the  metering  alone,  but  was  aided  by  the  use  of  detectors 
and  an  efficient  system  of  inspection,  which  checked  waste  from  other 
causes.  In  ]\Iilwaukee,  before  meters  were  generally  adopted,  the  water 
used  per  tap  was  1,781  gallons  per  day.  After  the  majority  of  houses 
were  furnished  with  meters,  the  amount  used  per  tap  was  only  614: 
gallons.  Buffalo  reduced  her  water  consumption  during  the  war  (1918) 
from  over  300  gallons  per  capita  to  260  with  a  survey  that  covered  only 
part  of  the  city.  Another  notable  instance  of  checking  waste  was  fur- 
nished by  Liverpool,  where  the  average  amount  supplied  daily  per  head 
was  33.5  gallons.  Deacons'  water  waste  detectors  were  introduced,  and 
these,  together  with  efficient  inspection,  reduced  the  supply  to  23  gal- 
lons without  any  restrictions  being  placed  upon  the  consumers.  At 
Shoreditch.  in  England  (population  87,000),  the  introduction  of  waste 
detectors  effected  in  the  course  of  three  years  a  diminution  of  waste 
and  undue  consumption  amounting  to  720,000,000  gallons  per  annum. 
At  Exeter  the  introduction  of  waste  detectors  reduced  the  amount  from 
75  to  12  gallons  per  head  per  day. 

It  is  estimated  by  engineers  that  45  per  cent,  of  the  water  supplied 
to  Manhattan  and  the  Bronx  is  w^asted,  and  that  if  this  waste  were 
checked  the  new  aqueduct  from  the  Catskills,  whicli  cost  over  $160,- 
000,000,  would  not  have  been  needed.  While  it  is  necessary  to  allow  a 
liberal  supply,  there  is  no  sanitary  advantage  in  waste.  Good  clean 
water  in  large  quantities  is  diflficult  to  obtain  and  expensive.  Economy 
and  avoidance  of  waste  are,  therefore,  essential. 

DUAL  WATER  SUPPLY 

The  question  of  a  dual  supply  of  water,  one  cheap  for  general  pur- 
poses and  the  other  high  class  for  personal  use,  has  often  engaged  the 
attention  of  engineers  and  sanitarians.     Ancient   Eome  had   a  sort  of 

^In  cities  where  this  practice  prevails,  more  water  is  used  in  the  winter  time 
than  in  the  summer  months. 


1023  GENEEAL  CONSIDERATIONS 

double  supply,  and  Paris  and  other  European  cities  have  it  at  pres- 
ent. The  advantages  and  disadvantages  of  the  double  system  are  evi- 
dent. Even  where  the  community  served  is  intelligent  and  careful, 
the  danger  of  a  double  system  is  very  great,  and  it  will  probably  never 
be  resorted  to  except  through  stress  of  circumstances. 

A  number  of  cities  have  a  separate  water  system  under  high  pres- 
sure for  fire  fighting.  Auxiliary  water  systems  are  often  connected  with 
the  drinking  water  mains,  and  controlled  by  means  of  check  valves,  by- 
passes, etc.  This  arrangement  is  hazardous  and  a  number  of  outbreaks 
of  typhoid  fever  have  been  traced  to  faulty  valves  or  failure  to  close  by- 
passes in  such  a  dual  system. 


SOURCES  OF  WATER 

"We  may  begin  the  circle  by  considering  that  all  water  comes  to  us 
from  the  aqueous  vapor  condensed  in 'the  form  of  rain  or  snow.  Of 
this  a  certain  amount  returns  to  the  atmosphere  by  evaporation;  the 
rest  collects  upon  the  surface  of  the  earth  or  soaks  into  the  ground. 
Some  of  it  flows  off  in  the  direction  of  surface  slope  to  join  the  ponds, 
lakes,  rivers,  or  seas,  or  some  of  it  may  penetrate  the  earth  to  variable 
depths.  The  sources  of  our  water  supply  may,  therefore,  be  classified 
as:  (1)  rain  or  snow  water,  (2)  surface  water,  including  ponds,  lakes, 
streams,  and  rivers,  and  (3)  ground  water,  including  springs  and  wells. 
This  classification  is  evidently  an  arbitrary  one,  used  for  convenience. 
There  is  no  sharp  line  of  demarcation  between  rain,  surface,  and  ground 
Avater.  Eain  water  soon  becomes  surface  water,  and  surface  water 
quickly  passes  into  the  ground ;  the  ground  water  frequently  reappears 
as  springs  to  form  streams  and  lakes  and  other  surface  supplies. 

Eain  water  is  nominally  the  purest  and  may  be  free  from  all  traces 
of  organic  matter,  but  is  liable  to  irregularity  of  composition,  and  in 
built-up  sections  it  is  difficult  to  collect  it  so  as  to  be  free  from  con- 
tamination and  fit  for  drinking.  Surface  water  frpm  inhabited  water- 
sheds is,  in  its  raw  condition,  never  entirely  safe  for  drinking  pur- 
poses. Ground  water  obtained  from  the  subsoil  of  a  catchment  area, 
free  from  sources  of  pollution,  is  usually  of  a  satisfactory  character. 
Artesian  water,  which  is  ground  water  obtained  from  the  deeper  under- 
lying strata,  is  often  so  rich  in  mineral  matters  that  it  is  unsatisfactory 
for  most  uses.  The  various  sources  of  pollution,  its  character,  and 
dangers  will  be  considered  in  subsequent  pages. 

RAIN  WATER 

Eain  water  is  really  ''distilled  water,"  that  is,  it  is  water  that  has 
been  vaporized  and  then  condensed.     The  process  of  distillation  is  one 


ROT^RCFR  OF  WATER  10-23 

of  the  best  known  methods  for  purifying  liquids  of  all  kinds.  All  the 
non-volatile  substances  are  left  behind ;  theoretically,  therefore,  rain 
water  should  approach  nearer  to  absolute  purity  than  any  other  kind 
of  natural  water.  However,  it  receives  impurities  from  the  moment 
it  condenses,  for  each  droplet  of  mist  is  formed  about  a  particle  of 
dust  in  the  air.  Tlie  rain  drop  further  absorbs  gases,  and  as  it  drops 
through  the  air  collects  a  large  amount  of  the  "dirt"  floating  in  the 
luwer  portions  of  the  atmosphere.  It  is  a  common  ob;-ervation  how  a 
shower  will  wash  the  air  so  that  it  becomes  beautifully  clear  and  clean. 
The  impurities  collected,  by  the  rain  before  it  reaches  the  surface  of 
the  earth,  while  considerable  in  amount,  are  practically  negligible  from 
a  sanitary  standpoint.  After  rain  touches  the  earth's  surface  it  becomes, 
to  all  intents  and  purposes,  a  surface  water,  unless  collected  with  special 
precautions  to  avoid  contamination.  If  collected  from  a  clean,  impervi- 
ous surface  in  the  open  country,  it  is  the  purest  of  natural  waters.  The 
use  of  rain  water  for  drinking  purposes  has  met  with  little  favor  by 
sanitarians,  despite  its  exceptional  purity,  because  it  is  so  frequently  col- 
lected and  stored  in  such  a  careless  manner  that  it  is  subject  to  impuri- 
ties. It  is  true  that  rain  water  is  not  likely  to  be  infected  with  sewage, 
nevertheless  some  of  the  dirtiest  waters  used  for  domestic  purposes  come 
from  r?.in-water  tanks.  Even  casual  inspection  will  often  show  that 
rain  water  collected  and  stored  in  the  usual  way  is  very  far  from  being 
pure,  though  rarely  infected. 

Because  rain  water  is  soft  it  recommends  itself  for  use  in  the  laun- 
dry, and  the  absence  of  lime  salts  renders  it  desirable  for  cooking.  On 
the  whole,  however,  it  is  not  considered  as  practicable  as  a  good  ground 
or  surface  Avater  for  general  domestic  supply. 

The  storage  of  rain  water  in  cisterns  is  the  principal  factor  in  keep- 
ing yellow  fever  alive  in  endemic  foci.  The  yellow  fever  mosquito 
(Stegomyia  caJopus)  breeds  by  preference  in  artificial  containers  hold- 
ing rain  water.  It  was  the  abolition  of  such  breeding  places  that  has 
protected  Philadelphia,  Boston,  and  many  other  seaports,  now  including 
Xew  Orleans,  that  formerly  fostered  the  stegomyia  and  suffered  from 
yellow  fever  epidemics.     See  page  29.5. 

Usually  it  is  advisable  to  filter  rain  water  collected  from  the  roofs 
of  buildings,  especially  if  situated  in  towns,  near  dusty  roads,  etc. 

Underground  filters  for  rain  water,  in  order  to  purify  it  before  it 
enters  the  storage  tanks,  are  sometimes  provided.  These  filters  are  for 
the  most  part  unsatisfactory.  Either  the  material  is  so  coarse  that  little 
purification  is  effected,  or  so  fine  that  it  speedily  becomes  clogged  and 
useless.  They  rarely  receive  proper  attention  and,  therefore,  are  apt 
to  become  filthy. 

Amount. — The  average  annual  rainfall  on  the  globe  is  computed  to 
be  33  inches.     The  mean  annual  rainfall  for  different  portions  of  the 


1024  GENERAL  CONSIDEEATIONS 

United  States  has  been  tabnlated  by  the  United  States  Weather  Bureau 
to  average  some  30  inches.  In  .New  England  and  the  Middle  States  it 
amounts  to  40  inches.  In  Assam  from  600  to  805  inches  have  been 
recorded,  while  in  the  Sahara  desert,  part  of  Arabia,  the  desert  of 
Gobi,  and  portions  of  Mexico,  Chile,  and  Peru  it  has  seldom  been  known 
to  rain.  Coles-Finch  states  that  it  seems  to  l)e  a  fact  that  the  atmos- 
phere of  the  earth  is  growing  drier.  The  glaciers  are  retreating,  the 
Caspian  Sea  and  many  other  lakes  are  growing  smaller,  and  the  great 
deserts  seem  to  be  extending.  Some  of  the  richest  countries  on  earth 
have  seen  their  fertility  decreasing,  mainly  owing  to  lessened  rainfall, 
and  this  is  caused,  at  least  in  part,  by  the  ruthless  destruction  of  the 
forests.  Ruined  forests  mean  flooded  rivers,  periodic  droughts,  eroded 
soil,  and  dried-up  springs. 

The  amount  of  water  given  by  rain  can  easily  be  calculated  if  two 
points  are  known — the  mass  of  rainfall  and  the  area  of  the  receiving 
surface.  The  amount  is  determined  by  a  rain  gauge  and  the  area  of 
the  receiving  surface  must  be  measured.  Roughly,  the  amount  may 
be  calculated  by  multiplying  the  area  of  the  receiving  surface  in  square 
feet  by  half  the  rainfall  in  inches,  the  result  being  in  gallons.  Here 
the  error  is  about  4  per  cent.  Thus,  according  to  Church,  one  inch  of 
rain  on  a  house  roof  20  x  20  feet  area  would  be  about  250  gallons.  With 
a  rainfall  of  40  inches  per  annum  this  would  amount  to  10,000  gallons, 
or  27  gallons  per  day. 

The  total  theoretical  amount,  however,  is  never  available,  for  the 
reason  that  some  is  lost  by  evaporation  and  the  first  flow  should  be 
wasted.  Only  a  very  small  proportion  of  water  may  he  collected  from  a 
light  shower  spread  over  a  considerable  interval,  especially  in  hot  weather, 
as  nearly  all  is  lost  by  evaporation. 

The  stations  of  Prussia  allow  the  following  average  for  evaporation, 
the  amount  evaporated  in  the  open  fallow  field  being  called  100: 


Evaporated 

Retained  More 
than  in  Open 
Fallow  Field 

Under  beech  growth 

Per  Cent. 
40.4 
45.3 
41.8 
90.3 

Per  Cent. 
59.6 
54.7 
58  "^ 

Under  spruce  growth 

Under  pine  growth 

From  cultivated  field 

9.7 

It  is  this  protection  against  evaporation  which  gives  to  the  forest 
its  chief  value  as  a  guardian  of  water  supply.  The  forest  fioor,  with 
its  irregularities  and  its  sponge-like  qualities,  moreover  stops  the  rapid 
and  ruinous  draining  of  the  surface,  with  attendant  denuding  of  the 
land,  and  favors  slow  percolation  through  the  soil  and  reinforcement  of 
the  springs. 


SOURCES  OF  WATER  1025 

The  amount  of  water  that  can  be  utilized  from  the  rainfall,  drain- 
ing' a  catihnuMit  area,  may  be  stated  as  follows:  Taking,  for  example, 
an  average  of  -KJ  inches  of  rainfall  each  year  upon  the  catchment  area, 
one-half  of  this  is  lost  by  evaporation  from  the  water  surfaces,  from 
the  surface  of  the  ground,  and  es])ccially  from  the  leaves  of  all  the  plants 
and  trees  that  grow  u})on  it.  Tlie  Other  half,  equal  to  a  rainfall  of  23 
inches,  flows  off  into  streams,  and  sooner  or  later  reaches  the  lake  or 
impouiuling  reservoir.  Tn  wet  years  the  amount  that  flows  off  is 
gi-eater;  in  dry  years  it  is  less  than  the  average;  in  the  winter  and 
spring  months  the  flow  is  very  much  greater  than  at  other  times. 

Collection  and  Storage. — The  points  of  prime  importance  in  the  col- 
lection and  storage  of  rain  water  for  domestic  purposes  are:  (1)  the 
material  and  care  of  the  surface  upon  which  it  is  caught;  (2)  the  sep- 
aration of  the  first  flow,  which  contains  most  of  the  grossest  impurities; 
(3)  the  location  and  construction  of  the  storage  cistern. 

Storage  cisterns  for  collecting  rahi  water  are  frequently  placed  under- 
ground. In  some  places  rain  water  cisterns  are  built  of  cypress  wood 
and  always  above  ground.  Tanks  of  wood  serve  their  purpose  well, 
provided  they  be  kept  full.  If  there  is  great  fluctuation  in  the  water 
line  the  tank  itself  falls  out  of  repair.  Eain  water  attacks  iron,  lead, 
zinc,  and  other  metals,  and  when  metal  cisterns  are  used  the  metal  should 
be  coated  with  a  good  asphaltum  paint.  This  applies  also  to  the  de- 
livery pipe.  Under  no  circumstances  should  lead  cisterns  or  lead 
service  pipes  carry  rain  water  used  for  drinking  purposes.  It  should 
not  be  forgotten  that  cisterns  are  liable  to  the  grossest  kinds  of  pollu- 
tion, and  they  require  frequent  inspection  and  cleansing. 

Where  the  overflow  pipes  from  rain  water  tanks  are  connected  with 
sewage  drains,  precautions  must  be  taken  to  prevent  sewage  backing  up 
and  entering  the  tank. 

Composition. — Eain  water  varies  in  composition  with  the  purity  of 
the  atmosphere  through  which  it  has  passed.  It  always  contains  dis- 
solved gases,  an  average  of  25  c.  c.  per  liter.  These  gases  are  mainly 
nitrogen,  oxygen,  and  carbon  dioxid,  taken  up  in  proportion  to  their 
absorption  coefficients,  and  not  in  proportion  to  the  amount  contained 
in  the  atmosphere.  The  gases  contained  in  rain  water  consist  of  about 
6-i  per  cent,  nitrogen,  34  per  cent,  oxygen,  and  2  per  cent,  carbon 
dioxid.  In  addition  ammonia  is  very  commonly  present.  The  amount 
of  total  solids  varies;  throughout  England  it  averages  0.39  part  per 
million.  The  principal  inorganic  constituents  of  rain  water  are  sodium 
chlorid;  nitric  acid  and  nitrates,  sulphuric  acid  and  sulphate;  a  small 
quantity  of  nitrogenous  organic  matter  is  also  present.  The  sodium 
chlorid  comes  mostly  from  the  sea  spray  lifted  into  the  atmosphere 
through  wind  action.  The  sulphuric  acid  comes  largely  from  the  waste 
products  of  burning  coal.     Rain  water  is  soft  on  account  of  the  absence 


1026  GENEEAL  CONSIDERATIONS 

of  the  alkaline  earths,  and  is  almost  always  acid  in  reaction.  It  has  a 
mawkish  taste. 

Bacteria. — Eain  water  contains  a  variable  number  of  bacteria  and 
other  microorganisms,  the  number  and  kind  depending  upon  the  germ 
population  of  the  atmosphere  through  which  the  rain  passes.  Fortu- 
nately the  various  microorganisms  floating  in  the  air  and  carried  down 
mostly  by  the  first  shower  are  not  of  serious  moment,  as  far  as  health 
is  concerned.  Pathogenic  microorganisms  in  the  air  are  few  in  num- 
ber, and  these  are  soon  killed  by  desiccation  or  the  germicidal  action 
of  the  direct  sunlight,  to  which  they  are  so  thoroughly  exposed. 

Miquel,  at  the  Montsouris  Observatory  in  Paris,  found  rain  water 
to  contain  bacteria,  pollen,  spores  of  fungi,  protbcocci,  etc.,  especially 
numerous  in  the  warmer  months.  In  the  first  showers  after  a  long  spell 
of  dry  weather  over  100,000  such  organisms  may  occur  in  a, pint. 

SURFACE  WATERS 

Surface  waters  include  rivers,  creeks,  and  smaller  streams,  large  and 
small  lakes,  ponds,  and  impounding  reservoirs,  all  resting  upon  the 
bosom  of  the  earth  in  contact  with  the  atmosphere.  Surface  waters  vary 
greatly  in  composition,  depending  largely  upon  the  character  of  the 
catchment  basin.  A  water  flowing  over  a  rocky  soil  or  through  deep 
layers  of  sand  and  gravel  is  more  likely  to  be  free  of  organic  impurities 
than  one  that  is  drained  over  loam  or  has  stood  in  swamps. 

From  the  way  in  which  surface  waters  are  exposed  they  are  subject 
to  impurities,  and  from  a  sanitary  standpoint  are  frequently  dangerous 
and  almost  always  open  to  suspicion.  Most  cities,  especially  in  America, 
depend  upon  surface  waters  for  their  supply.  This  is  usually  taken  from 
rivers,  lakes,  or  impounding  reservoirs.  It  is  scarcely  possible,  in  a  pop- 
ulous country,  to  obtain  a  large  quantity  of  surface  water  free  from 
pollution  with  human  wastes.  Sanitarians  have,  therefore,  more  and 
more  come  to  the  conclusion  that,  while  surface  waters  used  for  drink- 
ing purposes  should  be  guarded  against  contamination,  as  far  as  prac- 
ticable, they  should  also  be  purified  before  they  are  used. 

Rivers. — Streams  are  the  natural  sewers  of  the  regions  they  drain, 
and,  when  used  as  a  source  of  water  supply,  we  have  established  a 
direct  connection  between  the  alimentary  canals  of  the  people  living 
upstream  with  the  mouths  of  those  below.  Most  of  our  large  rivers 
flow  through  more  than  one  state;  therefore,  the  interstate  pollution 
of  streams  becomes  a  national  problem.  In  the  older  countries  of  Eu- 
rope, with  more  centralized  power,  laws  to  prevent  the  pollution  of 
streams  are  enforced. 

In  our  country  the  rivers  furnish  the  chief  source  of  water  supply 
for  most  of  our  large  cities.     The  succession  of  cities  and  the  combined 


SOU-RCES  OF  WATER  1027 

use  of  the  river  as  a  sewer  and  source  of  water  supply  on  such  rivers 
as  the  Merriniac,  Hudson,  Dehiware,  Ohio,  Missouri,  and  Mississippi 
are  particularly  impressive.  When  the  water  of  these  rivers  has  been 
used  in  its  raw  or  uupurified  state  much  unnecessary  sickness  has  re- 
sulted and  thousands  of  lives  have  been  lost. 

No  stream  draining  an  inhabited  region  can  be  considered  safe 
without  some  method  of  purification.  There  are  a  thousand  minor 
sources  of  pollution  that  practically  cannot  be  stopped,  even  though 
the  sewage  flowing  into  the  stream  is  treated  and  all  reasonable  pre- 
cautions taken  in  connection  with  it.  It  is  well  known  that  very  few 
sewage  purification  works  treat  all  the  sewage  from  the  districts  which 
they  serve.  Thus,  there  are  storm  overflows  and  street  wash  that  can- 
not pass  through  sewers,  and  other  sources  of  pollution. 

Looking  at  the  whole  matter  of  streams  pollution  solely  as  an 
economic  engineering  problem,  it  is  cheaper  to  purify  the  water  sup- 
plies taken  from  the  rivers  than  to  purify  the  sewage  before  it  is  dis- 
charged into  them.  The  volume  to  be  handled  is  less  and  the  cost  of 
purifying  water  per  million  gallons  is  much  less  than  the  cost  of  purify- 
ing sewage.  Further,  in  the  present  state  of  our  knowledge  water  may 
be  purified  more  efl^ectively  and  with  greater  certainty  than  sewage. 
On  the  other  hand,  it  is  perfectly  clear  to  the  sanitarian  that  the  future 
will  require  both  methods,  that  is,  a  reasonable  protection  of  our  streams 
against  pollution  and  the  purification  of  the  water  served  to  cities. 

Composition. — The  composition  of  river  water  varies  very  much, 
according  to  the  part  of  the  river  whence  it  is  taken.  ISTear  its  source 
the  water  may  be  comparatively  pure,  but  it  soon  becomes  polluted. 
The  composition  is  complex,  as  the  water  of  rivers  consists  of  a  mixture 
of  rain  water  and  ground  water,  to  which  are  added  surface  impurities. 
As  a  rule,  river  water  is  softer  than  ground  water,  but  contains  a  greater 
amount  of  organic  matter. 

Sudden  and  great  changes  in  the  character  of  river  water  are  to 
be  expected.  Other  changes,  slow  in  operation  but  serious  in  result, 
come  from  the  increasing  pollution  with  sewage  from  a  growing  popu- 
lation upon  the  upper  regions  of  the  watershed. 

Rivers  are  generally  purer  near  their  source.  The  amount  of  impuri- 
ties increases  as  we  descend  the  stream,  since  the  water  courses  are 
the  natural  drainage  channels  of  the  country,  and  the  wastes  of  human 
life  and  occupation  as  well  as  the  scourings  of  the  land  find  their  way 
into  the  streams.  It  is  for  this  reason  that  rivers,  after  passing  through 
cultivated  valleys  with  cities,  towns,  or  settlements  along  their  banks, 
often  contain  a  very  great  amount  of  mineral  and  organic  matter.  Thus, 
the  Mississippi  at  Minneapolis  contains  only  18.6  parts  of  total  solids 
per  100,000,  while  the  same  river  at  St.  Louis  contains  244.3  per 
100,000. 


1028  GENERAL  CO^^SIDERATIONS 

The  amount  of  mineral  matter  picked  up  by  a  stream  depends  largely 
on  the  geological  formation  of  the  country  and  the  erosive  power  of 
the  stream. 

Frequent  attempts  have  been  made  to  correlate  the  flow  of  streams 
and  the  stages  of  the  river  with  the  outbreaks  of  disease,  especially 
typhoid  fever.  It  is  to  be  remembered  that  the  flow  of  streams  is  depend- 
ent in  most  cases  not  only  on  the  rainfall,  but  on  springs  of  local  origin. 
Typhoid  may  be,  and  usually  is,  independent  of  the  stage  of  the  river. 
Outbreaks  are  often  connected  with  sudden  freshets  following  a  long 
dry  spell,  and  the  explanation  seems  to  be  that  the  accumulated  filth 
is  thereby  washed  down  from  the  slopes  and  banks  of  the  stream.  When 
streams  are  very  low  the  flow  becomes  sluggish,  sedimentation  and  other 
factors  influencing  self-purification  take  place  in  comparatively  short 
distances;  when  the  river  is  high  the  rapid  flow  is  more  apt  to  bring 
fresh  and  virulent  infection.  The  decline  of  t}'phoid  fever  in  Allegheny 
in  1908  and  1909  was  coincident  with  an  exceptionally  low  stage  of  the 
river.  During  the  spring  and  fall  freshets,  when  the  water  is  cold  and 
the  current  swift,  the  danger  is  the  greatest.  In  other  words,  it  is  the 
rapidity  of  flow  or  the  time  consumed  rather  than  the  stage  of  the  river 
or  the  dilution,  that  is  most  often  responsible  for  typhoid  and  other 
infections  in  river  waters. 

If  typhoid  bacilli  are  discharged  into  a  stream  which  flows  at  a  rate 
of  5  miles  an  hour,  which  is  a  comparatively  quiet  stream,  and  accept- 
ing the  usual  figures  that  the  bacteria  may  die  in  5  days,  these  organ- 
isms could  be  carried  600  miles,  usually  far  enough  to  reach  some  do- 
mestic supply.  Hence,  any  pollution  is  apt  to  reach  some  consumer 
unless  it  occurs  near  the  sea.  Xevertheless,  the  Potomac  Eiver  at  "Wash- 
ington seems  to  be  responsible  for  little  or  none  of  the  typhoid  fever  in 
that  city,  although  it  drains  an  area  of  about  11.400  square  miles,  having 
a  population  in  1900  of  about  half  a  million  and  receiving  directly  the 
sewage  of  some  45,000  persons.  The  question  of  the  self-purification  of 
streams  is  considered  on  page  1109. 

Lakes  and  Ponds. — Fresh  water  lakes  and  ponds  make  admirable 
sources  of  water  supply  when  kept  free  from  pollution  with  the  wastes 
of  human  life  and  industry.  This  is  much  more  practical  than  in  the 
case  of  rivers,  on  account  of  the  limited  area  of  the  catchment  basin 
directly  draining  into  a  small  lake  or  pond.  Lake  water  is  apt  to  be 
soft  and  free  from  serious  organic  impurities.  In  large  lakes  the  dilu- 
tion of  accidental  contamination  is  enormous,  and  the  effects  of  time, 
storage,  sedimentation,  and  other  purifying  factors  have  a  good  chance 
of  exerting  their  maximum  influence.  The  problem  from  a  sanitary 
standpoint  is  quite  different  when  we  consider  large  bodies  of  fresh 
water,  such  as  our  Great  Lakes,  or  smaller  lakes  and  ponds. 


SOURCES  OP  WATER  1029 

The  Great  Lakes. — The  lake  cities  suffer  most  from  the  mingling 
of  their  own  Pe\va<::e  with  their  own  water  supplies.  This  is  avoided 
in  part  by  build inii;  the  intakes  farther  out  into  the  lake  or  by  placing 
the  intakes  in  dt'e])  water  at  jjoiiits  where  there  seem  to  be  fairly  defi- 
nite currents,  bringing-  fresh,  clear  water  from  the  body  of  the  lake  to 
the  intake.  The  currents  are  never  constant,  being  controlled  by  the 
wind,  hence  safety  caniiut  be  secured  in  this  way.  Almost  every  lake 
city  has  at  one  time  or  another  suffered  from  outbreaks  of  typhoid  fever. 
Chicago  has  cut  a  drainage  canal  to  keep  her  sewage  from  entering  the 
lake,  so  that  it  now  flows  through  tributaries  to  the  Mississippi  River. 
This  sanitary  reform  cost  the  city  of  Chicago  upward  of  $40,000,000,  and 
it  eliminates  the  sewage  of  a  large  part  of  the  city,  but  not  including  cer- 
tain areas  of  Evanston  and  the  north  side.  Despite  this  commendable 
piece  of  sanitary  engineering  designed  to  keep  the  water  clean,  Chicago 
disinfects  its  water  supply  with  bleaching  powder. 

Hazen  points  out  that  in  the  smaller  cities  upon  the  lakes  the  min- 
gling of  the  sewage  and  water  may  be  relatively  just  as  important  as  in 
the  larger  ones.  They  have  less  money  to  spend,  their  intakes  do  not 
go  out  so  far,  their  sewers  are  apt  to  discharge  at  the  nearest  point, 
sometimes  directly  in  front  of  the  waterworks  intake.  The  water  may 
be  shallow^  and  stirred  by  the  wind  to  the  bottom,  and,  in  short,  "Menom- 
inee's sewage  in  Menominee's  water  may  be  just  as  bad  as  Chicago 
sewage  in  Chicago  water." 

The  Great  Lakes  are  so  large  and  the  dilution  and  time  intervals 
and  exposure  to  sun  and  air  are  so  great  that  there  is  practically  no 
chance  of  infection  being  carried  from  one  of  the  great  cities  to  another. 
Thus,  Chicago  sewage  would  scarcely  endanger  the  purity  of  Detroit's 
water  supply,  even  with  no  drainage  canal.  The  little  city  of  St.  Clair, 
with  2,543  inhabitants,  only  45  miles  away,  is  far  more  dangerous  to  De- 
troit. In  the  same  way  Detroit's  sewage  is  probably  harmless  at  Cleveland, 
and  Cleveland  sewage  is  harmless  at  Buffalo.  The  sewage  of  Buffalo, 
however,  is  a  great  menace  to  those  drinking  the  water  at  Magara  Falls. 

Pollution  may  travel  a  variable  distance  in  large  lakes.  At  the 
mouth  of  the  Detroit  River,  for  instance,  serious  pollution  was  shown, 
extending  normally  more  than  10  miles  into  the  lake,  and  at  other 
places  scAvage  pollution  was  shown,  extending  as  far  as  18  miles  from 
the  shore. ^  The  pollution  from  boats  passing  near  the  intake  may  also 
be  a  serious  menace. 

Most  of  the  cities  on  our  great  lakes  find  it  impracticable  to  extend 
water  pipes  into  zones  of  pure  water  on  account  of  the  great  cost  of  these 
extensions  and  the  engineering  difficulties  involved  in  placing  intakes 
beyond  a  70  ft.  depth.  Therefore,  in  most  instances,  our  lake  cities  can- 
not obtain  a  safe  water  supply  without  purification. 

'  Internat.  Joint  Commission  of  the  U.  S.  and  Canada. 


1030  GENERAL  CONSIDERATIONS 

Impounding-  Reservoirs. — Impounding  reservoirs  are  artificial  ponds 
or  lakes,  usually  made  by  throwing  a  dam  across  a  narrow  valley.  Most 
impounding  reservoirs  are  made  along  the  course  of  a  small  stream. 

The  principal  use  of  impounding  reservoirs  is  to  hold  the  excess 
of  water  of  the  winter  and  spring  flows  and  make  it  available  during 
the  summer  and  fall. 

The  impounding  reservoir  designed  to  furnish  New  York  City  with 
a  new  supply  of  water  to  supplement  the  Croton  system  is  the  largest 
artificial  reservoir  for  water  supply  in  America,  if  not  in  the  World. 
It  is  situated  in  the  Catskill  mountains,  and  is  made  by  damming 
Esopus  Creek,  and  holds  one  hundred  and  twenty  billion  gallons  of 
water.  Boston  is  supplied  from  impounding  reservoirs  on  small  streams ; 
the  Cochituate  (1848),  the  Sudbury  (1878),  and  the  Nashua  (1898). 
The  Wachusett  reservoir  stores  the  combined  water  from  the  smaller 
sources  of  supply,  and  has  a  capacity  of  63,000,000,000  gallons  of 
water.  Baltimore  has  an  impounding  reservoir  upon  the  Gunpowder 
River;  other  cities  similarly  supplied  are  Newark  and  Jersey  City  in 
New  Jersey;  Worcester,  Cambridge,  and  Springfield  in  Massachusetts; 
New  Haven  and  Hartford  in  Connecticut ;  Altoona  in  Pennsylvania,  and 
Denver  in  Colorado;  San  Francisco  and  Oakland  in  California;  and 
numerous  other  smaller  cities.  From  a  sanitary  standpoint  the  great 
advantage  of  an  impounding  reservoir  is  that  it  drains  a  comparatively 
small  area  that  is  amenable  to  control;  often  the  catchment  area  is  in 
uninhabited  hilly  or  mountainous  districts.  The  other  sanitary  advan- 
tage lies  in  the  fact  that  benefit  is  taken  of  the  great  sanitary  safe- 
guard of  storage.  Most  pathogenic  microorganisms  die  a  natural  death 
during  the  time  that  the  water  is  stored  in  a  large  impounding  reservoir. 
In  Boston  it  is  estimated  that  the  water  is  stored  an  average  of  30  days 
before  it  reaches  the  consumer.  Few  non-sporulating  bacteria  dangerous 
to  man  can  live  that  long  in  water  under  natural  conditions. 

The  chief  disadvantage  of  impounding  reservoirs  as  storage  basins 
is  that  they  are  open  to  the  air  and  light,  and  thus  favor  the  growth 
of  algae  and  other  microscopic  organisms  responsible  for  objectionable 
tastes  and  odors.  Further,  the  stagnation  of  the  water  favors  the  ac- 
cumulation of  the  products  of  decomposition,  Avhich  is  another  source 
of  evil  smells  and  vile  tastes.  The  stagnation  of  water  in  impounding 
reservoirs  and  small  lakes  and  ponds  deserves  special  mention. 

Stagnation  of  Water  in  Impounding  Reservoirs  and  Small  Lakes. — 
Hazen  points  out  that  in  our  climate,  when  a  reservoir  or  lake  is  more 
than  20  to  40  feet  deep,  the  upper  part  of  the  water  is  usually  in  cir- 
culation under  the  influence  of  the  wind,  and  the  lower  part  remains 
stagnant.  There  is  little  or  no  mixing  between  the  surface  water  and 
the  bottom  water,  except  for  two  short  periods  each  year,  one  in  the 
spring  and  one  in  the  fall.     These  periods  of  circulation  to  the  bottom 


SOURCES  OF  WATER  1031 

are  known  to  waterworks  men  as  tlic  spring  "overturn"  and  the  fall 
"overturn.'' 

During  the  summer  weather  a  stratum  of  warm  water  remains  at 
the  surface.  This  layer  may  be  ^0  feet  in  small  reservoirs,  and  40  feet  in 
great  lakes.  The  temperature  of. this  surface  layer  may  reach  75°  or 
80°  F.  or  more  in  midsummer.  The  wind  stirs  it  up  to  a  certain  depth 
(about  20  to  40  feet),  depending  upon  the  depth  of  the  reservoir  and 
the  force,  direction,  etc.,  of  the  winds. 

The  hottom  layer  is  cool  and  quiet.  As  the  air  temperature  falls 
with  the  approach  of  winter  the  surface  water  cools,  until  it  approaches 
that  of  tlie  bottom  water.  When  the  difference  in  temperature  between 
the  surface  and  bottom  layers  is  less,  the  wind  action  extends  deeper, 
until,  all  at  once,  often  when  the  wand  is  blowing,  vertical  currents 
arise,  so  that  all  the  water  in  the  reservoir  turns  over  and  mixes  from 
top  to  bottom.  The  mixing  continues  for  a  few  weeks,  until  the  tem- 
perature of  the  surface  water  falls  below  the  point  of  maximum  density, 
namely,  4°  C.  Then  the  colder  water  commences  to  accumulate  at  the 
top.  The  top  often  freezes  and  entirely  shuts  out  wind  action,  so  that 
the  period  of  winter  stagnation  is  ever  more  quiet  than  the  summer 
period.  The  spring  "overturn"  is  caused  by  a  reversal  of  the  conditions 
causing  the  fall  "overturn" ;  surface  water  is  warmed  imtil  it  reaches  the 
temperature  of  the  bottom  water,  when  the  upward  and  do"\vnward 
currents  take  place. 

It  can  readily  be  seen  that  this  phenomenon  has  much  to  do  with 
the  quality  of  the  water.  Thus,  the  organic  matter  upon  the  bottom 
of  almost  all  reservoirs  decomposes,  and  in  the  absence  of  oxygen  pro- 
duces the  vile  odors  and  nasty  tastes  of  putrefaction.  These  odors  and 
tastes  accumulate  in  the  bottom  water  until  the  fall  "overturn";  then 
they  become  mixed  with  all  the  water  in  the  reservoir.  If  the  water  is 
draTSTQ  from  the  reservoir  near  the  top,  as  it  usually  is,  there  will  be 
a  great  change  in  the  quality  of  the  water  on  the  day  of  the  fall  "over- 
turn." These  fall  changes  are  more  intense  than  those  which  take  place 
in  the  spring.  The  surface  water  is  well  charged  with  oxygen,  and,  as 
this  falls  to  the  bottom,  it  oxidizes  and  neutralizes  some  of  these  products 
of  decomposition.  Tastes  and  odors  due  to  this  cause  may  be  removed  by 
aerating  the  water  by  means  of  fountains,  cascades,  falling  over  a  dam, 
or  any  other  similar  means.  For  a  further  discussion  of  this  interesting 
subject  see  Hazen's  "Clean  Water  and  How  to  Get  It." 

Stripping. — Stripping  consists  in  removing  the  organic  matter  of 
the  surface  soil,  which  is  to  become  the  bed  of  a  reservoir.  The  ob- 
ject of  stripping  is  to  diminish  the  amount  of  putrefaction  taking  place 
in  the  bottom  of  stagnant  w^ater,  and  also  to  furnish  less  food  for  bac- 
teria and  algae.  A  number  of  the  reservoirs  in  Massachusetts  were 
first  stripped  at  considerable  expense.     It  has  been  found  that  in  the 


1032  GENEEAL  CONSIDEEATIONS 

older  reservoirs  prepared  in  this  way  putrefaction  has  not  taken  place 
for  some  years,  although  in  some  cases  putrefaction  seems  not  to  have 
been  entirely  prevented,  even  at  the  outset.  Stripping  does  not  prevent 
objectionable  grovi^ths;  it  only  reduces  them  somewhat,  because  many 
of  the  organisms  do  not  need  or  make  use  of  the  organic  matter  of  the 
soil  as  their  food  supply.  The  algae  live  rather  on  the  mineral  mat- 
ters of  the  water  and  the  air,  and,  with  the  aid  of  the  sunshine,  they 
build  up  their  own  organic  matter,  precisely  as  the  higher  plants  do 
growing  in  soil. 

GROUND  WATER 

Water  which  is  taken  from  the  ground  by  means  of  wells  or  flow- 
ing naturally  from  the  ground,  as  in  springs,  is  usually  satisfactory,  as 
far  as  injurious  impurities  are  concerned.  The  surface  waten  is  greatly 
purified  as  it  percolates  through  fine,  sandy  soil.  This  is  nature's  process 
of  filtration;  the  organic  matter  is  oxidized,  the  bacteria  are  largely 


Fig.  105. — Gkound  Water. 
A,  High  level.    B,  Low  level.     C,  Intermittent  spring. 

strained  out.  The  soil  can  take  care  of  a  large  amount  of  pollution, 
and,  if  not  overburdened,  or  if  it  has  no  cracks  or  crevices,  the  ground 
water  may  be  entirely  free  of  objectionable  organic  substances  and  bac- 
teria. In  passing  through  the  soil  the  water  takes  up  a  rather  large 
amount  of  carbon  dioxid,  which  is  set  free  by  organic  decomposition. 
The  water,  thus  acidulated,  has  a  greater  solvent  action  for  lime  and 
other  mineral  constituents,  so  that  ground  water  is  apt  to  be  harder  than 
surface  waters,  and  to  contain  a  larger  amount  of  dissolved  inorganic 
substances.  In  deeper  waters  the  solvent  action  is  favored  by  increased 
heat  and  pressure,  so  that  deep  wells  and  artesian  waters  are  frequently 
unfit  for  domestic  use  on  account  of  the  large  amount  of  inorganic 
impurities  which  they  contain,  such  as  lime,  iron,  common  salt,  etc. 

The  water  that  soaks  into  the  soil  finally  rests  upon  an  impervious 
stratum.  Such  water,  as  a  rule,  does  not  exist  in  tKe  ground  as  a  river  ^ 
or  lake,  but  occupies  rather  the  spaces  between  the  sandy  particles,  except 
in  limestone  formations.  Ground  water,  therefore,  in  any  quantity  is 
found,  as  a  rule,  in  sandy,  gravelly,  or  sandstone  formations. 

*  Leipzig  and  Pueblo  both  take  their  water  supply  from  underground 
"rivers"  flowing  through  coarse  gravel.  In  Leipzig  the  stream  is  2  miles  Avide, 
40  feet  deep  and  covered  by  6  feet  of  soil;  it  probably  represents  the  bed  of 
an  old  river. 


SOURCES  OF  WATER  1033 

Ground  water  finally  ri'iuhes  a  certain  level,  where  it  ceases  to  pass 
downward,  and  is  then  directed  in  a  horizontal  plane,  forming  a  more 
or  less  continuous  bed  of  water.  This  is  known  as  the  ground-water 
table,  which  underlies  practically  all  of  the  earth's  surface.  It  is  tapped 
when  wells  are  sunk,  and  forms  springs,  lakes  and  marshes,  where  it 
reaches  the  surface. 

It  is  only  in  limestone  regions  that  the  ground  water  exists  as  flow- 
ing rivers  or  in  large  bodies.  In  such  instances,  as,  for  example,  the 
mammoth  cave  in  Kentucky,  the  underground  river  may  appear  and 
disappear  suddenly.  The  sanitary  significance  of  water  from  limestone 
crevices  is  entirely  different  from  that  obtained  from  a  sandy  soil. 

The  surface  of  the  ground  water  does  not  follow  the  surface  of  the 
land,  but  more  approximately  the  contour  of  the  impervious  stratum  on 
which  it  rests.  It  crops  out  at  the  surface  here  and  there,  to  form  rivers, 
ponds,  lakes,  and  springs.  The  irregularity  of  the  surface  of  the  ground 
water  table  is  due  to  a  certain  extent  to  the  rainfall.  Durino-  drouo-ht 
the  level  becomes  more  and  more  uniform,  until  it  may  become  quite 
horizontal. 

Movement. — In  most  cases,  except  where  water  lies  in  deep  depres- 
sions and  pockets,  the  ground  water  is  in  constant  lateral  motion.  This 
motion  is  usually  in  the  direction  of  outfall,  that  is,  toward  the  nearest 
large  bod}'  of  water — lake,  river,  or  sea.  That  is  why  fresh  water  may 
frequently  be  obtained  by  sinking  a  well  at  the  seacoast.  In  some  places 
the  rate  of  lateral  flow  is  so  slow  as  to  be  almost  imperceptible ;  at  other 
places  it  is  comparatively  rapid.  Thus,  at  Munich,  Pettenkofer  esti- 
mated 15  feet  per  day;  at  Budapest,  Fedor  found  the  ground  water  to 
flow  at  an  average  of  167.6  feet  per  day.  The  rate  of  movement  is  de- 
pendent upon  the  pressure  behind  and  the  inclination  or  grade  along 
which  it  flows.  Slichter  ^°  estimates  that  with  a  temperature  of  50°  F. 
a  porosity  of  32  per  cent,  and  a  pressure  gradient  of  10  feet  to  the  mile, 
water  has  been  estimated  to  travel  in  a  year  in  fine  sand  528  feet,  in 
medium  sand  216  feet,  in  coarse  sand  845  feet,  in  fine  gravel  5,386 
feet. 

The  method  of  determining  the  velocity  of  ground  water  which  has 
been  used  with  satisfactory  results  by  Thiem  is  as  follows : 

Three  or  four  borings  are  sunk  to  ground  water  in  a  line  in  the 
direction  of  flow.  A  large  dose  of  salt  is  then  put  into  the  upper  "hole, 
and  at  frequent  intervals  analyses  are  made  of  water  drawn  from  each 
hole  below,  until  the  salt  content  has  reached  its  maximum  in  each  case, 
and  the  rate  of  movement  is  computed  from  these  results. 

Amount. — The  amount  of  water  that  may  be  obtained  from  the 
ground  can  only  be  determined  by  means  of  actual  pumping  tests  car- 

"  Slichter,  C.  S.:  "The  INIotions  of  Underground  Waters,"  Water  Supply 
Paper  67,  U.  S.  Geological  Survey,  1902. 


1034  GENEEAL  CONSIDERATIONS 

ried  on  for  a  sufficient  length  of  time  to  bring  about  an  approximate 
state  of  equilibrium  between  the  supply  and  the  demand,  as  determined 
by  the  level  of  the  ground  water.  It  is  rarely  practical  to  continue  such 
tests  until  perfect  equilibrium  is  reached,  for  in  many  cases  several 
years  of  operation  would  be  required  to  determine  the  ultimate  capacity 
of  a  source.  Pumping  tests  of  short  duration  are  apt  to  be  very  decep- 
tive, as  ground  water  may  exist  in  the  form  of  a  large  basin  or  reservoir 
with  very  little  movement,  corresponding  to  a  surface  pond  with  small 
watershed,  and  brief  tests  would  give  little  more  information  than  sim- 
ilar tests  on  a  pond. 

It  is  easier  in  proportion  to  get  a  little  ground  water  than  to  get 
a  large  amount,  and  for  this  reason  ground  water  supplies  are  more 
generally  available  for,  and  better  adapted  to,  the  needs  of  small  places 
than  of  large  cities.  In  the  United  States,  many  small  middle  west 
communities  are  supplied  with  ground  water  from  driven  wells. 

In  Europe,  ground  water  supplies  have  been  secured  for  many  large 
cities;  there  has  been  no  corresponding  development  in  America.  The 
reasons  for  the  greater  use  of  this  method  of  supply  in  Europe  are: 
smaller  quantity  of  water  required  per  capita,  more  favorable  geologi- 
cal conditions,  and  more  study  given  to  the  subject  and  greater  efforts 
to  secure  them,  especially  in  Germany. 

Ground  water  may  be  obtained  from :  ( 1 )  sand  and  gravel  deposits, 
(2)  sandstone  rock,  (3)  limestone  formations. 

Temperature. — The  temperature  of  ground  water  at  a  depth  of  50 
feet  is  practically  constant  and  is  the  same  as  the  mean  atmospheric 
temperature  of  the  region  under  which  it  lies.  Below  50  feet  the  tem- 
perature increases  1°  for  each  60  feet  in  depth,  on  an  average.  Waters 
lying  less  than  50  feet  below  the  surface  are  colder  in  winter  and 
warmer  in  summer,  as  they  are  acted  upon  by  external  climatic  condi- 
tions. Waters  reaching  the  surface  at  hot  springs  must  come  from 
deep  sources  as  many  of  them  have  a  temperature  of  at  least  180°  F. 
Fuller  states  that  springs  with  a  temperature  of  over  150°  F.  are  rare, 
if  they  occur  at  all  outside  of  igneous  regions.  As  this  temperature  rep- 
resents only  a  depth  of  5,000  feet  it  is  readily  seen  that  we  have  ordi- 
narily no  truly  deep-seated  springs  whatever. 

Ground  Water  from  Sand  and  Gravel  Deposits. — Water  flows  through 
sand  with  some  difficulty.  From  a  given  pumping  station  it  is  only  pos- 
sible to  draw  the  water  from  a  limited  distance.  This,  distance  depends 
upon  the  depth  and  coarseness  of  the  sand.  Therefore,  the  only  way  to 
secure  a  large  quantity  of  water  from  such  formations  is  by  the  use  of 
a  number  of  comparatively  small  pumping  stations,  separated  so  as  not 
to  draw  from  the  same  territory. 

Only  a  given  amount  of  water  can  be  secured  from  a  square  mile 
of  ground.     The  amount  depends  upon  the  rainfall,  upon  the  evapora- 


SOURCES  OF  WATER  1035 

tion  from  the  surface  of  the  ground,  from  transpiration  of  vegetation, 
and  upon  the  amount  of  storage  in  the  pores  of  the  soil. 

Most  of  the  sand  deposits  of  our  country  are  not  practically  available 
for  water  supplv  purposes,  because  the  grains  of  sand  are  too  small 
and  the  flow  of  water  through  them  is  too  slow.  It  is  only  the  coarse- 
grained sands  that  are  practically  available. 

A  few  large  cities  in  America  obtain  their  drinking  water  supplies 
from  ground  water  obtained  from  sand  and  gravel  deposits.  At  Brook- 
lyn the  conditions  are  particularly  favorable,  and  it  is  estimated  that  78 
million  gallons  of  ground  water  are  obtained  each  day  for  that  borough 
of  JSTew  York.  For  this  purpose  24  separate  pumping  stations  are  used. 
The  water  supplied  to  Camden,  X.  J.,  is  obtained  from  the  ground 
through  wells  close  to  the  Delaware  River.  This  water  filters  through 
the  sand  slowly  and  is  thus  purified.  This  method  of  adding  to  the  yield 
of  wells  is  used  in  some  places  in  Germany  and  France.  Memphis, 
Tenn.,  is  probably  the  largest  city  of  the  United  States  supplied  entirely 
with  water  drawn  from  sand  and  gravel  deposits.  In  this  case  the  water- 
bearing area  is  several  hundred  feet  below  the  surface,  and  is  below  a 
clay  layer.  Lowell,  Mass.,  obtains  ground  water  from  three  stations. 
draining  different  areas  of  glacial  drift,  while  Baton  Rouge  obtains  its 
water  from  an  artesian  well  system  2,000  feet  deep. 

Filter  galleries  are  excavations  in  sandy  formations  near  river 
banks.  Water  from  such  sources  corresponds  in  all  practical  respects 
to  the  ground  water  obtained  from  sand  and  gravel  deposits  by  means 
of  wells.  The  wells  are  preferable,  as  they  allow  water  to  be  drawn 
at  a  lower  level,  and  this  tends  to  a  drainage  of  a  greater  area,  thereby 
securing  a  larger  quantity  of  water. 

Filter  galleries  are  apt  to  furnish  a  diminishing  supply,  because  the 
pores  of  the  filtering  material  become  filled  with  the  sediment  of  the 
river  water.  When  this  happens  there  is  no  way  of  renewing  the  supply. 
In  some  torrential  streams  the  filtering  surface  is  renewed  from  time  to 
time,  but  this  usually  does  not  occur. 

Ground  water  obtained  from  sand  and  gravel  deposits  is  usually 
clean  and  free  from  unwholesome  impurities.  Xevertheless,  many  towns 
and  cities  having  such  a  supply  were  compelled  to  seek  other  sources, 
because  sufficient  water  was  not  obtainable  to  supply  rapidly  growing 
population. 

Ground  Water  from  Sandstone  Rock. — The  method  of  driving  wells 
in  sandstone  rock  differs  from  that  in  driving  wells  in  sand  or  gravel, 
but  the  collection,  storage,  and  flow  of  water  are  precisely  the  same. 

The  cementing  material,  which  binds  what  otherwise  would  be  loose 
sand  into  a  solid  rock,  often  seems  to  offer  but  little  resistance  to  the 
flow  of  water,  and  the  sandstone  for  water  supply  purposes  acts  as  so 
much  sand  would  act. 


1036  GENEEAL  COXSIDEEATIONS 

Water  dra'WTi  from  sandstone  is  always  well  filtered.  It,  however, 
is  usually  limited  in  amount,  and,  while  of  the  greatest  value  for  small 
supplies,  is  not  sufficient  for  large  communities. 

The  Marshall  and  Potsdam  sandstone  underlying  parts  of  Michigan, 
Illinois,  Wisconsin,  and  Minnesota  are  used  extensively  for  supplying 
towns  and  small  cities.  Thus,  Jackson,  Mich.,  with  a  population  of 
over  25,000,  is  one  of  the  largest  cities  so  supplied. 

Ground  Water  from  Limestone  Formations. — In  limestone  formations 
the  underground  flow  of  the  water  is  not  through  sandy  or  porous  rock, 
for  limestone  is  not  porous.  The  water  travels  through  fissures  or  pas- 
sages. When  these  are  large  they  are  called  caverns  or  caves,  as,  for 
example,  the  Mammoth  Cave  in  Kentucky.  These  caverns  or  caves  are 
natural  seams  or  cracks  enlarged  by  the  gradual  solution  and  removal 
of  the  limestone  by  the  passing  water.  Limestone  is  the  on]y  common 
rock  that  is  soluble  in  this  way,  and,  for  water  supply  purposes,  lime- 
stone formations  must  be  distinguished  from  all  others. 

The  crevices  may  be,  and  often  are,  continuous  for  many  miles. 
They  are  remarkably  tortuous  and  anastomose  freely,  and  the  direction 
and  flow  of  the  water  bear  no  relation  whatever  to  the  surface  topog- 
raphy. Pollution  at  one  point  may,  therefore,  endanger  those  using 
the  water  at  a  far  distant  place. 

Limestone  formation  has  little  ability  to  hold  the  abundant  winter 
flows  to  maintain  a  supply  through  droughts.  The  difference  between 
limestone  and  sand  in  this  respect  is  striking,  and,  from  a  sanitary 
standpoint,  the  fact  that  water  flowing  through  sand  is  filtered  and 
purified,  whereas  no  such  action  takes  place  through  limestone  fissures, 
is  significant.  While  much  water  is  frequently  available  at  one  point 
in  limestone  formations,  the  amount  is  subject  to  greater  fiuctuations, 
and  the  supply  may  fall  short  when  most  needed. 

That  contamination  at  one  point  may  soon  reappear  at  a  far  distant 
point  may  be  demonstrated  by  the  use  of  fluorescent  dyes,  or  by  the  use 
of  massive  cultures  of  some  harmless  microorganism,  such  as  yeast  or 
Bacillus  prodigiosus. 

In  our  country  San  Antonio,  Texas,  is  supplied  with  water  from 
limestone  springs.  Indianapolis  was  at  one  time  and  Winnipeg  in 
Canada  was  also  supplied  largely  from  this  source.  Paris  in  France 
is  partially  supplied  with  limestone  water.  Vienna  obtains  its  supply 
from  the  wonderful  Kaiserbrunnen  and  other  limestone  sources,  which 
are  aU  in  the  high  mountains,  where  there  is  scarcely  any  population  or 
pollution.  This  supply  is  mainly  from  the  melting  ice  and  snow  of  the 
high  mountains  which  replenishes  the  springs,  so  that  the  amount  of 
water  obtainable  is  greater  in  summer  than  winter. 

Typhoid  fever  has  been  caused  rather  frequently  by  the  use  of  ground 
water  from  limestone  formations.    This  has  been  demonstrated  in  Paris, 


SOURCES  OF  WATER 


1037 


Qoo 


)DOQQp 


Switzerland,  France,  England  and  elsewhere.    Water  supplies  from  lime- 
stone formations  must,  therefore,  be  regarded  with  suspicion. 

Wells. — A  well  is  nothing  more  or  less  than  a  hole  sunk  into  the 
earth  to  reaeh  a  su|)|)ly  of  water  and  fitted  with  some  mechanical  ar- 
rangement for  lifting  the  water  to  the  surface.  Wells  may  he  either 
shallow  or  deep,  dug,  drilled  or  driven.  The  type  depends  upon  the 
nature  of  the  material  through  which  the  well  is  sunk.  By  a  shallow 
well  is  usually  imder- 
stood  one  which  is  dug 
and  lined  with  stone  or 
brickwork.  The  cylin- 
der is  usually  5  or  6  feet 
in  diameter  and  rarely 
over  30  feet  deep. 
Driven  wells  are  made 
by  driving  an  iron  pipe 
into  a  sandy  or  gravelly 
soil.  The  iron  pipe  is 
perforated  near  its 
pointed  end,  for  the 
entrance  of  the  water. 
By  deep  wells  are 
meant  drilled  or  the 
so-called  artesian  wells. 
They  consist  of  an  iron 
pipe  or  tube  6  to  8 
inches  in  diameter,  and 
may  extend  many  hun- 
dred feet  into  the  earth. 
If  the  water  is  drawn 
from  a  depth  of  100  feet 
or  more  without  pass- 
ing an  impervious  stra- 
tum, the  well  is  usually  spoken  of  as  a  deep  well.  If  the  well  passes 
through  an  impervious  stratum  into  a  pervious  one  beneath,  in  which 
the  water  rests  upon  another  impervious  stratum,  it  is  spoken  of  as  an 
artesian  ^^  well.  Water  is  usually  pumped  from  the  well  either  by  -means 
of  the  ordinary  suction  pump  or  by  means  of  compressed  air. 

Contrary  to  the  generally  accepted  opinion  wells  are  usually  pol- 
luted from  the  surface  and  not  from  the  subsoil  drainage.  The  filtering 
power  of  the  soil  is  usually  sufficient  to  protect  the  water  drawn  from 


jfiOit^uf*-  — . 


Fig.  106. — Usual  Method  of  Pollution  and  even 
Infection  of  Wells. 


"  The  word  "artesian"  is  derived  from  Artois,  an  ancient  province  in  France 
which  was  su^^plied  with  flowing  wells.  Artesian  water  may  or  may  not  flow 
spontaneously. 


1038 


GENERAL  CONSIDERATIONS 


a  well,  unless  (1)  the  soil  is  overburdened  with  organic  matter,  or  (2) 
a  cesspool,  broken  sewer,  or  other  gross  source  of  pollution  is  very 
close,  or  (3)  channels,  fissures,  or  crevices  exist  in  the  soil  and  subsoil 


^ 


CR 


>^ooc/   Of  lror>    Cofer 


f'pes 


Fig.  107. — Pbopek  Constkuction   of  a   Wexl,   Lined  with   Bell  and   Spigot 

Vitrified  Clay  Pipe. 
Design  approved  by  the  Rural  District  Council  of  Chelmsford,  England. 

SO  that  impurities  reach  the  well  without  undergoing  the  process   of 
biologic  filtration. 

In  locating  a  well,  therefore,  much  depends  upon  the  surface  config- 
uration of  the  ground,  the  character  of  the  soil,  and  the  proximity  of 


SOURCES  OF  WATER 


1039 


possible  sources  of  pollution.  The  casing  of  the  well  should  be  soun<J 
and  tight,  preferably  of  brick  laid  in  cement  mortar,  pointed  on  the 
inside.  This  impervious  casing  should  extend  as  deeply  into  the  weU 
as  practicable,  and  after  it  is  laid  the  outer  space  between  the  casing 
and  the  earth  should  be  filled  in  with  well-tamped  clay  soil  or  concrete. 
One  of  the  most  important  points  in  the  construction  of  a  shallow  well 
is  to  extend  the  casing  at  least  18  inches  above  the  surface  of  the 
ground  and  to  build  around  it  a  shield  of  concrete  or  brick  laid  in  cement 
extendincr  in  a  circle  from  the  top  of  the  well  3  or  4  feet  wide.     This 


#^^/i^ 


Fig.    108. — PoprLAB   Idea    of   How   Wells    Become   Infected   from    Scbface 

PoLLrnox. 
This  probably  rarely  takes  place  in  rural  districts,  as  the  soil  can  usually 
hold  back  most  of  the  impurities.     The  danger  is  great,  however,  where  fissures, 
cracks,  or  crevices  exist,  or  where  sewage  enters  beneath  the  surface  of  the  soil 
from  broken  drains  or  leaky  privies,  especially  in  limestone  formations. 

shield  should  join  the  well  casing  so  as  to  make  a  tight  joint  with  the  cas- 
ing. The  iioor  of  the  well  should  rest  upon  the  top  of  the  casing,  so  that 
no  space  is  left  for  frogs,  mice,  or  bugs  to  crawl  in.  The  floor  should 
likewise  be  water-tight,  and  is  best  made  of  reinforced  concrete  with  a 
cement  surface.  If  this  is  not  practicable,  it  should  be  made  of  sound, 
hard,  tongue-and-grooved  boards  well  driven  up,  and  the  edges  painted 
with  white  lead.  Upon  this  should  be  laid  another  floor  of  similar 
material  at  right  angles  to  the  first.  The  pump  should  be  let  into  the 
floor  and  firmly  fastened  to  it,  and  protected  vrith  a  flashing  of  tin  to 
prevent  water  washing  back  into  the  well. 

The  widely  prevalent  idea  that  some  form  of  ventilation  must  be 
provided  for  a  well  is  entirely  unnecessary.  Well  water  keeps  better  in 
the  dark  and  protected  from  the  outer  air  and  dust. 


1040 


GENERAL  CONSIDERATIONS 


The  top  of  driven  wells  should  be  as  carefully  protected  as  just 
described  for  a  dug  well,  as  otherwise  the  polluted  surface  water  may 
work  down  the  sides  of  the  pipe.  Care  should  be  taken  that  the 
pipes  of  a  driven  well  near  the  surface  of  the  ground  do  not  rust  and 
become  leaky.  Such  wells  should  be  provided  with  a  heavy  top,  to 
which  the  pump  frame  should  be  tightly  bolted,  in  order  to  prevent 
the  loosening  of  the  joints  in  the  pipe  by  the  vibration  of  pumping. 
The  space  between  the  base  and  the  well  casing  of  driven  wells  should  be 
filled  with  grouting  and  overlaid  with  cement  near  the  top.  The  ground 
about  all  wells  should  slope  away  and  be  kept  clean,  and,  where  pos- 


Wmperuious  Stratum 

Fig.  109. — Depression  of  the  Grouxd  Watek  Level  by  Pumping  and  Tentjency 
TO  Draw  Near-by  Pollution  from  the  Soil  or  Cesspool. 


sible,  should  be  turfed.  The  waste  water  should  be  carried  by  pipes  to 
a  considerable  distance  from  the  well. 

Artesian  water  and  water  from  deep  wells  furnish  the  safest  and 
most  satisfactory  sources  of  supply  we  have.  Such  water  is  usually 
clear  and  of  high  sanitary  quality.  Sometimes  such  waters  contain  a 
large  amount  of  inorganic  impurities,  which  render  them  unfit  for  do- 
mestic purposes.  Frequently  they  contain  iron  in  the  ferrous  state, 
which  soon  oxidizes  upon  contact  with  the  air  and  is  thrown  out  as  an 
insoluble  ferric  salt,  which  renders  the  water  yellowish  or  brownish. 
Deep  well  waters  may  also  contain  an  excess  of  lime  salts,  common 
salt,  manganese,  or  hydrogen  sulphid,  etc. 

Water  from  shallow  wells  located  in  sandy  or  gravelly  formations 
is  entirely  satisfactory,  provided  there  are  no  nearby  sources  of  pollu- 
tion. The  proximity  of  well  and  privy  may  be  especially  hazardous. 
Shallow  wells  in  limestone  regions  must  be  carefully  guarded  and 
always  looked  upon  with  suspicion. 


SOURCES  OF  WATER 


1041 


It  is  evident  that  in  a  densely  inhabited  area,  with  miles  of  sewers, 
some  of  them  doubtless  broken  or  leaky,  and  with  the  thousands  of  privy 
vaults  which  still  survive  in  most  of  our  American  cities,  we  have 
a  more  or  less  sewage-polluted  condition  of  the  soil  favorable  for  the 
contamination  of  shallow  wells.  Shallow  wells,  on  general  principles, 
have  been  gradually  eliminated  from  all  large  cities  having  an  abundant 
water  supply.  This  danger  was  well  shown  in  the  studies  upon  typhoid 
fever  in  the  District  of  Columbia,  in  which  many  of  the  shallow  wells 
situated  within  the  city  limits  were  shown,  by  chemical  and  bacterio- 
logical analyses,  to  be  polluted. 


Fig.  110.- 


-In  a  LiMESTOXE  Formation  It  Is  Difficult  to  Tell  Anything  about 
THE  Source  of  Water  Obtained  from  a  Well. 


Wells  may  he  disinfected  with  lime,  which  has  been  found  to  be 
fairly  effective.  A  mixture  of  carbolic  acid  and  sulphuric  acid  in  suffi- 
cient quantity  will  sterilize  a  well,  but  these  substances  have  evident 
objections.  The  method  of  injecting  steam  under  a  pressure  of  two 
atmospheres  has  been  used.  The  steam  is  forced  into  the  water  until 
the  temperature  is  brought  to  near  the  boiling  point.  Bleaching  powder, 
however,  is  the  cheapest  and  most  practical  method  of  disinfecting  wells 
that  need  such  purification. 

Springs. — A  spring  is  a  stream  of  water  emerging  from  the  ground, 
its  flow  being  due  to  natural  causes.  Spring  water  does  not  differ  in 
any  essential  particular  from  the  ground  water  obtained  from  shallow 
wells.  Springs  may  be  regarded  as  natural  wells,  outcropping  where 
the  geological  formation  is  favorable.     Spring  water,  as  a  rule,  is  of  a 


1042  GENERAL  CONSIDEEATIONS 

high  degree  of  purity,  and  as  the  water  flows  spontaneously  it  can  easily 
be  utilized ;  and,  as  no  form  of  machinery  is  necessary  to  pump  it,  it  is 
less  subject  to  contamination  than  well  water.  Spring  waters  differ 
greatly  in  character,  depending  upon  the  temperature  of  the  water 
and  the  inorganic  constituents  which  it  contains.  Springs  may  be 
perennial,  the  flow  being  constant  or  intermittent. 

Fuller  classifies  springs,  according  to  their  origin,  as  gravity  and 
artesian;  and  according  to  the  kind  of  passages  traversed  by  the  water, 
as  tubular  and  fissure  springs. 

Some  of  the  largest  flowing  springs  are  found  in  Florida,  notable 
among  these  being  the  Silver  Spring  with  an  estimated  flow  of  368,913 
gallons  per  minute,  and  Blue  Springs  with  a  flow  of  349,166  gallons 
per  minute. 

Springs  may  be  polluted  from  various  sources,  and  in  much  the  same 
way  that  wells  are  polluted.  The  overlying  porous  layer  of  soil  may  be 
too  thin  to  remove  the  contamination  vt  surface  washings  from  privies, 
stables,  hog  pens,  and  other  sources  of  contamination.  This  is  prob- 
ably not  a  frequent  source  of  danger  in  such  waters.  Springs  may  be 
contaminated  from  surface  washings;  that  is,  the  infective  material  may 
be  washed  down  and  into  the  spring  by  heavy  rains,  and,  unless  the 
spring  has  a  bold  flow,  the  polluting  material  may  remain  in  it  for 
some  time.  Leaky  cesspools  above  a  spring  may  carry  dangerous  mate- 
rial almost  directly  into  the  water,  just  as  they  endanger  wells  in  pre- 
cisely the  same  way. 

The  protection  of  a  spring  against  contamination  requires  a  careful 
study  of  each  location.  Stables,  hog  pens,  and  privies  should  be  distant, 
and,  if  possible,  on  another  slope.  Soil  pollution  must  be  prevented  in 
the  neighborhood  of  the  spring,  and  animals  kept  away,  and  special  re- 
gard must  be  had  for  the  location  and  character  of  the  privy.  The 
spring  should  be  protected  above  with  a  masonry  or  concrete  wall.  This 
should  extend  well  into  the  ground,  so  as  to  guard  against  surface 
washings.  A  ditch  should  be  dug  around  both  sides  of  the  spring,  to 
carry  off  the  surface  water  and  the  neighborhood  kept  clear  of  weeds  and 
growth.  It  is  well  to  plant  grass  about  the  spring  so  as  to  keep  out  dust 
and  prevent  erosion  of  the  soil. 

In  limestone  regions  springs  are  subject  to  the  danger  already  spoken 
of  in  the  case  of  wells.  A  spring  in  such  a  region  may  be  the  same 
underground  stream  that  runs  through  the  neighbor's  back  yard  and 
disappears  in  his  meadow.  A  limestone  spring  that  becomes  muddj) 
soon  after  a  rain  should  be  regarded  as  particularly  suspicious. 


POLLUTION  AND  INFECTION  1043 


THE  SOURCES  AND  NATURE  OF  WATER  POLLUTION  AND 

INFECTION 

A  distinction  is  drawn  between  a  polluted  and  an  infected  water. 
A  polluted  water  is  one  that  contains  organic  matter  and  the  products 
of  decay,  either  of  vegetable  or  animal  origin.  An  infected  water  is 
one  that  contains  the  specific  parasites  causing  disease,  A  polluted 
water  may  not  be  particularly  harmful  to  health;  it  is  suspicious. 
That  is,  a  polluted  water  is  not  necessarily  infective ;  an  infected  water 
is  practically  always  polluted.  Practically  all  surface  waters  are  pol- 
luted ;  ground  waters  usually  show  evidence  of  past  pollution ;  that  is, 
they  contain  inorganic  salts  in  solution  resulting  from  the  mineraliza- 
tion of  organic  matter. 

The  greatest  hazard  to  man  is  found  in  a  water  polluted  with  the 
discharges  from  the  human  body — feces,  urine,  and  sputum.  There 
is  comparatively  little  danger  from  water  containing  the  wastes  of  other 
animal  life,  for  the  reason  that  few  of  the  infections  of  the  lower  ani- 
mals are  thus  transmissible  to  man.  There  is  still  less  danger  in  water 
contaminated  with  organic  matter  of  plant  origin.  Water  containing 
small  amounts  of  inorganic  substances  in  solution  plays  a  relatively 
minor  role,  as  far  as  health  is  concerned. 

From  a  sanitary  standpoint,  then,  it  is  the  wastes  of  human  life  that 
concern  us  especially.  These  may  enter  a  surface  water  directly  from 
overhanging  privies,  or  from  sewers,  or  from  washings  of  the  land. 
Ground  water  becomes  polluted  in  ways  already  discussed. 

The  prevention  of  the  pollution  of  our  streams,  lakes,  ponds,  and 
other  surface  supplies  is  an  important  sanitary  problem  with  a  large 
economic  side.  As  far  as  streams  and  large  lakes  are  concerned,  the 
most  dangerous  infection  is  that  which  is  nearby — that  is,  that  which 
is  quickly  transferred  in  a  fresh  and  virulent  form.  Distant  infection 
is  much  less  dangerous.  Cities  taking  water  from  an  average  stream 
should  prevent  the  access  of  direct  pollution  for  at  least  50  miles,  or 
better  100  miles,  above  the  intake.  Partial  protection  may  also  be  accom- 
plished by  requiring  sewage  disposal  works  for  all  towns  and  settlements, 
and  abolishing  all  overhanging  privies  upon  the  river  and  its  tributaries. 
A  sanitary  inspector  could  cover  a  large  area  for  this  purpose.  When 
these  measures  are  not  feasible,  intercepting  sewers  may  be  built,  as 
on  the  Schuylkill  at  Philadelphia.  Canals  that  parallel  a  river,  as  the 
one  upon  the  bank  of  the  Potomac,  may  receive  the  sewage  and  surface 
drainage  and  thus  protect  the  stream.  It  is  comparatively  easier  to 
guard  smaller  lakes  and  ponds  and  impounding  reservoirs. 

Simple  Tests  to  Determine  Sources  of  Pollution. — Sources  of  pollu- 
tion and  possibly  of  infection  may  often  be  determined  by  simple  tests 


1044  GENERAL  COITSIDERATIONS 

which  may  be  carried  out  by  a  layman.  These  tests  afford  valuable  infor- 
mation and  consist  in  the  addition  of  some  chemical  substance  to  the 
source  from  which  pollution  is  possible  and  then  determining  whether 
the  same  reappears  in  the  water  supply.  Eor  this  purpose  a  large  number 
of  substances  that  may  be  readily  recognized  by  their  taste,  odor,  or  ap- 
pearance may  be  used,  such  as  coal  oil,  carbolic  acid,  fluoxescin,  and  com- 
mon salt.  Coal  oil  poured  near  the  ground  of  an  artesian  well  is  an 
easy  and  convincing  method  of  establishing  the  presence  of  defective 
piping  and  surface  or  subsoil  contamination.  Nordlinger  recommends 
for  this  purpose  saprol,  which  tastes  like  naphtha  and  is  so  penetrating 
that  its  odor  may  be  readily  recognized  in  proportions  of  1-1,000,000  or 
by  taste  in  solutions  of  1-2,000,000,  Trillat  experimented  with  a  large 
number  of  dyes  and  finds  that  fluorescin  dissolved  in  alcohol  and  diluted 
with  5  per  cent,  ammonia  solution  can  be  detected  by  a  fluoroscope  in 
proportions  of  1-2,000,000,000.  The  fluoroscope  is  a  tube  of  clear  glass 
three  or  four  feet  long  and  one-half  inch  in  diameter,  closed  at  one  end 
with  a  rubber  cork.  In  such  a  tube  natural  waters  have  a  somber  blue 
color  which  changes  to  a  clear  green  if  fluorescin  is  present.  Eluorescin 
can  be  detected  by  the  unaided  eye  in  dilutions  of  0.625  part  per  million. 
This  dye  possesses  the  evident  advantage  of  not  being  precipitated  by 
the  soil  ingredients,  a  reaction  that  readily  occurs  with  most  aniline  dyes 
brought  in  contact  with  calcareous  solutions.  Salts  of  lithium  are  some- 
times used,  for  they  may  be  detected  in  the  minutest  traces  if  the  w^ater 
is  examined  by  the  aid  of  a  spectroscope. 

The  conclusion  must  not  be  drawn  that  because  these  soluble  salts 
reappear  in  the  water  microorganisms  and  dangerous  pollution  would 
likewise  find  its  way  through  the  soil  for  an  equal  distance,  for  the 
soil  has  well-known  filtering  power  when  free  from  fissures  or  open 
channels  and  is  capable  of  removing  bacteria  and  oxidizing  large  quan- 
tities of  organic  matter.  However,  these  methods  are  of  service  in  indi- 
cating the  possibility  of  danger  under  certain  circumstances  and  are 
particularly  useful  in  discovering  sources  of  pollution  near  wells  or  in 
limestone  formations. 

Massive  cultures  of  prodigiosus,  pyocyaneus,  fluorescens,  yeasts,  and 
other  microorganisms  if  not  normally  present  in  the  water  under  exam- 
ination may  be  used  to  detect  the  possibility  of  infection.  The  cultures 
are  poured  upon  the  ground  or  into  suspicious  places  and  the  water 
tested  at  varying  intervals  to  determine  whether  they  reach  the  supply. 
Careful  controls  must  be  made  beforehand  to  assure  the  absence  of  the 
particular  organism  used. 

The  Interstate  Pollution  of  Streams.— Sanitarians  have  maintained 
for  years  that  no  community  or  individual  has  a  right  to  pollute  streams 
used-  for  public  water  supplies,  any  more  than  a  man  has  a  right  ta 
poison  his  neighbor's  well.     England  enjoyed  the  benefit  of  a  Eivers 


POLLUTION  AND  INFECTION  1045 

Pollution  Commission  as  early  as  1855,  in  order  to  prevent,  remedy, 
and  remove  the  danger  of  polluted  water  su])plies.  This  commission 
adopted  a  comprehensive  system  for  the  disposal  of  sewage  and  for 
water  purification,  the  fruits  of  wliich  England  is  enjoying  today.  This 
country  has  no  law  regarding  the  interstate  pollution  of  streams,  and 
with  our  growing  population  and  increasing  amount  of  pollution  this 
is  becoming  a  live  and  pressing  sanitary  question.  After  the  Chicago 
drainage  canal  was  opened  the  city  of  St.  Louis  (state  of  Missouri)  sued 
the  city  of  Chicago  (state  of  Illinois)  through  the  federal  courts,  ask- 
ing an  injunction  against  the  pollution  of  the  Mississippi  River,  from 
which  St.  Louis  draws  its  drinking  supply.  The  testimony  occupied 
many  weeks,  and  in  published  form  takes  up  many  volumes.  The 
verdict  was  "no  cause  for  action,"  or  "not  guilty,"  that  is,  it  was  not 
proved  that  typhoid  bacilli  or  other  organisms  dangerous  to  health 
reached  St.  Louis  from  Chicago. 

The  principles  of  common  law  as  to  interstate  waters  have  been  ap- 
preciated by  some  of  the  nations  of  Europe.  Thus,  the  inhabitants 
of  a  town  in  Belgium  suffered  from  the  effects  of  a  river  polluted  by 
the  French,  and  the  French  government  not  only  compelled  the  offend- 
ing city  to  dispose  of  its  sewage  by  irrigation,  but  granted  a  subsidy 
for  this  purpose.  In  some  of  our  more  progressive  states,  as,  for  ex- 
ample, Massachusetts,  Pennsylvania,  Connecticut,  Minnesota,  New 
Hampshire,  New  Jersey,  New  York,  Vermont,  and  others,  the  State 
Board  of  Health  is  given  control  over  the  pollution  of  streams  within 
the  borders  of  the  state. 

Speaking  generally.  Jurisdiction  over  the  pollution  of  waters  in  the 
United  States  is  confined  to  the  several  states.  There  is  no  provision 
in  the  Constitution  which  gives  to  Congress  authority  in  the  premises. 
Hence,  by  the  familiar  principle  in  our  Constitution  that  the  several 
states  retain  full  sovereign  power,  except  so  far  as  such  powers  are 
restricted  by  the  national  Constitution  or  expressly  delegated  thereby  to 
the  national  government,  the  individual  states  have  full  control  of  this 
subject — a  subject  with  which  they  are  individually  impotent  to  deal 
and  which  logically  belongs  to  the  federal  government. 

Pollution  of  International  Boundary  Waters. — LTnder  terms  of  Ar- 
ticle IX  of  a  treaty  of  January  11,  1909,  between  the  United  States  and 
Great  Britain,  the  questions  of  extension  of  pollution  of  boundary 
waters  and  remedies  were  referred  to  the  International  Joint  Commis- 
sion under  date  of  August  1,  1912.  A  sanitary  survey  was  made  of  the 
Great  Lakes  District,  particular  emphasis  being  laid  on  sewage  pollu- 
tion from  cities  and  towns,  sewage  from  vessels,  saw  mill  and  other  in- 
dustrial and  household  wastes,  and  present  methods  for  their  control.  In 
general,  the  conclusions  embodied  in  their  final  report,  1919,  are  that 
it  is  "feasible  and  practicable  without  imposing  an  unreasonable  burden 


1046  GEN"ERAL  CONSIDERATIONS 

on  the  offending  communities  to  prevent  or  remedy  pollution,  both  in 
the  case  of  boundary  waters  and  waters  crossing  the  boundary.  In  case  ■ 
of  city  sewage,  this  can  best  be  accomplished  by  installing  collection  and 
treatment  works  having  special  reference  to  the  removal  of  bacteria  and 
matters  in  suspension."  The  conclusion  is  made  that  vessels  should  treat 
their  sewage  before  discharge,  as  for  instance  with  live  steam,  also  that 
water  ballast  discharge  be  regulated  with  due  regard  for  drinking  water 
intakes  for  any  neighboring  community ;  further,  that  restriction  should 
be  placed  on  disposal  of  garbage  and  carcasses  in  boundary  waters. 

The  Care  of  Catchment  Areas. — "Catchment  area,"  "watershed," 
"drainage  area,"  and  "catchment  basin"  are  terms  used  to  include  the 
area  immediately  surrounding  a  water  supply  so  situated  that  water 
falling  upon  it  will  be  directed  toward  this  supply.  The  ideal  catchment 
area  is  free  from  human  habitation  and  is  covered  with  fo-rests.  The 
catchment  areas  supplying  impounding  reservoirs  and  the  natural  ponds 
and  lakes  used  as  reservoirs  are  limited  in  area  when  compared,  for 
example,  with  the  catchment  areas  of  the  great  rivers,  from  which  many 
public  water  supplies  are  drawn.  It  is,  therefore,  possible  to  inspect  and 
control  the  former  more  readily  than  the  latter. 

It  is  often  impossible  to  remove  population  from  a  catchment  area, 
and,  in  fact,  it  is  usually  unnecessary  to  do  so.  Very  good  Avater  may 
be  drawn  from  areas  upon  which  there  is  a  large  population,  when  proper 
and  well-known  precautions  are  taken.  Thus,  there  are  776  people  per 
square  mile  upon  the  Cochituate  catchment  area,  282  upon  the  Sudbury, 
49  upon  the  "Wachusett,  furnishing  Boston's  water  supply,  and  59  upon 
the  Croton,  furnishing  Xew  York's  water  supply. 

The  prolonged  storage  of  the  water  in  large  protected  reservoirs  is  a 
sanitary  safeguard,  and  makes  the  Boston  water  and  the  Xew  York  water 
safer  than  it  otherwise  would  be.  The  greatest  danger  is  that  some 
polluted  water  will  sometimes  get  by  the  reservoir  or  flow  through  it 
by  some  short  circuit,  as  surface  currents  or  by-passes,  and  so  reach  the 
consumer,  before  it  is  subjected  long  enough  to  full  storage  conditions. 

The  proper  sanitary  care  of  a  catchment  area  requires,  first  of  all, 
sufficient  laws  granting  suitable  authority,  especially  concerning  the  dis- 
posal of  himian  wastes. 

Care  must  also  be  exercised  to  keep  out  manufacturing  wastes  and 
the  surface  washings  that  may  carry  pollution  from  human  sources  or 
undesirable  contamination  from  other  sources.  This  object  may  be  ac- 
complished in  various  ways.  The  city  should  own  the  shores  of  the 
reservoirs  and  also  as  much  of  the  land  along  the  important  streams 
as  is  necessary  to  carry  out  these  objects.  Old  sources  of  pollution  must 
be  removed,  and  new  sources  not  permitted.  Where  the  danger  from 
human  pollution  is  especially  great,  as  around  the  impounding  reservoir 
itself  or  at  nearby  suburban  settlements,  engineering  projects,   some- 


POLLUTION  AND  mPECTION  1047 

times  of  considerable  magnitutle.  are  necessary  to  carry  away  the  sewage 
and  the  surface  drainage.  A  strict  patrpl  of  the  catchment  area,  in 
order  to  supervise  picnic  and  camping  parties,  the  camps  of  construction 
gangs,  and  other  sources  of  danger,  must  be  exercised.  A  good  man  on 
the  alert  can  patrol  a  large  district,  getting  his  information  through 
various  ways,  and  personally  inspecting  all  suspicious  localities  fre- 
quently. 

In  the  investigation  of  a  stream  and  its  watershed  the  chief  points 
requiring  attention  are  the  relative  proportions  of  the  polluting  mat- 
ter and  the  flow  of  the  river  when  at  its  minimum;  the  general  char- 
acter of.  the  stream,  the  rate  of  flow,  and  the  distance  between  the 
source  of  pollution  and  the  intake  of  the  water. 

Many  Water  Boards,  having  control  of  large  tracts  of  land,  are 
planting  their  catchment  areas  with  trees  with  advantage  and  profit.  It 
is  found  that  the  presence  of  trees  adds  to  the  retention  of  water  falling 
as  rain,  lessens  evaporation,  and  cools  the  adjacent  atmosphere,  per- 
haps  aiding  condensation.  Trees  prevent  floods,  regulate  and  help 
to  purify  the  supply,  for  water  draining  through  the  soil  of  wooded  areas 
is  naturallv  cleaner  than  that  scouring  the  surface  of  barren  land. 


CHAPTEE  II 
SANITAEY  ANALYSIS  OF  WATER 

A  complete  sanitary  analysis  of  water  includes:  (1)  a  physical  exam- 
ination to  determine  color,  turbidity,  odor,  and  taste;  (2)  a  microscopic 
examination  to  determine  the  number  and  character  of  particles  in  sus- 
pension, especially  algae;  (3)  a  chemical  analysis  to  determine  the  nature 
and  amounts  of  chemical  impurities;  (4)  a  bacteriological  examination 
to  estimate  the  number  and  kind  of  bacteria;  (5)  a  sanitary  survey  of 
the  watershed,  including  the  methods  of  collecting,  storing,  handling,  and 
distributing  the  water;  and  (6)  clinical  result,  which,  after  all,  is  the 
final  test,  for  water  may  contain  impurities  or  qualities  detrimental  to 
health  that  are  not  recognizable  by  any  other  method.  Thus,  the  water 
supply  of  Vienna  from  the  famous  Kaiserbrunnen  is  particularly  pure, 
as  determined  by  laboratory  analysis.  Nevertheless,  this  water,  owing 
to  a  lack  of  iodin,  is  responsible  for  the  great  increase  in  the  number  of 
cases  of  goiter  which  has  been  observed  in  Vienna  since  its  introduc- 
tion. 

Water  is  particularly  liable  to  contamination  under  prevailing  con- 
ditions and  must,  of  necessity,  demand  increasing  watchfulness  and  a 
continual  readjustment  of  restrictions  governing  its  use. 

The  fact  that  water  is  the  most  universal  solvent  known  is  not  to 
be  neglected.  The  water  we  drink  has  come  in  contact  with  the  earth 
and  many  other  substances.  It  dissolves  many  organic  and  many  in- 
organic impurities,  few  of  which  can  be  detected  in  the  laboratory  by 
the  routine  methods  used.  The  influence  of  many  of  these  substances 
upon  health  is  unknown.  Exceedingly  small  amounts  of  poisonous  sub- 
stance in  water  may  act  injuriously  when  we  recall  how  much  water 
is  daily  taken.  All  these  facts  should  make  us  cautious  before  we  give 
a  water  supply  a  clean  bill  of  health,  and  communities  will  find  it  pays 
in  the  end  to  go  to  great  expense  to  improve  this  important  article 
of  daily  use. 

Standard  Methods.( — The  advantages  of  using  a  standard  method  are 
self-evident ;  it  at  least  gives  results  that  are  fairly  comparable  with  the 
work  of  others.  The  standard  methods  for  water  analysis  have  been 
carefully  considered  by  a  competent  committee  of  the  American  Public 
Health  Association.     The  first  report  was  published  in  the  Journal  of 

1048 


SANITARY  ANALY^S  OF  WATER  1049 

Infectious  Diseases,  Snpitlcmciil  No.  1,  May,  H'OT).'  /Xtuci  id  merits  and 
improvements  to  the  niciliod  aic  iiuhlished  from  time  to  time.  For  any- 
one not  havinfi^  sjiecial  skill  in  ( licmical  analysis  or  bacteriological  tech- 
nic  it  is  advisable  to  adhere  closely  to  the  staiidaiil  procedures.  Any 
deviation  from  these  luctlnxls  slionid  always  be  noted  in  pnblished  re- 
ports. Because  a  method  is  ''slamlard"'  does  not.  mean  that  it  has  a 
fixed  and  permanent  value  as  a  model  to  be  blindly  followed  under  all 
circumstances.  Standard  methods  are  established  by  common  consent 
as  the  rule  to  be  followed  under  ordinary  circumstances,  especially  for 
routine  work  and  by  those  who  are  not  especially  skilled  in  laboratory 
technic.  For  reasons  that  seem  self-evident,  it  is  of  special  importance 
to  follow  the  standard  methods  for  bacterial  counts.^ 

Our  standards  by  which  the  purity  of  Avater  is  judged  are  constantly 
rising.  There  is  no  doubt  thai  many  waters  now  considered  safe  and 
wholesome  will  not  be  aeee]»table  in  the  future. 

Collection  of  the  Sample. — For  a  complete  physical,  chemical,  and 
microscopical  analysis  of  water  one  liter  is  necessary.  If  the  sample  has 
been  collected  in  a  sterile  container  with  precautions  to  prevent  con- 
tamination the  same  sample  may  serve  for  the  bacteriological  examina- 
tion. Usually  the  bacteriological  samples  are  collected  separately  in 
special  bottles  holding  at  least  100  c.  c. 

The  bottles  should  be  of  hard,  clear  white  glass  and  have  a  glass 
stopper.  They  should  be  chemically  clean  and  dry  sterilized  at  160°  C. 
for  1  hour,  or  in  the  autoclave  at  115°  C.  for  15  minutes.  For  transpor- 
tation they  may  be  wrapped  in  sterile  cloth  or  paper,  but,  better,  the 
neck  may  be  covered  with  tinfoil  and  the  bottle  placed  in  a  tin  box. 
When  bacterial  samples  must  of  necessity  stand  12  hours  before  plating, 
bottles  holding  more  than  4  ounces  should  be  used.  Cork  stoppers  should 
never  be  permitted,  except  when  physical  or  microscopical  examination 
only  is  to  be  made.  Earthen  jugs  and  metal  containers  are  entirely 
unsuitcd. 

Generally  speaking,  the  shorter  the  time  elapsing  between  the  collec- 
tion and  analysis,  the  more  reliable  will  be  the  analytical  results.  If  too 
long  a  time  intervenes,  it  affects  especially  the  bacterial  tests,  for  bac- 
teria multiply  enormously  when  water  is  kept  in  a  bottle  at  ordinary  tem- 
perature. The  oxygen  consumed,  oxygen  required,  and  nitrites  are. also 
materially  affected  by  comparatively  short  delay. 

In  general,  water  must  be  analyzed  as  soon  as  possible  after  sampling. 

'  The  fourth  edition  can  be  obtained  from  the  secretary  of  the  association, 
169  Massachusetts  Avenue,  Boston,  Mass. 

Bacteriological  standard  for  Drinking  Water.  U.  S.  Public  Health  Keports, 
Nov.  6,  1914. 

^In  the  methods  for  water  analysis  described  in  this  book  the  standard 
methods  have  been  closely  followed,  and  due  acknowledgment  is  here  given  to 
the  splendid  and  self-effacing  work  of  the  committee  that  devised  them. 


1050  SANITARY  ANALYHIS  OF  WATER 

The  following  are  the  maximum  times  allowed  by  the  Standard  Methods 
of  the  American  Public  Health  Association: 

Physical  and  Chemical  Analysis: 

Ground  waters 72  hours 

Fairly  pure  surface  waters 48 

Polluted   surface  waters 12       " 

Sewage   effluence 6 

Raw    sewages 6 

Microscopic  Examination: 

Ground  waters 72 

Fairly  pure  surface  waters 24 

Waters    containing    fragile    organ- 
isms       Immediate  examination 

should  be  made  in  situ 
if  practicable. 
Bacteriological  Examinations: 
Samples  at  less  than  10°   C 24'  hours 

Care  should  be  taken  to  secure  a  sample  which  is  thoroughly  repre- 
sentative of  the  water  to  be  analyzed.  A  pump  should  be  operated  five 
minutes,  or  water  faucet  allowed  to  run  several  minutes,  before  the 
bottle  is  filled.  In  collecting  samples  of  surface  waters  the  specimen 
should  not  be  obtained  too  near  the  bank  of  the  stream  or  pond.  A  note 
should  be  made  as  to  whether  the  specimen  is  collected  from  the  surface 
or  at  what  depth  under  the  surface  it  is  taken.  It  is  always  advisable 
to  take  the  temperature  of  the  water  at  the  time  of  collection. 


ODORS  AND  TASTE 

The  purest  water  is  absolutely  devoid  of  taste  and  odor,  but  it  is 
also  insipid.  If  such  water  is  aerated  by  agitation  or  by  filtration 
through  a  porous  air-containing  substance,  it  becomes  sparkling  and 
agreeable.  The  taste  is  imparted  to  most  waters  by  the  mineral  matter 
as  well  as  the  gases  held  in  solution,  hence  the  flat,  insipid  taste  of  dis- 
tilled water.  After  a  person  becomes  accustomed  to  the  taste  of  a  par- 
ticular water  another  does  not  appeal  to  him  and  does  not  satisfy  his 
thirst  to  so  great  an  extent.  Once  having  been  accustomed  to  a  moder- 
ately hard  water,  a  soft  water  is  very  flat  and  tastes  much  like  distilled 
or  rain  water. 

Odors  in  waters  are  objectionable,  rather  than  detrimental  to  health. 
As  a  rule,  the  most  objectionable  odors  develop  in  surface  waters  and 
are  caused  by  the  growth  of  algae,  diatoms,  protozoa,  and  other  micro- 
scopic beings.     Industrial  wastes  are  sometimes  responsible  for  odors 

^Formerly  only  6  hours  were  allowed.  The  results  will  be  more  truly  rep- 
resentative of  the  bacteriology  of  the  water,  the  shorter  the  time  between  collec- 
tion and  analysis. 


ODORS  AND  TASTE  1051 

aiitl  tastes.  The  earthy  odor  of  some  grouiul  waters  is  due  to  sub- 
stances taken  up  durin<j^  the  passage  of  the  water  through  the  soil.  When 
a  well  water  becomes  offensive  it  is  evidence  of  stagnation  at  the  bottom 
of  the  well  or  the  presence  of  dead  animals.  In  the  case  of  deep  wells 
hydrogen  sulphid  and  other  inorganic  compounds  may  impart  odors  to 
the  water.  The  odors  and  tastes  which  develop  in  impounding  reser- 
voirs from  stagnation  and  putrefaction  of  the  organic  matter  have  been 
discussed  qu  page  1030. 

On  the  whole,  the  waters  of  natural  lakes  and  ponds  are  less  subject 
to  objectionable  odors  and  tastes  than  are  the  waters  of  artificial  reser- 
voirs, and  putrefaction  is  less  troublesome,  but  the  difference  is  one  of 
degree,  not  of  kind. 

The  power  of  water  to  dissolve  or  absorb  gases  and  odors  is  an  im- 
portant one,  and  explains  how  water  may  become  "contaminated"  by 
mere  exposure  to  an  impure  atmosphere,  as  when  an  uncovered  cistern 
is  placed  in  a  water-closet  or  when  an  overflow  pipe  is  directly  connected 
with  a  drain. 

Method  of  Determining  Odor. — The  odor  of  the  water  should  be 
observed  both  at  room  temperature  and  just  below  the  boiling  point. 
Odors  should  be  determined  at  room  temperature  (20°  C.)  by  shaking  a 
sample  violently  in  a  gallon  collecting,  bottle  when  it  is  half  or  two- 
thirds  full;  and  by  heating  about  150  c.  c.  in  a  500  c.  c.  Erlenmeyer 
flask  and  covered  with  a  well-fitting  watch  glass.  In  either  case  care 
should  be  taken  to  observe  the  character  of  the  odor  the  instant  the  re- 
ceptacle is  uncovered.  The  kind  of  odor  observed  may  be  described  aa 
vegetable,  aromatic,  grassy,  fishy,  earthy,  moldy,  musty,  disagreeable, 
peaty,  sweetish,  etc.,  and  the  intensity  by  such  terms  as  very  faint,  dis- 
tinct, decided,  or  very  strong. 

The  odors  and  tastes  in  water  caused  by  microscopic  organisms  de- 
serve special  consideration,  because  they  are  common  faults  in  water 
stored  in  open  artificial  reservoirs  of  all  kinds.  Certain  organisms  can 
be  distinguished  by  their  odor,  as,  for  example,  the  "fishy"  odor  of 
Uroglena,  which  is  a  protozoon  and  classed  with  the  Infusoria;  the 
"aromatic"  or  "rose  geranium"  odor  of  AsterioneUa,  which  belongs  to 
the  Diatomaceae;  and  the  '^'pig-pen"  odor  of  Anaboena,  which  is  one  of 
the  blue-green  algae.*  These  microscopic  organisms  mostly  grow  near 
the  surface  and  require  sunlight  for  their  development;  hence,  odors 
produced  by  them  never  occur  in  covered  reservoirs  or  in  waters  kept 
in  the  dark. 

Calkins  has  shown  that  the  odors  caused  by  the  undecomposed  micro- 
scopic organisms  are  due  to  compounds  of  the  nature  of  essential  oils, 
and  Whipple  points  out  that  the  amount  of  such  oil  produced  by  an 

*See  also  Whipple,  "Microscopy  of  Drinking  Water,"  John  Wiley  &  Sons, 
1914. 


\ 


/ 


ALGAE:  I.  Urogllna-xsoo  ■   2,  Spiirogyra-x  500.,  3,  Resting  Scores  OFSp'ROGr-PA-x  500, 

4    ChLAMYOOMONAS    showing   resting  condition  and  REPRCCJC^./L    300iE:S-X    lOOC 


(Year  Book,  U.  ,S'.  Dept.  of  Agr.,  1902.) 

Fig.  111. — Al3Ae  CoiiMONLY  Found  in  Wateb. 
1052 


'"\- 


ALGAE:  I.  Clathrocystis-x500:      2.  Anabaena-x  500; 

3    OSClLLATORIA-X    500;  4  .  ASTERIONE:  LLA-X  500  ; 

5,  Navigula  showing  structure  or  diatom  -x  500. 


(Year  Book,  U.  S.  Dept.  of  Agr..  inoi.) 


Fig.  112. — Algae  Commoxly  For>-D  i.x  Wateb. 
1053 


1054  SANITAEY  ANALYSIS  OF  WATER 

abundant  growth  of  the  organisms  is  quite  sufficient  to  account  for  the 
effect  observed.  He  notes  for  comparison  that  oil  of  peppermint  can  be 
recognized  when  diluted  with  water  in  the  proportion  of  one  part  of 
oil  to  fifty  million  parts  of  water,  and  that  when  AsterioneUa  is  present 
to  the  extent  of  50,000  organisms  per  c.  c.  the  dilution  of  its  oil  is 
in  the  proportion  of  about  one  part  to  two  million  parts  of  water.  Whip- 
ple further  suggests  that  the  flow  of  water  through  pipes  may  cause  dis- 
integration of  organisms  with  liberation  of  the  odor-producing  oil,  hence 
the  odor  at  the  tap  may  be  greater  than  at  the  intake. 

The  Algae  responsible  for  the  vile  tastes  and  odors  in  water  do  not 
depend  upon  organic  matter  or  the  bodies  of  other  organisms  for  their 
food  supply.     They  require  only  carbonic  acid  and  the  nitrogen   and 

mineral  matters  always  present  in 
the  water  and  in  the  air,  and  the 
sunshine  for  their  growth.  In  other 
words,    they    have    properties    com- 

-■10     rr-      r.      T^  parable    in    many    respects    to    the 

Fig.   113. — The  Oil  Droplets  in  a       |  p       i  1 

Diatom.  higher    orders     of     chlorophyll-con- 

taining vegetation. 

There  are  very  many  kinds  of  algae,  and  they  differ  greatly  in  their 
odor-producing  powers.  Most  American  impounding  reservoir  waters 
suffer  from  them,  but  some  far  more  than  others.  English  reservoirs 
seem  to  be  comparatively  free  from  this  nuisance,  probably  because  of 
the  lower  temperatures  of  the  surface  waters.  There  is  an  average  dif- 
ference of  at  least  10°  F.  between  the  surface  temperatures  of  English 
and  American  reservoirs. 

A  certain  degree  of  quiet  and  repose  is  necessary  for  the  develop- 
ment of  a  large  growth  of  algae;  that  is  why  they  never  develop  to  any 
extent  in  rivers  and  flowing  water.  Wave  action  from  wind  also  pre- 
vents growth,  and  this  seems  to  be  the  only  reason  why  large  lakes  and 
reservoirs  are  less  troubled  by  them  than  smaller  ones. 

In  most  American  impounding  reservoirs  the  water  is  drawn  from 
near  the  surface  layer,  so  as  to  avoid  the  odors  and  tastes  of  putrefaction 
in  the  bottom  water,  but  it  sometimes  happens  that  the  surface  water  is 
the  more  objectionable. 

Prevention  and  Removal  of  Tastes  and  Odors. — The  natural  flow  of 
water  in  the  bed  of  a  mountain  stream  over  stones  and  ledges  aerates 
it  very  well.  This  is  nature's  method  of  removing  undesirable  tastes 
and  odors.  Aeration  may  also  be  accomplished  by  bringing  the  water 
in  contact  with  the  air  by  devices  such  as  fountains,  waterfalls,  etc. 
Such  aeration  always  reduces,  and  sometimes  removes,  tastes  and  odors 
from  the  waters  of  reservoirs  and  small  lakes,  whether  resulting  from 
putrefaction  in  the  stagnant  bottom  water  from  growths  or  organisms 
in  the  surface  water,  or  from  gases  held  in  solution. 


COLOR  1055 

In  general  it  may  be  stated  that  filtration  alone  is  not  efficient  in 
removing  tastes  and  odors;  however,  slow  sand  filtration  has  consid- 
erable power  of  reducing,  and  in  some  cases  of  removing,  tastes  and 
odors,  but  it  cannot  be  depended  upon  when  the  raw  water  is  very 
bad. 

Intermittent  filtration  is  particularly  successful  in  removing  tastes 
and  odors.  It  is  successful  because  it  brings  the  organic  matter  in  con- 
tact with  more  air  and  in  more  intimate  contact  with  air,  and  for  a 
longer  time  in  the  pores  of  the  sand,  than  can  be  secured  in  any  other 
way. 

It  is  practically  impossible  to  prevent  the  seeding  of  reservoirs  and 
ponds  with  algae  and  other  organisms  responsible  for  the  objectionable 
odors.  The  growth  may  be  checked  and  the  odors  temporarily  con- 
trolled by  the  use  of  copper  sulphate.     See  page  1143. 

If  a  well  becomes  stagnant  at  the  bottom,  and  thus  develops  vile 
odors  from  putrefying  organic  matter,  the  trouble  may  be  corrected  by 
lowering  the  pump  to  near  the  bottom  so  as  to  prevent  stagnation,  or  by 
filling  up  all  unnecessary'  space  with  clean  gravel  and  sand. 


COLOR 

Pure  water,  when  viewed  in  small  quantities,  appears  to  be  perfectly 
colorless,  but.  when  viewed  in  bulk,  as  in  the  white-tiled  baths  at  Bux- 
ton, and  in  certain  Swiss  lakes,  it  is  seen  to  possess  a  beautiful  greenish- 
blue  tint.  A  very  small  amount  of  suspended  or  dissolved  impurity 
is  sufficient  to  obscure  this  color. 

Impure  waters  almost  invariably  exhibit  a  color  varying  from  green 
to  yellow  and  brown,  when  examined  through  a  depth  of  two  feet  in 
suitable  tiibes.  It  does  not,  however,  follow  that  a  colored  water  is, 
therefore,  polluted  or  infected. 

Color  in  surface  water  is  usually  of  vegetable  origin;  animal  matter 
contributes  but  little  color.  The  coloring  matter  is  extracted  largely 
from  dead  leaves,  bark,  and  roots,  from  soil,  and  from  peat.  It  seems 
to  be  the  same  material  as  the  coloring  matter  of  tea.  It  is  certainly 
harmless,  but  it  makes  the  water  less  pleasing  in  appearance,  and 
great  efforts  have  rightly  been  made  to  prevent  and  remove  it.  Water 
from  swamps  is  usually  highly  colored,  the  degree  of  color  depending 
■upon  the  length  of  exposure. 

Ground  waters  are  usually  colorless.  If  the  water  contains  iron  it 
will  be  perfectly  clear  on  coming  from  the  ground,  but  will  soon  turn 
a  rust}'  yellow  color.  This  is  caused  by  the  oxidation  of  the  soluble  fer- 
rous salts  to  insoluble  ferric  salts. 

Color  in  water  should  be  distinguished  from  turbidity.     True  color 


1056  SANITAEY  ANALYSIS  OF  WATEE 

is  due  to  dissolved  impurities,  turbidity  to  substances  in  suspension.  The 
"'apparent  color"  is  the  color  of  the  original  sample,  due  to  both  dis- 
solved and  suspended  matter. 

The  prevention  of  color  in  surface  waters  consists  in  draining  swamps. 
Thus,  in  the  catchment  areas  of  the  various  reservoirs  supplying  Bos- 
ton thousands  of  acres  of  swampy  land  have  been  drained  for  the  pur- 
pose of  reducing  the  color  of  the  supplies,  and  with  good  results. 

A  colored  water  may  be  bleached  by  exposure  to  sunlight  and  air, 
but  the  bleaching  of  the  water  in  reservoirs  requires  great  storage 
capacity,  and  the  drainage  of  swamps  is  likewise  very  expensive.  Ozone 
applied  in  large  amounts  also  destroys  color,  and  the  only  objection  to 
its  use  is  the  cost.  Oxygenated  compounds  of  calcium,  sodium  and  chlo- 
rin  will  also  bleach  a  colored  water. 

About  20  per  cent,  of  the  dissolved  color  in  water  may  b^  removed  to 
a  considerable  extent  by  slow  filtration  through  sand.  If  the  coloring 
matter  is  first  rendered  insoluble  by  the  use  of  coagulants  (sulphate  of 
alumina),  it  is  readily  removed  by  filtration.^  Color  is  thus  successfully 
removed  from  the  waters  used  by  Norfolk,  Ya..  Charleston,  S.  C.,,  and 
Watertown,  N.  Y.  Sulphate  of  iron  is  less  satisfactory  as  a  coagulant 
than  sulphate  of  alumina  for  the  removal  of  color. 

Method  for  Estimating  Color. — Turl^id  waters  should  always  be  fil- 
tered before  the  color  observations  are  made.  The  intensity  of  color 
may  be  determined  by  comparing  with  a  standard  platinum-cobalt  solu- 
tion; the  tint  or  shade  may  be  determined  by  comparison  with  the 
standard  color  disks  of  the  United  States  Geological  Survey  or  a  Lovi- 
bond  tintometer. 

Platinum-Col) ali  Standard. — The  standard  solution,  which  has  a 
color  of  500,  is  prepared  as  follows : 

Dissolve  1.246  grams  of  potassium  platinic  chlorid  (PtCl^SKCl) 
containing  0.5  gram  platinum,  and  one  gram  crystallized  cobalt  chlorid 
(C0CI26H2O)  containing  0.25  gram  of  cobalt  in  water,  with  100  c.  c. 
concentrated  hydrochloric  acid,  and  make  up  to  one  liter  with  distilled 
water. 

By  diluting  this  solution  with  distilled  water  to  the  50  c.  c.  gradu- 
ation mark  on  the  Xessler  tubes,  standards  are  prepared  having  colors 
of  0,  5,  10,  15,  20,  25,  30,  35,  10,  50,  60,  and  70.  These  should  be 
kept  in  jSTessler  tubes  of  such  diameter  that  the  50  c.  c.  graduation 
mark  is  between  20  and  25  cm.  above  the  bottom,  and  is  uniform  for 
all  tubes.    They  should  be  protected  from  dust  and  light  when  not  in  use. 

Procedure. — The  color  of  a  sample  is  observed  by  filling  a  standard 
Nessler  tube  to  the  graduation  mark  with  the  water  to  be  examined,  to 
a  depth  equal  to  that  of  the  standards,  and  by  comparing  it  with  the 
standards.     The  observation  should  be  made  by  looking  vertically  down- 

°  For  the  reactions  with  Alum  see  page  1141. 


TURBIDITY  1057 

ward  througli  tlie  tubes  \i\H)n  a  white  surface  placed  at  such  an  angle 
that  light  is  reflected  ui)\vard  through  the  column  of  liquid. 

Waters  that  lia\e  a  color  darker  than  70  shoukl  be  dihited  before 
making  the  comparison,  in  order  that  no  difficulties  may  be  encountered 
in  matching  hues. 

TURBIDITY 

Practically  turbidity  is  synonymous  with  muddiness.  The  turbidity 
of  surface  waters  is  usually  due  to  mud,  clay  or  silt,  also  to  finely  di- 
vided organic  matter,  microscopic  organisms,  and  a  great  variety  of  ob- 
jects. Turbidity  represents  the  amount  of  foreign  substances  in  suspen- 
sion ;  it  is  frequently,  though  incorrectly,  spoken  of  as  color.  In  a  general 
way  turbid  waters  exi<t  in  those  regions  where  color  is  not  found; 
the  former  represents  the  washings  of  a  readily  eroded  drainage  basin, 
the  latter  is  mostly  extracted  from  the  decaying  vegetation  of 
swamps. 

Pure  water  is  clear  and  sparkling,  in  proportion  to  the  amount  of 
dissolved  oxygen  and  carbonic  acid.  While  brilliancy  and  clearness  do 
not  mean  purity,  on  the  otlier  hand  turl)id  waters  are  not  necessarily 
dangerous.  A  community  for  years  may  drink  and  seem  satisfied  with 
a  turbid  water  that  is  little  less  than  liquid  mud.  This  was  formerly  the 
case  Avith  Washington  and  the  Potomac  water,  St.  Louis  and  the  Missis- 
sippi and  many  other  cities.  When,  however,  such  a  city  once  appre- 
ciates the  beautiful  appearance  of  a  clean  water,  they  complain  if  the 
turbidity  reaches  the  point  of  a  faint  opalescence.  The  turbidity  question 
is  practically  limited  to  river  waters.  Ground  waters  should  never  be 
turbid,  and,  if  so,  should  at  once  excite  suspicion.  Some  ground  waters 
become  more  or  less  turbid  through  the  precipitation  of  iron. 

All  river  waters  are  more  or  less  turbid,  but  the  differences  are 
very  great  indeed.  The  amount  of  turbidity  depends  largely  upon  the 
character  of  the  catchment  areas.  In  general,  rivers  draining  the  large 
areas  of  our  N"orth  and  East,  covered  with  glacial  drift  of  a  sandy 
character,  are  but  little  subject  to  turbidity.  Thus,  on  an  average,  the 
Merrimac  and  Connecticut  Rivers  do  not  carr}'  more  than  10  parts  per 
million  of  suspended  matter.  In  that  part  of  our  country  which  is  not 
glaciated,  and  this  includes  the  lower  Susquehanna  basin,  much  of  the 
Ohio  basin,  and  the  Missouri  basin,  and  all  to  the  south  of  them,  tur- 
bidity is  often  present  in  large  amounts,  and  consists  largely  of  clay 
in  extremely  fine  particles.  The  water  often  runs  turbid  in  these  streams 
continuously  for  weeks  and  even  months  at  a  time.  The  Missouri  River 
carries  the  largest  amount  of  sediment  of  any  of  our  rivers  largely 
used  to  supply  water.  The  annual  average  runs  as  high  as  1,200  or 
1,500  parts  of  sandy  matter  per  million.    In  winter  it  falls  to  200  parts 


1058  SANITAEY  ANALYSIS  OF  WATEE 

or  less,  while  in  midsummer  it  rises  for  weeks  and  even  months  to  5,000 
parts  or  more. 

If  the  turbidity  is  sufficiently  coarse-grained  it  may  be  removed  by 
sand  filtration  without  previous  chemical  treatment.  Very  turbid  waters 
can  be  cleared,  in  part,  in  settling  basins;  this  lightens  the  work  of 
the  filters  and  reduces  the  cost.  Scrubbers,  which  are  preliminary  rough 
filters,  may  also  be  used  to  protect  the  sand  filters.  In  many  instances 
the  individual  particles  of  clay  which  make  up  the  turbidity  are  much 
smaller  than  the  bacteria.  They  will  not  settle  out,  even  after  prolonged 
storage,  and  they  cannot  always  be  removed  by  filtration  alone.  There 
is  only  one  known  way  of  removing  such  turbidity,  and  that  is  by  coagu- 
lation or  chemical  precipitation.  The  substances  most  commonly  used 
for  this  purpose  are:  aluminum  sulphate,  alum,  or  sulphate  of  iron. 
See  page  1141. 

This  is  successfully  done  with  very  muddy  supplies  at  New  Orleans, 
Nashville,  Eichmond,  St.  Louis  and  many  other  river  towns. 

With  reference  to  the  influence  of  the  suspended  matter  upon  health 
we  find  some  conflict  of  opinion.  Kober  states  that  water  containing  50 
parts  per  100,000  or  30  grains  of  solid  matter  per  gallon  is  unfit  for 
drinking  purposes,  on  account  of  its  irritating  effects  upon  the  gastro- 
intestinal tract.  Apart  from  this,  turbidity  appears  to  have  no  special 
sanitary  significance. 

Methods  for  Estimating'  Turbidity. — There  are  three  methods  by 
which  the  degree  of  turbidity  may  be  determined:  (1)  the  platinum 
wire  method,  which  consists  of  determining  the  depth  of  water  through 
Avhich  a  platinum  wire  of  standard  dianieter  may  be  seen;  (2)  com- 
parison with  waters  of  standard  turbidity,  made  by  adding  1  gram  of 
Pear's  "precipitated  fuller's  earth"  sifted  through  a  200-mesh  sieve,  to 
1  liter  of  distilled  water ;  this  is  known  as  the  silica  standard ;  and  has  a 
turbidity  value  of  1,000;  (3)  the  amount  of  suspended  particles  in 
water  may  be  determined  in  special  instruments  known  as  turbidimeters 
or  diaphanometers.  These  instruments  consist  of  a  graduated  glass 
tube  with  a  flat  polished  bottom,  inclosed  in  a  metal  case.  This  is  held 
over  an  English  standard  candle,  and  so  arranged  that  one  may  look 
vertically  down  through  the  tube  and  see  the  image  of  the  candle.  The 
observation  is  made  by  pouring  the  sample  water  into  the  tube  until 
the  image  of  the  candle  just  disappears  from  view.  The  graduations 
on  the  tube  correspond  to  turbidities  produced  in  distilled  water  by 
certain  numbers  of  parts  per  million  of  the  silica  standard. 

The  standard  of  turbidity  adopted  by  the  United  States  Geological 
Survey  ^  consists  of  a  water  which  contains  100  parts  of  silica  per  mil- 
lion, in  such  a  state  of  fineness  that  a  bright  platinum  wire  1  millimeter 
in  diameter  can  just  be  seen  when  the  center  of  the  wire  is  100  milli- 
*  U.  S.  Geolog.  Survey,  Div.  of  Hydrography,  Circula/r  No.  8,  1902. 


REACTION"  1059 

meters  below  the  surface  of  tlie  water  and  the  eye  of  the  observer  is  1.2 
meters  above  the  wire,  the  observations  being  made  in  the  middle  of  the 
day  in  the  open  air,  but  not  in  sunlight,  and  in  a  vessel  so  large  that  the 
sides  do  not  shut  out  the  light  so  as  to  influence  the  results.  The  tur- 
bidity of  such  water  is  taken  as  100,  and  all  turbidity  readings,  no 
matter  what  method  is  used,  should  conform  with  this  method. 

Where  only  an  occasional  analysis  is  made  for  general  purposes  it  is 
suflicient  to  record  the  seiliiiicnt  ami  tiii'l)i(lity  as  very  slight,  distinct, 
or  decided. 

Turbidity  determinations  should  be  made  as  a  routine  to  help  guide 
the  ethcient  and  economic  operation  of  a  filter  plant;  especially  where 
a  coagulant  is  used,  to  fix  the  dose. 


REACTION 

The  alkaline  reaction  of  natural  waters  ordinarily  depends  upon  the 
carbonate  and  bicarbonate  of  calcium  and  magnesium.  In  some  waters 
in  the  West  it  also  includes  the  carbonate  of  sodium  and  of  potassium. 
The  alkalinity  of  water  is  determined  by  titrating  100  c.  c.  of  the  sample 
with  ^  sulphuric  acid,  using  4  drops  of  a  solution  of  lacmoid  as  an 
indicator.  The  lacmoid  solution  consists  of  2  grams  in  one  liter  of 
50  per  cent,  alcohol.  The  last  cubic  centimeter  or  two  of  acid  must 
be  added  while  the  sample  is  almost  at  the  boiling  temperature,  and 
the  end  reaction  is  not  read  until  a  drop  of  acid,  striking  the  surface  of 
the  liquid,  sinks  to  the  bottom  of  the  dish  without  producing  a  change 
in  the  uniform  reddish  or  purplish  color  of  the  solution.  Erythrosin 
may  be  used  as  an  indicator  when  it  is  desired  not  to  use  heat.  The 
number  of  cubic  centimeters  of  ^  sulphuric  acid  used,  when  multiplied 
by  ten,  gives  the  number  of  parts  per  million  of  alkalinity  in  terms  of 
calcium  carbonate. 

Under  certain  circumstances  rain  water,  water  from  peat  bogs,  and 
water  from  coal  mines,  tanneries,  etc.,  have  an  acid  reaction.  In  min- 
ing regions  waters  are  frequently  acid  from  high  quantities  not  only 
of  CO,,  but  also  of  sulphuric  acid  and  various  sulphates — those  of  iron 
and  aluminum  giving  an  acid  reaction.  When  these  are  present,,  the 
total  acidity  is  determined  by  titrating  the  water  in  the  cold  with  a 
5^  sodium  carbonate  solution,  using  4  drops  phenolphthalein  as  an  in- 
dicator.   The  calculation  is  the  same  as  that  for  alkalinity. 

Mine  water  is  that  which  is  constantly  flowing  from  the  coal  and 
surrounding  strata.  It  is  collected  in  ditches  at  one  side  of  the  gang- 
ways and  tunnels,  and  is  allowed  to  flow  to  the  lowest  point  in  the  mine 
or  to  the  foot  of  the  shaft,  from  which  it  is  pumped  to  the  surface. 


1060  SANITARY  ANALYSIS  OF  WATEE 

Large  quantities  of  this  and  other  water  are  used  to  wash  the  coal.  This 
water  is  acid.     The  spent  tan  liquors  from  tanneries  are  also  acid. 

Eain  water  collected  in  the  vicinity  of  towns  has  usually  a  slight 
acid  reaction  and  acts  upon  lead.  The  free  acid  in  rain  water  is 
apparently  sulphuric,  no  doubt  derived  from  the  sulphur  in  the  coal 
burned. 

Water  from  marshes,  swamps,  and  especially  from  peat  bogs  may 
have  a  markedly  acid  reaction,  especially  in  dry  weather,  when  the 
flow  will  be  comparatively  small.  Heavy  storms  wash  out  the  water 
which  has  long  been  in  contact  with  the  decaying  vegetation.  The  acidity 
in  this  case  is  due  to  organic  acids. 

When  the  collection  of  an  acid  water  cannot  be  avoided,  arrangements 
should  be  made  for  adding  lime  or  some  other  suitable  alkaline  substance 
capable  of  completely  neutralizing  the  acid,  as  without  some  such  ar- 
rangement the  consumers  of  the  water  run  tha  risk  of  lead  poisoning, 
provided  lead  service  pipes  are  used.  A  river  water  suddenly  turning 
acid  in  reaction  plays  havoc  with  a  slow  sand  filter.  This  has  occurred 
in  the  Pittsburgh  filter. 

TOTAL  SOLIDS 

The  total  solids  or  residue  on  evaporation  is  obtained  by  evaporat- 
ing a  given  quantity  of  water  to  dryness,  when  a  grayish-white  residue, 
composed  of  mineral  and  some  organic  matter  which  has  been  held  by 
the  water  in  suspension  and  in  solution,  will  be  obtained.  The  amount 
of  this  residue  varies  with  the  character  of  the  water,  and  furnishes  an 
index  of  the  total  quantity  of  foreign  impurities,  and  further  furnishes 
a  rough  index  of  the  relative  quantity  of  inorganic  and  organic  sub- 
stances which  make  up  these  impurities. 

Method. — Place  100  c.  c.  of  the  water  in  a  clean  platinum  dish. 
Evaporate  to  dryness  on  a  water  bath,  and  finish  the  evaporation  for 
one  hour  or  to  constant  weight  in  an  oven  at  103°  C.  to  180°  C.  The 
temperature  used  should  be  mentioned  in  the  report.  Now  place  the 
platinum  dish  in  a  desiccator  over  sulphuric  acid  until  cool,  and  weigh. 
The  increase  in  weight  gives  the  total  solids,  or  residue  on  evaporation. 
This  weight  in  milligrams  multiplied  by  10  gives  parts  per  million. 

The  platinum  dish  containing  this  residue  is  now  heated  to  a  dull 
red  heat.  Allow  the  dish  to  cool  and  moisten  the  residue  with  a  few 
drops  of  distilled  water.  Dry  the  residue  in  an  oven,  cool  in  a  desic- 
cator and  again  weigh.  The  difference  in  weight  is  called  the  *^loss  on 
ignition,"  and  the  weight  of  the  substances  remaining  in  the  platinum 
dish  is  known  as  the  "fixed  residue."  The  loss  on  ignition  is  an  index 
of  the  amount  of  organic  matter  in  the  water.  A  portion  of  the  loss, 
however,  may  be  due  to  ammonia  or  other  volatile  compounds  and  un- 


HARDNESS  1061 

stable  mineral  salts.  The  fixed  residue  is  an  index  of  the  mineral  con- 
tent of  the  water.  With  waters  low  in  organic  matter,  but  relatively 
high  in  iron,  the  fixed  residue  is  occasionally  used  as  a  matter  of  conven- 
ience for  the  determination  of  iron.  In  water  analysis  it  is  usual  to 
note  the  character  of  the  odor  u])on  ignition  of  tlie  residue.  Tliis  may 
be  earthy,  or  may  suggest  organic  niatter  of  vegetable  origin  or  animal 
origin.  Such  determinations  have  little  value  in  determining  the  sani- 
tary character  of  a  water. 

The  amount  of  total  solids  in  a  water  depends  upon  the  character 
of  the  soil  with  wliich  the  water  has  been  in  contact,  the  length  of  expos- 
ure, and  the  amount  of  carbon  dioxid  in  the  water  to  favor  the  solution 
of  inorganic  salts.  Some  mineral  springs  contain  very  large  amounts  of 
total  solids,  derived  from  deeply  situated  natural  deposits,  as,  for  ex- 
ample, the  springs  at  Saratoga,  Carlsbad,  Kissingen,  etc. 

The  permissible  amount  of  solids  as  represented  by  the  residue  on 
evaporation,  which  consists  of  the  dissolved  mineral  constituents,  can- 
not be  arbitrarily  stated,  but  500  parts  per  million  are  generally  held 
as  excessive. 

HARDNESS 

Hard  water  is  objectionable  because  it  wastes  soap  and  affects  the 
skin  unpleasantly;  it  is  less  satisfactory  than  soft  water  for  cooking 
and  washing;  it  produces  scale  in  boilers  and  is  objectionable  in  some 
industries  such  as  paper  mills.  The  traveler  is  unpleasantly  reminded 
of  the  effect  of  abruptly  changing  from  a  soft  to  a  hard  water,  or  vice 
versa,  which  results  in  simple  gastro-intestinal  disturbances,  which  are 
temporary  in  effect.  Hardness  in  water  is  more  of  an  economic  question 
than  one  of  sanitary  interest,  except,  perhaps,  as  the  encouragement  of 
the  use  of  soap  and  cleanliness  is  of  fundamental  importance  in  hygiene 
and  sanitation.  Hardness  in  water  is  due  to  the  presence  of  the  soluble 
salts  of  the  alkaline  earths — especially  calcium  and  magnesium.  These 
salts  form  a  curd  with  soap  instead  of  a  lather,  hence  more  or  less  soap 
must  be  wasted  in  decomposing  the  lime  and  magnesia  compounds 
before  a  lather  will  form.  Thus,  one  grain  of  calcium  carbonate,  for 
example,  will  use  up  8  grains  of  soap  before  a  lather  can  be  produced ; 
in  this  way  hard  water  causes  an  enormous  waste  of  soap.  In  Eu-rope, 
hardness  is  usually  expressed  in  degrees.  Each  degree  corresponds  to 
one  grain  of  carbonate  of  lime  or  its  equivalent  of  other  lime  or  mag- 
nesium salts  in  a  gallon  of  water. 

The  hardness  of  water  is  called  "temporary"  or  "permanent,"  de- 
pending upon  the  solubility  of  the  salts  it  contains.  Temporary  hardness 
is  due  to  calcium  or  magnesium  carbonate  held  in  solution  as  a  bicar- 
bonate by  the  dissolved  COg.    The  hardness  is  "temporary"  because  the 


106^  SANITAEY  ANALYSIS  OF  WATER 

CO2  is  driven  off  by  boiling,  and  the  soluble  bicarbonates  are  precipi-. 
tated  as  insoluble  carbonates/    The  reaction  is  as  follows: 

CaaCCOs)^  +  heat  ^CaCOa  +  CO.  +  H2O 

Calcium  bicarbonate  =     Calcium  carbonate 

(Soluble)  (Insoluble) 

Permanent  hardness,  on  the  other  hand,  is  due  mainly  to  sulphates 
and  chlorids  of  calcium  or  magnesium.  These  salts  are  stable  and,  there- 
fore, are  not  precipitated  by  boiling. 

Waters  under  4  degrees  of  hardness  may  be  considered  soft,  those 
exceeding  12  degrees  hard.  Fifty  parts  per  million  of  calcium  sulphate 
and  chlorid  of  magnesium  is  usually  regarded  as  excessive.  In  the  lake 
cities,  100  parts  per  million  is  considered  satisfactory,  yet  such  a  hard- 
ness in  eastern  Atlantic  cities  would  be  considered  unsatisfactory.  Boiler 
scale  is  usually  due  to  deposits  of  sulphates  and  carbonates  of  calcium 
and  magnesium. 

Eain  water  is  always  soft ;  surface-  waters  vary,  but  are  usually  not 
very  hard;  ground  waters  are  apt  to  be  hard. 

Two  conditions  must  be  present  to  make  a  ground  water  hard :  first, 
the  material  through  which  the  water  passes  must  contain  lime  or  mag- 
nesia, and,  second,  the  conditions  must  be  favorable  for  dissolving  it. 
The  latter  practically  means  that  CO2  must  be  present. 

Waters  drawn  from  limestone  regions  vary  greatly  in  hardness.  Eain 
water  contains  but  little  carbonic  acid  and,  therefore,  has  little  power 
of  dissolving  lime.  The  principal  source  of  the  carbonic  acid  in  ground 
water  is  from  the  soil ;  and  conies  from  the  decomposition  of  organic  mat- 
ter. The  hardness  of  water,  therefore,  depends  more  upon  the  nature 
of  the  catchment  area  than  upon  the  amount  of  lime  in  the  various 
materials  over  which  the  water  flows.  Thus,  the  water  supply  of  Vienna 
is  comparatively  soft,  notwithstanding  that  it  comes  entirely  from  lime- 
stone rocks.  The  mountainous  region  which  forms  the  catchment  area 
is  barren  and  sterile,  and  the  water  does  not  get  the  carbonic  acid  needed 
to  dissolve  the  lime.  The  Winnipeg  water  drawn  from  limestone  under- 
lying the  rich  prairies  is  excessively  hard.  It  is  interesting  to  note  that 
many  deep  well  waters  of  eastern  Massachusetts  are  comparatively  soft, 
although  they  contain  large  amounts  of  carbonic  acid. 

The  Clark  Method  of  Softenings  Water. — Lime  is  added  to  the  water 

either  in  the  form  of  freshly  slaked  lime  or  milk  of  lime.     The  calcium 

hydroxid  unites  with  the  carbon  dioxid  in  the  water,  forming  calcium 

carbonate,  which   is  insoluble,   and  at  the  same  time  percipitates  the 

calcium  carbonate  held  in  solution  in  the  water  by  the  COg.     Sodium 

carbonate  is  used  to  reduce  the  permanent  hardness  of  water  due  to 

sulphates. 

^Calcium  carbonate  is  very  slightly  soluble  in  cold  water — 30  parts  per  mil- 
lion; magnesium  carbonate  880  parts  per  million. 


HARDNESS  1063 

When  bicarbonate  of  linio  or  ma^esia  are  precipitated  with  lime 
water  the  following  reaction  lakes  place: 

Cn(TTCO.0=  +  Ca(0TI)2  =  2CaC0,  +    2TI.0 

Calcium  bicarbonate  -j-  Calciiiin  bydroxid  =  Calcium  carbonate  -j-  Water 

CaCOa  =  100  CaO  r=  5()  2  X  100  2  X  18 

(Note:  The  hardness  of  water  is  always  expressed  in  terms  of  CaCOa, 
therefore,  all  calcium  and  magnesium  salts  wbich  cause  hardness  are  re- 
duced to  terms  of  CaCOs. 

The  amount  of  lime  added  is  weighed  as  unslaked  lime  (CaO),  therefore, 
the  molecular  weight  of  slaked  lime  (CaOtL)  is  expressed  in  terms  of  CaO.) 

One  grain  of  CaO  per  gallon  =  17.1  parts  per  million. 
17.1X  W=  31  parts  per  million  as  CaCOg. 

Or,  100  parts  per  million  CaCO^  will  require  3.2  grains  per  gallon. 
CaO  =  -lo5  pounds  per  million  gallons. 

When  sulphates  and  chlorids  of  lime  and  magnesia  are  precipitated 
with  soda  ash^  the  reactions  are: 

CaSO,  +  N"a,C03  =  CaCOa  +  Na^SO, 

Calcium  sulphate  +  Sodium  carbonate  =  Calcium  carbonate  +  Sodium  sulphate 
CaCOa  =:  100  106  100  142 

1  grain  of  Na^COg  per  gallon  =  17.1  parts  per  million. 
17.1X  {^  =16  parts  per  million  as  CaCOg,  but  present  as  CaSO^. 
Or,  100  parts  per  million  will  require  6.4  grains  of  NagCOg  per  gal- 
lon =  900  pounds  per  million  gallons. 

Softening  Water  with  a  Zeolite-Permutit. — This  is  an  efficient  and 
automatic  method  useful  for  softening  water  for  household  or  other  pur- 
poses. Zeolites  have  the  property  of  exchanging  the  sodium  base  which 
they  contain  for  other  bases  brought  into  contact  with  them.  The}'' 
exist  naturally  in  soils,  where  they  play  the  important  role  of  holding 
potassium  and  other  alkaline  bases  in  the  soil  and  thus  preventing  their 
being  washed  away  with  the  rain  water. 

For  the  purpose  of  water  softening,  a  synthetic  exchange  silicate 
(Permutit)  is  now  found  upon  the  market.  Synthetic  exchange  silicates 
are  produced  commercially  by  fusing  felspar,  kaolin,  pearl  ash  and  soda. 
The  glass  thus  produced  is  crushed  and  lixiviated  to  remove  the  soluble 
silicates.  In  passing  water  through  one  of  these  "exchange  silicates,'"' 
the  calcium  and  magnesium  are  entirely  removed  from  the  water,  and 
exchanged  for  the  sodium  of  the  zeolite.  The  zeolite  can  be  rejuvenated 
with  a  10  per  cent,  solution  of  sodium  chlorid.  The  Permutit  process 
is  used  to  soften  water  in  homes,  hotels,  laundries,  textile  and  other 
industries,  and  to  prevent  boiler  scale. 

Methods. — The  hardness  of  water,  both  temporary  and  permanent,  is 
determined  by  the  soap  method.  By  far  the  most  accurate  method  of 
determining  the  true  temporary  hardness  due  to  the  bicarbonate  alkalin- 


1064 


SANITAEY  ANALYSIS  OF  WATER 


ity  is  to  titrate  the  original  sample  of  water,  and  also  some  of  the  water 
after  boiling,  with  ;5^  sulphuric  acid,  using  lacmoid  or  erythrosin  as  an 
indicator,  as  already  described  under  Eeaction,  page  1059. 

The  soap  method  is  carried  out  as  follows :  Measure  50  c.  c.  of  the 
water  into  a  250-c.  c.  bottle  and  add  the  standard  soap  solution  in  small 
quantities  at  a  time  (from  0.2  to  0.3  c.  c),  shaking  the  bottle  vigor- 
ously after  each  addition  until  a  lather  forms  over  the  entire  surface  of 
the  water,  and  remains  continuous  for  5  minutes  after  the  bottle  is  laid 
upon  its  side.  The  standard  soap  solution  is  made  by  adding  100  grams 
of  dry  white  Castile  soap  to  1  liter  of  80  per  cent,  alcohol;  this  is 
standardized  against  a  known  calcium  chlorid  solution.  From  the 
amount  of  soap  solution  added,  the  quantity  of  calcium  carbonate  equiva- 
lent to  each  cubic  centimeter  of  the  soap  solution  is  indicated  in  the 
following  table : 

Table  of  hardness,  showing  the  parts  per  million  of  calcium  carbonate  (CaCOs) 
for  each  tenth  of  a  cubic  centimeter  of  soap  solution  when  50  c.  c.  of  the 
sample  are  used 


c.  c.  of  Soap 

0.0 

0.1 

0.2 

0.3 

0.4 

0.5 

0.6 

0.7 

0.8 

0.9 

Solution 

c.  c. 

c.  c. 

c.  c. 

c.  c. 

c.  c. 

c.  c. 

c.  c. 

c.  c. 

c.  c. 

c.  c. 

0.0 

0.0 

1.6 

3.2 

1.0 

4.8 

6.3 

7.9 

9.5 

li.i 

12.7 

14.3 

15.6 

16.9 

18.2 

2.0 

19.5 

20.8 

22.1 

23.4 

24.7 

26.0 

27.3 

28.6 

29.9 

31.2 

3.0 

32.5 

33.8 

35.1 

36.4 

37.7 

38.0 

40.3 

41.6 

42.9 

44.3 

4.0 

45.7 

47.1 

48.6 

50.0 

51.4 

52.9 

54.3 

55.7 

57.1 

58.6 

5.0 

60.0 

61.4 

62.9 

64.3 

65.7 

67.1 

68.6 

70.0 

71.4 

72.9 

6.0 

74.3 

75.7 

77.1 

92.9 

80.0 

81.4 

82.9 

84.3 

85.7 

87.1 

7.0 

88.6 

90.0 

91.4 

78.6 

94.3 

95.7 

97.1 

98.6 

100.0 

101.5 

To  translate  parts  per  million  to  degrees  of  hardness,  use  the  follow- 
ing table: 

Conversion  table  of  hardness 


Parts 

Parts  per 
MiUion 

Clark 
Degrees 

French 
Degrees 

German 
Degrees 

Parts  per  million 

Clark  degrees 

French  degrees 

1.00 
14.3 
10.0 
17.9 

0.07 
1.00 
0.70 
1.24 

0.10 
1.43 
1.00 
1.78 

0.056 

0.80 

0.56 

German  degrees 

1.00 

(Clark's    scale)    represent   grains   of   calcium 
100,000    of   calcium    car- 


English    degrees   of   hardness 
carbonate  per  imperial  gallon. 

French   degrees   of   hardness   represent   parts    per 
bonate. 

German  degrees  of  hardness  represent  parts  per  100,000  of  calcium  oxid. 

To  convert  hardness  from  one  scale  to  another,  multiply  by  the  factor  opposite 
the  scale  in  which  it  is  expressed  and  under  the  scale  to  which  it  is  to  be  con- 
verted.   Thus,  to  convert  parts  per  million  to  Clark  degrees,  multiply  by  0.07. 


ORGANIC  MATTER  1065 

The  stock  soap  solution  is  composed  of  100  grams  of  dry  white  Cas- 
tile soap  in  1  liter  of  80  per  cent,  alcohol.  The  solution  is  standardized 
against  a  standard  calcium  chlorid  solution.  To  make  the  latter  dissolve 
0.2  gram  pure  calcium  carbonate  in  dilute  hydrochloric  acid,  evaporating 
several  times  to  dryness  with  distilled  water  to  expel  free  acid.  The 
residue  is  diluted  to  1  liter.  In  standardizing,  20  c.  c.  of  the  calcium 
chlorid  solution  is  diluted  to  50  c.  c.  with  distilled  water,  and  stock 
soap  solution  added  as  described  above.  The  strength  of  the  latter  is 
then  adjusted  with  70  per  cent,  alcohol,  so  that  6.4  c.  c.  of  it  will  give 
a  permanent  lather  to  20  c.  c.  standard  calcium  chlorid  solution  under 
the  conditions  outlined.  One  liter  of  the  resulting  standard  soap 
solution  usually  requires  from  75  to  100  c.  c.  of  stock  soap  solu- 
tion. 

In  adding  the  soap  solution  to  waters  containing  magnesium  salts 
it  is  necessary  to  avoid  mistaking  the  false  or  magnesium  end-point  for 
the  true  one.  If  the  end-point  was  due  to  magnesium  the  lather  now  dis- 
appears. Soap  solution  must  then  be  added  until  the  true  end-point 
is  reached.  Usually  the  false  lather  persists  for  less  than  5  minutes. 
Consequently,  after  the  titration  is  apparently  finished,  read  the  burette 
and  add  about  0.5  c.  c.  of  soap  solution. 

At  best  the  soap  method  is  not  a  precise  test  on  account  of  the  vary- 
ing proportions  of  calcium  and  magnesium  present  in  different  waters. 
For  the  determination  of  hardness,  especially  in  connection  with  proc- 
esses for  purification  and  softening,  it  is  advisable  to  use  volumetric 
or  gravimetric  methods. 


ORGANIC  MATTER 

It  is  not  possible  to  determine  the  amount  of  organic  matter  pres- 
ent in  a  sample  of  water  by  any  direct  method.  As  all  protein  matter 
contains  nitrogen,  methods  have  been  devised  to  determine  the  total 
amount  of  nitrogen  and  also  the  amount  of  nitrogen  in  various  com- 
binations. From  such  data  valuable  information  concerning  the  sani- 
tary history  and  sanitary  quality  of  the  water  may  be  inferred.  The 
nitrogen  is  determined  as  (1)  total  nitrogen;  (2)  nitrogen  as  free  am- 
monia; (3)  nitrogen  as  albuminoid  ammonia;  (4)  nitrogen  as  nitrites; 
(5)  nitrogen  as  nitrates. 

The  organic  matter  in  water  is  of  animal  and  vegetable  origin  and 
exists  both  in  solution  and  in  suspension.  Some  of  it  is  in  the  body 
of  living  beings;  some  of  it  is  in  their  dead  bodies;  and  some  of  it 
is  in  various  stages  of  decomposition  until  the  final  stable  compounds, 
such  as  ammonia  and  nitrates,  are  reached.  The  total  amount  of  or- 
ganic matter  present  in  a  sample  of  water  is  represented  by  the  amount 


1066  SANITAEY  ANALYSIS  OF  WATER 

of  nitrogen  as  free  ammonia  and  albuminoid  ammonia.  The  presence 
of  nitrogen  as  nitrites  and  nitrates  indicates  the  amount  of  self-purifica- 
tion which  the  water  has  undergone.  Their  significance  will  be  dis- 
cussed separately. 

Free  Ammonia.' — If  there  is  much  "free"  ammonia  in  the  water  the 
sample  may  be  Nesslerized  directly.  If  the  water  contains  comparatively 
little,  as  is  usually  the  case;  the  ammonia  must  first  be  concentrated 
by  distillation  and  condensation. 

Place  500  c.  c.  of  the  sample  of  water  in  a  metal  or  glass  still  con- 
nected to  a  tin  or  aluminium  condenser  in  such  a  way  that  the  dis- 
tillate may  be  conveniently  delivered  directly  into  Nessler  tubes.  The 
entire  apparatus  must  first  be  freed  from  ammonia  by  blowing  steam 
through  it  until  the  distillate  shows  no  trace  of  free  ammonia.  When 
this  has  been  done  the  distilling  flask  is  emptied  and  500  g.  c.  of  the 
sample  water  measured  into  it.  The  distillation  should  be  carried 
on  at  a  rate  so  that  not  more  than  10  c,  c.  nor  less  than  6  c.  e.  condense 
per  minute;  that  is,  it  should  take  from  5  to  10  minutes  to  distill  50 
c.  c,  which  is  the  quantity  ISTessler  tubes  are  ordinarily  graduated  to 
contain.  Four  ISTessler  tubes  of  the  distillate  containing  50  c.  c.  each 
are  collected  from  the  first  portion  that  comes  over;  these  contain  the 
free  ammonia. 

If  the  sample  is  acid,  or  if  the  presence  of  urea  is  suspected,  about 
one-half  gram  of  sodium  carbonate  should  be  added  previous  to  dis- 
tillation, otherwise  the  ammonia  will  not  come  off.  Sodium  carbonate 
is  omitted,  when  possible,  as  it  tends  to  increase  "bumping.'^ 

The  amount  of  ammonia  is  determined  by  adding  2  c.  c.  of  Nessler 
reagent  to  each  tube  and  comparing  the  depth  of  color  with  a  set  of 
standard  tubes  prepared  with  a  known  quantity  of  ammonium  chlorid 
solution,  plus  an  equal  quantity  of  Nessler  reagent. 

Nessler  s  reagent  is  prepared  by  dissolving  50  grams  of  potassium 
iodid  in  a  minimum  quantity  of  cold  water.  To  this  add  a  saturated 
solution  of  mercuric  chlorid  until  a  slight  permanent  precipitate  per- 
sists. Then  add  400  c.  c.  of  50  per  cent,  potassium  hydroxid  solution 
which  has  been  allowed  to  clarify  by  sedimentation  before  using;  dilute 
to  one  liter,  allow  to  stand,  and  decant.^  The  solution  should  give 
the  required  color  with  ammonia  within  5  minutes  after  addition, 
and  should  not  precipitate  with  small  amounts  of  ammonia  within 
2  hours.  The  reaction  between  Nessler's  reagent  and  ammonia  is  an 
empiric  one.  The  Hgl22KIKOII,  which  constitutes  the  Nessler's 
reagent  in  the  presence  of  ammonia,  forms  a  brownish  compound 
which  is  known  as  mercurammonium  iodid,  and  has  the  formula 
NHg.IH^O. 

*  Another  method  of  making  Nessler's  reagent  will  be  found  in  Sutton's 
"Volumetric  Analysis." 


ORGANIC  MATTER  1067 

Ammonia-free  water  may  readily  be  obtained  by  distilling  water 
containing  about  0.2  per  cent,  dilute  sulphuric  acid. 

Standard  NH^Cl  Solution. — The  standards  for  comparison  con- 
sist of  ammonium  chlorid  dissolved  in  ammonia-free  water.  Dissolve 
3.82  grams  of  ammonium  chlorid  in  1  liter  of  water;  dilute  10  c.  c. 
of  this  to  1  liter  with  the  ammonia-free  water.  One  c.  c,  will  then 
equal  0.00001  gram  of  nitrogen  as  ammonia. 

A  gram  molecule  of  NH^Cl  weighs  53.5  grams — that  is : 

N  14  +  H  4  -f  CI  35.5  =  53.5 
The  equation  would  then  be : 

14  :53.5  ::  1  :x 
x  =  3.82 

That  is,,  if  there  are  14  grams  of  nitrogen  in  53.5  grams  of  am- 
monium  chlorid,  then  1  gram  of  nitrogen  is  contained  in  3.82  grams 
of  ammonium  chlorid.  It  is  to  be  noted  that,  while  the  method  deter- 
mines the  amount  of  ammonia,  the  results  are  expressed  in  terms  of 
nitrogen.  In  the  same  way  the  nitrites  and  nitrates  are  also  expressed 
in  terms  of  nitrogen. 

Prepare  a  series  of  16  iSTessler  tubes,  which  contain  the  following 
number  of  cubic  centimeters  of  the  standard  ammonium  chlorid  solu- 
tion, namely:  0.0,  0.1,  0.3,  0.5,  0.7,  1.0,  1.4,  1.7,  2.0,  2.5,  3.0,  3.5,  4.0,  4.5, 
5.0,  and  6.0;  dilute  each  one  to  the  50  c.  c.  mark  with  ammonia-free 
water.  These  will  contain  0.00001  gram  of  nitrogen  for  each  cubic  centi- 
meter of  the  standard  solution  used.  Add  about  1  c.  c.  of  the  Nessler 
reagent  to  each  tube;  do  not  stir  the  contents  of  the  tubes. 

The  color  produced  in  the  distillate  from  the  sample  under  exam- 
ination is  now  compared  with  standards  by  looking  vertically  down- 
ward through  them  at  a  white  surface  placed  at  an  angle  in  front  of 
a  window  so  as  to  reflect  the  light  upward.  The  tubes  should  be  allowed 
to  stand  at  least  10  minutes  after  Xesslerizing  before  making  the  com- 
parison. 

The  last  50  cubic  centimeters  of  the  distillate  examined  should  con- 
tain no  ammonia,  or  at  most  a  trace,  otherwise  it  may  be  inferred  that 
all  has  not  been  collected,  or  some  error  has  crept  into  the  work.  "  It  is 
not  uncommon  for  the  last  tube  to  contain  a  little  ammonia  when  the 
organic  matter  is  of  plant  origin.  Ammonia  determinations  should 
be  carried  out  in  a  special  room,  where  at  least  volatile  ammonia  re- 
agents are  not  exposed.  Special  care  must  be  exercised  not  to  contam- 
inate the  Xessler  tubes  with  soiled  fingers,  rags,  etc.  Care  must  be  exer- 
cised thoroughly  to  wash  the  tubes  free  from  alkaline  soaps,  and  to  rinse 
with  ammonia-free  water.     The  ISTessler  tubes  containing  the  standard 


1068  SANITAEY  ANALYSIS  OF  WATER 

solution  and  the  samples  for  comparison  should  be  at  the  same  tem- 
perature, and  other  conditions  should  be  as  nearly  alike  as  possible. 

Example. — 

The  first  Nessler  tube^2.5  c.  c.  standard  XH^Cl  solution,  or 
0.000,025  gram  ,N  as  NH3. 

The  second  Nessler  tube:=0.7  c.  c.  standard  NH^Cl  solution,  or 
0.000,007  gram  N  as  NH3. 

The  third  Xessler  tube=0.0  c.  c.  standard  XH^Cl  solution,  or 
0.000,000  gram  N  as  NH3. 

Total,  0.000,032  gram  N  as  NH3. 

(Note :  1  c.  c.  of  the  standard  solution  contains  0.00001  gram  of 
N  as  NH3.) 

Only  500  c.  c.  of  the  sample  of  water  was  distilled.  We  must,  there- 
fore, multiply  by  2  in  order  to  obtain  the  amount  of  N  in  one  liter : 

0.000,032X2=0.000,064  gram  .of  X  as  NH3  per  1,000  c.  c. 

If  1,000  c.  c.  contains  0.000,064  gram  of  N  as  X^Hg,  1,000,000  parts 
will  contain  0.064  part  of  X  as  XH, — usually  expressed  as  0.064  part 
per  million. 

A  simpler  method  of  making  the  calculation  is  as  follows . 

First  Xessler  tube 2.5 

Second  Xessler  tube 0.7 

Third  X^essler  tube 0.0 

3.2X0.02=0.064  part  per  million. 

Significance  of  Free  Ammonio: — The  free  ammonia  which-  comes 
off  with  the  first  part  of  the  distillate  usually  exists  in  the  water  as 
chlorids  or  carbonates.  It  is  called  "free  ammonia"  because  these  salts 
are  readily  decomposed  and  the  ammonia  is  expelled  by  boiling. 

Eain  water  washes  down  some  free  ammonia  which  is  found  in  the 
atmosphere.  Angus  Smith  and  Boussingault  place  the  average  amount 
of  ammonia  in  the  rain  of  temperate  climates  as  0.5  part  per  million. 

The  amount  of  ammonia  in  rain  water  was  studied  by  Filhol.  He 
found  that  in  the  city  of  Toulouse  the  rain  water  contained  6.60  parts 
per  million,  while  the  rain  water  collected  near  the  city  contained  only 
from  0.44  to  0.77  part  per  million.  These  figures  show  the  marked  dif- 
ference between  city  and  country  rain. 

In  a  surface  or  ground  water  free  ammonia  represents  one  of  the 
latter  stages  of  putrefaction  of  organic  matter;  thus,  the  bacterial  de- 
composition of  sewage  yields  ammonia  in  abundance. 

The  ammonia  itself  ordinarily  found  in  drinking  water  is  harmless; 
its  significance  lies  in  the  fact  that  it  indicates  the  presence  of  putre- 
fying organic  matter. 


ORGANIC  MATTER  1069 

The  presence  of  free  animonia  in  ch'nu  and  properly  stored  rain 
water  has  much  less  significance  tlian  in  a  surface  or  ground  water. 

Yrce  ammonia  in  water  results  not  only  from  the  decomposition  of 
nitrogenous  organic  matter,  hut  is  also  formed  during  the  process  of 
denitrification,  by  which  nitrates  are  again  reduced  to  nitrites  and 
nitrites  to  ammonia.  This  action  only  takes  place  near  the  surface 
of  the  soil,  and  to  a  limited  extent.  Deep  well  waters  of  exceptional 
purity  upon  chemical  analysis  and  practically  sterile  upon  bacteriologi- 
cal examination,  may  contain  a  relatively  high  percentage  of  free  am- 
monia. This  is  supposed  to  come  from  a  chemical  reduction  under 
high  pressure  and  perhaps  temperature  of  the  geological  nitrogenous 
matter  in  coal  and  alluvial  deposits. 

A  definite  permissible  limit  for  the  amount  of  free  ammonia  which 
good  water  should  contain  cannot  be  fixed.  Its  significance  must  be 
judged  from  the  other  constituents  of  the  water  and  a  sanitary  survey 
of  its  source.  As  a  rule,  safe  water  may  contain  from  0.015  to  0.03 
or  even  0.055  part  per  million.  In  general,  free  ammonia  is  less  of  a 
danger  si.irnal  than  the  fixed  or  albuminoid  ammonia. 

Albuminoid  Ammonia. — Xitrogen  as  albuminoid  ammonia  is  always 
determined  in  conjunction  with  and  as  a  continuation  of  the  method 
for  determining  nitrogen  as  free  ammonia.  After  obtaining  200  c.  c. 
(that  is,  4  Xessler  tubes  of  50  c.  c.  each)  from  the  first  portion  of  the 
distillate,  for  the  purpose  of  determining  nitrogen  as  free  ammonia, 
withdraw  the  flame,  disconnect  the  flask  and  add  40  c.  c.  or  more  of  hot 
alkaline  potassium  permanganate,  and  continue  the  distillation  until 
at  least  4  portions  of  50  c.  c.  each,  or,  preferably,  5  portions,  of  the 
distillate  have  been  collected  in  separate  Xessler  tubes. 

The  calculation  is  as  follows : 

First  Xessler  tube 1.7 

Second  Xessler  tube 0.8 

Third  Xessler  tube 0.5 

Fourth  Xessler  tube 0.3 

Fifth  Xessler  tube 0.3 


3.6X0.02=0.072  part  per  million. 

The  alkaline  potassium  permanganate  solution  is  made  by  pouring 
1,200  c.  c.  of  distilled  water  into  a  porcelain  dish  holding  2,500  c.  c; 
boil  10  minutes  and  turn  off  the  gas.  Add  16  grams  of  C.  P.  potas- 
sium permanganate  and  stir  until  dissolved.  Then  add  800  c.  c.  of  50 
per  cent,  clarified  solution  of  potassium  or  sodium  hydrate  and  enough 
distilled  water  to  fill  the  dish.  Boil  down  to  2,000  c.  c.  Test  each  batch 
of  this  solution  for  albuminoid  ammonia  by  making  a  blank  determi- 
nation.    Correction  should  be  made  accordingly. 


1070  SANITARY  ANALYSIS  OF  WATER 

After  the  readily  decomposed  ammonia  salts  have  been  broken 
up  and  the  ammonia  driven  off  in  the  steam  which  condenses  to  form 
the  first  200  c.  c,  the  remainder  of  the  sample  of  water  in  the  still  eon- 
tains  nitrogenous  organic  matter  that  requires  a  strong  oxidizing  agent 
to  disintegrate  it.  This  is  accomplished  by  the  alkaline  potassium  per- 
manganate. The  nitrogen  in  the  complex  protein  molecule  finally  forms 
ammonia,  and  hence  this  is  called  albuminoid  ammonia;  the  amount 
of  it  is  determined  by  Nesslerization,  precisely  as  for  free  ammonia. 
In  ground  waters  and  surface  waters  containing  but  little  pollution  the 
nitrogen  as  albuminoid  ammonia  usually  approximates  about  one-half 
of  the  total  organic  nitrogen.  In  sewage  and  other  liquids  containing 
considerable  nitrogenous  organic  matter  the  percentage  of  ammonia 
forming  organic  matter  is  variable.  For  this  reason  the  amount  of 
albuminoid  ammonia  obtained  by  the  alkaline  permanganate  method 
is  less  valuable  than  the  total  organic  nitrogen  determined  by  the  Kjel- 
dahl  method. 

If  it  is  desired  to  determine  how  much  of  the  organic  matter  is  in 
solution  and  how  much  in  suspension,  the  sample  of  water  should  be 
passed  through  a  Berkefeld  filter.  The  albuminoid  ammonia  in  the 
filtrate  represents  the  dissolved  organic  matter,  and  the  difference  be- 
tween the  albuminoid  ammonia  in  the  total  sample  and  the  filtered 
sample  gives  the  suspended  nitrogen  as  albuminoid  ammonia. 

The  albuminoid  ammonia  is  a  fairly  correct  index  of  the  amount 
of  organic  pollution  in  the  water.  It  comes  from  minute  organisms, 
both  living  and  dead,  that  are  in  the  sample,  also  from  particles  of 
animal  and  vegetable  matter  in  suspension,  and  finally  from  the  nitrog- 
enous substances  in  solution  and  in  various  stages  of  decomposition. 
The  organic  matter  in  itself  is  not  dangerous  to  health,  but  is  unde- 
sirable because  it  putrefies  and  thus  gives  a  water  disagreeable  tastes 
and  odors;  further,  it  offers  food  for  bacterial  growth.  The  amount 
of  albuminoid  ammonia  is  therefore  an  index  of  pollution,  but  if  of 
vegetable  origin  it  has  much  less  sanitary  significance  than  if  of  animal 
origin.  Organic  matter  of  animal  origin  yields  a  much  larger  amount 
of  albuminoid  ammonia  than  a  similar  amount  of  vegetable  matter. 
Whether  the  organic  matter  comes  from  sewage,  from  a  dead  carcass, 
of  from  the  swamps,  cannot  be  stated  with  certainty  from  this  test,  but 
if  the  albuminoid  ammonia  comes  over  quickly,  that  is,  if  most  of  it 
appears  in  the  first  Nessler  tube,  it  is  presumably  of  animal  origin; 
whereas,  if  the  ammonia  comes  over  more  slowly  and  the  second  and 
third  Nessler  tubes  contain  appreciable  amounts,  the  organic  matter  is 
presumably  of  vegetable  origin. 

No  arbitrary  standard  can  be  set  as  to  the  maximum  amount  of 
albuminoid  ammonia  a  good  water  may  contain.     Waters  considered 


OEGANIC  MATTER  1071 

''pure"  often  contain  as  nuicli  as  0.079  to  0.34  part  of  nitrogen  as  al- 
buminoid ammonia  per  million. 

Nitrites. — Nitrites  in  Avator  are  regarded  as  a  special  danger  signal. 
The  reason  for  this  is  that  nitrites  indicate  that  active  putrefaction  of 
nitrogenous  organic  matter  is  going  on  as  the  result  of  bacterial  activ- 
ity. The  presence  of  nitrites,  therefore,  at  once  suggests  organic  pollu- 
tion. The  presence  of  nitrites  in  water  represents  the  transitional  stage 
in  the  oxidation  of  organic  matter  between  ammonia  and  nitrates,  and 
therefore  indicates  incomplete  oxidation  of  the  protein  and  the  active 
growth  of  bacteria. 

Nitrites  are  never  present  except  in  small  amounts,  for  they  are  soon 
oxidized  to  the  higher  and  more  stable  nitrates,  but  a  minute  amount, 
according  to  some  authorities,  is  sufficient  to  condemn  a  water.  As  a 
rule,  pure  water  contains  no  nitrites,  or  traces  only;  on  the  other  hand, 
nitrites  may  be  absent  from  an  impure  water,  owing  to  the  fact  that 
the  oxidation  has  not  reached  this  stage,  or  perhaps  has  entirely  passed 
it.  The  absence  of  nitrites,  therefore,  does  not  mean  that  the  water  is 
necessarily  safe,  while  their  presence  in  any  but  the  smallest  measurable 
amounts  shows  pollution.  "We  must  not  give  to  the  nitrites  an  exag- 
gerated importance :  they  are  a  danger  signal  in  the  same  sense  that 
the  colon  bacillus  is  a  danger  signal,  indicating  pollution  but  not  neces- 
sarily infection,  for  they  do  not  tell  the  source  or  nature  of  the  organic 
matter.  The  presence  of  nitrites  in  spring  and  deep  well  water  may 
be  without  sanitary  signilicance,  for  in  these  cases  they  may  be  gen- 
erated by  the  deoxidation  of  the  nitrates  which  is  brought  about  either 
by  the  action  of  reducing  substances,  such  as  ferrous  oxid,  or  by  organic 
matter.  It  should  be  remembered  that  the  colorimetric  test  for  nitrites 
with  sulphanilic  acid  and  a-amidonaphthylamin  is  one  of  the  most  deli- 
cate tests  in  chemistry.  With  this  method  we  are  able  to  detect  quan- 
tities as  small  as  one  part  in  a  hundred  million.  When,  therefore,  a 
water  analyst  reports  a  trace  of  nitrites  it  means  an  exceedingly  minute 
quantity. 

Nitrites  are  not  only  formed  by  the  nitrifying  bacteria  in  the  soil 
from  ammonia,  but  are  also  formed  from  the  denitrification  of  nitrates 
by  a  variety  of  microorganisms.  The  typhoid  bacillus,  the  colon  bacillus, 
and  many  other  bacteria  have  the  power  of  producing  nitrites  in  culture 
media. 

Nitrites  are  poisonous,  but  the  minute  amounts  found  in  water  can 
scarcely  have  a  pharmacological  effect. 

Method  for  Estimating  Nitrogen  as  Nitrites — Eeagents:  (1)  Sul- 
phanilic acid  solution.  Dissolve  eight  grams  of  the  purest  sulphanilic 
acid  in  1,000  c.  c.  of  5  N.  acetic  acid  (sp.  gr.  1.041).  This  is  prac- 
tically a  saturated  solution. 

(2)  Naphthylamin  acetate  or  chlorid  solution.     Dissolve  5.0  grams 


1073  SANITAEY  ANALYSIS  OF  WATER 

solid  a-naphthylamin  in  1,000  c.  c.  of  5  N.  acetic  acid ;  filter  the  solution 
through  washed  absorbent  cotton,  or  an  alundum  filter. 

(3)  Sodium  nitrite,  stock  solution.  Dissolve  1.1  grams  silver  ni- 
trite in  nitrite-free  water;  precipitate  the  silver  with  sodium  chlorid 
solution  and  dilute  the  whole  to  one  liter. 

(4)  Standard  sodium  nitrite  solution.  Dilute  100  c.  c.  of  solution 
(3)  to  one  liter;  then  dilute  5  c.  c.  of  this  solution  to  one  liter  with 
sterilized  nitrite-free  water;  add  one  c.  c.  of  chloroform  and  preserve 
in  a  sterilized  bottle.     One  c.  c.  =  0.0005  mg.  nitrogen. 

Procedure. — Measure  out  50  c.  c.  of  the  decolorized  sample  (de- 
colorized by  adding  aluminium  hydrate  free  of  nitrite — see  under  Chlo- 
rin),  or  a  smaller  portion  diluted  to  50  c.  c,  into  a  Nessler  tube. 
At  the  same  time  make  a  set  of  standards  by  diluting  various  volumes 
of  the  standard  nitrite  solution  in  Nessler  tubes  to  50  c.  c.  with  nitrite- 
free  water,  for  example,  0.0,  0.1,  0.2,  0.4,  0.7,  1.0,  1.4,  1.7,'  2.0,  and 
2.5  c.  c.  Add  1  c.  c.  each  of  reagents  ISTos.  1  and  2  (above)  to  each  100 
c.  c.  of  the  sample  and  to  each  standard.  Mix;  allow  to  stand  10  min- 
utes. Compare  the  samples  with  the  standards.  Do  not  allow  the  sam- 
ples to  stand  over  one-half  hour  before  being  compared,  on  account  of  ab- 
sorption of  nitrites  from  the  air.  Make  a  blank  determination  in  all 
cases  to  correct  for  tlie  presence  of  nitrites  in  the  air,  the  water  and  other 
reagents.  Dilute  all  samples  which  develop  more  color  than  the  2.5 
c.  c.  standard  before  comparing.    Mixing  is  important. 

When  50  c.  c.  of  the  sample  are  used,  then  0.01  times  the  number 
of  c.  c.  of  the  standard  gives  the  parts  per  million  of  nitrogen  as  nitrite. 

Calculation. — One  c.  c.  of  the  standard  equals  0.0005  mg.  ^N".  as 
nitrites.  50  c.  c.  of  the  sample  is  used  and  is  found  to  equal  0.5  c.  c.  of 
the  standard. 

Then  50  c.  c.  sample  contains  0.00025  mg.  IsT.  as  nitrites  and  one 
liter  will  contain  20  X  0.00025  or  0.005  mg.  of  N.  or  0.005  part  per 
million. 

When  50  c.  c.  of  the  sample  is  used  20  X  0.0005  X  the  number 
c.  c.  of  the  standard  will  give  the  number  mg.  N.  per  liter  or  parts 
per  million.  This  can  be  shortened  to  0.01  X  the  number  c.  c.  standard 
used  equal  parts  per  million  of  N.  as  nitrites. 

Nitrates. — Nitrates  are  the  end  products  of  the  mineralization  of 
organic  matter.  Their  presence,  therefore,  signifies  past  or  distant 
pollution.  While  the  absence  of  nitrates  does  not  necessarily  mean 
purity,  their  presence,  on  the  other  hand,  does  not  necessarily  indicate 
immediate  danger.  If  a  water  contains  an  appreciable  quantity  of  ni- 
trates and  no  nitrites,  it  shows  that  the  source  of  pollution  has  been 
distant  and  that  the  organic  matter  has  been  completely  oxidized.  In 
waters  considered  pure  the  nitrates  are  rarely  less  than  0.3  part,  or 
they  may  run  as  high  as  1.6  parts,  per  million,    Polluted  waters  usually 


ORGANIC  MATTER  1073 

contain  very  much  more,  as  17  to  20,  or  more  parts  per  million.  Nitrates 
usually  exist  in  water  as  salts  of  alkaline  bases. 

Young  ^  has  shown  that  the  ground  waters  of  Kansas  sometimes 
contain  large  amounts  of  nitrates — as  mueh  as  500  ])arts  per  million. 
The  medit'inal  dose  of  potassium  nitrate  is  0.3  gram.  Less  than  a 
liter  of  water  would  therefore  contain  sufficient  nitrates  to  produce 
therapeutic  effects  such  as  irritation  of  the  mucous  membrane  of  the 
stomach,  resulting  in  gastritis,  and  also  diuresis,  with  irritation  of  the 
mucous  membrane  of  the  bladder. 

The  test  for  nitrates  depends  upon  the  fact  that  they  react  with 
phenoldisulphonic  acid  to  form  a  compound  resembling  picric  acid,  which 
is  yellow  in  the  presence  of  an  alkali.  The  amount  of  nitrates  is  deter- 
mined colorimetrically  by  comparison  with  standard  solutions. 

Phenoldisulphonic  Acid  Method. — Rraf/enfs:  (1)  PlienoWii^ul phonic 
acid.  Dissolve  25  grams  of  pure  white  phenol  in  150  c.  c.  of  pure  con- 
centrated sulphuric  acid.  Add  75  c.  c.  of  fuming  sulphuric  acid  (15 
per  cent.  SO3),  stir  well,  and  heat  for  2  hours  at  about  100°  C. 

(2)  rofassium  hydroxid  solution.  Prepare  an  approximately  12 
N.  solution,  10  c.  c.  of  which  will  neutralize  about  4  c.  c.  of  the  phenol- 
disulphonic acid. 

(3)  Standard  mtrate  solution.  Dissolve  0.72  gram  of  pure  re- 
crystallized  potassium  nitrate  in  1  liter  of  distilled  water.  Evaporate 
cautiously  to  dryness  10  c.  c.  of  the^solution  on  the  water  bath.  Moisten 
residue  quickly  and  thoroughly  with  2  c.  c.  of  phenoldisulphonic  acid  and 
dilute  to  1  liter.  This  is  the  standard  solution,  1  c.  c.  of  which  equals 
0.001  mg.  of  nitrate  nitrogen, 

(4)  Standard  sitver  sulphate  solution.  Dissolve  4.4  grams  of 
silver  sulphate  free  from  nitrate  in  1  liter  of  water.  One  c.  c.  of  this 
solution  is  equal  to  1  mg.  of  chlorid. 

Procedure. — The  alkalinity,  chlorid  and  nitrite  content,  and  color 
of  the  sample  must  first  be  determined.  If  the  sample  is  highly  colored 
decolorize  it  with  freshly  precipitated  aluminium  hydroxid.  Measure 
into  an  evaporating  dish  100  c.  c.  of  the  sample,  or  if  nitrate  is  very 
high  such  volume  as  will  contain  about  0.01  mg.  of  nitrate  nitrogen. 
Add  sufficient  -^  sulphuric  acid  nearly  to  neutralize  the  alkalinity. 
Then  add  sufficient  standard  silver  sulphate  to  precipitate  all  but  about 
0.1  mg.  of  chlorid.  The  removal  of  chlorid  may  be  omitted  if  the  sample 
contains  less  than  30  parts  per  million  of  chlorid.  Heat  the  mixture  to 
boiling,  add  a  little  aluminium  hydroxid,  stir,  filter,  and  wash  with 
small  amounts  of  hot  water.  Evaporate  the  filtrate  to  dryness,  and  add 
2  c.  e.  of  the  phenoldisulphonic  acid,  rubbing  with  a  glass  rod  to  insure 
intimate  contact.  If  the  residue  becomes  packed  or  appears  vitreous  be- 
cause of  the  presence  of  much  iron,  heat  the  dish  on  the  water  bath  for 

» Young,  C.  C:     Jowr.  A.  M.  A.,  June  24,  1911,  LVI,  p.  1881, 


1074  SANITAEY  ANALYSIS  OF  WATER 

a  few  minutes.  Dilute  the  mixture  with  distilled  water,  and  add  slowly 
a  strong  solution  of  potassium  hydroxid  or  ammonium  hydroxid  until 
the  maximum  color  is  developed.  Transfer  the  solution  to  a  ISTessler 
tube,  filtering  if  necessary.  If  nitrate  is  present  a  yellow  color  will 
be  formed.  Compare  the  color  with  that  of  standards  made  by  adding 
2  c.  c.  of  strong  potassium  hydroxid  or  ammonium  hydroxid  to  various 
amounts  of  standard  nitrate  solution  and  diluting  them  to  50  c.  c.  in 
Nessler  tubes.  The  following  amounts  of  standard  nitrate  solution  are 
suggested :  0,  0.5,  1.0,  1.5,  2.0,  4.0,  6.0,  8.0,  10.0,  15.0,  20.0,  and  40.0 
c.  c.  These  standards  may  be  kept  several  weeks  without  deterioration. 
If  100  c.  c.  of  water  is  used  the  number  of  cubic  centimeters  of  the  stand- 
ard multiplied  by  0.01  is  equal  to  parts  per  million  of  nitrate  ni- 
trogen. 

Standards  that  will  remain  permanent  for  several  years  if  stored  in 
the  dark  may  be  prepared  from  tripotassium  nitrophenoldisulphonate. 

If  nitrate  nitrogen  is  present  in  .excess  of  1  part  per  million  it 
should  be  oxidized  by  heating  the  samples  a  few  minutes  with  a  few 
drops  of  hydrogen  peroxid,  free  from  nitrate,  repeatedly  added,  or  by 
adding  dilute  potassium  permanganate  in  the  cold  until  a  faint  pink 
coloration  appears;  the  nitrogen  equivalent  of  the  nitrite  thus  oxidized 
to  nitrate  is  then  subtracted  from  the  final  nitrate  nitrogen  reading. 


CHLORIDS 

Chlorin  as  sodium  chlorid  or  common  salt  is  a  normal  constituent 
of  all  waters.  Traces  of  it  taken  up  from  the  air  are  found  in  rain 
water,  especially  near  the  seacoast.  The  rain  water  collected  at  Troy, 
T^ew  York,  was  found  by  Mason  to  average  1.64  parts  per  million  of 
chlorin.  The  amounts  varied  from  0.75  part  per  million  in  April  to  3 
parts  per  million  in  October.  The  chlorid  in  surface  and  ground  waters, 
generally  speaking,  comes  from  the  mineral  deposits  in  the  earth;  from 
the  ocean  vapors  and  spray  carried  inland  by  the  wind;  also  from  pol- 
luting materials  like  sewage  and  trade  wastes,  both  of  which  are  apt  to 
contain  the  common  salt  used  in  the  household  and  in  manufacturing. 
A  comparison  of  the  chlorin  content  of  a  water  with  that  of  other  waters 
in  the  general  vicinity  known  to  be  unpolluted  frequently  affords  useful 
information  as  to  its  sanitary  quality. 

Before  the  water  analyst  is  able  properly  to  interpret  the  significance 
of  the  chlorin  content  of  a  water  it  is  necessary  to  know  the  normal 
amount  of  chlorin  present  in  the  waters  of  that  locality.  Thus,  surface 
waters  near  Provincetown,  on  Cape  Cod,  contain  from  23  to  24  parts 
of  chlorin  per  million,  while  surface  waters  near  Boston  contain  from 
3  to  6  parts  per  million.    IsTear  the  middle  of  the  state  of  Massachusetts 


CHLORIDS  1075 

(Worcester)  the  surface  waters  contain  only  1.2  to  1.9  parts  per  million, 
while  in  the  western  portion  of  the  state,  farthest  from  the  sea,  the 
surface  waters  contain  but  0.7  to  0.9  part  per  million.  The  amcmnt 
of  normal  chlorid  in  the  waters  of  Massachusetts  has  been  carefully 
studied  by  the  State  Board  of  Health,  and  a  map  has  been  issued  show- 
ing the  isochlors,  or  normal  chlorin  lines. 

In  Massachusetts  the  whole  of  the  surface  of  the  country,  with  the 
exception  of  a  very  small  portion,  is  non-calcareous,  and  the  surface 
waters  carry  but  little  chlorin  in  composition,  if  unpolluted,  the  amount 
of  chlorin  decreasing  continuously  from  the  coast  inland.  In  a  report 
on  the  State  water  supplies,  1887-1890,  the  Commissioners  state  that 
"in  a  general  way  4  families  or  20  persons  per  square  mile  will  add,  on 
an  average,  0.01  of  a  part  per  100,000  of  chlorid  (0.1  part  per  million) 
to  the  water  flowing  from  this  area,  and  that  a  much  smaller  population 
will  have  the  same  effect  during  seasons  of  low  flow." 

The  amount  of  chlorid  in  a  water  of  a  district  varies  with  several 
factors,  such  as  the  distance  from  the  sea,  the  amount  of  rainfall,  the 
amount  of  evaporation,  and  the  direction  of  the  winds.  An  increase  over 
the  normal  is  an  indication  of  pollution,  and  comes  mostly  from  urine. 
While  the  ammonia  and  the  nitrites  may  have  disappeared  and  the  ni- 
trates may  have  been  largely  taken  up  by  growing  vegetation,  the  chlorid 
salts,  which  are  exceedingly  stable,  will  be  left  to  indicate  remote  or 
passed  pollution. 

The  mixture  of  even  a  small  proportion  of  sea-water  renders  the 
water  hard  and  salty  and  undesirable  for  domestic  use.  Magnesium 
chlorid  also  renders  a  water  unsuitable  for  use  in  boilers.  Wells  driven 
near  the  sea  frequently  become  mixed  with  sea-water,  particularly  if 
sufficient  water  is  withdrawn  to  cause  suction.  When  this  happens  the 
sea-water  passes  back  under  the  wells  as  an  undercurrent  and  gradually 
mixes  with  the  fresh  water  above  it  and  sooner  or  later  appears  in  the 
well.  When  this  happens  it  may  be  a  slow  and  hard  process  to  operate 
the  well  so  as  to  avoid  drawing  sea-water.  In  wells  near  the  sea  it  is 
important  to  draw  no  more  fresh  water  than  would  otherwise  flow  to 
the  ocean.  This  is  often  a  difficult  problem  to  arrange  so  as  to  get  the 
maximum  quantity  of  water  obtainable.  This  sea-water  question  has 
been  more  thoroughly  and  scientifically  studied  in  Holland  than  else- 
where. 

Determination  of  Chlorid-Reagents :  (1)  Standard  salt  solution. 
Dissolve  16.48  grams  of  fused  sodium  chlorid  in  one  liter  of  distilled 
water.  Dilute  100  c.  c.  of  this  stock  solution  to  one  liter  in  order  to 
obtain  a  standard  solution,  each  c.  c.  of  which  contains  0.001  gram  of 
chlorid. 

(2)  Silver  nitrate  solution.  Dissolve  about  2. -10  grams  of  silver 
nitrate  crystals  in  one  liter  of  distilled  water.     One  c.  c.  of  this  will 


10^6  SAmTARY  Al^ALYSIS  OF  WATER 

approximately  equal  0.0005  gram  of  chlorid.     Standardize  this  against 
the  standard  salt  solution, 

(3)  Potassium  cliromate.  Dissolve  50  grams  of  neutral  potassium 
chromate  in  a  little  distilled  water.  Add  enough  silver  nitrate  to  pro- 
duce a  slight  red  precipitate.  Filter  and  make  up  the  filtrate  to  one 
liter  with  distilled  water. 

(4)  Aluminium  liijdroxid.  This  is  used  only  to  clarify  the  water 
in  case  of  high  color.  Dissolve  125  grams  of  potash  or  ammonium 
alum  in  one  liter  of  distilled  water.  Precipitate  the  aluminium  hydrate 
by  cautiously  adding  ammonium  hydroxid.  Wash  the  precipitate  in  a 
large  jar  by  the  successive  addition  of  distilled  water  and  by  decan- 
tation  until  free  from  chlorid,  nitrite,  and  ammonia. 

Procedure. — For  this  determination  where  the  chlorid  content  is  not 
extremely  low  or  very  high,  titrate  50  c.  c.  of  the  sample  in  ,a  white  six- 
inch  porcelain  evaporating  dish  with  the  standard  silver  nitrate  solution. 
If  the  chlorid  is  very  high  in  amount,  use  25  c.  c,  or  even  a  smaller 
quantity  if  desired,  diluting  the  volume  taken  with  distilled  water  to 
50  c.  c.  When  the  sample  is  very  low  in  its  chlorid  content,  more  ac- 
curate results  may  be  obtained  by  using  50  c.  c.  of  the  sample  and  add- 
ing, prior  to  titration,  1  c.  c.  of  standard  salt  solution. 

Measure  out  50  c.  c.  of  the  sample  into  the  evaporating  dish.  Into 
another,  measure  50  c.  c.  of  distilled  water.  Add  to  each,  1  c.  c.  of  the 
potassium  chromate  indicator.  To  the  sample  add  carefully  from  the 
buret,  standard  AgXOg  until  the  red  of  the  silver  chromate  persists, 
using  the  distilled  water  for  comparison  of  colors.  Record  number  of 
c.  c.  of  the  standard  AgNOg  solution  used. 

Calculation. — One  c.  c.  of  the  silver  nitrate  solution  equals  0.0005  gm. 
of  chlorid. 

Assuming  that  50  c.  c.  of  the  sample  requires  5  c.  c.  of  the  stand- 
ard, then  50  c.  c.  of  the  sample  contains  0.0005  X  5.  =  0.0025  gm.  of  CI. 
or  2.5  mg.  of  CI. 

1,000  c.  c.  then  would  contain  2.5  X  20  or  50  mg.  CI.;  or  50  parts 
per  million. 

In  short,  when  the  standard  silver  solution  equals  just  0.0005  gm. 
CI.,  the  number  of  e.  c.  used  in  titrating  multiplied  by  10  will  give  the 
parts  per  million. 

CHLORIN 

In  waters  that  have  been  treated  with  calcium  hypochlorite  or  liquid 
chlorin,  it  is  frequently  advisable  to  ascertain  the  presence  or  absence 
of  chlorin.  As  the  reagents  which  have  been  proposed  for  its  detec- 
tion are  not  specific  for  chlorin  but  give  similar  or  identical  reactions 
with  oxidizing  agents  or  reducible  substances  care  must  be  exercised  in 


OXYGEN 


1077 


interpreting  the  results  of  such  tests :  nitrites  and  ferric  salts  are  of  com- 
mon occurrence,  and  chlorates  also  may  lead  to  misinterpretation  in 
waters  treated  with  calcium  hypochlorite. 

Reagents:  (1)  Tolidin  solution.  One  gram  of  o-loliilin,  purified 
by  being  recrystallized  from  alcohol,  is  dissolved  in  1  liter  of  10  per 
cent,  hydrochloric  acid. 

(2)  Copper  sulphate  solution.  Dissolve  1.5  grams  of  copper 
sulphate  and  1  c.  c.  of  conceiitratcd  sulphuric  acid  in  distilled  water  and 
dilute  the  solution  to  100  c.  c. 

(3)  Potassium  bichromate  solution.  Dissolve  0.025  gram  of  potaij- 
sium  bichromate  and  0.1  c.  c.  of  concentrated  sulphuric  acid  in  distilled 
water  and  dilute  the  solution  to  100  c.  c. 

Procedure. — Mix  1  c.  c.  of  the  tolidin  reagent  with  100  c.  c.  of  the 
sample  in  a  Nessler  tube  and  allow  the  solution  to  stand  at  least  5  min- 
utes. Small  amounts  of  free  chlorin  give  a  yellow  and  larger  amounts 
an  orange  color. 

For  quantitative  determination  compare  the  color  with  that  of  stand- 
ards in  similar  tubes  prepared  from  the  solutions  of  copper  sulphate  and 
potassium  bichromate.  The  amounts  of  solution  for  various  standards 
are  indicated  in  the  following  table : 

PREPARATION  OF  PERMANENT   STANDARDS   FOR   CONTENT   OF   CHLORIN 


Chlorin 

Solution  of 

Solution  of 

Copper  Sulphate 

Potassium  Bichromate 

Parts  per  Million 

C.   G. 

c.  c. 

0.01 

0.0 

0.8 

.02 

.0 

2.1 

.03 

.0 

3.2 

.04 

.0 

4.3 

.05 

.4 

5.5 

.06 

.8 

6.6 

.07 

1.2 

7.5 

.08 

1.5 

8.7 

.09 

1.7 

9.0 

.10 

1.8 

10.0 

.20 

1.9 

20.0 

.30 

1.9 

30.0 

.40 

2.0 

38.0 

.50 

2.0 

45.0 

OXYGEN 


Oxygen  Consumed.— The  oxygen  consumed  means  the  oxygen  which 
the  organic  compounds  in  water  consume  when  treated  in  an  acid  solu- 
tion with  potassium  permanganate.  The  expression  is  synonymous  with 
"oxygen  required"  or  "oxygen  absorbed."  Oxygen  consumed  is,  there- 
fore, an  index  of  the  amount  of  putrescible  organic  matter  present  and 
should  carefully  be  distinguished  from  the  expression  "dissolved  oxy- 


1078  SANITAEY  ANALYSIS  OF  WATER 

gen/'  which  refers  simply  to  the  amount  of  oxygen  held  in  solution  by 
the  water. 

It  is  the  carbon  and  not  the  nitrogen  in  organic  matter  which  is 
oxidized  by  potassium  permanganate  in  an  acid  solution;  hence  this  de- 
termination is  frequently  referred  to  as  an  indication  of  the  carbonaceous 
organic  matter  present.  The  method  indicates  only  a  certain  portion 
of  the  carbon,  and  this  ratio  varies  in  different  samples  of  water.  Fur- 
ther, it  does  not  differentiate  the  carbon  present  in  unstable  organic 
matter  from  that  in  what  might  be  called  fairly  stable  organic  matter, 
such  as  is  sometimes  referred  to  as  "residual  humus."  The  presence 
of  nitrites,  ferrous  iron,  sulphids,  or  other  unoxidized  mineral  com- 
pounds causes  oxygen  to  be  taken  up  and  hence  increases  the  amount 
of  oxygen  consumed  by  this  method.  In  case  such  substances  are  pres- 
ent, a  correction  should  be  made  when  studying  carbonaceous  organic 
matter. 

Determination  of  Oxygen  Consumed — Reagents:  (1)  Dilute 
sulphuric  acid.  One  part  of  sulphuric  acid  to  three  parts  of  distilled 
water.  This  shall  be  freed  from  oxidizable  matters  by  adding  potas- 
sium permanganate  until  a  faint  pink  color  persists  after  standing 
several  hours. 

(3)  Standard  ammonium  oxalate.  Dissolve  0.888  gram  of  the  pure 
salt  in  1  liter  of  distilled  water.  One  c.  c.  is  equivalent  to  0,1  mg. 
of  oxygen.  An  equivalent  quantity  of  oxalic  acid  or  sodium  oxalate  may 
be  used. 

(3)  Standard  potassium  permanganate.  Dissolve  0.4  gram  of  the 
crystallized  salt  in  1  liter  of  distilled  water.  Add  10  c.  c.  of  the 
dilute  sulphuric  acid  and  10  c.  c.  of  this  solution  of  potassium  perman- 
ganate to  100  c.  c.  of  distilled  water,  and  digest  30  minutes.  Add  10 
e.  c.  of  the  ammonium  oxalate  solution,  and  then  add  potassium  per- 
manganate till  a  pink  coloration  appears.  This  destroys  the  oxygen- 
consuming  capacity  of  the  water  used.  Xow  add  another  10  c.  c.  of  am- 
monium oxalate  solution  and  titrate  with  potassium  permanganate.  Ad- 
just the  potassium  permanganate  solution  so  that  1  c.  c.  is  equivalent  to 
1  c.  c.  of  ammonium  oxalate  solution  or  0.1  mg.  of  available  oxygen. 
Measure  into  a  flask  100  c.  c.  of  the  water,  or  a  smaller  diluted  por- 
tion if  the  water  is  of  high  organic  content.  Add  10  c.  c.  of  sulphuric 
acid  solution  and  10  c.  c.  of  potassium  permanganate  solution,  and  al- 
low the  treated  sample  of  water  to  digest  exactly  30  minutes  at  boil- 
ing temperature  in  a  water  bath  of  boiling  water,  the  level  of  which  is 
kept  above  that  of  the  contents  of  the  flask.  Thirty  minutes  is  an 
arbitrary  time. 

Precisely  at  the  end  of  the  period  of  digestion  remove  the  flask  and 
add  10  c.  c.  of  the  ammonium  oxalate  solution.  Titrate  with  the  per- 
manganate solution  until  a  faint  but  distinct  color  is  obtained. 


OXYGEN  1079 

If  100  c.  c.  of  water  is  used,  the  number  of  c.  c.  of  potassium 
permangfanate  solution  in  excess  of  the  number  of  c.  c.  of  ammonium 
oxalate  solution  is  equal  to  parts  per  million  of  oxygen  consumed. 

Sliould  the  volume  of  permanganate  solution  be  insufficient  for  com- 
plete oxidation,  rei)oat  the  analysis,  using  a  larger  volume,  so  that  at 
least  5  c.  c.  of  the  permanganate  solution  will  be  present  in  excess  when 
the  ammonium  crvalate  solution  is  added. 

When  unoxidized  mineral  substances,  such  as  ferrous  sulphate,  sul- 
phids,  nitrites,  etc.,  are  present  in  the  sample,  corrections  should  be 
applied  as  accurately  as  possible  by  procedures  suitable  for  the  samples 
being  analyzed.  Direct  titration  of  the  acidified  sample  in  the  cold, 
using  a  three-minute  period  of  digestion,  serves  this  purpose  quite  well 
for  polluted  surface  waters  and  fairly  well  for  purified  sewage  effluents. 
Raw  sewages  containing  no  trade  wastes  seldom  need  such  a  correction, 
but  when  raw  sewages  contain  "pickling  liquors'^  it  is  important.  In 
all  samples  containing  both  unoxidized  mineral  compounds  and  gaseous 
organic  substances  the  latter  should  be  driven  off  by  heat  and  the  sample 
allowed  to  cool  before  applying  this  test  for  the  correction  factor.  "Where 
such  corrections  are  necessary  the  fact  should  be  stated,  with  the  amount 
of  correction. 

This  is  one  of  the  oldest  methods  for  determining  organic  matter 
and  has  been  in  very  wide  use  for  more  than  half  a  century.  It  was 
introduced  as  soon  as  the  fact  was  recognized  that  the  loss  on  ignition 
of  the  residue  upon  evaporation  may  indicate  certain  volatile  mineral 
matters,  as  well  as  organic  matter.  To-day  the  method  of  determination 
of  oxygen  consumed  is  ordinarily  not  included  in  a  water  analysis  for 
the  reason  that  the  results  vary  widely,  depending  on  the  procedure 
as  to  certain  details  of  the  method,  and  from  the  further  fact  that  the 
determinations  of  the  organic  matter  in  water  may  be  more  conveniently 
and  satisfactorily  e^^timated  from  the  free  and  albuminoid  ammonia. 

Dissolved  Oxygen. — Dissolved  oxygen  is  another  expression  for  the 
degree  of  aeration  or  oxygenation  of  water.  It  varies  from  zero  to  sat- 
uration or  slight  supersaturation.  The  amount  of  oxygen  in  solution  is 
fairly  constant  in  waters  of  uniform  composition  freely  exposed  to  the 
air.  Water  containing  sewage  and  other  oxidizable  matters  uses  up  the 
dissolved  oxygen.  In  badly  polluted  streams  so  much  of  the  dissolved 
oxygen  may  be  lost  in  this  way  that  fish  cannot  breathe.  They  die  from 
suffocation  rather  than  from  the  toxic  effects  of  the  sewage;  fish  must 
have  at  least  2.5  parts  of  oxygen  per  million.  Water  may  contain  prac- 
tically no  oxygen  at  depth  of  40  or  50  feet,  but  deep  soundings  show 
that  aeration  probably  exists  to  greater  depths^  for  fish  and  aerobic 
organisms  live  at  the  bottom  of  the  sea.  In  this  case  the  oxygen  may 
possibly  be  obtained  from  sources  other  than  the  dissolved  oxygen  from 
the  air. 


1080  SANITARY  ANALYSIS  OF  WATER 

Dissolved  oxygen  makes  water  sparkling  and  palatable  and  also  helps 
to  consume  the  organic  matter.  Its  absence  permits  the  growth  of  an- 
aerobic organisms  that  cause  putrefaction  and  impart  putrid  tastes  and 
odors  to  the  water.  Pasteur's  original  conception  of  fermentation  was 
decomposition  in  the  absence  of  oxygen. 

The  amount  of  oxygen  found  in  the  water  of  a  running  stream  taken 
at  different  points  may  furnish  valuable  information  as  to  the  rapidity 
with  which  the  process  of  self-purification  is  taking  place  from  a  chemi- 
cal standpoint. 

The  amount  of  oxygen  dissolved  in  a  water  may  be  measured  by 
three  methods,  viz.,  that  of  Winkler,  Thresh,  or  Levy.  The  method  of 
Winkler  is  generally  used  in  this  country  and  possesses  the  advantage  of 
requiring  only  simple  and  not  readily  breakable  apparatus.  It  is  there- 
fore recommended  as  the  standard  method. 

Sample. — To  determine  the  amount  of  dissolved  oxygen  it  is  neces- 
sary to  collect, the  sample  with  extreme  care  in  order  to  avoid  the  en- 
trainment  of  any  oxygen  from  the  atmosphere.  The  sample  bottles 
should  be  glass-stoppered,  with  a  narrow  neck,  holding  at  least  250  c.  c. 
The  exact  capacity  of  the  bottle  must  be  determined.  The  bottle  should 
be  filled  through  a  glass  or  rubber  tube  which  reaches  to  the  bottom  of 
the  bottle,  and  the  water  allowed  to  overflow  for  several  minutes,  after 
which  the  glass  stopper  is  carefully  replaced,  so  that  no  bubble  of  air 
is  caught  beneath  it. 

IRON 

Iron  in  water  influences  its  quality  from  the  standpoint  of  desir- 
ability rather  than  from  the  standpoint  of  health.  After  hardness  there 
is  no  question  of  greater  practical  importance  in  considering  the  quality 
of  a  water.  All  natural  waters  contain  a  certain  amount  of  iron,  and 
ground  waters  are  apt  to  contain  it  in  objectionable  amounts.  No 
water  can  be  considered  entirely  satisfactory  that  contains  more  than 
about  1  part  of  total  iron  per  million  parts  of  water.  Appreciable 
amounts  of  iron  render  water  imsuitable  for  domestic  and  technical 
purposes;  it  stains  clothes  in  the  laundry,  but  has  little  sanitary  sig- 
nificance, for  when  present  in  large  amounts,  its  undesirable  taste  would 
preclude  its  use. 

When  iron  is  present  in  water  it  supports  a  fungus  (Crenothrix 
kuehniana),  an  organism  which  may  grow  in  the  pipes  in  sufficient 
amount  to  obstruct  the  flow  of  water  or  even  completely  choke  the  pipe. 
It  is  chiefly  troublesome  in  ground  waters  containing  organic  matter  and 
iron.  This  was  the  cause  of  the  complete  obstruction  of  the  water  pipes 
in  the  New  York  Custom  House  in  1907.  The  same  sometimes  occurs 
in  the  pipes  of  driven  wells. 


IRON  1081 

Iron  is  very  widely  distributed  and  exists  in  practically  all  sands, 
gravels,  soils,  and  rocks  with  which  water  comes  in  contact.  The  solu- 
tion of  the  iron  is  brought  about  by  the  organic  matter.  The  iron  exists 
in  the  soil  as  ferric  compounds.  These  are  reduced  by  the  organic  mat- 
ter to  ferrous  salts,  which  are  soluble  in  water  containing  carbonic  acid. 
Trouble  from  iron  is  always  to  be  expected  when  there  is  an  excess  of 
organic  matter  in  tlie  material  through  which  the  water  passes.  In  a 
well-drained,  j)orous  soil  the  oxygen  from  the  air  circulates  in  the 
pores  of  the  soil  and  furnislies  what  is  required  for  the  oxidation  of  the 
organic  matter.  Iron  is  not  dissolved  under  these  conditions,  even  in 
the  presence  of  large  amounts  of  organic  matter,  but  if  the  air  supply 
is  cut  off,  as  for  instance  in  case  the  pores  of  the  soil  are  filled  with 
water,  the  solution  of  iron  is  sure  to  take  place.  The  iron  is  dissolved 
in  the  form  of  ferrous  salts,  usually  ferrous  carbonate.  When  ground 
waters  containing  iron  are  first  drawn  they  look  clear,  but  the  ferrous 
salts  in  solution  are  soon  oxidized  on  contact  with  the  air  to  insoluble 
ferric  salts,  which  are  precipitated  as  red  oxids. 

Iron  Pipes. — Xearly  all  waters  attack  iron  pipes,  corroding  them  and 
forming  tubercles  on  the  inner  surface.  This  is  objectionable,  be- 
cause it  reduces  the  carrying  capacity  of  the  pipe  and  also  influences 
the  quality  of  the  water. 

Tubercles  are  formed  as  follows :  The  organic  matter  in  the  water 
settles  in  the  pipe  and  attacks  the  iron  through  a  blow  hole  or  other 
minute  opening  in  the  coating.  The  organic  matter  decomposes,  form- 
ing carbon  dioxid,  which  acts  upon  the  iron,  causing  some  of  it  to  go 
into  solution  as  ferrous  carbonate.  The  soluble  ferrous  carbonate  for 
the  most  part  passes  on  in  the  flowing  water,  but  some  of  it  becomes 
oxidized  by  the  oxygen  in  the  flowing  water  and  is  precipitated  as  the 
insoluble  ferric  carbonate  and  remains  at  the  surface  of  the  deposit. 
The  iron  precipitated  in  this  way  acts  as  a  coagulant  upon  the  organic 
matter  in  the  flowing  water  at  the  point  where  the  iron  is  precipitated. 
It  thus  attracts  the  organic  matter  from  the  flowing  water  and  binds  it 
to  that  previously  deposited  into  a  firm,  compact,  but  porous  mass,  and 
this  mass  is  the  beginning  of  a  tubercle.  The  process  is  continuous, 
though  slow.  Many  years  may  elapse  before  the  tubercle  reaches  the 
height  of  an  inch.  Tuberculation  starts  more  freely  and  progresses 
more  rapidly  in  waters  from  rivers  or  reservoirs  containing  suspended 
organic  matter.  It  is  less  troublesome  with  filtered  waters,  and  with  lake 
waters  relatively  free  from  such  suspended  matter.  Tuberculation  may 
be  prevented  by  improving  the  quality  of  the  water  or  by  thoroughly 
coating  the  inside  of  the  pipes  with  asphaltum  or  tar.  Cement-lined 
pipes  are  not  subject  to  tuberculation.  but  have  defects  in  other  particu- 
lars. When  the  process  has  advanced  far  it  may  be  corrected  by  pipe 
scrapers.     They   consist   of   appliances   driven   by   the   water   pressure 


1082  SANITAEY  ANALYSIS  OF  WATEE 

through  the  pipes,  with  arrangements  to  scrape  off  the  tubercles.  This 
temporarily  restores  the  original  carrying  capacity  of  the  pipe,  but  the 
process  must  be  repeated  at  intervals.  It  has  the  disadvantage  of  also 
scraping  off  a  large  part  of  the  tar  coating  and  leaving  the  iron  of 
the  pipe  exposed  to  the  action  of  water  to  a  much  greater  extent. 
(Hazen.) 

Water  that  passes  through  the  water-backs  of  the  kitchen  stove  to 
the  hot-water  tank  is  particularly  likely  to  collect  iron,  which  accumu- 
lates at  the  bottom  of  the  hot-water  tank.  This  deposit  may  accumulate 
for  days  and  even  weeks  until  some  unusual  draught  of  water  or  other 
disturbance  occurs — perhaps  on  washing  day — causing  a  stirring  up  of 
the  iron  precipitate.     When  this  happens  it  is  very  objectionable. 

The  household  filter  is  the  most  convenient  and  satisfactory  means 
of  removing  iron  deposits  from  water  that  is  otherwise  good.  The  re- 
moval of  iron  from  a  city's  water  supply  is  a  distinct  process  rarely 
combined  with  purification.  In  most,  cases  iron  may  be  removed  by 
thoroughly  aerating  the  water  in  order  to  drive  off  the  excess  of  CO, 
and  in  order  to  introduce  oxygen  necessary  to  oxidize  the  iron  from  the 
soluble  ferrous  state,  in  which  it  exists,  to  the  insoluble  ferric  state. 
The  precipitated  ferric  salts  can  then  be  removed  by  sedimentation  or, 
better,  by  filtration. 

LEAD 

Tests. — The  presence  of  lead  may  be  discovered  by  chemical  tests  or 
surmised  from  the  symptoms  of  lead  poisoning  among  those  who  use 
the  water.  In  the  amounts  present  it  does  not  affect  either  the  appear- 
ance or  taste  of  the  water. 

It  is  possible  to  determine  the  presence  of  lead  in  clear  water  and 
roughly  estimate  its  amounts  by  acidifying  with  acetic  acid,  saturating 
with  hydrogen  sulphid  and  comparing  the  brown  tint  produced  with 
that  produced  by  standard  lead  solutions  contained  in  Nessler  tubes  simi- 
lar to  those  for  containing  the  sample  under  examination.  This  method 
is  not  applicable  if  the  water  is  colored  or  contains  iron — in  this  case 
special  analytical  procedures  are  necessary. 

The  sample  of  water  used  for  testing  lead  should  be  the  first  portion 
(a  pint  or  less)   drawn  after  standing  at  least  one  hour  in  the  pipes. 

No  water  should  be  used  for  drinking  purposes  containing  even  a 
trace  of  lead,  for,  however  minute  it  is,  its  presence  in  the  water  indi- 
cates danger.  Very  often  the  sample  examined  will  not  represent  the 
daily  maximum.     See  Lead  Poisoning,  page  1155.  . 


EXPRESSION  OF  CHEMICAL  RESULTS 


1083 


EXPRESSION  OF  CHEMICAL  RESULTS 

Formerly  results  were  expressed  in  grains  per  gallon.  After  the 
introduction  of  the  metric  system  results  were  expressed  in  parts  per 
100,000,  but  now  results  are  commonly  expressed  in  parts  per  million. 
The  latter  method  Jias  the  advantaii-e  that  1  milligram  is  0.000,0(11  liltT, 
and,  therefore,  1  milligram  in  1,000  c.  e.  =  1  part  per  million.  A  liter 
or  a  fraction  thereof  of  the  water  to  be  analyzed  is  used,  which  greatly 
simplifies  the  calculations. 

Of  course,  the  assumption  is  made  that  a  liter  of  water  weighs  a 
kilogram.  This  is  sufficiently  accurate  for  potable  waters,  but  intro- 
duces an  error  where  mineral  waters  are  dealt  with  whose  specific  gravi- 
ties are  appreciably  higher  than  unity.  In  siich  cases  the  water  may  be 
actually  weighed,  or  else  the  weight  may  be  estimated  from  the  known 
specific  gravity  and  volume. 

The  results  expressed  in  parts  per  100,000  or  in  grains  per  gallon 
may  be  transformed  to  parts  per  million,  or,  conversely,  by  the  use  of 
the  following-  table: 


Grains 
per 
U.  S.  Gal- 
lon 

Grains 

per 

Imperial 

Gallon 

Parts  per 
100,000 

Parts  per 
1,000,000 

1  grain  per  U.  S.  gallon 

1  grain  per  Imperial  gallon .  . 
1  part  per  100,000 

1.000 
0.835 
0.585 
0.058 

1.20 
1.00 
0.70 
0.07 

1.71 
1.43 
1.00 
0.10 

17.1 
14.3 
10.0 

1  part  per  1,000,000 

1.0 

CHAPTER  III 
MICROSCOPICAL  EXAMINATION  OF  WATER 

The  chief  object  of  the  microscopic  examination  of  water  is  the  de- 
termination of  the  presence  or  absence  of  those  microorganisms  which 
produce  objectionable  tastes  and  odors.  In  certain  cases  the  determina- 
tion is  also  of  value  as  an  index  of  pollution  or  as  a  guide  to  the  iden- 
tity of  the  water.  The  microscopical  organisms  comprise  the  Dia- 
tomaceae,  Chlorophyceae,  Cyanophyceae,  Pungi,  Protozoa,  Rotifera,  Crus- 
taceae  and  other  organisms  minute  in  size,  but  not  including  the  bacteria. 
Fragments  of  organic  matter,  broken-down  organisms,  zooglea,  etc., 
should  be  termed  amorphous  matter.  Clay,  silt,  oxid  of  iron,  and  mineral 
matter  in  general  are  not  included  under  amorphous  matter  and  are  not 
measured  by  microscopic  examination. 

The  term  "microorganisms"'  as  used  by  the  water  analyst  includes 
all  organisms,  Avhether  plant  or  animal,  that  are  invisible  or  barely 
visible  to  the  naked  eye,  other  than  bacteria.  The  bacteria  are  set  apart, 
inasmuch  as  their  significance  and  the  method  of  studying  them  are  dif- 
ferent from  all  other  microscopic  organisms.  As  Whipple  aptly  phrases 
it,  "Bacteria  make  a  water  unsafe,  microorganisms  make  it  unsavory." 

The  sanitary  quality  of  water  cannot  be  definitely  shown  from  a 
microscopical  examination.  Surface  waters  are  usually  rich  in  micro- 
scopic life,  while  ground  waters  are  comparatively  free.  However,  as 
soon  as  ground  waters  stand  in  pipes  or  are  exposed  to  the  light,  micro- 
scopic organisms .  develop. 

"Plankton"  is  the  general  name  given  to  the  microscopic  aggrega- 
tion which  is  investigated  in  any  given  sample  of  water.  The  term  as 
used  embraces  plants  and  animals  that  float  about  in  the  free  state,  also 
larvae,  egg  masses,  etc.,  of  higher  animals.  It  includes  diatoms,  algae, 
fungi,  protozoa,  etc.^ 

The  Sed^wick-Rafter  Method.— This  is  the  standard  method  for 
counting  the  number  of  microscopic  organisms  in  water.  It  consists  in 
collecting  the  microscopic  particles  suspended  in  a  known  quantity  of 
water,  and  counting  them  in  a  cell  of  known  capacity  under  the  micro- 
scope. The  microscopic  particles  are  collected  upon  sand  by  filtration. 
This  is  done  in  a  straight-sided  cylindrical  funnel,  shaped  and  graduated 
as  shown  in  Fig.  114. 

^  For  a  full  discussion  of  this  subject  see  "The  Microscopy  of  Drinking  Water," 
by  George  C.  Whipple.     John  Wiley  &  Sons,  N.  Y.,  1914. 

1084 


MICROSCOPICAL  EXAMINATION  OF  WATER        1085 


c  c 

100 

CO 

100 

ISO 

300 

250 

i:j 

no 
too 

\ 

so 

/ 

Moisten  a  disk  of  bolting  dotli  and  jilace  it  over  the  small  end  of  the 
rubber  stopper  and  press  it  tightly  into  the  lower  end  of  the  funnel. 
Now  pour  sand  on  to  the  bolting  cloth,  to  the  depth  of  about  1  cm. 
Quartz  sand  or  white  alundum  may  be  used,  but  it  should  first  be  washed 
and  ignited;  and  of  such  size  that  it  will  pass  through  a  sieve  having 
60  meshes  to  the  square  inch,  but  will  not  pass  a  100 
mesh  sieve.  Sand  between  I'-^O  and  IK)  meshes  may 
be  used  if  the  water  contains  very  small  microorgan- 
isms. Now  run  250  c.  c.  of  the  water  to  be  examined 
into  the  funnel  without  disturbing  the  sand.  Filtra- 
tion may  be  hastened  either  by  pressure  from  above 
or  suction  from  below ;  if  the  water  filters  too  slowly 
errors  will  result  from  many  of  the  microorganisms 
sticking  to  the  sides  of  the  funnel.  When  practically 
all  the  water  has  passed  off,  and  the  sand  begins  to 
dry,  hold  the  funnel  in  the  left  hand  and  slope  it 
so  that  the  sand  falls  away  from  the  stopper;  re- 
move the  stopper  and  quickly  slip  a  test  tube  over 
the  end  of  the  funnel  and  allow  the  sand  to  flow 
ilito  it.  Without  removing  the  test  tube,  wash  the 
funnel  with  5  c.  c.  of  distilled  water.  The  mixture 
of  sand,  microorganisms  and  water  in  the  test  tube 
is  agitated,  and  the  supernatant  suspension  decanted 
into  a  second  tube  from  which  1  c.  c.  is  placed  into 
the  counting  cell  of  that  capacity.  Slip  the  cover 
glass  into  place  and  count  the  microorganisms  with 
a  specially  ruled  ocular  micrometer  and  a  2/3-inch 
objective. 

The  counting  cell  consists  of  a  rectangular  brass 
rim  cemented  to  an  ordinary  glass  slide.  The  inside 
dimensions  of  the  rim  are  50  mm.  by  20  mm.  by 
1  mm.,  making  a  capacity  of  one  cubic  centimeter. 
The  roof  of  the  cell  consists  of  a  cover  glass  (No.  3) 
of  sufficient  size. 

The  ocular  micrometer  is  so  ruled  that  the  larg- 
est square  is  1  square  millimeter ;  the  smallest  square 
is  1  standard  unit.  The  area  which  the  largest  square  covers,  on  the 
stage  of  the  microscope  should  be  measured  with  a  stage  micrometer 
and  adjusted  by  changing  the  length  of  the  draw  tube  of  the  microscope 
so  that  this  large  square  will  measure  just  1  square  millimeter.  A  rough 
and  ready  ocular  micrometer  can  be  made  by  cutting  out  a  circle  of 
cardboard  which  will  fit  into  the  tube  of  the  microscope,  this  circle  of 
cardboard  having  a  square  cut  in  its  center,  the  size  of  the  square  to  be 
the  largest  which  the  diaphragm  will  allow.     It  will  be  found  that  the 


Fig.  114. — Gradu- 
ated Cylindri- 
cal Funnel  and 
Concentrating 
Attac  h  m  en  t 
Used  in  the 
Sedgwick  -  Raf- 
ter Method. 


1086         MICEOSCOPICAL  EXAMINATION  OF  WATEE 

area  of  the  stage  which  will  be  included  in  the  field  will  be  approxi- 
mately 1  square  millimeter. 

Recording  Results. — Twenty  full  squares  of  1  mm.  each  are  counted 
at  random,  the  organisms  identified,  and  the  results  calculated  either 
by  the  number  of  organisms  per  cubic  centimeter  of  the  sample,  or, 
better  perhaps,  the  number  of  standard  units  per  cubic  centimeter  of 
the  sample. 

The  number  of  organisms  per  cubic  centimeter  may  be  determined 
from  the  following  equation : 

lOOOW 

Number  per  cubic  centimeter  = 

NF 
W  =  the  number  of  cubic  centimeters  of  water  used  in  washing  the  sand. 
N  =  the  number  of  squares  counted. 
F  =  the  number  of  cubic  centimeters  of  water  filtered. 

The  standard  unit  is  an  attempt  to  measure  the  mass  rather  than 
the  number  of  microscopic  organisms  present  in  the  water.  By  this 
means  a  rough  estimation  of  the  amount  of  suspended  organic  matter 
is  obtained.  Whipple,  who  devised  the  standard  unit  method  of  count- 
ing microorganisms,  defines  the  standard  unit  as  a  square  20  x  20 
microns  =  400  square  microns.     A  micron  is  0.001  millimeter. 

The  ocular  micrometer  used  corresponds  to  the  standard  unit.  A 
square  which  covers  1  square  millimeter  on  the  stage  of  the  microscope 
is  divided  into  four  equal  squares.  Each  of  these  is  subdivided  into 
25  equal  squares.  Each  of  these  contains  25  standard  units.  The  eye 
can  easily  divide  the  side  of  the  smallest  squares  into  fifths,  and  each  of 
these  fifths  is  the  size  of  a  standard  unit. 

Si^ificance  of  the  Examination. — The  microscopical  examination  of 
water  is  of  great  value  in  supplementing  the  chemical  and  bacterial 
analyses.  It  may  explain  the  cause  of  odors  and  tastes  in  a  water;  It 
may  explain  certain  chemical  determinations,  as  albuminoid  ammonia, 
dissolved  oxygen,  oxygen  consumed,  carbon  dioxid,  etc. ;  it  may  indicate 
sewage  contamination;  it  may  suggest  the  state  of  self -purification  of 
a  polluted  water ;  it  may  identify  the  source  of  the  water. 

Several  of  the  microscopic  organisms,  when  present  in  sufficient  quan- 
titieSj  give  rise  to  objectionable  odors  and  tastes,  either  when  in  a  vege- 
tative state  or  upon  decomposition.  The  natural  odors  of  organisms  are 
due  to  oils  analogous  to  the  essential  oils  as  in  peppermint  and  in  cer- 
tain fishes.  In  general,  the  diatoms  have  an  aromatic  odor,  increasing 
to  that  of  a  geranium  leaf,  and  even  to  an  intensity  that  is  fishy.  The 
cyanophyceae,  or  blue-green  algae,  have  a  grassy  or  moldy  odor.  The 
chlorophyceae  have  little  odor,  although  some  of  the  motile  forms  give 
rise  to  faintly  fishy  odors.     The  ciliated  protozoa  have  in  general  no 


THE  BACTERIOLOGICAL  EXAMINATION  1087 

odor.  Urogk'iia,  syiiura,  dinobryoii,  and  pcridiiiium  may  and  often  do 
give  rise  to  fishy  odors.  Of  the  other  microorganisms,  the  rotifera  and 
Crustacea,  no  forms  have  been  recorded  as  giving  rise  to  objectionable 
odors.  These  forms  are  ])resent  only  when  there  are  lower  forms  upon 
which  to  food.  They  are  scavengers  and  as  such  may  be  considered 
as  desirable  elements  in  water.  Their  presence,  however,  calls  for 
an  investigation  of  the  nature  of  their  food  supply,  as  it  is  often  fur- 
nished by  pollution.     This  does  not  necessarily  hold  true  in  all  cases. 

Besides  these  animal  and  plant  forms  there  may  be  present  also 
sponges,  mosses,  yeasts,  and  molds,  the  significance  of  which  is  varied 
and  dependent  upon  local  conditions. 

There  are  many  sources  of  error  in  a  quantitative  determination  of 
the  microscopic  organisms  in  water.  Some  of  the  organisms  stick  to 
the  sides  of  the  funnel ;  some  pass  through  the  sand ;  some  are  so  heavy 
they  settle  in  the  sample,  especially  if  it  has  been  allowed  to  stand;  some 
are  so  fragile  that  they  disintegrate  readily,  and  furtlier  error  may  be 
due  to  unequal  distribution  of  the  organisms  in  the  counting  cell.  For 
all  these  reasons  accurate  results  within  10  per  cent,  are  not  possible, 
and  comparative  results  may  only  be  obtained  by  careful  standardization 
of  methods. 

THE  BACTERIOLOGICAL  EXAMINATION 

Practically  all  natural  waters  contain  bacteria.  This  is  true  of  rain 
water,  ground  water,  and  the  waters  of  lakes,  rivers,  and  oceans.  The 
number  and  variety  of  the  bacteria  vary  greatly  in  different  places  and 
under  different  conditions.  The  bacteria  are  washed  into  the  water  from 
the  air,  from  the  soil,  and  from  almost  every  conceivable  object.  The 
intestinal  contents  of  animals  pollute  waters  with  enormous  numbers 
of  microorganisms,  but  it  is  the  infection  with  certain  species  from  man 
that  makes  water  most  dangerous  when  consumed  by  his  fellowmen. 

A  final  judgment  of  the  potability  of  a  water  should  never  be  given 
upon  the  bacteriological  examination  alone,  but  should  be  combined 
with  a  sanitary  survey.  A  sanitary  survey  may  discover  possibilities  of 
danger,  even  though  the  sample  examined  contains  few  bacteria  and  no 
B.  coli.  On  the  other  hand,  a  water  may  contain  large  numbers  and 
miscellaneous  kinds  of  bacteria  and  yet  a  sanitary  survey  will  disclose 
absence  of  human  pollution. 

THE  NUMBER  OF  BACTERIA  IN  WATER 

The  number  of  bacteria  is  not  as  important  as  the  kind,  3'et  much 
may  be  learned  from  a  simple  enumeration  of  the  bacteria.  Eoughly 
speaking,  the  number  of  bacteria  in  water  corresponds  to  the  amount 


1088        MICEOSCOPICAL  EXAMINATION  OF  WATEE 

of  orc^anic  pollution.  No  known  method  furnishes  a  complete  census 
of  the  bacterial  population  of  a  given  sample  of  water.  Methods  based 
upon  the  direct  microscopic  count  of  the  bacteria  do  not  distinguish  be- 
tween the  live  and  the  dead  ones;  further,  only  those  that  may  readily 
be  seen  by  simple  methods  are  thus  visible.  Many  bacteria,  especially 
those  pathogenic  for  man,  do  not  vegetate  at  20°  C,  so  that  the  usual 
counts  upon  gelatin  may  vary  greatly  from  those  obtained  upon  agar 
at  37°  C.  Some  varieties  require  acid,  others  alkaline  media;  some  are 
aerobic,  others  anaerobic ;  some  will  not  grow  unless  the  medium  contains 
blood  or  other  suitable  pabulum,  and  so  on  through  a  wide  gamut  of 
conditions. 

Although  it  is  not  possible  to  determine  the  total  number,  inferences 
of  importance  may  be  drawn  from  the  differences  in  the  numbers  of 
bacteria  in  a  given  water  obtained  by  different  methods.  Thus  a  water 
containing  great  numbers  of  bacteria,  developing  on  gelatin  at  20° 
C,  and  but  few  colonies  upon  agar  at-  37°  C,  has  little  sanitary  sig- 
nificance, whereas  a  water  containing  few  bacteria,  but  most  of  them 
varieties  that  grow  upon  agar  at  37°  C,  with  relatively  few  at  20°  C, 
must  be  looked  upon  with  suspicion.  The  distinction  between  polluted 
waters  and  waters  of  good  quality  is  more  sharply  marked  by  counts  at 
37°  C.  than  is  the  case  with  counts  at  20°  C,  Another  advantage  of 
growing  the  plates  at  a  higher  temperature  is  that  the  results  are  avail- 
able in  a  much  shorter  time. 

The  number  of  bacteria  which  grow  at  40°  C.  may  be  of  special 
value,  since  this  class  includes  the  typhoid  bacillus  and  other  water- 
borne  pathogens,  but  excludes  the  common  water  bacteria  of  little  sani- 
tary importance. 

From  Germany  we  have  the  arbitrary  standard  based  upon  the  dic- 
tum of  Koch  that  a  good  water  should  not  contain  over  100  bacteria 
per  c.  c.  This  is  a  good  working  rule,  but  should  not  be  taken  too  liter- 
ally. Thus,  water  may  contain  great  numbers  of  the  common  aquatic 
bacteria  which  vegetate  at  room  temperature  and  which  are  not  harmful 
to  man.  Surface  waters  contain  the  greatest  numbers  on  account  of 
exposure  to  contamination  to  which  they  are  liable;  rain  waters  contain 
comparatively  few,  excepting  the  first  shower  through  a  very  dusty  at- 
mosphere ;  ground  waters  from  the  depths  are  practically  sterile.  Un- 
polluted shallow  well  waters  are  also  exceptionally  free.  The  number 
and  significance  of  the  bacteria,  therefore,  vary  with  the  source  of  the 
water.  For  example,  a  hundred  bacteria,  including  a  few  colon  bacilli, 
of  the  fecal  type,  in  a  well  water  would  be  regarded  with  great  suspicion, 
whereas  a  hundred  or  more  bacteria,  with  an  occasional  colon  bacillus,  in 
a  river  water  draining  an  uninhabitated  watershed  would  be  normal. 

The  number  of  bacteria  in  water  depends  somewhat  upon  the  man- 
ner in  which  it  is  stored.     Thus  a  water  containing  a  few  organisms 


THE  BACTRI^TOLOGICAL  EXAATTNATTON  1089 

placed  in  a  closed  bottle  mid  kept  at.  room  tcm|>ci-atiii-<'  may,  at  the  end 
of  24  hours,  contain  Inuidreds  or  thousands  per  (  .  c  I  (ince  examined 
a  deep  well  water  that  was  practically  sterile  as  it  came  out  of  the  earth, 
but  when  stored  in  a  cistern  gave  over  a  thousand  organisms  per  c.  c. 
These  came  from  the  multiplication  of  the  bacteria  that  entered  the 
water  from  the  air,  dust,  leaves,  and  other  sources.  On  the  other  hand, 
water  stored  in  impounding  reservoirs  shows  a  marked  diminution  in 
the  number  of  bacteria. 

The  numerical  determination  of  bacteria  in  water  is  of  very  great 
value  when  studying  surface  waters,  such  as  lakes  and  rivers.  As  a 
rule,  the  number  of  bacteria  is  proportional  to  the  pollution  of  a  river — 
not  necessarily  fecal  pollution,  but  pollution  from  dead  organic  matter 
of  one  kind  or  another.  The  bacterial  content  of  a  river  water  varies 
sharply  from  time  to  time.  Contrary  to  the  usual  opinion,  a  river  con- 
tains more  bacteria  in  the  winter  time  than  in  the  warm  weather.  Dur- 
ing times  of  freshets  or  turbidity  the  number  of  bacteria  will  rise  very 
abruptly.  In  other  words,  the  number  of  bacteria  in  a  stream  is  an 
index  of  its  turbidity.  It  is  an  interesting  fact  that  in  the  Potomac  and 
other  rivers  the  bacterial  curve  does  not  correspond  to  the  typhoid  fever 
curve.  Typhoid  in  Washington  is  highest  in  summer,  but  the  bacteria 
are  most  numerous  in  winter.  While  sudden  variations  in  the  number 
of  bacteria  have  a  ready  explanation  in  the  case  of  turbid  and  torrential 
rivers,  in  the  ease  of  lakes,  and  especially  in  a  ground  water,  variation 
in  numbers  indicates  nearby  sources  of  pollution  and  is  a  danger  signal. 
For  shallow  w^ells  the  interpretation  of  numbers  is  not  so  easy,  largely 
because  infection  may  enter  at  the  surface.  Wells  w^hich  are  poorly  pro- 
tected at  the  top  will  always  show  an  unusually  large  number  and  variety 
of  bacteria. 

Numerical  determination  is  also  of  importance  in  tracing  imperfec- 
tions and  leaks  in  a  water  supply.  Thus  Dr.  Shuttleworth,  of  Toronto, 
was  able  through  this  means  to  suspect  a  broken  water  main,  and  upon 
examination  it  was  found  that  a  whole  section  of  the  conduit  had  dropped 
out  of  place,  so  that  the  supply  was  being  taken  from  the  lake  near  the 
shore  instead  of  some  distance  away  where  the  intake  was  located. 

The  great  value  of  the  numerical  estimate  of  bacteria  is  well  known 
in  determining  the  efficiency  of  filters. 

Method  for  Determining  the  Number  of  Bacteria  in  Water. — The 
standard  medium  for  determining  the  number  of  bacteria  in  w^ater  is  a 
nutrient  agar  having  a  reaction  of  -f-1  P^r  cent.,  using  phenolphthalein 
as  an  indicator.  If  the  reaction  is  between  -|-0.5  per  cent,  and  -|-1.0 
per  cent.,  it  is  not  adjusted.  A  liter  of  nutrient  agar  consists  of  3  grams 
of  beef  extract  (Liebig's  preferably),  5  grams  of  peptone,  12  grams  of 
oven  dried  agar,  and  1,000  c.  c.  of  distilled  water. 

The  sample  of  water  must  be  shaken  vigorously  at  least  25  times 


1090         MICROSCOPICAL  EXAMINATION  OF  WATER 

in  order  to  break  up  the  bacterial  clumps  and  to  obtain  a  uniform  sus- 
pension. If  the  water  contains  less  than  200  bacteria  per  c.  c,  1  c.  c.  of 
it  may  be  placed  directly  in  the  petri  dish,  then  add  10  c.  c.  of  the 
standard  medium.  Mix  well,  congeal,  invert  the  plates,  and  incubate  at 
37°  C.  for  48  hours  in  a  dark,  well-ventilated  incubator  where  the  at- 
mosphere is  practically  saturated  with  moisture.  When  gelatin  is  used 
the  plates  should  be  incubated  at  20°  C.  for  4  days.  If  there  is  reason  to 
believe  that  the  number  of  bacteria  is  more  than  250  per  c.  c,  dilute 
by  mixing  1  c.  c.  of  the  sample  with  9  c.  c.  of  sterilized  tap  or  distilled 
water.  Again  shake  25  times  and  plate  1  c.  c.  of  the  dilution.  Higher 
dilutions  may  be  made  in  99  c.  c.  and  so  on.  In  the  case  of  an  unknown 
water  or  sewage  it  is  customary  to  use  several  dilutions  of  the  same 
sample.  It  is  desirable  to  use  such  portions  of  the  sample  as  will 
give  between  25  and  250  colonies  on  duplicate  plates.  County  the  colo- 
nies upon  a  Wolffhiigel  apparatus  or  a  Jeffer's  plate,  using  a  lens  of 
2l^  diameters,  3i/4"  focus.  It  is  not  necessary  for  one  who  wears  glasses 
to  remove  same  while  counting.  The  whole  number  of  colonies  on  a 
plate  should  be  counted,  the  practice  of  counting  a  fractional  part  being 
resorted  to  only  in  cases  of  necessity. 

When  agar  is  used  for  plating  it  may  be  found  advantageous  to  use 
Petri  dishes  with  porous  earthenware  covers  in  order  to  avoid  the  spread- 
ing of  colonies  by  the  water  of  condensation. 

In  order  to  avoid  fictitious  accuracy  and  yet  express  the  numerical 
results  by  a  method  consistent  with  the  precision  of  the  work,  the  table 
below  should  be  followed  in  expressing  the  numbers  of  bacteria  per  c.  c. : 


From 


1  to 


50  recorded  as  found 


51 

a 

100 

*    to 

the  nearest     5 

101 

a 

250 

li 

10 

251 

U 

500    ' 

a 

25 

501 

u 

1,000    * 

u 

50 

1,001 

u 

10,000    ' 

u 

"      100 

10,001 

u 

50,000    ' 

a 

500 

50,001 

li 

100,000    ' 

u 

"     1,000 

100,001 

u 

500,000    ' 

a 

10,000 

500,001 

u 

1,000,000 

ii 

"    50,000 

1,000,001 

u 

10,000,000    ' 

a 

"   100,000 

KINDS  OF  BACTERIA  IN  WATER 


Water  analysis  is  in  its  infancy  so  far  as  methods  for  determining 
the  kinds  of  bacteria  are  concerned.  It  is  comparatively  easy  to  isolate 
colon  bacilli  and  to  determine  their  approximate  number  in  a  water. 
It  is  also  comparatively  easy  to  isolate  cholera  vibrio.  Methods  for  de- 
termining whether  a  water  does  or  does  not  contain  typhoid,  dysentery, 
and  other  pathogenic  parasites  are  tedious,  difficult,  and  often  impossible 
in  the  present  state  of  our  knowledge. 


THE  BACTERIOLOGICAL  EXAMINATION  1091 

A  certain  amount  of  information  may  be  gleaned  from  the  presence 
and  number  of  organisms  belonging  to  certain  groups,  such  as  chromo- 
genic,  liquefying,  and  fermenting  types.  Chromogenic  organisms  exist 
everywhere  iji  surface  waters.  They  should  be  practically  absent  from 
ground  waters.  The  same  is  true  of  organisms  that  are  able  to  liquefy 
gelatin  and  ferment  sugars.  The  chromogenic,  proteolytic  and  ferment- 
ing types  are  widespread  in  nature  and  exist  almost  everywhere  in  the 
air,  the  soil,  and  in  surface  waters.  Their  presence  in  a  ground  water 
signifies  contamination  or  pollution,  often  from  the  surface. 

The  significance  of  the  various  types  of  bacteria  that  grow  at  dif- 
ferent temperatures  has  already  been  discussed. 

THE  COLON  BACILLUS 

The  Bacillus  coli  group  is  very  widely  distributed  in  nature.  The 
normal  habitat  of  certain  members  of  this  group  may  be  regarded  as. 
the  intestines  of  man  and  many  other  animals.  The  colon  bacillus  is 
usually  taken  as  an  index  of  pollution.  The  sanitary  significance  of 
colon  bacilli  in  water  varies  with  their  number  and,  further,  with  their 
source.  While  the  colon  bacillus  indicates  pollution^  it  does  not  neces- 
sarily signify  danger,  that  is,  infection. 

By  common  consent  a  ground  water  should  be  condemned  if  it  con- 
tains even  a  few  colon  bacilli  of  fecal  type,  for  these  organisms  have 
no  business  in  a  soil-filtered  and  properly  protected  well  or  spring  water.- 
Surface  waters  are  not  regarded  as  particularly  suspicious,  provided  tliey 
have  not  more  than  one  colon  bacillus  per  c.  c,  especially  if  the  surface 
water  is  known  to  drain  an  uninhabited  or  controlled  catchment  area. 
Many  of  the  colon  bacilli  in  a  surface  water  come  from  the  droppings 
of  wild  and  domestic  animals  and,  therefore,  are  infinitely  less  indi- 
cative than  those  that  come  from  the  intestinal  tract  of  man.  Tests 
for  the  colon  bacilli  in  water  must,  therefore,  be  qualitative  and  quan- 
titative. 

Types  of  B.  Coli. — There  are  various  types  in  the  colon  bacillus 
group.  One  type,  believed  to  be  of  fecal  origin,  is  characterized  by  (1) 
a  low  gas  ratio— approximately  equal  volumes  of  carbon  dioxid  and 
hydrogen;  (2)  a  red  reaction  with  methyl  red,  indicating  a  *high  h3^dro- 
gen  ion  concentration;  and  (3)  a  negative  Yoges-Proskauer  reaction,  in- 
dicating the  absence  of  a  certain  type  of  decomposition  of  dextrose.  The 
other  type,  believed  to  be  non-fecal  in  origin  and  sometimes  included 
in  the  B.  aerogenes  group,  has  (1)  a  high  gas  ratio — two  volumes  of 
carbon  dioxid  to  1  volume  of  hydrogen;  (2)  a  yellow  reaction 
Avith  methyl  red;  and  (3)  a  positive  Voges-Proskauer  reaction.  These 
distinctions  are  not  absolute,  for  B.  coli  of  non-fecal   (aerogenes)   type 

^  Carbonated  bottle  waters  mav  contain  B.  coli  in  relatively  large  numbers. 


1092         MICROSCOPICAL  EXAMINATION  OF  WATER 

may  be  found  iii  fresh  feces — although  relatively  few  occur  in  man, 
more  in  other  animals.  Appropriate  laboratory  tests  to  determine  types 
of  the  colon  group,  combined  with  a  sanitary  survey  of  the  watershed, 
will  do  much  to  indicate  the  probability  of  fecal  contamination.  See 
tests  given  below. 

The  absence  of  colon  bacilli  in  water  proves  its  harmlessness  so  far 
as  bacteriology  can  prove  it.  It  is  fair  to  assume  that  typhoid  bacilli, 
dysentery  bacilli,  and  other  intestinal  parasites  would  not  be  likely  to 
be  present  in  a  water  in  the  absence  of  the  colon  bacillus.  It  is  possible 
to  conceive  that  in  rare  instances  a  water  may  be  polluted  with  urine 
alone  containing  typhoid  bacilli,  but  no  colon  bacilli. 

Tests  for  the  Colon  Bacillus. — Presumptive  tests  or  partial  tests 
are  sometimes  used  to  determine  the  presence  of  B.  coli.  These  tests 
are  fairly  reliable,  and  afford  useful  information.  They  consist,  as  a 
rule,  in  planting  small  quantities  of  the  water  sample  in  lactose  bouillon 
in  fermentation  tubes  and  incubating  at  37°  C.  for  24  to  48  hours. 
Under  these  circumstances  it  may  be  presumed  that  in  the  absence  of 
fermentation  colon  bacilli  are  absent,  and  that  fermentation  with  gas 
production  suggests  their  presence.  Both  these  conclusions  may  be 
misleading.  Grossly  polluted  waters  containing  many  colon  bacilli  may 
be  slow  in  fermenting  sugars  with  the  production  of  gas  on  account  of 
the  preponderance  of  other  more  active  species.  On  the  other  hand, 
many  organisms  other  than  the .  colon  bacillus  often  found  in  water 
ferment  sugars  with  gas  production.  It  is  therefore  necessary  to  isolate 
the  suspected  organism  in  pure  culture  and  pass  it  through  the  well- 
known  tests  before  it  is  labeled  B.  coli. 

Presumptive  Tests  for  B.  Coli. — A  satisfactory  method  consists  in 
inoculating  a  10  c.  c.  portion  of  sample  into  each  of  five  fermentation 
tubes  containing  from  30  to  40  c.  c.  of  lactose  broth.  In  order  to 
obtain  a  sufficiently  low  dilution,  so  that  no  fermentation  will  result 
in  one  tube  in  the  series  1  c.  c,  0.1  c.  c,  0.01  c.  c,  or  even  0.001  c.  c. 
(if  heavy  pollution  is  suspected),  portions  of  the  sample  may  be  inocu- 
lated into  lactose  fermentation  tubes.  When  such  small  quantities  of 
water  are  tested,  less  than  30  c.  c.  portions  of  media  mav  well  be  use?!. 
The  fermentation  tubes  described  above  should  be  incubated  48  hours  at 
37°  C.  The  presence  of  10  per  cent,  or  more  of  gas  constitutes  a  pre- 
sumptive test. 

If  in  such  a  series  fermentation  with  gas  production  occurs  in  the 
tubes  containing  1  c.  c.  or  more,  but  does  not  take  place  in  the  tubes 
containing  the  smaller  portions,  it  may  then  be  stated  that  the  water 
contains  at  least  one  colon  bacillus  per  cubic  centimeter,  provided  the 
isolation  tests  show  that  the  fermentation  was  caused  by  this  organism. 

The  number  of  colon  bacilli  may  also  be  determined  approximately 
by  planting  the  water  directly  upon  the  surface  of  lactose  litmus  agar  or 


THE  BACTERTOLOflTCAL  EXAMINATION  1093 

Endo's  medium.  'J'he  rod  colonies  should  then  be  studied  to  determine 
how  many  of  them  are  />'.  coli,  and  th(i  nunil)er  may  thus  be  approxi- 
mated per  cubic  centimeter. 

Confirmation  Tests  for  />.  Coli. — Cultures  should  be  made  on  Endo's 
or  litmus  lactose  agar  plates  from  tube  showing  gas  with  smallest  por- 
tion of  sample,  and  incubated  2-1  to  48  hours.  If  typical  colon-like 
colonies  form,  at  least  two  from  each  sample  should  be  inoculated  on 
agar  slants  and  tubes  of  lactose  fermentation  medium  for  further  con- 
firmation. If,  after  48  hours,  no  typical  colon  colonies  develop  on  the 
Endo's  or  litmus  lactose  agar  plates,  two  colonies  appearing  nearest  like 
coli  are  treated  as  above.  From  the  agar  slant,  examinations  may  be 
made  to  demonstrate  that  the  organism  in  question  is  a  short,  gram 
negative,  non-spore-forming  rod.  If  sufficient  organisms  of  the  B.  coli 
group  have  been  found  to  render  the  water  questionable,  further  studies 
should  be  made  to  determine  their  type,  that  is,  Avhether  fecal  or  non- 
fecal.  This  may  best  be  done  from  colonies  on  Endo's  or  litmus  lactose 
agar  plated  directly  from  the  water,  at  least  10  or  12  colonies  being 
studied.  If  no  direct  platings  from  the  sample  are  available,  a  similar 
study  may  be  made  of  cultures  obtained  from  fermentation  tubes,  but 
these  may  all  be  descendants  of  a  single  cell  in  the  original  sample. 

Differentiating'  Fecal  from  Non-Fecal  B.  Coli — The  Gas  Ratio  Test. — 
The  earlier  workers  in  this  subject  defined  B.  coli  as  an  organism  pro- 
ducing gas  from  dextrose,  consisting  of  one  volume  of  carbon  dioxid 
to  two  volumes  of  hydrogen.  More  recent  work  indicates  that  the  fecal 
coli  usually  produce  carbon  dioxid  and  hydrogen  in  about  equal  volumes, 
and  is  thus  a  low  gas  ratio  organism.  Organisms  of  the  colon  group 
are  frequently  obtained  from  soil,  seeds,  fruit,  leaves,  and  many  other 
similar  non-fecal  sources.  Pollution  of  a  water  supply  by  bacteria 
from  such  a  source  would  not  in  itself  indicate  direct  fecal  contamina- 
tion. Such  organisms  usually  differ  from  the  fecal  type  in  that  they  pro- 
duce carbon  dioxid  and  h3'drogen  in  a  ratio  of  2:1  or  3:1  (high  ratio 
type).  Feces  of  different  animals  as  a  rule  contain  a  small  percentage 
of  this  non-fecal  type  of  organism. 

The  Methyl  Red  Test. — The  fecal  type  of  B.  coli  produces  a  relatively 
high  concentration  of  hydrogen  ions  in  dextrose  broth,  and  this  cor- 
relates very  well  with  low  gas  ratio.  The  non-fecal  type,  in  addition  to 
having  a  high  gas  ratio,  is  characterized  by  a  relatively  low  hydrogen  ion 
concentration.  This  may  be  determined  by  the  addition  of  methyl  red 
to  cultures  of  dextrose  broth.  The  former  (fecal  type)  will  give  a  red 
color,  :=  acid  or  methyl-red-positive,  and  the  latter  (non-fecal  tvpe), 
yellow,  =  alkaline  or  methyl-red-negative. 

The  Voges-Proskauer  reaction  is  also,  useful  in  differentiating  be- 
tween the  various  members  of  the  B.  coli  group.  To  5  c.  c.  of  a  dextrose 
broth  culture,  add  5  c.  c,  of  a  10  per  cent,  solution  of  potassium  hy- 


1094        MICROSCOPICAL  EXAMINATION  OF  WATER 

droxid.  Allow  this  to  stand  12  to  18  hours.  A  positive  test  is  indicated 
by  an  eosin  pink  color,  and  is  seldom  given  by  a  positive-methyl-red  or- 
ganism. This  production  of  pink  color  with  a  fluorescence  is  probably 
due  to  action  of  acetyl-methyl-carbinol  (one  of  the  by-products  in  decom- 
position of  dextrose  by  bacteria)  on  peptone  in  the  presence  of  alkali. 
In  general,  the  methyl -red  positive,  and  Voges-Proskauer  negative  or- 
ganisms may  be  assumed  to  represent  B.  coli  of  fecal  origin;  methyl- 
red  negative,  Voges-Proskauer  positive,  B.  aerogenes  type,  and  most  of 
these  not  fecal  in  origin.  The  presence  in  any  considerable  amount  of 
organisms  of  the  B.  coli  group  would  render  the  water  questionable, 
and  it  would  not  seem  advisable  to  certify  to  its  purity  on  laboratory 
evidence  alone,  even  if  the  organisms  did  appear  to  belong  to  the  so- 
called  non-fecal  type. 

SEWAGE  STEEPTOCOCCI 

Fresh  sewage  from  man  and  other  mammalian  animals  usually  con- 
tains streptococci  resembling  the  Streptococcus  pyogenes.  At  present 
little  stress  is  placed  upon  isolation  of  these  types,  and  the  general  con- 
sensus of  opinion  is  that  the  occurrence  of  these  organisms  in  a  water 
is  of  less  significance  than  B.  coli;  the  streptococcus  test  is  therefore  of 
subordinate  importance. 

TYPHOID  BACILLUS 

The  search  for  a  typhoid  bacillus  in  water  is  frequently  like  looking 
for  a  needle  in  a  haystack;  in  fact,  it  has  seldom  been  isolated  from  a 
drinking  water.  It  is  probable  that  the  typhoid  bacillus  rarely,  if  ever, 
multiplies  in  natural  waters.  The  dilution  is  usually  enormous,  and 
their  number  is  therefore  comparatively  few.  With  modern  methods 
and  the  use  of  Endo's  medium  it  is  comparatively  easy  to  isolate  ty- 
phoid bacilli  from  water  richly  seeded  with  these  organisms,  but  it  is 
practically  a  hopeless  task  to  find  them  when  there  are  only  a  few  in  a 
glassful.  Great  care  must  be  exercised  before  an  organism  isolated  from 
water  is  reported  as  B.  typhosus.  There  are  many  organisms  in  water 
closely  resembling  typhoid,  sgme  of  them  even  giving  pronounced  ag- 
glutination with  specific  serum.  Thus  B.  proteus,  B.  fluorescens,  and 
even  B.  coli  sometimes  agglutinate  with  typhoid  serum  and  in  higher 
dilutions  than  typhoid  strains  themselves.  An  interesting  instance  of 
this  was  found  in  our  studies  of  the  Potomac  River  water.  Frost  iso- 
lated an  organism,  the  " Pseudomonas  protea,"  from  the  filtered  Poto- 
mac River  water  which,  during  the  months  of  August,  September,  and 
October,  1909,  was  more  common  than  B.  coli.  This  organism  could  not 
be  found  in  the  raw  water,  nor  could  it  be  found  in  a  large  number  of 
stools  examined,  which  points  to  a  saprophytic  existence.  This  organ- 
ism may  readily  be  distinguished  from  B.  typliosus,  in  that  it  has  dif- 


THE  BACTERIOLOGICAL  EXAMINATION  1095 

ferent  cultural  characters,  and  further  that  animals  injected  with  cul- 
tures of  Psendomonas  prolea  develop  agglutinations  for  this  organism, 
but  not  for  B.  typhosus. 

CHOLERA 

The  cholera  vibrio  may  be  detected  in  water  by  making  a  Dunham's 
solution  of  the  water  itself;  that  is,  to  a  large  quantity  of  the  water 
sample  add  sufficient  peptone  to  make  a  1  per  cent,  solution,  and  render 
slightly  alkaline  with  sodium  carbonate.  The  water  should  be  placed  in 
Erlenmeyer,  Fernbach,  or  similar  flasks,  presenting  a  large  surface  favor- 
ing aerobic  development.  The  flasks  are  then  placed  in  the  thermostat 
at  37°  C.  and  in  16,  18,  24  hours,  or  longer,  a  loopful  of  the  surface 
gro^i;h  is  planted  upon  agar,  Endo's  medium,  or  gelatin.  Cholera  colo- 
nies upon  gelatin  have  a  ground-glass  appearance  when  examined  under 
a  low  power  of  the  microscope,  with  irregular  margins,  and  the  gelatin 
is  slowly  liquefied.  Upon  agar  the  colonies  are  not  particularly  distinc-' 
tive ;  upon  the  surface  of  Endo's  medium  cholera  grows  as  faintly  pinkish, 
moist,  translucent  colonies,  not  unlike  typhoid  colonies,  excepting  that 
they  have  slightly  more  color.^  Dependence  cannot  be  placed  upon  the 
appearance  of  the  colonies  nor  upon  the  morphological  characteristics 
of  the  organism.  Suspicious  colonies  should  be  isolated  and  tested  with 
an  agglutinating  serum  of  known  specificity  having  a  high  agglutinating 
value.  All  organisms  that  are  agglutinated  with  this  serum  in  a 
dilution  of  1-1.000  or  over  may  be  regarded  as  cholera.  This,  how- 
ever, should  not  be  accepted  as  final,  for,  as  is  the  case  with  typhoid, 
there  are  numerous  cholera-like  organisms  in  water  that  agglutinate 
with  a  cholera  serum,  but  which  upon  further  study  have  characteris- 
tics which  plainly  show  that  they  are  not  the  organism  which  causes 
cholera.  Final  dependence  should  be  placed  upon  Pfeiffer^s  phenomenon 
and  upon  cross-agglutinating  tests  or  absorption  tests  to  eliminate  the 
phenomenon  of  group  agglutination. 

"See  also  pp.  Ill,  140,  and  144. 


CHAPTER  TV 
INTERPRETATION  OF  SANITARY  WATER  ANALYSIS 

The  interpretation  of  a  sanitary  A^^ater  analysis  is  much  more  diffi- 
cult than  the  analysis  itself,  where  everything  may  be  carried  out  by 
rule  of  thumb  in  accordance  with  standard  procedures.  Single  or  occa- 
sional determinations  of  either  the  chemical  or  bacterial  properties  of 
water  are  of  little  value.  A  single  water  analysis  is  often  misleading, 
especially  in  surface  waters,  which  may  vary  greatly  from  time  to  time. 
A  river  water  may  require  repeated  examinations  extending  over  long 
periods  of  time  correlated  with  conditions  of  rainfall,  stream  flow, 
wind,  temperature,  sewage  pollution,  and  other  factors  in  order  to  be 
helpful. 

There  has  been  much  conflict  and  useless  discussion  between  chem- 
ists and  bacteriologists  concerning  the  relative  advantages  of  their 
methods.  The  chemists  were  first  in  the  field,  but  the  limitations  of 
chemical  methods  were  strongly  emphasized  when  it  was  shown  that 
chemistry  can  only  indicate  pollution  but  cannot  discover  infection. 
Much  was  hoped  from  bacteriology,  but  it  is  rather  exceptional  that 
bacteriologists  are  able  to  isolate  pathogenic  microorganisms  from  a 
sample  of  water.  For  the  most  part,  the  routine  bacteriological  exam- 
ination of  water  does  nothing  more  than  the  chemical  examination,  that 
is,  it  shows  pollution  but  does  not  prove  infection.  Both  chemical 
and  bacterial  analyses  of  water  have,  therefore,  distinct  limitations; 
they  do  not  antagonize,  but  supplement  each  other.  From  the  chemical 
side  we  learn  much  of  the  past  history  of  a  water;  the  bacteriology  tells 
us  more  of  its  present  state.  Chemical  methods  reign  supreme  when  we 
desire  to  discover  the  presence  of  lead  or  other  inorganic  poisons;  also 
in  determining  the  hardness,  mineral  and  organic  constituents,  etc. 
From  the  number  and  character  of  the  bacteria  in  water  we  obtain  a 
fair  index  of  the  presence  and  degree  of  pollution.  Occasionally  bac- 
teriologists may  determine  whether  a  water  contains  certain  specific 
agents,  such  as  cholera  vibrio.  It  must,  however,  be  admitted  that  the 
ordinary  routine  chemical  and  bacterial  examination  of  water  affords 
but  meager  information,  especially  when  only  one  analysis  has  beeti 
made.  Fortunately,  the  inferences  drawn  from  a  sanitary  water  analysis 
are  on  the  safe  side,  for  many  good  waters  are  condemned,  so  that  it 
would  be  very  difficult  for  an  unsafe  water  to  pass  the  muster  of  a 

1096 


INTEEPKETATION  OF  SANTTAT^Y  WATETl  ANALYSTS  1097 

C'oinjilcto  sanilarv  analysis.  At  iiiosi,  llie  inl'oniial  ion  fnrnislicd  is  only 
of  present  conditions  and  is  not  a  "guarantee  of  futni'L'  safety.  A  surface 
water  or  a  <,n-ound  water  may  today  be  exceptionally  free  from  cliemit-al 
jmpui'itics  and  piartically  sterile  i)acteriologically,  whereas  tomorrow  it 
may  contain  typhoid,  dysentery,  cholera,  or  other  water-borne  infections; 
these  may  come  from  sources  that  would  at  once  be  perfectly  evident 
from  a  sanitary  survey  of  the  watershed. 

A  sanitary  survey  of  tlie  catcliment  area  is  frequently  of  much 
greater  practical  importance  than  all  the  information  furnished  hy  the 
laboratory.  It  needs  neither  chemists  nor  bacteriologists  to  tell  us  that 
the  water  from  a  creek  with  an  overhanging  privy  a  short  distance  above 
will  some  day  carry  infection;  or  that  the  water  from  a  shallow  well 
in  limestone  or  coarse  gravel  very  near  a  leaking  cesspool  must  be  a 
source  of  danger.  A  sanitary  survey  is  able  to  discover  the  sources  of 
contamination,  the  kinds  of  pollution,  and  the  degree,  often  with  greater 
precision  than  combined  chemical  or  bacteriological  tests.  No  sanitary 
analysis  of  a  water  can  therefore  be  considered  complete  unless  it  includes 
an  examination  of  the  watershed  and  a  study  of  the  geology  and  to- 
pography of  the  catchment  area. 

From  a  sanitary  standpoint,  the  principal  substances  to  look  for  in 
a  chemical  analysis  are  the  organic  matter,  nitrates,  nitrites,  and  chlorin. 
Of  these  the  nitrites  are  the  greatest  danger  signal,  indicating  oxidation 
of.  organic  matter  through  bacterial  activity.  High  chlorin  and  nitrates 
without  nitrites  indicate  passed  or  remote  pollution;  this  is  a  frequent 
combination  in  ground  waters.  The  ammonias  (free  and  albuminoid) 
are  a  measure  of  the  amount  of  nitrogenous  organic  matter  in  the  water. 
A  surface  water  may  safely  contain  an  amount  of  albuminoid  ammonia 
that  would  be  suspicious  in  a  ground  water.  The  significance  of  the 
chlorin  varies  with  the  location  and  source  of  the  water.  Ground  waters 
should  contain  fewer  bacteria  than  surface  waters.  Artesian  wells  should 
be  practically  sterile,  and  a  good  surface  water  should  not  contain  over 
100  bacteria  per  cubic  centimeter.  Waters  that  vary  in  composition 
from  time  to  time  without  evident  cause  must  be  regarded  as  unsafe. 
This  applies  particularly  to  ground  waters.  Surface  waters  vary  greatly 
as  the  result  of  freshets,  etc.,  but  a  ground  water,  pond,  or  lake  should 
show  no  sudden  variations. 

These  general  statements  may  be  quite  misleading  when  interpreting 
the  analysis  of  a  specific  case.  Therefore  several  selected  analyses  and 
interpretations  have  been  given  below. 

Allowable  Limits. — The  following  are  sometimes  considered  as  the 
allowable  limits  of  the  impurities  commonly  regarded  as  permissible  in 
drinking  water. 

Chlorin  depends  upon  the  normal  chlorin  content  of  unpolluted  sur- 
face waters  in  the  neighborhood. 


1098  INTEEPEETATION  OF  SANITAEY  WATEE  ANALYSIS 

Bacteria  not  over  100  per  cubic  centimeter. 

Colon  bacillus  should  be  absent  from  the  ground  water  and  not  more 
than  1  per  10  c.  c.  in  a  stream  or  in  a  river  water. 

Free  ammonia 0.015-0.03 

Albuminoid  ammonia 0.07  -0.35 

Nitrogen  as  nitrites None,  or  at  most  a  trace  (0.0001) 

Nitrogen  as  nitrates 0.3  to  1.6 

[Parts  per  million] 

The  standard  adopted  by  the  government  ^  for  drinking  water  sup- 
plied by  common  carriers  in  interstate  commerce  and  also  for  bottled 
waters  demands  that  the  total  number  of  bacteria  shall  not  exceed  100 


Much  Organic  Matter 
"      CI 
"     NO  2     &    NO3 


Feui  or  No  Bacteria  ^^± 


Few  or  No  Bacteria 


Fig.  115. — Diagram  Illustrating  the  Character  of  the  Ground  Water  in 
Relation  to  Soil  Pollution,  to  Assist  in  the  Interpretation  or  a  Sani- 
tary Analysis.     See  also  Nitrogen  Cycle,  page  998. 


per  cubic  centimeter  when  grown  on  standard  agar  plates  and  counted 
after  twenty-four  hours'  incubation  at  37°  C.  Further,  that  not  more 
than  one  out  of  five  10  c.  c.  portions  of  any  sample  examined  shall 
show  the  presence  of  organisms  of  the  bacillus  coll  group.  Later  (Feb- 
ruary 12,  1917),  the  requirement  was  added  that  the  source  of  water 
supplied  interstate  carriers  be  free  of  contamination. 

According  to  the  International  Boundaries  Commission,  a  raw  water 
containing  over  500  B.  coli  per  100  c.  c.  is  too  polluted  for  use  even 
after  purification. 

Bacteriological  standards  for  drinking  water  supplied  common  car- 
riers in  interstate  commerce  are  given  in  the  U.  S.  Public  Health 
Eeports,  November  6,  1914. 

These  figures  must  not  be  taken  literally,   and  are  not  given  as 

^Public  Health  Reports.  Nov.  16,  1914.    No.  29,  Vol.  XLV,  p.  2959. 


INTERPRETATION  OF  SANITARY  WATER  ANALYSIS  1099 

standards  of  purity,  but  the  maxiiiiuiii  limits  of  the  impurities  allowable 
under  ordinary  conditions.  It  will  be  seen  from  the* illustrative  analyses 
given  below  that  at  times  these  limits  may  be  exceeded  without  sanitary 
significance,  whereas  at  other  times  a  water  well  within  the  prescribed 
limits  may  contain  infection. 

For  a  better  inidcrstanding  a  numl)cr  of  sanitary  analyses  of  water 
are  given  with  an  interpretation.  The  student  is  advised  first  to  study 
the  analyses,  draw  his  own  conclusions,  and  then  compare  them  with  the 
interpretation  given. 

AxALVsis  No.  1 — Gross  Pollution 

Free  ammonia 0.214  part  per  million 

Albuminoid  ammonia 0.810     "  "  " 

Nitrogen  as  nitrites 0.005     ''  "  " 

Nitrogen  as  nitrates 21.0  parts  "  " 

Chlorin    47.0         "  "  " 

Total   residue 412.0        "  "  " 

Volatile  residue 279.0        "  "  " 

Fixed  residue 133.0        "       "         " 

Bacteria  per  c.  c.  upon  gelatin   at   20°    C 65,000 

Bacteria  per  c.  c.  upon  agar  at  37°   C 120,000 

Many  liquefying  colonies.     Many  chromogens  per  c.  c.    . 
Fermentation  in  lactose  bouillon  in  0.001  c.  c.     B.  coli 
present  in  0.01  c.  c. 

This  represents  a  grossly  polluted  water  and  should  unhesitatingly 
be  condemned,  no  matter  what  its  source. 

The  following  analysis  of  the  Hamburg  public  supply  from  tha 
Elbe  River  during  the  cholera  epidemic  of  1892  is  given  in  Chemical 
News,  LXVI,  144 : 

Analysis  No.  2 — Elbe  River  During  Cholera  Epidemic 

Appearance   Turbid  and  very  yellow 

Taste   Slightly   unpleasant 

Odor   Extremely  little 

Deposit    Small  and  dirty-looking 

Chlorin 472.0       parts  per  million 

Free   ammonia 1.065       "        "         ." 

Albuminoid    ammonia 0.293       "        "          " 

Nitrates    26.43         "        "         " 

Required  oxygen  (15  minutes) 0.928       "        "          " 

Required  oxygen  (4  hours) 3.428       "        "          " 

Total   solids 1,160.7          "       "         " 

This  is  given  simply  as  an  instance  of  a  grossly  polluted  river 
(Elbe)  water,  known  to  be  infected. 


1100  INTEEPRETATION  OF  SANITAEY  WATER  ANALYSIS 

Analysis  No.  3 — Boston  Tap,  Typical  (not  averaged  results) 

Free  ammonia 0.010  part  per  million 

Albuminoid  ammonia 0.114     "        "  " 

Nitrogen  as  nitrites 0.000     "        "  " 

Nitrogen  as  nitrates 0.02       "        "  " 

Chlorin 2.7       parts  "  " 

Total  residue.. 27.0        "       " 

Volatile  residue 10.0         "        "  " 

Fixed  residue 17.0         "        "  " 

Hardness,  13°. 
Bacteria  per  c.  c.  upon  gelatin  at  20°  C 77 

B.   coli None 

This   is   a   surface   water,    collected   in   impounding  reservoirs   and 

stored  about  30  days  before  it  reaches  the  consumer.     The  watershed 

is   fairly  well   protected.     The   chemical   analysis   shows   little   organic 

pollution;    the   ammonias    are    moderate    in    amount,    nitrites    absent; 

nitrates  low;   chlorin  normal;   bacteria  indicating  nothing  suspicious. 

The  water  is  of  good  sanitary  quality,  j^udged  by  chemical  and  bacterial 

analysis. 

Analysis  No.  4 — A  Suspicious  Water 

Free  ammonia 0.018  part  per  million 

Albuminoid  ammonia 0.020     " 

Nitrogen  as  nitrites 0.007     " 

Nitrogen  as  nitrates 1.5       parts 

Chlorin 19.3 

Total  residue 106.0         " 

Volatile  residue 37.0        " 


Fixed  residue 69.0         "        "'  " 

Hardness,  33.8°. 

(The  residue  did  not  char  and  gave  no  odor  upon  ignition.) 

Bacteria  per  c.  c.  upon  gelatin  at  20°   C 60 

Bacteria  per  c.  c.  upon  agar  at  37°   C 45 

No    liquefying   colonies.      One   chromogen   per    c.    c.      No 
fermentation  in  lactose  bouillon  in  10  c.  c.     No  B.  coli. 

This  water  came  from  a  driven  well  at  Wenham,  Mass.  Upon  in- 
spection it  was  found  that  the  well  was  400  feet  from  a  stable,  200 
feet  from  a  cesspool,  and  250  feet  from  the  house. 

The  first  thing  that  strikes  our  attention  in  this  analysis  is  the  high 
chlorin.  This,  however,  lacks  sanitary  significance,  as  it  is  normal  for 
the  ground  waters  of  this  neighborhood.  The  hardness  of  the  water  is 
due  to  the  very  fertile  character  of  the  surrounding  soil  through  which 
the  Avater  percolates.  The  carbonic  acid  taken  up  by  the  water  from 
the  decomposing  organic  matter  dissolves  the  lime  in  the  soil.  The 
organic  matter  as  represented  by  the  ammonias  is  quite  low.  The 
nitrates  are  high  and  indicate  that  the  water  has  dissolved  this  end 


mTERPKETATION  OV  SANITAT^Y  WATET^  ANALYSIS  MOl 

product  uf  Ihe  oxidalioii  of  organic  matter  in  its  passage  through  the 
soil  and  perhaps  in  seepage  from  the  eessjxx)!.  The  notiecable  quantity 
of  nitrites  indicates  tliat  all  the  organic  matter  has  not  been  consumer] 
and  that  thi'  niiiicialization  is  not.  coni|)h'te.  'i'lie  small  number  of 
bacteria  present  shows  that  the  liltering  action  of  this  soil  througli  which 
the  water  passes  is  effective  in  keeping  out  sewage  contamination  either 
from  the  surface  or  from  the  cesspool.  This  conclusion  is  strength- 
ened by  the  absence  of  fermenting  organisms  and  especially  the  absence 
of  B.  coll.  The  absence  of  liquefying  bacteria  and  the  presence  of  an 
occasional  chromogenic  organism  indicate  that  there  is  little  or  no  con- 
tamination from  the  surface  and,  in  fact,  upon  inspection  the  platform 
covering  the  well  was  found  to  be  tight  and  well  constructed. 

This  particular  sample  of  well  water  shows  nothing  injurious  to 
health,  and  if  subsequent  analyses  are  equally  satisfactory  the  water 
may  be  uGed  without  fear  for  drinking  purposes.  It  is  plain,  however, 
that  this  well  needs  watching,  for  it  is  evident  that  the  soil  is  already 
surcharged  with  organic  matter,  some  of  which  appears  in  the  water, 
and  a  further  loading  of  the  soil  or  a  break  in  the  cesspool  might 
readily  infect  the  w'ell. 

Analysis  No.  5 — Surface  Pollution  of  a  Well 

JFree  ammonia 0.022  part  per  million 

Albuminoid  ammonia 0.035     "        "  " 

Nitrogen  as  nitrites 0.007     "        "  " 

Nitrogen  as  nitrates 1.0         "        "  " 

Chlorin    19.0       parts"  " 

Total  residue 356.0        "       "  " 

Volatile  residue 151.0        "       "  " 

Fixed  residue 205.0        "       "  " 

(Residue  charred  upon  ignition  with  disagreeable  odor.) 

Bacteria  per  c.  c.  upon  gelatin  at  20°   C 9 

Bacteria  per  c.  c.  upon  agar  at  37°  C 275 

Many  liquefying  colonies.  Several  chromogens  per  c.  c. 
Fermentation  in  lactose  bouillon  in  0.1  c.  c.  B.  coli  present 
in  1  c.  c. 

This  is  a  shallow  well  in  Washington,  D.  C,  28  feet  deep,  the  water 
standing  4  feet  in  the  well.  There  is  a  sewer  60  feet  from  the  well 
and  a  privy  within  a  block.  The  pump  is  old  and  of  wood  and  the 
cover  to  the  well  is  rotten  at  the  base. 

Although  this  water  contains  a  small  amount  of  organic  matter, 
as  indicated  by  the  ammonias,  every  other  factor  indicates  pollution 
both  present  and  past.  The  nitrates  and  nitrites  are  high;  the  chlorin 
is  excessive.  It  is  important  to  notice  that  this  water  has  only  9  bac- 
teria per  cubic  centimeter  when  judged  by  the  colonies  that  grow  upon 
gelatin  at  20°  C.    Nevertheless,  it  contains  colon  bacilli  in  1  c.  c,  other 


1102  INTERPEETATION  OF  SANITARY  WATER  ANALYSIS 

fermenting  organisms,  as  well  as  liquefying  and  chromogenic  colonies. 
It  is  probable  that  most  of  the  contamination  in  this  case  came  from 
the  surface,  as  the  well  had  a  very  poor  and  leaky  platform.  This 
water  should  not  be  used  for  domestic  purposes,  and  if  it  did  not  ma- 
terially improve  after  the  correction  of  the  platform  it  should  be  con- 
demned. 

Akalysi-s  No.  6 — Well  Water,  Surface  Pollution 

Free  ammonia 0.007  part  per  million 

Albuminoid  ammonia 0.018     "  "  " 

Nitrogen  as  nitrites 0.0005  "  "  " 

Nitrogen  as  nitrates 2. ,5       parts  "  " 

Chlorin    14.0         "  "  " 

Total  residue 62.0         "  "  " 

Volatile  residue 32.0        "  "  " 

Fixed  residue 30.0        "  "  'i 

(Residue  charred  upon  ignition  and  gave  disagreeable  odor.) 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 820 

Bacteria  per  c.  c.  upon  agar  at  37°  C 640 

Many  liquefying  colonies.    Many  chromogens  per  e.  c.    Fer- 
mentation in  lactose  bouillon  in  1  c.  c.    B.  coU  in  10  c.  c. 

This  water  came  from  a  shallow  well  in  Washington,  D.  C,  18  feet 
deep,  the  water  standing  3  feet  from  the  bottom.  The  rather  high 
nitrates  and  chlorin  in  this  case  represent  past  pollution.  The  small 
amount  of  organic  matter  with  a  trace  of  nitrites  plus  the  number  and 
character  of  the  bacteria  indicate  surface  pollution.  This  view  is 
strengthened  by  the  fact  that  repeated  examinations  of  the  water  from 
this  well  showed  marked  variations  in  the  number  of  bacteria.  Upon 
inspection  the  pump  and  covering  to  the  well  were  found  in  very  bad 
condition,  leaky,  and  with  surface  drainage  toward  the  well. 

Analysis  No.  7 — Illustrating  Remote  Pollution 

Free  ammonia 0.006  part  per  million 

Albuminoid  ammonia 0.011     "  "  " 

Nitrogen  as  nitrites trace     "  "  " 

Nitrogen  as  nitrates 20.0       parts  "  " 

Chlorin    89.0        "  "  " 

Total  residue 430.0        "  "  " 

Volatile  residue 113.0        "  "  " 

Fixed  residue 317.0         "  "  " 

(No  charring  upon  ignition  •  odor  of  burning  rubber.) 

Bacteria  per  c.  c.  upon  gelatin  at  20°    C 92 

Bacteria  per  c.  c.  upon  agar  at  37°  C 16 

No  liquefying  colonies.     No  chromogens  per  c.  c.     No  fer- 
mentation in  lactose  bouillon  in  10  c.  c.    B.  coli  absent. 


INTERPRETATION  OF  SAXITAKV    WATER   ANALYSIS  1103 

This  is  a  giouiid  watt'i-  from  ;i  shallow  well  in  \Vashin<Tton,  D.  C. 
The  well  is  29  feet  deep  ami  the  water  stands  4  feet  fioiii  the  hottom. 
To])  is  well  protected,  waste  water  drains  to  sewer  iicarhy.  There;  arc 
two  privy  vaults  within  two  hlocks  of  the  well. 

The  analysis  shows  hi^h  clildiin  and  nitrates;  otherwise  nothing 
suspicions.  This  means  ri'inote  i)(.)llntion.  The  organic  matter  has  been 
completely  mineralized  and  the  bacteria  held  back  by  the  soil. 

Analysis  No.  8 — High  Chlurln 

Free  anuijonia 0.016  part  per  million 

Albiniiinoid  anniioiiia 0.015     "        "  " 

Nitrogen  as  nitrites 0.000     "        "  " 

^'itrogen  as  nitrates 0.14       "        "  " 

Chlorin    11.20     parts"  " 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 48 

Bacteria  per  c.  c.  upon  agar  at  37°  C 12 

No  liquefying  colonies.     No  chromogens  per  c.  c.     No  fer- 
mentation in  lactose  bouillon  in  10  c.  c.    B.  coli  absent. 

This  Avater  is  from  a  driven  well  at  Beverley,  Mass.  The  analysis 
shows  nothing  suspicious,  excepting  the  high  chlorin,  which  is  normal 
for  this  neighborhood  and  therefore  lacks  sanitary  significance. 

Analysis  Na.  9 — High  Free  Ammonia;  Deep  Well 

Free  ammonia 0.170  part  per  million 

Albuminoid  ammonia 0.000     "        "  " 

Nitrogen  as  nitrites trace     "        "  " 

Nitrogen  as  nitrates 0.0         "        "  " 

Chlorin    3.1       parts"  " 

Total  residue 115.0         "        "  " 

Volatile  residue 45.0        "       "  " 

Fixed  residue 70.0        "       "  " 

No  bacteria  per  c.  c.  upon  gelatin  at  20°  C. 
No  bacteria  per  c.  c.  upon  agar  at  37°  C. 
No  fermentation  in  lactose  bouillon. 

This  water  is  from  a  driven  well  in  Washington,  D.  C,  96  feet 
deep;  water  stands  81  feet  from  the  bottom.  Good  platform  and  drain, 
and  pump  is  in  first-class  condition. 

It  is  exceptionally  pure,  both  chemically  and  bacteriologically,  ex- 
cepting the  large  amount  of  free  ammonia.  This  supposedly  comes 
from  the  reduction  of  nitrates. 

It  is  not  uncommon  to  find  water  from  deep  wells  to  be  high  in  free 
ammonia,  and  it  is  assumed  that  this  comes  from  a  chemical  reduction 
under  high  pressure,  and  perhaps  temperature  of  the  nitrogenous  matter 
in  coal  and  alluvial  deposits. 


1104  INTEEPEETATION  OF  SANITAEY  WATER  ANALYSIS 

Analysis  No.  10 — Rain  Water  Stored  and  Polluted 

Free  ammonia. 1-050  parts  per  million 

Albuminoid  ammonia 0.175 

Chlorin    2.0  "        ^^  ^^ 

Nitrogen  as  nitrites strong  trace      " 

Nitrogen  as  nitrates 0.0 

Eequired   oxygen 2.25 

Total  residue 20.0         "        " 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 625 

No  fevmenting  organisms.     No  B.  coli. 

This  is  rain  water  from  a  dirty  cistern.  In  appearance  the  water 
was  clear  and  good.  The  analysis  shows  that  the  water  is  dirty  and 
contaminated  with  organic  matter.  The  bacteriological  results  indicate 
absence  of  fecal  pollution.  The  water  is  undesirable,  but  not  dangerous, 
as  far  as  infection  is  concerned. 

Analysis  No.  11 — Artesian  Well  Water,  Shotving  the  Effects  of  Storage 
(The  figures  are  in  parts  per  million) 


Free  ammonia 

Albuminoid  ammonia 

Nitrogen  as  nitrites 

Nitrogen  as  nitrates . 

Chlorin 

Dissolved  oxygen 

Oxygen  required 

Total  residue 

Volatile  residue 

Fixed  residue  (mineral  matter) 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 

Fermentation  in  lactose  bouillon 

B.  coli 


Water  Directly 
from  the  Well 


.0.52 
.003 
.000 
.01 
10.4 
10.65 
.10 
111.0 
40.0 
71.0 
6.0 
in  none 
absent 


Same  Water 

from  the 

Storage  Cistern 


.062 
.016 
.0007 
.01 

10.2 

10.69 
.15 

97. 

30. 

67. 
6500. 
in  0.1  c.  c. 

absent 


This  water  is  from  eight  artesian  wells  at  the  Government  Hospital 
for  the  Insane  at  Anacostia,  D.  C,  375  feet  deep.  The  water  is  forced 
out  by  compressed  air  and  flows  by  gravity  to  the  storage  cistern,  which 
is  of  brick  and  cement,  and  has  a  capacity  of  80,000  gallons. 

It  will  be  observed  that  this  water  is  low  in  total  solids  and  is 
almost  free  of  organic  matter  as  represented  by  the  ammonias,  nitrites, 
nitrates,  and  oxygen  required.  The  water  is  clear  as  it  flows  from  the 
ground,  but  soon  turns  slightly  yellowish  on  account  of  a  small  amount 
of  iron  in  the  ferrous  state  that  is  oxidized  to  the  ferric  salt,  which 
is  insoluble  and  is  precipitated  upon  contact  with  the  air.  The  amount 
of  chlorin  is  somewhat  large,  but  has  no  sanitary  significance  in  this 
case.  .  The  principal  point  in  this  analysis  is  the  bacteriology,  which 


INTERPRETATION  OF  SANITARY  WATER  ANALYSIS  1105 

shows  the  water  to  be  practically  sterile  as  it  flows  from  the  ground, 
but  which  contains  over  (),()()()  bacteria  per  cubic  centimeter  in  the  storage 
cistern.  These  come  from  the  air  and  other  contaminating  objects,  and 
illustrate  the  great  growth  of  the  common  water  bacteria  in  water 
stored  under  these  circumstances.  The  slight  increase  of  the  ammonias 
and  nitrites  in  the  cistern  water,  as  compared  with  the  water  direct 
from  the  well,  indicates  organic  pollution  and  bacterial  activity.  The 
diminution  in  the  residue  results  largely  from  separation  of  the  iron. 
This  water  is  pure  and  wholesome,  despite  the  fact  it  contains  many 
more  bacteria  than  that  usually  allowed.  It  has  been  used  for  some 
years  by  about  3,000  persons,  who  are  singularly  free  from  typhoid  fever 
and  other  water-borne  diseases. 


Analysis  No.  12 — Chemical  and  Bacteriological  Changes  in  Potomac  River  Water 
as  the  Result  of  Storage  and  Filtration 

(The  figures  are  the  averages  of  fourteen  representative  analyses) 


Dalecarlia 

Inlet 

Raw  Water 

Entering 

Storage 

Reservoir 

Dalecarlia 
Outlet 

Raw  Water 

After 

About 

3  Days' 

Storage 

Georgetown 

Reservoir 

Second 

Storage 

Reservoir 

(Water 

Remains 

Here  About 

a  Day) 

Washington 

Reservoir 

3rd  Storage 

Basin 

Water 

Applied  to 

Filter 

Filtered 
Water 
from 
Filtered 
Water 
Reservoir 

Free  ammonia   

0.024 

0.161 

0.0031 

0.61 

2.6 

203.0 
47.1 

156.0 

526 
42 
28 
71 

0.027 

0.131 

0.0051 

0.57 

2.61 

163.0 
48.0 

115.0 

381 
40 
40 
80 

0.022 

0.117 

0.0065 

0.6 

2.61 

160.0 
49.0 

111.0 

306 
33 

40 
73 

0.017 

0.096 

0.0056' 

0.61 

2.47 

141.0 
41.0 

100.0 

235 
16 
41 
52 

0.015 

Albuminoid   ammonia    .  .  . 
Nitrogen   as   nitrites    ..  .. 
Nitrogen  as  nitrates    .... 

0.054 
0.0003 
0.67 
2.53 

Total   residue    

Volatile  residue    

127.0 
39.0 
88.0 

Bacteria    per    c.    c.    upon 

gelatin  at  20°  C 

Per  cent,   of  B.   coli  in   1 

36 
4.7 

Per  cent,   of  B.  coli  in  10 

9.5 

Total    per    cent,    showing 
B.  coli 

14.2 

Analysis  No.  12  is  a  good  illustration  of  the  bacteriological  and 
chemical  character  of  a  river  water,  and  illustrates  the  changes  that 
occur  during  short  storage  (3  to  5  days)  and  after  filtration  through  a 
slow  sand  filter. 

It  will  be  seen  from  this  table  that  there  is  a  gradual  diminution 
in  the  amount  of  free  ammonia  and  a  more  marked  diminution  in  the 
amount  of  albuminoid  ammonia.  The  amount  of  organic  matter  as 
represented  by  the  ammonias  is  diminished  just  one-third.  The  nitrites 
show  an  increase  during  storage  of  the  water,  indicating  active  oxida- 
tion, but  a  marked  decrease  after  it  is  filtered,  showing  the  rapid  com- 
pletion of  the  oxidation  of  the  organic  matter  in  the  filter.    The  nitrate.^ 


1106  INTEEPRETATION  OF  SANITARY  WATER  ANALYSIS 

show  a  tendency  to  increase  in  amount,  which  would  be  expected  as 
the  nitrites  diminish.  It  is  evident  that  storage  and  filtration  have  little 
effect  upon  the  chlorin  content  of  the  water.  The  total  residue  diminishes 
as  the  result  of  storage,  sedimentation,  and  filtration.  It  will  he 
noted,  however,  that  this  diminution  is  more  marked  with  the  fixed 
residue  than  with  the  volatile  residue. 

The  number  of  bacteria  decreases  as  the  result  of  storage,  but  the 
most  marked  decrease  occurs  as  the  result  of  filtration.     It  should  be 


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Fig.  116. — Diagram  Showing  Location  of  Samples. 
Analysis  No.   13,  page  1107. 

remembered  that  all  the  bacteria  in  the  filtered  water  do  not  represent 
those  which  have  passed  the  filter.  The  effect  of  the  few  days'  storage 
upon  this  water  does  not  very  materially  affect  the  number  of  B.  coli, 
but  there  is  a  marked  diminution  in  their  number  as  the  result  of 
filtration. 

The  analyses  of  surface  waters,  shown  in  the  table  on  page  1107,  with 
diagram  showing  the  locations  from  which  samples  were  obtained,  will 
repay  careful  study.  This  table  and  diagram  were  furnished  through 
tlie  kindness  of  Professor  Whipple. 

The  diagram  (Fig.  116)  shows  the  location  of  the  samples  em- 
ployed in  Analysis  No.  13, 


INTERPRETATION  OF  SANITARY  WATER   ANALYSIS  1107 


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CHAPTEE  V 
THE  PUKIFIOATION  OE  WATEE 

The  ways  in  which  water  may  be  puriiied  for  practical  purposes  are 
not  many.  It  is  worth  noting  that  most  of  the  advances  in  water  puri- 
fication come  from  the  development  of.  old  empiric  processes.  It  is  only 
at  long  intervals  that  a  new  method  or  principle  of  treatment  is  dis- 
covered that  is  important  enough  to  find  a  permanent  place  in  the  art  of 
water  purification. 

The  principal  methods  at  present  serviceable  for  the  purification  of 
water  upon  a  large  scale  are:  (1)  storage,  (2)  filtration,  (3)  chemicals, 
such  as  ozone,  hypochlorite  of  lime,  sulphate  of  aluminium  or  iron,  (4) 
ultraviolet  rays. 

No  method  of  purifying  water  can  be  considered  to  approach  a 
satisfactory  hygienic  standard  that  does  not  first  of  all  practically  elim- 
inate water-borne  diseases.  The  process  must  also  reduce  the  turbidity 
and  color  to  inappreciable  amounts  and  remove  something  like  99  per 
cent,  of  the  bacteria,  when  these  organisms  result  from  sewage  pollution 
and  are  fairly  numerous:  there  is  perhaps  no  final  reason  for  the  bac- 
terial standard.  It  has  been  adopted  by  consent  because  it  represents 
a  purification  that  is  reasonably  satisfactory  and  that  can  be  accom- 
plished at  small  cost.  With  the  further  awakening  of  the  sanitary 
conscience  of  the  community  the  standards  will  inevitably  tend  higher, 
and  it  is  probable  that  in  time  our  standards  will  approach  an  ideal 
that  is  now  not  regarded  as  necessary.  At  present  there  is  no  evidence 
that  the  few  microorganisms  left  in  the  water  after  a  satisfactory 
method  of  purification,  such  as  slow  sand  filtration,  are  injurious. 
Certainly,  if  injurious  influence  is  exercised,  it  is  too  small  to  be  de- 
termined or  measured  by  any  methods  now  at  our  disposal. 


NATURE'S  METHODS  OF  PURIFYING  WATER 

In  nature,  water  is  purified  by  various  methods,  the  chief  of  which 
are:  (a)  evaporation  and  condensation,  which  makes  rain  water  the 
purest  of  natural  waters;  (b)  the  self -purification  of  running  streams, 
which  is  a  variable  and  uncertain  quantity;  (c)  storage  in  lakes  and 
ponds  which  clarifies  water  and  in  time  eliminates  danger;  and  (d) 
the  physical,  chemical,  and  biologic  action  of  the  soil  upon  water  that 

1108 


NATURE'S  METHODS  OF  PURIFYING  AVATER       1109 

filters  through  the  soil  into  the  earth,  vhich  is  one  of  nature's  greatest 
purifying  a.iioncics. 

Evaporation,  and  Condensation. — 'i'he  purifying  action  of  the  dis- 
tilling and  condensing  process  through  which  all  meteoric  water  passes 
is  one  of  nature's  honeficcnt  processes.  Enormous  quantities  of  sea 
water,  marsh  water,  and  polluted  water  of  all  kinds  are  thus  returned 
to  us  suitable  for  domestic  use.  Somerville  estimates  that  "ISG.'BIO 
cubic  miles  of  water  are  annually  raised  from  the  surface  of  the  globe 
in  the  form  of  vapor  chiefly  in  the  intertropical  seas."  Water  is  thus 
constantly  being  purified  in  nature.  The  ocean  has  been  compared  to  a 
boiler,  the  sun  to  a  furnace,  and  the  atmosphere  to  a  vast  still.  The 
cooler  air  of  the  higher  atmosphere  and  colder  zones  acts  as  a  con- 
denser, causing  the  precipitation  of  the  distilled  water  as  rain.  About 
three-fourths  of  the  earth's  surface  (145,000,000  square  miles)  is  cov- 
ered with  water,  much  of  which  is  in  the  tropical  belt. 

Self-purification  of  Streams. — Streams  become  purer  during  the 
course  of  their  flow.  Of  this  there  can  be  no  doubt.  This  half-truth 
based  upon  chemical  data  has  in  the  past  suffered  sanitarians  to  permit 
the  use  of  water  that  now  we  know  was  responsible  for  much  sickness 
and  many  deaths.  Streams  become  purer,  but  not  pure.  Some  im- 
purities always  remain,  that  is,  the  process  is  not  complete  and  final. 
All  surface  supplies  are  now  regarded  with  suspicion  and  are  stored, 
filtered,  or  otherwise  purified  before  they  are  used  by  educated  com- 
munities. 

It  was  formerly  said  that  a  stream  purifies  itself  in  seven  miles. 
Such  a  generalization  is  absurd.  "We  now  know  that  it  is  not  the  dis- 
tance so  much  as  the  time  and  opportunity  for  the  various  factors  in- 
volved to  become  effective.  Thus,  Buffalo's  sewage  flows  to  JSTiagara's 
intake,  a  distance  of  about  16  miles,  in  a  few  hours.  There  is  little 
chance  for  self-purification  to  take  place,  and  despite  the  great  dilution 
the  danger  is  very  great.  Niagara's  average  typhoid  rate  for  10  years, 
from  1899  to  1908,  was  132.9  per  100,000,  the  highest  in  the  country. 
A  brisk  flow  brings  the  microorganisms  of  disease  alive  and  virulent  to 
the  intake  of  the  water  works  below;  sluggish  flow  or  stagnation  corre- 
sponds to  storage  and  results  in  the  destruction  of  most  of  the  bacteria 
which  cause  water-borne  infections. 

A  good  instance  of  self -purification  of  streams  was  found- in  the 
studies  of  the  Potomac  River  and  its  relation  to  typhoid  fever  in  the 
District  of  Columbia.  The  Potomac  River  drains  an  area  of  about 
11.400  square  miles  which,  in  1900,  contained  a  population  estimated 
to  be  about  half  a  million,  or  about  44  per  square  mile.  The  velocity  of 
the  flow  of  the  Potomac  is  extremely  variable.  It  takes  from  4  to  7 
days  for  the  water  to  travel  from  Cumberland  to  Great  Falls  (where 
the  Washington  intake  is  located),  a  distance  of  about  176  miles.     The 


1110  THE  PURIFICATION  OF  WATEE 

waters  of  the  Potomac  ara  directly  polluted  by  sewage  at  numerous 
points.  The  direct  pollution  is  contributed  by  about  45,000  individuals, 
or  9,1  per  cent,  of  the  total  population  on  the  watershed.  Of  this 
pollution  about  80  per  cent,  enters  the  river  at  points  176  or  more 
miles  from  the  intake  at  Great  Falls,  about  15  per  cent,  enters  it  at 
points  between  50  and  170  miles  above  Great  Falls,  and  5  per  cent. 
is  contributed  by  about  2,200  of  the  population  and  enters  the  river  at 
points  between  19  and  50  miles  above  the  intake.  There  is  practically 
no  direct  pollution  of  the  Potomac  within  19  miles  of  the  intake.  Here 
we  have  an  instance  of  a  stream  draining  an  extensive  and  populous 
area  and  receiving  industrial  and  human  wastes  from  many  thousand 
persons.  Nevertheless,  self-purification  has  occurred  to  such  an  extent 
that  little,  if  any,  of  the  typhoid  fever  occurring  in  "Washington  could 
be  attributed  to  the  use  of  this  water. 

The  Mississippi  Eiver  is  perhaps  one  of  the  best  examples  of  the 
self-purification  of  a  stream,  for,  after  ^draining  almost  the  entire  conti- 
nental United  States  in  a  flow  of  over  3,000  miles,  it  is  exceptionally 
free  of  intestinal  bacteria  at  New  Orleans,  judged  by  the  comparative 
absence  of  colon  bacilli. 

The  principal  factors  concerned  in  the  self -purification  of  water  are 
varied  and  interesting.  They  are:  (1)  Chemical^  the  oxidation  of 
nitrogenous  organic  matter,  resulting  .  in  its  reduction  or  mineraliza- 
tion; (2)  biologic,  the  death  of  microorganisms  through  antibiosis, 
time,  and  various  means;  and  (3)  physical,  such  as  dilution,  sedimen- 
tation, sunlight,  etc. 

Oxidation. — Organic  matter  is  gradually  oxidized,  thus  diminishing 
the  amount  of  food  for  bacteria.  The  activity  of  the  oxidation  depends 
largely  upon  the  amount  of  dissolved  oxygen  in  the  water.  It  is  there- 
fore favored  by  falls,  rapids,  and  a  turbulent  flow.  It  is  mainly  the 
aerobic  bacteria  which  have  an  active  proteolytic  action,  and  are  thus 
able  to  digest  and  destroy  organic  matter.  During  the  course  of  flow 
the  complex  nitrogenous  substances  are  thus  mineralized.  Chemical 
analyses  show  a  rapid  decrease  in  the  amount  of  organic  matter  and  an 
increase  of  nitrates,  and  diminution  of  nitrites.  It  was  these  facts 
that  led  chemists  to  conclude  that  flowing  rivers  soon  purified  them- 
selves. 

Biological  Factors. — Minute  animals,  such  as  infusoria,  amebae, 
water-worms,  water-fleas,  etc.,  which  exist  in  countless  numbers  in 
certain  waters,  feed  upon  the  organic  matter  and  bacteria,  and  are  a 
considerable  factor  in  the  self-purification  of  water. 

Time  and  antibiosis  play  an  important  role  in  self-purification 
of  streams,  as  they  do  elsewhere.  Pathogenic  bacteria  die  more  quickly 
in  a  polluted  water  than  in  a  pure  water.  It  is  probable  that  symbiosis 
and  antibiosis  here  plays  a  part.    The  saprophytic  bacteria  somehow  help 


NATURE'S  METHODS  OF  PURIFYING  \YATER       1111 

to  kill  off  the  dangerous  varieties.  Pottenkoler  believed  that  the  greater 
part  of  self-purification  is  due  to  the  growth  of  algae  and  other  low  forms 
of  vegetation  which  clear  the  water  of  its  impurities  in  the  same  way  that 
the  higher  plants  utilize  the  decomposing  manure  on  cultivated  fields. 
This  view  is  endorsed  by  Bokorny.  Emerisch,  and  Briiner  and  others 
who  have  studied  the  question.  It  is  proved  that  these  plants  take 
up  all  manner  of  organic  substances.  This  includes  volatile  fatty 
acids,  amino-acids,  glucose,  and  urea.  The  purifying  effects  of  water 
vegetation  are  therefore  placed  near  the  head  of  the  list  of  self-puri- 
rying  agencies. 

Dilution  and  Sedimentation. — Dilution  is  one  of  nature's  real 
sanitary  blessings.  The  abundance  of  water  quickly  dilutes  the  im- 
purities under  ordinary  conditions  so  as  to  render  them  harmless. 
A  small  amount  of  infection  in  a  great  volume  of  river  or  lake  water 
soon  becomes  so  diluted  as  literally  to  become  lost.  It  is  true  that 
one  germ  may  cause  disease  just  as  a  spark  may  start  a  forest  fire, 
but  the  conditions  must  be  exceptionally  favorable.  It  is  fortunate  for 
us  that  a  single  typhoid,  cholera,  or  dysentert-  bacillus,  especially  when 
attenuated,  may  not,  as  a  rule,  induce  disease.  It  is  further  clear  that 
the  chances  of  receiving  a  single  bacillus  in  the  few  glasses  of  water 
one  drinks  are  mathematically  very  small  when  the  dilution  is  very 
great.  Owing  to  tliese  facts  and  to  the  further  fact  that  pathogenic 
spore-free  bacteria  soon  become  attenuated  and  die  in  water,  dilution 
becomes  one  of  our  chief  sanitary  safeguards. 

Sedimentation  is  favored  by  a  slow-moving  stream  containing  in- 
soluble inorganic  particles  such  as  clay.  In  muddy  streams  such  as  the 
Mississippi  and  Potomac  Rivers  the  water  is  purified  in  very  much  the 
same  way  that  the  snow  clears  the  air.  The  particles,  constantly  settling, 
wash  the  water  by  enmeshing  the  bacteria,  which  are  thus  carried  to 
the  bottom,  where  they  are  imprisoned  and  die.  It  is  abnost  a  filtration 
process.  The  water  is  swept  or  scoured  many  times  by  the  innumerable 
fine  particles  in  a  turbid  stream.  This  is  the  same  principle  used  to 
clarify  water  with  chemical  coagulants  such  as  sulphate  of  alumina. 

Sunlight. — The  germicidal  influence  of  sunlight  exerts  its  power 
upon  all  surface  waters.  The  depth  of  penetration  is  slight,  but  varies 
somewhat  with  the  turbidity  of  the  water,  the  strength  and  direction  of 
the  sun's  rays,  and  other  factors. 

Storage  in  Lakes  and  Ponds. — Xature  makes  use  of  the  purifying 
power  of  time  in  storing  water  in  lakes  and  ponds  and  other  surface 
collections.  Very  few  parasites  pathogenic  for  man  multiply  in  water 
under  natural  conditions.  In  time  they  all  die  out.  .  Hence  a  stored 
water  is  reasonably  safe.  In  addition,  the  organic  matter  undergoes  decay 
and  returns  to  its  simple  mineral  constituents.  Hence  a  stored  water 
will  in  time  free  itself  not  only  of  harmful  parasites,  but  also  of  most 


1112  THE  PURIFICATION  OF  WATER 

of  its  organic  pollution.     The  stagnation  of  stored  water  has  been  de- 
scribed on  page  1030. 

The  purifying  power  of  the  soil  has  been  fully  discussed  in  connection 
with  the  nitrogen  cycle  (page  998). 


DISTILLED  WATER 

The  distillation  of  water  is  the  only  method  known  for  rendering  it 
pure  in  a  chemical  sense.  From  a  hygienic  standpoint  it  is  ideal ;  from 
a  practical  and  economic  standpoint  it  has  several  objections.  It  is  used 
especially  on  naval  and  other  vessels  and  in  some  industries. 

In  the  distillation  of  water  the  first  portion  of  vapor  contains  a 
disproportionate  amount  of  volatile  impurities,  if  such  are  present. 
If  the  distillation  is  continued  to  dryness  or  nearly  so  the  concentrated 
solution  of  mineral  and  organic  matters  suffers  reactions  by  which  more 
volatile  matter  is  formed  and  the  distillate  is  again  contaminated.  For 
these  reasons  standard  distilled  water  usually  includes  only  what  is 
technically  termed  the  "middle  run  of  the  still,"  some  of  the  first 
portion  being  rejected  and  the  distillation  stopped  before  all  the  water 
passes  oVer. 

Distilled  water,  even  when  obtained  with  precautions,  is  not  always 
acceptable  for  drinking  purposes.  The  taste  is  flat  and  suggestive  of 
scorched  organic  matter.  This  is  often  ascribed  to  the  want  of  aera- 
tion, but  in  many  cases  the  sample  is  not  improved  by  thorough  aera- 
tion. Even  when  so  improved,  the  additional  operation  adds  expense, 
and  unless  purified  air  is  used  it  adds  organic  matters  living  and  dead. 
Leffmann  believes  that  the  disagreeable  taste  of  distilled  water  is  often 
due  to  volatile  matter. 

The  economic  production  of  a  high-class  distilled  water  is  to  be 
desired  both  from  a  sanitary  and  technical  point  of  view,  such  as  for 
use  by  brewers  and  bottlers  of  soft  drinks,  laundries,  paper  mills,  and 
many  other  processes  requiring  clean  and  pure  water. 

Statements  are  occasionally  made  that  distilled  water  is  too  pure  and 
hence  not  well  adapted  for  drinking  purposes,  but  these  statements 
are  not  based  upon  physiological  principles  or  clinical  experience. 

BOILED  WATER 

Boiling  renders  water  safe  so  far  as  water-borne  infections  are  con- 
cerned. It  also  destroys  the  true  toxins  and  probably  renders  most  poi- 
sonous substances  of  organic  origin  that  may  be  in  the  water  harmless. 
Water  containing  lead  and  other  stable  chemical  substances  injurious  to 
health  would  not,  of  course,  be  rendered  safe  by  boiling. 


FILTia?S  1113 

For  the  traveler,  the  camper,  and  others  Avho  must  use  water  of 
various  sources,  the  character  of  which  cannot  be  readil}'  ascertained, 
ihe  only  safe  procedure  is  to  have  his  own  tea  kettle  and  little  alcohol 
lamp.  Enough  water  may  be  boiled  in  a  few  minutes  in  the  morning  or 
evening  to  last  twenty-four  hours  or  more  for  personal  use.  Chlorinated 
lime  may  also  be  used  for  this  purpose.     See  page  1139. 

Boiling  drives  off  the  dissolved  gases,  which  gives  to  boiled  water  a 
flat  taste.  This  may  be  corrected  by  shaking  the  water  in  a  bottle 
or  stirring  with  an  egg-beater,  or  simply  exposing  it  to  the  air  over 
iiight,  care  being  taken  not  to  rccontaminatc  it.  The  disagreeable  taste 
of  boiled  water  is  partly  due  to  changes  in  the  organic  matter  which 
take  place  at  100°  C.  As  a  matter  of  fact,  it  is  not  necessary  actually  to 
boil  water  to  render  it  safe  so  far  as  typhoid,  cholera,  dysentery,  and 
other  non-spore-bearing  infections  are  concerned.  A  temperature  of 
60°  C.  for  twenty  minutes  or  70°  C.  or  80°  C.  for  a  few  moments  is 
sufficient.  However,  in  the  kitchen,  where  thermometers  and  scientific 
care  are  not  expected,  it  is  better  to  require  the  water  actually  to  boil 
to  insure  safety,  especially  in  w^aters  known  to  be  infected  or  during  epi- 
demics. Boiled  water  may  be  kept  in  covered  pails  or  conveniently 
placed  in  well  stoppered  bottles,  in  which  case  it  may  be  iced  without 
the  risk  of  contamination. 

FILTERS 

Slow  Sand  Filters. — Slow  sand  filters,  also  called  English  filter-beds, 
consist  of  large,  shallow,  tight  reservoirs  suitably  underdrgined  and 
containing  some  five  or  six  feet  of  stratified  filtering  material  of  progres- 
sive degrees  of  fineness,  beginning  at  the  bottom  with  broken  stone  or 
gravel  and  ending  with  an  upper  layer  of  fine  sand.  The  water  is 
passed  through  such  a  filter  very  slowly,  from  above  downward.  The 
cleansing  of  such  a  filter  is  done  by  removing  the  surface  layer  of 
dirty  sand. 

Slowly  passing  water  in  this  way  through  sand  purifies  it  biologically, 
physically,  and  chemically;  nearly  all  of  the  objectionable  bacteria  as 
w'cll  as  other  microorganisms  are  removed  and  many  of  the  particles 
in  suspension  are  strained  out  and  much  of  the  organic  matter  is 
oxidized. 

This  process  is  called  "slow"  sand  filtration  to  distinguish  it  from 
the  rapid  process  known  as  mechanical  filtration.  The  slow  sand  filters 
are  spoken  of  as  the  English  method,  or  as  English  filter-beds,  because 
it  was  in  England  that  they  originated;^  whereas  the  mechanical  filters 

*The  first  recorded  attempt  to  filter  water  through  sand  was  in  1829  when 
the  one-acre  slow  sand  filter  was  built  by  James  Simpson  for  the  East  Chelsea 
Water  Co.,  at  London,  England.     In  1872  a  plant  was  built  at  Poughkeepsie, 


1114         '  THE  PUEIFICATION  OF  WATEE 

are  spoken  of  as  the  American  method,  because  this  process  was  de- 
veloped in  this  country  to  meet  our  special  needs.  The  student  should 
have  a  clear  comprehension  of  the  differences  between  these  two  methods. 
The  water  in  the  slow  sand  filter  passes  very  slowly  through  a  layer 
of  sand;  the  filter  chokes  by  the  clogging  of  the  superficial  layer  of 
sand,  and  the  cleansing  of  this  type  of  filter  is  done  by  removing  this 
layer  or  Sclimutzdecke,  as  it  is  called.  Mechanical  filtration,  on  the 
other  hand,  consists  in  first  adding  a  coagulant  such  as  sulphate  of 
alumina  and  then  passing  the  Avater  rapidly  through  a  layer  of  sand. 


Fig.  117. — Section  of  an  English  Filter-Bed. 

The  sand  is  cleansed  mechanically  by  clever  devices  and  by  a  reversed 
current  of  the  water. 

The  slow  filtration  of  water  through  sand  originated  as  an  empiric 
process  imitating  nature's  method  of  purifying  water  as  it  slowly  passes 
through  the  soil.  It  was  used  before  the  chemistry  or  bacteriology  of 
the  process  was  understood.  In  fact,  the  intimate  processes  concerned 
in  slow  sand  filtration  are  not  yet  part  of  our  philosophy.  We  know 
that  the  spaces  between  the  sand  are  enormous  when  compared  with 
the  size  of  bacteria;  nevertheless,  over  99  per  cent,  of  the  bacteria  are 
held  in  the  superficial  layers  of  the  sand.  Nitrification  and  oxidation  of 
organic  matter  also  take  place.     The  process  is  not  a  simple  straining, 

N,  Y.,  in  accordance  with  plans  prepared  by  Mr.  James  P.  Kirkwood,  which 
was  the  first  practical  attempt  at  purification  of  a  municipal  water  supply 
in  America. 


FILTERS 


nio 


that,  is,  a  sinii)l('.  incclianical  filtration.  It  is  a  "vital"  process  in  which 
haeterial  activity  phiys  a  very  large  part.  The  hacteria,  algae,  and  other 
microorganisms  resting  upon  the  upjier  layer  of  the  sand  grow  and  form 
a  zoiigleal  mass;  each  grain  of  sand  hecomes  coated  with  a  gelatinous 
and  adhesive  growth.  A  continuous  layer  forms  upon  the  surface  a 
carpet-like  mass  which  constitutes  the  Schmuizdeclce.  This  Schmuiz- 
dccl-e  effectively  holds  hack  the  hacteria  in  the  water. 

The  removal  of  the  hacteria  then  is  largely  due  to  the  action  of  the 
hacteria  themselves,  hut  a  visihie  >'<(lnn(itzdecki'  is  not  essential  for  suc- 
cessful sand  filtration.  In  Ilaniljurg,  Lawrence,  and  other  cities  a  green- 
ish or  brown isli,  slimy  Sdmiulzdt'il-e  is  formed  upon  the  surface  of 
the  sand,  and  gradually  becomes  so  thick  and  dense  as  to  offer  much 
resistance  to  the  passage  of  the  water  itself.  The  Sclirnutzdeche  is  then 
removed.      This   can   readily  be   done  by  scraping  or  shoveling,   or  by 


Fig.  118. — The  Arraxgemext  of  a  Slow  Sand  Filter. 


washing  the  surface  sand  with  special  apparatus.  Where  a  visible 
Schmuizdeclce  is  not  formed,  as  in  Washington  sand  filters,  it  is  prob- 
able that  the  microorganisms  which,  form  a  zoogleal  mass  do  not  find 
favorable  conditions  for  growth.  Xevertheless,  in  this  case  the  surface 
layer  of  the  sand  becomes  clogged  in  the  usual  manner  and  the  underly- 
ing sand  is  quite  clean.  The  bacteria  that  escape  the  surface  action 
are  caught  upon  and  stick  to  the  mucilaginous  coating  of  the  sand  par- 
ticles, where  they  perish  as  in  a  trap.  The  experiments  of  the  ]\Iassa- 
chusetts  Board  of  Health  at  Lawrence  show  that  filtration  may  be  as 
effective  from  a  bacteriological  standpoint  without  the  visible  Schmutz- 
decke  as  with  it. 

Construction  and  Operation. — In  view  of  the  importance  of  the 
subject  the  student  should  be  familiar  with  the  general  principles  and 
some  of  the  details  concerning  the  construction  and  method  of  operating 
a  slow  sand  filter. 

It  is  advisable  to  let  the  water  settle  before  it  is  applied  to  the 
sand  for  the  reason  that  this  prevents  undue  choking  or  clogging  of 
the  filters  and  thus  effects  a  great  economy.  One  of  the  main  items 
in  the  cost  of  maintaining  a  slow  sand  filter  is  the  scraping  of  the  sur- 
face layer  and  the  washing  of  the  dirty  sand.  There  are  several  pre- 
liminary methods  of  treating  the  water  before  it  is  applied  to  the  filter. 
These  methods  differ  with  the  character  of  the  water,  and  consi-st  in  the 


IIIG  THE  PURIFICATION  OF  WATER 

main  of  screening,  scrubbing,  or  coagulation.  These  processes  are  dis- 
cussed more  in  detail  upon  another  page. 

A  slow  sand  filter  requires  an  extensive  tract  of  land,  for  it  should  be 
recalled  that  only  two  and  one-half  to  five  million  gallons  of  water  should 
be  filtered  per  acre  per  day.  The  filter  should  be  conveniently  located 
near  the  community  it  is  to  serve,  and  the  high  price  of  urban  property 
is  an  important  economic  consideration.  Thus,  in  Washington  it  re- 
quires 21  acres  alone  for  the  filter-beds  to  furnish  63,000,000  gallons  of 
water  daily  at  a  3-million-gallon  rate  per  acre.  The  settling  basins,  stor- 
age basins  for  the  filtered  water,  sand-washing  apparatus,  pumping  sta- 
tion, laboratory,  and  other  accessories  require  ccmsiderably  more  land. 

The  entire  filtering  surface  is  divided  into  units  known  as  filter-beds. 
The  size  of  each  filter-bed  has  grown  with  the  development  of  the  art. 
In  the  filters  recently  constructed  each  bed  occupies  about  one  acre. 
Each  bed  must  be  an  independent  unit,  so  that  the  rate  of  filtra- 
tion, the  cleaning  and  all  other  operations  may  be  carried  on  without 
disturbing  the  other  beds.  The  pipes  carrying  the  effluent  from  each 
filter-bed  must  be  so  arranged  that  the  water  may  be  wasted  or  util- 
ized. Where  the  climate  is  cold,  filters  should  be  covered  to  prevent 
freezing. 

In  construction  a  filter-bed  is  built  very  much  like  an  ordinary  re- 
inforced concrete  reservoir.  The  bottom  and  sides  must  be  water-tight, 
for  failure  in  this  regard  may  be  annoying  and  dangerous  for  the  reason 
that  there  may  be  considerable  loss  of  filtered  water  or  entrance  of  pollu- 
tion from  the  outside  if  the  pressure  is  reversed.  The  sides  of  the  bed 
are  usually  vertical,  although  it  is  of  some  advantage  to  make  them 
slanting  or  with  horizontal  ledges  in  order  to  diminish  leaks. 

The  sand  may  be  obtained  from  a  river  bed  or  from  sand  banks; 
the  grains  should  be  sharp,  hard  silicates.  If  the  sand  contains  clay 
this  should  be  removed  by  washing  before  it  is  used.  It  is  also  im- 
portant that  the  filtering  sand  should  be  free  from  lime,  which  has  a 
tendency  to  make  the  water  hard.  The  average  diameter  of  the  sand 
best  suited  usually  varies  from  0.2  to  0.3  millimeter.  It  is  especially 
important  that  the  particles  should  be  mainly  of  the  same  size.  This  is 
determined  by  establishing  the  coefficient  of  uniformity. 

The  sand  used  for  filtration  contains  particles  of  various  sizes;  the 
water  is  forced  around  the  larger  particles  and  through  the  finer  inter- 
stices which  occupy  the  intervening  spaces,  so  that  it  is  the  finest  por- 
tion which  mainly  determines  the  efficiency  of  the  sand  for  filtration. 
According  to  Hazen,  a  provisional  basis  which  best  accounts  for  the 
known  facts  considers  the  size  of  grain  such  that  10  per  cent,  by  weight 
of  the  particles  are  smaller  and  90  per  cent,  larger  than  itself.  This 
is  considered  the  effective  size,  and  is  determined  by  sifting  a  weighed 
amount  of  the  sand  through  a  series  of  sieves.    Another  important  point 


FILTERS  llir 

in  regard  to  the  sand  is  its  degree  of  unifonnity;  that  is,  whether  the 
particles  arc  mainly  of  the  same  size  or  whether  there  is  a  great  range 
in  their  diameters.  This  is  shown  by  the  unifonnity  coefficient,  a  term 
used  to  designate  the  ratio  of  the  size  of  grain  which  is  GO  per  cent, 
of  the  sample  finer  than  itself  to  the  size  which  is  10  per  cent,  finer  than 
itself. 

The  usual  thickness  of  the  sand  layer  varies  from  12  to  48  inches. 
The  Imperial  Board  of  Health  of  Germany  has  fixed  12  inches  as  the 
limit  below  which  the  sand  should  never  be  scraped.  The  higher  limit 
is  advisable  wherever  practicable.  In  this  country  the  usual  depth  of  the 
sand  layer  is  about  3  feet,  and  this  is  reduced  by  successive  scrapings 
for  the  purpose  of  cleaning  until  it  approaches  12  inches,  when  the 
sand  is  replaced.  A  thick  sand  layer  has  a  steadying  action  upon  the 
water  on  account  of  the  increased  friction,  and  thus  aids  in  preventing 
irregularities  in  the  rate  of  filtration. 

The  sand  rests  upon  a  stratified  layer  of  rock  and  gravel  laid  in 
graded  sizes  which  supports  it  so  that  it  does  not  work  its  way  down  into 
the  underdrains. 

The  size,  position,  and  nature  of  the  underdrains  are  a  very  essential 
part  of  the  construction  of  a  slow  sand  filter.  The  underdrains  must 
be  set  so  that  the  rate  of  filtration  will  be  the  same  in  all  parts  of  the 
filter.  If  this  part  of  the  apparatus  is  not  properly  designed  in  a  filter- 
bed  having  the  broad  expanse  of  an  acre  the  water  may  pass  through 
the  sand  in  certain  portions  at  the  rate  of  ten  or  more  million  gallons 
while  it  may  be  found  that  at  other  portions  there  is  practically  no  flow 
at  all. 

The  depth  of  the  water  above  the  sand  is  usually  3  feet.  In 
European  filters  the  depth  varies  from  3  feet  to  52  inches.  It  is  com- 
paratively easy  through  simple  mechanical  devices  to  regulate  the  flow 
of  the  applied  water  so  that  the  depth  of  the  water  above  the  sand  will 
remain  uniform. 

Probably  the  most  important  factor  in  the  operation  of  a  slow  sand 
filter  is  the  rate  of  filtration.  The  tendency  has  been  gradually  to  re- 
duce the  rate  during  the  past  thirty  years.  In  this  country  slow  sand 
filters  are  usually  run  at  a  rate  of  about  2,500,000  to  3,000,000  gallons 
per  acre  per  day.  Three  million  gallons  is  the  maximum  rate  com- 
monly allowed.  During  times  of  stress,  however,  or  for  other  reasons, 
the  rate  is  sometimes  speeded  up  to  five  or  six  million  gallons  per  acre 
daily.  In  Hamburg  the  filters  are  not  allowed  to  run  faster  than 
1,600,000  gallons,  and  in  Berlin  2,500,000  gallons.  Water  passed 
through  sand  at  the  rate  of  4,800,000  gallons  per  acre  daily  has  a 
vertical  movement  of  3.94  inches  in  an  hour.  When  the  rate  is  2,400,000 
gallons  the  vertical  motion  is  1.97  inches  per  hour,  and  when  the  rate 
is  slow^er  the  vertical  motion  is  correspondingly   diminished.     It  will 


1118 


THE  FURIFICATION  OF  WATER 


Overflow 


Sand 


thus  be  seen  that  this  process  is  well  named  in  that  the  water  passes 
very  slowly  through  the  filter.  This  is  of  fundamental  importance  be- 
cause the  hour  or  more  during  which  the  water  rests  upon  the  surface 
of  the  sand  and  passes  through  the  superficial  layer  is  the  critical  time 
when  the  bacteria  are  enmeshed  in  the  Schmutzdeche  or  adhere  to  the 
particles  of  sand  and  the  other  biological  and  chemical  processes  take 
place.  The  tendency  of  engineers  is  to  increase  the  rate  of  filtration 
on  account  of  the  evident  economy;  the  tendency  of  sanitarians  is  to 
diminish  it  so  as  to  keep  well  within  the  factors  of  safety.  If  hypo- 
chlorite or  chlorin  is  added  to  the  filtered  water  there  is  no  objection  to 
speeding  up  the  rate  of  the  filter.  The  rate  of  filtration  may  be  governed 
by  automatic  devices  or  may  be  controlled  by  hand  by  simply  regulating 

the  valve  which  governs  the  pipe  carry- 
ing the  effluent  from  each  filter-bed. 
The  friction  of  the  sand  layer  varies 
from  -time  to  time,  so  that  careful  at- 
tention is  required  in  order  to  maintain 
a  steady  flow  and  a  constant  rate,  which 
is  essential,  for  sudden  variations  in 
rate  are  fatal  to  the  successful  purifi- 
cation of  water  by  the  slow  sand  pro- 
cess. 

The  friction  of  the  sand  is  measured 
by  the  loss  of  head.  The  loss  of  head 
is  the  diff'erence  between  the  level  of 
the  water  above  and  below  the  sand 
layer  measured  in  water  gauges.  This 
loss  represents  the  friction  or  resistance 
of  the  sand  layer.  It  greatly  increases  as  the  filter  clogs  up.  When  a 
filter  is  new  or  perfectly  clean  the  loss  of  head  is  usually  about  0.3  foot 
or  less ;  when  it  exceeds  4  feet  the  rate  of  filtration  cannot  be  maintained 
at  3,000,000  gallons  per  acre  daily  with  the  devices  provided,  and  the 
filters  must  be  cleaned. 

The  length  of  time  a  filter  may  run  before  the  loss  of  head  becomes 
so  great  that  it  becomes  unprofitable  and  requires  cleaning  varies  from 
a  few  days  to  many  months.  The  time  depends  upon  the  character  of 
the  water,  the  rate  of  filtration,  and  temperature,  the  formation  of 
the  SchmutzdecTce  and  many  other  factors.  In  cleaning  a  filter  it  is  suffi- 
cient to  scrape  off  only  enough  sand  to  a  layer  that  appears  clean.  As 
a  rule  the  sand  immediately  below  the  surface  is  not  apparently  soiled, 
and  usually  it  is  not  necessary  to  take  off  more  than  an  inch  or  so  of 
the  surface  layer.  This  sand  is  removed  to  special  cleaning  devices, 
where  it  is  thoroughly  washed  with  filtered  water  and  then  stored  in 
bins  and  replaced  when  the  sand  layer  reaches  a  depth  of  about  VZ 


?o  ftP/r-?/i   O  O  rt  O  C,  0,0  0  o  0  o 


Filtered 
Water 


Fig.  119. — Diagram  Illustrating 
"Loss  OF  Head." 


FILTERS  1110 

inches.  Hie  Sclnnutzdecke  and  the  surface  layers  of  the  sand  aro 
usually  removed  by  liand  with  hroad  shovels.  There  are  also  mechanical 
devices  which  accomplish  the  same  purpose.  After  cleansing,  the  efflu- 
ent from  a  filter-bed  should  be  wasted  until  the  bacteriological  examina- 
tion shows  that  tlie  filter  is  again  performing  efficient  work.  This  may 
require  several  days,  the  time  varying  with  the  temperature  and  other 
conditions. 

Efficiency  and  Control  of  Slow  Sand  Filters. — The  efficiency  of  a 
slow  sand  filter  is  mainly  measured  by  a  comparison  of  the  number 
of  bacteria  in  the  raw  and  filtered  water.  A  good  filter  should  eliminate 
at  least  99  per  cent,  of  the  bacteria,  provided  the  applied  water  is 
grossly  polluted.  In  any  event  the  filtered  water  should  not  contain 
over  100  bacteria  per  cubic  centimeter  and  very  few  colon  bacilli.  It 
is  to  be  noted  that  all  the  bacteria  in  the  filtered  water  do  not  represent 
those  that  actually  pass  through  the  sand.  Some  of  them  grow  in  the 
underdrains  and  gravel  layer  and  are,  so  far  as  known,  harmless  varieties. 

In  Germany  the  rate  of  filtration  and  other  factors  are  minutely 
regulated  and  controlled  by  official  ordinances.  In  this  country  the 
operation  of  the  filter  is  usually  left  to  the  individual  caprice  of  the 
engineer  in  charge. 

Xew  Jersey  has  recently  (August,  1918)  passed  a  law  requiring  the 
examining  and  licensing  of  operators  of  water  and  sewage  treatment 
plants,  under  the  direct  control  of  the  State  Department  of  Health. 
This  appears  to  be  pioneer  legislation  of  this  kind  in  this  country.^ 

A  slow  sand  filter  cannot  be  effectively  operated  without  skilled 
superintendence  of  an  engineer  expert  in  the  art  of  water  purification. 
It  also  requires  a  small  laboratory  with  a  competent  bacteriologist,  who 
must  make  daily  observations  of  the  applied  water  and  the  effluent 
from  each  filter.  The  effluent  from  a  filter  not  giving  good  results 
should  be  wasted.  The  water  from  a  new  filter,  or  one  just  scraped, 
should  not  be  used  until  the  bacterial  results  show  that  it  is  accom- 
plishing effective  purification. 

There  are  many  ways  by  which  a  better  effluent  may  be  secured,  such 

as  the  use  of  lower  rates  of  filtration,  finer  grained  filtering  materials, 

and   more   complete   preliminary   treatment,    such   as    settling   basins, 

storage,  or  chemical  coagulation.     The  filtered  water  may  be  further 

purified  with  hypochlorite  of  lime,  chlorin,  ultraviolet  rays,  or  "ozone. 

It  requires  a  surprisingly  small  amount  of  hypochlorite  practically  to 

sterilize  a  filtered  water.     In  Pittsburgh  0.13  part  of  bleaching  powder 

(measured  as  available  chlorin)  per  million  parts  of  water  is  sufficient 

for  this  purpose. 

^  The  need  for  expert  supervision  was  recently  shown  by  the  occurrence  of  an 
epidemic  of  typhoid  fever  at  Xenia,  Ohio.  The  city's  drinking  water  was  treated 
with  bleach,  and  therefore  was  considered  safe.  It  developed  on  investigation 
that  the  hypochlorite  used  had  a  chlorin  content  lower  than  specified. 


1120  THE  PURIFICATION  OF  WATEE 

Because  slow  sand  filtration  has  achieved  such  marked  success  with 
some  waters  and  greatly  reduced  the  amount  of  typhoid  is  no  reason 
why  it  should  be  universally  recommended  under  all  circumstances.  To 
recommend  slow  sand  filtration  in  all  cases  would  be  as  irrational  as 
to  recommend  the  use  of  antitoxin  in  every  case  of  sore  throat.  A 
correct  diagnosis  is  essential.  Every  water  cannot  be  successfully  or 
economically  treated  by  this  process  alone.  Thus,  the  very  turbid  waters 
of  our  South  and  West  contain  particles  of  clay  so  fine  that  they  pass 
a  sand  filter.  No  amount  of  sand  filtration  will  take  out  some  of  these 
particles.  The  Potomac  water  in  times  of  high  turbidity  may  be 
passed  through  a  sand  filter  three  or  four  times  without  removing  the 
residual  turbidity  due  to  these  microscopic  particles.  To  apply  a  very 
turbid  water  to  a  sand  filter  soon  chokes  it  and  adds  unnecessarily  to 
the  difficulty  and  expense  of  the  process.  The  particles  may  be  so  fine 
that  they  will  not  all  settle  even  when  the  water  is  given  long  storage. 
There  are  several  ways  of  solving  this -problem,  which  is  of  first  magni- 
tude for  the  purification  of  the  surface  water  of  a  large  part  of  our 
country.  One  of  the  best  ways  is  to  provide  large  storage  reservoirs, 
so  that  the  water  may  be  taken  from  the  river  only  at  favorable  times, 
rejecting  the  flow  during  periods  of  high  turbidity.  Another  is  to  use 
preliminary  coagulation  with  aluminium  sulphate  and  provide  for  sedi- 
mentation before  applying  the  water  to  the  sand.  Much  of  the  turbidity 
may  be  removed  by  a  rapid  preliminary  filtration  through  some  coarse 
material  such  as  charcoal,  sponge,  etc.  This  process  is  known  as  scrub- 
bing. No  general  rule  can  be  set  down.  Waters  differ  radically,  and 
the  same  stream  varies  from  time  to  time.  Each  problem  must  be 
studied  and  solved  in  relation  to  its  own  special  condition.  Whether 
the  filtered  water  should  be  further  purified  with  bleaching  powder, 
chlorin,  ultraviolet  rays,  or  ozone  depends  upon  circumstances. 

Results  of  Slow  Sand  Filtration. — ^The  cities  listed  in  the  table  on 
the  following  page  purify  their  water  supply  by  slow  sand  filtration.^ 

The  good  results  of  purifying  water  by  the  slow  sand  method  have 
been  abundantly  demonstrated  in  Altone,  near  Hamburg,  in  1892,  dur- 
ing the  cholera  epidemic;  also  in  Hamburg  since  1893  and  in  Lawrence 
also  since  1893;  further  in  Albany,  Philadelphia,  Pittsburgh,  Berlin, 
Paris,  and  many  English  cities.  It  should  be  noted  especially  at  Albany ' 
that  the  typhoid  rate  did  not  come  down  immediately  after  filtration.  It 
sometimes  requires  one  or  two  years  to  reach  the  residual  or  "normal" 
rate.  In  a  few  instances,  such  as  Washington,  D.  C,  and  Youngstown, 
0.,  filtration  of  the  water  was  not  followed  by  a  noticeable  diminution  in 
the  typhoid  rates,  presumably  due  to  the  fact  that  little  of  the  typhoid 
fever  in  these  places  was  water-borne. 

The  best  results  in  water  purification,  as  measured  by  the  improve- 

*List  furnished  by  Allen  Hazen,  March  31,  1920. 


FILTERS  11? 

UST  OF  SLOW  SAND  FILTRATION  PLANTS  IN  U.  S.  AND  CANADA 


Population 


Philadelphia     

Pittsbuigii    

Montreal  

Toronto,  Ont 

Washington    

Indianapolis 

Providence    

Denver 

New   Haven 

Lowell   

Albanv    

Hartford 

Reading    

Springfield       ( Lud- 
low )    

Springfield     ( Little 
River)    

Wilmington    

Lawrence   

Yonkers 

Superior    

Poughkeepsie   

Brookline   

Ogdensburg   

Peekskill 

Steelton    

Dover,  N.  H 

So.  Bethlehem 

Milford,   Mass 

Geneva,  N.  Y 

Ashland,  Wis 

Hudson    

Coatesville,    Pa ...  . 

San  Angelo,  Texas. 

So.  Norwalk 

Middleboro,  Mass.  . 

Greeley,  Col 

St.  Johnsbury,  Vt. . 

Fostoria,  Ohio 

Marblehead,  Mass.. 

Putnam  

Somersworth,  N.  H. 

Mechanicsville, 
N.  Y 

Hion,  N.  Y 

Franklin,  N.  H 

Gardiner,  Me 

Canon  City,  Col.  .  . 

Lambertviile,  N.  J. 

Nyack,  N.  Y 

Bethel,  Conn 

Apollo,  Pa 

Bar  Harbor,  Me.. . . 

Westfield,  N.  Y.... 

Nantucket    

Plot  Springs,  S.  D .  . 
Yuma,  Ariz 


1,549,000 
533,905 
450,273 
370,538 
331,009 
233.050 
224,320 
213,381 
133,005 
106,290 
100,253 
98,915 
96,071 

88,926 


87,411 

85,892 

79,803 

40,384 

27,936 

27,800 

15,933 

15,245 

14,246 

13,247 

13,241 

13,055 

12,446 

11,594 

11,417 

11,084 

10,323 

8,970 

8,210 

8,180 

8,100 

7,730 

7,340 

7,280 

6,700 

6,630 
6,590 
6,130 
5,311 
5,160 
4,637 
4.620 
3,790 
3,010 
(  3,000 
\  10,000 
2,990 
2,962 
2,140 
2,910 


Date  of 
Installation 


1902 
1908-10 

1910 

1905 

1903 

1904 

1890 

1905 

1915 

1899 

Building 

1911-13 

1906 

1909 

1909 

1893-1907 

1903-06-13 

1899 

1874 

1915 

1912 

1909 

1907 

1902 

1905 

1902 

1911 

1895 

1876 

1915 

1907 
1913 
1906 
1897 
1907 
1908 
1907 
1898 


1893 


Area  in 
Acres 


Capacity  in 

Million  Gallons 

per  Day 


1908 
1896 
1899 


1906 

1892 
1903 


70 
56 

6 

9.6 
29 

4.5 
10 
10 

4 

1 

5.6 

4.25 

7.0 


3 

2 

3.25 

4 

0.5 

1.36 

1 

0.8 

0.8 

0.435 

0.4 

0.261 

0.5 

0.74 

0.5 

1.25 

2.5 

0,67 

0.224 
0.5 


0.14 

0.4 
1.0 
0.3 
0.38 

1 

0.8 

0.5 
0.11 
0.4 
0.3 


420 
225 

60 

60 

87 

24 

24 

30 

15 

10  iron  removal 

17 

23 

22 

12 

15 
15 

7 
10 

5  iron  removal 

5 

5 

3 

3 

4 

2 

4 

0.8 

3 

2 

2.5 

2 

1 

2.5 

1.0 

5.0 

2.5 

1.5 

2.0 

1.0 

1.5 

2.6 
1.02 
0.5 
1.0 
2.0       - 

2.0 
0.5 
2.0 

2.5 

1.0 

0.55 


1123 


THE  PURTFlCx\TION  OF  WATER 


LIST  OF  SLOW  SAND  FILTRATION  PLANTS  IN  U.  S.  ANO  CANADA— Continued 


Capacity  in 

Population 

Date  of 
Installation 

Acres 

Million  Gallons 
.per  Day 

Baltimore  Water  Co. 

1905 

0.5 

1.5 

Deposit,  N.  Y 

i,866 

0.11 

0.5 

Mellen,  Wis 

1,830 

0.2 

Hamilton,  N.  Y.... 

1,689 

1.5 

Matawan,  N.  J .  . .  . 

1,650 

0.2 

Marion,  N.  C 

1,520 

0.3 

Buena  Vista,  Cal. .  . 

1,040 

0.5 

Berwin,   Pa 

1,000 

1898 

0.5 

2.0 

Marion,  Mass 

1,000 

0.3 

H  a  r  r  i  s  b  urg,  Pa. 

Jjosp             

1899 

0.12 

0.15 

Poughkeepsie,  H.  R. 

. 

jjosp            

1905 

0.3 

1 

Brooklyn,   Bayside. 

1909 

0.4 

2.0 

Brooklyn,  N.  Y 

1909 

1.0 

RedBank,  N.  J 

1897 

0.03 

0.10 

Calexico,  Cal 

800 

Brooklyn : 

Forest  Stream .  . 

1905 

2.0 

6.0 

Hempstead    .  . . 

1905 

0.9 

3.0 

Far    Rockaway 

1896 

0.92 

10  iron  removal 

nient  in  the  health  and  reduction  of  the  death  rate  among  those  who 
use  the  water,  have  been  obtained  with  slow  sand  filters.  .Hazen  believes 
that  this  is  probably  because  the  method  is  an  old  one,  has  been  long 
and  carefully  studied,  and  has  been  applied  on  a  large  scale  in  well- 
perfected  forms  for  many  years,  rather  than  to  any  natural  superiority 
of  the  method. 

The  purification  of  water  through  slow  sand  filtration  not  only 
diminishes  the  amount  of  typhoid  and  other  water-borne  intestinal  in- 
fections, but  is  believed  also  to  reduce  the  general  death  rate.  This  fact, 
known  as  the  Mills-Eeinecke  phenomenon,  is  discussed  on  page  1148. 

Mechanical  Filters. — The  essential  and  characteristic  features  of 
mechanical  filtration  are:  (1)  The  addition  of  a  chemical  precipitant 
or  coagulant  to  the  water,  and  (2)  then  passing  the  water  rapidly 
through  a  layer  of  sand.  These  are  either  the  gravity  or  the  pressure 
type.  The  filtering  sand  is  contained  in  a  large  wooden,  iron,  or  con- 
crete tank  so  arranged  that  it  can  be  mechanically  washed.*  These 
filters  are  well  named,  not  only  because  the  filtering  sand  is  washed 
mechanically,  but  because  the  action  is  more  strictly  a  mechanical  strain- 

*  Mechanical  filters  date  from  1884,  when  the  process  was  patented  by  J.  W. 
Hyatt  and  Professor  Albert  R.  Leeds.  They  were  first  used  municipally  at 
Somerville,  N.  J.,  in  1885.  The  Hyatt  patent  expired  in  1901,  and  since  then 
numerous  improvements  in  details  have  been  made  and  patented,  considerably 
improving  the  art  of  cleaning  water  through  this  process. 


FILTERS  1\2:> 

ing,  whereas  biological  processes  are  the  main  features  in  the  purification 
of  water  passiiiij:  tlirou^^li  a  slow  sand  filter. 

Washing  the  Filters. — The  filters  are  washed  by  a  reversed  flow  of 
water.  The  sand  may  be  agitated  by  compressed  air;  originally  revolv- 
ing rakes  were  used  in  small  installations.  When  a  ''high  velocity  wash" 
is  provided,  as  is  usually  the  case,  twenty  gallons  or  more  filtered 
water  per  square  foot  of  filter  per  minute  is  forced  in  a  reversed  direc- 
tion through  the  sand.  This  rate  provides  sufficient  force  to  "boil"  the 
sand,  at  the  same  time  ridding  it  of  retained  coagulura.  Low  velocity 
washing  occasionally  used  in  conjunction  with  compressed  air  saves 
filtered  water.  This  requires  filtered  water  to  the  extent  of  5  per  cent, 
of  the  total  daily  pumpage. 

It  has  been  found  that  the  periods  of  operation  in  some  instances 
can  be  more  than  doubled  by  shutting  the  effluent  valve  to  allow  air  and 
gases  entrained  in  the  sand  to  rise,  or  by  slowly  passing  filtered  water 
back  to  drive  it  out  without  disturbing  the  sand. 

Coagulants. — The  coagulants  commonly  used  are  sulphate  of  alu- 
minium, sometimes  alum,  occasionally  sulphate  of  iron.  The  alkaline 
carbonates  present  in  the  water  decompose  the  aluminium  sulphate  with 
the  formation  of  aluminium  hydroxid,  which  is  thrown  out  of  the  solu- 
tion as  a  flocculent,  colloidal,  jelly-like  precipitate.  The  reaction  is 
as  follows: 

AI2  (S0j3-f  3Ca  (HC03)2  =  2A1  (0H)3 -f  3CaS0, -f  6  CO2. 

Calcium  bicarbonate  is  necessary  to  break  up  the  alum,  and  if  not 
normally  present  in  the  water  some  lime  or  soda  must  be  added.  The 
reactions  and  methods  of  estimating  the  quantities  are  given  in  detail  on 
page  1141.  The  precipitated  aluminium  hydroxid  clears  the  water  very 
much  as  white  of  egg  clears  coffee.  Suspended  matter,  including  bacteria 
and  inorganic  particles,  are  enmeshed  and  deposited  on  the  surface  of 
the  sand.  Thus  it  will  be  seen  that  an  artificial  inorganic  SclimutzdecJce 
is  produced  upon  mechanical  filters  instead  of  the  natural  organic 
Schmutzdecke  of  the  slow  sand  filter-bed.  When  this  deposit  becomes 
abundant  enough  to  clog  the  filter  the  filter  is  washed  by  reversing  the 
flow  and  mechanically  agitating  the  sand. 

It  is  advisable  to  provide  coagulating  basins  to  hold  the  water  for 
a  short  time  after  it  has  received  the  coagulant,  in  order  to  aJlow  the 
chemical  reaction  resulting  from  the  treatment  to  take  place.  Such 
basins  also  serve  to  remove  by  sedimentation  much  of  the  precipitate, 
and  the  filters  therefore  do  not  clog  so  readily,  and  cleansing  is  not 
required  so  frequently. 

The  rate  at  which  water  is  passed  through  mechanical  filters  is  very 
great  when  compared  with  slow  sand  filters.  Eates  varying  from  125,- 
000,000  to  175,000,000  gallons  per  acre  per  day  are  used. 


1124  THE  PURIFICATION  OF  WATEE 

One  hundred  and  fifty  million  gallons  per  acre  daily  may  be  taken 
as  a  fair  average  of  what  is  to  be  expected  of  them.  On  account  of 
the  rapid  rat^  of  filtration  there  is  great  economy  of  space.  However, 
while  the  mechanical  filters  are  cheaper  when  first  cost  is  considered, 
the  advantage  is  with  slow  sand  filters  as  far  as  cost  of  maintenance  is 
concerned. 

The  proper  amount  of  coagulant  is  added  to  the  water  by  means 
of  a  small  automatic  measuring  apparatus.  It  requires,  as  a  rule, 
about  one  or  two  grains  of  alum  or  sulphate  of  aluminium  for  each  gallon 
of  water  to  be  treated.  The  amount  of  alum  added  to  the  water  must 
vary  from  time  to  time,  depending  upon  the  turbidity,  the  reaction, 
and  also  upon  the  amount  of  calcium  carbonate  in  the  water.  The 
turbidity  and  composition  of  many  of  our  streams  vary  suddenly  and 
require  a  watchful  eye.  If  too  little  alum  is  added  the  effluent  will  not 
be  clear;  if  too  much  is  used  the  effluent  will  contain  the  excess  of  alum 
in  solution.  Mechanical  filters,  therefore,  require  intelligent  and  con- 
stant supervision  in  order  to  furnish  satisfactory  results. 

Mechanical  filtration  meets  with  special  favor  in  this  country  be- 
cause it  affords  a  comparatively  cheap  method  of  supplying  a  clean- 
looking  water  from  a  very  turbid  source.  The  process  is  particularly 
applicable  to  the  muddy  streams  of  our  South  and  West.  In  fact,  it  is 
the  only  known  method  of  rendering  some  of  these  waters  quite  free 
of  turbidity. 

Mechanical  filters,  when  properly  manipulated,  will  take  out  most 
(from  95  to  99  per  cent.)  of  the  bacteria  contained  in  the  raw  water. 
The  bacterial  purification,  however,  is  not  as  constant  and  uniformly 
high  as  that  obtained  by  slow  sand  filtration.  The  aluminium  hydroxid 
also  takes  out  much  of  the  soluble  coloring  matter  which  the  water  may 
contain,  as  well  as  its  turbidity. 

Judged  by  the  effects  upon  morbidity  and  mortality,  mechanical 
filtration  of  water  alone  has  in  no  instance  given  the  same  satisfactory 
results  afforded  by  slow  sand  filtration.  Most  of  the  older  mechanical 
filters  in  use  in  America  fell  short  in  hygienic  efficiency.  This  was 
especially  true  with  the  old  and  inferior  plants  which  often  were  with- 
out skillful  supervision. 

In  1900,  according  to  Hazen,  1,860,000  people,  or  6.3  per  cent,  of 
the  urban  population  of  the  United  States,  were  being  supplied  with 
filtered  water.  In  1904  the  number  of  people  so  supplied  had  increased 
to  3,160,000,  or  9.7  per  cent,  of  the  urban  population  of  the  country. 
Since  that  time  many  large  cities  have  installed  filter  plants,  until 
(1913)  about  8,000,000  people,  or  over  20  per  cent,  of  the  urban  popu- 
lation, were  being  served  with  filtered  water.  Most  of  this  filtered  water 
is  now  also  treated  with  bleaching  powder  or  chlorin. 


FILTERS 


112i 


The  Difference  between    Slow 

Slow  Sand  Filtration 

English  system  or  English  filter-beds 
— originated  in  England. 


Sand  and  Mechanical  Filtration 
Mechanical  Filtration 

American     system  —  developed     in 
America  to  meet  our  special  needs. 


Has  been  long  in  use  and  elt'ectrve- 
ness  is  established. 


Preliminary  treatment  not  an  essen- 
tial part  of  the  process,  though 
sometimes  desirable. 


Water  passes  slowly  through  a  layer 
of  sand,  in  large,  shallow,  tight 
reservoirs. 


Usual  rates  from  1,600,000  to  5,000,- 
000  gallons  per  acre  per  day. 


Cleaned  by  scraping  surface  layer  of 
sand — Sch  m  utzdecJce. 


The  process  is  mainly  biological, 
partly  a  mechanical  straining. 
Duplicates  nature's  process  of 
purifying  water. 

Partial  oxidation  of  nitrogen  com- 
pounds. 


First     cost     is     large;     maintenance 
comparatively  small. 


Especially  serviceable  for  water  hav- 
ing little  turbidity. 


Removes   about  20  per   cent,   of  the 
coloring  matter. 


Pemoves   about   99   per  cent,   of  the 
bacteria ;  action  is  uniform. 


Favorable  effect  upon  health  demon- 
strated. 


Comparatively  recent  (since  1884), 
and  hygienic  effectiveness  not  fully 
established. 


A  coagulant  is  first  added  to  the 
water — sulphate  of  aluminium, 
alum,  or  sulphate  of  iron. 


Water  passes  rapidly  through  a  layer 
of  sand  in  small  wooden,  concrete, 
or  iron  tanks. 


Usual  rates  100  to  200  times  as  rapid 
—100,000,000  to  175,000,000  or 
more  gallons  per  acre  daily. 


Cleaned  by  reversed  flow  of  water 
and  mechanical  agitation  of  the 
sand — hence  the  name  "mechani- 
cal'' filtration. 

The  process  is  mainly  a  mechanical 
straining.  An  artificial  imitation 
of  nature's  process. 

Chemical  indices  of  pollution  not  af- 
fected. 


First    cost    is    comparatively    small; 
maintenance  large. 

Especially  suitable  for  turbid  waters, 
containing  silt  and  clay. 


Takes    out    nearly    all    of    dissolved 
coloring  matter. 


When  properly  operated  removes 
from  95  to  99  per  cent,  of  bac- 
teria— less  uniform. 


Hygienic  efficiency  not  established, 
but  doubtless  would  be  more  sat- 
isfactory if  well  operated. 


Recent  Tendencies  in  Water  Purification. — The  development  of 
water  disinfection  with  chemicals  (bleach  or  chlorin)  has  lessened  the 
importance  of  filtration  as  a  sanitary  safeguard.  Chemical  disinfection 
invariably  follows  filtration ;  that  is,  filtration  is  now  used  to  render  the 
water  clean,  disinfection  to  render  it  safe.  Filtration  is  now  used 
mainly  to  remove  turbidity  and  color ;  chemicals  are  used  to  kill  typhoid 
and  other  bacteria.     The  sanitary  importance  of  filtration,  therefore,  is 


1126 


THE  PURIFICATION  OF  WATER 


The  following  is  a  partial  list  compiled  by  Hazen  of  places  in  the  United 
States  where  mechanical  filters  are  in  use: 


Place 


Cincinnati    

New  Orleans 

Minneapolis   

East  Jersey  Water  Co 
Hackensack  Water  Co. 

Louisville 

Columbus   

Toledo    

A-tlanta 

Scranton    

Grand  Rapids 

Kansas  City,  Kan .... 

Youngstown     

St.  Joseph 

Fort  Worth 

Evansville  

Norfolk    

Oklahoma  City,  Okla.. 

Harrisburg 

Charleston 

East  St.  Louis 

Terre  Haute 

Binghamton 

Little  Rock 

York  

Chattanooga  

Davenport  

McKeesport  

Augusta,  Ga 

Macon   

San  Diego 

Chester   

Montgomery  

Elmira  

Quincy 

Knoxville 

Newcastle 

Springfield,  Mo.. . .  . . . 

Lexington,  Ky 

Oshkosh,  Wis 

Cedar  Rapids 

Decatur  

Niagara  Falls 

Lorain 

Danville,  111 

Newport,  R.  I 

Watertown,  N.  Y 

Waterloo,  la 

Columbia,  S.  C 

Elgin    

Kingston   

Wilmington,  N.  C.  . .  . 
Newark,  Ohio 


Population 
1910 


363,591 
339,075 
301,408 
300,000 
250,000 
223,928 
181,548 
168,497 
154,839 
129,867 
112,571 
82,331 
79,066 
77,403 
73,312 
69,647 
67,452 
6"4,205 
64,186 
58,833 
58,547 
58,157 
48,443 
45,941 
44,750 
44,604 
43,028 
42,694 
41,040 
40,665 
39,578 
38,537 
38,136 
37,176 
36,587 
36,346 
36,280 
35,201 
35,099 
33,062 
32,811 
31,140 
30,445 
28,883 
27,871 
27,149 
26,730 
26,693 
26,319 
25,976 
25,908 
25,748 
25.404 


Capacity  of  Filters  in 
Gallons  per  Day 


112,000,000 

44,000,000 

20,000,000 

32,000,000 

24,000,000 

37,000,000 

30,000,000 

20,000.000 

21,000,000 

6.000,000 

20.000,000 

6,000,000 

11,000,000 

11,000,000 

5,000,000 

12,000,000 

8,000,000 

4,000,000 

12,000,000 

5,000,000 

11,000,000 

9,000,000 

8,000,000 

5,000,000 

4,000,000 

9,000,000 

7,000,000 

10,000,000 

6,000,000 

5,bbo,bbb 

4,000,000 
1,000,000 
7,000,000 
4,000,000 
4,000,000 
4,000,000 
6,000,000 
3,000,000 
2.000,000 
2,000,000 

'  ieioboibob 

9,000,000 
6,000,000 
6,000.000 
6,000,000 

8.bbb,bbb 

2,000,000 

'  "2i6bb,6bb 

2,000,000 


And  about  250  smaller  plants. 


FILTERS  1127 

lessened,  where  reliance  is  placed  on  chemical  disinfection.  For  these 
reasons,  sand  filters  are  speeded  up.  This  tendency  lias  an  element  of 
danger,  for  the  factor  of  safety  in  many  municipal  water  plants  is  now 
very  small.     Accidents  happen  with  dire  results. 

Nearly  all  of  our  large  cities  have  adopted  filtration  or  chlorination 
or  both.  Boston  is  practically  alone  at  present  in  supplying  an  un- 
filtered,  untreated  water.  The  most  notable  recent  developments  in 
municipal  water  supplies  may  be  found  in  impounded  and  gravity  sup- 
plies. New  York  City  ])ro|)()Spd  to  add  a  ra])i(l  sand  filter  of  320  milliou 
gallons  per  day  to  the  (^rotoii  sii|)|)ly.  Los  Angoics  uses  a  mountain 
stream  250  miles  away  for  her  driiikiug  water,  while  the  IIctch-Hetchy 
project  for  San  Francisco  is  17.")  miles  distant  from  that  city. 

Household  Filters. — The  (iouicstic  filter  as  ordinarily  used  in  the 
household  has  limited  sanitary  value.  The  purification  of  water,  even  by 
so  simple  a  method  as  straining,  requires  a  degree  of  care,  knowledge, 
and  experience  that  is  not  found  in  the  kitchen.  If  a  water  is  infected, 
reliance  should  not  be  placed  upon  any  household  filter  operated  in 
the  usual  way.  It  is  possible  in  the  laboratory  by  the  use  of  special 
precautions  to  pass  water  through  a  Pasteur-Chamberland  or  a  Berkefeld 
filter  so  as  to  obtain  a  sterile  filtrate.  This  requires  skilled  bacteriolog- 
ical manipulation  of  a  kind  that  cannot  be  attained  in  ordinary  service 
in  the  house.  I  have  seen  janitors  "clean''  a  filter  in  such  a  way  as  to 
actually  contaminate  the  water. 

There  are  two  main  types  of  household  filters :  one  made  of  unglazed 
porcelain  (kaolin),  known  as  the  Pasteur-Chamberland,  and  the  other 
made  of  diatomaceous  earth,  the  Berkefeld,  or  Handler.  Even  in  the 
closest  grained  unglazed  porcelain  filter  the  pores  of  the  filter  are  larger 
than  the  bacteria.  The  bacteria  do  not  get  through  on  account  of  the 
tortuous  passage ;  they  adhere  to  the  particles  that  make  up  the  filtering 
substance.  But  if  conditions  are  favorable,  bacteria,  such  as  typhoid, 
may  soon  grow  through  its  walls.  The  Berkefeld  or  Handler  filters  of 
diatomaceous  earth  are  more  porous  than  the  Pasteur-Chamberland 
filters. 

When  a  water  is  not  infected,  but  turbid,  household  filters  are  ser- 
viceable in  rendering  it  clear.  They  are  specially  useful  when  the  tur- 
bidity is  due  to  clay  or  to  iron,  or  other  inorganic  particles  that  may 
readily  be  removed  by  simple  straining. 

The  sanitarian  places  no  reliance  upon  the  filtration  of  water  in 
the  household,  and  for  drinking  purposes  such  water,  if  infected,  or 
suspected,  should  be  boiled.    The  l^oiling  should  l)e  the  last  process. 

Filters  of  natural  stone,  charcoal,  asbestos,  and  a  great  variety  of 
porous  substances  are  on  the  market  for  domestic  use.  These  filters 
may  be  useful  in  cleaning  water  that  is  turbid,  but  they  cannot  be  de- 
pended upon  to  purify  an  infected  supply. 


1128  THE  PUEinCATION  OF  WATEE 

Scrubbing  or  Roughing  Filters. — Scrubbers  are  rapid  coarse-grained 
filters  through  which  turbid  water  is  passed  at  a  very  high  rate  in 
order  to  remove  coarser  particles  and  some  of  the  turbidity.  This 
process  of  scrubbing  the  water  is  principally  used  as  a  preliminary 
to  sand  filtration.  It  is  designed- to  protect  the  sand  filters  from  clog- 
ging up  too  quickly  and  thus  economize  the  operation.  Scrubbers,  also 
known  as  roughing  filters,  consi.st  of  some  porous  substances  such  as 
sponge,  coke,  and  lava.  The  principal  difficulty  connected  with  a  scrub- 
ber is  an  efficient  and  economical  device  for  cleaning  them,  which  must 
be  done  at  frequent  intervals. 

Screening. — Screening  or  straining  is  used  particularly  to  remove  fish 
and  floating  leaves,  sticks,  etc.  Screens  may  consist  of  steel  bars  arranged 
so  that  they  may  be  easily  raked  off,  or  of  wire  cloth  arranged  in  pairs,  so 
that  while  one  screen  is  raised  for  cleaning  its  mate  is  below  in  service. 
Eevolving  screens  are  efficient.  The  motion  should  be  continuous,  and 
the  cleaning  is  done  on  that  part  of  the  screen  above  the  water  by  jets 
of  water  playing  upon  it.  Screening  is  of  no  service  in  removing  algae 
or  microorganisms,  and  can  only  be  depended  upon  to  remove  the  coarse 
particles,  and  is  only  necessary  where  the  water  contains  such  material. 
Thus,  St.  Paul  uses  a  motor-driven  rotary  screen  of  80  mesh  monel  metal 
to  eliminate  vegetable  and  solid  matter  in  its  lake  water  supply. 


STORAGE 

The  storage  of  water  is  one  of  the  simplest  and  best  means  of  purify- 
ing it.  The  first  cost  may  be  large,  but  the  cost  of  maintenance  is  com- 
paratively trifling.  Harmful  bacteria  soon  die  in  a  stored  water,  the 
solid  particles  settle  out,  the  organic  matter  is  largely  oxidized,  the 
color  is  gradually  bleached,  and  other  improvements  take  place.  Storage 
takes  advantage  of  many  of  nature's  methods  of  purifying  water,  viz., 
time,  sunlight,  dilution,  sedimentation,  oxidation,  and  antibiosis. 

A  stored  water  may  deteriorate  in  quality  owing  to  the  growth  of 
algae  and  the  decomposition  of  organic  matter.  Algae  and  diatoms 
grow  in  stored  water  exposed  to  sunlight,  particularly  in  warm  weather. 
While  these  organisms  are  not  harmful,  they  impart  disagreeable  tastes 
and  odors  to  the  water.  See  page  1050.  The  decomposition  of  the 
organic  matter  in  a  storage  water  may  also  cause  unpleasant  tastes 
and  odors,  especially  at  the  spring  and  fall  overturn.  See  page  1031. 
Waters  stored  in  a  closed  reservoir  keep  without  deterioration,  and  the 
advantage  is  therefore  manifest.  Filtered  water  should  always  be  stored 
in  covered  reservoirs,  not  only  to  protect  it  from  strong  light,  but  also 
to  prevent  contamination  from  dust  and  other  sources. 


CHEMICAL  METHODS  OF  PURIFYIXO  WATER       11>!) 

SEDIMENTATION 

Sedimentation  is  of  limited  use  in  improving  the  sanitary  quality  of 
a  water.  Sedimentation  basins  are  frequently  used  as  a  preliminary 
process  in  water  purification.  It  is  the  cheapest  way  of  removing  rela- 
tively large  particles  which  will  scttU'  out  in  a  moderately  short  time. 
There  is  also  a  sanitary  advantage  in  that  the  suspended  particles  me- 
chanically carry  down  with  them  some  of  the  bacteria.  The  water, 
as  a  rule,  does  not  remain  in  the  sedimenting  basins  long  enough  to 
obtain  the  full  effects  of  storage. 

Sedimentation  is  a  very  important  factor  in  the  bacterial  purification 
of  flowing  streams.  The  effect  of  sedimentation  is  most  manifest  when 
the  flow  of  water  is  rapid  enough  to  prevent  accumulation,  at  any  point, 
of  the  products  of  bacterial  multiplication,  but  not  so  rapid  as  to  inter- 
fere with  a  comparatively  rapid  action  of  gravity.  Turbid  streams' 
purify  themselves  through  sedimentation  more  quickly  than  clear 
streams,  owing  to  the  washing  or  scouring  action  of  the  particles  as 
they  fall  through  the  water. 


CHEMICAL  METHODS  OF  PURIFYING  WATER 

Methods  for  chemically  purifying  drinking  water  include  the  use  of 
lime,  ozone,  permanganate  of  potash,  various  metals  and  their  salts,  and 
chlorin  and  its  compounds  the  hypochlorites.  Other  methods  have  em- 
ployed hydrogen  peroxid,  barium  peroxid,  peroxid  of  chlorin  (ClOo)  and 
bromin  and  chlorin  together. 

Ozone. — Ozone,  discovered  by  Schonbein  in  1840,  is  one  of  the  most 
satisfactory  methods  of  purifying  water  from  a  sanitar\'  standpoint. 
As  a  germicide  it  is  the  most  effective  of  all  the  methods  used  except 
boiling.  A  ozonized  water  is  practically  sterile  and  the  organic  matter 
is  partially  oxidized.  It  is  true  that  a  few  resisting  spores  are  not 
killed,  but  they  are  harmless  when  taken  by  the  mouth.  The  limitations 
of  the  ozone  process  are  that  it  does  not  clarify  the  water  in  any 
way,  and  that  it  has  practically  no  effect  upon  the  mineral  salts.  From 
a  practical  standpoint  the  expense  of  producing  ozone  in  sufficient  con- 
centration is  disproportionately  large,  but  this  is  an  electrical  engineer- 
ing problem  which  is  showing  encouraging  advance. 

As  a  general  rule  it  is  not  desirable  to  add  ozone  to  a  dirty  or  turbid 
raw  water.  It  is  better  first  to  clarify  the  water  by  some  method  be- 
fore applying  the  ozone.  The  quantity  of  ozone  required  for  effective 
bacterial  action  depends  upon  the  amount  of  organic  impurities  con- 
tained in  the  water.    Some  German  plants  have  an  average  consumption 


1130 


THE  PUEIFICATIOX  OF  WATER 


of  1.3  g.  of  ozone  per  c.  c,  or  about  10  pounds  per  million  gallons. 
Much  of  the  ozone  is  used  up  by  the  organic  impurities,  and  this  may 
happen  so  rapidly  that  it  will  not  have  a  chance  to  act  upon  the  micro- 
organisms. 

An  impure  water  containing  much  organic  pollution  treated  with 
ozone  may  give  disappointing  results,  from  the  fact  that  unpleasant 
flavors  may  be  developed.  These  are  doubtless  due  to  the  partial  oxida- 
tion of  the  decomposing  organic  matter  with, 
the  production  of  nitrogenous  compounds  not 
well  understood. 

For  the  purification  of  water,  ozone  is  pro- 
duced by  electrical  discharges  in  the  atmosphere, 
and  this  ozonized  air  is  then  brought  into  inti- 
mate contact  with  the  water.  To  produce  the 
ozone  requires  a  silent  biush  discharge  and  the 
air  must  be  cold  'and  free  of  moisture.  If  spark- 
ing occurs  between  terminals,  oxids  of  nitrogen 
are  formed  which  are  corrosive  and  prevent  the 
formation  of  ozone.  The  ozonizing  apparatus 
therefore  must  be  carefully  designed,  and  its 
operation  needs  skilled  supervision. 

An  ozonizer  consists  of  two  conducting  metal- 
lic surfaces  separated  by  a  dielectric,  such  as 
glass  or  mica,  and  so  constructed  that  a  current 
of  air  may  pass  between  the  two  conducting 
surfaces. 

Fig.  120  represents  a  common  form  of  ozon- 
izer. Oxygen  or  air  enters  at  A  and  follows  the 
course  indicated  by  the  arrows.  The  conduct- 
ing surfaces  B  and  C  are  separated  by  a  glass 
dielectric  D.  Wires  leading  from  an  induction 
coil  are  connected  with  B  and  C.  As  the 
oxygen  passes  upward  between  the  conducting  surfaces  it  is  subjected 
to  the  influence  of  the  electric  discharge,  and  a  portion  of  the  element  is 
thereby  changed  into  ozone.  The  air  passing  between  the  electrodes  must 
be  dry,  otherwise  peroxid  of  hydrogen  will  form  at  the  expense  of  the 
ozone.  It  is  therefore  customary  first  to  dry  the  air  by  refrigeration 
or  by  passing  it  over  unslaked  lime  before  it  enters  the  ozonizer.  The 
temperature  of  the  air  in  the  ozonizer  must  not  go  above  a  certain 
degree,  else  ozone  will  not  be  formed.  The  maximum  production  of 
ozone  takes  place  at  about  25°  C.  Overheating  may  be  prevented  by  a 
water  jacket  in  contact  with  the  electrodes.  The  voltage  must  be  high — 
from  8,000  to  20,000  volts;  that  is,  the  current  must  have  a  small 
volume,  but  high  potential.     Ordinarily  only  a  very  small  percentage  of 


Fig.  ]20. — An  Ozonizer. 
A.  Open  tube  through 
which  air  is  led.  B  and 
C  are  electrodes,  sep- 
arated by  the  glass 
tubes  D,  between  which 
the  current  of  air 
passes.  (After  McPher- 
son  and  Henderson's 
"A  Course  in  General 
Chemistry,"  published 
by  Ginn  and  Co.,  Fig. 
13,  p.  31.) 


CHEMICAL  METHODS  OF  PURIFYING  WATER      11  :U 

the  oxygen  is  transformed  into  ozone.  Recently,  however,  Harries  has 
obtained  a  yield  of  from  18  to  19  per  cent,  by  means  of  an  improved 
ozonizer. 

The  molecule  of  ozone  (O3)  readily  gives  up  one  atom  of  this  gas  in  a 
nascent  condition.  It  therefore  has  a  very  strong  oxidizing  action  upon 
organic  matter,  decolorizes  many  pigments,  esp3cially  of  vegetable  origin, 
and  has  a  very  powerful  germicidal  action.  In  this  respect  the  action 
of  ozone  corresponds  chemically  to  potassium  permanganate,  the  hypo- 
chlorites, and  other  powerful  oxidizing  chemicals  used  in  water  puri- 
fication. 


Fig.  121. — An  Ixstallatiox  for  Tkeatixg  Water  with  Ozoxe 
A.  Settling   tank.      B.  Filter.      C.  Storage   reservoir    for    filtered    water.      D. 
Tower,  water  enters  above  and  ozone  below.     E.  Pure  water  reservoir.     F.  Ozon- 
izer.    G.  Drver,  to  remove  moisture  from  air  before  it  passes  into  ozonizer.     H. 
Fan. 


It  is  necessary  to  get  any  excess  of  ozone  out  of  the  water  in  order 
to  avoid  the  corrosion  of  pipes.  This  may  be  done  by  aeration,  by  means 
of  fountains  or  cascades.  On  account  of  the  insolubility  of  the  ozone, 
it  soon  disappears.  The  fact  that  ozone  is  largely  insoluble  in  water 
makes  it  necessary  to  bring  it  into  intimate  contact  with  all  portions  of 
the  water  to  be  treated.  This  is  usually  accomplished  by  allowing  the 
water  to  trickle  downward  through  tall  cylinders  filled  with  coke,  lava, 
or  other  similar  substances  while  the  ozone  is  admitted  to  the  bottom 
of  the  cylinder.  The  water  flows  downward,  the  ozonized  air  works  its 
way  upward,  and  in  that  way  the  desired  contact  is  obtained  between 
the  ozone  and  every  portion  of  the  water. 

A  very  small  amount  of  ozone  is  effective  for  the  purification  of 
water.  It  only  requires  from  1  to  3  milligrams  per  liter.  The  modern 
machines  produce  concentrations  as  high  as  10  grams  and  more  of 
ozone  per  cubic  meter  of  air.     The  ozone  not  taken  up  by  the  water 


1132  THE  PURIFICATION^  OF  WATER 

may  be  used  over  and  over  again.  This  is  accomplished  in  some  of  the 
ozonizing  processes  by  conducting  the  air  that  leaves  the  upper  part  of 
the  water  cylinder  back  to  the  ozonizer. 

In  general,  it  may  be  said  that,  owing  to  the  expense  and  the  elec- 
trical and  engineering  difficulties  involved,  the  ozonizing  process  is 
not  at  present  applicable  to  the  purification  of  water  upon  a  small  scale. 
It  has  been  applied  with  success  upon  a  large  scale  in  a  number  of 
places.  The  first  ozonizing  apparatus  for  the  purification  of  water  on 
a  large  scale  was  installed  by  Siemens-Halske  at  Lille,  France.  Other 
ozonizing  plants  for  purification  of  drinking  water  have  been  installed 
at  Wiesbaden  and  Paderborn  in  Germany;  Cosne,  Chartres,  Mce,  Den- 
ard  in  France;  Ginnekin  in  Holland;  Sulina  on  the  Black  Sea,  and 
Petrograd  in  Russia;  Lindsay,  Ontario;  and  Paris,  in  part,  24,000,000 
gallons  per  day  from  the  River  Marne.  In  France  there  are  '26  large 
municipal  plants  where  ozone  is  used.  At  Lindsay  the  ozone  treatment 
failed  because  the  ozone  and  the  water  were  not  properly  mingled.  At 
Wiesbaden  much  trouble  was  caused  by  the  oxidation  of  the  iron.  Ex- 
periments at  Ogdensburg,  JST.  Y.,  failed  to  remove  the  color  of  the  water. 
Where  water  power  may  be  obtained  for  the  generation  of  the  electricity 
necessary  to  produce  the  ozone  the  cost  is  very  much  lessened.  The 
principal  systems  at  present  used  for  ozonizing  water  are  the  Siemens- 
Halske,  the  Gerhard,  Tindal,  De  Frise,  Otto,  Abraham  Marmier,  Vos- 
maer.  Bridge,  Stynis,  and  others. 

.Ozone  treatment  is  best  adapted  to  sewage-polluted  waters,  the  ap- 
pearance of  which  is  satisfactory.  Waters  of  turbid  streams  are  least 
suited  to  this  treatment.  Ozone  must  now  compete  with  bleaching 
powder,  which  has  nearly  the  same  effect  and  is  cheaper  and  simpler. 
One  objection  to  the  treatment  of  water  by  ozone  is  that  the  electric 
apparatus  is  delicate  and  complicated  and  requires  skilled  attendance. 
The  ozone  processes  are  not  yet  standardized;  at  present  it  is  difficult 
to  determine  what  waters  may  best  be  treated  with  it. 

Chlorinated  Lime — Bleaching  P&wder  or  "Chlorid  of  Lime." — Chlor- 
inated lime,  popularly  miscalled  "chlorid  of  lime,"  and  often  spoken  of 
as  "bleach,''  has  for  years  been  used  to  disinfect  sewage,  outhouses, 
cellars,  and  for  miscellaneous  purposes.  The  first  recorded  use  of  hypo- 
chlorite was  by  Houston  in  1905  at  Lincoln,  England,  where  the  sodium 
salt  was  employed.  Its  use  in  the  disinfection  of  water  as  a  practical 
process  in  the  United  States  dates  from  1908,  when  Mr.  G.  A.  Johnson 
was  called  to  solve  the  serious  and  difficult  problem  in  water  purifica- 
tion at  the  Chicago  stock  yards,  the  discharges  from  which  entered 
Bubbly  Creek.  Filtration  of  the  water  of  Bubbly  Creek  was  not  satis- 
factory, and  all  methods  failed  to  abate  the  nuisance  until  Mr.  Johnson 
treated  the  water  with  chlorinated  lime.  The  method  further  attracted 
widespread  attention  by  the  Jx^rsey  City  Water  Company  in  essaying  to 


OHE^riOAL  METHODS  OF  PTTRTFYTNG  WATER      U?,?, 

com])ly  with  its  conli'iut  to  ruriiisli  puw  wiiU'v  to  Jersey  ('ily  by  simply 
adding  a  little  l)leafliiiig  j)o\V(ler.  Other  municipalities  soon  took  it  up 
in  order  to  render  their  public  water  supply  safe,  until  now  it  is  used  by 
most  cities  and  towns  throughout  the  country. 

Properties. — Chlorinated  lime  is  made  by  saturating  slaked  lime 
with  chlorin  at  ordinary  temperatures.  It  is  a  white  or  whitish  powder 
occurring  also  in  friable  lumps;  dry  or  slightly  damp,  with  a  feeble 
odor  of  chlorin  and  a  disagreeable,  bitter,  and  saline  taste.  It  has  an 
alkaline  reaction,  but  finally  bleaches  litmus  paper.  The  medicinal  dose 
administered  by  the  mouth  is  from  one  to  five  grains  (gram,  0.06 — 0.3). 
As  a  mouth  wash  a  one  per  cent,  solution  may  be  used.  The  physiologi- 
cal action  of  chlorinated  lime  resembles  that  of  chlorin  with  the  super- 
added causticity  derived  from  the  lime  in  its  composition.  Externally 
it  is  an  active  irritant  and  sometimes  moderately  caustic. 

A  6  per  cent,  solution  in  water  may  be  made.  However,  all  the  con- 
stituents of  bleaching  powder  are  not  soluble.  Chlorinated  lime  con- 
tains a  large  amount  of  calcium  hydroxid  (Ca(0H)2)  which  is  largely 
insoluble,  hence  the  milky  appearance  of  the  solution,  and  also  the  pre- 
cipitate known  as  "sludge,"  which  settles  rapidly.  The  calcium  oxy- 
chlorid,  and  also  calcium  hypochlorite,  the  active  principles  in  chlor- 
inated lime,  are  readily  soluble  in  water. 

Upon  exposure  to  the  air  the  hypochlorites  deteriorate  rapidly  to 
the  more  stable  and  inert  carbonates.  Great  care  must  therefore  be 
taken  to  keep  the  substance  in  air-tight  containers  and  to  know  the 
correct  amount  of  available  chlorin  in  each  lot  of  the  bleach  at  the  time 
it  is  used. 

Composition. — The  precise  chemical  constitution  of  chlorinated 
lime  is  not  definitely  known,  although  the  matter  has  been  frequently 
investigated.  It  seems  quite  certain  that  neither  chlorid  of  lime, 
CaCL,  nor  hypochlorite  of  lime,  Ca(0Cl)2,  exists  as  such  in  dry  bleach- 
ing powder,  but  is  formed  on  dissolving  it  in  water.  Calcium  oxy- 
chlorid,  CaOCL,  is  now  generally  accepted  to  be  the  essential  agent  of 
dry  bleaching  powder,  and  calcium  hypochlorite,  Ca(0Cl)2.  to  be  the 
active  germicidal  principle  of  the  solution.     Thus : 

2CaOCl2.         =  Ca(OCl),  +  CaCL 

Calcium  oxychlorid   =    Calcium  hypochlorite    -\-    Calcium  chlorid. 

Calcium  chlorid  which  is  thus  formed,  or  calcium  carbonate,  whieli 
forms  when  bleaching  powder  is  exposed  to  carbon  dioxid,  are  both  inert 
so  far  as  germicidal  value  is  concerned. 

Modes  of  Action. — When  bleaching  powder  is  added  to  water,  the 
reactions  taking  place  are  complex.  The  germicidal  action  is  due  at 
least  to  three  factors:  (1)  the  nascent  oxygen  formed;  (2)  the  free 
and   liberated    chlorin;    and    (3)    chloramins    which    are   formed    from 


1134  THE  PURIFICATION  OF  WATER 

organic   matter   in   the   Avater.      The   hypochlorites    are    themselves    di- 
rectly toxic. 

(1)  Nascent  oxygen  is  a  very  powerful  germicide;  it  is  liberated 
from  the  hypochlorous  acid. 

2CaOClo  becomes  in  water  Ca(OCl).  +  CaCL 

Ca(0Cl)2  +  H3CO3  =  CaCOo  +  2H0C1 

2H0C1  breaks  down  to  2HC1  +  0, 

(2)  Chlorin  is  a  potent  germicide.  There  is  always  some  free 
chlorin  in  bleaching  pov.'der.  Chlorin  is  also  liberated  when  the  hypo- 
chlorous  acid  decomposes,  thns: 

2HC10  =  H2O  +  CL  +  0 

The  intimate  nature  of  the  chemical  processes  is  somewhat  involved, 
but  it  is  plain  that  hypochlorous  acid  and  its  salt,  calcium  hypochlorite, 
both  liberate  free  chlorin,  especially  in  a'cid  solutions. 

That  chlorin  itself  acts  as  a  germicide  in  water  is  evident  from 
the  fact  that  liquid  chlorin  gas  has  about  twice  the  effect  of  the  same 
amount  of  chlorin  in  bleaching  powder.  Further,  water  free  of  organic 
matter  (except  bacteria)  can  be  sterilized  with  minute  amounts  of 
chlorin,  before  this  element  has  combined  chemically  with  HoO. 

(3)  Chloramins.  Hypochlorites  in  contact  with  ammonia  form 
chloramin,  XH2CI.  Hypochlorites  in  contact  with  amino-acids  also 
form  chloramins,  most  of  which  are  germicidal,  some  of  which  have 
extraordinary  potency.  Dakin  and  Cohen  examined  a  number  of  chlor- 
amins, and  found  dichloramin-T  to  be  particularly  active. 

Rideal  added  chlorin  to  water  and  found  that  when  all  the  chlorin 
is  consumed,  there  remains  a  strong  germicidal  action.  It  was  also 
found  that  ammonia  added  to  water  with  bleaching  powder  increases 
the  activity  of  the  hypochlorite.  Dakin  attributed  the  persistent  action 
to  the  formation  of  chloramins,  by  reaction  of  the  hypochlorites  on 
protein  or  amino-acids.  Dakin  and  Dunham  studied  the  disinfection 
of  water  and  found  that  adding  citric,  tartaric,  acetic  and  similar 
organic  acids  increases  the  activity  of  chloramin-T.  The  compounds 
thus  formed  are  unstable  but  benzoic  acid  produces  a  relatively  stable 
compound  with  chloramin-T  which  is  sold  as  Halozone  (p-sulphon-di- 
chloramin-benzoic-acid).  It  destroys  typhoid  bacilli  in  thirty  minutes 
in  dilutions  of  1  part  to  300,000  parts  of  water.  For  further  discus- 
sion of  chloramins,  see  page  1417. 

It  will  thus  be  seen  that  chlorin  itself,  nascent  oxygen  and  also 
chloramins  take  part  in  the  disinfecting  action  of  bleaching  powder. 
The  relative  part  played  will  vary  with  the  amount  of  organic  matter 
contained  in  the  water.  It  is  theorv^tically -conceivable  that  the  liberated 
chlorin   will    directly   kill   a   typhoid   bacillus   by   combining   with    the 


CHEMICAL  METHODS  OF  PURIFYING  WATER      1135 

protein  of  the  germ,  aiul  Uk'  tlilonmiin  tlius  formed  may  kill  another 
ty])hoi(l    haeillus. 

Strength. — Tlic  aiiioimt  of  iiypochlorites  added  is  usually  expressed 
in  terms  of  "availahle  tidoi'in.''  altlioui^h  in  reality  this  represents  the 
available  oxygen  liberated  by  the  ehlorin.  Thus  a  good  bleaching 
powder  will  average  35  per  cent,  of  available  ehlorin,  which  is  the 
equi\aleiit  of  about  7.!)  ])cr  cent,  of  a\ailal)lc  oxygen.  By  available 
ehlorin  is  understood  the  chloi'lii  readily  liberated  from  its  combination 
as  determined  by  the  usual  thiosulphate  titration. 

Hotu  to  Dissolve  Chlorinated  Lime. — Chlorinated  lime  is  soluble 
in  about  twenty  times  its  weight  of  water,  leaving  an  insoluble  residue 
consisting  mostly  of  calcium  hydroxid,  Ca  (011)0.  Half  a  pound  of 
chlorinated  lime  may  be  dissolved  in  a  gallon  of  w-ater.  Such  a  solu- 
tion contains  approximately  6  per  cent,  by  weight  of  chlorinated  lime, 
representing  about  2  per  cent,  of  available  ehlorin. 

To  obtain  a  clear  solution  of  chlorinated  lime  it  is  important  to' 
remember  that  the  available  ehlorin  is  readily  soluble,  even  in  fairly  cold 
water,  and  the  undissolved  sludge  of  calcium  hydroxid,  silica,  etc.,  set- 
tles readily.  Settling,  at.  least,  takes  place  readily  if  a  few  simple  rules 
are  observed.  (1)  Do  not  mix  too  stiff  a  paste,  otherwise  a  gelatinizing 
action  takes  place  and  greater  difficulty  in  settling  is  encountered.  (3) 
Never  mix  a  paste  with  less  than  one-half  a  gallon  of  water  for  one 
pound  of  chlorinated  lime.  (3)  It  is  not  necessary  or  desirable  to 
grind  up  or  break  up  the  lumps  too  thoroughly;  the  available  ehlorin 
nearly  all  dissolves  readily,  and  too  much  agitation  is  detrimental  to 
prompt  settling.  With  these  points  in  view  a  stock  solution  containing 
approximately  2  per  cent,  of  available  ehlorin  may  be  made  as  follows : 

Three  hundred  pounds  commercial  chlorinated  lime  (35  per  cent, 
available  ehlorin)  =  105  pounds  of  available  ehlorin,  assuming  a  recov- 
ery of  100  pounds  of  this  free  from  sludge.  These  100  pounds  must  be 
contained  in  600  gallons  to  give  a  clear  2  per  cent,  solution.  Due  allow- 
ance must  be  made  for  proper  washing  of  the  sludge,  for  it  contains,  in 
addition  to  the  suspended  lime  and  silica,  a  solution  of  equal  strength  to 
that  of  the  clear  liquid.  The  amount  of  sludge  is  equivalent  to  about 
one  gallon  for  each  five  pounds  of  chlorinated  lime  used. 

Method  of  Dosing. — While  the  chlorinated  lime  treatment  of  water 
supplies  is  essentially  simple,  yet  it  requires  able  professional  super- 
vision; disappointing  results  will  come  from  haphazard  work.  The 
great  essential  is  a  uniform  dosing  of  a  standard  solution. 

Economical  working  makes  it  desirable  to  use  two  tanks,  each 
equipped  with  agitators  and  a  looped  chain  as  a  drag  along  the  bottom. 
These  tanks  should  be  made  of  concrete,  or  at  least  lined  wdth  cement, 
and  adjustable  means  provided  for  drawing  off  tlie  clear  liquor  from 
above,  as-  well  as  an  outlet  for  removing  the  sludge  at  the  bottom. 


1136  THE  PURIFICATION  OF  WATER 

Assuming  that  two  700-gallon  tanks  are  provided,  and  that  300 
pounds  of  chlorinated  lime  giving  600  gallons  of  clear  2  per  cent,  solu- 
tion are  to  be  prepared  in  each  tank  at  one  mixing,  the  procedure  should 
be  as  follows : 

Into  tank  No.  1,  which  is  empty,  is  drawn  200  gallons  of  weak 
M'^ash  water  from  tank  No.  2, 

Then  300  pounds  of  chlorinated  lime  is  dumped  into  the  tank  and 
mixed  for  one-half  hour. 

The  tank  is  now  filled  to  a  mark  indicating  660  gallons  with  the 
remaining  wash  water  from  tank  No.  2,  which  does  not  have  to  be 
particularly  clear. 

This  is  now  allowed  to  settle  for  at  least  8  hours  and  preferably 
over  night,  when  600  gallons  of  clear  solution  will  be  ready  to  draw 
off  to  the  stock  tank.  There  will  remain  about  60  gallons  of  sludge  which 
requires  washing  to  obtain  the  remaining  available  chlorin.  The  agi- 
tator is  now  started  in  tank  No.  1,  which  i«  filled  to  the  660-gallon  mark 
with  water,  and  then  allowed  to  settle.  This  wash  w^ater  is  used  in 
making  up  the  next  batch  in  No.  2  tank ;  the  now  practically  exhausted 
lime  sludge  in  tank  No.  1  is  thrown  away. 

The  standard  stock  solution  thus  prepared  will  contain  available 
chlorin  equal  to  %  pound  of  chlorinated  lime  per  gallon,  or  about  2 
per  cent,  available  chlorin,  or  6  per  cent,  of  chlorinated  lime  by  weight. 
Hence  an  average  clear  water  requiring  8  pounds  of  chlorinated  lime 
per  million  gallons  will  require  16  gallons  of  this  standard  solution  per 
million  gallons  of  water.  This  is  a  trifle  less  than  1  drop  of  this  solu- 
tion containing  2  per  cent,  of  available  chlorin  in  a  gallon  of  water. 

The  table  on  the  following  page  covers  the  range  of  chlorinated  lime 
ordinarily  used  in  water  purification,  and  may  be  found  useful  for  com- 
parison. 

Amount  Used  in  Water  Purification. — The  remarkable  germi- 
cidal power  of  chlorinated  lime  is  better  understood  when  it  is  known 
that  3  grains  of  a  practically  harmless  substance  will  kill  myriads  of  bac- 
teria contained  in  a  barrel  of  water.  Ordinarily  the  amounts  used  are 
from  1  to  2,  or  5  parts  in  terms  of  "available  chlorin"  per  million  gal- 
lons of  water.  In  practice  the  actual  amount  used  in  water  purification 
is  from  5  to  12  or  more  pounds  of  bleaching  powder  per  million  gallons 
of  water.  The  bleach  cannot  be  detected  by  the  sense  of  taste  provided 
the  amount  does  not  exceed  25  pounds. 

The  amount  of  chlorinated  lime  necessary  to  add  to  a  water  in  order 
to  accomplish  satisfactory  results  varies  with  the  composition  of  the 
water.  In  general,  the  more  organic  matter  the  water  contains  the 
more  bleaching  powder  is  necessary.  This  is  for  the  reason  that  some 
of  the  bleaching  powder  is  used  to  oxidize  the  organic  matter  before  it 
can  produce  its  germicidal  action.    A  bacterial  reduction  of  99  per  cent. 


CHEMICAL  METHODS  OF  PURIFYING  WATER       1137 


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may  be  obtained  in  a  water  containing  little  organic  matter  with  1  part 
per  million,  whereas  it  requires  up  to  40  parts  per  million  in  sewage  to 
affect  a  similar  bacterial  reduction;  and  still  more  for  feces  in  a  bed 
pan  or  cesspool. 

Xew  York  used  16  pounds  per  million  gallons;  Omaha,  7I/2  pounds 
per  million  gallons  after  coagulation  and.  sedimentation;  Cincinnati, 
5  to  121/^  pounds;  Toronto,  6  pounds;  Montreal,  5  to  7I/2  pounds;  Cleve- 
land,. 16  pounds;  Erie,  7  to  10  pounds;  Milwaukee,  6  pounds;  Pitts- 
burgh, 3  pounds  after  slow  sand  filtration;  Jersey  City,  5  to  8  pounds; 
Council  Bluffs,  15  pounds  following  the  alum  precipitation;  Nashville, 
14  pounds.  Bleaching  powder  was  also  used  to  purify  the  public  water 
supplies  of  St.  Louis,  Minneapolis,  Chicago,  Brainerd,  Minn. ;  Ridg- 
"wood,  X.  J. ;  Corning,  X.  Y. ;  Grand  Rapids,  Mich. ;  Little  Falls,  X.  J. ; 
Harrisburg,  Pa.;  Baltimore,  Md.;  Xiagara  Falls;  Toronto;  Ottumwa, 
la.,  and  many  other  places.  Some  of  these  cities  have  recently  changed 
from  bleaching  powder  to  chlorin  gas. 

Clark  and  Gage  found  that  0.1  part  of  available  chlorin  per  100,000 
effected  a  satisfactory  purification  of  the  Merrimac  River  water;  that  is, 
results  were  obtained  equal  to  slow  sand  filtration.  B.  coli  was  entirely 
eliminated.  They  discovered  the  interesting  fact  that  the  hypochlorite 
is  a  differential  germicide,  that  it  destroj's  some  bacteria  more  readily 
than  other.<.  When  small  quantities  are  employed  certain  species 
growing  at  body  temperature  are  only  slightly  affected.  In  Pittsburgh 
it  was  found  that  0.13  part  of  chlorinated  lime,  measured  in  terms  of 
available  chlorin  per  1,000,000  parts  of  water,  was  sufficient  to  prac- 


1138  THE  PUEIFICATION  OF  WATEE 

tically  sterilize  the  Allegheny  Eiver  water  after  it  had  passed  the  sand 
filters.  It  required  as  much  as  1  part  per  1,000,000  to  accomplish  the 
same  results  in  the  raw  water.  In  Minneapolis  from  2  to  4  parts  per 
1,000,000  have  been  used.  In  the  Jersey  City  case,  already  referred  to, 
5  pounds  of  bleaching  powder,  containing  35  per  cent,  of  available 
chlorin,  are  added  to  each  million  gallons  of  water  treated.  The  raw 
water  in  this  case  is  not  highly  polluted,  ranging  as  low  as  30  bacteria 
per  cubic  centimeter,  and  rarely  going  over  15,000.  The  number  of 
bacteria  in  the  treated  water  averages  only  15  bacteria  per  cubic  centi-' 
meter,  and  B.  coli  is  practically  absent.  It  was  found  only  once  out 
of  455  samples. 

Summary. — The  purification  of  water  by  means  of  a  little  bleaching 
powder  is  cheap,  reliable,  efficient,  harmless,  and  easy  of  application, 
all  of  which  make  it  an  attractive  method.  When  added  in  proper  quan- 
tities it  leaves  no  undesirable  chemical  substance  in  the  water.  It  must, 
.  however,  be  remembered  that  bleaching  powder  in  no  sense  clarifies  a 
water.  In  fact,  turbidity  interferes  with  its  action  to  a  certain  extent. 
It  cannot,  therefore,  render  a  turbid  supply  satisfactory.  Further- 
more, while  chlorinated  lime  in  such  small  quantities  will  kill  bacteria 
it  will  not  purify  organic  matter  nor  cure  discoloration,  nor  take  away 
the  unpleasant  smells  which  raw  waters  often  contain.  It  is,  in  fact, 
least  effective  when  water  is  most  polluted  with  organic  matter.  It  is 
especially  useful  in  a  clean  water;  hence,  turbid  and  polluted  waters 
should  have  a  preliminary  process. 

In  spite  of  the  enormous  improvement  effected  in  the  safety  of 
public  water  supplies  in  this  country  by  chlorination,  the  danger  of 
water-borne  typhoid  is  by  no  means  a  thing  of  the  past.  Epidemics 
are  occurring  from  time  to  time  as  a  result  of  mismanagement,  neglect 
and  other  causes. 

Chlorinated  lime  has  a  slight  tendency  to  add  to  the  hardness,  while 
chlorinated  soda  renders  the  water  correspondingly  soft.  The  latter, 
however,  is  more  expensive  than  the  former. 

Impure  waters  containing  organic  matter  of  any  kind  may,  when 
attacked  by  hypochlorites,  give  rise  to  unpleasant  flavors.  These  sub- 
stances appear  related  to  the  amins,  chloramins,  and  other  compounds 
the  exact  composition  of  which  requires  further  study.  Hence  the 
chemical  sterilization  of  impure  waters  without  subjecting  them  to  some 
preliminary  treatment  may  give  disappointing  results. 

Bleaching  powder  is  also  used  in  the  disinfection  of  the  water  of 
swimming  pools,  for  street  sprinkling,  and  flushing,  for  the  disinfec- 
tion of  feces  and  sputum ;  and  to  a  certain  extent,  for  the  disinfection 
of  glassware,  fabrics,  brushes,  and  combs.  It  is  one  of  the  best  sub- 
stances we  haTe  for  the  general  disinfection  of  rough  places,  such  as 
slaughter-houses,  bakehouses,  dairies,  outhouses,  cellars,  and  the  like. 


CHEMICAL  METHODS  OF  rUBTEYTXCx  WATEE       1130 

In   surgery   tliloi'inalrd    soda,  is   used,   the   action   of   wliidi   is  entirely 
analogons  to  ehlorinated  lime. 

•  The  hypochlorite  treatment  is  also  suitable  for  water  on  a  small 
scale,  as  for  military  use,  camps,  tourists,  explorers,  and  others.  For 
tourists  and  campers  a  solution  may  be  prepared  by  adding  oue-lialf  a 
teaspoonful  of  chlorinated  lime  to  one  pint  of  water.  T^se  one  teaspoon- 
ful  of  this  to  10  gallons;  3(5  drops  to  1  gallon;  or  9  drops  to  1  quart. 
Let  stand  at  least  lo  minutes. 

Tablets  of  ''Hala/.one"  ^  and  other  hypochlorites  have  been  prepared 
for  this  purpose;  they  are  effective  only  when  fresh,  for  they  are 
not  stable, 

Chlorin. — Liquid  chlorin  may  be  used  in  place  of  chlorinated  lime. 
It  is  just  as  efficient  and  acts  in  practically  the  same  manner.  Its  first 
use  for  the  disinfection  of  a  city  wafer  supply  dates  from  December, 
1912,  at  Niagara  Falls,  and  January,  1913,  at  Wilmington,  Delaware; 
by  the  end  of  1918  there  were  about  2,500  liquid  chlorin  municipal 
plants  in  the  United  States. 

Chlorin  gas  is  formed  by  the  electrolytic  decomposition  of  salt  solu- 
tions. The  moist  gas  evolved  from  the  electrolytic  cells  is  dried  and 
then  compressed  into  a  liquid  in  steel  cylinders  of  about  100  pounds 
capacity.  The  gas  is  controlled  and  measured  by  special  apparatus  and 
introduced  into  the  water  (or  sewage)  in  the  proper  proportions  to  etfect 
disinfection. 

There  are  two  general  types  of  apparatus,  one  by  which  the  chlorin 
gas  is  introduced  directly  into  the  water;  this  is  known  as  dry  feed; 
another  by  which  the  gas  is  first  dissolved  in  a  small  quantity  of  water 
and  the  resulting  chlorin  solution  is  piped  to  the  point  of  application — 
u-et  feed. 

The  gaseous  chlorin  process  is  covered  by  general  process  patents 
and  the  mechanical  devices  necessary  for  its  application  are  likewise 
controlled  by  a  few  companies  engaged  in  installing  plants. 

The  action  of  chlorin  gas  in  water  is  just  like  the  action  of  the 
hypochlorites.  The  advantages  of  chlorin  gas  are  such  that  it  is  rapidly 
replacing  bleaching  powder  for  the  purification  of  many  water  supplies. 
The  gas  can  be  obtained  in  a  pure  state,  the  dosage  can  be  accurately 
controlled,  it  does  not  deteriorate  on  keeping,  the  apparatus  is  compact, 
and  the  results  are  uniform.  The  cost  is  about  the  same  as  for  bleaching 
powder. 

The  quantities  added  are  usually  expressed  in  parts  of  chlorin  per 
million  parts  of  water  by  weight;  8.3  pounds  of  chlorin  to  1,000,000 
gallons  of  water  is  the  equivalent  of  one  part  per  million,  since  a 
gallon  of  water  weighs  8,3  pounds.  The  amounts  used  to  disinfect  the 
water  are  the  same  as  stated  under  chlorinated  lime,  and  vary  in  prac- 

'Pakin  and  Dunham,  British  Medical  Journal,  May  26,  1917. 


1140  THE  PUEIFICATTON  OF  WATEE 

tire  from  0.2  to  0.75  part  per  million,  depending  upon  the  amomit 
of  organic  matter  present  in  the  water. 

Good  results  on  the  typhoid  rates  have  followed  the  chlorination  of 
the  water  in  Chicago,  IBaltimore,  Jersey  City,  Milwaukee  and  else- 
where. Chlorination  plants  should  always  be  installed  in  duplicate,  to 
provide  against  accident  or  emergency.  The  use  of  a  polluted  water 
supply  seems  to  give  a  communal  tolerance  or  immunity  not  evidenced 
in  cities  using  a  pure  or  purified  source  of  supply.  Thus,  it  is  often 
noted  that  typhoid  and  diarrheal  outbreaks  are  especially  severe  and 
explosive  in  case  of  a  breakdown  or  failure  of  the  chlorinating  process. 

Chlorin  is  used  to  disinfect  the  water  supply  of  Buffalo,  New  York 
City,  Philadelphia,  Chicago,  Richmond,  Baltimore,  Detroit,  Louisville, 
New  Haven  and  Stamford,  Conn.;  New  Brunswick,  N.  J.,  and  very 
many  other  cities.  It  was  also  used  both  in  the  United  States  and 
abroad  in  many  government  camps,  military  establishments  and  field 
units  during  the  World  War. 

Many  state  boards  of  health  have  provided  traveling  emergency 
chlorin  outfits  for  use  in  epidemics.  Louisiana  was  the  first  state  to 
use  a  railroad  coach  as  a  laboratory  for  water  analysis,  and  garage 
for  housing  machines  used  in  collecting  samples  and  for  fighting  water- 
borne  epidemics.  New  Jersey  uses  a  small  automobile  for  both  purposes, 
Avhile  other  states  merely  keep  hand-operated  chlorin  apparatus  for 
emergency  work.  Uruguay,  because  of  distances,  has  equipped  several 
railroad  coaches  with  emergency  chlorin  outfits. 

Nearly  all  states  have  supervision  not  only  over  the  design,  construc- 
tion and  operation  of  water  systems^,  but  of  sewage  systems  as  well. 

Permanganate  of  Potash.— Permanganate  of  potash  was  much  used 
in  India,  particularly  in  wells  during  cholera  epidemics;  also  in  water 
tanks  on  board  ships,  and  other  places.  Enough  permanganate  is  added 
to  secure  a  faint  pink  tinge,  which  indicates  a  slight  excess.  The  per- 
manganate acts  as  an  oxidizing  agent  precisely  as  ozone,  or  similar  to 
the  hypochlorites.  It  is  a  powerful  germicide,  but  not  sufficiently  so 
in  the  strength  used  to  depend  upon  it.  If  too  much  is  added  to  wells, 
springs,  etc.,  so  as  to  kill  the  fish,  frogs,  and  turtles,  the  water  may 
be  spoiled  by  putrefaction  of  their  dead  bodies.  Like  all  chemical  meth- 
ods, the  action  is  not  continuous;  the  agent  expends  itself  in  oxidizing 
organic  matters  before  attacking  the  bacteria,  and  the  amount  necessary 
for  the  purification  of  a  water  depends,  therefore,  upon  the  amount  of 
organic  impurities  in  the  water. 

Experiments  by  Clark  and  Gage  show  that  complete  sterilization 
is  not  obtained  by  the  use  of  permanganate  of  potash.  Over  98  per 
cent,  of  the  bacteria  were  eliminated  by  treating  water  with  0.5  part 
to  100,000  in  from  4  to  6  hours.  Larger  amounts  of  potassium  per- 
manganate   or   longer   time   gave    no    better    results.      Potassium    per- 


CHEMICAL  METHODS  OF  PURIFYING  WATER       lUl 

manganate  has  a  comparatively  low  efficiency  with  a  relatively  high 
cost,  which  will  always  limit  its  usefulness.  Further,  the  method  is 
difficult  of  practical  application,  being  rather  slow. 

Alum  or  Sulphate  of  Aluminium. — The  single  and  double  sulphates 
of  aluminium  have  long  been  used  to  clarify  turbid  waters.  In  the 
amounts  used  they  have  no  direct  germicidal  action,  nor  any  direct 
chemical  action  upon  the  water  itself.  The  action  is  entirely  an  in- 
direct one,  and  depends  upon  the  fact  that  the  alkaline  carbonates  react 
upon  the  alum  to  form  aluminium  hydrate.  This  salt  has  a  large  col- 
loidal molecule  and,  being  insoluble,  is  thrown  out  of  solution  as  a 
flocculent  precipitate  which  entangles  much  of  the  suspended  matter 
and  bacteria.  In  a  sense  the  purification  of  water  with  alum  corre- 
sponds very  much  to  the  clearing  of  coffee  with  the  white  of  egg.  Some 
of  the  aluminium  hydrate  may  also  combine  directly  with  the  organic 
matter  to  form  undetermined  compounds.     The  reaction  is  as  follows: 

AL(S0J3-1SH,0  +  SCaCOj  +  3H,0  =  .SCaSO,  +  2A1(0H)3  +  3C0j 
666.7  +3x100-1-3x18  =  3x136+     2x78      +3x44 

1  grain  of  alum  per  gallon  =.  142      lbs.  per  million  gallons. 

1       "       "       "        "        "       =     17.1  parts  per  million  parts  of  water. 

300 
17.1   X   TTTTTT^  =  "•"  parts  per  million  of  alkalinity  expressed  as  CaCO,. 

ODD./  ' 

142:100::7.7:x  =  .5.5. 

100  lbs.  of  alum  per  million  gallons  =  5. .5  parts  per  million  of  alkalinity 
as  CaCOj. 

In  water,  however,  the  reaction  is  with  calcium  bicarbonate: 

AL(S0J3-18H,0  +  3Ca(HC03),  =  3CaSO,+2Al(OH)3  +  6C0, 
666.7  +      3  X  262       =3  X  136  +  2  X  1.56    +   6  X  44 

Therefore   1  grain   of   alum  per   gallon   liberates   6.8   parts   per  million   CO,. 
And  1  grain  of  alum   per  gallon   converts   7.7  parts  per  million  bicarbonate 
alkalinity  to  7.7  parts  sulphates  or  incrustants. 

Reactions  using  soda  ash  ^^•ith  alum: 

AKSOJa-lSH^O  +  .SXaX'Oa  +   3n,0  =  3Xa„S0,  +  2A1(0H)3  -f  3C0j 
666.7  3  X  106  =  3  X  142  2  X  78        3  X  44 

318 
1  grain  per  gallon  alum  requires  -^W^  of  17.1  =  8.2  p.  p.  m. 

NajC03  =  68  lbs.  per  m.  g.  XaX'Oj 

132 
1  grain  per  gallon  alum  liberates  -^^^-^r  of  1"-1  ^  3.4  p.  p.  m.  CO; 

Since  1  grain  per  gallon  alum  =  8.2  p.  p.  m.  Xa^COa  and  7.7  p.  p.  m.  of 
alkalinity,  and  1  p.  p.  m.  ^  8.3  lbs.  p.  m.  g.,  then  1  p.  p.  m.  alkalinity  as 

8  2 
NajCOa  =  -^   X   8.3  =  8.8  lbs.  per  m.  g. 

Reaction  using  lime  with  alum: 

AL(;504)3.18H..O  +  3Ca(0H),  =  3CaS0,  +  2AUOH)3 
666.7  leSCaO 

1  grain  per  gallon  alum  requires  -^^^-=  of  17.1  =  4.3  p.  p.  m.  CaO  =  36  lbs. 

per  m.  g.  CaO. 

This  liberates  no  CO^. 

1  grain  per  gallon  alum  with  lime  increases  hardness  7.7  p.  p.  m. 


1142  THE  PURIFICATION  OF  WATEE 

It  will  be  seen  that  if  alum  is  added  in  Just  sufficient  quantities 
to  a  water  it  leaves  no  undesirable  constituent  in  the  water.  This  is 
important,  for  there  is  a  great  prejudice  against  the  addition  of  a  chemi- 
cal, especially  alum,  to  drinking  water.  In  Washington  it  is  actually 
forbidden  by  law,  despite  the  fact  that  it  has  been  shown  that  in  times 
of  great  turbidity  the  only  knowh  method  of  clearing  the  Potomac  water 
is  by  the  use  of  a  coagulant  such  as  alum.  It  has  already  been  pointed 
out  that  there  are  many  such  turbid  waters  in  our  country  which  contain 
silt  in  such  fine  subdivision  that  even  prolonged  sedimentation  and  re- 
peated filtration  will  not  render  them  entirely  clear. 

In  the  use  of  alum  good  results  depend  upon  adding  it  in  just  the 
right  amount.  The  quantity  will  vary  with  the  turbidity  and  the  amount 
of  calcium  carbonate  contained  in  the  water.  The  usual  amount  of  alum 
added  to  water  is  from  1  to  4  grains  per  gallon.  This  should  be  care- 
fully determined  from  time  to  time,  for  if  not  enough  alum  is  added  the 
result  is  incomplete,  and  if  too  much  is  added  it  remains  in  the  water 
as  such.  The  process  therefore  needs  constant  supervision,  for  turbid 
waters  usually  come  from  turbulent  streams,  which  are  subject  to  sudden 
variations.  If  the  process  is  left  to  automatic  devices  or  placed  in  in- 
competent hands  it  is  sure  to  give  disappointing  results. 

Few  waters  may  be  satisfactorily  purified  by  alum  alone.  Alum 
should  be  regarded  as  only  one  part  of  the  process.  Subsequent  sedi- 
mentation, filtration,  or  hypochlorite,  etc.,  is  necessary,  depending  upon 
circumstances.  Alum  alone  should  never  be  depended  upon  to  purify  a 
sewage-polluted  water.  Properly  combined  with  filtration,  alum  will 
eliminate  a  large  percentage  of  the  bacteria.  See  Mechanical  Filtration, 
page  1122. 

Most  plants  have  been  dependent  upon  the  open  market  for  alum. 
Hoover  of  Columbus  devised  in  1916  a  practical  method  for  makmg 
alum  at  the  plant.  Two  parts  of  commercial  sulphuric  acid  are  mixed 
with  one  part  of  low  grade  bauxite  ore  and  poured  into  flat  boxes.  In  a 
few  hours  alum  cake  has  formed  in  the  pans,  and  is  used  without  further 
treatment.  The  product  has  greater  coagulating  power,  and  is  con- 
siderably cheaper  than  commercial  aluminium  sulphate. 

Sulphate  of  Iron  and  lime. — This  combination  is  used  in  many 
places.  At  St.  Louis  it  was  introduced  as  an  emergency  installation  to 
clarify  the  muddy  waters  of  the  Mississippi,  to  make  a  good  impression 
during  the  Louisiana  Purchase  Exposition  in  1904.  It  gave  such  satis- 
factory results  that  it  was  decided  to  continue  its  use. 
Reaction  using  lime  and  iron   (ferrous  sulphate)  : 

FeSO^JH.O  +  Ca(HC03)2  =  FelHCO,),  +  CaSO,  +  7H,0 

278  lOOCaCOs  178  136 

Fe(HC03)2  +  2Ca(OH)3  =  Fe(OH)„  +   2CaC0,   +   2H,0 

178  112CaO  89.9     "        2  X  100 

2Fe{0H),  +  O  -I-  H,0  =  2Fe(0H), 

2  X  89.9         16         18         2  X  106.9' 


CHEMICAL  METHODS  OF  PURIFYING  WATER       1143 

1   {^liiiii   \wr  fiiilloii   FeS0,.7llj<)  ^=  17.1  X    »^q  =  •*•-  P-  P-  Qi-  alkalinity  and 

100  lbs.  per  ni.  g.  =i  4.5  p.  p.  m.  alkalinity. 

1  grain   per  gallon   FeSOi  oonvorta  (5.2   p.    p.   ni.    alkalinity   ti)  G.2   p.   p.   ni. 

incrustanta. 

112 
To   precipitate   the   ferrous   bicarbonate   first    formed   requires    17.1    X    -5=^ 

=  6.9  p.  p.  m.  CaO  ^=  57  lbs.  per  m.  g.  for  each  grain  per  gallon  FeSO<. 

The  dissolved  oxygen  in  the  water  completes  the  reaction,  forming  brown 
Fe(0H)3. 

Lime  and  iron  are  cheaper  than  sulphate  of  aluminium.  Their 
application  is  much  more  difficult  to  control  adequately,  and  it  should 
never  be  undertaken  except  with  the  assistance  of  a  competent  resident 
chemist  and  good  appliances  for  adding  the  lime  in  any  quantity  that 
may  be  required  by  the  composition  of  the  Avater.  At  St.  Louis  the 
water  is  subject  to  the  iron  and  lime  treatment,^  followed  by  subsidence 
in  large  basins  in  which  the  bulk  of  the  precipitate  settles.  This  clari- 
fied water  is  then  chlorinated.    New  Orleans  uses  a  similar  method. 

Metallic  Iron:  the  Anderson  Process. — The  Anderson  process  (pat- 
ented) for  the  purification  of  water  consists  in  agitating  the  water  in 
contact  with  metallic  iron,  a  portion  of  whicli  is  taken  into  solution  as 
ferrous  carbonate.  This  action  is  brought  about  by  the  CO^  in  the  water 
which  attacks  the  iron.  Upon  subsequent  aeration  the  ferrous  car- 
bonate is  oxidized  and  precipitated  out  as  the  insoluble  ferric  hydrate, 
which  accomplishes  all  the  good  and  none  of  the  bad  effects  which  fol- 
low the  use  of  alum.  The  precipitate  is  partially  removed  by  sedi- 
mentation, or  filtration  may  complete  the  process.  The  process  is  used 
on  a  large  scale  at  Antwerp,  Belgium,  where  the  water  passes  through 
long  revolving  cylinders  containing  baffle  plates  and  loose  pieces  of 
metallic  iron.  As  the  cylinders  revolve  the  iron  is  continually  carried 
up  and  dropped  through  the  water  in  a  constant  shower.  The  water 
passes  slowly  from  one  end  of  the  cylinder  to  the  other. 

The  process  theoretically  is  an  excellent  one,  but  apparently  enough 
iron  is  not  always  obtained  in  solution  to  accomplish  the  results  when 
applied  on  a  large  scale.  Especially  when  peaty  waters  are  used,  it  seems 
impossible  to  get  enough  iron  into  solution  in  the  time  which  can  be 
allowed;  or  the  inorganic  acids  may  form  soluble  compounds  with  the 
iron,  thus  defeating  the  object  of  the  process.  Other  places  where 
the  Anderson  process  is  used  are  Dortrecht,  Holland,  Boulogne-sur-Seine, 
near  Paris,  and  elsewhere. 

Copper  Sulphate. — The  use  of  copper  sulphate  in  drinking  waters  was 
proposed  by  George  T.  Moore  of  the  United  States  Department  of  Agri- 
culture in  1904.  The  original  claim  was  that  copper  sulphate  in  minute 
amounts  would  poison  algae  which  produced  objectionable  tastes  and 
odors,  and  the  further  claim  was  made  that  it  was  also   capable  of 

"There  are  2.1.3  grains  of  iron  sulphate  per  gallon  and  7.39  grains  of  lime 
per  gallon. 


1144  THE  PURIFICATION  OE  WATER 

destroying  typhoid  and  other  pathogenic  microorganisms.  We  know 
now  that  copper  sulphate  in  great  dilution  is  a  specific  poison  for  many 
algae  and  other  microscopic  organisms,  but  that  it  has  little  or  no 
effect  upon  typhoid,  cholera,  or  dysentery  bacilli  in  the  amounts  used. 

Copper  sulphate  is  used  in  the  proportion  of  0.1  to  0.25  part  per 
1,000,000  parts  of  water.  Some  algae  require  larger  doses.  Most  of 
the  copper  combines  with  the  bodies  of  the  microorganisms  and  settles 
with  them  to  the  bottom  and  in  this  way  is  removed  from  the  water. 
If  the  water  is  afterwards  filtered  most  of  the  remaining  copper  is  re- 
moved. The  copper  remaining  in  the  water  is  in  such  minute  amounts 
that  there  seems  to  be  no  real  danger  in  using  it  in  this  way  or  even 
in  its  occasional  use  in  somewhat  larger  doses  where  the  water  is 
very  bad. 

The  method  of  applying  the  copper  is  to  place  weighed  ^quantities 
of  the  copper  sulphate  in  loose  cloth  bags  and  to  tow  them  back  and 
forth  with  rowboats  through  the  water  of  the  reservoir  until  the  material 
is  dissolved.  It  should  be  remembered  that,  while  the  copper  kills 
some  species  of  organisms  in  the  amounts  used,  it  has  no  effect  what- 
ever upon  others.  Thus,  Fort  Worth  recently  found  that  no  aeration  in 
addition  to  copper  sulphate  was  necessary  to  eliminate  algae  from  the 
source  of  supply.  In  fact,  it  permits  the  growth  of  certain  species  by 
removing  the  retarding  symbionts,  thus  clearing  the  way  for  stronger 
growths  of  the  forms  that  are  not  directly  affected.  Copper  sulphate 
may  therefore  entirely  change  the  flora  in  a  reservoir.  This  change 
is  frequently  accompanied  by  a  great  improvement  in  odors  and  tastes. 
On  the  other  hand,  the  destruction  or  suppression  of  one  species  may 
be  followed  by  an  overgrowth  of  an  equally  objectionable  and  more 
hardy  form.  Therefore  the  results  from  the  use  of  copper  sulphate 
for  the  correction  of  odors  and  tastes  in  water  vary  from  complete  suc- 
cesses to  utter  failure. 

It  is  clearly  established  that  copper  sulphate  does  not  prevent  or 
even  materially  reduce  putrefaction  and  the  tastes  and  odors  resulting 
from  it.  According  to  Hazen,  the  method  of  treating  water  with 
copper  sulphate  is  easily  and  quickly  applied,  and  considerable  good 
has  come  from  it.  The  correction  is  only  partial,  however,  and  is  not 
always  permanent.    It  is  not  therefore  to  be  relied  upon  in  all  cases. 


ULTRAVIOLET  RAYS ' 

Recently  the  well-known  germicidal  power  of  the  ultraviolet  rays 
has  been  put  to  practical  use  in  the  sterilization  of  water  and  other 
substances.     These  rays,  of  short  wave  length,  may  be  obtained  from 

'  See  also  page  1375. 


ULTRAVIOLET  RAYS  1145 

the  Cooper-Hewitt  niorciiry  vapor  lani|).  wliicli  is  very  rich  in  ultra- 
violet rays/  Nagicr  conceived  the  idea  that  this  hunp  ini<^ht  he  used 
for  tlie  .sterilization  of  water,  and  the  experiments  made  in  France, 
England,  and  elsewhere  show  (his  assiini})tion  to  he  correct.  As  glass 
is  opaque  to  ultraviolet  rays,  it  is  necessary  to  use  quartz  or  lamps 
made  of  fused  silica.  The  apparatus  used  in  the  experiments  of  Thresh 
and  Reallc  consists  of  an  aluminium  cylinder  ahoiit  I'i  inches  lon.ir  hv  'i 
inches  in  diameter  containing  a  Cooper-Hewitt  quartz  lamp  with  an  in- 
ternal diaphragm,  which  causes  the  water  entering  at  one  end  to  travel 
along  the  cylinder  in  close  proximity  to  the  lamp.  By  an  ingenious  ar- 
rangement the  moment  the  light  goes  out  the  flow  of  water  is  stopped. 
This  small  apparatus  is  capable  of  sterilizing  50  to  200  gallons  of  water 
per  hour,  depending  upon  the  character  of  the  water.  In  clear  water 
many  of  the  bacteria  are  killed  in  from  5  to  20  seconds.  The  resisting 
spores  succumb  in  from  30  to  60  seconds,  B.  coli  in  from  15  to  20  seconds, 
B.  ij/phosus  from  10  to  20  seconds,  cholera  vibrio  10  to  15  seconds.  The 
presence  of  colloidal  material  or  turbidity  retards  the  actions  of  the  rays. 
The  current  used  in  these  experiments  waa  6  amperes  and  130  volts. 
The  results  show^  that  a  fairly  clear  and  bright  water  may  be  practically 
sterilized  by  exposure  to  ultraviolet  rays  for  a  brief  time.  The  sim- 
plicity of  the  apparatus  and  its  comparative  cheapness  make  it  attractive, 
so  that  it  doubtless  will  receive  much  attention  in  the  future. 

Installations  may  now  be  had  for  houses,  hotels,  swdmming  pools, 
steamships,  etc. 

Marseilles  adopted  the  ultraviolet  rays  to  purify  its  water  supply. 
There  are  preliminary  roughing  filters,  and  the  water  passes  the  quartz 
tube  mercury  arc  lamp  three  times.  No  B.  coli  were  found  in  the  treated 
water,  and  the  total  bacterial  reduction  was  98.3  per  cent.,  and  more 
recently  a  plant  was  installed  at  Henderson,  Kentucky,  which  sterilizes 
water  previously  passed  through  a  rapid  sand  filter.  Good  bacterial 
results  are  obtained. 

The  bacteria  are  killed  by  exposure  to  the  direct  action  of  the  ultra- 
violet rays  themselves. 

The  action  is  not  influenced  by  temperature  (0°-55°  C.)  and  oxygen 
content  of  the  water.  The  formation  of  H^O,  is  not  necessary  to  pro- 
duce sterilization.  The  process  does  not  in  any  way  clarify  the 
water. 

In  191.")  there  were  320  plants  in  the  United  States,  comprising  20 
for  swimming  pools.  I^ltraviolet  rays  should  preferably  be  applied  to 
water  free  of  turbidity  or  filtered.  Overdosing  gives  no  detrimental 
eifeets  other  than  increased  cost.  1'he  water  is  not  changed  in  any 
way  chemically.     Turluditv  of  the  water  or  acenmulation  on  the  lamps 

'Recent  literature  is  abstracted  in  the  U.  S.  Public  Health  Reports,  December 
12,  1919,  p.  2821. 


1146  THE  PURIFICATION  OF  WATER 

greatly  impairs  the  efficiency  of  the  rays.  Direct  current  is  now  used 
at  110  to  500  volts.  A  continuous  good  effluent  requires  constant 
voltage  and  that  the  lamp  be  in  good  condition.  The  ultraviolet  ray 
treatment  of  water  can  be  made  satisfactory  and  reliable  (page  1375). 


CHAPTER   VI 
WATER  AND  ITS  RELATION  TO  DISEASE 

Water  is  a  vehicle  for  certain  infections  such  as  cliolera,  typhoid 
fever,  dysentery,  and  other  diseases,  having  their  primary  seat  in  the 
digestive  tract.  It  may  carry  inorganic  poisons  such  as  lead.  It  is 
responsible  for  a  large  group  of  nutritional  and  dietetic  disorders  less 
well  understood.  It  may  contain  qualities  which  bring  about  derange- 
ments of  metabolism  resulting  in  such  conditions  as  goiter;  further,  it 
may  be  the  medium  for  carrying  infections  now  not  generally  regarded 
as  water-borne,  or  it  may  lower  resistance  so  as  to  favor  infections  not 
water-borne.  It  is  also  occasionally  responsible  for  conveying  animal 
parasites,  amebae,  worms,  etc. 

While  Mater  has  an  established  place  among  the  carriers  of  certain 
infections,  it  has  not  a  supreme  or  exclusive  place,  and  this  should  be 
kept  carefully  before  us.  The  tendency  to  exaggerate  the  importance 
of  water  as  a  bearer  of  disease  and  death  has  sometimes  led  to  over- 
statement. The  facts  are  bad  enough  and  do  not  require  extravagant 
language  to  emphasize  their  importance.  The  greatest  danger  in  water 
is  pollution  from  human  sources.  All  the  discharges  from  the  body: 
urine,  feces,  expectoration,  secretions  from  the  nose,  and  washings  from 
the  skin,  find  their  way  sooner  or  later  into  our  streams,  especially 
where  modern  water-carriage  systems  are  installed  for  the  disposal  of 
wastes.  All  sewage-polluted  water  must  be  regarded  as  dangerous, 
whether  there  are  any  known  cases  of  typhoid  fever  on  the  water- 
shed or  not.  It  is  highly  probable  that  the  sewage  of  large  communities 
always  contains  typhoid  bacilli  in  larger  or  smaller  numbers,  because 
in  large  communities  typhoid  fever  does  not  die  out  completely  at  any 
time,  and  carriers  and  missed  cases  are  growing  in  interest  and  im- 
portance. 

Water  differs  in  several  essential  particulars  from  anj  other  ar-ticle  of 
diet.  Above  all,  it  is  partaken  of  raw,  while  perhaps  90  per  cent,  of  all 
our  other  food  is  disinfected  by  cooking  before  it  is  used.  Again,  it 
is  a  vehicle  which  comes  in  contact  with  many  objects  spread  over  broad 
acres,  and  it  is  the  natural  vehicle  for  the  removal  of  wastes  from  these 
areas.    Its  great  solvent  and  erosive  powers  favor  this  action. 

The  relation  of  water  supply  to  sickness  and  death  has  been  shown 
with  force  in  many  cities,  notably  at  Lowell  and  Lawrence,  Mass.;  in 

1147 


1148  WATER  AND  ITS  PtELATION  TO  DISEASE 

Albany,  IST.  Y. ;  at  Jersey  City  and  Newark,  X.  J.;  at  Pliiladelphia  and 
Pittsburgh,  Pa.;  at  Chicago,  111.;  and  abroad  at  London,  Paris,  Ham- 
burg, Altona,  Berlin,  and  many  other  cities. 


THE  MILLS-REINCKE  PHENOMENON 

Following  the  filtration  of  the  water  supply  at  Lawrence,  Mass.,  in 
September,  1893,  Mr.  Hiram  F.  Mills,  a  member  of  the  State  Board 
of  Health  of  Massachusetts,  noted  that  a  marked  decrease  in  the  general 
death  rate  of  the  city,  and  not  merely  in  the  death  rate  from  typhoid 
fever,  was  taking  place.  About  the  same  time  (May,  1893)  filtered  Elbe 
Eiver  water  was  furnished  the  city  of  Hamburg,  and  Dr.  J.  J.  Eeincke, 
health  officer  of  that  city,  in  his  successive  annual  reports,  noticed  that 
the  general  death  rate  was  declining  more  rapidly  than  could  possibly  be 
accounted  for  by  the  deaths  from  typhoid  fever  alone.  To  this  phenome- 
non Sedgwdck  and  MacKutt  have  given  the  name  of  the  "Mills-Eeincke 
phenomenon."  ^  In  1904  Mr.  Allen  Hazen,  a  sanitary  engineer,  formu- 
lated a  numerical  expression  for  the  comparative  effect  of  water  purifica- 
tion upon  typhoid  fever  mortality  and  total  mortality.  He  said  that, 
"where  one  death  from  typhoid  fever  has  been  avoided  by  the  use  of  a 
better  water,  a  certain  number  of  deaths,  probably  two  or  three,  from 
other  causes  have  been  avoided."  Sedgwick  and  MacXutt  examined  the 
vital  statistics  of  the  cities  of  Lawrence,  Mass.,  and  Hamburg,  Germany, 
and  also  of  Lowell.  Mass.,  Albany,  Binghamton,  and  Waterto'um,  X.  Y. 
They  foimd  evidence  of  the  great  life-saving  power  of  a  purified  water  in 
preventing  many  diseases  other  than  typhoid  fever  in  the  cities  studied, 
except  AVatertown,  and  in  this  case  it  is  possible  that  the  purification  of 
the  public  water  supply  has  been  as  yet  relatively  imperfect.  It  is 
further  to  be  noted  that  the  method  of  purification  used  at  Watertown 
is  mechanical  filtration. 

One  of  the  most  surprising  results  of  these  studies  is  the  disclosure 
of  the  remarkable  relation  existing  between  polluted  water  and  infant 
mortality.  This  was  emphasized  especially  by  Dr.  Eeincke  at  Hamburg. 
Closely  associated  with  infant  mortality  stand  diarrhea  and  gastro- 
intestinal disorders  in  relation  to  polluted  water. 

McLaughlin  ^  has  also  noted  the  relation  of  a  sewage-polluted  water 
to  infant  mortality,  and  concludes  that  it  is  certain  that  in  practically 
every  instance,  in  addition  to  a  lessened  number  of  deaths  from  typhoid 
fever,  the  substitution  of  a  safe  for  a  polluted  water  supply  results  in 

^  W.  T.  Sedgwick  and  J.  S.  MacNutt :  "The  Mills-Reincke  Phenomenon  and 
ITazen's  Theorem  Concerning  the  Decrease  of  Mortality  from  Diseases  Other 
Than  Typhoid  Fever  Following  the  Purification  of  Public  Water  Supplies,"  Jour. 
Infect.  Dis.,  Vol.  VII,  No.  4,  Aug.  24,  1910,  pp.  489-564. 

'Public  Health  Reports,  Vol.  XXVII,  No.  17,  April  26,  1912. 


NON-SPECIFIC  DISEASES  DUE  TO  WATEK  111!) 

the  saving  of  many  lives  from  diseases  which  are  not  reported  as  typhoid 
fever.  Hazen's  theorem  has  also  been  studied  by  Arthur  Lederer,''  who 
finds  a  large  number  of  atiirmative  statistical  results. 

More  recent  evidence  from  Providence,  Cincinnati,  Columbus,  Pitts- 
burgh, and  Philadelphia  does  not  tend  to  bear  out  the  Mills-Reincke 
theory,  except  perhaps  in  regard  to  diarrheal  diseases  in  Pittsburgh. 
The  proposition  is  not  demonstrated  and  it  would  be  exceedingly  unwise 
to  promise  a  marked  lowering  of  the  general  death  rate  as  a  result  of 
the  purification  of  water  supplies  alone. 


NON-SPECIFIC  DISEASES  DUE  TO  WATER 

Impure  Avater  is  responsible  for  disorders  other  than  the  specific  gas- 
tro-intestinal  infections,  but  these  disorders  are  often  obscure  or  over- 
looked. It  is  not  always  plain  just  what  quality  or  what  impurity  in 
the  water  is  responsible  for  these  non-specific  disorders,  and  the  dis- 
eases themselves  may  present  a  vague  and  ill-defined,  clinical  picture. 
The  relationship  has  been  worked  out  in  only  a  few  instances. 

A  turbid  or  malodorous  water  may  not  in  itself  be  particularly  in- 
jurious to  health,  but,  on  account  of  its  unattractive  appearance  or  repul- 
sive condition,  less  may  be  taken  than  is  necessary  for  the  maintenance 
of  good  health.  In  this  way  water  may  be  indirectly  responsible  for 
much  harm.  The  drinking  of  too  little  water  is  a  very  common  dietetic 
error. 

While  a  polluted  water  may  not  carry  specific  germs,  it  may  so 
undermine  health  or  lower  resistance  as  to  favor  infections  not  usually 
associated  with  the  digestive  tract,  such  as  pneumonia  and  tuberculosis 
and  the  diseases  responsible  for  infant  mortality. 

From  the  nature  of  the  case  the  effects  of  an  impure  water  cannot 
always  be  measured  by  gross  results,  hut  the  cumulative  or  separate  ac- 
tion of  small  effects  often  repeated  may  result  in  deranged  digestion, 
altered  metabolism,  irritation  of  delicate  membranes  or  sensitive  or- 
gans and  structures,  which  may  lead  to  or  hasten  the  course  of  chronic 
diseases. 

The  organic  matter  in  the  quantities  usually  contained  in  a  natural 
water  is  not  of  itself  harmful.  This  organic  matter,  however,  does  not 
stay  in  its  native  state,  but  soon  putrefies,  and  it  is  suspected  that  some 
of  the  intermediate  products  of  putrefaction  may  have  toxic  potenc5^ 
Ordinarily  these  toxic  substances  are  in  minute  quantities,  or  at  least 
in  great  dilution,  but  under  certain  circumstances  they  may  accumulate 
in  noticeable  concentration.  Further,  while  persons  habitually  taking 
such  toxic  substances  may  soon  become  immune,  the  new-comer  will  not 

'Arthur  Lederer:     Amer.  Journal  Public  Hygiene,  June,  1910,  p.  304. 


1150  WATER  AND  ITS  RELATION  TO  DISEASE 

be  so  fortunate.  The  case  of  organic  matter  in  water  is  not  a  clear  one, 
and  sanitarians  have  ever  erred  on  the  safe  side  in  condemning  waters 
containing  much  organic  matter.  It  is  well  known  that  if  the  organic 
matter  is  not  derived  from  sewage  it  is  probably  harmless.  Thus,  in  the 
case  of  organic  matter  of  vegetable  origin,  Mason  has  been  able  to  find 
but  few  cases  of  illness  traceable  to  peaty  waters.  In  such  instances  the 
patients  suffered  from  a  mild  and  transient  form  of  diarrhea.  I  am 
familiar  with  an  outbreak  of  diarrhea  traced  to  a  dead  fish  caught  in 
the  water  meter  of  a  hospital.  This  is  probably  a  type  of  water-borne 
disease  due  to  organic  pollution  which  is  not  infrequent.  Whether  in 
such  cases  the  trouble  is  due  to  bacteria  or  to  bacterial  toxins,  or  to 
the  degradation  products  of  protein  decomposition,  cannot  always  be 
made  out. 

As  far  as  the  inorganic  impurities  usually  found  in  water  are  con- 
cerned, the  chlorids,  carbonates,  sulphates,  and  silicates,  and  lime,  mag- 
nesia, and  aluminium  can  scarcely  be  harmful  in  the  amounts  ordinarily 
found.  It  is  commonly  stated  thai:  water  containing  500  parts  per 
million,  or  30  grains  per  gallon,  of  clay  and  silt  is  unfit  for  drinking 
purposes,  on  account  of  its  irritating  effects  upon  the  gastro-intestinal 
tract;  but  beyond  this  probability,  turbidity  is  of  no  special  sanitary 
significance,  unless  the  water  also  contains  metallic  poisons  or  objection- 
able chemicals. 

An  attempt  has  frequently  been  made  to  correlate  the  formation  of 
concretions  such  as  urinary  and  biliary  calculi  with  the  inorganic  salts 
in  water.  We  now  know  that  biliary  calculi  usually  form  about  a  colon 
bacillus  or  a  typhoid  bacillus  or  about  some  pathological  particle  as  a 
nucleus,  and  that  urinary  calculi  probably  have  a  similar  pathogenesis. 
There  is  no  known  relation  between  these  concretions  in  the  body  and 
the  inorganic  salts  in  water,  even  those  in  a  very  hard  water.  It  is  stated 
that  a  change  from  a  soft  to  a  hard  water  causes  diarrhea.  The  relation 
of  inorganic  substances  in  water  to  goiter  will  be  discussed  separately. 


GOITER 

Goiter  (from  guttur,  throat)  is  a  chronic  enlargement  of  the  thyroid 
gland,  and  may  be  due  to  a  variety  of  causes. 

The  functions  of  the  thyroid  gland  are  due  to  its  internal  secretion, 
which  contains  iodin.  The  secretion  of  the  thyroid  acts  as  an  excitant 
(hormone)  of  the  metabolic  rate  of  the  body;  through  its  action  on 
other  endocrine  glands,  it  influences  reproductive  and  digestive  func- 
tions; and  exerts  some  control  on  the  functions  of  other  organs.  One 
of  the  chief  functions  of  the  thyroid  is  to  stimulate  and  maintain  the 
energy  utilization  of  the  body  at  a  normal  level,  in  other  words  to  regu- 


GOITEK  1151 

late  metal)()lisin.  llvpcrsecrction  raises  tlie  rate  of  inetal)olism  of  all 
foodstuffs,  so  that  protein,  carbohydrates  and  fats  are  consumed  at  an 
increased  rate.  The  thyroid  also  exerts  some  control  of  the  glycogenic 
content  of  the  liver,  for  in  hyperthyroidism  the  liver  is  not  capable 
of  the  normal  storing  of  glycogen  although  the  body  is  still  able  to 
metabolize  carbohydrates  in  usual  amounts.  In  deficient  secretion  (hy- 
posecretion)  there  is  a  diminished  and  retarded  growth  of  tissues  and  a 
lowered  metabolism. 

The  thyroid  has  some  relationship  with  the  sex  organs,*  especially  in 
the  female,  the  nature  of  wliicli  is  at  present  but  poorly  understood. 
There  often  is  increase  of  size  of  the  thyroid  at  puberty  or  during  men- 
struation, pregnancy  and  lactation.  There  is  also  some  evidence  that 
it  has  a  detoxicating  action  on  certain  poisonous  substances,  but  our 
knowledge  here  is  meager. 

There  are  three  diseases  due  to  disturbed  function,  of  the  thyroid 
gland:  (1)  liypoihyroidism,  associated  with  atrophy  of  the  gland  and 
diminished  functional  activity;  (2)  Uyperthyroidism,  associated  with 
enlargement  of  the  gland  and  increased  functional  activity;  (3)  simple 
goiter,  probably  compensatory,  associated  with  enlargement  of  the  gland, 
but  little  or  no  constitutional  manifestations. 

Hypothyroidism,  or  cretinism,  occurs  congenitally  or  develops  in 
early  years  of  childhood,  and  is  characterized  by  imperfect  development 
of  mind  and  body.  Myxedema  occurs  mostly  in  women  between  the  ages 
of  30  and  50  years.  It  is  characterized  by  loss  of  expression  and 
memory,  thickening  of  the  skin,  and  subsequent  infiltration  with  a 
peculiar  mucoid  edema. 

Hyperthyroidism,  or  exophthalmic  goiter  (also  known  as  Graves', 
Basedow's  or  Parry's  disease),  is  an  enlargement  of  the  thyroid  gland 
with  increased  functional  activity.  The  chief  symptoms  are  tachycardia, 
exophthalmos,  goiter  and  tremor. 

ENDEMIC  OR  SIMPLE  GOITER 

Simple  goiter  is  of  special  interest  to  the  sanitarian  because  it  is 
frequent,  widespread  and  readily  preventable,  even  curable  if  not  too 
far  advanced.  Simple  goiter  is  a  deficiency  disease,  due  to  lack  of  iodin 
in  water,  food,  or  both. 

Simple  goiter  includes  all  cases  of  enlargement  of  the  thyroid,  except 
toxic  goiter,  exophthalmic  goiter,  thyroiditis,  and  true  neoplasms  of  the 
thyroid.  Simple  goiter  embraces  types  formerly  called  endemic,  epi- 
demic and  sporadic  goiter;  adolescent  goiter  and  goiter  of  pregnancy; 
also  non-toxic,  parenchymatous  goiter,  colloidal  goiter,  and  cystic  goiter. 
It  is  also  called  struma  or  bronchocele. 

*  In  the  king  scorpion  the  thyroid  is  a  reproductive  gland. 


1152  WATER  AND  ITS  EELATION  TO  DISEASE 

Simple  goiter  is  a  deficiency  disease  characterized  by  a  non-inflamma- 
tory enlargement  of  the  thyroid  gland,  ^vithout  marked  functional  dis- 
turbances. The  goiter  is  a  matter  of  concern  to  the  patient,  because  (1) 
it  is  disfiguring;^  (2)  it  may  cause  pressure  symptoms  on  the  trachea 
or  surrounding  structures;  (3)  it  may  be  responsible  for  constitutional 
disturbances  such  as  apathy,  chilliness,  constipation,  asthenia  and  mental 
apprehension. 

Simple  goiter  is  rarely  congenital.  It  usually  starts  at  or  about 
puberty,  and  the  tendency  diminishes  after  the  twentieth  year.  Women 
are  more  susceptible  than  men,  in  the  proportion  of  six  or  eight  to  one. 
This  sex  predisposition  probably  finds  its  explanation  in  the  fact  that 
the  thyroid  gland  is  associated  with  the  physiologic  processes  of  the 
female,  particularly  with  the  female  generative  functions.  It  is  usually 
endemic,  but  sometimes  occurs  sporadically.  Epidemics  have  Jbeen  noted, 
but  usually  in  endemic  localities. 

Prevalence. — The  classic  home  of  simple  or  endemic  goiter  is  in  the 
Swiss  Alps.  In  certain  regions  of  these  mountains  it  is  very  prevalent. 
Thus,  in  Piedmont  it  sometimes  affects  more  than  two  out  of  every 
three  of  the  inhabitants.  It  also  occurs  in  the  mountains  of  Austria, 
France,  and  Germany,  and  there  are  a  few  endemic  centers  in  Norway, 
Sweden,  Finland,  and  the  Baltic  provinces.  The  traditional  seat  of 
goiter  in  England  is  in  Derbyshire  ("Derbyshire  neck"),  while  Sussex 
and  Hampshire  have  also  been  affected.  There  are  many  endemic  centers 
in  the  mountains  of  Asia,  Japan,  the  Asiatic  Islands,  Africa,  Mexico, 
and  South  America.  The  early  explorers  found  it  among  the  North 
American  Indians,  as  Munsen  has  in  more  recent  times  in  the  Eskimos. 
The  region  of  our  Great  Lakes  shows  considerable  numbers;  also  in 
sections  of  West  Virginia,  but  in  the  United  States  and  Canada  the 
goiters  are  not  large  and  cretinism  is  rare. 

Marine  and  Kimball  ®  in  April,  1917,  examined  3,872  school  girls 
in  the  second  decade  of  life,  in  the  city  of  Akron,  Ohio.  Of  this  num- 
ber, 2,184,  or  57  per  cent.,  were  found  to  present  simple  goiter.  The 
frequency  increased  with  the  years  of  age,  being  41  per  cent,  for  the 
years  10  to  12,  inclusive,  and  60  per  cent,  for  the  years  18  to  20,  In 
West  Virginia,  Clarke  ^  examined  13,836  school  children  of  11  counties, 
in  1913,  and  found  1,234  cases  of  goiter,  which  is  9  per  cent,  of  the 
number  examined.  In  Virginia,  the  same  worker  examined  6,432  school 
children  in  9  counties,  and  found  817  cases  of  goiter — 12  per  cent.  In 
Huntington,  West  Virginia,  50  per  cent,  of  the  girl  students  were  found 
to  be  affected;  in  Virginia,  less  than  0.1  per  cent,  of  the  goiters  were 
among  boys.    In  Europe,  an  even  higher  incidence  among  school  children 

"The  full  goitrous  throat  is   so   common  in   some  localities   that   it   is   re- 
garded as  a  type  of  beauty.     See  pictures  of  Burne-Jones  and  many  other  artists. 
''Journ.  Lab.  and  Clin.  Med.,  1917,  III,  No.  1. 
'  Public  Health  Reports,  1914,  XXIX,  939. 


GOITER  1153 

is  reported.  In  Bavaria,  Schittenhelm  and  Weichardt  found  an  inci- 
dence as  high  as  77  to  89  per  cent,  of  the  total  school  population. 
Hall  ^  found  18  per  cent,  of  2,086  men  at  the  University  of  Washington 
to  have  enlarged  thyroid  glands,  and  31  per  cent.,  or  1,252  women  stu- 
dents. Smith,^  an  army  surgeon,  in  1918  e.xamined  65,507  men  between 
the  ages  of  18  and  31  at  Jefferson  Barracks,  and  established  an  inci- 
dence of  1.63  per  cent.  Kerr  ^°  found  21  per  cent,  of  21,182  troops  at 
Camp  Lewis,  Washington,  to  have  goiter. 

The  absolute  number  of  goiter  subjects  in  countries  witli  high 
endemic  index  is  of  great  social  and  economic  importance.  In  France, 
Mayet  (1900)  estimates  the  number  at  400,000.  The  drain  on  the 
country  is  better  expressed  by  the  number  of  cretins.  In  Cisleithan, 
Austria,  there  were  in  1883  a  total  of  12,815,  or  71  per  100,000;  in  one 
district  in  Styria  a  proportion  of  1,045  in  100,000.  In  Piedmont,  Lom- 
bardy,  and  Venetia  there  were  in  1883,  12,882  cretins  in  a  population 
of  9,565,038. 

Goiter  in  Animals. — Sheep  and  swine,  and  also  mules,  horses  and 
pigs  have  goiter,  though  not  constantly,  in  endemic  centers.  Marine 
and  Lenhart  ^^  also  observed  goiter  among  brook  trout  in  fish  hatcheries; 
rats  and  mice  are  susceptible.  Marine  ^-  found  that  90  per  cent,  of  the 
dogs  in  Cleveland  are  affected  with  goiter.  It  is  perhaps  an  index  of 
our  comparative  concern  in  human  and  animal  welfare  that  goiter  among 
animals  has  been  the  object  of  many  prophylactic  measures,  whereas,  in 
the  same  district,  the  occurrence  of  goiter  among  humans  has  been  given 
scanty  consideration.  The  early  days  of  the  sheep  industry  in  Michigan 
were  found  to  be  unprofitable  in  that  a  large  percentage  of  the  animals 
presented  goiter.  The  abandonment  of  the  industry  was  contemplated, 
when  salt  mines  were  opened  up  in  the  vicinity  of  Detroit.  Heretofore, 
the  sheep  had  been  fed  with  salt  obtained  from  a  remote  source.  It 
was  soon  observed  that  the  sheep  fed  with  the  local  salt  were  better  in 
every  way;  the  young  were  born  free  of  goiter  and  did  not  subsequently 
develop  it.  Careful  investigation  established  the  fact  that  the  local 
supply  of  salt  contained  minute  traces  of  iodin  as  an  impurity.  In 
Montana  alone.  Smith  reports  that  about  1,000,000  pigs  were  lost 
annually  on  account  of  this  disease.  The  condition  was  present  at 
birth,  the  young  pigs  being  born  hairless  and  generally  stunted.  Many 
were  dead  at  birth,  and  few  survived  more  than  24  to  36  hours.  The 
affected  areas  in  some  instances  are  sharply  demarked.  At  times  the 
district  is  confined  to  a  creek  bottom  one-half  mile  wide.     The  affected 

^Northwest  Medicine,  1914,  n.s.,  VI,  189. 

*J.  A.  M.  A.,  1919,  LXXII,  471. 

"^"Arch.  Int.  Med.,  XXIV,  No.  3,  347. 

^  Johns  Hopkins  Hospital  Bull.,  1910,  XXI,  95. 

"Arch.  Int.  Med.,  1918,  XXII,  41. 


1154  WATER  AND  ITS  RELATION  TO  DISEASE 

pigs  had  large  thyroids  with  low  iodin  content.  The  addition  of  small 
quantities  of  iodin  salts  to  the  food  eliminated  the  condition. 

Goiter  occurs  among  fish,  seldom  in  the  native  state,  but  usually 
under  conditions  of  artificial  propagation.  It  has  been  observed  that 
the  amount  of  goiter  in  any  hatchery  is  in  proportion  to  tlie  uncleanli- 
ness  and  general  lack  of  sanitation  in  the  hatchery  in  which  the  fish 
propagate.  Through  the  work  of  Marine  and  Lenhart,  the  nature  of  the 
disease  was  established  and  simple  means  were  evolved  for  its  reduc- 
tion. In  general,  the  measures  consist  of  continued  cleanliness  of  the 
fisheries  and  the  supplying  of  food  containing  proper  constituents,  but 
particularly  to  the  addition  of  small  traces  of  iodin  or  iodin  salts  to 
the  living  water  of  the  fish. 

The  Cause  and  Prevention  of  Goiter. — It  is  now  clear  that  simple 
goiter  is  a  deficiency  disease  and  that  it  is  aggravated  by  and  increased 
in  frequency  by  improper  hygienic  and  sanitary  conditions,  such  as  over- 
work, overcrowding,  poor  ventilation,  bad  water  supply,  lack  of  proper 
personal  hygiene,  improper  disposal  of  sewage,  worry,  and  anything  that 
makes  an  undue  demand  upon  the  physiologic  functions  of  the  thyroid 
gland  contributes  to  the  development  of  goiter.  In  accordance  with 
this  view,  the  prevention  is  clear;  in  fact,  simple  goiter  is  probably  the 
easiest  of  all  known  diseases  to  prevent.  Marine  and  his  co-workers  ^^ 
used  the  following  method  with  success  at  Akron,  Ohio :  Two  grams 
sodium  iodid  were  given  in  0.2  gram  doses  for  10  consecutive  school  days, 
repeated  each  autumn  and  spring.  This  prevented  the  development  of 
new  goiters.  The  danger  of  iodism  or  exophthalmic  goiter  from  such 
amounts  of  iodin  is  negligible. 

The  cause  of  goiter  has  long  been  a  mystery,  and  certain  features 
of  the  condition  are  still  not  entirely  clear.  It  has  long  been  associated 
with  drinking  water;  in  fact,  remarkably  good  effects  have  been  obtained 
in  parts  of  Switzerland  and  Italy  by  the  introduction  of  good  drinking 
water.  There  are  goiter  wells  in  France  and  Switzerland,  the  waters 
of  which  are  used  successfully  for  the  intentional  production  of  the 
disease  with  a  view  to  escaping  compulsory  military  service. 

The  relation  of  water  to  goiter  is  also  illustrated  in  Vienna.  This 
city  long  boasted  of  the  best  water  among  all  European  cities.  It  is 
brought  in  long  aqueducts  and  subterranean  pipes  from  the  Schneeberg, 
a  mountain  group  about  6,000  feet  high  and  85  miles  to  the  north  of  the 
city.  This  water,  used  since  1872,  put  a  stop  to  typhoid  and  other 
gastro-intestinal  diseases.  The  water  comes  from  limestone  formations, 
and  has  a  low  degree  of  hardness,  owing  to  the  absence  of  vegetation 
upon  the  catchment  area.  Since  1873  the  number  of  goiters  in  Vienna 
have  increased  200  per  cent.,  and  popular  belief  always  pointed  to  the 
water  as  the  cause.     The  water  used  by  the  inhabitants  in  many  of  the 

^J.  A.  M,  A.,  Dec.  20,  1919,  Vol.  LXXIII,  p.  1873. 


LKAI)  POlSOXIXa  1155 

goiter  regions  in  SwitzcM-laiid  coiucs  from  similar  limestone  formations. 

Further  presumplive  evidence  Unit  goiter  is  m  wnier-honie  disease 
is  found  in  ciM'tain  villages  in  tlie  (iili,Mt  District  in  India.  Mere  ((ight 
villa,u"es  adjaeeid.  hi  each  dllier  dei'i\('  tlieii-  water  frdin  a  neighboring 
stream,  and  all  are  badly  all'eeted  with  goiter.  Another  village  in  the 
same  district  takes  its  water  from  a  spring  and  has  no  goiter. 

Another  instance  in  wliicb  the  change  of  water  supply  is  said  to  have 
influenced  the  prevalence  of  goiter  is  that  of  the  village  of  Bozel  in 
Tarentaise.  In  this  village,  during  1848,  of  a  population  of  1,473,  there 
were  900  eases  of  goiter  and  109  cretins.  About  this  time  a  new  water 
supply  was  introduced  from  a  source  only  800  meters  distant,  and  16 
years  afterward,  among  practically  the  same  population,  there  were  only 
39  cases  of  goiter  and  58  cretins. 

On  the  other  hand,  able  investigators,  such  as  Kocher,  Ewald, 
Bircher,  McCarrison  ^*  and  others  believe  that  goiter  is  an  infection 
due  to  a  living  microorganism.  It  is  in  fact  difficult  to  reconcile  some 
of  McCarrison's  observations,  upon  the  theory  that  the  disease  is  simply 
a  deficiency  of  iodin  in  the  water  or  food.  Further  study  may  develop 
the  fact  that  certain  parasites  may  cause  enlargement  of  the  thyroid 
gland. 

Simple  goiter  in  this  country  is  without  doubt  a  deficiency  disease, 
and  may  be  prevented  and  even  cured,  if  not  too  far  advanced,  by  the 
use  of  iodin.  The  secondary'  factors  which  aggravate  the  incidence  as 
well  as  the  severity  of  the  condition,  such  as  hygiene  and  sanitation, 
must  be  taken  into  account. 

LEAD  POISONING 

Lead  Poisoning.i — Lead  is  practically  never  found  in  natural  waters. 
The  source  of  the  lead  in  the  water  is  almost  always  lead  service  pipes, 
or  some  other  lead  object  used  in  collecting, .  storing,  or  delivering  the 
water.  Lead  is  the  most  dangerous  inorganic  substance  with  which 
our  drinking  water  is  ordinarily  contaminated.  Lead  poisoning  from 
this  source  is  much  more  common  than  it  is  given  credit  for.  A  cele- 
brated instance  of  lead  poisoning  occurred  in  Lancashire  and  York- 
shire, England.  The  water  came  from  peaty  moorlands  and  was  de- 
livered through  lead  pipes.  The  citizens  of  these  towns  experienced  a 
mysterious  bodily  derangement  for  some  years,  until  it  was  finally  dis- 
covered that  lead  poisoning  was  prevalent.  In  many  other  places,  as 
Somerfeld,  Germany,  and  Lowell,  Mass.,  numerous  cases  of  lead  poison- 
ing due  to  the  action  of  water  in  lead  pipes  have  been  reported. 

Enormous  quantities  of  lead  service  pipes  are  still  in  use,  not  only 
in  the  old  plumbing,  but  in  the  newer  installations.     It  is  so  pliable 

^*L(mcet,  Jan.  18  and  25,  and  Feb.  8,  1913. 


1156  WATEE  AND  ITS  EELATION  TO  DISEASE 

that  plumbers  find  it  much  easier  to  bend  it  around  corners  and  angles 
than  to  make  the  usual  connections  with  iron  or  brass  pipe,  and  it  is 
therefore  a  great  temptation  to  put  in  short  lengths  of  it  in  difficult 
places.  Lead  poisoning  may,  under  certain  circumstances,  come  from 
a  few  feet  of  lead  pipe.  The  various  factors  that  determine  the  corro- 
sive action  of  water  upon  lead  are  very  complex.  It  is  not  possible  to 
determine  by  chemical  tests  whether  or  not  a  water  has  plumbisolvent 
action.  All  natural  waters  have  some  solvent  power.  The  only  sure 
method  of  determining  to  what  degree  a  given  water  will  take  up  lead 
is  by  testing  the  question  experimentally  under  practical  conditions  and 
establishing  the  amount  of  lead  taken  up. 

The  way  by  which  water  takes  up  lead  is  first  through  the  formation 
of  lead  oxid.  This  oxidation  is  favored  by  the  amount  of  oxygen  car- 
ried in  the  water,  possibly  aided  by  the  nitrates  and  nitrites  serving 
as  oxygen  carriers.  The  lead  oxid  may  then  be  dissolved,  more  rapidly 
if  the  water  is  acid,  or  may  be  washed  away  by  the  currents  in  the  state 
of  a  fine  powder  in  suspension. 

As  a  general  rule  clean  (pure)  waters  have  a  greater  corrosive  action 
upon  lead  than  turbid  waters.  'This  is  partly  for  the  reason  that  the 
mud  coats  the  pipes  and  protects  them  mechanically.  Acid  waters  are 
almost  sure  to  take  up  lead  if  allowed  to  come  in  contact  with  that 
metal.  Even  so  feeble  an  acid  as  carbonic  acid  may  under  certain  cir- 
cumstances greatly  increase  the  plumbisolvent  action  of  water.  Soda 
water  (highly  charged  with  CO2  under  pressure)  takes  up  relatively 
large  quantities,  if  lead  pipes  are  used  in  soda  water  fountains  or 
"syphon"  bottles.  Waters  containing  carbonates  or  sulphates  are  not 
apt  to  take  up  lead  because  the  corresponding  salts  of  lead  are  insoluble, 
and  thus  form  a  protecting  coating.  Even  though  a  water  has  no  plum- 
bisolvent action,  the  use  of  lead  piping,  lead  cooking  utensils,  lead- 
lined  cisterns,  etc.,  is  entirely  unjustified  for  domestic  service,  for 
the  reason  that  under  certain  circumstances  electrolytic  action,  changes 
in  the  character  of  the  water,  or  other  causes  may  lead  to  lead  poisoning. 

Various  conditions  afl^ect  the  plumbisolvent  action  of  water,  such 
as  the  duration  of  contact,  the  temperature,  the  pressure,  the  season  of 
the  year,  the  purity  of  the  lead,  etc.  Water  remaining  in  the  pipes 
all  night  naturally  takes  up  more  lead  than  the  water  that  flows  more 
or  less  rapidly  during  the  day.  Lead  pipes  were  formerly  used  in  soda 
water  fountains  and  the  employee  who  took  the  first  drink  in  the  morn- 
ing before  the  proprietor  arrived  received  a  concentrated  dose.  Hot 
water  has  a  greater  solvent  action  than  cold  water;  so,  also,  increase  in 
pressure  up  to  140  pounds  to  the  square  inch.  For  some  unexplained 
reason  more  lead  is  often  found  in  the  water  during  the  winter  than 
during  the  summer.  The  purer  the  lead  in  the  pipes  the  freer  the 
solvent  action.    New  pipes  give  up  more  lead  than  old  pipes.    However, 


LEAD  POISONTNO  1157 

in  some  cases  the  poisoniii^^  iiiaiiirests  itself  only  after  the  ])i|)('  has 
been  in  use  for  years.  Lead  pipes  are  purer  now  than  formerly,  owing 
to  profitable  methods  of  extracting  the  silver  and  other  metals  with 
which  it  is  frequently  associated.  If  the  lead  is  combined  with  copper, 
zinc,  or  tin  the  lead  passes  into  the  water  more  quickly  in  consequence 
of  galvanic  action  than  when  pure  lead  is  used.  Electrolytic  action 
favors  the  solution  of  lead,  and  the  modern  method  of  grounding  electric 
currents  adds  to  the  danger. 

The  various  conditions  of  water  that  favor  plumbisolvent  action  are : 
Those  containing  free  acid,  such  as  soft,  peaty  waters;  those  containing 
much  oxygen  and  little  dissolved  salts,  that  is,  soft  waters,  such  as 
rain  water;  those  containing  organic  matter,  nitrites,  and  nitrates,  that 
is,  sewage-contaminated  water  in  the  stage  of  oxidization;  those  contain- 
ing chlorids,  because  chlorids  dissolve  the  protecting  film  of  carbonates. 
Waters  that  act  least  upon  lead  are  turbid  waters  and  hard  waters, 
especially  those  containing  free  CO2,  for  here  again  carbonates  are 
formed  which  protect  the  lead  with  an  insoluble  film.  However,  if 
CO2  is  present  in  excess  or  under  pressure  the  carbonates  are  redissolved. 

It  will  therefore  be  seen  that  the  purest,  softest,  and  best  aerated 
waters  are  especially  prone  to  act  upon  lead.  Distilled  water  will  take 
up  lead  even  from  impure  zinc  pipes  (containing  some  lead)  used  on 
board  ships.  Absolutely  pure  water  probably  has  no  appreciable  action 
upon  metals  such  as  lead,  iron,  and  zinc,  but  absolutely  pure  waters 
are  not  found  in  nature.  The  plumbisolvent  action  is  in  part  a  me- 
chanical erosion,  in  part  a  chemical  solution,  and  in  part  results  from 
electrolytic  action. 

Symptoms. — The  early  symptoms  of  lead  poisoning  are  sometimes 
vague  and  readily  overlooked.  Fatal  poisoning  may  be  caused  when  very 
little  lead  is  taken  -with  the  water  each  day;  the  action  is  cumulative  and 
the  course  of  the  intoxication  is  chronic;  the  immediate  and  remote 
effects  are  serious. ^^ 

The  usual  symptoms  of  chronic  lead  poisoning  are  anemia,  dyspepsia, 
depression,  constipation,  colic;  various  forms  of  paralysis,  especially 
paralysis  of  the  extensor  muscles  of  the  forearm  leading  to  wrist-drop ;  a 
blue  line  along  the  edges  of  the  gums,  due  to  the  formation  of  sulphid 
of  lead  deposited  in  the  tissues.  Optic  neuritis  may  come  on.  There 
is  an  increase  in  the  blood  pressure.  Chronic  lead  poisoning  leads  to 
arteriosclerosis,  fibrosis  of  the  kidneys,  and  the  remote  consequences  of 
these  changes.  Muscular  paresis,  pain  and  swelling  of  the  joints,  often 
occur  and  may  be  mistaken  for  "rheumatism."  In  some  cases  gout  is 
closely  simulated.     The  pain  is  usually  worse  at  night. 

The  individual  susceptibility  to  lead  poisoning  varies  remarkably. 
Of  a  number  of  individuals  equally  exposed  some  will  suffer  and  others 

"  For  further  discussion  of  Lead  Poisoning,  see  page    1293. 


1158  WATER  AND  ITS  RELATION  TO  DISEASE 

escape.  Of  those  who  suffer,  the  degree  of  intoxication  varies  consid- 
erably. It  is  quite  common  to  find  that  among  the  members  of  a  family 
using  a  water  containing  lead  only  one  is  stricken,  while  the  others  seem 
to  be  "immune";  that  is,  they  either  do  not  absorb  the  lead  or  are  able 
to  eliminate  it. 

Mild  cases  of  lead  poisoning  may  show  only  symptoms  of  anemia, 
vague  or  fugitive  pains,  or  a  mild  type  of  peripheral  neuritis.  This 
stage  of  lead  poisoning,  which  does  not  vary  essentially  from  other  in- 
toxications of  mild  degree,  is  readily  overlooked  clinically. 

Lead  is  absorbed  from  the  intestines  and  eliminated  by  the  kidneys 
and  the  liver.  It  therefore  may  appear  in  either  the  urine  or  feces. 
Lead  in  the  urine  is  always  associated  with  albumin,  and  may  be  inter- 
mittent. That  is,  a  well-marked  case  of  lead  poisoning  may  excrete 
urine  free  from  both  lead  and  albumin.  However,  if  the  feces  are 
examined  they  will  be  found  to  contain  lead. 

Cases. — Lead  poisoning  may  occur  when  a  comparatively  small  sur- 
face of  lead  is  exposed  to  the  solvent  action  of  the  water.  This  is  well 
illustrated  in  the  following  cases :  ^^ 

Case  1. — A  man  about  fifty-years  old  contracted  lead  poisoning  from 
using  cistern  water.  Twelve  feet  of  the  service  pipe  was  lead,  and 
almost  wholly  in  the  water,  as  it  was  bent  at  right  angles  and  ran 
across  the  cistern  under  the  water. 

Case  2. — Mrs.  W.,  sixty-six  years  of  age,  contracted  lead  poisoning 
from  a  well  water  which  was  contaminated  from  an  old  lead  clock 
weight  which  had  been  accidentally  dropped  into  the  well.  The  clock 
weight  had  been  in  the  water  about  fourteen  months  before  the  appear- 
ance of  symptoms.  The  well  was  pumped  free  of  water  and  the  clock 
weight  found  and  removed.  In  two  weeks  from  this  time  Mrs.  W. 
noticed  an  improvement  in  her  lameness,  and  in  four  months  she  was 
entirely  w^ell. 

Case  3. — In  this  case  the  patient  was  poisoned  by  cistern  water 
pumped  through  ten  feet  of  lead  pipe.  The  symptoms  were  acute  mul- 
tiple peripheral  neuritis,  with  extensive  paralysis.  After  the  lead  in 
the  water  was  removed  recovery  was  only  partial  after  a  period  of  two 
years. 

The  exact  amount  of  lead  which  may  be  taken  into  the  system  with- 
out producing  harm  is  not  definitely  known,  and  doubtless  varies  with 
different  people,  but  it  is  known  that  the  continuous  use  of  water  con- 
taining quantities  of  lead  as  small  as  0.005  of  a  part  per  million,  or  about 
1/33  of  a  grain  per  gallon,  has  caused  serious  injury  to  health.^'^ 

No  instances  have  been  recorded  of  ill  effects  upon  health  of  persons 
drinking  water  due  to  copper  or  zinc-lined  pipes. 

"Bull.  State  Board  of  Eealth,  Maine,  Jan.,  1909,  Vol.  1,  No.  21. 
^'  Mass.  State  Board  of  Eealth  Ann.  Report,  1898,  p.  XXXII. 


SPECIFIC  DISEASES  DUE  TO  WATER  1159 


SPECIFIC  DISEASES  DUE  TO  WATER 

The  principal  diseases  of  man  contracted  by  drinking  infected  water 
are  typhoid  fever,  cholera,  and  dysentery.  Water-borne  epidemics  of 
these  diseases  have  frequently  occurred  in  the  history  of  the  world. 
It  should  be  remembered  that  endemic  and  sporadic  cases  may  also  con- 
tract their  infections  through  water.  The  great  water-borne  tragedies 
have  for  a  time  occupied  an  exaggerated  position.  They  overshadowed 
the  less  dramatic,  but  more  insidious,  and  nevertheless  frequent  modes 
of  transmission  of  infection  through  other  channels,  especially  "con- 
tacts.^'  It  is  only  in  recent  years,  since  the  water  supplies  of  most  of 
our  large  communities  have  been  very  much  improved,  so  that  water- 
borne  epidemics  have  been  excluded,  that  sanitarians  have  appreciated 
the  quantitative  role  played  by  water  as  a  medium  of  convection  in 
distributing  pathogenic  microorganisms. 

It  is  worthy  of  note  that  almost  all  the  large  water-borne  outbreaks 
that  have  been  investigated  have  been  traced  to  a  quick  transfer  of  the 
infected  material  from  the  patient  to  the  victim.  Even  in  Pittsburgh 
the  Typhoid  Fever  Commission  showed  that  most  of  the  fever  there  had 
been  due  to  nearby  rather  than  to  remote  pollution  of  the  river.  The 
greater  the  distance  and  the  longer  the  time  between  the  source  of  the 
infection  and  the  use  of  the  water,  the  less  are  the  chances  of  harm. 
This  we  now  understand  as  the  result  of  several  factors  which  have  been 
discussed. 

It  is  doubtful  whether  typhoid,  cholera,  or  dysentery  bacilli  multiply 
in  water  under  natural  conditions,  certainly  to  no  great  extent.  Almost 
all  the  great  water-borne  epidemics  of  typhoid  fever  occur  in  the  spring, 
winter,  or  fall  of  the  year,  when  the  water  is  very  cold.  Water-borne 
epidemics  of  typhoid  in  the  summertime,  when  the  conditions  seem 
favorable  for  multiplication  of  the  bacilli,  are  relatively  infrequent. 
Assuming  that  in  the  case  of  typhoid  there  is  no  multiplication  of  the 
bacilli  in  the  water,  the  dilution  must  have  been  enormous  in  many  of 
the  cases  recorded ;  that  is,  there  must  have  been  very  few  typhoid  bacilli 
in  a  tumblerful  of  water.  If  these  facts  are  correct  it  illustrates  how 
very  few  bacteria,  when  fresh  and  virulent,  may  induce  disease.  The 
experimental  data  from  the  laboratory  indicate  that  the  healthy  organ- 
ism may,  as  a  rule,  successfully  overcome  small  doses  of  infection.  Feed- 
ing  experiments,  especially  upon  the  lower  animals,  under  laboratory 
conditions,  indicate  that  very  large  numbers  of  microorganisms  are 
usually  necessary  to  induce  disease  when  administered  by  the  mouth. 
This  is  only  one  of  the  many  discrepancies  between  laborators*  and 
natural  conditions.  Many  large  epidemics  have  been  traced  to  indi- 
vidual instances  of  pollution.    In  the  typhoid,  epidemics  at  Butler,  Plym- 


1160  WATER  AND  ITS  RELATION  TO  DISEASE 

outh,  New  Haven,  in  Nanticoke  and  Reading,  there  were  collectively 
3,929  cases  of  typhoid  fever,  with  361  deaths,  resulting  from  the  care- 
less treatment  of  the  discharges  of  but  one  individual  patient  in  each 
outbreak. 

Outbreaks  due  to  water  are  usually  caused  by  the  contamination  of 
surface  supplies;  less  often  by  wells  and  springs.  It  is  self-evident 
that  the  great  epidemics  have  always  been  caused  by  polluted  river  or 
lake  waters,  and  not  by  ground  waters.  Ground  water  is  sometimes 
responsible  for  outbreaks  of  typhoid  fever,  especially  in  limestone  dis-  ' 
tricts,  as  at  Lausen,  Switzerland;  Paris,  France,  etc.  Usually  when  a 
well  becomes  badly  infected  it  is  from  a  nearby  privy  or  broken  sewer 
underground,  as  in  the  instance  of  the  Broad  Street  cholera  epidemic  in 
London. 

Epidemics  from  public  water  supplies  result  from  contamination  by 
various  factors.  The  use  of  a  raw  water  into  which  is  continually  dis- 
charged the  sewage  of  other  towns  has  occurred  at  Pittsburgh,  Law- 
rence, Niagara  Falls,  Albany,  and  Philadelphia.  A  city  may  drink 
the  water  of  a  lake  which  has  become  its  own  cesspool,  as  did  Chicago, 
Cleveland,  and  Burlington.  The  pollution  may  come  from  the  wastes 
of  individual  houses,  as  at  Plymouth,  or  from  institutions  or  factories; 
or  the  pollution  may  come  from  privies  situated  directly  over  the  stream 
or  on  its  banks,  as  at  Ithaca ;  or  the  pollution  may  come  indirectly  after 
the  offending  matter  has  been  deposited  on  the  surface  of  the  ground, 
later  gaining  access  to  the  water  course  by  the  washing  of  rain  or  seep- 
age through  ground  seams.  In  some  instances  epidemics  originate 
through  criminal  thoughtlessness  in  a  town  that  has  been  supplied  with 
a  pure  or  purified  water.  Thus  a  water  pipe  laid  through  a  polluted 
pond  may  become  sufficiently  disjointed  to  permit  admission  of  the  in- 
fected water,  as  occurred  at  Baraboo,  Wis.,  and  Palmerton,  Pa.  The 
admission  of  polluted  water  to  a  pure  city  supply  at  any  time  is  inexcus- 
able. Epidemics  have  originated  as  a  result  of  the  unusual  drain  upon 
the  water  supply  at  times  of  fire,  as  in  the  case  of  Lawrence ;  or  through 
failure  of  valves  to  operate,  as  in  the  case  of  Wilkinsburg,  Pa.;  when 
the  ordinary  water  supply  was  judged  to  be  insufficient  and  no  public 
warning  was  given  of  the  substitution  as  at  Newburyport;  or  when 
polluted  water  was  furnished  temporarily  while  the  filter  plant  was 
imdergoing  repair,  as  at  Lawrence,  Mass.,  in  1902,  in  Brewer,  in  Pough- 
keepsie,  N.  Y.,  and  Millinocket,  Me.  Various  public  wells  have  become 
infected  through  ground  seams,  and  have  thus  caused  epidemics  of 
typhoid  fever  at  Trenton,  Newport,  and  Mt.  Savage,  Md.^® 

In  addition  to  the  usual  sources  of  pollution  of  a  surface  water, 
the  following,  while  relatively  infrequent,  may  be  particularly  dangerous, 

"Harold  B.  Wood:  "The  Economic  Value  of  Protecting  the  Water  Sup- 
plies," J.  A.  M.  A.,  Oct.  2,  1909,  p.  1093, 


SPECIFIC  DISEASES  DUE  TO  WATER  1161 

for  the  reason  that  they  are  apt  to  UAie  plaee  near  the  source  of  supply: 
discharges  from  water-closets  of  railroad  trains  while  crossing  bridges 
or  passing  the  hanks  of  reservoirs  and  streams;  picnic  parties;  camping 
parties;  construction  gangs;  fishermen;  ferryboats  and  other  craft  upon 
navigable  streams.  The  large  boats  plying  our  Great  Lakes  may  dis- 
charge dangerous  and  obnoxious  material  very  near  an  intake. 

Cholera — Cholera  in  London  in  JSoJfj  the  Case  of  the  Broad 
Street  Pump. — Cholera  was  prevalent  in  London  in  1854,  but  prevailed 
with  epidemic  intensity  in  the  district  about  Broad  Street.  This  focus 
was  conspicuously  circumscribed  in  area,  and  the  disease  was  virulent, 
with  great  fatality.  This  case  has  become  classic  because  it  was  one 
of  the  earliest  instances,  if  not  the  first,  in  which  water  was  proved  to 
convey  a  specific  disease.  The  circumstances  were  studied  by  Dr.  John 
Snow  and  by  Mr.  John  York,  Secretary  and  Surveyor  of  the  Cholera 
Inquiry  Committee.^"  No  less  than  700  deaths  occurred  in  St.  James 
Parish  during  the  seventeen  weeks  that  the  cholera  raged.  The  death 
rate  was  220  per  10,000  in  the  parish,  which  contained  a  population  in:- 
1851  of  36,406.  In  the  adjoining  districts  the  death  rate  varied  from 
9  to  33  per  10,000. 

Dr.  Snow  made  a  careful  epidemiological  study  of  the  outbreak  and 
compiled  a  statistical  statement  of  special  value,  which  is  given  in  its 
original  form  on  the  next  page. 

Many  of  the  facts  of  this  epidemic  are  taken  from  Sedgwick's  excel- 
lent account  in  his  "Principles  of  Sanitary  Science  and  the  Public 
Health,"  1902,  which  the  student  is  advised  to  read. 

It  will  be  seen  that  the  disease  broke  out  with  special  intensity  upon 
August  30  and  declined  noticeably  after  September  10.  The  pump 
had  been  removed  on  September  8.  Dr.  Snow's  inquiry  showed  that 
most  of  the  victims  had  preferred  or  had  access  to  the  water  of  the 
Broad  Street  well,  and  only  in  a  few  cases  was  it  impossible  to  trace 
any  connection  with  that  source.  Thus,  with  regard  to  73  deaths  occur- 
ring in  the  locality  of  the  pump  and  studied  especially  with  reference 
to  this  point,  it  was  found  that  there  were  61  instances  in  which  the 
deceased  persons  used  to  drink  the  water  from  the  pump  in  Broad 
Street,  either  constantly  or  occasionally.  In  6  instances  no  information 
could  be  obtained,  and  in  6  cases  it  was  stated  that  the  deceased  persons 
did  not  drink  the  pump  water  before  their  illness. 

On  the  other  hand.  Dr.  Snow  discovered  that,  while  a  workhouse 

(almshouse)   in  Poland  Street  was  three-fourths  surrounded  by  houses 

in  which  cholera  deaths  occurred,  out  of  535  inmates  of  the  workhouse 

only  5  cholera  deaths  occurred.     The  workhouse,  however,  had  a  well  of 

"The  complete  original  report  is  entitled  "Eeport  on  the  Cholera  Outhreak 
in  the  Parish  of  St.  James,  Westminster,  during  the  Autumn  of  18.54.  Presented 
to  the  Vestrv  by  the  Cholera  Inquiry  Committee,  July,  1855."  London,  J. 
Churchill,  1855, 


1162 


WATER  AND  ITS  RELATION  TO  DISEASE 


The  Broad  Street  (London)  well  and  deaths  from  Asiatic  cholera  near  it  in  185^ 


Aug.  19. 

Aug.  20. 

Aug.  21, 

Aug.  22. 

Aug.  23. 

Aug.  24. 

Aug.  25. 

Aug.  26. 

Aug.  27. 

Aug.  28. 

Aug.  29. 

Aug.  30. 

Aug.  31. 

Sept.  1 

Sept.  2 

Sept.  3 

Sept.  4 

Sept.  5 

Sept.  6 

Sept.  7 

Sept.  8 

Sept.  9 

Sept.  10 


Number 
of  Fatal 
Attacks 


1 
1 
1 
0 
1 
1 
0 

1 
1 
1 
1 

8 

56 

143 

116 

54 

46 

36 

20 

28 

12 

11 

5 


Deaths 


1 

0 

2 

0 

0 

2 

0 

0 

1 

0 

1 

2 

3 

70 

127 

76 

71 

45 

37 

32 

30 

24 

18 


Date 


Sept.   11 

Sept.   12 

Sept.  13 

Sept.  14 

kSept.  15 

Sept.    16 

Sept.    17 

Sept.    18 

Sept.    19 

Sept.    20 

Sept.    21 

Sept.    22 

Sept.    23 

Sept.    24 

Sept.    25 

Sept.-  26 

Sept.    27 

Sept.    28 

Sept.    29 

Sept.    30 

Date  unknown. 


Total. 


Number 
of  Fatal 
Attacks 


0 

0 

0 

45 

616 


Deaths 


15 
6 

13 
6 
8 
6 
5 
2 
3 
0 
0 
2 
3 
0 
0 
2 
0 
2 
0 
0 
0 

616 


its  own  in  addition  to  the  city  supply,  and  never  sent  for  water  to  the 
Broad  Street  pump.  If  the  cholera  mortality  in  the  workhouse  had 
been  equal  to  that  in  its  immediate  vicinity  it  should  have  had  50 
deaths. 

A  brewery  in  Broad  Street  employing  seventy  workmen  was  entirely 
exempt,  but,  having  a  well  of  its  own,  and  allowances  of  malt  liquor 
having  been  customarily  made  to  the  employees,  it  appeared  likely  that 
the  proprietor  was  right  in  his  belief  that  resort  was  never  had  to  the 
Broad  Street  well. 

It  was  quite  otherwise  in  a  cartridge  factory  at  No.  38  Broad  Street, 
where  about  200  workpeople  were  employed,  two  tubs  of  drinking  water 
having  been  kept  on  the  premises  and  always  filled  from  the  Broad 
Street  well.  Among  these  employees  eighteen  died  of  cholera.  Similar 
facts  were  elicited  for  other  factories  on  the  same  street,  all  tending  to 
show  that  in  general  those  who  drank  the  water  from  the  Broad  Street 
well  suffered  either  from  cholera  or  diarrhea,  while  those  who  did  not 
drink  that  water  escaped.  The  whole  chain  of  evidence  was  made 
absolutely  conclusive  by  several  remarkable  and  striking  cases  in  Dr. 
Snow's  report  like  the  following : 

"A  gentleman  in  delicate  health  was  sent  for  from  Brighton  to  see 
his  brother  at  JSTo.  6  Poland  Street  who  was  attacked  with  cholera  and 
died  in  twelve  hours^  on  the  first  of  September.    The  gentleman  arrived 


SPECIFIC  DISEASES  DUE  TO  WATER 


1163 


after  his  brother's  death,  and  did  not  see  the  body.  He  only  stayed 
about  twenty  minutes  in  the  house,  where  he  took  a  hasty  and  scanty 
luncheon  of  rump  steak,  taking  with  it  a  small  tumbler  of  cold  brandy 
and  water,  the  water  being  from  the  Broad  Street  pump.  He  went  to 
Pentonville,  and  was  attacked  with  cholera  on  the  evening  of  the  fol- 
lowing day,  and  died  the  next  evening. 

"The  deaths  of  Mrs.  E.  and  licr  niece,  who  drank  the  water  from 


ASIATIC  CHOLERA 
avMD 
THE  BROAD  STREET  PUMR 
LONDON  1654. 


•  •LOCflTIOM  or  I^UMPS. 

•  »  LOCATION  OF  F«TflL  CHOLERA  CASES 

—  —  BOUnOABV  or  E9UAL   OlSTAnCES   BETWEEhu-jt 
BROAD  STREET   PUMP  AMD  —  " 

OTHER    PUMPS. 

(AFTER  THE  ORISIHAL  MAP   Br 

OR.   JOHII   SNOW.) 


^^^tM^ 


Fig.  122. 


Broad  Street  at  the  West  End,  Hampstead,  deserve  especially  to  be 
noticed.  I  was  informed  by  Mrs.  E.'s  son  that  his  mother  had  not 
been  in  the  neighborhood  of  Broad  Street  for  many  months.  A  cart  went 
from  Broad  Street  to  West  End  every  day,  and  it  was  the  custom  to 
take  out  a  large  bottle  of  the  water  from  the  pump  in  Broad  Street,  as 
she  preferred  it.  The  water  was  taken  out  on  Thursday,  the  31st  of 
August,  and  she  drank  of  it  in  the  evening  and  also  on  Friday.  She 
was  seized  with  cholera  on  the  evening  of  the  latter  day,  and  died  on 
Saturday.  A  niece  who  was  on  a  visit  to  this  lady  also  drank  of  the 
water.     She  returned  to   her   residence,   a  high   and   healthy  part  of 


1164 


WATEE  AND  ITS  EELATION"  TO  DISEASE 


r 

I 

I 

i 


PAVEMENT. 


A 


I 


WATER      LINE. 


Islington,  was  attacked  with  cholera,  and  died  also.  There  was  no 
cholera  at  this  time,  either  at  West  End  or  in  the  neighborhood  where 
the  niece  died.  Besides  these  two  persons  only  one  servant  partook  of 
the  water  at  "West  End,  Hampstead,  and  she  did  not  suffer,  or,  at  least, 
not  severely.     She  had  diarrhea." 

Mr.  York,  Secretary  and  Surveyor  of  the  Cholera  Inquiry  Commit- 
tee, was  instructed  to  survey  the  locality  and  examine  the  well,  cess- 
pool, and  drains  at  No.  40  Broad  Street.  His  report  revealed  the  fol- 
lowing condition  of  affairs : 
The  well  "was  circular  in 
section,  28  feet  10  inches 
deep,  6  feet  in  diameter, 
lined  with  brick,  and  when 
examined  (April,  1855) 
contained  7  feet  6  inches  of 
water.  It  was  arched  in  at 
the  top,  dome  fashion,  and 
tightly  closed  at  a  level  3 
feet  6  inches  below  the 
street  by  a  cover  occupying 
the  crest  of  the  dome.  The 
bottom  of  the  main  drain 
of  the  house  from  No.  40 
Broad  Street  lay  9  feet  3 
inches  above  the  water  level, 
and  one  of  its  sides  was  dis- 
tant from  the  brick  lining 
of  the  well  only  2  feet  8 
inches.  This  was  an  old- 
fashioned  drain  12  inches 
wide,  with  brick  sides;  the 
top  and  bottom  were  made 
with  old  stone.  It  had  a  small  fall  to  the  main  sewer.  The  mortar 
joints  of  the  old  stone  bottom  were  found  to  be  perished,  as  was  also 
the  jointing  of  the  brick  sides,  which  had  brought  the  brickwork  into 
the  condition  of  a  sieve,  through  which  the  house  drainage  must 
have  percolated  for  a  considerable  period.  Dr.  Snow  found  the  cesspool 
intended  for  a  trap,  but  misconstructed,  and  upon  and  over  a  part  of 
the  cesspool  a  common  privy,  without  water  supply,  for  the  use  of  the 
house  had'  been  erected.  The  brickwork  of  the  cesspool  was  found  to 
be  in  the  same  decayed  condition  as  the  drain.  Dr.  Snow  states  that, 
"from  the  charged  condition  of  the  cesspool,  the  defective  state  of  its 
brickwork,  and  also  that  of  the  drain,  no  doubt  remains  upon  my  mind 
that  constant  percolation,  and  for  a  considerable  period,  had  been  con- 


ASIATIC   CHOLERA 

AND 

THE  BROAD  STREET  WELL. 
LONDON   1854. 

W. .WELL. 

0 MAfN    DRAIN    or  HOUSE    N0.40. 

VANoV.t.CELLARS     UNDER    STRCCT. 

C. CESSPOOL. 

P„. PRIVY. 

{after  MR.  YORkJB  ORIGINAL    DRAWINGS.) 

Fig.  123. 


SPECIFIC  DISEASES  DUE  TO  WATER  1165 

veying  fluid  matter  from  tlie  drains  into  tlie  well.  A  washed  appearance 
of  the  ground  and  gravel  flow  corroborated  this  assumption.  The  ground 
between  the  cesspool  and  the  well  was  black,  saturated,  and  in  a  swampy 
condition,  clearly  demonstrating  the  fact."  This  evidence,  while  only 
circumstantial,  is  sufficient  to  connect  the  cesspool  with  the  well,  and 
can  leave  no  doubt  in  the  minds  of  those  who  study  this  interesting 
and  instructive  instance  that  the  water  became  infected  with  cholera 
germs  through  this  channel.  It  should  be  remembered  that  this  out- 
break occurred  before  the  days  of  bacteriology,  so  that  direct  proof  is  not 
at  hand.  As  far  as  could  be  determined,  the  infection  of  the  well  came 
from  an  unrecognized  case  of  cholera  in  the  house  at  Xo.  40  Broad 
Street.  There  were  four  severer  cases  of  cholera  subsequeaitly  in  the 
same  house. 

The  Cholera  Epidemic  in  Hamburg  in  1892. — This  epidemic  stands 
out  clearly,  not  only  as  one  of  the  most  devastating  of  modern  times, 
but  as  one  of  the  most  instructive.  The  relation  between  the  infected 
water  and  the  disease  was  conclusively  proved,  and  the  value  of  slow 
sand  filtration  placed  upon  a  strong  foundation.  The  conditions  of 
the  epidemic  were  equal  to  those  of  a  well-controlled  laboratory  ex- 
periment, and  the  bacteriological  and  epidemiological  evidence  corrobo- 
rated each  other  in  every  essential  particular. 

From  August  17  to  October  23,  1892,  a  little  over  two  months,  there 
were  nearly  17,000  cases  of  cholera  in  Hamburg  (population  640,000), 
with  8.605  deaths.  On  one  day  during  the  height  of  the  epidemic  over 
1,000  new  cases  occurred.  This  was  a  pandemic  year  for  cholera  in 
the  sense  that  it  showed  a  remarkable  tendency  to  spread  to  all  parts 
of  the  world.  It  traveled  from  the  valley  of  the  Ganges  through  Per- 
sia, to  Eussia,  Germany,  x\ustria,  France,  Belgium,  Holland,  and  the 
disease  was  brought  to  our  own  doors  and  several  cases  occurred  in 
Xew  York  City. 

Hamburg  is  a  separate  city,  and  at  the  time  of  the  epidemic  had  a 
population  of  640,000.  Altona  (population  143,000)  is  in  Prussia. 
Politically  Hamburg  and  Altona  are  separate,  but  geographically  and 
actually  they  form  one  large  city.  The  boundary  runs  through  a  street 
on  one  side  of  which  is  Hamburg,  on  the  other  Altona.  Wandsbeck 
(population  20,000)  is  a  nearby  suburban  town.  Each  of  these  three 
places  at  the  time  of  the  epidemic  had  a  separate  water  supply..  Wands- 
beck  drank  filtered  water  from  a  spring  little  subject  to  pollution. 
Hamburg  and  Altona  were  both  furnished  with  water  from  the  Elbe 
River,  which  is  a  grossly  polluted  stream.  Both  the  cities  of  Hamburg 
and  Altona  rest  upon  the  bank  of  the  Elbe  River,  but  Altona  is  below 
or  downstream.  At  the  time  of  the  epidemic  the  intake  for  the  water 
supply  of  each  city  was  directly  at  the  river  front,  and  the  sewers  of 
the  city  emptied  into  the  river  at  various  points  along  the  same  river 


1166 


WATER  AND  ITS  RELATION  TO  DISEASE 


fronts.  It  will  therefore  be  seen  that  Altona  had  Elbe  River  water  plus 
Hamburg's  sewage.  Altona,  however,  first  filtered  this  water  by  the 
slow  sand  process;  Hamburg,  however,  furnished  its  citizens  with  the 
raw,  unfiltered  Elbe  River  water.  This  water  was  first  pumped  to  a 
single  reservoir,  which  at  one  time  held  approximately  a  day's  supply, 
but  had  long  outgrown  its  usefulness.  It  will  therefore  be  seen  that 
these  three  cities,  with  a  homogeneous  population,  with  the  same  climate, 


yANDSBECH 
iftO.OOO) 


Fig.  124. — Water  Supply  of  Hamburg. 
Hamburg  received  its  water  supply  from  the  Eiver  Elbe  (unfiltered)  at  G. 
The  sewage  of  Hamburg  and  Altona  entered  the  Elbe  at  ABC.  Altona  received  its 
water  supply  from  the  Elbe  at  D,  about  8  miles  below  ABC.  The  sand  filters 
which  purified  this  water  were  located  at  Blankenese.  Wandsbeck  had  an  inde- 
pendent water  supply  from  a  small  lake. 

the  same  low-lying  site,  and  all  other  conditions  similar,  differed  only 
in  their  water  supply. 

Relatively  few  cases  occurred  in  Altona,  and  most  of  these  were  on 
the  boundary,  where  the  people  probably  had  access  to  the  raw,  un- 
filtered Elbe  River  water.  In  Koch's  own  words,  "cholera  in  Ham- 
burg went  right  up  to  the  boundary  of  Altona  and  there  stopped. 
In  one  street,  which  for  a  long  way  forms  the  boundary,  there  was 
cholera  on  the  Hamburg  side,  whereas  the  Altona  side  was  free  from  it.'' 

During  the  epidemic  the  deaths  in  the  several  cities  were  as  follows : 


Population 

Deaths 

Deaths 
per  10,000 
Inhabitants 

Hamburg 

640,400 

143,000 

20,000 

8,605 

328 

43 

134.4 

Altona 

23.0 

Wandsbeck , 

22.0 

Further  evidence  consisted  in  the  fact  that  at  one   point  close  to 
and  on  the  Hamburg  side  of  the  boundary  line  between  Hamburg  and 


SPECIFIC  DISEASES  DUE  TO  WATER  1167 

Altona  is  a  lari,^'  yard  known  as  the  Uanibin-frer  Platz.  It  contains 
two  rows  of  lar^o  and  lol'ty  dwellings  containing''  seventy-two  sepa- 
rate tonenu>nts  and  some  400  ])eoj)le  belonging  almost  wholly  to  those 
classes  who  sull'er  most  from  cholera  elsewhere  in  Hamburg.  While 
cholera  prevailed  all  around  no  single  case  occurred  among  the  many 
residents  of  this  court  during  the  whole  epidemic.  Koch  found  that, 
owing  to  local  dilliculties,  water  from  the  Hamburg  mains  could  not 
easily  be  obtained  for  the  dwellings  in  question,  and  hence  a  supply 
had  been  obtained  from  one  of  the  Altona  mains  in  an  adjacent  street. 
This  was  the  only  part  of  Hamburg  that  received  Altona  water,  and  it 
was  also  the  only  spot  in  Hamburg  in  which  was  aggregated  a  population 
of  the  class  in  question  which  escaped  the  cholera.  The  source  of  the 
epidemic  was  traced  to  Russian  immigrants  crowded  in  barracks  on  one 
of  the  wharves  pending  their  embarkation  for  the  United  States,  and 
"at  the  time  of  the  outbreak  there  were  on  an  average  about  1,000  of 
these  people  on  hand  all  the  time.  Many  of  them  came  from  districts 
in  Russia  which  had  been,  and  were  then,  suffering  severely  from 
cholera,  and  all  were  well  supplied  with  dirty  clothing  and  blankets, 
some  of  which  they  washed  "s^hile  they  were  being  detained.  It  is  be- 
lieved that  among  those  that  had  arrived  there  must  have  been  some 
mild  cases  of  the  disease,  or  at  least  some  convalescents  with  cholera 
germs  still  in  their  evacuations  two  or  three  weeks  after  recovery.  All 
of  the  sewage  matters  of  every  description  from  these  people  were  dis- 
charged directly  into  the  river  at  the  wharf."  After  the  Elbe  River 
once  became  seeded  with  the  cholera  vibrio  the  people  in  Hamburg  who 
drank  this  infected  water  took  the  disease,  and  their  discharges,  return- 
ing to  the  river,  added  fuel  to  the  flames.  A  vicious  circle  was  thus 
set  up,  so  that  the  infection  became  exceedingly  concentrated  and  in- 
tense, and  as  the  circle  was  a  short  one  the  time  interval  was  corre- 
spondingly brief  and  the  virulence  unusually  severe. 

The  Hamburg  outbreak  will  ever  remain  classic  on  account  of  the 
clearness  of  the  circumstances  and  the  fact  that  there  is  no  missing 
link  in  the  chain  of  evidence  as  the  specific  organism  was  readily  iso- 
lated from  the  Elbe  River  water. 

Typhoid  Fever — The  Influence  of  Pure  Water  upon  Typhoid  Fever. 
— The  effect  of  an  improved  water  supply  appears  to  have  a  more 
favorable  influence  upon  typhoid  fever  than  upon  any  other  disease. 
The  relation  between  water  and  typhoid  fever  has  long  been  known, 
and  the  attention  of  vital  statisticians  has  been  focused  upon  the 
improvement  in  morbidity  and  mortality  of  this  disease  following  the 
purification  of  a  water  supply.  There  is  now  reason  to  believe  that 
the  good  effects  of  a  pure'  water  in  preventing  other  diseases  may  pos- 
sibly outweigh  the  good  effects  in  typhoid  alone.  The  typhoid  figures 
present  such  clear  and  often  dramatic  proof  of  the  value  of  clean  water 


1168 


WATEK  AND  ITS  EELATION  TO  DISEASE 


in  the  conservation  of  health  that  a  few  of  the  striking  tables  and  charts 
are  shown  upon  the  following  pages,  and  should  he  carefully  studied 
by  the  student. 

For  the  general  character  of  water-borne  epidemics  of  typhoid  fever 
and  the  relation  of  ice  and  cold  water  to  typhoid  see  page  118. 

The  table  on  page  1170,  compiled  by  Kober,^*'  clearly  shows  the  effect 
of  improving  the  water  supply  in  typhoid  fever  death  rates  in  American 
cities. 

From,  this  table  we  learn  that  the  combined  average  annual  rate 
from  typhoid  fever  in  cities  with  a  polluted  supply  was  69.4,  and  after 
the  substitution  of  a  purer  water  fell  to  19.8  per  100,000 — a  reduction 
of  71.4+  per  cent.  The  Bulletin  of  the  New  York  State  Health  Depart- 
ment for  April,  1908,  shows  that  the  death  rate  from  typhoid  fever 
in  ten  cities  of  that  state  has  been  reduced  53.4  per  cent,  by  an  im- 
proved water  supply.    Many  similar  instances  are  cited  in  the  literature. 

Table  sJwwing  the  average  typJioid  death  rate' per  100,000  for  a  period  prior  to 

the  improvement  in  the  loater  supply,  the  average  typhoid  death  rate  per 

100,000  since  the  change  in  the  water  supply,  and  the  percentage 

of  reduction,  caused  by  the  improvement 


Place 

Average 

Before 

Improvement 

Average 

After 

Improvement 

Per  Cent. 
Reduction  In 
Death  Rate 

1 

Albany 

88.8 
39.3 
54.9 
42.4 
64.3 
67.2 
95.5 
25.0 
58.2 
94.7 

23.7 
11.7 

41.5 
24.7 
31.9 
14.6 
54.4 
14.4 
31.0 
36.9 

73.0 

2 

3 

Binghamton 

Elmira 

72.2 
24.4 

4 

Hornell 

41.4 

5 

Hudson 

50.5 

6 

Ithaca 

78.3 

7 

Rensselaer 

43.0 

8 

Schenectady 

42.6 

9 

Trov                

46.8 

10 

Watertown 

61.8 

The  Typhoid  Epidemic  at  Lausen,  Switzerland. — The  epidemic  of 
typhoid  fever  which  occurred  in  Lausen,  Switzerland,  in  1872,  was 
the  first  to  attract  general  attention,  "and,  because  of  certain ,  peculiar 
conditions  connected  with  it,  and  especially  because  of  its  influence  upon 
the  theory  and  practice  of  the  purification  of  water  by  filtration,  it  de- 
serves the  most  careful  consideration  by  all  students  of  sanitation.'^ 
It  is  also  interesting  because  of  the  remoteness  and  unusual  method 
by  which  the  infection  reached  the  water  supply.  The  following  ac- 
count of  this  epidemic  is  from  the  description  by  Sedgwick,  quoting 
Dr.  Hagler's  ^^  report : 

The  epidemic  occurred  in  the  little  village  of  Lausen  in  the  canton 

^  "Conservation  of  Life  and  Health  by  Improved  Water  Supply,"  George  M. 
Kober,  1908. 

^^  Sixth  Report,  Rivers  Pollution  Commission  of  18E8,  London,  1874. 


SPECIFIC  DISEASES  DUE  TO  WATER 


llfiO 


0 

160 

140 

120 

100 

80 

60 

40 

20 

0 

100 

80 

60 

40 

20 

0 

100 

80 

60 

40 

20 

0 

40 

20 

0 

160 

140 

120 

100 

80 

60 

40 

20 

0 

100 

80 

60 

40 

20 

O 


rffl^n^"^' 


Fig.  125. — Chat^^ge  in  Water  Supply. 

1.  From  unfiltered  river  supply  to  filtered  river  supply. 

2.  From  unfiltered  river  supply  to  wells. 

3.  From  polluted  river  supply  to  conserved  river  supply.      (Kober.) 


1170 


WATER  AND  ITS  RELATION  TO  DISEASE 


60      70      80       90      100     IIO     120 


Pure  Motmldm  Spring? 


Filtered  Waters 
European  ftfies 


Fittertrt  Waters 
AroencaitCiVies 


GroutAWaters->ar^g  wells 


Impounding  Reservoirs 
Protected  Water  slveds 


Protected  Kiver  or  Stream  suppt\} 


tmm^ 


Smal^LaKes 


Great  Lakes  sutiject  to  pollution 


Mixed  surface  and  underground  waters 


-4.o"^,'i'«ch 


/lerniii 
Herliu 

^  -  Zuriili 
_9iL  Hmiliiiio 

Paris  • 

I  Loudon 

rftilersoii 

^     Biiujliaiiitdii 
jOMlhiiiiu 
l;iwreiife 


-18.1 


T8.5 


J&i 


193 


331 


.iwalerlijwiv 
fRiilniio(irll)(iriiiiyh 
J  Qupf  iislioroiitjh 
JCamdtn 
.iLiiwell 
fBctibutp 

Camt»nilQC 

Soinerville 

\M)rce?ter 

Britfoeporr 

HariJoixJ 

Malaen 

Boston 

Chelsea.,   . 

New  Bedford 

Waterburii 

Holijuke 

Bro)ixborouQl» 

ManliattuiitH)roH()li 

Pawtuckct 

MewarK 

Jersey  Citu 

Baliirfiore 

Rochestei" 

Suracust! 

fall  River 

Brocton 

Taunton 

Haverhill 

Portland 

Salem 

MitwauM 

Detroit 

Chiciioo 

BuMc 

Erie 

Oeveland 

,Dutulli 
.  St.Paut 

Canton 
■  BrooX)Mnborou(i 

ColUlDDUS 

.  McKeesport 

Miinieapoli? 

Seattle 

New  Orleans 
.  Toledo 

Evansvi^e 

Springfield 

Lovinolon 

GraniTRapids 

Wilmmjon 

RichTTiond 

Cincinnati 

Louisvrtte 

Philodelpliia 

Lancaster 

Atlanta 

Harrtstiurg 

Wtieelinfl 

Allegheny 


Fig.  126. — ^Mean  Death  Eates  feom  Typhoid  Fevee,  1902  to  1906,  in  66  Amer- 
ican Cities  and  7  Foreign  Cities  Grouped  According  to  their  Drinking 
Water. 
The  rates  for  foreign  cities  are  taken  from  James  H.  Fuertes.     (Kober.) 


SPECIFIC  DISEASES  DUE  TO  WATER  lin 

of  Basel  in  Switzerlaiul  in  Au^^ust,  IST'i.  Lauscn  was  a  well-kept  village 
of  90  houses  and  780  inhabitants,  and  had  never,  so  far  as  known,  suf- 
fered from  a  tyjthoid  e))i(leniie.  For  many  years  it  had  not  had  even 
a  single  case  of  tyiilioid  fever,  and  it  had  escaped  cholera  even  when  the 
surrounding  t'ountry  sutl'ered  from  it.  Suddenly,  in  August,  1H72,  an 
outbreak  of  tyjihoid  fever  occurred,  affecting  a  large  part  of  the  entire 
population. 

A  sliort  distance  south  of  Lausen  is  a  little  valley,  the  Fiirlethal, 
separated  from  Lausen  by  a  hill,  the  Stockhalden,  and  in  this  valley,  on 
June  19,  upon  an  isolated  farm,  a  peasant,  who  had  recently  been  away 
from  home,  fell  ill  with  a  very  severe  case  of  typhoid  fever,  which  he 
had  apparently  contracted  during  his  absence.  In  the  next  two  months 
there  occurred  three  other  cases  in  the  neighborhood — a  girl,  and  the 
wife  and  son  of  the  peasant. 

Ko  one  in  Lausen  knew  anything  of  these  cases  in  the  remote  and 
lonely  valley,  when  suddenly,  on  August  7,  10  cases  of  typhoid  fever- 
appeared  in  Lausen,  and  by  the  end  of  nine  days  57  cases.  The  num- 
ber rose  in  the  first  four  weeks  to  more  than  100,  and  by  the  end  of 
the  epidemic  in  October  to  about  130,  or  seventeen  per  cent,  of  the 
population.  Besides  these,  fourteen  children  who  had  spent  their  sum- 
mer vacation  in  Lausen  fell  ill  with  the  same  disease  in  Basel.  The 
fever  was  distributed  quite  evenly  throughout  the  town,  with  the  excep- 
tion of  certain  houses  which  derived  their  water  from  their  oa\ti  wells 
and  not  from  the  public  water  supply.  Attention  was  thus  fixed  upon 
the  latter,  which  was  obtained  from  a  well  at  the  foot  of  the  Stockhalden 
hill  on  the  Lausen  side.  The  well  was  walled  up,  covered,  and  appar- 
ently protected,  and  from  it  the  water  was  conducted  to  the  village, 
where  it  was  distributed  by  several  public  fountains.  Only  six  houses 
used  their  own  wells,  and  in  these  six  there  was  not  a  single  case  of 
typhoid  fever,  while  in  almost  all  the  other  houses  of  the  village,  which 
depended  upon  the  public  water  supply,  cases  of  the  disease  existed. 
Suspicion  was  thus  directed  to  the  water  supply  as  the  source  of  the 
typhoid,  very  largely  because  no  other  source  could  well  be  imagined. 

There  had  long  been  a  belief  that  the  Lausen  well  or  spring  was 
fed  by  and  had  a  subterranean  connection  with  a  brook  (the  Fiirler 
brook)  in  the  neighboring  Fiirler  valley;  and  since  this  brook  ran  near 
the  peasant's  house  and  was  known  to  have  been  freely  polluted  by  the 
excreta  of  the  typhoid  fever  patients,  absolute  proofs  of  the  connection 
between  the  well  of  Lausen  and  the  Fiirler  brook  could  not  fail  to  be 
highly  suggestive  and  important.  Fortunately,  such  proofs  were  not 
far  to  seek.  Some  ten  years  before  observations  had  been  made  which 
had  shown  an  intimate  connection  between  the  brook  and  the  well. 
At  that  time,  without  any  known  reason,  there  had  suddenly  appeared 
near  the  brook  in  the  Fiirler  valley  below  the  hamlet,  a  hole  about  eight 


1172  WATEE  AND  ITS  EELATION  TO  DISEASE 

feet  deep  and  three  feet  in  diameter,  at  the  bottom  of  which  a  consider- 
able quantity  of  clear  water  was  flowing.  As  an  experiment  the  water 
of  the  little  Fiirler  brook  was  at  that  time  turned  into  this  hole,  with 
the  result  that  it  had  all  flowed  away  underground  and  disappeared,  and 
an  hour  or  two  later  the  public  fountains  at  Lausen,  which,  on  account 
of  the  dry  weather  prevailing  at  the  time,  were  not  running,  had  begun 
flowing  abundantly.  The  water  from  them,  which  was  at  first  turbid, 
later  became  clear;  and  they  had  continued  to  flow  freely  until  the 
Fiirler  brook  was  returned  to  its  original  bed  and  the  hole  had  been 
filled  up.  But  every  year  afterward,  whenever  the  meadows  below  the 
site  of  the  hole  were  irrigated,  or  overflowed,  by  the  waters  of  the  brook, 
the  Lausen  fountains  soon  began  to  flow  more  freely.  In  the  epidemic 
year  (1872)  the  meadows  had  been  overflowed  as  usual  from  the  middle 
to  the  end  of  July,  which  was  the  very  time  when  the  brook,  had  been 
infected  hy  the  excrements  of  the  typhoid  patients.  The  water  supply 
of  Lausen  had  increased  as  usual,  had  been  turbid  at  the  beginning,  and 
had  had  a  disagreeable  taste.  And  about  three  weeks  before  the  begin- 
ning of  the  irrigation  of  the  Fiirler  meadows  typhoid  fever  had  broken 
out,  suddenly  and  violently,  in  Lausen. 

In  order  to  make  matters,  if  possible,  more  certain  the  following 
experiments  were  made,  but  unfortunately  not  until  the  end  of  August 
when  the  water  of  the  Lausen  supply  had  again  become  clear.  The  hole 
which  had  appeared  ten  years  earlier,  and  had  afterward  been  flUed  up, 
was  reopened,  and  the  little  brook  was  once  more  led  into  it ;  three  hours 
later  the  Lausen  fountains  were  yielding  double  their  usual  volume.  A 
quantity  of  brine  containing  about  eighteen  hundred  pounds  of  common 
salt  was  now  poured  into  the  brook  as  it  entered  the  hole,  whereupon 
there  appeared  very  soon  in  the  Lausen  water  flrst  a  small,  later  a  con- 
siderable, and  finally  a  very  strong  reaction  for  chlorin,  while  the  total 
solids  increased  to  an  amount  three  times  as  great  as  before  the  brine 
was  added.  In  another  experiment  five  thousand  pounds  of  flour 
(]\Iehl),  flnely  ground,  were  likewise  added  to  the  brook  as  it  disap- 
peared in  the  hole;  but  this  time  there  was  no  increase  of  the  total 
solids,  nor  were  any  starch  grains  detected  in  the  Lausen  water. 

It  was  naturally  concluded  from  these  experiments  that  while  the 
water  of  the  brook  undoubtedly  passed  through  to  Lausen  and  carried 
with  it  salts  in  solution,  it  nevertheless  underwent  a  filtration  which 
forbade  the  passage  of  suspended  matters  as  large  as  starch  grains.  Dr. 
Hagler,  from  whose  report  the  foregoing  facts  are  taken,  was  careful, 
however,  to  state  that  "it  is  not  denied  that  small  organized  particles, 
such  as  tv'phoid  fever  germs,  may  nevertheless  have  been  able  to  find  a 
passage."  As  a  matter  of  fact  Dr.  Haglers  minute  account  does  today 
give  us  some  indication  that  such  germs  might  easily  have  passed  from 
the  brook  to  Lausen,  for  the  turbidity  of  which  he  repeatedly  speaks  is 


SPECIFIC  DISEASES  DUE  TO  WATER 


1173 


evidence  of  the  passage  of  particles  as  small  as,  and  possibly  smaller 
than,  the  germs  of  typhoid  fever." 

Unfortunately  this  was  before  pure  cultures  of  bacteria  were  known, 
and  no  experiments  were  made  with  suspended  matters  as  small  as  bac- 
teria. The  conclusion  was  inevitable  that  although  filtration  had  in  this 
case  sufficed  to  remove  starch  grains,  it  had  been  powerless  to  remove  the 
germs  of  typhoid  fever ;  and,  accordingly,  filtration  as  a  safeguard  against 
disease  in  drinking  water  fell  for  a  time  into  disrepute.-^ 

The    Typhoid  Epidemic 


AVi  RESERVOIR 


HOUSE  TROM  WHICH 
'^THE  INFECTION  CAME. 


in  Plymouth,  Penn.  —  In 
1885  the  mining  town  of 
Plymouth,  Penn.,  with  a 
population  of  about  8,000, 
suffered  with  a  severe  out- 
break of  typhoid  fever  which 
involved  one  in  every  eight 
of  the  inhabitants.  Plym- 
outh received  its  water 
from  a  mountain  brook 
which  drained  an  almost 
uninhabited  watershed.  The 
stream  was  dammed  at  in- 
tervals and  the  water  was 
stored  in  a  series  of  four 
small  impounding  r  e  s  e  r  - 
voirs.  The  source  of  the 
infection  was  traced  to  a 
citizen  who  spent  his  Christ- 
mas holidays  in  Philadel- 
phia and  returned  home  in 
January.  He  contracted 
typhoid;  the  excreta  were 
not  disinfected,  but  were 
thrown    either    into    the 

frozen  creek  or  upon  its  banks  within  25  or  30  feet  of  the  edge  of  the 
stream  (see  map).  At  this  time  the  brook  was  frozen  and  remained 
so  until  spring.  There  came  a  thaw  in  March  and  the  entire  accumu- 
lation was  washed  into  the  brook  and  thence  into  the  water-main.  Three 
weeks  thereafter  cases  of  tvphoid  by  the  score  made  their  appearance 
throughout  the  town.     On  some  days  more  than  100  new  cases  occurred. 

^"Typhus  und  Trinkwasser,"  Vierteljahresschrift  fur  offentliche  Gesund- 
heitspflege,  VI,  154;  also  Sixth  Report,  Rivers  Pollution  Commission  of  1868, 
London,   1874. 

^  Sedgwick,  Journal  New  England  Water  Warks  Association,  XV,  1901,  p. 
330,  No.  4, 


MAP  OF 

PLYMOUTH,  PENN» 

IN     1885. 


Fig.  127. 


1174  WATEE  AND  ITS  EELATION  TO  DISEASE 

In  all  1,004  cases  were  reported.  Some  estimates  placed  the  number  at 
1,500,  that  is,  1  in  every  5  of  the  inhabitants.  There  were  114  deaths.  The 
epidemic  was  limited  to  the  houses  supplied  with  the  town  water  or  to  per- 
sons who  drank  of  the  public  water  supply.  The  distinction  was  particu- 
larly emphasized  on  one  street  where  the  houses  on  one  side  had  one  or 
more  cases  while  the  houses  on  the  other  side  had  none  at  all.  The 
former  were  supplied  by  the  town  water,  the  latter  depended  upon  wells. 

This  epidemic  will  ever  stand  out  in  the  literature  as  a  clear-cut 
instance  of  water-borne  typhoid  caused  by  the  quick  transfer  of  virulent 
material  from  a  single  case.  It  proves  further  that  freezing  alone  was 
not  sufficient  to  destroy  the  typhoid  infection,  and  on  account  of  the 
coldness  of  the  water  it  is  exceedingly  unlikely  that  any  multiplication 
of  the  typhoid  bacilli  occurred.  The  infection,  although  greatly  diluted, 
was  nevertheless  sufficiently  virulent  to  induce  the  disease  in  most  of 
those  who  drank  the  water.  It  further  teaches  the  lesson  how  one  per- 
son is  sufficient  to  defile  the  "pure  waters  of  a  mountain  brook  draining 
an  almost  uninhabited  territory."  This  epidemic  was  the  first  large 
outbreak  in  America  where  the  cause  was  definitely  traced  to  the  water 
supply.  It  stands  out  sharply  in  the  sanitary  annals  of  our  country  on 
account  of  the  lessons  it  taught  and  the  good  influence  it  had  in  stimu- 
lating other  cities  to  safeguard  and  improve  their  water  supplies. 

The  Typhoid  Epidemic  at  New  Haven. — Very  similar  to  the  Plym- 
outh outbreak  was  that  at  New  Haven,  Conn.,  during  April,  May,  and 
June  of  1901,  when  514  cases  of  typhoid  fever  occurred,  resulting  in  73 
deaths.  The  outbreak  was  carefully  studied  by  Professor  Herbert  E. 
Smith,  who  found  that  it  was  unq^iestionably  due  to  an  infection  of  one 
of  the  sources  of  public  water  supply. 

The  water  supply  in  New  Haven  was  drawn  from  five  distinct  sys- 
tems. It  was  all  surface  water  and  was  used  without  filtration.  One  of 
the  sources  was  known  as  the  Dawson  supply.  Dawson  Lake  was  a 
storage  reservoir  located  on  West  Biver  in  Woodbridge,  five  miles  from 
New  Haven.  Dawson  Lake  had  an  area  of  60  acres  and  a  capacity 
of  300,000,000  gallons.  There  was  no  direct  sewage  pollution  upon 
the  catchment  area  and  the  rural  population  was  only  25  per  square 
mile. 

A  mile  and  a  half  above  the  Dawson  Lake  a  small  str.eam  flowed  into 
the  river,  and  about  half  a  mile  up  this  stream  there  was  a  farmhouse 
situated  at  an  elevation  of  about  180  feet  above  the  water  in  the  lake. 
Several  cases  occurred  in  this  house  during  January  and  February,  1901. 
The  excreta  was  thrown  into  a  shallow  privy  vault  without  disinfection 
(for  the  reason  that  typhoid  fever  was  not  at  first  recognized).  Here 
they  accumulated  and  remained  more  or  less  frozen  for  six  weeks  or 
more.  This  privy  was  325  feet  from  the  brook  and  40  feet  above  it. 
On  March  10  and  11  there  was  a  heavy  rainfall   (2.46  inches)   and  a 


SPECIFIC  DISEASES  DUE  TO  WATER 


1175 


sudden  thaw.  The  flow  was  so  large  that  in  spite  of  the  intervention 
of  the  storage  reservoir  the  water  iu  the  city  was  in  a  turbid  condition 
on  the  afternoon  of  March  11.  The  typhoid  fever  outbreak  began  about 
10  days  later,  and  there  seems  to  be  little  doubt  that  infection  took 
place  at  this  time.  Professor  Smith  found  that  96  per  cent,  of  the  cases 
that  occurred  were  iu  the  districts  supplied  with  water  from  the  Dawson 
Lake  (Whipple). 

This  outbreak  again  illustrates  the  resistance  of  the  typhoid  infection 
to  freezing,  and  the  danger  from  a  surface  supply  that  for  years  may  run 
satisfactorily.  Even 
the  storage  reservoir 
failed  in  this  case,  as 
in  the  Plymouth 
case,  to  check  the 
quick  transfer  of  the 
infection.  Had  the 
Dawson  supply  been 
filtered  or  otherwise 
purified  the  epidemic 
could  have  been 
averted. 

The  Typhoid 
Epidemic  at  A  sh  - 
land,  Wisconsin.  — 
This  outbreak  i  s 
cited  from  Harring- 
ton and  is  one  of 
peculiar  interest,  in 
that,  in  addition  to 
serving  as  an  excel- 
lent illustration  of 
the  danger  of  using 

the  same  body  of  water  as  a  place  for  the  disposal  of  sewage  and  as  a 
source  of  drinking  water,  it  was  made  the  basis  of  an  action  at  law, 
which  established  the  liability  of  water  companies  and  municipalities 
in  case  of  sickness  and  death  caused  by  the  distribution  and  use  of 
infected  water. 

The  city's  supply  is  derived  from  an  arm  of  Lake  Superior,  Che- 
quamegon  Bay,  upon  which  the  city  is  situated.  This  bay,  which  is 
about  twelve  miles  long,  and  has  an  average  width  of  five  miles,  varies 
from  eight  to  thirty-six  feet  in  depth.  Xorth  of  the  citj,  and  extending 
outward  in  a  northwesterly  direction,  is  a  breakwater  constriicted  for 
the  protection  of  the  harbor  against  northerly  gales.  The  mouth  of 
the  water  intake  is  located  about  a  mile  from  the  shore  between  the 


Fig.   12 


1176  WATEE  AXD  ITS  EELATIOX  TO  DISEASE 

break^vater  and  the  city  (see  Fig.  128).  The  seAvage  of  the  city  is 
discharged  further  to  the  west  and  south.  The  currents  in  the  bay 
follow  the  course  indicated  by  the  arrows  in  the  figure,  and  carry  the 
sewage  toward  the  breakwater  and  over  the  mouth  of  the  intake.  This 
condition  of  affairs  was  brought  to  the  attention  of  the  company  by 
the  health  boards  of  the  city  and  state  repeatedly,  but  without  results. 
That  the  water  was  polluted  was  evident  on  mere  ocular  inspection,  for 
it  was  often  cloudy  or  markedly  turbulent.  During  the  winter  of 
1893-94  typhoid  fever  made  its  appearance  in  the  city,  and  from  the 
initial  cases  a  disastrous  epidemic  developed,  which  led  to  the  establish- 
ment of  a  model  filtering  plant. 

The  action  at  law  referred  to  above  was  brought  by  the  widow  of 
one  of  the  victims.  In  evidence  it  was  shown  that  he  lived  continuously 
in  Ashland,  and  drank  no  water  other  than  that  supplied  by.  the  water 
company;  that  previous  to  his  sickness  the  disease  had  prevailed  in  the 
city,  and  that  the  discharges  from  the  antecedent  cases  had  passed  into 
the  waters  of  the  bay  by  way  of  the  city  seWers.  The  court  found  for 
the  plaintiff  in  the  sum  of  $5,000. 

The  Typhoid  Epidemic  in  Manl-ato,  Minn. — Mankato  (popula- 
tion 11,553)  receives  its  water  supply  from  four  deep  artesian  wells  on 
Washington  Street.  Two  of  these  wells  are  within  from  16  to  18  feet 
of  the  pumping  station.  The  main  outlet  of  the  sewer  runs  down  Wash- 
ington Street,  emptying  into  the  river.  A  great  flood  occurred  May  20 
to  24,  1908.  The  gate  in  the  main  trunk  of  the  sewer  was  let  down  on 
the  night  of  June  24,  1908,  in  order  to  keep  the  river  from  backing  up 
into  the  sewers.  This  caused  a  backing  up  or  stasis  of  the  sewage,  which 
in  turn  backed  up  into  a  well  pit  of  the  new  artesian  well  near  the 
pumping  station,  hence  sewage  was  pumped  into  the  water  system.  Two 
of  the  other  wells  and  suction  mains  were  rusty  and  leaked  and  had 
not  been  properly  looked  after  for  a  number  of  years.  Then  came  a 
sudden  sharp  epidemic  of  diarrhea,  June  26.  Probably  2,000  persons 
were  affected.  It  soon  developed  that  the  prevailing  disease  was  typhoid 
fever.  The  epidemic  lasted  from  June  26  and  gradually  died  out  by 
Nov.  20,  1908.  From  July  7  to  Nov.  20  464  cases  of  typhoid  fever 
were  reported  to  the  Health  Officer.  Four  hundred  and  one  of  these 
cases  were  considered  primary  and  57  secondary  or  contact  cases  and  6 
outside  or  imported  infection. 

This  water-borne  outbreak  of  typhoid  fever  is  particularly  instructive 
from  the  fact  that  Delia  McKeever  and  Kate  Flanagan,  administratrices 
of  the  estates  of  their  husbands,  who  had  died  of  the  fever,  sued  the  city 
of  Mankato  for  damages.  The  city  demurred  to  this  complaint  on  the 
grrounds  that  as  a  government  it  could  not  be  sued  and  was  exempt 
because  it  was  carrying  out  a  government  function.  The  Supreme  Court 
of  Minnesota  held  that  "the  state  is  liable  if  damages  can  be  proved.'* 


SPECIFIC  DISEASES  DUE  TO  WATEE  1177 

The  decision  of  the  Supreme  Court  in  hokling  the  city  liable  sets  an  ex- 
cellent precedent  which  ])]aces  the  responsibility  where  it  should  be. 
Citizens  are  evidently  as  much  entitled  to  reasonable  sanitary  protection 
as  they  are  to  police  protection,  or  to  protection  from  accidents  at  grade 
crossings.  It  is  a  fortunate  day  for  preventive  medicine  when  the  prin- 
ciple is  recognized  that  sanitary  negligence  is  just  as  culpable  as  the 
negligence  which  fails  to  ])lace  a  rod  flag  or  a  red  lantern  to  warn 
against  a  pitfall  in  tlie  public  liigliway. 

The  Typhoid  Epidemic  in  Ithaca,  Netv  York. — In  the  winter  of 
1903  Ithaca,  Xew  York,  tlio  seat  of  Cornell  University,  was  visited  by  a 
severe  epidemic  in  tlie  course  of  wliich  1,350  cases  of  typhoid  fever 
occurred  in  a  population  of  about  13,1.")G.  The  population  included 
about  3,000  students  at  the  university.  ]\lorc  than  500  homes  were  vis- 
ited and  there  were  8"2  deaths.  Tbc  epidemic  covered  a  period  of  about 
3  months  and  extended  from  about  the  11th  of  January,  1903,  to  the  1st 
of  April,  although  for  several  months  before  the  epidemic  began  typhoid 
fever  had  been  unduly  prevalent.  The  epidemic  was  carefully  studied 
by  Dr.  George  A.  Soper,  who  clearly  showed  that  the  disease  was  due 
to  the  public  water  supply,  although  the  original  case  or  cases  which 
gave  rise  to  the  epidemic  were  not  ascertained.  Ithaca  had  at  that  time 
three  separate  sources  of  water  supply.  The  largest  one  was  derived 
from  Six-Mile  Creek  and  the  second  supply  from  Buttermilk  Creek,  and 
the  third  was  an  independent  supply  for  the  university.  The  conditions 
on  the  two  streams  were  similar.  Both  streams  were  considerably  pol- 
luted by  the  population  which  lived  largely  in  villages  bordering  on  the 
streams.  The  nearest  of  these  villages  was  5  miles  above  the  intake. 
Soper  found  numerous  other  sources  of  contamination  on  the  water- 
shed, and  some  even  in  the  city  of  Ithaca  a  few  rods  above  the  intake  of 
the  water-works  where  there  were  no  less  than  17  privies  located  on  the 
precipitous  banks  of  the  creek.  It  was  known  that  during  the  year 
previous  to  the  epidemic  there  had  been  at  least  6  cases  of  typhoid  fever 
on  the  watershed.  The  typhoid  epidemic  in  Ithaca  followed  a  flood  in 
the  river. 

One  episode  of  the  epidemic  is  worthy  of  special  mention,  namely, 
a  secondary  outbreak  which  resulted  from  the  infection  of  a  well.  This 
well  had  become  popular  among  the  residents  of  a  certain  district  at  the 
time  when  the  public  supply  came  to  be  distrusted,  and  its  good  quality 
was  taken  for  granted.  But  the  wife  of  the  owner  was  taken  sick  with 
typhoid  fever  during  the  epidemic,  and  her  dejecta  passed  without  disin- 
fection through  the.  water-closet,  and  into  a  drain-pipe  which  ran  within 
three  or  four  feet  of  the  well.  The  joints  of  the  drain-pipe  were  insecure ; 
and  the  well  water,  which  had  probably  been  for  some  time  grossly 
contaminated^  finally  became  infected.  As  a  result  about  fifty  cases  of 


1178  WATEE  AXD  ITS  EELATIOX  TO  DISEASE 

typhoid  fever  and  five  deaths  were  traced  to  people  who  used  this  well 
water   (Whipple). 

The  Typlioid  Epidemic  in  Butler,  Penn. — Butler,  Penn.  (popu- 
lation 16,000),  had  an  epidemic  of  typhoid  fever  in  1903.  There  were 
1,270  cases;  that  is,  about  8  per  cent,  of  the  population  were  attacked. 
Infection  in  this  case  was  clearly  water-borne  and  was  traced  to  one  of 
various  points  of  the  stream,  small  tributaries,  or  creeks.  One  house  in 
particular,  provided  with  an  overhanging  privy,  emptied  into  the  creek 
within  a  short  distance  of  the  pumping  station. 

The  Typhoid  Epidemics  of  Laivrence  and  Lowell. — During  the 
years  1890-91  a  typhoid  fever  epidemic  occurred  in  Lowell  and  Law- 
rence, Mass.  This  epidemic  illustrates  with  great  clearness  what  occurs 
on  streams  which  are  used  both  as  sources  of  water  supply  and  as  re- 
ceptacles for  sewage.  Both  cities  are  on  the  Merrimac  Eiver,  which  was 
grossly  polluted  by  the  sewage  of  Manchester  (population  44,126), 
Haverhill  (population  27,412),  Xashua  (population  19,311),  Concord 
(population  17,004),  Fitchburg  (population  22,037),  Xewburyport 
(population  13,947),  Marlborough  (population  13,805),  Clinton  (popu- 
lation 10,424),  and  from  other  sources  of  pollution.  In  Lowell  550 
cases  of  typhoid  fever  occurred  from  Sept.,  1890,  to  Jan.,  1891.  The 
epidemic  was  carefully  studied  by  Professor  "William  T.  Sedgwick,  who 
made  a  most  thorough  investigation. 

A  short  time  after  the  epidemic  in  Lowell  typhoid  fever  broke  out 
in  Lawrence,  nine  miles  downstream,  and  rapidly  increased.  The  rela- 
tion between  these  two  epidemics  was  most  striking.  Lowell  discharged 
its  sewage  into  the  river,  Lawrence  drank  the  water  without  filtration. 
The  climax  of  the  Lawrence  epidemic  occurred  about  one  month  after 
that  in  Lowell.  In  1892  there  was  a  repetition  of  this  episode.  Typhoid 
fever  in  Lowell  was  again  responsible  for  an  increase  of  t}T3hoid  fever 
in  Lawrence.  As  a  consequence  of  these  occurrences  Lowell  abandoned 
the  river  and  introduced  a  ground  water  supply,  while  at  Lawrence  a 
filtration  plant  was  constructed  which  has  materially  reduced  the 
amount  of  typhoid  fever  in  that  city  (Whipple). 

The  Typhoid  Epidemics  of  Pittsburgh  and  Alleghany. — These 
two  Pennsylvania  cities  are  situated  at  the  junction  of  the  Alleghany 
and  Monongahela  Elvers,  where  they  unite  to  form  the  Ohio.  In  1900 
Pittsburgh  had  a  population  of  321,616  and  Alleghany  129,896.  Pitts- 
burgh takes  its  water  from  the  Alleghany  Eiver  at  BriUiant  Station,  six 
miles  above  the  junction  of  the  rivers,  and  from  the  Monongahela  Eiver 
at  a  point  three  miles  above  the  junction.  Alleghany  receives  its  water 
supply  from  the  Alleghany  Eiver  at  Montrose,  ten  miles  from  the  point; 
it  is  drawn  from  a  rock-filled  crib.  It  is  practically  unfiltered  water. 
Both  the  Monongahela  and  the  Alleghany  Elvers  are  grossly  polluted 
streams,  receiving  the  sewage  from  a  populous  watershed;  in  addition 


SPECIFIC  DISEASES  DUE  TO  WATER  1179 

the  sewers  of  the  cities  of  Alleghany  and  Pittsburgh  empty  directly  into 
these  streams,  and  on  account  of  the  rapid  growth  of  these  cities  much 
of  this  sewage  entered  the  river  dangerously  near  to  the  water  intakes. 
The  records  of  the  Board  of  Health  show  that  at  this  time  there  oc- 
curred annually  upward  of  5,000  cases  of  typhoid  fever. 

For  about  ten  years  centering  around  1900  Pittsburgh  and  Alleghany 
had  the  unenviable  distinction  of  having  the  highest  typhoid  death 
rate  of  any  city  in  this  country  and  probably  of  any  large  city  in  the 
world.  At  times  the  rates  ran  above  150  per  100,000.  The  condi- 
tions have  recently  been  improved  by  the  introduction  of  slow  sand 
filtration  for  the  city  of  Pittsburgh.  Alleghany,  which  is  now  offi- 
cially known  as  Xortli  Pittsburgli,  was  furnished  (lltl3)  witli  filtered 
water. 

The  Typhoid  Epidemic  at  Chicago. — The  Chicago  epidemic  is  an 
illustration  of  a  city  using  a  lake  water  which  is  infected  with  its  own 
sewage.  The  water  in  1892  was  taken  from  Lake  Michigan  opposite  the 
city  at  several  "cribs"  which  were  1.5  to  1  miles  off-shore.  The  Chicago 
sewage  was  discharged  all  along  the  water-front,  while  the  Chicago  Eiver 
penetrated  the  city  with  its  north  and  south  branches  and,  polluted 
almost  beyond  endurance,  flowed  out  into  the  lake  about  midway  be- 
tween the  upper  and  lower  cribs.  The  pollution  of  the  lake  water  was 
at  times  so  intense  that  the  foul  river  water  could  be  traced  to  the  in- 
takes with  the  eye.  This  intolerable  situation  resulted  in  the  building 
of  the  Chicago  drainage  canal,  the  object  of  which  was  to  keep  the 
sewage  out  of  the  lake  and  carry  it  down  the  Des  Plaines  and  Illinois 
Eivers  into  the  Mississippi.  By  the  construction  of  this  canal  the  flow 
of  the  Chicago  River  was  reversed  so  that,  instead  of  the  sewage  entering 
the  lake  and  polluting  the  water  supply,  the  water  of  Lake  Michigan 
now  flows  westward  to  the  Mississippi  and  to  the  Gulf  of  Mexico.  Dur- 
ing the  years  1890,  1891,  and  1892  typhoid  fever  was  unusually  preva- 
lent in  Chicago.  In  1890,  1,008  of  the  inhabitants  died  from  typhoid 
fever,  in  1891  the  death  toll  from  this  preventable  disease  was  997  and 
in  1892,  1,489.  The  present  conditions  in  Chicago,  o^^dng  to  the  improve- 
ments in  the  water  supply,  in  the  milk  supply,  and  an  attack  upon  the 
residual  typhoid  as  contact  infection,  have  reduced  the  death  rate  to 
about  2  per  100,000,  which  was  further  lowered  by  chlorination  of  the 
water  supply. 

The  above  water-borne  typhoid  fever  epidemics  have  been  selected 
as  examples.  Many  more  may  be  found  in  the  literature.  Whipple,  in 
his  book  on  "Typhoid  Fever,^'  cites  numerous  instances  and  gives  in 
tabular  form  an  impressive  list  of  such  outbreaks,  with  references  to 
the  literature. 

Dysentery. — Both  bacillary  dysentery  and  amebic  dysentery  may  be 
transferred  through  drinking  water.     The  infection  in  both  types  of 


1180  WATER  AND  ITS  RELATION  TO  DISEASE 

dysentery  is  discharged  in  the  feces  and  taken  in  by  the  mouth;  there 
is,  therefore,  every  opportunity  for  water  to  play  the  same  role  in  dysen- 
tery that  it  plays  in  typhoid.  However,  comparatively  few  water-borne 
epidemics  of  bacillary  dysentery  have  been  reported ;  these  few,  neverthe- 
less, are  sufficiently  conclusive  to  be  convincing.  Amebic  dysentery  does 
not  occur  in  epidemic  form,  but  the  known  facts  are  sufficient  to  in- 
criminate water  as  one  of  the  vehicles  of  convection. 

Shiga  reports  outbreaks  in  Japan  from  the  use  of  well  and  river 
water.  Eldridge  states  that  dysentery  is  a  rural  disease  in  Japan;  the 
use  of  human  feces  as  a  fertilizer  and  the  frequency  of  the  infection  of 
the  numerous  small  streams  and  wells  render  it  preeminently  a  water- 
borne  disease.  Whittaker  ^*  reports  a  water-borne  epidemic  of  dysentery 
at  South  St.  Paul,  Minnesota,  caused  by  using  infected  water  from  a 
fire  connection.  The  epidemic  described  by  Duprey  which  Occurred  at 
Grenada  Island  in  1901  is  one  of  the  best  examples  of  a  water-borne 
epidemic  of  dysentery,  Shiga,  in  Osier's  "Modern  Medicine,"  gives  the 
following  instance: 

In  a  village  called  Momma-Mura,  at  Nobechi,  in  Japan,  in  1900,  a 
dysentery  epidemic  broke  out  in  houses  situated  near  each  other.  It  was 
proved  that  the  well,  used  by  all  the  households  suffering  from  the  dis- 
ease, was  infected  with  the  dysentery  bacillus.  We  have  also  an  in- 
teresting example  of  river-water  infection  in  Japan.  There  is  a  village 
called  Mitake-Mura  in  the  district  Miyagi-Ken,  through  which  a  river 
flows.  Fishing  and  swimming  are  prohibited  in  it  because  of  fish  breed- 
ing. In  the  late  summer  of  1899,  the  prohibition  having  been  removed, 
the  men  of  the  village  were  very  glad  to  be  allowed  to  fish  and  swim 
once  more  in  the  river.  However,  after  four  or  five  days  an  epidemic  of 
dysentery  broke  out  with  10  patients  on  the  first  day,  and  increasing 
numbers  daily  afterward.  There  were  in  all  413  cases,  of  which  115 
were  boys  under  ten  years  of  age.  After  investigation  it  was  found 
that  there  was  an  epidemic  of  dysentery  in  a  village  higher  up  the  river, 
and  the  water  had  been  soiled  with  the  infected  clothes. 

Epidemics  of  bacillary  dysentery  in  this  country  in  institutions  have 
not,  as  a  rule,  been  associated  with  water. 

The  Entameha  histolytica,  causing  amebic  dysentery,  was  recovered 
by  Musgrave  and  Clegg  ^^  from  17  to  61  samples  of  the  public  water 
supply  of  Manila  and  was  found  in  tanks  used  for  holding  distilled 
water  and  also  in  many  wells.  Recently  Allan  ^®  has  reported  a  small 
outbreak  of  amebic  dysentery  in  North  Carolina  due  to  an  infected  well. 

Diarrhea. — Polluted  waters  not  infrequently  cause  diarrhea,  some- 
times as  widespread  epidemics,  sometimes  as  small  outbreaks  or  sporadic 

="  Public  Health  Reports,  Vol.  XXX.  No.  48,  November  26,  1915,  p.  3473. 
^"Musgrave  and  Clegg:     Bull.  18,  Bu.  Gov.  Lab.,  P.  I.,  93;  Rep.  Bd.  Health, 
P.  I.  1904-05,  10. 

^* Allan:     J.  A.  M.  A.,  Chicago,  1909,  LIU,  1561. 


SPECIFIC  DISEASES  DUE  TO  WATER  1181 

cases.  Whenever  there  is  a  water-borne  outbreak  of  typhoid  fever  or 
cholera  there  are  also  a  large  number  of  cases  of  diarrhea  and  gastro- 
intestinal disturbances  in  whiili  the  precise  etiological  factor  has  not 
been  discovered.  Some  of  these  cases  may  be  mild  instances  of  the 
major  disease.  Infantile  diarrheas  are  especially  prevalent  at  such  times 
and  very  likely  due  to  the  contaminated  water.  Thus  Reincke  states 
that  infantile  diarrhea  was  greatly  U'sseiied  after  the  improvement  in 
the  water  supply  of  Hamburg.  The  same  phenomenon  was  noted  by 
Hiram  0.  ]\Iills  after  the  iiltration  of  the  water  supply  of  Lawrence. 
Mass.  Sedgwick  noted  an  excessive  prevalence  of  both  typhoid  fever 
and  diarrhea  in  Burlington  and  attributed  the  diarrhea  to  the  sewage 
contamination  of  the  water  supply.  Whipple  states  that  in  Albany 
there  was  a  reduction  of  57  per  cent,  in  the  mortality  from  diarrheal 
diseases  after  the  introduction  of  filtration  in  1S98.  Chapin  questions 
whether  such  statistical  evidence  is  sufficient  to  incriminate  water  as 
an  influence  to  the  causation  of  diarrheal  diseases. 

It  is  generally  believed  that  diarrhea  may  be  brought  on  by  changes 
from  a  hard  to  a  soft  water ;  also  by  organic  and  inorganic  impurities. 

Xumerous  outbreaks  of  diarrhea  have  been  attributed  to  the  follow- 
ing microorganisms  in  water,  viz. :  B.  coll,  B.  enteritidis  of  Gaertner, 
B.  pyocyaneus,  B.  proteMS,  B.  aerogenes  capsulatus  of  Welch,  B.  mesen- 
iericus,  and  streptococci.  Water  containing  these  and  other  organisms 
is  not  infrequently  regarded  as  the  cause  of  outbreaks  of  gastro-intestinal 
irritation.  The  symptoms  vary  greatly  in  intensity,  but  usually  the  dis- 
ease is  not  fatal  excepting  in  the  3'oung  and  feeble.  The  relation  be- 
tween the  diarrhea  and  the  water  is  usually  based  upon  the  fact  that 
some  species  of  microorganisms  are  found  both  in  the  water  and  in  the 
stools.  Corroborative  evidence,  such  as  the  finding  of  specific  agglutin- 
ins and  other  antibodies  in  the  blood,  lends  countenance  to  the  claim  that 
the  particular  microorganism  is,  in  fact,  the  cause  of  the  complaint. 
While  the  evidence  is  not  conclusive,  it  is  suggestive,  and  in  many  cases 
doubtless  correct. 

So-called  "winter  cholera''  is  a  mild  diarrheal  disease.  It  is  prob- 
ably water-borne,  but  the  cause  is  not  known.  It  occurs  in  epidemic 
outbreaks. 

Animal  Parasites. — The  eggs,  larvae,  or  other  stages  in  the  life  cycle 
of  various  intestinal  parasites  may  enter  the  body  in  drinking  water. 
Thus  the  eggs  of  Ascaris  lumhricoides  discharged  in  the  feces,  which  re- 
quire a  month  for  development  may  contaminate  streams  and  then 
be  returned  to  the  mouth.  Some  cases  of  infection  with  this  parasite 
probably  occur  in  this  way.  Oxyuris  vermicularis,  the  pinworm^  and 
Trichuris  tricliiura,  the  whipworm,  may  similarly  be  contracted  through 
drinking  water.  The  guinea  worm,  Dracunculus  medinensis,  may  be 
contracted  by  the  mouthy  in  drinking  water.     The  living  embryos  of 


1182  WATEE  AXD  ITS  EELATION"  TO  DISEASE 

this  worm  are  liberated  and  find  their  way  into  fresh  water.  There 
they  enter  the  bodies  of  small  fresh  water  Crustacea,  Cyclops,  which  act 
as  intermediate  hosts. 

It  is  fairly  well  established  that  the  larvae  of  the  hookworm  may  be 
taken  into  the  stomach  through  drinking  water,  and  the  same  is  as- 
sumed of  the  similar  parasite  of  Cochin  China  diarrhea. 


THE  SANITATION  OF  SWIMMING  POOLS 

The  problem  of  the  swimming  pool  is  a  good  example  of  an  institu- 
tion devised  to  improve  hygienic  conditions,  yet  the  device  itself  may 
be  a  hygienic  menace.  Swimming  is  one  of  the  best  and  most  ex- 
hilarating forms  of  exercise.  It  is  especially  suitable  for  the  tropics. 
Swimming  is  about  the  only  form  of  violent  exercise  that  can  be  prac- 
ticed in  hot  weather  without  danger  of  overheating  the  body.  Swim- 
ming has  the  added  hygienic  advantage  of  promoting  cleanliness. 

Swimming  pools  are  nothing  more  or  less  than  common  bath  tubs. 
The  growing  popularit}-  of  swimming  pools  has  led  to  an  increased  in- 
terest in  the  sanitary  conditions  that  prevail  in  them.  There  is  no 
longer  any  doubt  that  they  can  and  sometimes  do  transmit  disease. 
When  the  use  of  swimming  pools  is  made  compulsor}',  as  is  the  case 
with  pupils  of  some  secondary  schools,  a  serious  duty  of  sanitary  super- 
vision and  responsibility  arises. 

The  diseases  contracted  in  swimming  pools  are  intestinal  infections; 
inflammatory  infections  of  the  upper  respiratory  tract  and  conjunctiva; 
injury  and  inflammation  of  the  ears;  venereal  and  skin  diseases,  etc. 
Typhoid  fever  and  diarrheal  conditions  have  been  traced  on  reasonably 
reliable  evidence  to  swimming  pools  such  as  are  installed  by  private 
individuals,  or  found  in  colleges  and  universities,  public  and  private 
schools,  gymnasiums,  steamships,  and  special  bathing  establishments. 

The  chief  danger  of  infection  comes  from  the  water,  if  not  kept 
clean,  or  from  the  towels  and  swimming  suits,  if  not  disinfected.  The 
source  of  the  infection  comes  in  almost  all  instances  from  the  persons 
using  the  pool.  One  of  the  first  essentials,  therefore,  in  the  sanitation 
of  swimming  pools  is  to  require  a  shower  bath  with  the  liberal  use  of 
soap  before  entering  the  tank.  At  the  same  time,  a  careful  examination 
should  be  made  of  each  person  to  determine  especially  the  presence  of 
skin  diseases,  running  ears,  ulcers,  conjunctivitis,  venereal  disease,  or 
signs  of  inflammation  of  the  upper  respiratory  tract. 

Full  showers,  with  soap,  under  inspection,  should  be  demanded  of 
all  bathers  before  entering  the  pool.  Especial  attention  should  be  given 
to  the  perineal  region.  When  water  strikes  a  person's  body,  the  natural 
tendency  is  to  urinate.    This  should  occur  in  the  shower,  not  in  the  pool. 


THE  SANITATION  OF  SWIMMING  POOLS  1183 

Bathers  should  bo  instnittt'd  in  pool  sanitation.  Nude  bathing  should 
be  encouraged,  because  it  favors  inspection  and  does  away  with  the 
danger  of  contracting  infcflion  from  the  swimming  suit. 

The  water  should  have  an  initial  purity  equal  to  that  of  a  safe  drink- 
ing water  and  may  be  kept  fairly  clean  by  filtration  and  reasonably  safe 
by  ozone,  ultraviolet  rays;  chlorin  or  bleaching  powder.  The  com- 
bination of  refiltration  to  clean,  and  ozonization  to  disinfect  the  water  is 
the  best  present  available  method  to  keep  the  water  of  swimming  pools 
in  satisfactory  sanitary  conditions.  Occasional  use  of  sulphate  of  copper 
may  be  necessary  to  keep  down  excessive  growth  of  algae. 

The  bathers  are  constantly  introducing  pollution  and  occasionally 
infection.  To  offset  this,  disinfection  should  be  continuous,  at  least  it 
should  be  most  effective  at  the  time  when  the  pool  is  in  use. 

The  disinfection  of  the  water  in  the  pool  is  economical,  in  that  it 
is  not  necessary  to  change  the  water  as  often  as  without  treatment ; 
decency  and  safet}-^  require  frequent  changes  of  fresh  water.  Chlorin 
or  bleaching  powder  are  effective,  but  they  are  soon  oxidized  and  their 
disinfecting  power  rapidly  disappears.  If  too  much  chlorin  or  its 
compounds  are  added,  the  water  will  smart  the  eyes  and  have  an  un- 
pleasant odor  and  taste.  Copper  sulphate  is  unreliable;  ultraviolet  light 
can  be  used;  the  best  results  have  been  obtained  with  ozone,  for  it  is 
automatic  in  control,  reliable  in  action  and  inexpensive  in  operation. 
One  part  of  ozone  per  million  parts  of  water  will  sterilize.  In  addi- 
tion to  a  continuous  disinfection,  the  water  should  be  sterilized  at 
least  once  daily.  The  examination  of  swimming  pool  water  for  colon 
bacilli  as  an  index  of  pollution  is  as  logical  a  method  of  control  as  it 
is  in  the  case  of  drinking  water. 

In  localities  where  blood-flukes,  ScJiistosoma^  occur,  special  precau- 
tions are  necessary  with  respect  to  swimming  pools.  According  to 
Leiper,  the  cercariae,  which  are  the  infective  stage  of  the  parasites  and 
whose  penetration  through  the  skin  results  in  infection,  are  unable 
to  live  in  water  more  than  36  hours  after  their  escape  from  the  snails 
which  act  as  intermediate  hosts.  Consequently,  he  recommends  that  water 
before  it  is  used  he  stored  for  not  less  than  36  hours,  better  48  hours, 
in  reservoirs  that  are  protected  from  invasion  by  snails. 

The  sanitation  of  swimming  pools  requires  good  construction  and 
efficient  management.  The  tank  should  be  large,  Eoughly,  at 'least 
400  gallons  of  water  per  bather  is  needed.  The  pool  should  have  a 
smooth  lining.  The  dilution  should  be  continuous  and.  liberal,  and  the 
tank  emptied  and  refilled  frequently.  When  empty,  the  tank  should 
be  scraped,  scrubbed,  flushed,  then  steamed,  aired  and  dried.  The 
cleanliness  of  the  tank  is  aided  by  the  construction  of  troughs  at  the 
edges  to  afford  place  for  expectoration  and  to  prevent  dirt  from  the 
floor   draining  into  the  pool.      Sediment  on  the   floor  should  be  re- 


1184  WATEE  AND  ITS  RELATION  TO  DISEASE 

moved  with  hand  pumps.  The  filtering  should  be  continuous  and  the 
filter  of  sufficient  capacity  to  refilter  all  the  water  in  the  tank  in  eight 
hours.  Clear  water  is  essential  not  only  for  esthetic  reasons,  but  to 
reduce  the  hazard  of  drowning. 

Satisfactory  hygienic  conditions  in  swimming  pools  require  suit- 
able administration  of  the  plant,  including  the  supervision  of  the  work- 
ing force,  the  inspection  and  ablution  of  the  bathers  before  they  enter 
the  water,  and  their  instruction  in  pool  sanitation.  Finally,  steriliza- 
tion by  boiling  or  steaming  of  the  towels  and  bathing  suits  after  each 
use  will  avoid  one  of  the  sources  of  conveying  infection. 


DRINKING  FOUNTAIN 

The  movement  toward  the  abolition  of  the  common  drinking  cup 
has  led  to  the  development  of  so-called  drinking  fountains,  of  which 
there  are  many  types  on  the  market.  They  may  be  divided  into  inter- 
mittent and  continuous,  and  each  in  turn  into  those  with  and  without 
suitable  mouthguards. 

The  water  should  not  pass  through  a  cup  of  water  sure  to  become 
contaminated.  Experiments  show  that  it  takes  a  long  time  for  B.  coli 
to  be  eliminated  from  these  cups.  The  design  should  be  such  that  the 
user  cannot  touch  the  ball  with  the  lips,  and  that  waste  water  cannot 
remain  so  as  to  endanger  the  next  user  of  the  fountain.  The  Commit- 
tee on  Sanitary  Drinking  Fountains  ^^  recommended  that:  (1)  Mouth 
guards  are  a  necessity.  (2)  The  intermittent  vertical  jet  fountain  is 
unqualifiedly  condemned.  (3)  Continuous  vertical  jet  fountains  are 
open  to  suspicion.  (4)  A  slanting  jet  projected  with  a  mouthguard  is 
perfectly  safe. 

ICE 

Ice  was  not  suspected  of  being  a  vehicle  by  which  infection  could  be 
spread  until  it  was  shown  in  bacteriological  laboratories  that  typhoid  and 
other  cultures  are  not  killed  by  freezing.  Leidy  in  1848  showed  that 
water  derived  from  melted  ice  contained  not  only  living  infusoria,  but 
also  rotifers  and  worms.  Macfadyen  proved  that  the  temperature  of 
liquid  air  ( — 315°  F.)  does  not  kill  bacteria.  In  fact,  some  bacteria 
and  molds  grow  and  multiply  at  temperatures  as  low  as  0°  C,  See  also 
effects  of  cold,  page  730,  . 

Euata  ^^  finds  even  more  rapid  destruction.  Thus,  cultures  of  B.  coli, 
four  strains  of  another  bacillus  and  a  streptococcus  were  killed  after  four 
days  at  — 3°  C.  to — 12°  C. 

^  Journ.  Am.  Water  Wits.  Assn.,  Vol.  V,  1918,  110. 
^Ann.  d'Igiene,  Eoma,  Jan.,  1918,  28,  No.  1,  p.  1125. 


ICE  1185 

Sedgwick  and  Winslow -"'  (190"?)  were  the  first  to  make  quantitative 
studies  on  the  ett'eit  uf  freezing  upon  jiathogenie  Ijacteria.  'I'hey  used 
cultures  of  the  typhoid  hacillus  and  showed  that  50  per  cent,  of  the 
organisms  die  at  tlic  end  of  tlie  first  week,  90  per  cent,  at  the  end  of 
the  second  week,  and  practically  all  at  the  end  of  12  weeks.  They  con- 
sider that  we  may  be  sure  that  in  nature  the  destruction  would  exceed 
rather  than  fall  short  of  these  figures,  for  the  experiments  were  made 
in  a  test-tube  where  all  the  bacteria  are  imprisoned,  while  in  nature  per- 
haps 90  per  cent,  are  extruded  during  the  purifying  process  of  freezing. 

As  water  crystallizes  it  excludes  suspended  matter  and  even  dissolved 
substances.  The  extent  to  which  water  thus  purifies  itself  depends,  how- 
ever, upon  conditions,  for  under  certain  circumstances  the  impurities 
may  be  entangled  or  even  concentrated  during  the  process  of  freezing. 

S.  C.  Keith  ^"  considers  that  low  temperatures  alone  do  not  destroy 
bacteria.  On  the  contrary,  they  appear  to  favor  bacterial  longevity, 
doubtless  by  diminishing  destructive  metabolism.  Frozen  food  mate: 
rials,  such  as  ice  cream,  milk  and  egg  substance,  favor  the  existence  of 
bacteria  at  low  temperatures,  not  because  they  are  foods,  but  apparently 
because  they  furnish  physical  conditions  somewhat  protective  to  the 
bacteria.  It  seems  likely  that  water-bearing  food  materials  freeze  in 
such  a  way  that  most  of  the  bacteria  are  extruded  from  the  water  crys- 
tals with  other  non-aqueous  materials  (including  air)  and  the  bacteria 
then  lie  in  or  among  these  substances  without  being  crushed  or  otherwise 
injured.  In  pure  water,  and  above  all,  in  water  in  which  the  whole  mass 
becomes  solidly  crystalline,  the  bacteria  have  no  similar  refuge,  but  are 
caught  and  ultimately  mechanically  destroyed  between  the  growing  crys- 
tals. This  explanation  would  account  in  part  for  the  absence  of  live 
bacteria  in  clear  ice,  their  comparative  abundance  in  "snowj'"  ice  and 
"bubbly"  ice,  and  also  the  fact  that  the  more  watery  food  materials 
when  frozen  contain  the  fewest,  and  the  least  watery  the  most  living 
bacteria.  At  low  temperatures  metabolism  ceases  and  the  bacteria  con- 
tinue to  exist  in  a  state  of  suspended  vitality  similar  to  that  exhibited 
by  many  other  and  higher  plants  which,  in  the  far  north,  are  subject, 
without  apparent  injury,  for  long  periods  to  temperatures  much  below 
the  freezing  point  of  water. 

Hilliard  and  Davis  ^^  state  that  intermittent  freezing  exerts  a  more 
etfective  germicidal  action  than  continuous  freezing.     The  reduction  is 

^Sedgwick,  W.  T.,  and  Winslow,  C.  E.  A.:  (1)  "Experiments  on  the  Effect 
of  Freezing  and  Other  Low  Temperatures  upon  the  Viability  of  the  Bacillus  of 
Typhoid  Fever,  with  Considerations  Regarding  Ice  as  a  Vehicle  of  Infectious  Dis- 
ease." (2)  "Statistical  Studies  on  the  Seasonal  Prevalence  of  Typhoid  Fever  in 
Various  Countries  and  Its  Relation  to  Seasonal  Temperature."  2Iem.  Am.  Acad. 
Arts  and  Set..  Vol.  XII.  Xo.  5,  Aug.,  1902.  Summary,  Boston  Sac.  Med.  Sci., 
1899-1900,  Vol.  R^  p.  181. 

^  Science,  N.  8.,  Vol.  XXXVII,  No.  962,  pp.  877-879,  .June  6,  1913. 

^^Journ.  of  Bacteriologi/,  Julv.  1918.  VIII.  4,  p.  423. 


1186 


WATEE  AND  ITS  RELATION  TO  DISEASE 


much  less  in  milk  and  cream  than  in  pure  tap  water.  The  degree  of 
cold  below  freezing  is  not  a  very  important  factor  in  the  destruction  of 
bacteria.  The  bacteria  are  probably  killed  by  crushing  in  the  crystal- 
lization rather  than  by  the  cold,  or  by  the  "shock"  of  freezing  and  re- 
freezing. 

It  is  necessary  to  distinguish  between  natural  ice  and  manufactured 
ice. 

Natural  Ice. — Natural  ice  should  be  harvested  from  water  of  good 
sanitary  quality  and  handled  in  a  cleanly  manner.  Even  when  natural- 
ice  is  obtained  from  a  polluted  water  the  danger  is  greatly  reduced,  not 
only  because  ice  purifies  itself  in  freezing,  but  because  natural  ice  is 
usually  stored  weeks  and  months  before  it  is  used.  There  are  plenty 
of  clean,  fresh  streams,  lakes  and  ponds  from  which  an  abundant  supply 
may  be  obtained.  It  is  comparatively  easy  to  protect  most  ponds,  from 
which  ice  is  harvested,  from  undesirable  pollution.  Under  natural  con- 
ditions the  surface  layer  of  ice  contains  most  of  the  impurities  and  the 
lower  layers  are  relatively  purer,  for  the  reason  that  ice  grows  from 
above  downward  and  extrudes  both  suspended  and  dissolved  matters; 
the  surface,  however,  receives  additional  contamination  from  the  dust, 
snow,  flooding  and  other  sources.  It  is,  therefore,  good  practice  to  plane 
the  surface  of  snow  ice. 

The  fact  that  natural  ice  is  usually  purer  than  the  water  from  which 
it  is  taken  is  shown  by  the  following  analyses  which  give  the  chemical 
and  bacterial  composition  of  natural  ice  and  the  water  from  which  it 
was  frozen.    In  this  case  the  water  was  a  sewage-polluted  stream: 


Ice 
3  to  6  Inches  Thick 

Water 

Free  ammonia 

.008—       .034 
.156—       .214 
.05  —       .20 
2.0     —     3.0 
11.0     —  28.5 
30.       —210. 
10  c.  c— 10  c.  c. 

.016—       .136 
.230—       .726 
.0     —       .050 

0.8     —     3.50 
18.0    —  34.0 

2.       —  60. 

0.       —     0. 

.460— 

.146— 

.350— 

4.500— 

57.000— 

5200.       — 

1.       — 

.006— 

.116— 

.260— 

5.500— 

58.500— 

2500.       — 

1.       — 

.084 

Albuminoid  ammonia 

Nitrates 

.276 

.480 

Chlorin 

6.000 

Hardness 

60.000 

Bacteria  per  c.  c 

13000. 

Bacillus  coli  in 

.1 

Free  ammonia 

.038 

Albuminoid  ammonia 

Nitrates 

.166 
.400 

Chlorin 

Hardness 

62.000 

Bacteria  per  c.  c 

3900. 

Bacillus  coli  in 

0.1  c.  c. 

The   chemical  figures  in  this  table  are  in  parts  per  million. 


The  reduction  in  the  number  of  bacteria  is  noteworthy.  It  will  be 
noticed  that  there  was  no  diminution,  rather  an  increase  in  the  free  and 
albuminoid  ammonia. 


ICE 


118^ 


Manufactured  Ice. — ^ranufactured  ice  is  now  universally  made  by  the 
ammonia  prucess.  The  condensed  ammonia  in  expanding  requires 
heat  which  it  takes  from  surrounding  objects  and  in  this  way  the  water 
is  frozen.  There  are  two  distinct  processes;  one  known  as  "can  ice"  and 
the  other  as  "plate  ice."  In  the  first  case  the  freezing  takes  place  in 
rectangular  cans,  the  water  freezes  from  the  sides  of  the  can  toward  the 
center,  and  the  impurities  are  extruded  and  concentrated  in  the  core, 
which  is  often  visible  in  a  cake  of  can  ice.  In  making  can  ice  the  water 
must  first  be  distilled  or  boiled  in  order  to  drive  out  the  air,  else  the 
resulting  product  will  be  bubbly.  Plate  ice  is  made  by  freezing  water 
in  large  shallow  tanks.  The  water  freezes  upon  the  surface  and  when 
of  sufficient  thickness  is  cut  out  and  removed  in  blocks.  In  this  method 
it  is  not  necessary  to  distill  or  boil  the  water  for  the  reason  that  the 
air  is  extruded  naturally  during  the  process  of  freezing.  Plate  ice 
should  be  made  from  water  of  good  sanitary  quality,  especially  as  it  is 
not  usually  stored  a  long  time  before  it  is  used. 

When  ice  is  made  from  distilled  or  boiled  water  it  should  be  above 
reproach.  I  have  found,  however,  that  manufactured  ice  may  contain 
more  bacteria  than  the  water  from  which  it  was  made.  This  is  due  to 
uncleanly  methods.  Thus  six  specimens  of  plate  ice  made  from  water 
containing  64  microorganisms  per  cubic  centimeter  and  no  colon  bacilli 
gave  the  following  results : 


Number  of 
Sample 

Manufacturer 

Organisms  per 
Cubic  Centimeter 

Colon  Bacillus 

24 

C.  P.  Co 

4.5.5 
5,000 
230 
650 
470 
8 

Absent 

29 

C.  P.  Co 

In  1  c.  c. 

26 

G.  Ice  Co 

In  10  c.  c. 

27 

G.  Ice  Co 

Absent 

32 

C.-S.    Co 

Absent 

34 

P.  Ice  Co 

In  1  c.  c. 

The  laborers  who  work  "on  ice,"  as  it  is  termed,  scrape  considerable 
amounts  of  dirt  from  their  shoes  in  walking  over  the  cans  and  tanks, 
and  pollution  takes  place  from  other  sources. 

The  chemical  examination  of  manufactured  ice  may  show  conspicu- 
ously less  total  solids,  less  chlorin  and  less  nitrates  than  found  in  the 
water  from  which  it  was  made.  On  the  other  hand,  it  may  be  very  high 
in  free  ammonia.  This  is  accounted  for  by  the  fact  that  there' is  always 
some  leakage  of  this  gas  about  ice  factories  using  the  ammonia  process. 
Sometimes  ammonia  occurs  in  such  quantities  as  to  impart  a  distinctly 
alkaline  taste  to  the  manufactured  ice. 

There  is  no  excuse  for  uncleanly  methods  in  handling  ice  that  is 
used  on  or  in  our  foods.  The  fact  that  surface  impurities  may  be  washed 
from  a  cake  of  ice  is  no  reason  for  dragging  it  over  sputum-laden  pave- 


1188  WATER  AND  ITS  RELATION  TO  DISEASE 

ments,  over  dirty  railroad  platforms,  and  similar  methods  familiar  to 
all.  The  general  use  of  ice  is  a  modern  innovation.  It  has  come  into 
vogue  within  the  past  100  years.  For  the  uses  of  ice  as  a  preservative 
see  page  730. 

Ice  and  Disease. — A  search  of  the  literature  discloses  but  few  in- 
stances of  disease  attributable  to  impurities  in  ice.  While  the  experi- 
mental evidence  indicates  that  there  is  a  quantitative  reduction  of  the 
number  of  bacteria  in  freezing,  and  that  the  imprisoned  bacteria  gradu- 
ally die,  nevertheless  experience  has  shown  that  low  temperatures  alone 
cannot  be  depended  upon  to  remove  the  danger  of  typhoid  infection. 
For  example,  we  have  the  water-borne  epidemic  in  Plymouth,  Pa.,  in 
1885,  presumably  produced  from  the  frozen  accumulation  of  typhoid 
excrement  from  a  single  case.  Very  similar  to  the  Plymouth  outbreak 
was  that  at  New  Haven,  Conn.,  in  1901.  In  only  a  few  isolated  in- 
stances, however,  has  ice  itself  been  accused  of  being  the  vehicle-by  which 
the  infection  of  typhoid  fever  has  been  spread.  It  appears  probable 
that  milder  intestinal  diseases  may  be  caused  by  highly  polluted  ice,  of 
which  the  Rye  Beach  epidemic,  studied  by  Nichols  ^^  of  Boston  in  1875, 
is  a  point  in  evidence. 

Park  ^^  (1901)  described  an  epidemic  which  was  believed  to  have  had 
its  origin  in  ice  obtained  from  a  pond  in  which  it  was  shown  that  the 
excrement  from  a  patient  sick  with  typhoid  fever  had  been  thrown  while 
the  pond  was  covered  with  ice. 

In  the  second  annual  report  of  the  Board  of  Health  of  Connecticut 
for  1882  an  interesting  single  case  of  typhoid  fever  is  cited  as  probably 
derived  from  ice. 

Dorange  ^*  (1898)  described  an  epidemic  of  typhoid  fever  attributed 
to  ice  among  eight  lieutenants  in  a  regiment  stationed  at  Rennes  in  the 
autumn  of  1895.  The  implication  of  the  ice  in  this  instance  rests  upon 
a  doubtful  chain  of  evidence,  however,  and  no  mention  is  made  of  other 
possible  factors. 

Hutchins  and  Wheeler  ^^  (1903)  report  an  epidemic  of  typhoid  fever 
in  the  St.  Lawrence  State  Hospital,  three  miles  beloAv  Ogdensburg, 
N.  Y.,  which  seems  to  have  been  due  to  impure  ice.  The  disease  was 
endemic  in  the  hospital  for  ten  years,  increasing  from  two  cases  with 
the  opening  of  the  hospital  in  1890  to  forty  cases  in  1900.  Although 
the  water  supply,  tested  bacteriologically  and  chemically,  gave  negative 
results,  all  observers  agreed  that  the  disease  was  water-borne.     In  De- 

^  Nichols,  A.  H. :  "Report  on  an  Outbreak  of  Intestinal  Disorder  Attrib- 
utable to  the  Contamination  of  Drinking  Water  by  Means  of  Impure  Ice," 
Seventh  Ann.  Rep.,  S.  B.  H.,  Mass.,  1876,  p.  467. 

^  Park,  W.  H. :     yirclioic-IIirsch's  Jahrhericht  f.  1901,  p.  16. 

^^  Dorange :  "Epidemie  de  Fifevre  Typhoide  du  a  I'lngestion  de  Glace  Im- 
pure," Rev.  d'Eyg.,  Vol.  XX,  1898,  p.  295. 

'^Hutchins,  R.  H.,  and  Wheeler.  A.  W. :  "An  Epidemic  of  Typhoid  Fever 
Due  to  Impure  Ice,"  Am.  Jour.  Med.  Sci.,  Vol.  CXXVI,  1903,  p.  680. 


TCP]  1189 

cember,  1!)00,  tlio  source  of  the  water  supjjly  was  eliaii<re(l  to  the  Oswe- 
^ateliie  l»i\('i\  a  small  Ailiroiulack  stream  sii|)|»lyiii<i;  ()^M|e!isi)urf^.  This 
|iraeti(ally  put  a  stop  to  the  disease,  for  there  were  no  eases  of 
typhoid  tlial  were  not  clearly  contracted  elsewhere  until  October, 
190-^. 

Following  this  eigiit  ])ersons  were  attacked,  seven  of  whom  were 
employees  in  the  dining-room.  It  seems  the  milk  "could  not  have  been 
infected."  'J'he  water  was  excluded  and  other  sources  studied,  with 
negative  results.  The  ice  fell  under  suspicion.  It  had  recently  been 
taken  from  a  newly  opened  ice-house.  The  ice  had  been  harvested  from 
the  St.  Lawrence  River  at  about  the  same  spot  as  the  ice  previously 
used.  It  was  gathered  in  February  and  consequently  had  been  stored 
for  seven  months.  This  ice  disclosed  a  contamination  of  30,400  bacteria 
per  cubic  centimeter  on  agar  plates  and  50,400  on  gelatin.  Of  eight 
fermentation  tubes  three  showed  the  presence  of  colon  bacilli. 

The  stock  of  ice  was  then  examined.  In  the  center  of  certain  cakes 
were  found  foreign  substances  in  the  form  of  black  or  dark  brown 
granular  matter.  Examined  under  the  microscope,  this  matter  was 
found  to  be  teeming  Avith  bacteria,  from  which  both  the  colon  and 
typhoid  bacillus  were  isolated  in  pure  culture. 

"With  the  discontinuance  of  the  use  of  this  infected  ice  the  epidemic 
gradually  subsided.  There  were  in  all  thirty-nine  cases.  The  evidence 
of  this  outbreak  was  studied  by  Hill,  who  doubted  the  relation  of  the 
ice  to  the  disease. 


REFERENCES 

Report  of  the  Committee  of  the  American  Public  Health  Assn.,  Standard 

Methods  of  Water  Analysis.    3rd  Ed.,  1917. 
Whipple,  G.  C.  :     The  Microscopy  of  Drinking  Water.     3rd  Ed.     N.  Y., 

1914.    Wiley  &  Sons. 
Prescott,  S.  C,  and  Winslow,  C-E.  A. :    Elements  of  Water  Bacteriology. 

3rd  Ed.    N.  Y.,  1913.     Wiley  &  Sons. 
Savage,   W.    G.  :      The   Bacteriological    Examination    of   Water    Supplies. 

Phila.,  1906.    Blakiston's  Son  &  Co. 
Thresh,  J.  C. :     The  Examination  of  Waters  and  Water  Supplies.     2nd 

Ed.  Phila.,  1914.    Blakiston's  Son  &  Co. 
TuRNEAL-RE,  E.  E.,  and  Elssell,  H.  L.  :     Public  Water  Supplies.     N.  Y., 

1907.    Wiley  &  Sons. 
Masox,  W.  p.  :     Water  Supply.    3rd  Ed.   N.  Y.,  1902,  Wiley  &  Sons. 
Hazex,  A. :    Clean  Water  and  How  to  Get  It.    X.  Y.,  1916.    Wiley  &  Sons. 
Don,  J.,  and  Chisholm,  J.:     Modern  Method  of  Water  Purification.     2nd 

Ed.     X.  Y.,  1913.     Longmans,  Green  &  Co. 
Johxsox,  George  A. :     The  Purification  of  Public  Water  Supplies.     U.  S. 

Geological  Survey,  Water-Supply  Paper  315,  1913. 


1190  WATER  AND  ITS  RELATION  TO  DISEASE      . 

For  typical  and  composite  analyses  see: 

Clarke:     The  Data  of  Geochemistry,  Chemistry  and  Physics,  54,  U.   S. 

Geological  Survey,  1908,  Bull.  No.  330,  Series  E. 
The  Municipal  Water  Supplies  of  Illinois.     Bull,  of  the  111.  State  Board 

of  Health,  June,  1908,  IV,  6. 
Annual  Reports  of  the  Massachusetts  State  Board  of  Health. 
Bulletins  of  the  U.  S.  Geological  Survey.     Water  supply  papers. 


SECTIOX  IX 

SEWAGE  DISPOSAL 

By  Gkouge  C.  Whipple 
Professor  of  Samtarij  Engineeri?ig  in  (he  Harvard  Enginecrinfj  School 

Importance  of  Speedy  Removal  of  Fecal  Matter. — The  basic  principle 
that  underlies  all  methods  of  sewage  disposal  is  to  get  rid  of  the  sewage 
as  speedily  as  possible,  with  the  least  nuisance  to  the  smallest  number 
of  people,  with  the  least  damage  to  health  or  property,  and  at  the  small' 
est  cost.  Experience  has  shown  that  failure  to  remove  human  excre- 
mentitious  matter  promptly  and  properly  from  a  community  is  a  menace 
to  the  public  health.  Privies  and  cesspools  should  not  be  tolerated  in 
a  closely  built  up  area.  Unless  more  than  ordinary  care  is  exercised 
their  existence  may  give  opportunity  for  the  spread  of  disease  by  insects 
and  animals  and  by  the  pollution  of  local  wells.  Statistics  show  that  the 
abandonment  of  privies  and  the  substitution  of  sewage  systems  have 
reduced  the  general  death  rate  in  many  a  city.  Thus  Dr.  Boobyer  has 
reported  that  at  Xottiugham,  England,  in  a  period  covering  ten  years 
typhoid  fever  cases  occurred  in  2.7  per  cent,  of  the  houses  that  were 
provided  with  privies,  in  0.83  per  cent,  of  the  houses  where  pail  closets 
were  used,  and  in  only  0.18  per  cent,  of  the  houses  that  had  water-closets 
connected  with  the  sewers.  Similarly,  Dr.  Porter  has  stated  that  in 
Stockport,  England,  during  the  years  1893-7  typhoid  fever  occurred  in 
3.4  per  cent,  of  the  houses  where  there  were  privies,  but  in  only  1.2  per 
cent,  of  the  houses  that  had  sewer  connections,  these  figures  being  based 
on  a  study  of  over  18,000  houses.  In  Munich,  when  sewers  were  con- 
structed in  185G-9  the  typhoid  fever  death  rate  fell  from  2-42  to  166  per 
100,000;  later,  after  an  improved  water  supply  and  other  sanitary 
reforms  had  been  brought  about,  the  typhoid  fever  death  rate  fell  to  a 
much  lower  figure. 

By  taking  special  precautions  against  the  spread  of  infection  through 
the  agency  of  flies,  either  by  preventing  their  breeding  or  preventing 
them  from  obtaining  access  to  fecal  matter,  and  by  closing  polluted  wells 
in  crowded  districts,  the  dangers  from  privies  and  cesspools  may  be 
greatly  reduced.^  Sometimes  it  is  wiser  to  do  this  in  villages  and 
small  towns  than  to  go  to  the  expense  of  introducing  sewage  systems, 

^  For  the  dangers  of  polluting  the  soil  with  feces  see  chapter  on  Soil. 

1191 


1192  SEWAGE  DISPOSAL 

with  perhaps  the  attendant  difficulty  and  expense  of  purifying  the  sew- 
age after  collection. 

Ordinarily  in  this  country  sewerage  systems  and  puhlic  water  sup- 
plies are  introduced  in  towns  where  the  population  exceeds  about  3,000. 
and  in  smaller  places  if  the  population  is  concentrated.  This  is  so  gen- 
erally true  that  towns  that  have  less  than  2,500  or  3,000  population  are 
classed  as  '"rural,"  the  larger  towns  being  called  "urban." 

Dry  Earth  System. — The  dry  earth  system,  much  in  vogue  before  the 
general  introduction  of  the  water  carriage  system,  is  now  but  little  used ; 
yet  under  some  conditions  it  has  advantages.  With  this  method  the 
water-closets  are  replaced  by  removable  water-tight  receptacles,  or  pails, 
in  which  the  fecal  matter  is  kept  covered  with  dry  earth,  ashes,  or  some 
similar  material.  The  pails  are  collected  at  frequent  intervals,  prefer- 
ably daily,  and  a  clean,  empty  pail  substituted.  The  material  is  usually 
buried  in  the  ground.  For  isolated  houses,  for  temporary  camps  of  la- 
borers, for  small  scattered  summer  colonies,  and  for  houses  situated  near 
streams  or  lakes  used  for  public  water  supplies  this  method  is  satisfac- 
tory, and  is  often  the  best  possible  method,  provided  that  proper  care  is 
taken  by  the  user  and  the  collector.  Cleanliness  in  handling,  the  pro- 
tection of  the  material  against  flies,  regular  and  frequent  collection,  occa- 
sional disinfection  of  the  pails,  and  prompt  burial  in  proper  soil  are  es- 
sential to  success. 

Water  Carriage  System. — So  accustomed  are  we  to  present  methods 
of  sewage  that  it  is  hard  to  realize  that  the  system  of  water  carriage 
of  fecal  matter  is  less  than  a  century  old.  Up  to  1815  the  public  drains 
of  London  were  not  permitted  to  receive  excreta;  in  Boston  fecal  mat- 
ter was  rigidly  excluded  from  the  sewers  until  1833;  and  in  Paris  this 
was  the  case  even  up  to  1880. 

Following  the  report  of  the  Health  of  Towns  Commission  in  Eng- 
land in  1844,  water-closets  were  rapidly  introduced,  and  in  1847  their 
connection  with  the  sewers  was  required  by  law.  The  modern  sewerage 
system,  therefore,  dates  from  about  the  middle  of  the  last  century. 
Chesbrough  designed  a  general  sewerage  system  in  Chicago  in  1855. 
Boston's  first  sewerage  commission  was  appointed  in  1875.  Baltimore 
was  without  a  sewerage  system  until  within  a  few  5^ears,  and  even  as 
late  as  1912,  the  system  was  not  fully  completed,  and  many  houses  were 
not  connected  with  it. 

The  introduction  of  the  water  carriage  system  accomplished  its  pur- 
pose and  effectually  did  away  with  the  offensive  accumulations  of  filth 
around  city  dwellings,  but  it  gave  rise  to  a  series  of  other  problems  that 
sanitarians  are  now  endeavoring  to  solve.  The  sewers  were  naturally 
built  to  discharge  their  contents  into  the  nearest  available  body  of  water 
— into  river,  lake,  or  harbor,  according  to  the  situation  of  the  city. 
Where  the  streams  were  relatively  large,  no  nuisance  was  caused  by 


SEWAGE  DISPOSAL  1193 

doing  this,  but  wliorc  tlic  stR-aiiis  were  rclativi'iy  small  ["oul  ((jiKJitioiis 
soon  arose,  and  it  hecanie  nocessarv  to  reduce  the  amount  of  organic  mat- 
ter discharged  from  the  sewers  iuto  tiicni.  Water  .--upplies  also  became 
infected  and  in  some  instances  great  epitlemics  followed,  while  infection 
was  spread  in  other  minor  ways.  Thus  the  problem  of  the  removal  of 
fecal  matter  was  sometimes  solved  at  one  place  only  to  reappear  else- 
where. Litigation  also  arose  between  riparian  owners  along  the  water 
courses,  invulving  damages  caused  by  the  pollution  of  the  water. 

The  problem  has  thus  broadened  from  a  local  one  to  one  in  which 
different  cities  and  even  different  states  have  become  involved.  It  is  to 
the  solution  of  these  problems  of  maintaining  our  streams  and  lakes 
and  harbors  in  a  satisfactory  condition  that  sanitarians  are  now  earnestly 
devoting  themselves. 

Separate  and  Combined  Systems. — The  sewers  and  drains  of  a  city 
are  used  for  various  purposes,  the  two  most  important  ones  being  the 
removal  of  domestic  house  sewage,  and  the  rain  water  that  falls  on  roofs^ 
yards,  sidewalks,  and  streets.  Sometimes  the  same  system  of  sewers  is 
used  to  carry  both  domestic  sewage  and  storm  water.  Such  is  called 
a  combined  system.  Sometimes  the  storm  water  is  carried  in  relatively 
large  drains,  or  allowed  to  flow  along  in  the  street  gutters,  while  the 
domestic  sewage  is  carried  in  a  separate  system  of  sewers  of  smaller 
size.  The  choice  of  the  two  systems  depends  upon  the  local  situation,  but 
in  general  the  following  conditions  control. 

The  combined  system  is  the  older  and  the  one  more  commonly  used 
in  large  cities  and  crowded  communities,  for  it  is  cheaper  than  a  dual 
system,  where  both  separate  sewers  for  the  house  sewage  and  drains  for 
the  storm  water  are  required.  Where  the  storm  water  can  be  allowed 
to  ilow  off  in  the  gutters  without  serious  inconvenience  from  flooding 
the  separate  system  is  cheaper,  as  the  pipes  are  smaller.  Where  the 
sewage  must  be  pumped  or  carried  long  distances  in  pipes  or  puri- 
fied by  expensive  methods  the  advantages  lie  with  the  separate  sys- 
tem, as  the  quantity  of  sewage  is  less  and  its  flow  more  constant.  From 
the  sanitary  standpoint  either  method  is  satisfactory.  The  choice 
of  the  two  systems  depends  upon  various  engineering  questions  involv- 
ing cost,  so  that  the  matter  is  one-  that  should  be  submitted  to  an 
engineer. 

Sewerage  systems  consist  of  house  sewers  or  house  drains  that  convey 
the  sewage  to  the  street  sewers  or  lateral  sewers.  These  unite'  in  what 
are  termed  district  sewers,  and  the  latter  sometimes  unite  in  one  or 
more  trunk  seivers  of  large  size.  Relief  seivers  are  sometimes  built 
parallel  to  old  sewers  of  inadequate  capacity,  and  storm  sewers  are  some- 
times built  to  carry  away^  surface  water,  while  underdrains  may  be  used 
in  connection  with  the  separate  system  to  remove  some  of  the  ground 
water.     Intercepting  sewers  are  sometimes  built  parallel  to  a  stream 


1194  SEWAGE  DISPOSAL 

for  collecting  the  sewage  from  a  number  of  district  sewers  and  convey- 
ing it  to  a  safer  point  of  discharge.  When  intercepting  sewers  are  used 
with  the  combined  system  they  are  not  designed  to  carry  all  of  the  flow 
at  times  of  storm,  but  are  provided  with  overflows,  so  that  the  excess  of 
storm  water  discharges  into  the  river  at  various  points  of  overflow. 
This  is  a  matter  of  importance  and  one  to  be  remembered  in  connection 
with  the  purification  of  sewage,  for  the  quantity  of  sewage  that  passes 
these  overflows  at  times  of  heavy  rain  may  amount  to  25  per  cent,  or  50 
per  cent,  or  more  of  the  sewage,  and  during  the  course  of  the  year  may. 
amount  to  from  2  per  cent,  to  5  per  cent.,  or  even  more,  of  the  entire 
sewage  of  the  city.  Such  overflow  water  is  almost  never  purified.  At 
Birmingham,  England,  Watson  has  estimated  that,  in  spite  of  the  elabo- 
rate provisions  for  purification,  a  large  part  of  the  city's  sewage  is 
at  times  discharged  untreated,  and  at  Milwaukee  the  Sewerage  Com- 
mission estimated  that  nearly  2  per  cent,  of  the  sewage  wouM  fail  to 
be  collected  by  a  very  liberally  designed  system  of  intercepting  sewers. 

Quantity  of  Sewage. — The  volume  of  sewage  flowing  in  a  separate 
system,  or  in  a  combined  system  during  dry  weather,  does  not  differ 
materially  from  the  water  consumption  of  the  city.  In  small  towns 
this  may  be  as  low  as  40  or  50  gallons  per  capita  daily,  although  ordi- 
narily it  is  rather  more  than  this.  In  large  cities  it  may  amount  to  from 
100  to  200  gallons  per  capita,  and  more  than  this  in  extreme  cases. 

Intercepting  sewers  are  commonly  designed  to  provide  for  a  flow  of 
300  to  400  gallons  per  capita  daily.  The  amount  of  storm  water  depends 
upon  climatic  conditions,  and  for  this  subject  engineering  books  should 
be  consulted.  The  flow  of  sewage  fluctuates  hourly,  and  the  maximum 
may  be  from  50  to  100  per  cent,  of  the  daily  average,  while  greater 
fluctuations  may  be  found,  especially  in  cities  where  large  quantities 
of  water  are  used  in  manufacturing. 

Composition  of  Sewage. — A  city's  sewage  consists  of  the  public  water 
supply  soiled  with  the  waste  products  of  human  life  and  refuse  from 
household  and  factory,  increased  by  a  certain  amount  of  ground  water 
which  leaks  into  the  sewers,  and,  in  the  combined  system,  by  varying 
quantities  of  rain  w^ater  and  street  wash.  Disintegrating  and  decom- 
posing as  it  flows,  the  sewage  gradually  becomes  a  more  or  less  homo- 
geneous suspension  of  fine  particles  in  water,  with  organic  and  mineral 
matter  in  solution.  The  longer  the  sewage  flows  or  stands,  the  more  its 
constituents  become  disintegrated;  fecal  matter  and  paper  become  un- 
recognizable as  such;  bacteria  increase  enormously,  and  assist  in  the 
breaking  down  of  the  complex  organic  compounds.  The  oxygen  orig- 
inally present  in  the  water  becomes  reduced  and  finally  disappears,  so 
that  from  a  fresh  condition  the  sewage  becomes  first  stale  and  then 
"septic."  Mixed  with  the  putrefying  organic  matter  and  the  swarming 
hosts  of  bacteria  harmlessly  engaged  in  their  beneficent  work  of  de- 


SEWAGE  DISPOSAL 


119; 


stroyin^  tho  organic  matter,  thore  may  be  also  bacteria  which  have  come 
from  persons  sick  with  tyi>lioi(l  fever,  dysentery,  cliolera.  tuberculosis, 
and   other  diseases. 

Sewa*,''e  is  obnoxious  to  the  senses  because  of  its  (leconii)osing  organic 
matter,  but  it  is  tbmgerous  to  health  because  of  the  possible  presence 
of  pathogenic  bacteria. 

Among  the  important  constituents  of  sewage  from  tlie  standpoint 
of  purification  are  urea,  various  proteid  substances  such  as  albumin, 
fibrin,  casein ;  starch,  sugar,  and  other  carbohydrates,  fats,  soaps,  and 
other  organii-  sul»stances.  Important  among  the  elements  present  in  the 
easily  decomposable  matter  are  nitrogen  and  sulphur.  The  concentra- 
tion of  these  substances,  that  is,  the  amount  present  in  a  given  volume 
of  sewage,  depends  upon  the  per  capita  volume  of  the  sewage  and  varies 
widely  in  ditt'erent  places.  Somewhat  more  constant,  however,  are  these 
constituents  when  compared  with  the  number  of  persons  dwelling  in 
houses  connected  with  the  sewers. 

The  following  figures  show  the  approximate  constituents  of  sewage 
expressed  in  terms  of  grams  per  capita  daily  and  in  parts  per  million 
when  the  volume  of  sewage  amounts  to  100  gallons  per  capita  daily. 

Estimated  Constituents  of  Average  Sewage 
{After  Fuller) 


Oxygen  consumed... 


Nitrogen  as. 


Chlorin . 

Fats . . . 


Two  minutes  boiling.  . 
Five  minutes  boiling.  . 

Free  ammonia 

Albuminoid  ammonia. 

Organic 

Total 


I 


Total 

Mineral 

Organic  and  volatile. 

Total 

Mineral 

Organic  and  volatile. 

Total 

Mineral 

Organic  and  volatile. 
Bacteria.  .322  billion  per  capita  daily. 


Dissolved  matter. 


Suspended  matters. 


Total  solids. 


Grams  per 
Capita  Daily  * 


15.0 

22.0 

7.0 

2.-5 

S.O 

15.0 

19.0 

19.0 

136.0 

99.0 

37.0 

66.0 

58.0 

40.0 

229.0 

L52.0 

77.0 


Parts  per 
MilUonf 


39.6 

58.0 

18.5 

6.6 

21.1 

39.6 

50.2 

50.2 

359.0 

261.0 

98.0 

246.0 

140.0 

106.0 

605.0 

402.0 

203.0 


*  These  figures  also  indicate  parts  per  million   if  the  per  capita   volume   of  sewage  is 
264  gallons  per  day. 

t  Assuming  a  per  capita  volume  of  100  gallons  per  day. 


The  methods  of  sewage  analyses  at  present  are  practically  the  same 
as  those  used  in  the  analysis  of  water  (page  1048).  They  are  not  in 
all  respects  satisfactory. 


1196  SEWAGE  DISPOSAL 

Ventilation  and  Flushing  of  Sewers. — The  old  bugaboo  of  sewer  gas 
that  frightened  our  fathers  before  the  days  of  bacteriology  is  no  longer 
feared  by  sanitarians,  although  its  influence  still  pervades  the  antique 
plumbing  regulations  in  force  in  many  places.  It  is  indeed  desirable 
to  keep  the  air  of  sewers  from  mixing  with  the  air  we  breathe — the 
debilitating  influence  of  all  impure  air  should  be  avoided — but  the 
danger  of  any  one's  becoming  infected  with  the  germs  of  disease  by 
breathing  sewer  gas  is  negligible. 

The  water  carriage  system  offers  practically  no  danger  to  the  public, 
health  during  the  transmission  of  sewage.  In  many  cities  the  sewers 
are  ventilated  by  allowing  a  free  flow  of  air  from  the  sewers  through 
the  house  drains,  the  individual  house  fixtures  only  being  trapped.  This 
method  is  apparently  safe,  provided  the  plumbing  is  of  substantial 
character.  If  it  is  not,  it  is  better  to  place  a  trap  upon  the  main  house 
drain.  It  is  believed  that  in  the  future  plumbing  will  develop  along  the 
lines  of  simplicity  and  improved  quality  of  materials  and  work,  and 
that  the  present  complicated  system  of  traps  and  vents  will  be  abandoned. 

The  catch-basins,  through  which  the  street  wash  enters  the  sewers, 
are  trapped  against  the  egress  of  sewer  air.  The  water  that  stands  in 
them  is  a  prolific  breeding  place  for  mosquitoes.  Unless  catch-basins 
are  frequently  cleaned,  the  accumulating  organic  matter  putrefies  and 
the  odor  from  it  may  be  worse  than  that  of  the  air  of  the  sewer.  Catch- 
basins  are  being  omitted  from  some  of  the  best  designed  modern  sewer- 
age systems. 

Combined  sewers  are  sufficiently  flushed  by  the  storms.  Separate 
sewers,  if  laid  on  proper  grades,  need  little  or  no  flushing.  It  has-been 
common  in  the  past  to  employ  flush  tanks  at  the  end  of  lateral  sewers, 
but  these  are  troublesome  and  waste  much  water. 

STREAM  POLLUTION 

Sewage  Disposal  by  Dilution. — The  readiest  method  of  sewage  dis- 
posal, and  the  one  which,  until  within  the  last  few  years,  has  been  uni- 
versally practiced  in  this  country,  is  to  allow  the  sewage  to  flow  with- 
out treatment  into  the  nearest  stream  or  lake  or  harbor.  This  method 
is  known  as  disposal  by  dilution.  It  is  a  proper  and  satisfactory  method 
of  disposal  where  the  dilution  is  sufficient.  It  is,  however,  capable  of 
abuse,  and  from  its  abuse  water  supplies  may  become  polluted,  oyster 
beds  may  become  infected,  and  in  severe  cases  streams  may  be  so  over- 
loaded with  sewage  as  to  become  an  offense  to  sight  and  smell.  Properly 
restricted,  however,  the  sewage  is  effectively  disposed  of,  the  heavy 
particles  settle  to  the  bottom,  the  organic  matter  is  oxidized  by  the  oxy- 
gen dissolved  in  the  water,  and  the  bacteria  are  gradually  dispersed,  con- 
sumed by  other  organisms,  killed  by  sunlight,  or  otherwise  destroyed. 


STIJKAM    I'ol.Ll  'I'lON  1197 

Tlieso  agencies  bring  about  llie  jjhenonienon  known  as  the  self-j)urifica- 
tion  of  streams.     See  page  1109. 

While  it  is  true  that  hygienic  and  sanitary  considerations  materially 
affect  the  use  of  rivers  and  waterways  as  vehicles  for  the  reception,  trans- 
mission, and  ultimate  disposal  of  sewage,  the  question  is  primarily  an 
economic  one.  The  power  of  streams  to  transport  suspended  matter  and 
the  ability  of  natural  bodies  of  water  to  oxidize  and  destroy  offensive 
substances  represent  a  natural  resource  that  should  be  utilized  just  as 
far  as  this  can  be  done  with  safety  and  without  offense.  For  each  river 
there  is  a  limit  to  the  amount  of  permissible  pollution.  The  reasons  for 
this  limit  are  not  the  same  in  all  cases^  but  vary  according  to  the  use 
that  is  made  of  the  water  of  the  river,  and  no  universal  standard  can 
be  wisely  set  up  or  maintained.  When  the  extent  of  the  pollution  is 
such  as  to  affect  public  health  in  any  way  by  any  reasonable  use  of  the 
river  the  sanitary  aspect  of  the  situation  should  control. 

The  minimum  amount  of  water  required  to  dilute  sewage  in  stream's 
is  usually  considered  to  be  from  2.5  to  -1  cubic  feet  per  second  for  the 
sewage  of  one  thousand  people.  The  Chicago  Drainage  Canal  was  de- 
signed on  the  basis  of  3.3  cubic  feet  per  second  for  one  thousand  people. 
Rapidly  flowing  streams  require  less  than  this,  as  much  oxygen  is  ab- 
sorbed from  the  air.  Stagnant  streams  may  require  considerably  more 
water.  The  presence  of  certain  trade  wastes  in  the  sewage  may  mate- 
rially increase  the  dilution  required.  For  example,  oily  matters  that  float 
on  the  surface  and  form  scums  may  interfere  with  the  absorption  of 
oxygen  from  the  air. 

In  lakes  the  relation  between  the  sewer  outfall  and  the  intake  of 
the  water  works  must  be  carefully  considered,  and  the  dispersion  of 
bacteria  by  currents  induced  by  the  wind  and  temperature  must  be 
studied.  In  harbors  the  effects  of  the  tides  must  be  taken  into  ac- 
count. 

Dissolved  Oxygen  in  Water. — The  aiuount  of  oxygen  dissolved 
in  water  depends  largely  upon  its  temperature,  as  shown  by  the  figures 
in  the  table  on  page  1198. 

Water  near  the  freezing  point  will  hold  nearly  twice  as  much  oxygen 
as  at  prevailing  summer  temperatures.  The  dilution  required  in  sum- 
mer is  therefore  greater  than  in  winter,  and  in  some  situations  it  would 
be  logical  to  construct  purification  plants  to  be  operated  during  the 
summer  only,  thus  making  a  material  saving  in  cost. 

Sea  water  dissolves  about  "20  per  cent,  less  oxygen  than  fresh  water. 

In  order  that  the  dissolved  oxygen  may  be  used  to  its  best  advantage, 
it  is  necessary  to  have  the  sewage  thoroughly  and  quickly  diffused 
through  the  water.  Otherwise  the  oxygen  near  the  point  of  discharge 
may  be  too  greatly  reduced,  and  nuisance  may  result,  even  though  there 
be  plenty  of  unusual  oxygen  near  by. 


1198 


SEWAGE  DISPOSAL 


Solubility  of  dissolved  oxygen  in  water — parts  per  million 


Temp.  "  C. 

Oxygen 

Temp.  °  C. 

Oxygen 

Temp.  °  C. 

Oxygen 

0 

14.70 

10 

11.31 

20 

9.19 

1 

14.28 

11 

11.05 

21 

9.01 

2 

13.88 

12 

10.80 

22 

8.84 

3 

13.50 

13 

10.57 

23 

8.67 

4 

13.14 

14 

10.35 

24 

8.51 

5 

12.80 

15 

10.14 

25 

8.35 

6 

12.47 

16 

9.94 

26 

8.19 

7 

12.16 

17 

9.75 

27 

8.03 

8 

11.86 

18 

9.56 

28 

7.88 

9 

11.58 

19 

9.37 

29 

7.74 

Necessity  of  Biological  Equilibrium. — It  is  becoming  recognized 
that  the  problem  of  sewage  disposal  by  dilution  is  largely  a  biological 
one.  The  decomposition  and  oxidation  of  the  organic  matter  in  sewage 
are  brought  about  by  bacteria,  and  the  bacteria  serve  as  food  for  proto- 
zoa and  other  forms  of  microscopic  animal  life.  The  dissolved  organic 
matter  in  sewage  serves  as  food  for  algae.  These  algae  and  protozoa 
are,  in  turn,  consumed  by  rotifers  and  Crustacea,  while  the  latter  form 
the  basis  of  the  food  supply  for  various  aquatic  animals  and  fishes.  Thus 
there  is  a  continuous  biological  cycle.  Again,  animal  forms  require 
oxygen  and  produce  carbonic  acid,  while  plants  consume  carbonic  acid 
and  produce  oxygen.^  Where  these  processes  occur  normally  and  with  a 
proper  equilibrium  maintained  between  animal  and  plant  life,  offensive 
conditions  do  not  result,  but  where  abnormal  conditions  are  produced, 
as,  for  example,  by  the  discharge  of  excessive  quantities  of  sewage  or 
trade  wastes  into  a  stream,  a  depletion  of  the  dissolved  oxygen  may 
follow,  or  there  may  be  an  over-production  of  algae,  so  that  the  condi- 
tions become  offensive.  It  is  coming  to  be  realized  that  in  order 
properly  to  determine  the  dilution  required  in  any  particular  case  the 
conditions  required  to  bring  about  this  condition  of  biological  equilibrium 
must  be  determined. 

Hygienic  Aspects  of  Stream  Pollution. — Considering  the  hygienic 
aspects  of  stream  pollution  with  special  reference  to  the  pollution  of 
water  supplies,  it  is  important  to  remember  that  the  typhoid  fever  bacilli 
do  not  multiply  in  the  ordinary  water  of  our  streams,  but,  on  the  con- 
trary, when  discharged  into  water  they  rapidly  diminish  in  number. 
After  a  week  not  more  than  10  per  cent,  may  remain  alive,  and  after 
a  month  not  more  than  1'  per  cent. 

It  follows  that  recent  pollution  is  the  most  dangerous,  and  that 
Water  stored  in  reservoirs  and  lakes  becomes  more  and  more  safe  for 
use  as  time  of  storage  increases.     The  longevity  of  the  typhoid  bacillus  is 

^'When  fish  die  in  sewage  polluted  water  it  is  usually  due  to  lack  of 
oxygen. 


STKKAM    roMJTTTON  1199 

much  greater  in  cold  water  than  in  warm  water.  Jleiice,  typhoid  fever 
epidemics  are  more  common  in  winter  than  in  summer,  and  in  northern 
climates  tiian   in   southern  climates. 


riiOTEGTION  AGAINST  POLLUTION 
WATER  FILTRATION 

Long  experience  in  this  country  and  a  much  longer  experience  in 
England  and  Germany  have  demonstrated  clearly  and  unmistakahly 
that  polluted  waters  can  he  and  arc  heing  constantly  purified  hy  means 
of  filtrati(m  to  such  an  extent  that  they  are  reliably  wholesome.  In 
Germany  the  typhoid  fever  death  rates  in  the  large  cities  have  ])een 
reduced  to  figures  far  1)el()w  those  of  American  cities.  In  Europe  it 
is  not  at  all  uncommon  for  the  typhoid  death  rate  to  remain  less  than 
10  per  100.000  for  ten  and  even  twenty  years  in  succession,  the  rate 
not  infrequently  dropping  as  low  as  3  and  -1  per  100,000.  There  the 
filtration  of  surface  water  is  required  by  law,  and  the  eflficiency  of  the 
filters  is  likewise  required  to  rise  to  a  certain  fixed  standard.  It  is 
worth  remembering  also  that  the  streams  of  Germany  are  far  from 
being  unpolluted  Math  sewage,  and  that  no  general  attempt  is  made  to 
provide  sewage  purification  works  of  high  bacterial  efficiency.  Only  in 
case  of  actual  epidemics  is  the  practice  of  disinfection  of  sewage  fol- 
lo^ved.  The  theory  that  water  filtration  is  superior  to  sewage  purifica- 
tion as  a  means  of  protecting  water  supplies  against  infection  appears 
to  prevail.     The  success  of  this  policy  has  been  amply  demonstrated. 

TREATMENT  OF  SEWAGE 

By  appropriate  processes  sewage  can  be  artificially  purified  so  that 
the  decomposable  organic  matter  is  removed  or  oxidized  and  the  bacteria 
removed  or  killed.  A  complete  purification  is  not  attempted  even  in 
the  best  conducted  plants,  as  the  processes  demanded  are  too  elaborate, 
too  expensive,  and  too  uncertain  of  results.  More  often  the  purifica- 
tion is  incomplete,  the  degree  of  purification  secured  being  adjusted  to 
the  particular  needs  of  the  situation.  In  the  past  sewage  treatment 
works  have  been  built  to  remove  as  much  of  the  decomposable  organic 
matter  as  was  necessary  to  enable  the  etfluent  to  be  discharged  into  some 
waterway  without  causing  offensive  conditions.  This  was  the  case  in 
Europe,  and  especially  in  England,  where  the  streams  are  relatively 
small  and  the  cities  relatively  large  and  the  amounts  of  trade  waste 
considerable. 

In  some  places  greater  emphasis  has  been  placed  on  the  removal  or 
destruction  of  pathogenic  bacteria,  with  the  object  of  protecting  oyster 
beds,  bathing  beaches,  or  reducing  the  "load"  on  water  filters. 


1200  SEWAGE  DISPOSAL 

The  degree  of  purification  thus  required  varies  all  the  way  from 
a  nearly  complete  purification  down  to  a  mere  straining  out  of  the 
grosser  solids. 

Fundamental  Principles  of  Sewage  Treatment.i — The  fundamental 
processes  in  sewage  treatment  are : 

(1)  Separation  of  the  suspended  matter  from  the  liquid  sewage. 

(2)  Destruction  of  the  putrescible  organic  matter  in  the  liquid 
sewage  looking  to  final  mineralization  by  the  processes  of  oxidation  and. 
bacterial  action. 

(3)  The  transformation  of  the  sewage  sludge  to  a  condition  of 
stability  and  inertness  by  bacterial  action,  with  or  without  oxidation. 

(4)  Destruction  or  removal  of  the  bacteria  from  the  liquid  effluent. 
The  processes  involved  may  be  classified  as  follows : 

(1)  Preparatory  processes,  such  as  screens,  detritus  tanks,  plain 
settling  tanks,  septic  tanks,  digestion  tanks,  chemical  precipitation  tanks, 
roughing  filters. 

(2)  Purification  processes,  such  as  sub-surface  irrigation,  broad 
irrigation,  intermittent  filtration,  contact  beds,  and  trickling  filters. 

(3)  Finishing  processes,  such  as  sedimentation  or  coarse  filtration, 
land  treatment,  disinfection. 

(4)  Sludge  disposal  by  digestion  tanks,  filter  presses,  drying  on 
land,  dumping  at  sea. 

These  processes  are  by  no  means  clear  cut.  They  overlap  at  many 
points;  they  are  used  singly  or  in  all  sorts  of  combinations. 

Preparatory  Processes — Screening. — Sewage  is  screened  to  remove 
the  larger  substances  that  might  injure  pumps,  clog  filters,  or  appear 
as  unsightly  litter.  Coarse  screens  consist  of  gratings  of  iron  bars; 
fine  screens  of  wire  cloth.  The  amount  of  material  screened  from 
sewage  varies  from  0.1  to  1.0  cubic  yard  per  million  gallons  of  sewage, 
according  to  the  fineness  of  the  screens.  It  is  pressed  and  burned  under 
a  boiler  or  buried  in  land.  Screening  has  attained  its  greatest  develop- 
ment in  Europe. 

Fine  screening  is  attracting  increasing  attention.  Screens  may  be 
called  fine  if  the  clear  opening  is  less  than  about  half  an  inch.  Often 
the  mesh  is  much  finer  than  this.  jSTaturally  they  clog  rapidly  and 
for  that  reason  they  are  movable  instead  of  stationary  and  special  ar- 
rangements are  made  for  cleaning.  The  collected  material  is  usually 
scraped  off  by  a  continuous  process  from  a  part  of  the  screen  as  it 
slowly  emerges  from  the  sewage.  There  are  at  least  six  types  of 
fine  screens :  (a)  The  Band  Screen,  an  endless  flexible  band  of  wire  or 
links  which  passes  over  upper  and  lower  rollers,  and  which  is  inclined 
in  the  sewage  channel;  (b)  The  Wing  Screen,  consisting  of  meshed 
vanes  or  paddles  on  a  horizontal  axis,  and  which  in  the  lower  positions, 
are  across  the  path  of  the  sewage;  (c)  The  Shovel-Vane  Screens  which 


STIMIAM    I'OM.I'I'IOX 


1201 


difTer  from  the  j)i-('i('(liiin-  in  liaviii';-  curved  vanes;  (d)  Tlie  Cylindrical 
Screen,  which  revolves  in  an  inclined  position  on  an  axis  nearly  parallel 
with  the  scwa<,'e  flow,  the  sewage  flnwin*:^  throiifih  the  cylinder,  and  the 
screen  bein<^  kept  elean  by  jets  of  water  playing'-  iijion  it  from  the 
outside,  the  screenings  passing  to  one  end  of  the  cylinder  ami  evacuated 
by  means  of  a  bucket  lift;  (e)  The  Drum  Screen,  a  truncated  cone  of 
wire  mesh  or  perforated  plate,  which  rotates  on  a  horizontal  axis;  (f) 
The  I nclinrd  Pise  Screen,  commonly  known  as  the  Reinsch-Wurl  Screen, 
which  consists  of  a  perforated   disc  surmounted   by  a   truncated   cone, 


Fig.  129. — Txclined  Screen  Operated  by  Water  Wheel,  Bir^eixgham, 

England. 


which  moves  on  an  inclined  axis.  Of  these  types  the  last  appears  to 
be  the  most  successful. 

The  openings  in  the  plate  are  slots  commonly  about  2  m.m.  wide  and 
30  m.m.  long,  staggered  in  rows,  6  m.m.  apart,  but  these  dimensions 
vary.  The  plate  is  swept  by  brushes  as  it  emerges  from  the  sewage. 
This  process  forces  some  of  the  friable  solid  matter  through  the  screen, 
but  leaves  it  in  a  finely  divided  state. 

Sedime?itatio?i. — Sedimentation  is  the  most  important  of  the  pre- 
paratory process.  By  allowing  the  sewage  to  flow  slowly  through 
basins  in  which  the  velocity  is  checked  some  of  the  suspended  matter  is 
deposited  and  the  sewage  clarified  accordingly.  There  are  five  types 
of  sedimentation  basins:  (i)  grit  chambers  or  detritus  tanks,  (2)  plain 
settling  tanks.  (3)  septic  tanks,  (4)  digestion  tanks,  and  (5)  chemical 
precipitation  tanks. 

(1)  Grit  Chambers. — Grit  chambers  are  small  settling  basins  in 
which  the  sewage  remains  for  a  brief  interval,  often  not  more  than  a 
few  minutes,  and  where  the  velocity  is  commonly  between  10  and  30 


1202 


SEWAGE  DISPOSAL 


inches  per  minute.  THey  require  frequent  cleaning.  The  material  col- 
lected consists  largely  of  sand  and  gravel,  but  usually  with  enough 
organic  matter  to  make  the  sludge  offensive. 

(2)      Plain  Settling  Tanks. — Plain  settling  basins  retain  the  sewage 
from  one  to  twelve  hours.     The  velocity  of  flow  is  commonly  from  0.1 


jA/lol/r^r/ye 


3rusfy 


Trouc/h 


Fig.  130. — Reinsch-Wxtkl  Screen. 

to  0.5   inch  per  minute.     Sludge  is  removed  at  frequent  intervals   in 
order  to  prevent  bacterial  decomposition. 

(3)  Septic  Tanks. — Septic  tanks  are  settling  tanks  large  enough  to 
retain  the  flow  of  sewage  from  eight  to  twenty-four  hours  or  longer,  the 
velocity  of  flow  varying  from  0.1  to  0,3  inch  or  more  per  minute.     The 


Fig.  131. — Cross  Section  of  Septic  Tank. 


sludge  is  allowed  to  remain  in  the  tanks  for  long  periods,  giving  oppor- 
tunity for  intensified  bacterial  action  to  take  place  in  the  absence 
of  oxygen;  that  is,  under  anaerobic  conditions.  As  a  result  some  of 
the  solid  organic  matter  is  liquefied  or  gasified  and  the  amount  of 
sludge  reduced.  This  process  is  spoken  of  as  digestion.  It  is  ac- 
companied by  the  presence  of  a  scum  on  the  surface  of  the  tank  and  a 


STHKAM    rOLI.r'PloN 


1203 


continual  risino^  and  lallin-,^  ui'  sludge  tbrougli  tlic  li(juid.  The  amount 
of  solid  organic  matter  thus  digested  varies  Ironi  Kt  per  cfiit.  to  10 
per  cent.,  being  greatest  in  strong  domestic  sewa.iic.  Sciilic  aelion  does 
not  materially  improve  the  qual- 
ity of  the  effluent.  It  may,  in 
fact,  make  it  more  objectionable. 
Septic  action  cannot  be  depended 
upon  to  render  sewage  safe  so  far 
as  infections  are  concerned. 

(4)  Digestion  Tanks.  —  The 
best  known  type  of  digestion  tank 
is  the  Imhoff,  or  Emscher,  tank. 
This  is  a  deep  septic  tank  divided 
by  sloping  partitions  into  an  up- 
per and  a  lower  compartment,  so 
arranged  that  the  sewage  flows 
through  the  upper  compartment, 
while  the  sludge  settles  through 
openings  in  the  partition  walls 
into  the  lower  compartment, 
where  digestion  takes  place.  The 
advantage  of  this  type  of  septic 
tank  is  that  the  sludge  alone  is 
submitted  to  septic  action  with- 
out allowing  the  products  of  decomposition  to  mix  with  the  flowing 
sewage  above,  while  more  complete  digestion  improves  the  character  of 
the  sludge  from  the  standpoint  of  subsequent  disposal. 

The  following  figures  show  the  approximate  percentage  of  suspended 
matter  removed  by  sedimentation : 

Percentage  removal  of  suspended  matter 


Fig.  132. — Typical  Section  of  an  Im- 
hoff Tank. 
a.  Compartment  for  flowing  sewage. 

f.  Sludge   digestion    compartment. 

g.  Baffle    to    prevent    gases    and    sludge 

from  rising  into  compartment  a.  but 
permitting  sediment  to  fall  into  the 
sludge  compartment. 
b-c.  Pipe   for   withdrawing   sludge. 


Kinds  of  Sedimentation 

Period. 
Hours 

Weak 
Sewage 

Medium 
Sewage 

Strong 
Sewage 

Grit,  or  detritus  tanks 

1 

6 

12 

24 

48 

10% 

2.5 

.30 

40 

.50 

15% 

40 

50 

65 

75 

25% 

Plain  sedimentation 

60 

Plain  or  septic  sedimentation 

Septic  sedimentation 

.     75 

80 

Septic  sedimentation 

85 

(5)  Chemical  Precipitation. — Sedimentation  may  be  hastened  and 
increased  by  the  use  of  chemicals.  Lime,  copperas  (ferrous  sulphate), 
and  alum  (aluminium  sulphate)  are  commonly  used.  The  active 
coagulants  are  the  hvdroxids  of  iron  aiul  aluminium.     When  the  sewage 


1204 


SEWAGE  DISPOSAL 


itself  contains  the  necessary  amount  of  iron,  lime  only  is  needed.  Wlien 
alum  is  used  500  to  1,500  pounds  are  required  per  million  gallons. 
At  London  the  sewage  is  treated  with  500  pounds  of  lime  and  120 
pounds  of  copperas  per  million  gallons ;  at  Worcester,  Mass.,  with  1,000 
pounds  of  lime  and  no  copperas;  at  Providence,  Pi.  I.,  with  600  pounds 
of  lime  and  no  copperas ;  at  Glasgow  with  600  pounds  of  lime  and  1,000 
pounds  of  copperas. 

(6)  Grease  in  Sewage. — The  recovery  of  grease  from  sewage  is 
attracting  attention  because  of  its  value  as  a  by-product  and  because  it 
interferes  somewhat  with  the  biological  processes  of  purification.     In 


Fig.  1.33. — ^Chemical  Precipitation  Plaxt  at  Woecestek,  Mass.,  Outlet. 


England;,  sulphuric  acid  is  used  to  some  extent,  and  applied  to  the 
sludge  or  to  the  raw  sewage.  By  this  means  the  grease  is  separated  and 
removed  by  skimming.  In  this  sulphurous  acid,  the  so-called  Miles 
Process,  has  been  used  experimentally.  In  the  army  cantonments  efforts 
were  made  to  eliminate  grease  by  the  use  of  traps  of  special  design 
located  on  the  drains  from  the  kitchens.     (Fig.  192.) 

Purification  Processes — Subsurface  Irrigation. — For  small  instal- 
lations a  satisfactory  method  of  disposing  of  sewage  after  sedimenta- 
tion is  to  discharge  it  through  3-inch  or  4-inch  tile  pipes  laid  in  the 
ground  10  to  18  inches  deep  in  rows  2%  to  3  feet  apart.  In  sandy  soils 
this  method  gives  satisfaction,  and  under  favorable  conditions  the  sew- 
age of  150  to  250  people  can  be  applied  to  an-  acre,  the  rate  of  applica- 
tion being  commonly  one  to  two  gallons  per  lineal  foot,  or  20.000  to 
30,000  gallons  per  acre  daily.  With  tight  soils  larger  areas  are  required. 
With  clay  soils  the  method  cannot  be  used. 

This  method  of  sewage  disposal  is  particularly  applicable  to  subur- 
ban and  rural  conditions. 


STI.'KA.M    I'OIJJ'I'ION 


120.! 


Broad  Irrigalioth — Brmul  irrigation  cojisists  in  the  application  of 
crude  sewage  to  land,  making  it  serve  as  food  for  crops,  the  principal 
value,  however,  being  in  the  water  itself.  It  is  distributed  by  means 
of  ditches  and  other  channels  as  in  ordinary  irrigation.  The  sewage 
farms  of  Berlin  and  Paris  are  very  extensive,  the  Berlin  farms  covering 
nearly  20,000  acres.  The  rate  of  application  varies  from  3,000  to  15,000 
gallons  per  acre  daily,  an  acre  serving  for  the  sewage  of  from  100  to 
300  persons.  The  crops  raised  on  sewage  farms  frequently  pay  the 
expenses  of  operation,  but  seldom  pay  the  interest  on  the  investment 
excejit  in  arid  regions,  where  irrigation  is  profitable.     Broad  irrigation 


Fig.  134. — Triple  Contact  Beds  at  Hamptox,  Englaxd. 


cannot  be  successfully  used  with  clayey  soils.     The  purification  obtained 
is  usually  very  satisfactory,  both  chemically  and  bacteriologically. 

Intermittent  Sand  Filtration. — With,  this  method  the  sewage  is 
applied  intermittently  to  beds  of  sand,  especially  prepared  for  the  pur- 
pose, in  such  quantities  that  it  quickly  soaks  away,  leaving  the  bed  ex- 
posed to  the  air  for  a  period  of  several  hours  or  several  days,  thus  giving 
opportunity  for  aeration  and  oxidation  of  the  organic  matter.  The 
results  obtained  are  usually  very  satisfactory,  provided  that  the  filters 
are  not  overloaded.  When  raw  sewage  is  applied  directly  to  the  beds 
the  rates  of  application  vary  from  50,000  to  150,000  gallons  per  acre 
daily,  the  population  served  per  acre  being  from  300  to  1,200.  With 
preliminary  treatment  higher  rates  may  be  used,  and  the  sewage  of 
1,500  to  2,000  people  applied  per  acre.  The  filters  are  usually  divided 
into  beds  by  means  of  earth  embankments  which  cover  the  distributing 
pipes.  Often  they  are  underdrained  with  tiles  laid  20  to  30  feet  apart 
in  fine  material,  or  100  feet  apart  in  coarse  material,  their  depth  below 
the  surface  varying  from  3  to  8  feet.     Crops  are  sometimes  growTi  on 


1206 


SEWAGE  DISPOSAL 


these  beds,  but  agricultural  operations  are  regarded  as  a  secondary  mat- 
ter. In  winter  the  beds  are  plowed  into  ridges  or  the  sludge  is  collected 
into  piles  so  that  ice  may  form  and  be  supported  upon  them,  leaving 
channels  beneath  the  ice  by  which  the  sewage  can  be  distributed.  After 
a  few  weeks  or  months  the  beds  become  clogged  and  it  is  necessary  to 
rake  the  surface.  At  intervals  the  accumulated  deposit  on  the  sand 
lias  to  be  scraped  off. 


^ 


D/STRiaUTOR  ■, 


~?i^ 


sp 


s; 


MA/N  J 
^Uf^DERDRA/N  DRAIN 

Fig.  l;ia. — Cross  Section  of  Intermittent  Sand  Filter. 


The  efficiency  of  intermittent  sand  filtration  is  higher  than  that  of 
any  other  process.  Well  operated  plants  are  capable  of  removing  from 
95  to  98  per  cent,  of  the  suspended  matter  and  bacteria,  while  the  effluent 
is  quite  clear  and  non-putrescible.  The  method  is  limited,  however,  to 
regions  where  suitable  and  convenient  areas  of  sandy  soil  exist. 

Contact  Beds. — Contact  beds  are  water-tight  compartments  filled 
with  porous  material,  such  as  broken  stone  or  coke,  and  operated  as 
follows:  The  bed  is  slowly  filled  with  sewage,  which  has  previously 
passed  through  a  septic  tank,  and  allowed  to  remain  full  for  a  brief 


PRiMARr  aro 


Fig.  136. — Cross  Section  of  Contact  Bed. 

period,  after  which  it  is  emptied  and  allowed  to  remain  empty  for  a 
longer  period.  A  cycle  commonly  employed  is  to  allow  one  hour  for 
filling,  two  hours  for  contact,  one  hour  for  emptying,  and  four  hours 
for  rest.  During  the  period  of  contact  the  suspended  matter  tends  to 
settle  upon  and  adhere  to  the  exposed  surfaces  of  the  broken  stone  or 
coke,  thus  forming  a  film.  While  standing  full  septic  action  occurs  and 
organic  matter  is  absorbed  by  the  film.  During  the  resting  period 
oxidation  of  this  organic  matter  takes  place.  The  purification  obtained 
in  this  way  is  partial.  Commonly,  two  or  three  contact  beds  are  used 
in  series,  the  effluent  from  the  first  passing  to  the  second,  and  that  of  the 


STKKAM    l'()l.Li:'ll()X 


1207 


second  to  tlie  third.  Tho  depth  of  contact  beds  varies  from  2  to  6  or 
8  feet,  the  broken  stone  or  eoke  being  from  i/^  incii  to  2  incites  in  size. 
The  rate  of  application  is  usually  between  300,000  and  800,000  gallons 
per  acre  daily,  one  acre  serving  a  population  of  about  .5,000.  When 
properly  operated  and  receiving  the  sewage  of  septic  tanks  contact  beds 
are  capable  of  removing  aliout  (55  to  70  per  cent,  of  the  organic  matter, 
80  to  85  per  cent,  of  bacteria,  and  85  to  90  per  cent,  of  suspended  mat- 
ter. Contact  beds  become  clogged  with  use,  and  after  periods  varying 
from  five  to  eight  years  it  is  necessary  to  remove  the  stone  or  coke  and 
clean  them. 

Tricl-Hng  Fllfcrs. — Trickling  filters,  otherwise  called  "sprinkling 
filters"  or  "percolating  filters/'  consist  of  beds  of  porous  material  such 
as  broken  stone,  coke,  or  clinkers  upon  which  the  sewage  is  sprinkled  aiid 


Vic.  1.37. — Typical  Section  of  a  Sprinkling  Filter. 


through  which  it  percolates  to  underdrains  laid  on  a  tight  floor  beneath. 
The  entire  bed  is  arranged  with  reference  to  complete  aeration  through- 
out, in  order  that  the  organic  matter  of  the  sewage  may  become  thor- 
oughly oxidized.  The  suspended  matter  of  the  sewage  is  not  perma- 
nently retained  in  the  beds,  but  is  carried  out  in  the  effluent,  which  is 
turbid  and  requires  subsequent  clarification.  The  object  of  the  trickling 
filter  is  to  change  the  character  of  the  organic  matter  so  as  to  render 
it  non-putrescible.  The  sewage  is  applied  to  the  beds  by  sprinkling 
through,  fixed  sprinklers  or  by  use  of  traveling  sprinklers,  rotary  or 
rectangular,  operated  by  the  discharging  sewage  or  by  power.  The  rate 
of  application  varies  from  0.5  to  2.0  million  gallons  per  acre  daily, 
one  acre  of  trickling  filter  serving  a  population  of  10,000  or  more. 
The  beds  vary  in  depth  from  5  to  10  feet,  coarser  material  being  used 
for  the  deeper  beds.  Well-operated  sprinkling  filters  receiving  the 
efiluent  from  plain  sedimentation  or  septic  tanks  are  capable  of  remov- 
ing from  85  to  90  per  cent,  of  the  suspended  matter  and  from  90  to  95 
per  cent,  of  bacteria,  yielding  an  effluent  that  is  non-putrescible.  The 
effluent  from  trickling  filters  is  not  always  clear,  and  should  be  passed 
through  settling  basins  before  discharge.  This  method  is  useful  when 
sandy  areas  of  sufficient  size  are  not  available  for  intermittent  filtration 
or  are  too  expensive. 


1208 


SEWAGE  DISPOSAL 


Activated  Sludge  Tanks. — A  recent  form  of  tank  treatment  is  one 
which  combines  forced  aeration  with  bacterial  action.  By  pumping 
compressed  air  into  a  tank  containing  sewage  so  that  the  bubbles  rise 
through  it,  causing  the  sediment  to  be  thoroughly  agitated,  the  particles 
of  suspended  matter  after  a  few  weeks  become  coated  with  a  bacterial 
slime  so  that  colloidal  particles  become  attached  to  them.  When  this 
condition  has  been  reached  sewage  is  allowed  to  pass  through  the  tank, 
aeration  being  maintained,  the  result  being  a  surprising  clarification  and 
reduction  in  bacterial  content.  A  certain  amount  of  nitrification  also 
takes  place.     The  operation  may  be  conducted  on  the  fill  and  draw 


Fig.  138. — Tricki.ixg  Filter  at  P.irmixgham,  England. 


principle  or  on  the  principle  of  continuous  flow.  This  process  is  being 
experimented  Avith  in  many  places  and  promising  results  are  being  ob- 
tained. In  principle  the  process  resembles  that  of  filtration  in  that  the 
colloidal  substances  are  brought  in  contact  with  particles  covered  with 
bacterial  slime,  in  one  case  the  grains  being  scattered  through  the  sew- 
age, in  the  other  the  sewage  being  allowed  to  filter  or  percolate  through 
the  grains. 

If  this  process  proves  successful  on  a  large  scale  it  is  destined  mate- 
rially to  alter  present  methods  of  sewage  treatment,  as  the  structures 
required  would  be  very  simple.  The  sludge  is  said  to  be  relatively  inof- 
fensive and  well  suited  to  agricultural  use,  but  it  contains  a  large  amount 
of  water.  The  economy  of  this  method  will  depend  upon  the  cost  of  sup- 
ply air  and  the  cost  of  sludge  disposal. 

Sludge  Disposal. — The  disposal  of  sludge  is  one  of  the  most  diffi- 
cult parts  of  sewage  purification.  Grit  chambers  collect  from  0.1  to  1 
cubic  yard  of  wet  sludge  per  million  gallons  of  sewage;  plain  settling 
tanks  from  1  to  4  cubic  yards;  septic  tanks  from  1  to  2  cubic  yards. 


.STKKAM    I'ol.l.l'lIoX 


1209 


Sludge  deposited  in  j)]aiii  sctUiii^^  tanks  coiilains  from  !H)  to  05  per 
cent,  of  water;  septic  tank  sludge,  after  storage,  contains  from  80  to  85 
per  cent. ;  chemical  precipitation  sludge  from  90  to  92  per  cent. ;  Imhoff 
lank  sludge  from  SO  to  90  per  cent.  Sludge  after  pressing  contains 
from  2o  to  50  per  cent,  of  water.  Jt  has  some  manurial  value,  and  is 
used,  to  some  extent,  on  land.  As  a  general  proposition,  liowcver,  the 
attempt  to  "'utilize"  the  sludge  has  not  met  with  financial  success. 

Finishing'  Processes — Disinfection  of  Sewage. — The  licst  disin- 
fectant for  sewage  or  sewage  effluent  is  "chlorid  of  lime,"  or  bleaching 
powder,  whicli  is  usually  applied  in  the  form  of  a  1  per  cent,  to  2  per 


Fig.    139. — Septic   Tank  and   Chemical   Precipitation   Tanks   at   Rochdale, 

England. 


cent,  solution.  The  quantities  required  are  25  to  75  pounds  per  million 
gallons  for  good  effluents  from  sprinkling  filters  or  contact  beds,  75  to 
125  pounds  for  poor  effluents,  125  to  250  pounds  for  crude  sewage,  and 
250  to  375  pounds  for  septic  sewage,  tlie  time  of  contact  required  vary- 
ing from  about  i/L'  hour  to  2  or  more  hours.  By  properly  applying  the 
chemicals  in  these  quantities  it  is  possible  to  destroy  from  95  to  99 
per  cent,  of  the  bacteria. 

Choice  of  Methods. — The  choice  of  methods  to  be  used  in  any  case 
depends  upon  various  considerations,  such  as  the  nature  of  the  sewage 
to  be  treated,  the  allowable  character  of  the  effluent  considered  with  ref- 
erence to  the  use  made  of  the  water  into  which  it  is  to  be  discharged, 
the  availability  of  suitable  areas  of  land  at  proper  elevation,  and  finally 
the  cost,  both  of  construction  and  operation. 

Where  suitable  areas  of  sandy  soil  are  available  the  method  of 
intermittent  filtration  is  ordinarily  the  most  satisfactory  one  that  can 


1210  SEWAGE  DISPOSAL 

be  adopted.  This  is  the  case  in  many  parts  of  New  England  and  in 
some  other  parts  of  our  country.  Over  much  of  the  United  States, 
however,  the  soil  is  far  too  heavy  to  allow  this  method  to  be  used  satis- 
factorily, and  when  this  is  the  case  some  of  the  newer  methods  must  be 
resorted  to,  such  as  sedimentation  followed  by  oxidation  in  trickling 
filters,  centact  beds,  etc.  Under  some  special  conditions  broad  irrigation 
may  be  desirable,  but,  generally  speaking,  this  method  is  falling  into 
disuse.  When  the  effluent  is  to  be  discharged  into  a  -stream  used  for  a 
nearby  supply  of  drinking  water,  or  into  the  ocean  or  a  harbor  in  the 
vicinity  of  oyster  beds,  disinfection  may  properly  form  a  part  of  the 
process.  Chemical  precipitation  is  seldom  used  where  the  sewage  is  of 
a  strictly  doiuestic  character,  but  it  may  be  used  to  advantage  when  the 
sewage  contains  large  amounts  of  trade  wastes. 

Methods  for  the  purification  of  sewage  are  quite  elastic  inasmuch  as 
the  difi^erent  processes  may  be  combined  in  different  ways.  A  study  of 
the  works  that  have  been  built  in  the-  United  States  during  the  last 
generation  shows  that  not  infrequently  they  have  been  made  more 
elaborate  than  was  necessary.  Often  a  simpler  design  with  a  large 
capacity  gives  better  results  than  an  elaborate  combination  of  processes 
of  limited  capacity.  Important  engineering  problems  are  almost  always 
involved  in  the  laying  out  of  sewage  treatment  works. 

Relative  Bacterial  Efficiency  of  Different  Processes. — By  way  of  re- 
capitulation the  following  figures  are  given  to  show  the  relative  sanitary 
efficiency  of  various  processes  employed  in  sewage  treatment: 

Percentage  • 
Removal  of  Bacteria 

Coarse  screens 0  to     5 

Fine  screens 10    "    20 

Grit  chambers '. 10    "    25 

Sedimentation    25    "    75 

Septic  sedimentation 25    "    75 

Chemical  precipitation 40    "    80 

Contact  beds 80    "    90    ■ 

Activated  sludge  process 85    "    95 

Trickling  filters 90    "    95 

Intermittent  sand  filters 95    "    98 

Broad  irrigation 97    "    99 

Disinfection  of  raw  or  settled  sewage 90    "    95 

Disinfection  of  filter  effluents 98    "    99 

These  figures  are  mere  approximations,  but  they  serve  to  show  how 
some  forms  of  treatment,  very  desirable  from  many  points  of  view, 
have  a  low  sanitary  efficiency.  The  septic  treatment,  for  example,  does 
not  greatly  reduce  the  number  of  bacteria  in  sewage;  in  fact,  if  the 
period  of  detention  of  the  sewage  in  the  tank  is  long  the  numbers  of 
bacteria  in  the  effluent  may  be  greater  than  those  in  the  raw  sewage. 


STREAM  POLLUTION  1211 

Management  of  Sewage  Treatment  Works. — Proper  management  of 
sewage  treatment  works  is  as  important  as  proper  design,  and  is  more 
diffieult  to  seeure.  It  is  a  most  regrettable  fact  tliat  many  treatment 
works  in  the  United  States  have  been  badly  neglected,  and,  in  conse- 
quence, have  given  inethcient  service.  Neglect  not  only  results  in  mak- 
ing the  etflnent  unsatisfactory,  but  leaves  the  works  themselves  in  an 
otl'ensive  condition.  Neglect  of  small  ])lants  is  more  common  than  of 
jtlants  large  enough  to  reiiuire  the  entire  lime  of  one  or  more  attendants. 

Another  frequent  cause  of  failure  is  that  treatment  works  are  allowed 
to  become  outgrown,  so  that  the  plant  becomes  overloaded  and  the 
process  becomes  inefficient.  The  sewers  of  a  city  are  usually  designed 
for  a  long  period  in  advance — forty  or  fifty  years — but  this  is  not  the 
case  with  treatment  works,  for  the  reason  that  such  works  can  ordi- 
narily be  enlarged  when  necessary.  This  is  sound  policy,  for  the  reason 
that  the  methods  of  purification  are  constantly  improving,  and  it  is  de- 
sirable to  take  advantage  of  these  improvements  as  far  as  possible 
whenever  enlargement  is  necessary.  But,  if  the  works  are  to  operate 
satisfactorily,  the  enlargement  must  be  made  as  the  tributary  population 
increases,  taking  advantage  of  the  methods  and  improvement  developed 
up  to  the  time. 

The  purification  of  sewage  is  so  largely  a  chemical  and  biological 
matter  that  it  is  desirable  to  have  the  works  in  charge  of  men  trained 
in  sanitary  engineering,  with  a  laboratory  equipment  at  their  disposal. 
Tests  of  the  sewage  before  and  after  treatment  should  be  made  regularly 
in  order  to  ascertain  the  efficiency  of  the  process.  Tests  should  also 
be  made  of  the  water  into  which  the  sewage  is  discharged.  In  the 
case  of  plants  of  large  size,  provided  with  laboratories,  such  tests  are 
made  daily,  but  in  the  case  of  plants  too  small  constantly  to  employ  a 
chemist  tests  should  be  made  regularly  by  some  controlling  authority. 
Herein  lies  one  of  the  functions  of  the  State  Board  of  Health. 

Treatment  Plants  as  Nuisances. — If  sewage  treatment  works  are  prop- 
erly designed  and  carefully  operated,  and  if  they  are  enlarged  from  time 
to  time  to  meet  the  needs  of  the  growing  community,  they  need  not 
be  the  cause  of  offensive  conditions,  but  often  they  are.  as  a  matter  of 
fact,  a  source  of  nuisance  in  themselves.  There  is  a  natural  opprobrium 
attached  to  a  region  where  such  works  exist  that  results  in  a  recognized 
deterioration  of  property  values.  The  processes  used  for  the  treatment 
of  sewage  not  infrequently  result  in  odors  that  may  be  objectionable  over 
considerable  areas.  Where  the  treatment  w^orks  are  entirely  covered,  as 
some  kinds  of  works  may  be,  little  or  no  nuisance  may  result,  but 
where,  for  example,  the  sewage  is  first  sui)mitted  to  putrefaction  in  a 
septic  tank  and  the  septic  effluent  then  sprayed  into  open  air  upon  the 
surface  of  sprinkling  filters,  this  exposure  of  the  atomized  liquid  results 
in  the  liberation  of  odors  that  may  reach  distances  up  to  perhaps  half  a 


1212  SEWAGE  DISPOSAL 

mile  from  the  plant,  depending  upon  the  amount  and  character  of 
scM^age  treatment,  the  local  topography,  prevailing  direction  of  the  wind, 
humidity  in  the  atmosphere,  and  other  conditions. 

Frequently  high  winds  will  carry  the  spray  itself  for  several  hundred 
feet  with  inevitable  bacterial  pollution  of  the  air.  In  the  operation  of 
sprinkling  filters  also  it  has  been  found  that  at  certain  seasons  of  the 
year  swarms  of  ilies  breed  in  the  porous  beds.  These  are  very  trouble- 
some, if  not  dangerous,  in  the  immediate  vicinity  of  such  works.  In 
considering  the  need  of  sewage  treatment  it  is  proper  to  balance  these 
possible  nuisances  against  those  resulting  from  the  discharge  of  un- 
purified  sewage  into  a  body  of  water.  It  not  infrequently  happens  that 
the  installation  of  sewage  treatment  works  merely  substitutes  one 
nuisance  for  another. 

Nuisances  Caused  by  Trade  Wastes. — It  not  infreqviently  happens 
that  the  greatest  nuisance  in  streams  is  due  not  so  much  to  domestic 
sewage  as  to  the  presence  of  trade  wastes  that  may  be  discharged  into 
the  stream  directly,  or  that  may  be  allowed  to  flow  into  the  stream 
through  the  sewers.  For  example,  the  discharge  of  spent  dye  liquors 
may  color  the  water  of  a  stream  for  many  miles;  petroleum  wastes 
from  gas  works  may  cause  iridescent  films  to  form  upon  the  surface 
of  the  water,  producing  an  unsightly  appearance  and  increasing  the 
odor  directly,  as  well  as  indirectly,  by  excluding  air  from  the  water; 
the  acid  iron  wastes  from  galvanizing  works  may  cause  a  rusty  discolora- 
tion that  not  only  imparts  a  brown  color  to  the  water,  but  paints  the 
rocks  and  submerged  stumps  along  the  shores  for  many  miles.  When 
nuisances  of  this  character  arise  it  is  wise  and  proper  to  install  sewage 
clarification  plants,  and  sometimes  more  elaborate  works,  for  such 
nuisances  cause  real  damage  to  property  and  to  personal  comfort.  Trade 
waste  pollution  may  interfere  with  the  filtration  of  water  even  more 
than  sewage  itself.  Illustrations  of  this  are  the  paper-mill  pollutions  in 
New  York  State  and  the  acid-iron  wastes  in  Pennsylvania. 

COOPERATIVE  SANITATION 

What  appears  to  be  needed  at  the  present  time  is  some  method  of 
cooperation  by  which  needed  sanitary  reforms  can  be  brought  about 
at  least  expense.  It  is  unbusinesslike  to  compel  the  purification  of  the 
sewage  of  a  large  upstream  city  in  order  to  protect  the  water  supply  of 
a  small  city  lower  down,  if  pure  water  can  be  furnished  the  latter  in 
some  better  and  cheaper  way.  Legislation  that  clothes  the  State  authori- 
ties with  power  to  prevent  the  pollution  of  streams  by  sewage,  but  does 
not  give  them  power  to  compel  the  purification  of  water  or  to  control 
pollution  by  trade  wastes,  is  unfortunate.  It  naturally  leads  to  litigation 
rather  than  cooperation,  and  may  retard  rather  than  hasten  necessary 


THE  RURAL  PKOTlLKAr  OF  SEWACE  DISPOSAL       1:313 

sanitary  rofonns.  11'  our  State  authorities  cannot  be  trusted  in  this 
matter  it  may  be  that  a  proper  solution  of  the  difficulty  will  be  found 
in  the  establishment  of  district  boards  similar  to  those  in  England  and 
Germany,  such  boards  having  jurisdiction  over  the  limits  of  particular 
catchment  areas.  In  some  respects  these  natural  hydrographic  boun- 
daries have  advantages  over  artificial  State  boundaries.  In  the  near 
future  also  our  national  government  will  doubtless  take  a  hand  in  the 
matter.  In  whatever  form  the  authority  may  be  constituted  the  idea  of 
cooperation  should  prevail,  and  ironclad  rules  against  stream  pollution 
should  give  way  to  a  rational  distribution  of  the  burden  of  water  puri- 
fication and  sewage  treatment,  and  an  equitable  adjustment  of  cost  made 
between  the  parties  interested,  thus  decreasing  the  total  expense  of  sani- 
tary measures  required  and  utilizing  natural  resources  for  the  purifica- 
tion of  sewage  in  water  as  far  as  this  is  safe. 

If  the  system  of  water  carriage  of  sewage  continues  in  use  the  time 
will  some  day  come  wlien  the  sewage  of  all  of  our  cities  will  be  purified,, 
partially  or  completely,  and  all  surface  water  supplies  filtered.  It  is 
proper  to  anticipate  this  consummation  as  far  as  our  means  permit, 
but  meantime  it  is  good  business  and  sound  common  sense  to  spend  our 
money  first  where  it  will  go  furthest  and  do  the  most  good,  building 
water  filters  and  sewage  treatment  works,  sometimes  one,  sometimes 
both,  as  they  may  be  needed. 

Adequate  remedies  against  stream  pollution  from  the  standpoint  of 
nuisance  have  been  usually  obtained  by  an  appeal  to  the  principles  of 
common  law.  Cases  involving  bacterial  pollution  by  sewage  have  been 
thus  far  too  few  to  establish  definite  precedents.  It  will  be  interesting  to 
see  whether,  in  view  of  our  increasing  population,  and  especially  the 
increasing  growth  of  our  cities,  the  courts  will  ultimately  decide  that 
the  use  of  unfiltered  river  water  as  a  source  of  water  supply  by  riparian 
owners  is  a  reasonable  use  of  the  water. 


THE  RURAL  PROBLEM  OF  SEWAGE  DISPOSAL 

One  of  the  most  difficult  problems  of  modern  sanitation  is  to  secure 
proper  disposal  of  fecal  matter  in  rural  communities,  at  summer  hotels, 
at  temporary  camps  of  laborers,  at  summer  colonies  at  beach  and  moun- 
tain, and  at  individual  houses  in  villages  and  on  the  farm.  It  is  difficult 
Ijecause  the  necessary  structures  are  so  small  and  simple  that  they  have 
been  thoughtlessly  constructed,  because  adequate  care  of  the  processes 
is  more  or  less  disagreeable  and  therefore  neglected,  but  chiefly  because 
the  inherent  dangers  have  not  been  understood  or  appreciated. 

One  of  the  most  needed  reforms,  and  one  that  is  happily  making 
progress,  is  that  of  the  protected  privy,  that  is,  one  where  the  fecal 


1214  SEWAGE  DISPOSAL 

matter  is  received  in  a  tight  vault  so  constructed  that  the  contents  can- 
not be  reached  by  flies,  insects,  rats,  hens,  or  pigs,  yet  so  ventilated  as 
to  prevent  disagreeable  odors  and  give  opportunity  for  evaporation  of 
liquids.  This  necessitates  the  liberal  use  of  screens  around  the  vault 
and  on  the  windows  and  doors,  and  the  use  of  a  self-closing  cover  for 
the  seat.  The  privy  vault  may  be  constructed  of  concrete,  with  bottom 
and  walls  3  inches  to  6  inches  in  thickness,  or  the  vault  may  be  re- 
placed with  a  tight,  removable  receptacle  of  metal  or  wood  placed  in 
a  screened  compartment.  Properly  constructed  privies  of  this  charac- 
ter may  be  located  near  dwellings,  the  only  conditions  being  those  con- 
trolling offensive  odors,  but  this  presupposes  greater  care  than  is  ordi- 


FiG.  140. — Intermittent  Sand  Filtkation  Bed  at  Brockton,  Mass. 

narily  given  to  such  matters.  Preferably,  therefore,  they  should  be  lo- 
cated at  some  reasonable  distance  from  dwellings. 

Privies  that  are  not  provided  with  water-tight  vaults,  but  are  so 
arranged  that  the  fecal  matter  falls  upon  the  soil,  may  be  safe,  so  far 
as  water  pollution  is  concerned,  if  the  soil  is  of  proper  character  and 
if  the  privy  is  sufficiently  removed  from  the  house  well;  but  are  unde- 
sirable for  other  reasons.  (No  arbitrary  rules  as  to  the  necessary  mini- 
mum distance  of  a  privy  from  a  well  can  be  laid  down,  as  everything 
depends  upon  the  character  of  the  soil,  the  slope  of  the  ground,  the 
elevation  of  the  natural  ground  water,  and  the  draught  of  water  from 
the  well,  A  distance  of  at  least  25  feet  should  be  secured  with  sandy 
soils,  whenever  possible,  and  preferably  50  feet  or  more.  With  clay  soils, 
liable  to  dry  and  crack,  and  in  limestone  regions,  liable  to  contain 
crevices  in  the  rock,  leaching  privies  should  not  be  used,  as  wells  may 
be  polluted  100  feet  or  even  a  mile  or  more  away. 

Cesspools  are  holes  dug  in  the  ground  to  receive  not  only  fecal 


THE  RURAL  PROBLEM  OF  SEWACE  DISPOSAL      1?15 

matter,  but  also,  perhaps,  sink  wastes  and  water-closet  discharges.  They 
are  often  lined  with  loose  stones  to  prevent  caving,  but  this  permits  the 
liquids  to  leach  into  the  soil.  When  the  soil  is  sandy  there  is  no  ol)jec- 
tiou  to  this  method  of  disposal;  in  fact,  it  is  like  the  method  of  sub- 
soil disposal  previously  described,  except  that  the  sewage  is  discharged 
into  the  soil  below  tiie  depth  where  the  soil  bacteria  are  at  work.  This 
may  be  an  important  difference,  however,  and  the  oxidation  of  the  dis- 
solved organic  matter  proceeds  by  a  slow  and  incomplete  process.  Leach- 
ing cesspools,  however,  should  not  be  located  near  wells  used  for  drink- 
ing water  supplies.  In  sandy  soils  the  danger  of  bacterial  contamination 
is  small  if  the  distance  is  more  than  25  feet,  but,  even  so,  the  idea  of 


Fig.  141.^Filtee  Bed  with  Saxd  Ridged  fob  Wixteb  Opeeatiox  at  Brock- 

Tox,  Mass. 
The  ice  sheet  rests  on  the  ridges.    The  photograph  shows  the  accumulation 
of  suspended  matter  during  the  winter. 

infiltration  of  sewage  into  a  well  is  repugnant,  and  often  the  water  may 
be  so  tainted  as  to  have  a  disagreeable  odor,  even  when  analysis  shows 
it  to  be  bacterially  safe. 

Ordinarily  leaching  cesspools  should  not  be  constructed  in  clay  soils 
or  in  limestone  regions,  for  they  are  liable  seriously  to  pollute  the 
ground  water  and  are  almost  sure  to  overflow.  If  cesspools  are  neces- 
sary under  such  conditions  they  should  be  made  water-tight  and  treated 
as  septic  tanks  and  the  effluent  taken  care  of  by  subsurface  irrigation  or 
some  form  of  land  treatment. 

In  cesspools  the  organic  matter  undergoes  septic  action  and  the 
amount  of  sludge  that  accumulates  is  often  small.  Xevertheless,  clean- 
ing is  necessary  at  intervals  in  the  case  of  all  cesspools.  The  disposal 
of  the  contents  is  one  of  the  most  troublesome  questions  connected  witli 
this  form  of  sewage  disposal.    The  common  method  is  to  spread  it  upon 


1216  SEWAGE  DISPOSAL 

the  land  as  a  topdressing.  The  Avork  is  apt  to  be  done  in  the  winter, 
when  other  farm  Avork  is  not  pressing,  and  not  infrequently  when  the 
ground  is  frozen.  Thus  opportunity  is  given  for  fecal  bacteria  of  human 
origin  to  be  washed  into  a  well  or  some  public  water  supply.  If  spread 
on  the  ground  during  the  summer  flies  have  access  to  it.  If  used  for 
fertilizer  for  crops  eaten  raw,  as  celery  or  lettuce,  opportunity  is  offered 
for  transmission  of  infection  by  such  foods.  The  only  proper  method  of 
disposal  for  cesspool  sludge  is  by  burial  or  disinfection.     In  laborers' 


■ 

1 

sfc^-a-Wwi-^     ^^^^^^^g^^^^^B^BHSBP^HM^B 

iBIi--:^"- 

^^^^^H 

^■^'- 

m 

iMflH 

^^1 

Fig.  142. — Discharge  of  Sewagk  upon  a  Filter  Bed  at  Brocktox,  Mass. 

camps,   and  in  army  camps,  disposal  of  fecal  matter  by  cremation  is 
practiced  with  advantage. 

In  the  South,  where  hookworm  disease  is  prevalent,  the  scattering 
of  human  fecal  matter  upon  the  surface  of  the  ground  is  one  of  the 
greatest  elements  of  danger.  The  danger  of  transmission  of  iiifection 
by  flies  from  fecal  matter  to  food  is  likewise  greater  in  tlie  South,  as 
the  warm  season  is  longer,  so  that  greater  care  needs  to  be  exercised  in 
the  construction  and  care  of  protected  privies  than  in  the  North. 

REFERENCES 

1890-1910. — Annual  Report  of  the  Massachusetts  State  Board  of  Health. 
(Summary  of  Results  Obtained  at  the  Lawrence  Experiment  Station 
During  Twenty-one  Years  Is  Given  in  the  Report  of  1908.) 

1905-1910. — Contributions  from  the  Sanitary  Research  Laboratory  of  the 
Massachusetts  Institute  of  Technology.  Eight  volumes,  containing 
papers  by  Professors  Sedgwick,  Winslow,  Phelps,  and  others. 

1908.— Duxbar  :  "Principles  of  Sewage  Treatment."  Translated  by  H.  T. 
Calvert.     Charles  Griffin  &  Co.,  Ltd.,  London. 


REFERENCES  1217 

1910. — ScHMEiTZNER,  RuDOLF :     "Clarification  of  Sewage,"  translated  by  A. 

E.  Kiniborly.     Engineering  News  Publishing  Coiniiany,  Now  York. 
1911. — Kershaw,  G.  Bertram:     "^loilorn  Motliods  of  Sewage  Puritication." 

Charles  Griffin  &  Co.,  Ltd.,  London. 
1912. — Elsner.  Alexander:     "Sewage  Sludge  Treatment."     Transhited  by 

Kenneth  Allen.     McGraw-Hill  Book  Co.,  New  York. 
1912.— Fuller,  G.  W.:     "Sewage  Disposal."    McGraw-Hill  Book  Co.,  New 

York. 
1912. — Ogden,  Henry  N.,  and  Cleveland,  H.  B.  :     "Practical  Methods  of 

Sewage  Disposal." 
1915. — Metcalf  and  Eddy:   "American  Sewerage  Practice,"  3  volumes.  The 

third  volume  treats  of  sewage  disposal. 
1918. — Follwell,     A.     Prescott:     "Sewerage."     Eighth      edition.     John 

Wiley  &  Sons,  New  York. 
1919. — KiNNicuTT,  Winslow,  arid  Pratt:    "Sewage  Disposal."    John  Wiley 

&  Sons,  New  York.     Second  edition. 
For  references  to  recent  works  for  the  treatment  of  sewage  see  files  of  Engi- 
neering News-Record. 


SECTION  X 

REFUSE  DISPOSAL 

By  George  C.  Whipple 
Professor  of  Sanifarij  Kiif/iiicrriiu/  in  tlie  Harvard  Engineering  School 

The  general  term  "refuse''  is  applied  to  all  of  the  solid  waste  ma- 
terial not  carried  by  the  sewers,  such  as  ashes,  rubbish,  garbage,  street 
sweepings,  manure,  and  dead  animals.  The  quantity  of  this  waste 
material  that  has  to  be  gotten  rid  of  in  a  city  is  very  large.  For  exam- 
ple, in  the  Borough  of  IManhattan,  New  York  City,  the  ashes  amount 
to  about  1,200  pounds  per  capita  per  year,  the  rubbish  100  pounds,  the 
street  sweepings  300  pounds,  and  the  garbage  200  pounds,  the  total 
amount  of  refuse  being,  in  round  numbers,  a  ton  per  capita  per  year. 
In  smaller  cities  the  per  capita  quantities  of  collected  refuse  are  less 
than  half  of  this,  sometimes  considerably  less.  The  amount  of  garbage 
alone  varies  from  less  than  100  to  upward  of  200  pounds  per  capita 
per  year.  Both  the  quantity  and  character  of  the  refuse  vary  with  the 
seasons,  the  maximum  amount  of  ashes  occurring  in  the  winter  and  the 
maximum  amount  of  garbage  in  the  summer.  This  fact  has  an  im- 
portant bearing  on  the  problem  of  ultimate  disposal. 

Ashes  weigh  from  900  to  1,200  pounds  per  cubic  yard,  garbage  from 
900  to  1,100  pounds,  street  sweepings  from  700  to  1,800  pounds,  and 
rubbish  from  150  to  250  pounds.  The  following  figures  serve  to  indi- 
cate approximately  the  constituents  of  the  principal  classes  of  refuse: 

COXSTITTJEXTS   OF    CITY   REFUSE 


Water 

Volatile 
Matter 

Ash 

Carbon 

Heat  Units 

per  Pound 

of  Refuse 

B.  T.  U. 

Ashes 

Garbage 

Rubbish 

Street  sweepings. 

7-25  % 
70-80  % 

5-15  % 
35-45  % 

8-10  % 
15-25  % 
40-65  % 
20-30  % 

50-60  % 
5-15  % 
5-15  % 

25-95  % 

18-25  % 

4-8    % 

15-40  % 

18-25  % 

.3.700 
2.000 
6,000 
4,000 

The  refuse  problem  is  to  a  slight  extent  a  hygienic  one,  but  it  is  more 
a  problem  of  economy,  convenience,  and  general  cleanliness.  Bad  smells 
from  fermenting  garbage  do  not  directly  injure  the  public  health,  yet 
they   are   an  offense,   and   their   elimination    is   an    important   matter. 

1219 


1220 


KEFUSE  DISPOSAL 


Ashes  and  street  dust  may  irritate  the  eyes,  nose,  and  throat  and 
predispose  to  bacterial  infection.  Accumulating  rubbish  is  not  only  un- 
sightly, but  may  provide  conditions  favorable  for  mosquito  breeding, 
while  accumulating  manure  may  breed  flies.  Garbage  attracts  flies  and 
may  breed  them  if  the  cans  are  left  uncleaned  from  week  to  week,  but 
ordinarily  garbage  does  not  stand  uncollected  long  enough  to  give  oppor- 
tunity for  the  larvae  to  hatch. 


7c  F/// 


Barre/s  pgf? 


^or  ferfi/izer 


Fig.  14.3. — Digestion  Process  of  Garbage  Reduction. 
(Boston  Development  and  Sanitary  Company) 


There  are  two  general  methods  of  collection  and  disposal  of  city 
refuse :  the  mixed  system  and  the  separate  system.  With  the  mixed 
system,  which  is  the  one  most  generally  used  in  Europe,  all  of  the 
refuse,  ashes,  garbage,  and  rubbish  is  put  together  by  the  householder  in 
a  single  can,  conveyed  by  wagon  to  the  disposal  plant,  where  it  is  all 
burned  together  and  the  organic  matter  thus  destroyed.  The  com- 
bustible matter  in  the  rubbish  and  the  unburned  coal  in  the  ashes  are 
usually  sufficient  to  evaporate  the  water  in  the  garbage,  so  that  the 
material  is  self-consuming.  This  method  is  known  as  incineration,  or 
cremation,  or  destruction.  With  the  separate  system  the  garbage,  rub- 
bish, and  ashes  are  kept  separate  by  the  householder  and  collected  in 


REFUSE  DISPOSAL  1221 

separate  wagons  and  dispust'd  of  in  dill't-ront  ways.  Tlio  ashes  are  used 
for  filling  low  land,  the  rubbish  carried  to  the  duni)»,  and  the  garbage 
taken  to  sea  and  dumped  or  buried,  or  fed  to  hogs,  or  taken  to  a  re- 
duction plant,  where  it  is  cooked  and  treated  for  the  recovery  of  fats 
and  other  products. 

The  separate  system  is  connnoiily  used  in  America,  but  with  numer- 
ous combinations  of  processes  of  collection  and  disposal.  Whichever 
method  of  disposal  is  adopted  determines  the  manner  of  collection  and 
the  treatment  of  the  refuse  by  the  householder.  The  choice  of  the 
system  to  be  used  is  one  to  be  determined  for  each  community,  largely 
on  the  basis  of  cost.  Generally  speaking,  an  incineration  plant  entails 
a  greater  initial  outlay  than  a  reduction  plant.  Its  products  are  ashes 
and  steam.  The  ashes  transported  are  commonly  used  for  filling  near 
the  plant;  the  steam  is  used  for  power  to  run  the  works,  and  the  excess 
steam  is  sold  or  converted  into  electricity  and  conveyed  to  places  where 
it  can  be  utilized  to  advantage.  In  cities  where  power  is  expensive 
the  receipts  for  the  sale  of  power  may  be  sufficient  to  throw  the  balance 
in  favor  of  this  method  of  disposal.  Where  power  is  cheap,  however, 
the  opposite  may  be  the  case  and  the  reduction  process  prove  the  cheaper. 
With  the  reduction  process  the  salable  products  are  grease  and  tankage. 
The  former  is  sold  for  soap  manufacture,  and  the  latter,  which  con- 
sists of  the  solid  particles  of  the  cooked  garbage,  is  pressed,  dried,  and 
ground,  and  used  as  a  filler  for  fertilizers.  As  time  goes  on  other  useful 
products  are  likely  to  result  from  this  process,  as  the  materials  wasted 
or  sold  contain  much  sugar  and  proteid  bodies. 

Incineration  Plants. — There  are  two  general  types  of  dest^ructors. 
The  mutual  assistance  type,  where  there  are  several  grates  and  divided 
ash  pits,  the  products  of  combustion  commingling  above,  thus  combining 
several  furnaces  into  one,  and  the  separate  unit  type. 

The  temperature  of  combustion  varies  from  about  1,200°  to  2,000°  F. 
and  the  capacity  is  from  1,200  to  1,500  pounds  of  mixed  refuse  per  day 
for  each  square  foot  of  grate  surface.  Each  pound  of  mixed  refuse  is  ca- 
pable of  evaporating  from  one  to  two  pounds  of  water.  So-called  crema- 
tion plants  are  operated  at  lower  temperatures  and  are  less  satisfactory. 

The  best  illustration  of  an  incinerator  in  this  country  is  the  one 
recently  constructed  at  Milwaukee.  This  was  designed  by  Dr.  Eudolph 
Hering,  and  a  description  of  it  may  be  found  in  the  Engineering  Xeir.<< 
for  July  10,  1910.  It  has  a  capacity  of  300  tons  of  mixed  refuse  per 
day.  The  Milwaukee  incinerator  receives  street  sweepings  and  manure 
as  well  as  ashes,  rubbish,  and  garbage.  The  manure  has  been  found 
fully  as  difficult  to  burn  as  the  garbage,  and  on  general  principles  it 
would  appear  to  be  wasteful  to  dispose  of  it  in  that  way.  With  a  well- 
arranged  incinerator  there  are  practically  no  objectiona])le  odors  and 
very  little  disagreeable  smoke. 


-      2 


1222 


REFUSK  DISPOSAL 


U-i.i 


Reduction  Plants. —  This  iiu'tluxl  of  ^Mrlia;i;e  disposal  is  used  in  many 
of  our  largest  Amcritau  cilit's,  incliuling  New  York,  Boston,  Biifralo,  tlio 
plants  as  a  rule  being  owned  and  operated  by  ])rivate  (-(jnipanies  under 
contract  M'ith  the  city.  Recently  an  excellent  plant  of  the  reduction  type 
has  been  constructed  by  the  city  of  Columbus  and  is  now  operated  ])y  the 
city.    A  description  of  this  ]ilant  may  ])c  found  in  the  Engineering  Ticc- 


Oarba^e  Bins 


Sor/er 


Co/Tdenser 


fieaf^er 


>  Separa/or 


Tank  - 


id 


—  yVasfea 


Conveyor 


Steam 


£xfracf/o/7 
7a/7A 


iVater  fram 

&ariJOffe  {t^o 

setverj 


Grease 
and 
So/^ent 


AfudDrum 


<5team 


Tankage 


Screen 


Sf/// 


P/'cker  \-^f^(^l>b/sh 


(?r/ficfer 


Storage         dagger 


Bones,  ef^c. 


Grease         Tankage 

>So/d  for  So/das 

tSoaps  ana  Co/yd/es   rerfi/Jzer 

Fig.  145. — CoBWELL  Process  of  Garbage  Reductiox,  New  Bedford,  Mass. 


ord  of  Xovember  19,  1910.  When  the  garbage  reaches  a  plant  of  this 
type  it  is  sorted  to  remove  foreign  substances,  such  as  tin  cans,  glass 
bottles,  etc.,  and  conveyed  to  a  series  of  digestors,  where  it  is  cooked  for 
from  six  to  ten  hours  under  pressure  of  about  60  pounds.  It  then 
passes  through  presses  which  separate  the  water  and  fats  from  the  solid 
part,  called  tankage.  The  water  and  grease  are  allowed  to  pass  through 
settling  tanks,  where  the  grease  is  skintmed  off  the  top.  The  water  flows 
away  to  the  sewer  or  is  evaporated,  and  the  solids  added  to  the  tankage. 
The  latter  is  sometimes  treated  for  fat  recovery  by  the  use  of  hot  naphtha. 


1224  REFUSE  DISPOSAL 

Ultimately  the  tankage  is  ground  and  dried  and  used  as  a  filler  for 
fertilizers.  The  per  cent,  of  grease  recovered  may  amount  to  from  1  to 
3  per  cent,  and  the  marketable  tankage  to  about  20  per  cent,  of  the 
garbage.  Unless  a  plant  of  this  type  is  well  designed  and  carefully  man- 
aged offensive  odors  will  result,  but  these  can  be  almost  completely  done 
away  with  if  proper  precautions  are  taken. 

Feeding  Garbage  to  Hogs. — In  many  small  cities,  especially  those  of 
New  England,  the  garbage  is  fed  to  hogs.  This  requires  frequent  col- 
lection and  careful  management  at  the  piggery.  There  seems  to  be  no 
sanitary  objection  to  this  method,  while  it  may  be  a  profitable  one  on 
account  of  the  large  food  value  of  the  garbage.  Since  the  World  War, 
this  method  of  disposal  has  found  favor. 

Collection  of  Grarbage. — From  a  sanitary  standpoint,  and  even  from 
the  standpoint  of  nuisance,  the  problem  of  garbage  collection  -is  even  a 
more  difficult  one  than  that  of  garbage  disposal.  A  strong  argument  in 
favor  of  the  incinerator  method  is  that  the  method  of  mixed  collection 
can  be  carried  on  with  less  nuisance  than  separate  collection.  When 
garbage  is  mixed  with  th^  ashes  in  a  single  can  the  water  of  the  garbage 
is  absorbed  by  the  ashes,  fewer  flies  are  attracted  to  it,  and  the  odor 
is  reduced.  The  absorption  of  water  by  the  ashes  also  tends  to  reduce 
the  dust  nuisance.  Mixed  collection  is  also  more  economical,  as  fewer 
carts  are  required  and  collections  need  not  be  as  frequently  made.  Much 
depends,  however,  upon  local  conditions. 

Garbage  disposal  plants  are  best  located  near  the  outskirts  of  the 
city,  where  no  nuisance  will  result.  This  ordinarily  involves  a  long 
haul.  If  favorable  opportunities  exist  for  dumping  ashes  within  the  . 
limits  of  a  short  haul  the  separate  collection  of  refuse  may  prove  the 
cheaper.  At  Minneapolis  the  householders  are  required  to  wrap  each 
day's  garbage  in  paper.    This  method  is  said  to  be  very  satisfactory. 

REFERENCES 

1905. — Hering,  Rudolph:  "Review  of  General  Practice  of  Disposal  of 
Municipal  Refuse."  Transactions  American  Society  of  Civil  Engi- 
neers, Vol.  LIY,  Part  E,  p., 263. 

1906. — Parsons,  H.  deB.  :  "Disposal  of  Municipal  Refuse."  John  Wiley 
&  Sons,  New  York. 

1906.— Vexable,  W.  M.:  "Garbage  Crematories  of  the  United  States." 
John  Wiley  &  Sons,  New  York. 

1910.— Morse,  W.  P.:  "Collection  and  Disposal  of  Wastes."  Published 
by  the  Municipal  Journal,  New  York. 

1911. — Greeley,  Samuel  A.:  "Investigations  for  Municipal  Refuse  Dis- 
posal." Proceedings  New  Jersey  Sanitary  Association,  November, 
1911. 


SECTION  XI 

VITAL  STATISTICS 

The  Begisiration  of  Births,  Deaths,  and  Marriages,  and  the  Beporting 
of  Koti/iahle  Diseases;  the  Resulting  Records  and  Derived  Statistics; 
and  Tlicir  Legal,  Social,  and  Public  Health  Uses. 

By   John    W.    Trask 
Surgeon,  United  States  Public  Health  Service 
Medical  Director,  U.  S.  Employees'  Compensation  Commission    , 

[Statistical  Methods,  see  pages  631-638] 

Statistics  have  suffered  in  reputation  because  of  the  seeming  truth 
of  the  trite  statement  that  one  can  prove  anything  by  figures.  In  reality 
figures  are  but  evidence  upon  which  conclusions  may  be  based.  If  the 
evidence  is  faulty  and  the  faults  are  not  perceived,  errors  in  judgment 
may  result.  But  this  is  true  of  all  evidence  upon  which  opinions  are 
based  and  is  no  more  true  of  figures  and  statistics  than  it  is  of  other 
kinds  of  evidence. 

Statistics  are  derived  from  the  collection  and  numerical  classifica- 
tion of  observations  relating  to  certain  facts  or  events.  They  are  usually 
limited  to  the  systematic  collection  and  classification  of  data  relating 
to  relatively  large  classes  of  events.  In  the  making  of  statistics  the 
first  and  essential  step  is  the  recording  of  observations.  After  the 
observations  have  been  noted  a  numerical  compilation  of  their  fre- 
quency or  of  the  frequency  of  certain  of  their  conditions  or  attributes 
is  possible.  The  derived  statistics,  being  but  a  numerical  classification 
or  analysis  of  the  recorded  events,  depend  primarily  for  their  usefulness 
upon  the  accuracy  of  the  original  records  of  facts.  They  depend  sec- 
ondarily upon  the  accuracy  of  the  statistical  classification  and  compila- 
tion. 

The  original  notation  of  facts  and  of  the  occurrence  of  events  is 
usually  secured  in  one  of  two  ways,  by  enumeration  or  by  registration. 
In  the  United  States,  for  example,  observations  relating  to  the  popu- 
lation are  made  by  enumeration  at  the  decennial  censuses.  The  census 
enumerators  go  from  house  to  house  and  secure  certain  information  re- 
garding each  individual.    The  enumerators  are  the  observers  who  secure 

1225 


1226  VITAL  STATISTICS 

the  original  data.  Statistics  of  the  population  are  made  hy  the  classi- 
fication of  the  information  thus  obtained  and  the  numerical  compilation 
of  the  frequency  of  certain  attributes. 

On  the  other  hand,  the  notation  of  facts  relating  to  deaths  is  secured 
by  registration.  For  each  individual  who  dies  there  is  registered  with 
an  official  known  as  a  registrar  of  deaths  certain  information  regarding 
the  deceased  and  the  cause  and  time  of  death.  Here  the  observers  who 
record  the  original  data  are  the  physicians,  members  of  families,  and 
undertakers.  From  the  classification  and  compilation  of  the  mformation 
thus  recorded  mortality  statistics  are  derived.  Statistics  of  population 
depend  for  their  accuracy  upon  the  correctness  of  the  records  made  by 
the  enumerators  and  mortality  statistics  upon  the  accuracy  of  the  infor- 
mation registered  in  death  certificates. 

The  statistical  method  is  in  itself  dependable,  although  it  is  true  that 
statistics  may  be  vitiated  by  the  use  of  inaccurate  or  incomplete  data 
as  a  basis  or  of  faulty  methods  in  classification  and  compilation.  Con- 
clusions drawn  from  statistics  by  those  who  attempt  to  use  them  may 
be  quite  erroneous,  but  this  is  more  often  due  to  the  limitations  of  the 
user  than  to  the  limitations  of  the  statistics.  The  most  common  error 
in  the  use  of  statistics  is  perhaps  the  comparing  of  numerical  statements 
or  ratios  which  are  too  dissimilar  to  allow  of  comparison. 

One  of  the  dangers  in  drawing  conclusions  from  statistics  is  that  the 
statistics  may  have  been  compiled  and  published  by  statisticians  who 
were  unfamiliar  with  the  accuracy  or  inaccuracy  of  the  data  which 
they  have  compiled.  The  data  collected  by  census  enumerators  may  be 
incomplete  or  fictitious  as  it  has  been  at  times  for  certain  communi- 
ties. The  derived  population  statistics  must  necessarily  be  undepend- 
able. 

Vital  statisticians  may  compile  the  data  of  deaths  as  recorded  in 
death  certificates  without  knowing  that  the  causes  of  death  given  may 
be  erroneous  in  a  large  proportion  of  the  cases.  In  such  instances  the 
statistics  of  causes  of  death  must  be  equally  erroneous. 

.Statistics  of  birth  may  be  compiled  and  published  and  accepted  by 
the  unknowing  as  representing  actual  conditions.  The  fact  may  be 
that  in  the  state  or  city  under  consideration  only  ^0  per  cent,  or  may 
be  only  60  per  cent,  or  50  per  cent,  of  all  births  were  registered.  The 
derived  statistics  may  therefore  be  worse  than  useless,  for,  while  they 
have  the  appearance  of  giving  information,  what  they  actually  give  is 
misinformation. 

Morbidity  statistics,  statistics  of  the  incidence  of  disease,  may  be 
compiled  and  published  without  a  clear  explanation  that  the  statistics 
are  of  the  reported  cases  but  that  there  were  many  cases  that  were  not 
reported,  the  proportion  of  unreported  cases  depending  upon  the  disease, 
the  community  and  the  time. 


VITAL  STATISTICS  1227 

There  is  a  tendency  for  the  statistician  to  accept  the  data  given  to 
him  as  being  accurate  and  to  compile,  tabulate  and  analyze  them  as 
though  they  in  all  instances  represented  facts  possible  of  such  handling. 
The  final  statistical  results  are  likely  to  be  accepted  by  the  student 
without  a  thought  of  the  nature  or  source  or  possible  inaccuracies  of 
the  basic  data. 

Often  the  statistician  understands  the  incompleteness  and  inaccu- 
racies full  well  and  in  footnotes  and  explanatory  text  explains  pre- 
cisely the  nature  and  extent  of  dependability  of  published  statistical 
tables.  The  reader,  however,  is  prone  to  pay  little  attention  to  ex- 
planatory text  and  to  ignore  frequently  footnotes.  A  statistical  table 
should  always  be  studied  with  care  and  caution  and  at  times  critically 
to  an  extent  bordering  on  suspicion. 

Persons  unacquainted  with  statistical  methods  are  likely  to  con- 
sider statistics  as  a  subject  beyond  their  comprehension.  This  is  a 
mistaken  idea.  Most  statistical  tables  are  the  result  of  but  the  simplest 
of  mathematical  computations,  and  are  derived  usually  by  nothing  more 
intricate  than  addition,  multiplication  and  division.  Anyone  who  can 
comprehend  that  350  births  during  a  year  in  a  population  of  35,000 
persons  would  be  at  the  rate  of  10  births  for  each  thousand  of  the 
population  can  understand  most  ordinar}'  statistical  statements.  Famil- 
iarity with  the  meaning  of  certain  of  the  terms  in  common  use  is,  how- 
ever, essential. 

To  make  dependable  statistics  the  original  observations  and  record; 
from  which  they  are  derived  must  be  true  and  accurate,  and  the  classifi- 
cation, compilation,  and  analysis  must  be  done  by  competent  individuals. 
The  value  of  statistics  when  thus  handled  is  daily  demonstrated  in  vari- 
ous social,  economic  and  commercial  activities. 


VITAL  STATISTICS 

Definition.^ — Altai  statistics  may  be  defined  as  statistics  relating  to 
the  life  histories  of  communities  or  nations.  They  pertain  to  those 
events  which  have  to  do  with  the  origin,  continuation,  and  terminatio'i 
of  the  lives  of  the  inhabitants.  They  commonly  include  statistics  of 
population,  births,  marriages,  deaths,  and  the  occurrence  of  disease, 
and  the  conditions  attending  these  events. 

Development. — Vital  statistics  are  not  a  thing  of  recent  origin.  Their 
development  to  their  present  form,  however,  is  comparatively  modern. 
The  Eg}'ptians,  Creeks,  and  Romans  made  census  enumerations.  Some 
of  the  ancients,  notably  the  Romans,  required  also  the  registration  of 
births  and  deaths.     The  statistical  treatment  of  the  records  was,  how- 

*  For  statistical  nietliods  and  di-finitions  of  terms,  see  page  G31. 


1228  VITAL  STATISTICS 

ever,  comparatively  limited.  During  the  last  century  and  a  half,  and 
more  particularly  the  last  50  years,  the  treatment  of  vital  statistics  has 
been  undergoing  a  rapid  evolution.  In  their  present  developed  form 
they  give  a  fund  of  useful  information  otherwise  unobtainable.  They 
have  become  an  essential  to  every  well-organized  community  and  nation. 
They  give  a  composite  picture  of  the  life  history  of  a  people  which  can 
be  secured  in  no  other  way.  They  furnish  a  means  of  comparing  the 
life  history  of  one  community  or  people  with  that  of  others  and  of  the 
present  with  the  past. 

Based  upon  Population. — All  vital  statistics  are  based  upon  the  pop- 
ulation. The  frequency  of  births,  marriages,  sickness,  and  deaths  is 
expressed  in  terms  of  the  population,  usually  as  rates  giving  the  number 
for  each  1,000  inhabitants  or  class  of  inhabitants.  In  comparing  dif- 
ferent communities  or  different  periods,  births,  marriages,  deaths,  and 
the  incidence  of  disease  must  be  based  upon  a  common  unit  of  population. 
The  first  requisite  to  useful  vital  statistics  is  statistics  of  population  show- 
ing the  number  of  inhabitants,  classified  according  to  age,  sex,  nativity, 
race,  and  occupation.  It  would  be  desirable,  if  possible,  to  have  also  a 
classification  according  to  economic  status,  as  birth,  sickness,  marriage, 
and  mortality  rates  frequently  vary  with  the  incomes  of  individuals  or 
households.  An  understanding  of  population  statistics  is  therefore  the 
primary  essential  to  the  comprehension  or  use  of  vital  statistics,  and  sta- 
tistics of  population  will  be  first  considered. 


POPULATION  STATISTICS 

Source  of  Data. — The  principal  source  of  information  regarding  pop- 
ulation under  existing  conditions  is  a  census  enumeration.  For  the 
United  States  these  enumerations  are  made  every  10  years.  The  last 
census  was  taken  as  of  January  1,  1920.  In  the  United  States  a  census 
has  been  taken  every  10  years  since  1790,  in  Great  Britain  every  10  years 
since  1801.  In  taking  a  census  it  is  desirable  so  far  as  possible  to 
take  it  at  a  time  when  the  greatest  number  of  people  will  be  at  their 
usual  homes.  A  midwinter  census  would  find  many  people  absent  from 
the  Northern  States  and  an  unusual  number  in  southern  winter  resorts. 
A  midsummer  census  would  find  an  unusual  number  at  the  seashore  and 
at  other  summer  resorts.  A  number  of  the  States  take  a  census  midway 
between  the  United  States  decennial  censuses,  so  that  they  have  an 
enumeration  of  the  population  every  five  years. 

As  the  only  source  of  definite  information  as  to  population  is  the 
census  enumeration,  and  as  the  population  is  continually  changing, 
in  most  cases  increasing,  it  is  necessary  to  make  estimates  of  the  popu- 
lation for  the  periods  between  the  census  enumerations  upon  which  to 


POPULATION  STATISTICS  1229 

base  raU's  for  the  various  vital  events  and  cspcciiilly  for  the  accurate 
computation  and  e\|)i-essioii  of  marriage,  hirtli.  dcnili.  and  sickness  rates. 

Nature  of  Census  Information. — 1'lie  taking  of  a  eonsus  consists 
usually  of  more  than  a  mere  enumeration  of  all  persons  living  at  the 
time  the  census  is  taken.  It  includes  the  recording  of  certain  informa- 
tion regarding  eac-h  individual.  In  taking  the  1920  United  States  census 
the  following  information  relating  to  each  individual  was  recorded  by 
States,  counties,  and  townships,  villages  or  cities:  Name;  address;  sex; 
color  or  race;  age  at  last  birthday;  whether  single,  married,  widowed, 
or  divorced;  birth  and  "mother  tongue"  of  the  indivifhial  and  place 
of  birtli  of  his  father  and  mother;  year  of  migration  to  the  United 
States;  whether  naturalized  or  alien;  whether  able  to  speak  English: 
the  individual's  occupation,  the  kind  of  work  done  and  the  indus- 
try^ or  business  in  which  employed ;  whether  an  employer,  employee, 
or  working  on  own  account;  whether  able  to  read  and  write; 
whether  attending  school:  whether  he  owns  the  home  in  A\hich  le^ 
lives. 

From  the  information  thus  obtained  the  statistics  of  population  are 
made.  By  the  classification  and  numerical  compilation  of  this  data  it  is 
possible  to  ascertain  the  composition  and  distribution  of  the  population 
as  to  sex^  color  or  race,  age,  marital  status,  nativity,  occupation  and 
literacy. 

Sources  of  Error  in  Census  Enumerations.! — A  certain  number  of  in- 
dividuals Avill  be  enumerated  both  at  the  place  where  they  happen  to  be 
and  at  their  proper  residences.  A  few^  wall  be  missed  entirely.  However, 
the  degree  of  error  thus  caused  will  not  be  great. 

The  margin  of  error  in  the  securing  of  ages  is  greater.  The  age 
record  is  customarily  intended  to  be  the  age  in  years  at  the  last  birth- 
day. The  ages  given  for  children  under  5  years  old  are  likely  not  to  be 
accurate  due  to  the  tendency  to  give  the  age  of  a  child  between  6  and  12 
months  of  age  as  1  year  old  and  that  of  a  child  between  1  and  2  years 
old  as  2  years  of  age.  This  tendency  to  give  the  age  at  the  next  birthday 
persists  up  to  about  the  fifth  year,  although  it  is  perhaps  greatest  during 
the  first  and  second  years.  To  avoid  the  error  thus  arising,  the  United 
States  census  records  the  ages  of  children  under  two  years  of  age  in  years 
and  months.  For  example,  a  child  6  months  of  age  is  recorded  as  six- 
twelfths  of  a  year  old  and  a  child  of  17  months  of  age  as  1  '5/12  years 
old. 

Women  15  to  20  years  of  age  are  prone  to  give  their  ages  as  between 
20  and  25  years.  Adults  over  25  years  of  age  frequently  do  not  know 
their  exact  ages  and  are  likely  to  approximate  their  ages  as  being  30 
or  40  or  50  years,  and  to  a  less  extent  as  35  or  15  or  55  years.  The  result 
is  that  there  is  at  each  census  an  exaggerated  number  of  ages  of  30,  40^ 
50  years,  and  also  a  lesser  exaggeration  of  ages  35,  45,  55,  and  65  years. 


1230 


VITAL  STATISTICS 


Individuals  over  80  years  of  age  have  a  tendency  to  give  their  ages  as 
greater  than  they  really  are. 

There  is  also  a  considerable  margin  of  error  in  the  recording  of  occu- 
pation. This  is  due  largely  to  an  imperfect  understanding  of  what  is 
wanted  and  to  the  multiplicity  of  occupations  and  a  lack  of  knowledge 
as  to  their  proper  designation. 

Fluctuation  in  Population. — Populations  are  constantly  changing. 
Individuals  are  continually  being  added  by  immigration.  In  the  United 
States,  and  more  particularly  in  some  sections  of  the  United  States,  con- 
siderable numbers  are  annually  being  added  in  this  way.  Immigration 
is  also  an  important  factor  in  the  growth  of  population  in  certain  South 
American  countries,  South  Africa,  New  Zealand,  Australia,  and  Canada. 

Populations  suffer  a  continuous  diminution  by  reason  of  emigra- 
tion.   This  is  especially  true  of  some  European  countries. 

Migrations  may  not  only  affect  the  population  of  a  country  as  a 
whole,  but  may  also  alter  the  distribution  of  people  within  a  country. 
There  is  in  many  countries  a  constant  movement  of  people  from  rural 
localities  to  the  cities  and  from  one  locality  to  another. 

All  populations  are  also  being  increased  by  births  and  suffering 
losses  by  deaths.  The  rate  of  change,  however,  resulting  from  births 
and  deaths  is  usually  comparatively  constant  or  alters  gradually,  while 
the  changes  due  to  migrations  may  be  exceedingly  irregular.  The  in- 
crease in  the  population  caused  by  the  excess  of  births  over  deaths  is 
known  as  the  natural  increase.  A  country  in  which  the  birth  and  death 
rates  are  equal  and  in  which  the  factor  of  migration  is  negligible  will 
have  a  lixed  population. 

The  increase  of  population  in  certain  countries  is  shown  by  the  fol- 
lowing table : 

Showing  growth  of  population  of  certain  cowntries  in  millions,  1800  to  1910 


France 

Great  Britain  and  Ireland 

Russia  in  Europe 

Austria , 

Italy 

Spain 

Belgium 

Sweden 

United  States 


1800 
27 

1830 

1860 

1890 

32 

36 

38 

16 

24 

29 

38 

.35 

45 

68 

92 

25 

29 

34 

40 

17 

21 

25 

30 

10 

11 

15 

17 

3 

4 

6 

2 

2 

3 

4 

5 

12 

31 

62 

1910 


39 
44 

49 
34 
19 
7 
5 
92 


Estimates  of  Population. — The  frequency  of  births,  marriages,  or 
deaths  is  usually  expressed  as  the  number  occurring  during  the  calendar 
year  per  1,000  population.  The  figures  thus  given  are  known  as  the 
birth,  marriage,  or  death  rates,  and  are  computed  upon  the  mean  popu- 
lation— that  is,  the  number  of  inhabitants  estimated  to  have  existed  at 


POPULATION  STATISTICS  1J331 

the  middle  of  the  year,  -luly  1.  These  estimates  are  necessary  for  all 
dates  except  those  on  wliich  census  enumerations  are  made.  For  the 
making  of  estimates  there  are  two  jirincipal  methods  commonly  used, 
known,  respectively,  as  the  arithmetical  and  the  geometrical  methods. 
In  each  method  the  populations  at  the  last  two  census  enumerations 
form  tlie  known  quantities  from  which  the  estimates  are  derived. 

Arithmciiail  Method. — In  the  arithmet'ical  method  it  is  assumed 
that  the  increase  or  decrease  in  population  which  occurred  hetween  the 
last  two  census  enumerations  took  place  in  equal  amounts  during  each 
intercensal  year  (the  years  between  two  census  enumerations)  and  will 
continue  to  take  place  annually  in  like  numbers  until  the  next  census 
shall  have  been  taken.  Thus,  given  a  city  which  had  a  population  of 
50,000  at  the  1900  census  (June  1,  1900)  and  one  of  61,850  at  the  1910 
census  (Apr.  15,  1910),  the  increase  during  the  intercensal  period  (9 
years  and  10^4  months)  would  be  11,850,  and  the  annual  increase  ac- 
cording to  the  arithmetical  method  would  be 

61.800-50,000    ^^ 

If  it  is  desired  to  estimate  the  population  as  of  July  1,  1906,  for  the 
purpose  of  calculating  annual  rates,  this  is  done  by  adding  to  the  popu- 
lation as  it  existed  June  1,  1900,  the  sum  of  1,200  for  each  year  inter- 
vening between  the  date  of  enumeration  (June  1,  1900)  and  the  date 
for  which  the  estimate  is  to  be  made  (July  1,  1906).  There  being  6 
years  and  1  month  between  these  dates,  the  calculation  would  be 

50,000+ (6  1/12  X  1,200)  =57,300. 

This  method  assumes  the  same  amount  of  increase  each  year  and 
is  analogous  to  the  calculation  of  simple  interest.  It  does  not  take 
into  account  the  fact  that  with  the  annual  increase  in  population  the 
number  of  persons  of  marriageable  age  and  therefore  the  number  of 
married  persons  will  be  greater  each  year  and  consequently  the  number 
of  births.  The  growth  due  to  natural  increases  (the  excess  of  births  over 
deaths)  is  analogous  to  the  increment  of  compound  interest,  and  where 
this  factor  (the  natural  increase)  is  the  principal  one  affecting  the  popu- 
lation growth  estimates  of  population  made  by  the  arithmetical  method 
are  unsatisfactory,  and  especially  so  where  the  estimate  is  made  for  a 
date  several  years  away  from  a  census  enumeration.  Where  the  excess 
of  births  over  deaths  is  the  controlling  factor  in  population  growth  the 
geometrical  method  of  making  estimates,  being  based  on  the  principle  of 
compound  interest,  is  more  accurate.  Where  migration  is  an  important 
factor  in  population  change,  the  arithmetical  method  may  be  the  more 
accurate.  The  arithmetical  method  has  been  the  one  found  most  reliable 
in  the  United  States  and  is  the  method  used  most  commonly  in  the 


1232  VITAL  STATISTICS 

past  by  the  Bureau  of  the  Census.  The  method  best  adapted  to  a  given 
population  can  be  ascertained  by  taking  the  last  two  intercensal  periods 
and  finding  whether  the  rate  of  increase  during  the  last  intercensal 
period  was,  when  based  upon  the  increase  during  the  preceding  inter- 
censal period,  at  the  rate  indicated  by  the  arithmetical  or  the  geometrical 
method; 

Geometiical  Method. — As  previously  stated,  the  geometrical  method 
is  based  upon  the  principle  of  compound  interest. 

Assuming  a  decennial  census,  let 

P  ^population  in  1900. 
P'^rpopulation  in  1910. 
r    r=the  annual  increase  per  unit  of  population. 

Then  the  population  would  be — 

Inl901=P  (1+r) 

Inl902=P  (l-fr)2" 

Inl903=P  (1+r)' 

In  1910  (P')=P  (l+r)i« 

P' 


-^=(1+^) 


^f=X+.and.=^T:_ 


In  practice  the  calculation  would  be  made  with  the  aid  of  a  table 
of  logarithms,  and  given  the  value  of  r  the  estimated  population  for 
any  intercensal  or  postcensal  date  is  readily  obtained.  For  postcensal 
dates  the  estimated  population  would  be — 

In  1911=:P'  (1+r) 
Inl912=:P'  (l+r)2 
Inl913=P'  (l+r)2 
n^^jesiT='P'  (l+r)° 

The  registrar  general  of  England  and  Wales  uses  the  geometrical 
method  for  England  and  Wales  as  a  whole  and  a  modified  method  for 
lesser  subdivisions. 

However,  estimates  are  after  all  but  estimates  and  nothing  more. 
For  large  populations  as  of  entire  countries,  and  for  smaller  popula- 
tions not  much  aft'ected  by  migration,  they  are  usually  sufficiently  de- 
pendable. In  the  United  States  they  have  been  satisfactory  for  most 
of  the  older  states  and  for  many  of  the  larger  cities.  Illustrations 
of  where  they  have  not  been  dependable  are  the  state  of  Washington 
and  the  city  of  Detroit.  The  facts  were  that  the  state  of  Washing- 
ton had  a  much  more  rapid  growth  in  population  between  the  census 
vears  1900  and  1910  than  it  had  between  1910  and  1920;  therefore 


MAKIUAOE  STATISTICS  1233 

ostiniatos  made  in  the  usual  way,  sul)se(|ueiit  to  the  census  of  1910 
and  previous  to  that  of  1920,  overstated  the  population.  The  per- 
centage of  error  would  he  greater  for  each  succeeding  year.  In  De- 
troit the  pojMilation  increase  was  at  a  much  greater  annual  rate  hetween 
J!>1()  and  l!»-i(t  than  it  was  hetween  VMH)  and  li)l(l.  Therefore,  esti- 
mates hased  on  either  the  arithmetical  or  the  geometrical  method  of 
calculation  would  have  indicated  a  lesser  population  than  was  actually 
present  in  the  city. 

There  are  other  states  than  Washington  where  the  rate  of  growth 
lias  changed,  although  prohably  none  w^here  the  change  has  been  so 
great.  'JMierc  are  many  cities  where  the  change  in  rate  of  growth  has 
been  as  great  as  in  Detroit  although  this  is  probably  not  true  of  any 
other  city  of  the  size  of  Detroit. 

The  estimates  of  the  population  for  the  United  States  made  by  the 
Bureau  of  the  Census  are  computed  by  the  Geographer  of  the  Bureau. 
His  task  is  a  trying  and  in  a  measure  an  unsatisfactory  one,  dealing  as 
he  does  with  populations  which  ebb  and  flow  in  unrestricted  movement 
throughout  extensive  areas.  It  is  only  by  keeping  in  touch  with  the  local 
factors  which  affect  population  that  the  work  is  possible.  For  cities,  in 
addition  to  the  actual  movements  of  population,  there  must  be  con- 
sidered the  frequent  changes  in  area  and  boundaries.  American  cities 
are  continually  changing  their  corporate  limits,  most  of  these  changes 
are  of  the  nature  of  extensions  in  area  and  annex  populations  which  had 
been  previously  outside  the  cities. 

Estimates  of  population  for  intercensal  and  postcensal  years  for 
states  and  cities  of  the  United  States  can  usually  be  obtained  from  the 
Director  of  Census.  If  they  cannot  be  thus  obtained  it  is  probably 
because  the  data  are  not  available  from  which  a  reliable  estimate  can 
be  computed. 

MARRIAGE  STATISTICS 

Marriage  statistics  are  of  interest  because  of  the  information  they 
give  regarding  the  social  life  of  the  people  and  the  establishment  of 
families  and  households,  and  because  of  the  relation  of  marriages  to 
population  growth  through  their  influence  on  the  birth  rate,.  Their 
consideration  naturally  precedes  that  of  birth  statistics. 

The  data  for  marriage  statistics  are  obtained  by  the  registration  of 
marriages.  The  common  custom  in  the  Ignited  States  is  to  require  per- 
sons desiring  to  marry  to  obtain  first  a  license  from  a  designated  oflficial. 
This  license  is  i)resented  to  whoever  performs  the  marriage  ceremony. 
The  person  officiating  is  required  to  register  the  marriage.  Those  re- 
sponsible for  the  completeness  of  marriage  records  are  therefore  in  this 
country  usually  the  clergy  and  justices  of  the  peace.     There  is  seldom 


1234  VITAL  STATISTICS 

much  difficulty  in  securing  complete  records  of  marriages,  and  the 
amount  and  value  of  the  information  given  by  marriage  statistics  depend 
upon  the  nature  and  extent  of  the  facts  recorded  relating  to  the  con- 
tracting parties. 

In  England  and  Wales  marriage  statistics  are  compiled  by  the  regis- 
trar general  of  marriages,  births,  and  deaths.  In  this  country  the  official 
responsible  for  the  compilation  of  marriage  records  varies  in  the  several 
States.  The  United  States  Bureau  of  the  Census  compiled  and  published 
in  1909  statistics  of  the  number  of  marriages  and  divorces,  in  the 
United  States  from  1S67  to  1906.  It  has  also  compiled  the  number  for 
the  year  1916. 

Marriage  Rates. — Marriage  rates  may  be  expressed  as  the  number  of 
marriages  for  each  1,000  population.  While  this  method  gives  certain 
information  of  a  definite  character  and  is  useful  for  comparing  different 
years  of  the  same  community  and  different  communities  of  similar 
population  composition,  it  is  not  useful  in  comparing  populations  in 
which  the  proportion  of  single  persons  of  marriageable  age  is  not  the 
same.  For  the  purpose  of  comparing  marriage  rates,  therefore,  the 
more  exact  method  is  to  express  the  rate  as  the  number  of  marriages  or 
persons  married  for  each  1,000  unmarried,  divorced,  and  widowed,  of 
marriageable  age,  usually  those  over  15  years  of  age. 

Factors  Influencing  Marriage  Rates. — Marriage  rates  are  usually  in- 
fluenced by  economic  conditions.  National  prosperity  increases  the 
rate,  economic  depression  reduces  it.  For  the  same  reasons  it  is  influ- 
enced by  the  demand  for  labor  and  the  rate  of  wages.  The  relation  of 
the  adopted  standard  of  living  to  the  average  wage  has  a  similar  effect. 
In  the  absence  of  other  factors,  the  marriage  rate  is  usually  a  fair  index 
of  the  relation  of  average  income  to  standard  of  living. 

The  marriage  rate  may  also  be  affected  by  the  frequency  of  divorce 
and  remarriage.  A  high  birth  rate  tends  to  increase  the  marriage  rate 
in  succeeding  years.  In  communities  such  as  mining  towns  and  new 
industrial  centers  the  marriage  rate  may  be  limited  by  the  presence  of  a 
relatively  small  number  of  marriageable  women. 

The  marriage  rate  in  a  city  may  be  fictitiously  high,  due  to  the  fact 
that  many  couples  from  the  surrounding  country  and  small  towns  may 
go  there  for  the  purpose  of  being  married,  returning  then  to  their 
homes.  In  a  country  affected  by  emigration  a  relatively  large  propor- 
tion of  the  emigrants  are  apt  to  be  yovmg  men  and  women,  the  women 
frequently  following  after  the  men  have  become  located.  This  naturally 
affects  the  marriage  rate  of  the  home  country. 

Uses  of  Marriage  Registration. — The  purpose  of  the  registration  of  a 
marriage  is  largely  to  protect  the  home  and  family.  It  furnishes  reliable 
evidence  upon  which  to  base  the  legitimacy  of  children  and  the  dower 
rights  of  women. 


BIKTH  STATISTICS  1235 


BIRTH  STATISTICS 

Statistics  of  births  are  of  interest  mainly  because  of  their  relation 
to  population  growth,  the  excess"  of  births  over  deaths  being  known  as 
the  "natural  increase."  Growth  of  population  has  been  the  object  of 
concern  to  nations  largely  because  of  its  effect  in  determining  the  future 
military  strength  and  the  number  of  men  available  for  purposes  of  of- 
fense and  defense.  The  practically  stationary  population  of  France  has 
for  some  time  been  the  subject  of  comment,  but  with  her  limited  terri- 
tory it  is  a  question  whether  the  people  as  a  whole  are  not  better  ofE  with 
the  present  population  than  they  would  be  with  a  larger  one.  More 
people  mean  greater  congestion  and  more  intense  competitioii.  During 
the  last  century  Great  Britain,  Germany,  Austria,  and  Eussia  have  trebled 
in  population.  Had  France  done  the  same,  she  would  now  have  nearly 
80  millions  of  people,  and  it  is  doubtful  whether  this  Avould  have  added 
to  the  happiness  and  welfare  of  the  race  except  that  it  would  probably 
have  been  of  advantage  to  her  in  the  late  AYorld  War  and  would  be  an 
added  factor  of  security  for  the  future. 

It  is  undoubtedly  better  to  have  a  people  proportionate  in  number 
to  land  area  and  natural  resources  than  to  have  a  teeming  population 
with  the  consequent  economic  problems.  It  would  seem  more  in  keeping 
with  modern  ethics  to  strive  for  a  people  composed  of  intelligent,  physi- 
cally sound  individuals  free  from  disease  and  properly  housed,  fed  and 
clothed,  whose  days  furnished  time  for  both  labor  and  recreation  under 
conditions  which  conduced  to  physical  and  mental  welfare  and  not  to 
deterioration,  rather  than  to  strive  for  mere  numbers. 

To  the  health  officer  and  sanitarian  birth  statistics  have  only  casual 
interest.  Birth  registration,  however,  which  furnishes  the  data  from 
which  the  statistics  are  made,  is  important  not  only  in  public  health 
work  but  in  other  ways  as  well. 

Registratioii  in  the  United  States. — In  legislation  the  registration  of 
births,  marriages,  and  deaths  was  formerly  usually  associated  and  pro- 
vided for  by  the  same  laws.  Since  1900,  however,  this  has  not  been 
generally  true  in  the  United  States,  where  the  practice  has  developed 
of  providing  separately  for  the  registration  of  births  and  deaths.    . 

A  model  bill  for  the  registration  of  births  and  deaths  recommended 
for  enactment  by  the  several  State  legislatures  has  been  drafted  and 
indorsed  by  the  American  Medical  Association  in  consultation  with  rep- 
resentatives of  the  Bureau  of  the  Census,  the  Children's  Bureau,  the 
American  Public  Health  Association,  the  American  Bar  Association, 
and  a  number  of  other  organizations  and  societies  national  in  scope.  The 
essential  features  of  this  law  have  been  adopted  by  a  number  of  States. 
It  is  important  that  other  States  should  also  enact  it,  for  it  is  without 


1236  VITAL  STATISTICS 

question  as  effective  a  law  as  any  that  has  been  proposed  for  adoption 
in  this  country.  It  is  also  highly  desirable  that  the  laws  of  the  several 
States  on  the  subject  be  uniform,  if  the  Bureau  of  the  Census  is  to 
compile  the  records  for  statistical  purposes.  The  power  to  legislate  on 
such  matters  resides  with  the  individual  States.  The  only  means  the 
Bureau  of  the  Census  has  of  preparing-  national  birth  and  death  statistics 
is  to  compile  the  records  registered  in  the  several  States  under  State  laws. 
This  is  done  by  making  copies  of  the  birth  and  death  certificates  regis- 
tered in  the  various  States  and  from  these  copies  taking  the  data  for  sta- 
tistical tabulations.  The  adoption  of  a  uniform  law  would  therefore  have 
distinct  advantages,  even  if  it  were  possible  for  State  legislatures  indi- 
vidually to  draft  better  ones. 

United  States  Begistration  Area  for  Births. — A  registration  area 
for  births  was  designated  by  the  Bureau  of  the  Census,  beginning  with 
the  year  1915.  The  area  for  1915  contained  the  States  of  Maine,  N"ew 
Hampshire,  Vermont,  Massachusetts,  Connecticut,  Ehode  Island,  New 
York,  Pennsylvania,  Michigan,  and  Minnesota,  and  the  District  of 
Columbia.  There  have  since  been  added  to  the  area  Indiana,  Kansas, 
Kentucky,  Maryland,  Xorth  Carolina,  Ohio,  Utah,  Virginia,  Washington, 
Wisconsin,  Oregon,  California,  JS"ebraska  and  South  Carolina,  making  in 
1921  a  total  of  twenty-three  states  and  the  District  of  Columbia  contain- 
ing approximately  60  per  cent  of  the  total  population  of  the  country.^ 
The  statistics  of  births  have  been  compiled  for  this  area  from  transcripts 
made  of  the  birth  certificates  filed  in  the  respective  States  in  the  same 
manner  that  mortality  statistics  are  compiled  from  State  records. 

Source  of  Data. — While  the  data  from  which  population  statistics 
are  derived  are  obtained  by  direct  enumeration,  the  data  from  which 
birth  statistics  are  compiled  are  gotten  by  registration.  The  usual  re- 
quirement is  that  Avhenever  a  child  is  born  either  the  attending  phy- 
sician or  midwife,  or,  in  their  absence,  the  parents  or  the  head  of  the 
household  in  which  the  birth  occurred,  shall  register  with  an  official 
designated  for  the  purpose  certain  information  regarding  the  child  and 
its  parents. 

Nature  of  Information  Secured  by  Begistration. — The  informa- 
tion required  to  be  registered  concerning  each  child  born  usually  in- 
cludes certain  facts  relating  to  the  child  and  the  circumstances  of  its 
birth,  together  with  certain  items  concerning  the  paTents.  The  essential 
facts  are  the  name  of  the  child,  its  sex,  date  and  place  of  birth,  and 
whether  born  alive  or  stillborn,  and  the  names  and  residence  of  the  pa- 
rents. There  are  many  other  items  of  information  concerning  births 
which  are  of  the  greatest  value  and  serve  various  purposes,  such  as  the 
age,  color,  nativity,  and  occupation  of  the  parents,  whether  the  child  is 
a  single  birth,  a  twin,  or  triplet,  and  whether  legitimate  or  illegitimate. 

^  Rhode  Island  was  dropped  from  the  area  in  1919. 


BIKTH  STATISTICS 


1237 


These  facts  are  usually  required  to  be  stated.     The  standard  certificate 
of  l)irth  for  the  Tnited  States  is  as  follows: 


United  States  Standard  Ckktikicate  of  IJirth 


i  0  5  i 

I  z  «  1 

J  5  »  ' 

» z  s  Si 

0  -    ■.  b  > 

s  ID  «  S 1 

■  ir  2  ^1 

■»     ll.    I  B   ° 

.   (D  5  => 

t  LI   ^  ?  t 

g  It:  9  si 

1  z  ■  ?  ' 

I  -  £  SI 


*  £, 


PLACE  OF  BIRTH 


County  of 

Townthlp  of 

Vlllic*  of 

CItjof  


STANDARD  CERTIFICATE  OF  BIRTH 


FULL  NAME  OF  CHILD  . 


Rofl***'*^  "o 

St-I  WwO) 

r  If  cAtu  ta  M4  r«(  BUMi  duk* 


T>h,  IHpH 
Hallwl 
(T0U4 


IN««bir  la  or4t 
•rbbtt 
wly  IB  <wt  ol  plui^l  blttbt) 


,1»,i 


AOC  AT  LAST 


BIRTHPLACe 


OCCUPATION 


•\w,y-^  "iv;:;; 


RE810ENCC 


BIRTHDAY 


BIRTHPLACE 


OCCUPATION 


CERTIFICATE  OF  ATTENDING  PHYSICIAN  OR  MIDWIFE* 

(Bora  iiiVV  i^'fiiiiibofo')* ' 


I  hereby  certify  that  I  attended  the  birth  of  this  child,  who  was 

on  the  date  above  stated. 


or  midiHre.  th^n  the  fa\ 
rtc.  ahoMld  tnake  tUit  r* 
child  t»  one  that  nHlh^^  t 
othrr  eHdence  of  tifc  aftr- 


inO  phvHc<an\ 


(FhjvlctaB  or  Hktvlh) 


I  name  added  from  a  supplemental       Addn 


The  items  registered  serve  two  principal  purposes.  They  serve,  first, 
to  identify  the  child  and  to  establish  its  age  and  parentage,  and,  second, 
to  furnish  statistical  data. 

While  in  the  enumeration  of  the  population  the  original  observer, 
upon  the  accuracy  of  whose  work  population  statistics  largely  depend, 
is  the  census  enumerator,  in  birth  registration  the  original  observer, 
upon  whom  dependence  must  be  placed,  is  usually  the  physician  attend- 
ing at  the  birth,  sometimes  the  midwife,  and  in  the  absence  of  these  the 
parents. 

Births  are  usually  required  to  be  registered  with  an  official  appointed 
for  the  purpose  and  known  as  a  registrar.  Customarily  it  is  the  same 
official  with  whom  deaths  are  registered.  At  times  a  small  fee  has  been 
paid  to  the  person  making  the  registration  or  tilling  out  the  certificate. 
This  custom,  however,  is  likely  to  create  in  the  minds  of  many  the  idea 
that  the  registration  is  a  matter  of  discretion — that  if  the  fee  is  not 
wanted  there  is  no  compulsion  to  file  the  certificate  and  that  the  forfeit- 
ing of  the  fee  annuls  the  obligation.  This  is  especially  true  in  the  United 
States,  where  physicians  and  midwives  have  in  many  instances  not  yet 
come  to  realize  that  the  importance  of  proper  registration  may  mean  so 


•1238 


VITAL  STATISTICS 


much  to  the  child  and  its  parents  that  no  accoucheur  has  completed  his 
task  nor  fulfilled  his  obligations  to  the  child  and  its  mother  until  an 
accurately  filled  out  certificate  has  been  filed  with  the  registrar.  The 
failure  to  file  such  a  certificate  is  such  a  neglect  of  the  interests  of  both 
patients^  the  child  and  the  mother,  that  it  would  seem  proper  to  class  it 
with  malpractice. 

Birth.  Rates. — There  are  several  ways  of  expressing  the  birth  rate. 
Each  method  of  statement  gives  information  not  given  by  the  others. 

Rgite  per  1,000  Population. — The  birth  rate  may  be  expressed  as 
the  number  of  births  occurring  during  a  year  for  each  1,000  of  the  popu- 


1S75 

1880 

1885 

l»0 

1895 

1900 

1905 

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2.       / 

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__ 

Fig.    146. — Births    (Including   Stillbirths),   Persons   Married,  and  Deaths 
(Exc!LUDiNG  Stillbirths) — Eegistered   Per   1.000  Population  Per 
Annum — Michigan,  1871  to  1915. 

lation.  This  is  known  as  the  crude  birth  rate,  and  is  based  upon  the  total 
estimated  mean  population  for  the  year — that  is,  for  the  calendar  year, 
the  population  estimated  as  of  July  1.  The  crude  birth  rate  shows  the 
net  result  to  the  community  of  the  several  factors  governing  reproduc- 
tion—the number  of  women  of  child-bearing  age,  the  number  of  those 
who  are  married,  the  frequency  of  illegitimacy,  etc.  In  conjunction  with 
the  crude  death  rate  it  shows  the  ratio  at  which  the  community  is  repro- 
ducing itself  by  natural  increase.  It  is  a  quite  satisfactory  basis  for 
comparing  the  birth  rate  of  different  years  for  the  same  community  or 
that  of  different  communities  having  populations  of  similar  composition. 
It  is  imsatisfactory  for  the  comparison  of  populations  having  different 
proportions  of  females  of  child-bearing  age  or  of  married  women — a 
mining   town   or   new   industrial   center   may   have    comparatively   few 


P.lirni    STATISTICS  123?) 

M'onicii  :  a  rasliionalilc  icsiilciil  iai  districi  may  liavu  a  relatively  lnv^o.  J'e- 
male  ixipiilal  imi,  iimsl   of  which  ((tiisisls  of  uiiinarried  servants. 

Bale  per  I /HH)  Wunirn  of  Clnld-hrdriiu/  Age. —  Birth  rates  may  be 
expressed  as  the  number  of  births  occurring  during  the  year  per  1,000 
women  of  ehild-bearing  age.  For  this  purpose  the  female  population 
between  the  ages  of  15  and  45  years  as  determined  by  census  enumera- 
tion, or  by  estimation  for  intercensal  and  postcensal  years,  is  taken. 
The  proportion  of  women  of  these  ages  in  the  population  having  been 
ascertained  by  a  census,  the  same  relative  proportion  is  assumed  to  be 
maintained  until  a  succeeding  census  shows  a  change. 

This  method  gives  rates  that  furnish  a  much  better  basis  for  the 
comparison  of  different  communities,  inasmuch  as  it  gives  the  births 
in  proportion  to  the  number  of  potential  mothers.  It  is  not,  however, 
satisfactory  under  all  conditions,  and  the  method  next  described  yields 
more  useful  information. 

Hate  of  Legitimate  Births  per  1,000  Married  Women  of  Child- 
hearing  Age  (15  to  4-^  or  15  to  Jf9  Years  of  Age)  and  of  Illegitimate 
Births  per  1,000  Unmarried  Women  of  Child-hearing  Age. — In  dif- 
ferent communities  the  proportion  of  married  and  single  women  may 
differ  considerably  and  consequently  comparison  of  their  crude  birth 
rates  or  of  rates  based  on  the  number  of  women  of  child-bearing  age 
would  yield  comparatively  little  useful  information.  The  proportion  of 
married  women  in  industrial  communities  is  usually  considerably  larger 
than  it  is  in  residential  suburbs,  where  there  are  greater  numbers  of  fe- 
male servants.  To  make  allowance  for  these  differences  in  population 
composition  the  most  useful  method  of  stating  the  birth  rate  is  in  terms 
of  the  number  of  legitimate  births  per  1,000  married  women  of  child- 
bearing  age  (15  to  44  years  or  15  to  49  years)  and  the  number  of  illegiti- 
mate births  per  1,000  unmarried  women  of  this  age. 

Sources  of  Error  in  Birth.  Statistics. — The  principal  sources  of  error 
in  birth  statistics  are  to  be  found  in  defective  registration.  There  is 
no  reliable  check  by  which  the  failure  to  register  births  can  in  all  cases 
be  detected.  In  many  foreign  countries  the  people  have  become  accus- 
tomed to  register  births  and  apparently  their  returns  are  quite  complete. 
The  registration  of  illegitimate  births,  however,  is  always  less  complete 
than  that  of  the  legitimate.  In  the  United  States  the  people,  as  a 
whole,  have  in  many  sections  not  become  accustomed  to  the  registra- 
tion of  births.  This  is  undoubtedly  due  in  part  to  a  rapidly  changing 
population  continually  receiving  large  numbers  of  immigrants  from 
various  foreign  countries — immigrants  who  are  ignorant  of  our  regis- 
tration laws  and  have  little  opportunity  of  learning  their  requirements — • 
and  in  part  to  the  absence  of  effort  by  the  authorities  to  enforce  the 
laws. 

As  checks  upon  the  completeness  of  birth  registration  registrars  fre- 


1240 


VITAL  STATISTICS 


Birth  rates    (exclusive  of  stillbirths)   per  1,000  population  in  certain  countries, 
■    1S86,  1913,  1914  and  1915  '"' 


Country  or  State 

1886 

1913 

1914 

1915 

Australian  Commonwealth 

Austria       ....'. 

35.4 
38.3 
32.4 
32.8 
35.3 
23.9 
37.0 
45.6 
23.2 
37.0 
34.6 
33.1 
31.2 
42.2 
32.9 
42.0 
36.7 
29.8 

t22.2 

121.3 

28.3 

$31.3 
25.6 
24.1 

$27.1 
19.0 
27.5 

$36.3 
22.8 
31.7 
28.1 
26.1 
25.3 
42.1 
25.5 

$38.0 
30.4 
23.2 

25.6 

24.8 

28.1 

25!6 
23.8 
26.9 

18.0 

22.6 
31.1 
28.2 
26.0 
25.2 
42.5 
26.1 

29!8 
22.9 

26.5 
25.6 

27.3 

24.2 

22.0 

Finland   

France                 

German  Empire 

TTimffarv 

Ireland       

22.0 

Italy    

The  Netherlands  

26  2 

New  Zealand 

25.3 

Norway  

Roumania  

Servia    

23.8 
23^9 

Sweden   

Connecticut   

21.8 

26.6 

*  Taken  from  the  Annual  Reports  of  the  Registrar  General  of  Births,  Deaths,  and  Marriages 
in  England  and  AVales,  1913,  1914  and  1915,  except  the  rates  for  Connecticut  and  Michigan, 
which  were  taken  from  the   State  reports. 

t  Includes  stillbirths. 

t  Year  1912. 

quently  use  the  death  returns  of  young  children  and  especially  of  in- 
fants, checking  up  each  recorded  death  with  the  birth  records  to  see 
whether  the  birth  of  the  child  had  been  registered.  The  notices  of  births 
appearing  in  newspapers  are  also  often  used  for  the  same  purpose.  If 
the  christenings  were  required  to  be  notified  by  those  officiating,  this 
too  would  be  of  assistance. 

Uses  of  Birth  Registration  and  Statistics. — Birth  statistics  are  of  use 
in  ascertaining  the  natural  increase  of  the  population  (excess  of  births 
over  deaths).  They  also  give  valuable  information  regarding  the  effec- 
tive fertility  or  fecundity  of  the  race  and  of  the  frequency  of  illegit- 
imacy. These  matters  are  of  interest  to  the  economist  and  the  states- 
man. The  possession  of  birth  statistics  also  furnishes  the  basis  for  the 
present  accepted  means  of  stating  the  infant  mortality  rate,  as  will  be 
explained  later.  The  data  from  which  the  statistics  are  made,  the  regis- 
tered births,  are  on  the  other  hand  of  value  to  the  community  in  many 
ways,  and  to  the  health  officer  among  others  may  be  especially  useful. 
Some  of  the  uses  will  be  enumerated. 

Legal  Records — The  registration  of  a  child's  birth  forms  a.  legal 
record  that  is  frequently  useful  and  may  be  of  the  greatest  importance. 
It  establishes  the  date  of  birth  and  the  child's  parentage  and  legitimacy. 
It  may  be  required  to  establish  the  child's  age  for  attendance  at  public 


Blirru   STATISTICS  1-^il 

scliools,  for  ))eniii8si(»ii  to  wcuk  in  States  ulicrc  cliildi'eii  bolow  a  ccrlaiu 
age  are  not  allowed  by  law  to  Ix-  ciiiploycd  ;  to  show  whether  a  girl  has 
reached  the  age  of  {■onscnf,  wlictlicr  imliv  iduals  have  attained  the  age 
when  they  may  many  witlioiit  llic  |iai('iit>'  iiciiiiissioii  ;  lo  (>stal)lish  age 
in  connoetion  with  the  i;i';iiitiiig  of  pciisioiis,  military  and  jury  duty,  and 
voting.  Jt  may  he  necessary  in  coimect ion  witii  the  Ix'cjueathing  and 
inhp-itance  of  property  or  to  furnish  aeeeptahle  evidence  of  genealogy, 
and  in  I'act  may  I)e  important  and  useful  in  possible  e\cnts  too  numerous 
to  mention.  During  the  period  of  mobilization  for  the  late  war,  there 
were  many  instances  where  the  interests  of  individuals  were  curiously 
affected  because  of  there  being  no  dependable  record  of  the  lime  and 
place  of  their  births. 

Uses  in-  Public  IleaJlh  Administration. — Eegistration  of  births 
shows  where  the  babies  are  and  makes  possible  such  observance  and  pro- 
tection as  the  health  department  desires  to  extend.  With  birth  regis- 
tration it  would  be  possible  for  the  health  authorities  to  see  that  the 
babies  are  vaccinated  against  smallpox.  This  is  one  of  the  uses  made 
of  registration  in  England.  It  would  also  be  possible  to  see  that  the 
babies  in  poor  families  have  proper  food  and  adequate  attention.  The 
observation  of  infants  under  two  weeks  of  age  would  bring  to  light  some 
cases  of  ophthalmia  which  otherwise  might  cause  serious  injury  to 
vision  and  at  times  total  blindness. 

Factors  Influencing  Birth  Rates, — Birth  rates  are  directly  influenced 
by  the  number  of  women,  and  particularly  of  married  women,  of  child- 
bearing  age  in  the  population.  The  child-bearing  period  of  life  for 
Avomen  may  be  considered  as  that  between  the  ages  of  15  and  49 
years;  the  ages  between  25  and  44  years  are  for  most  races  of  the  north 
temperate  zones,  however,  those  mainly  productive. 

The  economic  and  social  status  of  the  population  may  also  affect 
the  birth  rate.  In  many  countries  at  present  the  poor  families  have 
considerably  more  children  per  family  than  have  the  well-to-do;  in  fact 
to  some  extent  the  number  of  children  per  marriage  seems  to  be  in  in- 
verse ratio  to  the  family  income.  On  the  other  hand,  to  a  degree  poor 
economic  conditions  are  liable  to  discourage  or  delay  marriage,  so  that 
married  couples  are  relatively  fewer  and  older  when  married,  with  fewer 
resulting  offspring.  The  adoption  of  a  more  expensive  standard  of  liv- 
ing may  produce  the  same  results  as  depressed  economic  conditions,  fewer 
and  delayed  marriages. 

The  birth  rate  is  also  affected  by  the  habits  and  customs  of  the  peo- 
ple, by  their  desire  to  have  children  or  their  desire  not  to  have  them. 
Also  a  high  infant  death  rate  is  usually  accompanied  by  a  high  birth  rate 
and,  conversely,  a  low  infant  death  rate  bv  a  low  birth  rate. 


1242  VITAL  STATISTICS 

MORBIDITY  STATISTICS 

Morbidity  statistics  are  the  statistics  of  sickness  and  disease.  They 
show  the  occurrence  of  diseases  and  their  relative  prevalence  in  different 
localities  and  at  different  times.  They  differ  from  mortality  statistics 
in  that  as  relates  to  disease,  mortality  statistics  are  the  statistics .  of 
fatal  cases  only,  while  morbidity  statistics  include  all  cases.  For  ex- 
ample, if  in  a  city  there  were  500  cases  of  typhoid  fever  of  which  50  ter- 
minated fatally,  mortality  statistics  would  deal  with  the  facts  relating 
to  the  50  fatal  cases,  while  morbidity  statistics  would  deal  with  the  entire 
500. 

In  the  life  of  the  individual,  after  birth,  the  next  event'  included  in 
vital  statistics  which  usually  occurs  is  sickness.  Disease  has  perhaps 
a  greater  influence  in  determining  the  happiness  and  efficiency  of  the 
individual  and  of  the  community  than  any  other  factor.  It  also  has 
a  direct  bearing  on  the  individual's  longevity  even  when  in  itself  not 
fatal,  for  every  attack  of  sickness  probably  does  some  injury  and  leaves 
the  human  machine  impaired  to  a  degree,  and  an  illness  occurring  a  num- 
ber of  years  before  death  may  have  a  far  greater  influence  in  determining 
the  duration  of  life  than  the  terminal  illness. 

Morbidity  statistics  have  not  evolved  apace  with  those  of  births, 
marriages  and  deaths.  This  is  due  to  the  different  purposes  they  serve. 
The  branches  which  have  to  do  directly  with  the  growth  of  population 
were  first  developed,  probably  because  of  the  need  of  the  information 
which  they  gave  in  connection  with  taxation  and  military  enlistment. 
Morbidity  statistics,  on  the  other  hand,  are  contemporary  with  our  com- 
paratively recently  acquired  knowledge  of  the  causes  of  diseases  and  their 
manner  of  spread.  Their  need  has  been  felt  only  with  the  advent  of 
present  day  public  health  administration,  which  in  turn  has  been  acti- 
vated in  large  measure  by  the  story  of  the  causes  of  death  told  by  mor- 
tality statistics. 

Morbidity  statistics  had  their  origin  in  the  requirement  of  the  notifi- 
cation of  cases  of  certain  dreaded  diseases,  notably  smallpox.  With  the 
appointment  of  health  officers  and  the  establishment  of  health  depan- 
ments  the  notification  of  other  diseases  has  been  required.  As  knowledge 
of  the  causes  of  diseases  and  their  manner  of  spread  has  been  obtained 
and  health  departments  have  been  faced  with  the  responsibility  of  con- 
trolling maladies  found  to  be  preventable,  the  list  of  notifiable  diseases 
has  grown,  for  those  responsible  for  public  health  administration  have 
found  that  it  is  impossible  effectively  to  control  a  disease  without  prompt 
information  of  when,  where,  and  under  what  conditions  cases  of  the  dis- 
ease are  occurring.  Xo  epidemiologist  would  think  of  attempting  to  con- 
trol an  outbreak  of  yellow  fever  or  cholera  without  inaugurating  a  dc- 


MOKBTDTTY  STATISTICS  1243 

pendable  system  whereby  he  would  receive  prompt  and  accurate  infor- 
mation ol'  the  occurrence  of  cases.  It  is  just  as  imixtssihle  effectively  to 
control  tuberculosis,  typhoid  fever,  scarlet  fever,  industrial  lead  poison- 
ing, or  any  other  preventable  disease  without  a  knowledge  of  the  occur- 
rence of  cases. 

The  requirements  for  notification  of  the  preventable  diseases  and 
the  extent  of  their  enforcement  may  be  taicen  as  one  index  of  the  intelli- 
gence and  efficiency  of  health  administration  in  a  community. 

Morbidity  Statistics  in  the  United  States — Prespul  S id  I  us. — In 
the  United  States  the  authority  to  require  the  notification  of  cases  of  sick- 
ness resides  in  the  respective  State  legislatures.  In  some  of  the  States 
authority  has  been  given  to  the  State  boards  of  health  to  cover  the  sub- 
ject by  regulations.  In  most  instances  local  authorities  have  the  right 
to  supplement  the  State  requirements  by  such  additional  ones  as  may  be 
needed.  The  laws  and  regulations  of  the  several  States  differ  widely, 
as  do  also  the  efforts  made  to  enforce  them. 

The  common  and  most  general  plan  is  to  require  that  the  original 
report  be  made  by  the  physician  to  the  local  health  officer  immediately 
on  diagnosis  of  the  case.  The  local  health  officer  forwards  to  the  State 
health  department,  either  immediately  or  at  intervals,  a  transcript  or  a 
summary  of  the  notifications  received  by  him.  In  a  number  of  States 
these  reports  by  the  local  health  departments-  are  made  to  the  State 
authorities  daily,  in  some  weekly,  in  several  States  monthly,  and  in  a 
few  States  at  longer  intervals.  In  the  States  in  which  the  reports  are 
made  daily  the  State  health  department  is  in  a  position  to  keep  con- 
stantly informed  regarding  the  prevalence  of  the  notifiable  diseases.  The 
same  is  in  less  measure  true  when  the  reports  are  made  weekly.  When 
the  reports  are  made  at  longer  intervals  the  current  value  of  the  infor- 
mation to  the  State  department  is  largely  lost. 

In  certain  States  physicians  have  been  required  to  report  the  notifi- 
able diseases  directly  to  the  State  health  department.  This,  in  effect, 
makes  the  State  health  officer  also  the  local  health  officer  and  responsible 
for  the  control  of  the  notifiable  diseases,  the  control  of  disease  and  the 
notification  of  cases  being  inseparable,  the  latter  giving  the  necessary 
information  by  which  to  direct  action  in  the  former. 

In  some  States  the  laws  relating  to  morbidity  reports  specify  that 
cases  of  certain  classes  of  disease  shall  be  notifiable.  These  classes  have 
been  variously  stated,  the  wording  being  in  some  instances  that  "^all  cases 
of  contagious' or  infectious  diseases  dangerous  to  the  public  health  shall 
be  reported,"  in  others  "all  communicable  diseases,"  or  "all  contagious 
diseases,"  or  "all  diseases  dangerous  to  the  public  health."  When  the 
requirements  have  been  stated  in  general  terms  in  this  way  their  en- 
forcement has  been  especially  difficult  unless  the  diseases  included  have 
been  specifically  enumerated. 


1244  VITAL  STATISTICS 

The   follow] iijo:   named   diseases   are  those   specified   by   the   various 

State   requirements,   with   the   number   of    States    in    which    each  is 
notifiable:  ^' 

The  Notifiable  Diseases 
Communicable  Diseases:  States 

Actinomycosis  14 

Anthrax    28 

.Chickenpox 34 

Cholera  (Asiatic) 46 

Dengue   12 

Diphtheria   48 

Dysentery    3 

Dysentery  (amebic) 15 

Dysentery  (bacillary)    11 

Dysentery  (epidemic)   7 

Erysipelas   10 

Favus    ^ . . . .  7 

German  measles 20 

Glanders    24 

Gonococcus  infection  ~. 44 

Hookworm    disease    17 

Leprosy    38 

Malaria    21 

Measles  41 

Meningitis  (epidemic  cerebrospinal)   40 

Mumps 20 

Ophthalmia  neonatorum  (conjunctivitis  of  newborn  infants) 38 

Paragonimiasis  (endemic  hemoptysis)   5 

Paratyphoid  fever 13 

Plague  40 

Pneumonia  (acute)   15 

Poliomyelitis   (acute  infectious)    38 

Puerperal  fever 9  ■ 

Rabies 25  - 

Relapsing  fever 7 

Rocky  Mountain  spotted  or  tick  fever 11 

Scarlet  fever 47 

Septic  sore  throat 12 

Smallpox  49 

Syphilis   , 14 

Tetanus    12 

Trachoma    32 

Trichinosis    13 

Tuberculosis  (all  forms) 38 

Tuberculosis  (laryngeal)   4 

Tuberculosis  (pulmonary)   8 

Typhoid  fever 44 

Typhus  fever 42 

Whooping-cough    39 

Yellow  fever 40 

Occupational  Diseases: 

Arsenic  poisoning 15 

Brass  poisoning 8 

Lead  poisoning 15 

Mercury  poisoning 15 

*  This  list  is  added  to  from  year  to  year. 


MORRinrrv  statistics 


i>i5 


The  Xotifiahle  Diseases — Cunliiuini 
Occui'ATioNAi.  DisKASKs — C oiif in iirtl :  States 

Pliosphorus  pois()iiiii<r 14 

Wood  alcohol  iioisoiiiii<; 8 

Caisson  disoaso  (coiniiivsscd-air  illness)   14 

All  occupational  diseases 9 

MlgCELLANKOUS    DiSKASKS  : 


Beriberi     

Cancer    

Continued  t'ever  lasting 
Pellaiira    


3 

6 

ivs 3 

23 

The  Model  State  Law  for  Morbidity  Reports. — Since  eacli  State  has 
exclusive  authority  within  its  jurisdiction  over  the  requirements  for 
the  notification  of  disease,  any  con;prehensive  plan  that  may  be  devel- 
oped for  morbidity  reports  and  morbidity  statistics  must  be  the  result  of 
combined  effort  and  cooperation  and  the  enactment  by  the  several  States 
of  similar  requirements.  It  implies  also  an  adequate  enforcement  of 
these  requirements.  The  question  of  State  morbidity  reports  is  one  of 
the  most  difficult  problems  to  be  solved  by  the  State  authorities.  A 
number  of  States  have  been  endeavoring  earnestly  to  solve  the  problem 
within  their  respective  jurisdictions.  Considerable  progress  has  been 
made  in  several  instances.  The  question  is  an  important  one,  and  is 
bound  to  receive  much  consideration  in  the  future.  The  State  health 
authorities  in  conference  with  the  Public  Health  Service  had  the  mat- 
ter under  consideration  for  some  time  and  in  June.  1913,  approved  a 
model  State  law  for  morbidity  reports.  The  model  law  makes  the  occur- 
rence of  cases  of  the  following-named  diseases  and  disabilities  notifiable : 

GROUP    1. — COMMUNICABLE    DISEASES 


Actinomycosis. 

Anthrax. 

Chickenpox. 

Cholera,  Asiatic  (also  cholera  nos- 
tras when  Asiatic  cholera  is  pres- 
ent or  its  importation  threatened). 

Deng^ue. 

Diphtheria. 

Dysentery : 

(a)  Amebic.  (h)  Bacillary. 

Favus. 

German  measles. 

Glanders. 

Gonococcus  infection. 

Hookworm  disease. 

Leprosy. 

Malaria. 

IVfeasles. 

Meningitis : 

(a)  Epidemic  cerebrospinal. 
(h)  Tuberculous. 

iMumps. 

Ophthalmia  neonatorum  (conjuncti- 
vitis of  newborn  infants). 


Paragonimiasis  (endemic  hemopty- 
sis). 

Paratyphoid  fever. 

Plague. 

Pneumonia   (acute). 

Poliomyelitis  (acute  infectious). 

Rabies. 

Rocky  Mountain  spotted  or  tick 
fever. 

Scarlet  fever. 

Septic  sore  throat. 

Smallpox. 

Syphilis. 

Tetanus. 

Trachoma. 

Trichinosis. 

Tuberculosis  (all  forms,  the  organ 
or  part  affected  in  each  case  to  be 
specified). 

Typhoid  fever. 

Typhus  fever. 

A\^hooping-cough. 

Yellow  fever. 


1246 


VITAL  STATISTICS 


GROUP    2. OCCUPATIONAL   DISEASES   AND   INJURIES 


Arsenic  poisoning. 
Brass  poisoning. 
Carbon  monoxid  poisoning. 
Lead  poisoning. 
Mercury  poisoning. 
Natural-gas  poisoning. 
Phosphorus  poisoning. 
Wood  alcohol  poisoning. 


Naphtha  poisoning. 

Bisulphid  of  carbon  poisoning, 

Dinitrobenzine  poisoning. 

Caisson  disease  (compressed-air  ill- 
ness). 

Any  other  disease  or  disability  con- 
tracted as  a  result  of  the  nature  of 
the  person's  employment. 


Beriberi. 

Cancer. 

Continued  fever  lasting  seven  days 


GROUP    3. — MISCELLANEOUS    DISEASES 

Drug  addictions  or  habits. 
Pellagra. 


The  Results  of  Notification  in  Certain  States  and  Cities. — The  com- 
pleteness of  the  reports  of  the  notifiable  diseases  in  States  and.  cities  in 
which  there  is  registration  of  deaths  may  be  estimated  with  some  degree 
of  accuracy  by  comparing  the  number  of  cases  reported  with  the  number 
of  deaths  registered  as  due  to  the  same  cause.  In  doing  this,  however, 
it  must  be  borne  in  mind  that  we  do  not  know  the  fatality  rates  of  many 
diseases,  for  rip  to  the  present  time  there  have  seldom  been  satisfactory 
morbidity  records  of  sufficiently  broad  application  to  permit  of  the  de- 
termination of  such  rates,  and  it  must  also  be  remembered  that  the  fatal- 

Diphtheria,  measles  and  typhoid  fever — Cases  reported,  deaths  registered,  indi- 
cated case  rates  per  1,000  population,  indicated  fatality  rates  per  JOG  cases, 
and  number  of  cases  reported  for  each  fatality  registered,  in  certain  cities, 
1917. 


Indicated 

Indicated 

Number  of 

Total   Cases 

Total  Deaths 

Case  Rate 

Fatality 

Cases 

States  and  Cities 

Reported, 

Registered, 

per  Annum 

Rate 

Notified 

1914 

1914 

per  1,000 

per  100 

for  Bach 

Inhabitants 

Cases 

Fatality 

Diphtheria 

Boston,  Mass 

4,098 

276 

5.337 

6.73 

15 

Cincinnati,  Ohio    .  .  . 

814 

47 

1.965 

5.77 

17 

Benver,  Colo 

404 

20 

1.505 

4.95 

20 

Detroit,  Mich 

4.477 

409 

7.225 

9.14 

11 

New  Orleans,  La.  .  .  . 

873 

32 

2.316 

3.67 

27 

San  Francisco,  Cal.  . 

860 

68 

1.826 

7.91 

13 

Measles 

Boston,  Mass 

5,695 

101 

7.417 

1.77 

56 

Cincinnati,   Ohio    .  .  . 

1,100 

20 

2.655 

1.82 

55 

Denver,  Colo 

5,376 

18 

20.027 

.33 

299 

Detroit,  Mich 

1,278 

57 

2.062 

4.46 

22 

New  Orleans,  La.  .  .  . 

5,500 

56 

14.588 

1.02 

98 

San  Francisco,  Cal.  . 

5,180 

36 

10.997 

.69 

144 

Typhoid  Fever 

Boston,  Mass 

201 

22 

.262 

10.95 

9 

Cincinnati,   Ohio    .  .  . 

89 

16 

.215 

17.98 

6 

Denver,  Colo 

108 

14 

.402 

12.96 

8 

Detroit,  Mich 

450 

107 

.726 

23.78 

4     - 

Xew  Orleans,  La.  .  .  . 

405 

87 

1.074 

21.48 

5 

San  Francisco,  Cal.  . 

194 

23 

.412 

11.86 

8 

MORBIDITY  STATISTICS 


1247 


ity  ratos  of  luiiiiy  diseases  vaiv  in  diireroiit  epidciuics,  and  from  year  to 
year,  and  with  the  season  and  ^'eoi:ra|>hic  location. 

To  sec  the  {>ossil)ilities  of  notification  and  tlie  results  heing  ob- 
tained in  certain  diseases  in  those  States  and  cities  in  which  notification 
has  been  developed  to  a  degree  ai)proaching  most  closely  one  that  is 
satisfai  tory,  refer  to  the  table  on  page  124(). 

Source  of  Statistical  Data. — The  manner  of  collecting  the  data  from 
which  morbidity  statistics  are  compiled  is  closely  allied  to  the  regi.stra- 
tion  method  ns-^d  for  births.    The  data  consist  of  the  reports  of  cases  of 

1905  raio 


1885 


1890 


1895 


1900 


n 

~i 

f— 

'~~ 

' 

^ 

9 

8 

\ 

/ 

"s 

N 

A 

\, 

7 

\ 

6 

/ 

/ 

5 

( 

s 

/ 

\ 

/ 

/ 

^ 

7^ 

^ 

^^ 

v 

\ 

A 

■"" 

— 

f- 

3 

2. 

7 

_j 

__j 

_^ 

Fig.  147. — Diphtheria. 

Number  of  cases  notified  per   annum  for   each   death   registered — Michigan, 
1884  to   1912. 


disease  made  usually  by  physicians  and  in  some  instances  by  the  heads 
of  families  and  households.  The  original  observers  then,  upon  whom 
morbidity  statistics  depend  chiefly  for  their  completeness,  are  the  prac- 
ticing physicians.  This  is  necessarily  so,  for  neither  the  health  depart- 
ment nor  any  other  branch  of  government  can  keep  in  such  close  touch 
with  the  lives  of  the  people  as  to  be  in  a  position  to  know  of  the  occur- 
rence of  disease.  The  physician  is  the  one  who,  because  of. the  ver\^ 
nature  of  his  work  and  his  relation  to  the  community,  is  best  able  to 
have  this  information  and  furnish  it.  He  comes  in  contact  with  the  sick 
to  a  degree  others  do  not.  The  health  officer  cannot  know  of  the  pres- 
ence of  disease  except  as  it  is  reported  to  him  by  physicians.  Experi- 
ence has  shown  that  there  may  be  hundreds  of  cases  of  a  dangerous 
infection  in  a  city  and  the  health  officer  not  know  of  its  presence  in  the 
absence  of  notification. 


1248 


VITAL  STATISTICS 


Unfortunately  many  practicing  physicians  have  little  knowledge  of 
the  methods  of  health  administration  and  in  common  with  people  in  gen- 
eral frequently  expect  the  health  department  in  some  mysterious  man- 


1885 

1890 

1895 

1900 

1905 

1910 

915 

/ 

S, 

/ 

s. 

/ 

^ 

^ 

\ 

9U00 

\ 

4000 

\ 

' 

1 

/ 

2000 

\ 

} 

s, 

/ 

\ 

/ 

/ 

\ 

I 

/ 

\ 

1000 

^ 

/ 

^     K! 

■ 

/ 

_ 

_ 

__ 

= 



^ 

^ 

_ 

^'\ 

— 

Fig.  148. — Smal-lpox. 
Number  of  cases  notified  per  annum  in  Michigan  from  1883  to  1915. 

ner  to  control  disease  without  placing  upon  them  the  burden  and  privi- 
lege of  cooperating  by  the  notification  of  the  occurrence  of  cases.  The 
practicing  physician,  whether  he  recognizes  it  or  not,  or  is  so  recognized 


1885 

I89C 

> 

1895 

I90C 

I90S 

1910 

9l5 

1 

7 

T 

- 

/inn 

1 

/" 

■  - 

ft 

^ 

~ 

■  ■" 

/ 

7 

1 1 

/ 

3nn 

/" 

) 

r 

~ 

"~ 

"' 

/ 

-q 

i— 

/ 

/ 

EGO 

-J 

i 

■^ 

/ 

' — 

( 

) 

"^i 

^ 

f— 

, 

■" 

^~ 

""■ 

c 

■ 

l^ 

^ 

5! 

P 

f). 

I 

i 

inn 

^ 

Z 

QJ 

^ 
^ 

i 

j 

^ 

^ 

"^ 

% 

i 

r 

- 

■"— 

'■"' 

— 

<o 

^ 

<z 

"^ 

^ 

/ 

1'- 

"^ 

,^ 

< 

1 

[— 

~ 

^ 

3 

=^ 

^^ 

.^- 

_ 

_, 

, 

~ 

e= 

_ 

Fig.  149. — Smallpox. 
Number   of  cases  notified   per  annum  for  each  death  registered — ^Michigan, 
188.3    to    1915.      In    1914    there    were    1527    cases   notified   and   only   one    death 
registered. 

by  the  community,  is  essentially  an  adjunct  of  the  health  department, 
for,  unless  he  performs  his  part,  the  health  department  is  in  large  measure 
helpless. 


MORBIDITY  STATISTICS 


1249 


1865 

1890 

1895 

1500 

1905 

1910 

1915 

40 

35 

30 

/ 

^ 

1 

/ 

\ 

j 

25 

\ 

/ 

— ■ 

1 

s 

/ 

\ 

/ 

X 

\ 

/ 

N 

/ 

\ 

/ 

20 

/ 

^ 

/ 

/ 

\ 

/ 

1 

\ 

/ 

/ 

\ 

/ 

\ 

/ 

\ 

1 

15 

/ 

\, 

/ 

^ 

/ 

> 

f 

/ 

\ 

/ 

/ 

10 

1 

\ 

k~_ 

/ 

5 

KiG.  l.")0. — Scarlet  Fevek. 
Number   of  cases   notified   per   anniira   for   each   death   registered — Michigan, 
1884  to  1915. 


1890 

1895 

1900 

1905 

1910 

I9i5 

300 

250 

200 

' 

j 

\ 

150 

/ 

1 

/ 

\ 

1 

\ 

/ 

\ 

100 

1 

/ 

V 

vj 

\ 

\ 

\ 

50 

N 

/ 

^ 

y 

N, 

,/ 

\ 

k' 

\ 

^ 

/ 

V 

/ 

N 

y 

\ 

/ 

_ 

_ 

_ 

_ 

_ 

Fig.  151. — Measles. 
Number  of  cases  notified  per  annum  for  each  death  registered — Michigan, 
1890  to  1917. 


1250  VITAL  STATISTICS 

Among  practicing  physicians,  at  least  in  the  United  States,  there  has 
at  times  been  the  feeling  that  the  knowledge  of  a  disease  in  a  patient  is 
privileged  information  which  they  should  not  be  called  upon  to  impArt. 
In  communities  where  the  laws  require  the  notification  of  the  disease  this 
feeling  has  no  legal  basis  and  the  physician  who  does  not  make  report  is 
not  a  law-abiding  citizen.  But  aside  from  the  legal  aspects  of  the  matter 
there  would  seem  to  be  little  justification  for  such  a  course.  Every  phy- 
sician has  a  number  of  individuals  or  families  who  look  to  him,  and 
properly  so,  not  only  for  treatment,  but  also  for  such  reasonable  protec- 
tion from  disease  as  he  is  able  to  give.  The  failure  to  report  the  occur- 
rence of  a  case  of  communicable  disease  in  one  patient  may  lead  to  its 
spread  to  others  among  his  clientele  whose  rights  he  has  ignored.  He 
therefore  violates  the  intent  and  spirit  of  the  ethical  principle  of  the 
protection  of  patients  among  whom  must  be  considered  the  well  together 
with  the  sick.  The  notification  of  disease  is  in  the  interests  and  for 
the  protection  of  the  community,  and  as  his  patients  are  members 
of  the  community  their  interests  are  ignored  and,  because  of  the  anti- 
social whim  or  supposed  convenience  of  the  individual  affected  with  a 
notifiable  disease,  they  are  deprived  of  the  protection  they  have  a  right  to 
expect.  It  would  seem  that  the  physician  who  fails  to  report  his  cases 
of  preventable  diseases  required  to  be  notified  may  properly  be  consid- 
ered as  actively  obstructing  public  health  administration, 

Eelated  in  thought  is  the  following  quotation  from  an  address  by 
Prof.  Victor  C.  Vaughan :  ^ 

In  the  future  the  training  of  the  medical  man  must  be  developed  largely 
with  a  view  to  his  broader  relations  to  the  public.  His  proper  function 
must  be  to  prevent,  rather  than  cure  disease.  The  physician's  duties  are 
to  become  more  and  more  largely  official  in  the  sense  that  his  services  are 
to  be  rendered  to  the  community,  and  not  exclusively  to  the  individual. 

The  health  department  laboratory  may  be,  and  in  many  places  is, 
an  important  factor  in  giving  information  of  the  occurrence  of  cases 
and  prevalence  of  certain  diseases.  By  having  a  diagnostic  laboratory 
with  a  trained  personnel  at  the  service  of  the  practicing  physician  the 
health  department  becomes  not  only  a  consultant  performing  gratuitous 
service  for  the  physician  but  at  the  same  time  secures  early  and  accu- 
rate information  of  many  cases  which  otherwise  might  not  be  properly 
diagnosed  and  therefore  not  reported.  A  record  of  every  positive  diag- 
nosis made  by  the  laboratory  should  be  sent  to  the  epidemiological  bureau , 
or  other  division  of  the  health  department  responsible  for  the  control 
of  disease  and  should  for  purposes  of  morbidity  records  constitute  notifi- 
cation of  the  case  when  accompanied  by  such  necessary  information  as 
the  name,  age,  sex,  and  address  of  the  patient.  There  would  seem  to 
be  no  good  reason  why  the  services  of  the  health  department  should  not 
^Pennsylvania  Medical  Journal,  November,  1913. 


MORBIDITY  STATISTICS  1251 

be  at  the  disposal  ct'  the  (•(iiiiiuunity   tor  llif  fliauiiosis  of  all  diseases. 

Nature  of  Information  Secured  by  Morbidity  Notification. — It  is  the 
practice  for  health  (U'pardneiits  to  furnish  to  physicians  notification 
blanks  upon  which  the  reports  are  to  be  made.  In  some  instances 
these  are  in  the  form  of  post-cards,  whicii  have  proper  spaces  indicated 
for  notation  of  the  reqiiired  information.  These  cards  require  the 
physician  to  affix  a  stamp  ijefore  mailinfr  them  to  the  health  department. 
A  far  better  practice  is  that  employed  by  many  States  and  cities  of  sup- 
plying physicians  with  postal-card  forms  which  do  not  require  addi- 
tional postage  before  mailing. 

The  information  relating  to  the  reported  cases  which  physicians  are 
required  to  give  varies  in  the  several  States.  It  has  been  customary 
to  require  the  physician,  in  making  his  report,  to  include  all  the 
data  regarding  the  case  desired  by  the  health  department.  In  the 
majority  of  instances  no  further  data  regarding  these  cases  are  secured 
by  the  health  officials.  "While  it  may  be  impracticable  in  most  instances 
to  change  this  practice  at  the  present  time,  it  must  be  recognized  that 
a  local  health  department  should  prefer  to  collect  its  data  regarding 
each  case  itself,  and  should  not  be  willing  to  depend  upon  the  physician's 
report  for  its  epidemiologic  information.  Logically,  the  only  informa- 
tion which  the  physician  should  be  depended  upon  to  give  in  his  report 
is  the  occurrence  of  a  case,  or  a  suspected  case,  of  a  given  disease  in  such 
and  such  a  person  at  such  and  such  an  address.  He  might  properly 
be  required  to  add  to  this  such  data  as  are  matters  of  record  or  easily 
verified,  such  as  the  age,  color,  and  sex  of  the  patient,  and  similar  in- 
formation. The  local  health  department,  however,  should  be  reluctant 
to  depend  upon  the  diagnosis  of  the  practicing  physician,  unless  the  diag- 
nosis has  been  verified  by  a  trained  diagnostician  in  the  service  of  the 
department  itself.  This  has  been  the  practice  during  recent  outlDreaks 
of  such  diseases  as  yellow  fever  and  plague.  It  is  also  the  practice  in 
certain  other  instances.  It  must  necessarily  become  the  practice  when- 
ever a  determined  effort  is  to  be  made  in  the  control  of  any  preventable 
disease. 

The  Standard  Notification  Blank. — The  standard  notification  blank 
approved  by  the  State  and  Territorial  health  authorities  of  the  United 
States  in  conference  with  the  Public  Health  Service  at  their  tenth  an- 
nual conference  in  June,  1913,  calls  for  the  following  inform-ation : 

1.  Date. 

2.  Name  of  disease  or  suspected  disease. 

3.  Patient's  name,  age,  sex,  color,  and  address.     (This  is  largely  for  pur- 

poses of  identification  and  location.) 

4.  Patient's  occupation.     (This  serves  to  show  both  the  possible  origin  of 

the  disease  and  the  probability  that  others  have  been  or  may  be 
exposed.) 


1252  VITAL  STATISTICS 

5.  School  attended  by  or  place  of  employment  of  patient.     (Serves  same 

purpose  as  the  preceding.) 

6.  Number  of  persons  in  the  household,  number  of  adults  and  number  of 

children.  (To  indicate  the  nature  of  the  household  and  the  prob- 
able danger  of  the  spread  of  the  disease.) 

7.  The  physician's  opinion  of  the  probable  source  of  infection  or  origin 

of  the  disease.  (This  gives  important  information  and  frequently 
reveals  unreported  cases.  It  is  of  particular  value  in  occupational 
diseases.) 

8.  If  the  disease  is  smallpox,  the  type   (whether  the  mild  or  virulent 

strain)  and  the  number  of  times  the  patient  has  been  successfully 
vaccinated,  and  the  approximate  dates.  (This  gives  the  vaccination 
status  and  history.) 

9.  If  the  disease  is  typhoid  fever,  scarlet  fever,  diphtheria,  or  septic  sore 

throat,  whether  the  patient  had  been  or  whether  any  member  of  the 
household  is  engaged  in  the  production  or  handling  of  milk. 
(These  diseases  being  frequently  spxead  through  milk,  this  informa- 
tion is  important  to  indicate  measures  to  prevent  further  spread.) 
10.     Address  and  signature  of  the  physician  making  the  report. 

These  reports  are  to  be  made  on  postal  cards  furnished  for  the 
purpose  and  mailed  immediately  to  the  local  health  department,  so 
that  proper  measures  can  be  taken  to  prevent  the  spread  of  the  disease 
or  to  find  the  focus  or  source  from  which  the  case  originated,  that  the 
occurrence  of  additional  cases  may  be  prevented.  These  reports  are  then 
to  be  forwarded  to  the  State  department  of  health,  but  before  being 
forwarded  the  local  health  department  is  to  note  thereon: 

1.  Whether  the  case  was  investigated  by  the  local  health  department. 

2.  Whether  the  nature  of  the  disease  was  verified. 

3.  What  measures  were  taken  by  the  local  health  department  to  prevent 

the  spread  of  the  disease  or  the  occurrence  of  additional  cases  from 
the  same  origin. 

Sources  of  Error  in  Morbidity  Statistics. — The  errors  in  morbidity 
statistics  of  civil  populations  are  due  principally  to  incomplete  notifica- 
tion— that  is,  to  the  failure  of  physicians  to  report  all  cases  of  the  noti- 
fiable diseases.  More  cases  of  disease  usually  occur  than  are  reported. 
This  can  never  be  entirely  overcome,  for  many  diseases  vary  in  severity 
under  different  conditions,  and  some  cases  are  so  mild  that  their  true 
nature  is  not  recognized,  and  frequently  they  do  not  come  to  the  at- 
tention of  physicians. 

The  cases  notified  are  usually  correctly  diagnosed,  for  physicians 
do  not  generally  report  cases  until  they  are  practically  sure  of  the 
diagnosis,  as  the  case  remains  an  evidence  of  faulty  diagnosis  if  a 
mistake  is  made.     Then,  too,  physicians  naturally  wish  to  report  only 


MORBIDITY  STATISTICS  1253 

those  cases  required  and  to  know  wlidlici-  a  ,i;i\i'ii  case  is  one  of  these 
he  must  fir^t  be  reasoiiablv  sure  of  his  diagnosis. 

The  errors  in  niorhidily  statistics  arc  therefore  chietly  those  of  in- 
completeness. In  this  tliey  resemble  liirth  statistics,  ah  hough  the 
degree  of  incom])h'teness,  (hu'  to  the  dilfcrence  in  the  nature  of  the  two, 
is  usually  greater  in  morl)idity  statistics. 

They  differ  from  mortality  statistics,  in  Avhich  the  ])i-in(i)ial  source 
of  error  is  iiu'orrect  statements  of  cause  of  (h'ath.  Due  to  the  control 
possible  over  the  disposal  of  bodies  of  the  dead,  it  is  not  difficult  in 
most  communities  to  obtain  practically  complete  registration  of  deaths. 
It  is,  however,  exceedingly  difficult  to  secure  correct  statements  of  the 
causes  of  death.  The  physician  feels  compelled  to  give  a  diagnosis  in 
each  death  certificate  and  usually  does  so  even  when  he  is  uncertain  of 
the  nature  of  the  malady,  realizing  probably  that  the  body  will  be  buried 
and  that  there  will  be  nothing  to  show  the  error  if  one  is  made. 

The  tendency  is  then  in  morbidity  reports  for  the  diagnoses  to  be 
correctly  given,  but  not  all  cases  reported,  while  in  the  registration  of 
deaths  the  tendency  is  for  the  recording  of  practically  all  deaths  but 
the  filing  of  many  incorrect  statements  of  the  causes  of  death. 

Uses  of  Morbidity  Reports  and  Statistics. — In  health  administration, 
morbidity  reports — that  is,  reports  of  cases  of  sickness — serve  several 
purposes,  which  may  be  briefly  stated  to  be  as  follows : 

1.  In  the  communicable  diseases  morbidity  reports  show  the  occur- 
rence of  cases  which  constitute  foci  from  which  the  disease  may  spread 
to  others,  as  in  scarlet  fever,  typhoid  fever,  tuberculosis,  or  yellow  fever, 
and  make  it  possible  to  take  proper  precautions  to  protect  the  family  of 
the  patient,  his  associates,  or  the  community  at  large. 

2.  In  some  diseases  morbidity  reports  make  it  possible  to  see  that 
the  sick  receive  proper  treatment,  as  in  ophthalmia  neonatorum,  diph- 
theria, and,  in  certain  cities,  tuberculosis.  The  reporting  of  cases  of 
ophthalmia  in  the  newborn  makes  it  possible  to  save  the  sight  of  some 
infants  who  would  otherwise  not  receive  adequate  treatment  until  after 
much  damage  had  been  done.  In  diphtheria  the  health  department  can 
be  of  service  in  furnishing  antitoxin.  Some  cities  furnish  hospital  or 
other  relief  to  consumptives  who  would  otherwise  be  without  proper 
treatment. 

3.  In  diseases  that  are  not  communicable,  such  as  those  due  to 
occupation  or  environment,  reported  cases  show  the  location  of  con- 
ditions which  are  causing  illness  or  injury.  This  makes  it  possible 
to  remedy  the  faulty  conditions,  so  that  others  may  not  be  similarly 
injured. 

4.  In  certain  diseases,  of  which  the  cause  or  means  of  spread  is 
unknown,  morbidity  reports  show  their  geographic  distribution  and 
varying  prevalence  and  the  conditions  under  which  cases  occur.     This 


1254  VITAL  STATISTICS 

information  has  great  potential   value  in   attempts   to   ascertain  their 
causes  and  means  of  spread. 

5.  Eeports  of  the  occurrence  of  disease  are  necessary  to  show  the 
need  of  certain  sanitary  measures  or  works  and  to  control  and  check 
the  efficiency  of  such  measures  or  works  when  put  into  operation.  In 
pulmonary  tuberculosis  such  reports  show  the  number  of  consumptives 
in  the  community  and  the  need  of  sanatoria.  In  malaria  they  show 
the  prevalence  of  the  disease,  the  need  for  drainage  and  other'  anti- 
mosquito  work,  the  efficiency  of  such  work  when  in  operation,  and  when 
a  change  in  the  prophylactic  measures  or  additional  ones  are  necessary. 
In  typhoid  fever  they  show  faults  in  the  water  supply  or  in  the  control 
of  the  production  and  distribution  of  milk  or  in  the  disposal  of  excreta 
in  special  localities. 

6.  Morbidity  reports  when  recorded  over  a  period  of  time  and  prop- 
erly compiled  become  a  record  of  the  past  occurrence  of  disease.  They 
show  the  relative  prevalence  of  disease,  from  year  to  year  and  under 
varying  conditions.  They  show  the  effect  of  the  introduction  of  public- 
health  measures  and  of  sanitary  works.  They  give  a  history  of  disease 
not  obtainable  in  their  absence. 

Morbidity  Rates — Crude  Morbidity  Bates. — Morbidity  rates  may 
be  expressed  as  the  number  of  cases  of  a  given  disease  occurring  during  a 
year  per  1,000  of  the  total  population,  or  the  rate  may  be  expressed  as 
the  number  of  cases  per  10,000  or  per  100,000  population.  These  are 
crude  rates.  Giving  the  rate  per  1,000  population  has  the  advantage 
of  employing  the  same  population  unit  as  that  used  for  expressing  birth, 
marriage,  and  death  rates.  It  has,  however,  what  has  been  considered  by 
some  a  disadvantage,  namely,  that  the  rates  will  frequently  be  expressed 
by  fractions  where  the  1,000  unit  of  population  is  taken  as  the  basis. 
For  this  reason  10,000  and  100,000  population  units  have  often  been 
used. 

Specific  Morbidity  Bates. — Diseases  limited  entirely  or  principally 
to  certain  ages  or  to  certain  classes  of  the  population  should  be  ex- 
pressed also  in  rates  of  the  number  of  cases  per  1,000  persons  in  the 
population  of  that  age  or  class.  Diseases  limited  to  childhood  should 
be  expressed  as  rates  per  1,000  children;  diseases  limited  to  women 
should  be  expressed  as  rates  per  1,000  women.  Occupational  disease 
rates  should  be  expressed  in  terms  of  the  number  of  cases  per  1,000 
persons  employed.     These  are  specific  rates. 

Specific  morbidity  rates  showing  the  incidence  of  disease  by  age 
groups,  sex,  occupation,  and  economic  or  social  condition  will  be  possi- 
ble with  the  improved  notification  methods  which  are  being  gradually 
adopted. 

Case  Fatality  Bates. — The  case  fatality  rate  of  a  disease  is 
usually   expressed   in  terms  of  the   number   of   deaths  per   100   cases; 


MORBIDITY  STATISTICS  1255 

thai  is,  as  the  jiercentaf^'e  of  cases  which  terminate  fatally.  For  ex- 
amj)lc,  if  out  of  100  cases  of  typhoid  fever  10  die,  the  case  fatality 
rate  is  10  per  hundred  or  10  ])cr  cent.  In  calculatinf^  fatality  rates 
it  is  to  he  horiu"  in  mind  llial  aiiion^  cases  reported  during  one  week, 
month,  or  year,  all  or  part  of  the  fatal  tcnninnl  ions  may  occur  during 
a  succeeding  M'(>ek,  month,  or  year. 

Hospital  Statistics  and  Sickness  Insurance  Records. — In  a  nurnher 
of  foreign  countries  much  valuahle  information  regarding  sickness  rates, 
aside  from  that  of  the  commonly  notifiahle  diseases,  is  being  secured 
from  the  workingmen's  sickness  insurance  records.  In  some  countries 
hospital  statistics  are  compiled  and  furnish  data  of  much  value.  Bold- 
uan  *  suggested  a  plan  for  compiling  hospital  morbidity  statistics  in 
this  country.  The  method  is  especially  applicable  to  the  hospitals  of 
a  large  city,  but  might  be  used  for  the  hospitals  of  an  entire  State 
and  is  capable  of  being  made  nation-wide  in  scope.  The  essential  fea- 
ture of  the  plan  is  the  filling  out  of  "discharge  certificates,"  analogoiis 
to  ordinary  death  certificates,  on  the  discharge  of  each  patient  from  a 
hospital.  These  discharge  certificates  are  then  to  be  sent  to  a  central 
filing  bureau,  preferably  the  health  department,  and  there  classified 
and  analyzed. 

It  is  also  especially  desirable  to  have  statistics  of  the  insane  and 
mentally  defective.  New  Jersey  has  enacted  a  law  requiring  the  notifi- 
cation of  cases  of  mental  deficiency  and  of  epilepsy. 

Factors  Influencing'  Morbidity  Rates. — The  factors  which  influence 
morbidity  rates  and  the  prevalence  of  sickness  are  the  manifold  direct 
and  indirect  causes  of  disease.  There  are  certain  widely  acting  indirect 
factors  which  increase  morbidity  by  lessening  individual  resistance. 
There  are  other  factors  which  are  specific  for  individual  diseases.  In 
malaria  the  direct  cause  is  infectious  anopheline  mosquitoes,  and  the 
indirect  cause  swamps  and  stagnant  water  in  which  the  mosquitoes 
breed.  The  factors-  influencing  typhoid  fever  rates  are  commonly  the 
milk  supply,  the  water  supply,  the  manner  of  disposal  of  excreta, 
presence  of  flies,  the  extent  to  which  houses  are  screened,  personal  and 
social  habits,  etc.  In  an  industrial  community  the  morbidity  from  occu- 
pational diseases  and  from  diseases  caused  indirectly  by  the  conditions 
attending  certain  kinds  of  labor  constitutes  a  factor  the  importance  of 
which  is  beginning  to  be  realized. 

Notification  of  Occupational  Diseases. — Most  civilized  nations  have 
during  the  last  hundred  years  undergone  an  industrial  evolution.  It 
has  been  within  this  period  that  the  large  factory  with  its  hundreds 
or  thousands  of  workers  has  had  its  development  and  that  many  of  our 
present  industries  and  the  majority  of  our  industrial  processes  have  been 

*  Bolduan,  Charles  F. :  "Hospital  Morbidity  Statistics,"  New  York  Medical 
Jov/mal,  March,  1913,  p.  643. 


1256  VITAL  STATISTICS 

developed.  So  great  has  been  this  change  in  the  industrial  life  of  the 
people  that  there  has  been  developed  a  new  and  important  branch  of 
hygiene  and  sanitation  which  is  properly  termed  industrial  hygiene. 
With  this  industrial  development  there  have  evolved  new  diseases  and 
disabilities  due  to  the  nature  of  the  individual's  work  or  to  the  condi- 
tions incident  to  the  work.  Not  only  have  new  diseases  in  a  sense  been 
evolved,  but  a  number  of  diseases  previously  rare  have  become  much 
more  common.  Under  existing  social  conditions  a  large  proportion  of 
the  people  are  engaged  in  some  occupation,  and  the  diseases  of  occupa- 
tion merit  the  attention  and  consideration  of  the  community. 

The  control  of  occupational  diseases  has  during  the  last  few  years 
been  receiving  much  consideration.  Naturally  the  first  step  in  the 
control  of  the  industrial  diseases  was  the  securing  of  a  means  by  which 
the  occurrence  and  prevalence  of  these  diseases  might  be  Jvnown  to 
those  whose  duty  it  would  be  to  control  them.  For  this  purpose,  and 
largely  because  of  the  activities  of  the  American  Association  for  Labor 
Legislation,  a  number  of  States  have  since  1911  enacted  laws  requiring 
the  notification  of  certain  occupational  diseases. 

A  number  of  State  laws  require  cases  of  occupational  diseases  to  be 
notified  to  the  State  health  department,  and  others  require  the  notifi- 
cations to  be  made  to  the  State  labor  office.  The  results  of  notification 
have  not  been  as  yet  satisfactory.  This  may  be  diie  to  the  newness  of  the 
idea  to  the  physician  of  considering  whether  a  disease  is  occupational  in 
origin.  The  medical  schools  have  given  little  attention  to  the  subject. 
It  is  highly  important  to  the  practicing  physician  that  he  have  a  knowl- 
edge of  the  industries  of  his  community  and  of  the  diseases  and  disabil- 
ities they  are  likely  to  cause.  The  proper  and  successful  treatment  of 
patients  necessarily  depends  upon  a  knowledge  of  the  direct  or  indirect 
cause  of  the  individual's  ailment,  and  in  an  industrial  community  this 
will  depend  frequently  upon  a  knowledge  of  occupational  diseases. 

A  number  of  States  have  enacted  laws  which  should  in  a  way  be 
much  more  successful  in  bringing  to  light  the  occurrence  of  these  dis- 
eases (Illinois,  Missouri,  Ohio,  and  Pennsylvania).  The  plan  referred 
to  is  that  of  requiring  certain  industries  to  have  their  employees  ex- 
amined physically  by  competent  physicians  at  stated  intervals  to  ascer- 
tain whether  there  exist  in  the  employees  any  ailments  or  disabilities 
due  to  the  nature  of  their  occupation.  The  physicians  making  these 
examinations  naturally  become  in  time  expert,  if  they  are  not  so  in  the 
beginning,  and  the  examination  of  the  employees  in  this  way  will  guar- 
antee the  finding  of  a  large  proportion  of  the  cases  of  industrial  dis- 
eases, in  most  instances  in  their  earlier  stages.  If  the  occupational 
diseases  are  to  be  controlled,  it  is  necessary  that  the  occurrence  of 
cases  be  ascertained  in  some  way,  for  the  occurrence  of  each  case  shows 
the  existence  of  conditions  which  have  produced  disease  in  one  employee 


MORBIDITY  STATISTICS  1257 

and  will  in  all  probability  produce  it  in  olliors.  Each  case  notified 
shows  a  danger  spot. 

Morbidity  Statistics  of  Military  Populations. — Military  organiza- 
tions oU'er  a  much  better  opportunity  for  the  recording  of  morbidity  data 
than  do  civil  populations.  In  military  organizations  all  persons  are 
under  constant  supervision  and  all  but  the  most  trivial  illnesses  be- 
come a  matter  of  record.  This  includes  not  only  the  cases  of  those 
diseases  which  are  ordinarily  reportable  among  civil  populations  but 
cases  of  other  illnesses  and  disabilities  as  well.  The  limitations  of  mili- 
tary morbidity  statistics  are  confined  largely  to  the  question  of  diag- 
nosis, but  even  the  dependability  of  diagnosis  is  probably  greater  in 
military  organizations  because  the  medical  officers  are  a  selected  group 
and  because  of  the  added  measures  of  control. 

Military  morbidity  statistics  may  be  exceedingly  useful  in  determin- 
ing the  geographic  distribution,  and  in  a  measure  the  relative  preva^ 
lence,  of  certain  diseases  throughout  the  country.  They  may  be  of 
particular  value  for  this  purpose  in  localities  where  these  diseases  are 
not  reportable  or  are  at  best  very  incompletely  reported  among  the 
civil  population.  Thus  records  of  the  incidence  of  malaria  at  military 
posts  and  camps  will  give  information  not  otherwise  obtainable  of  the 
prevalence  of  this  disease.  This  is  particularly  true  under  conditions 
existing  in  times  of  peace,  and  is  illustrated  by  the  records  of  the  troops 
at  Fort  Washington.  Fort  Washington  is  in  Prince  Georges  County, 
Maryland,  about  12  miles  south  of  the  city  of  Washington.  For  sev- 
eral years  up  to  1913  the  troops  at  Fort  Washington  had  the  highest 
malaria  rate  of  any  army  post  in  the  United  States.  The  malaria  ad- 
mission rate  had  varied  from  736  per  1,000  strength  in  1906  to  172 
per  1,000  in  1912.  And  yet  during  this  same  period  the  morbidity 
records  of  the  state  of  Maryland  showed  practically  no  malaria  in  Prince 
Georges  County.  This  was  so  notwithstanding  the  fact  that  at  the  time 
the  morbidity  records  of  the  state  as  regards  other  diseases  compared 
very  favorably  with  the  better  records  of  civil  populations  in  other 
states.  However,  the  civil  records  of  Maryland  gave  no  idea  whatsoever 
of  the  prevalence  of  malaria  and  had  the  disadvantage  of  appearing 
to  give  information  when  they  did  not. 

The  value  of  military  morbidity  records  to  show  the  geographic  dis- 
tribution of  disease  is  limited,  however,  largely  to  diseases  which  are 
endemic  or  pertain  particularly  to  localities  of  which  malaria  is  one  of 
the  most  typical. 

Some  of  the  terms  used  in  stating  morbidity  data  of  military  groups 
differ  from  the  corresponding  terms  used  for  civil  populations.  Thus 
in  the  Xavy  the  population  of  a  vessel  or  other  Xaval  unit  is  known 
as  the  "Complement."  In  the  army  the  military  population  of  a  camp 
or  other  military  group  is  commonly  termed  the  "Strength." 


1258 


VITAL  STATISTICS 


Admission  Rate. — Ordinarily  in  military  organizations  every  person 
reporting  ill  or  disabled  is  considered  as  "admitted"  to  the  sick  list  and 
the  total  number  so  reporting  constitutes  the  total  admissions.  For 
some  ailments  a.  soldier  or  sailor  may  apparently  recover  and  be  dis- 
charged from  the  sick  list,  but  have  relapses  and  be  readmitted  in  some 
instances  several  times.  To  this  extent  the  total  admissions  do  not 
show  the  total  number  of  cases  of  disease  or  disability.  The  first  ad- 
mission of  an  individual  for  a  case  of  illness  constitutes  the  original 
admission  and  the  subsequent  admissions  for  the  same  illness  or  dis- 
ability are  "readmissions."  The  number  of  original  admissions  there- 
fore gives  the  number  of  actual  cases.  The  term  "admission  rate"' 
corresponds  to  the  term  "morbidity  rate"  as  used  for  civil  populations, 
and  is  usually  expressed  as  the  number  of  original  admissions  during 
a  year  for  each  1,000  of  the  "complement"  or  "strength"  just  as  civil 
morbidity  rates  are  expressed  as  the  number  of  cases  recorded  during 
a  year  per  1,000  population.  Thus  an  admission  rate  of  640  would 
mean  that  there  had  been  640  cases  of  illness  or  disability  during  the 
year  for  each  1,000  of  the  military  population.  This  would  be  the 
crude  admission  rate.  Admission  rates  might  be  given  for  classes  of 
disease  or  disabilities  or  they  might  be  given  for  special  classes  of  the 
military  population.  These  would  be  specific  admission  rates.  This 
is  illustrated  by  the  following  two  tables,  one  taken  from  the  naval 
bulletin  issued  March  15,  1919,  the  other  from  the  annual  report  of  the 
Surgeon-General  of  the  Army  for  the  year  1917. 


MORBIDITY  RATES — NAVY 


Entire  Navy 


Admission  rate,  all  causes 
Admission  rate,  diseases 

only    

Admission  rate,  venereal 

diseases    

Cerebrospinal  fever    . .  . 

Measles    

Mumps     

Scarlet    fever    

Tuberculosis,  all   forms 

Diphtheria     

Pneumonia,  all  forms.. 

Malaria    

Typhoid  fever    

Smallpox    


1913 

1914 

1915 

1916 

19'17 

(65,926) 

(67,141) 

(68,075) 

(69,294) 

(245,580) 

511.22 

606.17 

657.26 

656.85 

534.88 

443.49 

525.46 

568.02 

561.18 

489.47 

143.09 

162.82 

151.56 

148.07 

88'.71 

.13 

.20 

.27 

.03 

1.51 

9.40 

6.43 

4.52. 

7.54 

31.32 

12.93 

11.63 

15.46 

10.47 

39.82 

.54 

.28 

.91 

1.31 

2.67 

4.89 

4.39 

3.07 

4.14 

3.24 

1.10 

.89 

.55. 

.69 

.85 

2.86 

4.34 

4.23 

3.73 

6.90 

12.07 

17.42 

17.63 

2.82 

8.32 

.31 

.19 

.26 

.23 

.26 

.57 

.07 

.07 

.05 

.04 

Combined' 

rate  for  the 

five-year 

period 
(combined 
comple- 
ment 
516,016) 

573.66 

513.91 

121.56 

.88 

18.56 

25.55 

1.67 

3.78 

.82 

5.27 

13.71 

.26 

.12 


Noneffective  Rate. — The  members  of  a  military  organization  who  are 
unable  to  perform  their  regular  military  duties  because  of  illness  or 
disability  are  known  as  noneffectives.     The  average  proportion  of  any 


MORTALITY  STATISTICS 


1259 


Influence  of  disease  on  enlisted  men,  Am^riean   troops,  serving  in   the   United 
States,  by  arms  of  service,  for  year  1916 


Mean 
strength 

Ad- 
mitted 

Dis- 
charged 
on  cer- 
tificate 
of  disa- 
bility 

Died 

Con- 
stantly 

non- 
effective 

Ratio  per  1,000  of  mean  strength 

' 

Ad- 
mitted 

Dis- 
charged 
on  cer- 
tificate 
of  disa- 
bility 

Died 

Con- 
stantly 

non- 
effective 

Infantry    .... 

Cavalry    .... 

Coast  Artil- 
lery     

Field  Artil- 
lery     

Engineers   . .  . 

Ordnance    . . . 

Signal   Corps. 

Hospital 
Corps     ..  .. 

All  others..  .  . 

16.730 
8,782 

13,999 

3,471 
927 
639 

1,056 

3.739 
12,067 

12,472 
7.846 

9.459 

3,158 
811 
S50 
616 

2,685 
8,377 

625 
244 

280 

95 

52 

4 

24 

114 

187 

102 
66 

62 

19 
5 
4 
5 

19 

66 

537.19 
356.41 

364.89 

117.27 
56.14 
11.98 
27.30 

100.30 
312.23 

745.49 
893.42 

675.69 

909.82 
874.86 
547.73 
583.33 

718.11 
694.21 

37.36 
27.78 

20.00 

27.37 

56.10 

6.26 

22.73 

30.49 
15.50 

6.10 
7.52 

4.43 

5.47 
5.39 
6.26 
4.73 

5.08 
5.47 

32.11 
40.58 

26.07 

33.79 
60.56 
18.75 
25.85 

ZB.83 
25.87 

Total    ... 

61,410 

45.774 

1,625 

348 

774.42 

745.38 

26.46 

5.67 

28.89 

organization  thus  unavailable  for  duty  is  known  as  the  noneffective 
rate,  and  is  expressed  as  the  average  daily  number  noneffective  per  100 
or  per  1,000  of  the  "complement"  or  "strength." 


MORTALITY  STATISTICS 


Mortality  statistics  are  statistics  of  deaths.  They  are  of  interest 
primarily  because  of  their  relation  to  changes  in  population.  Aside 
from  the  factor  of  emigration,  mortality  statistics  show  the  losses  in 
numbers  being  sustained  by  the  population,  just  as  birth  records  show 
the  additions.  Where  migration  is  a  factor  having  an  appreciable 
effect  upon  population  it  likewise  merits  statistical  consideration,  for 
it,  too,  represents  population  gains  and  losses. 

Mortality  statistics  have  performed  another  important  service  in 
creating  an  interest  in  public  health  administration  and  securing"  sup- 
port for  sanitary  measures.  They  show  the  extent  of  the  loss  by  death 
caused  by  diseases.  In  the  absence  of  morbidity  records  they  have  also 
frequently  been  used  as  an  index  of  the  prevalence  of  certain  infections. 
It  has  been  possible  to  use  mortality  statistics  for  the  latter  purpose  on 
the  assumption  that  the  fatality  rates  of  disease  are  fairly  constant. 
However,  we  should  bear  in  mind  what  Newsholme  has  said : 

"The  registration  of  deaths  gives  a  very  imperfect  view  of  the  preva- 
lence of  disease.  *  *  *  It  is  fallacious  to  assume  any  fixed  ratio  be- 
tween sickness  and  mortality.  The  fatality  of  a  given  infectious  disease 
varies  greatly  in  different  outbreaks  under  varying  conditions.     The 


1260 


VITAL  STATISTICS 


highest  ratio  of  sickness  is  occasionally  found  associated  with  a  favor- 
able rate  of  mortality.'* 

This  absence  of  fixed  fatality  rates  is  shown  by  the  experience  in 
the  United  States  with  smallpox,  in  which  the  ratio  of  deaths  to  cases 
has  varied  from  1:1,000  to  1:3;  measles,  in  which  the  ratio  of  deaths 
to  cases  has  been  from  1:800  to  1:20;  typhus  fever,  including  "Brill's 
disease,"  in  which  it  has  varied  from  1 :5  to  practically  no  fatality;  and 
typhoid  fever,  in  which  the  ratio  has  varied  from  1:24  to  1:5. 

Re^stration  of  Deaths  in  the  United  States. — The  history  of  the 
registration  of  deaths  in  England  and  the  United  States  is  coupled  with 
that  of  marriages  and  births.  In  the  United  States  dependable  registra- 
tion was  first  enforced  in  Massachusetts  and  New  Jersey.  Other  States 
have  had  laws  of  various  types,  mostly  inadequate.  Only  recently  have 
any  number  of  States  secured  anything  like  complete  registration.  The 
bringing  about  of  accurate  death  registration  in  the  United  States  is  due 
largely  to  the  efforts  made  by  the  Bureau  of  the  Census,  and  especially 
to  the  untiring  efforts  of  Dr.  Cressy  L.  Wilbur,  formerly  chief  statisti- 
cian, Bureau  of  the  Census. 

TTnited  States  Registration  Area  for  Deaths. — The  registration  area 
for  deaths  established  by  the  United  States  Bureau  of  the  Census  in- 
cludes the  States,  and  cities  in  other  States  which  effectively  enforce 
satisfactory  registration  laws,  and,  in  the  opinion  of  the  Director  of  the 
Census,  have  at  least  90  per  cent,  of  all  deaths  registered.  This  area 
was  first  estabHshed  in  1880  and  at  that  time  included  Massachusetts, 
Few  Jersey,  and  certain  cities  in  other  States.  The  States  included 
March,  1921,  and  the  dates  when  admitted  to  the  area  were: 

DEATH  REGISTRATION  AREA — STATES 


State 

Year  Admitted 

California    

1906 

Colorado   

1906 

Connecticut   

1890 

Delaware 

1919 

Florida 

1919 

Illinois  

1918 

Indiana 

1900 

Kansas  

1914 

Kentucky   

1911 

Louisiana       

1918 

Maine 

1900 

Maryland 

1906 

Massachusetts   

1880 

M^ichiffan       

1900 

Minnesota    

1910 

1919 

1911 

Montana   

1910 

MORTALITY  STATISTICS 


1261 


Di:.\Tii  UKCis'iiiAiiON  AKKA — STATES — Continued 


State 

Year  Admitted 

Nebraska 

1920 

New  Hampshire  

1890 

New  Jersey   

1880 

New  York 

1890 

North  Carolina 

1916 

Ohio   

1909 

Oregon   

1918 

Pennsylvania   

1906 

Rhode  Island     

1890 

South  Carolina 

1916 

1917 

Utah 

1910 

Vermont  

1890 

Virginia    

1913 

1908 

Wisconsin 

1908 

1880 

Territory  of  Hawaii 

1917 

DEATH   REGISTRATION   AREA CITIES 

(in  non-regulation  areas) 


Galveston,  Texas. 
Houston,  Texas. 
Mobile,  Alabama. 
Montgomery,  Alabama. 
Oklahoma  City,  Oklahoma. 
San  Antonio,  Texas. 
Savannah,  Georgia. 
Wheeling,  W.  Va. 


Atlanta,  Georgia. 
Augusta,  Georgia. 
Beaumont,  Texas. 
Birmingham,  Alabama. 
Brunswick,  Georgia. 
Cleburne,  Texas. 
Dallas,  Texas. 
El  Paso,  Texas. 
Fargo,  North  Dakota. 

This  made  a  total  of  3-4  states,  the  District  of  Columbia  and  the 
Territory  of  Hawaii  and  17  cities  in  nonregistration  states  containing 
in  all  approximately  82  per  cent,  of  the  country's  population. 

Source  of  Data. — The  original  information  from  which  mortality  sta- 
tistics are  derived  is  obtained  by  the  registration  of  deaths.  This  is 
commonly  accomplished  by  the  use  of  a  blank  or  schedule  prepared  for 
the  purpose  and  in  this  country  known  as  a  death  certificate.  The 
model  law  for  the  registration  of  births  and  deaths  provides  that  no 
body  shall  be  interred  or  otherwise  disposed  of  or  removed  or  tempora- 
rily held  pending  further  disposition  "more  than  72  hours  after  death 
unless  a  permit  for  burial,  removal,  or  other  disposition  thereof  shall 
have  been  properly  issued  by  the  local  registrar  of  the  registration  dis- 
trict in  which  the  death  occurred  or  the  body  was  found.  And  no  such 
hurial  or  removal  permit  shall  be  issued  by  any  registrar  until,  wherever 
practicable,  a  complete  and  satisfactory  certificate  of  death  has  been 
filed  with  him.  .  ."  This  insures  the  making  of  a  death  certificate 
and  its  registration  in  each  instance  of  death  unless  the  body  is  sur- 


1262  VITAL  STATISTICS 

reptitiously  and  illegally  disposed  of.  It  therefore  guarantees  prac- 
tically complete  registration.  In  the  rural  districts  of  some  localities 
bodies  are  frequently  interred  in  private  burial  grounds  and  on  farms 
in  some  chosen  spot  on  the  premises.  Under  these  conditions  bodies 
would  occasionally  be  buried  without  registration,  due  to  ignorance  of 
the  law. 

The  Standard  Death.  Certificate. — The  standard  death  certificate  in 
use  throughout  the  registration  area  for  deaths  calls  for  the  following 
information : 

Place  of  death. 

Name,  sex,  color,  race,  conjugal  condition,  age,  date  of  birth,  occupa- 
tion, and  birthplace  of  decedent,  name  and  birthplace  of  father,  maiden 
name  and  birthplace  of  mother. 

Signature  and  address  of  informant  giving  preceding  inform'ation. 

Date  and  time  of  death  and  a  statement  as  to  the  duration  of  medical 
attendance  on  the  decedent,  the  cause  of  death,  and  its  duration,  and 
certain  other  data  are  to  be  given  by  the  physician,  if  any,  last  in  at- 
tendance. 

The  date  and  intended  place  of  burial  and  the  address  of  the  under- 
taker are  to  be  given  over  the  undertaker's  signature. 

The  date  when  the  certificate  is  filed  is  inserted  by  the  registrar  with 
his  signature. 

The  style  and  form  of  the  standard  certificate  of  death  used  in  the 
United  States  is  shown  on  page  1263. 

The  responsibility  of  seeing  that  a  certificate  is  properly  made  out 
and  filed  with  the  registrar  rests  primarily  upon  the  undertaker^  accord- 
ing to  the  provisions  of  the  model  law. 

Sources  of  Error. — In  the  use  of  mortality  statistics  as  well  as  other 
statistics  erroneous  and  unwarranted  conclusions  are  sometimes  arrived 
at  by  attempting  to  compare  incomparable  data.  Mortality  rates  se- 
cured by  lax  enforcement  or  faulty  methods  of  registration  cannot 
properly  be  compared  with  those  based  upon  complete  registration.  Nor 
can  the  rates  of  communities  with  populations  of  different  sex  and  age 
composition  be  compared  unless  proper  allowances  are  made  and  the 
rates  expressed  in  terms  of  the  same  population.  For  example,  it  is 
improper  to  compare  the  mortality  rate  of  an  aggregation  of  young 
men  picked  for  physical  soundness,  such  as  an  army  or  navy,  with 
the  crude  or  general  mortality  rate  of  a  civilian  population.  The  near- 
est means  of  making  comparison  would  be  to  compare  the  rate  of  the 
picked  body  of  men  with  the  rate  among  men  of  the  same  age  groups 
in  the  civil  population.  But  even  this  would  be  faulty,  for  the  one 
group  would  consist  of  men  specially  picked  for  physical  fitness  while 
the  other  group  would  include  the  fit  and  the  unfit,  the  strong  and 
the  weak.    ISTor  is  it  possible  to  compare  the  mortality  rate  of  any  special 


MORTALITY  STATISTICS 


1263 


population  group  with  the  rate  of  the  ])o])uhiti()ii  from  vvhicii  it  lias  been 
derived  by  intentional  or  other  process  of  selection  unless  the  dilferences 
in  population  composition  are  considered.  Thus,  it  would  give  little 
information  of  value  regarding  the  effect  of  locality  and  environment 
upon  the  duration  of  life  to  compare  the  mortality  rate  of  New  York 
City  or  the  registration  area  of  the  United  States  with  that  of  the 
Canal  Zone  during  the  construction  of  the  canal  without  taking  into  ac- 


"SI 


z   ■=>;  ■ 


a.  iO  > 


5|S3  EOK 


STANDARD  CERTIFICATE  OF  DEATH 


1  PWCE  OF  DEATH 

County _. 

Township 

City 

2  FULL  NAME 


(a)  Residence.    No 

(I'sual  ph*iN;«[fcbodf) 
length  of  retldgnf  ft  In  cirjf  Of  tcwT  wha 


State.. 

.  or    Viilage  . 


.  Registered  No 


(Udrolb  oocumd  In  3  liosplu)  or  iDstltullon,  gl%*»  lu  n 


St Ward 

(Ifnonrftsl. 
di.        Ho«  long  In  U.  S..  If  of  foriign  birth  T 


PERSONAL  KND  STAriSTICAL  PARTICUUtRS 


4  COLOR  OR  RACE    i  Sinoli.  Mirried.  widowcs. 
orDi*<ORCCD  (uv'utbo  word  J 


>tUSBflNDof 


ndowed,  or  divorud 


6  DATE  OF  BIRTH  (monlb,  <l«y.  ind  ytai) 


I  OCCUPATION  OF  OECDkSED 

(i)  Trtde,  profeiilon,  or 

pirttojlir  Itlnd  of  worli —  . 


10  NAME  OF  FATHER 


11  BIRTHPLACE  OF  FATHER  (cllf  or  toim). 
(Statp  or  country) 


llEOFf^OTHER 


MEDICAL  CERTIFICATE  OF  DEATH 


1 6  DATE  OF  DEATH  (moitlb,  diy,  nnd  j 


I  merebVCjC  RXIF"V,  Ttiat  I  attended  deceased  from 


that  I  fast  saw  h af 

and  that  death  occu-'ied 
The  CAUSE  OF  DEATH* 


1  the  date  stated  ebove,  at  — . 


.  (duration) yn,. 


CONTRIBUTORY. 


18/ 

Did  an  operation  precede  death?  ... 

Was  there  an  autopsy? — 

What  test  confirmed  diagnosis?  — 
(SIgnod) — 

.19      (Addrosi) 


.  (duration) yrs 


•  State  tbo  Disease  Cacstno  Death,  or  In  deallL'  from  V 


(t)S 


I  Na 


T  CAIT3E9.  rtftt* 


ide  lor  additional  space  } 


19  PLACE  OF  BURIAL.  CREMATION,  OR  REMOVAL 


20  UNDERTAKER 


DATE  OF  BURIAL 


count  any  differences  which  may  have  been  produced  in  the  age  and 
sex  composition  of  the  two  populations  by  the  selective  process  naturally 
operating  in  the  ca.se  of  the  Canal  Zone.  For  the  same  reason  there 
is  little  to  he  gained  by  comparing  the  mortality  rate  of  any  American 
city  or  State  with  that  of  the  civil  employees  of  the  Philippine  Islands 
or  any  other  similar  group  unless  based  upon  an  analysis  of  age  and 
sex  composition  of  the  populations. 

Another  possible  source  of  error  in  mortality  statistics  which  re- 
quires to  be  considered  is  the  original  data  contained  in  the  death 
certificates  from  which  the  statistics  are  compiled.  The  personal  and 
statistical  particulars  usually  furnished  by  some  member  of  the  family  are 
undoubtedly  in  most  instances  accurate  with  the  exception  of  the  state- 


1264  VITAL  STATISTICS 

ment  of  occupation  of  the  decedent,  which  offers  unusual  difficulties, 
due  to  the  indetiniteness  of  many  of  the  terms  commonly  used  in  so 
far  as  showing  the  exact  kind  of  work  is  concerned.  This  is  due  in 
some  measure  to  the  fact  that  the  nomenclature  in  common  use  has 
not  progressed  apace  with  the  rapid  development  of  new  industries  and 
industrial  processes  and  methods.  Whereas  50  years  ago  the  statement 
of  occupation  would  have  been  in  most  cases  comparatively  simple  and 
easily  understood,  today  with  changed  industrial  conditions  the  matter 
requires  greater  ■  precision  if  useful  statistical  information  is  to  result; 

Perhaps  the  most  common  error  entering  into  death  registration, 
and  therefore  into  mortality  statistics,  is  in  connection  with  the  state- 
ment of  cause  of  death.  Aside  from  the  fact  that  in  the  instances  in 
which  it  has  been  impossible  for  the  attending  physician  to  feel  rea- 
sonably certain  as  to  the  nature  of  the  terminal  illness  a  cause  of  death 
is  nevertheless  usually  stated  in  the  certificate,  and  also  the  fact  that 
at  times  the  physician  knowing  the  nature  of  the  illness  may,  in  the 
belief  that  he  is  shielding  the  family  from  odium  or  because  of  their 
whim,  intentionally  state  an  erroneous  cause  of  death,  there  still  remain 
the  many  unavoidable  errors  of  mistaken  diagnosis.  Just  how  great  a 
factor  this  last  may  be  it  is  difficult  to  estimate. 

However,  the  findings  of  Dr.  Eichard  C.  Cabot  ^  give  at  least  a 
hint  of  its  possible  importance  and  the  extent  to  which  it  may  affect 
that  part  of  mortality  statistics  relating  to  causes  of  death.  In  a  study 
of  3,000  autopsies  with  regard  to  the  relation  of  the  actual  cause  of 
death  as  found  post  mortem  to  the  clinical  diagnosis  Cabot  found  that 
the  percentage  of  correct  clinical  diagnoses  in  various  diseases  was  as 
follows : 

Percentage  of 
Correct  Diagnoses 

Diabetes  mellitus    95 

Typhoid  92 

Aortic  regurgitation 84 

Cancer  of  colon 74 

Lobar  pneumonia  74 

Chronic  glomerulonephritis    74 

Cerebral  tumor   72.8 

Tuberculous  meningitis 72 

Gastric  cancer 72 

Mitral  stenosis 69 

Brain  hemorrhage 67 

Septic  meningitis 64 

Aortic  stenosis .61 

Phthisis,  active 59 

Miliary  tuberculosis  52 

Chronic  interstitial  nephritis 50 

Thoracic  aneurism   50 

^  Cabot,  Eichard  C. :  "Diagnostic  Pitfalls  Identified  During  a  Study  of  3,000 
Autopsies,"  Journal  Americcm  Medical  Association^  Dec.  28^  1912,  p.  2295. 


MORTALITY  STATISTICS 


1265 


Percentage  of 
Correct  Diagnoses 

Hepatic  cirrhosis  ,'59 

Acute  endocarditis   39 

Peptic  ulcer   36 

Supi)urativc  nci)liritis    35 

luMial  tuberculosis   33.3 

Bronchopncunionia    33 

Vertebral   tuberculosis    23 

Chronic  myocarditis 22 

Hepatic  abscess  20 

Acute  pericarditis 20 

Acute  nephritis  16 

The  cases  studied  were  hospital  cases  under  conditions  assumed  to 
be  favorable  to  correct  diagnosis.  It  is  quite  safe  to  assume  that  in 
medical  practice  at  large  the  percentages  of  correct  diagnoses  would 
be  found  lower  than  those  found  by  Cabot. 

McLaughlin  and  Andrews  "^  carried  on  an  investigation  in  Manila 
into  the  nature  of  the  diseases  from  which  children  were  dying.  They 
made  post-mortem  examinations  of  children  in  w^hich  certain  diseases 
had  been  given  as  the  cause  of  death.  The  diseases  selected  were  those 
appearing  most  frequently  in  death  certificates.  The  reason  for  the 
investigation  was  to  ascertain  whether  the  death  certificates  show^ed  the 
real  causes  of  death  in  children  in  Manila  and  if  not  what  the  actual 
causes  of  death  were. 

A  summary  of  their  findings  was  as  follows : 


Assigned  causes  of  death 

Meningitis 37 

Enteritis  22 

Convulsions  40 

Beriberi 50 

Bronchitis   27 


Total 176 


Causes  of  death  ascertained  hy 
autopsy 

Cholera 40 

Beriberi 97 

Pneumonia 14 

Enterocolitis   7 

Meningitis   4 

Nephritis   2 

Empyema    2 

Acute     tonsillitis,     pharyngitis, 

and  bronchitis 1 

Cerebral  hemorrhage 1 

Undetermined 8 

Total 176 


In  the  registration  area  of  the  United  States  very  probably  the 
causes  given  in  death  certificates  of  children  correspond  more  nearly 
to  the  actual  causes  of  death  than  they  did  in  Manila.  This,  however, 
should  be  ascertained  by  careful  studies.     Mortality  statistics  cannot  be 


*  McLaughlin,  Allan  J.,  and  Andrews,  Vernon  L. :     "Studies  on  Infant  Mor- 
tality," Philippine  Journal  of  Science,  Vol.  V,  No.  2,  July,  1910,  p.  149. 


1266 


VITAL  STATISTICS 


more  accurate  than  the  death  certificates  from  which  they  are  compiled. 

For  a  further  discussion  of  the  possible  scope  of  the  inaccuracies 
entering  into  mortality  statistics  because  of  the  faulty  or  incorrect 
statement  of  cause  of  death  on  death  certificates  the  reader  is  referred 
to  the  Twelfth  Annual  Eeport  of  the  Bureau  of  the  Census  giving  mor- 
tality statistics  for  the  year  1911,  pages  36  to  38. 

Uses  of  Death.  Registration. — Death  registration  serves  a  number  of 
highly  important  purposes.    Its  functions  are  legal,  economic,  and  social. 


1875 

IS80 

1885 

1890 

1895 

1900 

1905 

1910 

28 

/ 

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t 

y 

N 

/ 

\ 

f 

s 

/ 

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/ 

\ 

\ 

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/r, 

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■' 

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k 

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fs 

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20 

\ 

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I 

>et 

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/7i 

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18 

\ 



/ 

1 

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S 

/ 

\ 

16 

— ^ 

V. 

^ 

/ 

\ 

•v 

^ 

S 

14- 

\Z 

10 

8 

6 

4 

Z 

_ 

Fig.   152. — Bikths  and  Deaths    (ExcL■asI^^:  of  Stillbirths] 

ULATiON  Per  Annum 
Registered  in  Massachusetts,  1871  to  1911. 


Per  1,000  Pop- 


Death  registration  is  useful  in  preventing  and  detecting  crime  through 
the  restrictions  placed  upon  the  disposal  of  dead  bodies.  It  serves  as 
evidence  in  the  inheritance  of  property  and  in  the  settlement  of  life 
insurance  contracts  and  policies.  It  is  only  proper  that  the  time,  place, 
and  cause  of  death  of  each  individual  should  be  made  a  permanent 
record  for  both  sentimental  and  legal  reasons. 

Death  registration  makes  it  possible  to  show  by  mathematical  com- 
putations and  statistical  methods  the  extent  and  rate  of  change  in 
population  produced  by  deaths;  the  average  duration  of  life;  and,  to 
the  extent  that  the  certified  causes  of  death  have  been  correctly  stated, 
the  relative  frequency  with  which  the  several  causes  produce  death. 
Death  statistics  by  comparison  with  birth  statistics  give  useful  infoi"- 
mation  regarding  population  increase  or  decrease. 


MORTALITY  STATISTICS  1267 

Death  Rates. — Drath  rati's  may  be  expressed  as  the  ratio  of  the  total 
number  of  deaths,  taken  as  a  unit,  to  the  population.  For  example: 
1  in  GO.  The  usual  method,  however,  is  to  express  these  rates  in  terms 
of  the  number  of  deaths  per  1,000  population,  or  in  some  instances  per 
10,000  or  even   100,000,  or  1,000,000. 

Crude  Death  Bates. — The  rate  which  shows  the  proportion  of  all 
deaths  to  the  total  ])upulation,  and  which  is  usually  obtained  by  dividing 
the  total  number  of  deaths  by  tlie  total  population  in  thousands,  is 
known  as  the  crude  death  rate;  also  as  the  general  or  central  death  rate. 
To  compute  the  crude  death  rate  the  total  number  of  deaths  during  a 
year  and  tlie  mean  population  for  the  year  (estimated  population  a3 
of  the  middle  of  the  year,  for  the  calendar  year  as  of  July  1)  are  taken. 
To  illustrate:  In  a  city  having  a  total  of  900  deaths  during  a  calendar 
year,  and  an  estimated  population  of  60,000  as  of  July  1  of  the  year, 

60,000  ^     ■ 

the  crude  death  rate  would  be  900   -h    — —    =   15  and  would  be 

expressed  as  15  per  1,000  population. 

Crude  death  rates  are  of  value  chiefly  to  show  the  numerical  loss 
of  the  population  by  death.  They  also  serve  as  a  satisfactory  basis  for 
the  comparison  of  the  death  rates  of  different  communities  having 
populations  of  similar  composition  as  to  age  and  sex.  For  populations 
of  dissimilar  composition  they  are  not  suitable  as  a  basis  of  comparison, 
for  the  death  rates  of  women  are  usually  lower  than  those  of  men  and 
the  death  rates  of  the  several  age  groups  vary  within  wide  limits,  and 
the  death  rate,  therefore,  depends  to  a  marked  degree  upon  the  relative 
numbers  of  males  and  females  and  the  proportion  of  the  population 
included  in  the  various  age  groups. 

Death  Rates  for  Short  Periods. — Death  rates  for  short  periods 
(for  a  week,  month,  or  quarter)  are  expressed  in  terms  of  annual  rates; 
that  is,  what  the  annual  rate  would  be  provided  deaths  occurred  through- 
out the  year  with  the  same  frequency  as  during  the  week  or  month  under 
consideration.  Death  rates  for  short  periods  are  likely  to  have  little 
significance,  as  quite  accidental  causes  may  affect  them  to  a  considerable 
degree.  Taken  for  a  number  of  years,  however,  they  give  useful  infor- 
mation regarding  seasonal  variations.  If  in  a  city  there  were  20  deaths 
during  a  given  week  and  the  mean  population  of  the  city  for  the  year 
was  60,000,  then  the  crude  death  rate  for  the  week  would  be 

^^^365/daysinyearV   /60^0\  ^  ^^j^^^^^  ^^  ^^^  -^  thousands)  =17.38. 
7   \days  m  week/      \  1,000  / 

The  mortality  for  the  week  would,  therefore,  be  at  the  rate  of  17.38 
per  1,000  population  per  annum. 


1268  VITAL  STATISTICS 

Specific  Death  Plates. — Special  or  specific  death  rates  are  the 
rates  of  specified  or  limited  subgroups  of  the  population.  These  sub- 
groups may  be  obtained  by  dividing  the  population  according  to  sex, 
age,  race,  social  condition,  occupation,  and  so  on.  Specific  death  rates 
may  be  stated  as  the  proportion  of  the  number  of  deaths  per  annum" 
in  the  subgroup  per  1,000  of  the  mean  annual  number  of  the  population 
in  that  subgroup.  Sometimes  specific  death  rates  are  given  in  terms 
of  10,000,  100,000,  or  1,000,000  of  the  subgroup  population. 

Among  the  most  important  of  the  specific  rates  are  those  relating 
to  age  groups.  Their  significance  is  shown  by  the  following  statement 
of  rates  for  the  registration  States  of  the  United  States  for  the  year 
1911: 

Age  Group  Death  Eate 

per  1,000, 

Under  1  year 112.9 

1  to  4  years   11.8 

5  to  9  years   '. 3.1 

10  tol4  years 2.2 

15  to  19  years   3.6 

20  to  24  years   5.2 

25to34years   6.4 

35to44years   8.9 

45  to  54  years   13.6 

55to64years   26.2 

65  to  74  years   55.2 

Y5  years  and  over    138.9 

Allages  13.9 

Specific  race  group  rates  are  also  important.  In  the  registration 
area  for  deaths  in  1911,  the  death  rate  for  the  white  population  was 
13.7  and  that  of  the  colored  23.7  per  1,000,  while  the  rate  of  the  two 
groups  taken  together  was  14.2  per  1,000.  In  1916  the  death  rates 
in  the  city  of  Washington  were  15  per  1,000  among  the  white  popu- 
lation and  25.4  per  1,000  among  the  colored;  in  Baltimore  15.9  for 
white  and  30.7  for  colored;  in  Xew  Orleans  14.3  for  white  and  30  for 
colored.  For  the  registration  area  as  a  whole  the  death  rates  in  1916 
were  for  the  white  population  13.5  per  1,000  and  for  the  colored  20.5 
per  1,000. 

In  considering  the  separation  of  deaths  into  those  of  white  and 
colored,  one  must  bear  in  mind  the  possibility  that  in  many  com- 
munities such  a  separation  may  amount  to  a  classification  accord- 
ing to  industrial  or  economic  status,  the  colored-  deaths  being  those 
in  households  having  the  smaller  incomes.  In  this  connection  one 
is  reminded  that  investigations  into  the  rate  of  infant  mortality  and 
the  relative  prevalence  of  certain  diseases,  such  as  tuberculosis,  have 
revealed  that  the  infant  mortality  rate  varied  usually  with  the  in- 
comes  of  the   population   groups   and   that   the   relative   prevalence   of 


MORTALITY  STATISTICS  1269 

tuberculosis  seemed  to  be  largely  determined  by  tbe  same  factor.  It 
may  be  that  if  in  the  average  community  deaths  could  be  classified 
'according  to  economic  status — that  is,  according  to  the  family  or  house- 
hold income,  a  difference  in  the  mortality  rates  would  be  obtained 
approximately  as  great  as  that  resulting  from  a  white  and  colored 
classification. 

That  a  classification  of  deaths  on  a  basis  other  than  that  of  color 
may  show  differences  in  mortality  rates  fully  as  great  as  those  pro- 
duced by  a  white  and  colored  classification  is  well  known. 

In  New  York  City  (the  old  city)  for  the  year  1906  the  death  rate 
among  that  part  of  the  population  of  Irish  nativity  was  29,26  per 
1,000,  and  among  the  population  of  Swedish  nativity  11.21  per  1,000, 
while  the  death  rate  of  native-born  Americans  was  18.49.  Classified 
according  to  the  nativity  of  the  parents  of  the  decedents,  the  death 
rate  among  persons  whose  parents  were  born  in  Italy  was  36.43  per 
1,000;  of  those  whose  parents  were  born  in  Austria-Hungary,  23.4 
per  1,000;  and  of  those  whose  parents  were  born  in  Sweden,  10.97 
per  1,000;  while  of  those  whose  parents  were  born  in  the  United 
States  the  rate  was  13.98  per  1,000,  The  death  rate  of  the  colored 
population  throughout  the  whole  city  (greater  Xew  York)  was  27.16. 
These  figures  indicate  that,  in  so  far  as  crude  death  rates  are  con- 
cerned, other  groups  of  the  population  may  have,  and  in  Xew  York 
City  did  have,  higher  rates  than  the  colored  population. 

The  death  rate  differs  also  in  the  two  sexes.  It  is  higher  for 
males  than  for  females. 

Standardized  Death  Rates. — Due  to  the  wide  variation  in  the  death 
rates  at  different  ages  it  is  impossible  satisfactorily  to  compare  the 
crude  death  rates  of  populations  differing  in  compositions  as  regards 
the  relative  number  of  individuals  in  the  several  age  groups.  The 
International  Statistical  Institute  recommended  (1895)  that  to  facili- 
tate the  comparison  of  death  rates  the  population  of  Sweden  as  it 
existed  in  1890  be  used  as  a  standard  population  for  the  statement  of 
rates.  Eates  expressed  in  terms  of  standard  population  are  known  as 
standardized  or  corrected  rates.  The  method  is  as  follows :  Take  the 
population  for  which  it  is  desired  to  state  the  standardized  death  rate 
and  ascertain  the  specific  death  rates  of  its  several  age  groups.  Xow 
take  the  corresponding  age  groups  in  1,000,000  of  the  standard  popula- 
tion and  compute  the  number  of  deaths  that  would  have  occurred  in 
each  age  group  at  the  specific  death  rate  found  to  exist  in  the  popula- 
tion for  which  the  standard  death  rate  is  being  computed;  add  the 
number  of  deaths  which  it  is  thus  found  would  have  occurred  in  the 
age  groups  of  the  standard  population.  This  gives  the  standardized 
rate  per  1,000,000.  The  standardized  rate  per  1,000  is  obtained  by 
moving  the  decimal  point  three  places  to  the  left. 


1270  VITAL  STATISTICS 

The  standardized  death  rate  is  the  rate  which  would  have  occurred 
in  the  standard  population  if  the  death  rates  in  its  several  age  groups 
had  been  the  same  as  those  of  the  corresponding  age  groups  of  the  • 
population  under  consideration. 

The  registrar  general  of  births,  marriages,  and  deaths  of  England 
and  Wales  has  for  some  years  taken  for  a  standard  the  population  com- 
position of  England  and  Wales  as  shown  by  the  1901  census.  The  popu- 
lation of  Sweden  of  1890  was  divided  without  distinction  of  sex  into 
the  five  age  groups:  Under  12  months  of  age,  over  12  months  and 
under  20  years,  20  to  39  years  of  age  inclusive,  40  to  59  years  of  age 
inclusive,  and  60  years  of  age  and  over.  The  population  of  England 
and  Wales  is  classified  separately  by  sexes  in  quinquennial  age  groups 
and  furnishes  a  much  more  delicate  and  exact  standard  for  measure- 
ment. The  use  of  the  Swedish  population  standardizes  for  ^age ;  the 
use  of  the  English  standardizes  for  both  age  and  sex. 

Factors  Affecting  Death  Rates. — Death  rates  are  affected  not  only  by 
the  statistical-  methods  used  in  their  preparation  and  by  the  age,  sex, 
and  race  composition  of  the  population,  the  social,  marital,  and  eco- 
nomic status  of  the  people,  the  nature  and  conditions  of  employment  and 
the  adaptability  of  a  people  to  their  environment,  but  also  in  limited 
areas  by  a  number  of  other  factors,  such  as  the  location  of  hospitals 
and  institutions. 

Nonresidents;  Hospitals  and  Institutions. — Frequently  a  hospital 
or  other  institution  will  be  located  in  one  community  while  its  pa- 
tients or  inmates  will  come  largely  from  other  places.  The  extent  to 
which  this  is  true  depends  upon  the  nature  or  reputation  of  the  hospital 
or  institution.  The  result  may  be  that  the  local  death  rate  will  be 
affected  to  an  appreciable  extent  by  deaths  of  nonresidents  in  such 
institutions.  In  England  and  Wales  an  attempt  has  been  made  during 
recent  years  to  overcome  this  difficulty  by  the  allocation  of  all  deaths 
in  so  far  as  possible  to  the  locality  of  usual  residence.  In  compiling 
deaths  for  a  registration  district  or  area  for  the  purpose  of  showing 
death  rates,  erroneous  results  will  be  obtained  if  the  deaths  of  non- 
residents are  excluded  and  no  additions  made  for  the  deaths  of  resi- 
dents which  are  continually  occurring  and  being  registered  elsewhere. 

In  the  absence  of  a  dependable  means  of  including  the  deaths  of 
residents  occurring  in  other  districts  it  is,  unless  under  most  excep- 
tional circumstances,  unsafe  to  exclude  the  deaths  of  nonresidents. 

For  the  public  health  purposes  of  mortality  statistics  nonresident 
deaths  might  be  considered  as  those  of  persons  who  had  been  already 
affected  with  their  fatal  illnesses  at  the  time  they  had  come  to  the  local- 
ity and  who  had  not  developed  or  contracted  the  illnesses  in  the  locality. 

Migration. — Migration  affects  death  rates  by  changing  the  age, 
sex,  or  race  composition  of  the  population.     Migrants  are  likely  to  con- 


MORTALITY  STATISTICS 


1271 


sist  more  largely  of  males  than  of  females,  of  young  adults  than  of 
the  extremes  of  life.  The  effect  of  migration  depends  upon  whether 
the  balance  is  one  of  emigration  or  immigration  and  the  nature  of  the 
migrants  lost  or  gained. 

Birlh  Rate. — Ignoring  the  question  of  migration,  a  population  in- 
creases because  of  the  excess  of  births  over  deaths,  natural  increase.  In  a 
stationary  population  the  birth  rate  equals  the  death  rate.  As  all  born 
must  eventually  die  the  birth  rate  depends  for  its  excess  over  the  death 
rate  upon  the  ever-increasing  number  of  child-producing  elements  in  the 
population  and  the  resulting  greater  numbers  in  the  younger  age  groups. 
Other  things  being  equal,  a  community  with  a  high  birth  rate  will,  because 
of  the  greater  proportion  of  the  population  in  the  younger  age  groups, 
have  a  lower  crude  death  rate  than  a  community  with  a  low  birth  rate. 

Marital  Condition. — Mortality  in  certain  countries  seems  to  be 
more  dependent  on  marital  conditions  than  on  sex.  This  is  shown-  by 
the  following  table  taken  from  a  paper  entitled  "Some  Eesearches  Con- 
cerning the  Factors  of  Mortalit}^/'  by  Lucien  March  {Journal  of  the 
Royal  Statistical  Society,  London,  March,  1912)  : 

Shotcing  for  the  period  1886-1895,   the  numhei'  of   deaths  per  10,000   persons 
according  to  their  marital  status  in  France,  Prussia,  and  Siced^n 


il 

ales,   aged — 

Females,   aged — 

20-39 

40-59 

6t)  and 
Over 

20-39 

40-59 

60   and 
Over 

France: 
Married. 

77 
103 
211 

71 

84 
201 

53 

83 
104 

153 

24(3 
293 

175 
231 
346 

114 
204 
190 

583 
794 

1,148 

582 

806 

1,091 

453 
690 
856 

80 

78 

145 

79 

59 

101 

66 
61 
98 

121 

166 
198 

128 
179 
172 

96 
120 
132 

456 

Single    .  . 
Widowed 
Prussia: 
Married 
Sinsrle    .  . 

or  divorced 

730 
930 

497 
729 

Widowed 
Sweden : 
Married 

or  divorced 

805 
364 

Single    .  . 
Widowed 

or  divorced 

528 
698 

It  will  be  noted  in  the  following  table  that  there  has  been  a  marked 
fall  in  the  crude  death  rates  throughout  the  civilized  world.'  A  study 
of  the  deaths  by  age  groups  indicates  that  in  the  United  States  the 
reduction  in  death  rates  has  been  entirely  in  the  younger  age  groups 
and  that  the  rates  for  ages  above  45  or  50  years  have  not  only  not 
diminished  but  have  actually  increased.  This  means  that  a  greater 
proportion  of  the  population  than  formerly  is  living  to  be  50  years  of 
age.  The  increased  death  rates  among  that  part  of  the  population  over 
50  probably  means  that  those  saved  from  earlier  death  and  carried  along 


1272 


VITAL  STATISTICS 


Death  rates   {exclusive  of  stillbirths)   per  1,000  population  in  certain  countries, 
1886,  1913,  19U  and  1915* 


Country  or  State 

1886 

1913 

1914 

1915 

Australian  Commonwealth  

15.4 
29.7 
18.1 
19.5 
22.2 
22.5 
26.2 
31.7 
17.8 
28.7 
21.8 
10.5 
16.2 
26.7 
18.9 
29.6 
29.3 
16.6 

tl9.8 

16.2 

18.6 

8.9 

10.8 

t  20.5 

12.5 

13.8 

16.1 

17.7 

115.0 

t  23.3 

17.1 

$18.7 

12.3 

9.5 

13.2 

25.9 

15.5 

$21.1 

22.1 

13.6 

14.1 
15.0 
15.0 
13.9 

10.5 

i2!6 
14.0 
15.6 
19.6 

ie.h 

17.9 
12.4 
9.3 
13.5 
23.8 
15.5 

22!  i 

13.8 

13.6 
15.1 
14.7 
13.4 

10.7 

Austria   

Denmark    

England  and  Wales   

12.8 
15.7 

Finland 

German  Empire 

Hungary   

Ireland   

17.6 

Italy    

The  Netherlands 

i2!4 

New  Zealand  

Norway   

Roumania 

9.1  - 
13.3 

Scotland    

17.1 

Spain    

United     States      (registration     area     for 

deaths )    

Connecticut 

,  i4.6 

13.5    . 
14.9 

Michigan 

14.5 
13.4 

*  Taken  from  the  Annual  Reports  of  the  Registrar  General  of  Births,  Deaths  and 
Marriages  in  England  and  Wales,  1913,  1914  and  1915,  except  the  rates  for  Connecti- 
cut,   Massachusetts,    Michigan    and    the   United   States. 

tYear  1880. 

t  Year  1912. 

to  the  age  of  50  succumb  rather  rapidly  to  the  vicissitudes  of  life.  It 
would  seem  that  this  is  to  be  expected. 

The  International  List  of  Causes  of  Death. — Many  persons,  even 
among  registrars  and  statisticians,  seem  to  misunderstand  the  nature 
of  the  International  List  of  Causes  of  Death.  It  seems  to  be  frequently 
thought  of  as  being  a  nomenclature  of  diseases.  It  is  important  that 
just  what  it  is  shall  be  thoroughly  understood. 

In  the  course  of  the  registration  of  deaths  in  a  population  of  any 
size,  the  names  given  to  the  causes  of  death  as  written  on  the  death 
certificates  will  aggregate  in  the  total  many  thousands,  depending  upon 
the  education  and  training  of  the  physicians  signing  the  death  certifi- 
cates. Several  different  terms  will  be  used  by  different  physicians  for 
the  same  disease  or,  the  same  name  may  be  used  for  several  different 
morbid  conditions.  For  instance,  typhoid  fever  will  be  variously  termed 
abdominal  fever,  cerebral  typhoid,  continued  fever,  enteric  fever,  gastro- 
enteric fever,  typho-enteritis.  Malarial  fever  will  be  variously  recorded 
as  bilious  intermittent  fever,  chills  and  fever,  dumb  ague,  fever  and 
ague,  gastric  remittent  fever,  intermittent  fever,  marsh  anemia  and 
sometimes  as  malaria.  On  the  other  hand  "continued  fever,"  "rheuma- 
tism," "pneumonia,"  "cancer"  and  "heart  disease"  are  each   used   as 


MORTALITY  STATISTICS  1273 

the  name  of  many  different  pathologic  conditions  and  it  is  impossible 
to  know  what  is  meant  by  these  terms  unless  the  user  gives  his  defi- 
nition of  their  meaning  as  used  by  him. 

And  so  it  is  with  all  the  otiici'  diseases  and  conditions  causing  death. 
It  will  be  readily  understood  that  it  is  impossible  tor  the  statistician  te 
give  the  occurrence  of  death  for  each  of  the  multitudinous  causes 
which  are  thus  found  recorded  in  death  certificates.  Statistically,  it 
would  be  an  impossible  task  and  from  the  standpoint  of  printing  and 
publication  and  the  futility  when  published,  meaningless  and  of  no 
value.  It  is  therefore  necessary  for  the  statistician  to  take  the  death 
certificates  and  divide  them  into  a  practicable  number  of  groups,  under 
which*  they  can  be  compiled,  and  for  which  tables  can  be  published. 
Every  statistical  office  has  done  this.  The  only  alternative  would 
have  been  to  give  practically  a  serial  statement  of  deaths  and  their 
assigned  causes.  But  where  each  statistical  office  determined  for 
itself  the  groups  of  causes  of  death  which  it  would  associate  together 
in  one  table,  or,  in  other  words,  the  groupings  under  which  it  would 
publish  its  causes  of  death,  no  two  statistical  groupings  were  the  same, 
and  therefore,  no  two  sets  of  tables  were  comparable.  If  the  French 
statistical  office  made  one  grouping  and  published  their  tables  accord- 
ing to  their  grouping  and  the  English  statistical  office  made  another 
grouping  and  published  their  tables  according  to  that  grouping,  com- 
parative deductions  as  relating  to  the  mortality  data  of  the  French  and 
English  peoples  would  be  impossible. 

To  overcome  this  difficulty  and  make  mortality  statistics  of  all  coun- 
tries comparable,  it  was  determined  about  1893  to  decide  upon  a  sta- 
tistical grouping  of  causes  of  death  for  purposes  of  tabulation  and  pub- 
lication which  would  be  used  by  the  several  countries  publishing  mor- 
tality data.  As  a  result  of  this  we  have  the  International  List  of  Causes 
of  Death.  Previous  to  the  revision  in  1920,  the  International  List  con- 
tained 189  titles  or  groupings  under  which  all  returns  of  death  may  be 
tabulated.^  Each  title  may  figuratively  be  considered  as  a  basket  and 
the  189  titles  as  the  189  baskets  into  one  of  which  the  statistician 
drops  each  death  certificate  coming  to  his  office.  From  the  assortment 
of  death  certificates  thus  made  statistical  tables  are  published.  About 
half  of  the  189  numbers  or  titles  of  the  list  include  but  one  disease; 
the  others  include  groups  of  diseases  or  death-producing  causes. 

It  will  thus  be  seen  that  the  International  List  is  by  no  means  a 
nomenclature,  nor  is  it  even  a  classification,  unless  it  be  considered  a 
classification  for  purposes  of  statistical  publication. 

Each  people  speaking  a  different  language  has  had  to  determine  for 

'At  the  time  of  writing  (February,  1921)  the  numbers  of  titles  in  the  revised 
list  had  not  been  decided  upon  by  the  conference  for  revision  which  had  met  in 
Paris  in  the  autumn  of  1920. 


1274 


VITAL  STATISTICS 


itself  which  names  given  on  death  certificates  as  causes  of  death  in 
their  respective  languages  should  be  included  under  each  of  the  189 
titles  in  the  International  List.  The  only  part  of  the  International 
List  which  can  be  international  is  the  189  numbers  and  the  titles  in 
so  far  as  the  titles  are  descriptive.  To  make  a  list  entirely  possible  of 
international  use,  each  title  should  have  a  number  and  a  definition  of 
the  disease  or  of  the  class  of  diseases  to  be  included  under  that  number. 
For  instance,  Title  15,  "Plague"  would  be  truly  capable  of  international 
use  only  when  the  definition  of  what  is  meant  by  "Plague"  is  given. 

To  illustrate  the  use  of  this  list  and  how  each  country  has  had  to 
determine  which  terms  given  on  death  certificates,  as  causes  of  death  in 
their  respective  countries,  should  be  considered  as  falling  under  the 
several  titles  of  the  International  List,  the  list  given  below  is  taken  from 
the  Manual  issued  by  the  Bureau  of  the  Census.  The  names  for  causes 
of  death  which,  when  given  on  death  certificates,  are  to  be  compiled  as 
coming  under  Title  1  of  the  International  List,  which  Title  jSTo.  1  is 
assumed  to  include  only  the  morbid  condition  due  to  infection  with 
bacillus  typhosus,  are  shown.  It  is  readily  understood  that  many  of 
these  terms  are  not  used  at  times  for  typhoid  fever,  and  their  inclusion 
under  that  title  causes  a  percentage  of  error.  However,  there  seems  to 
be  no  way  to  avoid  this.  It  will  be  readily  understood  also  that  these 
secondary  lists  of  terms  under  each  title  could  by  no  means  be  inter- 
national except  among  peoples  speaking  the  same  language  and  follow- 
ing much  the  same  usage  as  to  terms. 

The  following  terms  are  included  by  the  Bureau  of  the  Census  under 
Title  1  of  the  International  List  when  given  as  causes  of  death  on 
death  certificates. 


Title  1.  Typhoid  fever. 
Abdominal  fever. 
Abdominal  typhoid. 
Abdominal  typhus. 
Abortive  typhoid. 
Ambulant  typhoid. 
Cerebral  typhoid. 
Cerebral  typhus. 
Continued  fever. 
Enteric  fever. 
Enterica. 

Gastro-enteric  fever. 
Hemorrhagic  typhoid  fever. 
Ileotyphus. 

Intermittent   typhoid  fever. 
Malignant  typhoid  fever. 
Mountain  fever. 


Paratyphoid  fever. 
Para  typhus. 
Posttyphoid  abscess. 
Rheumatic  typhoid  fever. 
Typhobilious  fever. 
Typho-enteritis. 
Typhogastric  fever. 
Typhoid  fever. 
Typhoid  malaria. 
Typhoid  meningitis. 
Typhoid  stupor. 
Typhoid  ulcer. 
Typhomalaria. 
Typhomalarial  fever. 
Typhoperitonitis. 
Typhus   (unqualified). 
Typhus  abdominalis. 


INFANT  MORTALITY 


isrs 


INFANT  MORTALITY 


Infant  mortality  is  tlie  mortality  of  infants  under  1  year  of  age. 
While  the  specific  death  rates  for  other  age  groups  are  given  as  the  ratio 
of  the  number  of  deaths  to  the  number  of  individuals  in  the  age  group 
as  ascertained  by  census  enumeration  and  estimated  for  intercensal  and 
postcensal  years,  it  is  not  practicable  to  do  this  for  the  first  year  of  life. 
There  is  extreme  difficulty  in  ascertaining  by  enumeration  the  infant 
population.  This  is  due  largely  to  confusion  of  the  current  year  of  age 
with  the  completed  year  of  life.  Then  too,  a  census  of  infants  under 
one  year  of  age  would  be  of  value  only  for  the  yeac  in  which  it  was 
taken. 

Infant  mortality — Deaths  of  children  under  1  year  of  age  per  1,000  births   (ex- 
clusive of  stillbirths)   in  certain  countries,  1892,  1911  and  1915  * 


Country  or  State 

1892 

1911 

1915 

Australian  Commonwealth    

Austria    

106 
259 

140 
148 
170 
181 

274 
105 
184 
174 
89 
105 
243 
117 
196 
109 

68 
207 
106 
130 
114 

till 

192 

207 

94 

tl42 

137 

56 

167 

197 

tl08 

t  138 
t"5 

68 

Denmark    

England  and  Wales 

Finland    

France    

German  Empire  

Hungary    

95 

110 

Ireland    

Italy   

The  Netherlands 

92 

87 

Xew  Zealand       

50 

Norway    

Roumania    

Scotland    

126 

Servia   

Sweden    

*  Taken   from  the  Annual   Reports  of  the  Registrar  General  of  Births,   Deaths  and 
Marriages  in   England   and  Wales,   1911   and   1915. 
tYear  1910. 

The  commonly  accepted  method  of  stating  infant  mortality  is  as  the 
ratio  of  deaths  of  children  under  1  year  of  age  to  living  births,  and  is 
usually  expressed  as  the  proportion  of  deaths  during  the  calendar  year 
to  1,000  living  births  during  the  same  period.  To  illustrate :  If  in  a 
city  there  were  during  a  year  224  deaths  of  infants  under  1  year  of  age, 
and  if  during  the  same  year  there  were  2,000  births,  the  infant  mortality 
rate  would  be  112  per  1,000  births  per  annum. 

Infant  mortality  rates  might  be  based  upon  the  number  of  births 
during  the  preceding  year  or  upon  the  mean  of  the  number  of  births  of 
the  current  year  and  the  preceding  year.  However,  the  number  of  births 
of  the  current  year  has  been  accepted  as  the  basis  in  Great  Britain  and 
many  other  countries. 


1276 


VITAL  STATISTICS 


Making  the  estimation  of  infant  mortality  depend  upon  birth  regis- 
tration is  at  present  unfortunate  in  a  way  for  those  interested  in  the  sub- 
ject as  it  relates  to  the  United  States,  owing  to  deficient  birth  registra- 
tion in  this  country  and  the  impossibility  therefore  of  estimating  infant 
mortality  rates,  except  for  certain  limited  areas.  However,  there  is  no 
other  practicable  basis  for  estimation.  There  are,  too,  other  difficulties 
to  be  encountered  in  the  use  of  incomplete  birth  registration.  In  the 
absence  of  change  in  other  factors  an  improving  completeness  of  birth 
registration  would  give  an  apparent  decreasing  infant  mortality  rate  and 
might  lead  to  unwarranted  deductions.     See  also  page  -177. 


LIFE  TABLES 

In  theory  life  tables  represent  the  duration  of  life  of  individuals  born 
at  the  same  time.  Given  a  group  of  individuals  born  in  any  one  year 
and  a  life  table  will  show  the  number  in  the  group  that  will  still  be  alive 
in  each  succeeding  year  as  long  as  any  remain.  It  will  also  show  the 
number  who  will  have  died  previous  to  any  given  year  and  the  number 


AGE  IN  VEABS. 


Fig.  153. — State  Statistics  of  Original  Registration. 
Chart  showing  the  number  of  white  males  and  white  females  in  both  the 
rural  and  urban  populations,  and  of  colored  (negro)  males  and  colored  females 
in  the' total  population,  remaining  alive  at  each  age  out  of  100.000  born  alive  in 
the  "original  registration  States." — Based  upon  the  "United  States  life  tables: 
1910,"  published  by  the  Bureau  of  the  Census.  Taken  from  Public  Health 
Reports,  April  6,  1917. 

dying  during  each  year.  To  observe  a  group  of  individuals  from  the 
cradle  to  the  grave  is  under  most  conditions  impracticable,  and  besides 
yields  information  the  value  of  which  is  largely  lost  before  it  is  obtained, 
for  conditions  affecting  longevity  may  change  and  the  life  history  of 
one  generation  may  be  quite  different  from  that  of  the  next. 

Much  of  the  value  of  a  life  table. consists  in  showing  current  condi- 


LIFE  TABLES 


1277 


tions  Ls  they  alfcct  the  longevity  of  tlie  ((•minunity  or  race.  For  thi.s 
purpose  tables  are  constructed  from  the  information  furnished  by  an 
enumeration  of  the  population  (census)  classified  by  age  and  sex  and 
the  registration  of  deaths  with  the  decedents  classified  also  by  age  and 
sex.  The  population  age  and  sex  groups  give  the  number  and  propor- 
tion remaining  alive  at  each  year  of  age,  the  deaths  show  the  number 
dying  at  each  year  of  age.  For  the  purpose  of  getting  data  which  show 
general  conditions  prevailing  during  the  period,  and  of  avoiding  the 
errors  which  might  arise  by  using  the  death  records  of  a  year  during 
which  usual  mortality  conditions  prevailed,  the  death  records  for  a 
number  of  consecutive  years  are  usually  used. 

Given  the  above  data,  the  expectancy  of  life  or  mean  after  lifetime 
at  a  given  age  is  readily  obtained.  The  following  table  is  one  pre- 
pared under  the  direction  of  Dr.  William  H.  Guilfoy,  registrar  of  rec- 
ords of  the  Xew  York  City  department  of  health,  and  published  in 
the  monthly  bulletin  of  the  department  for  May,  1913.  It  compares 
the  expectation  of  life  based  on  the  mortality  experience  of  the  three 
years  1909,  1910,  and  1911,  with  that  found  by  the  late  John  S.  Billings 
based  upon  the  experience  of  1879,  1889,  and  1881 : 


Approximate  life  tables  for  the  citrj  of  New  York  based  on  mortalitij  returns  for 
the  triennials  1879  to  1881  and  1900  to  1911.      (Guilfov.) 


Expectation  of  life,  1879 

Expectation  of  life,  1909 

Gain  (  +  )  or  loss  (  — )  in 

Years  of 

to  1881 

to  1911 

•    years  of  expectancy 

Males 

Females 

Persons 

Males 

Females 

Persons 

Males 

Females 

Persons 

Ages  : 

—    0  . .  . 

39.7 

42.8 

41.3 

50.1 

53.8 

51.9 

+10.4 

+11.0 

+10.6 

5..  . 

44.9 

47.7 

46.3 

49.4 

52.9 

51.1 

+  4.5 

+   5.2 

+   4.8 

10..  . 

42.4 

45.3 

43.8 

45.2 

48.7 

46.9 

+   2.8 

+   3.4 

+   3.1 

15..  . 

38.2 

41.2 

39.7 

40.8 

44.2 

42.5 

+   2.6 

+   3.0 

+   2.8 

20..  . 

34.4 

37.3 

35.8 

36.6 

40.0 

38.3 

A-   2.2 

+   2.7 

+   2.5 

25... 

31.2 

34.0 

32.6 

32.7 

36.0 

34.3 

+   1.5 

+   2.0 

+   1-7 

30..  . 

28.2 

31.0 

29.6 

28.9 

32.1 

30.5 

+   0.7 

-1-   1.1 

+   0.9 

35..  . 

25.3 

28.1 

26.7 

25.4 

28.4 

26.9 

^    0.1 

+    0.3 

+   0.2 

40... 

22.5 

25.2 

23.9 

22.1 

24.7 

23.4 

—   0.4 

—   0.5 

—   0.5 

45..  . 

19.8 

22.4 

21.1 

18.9 

21.1 

20.0 

—    0.9 

-    1.1 

-   1.1 

50..  . 

17.2 

19.4 

18.3 

15.9 

17.7 

16.8 

-   1.3 

-    1.7 

-  1.5 

55..  . 

14.5 

16.4 

15.4 

13.2 

14.6 

13.9 

-   1.3 

—    1.8 

-   1.5 

60..  . 

12.2 

13.8 

13.0 

10.8 

11.8 

11.3 

—    1.4 

-    2.0 

-    1.7 

65..  . 

9.9 

11.2 

10.5 

8.8 

9.4 

9.1 

—   1.1 

-   1.8 

-    1.4 

70.  .  . 

8.5 

9.3 

8.9 

6.9 

7.5 

7.2 

—   1.6 

—   1.8' 

-   1.7 

75..  . 

7.1 

7.5 

7.3 

5.3 

5.7 

5.5 

—   1.8 

-   1.8 

-   1.8 

80..  . 

6.2 

6.5 

6.4 

4.1 

4.5 

4.3 

—   2.1 

—   2.0 

-    2.1 

+85... 

5.4 

5.5 

5.5 

2.0 

2.4 

2.2 

-    3.4 

-    3.1 

-    3.3 

r  -1-24.8 

+  28.7 

-^26.6 

Balance. 

■{    -15.3 

L  +    9.5 

-17.6 
+  11.1 

-16.6 
-10.0 

The  Bureau  of  the  Census  issued  in  June,  1916,  life  tables  prepared 
under  the  supervision  of  Professor  James  W.  Glover.  The  tables  relate 
chiefly  to  mortality  conditions  in  the  area  known  as  the  original  regis- 
tration states  comprising  Maine,  ^Xew  Hampshire,  Vermont,  Massachu- 


1278  VITAL  STATISTICS 

setts,  Ehode  Island,  Connecticut,  New  York,  New  Jersey,  Indiana,  Mich- 
igan, and  the  District  of  Columbia.  The  chart  on  page  1376  is  based  on 
the  material  in  these  tables. 

REFERENCES 

1885.— Farr,  William  :    "Vital  Statistics." 

1899.— Newsholme,  Arthur,  M.D.,  F.K.C.P.:     "The  Elements  of  Vital 

Statistics." 
1906. — Bailey,  William  B.,  Assistant  Professor  of  Political  Economy,  Yale 

University :    "Modern  Social  Conditions — A  Statistical  Study  of  Birth, 

Death,  Marriage,  Divorce,  Disease,   Suicide,  Immigration,  etc.,  with 

Special  Reference  to  the  United  States." 
1907. — BowLEY,  Arthur  L.,  M.A.,  F.S.S.,  Lecturer  in   Statistics  at  the 

London  School  of  Economics   and  Political   Science:      "Elements   of 

Statistics." 
1912. — Yule,  G.  Udny:     "An  Introduction  to  the  Theory  of  Statistics." 
1915. — King,  Willford  L,  M.A.,  Instructor  in  Statistics  in  the  University 

of  Wisconsin :     "The  Elements  of  Statistical  Method." 
Annual   Reports    and    Supplements    of    the   Registrar-General    of    Births, 

Deaths,  and  Marriages  in  England  and  Wales. 
Annual  Reports  on  Mortality  Statistics  of  the  Registration  Area  for  Deaths 

of  the  United  States  by  the  Bureau  of  the  Census. 
1911. — Bureau  municipal  de  Statistique  d' Amsterdam  :     "Statistique  Demo- 

graphique  des  Grandes  Villes  du  Monde,  1880-1909." 
1907. — Statistique  generale  de  la  France:     "Statistique  Internationale  du 

Mouvement  de  la  Population  d'apres  les  registres  d'etat  civil-Resume 

retrospectif  depuis  I'origine  des  Statistiques  de  I'etat  civil,  jusqu'en 

1905." 
1919.— Whipple,  George  C.  :     "Vital  Statistics."    John  Wiley  and  Sons. 


f^ECTIOX  XT  I 
INDUSTRIAL  HYCIENE  AND  DISEASES  OF  OCCUPATION 

Industrial  hygiene  is  one  ol"  the  most  important  topics  in  preventive 
medicine,  as  it  deals  with  the  health,  the  welfare,  and  the  human  rights 
of  the  vast  majority  of  the  population.  Industrial  hygiene  is  a  sub- 
ject in  which  the  medical,  economic,  and  sociologic  aspects  are  closely 
interwoven,  and  it  requires  a  broad  grasp  and  intimate  knowledge  of  the 
conditions  to  avoid  the  dangers  and  correct  the  injustices  to  which  work- 
people are  subjected.  The  questions  of  industrial  hygiene  strike  at  the 
very  root  of  our  social  system ;  they  include  the  relation  of  capital  and 
labor,  and  the  relation  of  man  to  his  fellow  men.  The  man  of  means 
may,  to  a  large  extent,  select  not  only  the  place,  but  even  the  character, 
of  his  employment.  He  can  choose  his  own  hours  of  work  and  can 
largely  control  his  environment  while  at  work,  so  far  as  it  affects  his 
health  and  comfort;  he  can  purchase  fresh  air,  sunshine,  good  food, 
rest,  recreation,  and  other  conditions  that  make  for  health,  longevity, 
and  happiness.  The  employee  must  largely  accept  the  conditions  as  he 
finds  them  and  is  frequently  denied  many  advantages,  even  necessities. 
As  the  power  of  the  employee  is  limited,  he  needs  the  assistance  of  the 
state  to  correct  the  unreasonable  demands  which  capital  has  ever  exacted 
of  labor.  Legislators  should  champion  the  rights  of  work-people,  espe- 
cially in  the  realm  of  industrial  hygiene.  Our  country  has  been  negligent 
in  this  regard  and  has  fallen  far  behind  England  and  Continental  coun- 
tries. The  situation  has  received  some  assistance  through  organized 
labor,  which  has  exerted  a  good  influence  in  limiting  the  avarice  of  the 
employer,  in  shortening  the  hours  of  work,  in  obtaining  a  more  just 
share  of  the  profits,  in  improving  sanitary  conditions,  and  in  exacting 
a  modicum  of  human  consideration.  Thus  when  the  stone  masons  came 
to  build  the  Hygienic  Laboratory  in  Washington  they  refused  to  work 
until  a  proper  shelter  and  other  reasonable  conveniences  were  provided, 
as  required  by  their  labor  union. 

Modern  conditions  have  brought  entirely  new  problems  into  indus- 
trial hygiene.  These  have  come  about  largely  through  the  development 
of  new  industries  and  the  invention  of  new  processes,  through  improved 
and  changed  methods  of  transportation,  and  through  specialization  and 
crowding  in  cities  and  work  places,  through  artificial  light,  through 
changing  relations  between  capital  and  labor,  and  the  intensive  and  un- 

1279 


1280    INDUSTRIAL  HYGIENE— DISEASES  OF  OCCUPATION 

relenting  pressure  of  the  times.  Some  of  the  conditions  which  oppress 
the  workmen  are  brought  about  by  the  greed  of  capital  and  disregard 
of  the  human  machine,  but  indifference,  carelessness,  and  ignorance  of 
the  workman  himself  are  responsible  for  many  avoidable  accidents  and 
preventable  maladies.  In  Eastman's  study  of  work  accidents  in  Pitts- 
burgh it  appeared  that,  out  of  410  fatal  accidents,  the  victim  or  his 
fellow  workers  were  responsible  in  188  cases  and  the  employer  in  147 
cases.  Despite  the  improvements  in  labor-saving  devices  the  human 
machine  will  ever  remain  the  most  vital  and  indispensable  machine  in 
the  production  of  wealth — at  the  same  time  it  is  the  most  delicate  and 
sensitive  machine.  Both  from  the  standpoint  of  humanity  and  the  stand- 
point of  economy  the  human  machine  deserves  greater  care  and  consid- 
eration than  any  other  mechanism  engaged  in  production. 

The  diseases  of  occupation  are  especial  dangers  to  health  incident  to 
certain  industries,  such  as  liability  to  lead  poisoning  in  the  manufac- 
ture of  white  lead ;  of  phossy  jaw  in  the  manufacture  of  matches  made 
with  white  phosphorus;  of  caisson  disease  in  divers  and  those  who  work 
in  compressed  air ;  special  affections  are  sometimes  caused  by  exposure 
to  high  temperatures;  there  are  extra  hazards  to  life  and  limb  in  rail- 
roading, mining,  and  among  those  who  work  with  explosives;  there  is 
a  particular  danger  to  those  who  are  compelled  to  work  in  a  dusty  at- 
mosphere, more  so  if  the  dust  is  of  an  irritating  or  poisonous  nature; 
and  there  is  danger  to  those  who  are  compelled  to  breathe  poisonous 
fumes  such  as  carbon  monoxid,  hydrogen  sulphid  or  mercury.  Most. in- 
dustrial poisons  are  due  to  gases,  vapors  and  dust.  Further,  there  are 
many  forms  of  neuroses  due  to  certain  kinds  of  work;  and  finally  infec- 
tions such  as  anthrax,  glanders,  and  hookworm  disease.  These  special 
instances  represent  the  true  diseases  of  occupation. 

Indtbstrial  hygiene,  on  the  other  hand,  includes  many  influences,  not 
specifically  inherent  in  industry,  to  which  the  workman  is  often  sub- 
jected which  seriously  influence  health ;  such  as  poor  ventilation,  lack  of 
cleanliness,  overcrowding,  excessive  hours,  improper  light,  fatigue,  and 
a  hundred  and  one  conditions  which  affect  the  health  and  the  efficiency 
of  the  workman.  The  prevention  of  the  communicable  infections  among 
work  people  is  based  upon  the  same  principles  and  practice  as  for  the 
civilian  population.  Work  should  be  ennobling,  and  anything  which 
tends  to  degrade  it  is  morally  wrong. 

The  statistics  of  morbidity  and  mortality  in  relation  to  diseases  of 
occupation  need  careful  scrutiny,  especially  when  used  for  comparison. 
The  factors  which  enter  into  such  statistics  are  so  numerous  and  the  con- 
ditions so  variable  that  misleading  conclusions  are  common.  The  work- 
men come  and  go,  they  vary  very  much  in  physical  vigor  to  start  with, 
are  of  all  ages,  both  sexes,  many  nationalities,  and  are  greatly  influenced 
by  home  conditions  and  by  the  character  of  their  recreation.     Some 


INDUSTRIAL  llYniENE— DISEASES  OF  OrCTPATIOX   1281 

indiustries.  wiiilf  not  in  tliemselves  ))ai-ti(ul;irly  hazardous,  are  rendered 
so  tlirou^di  intemperance  or  dissipation.  On  tlie  other  hand,  there  is  a 
relation  hetwcen  low  wa^jes  and  a  iiigh  niorhidity  rate  in  a  given  indus- 
try. Low  wages  mean  poor  housing,  insufficient  clothing,  poor  food, 
unhealthful  recreation,  increased  temptation  to  alcoholism,  and  an  undue 
proportion  of  youtiiful  w'orkers,  of  women,  and  of  men  more  or  less 
handicapped  by  poor  physique  or  bad  habits.  The  statistician  therefore 
must   be  careful  to  take  all    Factors  into  account   that   bear   upon   tiie 


Fig.  154. — Syste^i  of  Hoods  and  Vextila'tors  to  Carry  off  the  Fumes  from 
THE  FiRNACES  IX  A  FouxDRY.      ( Masrt.  State  Board  of  Health.  1 


subject.  Some  industries  are  blamed  for  conditions  affecting  health 
that  may  be  due  to  the  insanitary  home  conditions  and  bad  habits  of 
the  individual. 

In  recording  the  nature  of  a  man's  work  it  is  not  sufficient  simply  to 
state  that  he  is  a  laborer,  mechanic,  machinist,  mill  operator,  and  the 
like.  Such  information  is  frequently  of  no  more  value  to  the  student 
of  the  diseases  of  occupation  than  the  name  of  the  person  himself.  A 
"machinist"  may  set  hair  springs  in  watches  or  repair  automobiles.  If 
the  person  is  a  blacksmith  or  works  with  heavy  metals  it  is  plain  that 
he  works  under  a  severe  ph3'sical  strain.  If  he  is  a  sailor  upon  a  sailing 
ship  we  know  that  he  is  exposed  to  rough  weather  and  unusually  severe 
conditions,  whereas  if  he  is  a  sailor  upon  a  modern  passenger  steamship 


1282    INDUSTEIAL  HYGIENE— DISEASES  OF  OCCUPATION 

the  conditions  of  his  work  may  be  no  more  severe  than  those  of  the 
janitors  and  charmen  in  a  large  office  building.  If  he  is  in  finance  we 
may  be  sure  that  he  is  subject  to  severe  nervous  strain.  It  is  therefore 
not  sufficient  simply  to  give  the  name  of  the  trade,  but  detailed  inquiry 
should  be  made  into  the  precise  nature  of  the  individnaPs  work  and  the 
particular  conditions  under  which  he  works.^ 

Most  of  the  investigation  of  industrial  poisons  in  the  United  States 
has  been  made  within  very  recent  years,  and  the  field  has  not  yet  been 
nearly  covered.  Careful  studies  have  been  made  of  two  poisons,  white 
phosphorus  2  and  manganese,-'^  most  of  the  more  important  lead  indus- 
tries have  been  studied,*  and  there  are  some  excellent  surveys  of  the 
brass  industry^  and  of  the  various  occupations  in  which  mercury®  or 
its  compounds  are  used.^  There  is  urgent  need  for  more  study  of  sev- 
eral poisons  which  are  quite  extensively  employed  in  our  industries, 
such  as  carbon  monoxid ;  white  arsenic  and  arseniuretted  hydrogen  gas ; 
vanadium;  selenium;  carbon  disulphid;  sulphurated  hydrogen;  benzene; 
toluene,  and  their  many  derivatives,  of  which  anilin  is  the  most  im- 
portant; methyl  alcohol;  amyl  acetate;  carbon  tetrachlorid ;  acetylene 
tetrachlorid,  or  tetrachlorethane ;  aldehyds,  acetones  and  cyanogen. 

Conditions  in  American  industry  vary  much  more  widely  in  dif- 
ferent plants  than  tbey  do  in  the  older  countries,  and  while  our  best 
factories  are  equal  to  the  best  in  Europe,  or  occasionally  are  even  bet- 
ter, the  worst  fall  below  the  standard  required  by  law  in  Europe.  There 
is  on  the  whole,  in  America,  more  recklessness  in  the  handling  of  trade 
poisons  and  the  result  is  shown  in  all  the  statistics  of  industrial  poison- 
ing that  have  been  collected.  Thus,  in  the  making  of  storage  bat- 
teries, a  dangerous  lead  trade,  the  rate  of  poisoning  in  the  five  largest 

*The  Massachusetts  legislature  of  1904  took  the  first  step  in  this  country 
to  obtain  definite  scientific  data  on  the  subject  of  the  occupational  diseases. 
The  State  Board  of  Health  of  Massachusetts  made  an  investigation  into  the 
sanitary  condition  of  factories,  workshops,  and  mercantile  establishments,  and 
published  its  first  report  on  the  subject  in  1907.  Since  then  several  States 
have  taken  up  the  subject,  also  the  U.  S.  Dept.  of  Labor  and  the  Amer.  Assn. 
for  Labor  Legislation.  The  Hospital  for  Industrial  Diseases  at  Milan,  opened 
March,  1910,  is  the  only  institution  in  the  world  devoted  specifically  to  the 
investigation  and  care  of  such  diseases.  The  first  American  Congress  on  Indus- 
trial Diseases  met  in  June,  1910. 

The  earliest  successful  attempts  in  England  to  enforce  sanitation  and  to 
secure  healthy  conditions  of  work  were  introduced  by  the  Act  of  1833  involving 
the  appointment  of  paid  factory  inspectors,  who  antedated  medical  officers  of 
health  and  sanitary  inspectors. 

^  Andrews,  J.  M. :  Bull  86,  U.  S.  Bureau  of  Labor. 

^Edsall,  D.  L.,  and  Drinker,  C.  K. :  Journ.  of  Indus.  Hygiene,  1,  120,  1919, 
p.  183. 

*Bull.  95,  U.  S.  Bureau  of  Labor,  and  Bulls.  104,  1^1,  165,  209,  U.  S.  Bureau 
of  Labor  Statistics. 

^Hayhurst,  E.  R.:     Am.  Journ.  Med.  8c.,  1913,  Vol.  145,  N.  S.,  p.  723. 

"Mercury  Poisoning  in  the  Industries  of  New  York  City  and  Vicinity.  Nat. 
Civic  Federation  Women's  Welfare  Dept.,  1913. 

^Harris,  L.  I.:  Dept.  of  Health,  City  of  New  York,  Mono.  Series  No.  12, 
1915. 


SOME  FUNDAMENTAL  CONSIDERATIONS  1283 

factories  in  the  United  States  in  1914  was  17.!)  per  cent.,  while  Great 
Britain's  rate  for  1912  was  2  per  cent.,  and  the  largest  factory  in  Ger- 
many had  only  0.97  per  cent. 

Andrews  estimates  that  in  the  United  States  ;5(),(i()()  wage  earners 
are  killed  hy  industrial  accidents  every  year,  and  that  at  least  500,000 
more  are  seriously  injured.  A  memorial  on  industrial  injuries  prepared 
by  a  committee  of  inspectors,  a])pointed  hy  the  President  of  the  Asso- 
ciation for  Labor  Legislation,  states  that  there  are  probably  not  less  than 
13,000.000  cases  of  sickness  each  year  among  those  engaged  in  industrial 
employments.  The  money  lost  each  year  (for  those  who  find  dollars 
more  expressive  than  lives)  is  conservatively  calculated  at  nearly  three- 
fourths  of  a  billion  dollars.  At  least  one-fourth  of  this  painful  incapac- 
ity for  work  and  consequent  economic  loss  can  be  prevented. 

Good  industrial  conditions  mean  money  in  the  pockets  of  the  em- 
ployer. Thus.  Elliot  Washburn  reports  the  instance  of  twenty-eight 
emery  grinders  in  Massachusetts  working  in  a  badly  lighted  and  poorly 
ventilated  basement,  who  increased  their  efficiency  30  per  cent,  on  being 
transferred  to  a  well  lighted  and  ventilated  workroom. 

The  reporting  of  occupational  diseases  is  a  public  health  measure, 
and  of  first  importance  for  their  control. 

An  industry  may  be  a  nuisance  or  disturbance  to  the  community  as 
well  as  to  those  engaged  in  its  various  processes.  Thus,  the  noise  of  a 
tack  factory  or  boiler  shop,  the  smells  from  glue  or  fertilizing  factories, 
or  the  fumes  from  smelting  or  chemical  ^vorks,  or  the  smoke  from  chim- 
neys or  locomotives,  wastes  from  tanneries,  paper  mills,  and  mines  do 
not  come  directly  in  the  chapter  of  industrial  hygiene,  however  closely 
related. 


SOME  FUNDAMENTAL  CONSIDERATIONS  IN  PREVENTION 

In  order  to  improve  the  hygienic  conditions  under  Avhich  people 
work,  and  in  order  to  prevent  the  diseases  of  occupation,  five  funda- 
mental conditions  are  essential:  (1)  investigators;  (2)  laws;  (3)  fac- 
tory inspection;  (4)  penalties;  (5)  education.  It  is  self-evident  that 
before  anything  can  be  accomplished  a  careful  study  must  be  made  of 
the  facts.  These  investigations  must  include  not  only  scientific  studies, 
but  also  economic  and  sociological  factors.  Every  large  industrial  center 
should  have  a  clinic  for  the  study  and  care  of  industrial  diseases.  The 
subject  should  be  included  in  the  curriculum  of  medical  schools.  Suit- 
able laws  are  necessary,  for  it  has  been  found  in  practice  that  the  condi- 
tions cannot  be  corrected  by  an  appeal  to  voluntary  reform.  To  be  effec- 
tive the  laws  must  provide  ample  ways  and  means  for  their  energetic  en- 
forcement.   A  systematic  factory  inspection  is  necessary  in  order  not  only 


1284    INDUSTRIAL  HYGIENE— DISEASES  OF  OCCUPATION 

to  protect  work  people  against  the  preventable  diseases  of  occupation  and 
to  correct  sanitary  defects,  but  also  to  enforce  the  laws  concerning  hours 
of  occupation,  child  labor  laws,  and  related  subjects.  These. laws  have 
little  force  unless  they  provide  a  penalty  against  both  the  employer  and 
the  employees.  Either  party  to  the  contract  should  be  held  legally  re- 
sponsible in  case  of  violation.  Finally,  education  directed  to  the  em- 
ployer, the  employee,  and  also  to  the  public  at  large  is  necessary  to  ob- 
tain the  laws  and  maintain  the  standards. 

Hours  of  Work.! — No  general  rule  can  be  laid  down  for  the  hours  of 
work,  which  2uay  vary  with  the  character  of  the  employment.  Thus 
the  hours  of  active  work  are  limited  by  a  smith  or  glass-blower,  a  worker 
in  a  caisson  or  mine,  a  locomotive  engineer,  and  other  occupations  neces- 
sitating great  muscular  effort  or  intensive  concentration,  or  exposure  to 
unnatural  conditions.  Formerly  men  worked  at  the  quieter  occupa- 
tions all  the  time  not  given  to  sleep ;  now  the  day  is  better  divided  into 
eight  hours  of  work,  eight  hours  of  ''re-creation,"  and  eight  hours  of 
sleep.  Hygienically,  it  is  important  to  have  one  full  day's  rest  each  week. 
It  cannot  be  maintained  from  the  medical  side  that  working  longer  than 
eight  hours  a  day  is  harmful  to  health,  but  it  is  held  that  no  employer 
has  the  right  to  utilize  the  greater  part  of  a  man's  day  and  thus  deprive 
him  of  the  leisure  to  which  he,  as  a  human  being,  is  entitled.  Since  his 
whole  nature  has  to  be  developed,  time  must  be  given  for  the  intellectual, 
moral,  and  physical  welfare  of  man,  which  cannot  take  place  if  the 
hours  of  employment  are  too  long,  the  work  too  hard,  or  of  a  grinding 
nature.  The  hours  of  work  depend  somewhat  upon  the  physical  exertion 
required  and  also  upon  the  nervous  tension.  The  Saturday  half  holi- 
days, especially  during  the  heated  term;  a  vacation  period,  and  a  tend- 
ency to  increase  the  number  of  holidays  are  all  signs  of  social  improve- 
ment which  make  for  health  and  happiness. 

Fatig-ue. — Economic  engineers  find  that  it  pays  to  give  employees  a 
rest  at  stated  intervals  and  to  guard  the  conditions  surrounding  workers, 
so  that  they  are  neither  molested  nor  interrupted,  that  the  light  and 
other  factors  are  agreeable,  and  the  sanitary  surroundings  good.  Work 
and  rest  must  be  judiciously  alternated.  Efficiency  ceases  when  fatigue 
begins.  The  danger  to  the  workman  himself,  as  well  as  to  others,  is  now 
recognized  from  a  tired  brain,  tired  nerves,  and  tired  muscles.  Acci- 
dents are  especially  prone  to  happen  to  workmen  who  are  tired.  Thus 
most  accidents  in  factories  happen  as  the  day  wears  on.  The  effect  of 
fatigue  on  the  occurrence  of  accidents  is  graphically  shown  by  French 
and  Belgian  statistics.  The  number  of  accidents  increases  progressively 
during  the  morning  hours,  drops  after  the  noon  intermission,  and  then 
rises  from  hour  to  hour  until  the  end  of  the  working  day,  affording 
a  practical  illustration  of  Helmholtz's  experiment  in  attention  fatigue. 
Fatigue  is  not  only  dangerous  to  the  workman  himself,  but  sometimes 


SOME  FUNDAMENTAL  COXSIDERATIOXS  1285 

to  others;  tlius  tlie  ovcruroui^lit  aii<l  tired-out  Iniiii  (lisi)al(lu'r  may 
send  trains  into  collision,  rurther,  fatigue  of  certain  nerves  and 
muscles  may  result  in  definite  symptoms  such  as  writers'  cramp,  or 
more  general  manifestations  such  as  neurasthenia  or  nervous  prostration. 
Typewriters,  telegraph  operators,  and  others  suffer  from  these  occupa- 
tional neuroses. 

S))aeth  *  draws  attention  to  the  dilTerence  between  normal  fatigue 
which  is  harmless  and  cumulative  fatigue  which  is  dangerous  and  may 
be  associated  with  serious  nervous  disorders — industrial  psychoneuroses. 
The  one  merges  into  the  other,  and  therefore  the  reduction  of  normal 
fatigue  is  the  first  logical  step  in  a  prophylactic  attack. 

Fatigue  is  also  believed  to  predispose  to  certain  infections,  such  as 
cerebrospinal  fever  and  perhaps  pneumonia  and  other  respiratory  dis- 
eases. The  experience  of  the  World  War  clearly  showed  that  all  attempts 
to  make  a  soldier  too  rapidly,  through  fatiguing  drills,  invite  disaster. 

Next  to  fatigue,  nervous  tension  and  worry  are  very  wearing,  and 
when  combined  become  especially  harmful.  Diabetes  prevails  among 
engine  drivers  to  a  considerable  extent.  Worry,  hurry,  and  a  high 
nervous  tension  are  recognized  as  a  frequently  predisposing  cause  of  ill 
health  or  breakdown  in  all  walks  of  life,  including  the  so-called  higher 
professions. 

The  "Monday  Effect." — It  has  long  been  known  that  workers  are 
less  eflBcient  on  Monday  and  following  holidays  than  on  other  days  of 
the  week.  Efficiency  experts  know  that  the  smallest  output  of  the  week 
occurs  on  Monday. 

The  nsual  explanation  of  this  has  been  misuse  of  the  week-end  lei- 
sure and  of  the  week's  wages — as  excessive  eating,  excessive  drinking, 
late  nights  and  insuflBcient  sleep,  or  dissipation  of  other  kinds.  But 
it  is  now  apparent  that  these  are  not  the  real  reasons  for  inefficiency 
following  a  rest.  A.  F.  Stanley  Kent  ^  has  shown  that  the  week-end 
rest  affects  both  fatigue-production  and  recovery  from  fatigue  on  the 
one  hand,  and  output  on  the  other.  There  is  not  only  a  feeling  of  lassi- 
tude and  a  disinclination  to  work,  but  also  an  actual  diminished  effi- 
ciency. In  other  words,  upon  return  to  work  after  a  rest,  the  workman 
is  out  of  practice,  has  forgotten,  and  finds  a  certain  amount  of  loss  of 
coordination  rather  than  actual  fatigue.  He  must  relearn  before  the 
accustomed  efficiency  can  be  regained.  This  same  phenomenon  is  ob- 
served in  the  familiar  behavior  of  a  muscle  which  after  a  rest  shows  a 
progressive  improvement  as  a  result  of  activit}' — the  contractions  in- 
creasing in  a  '^stair-case"  effect.  Workers  in  nitroglycerin,  naphtha 
and  ether  always  feel  the  effects  of  these  substances  more  on  Monday 
or  following  a  holiday;  in  fact,  workers  in  nitroglycerin  carry  some  of 

^Journ.  Industrial  Hygiene,  I,  Xo.  9,  Jan.,  1920. 
^Journ.  of  Physiology,   1915-16,  LV. 


1586    INDUSTEIAL  HYGIET^E— DISEASES  OF  OCCTTPATION 

this  substance  in  their  hat  band  if  they  go  on  a  week's  vacation  in  order 
to  avoid  the  nitroglycerin  headache  upon  reexposure. 

Minors. — The  first  factory  act  in  this  country  was  passed  by  the 
State  of  New  York  in  1886.  By  this  act  no  child  under  13  years  of 
age  was  allowed  to  work  in  factories.  Since  then,  the  minimum  has 
been  raised  to  14  in  forty-five  states,  and  in  seven  of  these  the  limit  is 
higher  than  14  years. 

A  national  minimum  age  of  14  years  for  industrial  employment  has 
in  effect  been  established  by  the  passage  in  1918  of  a  measure  providing 
for  a  tax  ^°  of  ten  per  cent,  on  the  entire  net  profits  for  the  taxable 
year,  of  any  mill,  tannery,  factory,  or  manufacturing  establishment  in 
which  children  under  14  have  been  employed  or  permitted  to  work. 
The  same  act  prohibits  the  employment  of  children  under  16  in  any 
mine  or  quarr}^,  a  provision  previously  established  by  statute  in  nineteen 
states,  while  Texas  places  it  at  17  years,  and  Arizona  and  Wisconsin 
at  18  years. 

The  injustice  to  the  child  and  the  .consequence  upon  its  health  and 
development  of  subjecting  it  to  the  monotony  and  grind  of  factory  life 
are  too  evident  to  need  emphasis.  Eecently  it  has  been  claimed  that 
in  certain  districts,  as,  for  example,  the  mill  district  of  our  southland, 
the  children  are  better  off  in  a  good  textile  mill  of  modern  construc- 
tion than  they  are  living  under  the  insanitary  conditions  of  their  homes. 
It  would  be  just  as  logical  to  state  that  they  would  improve  in  health 
if  removed  to  a  sanitary  prison  or  almshouse.  The  child  of  today  is 
the  citizen  of  tomorrow  and  his  health  and  development  are  the  most 
important  assets  of  the  state. 

In  Massachusetts  minors  under  18  years  of  age  are  excluded  from 
the  following  occupations : 

1.  Processes  involving  exposure  to  poisonous  dusts  or  substances, 
such  as  the  manufacture  of  lead,  lead  pipe,  plumbers'  supplies;  electro- 
typing,  handling  white  lead  or  lead  monoxid  (litharge)  in  rubber  fac- 
tories; lead-paint  grinding;  lead  working  in  the  manufacture  of  storage 
batteries ;  file  cutting  by  hand ;  typesetting ;  cleaning  or  handling  of  type 
in  printing  offices;  glazing  in  pottery  establishments. 

2.  Processes  involving  exposure  to  irritating  dusts,  as  graphite  in 
the  manufacture  of  stove  polish;  bronzing  in  lithographing  business; 
cutlery  grinding  and  other  grinding;  polishing  on  emery  or  buffing 
wheels ;  cutting,  grinding  and  preparing  pearl  shell ;  talc  dusting  in  rub- 
ber works ;  sorting,  cutting  or  grinding  rags ;  filing  grooves  in  steel  rolls 
by  hand. 

3.  Processes  involving  exposure  to  poisonous  gases  and  fumes,  as 
exposure  to  naphtha  in  the  manufacture  of  rubber  goods, , in  japanned 

^"The  constitutionality  of  this  tax  (Title  XII  of  Eevenue  Act  of  1918)  has 
not  yet  been  passed  upon  by  the  Supreme  Court. 


SOME  FUNDAMENTAL  CONSIDERATIONS  1287 

or  patent  IcatluT;  exposure  to  funics  or  gases  from  lead  processes;  and 
the  spraying  of  amyl  acetate  on  pictures. 

4.  Processes  involving  exposure  to  irritating  gases  and  fumes,  such 
as  gassing  in  textile  factories;  singeing  in  print  works;  bleaching  and 
dyeing  works,  and  dipping  metal  in  acid  solutions. 

5.  Processes  involving  exposure  to  extremes  of  heat  and  other  condi- 
tions whicli  promote  susceptibility  to  disease,  as  melting  or  annealing  glass. 

In  respect  to  age  limit,  the  American  laws  compare  very  favorably 
with  those  of  European  countries,  but  in  other  respects  they  lag  be- 
hind. Thus,  while  Great  Britain,  Denmark,  P>a]ice,  Norway,  Sweden 
and  Switzerland  have  established  18  as  the  minimum  age  for  night 
work,  only  three  American  states  place  it  so  high,  and  the  Federal  taxa- 
tion law  fixes  it  at  1(5  years.  The  Children's  Bureau  Conference,  called 
in  1919  to  set  standards  for  employment  of  children  in  industry,  ad- 
vised the  prohiliition  of  nigbt  work  under  21  years,  Ijecause  of  the  phys- 
ical and  moral  dangers  which  night  work  for  the  young  entails.  Ameri- 
can laws  also  fail  to  protect  children  adequately  against  the  unhealth- 
ful  processes  in  industry.  Pennsylvania  alone  debars  young  persons 
under  21  years  from  certain  lead  processes,  while  a  limit  of  18  years  is 
prescribed  in  Maryland,  Massachusetts,  New  Jersey,  Ohio  and  Wisconsin. 
This  means  that  in  42  states  boys  and  girls  of  14  years  may  be  em- 
ployed in  work  exposing  them  to  lead,  mercury,  arsenic,  benzene,  carbon 
disulphid,  carbon  monoxid,  etc.  All  of  the  European  countries  recog- 
nize the  dangerous  nature  of  such  work  for  immature  persons  of  both 
sexes,  and  have  placed  it  under  legislative  control. 

Women. — The  protection  of  women  in  American  industries  also  falls 
below  the  standard  of  other  great  industrial  countries.  Women  are 
physiologically  not  capable  of  doing  the  same  work  as  men,  especially 
during  the  period  of  maternity.  Further,  several  days  each  month 
women  are  more  or  less  incapacitated  for  most  kinds  of  work  on  ac- 
count of  menstruation.  Pregnant  women  should  not  work  for  several 
weeks  before  labor,  and  after  labor  not  until  the  uterus  has  undergone 
involution,  which  is  a  matter  of  another  month.  It  is  in  regard  to  the 
prohibition  of  work  immediately  before  and  immediately  after  child- 
birth, the  prohibition  of  night  work,  and  of  employment  in  poisonous 
processes,  that  the  laws  of  many  of  our  states  are  inadequate.  Con- 
necticut, Massachusetts,  New  York  and  Vermont  have  passed  legisla- 
tion to  cover  the  first  point.  Only  nine  states  prohibit  the  night  work 
of  women,  although  so  long  ago  as  1906  all  the  countries  of  Europe  ex- 
cept Norway,  Denmark,  Roumania  and  Servia  signed  the  "Berne  In- 
ternational Convention''  prohibiting  it.  Only  Pennsylvania  and  New 
Jersey  exclude  women  from  the  dangerous  lead  trades,  and  New  York 
and  Ohio  have  a  curious  law  prohibiting  women  from  working  with 
emery  and  polishing  powders. 


1288    INDUSTRIAL  HYGIENE— DISEASES  OF  OCCUPATION 

Mr.  Brandeis  successfully  defended  the  constitutionality  of  the  ten- 
hour  law  for  women  in  Oregon.  The  brief  submitted  by  this  eminent 
jurist  in  a  similar  action  before  the  Illinois  Supreme  Court  "  should  be 
read  by  those  interested  in  this  subject.  The  primary  object  of  this 
brief  is  to  show  that  the  demands  of  public  health  require  legal  restric- 
tions in  the  work  of  women  because  of  the  peculiar  importance  to  the 
community  of  the  health  of  mothers.  The  effect  of  overwork  on  the 
different  organs  is  reviewed,  also  the  effect  of  night  work,  of  prolonged 
standing  on  the  feet,  of  foot-power  machinery,  and  of  the  speeding  up 
required  by  the  "piece-work  system."  The  general  literature  upon 
fatigue  and  overAvork  is  reviewed.    . 

The  effect  of  6verAvork  upon  fecundity  and  upon  infant  mortality  is 
impressive.  Broggi  states  that  of  172,365  Italian  women  between  the 
ages  of  fifteen  and  fifty-four  years  who  were  employed  in  industrial  oc- 
cupations the  average  child-bearing  coefficient  was  only  about  one-third 
of  the  general  fertility  of  Italian  women. 

It  is  now  a  well-established  fact  thg,t  infant  mortality  is  shockingly 
high  among  the  babies  of  women  who  work  in  factories  and  mills.  It 
has  been  shown  in  Germany  and  England  that  infant  mortality  increases 
progressively  according  to  the  increase  in  the  proportion  of  women 
obliged  to  work  outside  of  their  homes,  and  this  is  true  even  if  the 
mother's  work  results  in  higher  standards  of  comfort  in  the  home.  The 
two  classical  demonstrations  of  this' rule  are  the  great  Lancashire  cotton 
famine  and  the  Siege  of  Paris,  during  both  of  which  crises  there  were 
loss  of  employment  and  great  privation.  In  spite  of  the  starvation  and 
the  increased  general  death  rate,  the  infants'  death  rate  fell  in  Paris 
actually  to  40  per  cent,  simply  because  the  women,  being  out  of  work, 
were  obliged  themselves  to  nurse  and  care  for  their  children.  The  infant 
mortality  in  industrial  centers  such  as  Fall  River,  Lowell,  and  Lawrence, 
in  Massachusetts,  which  are  mill  towns,  is  twice  as  high  as  similar  towns 
without  many  factories  and  better  economic  standards. 

It  is  plainly  the  duty  of  the  nation  not  only  to  restrict  the  hours 
of  work  of  women,  but  also  to  prohibit  their  employment  in  certain 
industries  known  to  be  particularly  hazardous  to  them.  The  evidence 
presented  by  the  British,  especially  by  Oliver,^^  qj^  industrial  lead  pois- 
oning shows  clearly  the  greater  susceptibility  of  women  to  this  poison,  the 
severity  of  the  form  it  takes  in  women,  and  the  disastrous  effect  of 
maternal  plumbism  on  the  offspring  (see  page  1296).  Although  we  have 
no  statistics  to  prove  it,  there  is  every  reason  to  believe  that  the  same 
thing  is  true  of  other  poisons  used  in  industry.  Protection  should  also  be 
given  to  women  against  less  striking  evils  in  industry. 

"  Brandeis,  Louis  D.,  assisted  by  Goldmark,  Josephine :  Brief  and  Argument 
for  Appellants.  In  the  Supreme  Court  of  the  State  of  Illinois,  December  term, 
1909. 

"Dangerous  Trades.     London,  1902,  p.  296. 


SOME  FUNDAMEXTAL  rOXSIDEKATIOXS  1289 

Saleswon^eu  should  be  provided  with  seats  in  shops  so  as  to  avoid 
tlie  ill  effects  of  prolonged  standing,  they  should  have  one  or  two  days 
each  month  for  rest  during  the  menstrual  period,  and  should  he  pro- 
tected against  undue  strain  aiul  fatigue.  While  women's  work  may  be 
regulated  in  the  industries  and  the  hours  of  employment  may  be  lim- 
ited hy  law,  there  can  be  no  law  to  regulate  women's  work  in  the  house- 
hold which  is  "never  done."  ilen  have  still  to  learn  the  lesson  that 
nervous  breakdown  and  the  results  of  fatigue  are  as  harmful  in  women 
who  overwork  in  the  home  as  in  those  who  work  in  shops  and  factories. 
The  long  hours  and  confining  work  of  house  servants  sometimes  lead 
to  anemia  and  other  troubles.  Cooks  are  exposed  to  the  effects  of  exces- 
sive heat  and  to  sudden  changes  of  temperature.  Domestic  "servants" 
as  a  class  supply  a  large  contingent  of  patients  in  hospitals  and  out- 
clinics.  The  long  hours  and  insufficient  sleeping  accommodations,  as 
well  as  the  nature  of  the  work,  lead  to  ill  health  which  may  in  part  ac- 
count for  the  disinclination  of  women  to  accept  this  kind  of  service. 

Factory  Inspection. — There  is  no  longer  doubt  but  that  factory  in- 
spection is  necessary  as  a  protection  to  the  workman.  An  efficient  sys- 
tem requires  a  good  comprehensive  basic  law  and  a  capable  corps  of  in- 
spectors. The  inspectors  should  be  thoroughly  familiar  with  the  law  and 
with  the  processes  of  manufacture  and  also  with  the  problems  of  pre- 
ventive medicine.  Factory  inspectors  should  be  capable  of  making 
recommendations  outside  of  the  strict  regulations  under  which  they  op- 
erate so  as  to  improve  conditions  and  meet  the  needs  of  an  ever-changing 
situation.  Factory  inspection  really  falls  into  two  categories,  one  of 
■which  deals  mainly  with  the  medical  side  and  the  other  with  the  legal 
and  economic  side.  Both  inspectors  should  take  into  account  the  social 
and  humanitarian  side.  Some  of  the  factors  which  should  engage  the 
attention  of  a  factory  inspector  are :  ventilation,  dust,  gases,  vapors, 
odors,  temperature,  moisture,  light,  cleanliness,  over-crowding,  excessive 
heat,  dampness,  drinking-water,  children,  women,  washing  facilities,  wa- 
terclosets,  cloakrooms,  receptacles  for  expectoration,  defective  sanitary 
arrangements,  hours  of  work  and  rest,  the  age  of  the  employees,  their 
physical  condition,  etc.  Hanson  points  out  that  medical  men,  through 
their  training  and  attitude,  make  the  best  factory  inspectors,  for  they 
alone  are  in  a  position  to  make  the  best  use  of  facts,  and  learn  something 
of  the  sanitary  conditions  of  premises  where  men  and  women  work,  to 
study  the  possible  injurious  effects  of  certain  processes,  to  inspect  devices 
designed  to  protect  the  employees  against  injury  or  against  dangerous 
fumes  and  dust,  and  to  judge  the  effects  on  the  health  of  operatives  of 
such  substances,  as  well  as  to  detect  the  sjinptoms  of  certain  poisons  inci- 
dent to  such  occupations,  to  detect  and  protect  the  employees  and  others 
from  infectious  diseases,  to  make  physical  examinations  of  minors,  and 
to  collect  and  make  proper  use  of  all  facts  and  data,  including  morbidity 


1290    INDUSTRIAL  HYGIENE-DISEASES  OE  OCCUPATION 

and  mortality  statistics,  pertaining  to  occupational  hygiene.  The  medi- 
cal inspector  is  also  able  to  correlate  the  injurious  influences  in  the 
factory,  in  the  home,  and  in  the  habits  of  the  individual. 

Preventable  Accidents. — The  most  obvious  and  striking  of  the  pre- 
ventable accidents  occur  on  railroads,  in  mines,  and  in  factories.  About 
10,000  persons'are  killed  and  100,000  more  or  less  seriously  injured  on 
the  railroads  of  the  United  States  every  year.  Some  3,000  fatal  acci- 
dents occur  annually  in  the  course  of  mining  operations,  and  probably 
5,000  deaths  result  from  accidents,  in  the  operation  of  machinery  in 
factory  and  workshop.  Much  of  this  is  preventable,  in  fact,  prevented 
in  other  countries.  Winslow  points  out  that  fatalities  are  four  times  as 
common  among  our  railroad  employees  as  among  those  of  England,  and 
other  accidents  seven  times  as  frequent.  Coal  mining  was  nearly  as 
fatal  in  Belgium  between  1830  and  1840  as  it  is  in  the  United  States  to- 
day, but  the  Belgians  have  cut  their  death  rate  down  to  less,  than  one- 
third  of  what  it  was. 

Some  special  injuries  incident  to  work  are :  spinal  curvature  from 
faulty  posture;  flat  feet  or  varicose  veins  from  prolonged  standing,  as  in 
nurses  and  footmen;  injuries  to  the  eyes  from  metal  splinters  or  stone 
fragments;  impairment  of  vision  from  improper  lighting,  or  eye  strain, 
as  in  garment  workers  and  gun  pointers,  or  miners'  nystagmus;  injuries 
to  the  ears,  as  rupture  of  the  tympanum  from  air  pressure  in  caissons; 
labyrinthine  disease  leading  to  deafness  in  boiler -makers  and  gunners. 
Injuries  to  the  skin  are  commonly  caused  by  violence,  but  may  result 
from  excessive  moisture,  as  hydrocystoma  of  laundresses ;  chilblains  of 
cold  storage  workers;  and  ulcers  caused  by  X-ray  or  radium — most  of 
which  are  readily  preventable. 

A  system  of  workmen's  compensation,  by  which  the  victim  of  indus- 
trial accidents,  except  when  caused  by  his  own  neglect,  is  entitled  by 
right,  and  without  legal  proceedings,  to  a  proper  money  equivalent  for 
the  injury  received,  is  simple  justice  which  has  been  long  delayed  in  this 
country.  Workmen's  compensation  laws  have  been  in  successful  opera- 
tion in  all  the  principal  European  countries.  Many  of  our  larger  cor- 
porations voluntarily  and  automatically  compensate  employees  in  case 
of  accidents. 

Workmen's  compensation  laws,  the  first  of  which  was  enacted  in 
1911,  are  now  enforced  in  43  states  and  the  Federal  Government  pro- 
vides such  protection  for  its  own  million  civilian  employees.  The  com- 
pensation provided  runs  from  50  per  cent,  of  the  wages  to  66  2/3  per 
cent.,  and  in  case  of  death,  the  plan  generally  adopted  is  to  give  the 
widow  35  per  cent,  of  her  deceased  husband's  wages  with  10  per  cent,  in 
addition  for  each  child,  the  total  never  to  exceed  66  2/3  per  cent.^^ 

A  compensation  law  should  cover  all  industries  and  not  alone  those 

^American  Asso.  for  Labor  Legislation,  131  E.  23rd  Street,  New  York  City. 


SOME  FUNDAMENTAL  CONSl  DEKATiONS  i291 

that  are  hazardous;  it  should  include  disability  from  occupational  poisons 
as  well  as  from  accidents;  the  payment  should  be  adequate  and  certain. 
A  good  compensation  law  is  one  of  the  best  preventive  measures,  for  it 
has  been  found  that  employers  soon  discover  it  pays  to  safeguard  the 
workmen. 

In  the  case  of  Vennen  vs.  New  Dells  Lumber  Company,  154  N.  W. 
Eep.  040  (Oct.  26,  1915),  the  Supreme  Court  of  Wisconsin  decided  that 
the  death  of  an  employee  caused  by  typhoid  fever,  which  was  contracted 
by  drinking  impure  water  furnished  by  the  employer,  was  the  result  of 
an  "accident"  under  the  terms  of  the  ^Yorkmen's  Compensation  Law, 
and  that  the  employer  was  liable. 

Sedentary  Occupations. — Sedentary  oecupatiuns  in  tliemselves  may 
lead  to  harm,  especially  in  the  cases  of  those  who  bend  forward  while  at 
work,  causing  contraction  of  the  chest  and  pressure  upon  vital  organs 
which  interferes  with  important  physiological  functions.  The  circula- 
tion is  impeded,  respirations  are  shallow,  the  utilization  of  food  is 
diminished  and  the  appetite  fails,  constipation  and  hemorrhoids  are  com- 
mon, and  there  is  a  predisposition  to  common  colds  and  diseases  of  the 
lungs. 

Health  insurance,  or  "sickness  insurance,"  is  a  method  by  which 
the  economic  loss  caused  by  sickness  is  distributed  among  a  group  of 
persons.  The  distribution  is  effected  by  the  payment  of  periodic  pre- 
miums on  the  part  of  members  of  the  group.  In  this  way  the  cost  of 
sickness  arising  from  the  stoppage  of  income,  from  fees  of  doctors,  nurses 
and  hospitals,  from  expenditures  for  medicines  and  the  like,  does  not 
come  as  a  sudden  financial  burden  to  the  insured  individual.  This 
kind  of  insurance  is  now  provided  in  the  United  States  by  many  com- 
mercial companies  and  by  thousands  of  fraternal  orders  and  benefit 
associations  of  a  wide  variety  of  types,  and  is  taken  advantage  of  by  a 
large  proportion  of  those  who  are  thrifty  enough  and  financially  able 
to  pay  the  premiums.  In  the  principal  European  countries  sickness 
insurance  of  wage  earners  has  been  made  a  governmental  function,  but 
with  certain  fundamental  differences  from  that  form  of  sickness  in- 
surance which  exists  in  this  country.  Among  these  differences  are  its 
extension  to  all  wage  earners  upon  a  compulsory  basis,  the  addition  of 
medical  and  hospital  service  and  certain  other  benefits  to  the  cash  pay- 
ments to  the  sick,  and  the  distribution  of  the  cost  of  insurance  not 
only  among  the  insured,  but  also  among  the  two  other  groups — em- 
ployers and  the  public — who  are  considered  responsible  to  some  degree 
for  the  conditions  which  affect  the  health  of  the  insured.  The  proposals 
for  governmental  health  insurance  in  the  United  States  not  only  adopt 
the  principles  just  mentioned,  but  include  additional  features.  Among 
these  are  adequate  medical  service  for  the  insured,  and  definite  pro- 
visions for  rendering  the  health  insurance   system  an  aid  to   disease 


1292    IXDUSTEIAL  HYGIEXE— DISEASES  OF  OCCUPATION 

prevention.  It  has  been  proposed  that  the  preventive  force  of  goT- 
ernmental  health  insurance  shouhl  not  be  limited  to  the  financial  re- 
lief during  sickness,  to  the  medical  services  afforded,  and  to  the  pos- 
sible economic  incentive  to  reduce  sickness,  but  that  it  should  be  greatly 
increased  by  linking  the  health  insurance  system  to  the  existing  public 
health  agencies.  In  this  sense,  "sickness"  insurance,  it  is  believed,  would 
become  a  real  health  measure.  It  would  not  be  merely  a  variety  of  com- 
mercial or  mutual  insurance,  or  another  type  of  public  relief,  but  a  prac- 
tical method  of  improving  and  extending  the  present  facilities  for  the 
prevention  of  disease. 

DISEASES  OF  OCCUPATION 

Classification  of  the  Occupational  Diseases. — Oliver  divides  the  occu- 
pational diseases  into  five  general  classes : 

1.  Diseases  due  to  gases,  vapors,  an-d  high  temperatures. 

2.  Diseases  due  to  conditions  of  atmospheric  pressure. 

3.  Diseases  due  to  metallic  poisons,  diasts,  and  fumes. 

4.  Diseases  due  to  organic  or  inorganic  dust  and  heated  atmos- 
pheres. 

5.  Diseases  due  to  fatigue. 

The  j^rincipal  health  risks  in  industry,  as  far  as  we  know  them, 
may  be  conveniently  classified  according  to  their  nature  as  follows : 

1.  Dusts,  fumes,  gases,  vapors,  and  acids  (poisonous  and  non- 
poisonous  ) . 

2.  Harmful  bacteria  and  microorganisms. 

3.  Compressed  or  rarefied  atmospheres. 

4.  Improper  lighting. 

5.  Extremes  of  temperature. 

6.  Excessive  strain. 

Many  other  classifications  have  been  aitempted,  but  it  is  evident  that 
no  general  system  can  be  entirely  satisfactory.  Each  occupation  requires 
individual  study  and  separate  consideration.  In  many  occupations  a 
combination  of  varying  factors,  such  as  dust  fumes,  poisons,  fatigue,  etc., 
operate  coincidently.  In  the  following  pages  only  the  well-known  and 
better  studied  diseases  of  occupation  and  the  conditions  which  render 
the:n  hazardous,  as  well  as  methods  of  prevention,  are  considered.  The 
number  of  occupational  diseases  is  rapidly  growing  as  the  subject  is 
receiving  more  careful  attention.  Thus  recently  it  has  been  shown  that 
workers  with  heated  tallow  and  other  animal  grease  are  subject  to  gastro- 
intestinal disturbances,  apparently  due  to  the  volatile  fatty  acids  that 
are  given  off  and  that  the  workers  ingest  and  inhale.     A  large  number 


DISEASES  OF  OCCUPATTON  1293 

of  cases  of  poisoning  by  J'unu's  of  ar.^L'iiiuix'ltt'il  hydrogen  have  been  re- 
ported in  recent  years,  the  gas  being  accidentally  evolved  when  a  metal 
such  as  zinc  or  iron  containing  arsenic  as  an  impurity  is  brought  in 
contact  with  a  heavy  acid.  Skin  diseases  are  caused  by  many  of  the 
coal  tar  derivatives,  by  some  of  the  jtetroleum  distillates,  and  are  also 
frequently  found  among  workers  in  the  following  trades:  galvanizing, 
cuttersof  glass  and  pearl  shell,  workers  with  tar,  paraffin,  cement,  dyes, 
printer's  ink,  and  polishers. 

A  comprehensive  list  of  substances  that  injure  working  people  would 
be  long  and  impressive.  It  includes  acids  and  alkalies,  petroleum, 
gasoline,  naphtha,  paraffin,  coal  tar  and  its  derivatives  such  as  benzene, 
anilin,  phenol,  nitranilins  and  nitrophcnols,  toluene  and  trinitrotoluene 
(TXT),  carbon  disulphid,  sulphurated  hydrogen,  the  alcohols,  espe- 
cially methyl  alcohol,  chlorid  of  lime,  the  chromates,  cyanogen,  turpen- 
tine, the  oxids  of  nitrogen,  arayl  acetate,  formaldehyd  and  very  many 
others. 

LEAD 

Lead  poisoning  is  one  of  the  most  frequent,  most  serious,  and  most 
insidious  of  all  the  occupational  intoxicants.  If  a  pound  of  lead  drops 
on  a  workman's  head  the  catastrophe  is  more  obvious  than  if  minute 
quantities  of  lead  are  taken  into  the  system  day  by  day,  but  the  poison- 
ing may  be  as  fatal  as  the  accident.  "Epidemics"  of  lead  poisoning 
sometimes  occur  from  the  drinking  water,  from  beer  and  from  other  un- 
usual sources. 

Lead  is  a  typical  cumulative  poison.  A  large  amount  may  be  taken 
at  one  time  without  noticeable  effect,  but  small  quantities  ingested  daily 
are  absorbed,  stored  in  the  body,  resulting  in  chronic  poisoning  and  ev^n 
death.  Lead  is  excreted  both  by  the  kidneys  and  the  liver,  and  also  the 
skin.  It  probably  does  not  appear  in  the  urine  except  with  albumin,  that 
is,  lead  can  only  pass  a  damaged  kidney.  The  lead  excreted  by  the  liver 
passes  into  the  intestines  with  the  bile  and  may  be  found  in  the  feces. 
The  elimination  of  the  lead,  however,  is  slow  and  uncertain.  As  much 
as  one  ounce  of  the  acetate  of  lead  has  been  taken  at  one  time  without 
injury.  Older  physicians  frequently  prescribed  the  acetate  of  lead  as 
an  astringent  in  doses  of  10,  "20,  or  30  grains.  The  same  amount  of  lead 
distributed  in  minute  doses  and  taken  daily,  would  in  all  likelihood, 
result  in  serious  poisoning.  The  reason  for  this  is  that  when  one  large 
dose  is  taken  only  a  small  c|uantity  is  absorbed ;  the  rest  is  swept  through 
the  intestines,  but  when  small  quantities  are  taken  at  frequent  intervals 
practically  all  is  absorbed  and  the  metal  accumulates  in  the  tissues, 
poisoning  especially  the  delicate  nervous  structures. 

The  susceptibility  to  lead  poisoning  varies  greatly.  Of  a  number  of 
persons  exposed  to  the  same  conditions  some  are  fatally  poisoned,  others 


1294    INDUSTEIAL  HYGIENE— DISEASES  OF  OCCUPATION" 

suffer  with  mild  plumbism,  and  still  others  escape  entirely.  Young  per- 
sons are  much  more  susceptible  than  old.  Young  adults  suffer  most. 
Women  are  more  susceptible  than  men.  Recognizing  this  fact,  in  1898 
England  abolished  female  labor  in  the  dangerous  processes  of  white  lead 
manufacture.  The  reasons  for  this  varying  susceptibility  are  only  partly 
understood.  Hyperacidity  of  the  gastric  juice  is  a  predisposing  factor, 
because  the  lead  in  such  persons  is  readily  converted  to  the  soluble 
chlorid  in  the  stomach.  Personal  cleanliness  is  another  important  fac- 
tor, and  workers  in  lead  who  do  not  give  scrupulous  attention  to  cleanli- 
ness of  person  and  clothing  suffer  most.  Persons  who  are  not  particu- 
larly careful  about  cleaning  their  hands  before  eating,  or  who  frequently 
carry  their  fingers  to  their  mouth  and  nose,  run  especial  risks.  Oliver, 
has  shown  by  experiments  on  animals  that  alcohol  precipitates  attacks 
of  plumbism,  a  fact  which,  in  the  human  subject,  clinical  experience  has 
again  and  again  confirmed.  There  is  not  the  least  doubt  that  alcoholic 
intemperance  predisposes  to  lead  poisoning. 

Practically  all  forms  of  lead  are  poisonous,  even  the  metal  itself. 
The  basic  carbonate  and  the  suboxid  are  the  most  dangerous;  the 
higher  oxids,  litharge  and  red  lead,  come  next.  The  sulphate  and 
ehromate  are  less  soluble  in  human  gastric  juice  and  the  sulphid  is  the 
least  soluble.  The  water-soluble  compoimds,  the  acetate,  chlorid  and 
nitrate,  are  unimportant  in  industry  and  do  not  often  give  rise  to  any 
trouble. 

In  the  majority  of  cases  of  lead  poisoning  in  the  industries  the  lead 
comes  through  the  air  to  the  victim  as  dust,  sometimes  as  fumes.  Pre- 
ventive measures  must,  therefore,  be  directed  toward  keeping  the  air 
about  the  workmen  free  from  lead.  A  lead  trade  is  dangerous  in  propor- 
tion to  its  dustiness.  Lead  is  usually  taken  into  the  system  through  the 
digestive  tract,  although  absorption  from  the  respiratory  tract  and  even 
through  the  skin  may  occur.  For  many  years  it  was  a  disputed  point 
whether  the  lead  entered  through  the  skin  or  the  intestinal  tract,  but  it 
is  now  conceded  that  the  intestinal  mucosa,  also  that  of  the  mouth,  is 
the  usual  portal  of  entry.  Much  of  the  lead  dust  that  is  a  source  of  lead 
poisoning  is,  in  fact,  swallowed.  Lead  is  also  carried  to  the  mouth  by 
the  fingers,  pipes,  chewing  tobacco,  and  in  a  great  variety  of  other  ways. 

The  water-soluble  salts  of  lead  such  as  acetate,  chlorid,  and  nitrate 
may  be  absorbed  through  the  skin,  but  this  is  slow  and  requires  long 
exposure.  It  is  possible  that  the  non-soluble  salts  may  be  changed  by 
contact  with  the  fatty  acids  on  the  skin  into  soluble  compounds.  Lead 
poisoning  may  be  caused  by  absorption  through  the  skin  from  cosmetics 
containing  lead.  Edsall  thinks  skin  absorption  relatively  unimportant. 
In  this  he  is  in  accord  with  Weyl,  Legge,  Oliver,  and  Sommerfeld. 

The  classical  symptoms  of  lead  poisoning  are  a  bluish  black  line  or, 
rather,  collection  of  tiny  spots   (sulphid  of  lead)    along  the  margin  of 


DISEASES  OF  OCCUPATION 


1295 


the  gums  especially  of  the  lower  incisors;  loss  of  appetite,  headache, 
constipation,  colic,  "rheumatic''  pains  in  the  joints  and  muscles,  more 
particularly  in  the  back ;  slee})lessiiess  and  various  vague  nervous  dis- 
turbances. Among  the  earliest  manifestations  of  lead  poisoning  is  the 
pallor  of  the  skin,  out  of  proportion  to  the  anemia  as  determined  by 
the  redness  of  hemoglo])in  and  the  number  of  red  blood  cells.  Lead  can 
often  be  found  in  the  urine,  almost  always  in  the  feces,  and  examination 


Fig.    155. — Red    Oxid   of   Lead   and    Litharge   Being   Mixed   in   the   Manu- 
facture OF  Storage  Batteries. 
The  workman  is  wearing  a  respirator,  but  should  also  protect  himself  with 
long-wristed  gloves. 


of  the  red  blood  cells  usually  shows  a  granular  basophilic  degenera- 
tion, when  stained  with  one  of  the  polychrome  methylene  blue  dyes. 
Lead  palsy  is  rare  in  acute  plumbism,  but  fairly  common  in  chronic. 
It  is  a  motor  paralysis  affecting  those  muscles  which  have  been  subjected 
to  greatest  use;  in  painters,  the  extensors  of  the  wrist;  in  file  cutters, 
the  interosseous  muscles  of  the  hands;  in  lead  smelters,  the  muscles  of 
the  upper  arm  and  shoulder;  and  in  children,  the  muscles  of  the  foot 
and  ankle.  The  cerebral  form  of  plumbism,  known  as  lead  encephalop- 
athy, is  usually  seen  only  after  rapid  intoxication  by  a  massive  ex- 


1296   mDUSTRIAL  HYGIENE— DISEASES  OF  OCCUPATION 

posure  to  lead  dust  or  fumes.  It  is  characterized  by  epileptiform  con- 
vulsions, acute  delirium,  and  partial  or  total  blindness.  It  may  end 
in  death,  or  in  recovery,  or  pass  into  lasting  insanity.^* 

Chronic  lead  poisoning  is  far  more  common  in  industry  than  is  the 
acute  form.  It  is  characterized  by  increasing  anemia,  the  number  of 
corpuscles  falling  sometimes  to  half  normal;  by  indigestion  due  to 
atrophy  of  the  gastric  mucosa;  arteriosclerosis,  resulting  in  interference 
with  the  blood  supply  of  heart  and  kidneys  and  sometimes  of  the 
brain;  lead  palsy,  lead  insanity  or  apoplexy;  a  lowered  resistance  to 
infection,  especially  to  tuberculosis.  From  time  to  time  there  may  be  in 
the  course  of  chronic  plumbism  a  typical  acute  attack  of  lead  colic. 

The  diagnosis  of  industrial  lead  poisoning  is  based  on  the  grayish 
pallor;  the  pinched  appearance  of  the  face;  the  lead  line;  loss  of  appe- 
tite; disagreeable  sweetish  taste;  sense  of  weariness  disproportionate  to 
the  exertion;  loss  of  strength;  loss  of  weight;  gastric  distress;  consti- 
pation; disturbed  sleep.  Aids  to  diagnosis  are  the  detection  of  lead  in 
the  urine  or  feces  and  the  discovery  of.  stippled  red  blood  cells,  which 
to  be  significant  must  number  more  than  100  out  of  a  million. 

Fetal  death  and  abortion  are  common  in  maternal  lead  poisoning. 
Legge  abstracted  from  reports  of  the  British  Factory  Inspection  De- 
partment for  1897  the  following  statistics  concerning  women  lead 
workers:  Of  77  married  women,  15  never  became  pregnant;  15  of 
the  62  who  became  pregnant  never  bore  a  living  child;  among  the 
62  there  were  in  all  212  pregnancies,  but  these  resulted  in  only  61  liv- 
ing children,  21  stillbirths,  miscarriages  90,  and  of  the  101  children 
born  alive,  40  died  soon  after  birth.  Tardieu  reported  to  the  French 
Government  in  1905  that  608  out  of  1,000  pregnancies  in  lead  workers 
had  resulted  in  premature  birth.  The  offspring  may  even  be  affected 
when  the  mother  is  normal  but  the  father  "leaded." 

Cole  and  Bachhuber  ^^  fed  lead  acetate  to  rabbits  and  fowls.  In 
the  rabbits  the  mortality  of  the  young  during  the  first  four  days  after 
birth  was  47.7  per  cent,  for  offspring  of  '^'leaded"  males,  as  contracted 
with  29.2  per  cent,  for  offspring  of  normal  males.  The  average  weight 
at  birth  was  48.9  grams  for  the  former  and  59.0  grams  for  the  latter. 
With  Leghorn  hens  the  results  were  similar.  "Weller  ^^  used  commercial 
white  lead  (basic  carbonate),  which  he  fed  in  capsules  to  guinea-pigs. 
_The  experiments  showed  that  paternal  lead  poisoning  in  guinea-pigs  does 
not  result  in  sterility  or  in  stillbirth,  but  in  reduction  of  weight  at  birth, 
and  this  underweight  persists  throjigh  life.    Next  to  this,  the  most  strik- 

"^ 

"Paul  cited  in  G.  C.  Nijhoff's  article  on  "Action  on  Ovum  of  Superfluous 
Semen,"  Nederl.  Tijdschr.  v.  GeneesJcunde,  Amsterdam,  II,  No.  16. 

^^  Cole  and  Bachhuber:     Proo.  *S'oc.  Exper.  Biol,  and  Med.,  1914. 

i«  Weller,  C.  V.:     Jour.  Med.  Resea/rcli,  1915,  XXXIII,  271. 

The  Effect  on  the  Offspring  of  Lead  Poisoning  in  the  Father:  J.  A.  M.  A., 
Dec.  25,  1915,  LXV,  No.  26. 


DISEASES  OF  OCCUPATION  1297 

inii;  change  is  the  higli  rate  of  mortality  during  the  first  few  days  after 
birth. 

'^^I'lie  character  of  certain  occupations  has  an  influence  on  the  type  of 
lead  poisoning  which  develops.  Thus  Teleky  finds  that,  while  composi- 
ttu's  in  A'icnua  scldinn  siiU'ci'  trdiii  colic  or  from  the  severer  types  of  lead 
poisoning,  thoy  are  subject  to  an  unusual  extent  to  diseases  of  the  lungs 
aiul  kidneys.  The  relation  between  tul)erculosis  and  chronic  plurabism 
is  shown  in  llahn's  diagrams  Iiased  on  the  records  of  typographical  trades 
in  Vienna  and  Berlin,  the  curves  of  the  two  diseases  showing  a  remark- 
able parallelism.  Colic  is  said  by  Legge  to  be  most  frequent  among 
workers  in  white  lead,  red  lead,  enameling,  storage-batteries,  coach-paint- 
ing (which  involves  sandpapering).  Avhile  the  severer  form  with  pa- 
ralysis is  found  in  brass-workers,  plumbers,  printers,  file-cutters,  and 
tinsmiths.  The  former  are  very  dusty  trades ;  poisoning  occurs  rapidly 
and  encephalopathy  is  more  frequent  than  paralysis. 

The  manner  in  which  lead  is  handled  makes  a  vast  difference  so  far 
as  the  liability  to  plumbism  is  concerned.  Thus  Stiller  found  in  Vienna 
that  carriage  painters  are  ten  to  twenty  times  more  subject  to  lead 
poisoning  than  house  painters.  This  has  been  confirmed  by  Edsall  in 
this  country.  The  reason  for  this  is  that  carriage  painters  apply  a  large 
number  of  coats  of  paint  and  varnish,  polishing  between  coats,  and 
thereby  enveloping  themselves  in  dust  which  contains  much  lead;  fur- 
thermore, carriage  painters  are  required  to  work  indoors.  For  lead  poi- 
soning due  to  water  see  page  1155. 

lead  Oxids,  Litharge  and  Red  Lead. — In  the  manufacture  of  lith- 
arge and  red  lead,  the  metal  is  roasted  in  reverberatory  furnaces  and 
raked  from  time  to  time.  The  raking  or  rabbling  and  the  discharge 
from  the  furnace  may  be  mechanical,  in  which  case  the  danger  from 
fumes  and  dust  is  very  much  lessened.  The  oxids  are  light  and  fluffy 
and  it  is  hard  to  control  the  dust  produced  in  dumping,  grinding,  sift- 
ing and  packing  them,  and  although  great  improvements  have  taken 
place  in  many  oxid  works  of  late  years,  the  rate  of  plumbism  in  this 
industry  is  still  fairly  high. 

The  oxids  are  used  in  making  storage  batteries,  the  plates  of  which 
are  leaden  grids  with  a  paste  of  litharge  or  red  lead  rubbed  into  the 
interstices.  This  industry  is  recognized  in  all  countries  as  one  of  the 
most  dangerous  of  the  lead  trades.  Litharge  is  also  used  in  rubber 
compounding,  and  men  employed  in  weighing  out  the  compounds  and 
on  the  mixing  mills  may  suffer  from  lead  poisoning.  Eed  lead  is  used  as 
paint  for  bridges,  structural  iron  work,  certain  parts  of  railway  cars, 
and  ships — especially  battleships.  Stitt  ^'^  reported  three  cases  of  lead 
poisoning  and  encephalopathy  in  men  who  were  chipping  old  red  lead 
paint  from  the  bottoms  of  battleships.    Eed  lead  is  also  used  in  making 

"  U,  S.  Naval  Med.  Bull,  1912,  Vol.  VI,  p.  161. 


1298  TNDUSTEIAL  HYGIENE— DISEASES  OF  OCCUPATION 

glazes  for  tiles  and  terra  cotta,  and  enamel  for  porcelain  enameled  sani- 
tary ware,  and  in  these  occupations  there  is  a  great  deal  of  industrial 
plumbism. 

White  Lead. — Most  of  the  white  lead  is  still  made  by  the  old  Dutch 
method,  which  consists  in  the  transformation  of  metallic  lead  into  the 
white  carbonate  by  a  slow  and  double  process  of  conversion.  Numerous 
earthenware  pots  containing  3  per  cent,  of  acetic  acid  are  placed  on  tan 
bark  in  a  large  three-walled  chamber,  and  upon  these  pots  are  laid  thin 


Fig.  156. — A  Workee  with  Lead  Oxid,  Showing  Respirator  to  Protect  Him- 
self AGAINST  THE  POISONOUS  DusT.     (Mass.  State  Board  of  Health.) 


strips  of  metallic  lead  and  subsequently  planks  of  wood.  Tier  after  tier 
of  pots  resting  on  bark  and  covered  with  metallic  lead  and  wood  are  thus 
superimposed  until  the  chamber,  25  or  30  feet  in  height,  is  filled  to 
within  6  feet  from  the  top.  This  chamber,  known  as  the  "blue"  bed,  is 
kept  closed  for  14  weeks  or  longer.  Fermentation  causes  a  rise  in  tem- 
perature and  a  production  of  carbonic  acid.  The  acetic  acid  acts  upon 
the  lead  and  converts  it  into  acetate  of  lead,  while  the  COg  evolved  from 
the  bark  changes  the  acetate  into  carbonate  or  the  well-known  white  lead 
of  commerce.  The  danger  of  plumbism  occurs  during  the  emptying  or 
stripping  of  what  is  now  called  the  "white"  bed.  If  sufficient  time  has 
not  been  given  for  the  very  soluble  acetate  to  have  become  changed  into 
the  carbonate  the  danger  is  thereby  greater.     During  the  stripping  of 


DISEASES  OF  OCCUPATION  1299 

the  'Svhite''  bed  there  is  a  considerable  quantity  of  dust  raised,  a  large 
part  of  which  is  white  lead. 

Legge  found  that  of  1,463  persons  employed  ofT  and  on  in  white 
lead  works  the  incidence  of  lead  poisoning  was  G  per  cent,  of  the  aver- 
age number  regularly  employed,  and  in  those  casually  employed  39 
per  cent.  This  shows  the  great  risk  of  exposing  unskilled  labor  in  a 
dangerous  occupation. 

In  making  so-called  pulp  lead,  the  white  lead  suspended  in  water 
is  not  dried  but  is  ground  in  oil  which  gradually  displaces  the  water, 
a  method  involving  far  less  risk  of  poisoning. 

The  Carter  process,  much  used  at  present  in  the  United  States,  is 
a  rapid  corrosion  of  atomized  lead,  the  great  advantage  of  which  is  that 
it  is  largely  mechanical  and  requires  very  little  labor  in  proportion  to 
output. 

The  Manufacture  of  Pottery  and  Earthenware. — Lead  poisoning  in 
potteries  and  tile  works  has  been  notorious  for  years  in  Europe.  In 
England  and  Germany,  especially,  great  efforts  have  been  made  to  pro- 
tect the  workers  against  this  danger.  Aside  from  the  precautions  taken 
to  avoid  dust  and  other  dangers  in  potteries,  the  English  use  a  great 
deal  of  leadless  glaze,  and  when  this  is  not  possible  they  frit  the  lead, 
that  is,  they  fuse  it  with  the  other  constituents  of  the  glaze,  thus  chang- 
ing soluble  white  lead  or  red  lead  in  part  or  wholly  to  the  insoluble 
disilicate.  This  is  not  done  in  American  potteries  where  the  glaze  is 
fritted,  but  the  lead  is  added  subsequently.  It  is  also  unfortunately 
true  that  American  potteries  cannot  bear  comparison  with  British  or 
German  potteries  in  respect  to  construction  or  cleanliness  or  personal 
protection  of  the  workers,  and  there  is  much  more  lead  poisoning  among 
the  men  and  women  potters  in  America  than  in  Europe. 

The  chief  centers  for  the  manufacture  of  table  and  toilet  ware, 
sanitary  earthenware,  so-called  art  pottery,  and  tiles,  are  Trenton,  ISTew 
Jersey,  and  the  East  Liverpool  and  Zanesville  districts  of  Ohio.  The 
work  of  glazing  and  decorating  the  pottery  carries  with  it  the  danger 
of  lead  poisoning,  although  it  is  only  decoration  with  lead  colors  that 
is  dangerous;  decalcomania  or  the  use  of  lithotransfer  paper  is  not 
attended  with  any  danger.  The  glazes  used  in  white  ware  potteries  in 
1911  contained  from  1.75  to  33.3  per  cent,  of  white  lead.  In  the  pot- 
teries making  art  and  utility  ware  (yellow  ware),  and  in  the  tile  works, 
the  glazes  contained  from  5  to  60  per  cent,  of  white,  more  rarely  red 
lead.  The  dangerous  processes  are  mixing  the  glaze,  dipping  the  ware 
in  the  glaze,  cleaning  the  dipped  ware  to  get  rid  of  the  excess  of 
glaze,  and  stacking  it  on  boards  or  trays  to  be  fired,  firing  it  in  the  glost 
kilns,  and  decorating  it  by  the  processes  known  as  color  blowing,  or 
tinting  and  ground  laying. 

The   difference  between  the   sanitary   control    of   this   industr}^   in 


1300   INDUSTRIAL  HYGIENE— DISEASES  OF  OCCUPATION 

England  and  in  the  United  States  is  shown  by  the  rate  of  plumbism 
in  the  two  countries.  In  English  potteries  in  1910,  the  morbidit}'  rate 
for  plumbism  was  0.8  per  cent,  for  men  and  1.5  per  cent,  for  women, 
while  in  68  American  potteries  and  tile  works  in  1911  the  rate  was  8 
per  cent,  for  men  and  14  per  cent,  for  women.^^  Since  that  year  im- 
provements have  been  introduced  in  American  potteries,  but  they  are 
not  yet  nearly  up  to  the  English  standard. 

Lead  Mining,  Lead  Smelting  and  Refining. — In  lead  mining  there 
is  little  danger  of  poison,  for  the  ore  is  chiefly  sulphid  which  is  only 
sparingly  soluble  in  human  gastric  juice.  Smelting  and  refining  of  the 
ore  are  industries  attended  with  a  great  deal  of  plumbism  from  both 
dust  and  fumes.  In  smelting,  the  greatest  danger  is  found  in  the  work 
at  the  open  hearths,  the  blast  furnaces,  and  the  cleaning  out  of  flues 
and  bag  houses;  in  refineries  the  danger  from  fumes  should  not  be 
so  great,  but  there  is  more  dust  because  the  refineries  work  up  not  only 
lead  bullion  but  all  varieties  of  lead  scrap  and  refuse,  some  of  which 
is  very  powdery  and  fluffy.  The  industry  in  the  United  States  em- 
ployed in  1913  some  7,500  men,  and  the  rate  of  lead  poisoning  was 
over  22  per  cent.,  whereas  in  England  during  the  previous  year  the 
rate  was  1.8  per  cent,  among  about  2,000  men.^^ 

Miscellaneous  Industries. — Layet  computed  that  in  France  111  in- 
dustrial processes  involved  the  use  of  lead.  Hamilton  found  70  such 
processes  in  Illinois  in  which  lead  or  its  compounds  are  handled  and 
which  have  caused  lead  poisoning  in  recent  times.^° 

Some  of  the  industries  in  addition  to  those  mentioned  above  in 
which  lead  poisoning  may  occur  are:  making  and  selling  wall  paper; 
retouching  photographs  with  white  lead  paint  for  catalogues  and  adver- 
tisements; polishing  brass  (the  alloy  containing  lead)  ;  polishing  cut 
glass  with  lead  putty  powder;  mixing  compounds  for  rubber.  Other 
trades  that  use  metallic  lead  are  very  numerous,  including  the  making 
of  wire,  sheet,  piping,  plumbers'  goods,  machine  parts,  tinfoil,  car  seals 
and  can  seals,  picture  frames,  trimmings  for  coffins,  and  the  use  of 
solder  and  Babbitt.  The  most  important  one,  however,  is  the  printer's 
trade,  where  the  amount  of  lead  dust  and  fume  is  slight,  but  long  con- 
tinued exposure  brings  about  a  serious  form  of  chronic  plumbism  marked 
especially  by  a  lowered  resistance  to  tuberculosis. 

Certain  occupations  which  are  dwelt  on  in  the  European  litera- 
ture as  sources  of  serious  lead  poisoning  are  fairly  free  from  this  danger 
in  the  United  States  because  our  methods  are  different.  File  cutting 
is  one  of  these,  the  file  being  strapped  to  a  strip  of  lead;  another  is 
diamond  polishing,  the  jewel  being  imbedded  in  lead.     Very  little  jewel 

^Bull.  No.  104,  U.  S.  Bureau  of  Labor  Statistics. 
^  Bull.  No.  141,  U.  S.  Bureau  of  Labor  Statistics. 
^V.  A.  M.  A.,  1911,  Vol.  LVI.  p.  1240. 


DISEASES  OF  OCCUPATION"  1301 

polishing  of  this  sort  is  done  in  the  United  States  and  file  cutting  is 
mostly  done  by  machinery.  Euroi)cans  also  use  lead  colors  in  print- 
ing textiles  and  dyeing  them,  as  mc  do  not,  and  while  we  plate  kitchen 
ware  with  a  lead-free  enamel  or  with  a  pure  tin,  they  j)late  it  w'ith  a 
mixture  of  tin  and  lead,  often  a  large  proportion  of  the  latter. 

PREVENTION 

The  prevention  of  lead  poisoning  rests,  in  tlic  main,  upon  the  fact 
that  the  lead  comes  to  the  workman  usually  as  dust,  sometimes  as  fumes 
through  the  air,  but  it  must  be  remembered  that  lead  is  also  carried  to 
the  mouth  by  deposits  on  the  hands  and  other  objects.  Practical  ef- 
forts for  the  protection  of  lead  workers  must  be  directed  first  to  the 
prevention  of  dust  and  the  removal  of  fumes;  second  to  provisions  for 
bodily  cleanliness. 

The  first  essential  then  is  to  keep  the  air  which  the  workman  breathes 
and  which  surrounds  him  free  of  lead.  Most  cases  of  lead  poisoning 
could  be  averted  by  a  proper  system  of  ventilation.  Certain  processes 
should  be  carried  on  under  hoods  with  a  strong  draft,  or  in  cabinets,  or 
in  special  rooms  with  an  air  current  so  arranged  that  the  lead  is  kept 
away  from  the  mouth,  nose,  hands,  and  clothes  of  those  who  are  ex- 
posed. 

On  the  part  of  the  workman  the  prevention  of  lead  poisoning  con- 
sists in  cleanliness  of  the  hands  and  of  the  finger  nails,  frequent  bathing, 
and  the  use  of  special  clothing  while  at  work.  Care  must  be  taken  not 
to  carry  the  fingers,  which  may  be  contaminated  with  lead,  to  the  mouth 
and  nose,  and  to  wash  the  hands  thoroughly  before  eating.  Workmen 
should  never  take  their  lunch  in  the  rooms  where  there  is  a  suspicion  of 
lead  in  the  air.  The  hazard  of  chewing  tobacco  under  such  circumstances 
is  obvious.  Respirators  may  afford  protection  in  emergency  and  short 
exposure,  but  cannot  be  depended  on  as  a  routine  precaution,  because  the 
workmen  will  not  wear  them  continuously. 

Cleanliness  is  one  of  the  all-essential  requirements.  A  special  room 
for  the  clothes  of  the  workmen  and  special  overalls  should  be  provided 
for  those  who  are  exposed  to  lead.  It  is  ignorance  of  the  danger  and  the 
want  of  personal  cleanliness  that  make  casual  labor  in  lead  works  espe- 
cially dangerous.  Even  the  women  who  wash  the  clothes  of  the  workmen 
employed  in  lead  factories  may  sometimes  suffer  from  lead  poisoning. 
Lavatories  should  be  provided  at  the  factory  and  the  hands  should  be 
washed  with  water  containing  a  small  quantity  of  acetic  acid  followed  by 
a  liberal  allowance  of  soap. 

Workmen  should  alternate  employment  and  not  remain  too  long  in 
the  dangerous  departments.  Supplanting  hand  labor  by  machinery 
diminishes  the  number  exposed  to  the  risk.    A  medical  inspection  is  an 


1302   INDUSTRIAL  HYGIENE— DISEASES  OF  OCCUPATION 

important  preventive  guard  in  educating  the  workmen  and  in  detecting 
mild  and  beginning  cases. 

A  radical  measure  would  be  the  substitution  of  zinc-white  for  lead 
paints.  Zinc  may  be  used  as  a  substitute  for  lead,  especially  in  indoor 
work ;  in  fact  this  has  been  required  by  law  in  France.  White  lead  ap- 
pears-to  be  superior  to  zinc  for  outdoor  work. 

Keeping  down  the  hyperacidity  of  the  gastric  juice  is  believed  to  be 
a  good  preventive  measure.  This  may  be  accomplished  in  part  by  taking 
a  bland  oil  or  drinking  milk  at  intervals  during  work.  Milk  also  acts  by 
fixing  the  HCl  of  the  gastric  juice  by  the  milk  proteins.  The  milk  should 
be  taken  between  meals  (say  10  a.  m.  and  4  p.  m.)  for  in  some  persons 
there  is  considerable  secretion  of  gastric  juice  in  the  empty  stomach. 

The  Massachusetts  State  Board  of  Health  issues  the  following  pro- 
tective measures  against  lead  poisoning :  ^^ 

The  poison  gains  entrance  into  the  system: 

(1)  By  swallowing  minute  particles  of  lead. 

(2)  By  inhaling  lead  dust  or  the  fumes  of  lead  in  a  molten  state, 
or  the  vapor  of  lead  in  a  fused  state. 

(3)  By  absorption  from  the  skin  in  handling  lead. 

Advice  to  Employees 

(1)  General  personal  cleanliness  is  of  the  first  importance. 

(2)  Thoroughly  clean  your  hands  before  touching  food  and  before 
leaving  the  workroom. 

(3)  Thoroughly  rinse  your  mouth  before  eating. 

(4)  Take  good,  nutritious  food  and  plenty  of  milk. 

(5)  Take  a.  substantial  breakfast;  an  empty  stomach  is  more  sus- 
ceptible to  the  poisonous  effects  of  lead. 

(6)  Never  eat  at  your  work.  Eat  your  luncheon  outside  of  the 
workroom  if  possible;  if  not,  in  a  part  of  the  room  away  from  the  lead. 
Never  smoke  or  use  tobacco  in  any  form  while  at  work. 

(7)  Avoid  all  excesses;  alcoholic  beverages  are  especially  injurious. 

(8)  Wear  overalls  or  a  long  coat  at  your  work ;  also  a  cap  or  some  head 
covering.     Whenever  practicable  wear  gloves  when  lead  is  to  be  handled. 

(9)  Persons  working  in  white  lead  or  other  powdered  compounds 
of  lead  should  always  wear  a  respirator  while  at  work.  Cause  as  little 
dust  as  possible. 

(10)  Consult  a  physician  at  the  first  sign  of  ill  health. 

Advice  to  Employers 

(1)  Provide  washing  facilities,  lockers,  and  a  place  for  the  em- 
ployees to  eat  luncheons  away  from  lead. 

=^See  also  U.  S.  PuUic  Health  Reports,  Dec.  19,  1919,  p.  2905. 


DISEASES  OF  OCCUPATION  1303 

(2)  Provide  respirators  for  all  the  workers  wlio  luive  to  handle 
white  lead  or  other  ])owdered  compounds  of  lead. 

(;?)  'Vhv  tloors  (if  till'  workrooms  and  benches  at  wliicli  men  work 
should  be  cleaned  (hiily  after  tliorou'j^'hly  nioisteninfj^  them. 

(4)  These  regulatit)ns  should  be  posted  in  a  conspicuous  place  in 
the  workroom. 

PHOSPHORUS 

There  are  two  kinds  of  phosphorus:  (1)  the  white  or  yellow,  dis- 
covered by  Brandt  of  Haml)ur<?  in  1G69,  (2)  the  red  or  amorphous,  dis- 
covered by  Schriiter  of  Vienna  in  1845.  The  amorphous  phosphorus  is 
obtained  from  the  white  phosphorus  by  exposing  it  in  a  closed  vessel 
for  some  time  to  a  temperature  of  250°  C.  The  white  or  yellow  phos- 
phorus is  poisonous  and  has  been  the  cause  of  much  suffering  in  the 
match  industry.  The  red  or  amorphous  phosphorus  is  practically  not 
poisonous. ^^ 

Throe  kinds  of  matches  are  made:  (1)  The  safety  match,  which  con- 
tains no  phosphorus  and  is  harmless.  The  match  heads  contain  potas- 
sium chlorate  or  chromate  and  other  compounds  rich  in  oxygen  from 
which  the  oxygen  required  to  induce  conflagration  is  evolved.  The  paste 
applied  to  the  side  of  the  match-box  contains  antimony  sulphid  and  red 
phosphorus.  (2)  The  strike-anywhere  match  contains  the  poisonous 
white  phosphorus  in  the  head,  and  in  addition  glue,  chlorate  of  potassium, 
powdered  glass,  and  magenta  or  some  other  coloring  agent.  The  paste, 
or  composition,  contains  on  an  average  5  per  cent,  of  phosphorus.  It  is 
in  mixing  this  paste,  especially  when  done  by  hand  in  open  vessels,  and 
also  in  dipping  the  wooden  splints,  that  the  work-people  are  exposed  to 
fumes  that  become  a  menace  to  health.  (3)  The  strike-anywhere  match 
made  with  the  non-poisonous  sesquisulphid  of  phosphorus. 

When  pure,  phosphorus  is  colorless  and  transparent,  but  when  ex- 
posed to  the  light  it  becomes  yellowish.  The  white  and  yellow  forms  are 
extremely  poisonous ;  the  red  and  amorphous  phosphorus  can  be  handled 
with  impunity.  Eed  phosphorus  does  not  take  fire  when  rubbed  on  a 
rough  surface.  It  is  non-volatile  and  when  swallowed  is,  comparatively 
speaking,  non-poisonous.  One  to  3  grains  of  white  phosphorus  will 
cause  death.  The  fumes  from  white  or  yellow  phosphorus  are  rich  in 
phosphorus  oxids  and  these  are  absorbed  in  various  ways. 

Several  years  ago  the  Belgian  government  offered  a  prize  'of  50,000 
francs  to  any  person  who  would  invent  a  safety  strike-anywhere  match 
free  from  white  phosphorus.  The  problem  was  solved  by  Sevene  and 
Cahan  of  France,  who  demonstrated  that  the  sesquisulphid  of  phosphorus 
would  accomplish  all  that  white  phosphorus  does  without  causing  pois- 

=^  Phosphorus  Poisoning  in  the  Match  Industry,  by  J.  B.  Andrews,  Bull.  86, 
U.  S.  Bwreau  of  Labor. 


1304   JNDUSTPJAL  HYGIENE— DISEASES  OF  OCCUPATION 

oning.  The  sesquisulphid  is  an  almost  inodorous  powder  and  is,  practi- 
cally speaking,  non-poisonous.  It  contains  a  trace  of  red  or  amorphous 
phosphorus.  Since  the  introduction  into  France  of  the  manufacture  of 
the  sesquisulphid  match  there  has  not  been  in  the  factories  of  that 
country,  where  the  manufacture  of  matches  is  a  state  monopoly,  one  case 
of  phosphorus  poisoning,  nor  has  there  been  any  explosion  or  fire  in  any 
of  the  match  works.  It  has  been  found  that  the  sesquisulphid  of  phos- 
phorus acts,  in  some  instances,  as  an  irritant,  causing  conjunctivitis  and 
edema  of  the  eyelids,  also  eczema  of  the  skin.  This  may  be  obviated  by 
bathing  the  eyes  and  douching  the  nostrils  twice  a  day  before  leaving 
the  factory  with  an  alkaline  solution  of  bicarbonate  of  soda. 

AVhite  phosphorus  Inciter  matches  were  first  made  in  1833  and 
the  disease  known  as  "phossy  jaw"  was  first  reported  by  Lorinser  of 
Vienna  in  1845.  Soon  after  that,  similar  cases  were  reported  from  prac- 
tically all  European  countries.  In  the  United  States,  lucifer  matches 
were  first  made  in  Springfield,  Massachusetts,  in  1836,  and  in  1851  there 
was  the  first  description  of  a  case  of  ph'ossy  jaw  in  America,  a  man  who 
was  treated  in  the  Massachusetts  General  Hospital.  The  effects  of  phos- 
phorus poisoning  in  match  workers  attracted  widespread  attention  be- 
cause of  its  painfulness  and  its  disfiguring  effects,  and  it  was  not  long 
before  the  public  in  all  European  countries  began  to  agitate  against  the 
conditions  giving  rise  to  it  and  to  demand  their  abolition.  After  all  forms 
of  governmental  regulation  had  been  tried  without  success,  the  prin- 
cipal countries  of  Europe  entered  into  an  agreement,  the  Berne  Con- 
vention of  1906,  by  which  the  manufacture,  importation,  and  sale  of 
white  phosphorus  matches  were  prohibited.  The  United  States  was 
not  a  party  to  this  agreement,  and,  at  this  time  and  for  several  years 
after,  there  was  a  general  belief  in  this  country  that  our  superior  meth- 
ods and  our  factory  sanitation  had  driven  phossy  jaw  out  of  American 
match  factories,  but  the  thorough  investigation  carried  on  by  John  B. 
Andrews  in  1910  showed  that  this  was  a  fallacy.  He  discovered  a  total 
of  150  cases  of  phosphorus  poisoning  in  the  match  industry,  some  of 
them  very  severe,  attended  with  shocking  disfigurement,  and  four  of 
them  fatal.  The  publication  of  his  report  resulted  in  the  passage  of  the 
Esch  Law  in  1912,  which  placed  a  prohibitive  tax  on  white  phosphorus 
matches.  In  1913  their  importation  became  illegal  and  the  following 
year  their  exportation. 

The  reason  for  the  widespread  attention  given  to  phossy  jaw  is 
not  its  great  prevalence — for  only  a  small  proportion  of  those  exposed 
suffer — nor  because  it  is  very  dangerous  to  life,  for  the  mortality  is 
about  15  per  cent.  It  is,  however,  extremely  painful  and  the  results 
are  dramatically  visible  to  everyone.  It  attacks  the  bones  of  the  jaw, 
producing  deformities  and  disfigurements,  and  it  is  accompanied  by  a 
distressingly  fetid  discharge.     The  action  of  the  phosphorus  fumes  takes 


DISEASES  OF  OCCUPATION  1305 

place  throiif]rh  a  defective  tooth  or  tliro>i,i,di  the  woiiiul  left  hy  the  ex- 
traction of  a  tooth,  ami  tlic  fiiiiifs  reach  the  pcriostciiiii  of  the  jaw-hones, 
upper  or  lower,  or  hoth.  A  necrotic  process  sets  in  and  then  infection 
by  suppurative  germs  in  the  mouth  causes  abscess  formation  with  in- 
tense siiflFering.  Abscesses  in  the  iipjier  jaw  discharge  on  the  cheek  or 
into  the  mouth,  those  of  the  h)wer  jaw  make  their  way  down  on  the 
neck.  Absorption  from  the  suppurative  process  causes  cachexia,  which 
renders  the  victims  an  easy  prey  for  tuberculosis,  or  they  may  die  of 
chronic  septicemia.  In  rarer  cases,  the  periosteum  of  other  hones  is 
attacked,  rendering  them  brittle  and  liable  to  fracture  under  very  slight 
violence  (fragilitas  ossium). 

The  matches  now  made  are  the  red  phosphorus  safety  match,  and 
"strike  anywhere"  matches  made  with  the  sesquisulphid,  neither  of  which 
is  poisonous. 

ARSENIC 

i\.rsenic  acts  as  an  irritant  to  the  skin  and  mucous  membranes,  'set- 
ting up  conjunctivitis,  coryza,  eczema  and  ulcerations;  it  also  produces 
general  poisoning,  causing  anemia  and  neuritis  and  degenerative  changes 
in  liver  and  kidneys.     Arsenical  neuritis  is  particularly  severe. 

Arsenic  is  present  in  almost  all  the  sulphid  ores  of  the  metals  and 
is  therefore  encountered  in  iron,  lead,  zinc  and  copper  smelting.  The 
flue  dust  of  the  western  lead  smelters  contains  large  quantities  which 
are  recovered  by  sublimation  as  white  arsenic — the  trioxid.  used  in  va- 
rious industrial  processes.  The  other  compounds  of  arsenic  which  are 
industrially  important  are  lead  arsenate  and  the  aceto-arsenite  of  cop- 
per, or  Paris  green,  both  of  which  are  used  to  kill  insects  and  para- 
sites. White  arsenic  is  used  as  a  sheep  dip,  and  a  preservative  for  hides, 
skins  and  feathers.  It  is  also  used  in  curing  furs.  The  Massachusetts 
law  forbids  more  than  one  grain  of  arsenic  per  square  yard,  but  analyses 
reveal  that  it  often  reaches  170  grains.  Out  of  -±2  samples  of  fur  recently 
examined  in  America,  11  were  found  heavily  loaded  with  arsenic.  The 
presence  of  such  large  quantities  of  arsenic  in  furs  that  are  worn  or  in 
rugs  for  rooms  must  be  a  source  of  danger.  Another  danger  in  former 
years  came  from  the  use  of  arsenical  colors  in  wall  papers  and  textiles, 
but  this  is  no  longer  a  serious  matter  in  the  United  States.  The  Massa- 
chusetts law  of  1900  limited  the  amount  of  arsenic  in  wall  paper  to  0.1 
grain  per  square  yard,  and  in  textiles  for  clothing  to  0.01  .grain.  In 
1904,  an  investigation  made  by  the  U.  S.  Department  of  Agriculture 
showed  that  only  4  out  of  537  samples  of  wall  paper  had  more  than  0.1 
grain  per  square  yard. 

Workers  in  compounds  of  arsenic  often  present  general  symptoms 
resembling  those  of  lead  poisoning;  namely,  anemia,  loss  of  strength, 
loss  of  appetite,  gastric  disturbances,  but  instead  of  palsy  of  certain 


1306   INDUSTRIAL  HYGIENE— DISEASES  OF  OCCUPATION 

muscles  there  is  a  painful  neuritis  and  the  arsenical  worker  suffers  from 
lesions  of  the  skin  which  serve  to  distinguish  this  form  of  poisoning 
very  sharply  from  plumbism.  Workers  in  Paris  green  suffer  from  pain- 
ful redness  of  the  eyes  and  from  eczema  of  the  eyelids,  they  have  pain- 
ful ulcers  around  the  lips  and  nostrils  and  in  the  folds  of  the  skin 
where  the  perspiration  collects.  Ulcers  of  the  scrotum  are  particularly 
common. 

During  the  latter  part  of  1900,  there  occurred  in  England  and 
Wales  an  epidemic  of  arsenic  poisoning,  affecting  at  least  6,000  persons. 
The  districts  principally  affected  were  in  Lancashire  and  Staffordshire. 
The  cause  was  arsenic  which  contaminated  beer  from  breweries  that 
used  glucose  and  invert  sugar  from  a  single  firm. 

From  0.008  to  0.131  per  cent,  of  arsenic  was  found  in  the  glucose, 
and  from  0.02  to  0.063  per  cent,  in  the  invert  sugar,  estimated  as 
arsenous  oxid.  The  arsenic  came  from  the  sulphuric  acid^  used  to 
hydrolyze  the  starch  to  make  the  glucose  and  invert  sugar,  and  con- 
tained from  1.4  to  2.6  per  cent,  of  arsenous  oxid. 

Arsenic,  as  well  as  other  irritants,  is  believed  to  predispose  the  tis- 
sues to  growths  of  a  cancerous  nature. 

Arseniuretted  Hydrogen. (AsH^). — More  serious  than  arsenical  dust 
is  the  gas,  hydrogen  arsenid,  commonly  called  arseniuretted  hydro- 
gen, which  is  accidentally  evolved  in  the  course  of  many  industrial 
processes.  The  effects  of  this  gas  often  fail  to  be  recognized  because 
the  presence  of  the  arsenic  is  not  suspected.  Almost  all  of  the  metals 
used  in  industry  are  derived  from  arsenic-bearing  ores,  and  are  there- 
fore frequently  contaminated  with  arsenic.  The  larger  part  of  the  sul- 
phuric acid  used  in  industry  is  made  from  iron  sulphid  or  pyrites,  and 
may  also  have  traces  of  arsenic.  Whenever,  therefore,  such  an  acid  and 
metal  come  in  contact,  hydrogen  arsenid  may  be  given  off  and  severe, 
often  fatal  poisoning  results  from  the  inhalation  of  the  gas.  Work- 
men cleaning  out  or  repairing  iron  tanks,  which  have  held  arsenic,  have 
been  poisoned  in  this  way.  Other  occupations  which  involve  this  danger 
are  the  production  of  hydrogen  from  zinc  dust  and  hydrochloric  acid, 
and  the  use  of  such  hydrogen  for  the  flame  of  the  lead  burner  and 
for  filling  balloons.  Similar  accidents  have  occurred  in  making  acids 
from  arsenic-bearing  compounds ;  treating  waste  zinc  from  a  galvanizing 
plant  with  hydrochloric  acid  to  make  zinc  chlorid ;  pickling  metals,  i.  e., 
dipping  in  acid  in  preparation  for  plating  or  enameling;  recovering 
copper  by  electrolysis. 

Arsenic  is  no  longer  used  in  the  manufacture  of  aniline  dyes,  but 
arsenical  poisoning  sometimes  occurs  accidentally  in  dye  manufacture 
during  the  process  of  reduction  which  requires  the  use  of  metallic  dust 
and  acid.  Recently  wholesale  poisoning  from  this  gas  occurred  on  a 
British  submarine,  the  source  being  the  storage  batteries  in  which  acid 


DISEASES  OF  OCCUPATION  1307 

came  in  contact  with  plates  made  fi-oiii  an  anliiiioiiy-lcad   alloy  which 
contained  arsenic. 

The  symptoms  of  this  form  of  poisoning  are  quite  different  from  that 
caused  hy  arsenical  dusts.  I'licre  is  a  rapid  onset,  with  nausea,  vomit- 
ing, pain  in  (he  epigastiium,  headache,  dizziness,  dark  or  even  bloody 
urine.  Tlie  red  blood  corpuscles  undergo  a  rapid  destruction,  falling 
sometimes  to  less  than  a  million,  and  the  liver  and  kidneys  in  fatal  cases 
are  found  in  a  condition  of  hemorrhagic  inflammation.  The  mortality 
in  industrial  cases  is  about  3()  per  cent.^^ 

MERCURY 

Mercurial  poisoning-'*  may  be  contracted  by  workmen  employed  in 
extracting  mercury  from  cinnabar  (sulphid  of  mercury),  in  which  it  is 
usually  found  in  nature.  The  ore  is  simply  roasted  and  the  mercury 
volatilizes  and  readily  condenses  in  metallic  form.  Mercury  volatilizes 
at  a  low  temperature  and  it  is  this  circumstance  which  creates  much  of 
the  danger  to  those  who  work  with  this  substance,  especially  to  men  who 
work  in  a  closed  and  heated  atmosphere  containing  the  vapor  given  off 
by  the  metal.  ]\Iercury  is  absorbed  by  the  digestive  system^  by  the  respi- 
ratory tract,  and  also  through  the  skin.  As  an  instance  of  the  absorption 
of  mercury  through  the  skin  Edsall  cites  two  cases  in  dentists  who  were 
poisoned  as  a  result  of  the  custom  found  in  many  dentists  of  working 
up  their  amalgam  in  the  palms  of  their  hands. 

The  occupations  in  which  mercury  is  used  and  in  which  mercurial 
poisoning  occurs  are :  the  separation  of  gold  and  silver  from  their  re- 
spective ores,  which  is  done  by  means  of  an  amalgam ;  the  manufacture 
of  incandescent  lamps,  in  which  mercury  pumps  are  used,  to  create  a 
vacuum;  in  barometer  and  thermometer  making;  in  felt-hat  and  fur 
dressing,  in  which  mercuric  nitrate  is  used;  in  water-gilding,  where 
an  amalgam  of  gold  or  silver,  after  having  been  applied  to  an  object,  is 
heated  and  the  mercury  driven  off;  and  other  industries. 

The  ISTew  York  and  jSTew  Jersey  section  of  the  Xational  Civic  Federa- 
tion in  three  months'  time  found  60  cases  of  mercurial  poisoning,  a 
nervous  disease  called  in  the  trade  "^the  shakes-,"  among  the  hat  makers 
of  Brooklyn,  Newark,  and  Orange  as  a  result  of  the  mercury  salts  used 
in  preparing  felt. 

The  symptoms  of  mercurial  poisoning  are :  anemia,  headache,  dizzi- 
ness, tremor  of  the  muscles,  especially  the  tongue  and  limbs,  fetid  breath, 
soft,  swollen,  and  ulcerated  gums,  and  loosening  of  the  teeth.  The  sub- 
maxillary and  other  glands  of  the  neck  become  painful  and  the  secretion 

'"T.  M.  Legge  in  Kober  and  Hanson's  "Diseases  of  Occupation,"  page  3, 
Philadelphia,  1916. 

^^  Report  of  Mercurial  Poisoning  in  the  Industries  of  New  York  and  Vicinity: 
L.  W.  Bates,  National  Civic  Federation,  1912. 


1308   INDUSTElAL  HYGIENE— DISEASES  OF  OCCUPATION 

of  saliva  excessive.  Erethism  and  apprehensiveness  are  common;  in 
severe  cases  depression  and  melancholia.  A  persistent  and  apparently 
causeless  diarrhea  is  frequently  a  symptom  of  mercurial  poisoning. 

PREVENTION 

The  prevention  of  mercury  poisoning  is  almost  a  direct  counterpart 
of  the  prevention  of  lead  poisoning.  The  air  must  be  kept  free  of  mer- 
cury, and  this  can  be  accomplished  by  proper  systems  of  ventilation,  by 
the  use  of  hoods  with  forced  draft  and  other  devices  to  keep  the  mercury 
fumes  away  from  the  workmen.  Bubber  gloves  may  be  worn  to  prevent 
absorption  through  the  skin  and  also  to  prevent  the  carrying  of  the 
mercury  to  the  mouth.  Here  again  scrupulous  cleanliness  in  and  after 
leaving  the  workroom,  a  change  of  clothing,  and  washing  the  hands 
before  eating  are  essential. 

Other  metallic  poisons  found  in  the  industries  are  antimony;  brass  (an 
alloy  of  copper  and  zinc  with  more  or  less  lead),  chromium,  manganese, 
vanadium,  and  selenium. 

CARBON  MONOXID 

Carbon  monosid  is  a  colorless,  inodorous,  and  highly  poisonous  gas.  ) 
It  burns  with  a  pale  blue  flame.  It  is  one  of  the  products  of  the  incom- 
plete combustion  of  illuminating  gas,  also  of  coal  and  explosives.  It  is 
met  with  in  coal  mines  and  other  subterranean  galleries  where  blasting 
has  been  effected  by  dynamite  and  gun-powder.  It  forms  7  to  10  per 
cent,  of  ordinary  illuminating  gas  (coal  gas)  and  30  per  cent,  of  water 
gas.  It  is  the  source  of  blue  flame  seen  on  the  surface  of  an  ordinary 
coal  fire.  The  gas  is  given  off'  in  quantities  from  coke  ovens ;  it  is  evolved 
from  blasting  furnaces  in  the  smelting  of  iron,  especially  during  the 
charging  of  furnaces  and  their  tapping.  Carbon  monoxid  frequently  -re- 
mains in  the  furnace,  and  workmen  who  enter  such  a  furnace  in  order 
to  clean  it  may  be  overcome.  In  England  the  law  requires  two  workmen 
to  clean  furnaces;  one  stands  by  in  case  of  accident.  Carbon  monoxid  is 
also  evolved  from  hot-water  heaters;  in  the  Leblanc  process  of  soda 
manufacture;  in  cement  and  brick  works,  from  the  use  of  producer  gas 
and  a  fuel  oil.  Carbon  monoxid  is  given  off  in  the  exhaust  gases  from 
motor  cars,  and  is  responsible  for  the  serious  poisoning,  often  fatal, 
which  has  occurred  when  the  engine  of  a  motor  has  been  allowed  to  run 
in  a  closed  garage.  Such  accidents  used  to  be  called  "petromortis"  under 
the  impression  that  the  fumes  came  from  the  gasoline. 

The  poisonous  properties  of  carbon  monoxid  are,  according  to  Hal- 
dane,  due  to  the  great  affinity  it  has  for  the  hemoglobin  of  the  red 
corpuscles.  It  has  from  140  to  250  times  greater  chemical  affinity  for 
hemoglobin  than  oxygen.    It  forms  carbon  monoxid  hemoglobin,  a  more 


DISEASES  OF  OCCUPATIOX  1309 

stable  compouiul  than  oxyhemoglobin,  and  liierei'ore  prevents  the  oxygen 
being  given  to  the  tissues.  When  the  percentage  of  carbon  monoxid  rises 
to  0.4  the  atiHosjjlicre  becomes  dangerous  to  animal  life.  See  page 
941. 

The  inhalation  of  carbon  monoxid  causes  headache  and  a  sense  of 
loss  of  power  in  the  lower  extremities.  It  is  this  circumstance  which 
explains  many  of  the  cases  of  fatal  poisoning  in  confined  spaces.  There 
are  also  dizziness,  throbbing  of  the  temples,  ringing  in  the  ears,  a  sense 
of  lassitude,  and.  in  severe  cases,  convulsions  and  loss  of  consciousness. 
The  inhalation  of  small  quantities  also  leads  to  delusions  and  other  men- 
tal symptoms.  If  the  gas  enters  a  bedroom  and  is  inhaled  by  persons 
Avho  are  asleep  the  sleep  only  becomes  deeper  and  profound  narcosis  is 
developed  from  which  there  may  be  no  awakening.-'^  The  damage  done 
to  the  cells  of  the  brain  and  cord  may  be  permanent,  paralysis  and 
mental  symptoms  persisting  after  recovery  from  the  immediate  effects  of 
the  gassing. 

Oliver  gives  the  following  illustration  of  the  subtle  poisoning  by 
carbon  monoxid  at  Pelton  Fell,  a  mining  village  in  Durham  County. 
Some  shale  which  had  been  tipped  at  the  edge  of  a  ravine  caught  fire. 
The  carbon  monoxid  gas  given  off  during  the  combustion  traveled 
through  the  soil  and  entered  two  houses  in  different  streets,  full  30 
feet  away,  causing  the  death  of  two  elderly  people.  It  is  to  the  breath- 
ing of  this  gas  during  sleep  that  the  death  of  tramps,  drawn  to  the  coke 
ovens  by  their  inviting  warmth  on  a  winter's  night,  is  attributed.  I 
have  already  instanced  the  case  of  death  from  carbon  monoxid  resulting 
from  the  imperfect  operation  of  a  gas  water-heater.     See  page  945. 

HYDROGEN  SULPHID 

Hydrogen  sulphid  is  an  extremely  poisonous  gas  causing  death  in- 
stantaneously if  inhaled  in  large  quantities.  In  smaller  amounts  the 
symptoms  caused  are  nausea,  vertigo,  headache,  general  malaise,  all  of 
which  soon  disappear  if  the  workman  goes  into  the  open  air. 

The  industrial  processes  in  which  hydrogen  sulphid  gas  may  be  en- 
countered are  the  decomposition  of  sulphids  by  acids  in  chemical  works ; 
the  production  of  sulphur  compounds  such  as  sulphur  monochlorid  and 
barium  trisulphid ;  the  making  of  illuminating  gas  and  coke  by-products ; 
the  black  bronzing  of  metals  by  means  of  sulphid  of  arsenic ;  the  clean- 
ing of  boilers;  certain  processes  of  soap  making  where  large  quantities 
of  fat  are  decomposed ;  the  preparation  of  Prussian  blue :  the  decompo- 
sition of  ferrocyanid  of  potassium  by  sulphate  of  iron ;  the  making  of 
sulphuj-  dyes,  especially  khaki. 

In  nature  hydrogen  sulphid  is  one  of  the  products  found  during 

"  See  also  Bureau  of  Mines  Technical  Papers  156  and  106. 


1310    INDUSTEIAL  HYGIENE— DISEASES  OF  OCCUPATION 

the  putrefaction  of  organic  matter  containing  sulphur.  The  gas  may 
therefore  be  found  about  privies,  the  mud  of  marshes,  and  collections 
of  filth  and  manure,  but  in  quantities  too  small  seriously  to  influence 
health.     See  page  947. 

OTHER  INDUSTRIAL  POISONS 

Benzol  or  benzene  is  one  of  the  coal-tar  distillates,  and  is  used  either 
pure  or  as  commercial  benzene,  which  contains  such  impurities  as  xylene 
and  toluene.  Benzene  is  used  as  a  solvent  for  rubber,  also  in  the  pro- 
duction of  rubber,  resin,  iodin,  phosphorus,  sulphur  and  fats;  and  in  the 
dyeing  industry. 

Benzene  enters  the  body  as  a  vapor,  irritates  the  respiratory  tract, 
and  produces  acute  and  chronic  poisoning.  In  acute  poisoning  the  symp- 
toms are  of  respiratory  and  nervous  origin  and  range  from  cough,  ver- 
tigo, tinnitus,  vomiting,  perspiration  and  pruritus,  to  cyanosis,  irregular 
pulse,  anesthesias,  delirium,  convulsion^,  coma  and  death.  In  the  chronic 
form  there  are  purpuric  hemorrhages  from  the  mucous  membranes  of 
the  mouth  and  nose  and  into  the  skin,  fatty  degeneration  of  the  heart, 
kidneys  and  liver,  anemia,  an  extraordinary  leukopenia  and  death. 

Benzene  has  been  taken  as  a  type  of  the  volatile  hydrocarbons,  such 
as  solvent  naphtha,  nitrobenzol,  and  other  coal-tar  derivatives. 

Anilin.— Industrial  poisoning  from  anilin  and  substances  closely 
allied  to  it  is  well  known  in  Germany  and  in  Great  Britain.  It  is  just 
beginning  to  be  known  in  the  United  States,^®  where  it  has  already  been 
the  cause  of  many  cases  of  poisoning  among  men  engaged  in  the  manu- 
facture of  rubber  goods,  in  reclaiming  rubber  from  scrap,  in  making 
anilin  from  benzene,  and  in  using  certain  washes  for  press  rollers.  It 
also  occurs  in  the  dye  industry.  Anilin  causes  the  formation  of  methemo- 
globin,  and  poisoning  usually  takes  place  through  the  skin,  sometimes  the 
lungs.  It  is  commonly  called  "the  blues"  on  account  of  the  cyanosis 
produced. 

Exposure  to  the  fumes  alone  may  cause  poisoning,  especially  in  the 
susceptible,  but  the  most  serious  cases  follow  the  spilling  of  anilin  on 
the  skin,  and  the  first  precaution  to  be  taken  in  all  cases  of  anilin  poi- 
soning is  to  make  the  man  strip  and  take  a  full  bath.  Experience  shows 
that  skin  absorption  is  far  more  important  in  industrial  anilism  than 
the  breathing  of  fumes. 

Early  recognition  of  anilin  poisoning  is  of  prime  importance,  so  that 
the  sufferer  may  be  withdrawn  from  the  danger  of  further  exposure. 
Men  working  constantly  in  anilin  seem  to  acquire  a  certain  amount  of 
tolerance  to  it,  but  chronic  poisoning  may  result  apparently  from  cumu- 

^  Luce  and  Hamilton :  "Industrial  Anilin  Poisoning  in  the  U.  S.,"  J.  A. 
M.  A.,  May  6,  1916,  LXVI,  No.  19,  pp.  1441-1445. 


DISEASES  OF  OCCUPATION  1311 

lative  effect.  After  symptoms  of  poisoniiiu^  have  once  manifested  them- 
selves, the  individual  is  usually  hypersensitive  to  the  fumes. 

Manganese. — Up  to  1913,  this  rare  form  of  industrial  poisoning 
was  not  known  to  exist  in  the  United  States,  but  the  researches  of  Casa- 
major -"  and  of  Edsall  and  Drinker'-^  during  recent  years  have  brought 
to  light  some  39  cases,  while  the  number  reported  from  European  coun- 
tries is  only  15.  The  poisonings  follow  exposure,  usually  for  some 
months,  to  dust  containing  manganese  dioxid.  The  symptoms  were 
likened  by  von  Jaksch  and  Seelert  to  those  of  multiple  sclerosis,  by 
Edsall  and  Drinker  to  progressive  lenticular  degeneration.  The  last 
two  authors  summarized  the  symptoms  in  such  poisoning  as  follows: 
A  history  of  work  in  manganese  dust  for  at  least  three  months;  languor 
and  sleepiness ;  muscular  twitchings,  from  tremors  to  gross  rhythmical 
movements  of  arms  and  legs,  trunk  and  head ;  cramps  and  stiffness  of 
the  calves,  usually  at  night;  slight  increase  in  tendon  reflexes;  ankle 
and  patellar  clonus;  retropulsion  and  propulsion;  peculiar  slapping  gait; 
occasionally  uncontrollable  laughter,  less  often  weeping;  absence  of  sen- 
sory, gastro-intestinal,  eye,  genito-urinary  disturbances;  negative  blood, 
urine  and  spinal  fluid  findings. 

Carbon  Disulphid. — This  is  a  powerful  solvent  for  fats  and  gums 
and  has  long  beeii  used  in  the  rubber  industry  for  so-called  cold  or 
acid  vulcanization.  Sulphur  monochlorid  is  dissolved  in  carbon  disul- 
phid and  the  rubber  is  dipped  in  the  fluid  or  painted  over  with  the 
fluid  or  hung  in  its  vapors.  This  mode  of  vulcanization  is  not  so  gen- 
erally used  in  the  United  States  as  in  European  countries.^^  The  symp- 
toms of  carbon  disulphid  poison  consist  in  excitement  followed  by  depres- 
sion and  apathy.  There  is  an  increasing  weariness  and  loss  of  strength, 
most  marked  in  the  legs,  climbing  stairs  becomes  difficult.  There  is 
usually  drowsiness,  even  mental  confusion,  and  sometimes  severe  head- 
ache and  insomnia.  In  serious  cases  which  come  on  rapidly,  there  is 
acute  mania ;  in  those  that  come  on  more  slowly,  paralysis.  There  may 
also  be  impairment  of  -sight  from  atrophy  of  the  optic  nerve.  Because 
of  its  inflammaljle  character,  carbon  disulphid  is  gradually  being  re- 
placed in  rubber  works  by  the  non-inflammable  and  far  less  toxic  car- 
bon tetrachlorid.  It  is,  however,  coming  into  use  in  a  new  industry,  the 
making  of  artificial  silk. 

Brass. — Brass  is  an  alloy  of  copper  and  zinc,  the  cheaper  varieties 
containing  a  large  proportion  of  zinc  and  from  1  to  13  per-  cent,  of 
lead.  Brass  founders'  ague  has  been  known  for  fully  a  century.  It 
is  an  acute  ague-like  attack,  coming  on  usually  after  exposure  to  the 
fumes  of  molten  brass,  but  not  until  the  man  has  left  the  shop  and 

="J.  A.  M.  A.,  1913,  Vol.  LX,  p.  646. 
^Journ.  Industrial  Hijg.,  1919.  Vol.  I.  p.  183. 
^BuU.  Xo.  179.  r.  .S'.  Bureau  of  Labor  Statistics. 


1312    INDUSTEIAL  HYGIEI^E— DISEASES  OF  OCCUPATION 

gone  into  the  cold  air.  He  suffers  from  a  severe  chill,  weakness,  nau- 
sea, and  then  fever,  sweating  and  prostration,  but  usually  he  is  able  to 
return  to  work  the  next  day  and  hardly  ever  considers  the  attack  serious 
enough  to  send  for  medical  assistance.  It  is  the  zinc  in  the  alloy,  not 
the  copper,  that  causes  sickness,  and  it  is  only  when  volatilized  in  the 
form  of  fumes  and  inhaled  that  the  effect  is  produced.  Brass  polishers 
do  not  suffer  from  "the  shakes,"  and  the  sickness  described  as  brass 
poisoning   in   brass   polishers   is   often,   if   not   always,    lead   poisoning 


Fig.  1.57. — Workmen  Exposed  to  Zinc  Fumes  in  Brass  Casting,  Causing 
A  Condition  Known  as  "Brass-Founder's  Ague." 


from  the  dust  of  cheap  brass  containing  lead.  True  brass  founders'  ague 
occurs  also  in  braziers  who  weld  together  metallic  surfaces  with  the 
aid  of  a  solder  containing  brass;  also  in  zinc  smelters,  and  rarely  in  gal- 
vanizers  working  over  a  hot  zinc  bath,  in  autogenous  welders  working 
with  zinc.  The  brass  industry  is  generally  considered  more  unhealth- 
ful  than  the  average,  for  in  addition  to  brass  fumes  and  lead  dust, 
workers  are  exposed  to  fumes  of  acids,  of  volatile  solvents  for  shellac  and 
lacquer,  and  to  great  heat. 

Wiood  Alcohol. — Industrial  wood  alcohol  poisoning  has  assumed 
great  importance  of  late  years  in  connection  with  the  use  of  shellac, 
varnish,  paint  and  varnish  removers,  the  stiffening  of  felt  hats,  the  mak- 
ing of  celluloid  and  the  making  of  dye  intermediates  and  explosives. 


DISEASES  OF  OCCTTPATION  1313 

III  r.'lT),  Tyson  aii<l  S(  IiocmIxt^- •'"  cstiinatfd  tliat  twD  and  onc-lialf  mil- 
lion workers  in  tlic  I'nitcd  States  arc  exposed  to  wood  aleohol  by  in- 
halation or  contact  in  the  eourse  of  their  work,  and  they  have  discovered 
about  100  industrial  cases.  The  effect  of  wood  alcohol  differs  in  many 
respects  from  that  of  grain  alcohol.  It  acts  more  slowly,  and  is  far  more 
slowly  eliminated.  In  a  typical  case,  the  workman  suffers  for  some 
time  from  attacks  of  dizziness  and  headache  and  weakness,  which  gradu- 
ally increase  in  severity,  then  he  notices  a  dimness  or  foggiuess  l^efore  the 
eyes  whicli  may  suddenly  pass  into  complete  blindness.  This  blindness 
is  due  to  an  optic  neuritis,  followed  by  atrophy  and  the  result  is  par- 
tial or  total  permanent  blindness.  Severer  poisoning  causes  death,  pre- 
ceded l)y  l)linilncss,  convulsions  and  coma.     See  also  page  94. 

A  revenue  bill  passed  in  190G  permits  the  use  in  industry  of  grain 
alcohol  denatured  by  the  addition  of  2  per  cent.,  4  per  cent.,  10  per 
cent.,  or  20  per  cent,  of  wood  alcohol,  and  0.5  per  cent,  of  pyridin 
bases.  This  is  of  course  far  safer  than  pure  wood  alcohol,  but  the  use 
of  the  formulae  containing  the  larger  proportions  of  wood  alcohol  is 
not  unattended  with  risk,  for  some  people  are  decidedly  susceptible  and 
react  to  a  small  cpiantity  of  the  poison. 

Other  toxic  gaseous  vapors  and  fumes  occurring  more  or  less  com- 
monly in  industrial  processes  are:  Acetaldehyd,  acrolein,  ammonia,  amyl 
acetate,  annd  alcohol,  anilin  and  its  oils,  hydrogen  sulphid,  carbon 
monoxid;  carburetted  hydrogen,  chlorin,  diazomethane,  dimethyl  sul- 
phate, dinitrobenzol,  ether,  ethyl  nitrate,  formaldehyd,  hydrocyanic  acid 
and  cyanids,  lydol  and  titron,  methyl  alcohol,  naphtha  and  gasoline, 
nitrobenzol,  nitrous  gases,  phosgene,  phosphorus,  phosphorated  hydro- 
gen, sulphur  and  sulphur  dioxid,  sulphurated  hydrogen,  turpentine  and 
many  others.  Only  a  few  of  these  have  been  discussed  as  examples.  See 
also  poisonous  gases  in  the  atmosphere,  page  9-11. 

DUSTY    TRADES  ^^ 

Dust  is  the  great  enemy  of  the  workman.  Much  ill  health  is  caused 
by  the  inhalation  of  dust,  some  of  which  is  also  injurious  when  ingested 
and  some  of  which  is  irritating  to  the  skin,  eyes,  or  exposed  mucous 
membranes.  Dust  of  all  kinds,  both  organic  and  inorganic,  is  met 
with  in  the  various  industries.  Organic  dust  is  usually  less  irritating 
and  dangerous  than  inorganic  dust,  which  becomes  harmful  particularly 
when  the  particles  are  sharp  and  therefore  irritating.  The  principal 
trades  and  occupations  in  which  excessive  amounts  of  dust  are  found 
are:  all  forms  of  grinding  and  many  processes  of  polishing  and  clean- 
ing; the  textile  industries;  in  the  lead,  copper,  and  iron  trades  irritating 

^"J.  A.  M.  A..  191  i.  Vol.  LXIII,  p.  91.5. 
"See  also  page  931. 


1314   INDUSTRIAL  HYGIENE— DISEASES  OF  OCCUPATION 

and  poisonous  dusts  are  raised;  also  in  pottery  works  and  masonr}^,  and 
in  the  handling  of  leather,  skins,  feathers,  wool,  cotton,  wood,  paper, 
tobacco,  cement,  cutting  diamonds  and  other  precious  stones;  emery, 
glass,  horn,  bone  and  shell,  grain  and  flour,  etc.  The  amount  of  dust 
niay  be  A^ery  great ;  ^'^^  thus  Hesse  found  in  one  cubic  meter  of  air  the 
following  amounts  of  dust  in  the  occupations  named : 

Felt  hat  factory 175  milligrams 

An  old  flour  mill 48 

A  new  flour  mill 4 

Mechanical  knitting 3 

Sculpturing   9 

A  paper  factory 4-25 

Iron  works V2-100 

A  coal  mine 14 

A  living  room   0 

The  kinds  of  dust  vary  greatly  in  their  hygienic  significance.  Some 
are  poisonous,  some  act  as  mechanical  irritants.  The  principal  poison- 
ous dusts  found  in  the  industries  are  lead,  mercury,  arsenic,  manganese, 
and  zinc;  less  often  substances  from  tobacco,  wood,  dyes,  and  chemical 
works.  The  dust  particles  which  act  by  mechanical  irritation  are  espe- 
cially the  hard,  irregular  particles  with  sharp  edges  from  iron,  steel,  and 
other  metals;  from  granite,  basalt,  or  marble;  while  those  from  coal, 
chalk,  and  plaster  of  Paris  are  less  irritating. 

According  to  Sommerfeld  the  following  proportion  of  persons  per 
thousand  in  the  various  dusty  occupations  mentioned  die  of  pulmonary 
tuberculosis :  ^"      . 

Occupation  without  dust  production 2.39 

With  dust  production    5.42 

With  porcelain  dust    14.0 

With  iron  dust    5.55 

With  lead  dust 7.79 

With  stone  dust  34.9 

With  stone  workers 4.3 

With  wood  and  paper  dust    5.96 

With  tobacco  dust   8.47 

Persons  exposed  to  excessive  amounts  of  dust  for  long  periods  of 
time  suffer  from  a  general  condition  known  as  pneuniokomosis ;  when 
due  to  coal  dust  the  condition  is  known  as  anthracosis ;  when  due  to 
stone  dust,  siderosis  or  chalicosis;  when  due  to  vegetable  fibers  such'  as 
cotton,  hyssinosis.  The  dust  may,  in  part,  be  free  in  the  alveoli  of  the 
lungs  and  in  part  is  inclosed  in  the  cells.  The  epithelial  cells  lining  the 
alveoli  act  as  phagocytes.     At  times  some  of  the  alveoli  may  be  plugged 

3ia  Winslow,  C.-E.  A.,  Greenburg,  L.,  and  Greenberg,  D. :  "The  Dust  Hazard 
in  the  Abrasive  Industry."  Rep.  No.  530,  P.  H.  Rpts.,  Mav  30,  1919,  p.  1171;  also, 
Miller,  F,  G.,  and  Smith,  H.  F.:  "The  Dust  Hazard 'in  Certain  Industries," 
Jour.  A.  M.  A.,  Mar.  2,  1918,  Vol.  LXX,  No.  9,  p.  599. 

^F.  L.  Hoffman,  "Mortality  from  Tuberculosis  in  Dusty  Trades,"  Bulls.  19 
and  82,  U.  8.  Bureau  of  Labor. 


DISEASES  OF  OCCUPATIOiV 


1315 


willi  (lust  partick'S.  SoiiK'tinu's  the  dust  remains  in  the  lun<rs  without 
any  ai>f)aiH'nt  read  ion  on  ihe  pai'l  of  tlie  tissues.  I'sually  round  cells 
a])pear  in  liie  interalveolar  spaces,  and  other  indications  of  irritation 
and  inflammatory  reaction  take  place,  leadini,^  to  connective  tissue  forma- 
tion between  the  alveoli  and  thickeninn^  of  the  alveolar  wall  itself.  This 
mav  proirress  to  an  iiidui-ative  bronchitis;  that  is,  several  alveoli  become 
drawn  toflrethcr  bv  the  contractin"-  connective  tissue  into  a  nodule.     Other 


Fig.     158. — An    Effective    Dust-removing    System    in    the    Boot-axd-Shoh 

Industry. 

Edge  trimming.      (Mass.  State  Board  of  Health.) 

forms  of  inflammation,  such  as  nodular  peribronchitis  or  nodular  peri- 
vasculitis, may  take  place.  The  dust  particles  are  also  carried  by  the 
phagocytes  to  the  regional  lymphatics,  where  they  lodge.  These  irrita- 
tive processes  cause  a  low  grade  inflammatory  reaction  which_  only  awaits 
the  coming  of  bacteria  to  start  specific  or  destructive  processes  (page  927) . 
Some  dust  is  especially  irritating  to  the  conjunctiva,  as  wood  dust 
or  arsenic.  Certain  kinds  of  dust  are  prone  to  cause  chronic  catarrhal 
inflammation  of  the  upper  respiratory  passages,  while  dust  containing 
specific  microorganisms  such  as  anthrax  may  lead  to  acute  pneumonia 
(wool-sorter's  pneumonia). 


1316    INDUSTEIAL  HYGIENE— DISEASES  OF  OCCUPATION 

General  Principles  of  Prevention. — Much  of  the  dust  raised  in  indus- 
trial processes  may  be  limited  by  improvements  in  machinery  or  pre- 
ventive devices.  Sometimes  the  dust  may  be  kept  down  by  moisture, 
sprays,  or  even  conducting  the  work  imder  water  when  practicable. 
Certain  dusty  operations  should  be  conducted  in  inclosed  hoods  or 
special  cabinets  so  as  to  confine  the   dust  and   thus  protect  the   work 


Fig.   159. — A  Very  Dusty  Trade. 

Drum  with  nails  which  combs  out  the  small  pieces  of  broom  corn.      (Mass. 
State  Board  o*  Health.) 

people,  or  the  dust  may  be  removed  by  suction  fan  devices.  Good 
ventilation  diminishes  the  danger  very  much.  When  workmen  are 
compelled  to  stay  in  dusty  atmospheres  they  should  wear  respiratory 
masks,  and  the  number  of  persons  thus  exposed  should  be  reduced  to 
a  minimum.  Some  exceedingly  dusty  processes,  such  as  cleaning  cast- 
ings with  a  sand  blast,  demand  the  wearing  of  a  protective  headgear. 
Many  workmen  prefer  taking  chances  to  wearing  uncomfortable  res- 
pirators. For  a  further  discussion  of  dust,  smoke,  etc.,  see  Section 
VI. 

THE  TEXTILE  INDUSTRIES 


The  manufacture  of  cotton,  linens,  silk,  and  jute  has  received  an 
unenviable  reputation  as  a  dangerous  occupation,  despite  the  fact  that 


DISEASES  OE  Orm'ATIOX  1317 

those  iiulustiic's  iicecl  nut  iu  tlienisclves  l)e  parliiiilarly  uiilicalthy  oe-cupa- 
tioiis.  'Ihe  textile  iiulustrics  illustrate  several  points  iu  the  diseases  of 
oecupatioii.  One  is  that  an  entire  industry  shculd  not  he  conilemned 
because  one  of  its  processes  is  attended  ^vith  a  certain  amount  of  danger. 
The  other  is  that  the  risks  to  health  may  be  prevented  or  greatly  ameli- 
orated, rioneral  improvement  in  the  sanitary  conditions  of  textile  mills 
is  one  of  the  promising  signs  of  material  advancement  in  industrial 
hygiene. 

The  principal  conditions  which  affect  health  in  the  textile  industries 
are:  The  working  in  a  dusty  atmosphere  which  is  often  kept  very  moist 
and  usually  very  warm  in  order  to  keep  the  fiber  pliable  and  workable. 
The  humidity  and  temperature  may  be  regulated,  and  by  efficient  systems 
of  ventilation  their  ill  effects  may  be  minimized  or  even  neutralized. 
The  dust  may  also  be  lessened,  and  in  the  processes  in  which  it  is 
excessive  the  workmen  may  protcict  themselves  with  respirators. 

^luch  dust  is  raised  during  the  opening  and  emptying  of  the  bales 
of  the  raw  material.  This  is  avoided  in  the  better  mills  by  the  use  of 
machinery.  Most  dust  is  raised  during  the  process  of  '"carding"' ;  some 
during  "roving."  "spinning"  the  yarn,  and  "winding"'  it :  and  al>o  con- 
siderable during  "weaving."  In  linen  factories  the  "hecklers,"  that 
is,  the  men  who  dress  and  sort  the  rough  flax  (converted  into  tow  by 
having  been  passed  through  a  machine),  are  exposed  to  considerable 
amounts  of  dust  and  suffer  from  dryness  of  the  throat  and  bronchitis, 
attended  by  cough  and  shortness  of  breath.  In  the  manufacture  of  sacks, 
twine,  and  carpets  from  jute  the  processes  that  are  extremely  dusty  are 
the  preparing  and  spinning.     The  dust  given  off  by  jute  is  irritating. 

Humidity  in  Textile  Mills. — Working  in  an  atmosphere  which  is  ex- 
cessively moist  and  frequently  very  warm,  and,  further,  containing  an 
excessive  amount  of  organic  dust,  subjects  the  workmen  to  artificial  and 
unnatural  conditions  which  cannot  be  conducive  to  health.^^  Presumably 
the  heat  and  moisture  predispose  to  rheumatic  states  and  inflammatory 
conditions  of  the  respiratory  tract  which  are  aggravated  by  the  irritation 
of  the  fibrous  dust.  It  is  believed  that  workmen  so  exposed  are  more 
prone  to  contract  common  colds,  bronchitis,  pneumonia,  tuberculosis,  and 
other  inflammatory  diseases  of  the  respiratory  tract. 

The  humidity  of  the  air  is  an  important  factor  in  the  manufacture 
of  textile  fabrics.  The  former  supremacy  of  certain  English  localities 
as  textile  centers  Avas  due  to  the  naturally  favorable  climatic. conditions. 
This  led  to  the  adoption  of  artificial  means  of  increasing  the  moisture 
of  the  air  in  mills  less  favorably  located.  When  the  fihers  contain  a  cer- 
tain proportion  of  moisture  they  are  elastic  and  cling  closely  together, 
and  may  be  carded,  combed,  drawn  out,  and  spun  into  yarn,  and  woven 
into  cloth  more  easily  than  when  dry.     When  the  fiber  is  moist  the  work 

*^  For  eflfect  of  heat  and  humidity  upon  health  see  pages  004  and  064. 


1318    INDUSTRIAL  HYGIENE— DISEASES  OF  OCCUPATION 

in  all  these  processes  runs  better  and  smoother;  finer  grades  of  goods 
may  be  made  from  the  same  stock;  there  is  less  waste,  and  the  machines 
may  be  run  at  higher  speed  with  less  attention  from  the  operators.  Yarn 
spun  from  dry  fiber  is  harsh  and  kinky ;  it  does  not  retain  its  twist  and 
breaks  easily;  furthermore,  there  is  more  dust  and  "fly"  which  menace 
the  health  and  comfort  of  the  work  people. 

The  temperature  and  humidity  most  suitable  for  obtaining  the  best 
results  in  each  process  with  material  of  different  character  and  quality 
have  been  determined  with  considerable  care,  and,  generally  speaking, 
have  been  found  to  be  such  as  would  not  be  prejudicial  to  health.  Despite 
this  knowledge  excessive  moisture  and  high  temperatures  injurious  both 
to  health  and  to  the  processes  of  manufacture  are  found  in  some  mills. 

The  necessary  humidity  in  textile  mills  is  obtained  by  a  number  of 
different  devices.  The  methods  which  depend  upon  the  introduction  of 
moisture  directly  into  the  mill  rooms  are  more  objectionable,  than  the 
humidification  of  the  air  forced  into  the  rooms  by  some  system  of  me- 
chanical ventilation.  In  any  case,  the -water  used  to  moisten  the  air 
should  be  clean  and  free  from  odor  or  objectionable  impurities. 

The  simjjlest  method  of  producing  artificial  humidity  in  mill  rooms 
is  by  sprinkling  water  upon  the  floor  and  trusting  to  natural  evapora- 
tion. This  method,  known  as  "degging,"  was  widely  practiced  at  one 
time,  and  is  still  occasionally  found  in  some  foreign  mills.  Degging  was 
replaced  by  shallow  channels  in  the  floor  for  the  water,  or  by  the  placing 
of  pans  of  water  about  the  room,  and  later  by  introducing  steam  directly 
into  the  room.  Steam  is  objectionable  for  the  reason  that  it  unduly  in- 
creases the  temperature.  The  modern  types  of  humidifying  apparatus 
depend  upon  moistening  the  air  by  passing  it  over  water  surfaces  or 
through  water  curtains.  The  spray  moisteners  are  made  in  a  large 
variety  of  patterns.  Some  are  constructed  on  the  principle  of  the  com- 
mon household  atomizer. 

In  Massachusetts  there  is  a  law  regulating  the  amount  of  humidity 
and  temperature  in  the  textile  mills  which  is  based  upon  the  English 
schedule  contained  in  the  Weaver's  act  of  1870.  The  conditions  in 
Massachusetts,  however,  are  so  different  from  those  found  in  England, 
especially  in  the  summer  time,  that  the  schedule  has  not  been  found 
practical.  Much  of  the  ill  effects  in  the  textile  industries  may  be  neu- 
tralized by  good  ventilation,  abundant  air  space,  cleanliness,  sufficient 
light,  and  the  use  of  improved  machinery.  Special  rooms  should  be 
provided  for  the  clothes,  in  order  that  the  moist  garments  may  be 
changed  for  dry  ones  before  the  work  people  go  into  the  open  air.  thus 
avoiding  the  chilling  effects  of  damp  garments. 


DISEASES  OF  OCCII'ATIOX  1319 

WOOD  Dl'^T 

It  is  well  known  tiiat  workers  in  wood  are  subject  to  tlit-  nieclianical 
effects  of  ordinary  sawdust,  wliith  is  moderately  irritating.  Workers 
with  boxwood,  teak,  and  sequoia  (redwood)  are  subject  also  to  the  gen- 
eral poisonous  eU'ects  of  alkaloids  and  other  substances  contained  in 
these  woods  which  may  have  more  marked  general  effects,  especially  on 
the  circulation  and.  still  more  frequently,  marked  local  effect  on  the 
mucous  meml)ranes  and  the  skin.  In  1002  Young  observed  that  men 
working  with  ^laracaibo  boxwood  complained  of  dryness  of  the  throat 
and  inflammation  of  tlie  eyes  whicli  lasted  two  or  three  days.  This 
wood  is  used  in  the  making  of  rulers.  Oliver  notes  that  joiners  that 
saw  and  chip  sequoia  wood  suffer  with  symptoms  resembling  a  bad  cold 
in  the  head  and  chest;  a  tolerance  seems  to  be  established  except  by 
men  who  are  liable  to  bronchitis  and  asthma.  Woimds  caused  by  splin- 
ters of  the  wood  invariably  suppurate  and  do  not  heal  readily.  Oliver 
found  that  rats  were  also  susceptible  to  sequoia  sawdust.  They  suffer 
from  a  running  at  the  nostrils. 

Certain  kinds  of  wood  have  a  bad  reputation  among  joiners.  Some 
sawdusts  are  more  irritating  than  others,  probably  from  the  large  amount 
of  inorganic  matter  they  contain.  A  West  African  boxwood  from  which 
shuttles  are  made  causes  headache,  coryza,  excessive  secretion  of  tears, 
and  attacks  of  asthma.  These  woods  contain  alkaloids,  glucosids.  and 
other  extractives.  Workers  in  teakwood  occasionally  suffer  from  der- 
matitis. 

MIXING 

Coal  mining  is  one  of  the  dangerous  and  unhealthy  occupations. 
The  dust,  the  unnatural  conditions  under  which  the  miner  is  com- 
pelled to  work  underground,  the  poor  air.  and  sometimes  exposure  to 
poisonous  fumes  all  conspire  to  make  this  occupation  one  attended  with 
unusual  risks.  The  unsatisfactory  methods  for  disposal  of  feces  often 
found  in  mines  favor  the  spread  of  hookworm  and  other  parasites.  To 
this  must  be  added  the  danger  of  accidents  and  explosions. 

The  conditions  of  mines  have  been  greatly  improved,  especially 
through  better  systems  of  ventilation,  through  the  use  of  safety  lamps, 
through  reduction  of  the  amount  of  dust,  the  regulation  of  the  hours 
of  occupation,  and  devices  to  detect  poisonous  and  explosive  gases.  The 
sanitation  and  cleanliness  of  mines  have  also  shown  development.  As 
an  illustration  of  some  of  the  complications  and  difficulties  of  this  sub- 
ject, reference  is  made  to  the  fact  that  moisture  will  prevent  explosion 
in  mines.  ^Moisture  Avas,  therefore,  introduced  into  some  of  the  German 
mines  with  good  results,  so  far  as  explosions  are  concerned,  but  the 
moisture  favored  the  development  of  the  hookworm  larvae  and  hence 


1320    INDUSTEIAL  HYGIENE— DISEASES  OF  OCCUPATION 

caused  such  a  great  increase  in  the  amount  of  hookworm  infection  that 
it  became  necessary  to  seek  other  methods. 

The  mortality  from  accidents  and  diseases  of  the  lungs  is  high.  Coal 
miners'  phthisis,  or  anthracosis,  is  a  well-known  disease.  Although  coal 
is  a  vegetable  product  the  result  largely  of  microbial  action,  fresh  coal 
is  free  from  microorganisms.  Oliver  points  out  that  in  some  of  the  min- 
ing centers  colliers  not  only  suffer  less  from  pulmonary  tuberculosis  than 
persons  in  other  occupations,  but  that  they  also  suffer  unequally  in  dif- 


FiG.   160. — The  Stone  Industry. 
The  workman   is  using  a   surfacing  machine  operated   with   compressed   air. 
The  strong  blast  of  air  keeps  the  granite  clean,  but  gives  rise  to  a  great  amount 
of  dust.     Of  the  mineral  dusts  granite  is  generally  considered  as  most  irritating. 
(Mass.  State  Board  of  Health.) 


ferent  mining  centers.  Why  this  is  so  it  is  difficult  to  say.  While  the 
death  rate  from  pulmonary  tuberculosis  in  miners  is  in  some  places  low, 
that  due  to  non-tuberculous  affections  of  the  lungs  is,  comparatively 
speaking,  high. 

DeCrocq  speaks  of  the  rarity  of  phthisis  among  Belgian  coal  miners. 
Arnold  reports  that  in  Germany  tuberculous  diseases  are  rare  among  coal 
miners  and  that  there  is  a  prevailing  opinion  that  anthracosis  is  antago- 
nistic to  tuberculosis.  Goldman  attributed  the  freedom  of  the  coal  miner 
from  pulmonary  tuberculosis  to  an  antiseptic  action  of  the  coal  dust. 

Other  diseases  to  which  coal  miners  are  sul)ject  are  "beat  hand,"  as  a 
consequence  of  using  the  pick  and  friction  of  the  handle.  The  skin 
of  the  palm  over  the  bases  of  the  fingers  of  both  hands,  also  the  skin 


DISEASES  OF  OCCTJPATTON  1321 

over  the  ik'j^liy  ball  of  the  tliumt)  and  tluil  of  tliL'  otlicr  side  of  the  hand, 
becomes  extremely  hard  and  horny.  In  addition  to  the  enormous  thick- 
ening of  the  epithelial  hiyers  of  the  skin  there  is  inHannnation  of  the  sub- 
cutaneous connective  tissue.  Occasionally  suppuration  takes  place  in  the 
deeper  layers  of  the  hard  skin.  The  suppuratory  areas  are  called  ''keens" 
by  the  miners.  Beat  hand  is  a  painful  aft'ection  and  unfits  the  individual 
for  work  for  some  time.  A  similar  condition  sometimes  occurs  on  the 
knees  and  elbows,  hence  the  term  "beat  knee"  and  "beat  elbow."  Miners 
also  frequently  complain  of  backache,  largely  the  result  of  the  peculiar 
mode  of  sitting  while  at  work.  Dyspepsia,  miner's  nystagmus,  and  anky- 
lostomiasis are  other  conditions  to  which  miners  are  prone. 

Cancer.— Chronic  irritation  produced  by  coal  and  petroleum  products 
acts  as  a  cliemical  irritant  in  the  production  of  cancer,  accounting  for 
chimney  sweep's  cancer  and  the  tendency  to  cancer  among  workers  in 
tar  and  paraffin,  anil  in,  tobacco,  and  soot.  Arsenic  and  other  irritanti; 
are  believed  to  predispose  to  cancerous  growths.     See  pages  385  and  646. 

EFFECTS  OF  HEAT 

In  many  trades  workmen,  more  particularly  firemen,  stokers,  workers 
in  foundries  and  steel  mills,  are  exposed  to  high  degrees  of  heat.  Ed- 
sall  ^*  has  recently  called  attention  to  the  ill  eifects  of  exposure  to  unusual 
degrees  of  heat.  The  symptoms  are  acute,  violent  muscle  spasms.  The 
acute  effect  may  be  heat-stroke  and  heat  prostration;  there  may  be 
nervous  lesions  such  as  focal  meningitis,  as  well  as  more  or  less  serious 
circulatory  weakness,  anemia,  acute  and  chronic  disturbances  of  diges- 
tion, acute  and  chronic  nephritis.  Eespiratory  diseases  and  skin  lesions 
appear  to  be  unduly  frequent  in  persons  exposed  to  high  degrees  of  heat. 
There  is  more  than  a  suspicion  that  cataracts,  retinal  and  choroidal 
changes,  or  chronic  conjunctival  lesions  are  brought  on  in  glass-blowers 
and  perhaps  also  in  iron  puddlers  and  other  persons  whose  eyes  are  ex- 
posed to  very  intense  heat  and  light.  De  Schweinitz  states  that  he  can 
often  tell  whether  men  working  at  puddling  furnaces  are  right-handed 
or  left-handed  by  studying  the  effects  of  this  exposure  on  their  eye 
grounds.  Eopke  ^^  states  that  Quint  described  "to  him  cases  of  right- 
sided  cataract  in  right-handed  iron  workers  and  left-sided  in  those  who 
were  left-handed. 

Unnecessary  Noise. — Unnecessary  noise  may  become  a  nuisance,  and 
under  certain  conditions  is  a  menace  to  health,  especially  high-pitched 
sounds  long-continued,  which  lead  to  deafness ;  hence  the  deafness  of 
boiler  makers  and  others  is  "a  true  occupational  disease.  Siebenmann  and 
others  have  demonstrated  that  long-continued  exposure  to  high-pitched 

^.Tonr.  Amer.  Med.  Assn.,  LI.  Dec.  5,  1908.  p.  1969. 
""Wevl':-.  ■•Handlnieh  der  Arbeiterkrankheiten,"  1908. 


1322    INDUSTEIAL  HYGIENE— DISEASES  OF  OCCUPATION 

sounds  causes  degenerative  changes  in  the  organ  of  Corti  in  the  internal 
ear. 

Noises  also  disturb  rest  and  sleep,  irritate  the  nervous  organism,  and 
induce  unpleasant  results.  The  susceptibility  to  noises  varies  greatly. 
Many  unnecessary  noises  can  be  stopped  in  shop  and  street  with  a  corre- 
sponding saving  of  energy  and  increase  of  efficiency.  It  is  now  realized 
that  unnecessary  noise  represents  misspent  energy,  and  hence  so  much 
avoidable  waste.  Quiet  zones  at  least  should  be  established  around 
schools,  hospitals,  churches,  courts,  lecture  and  music  halls,   etc. 

Lighting  in  Industries. — See  pages  916  and  1342. 

COMMUNICABLE  INFECTIONS 

There  are  several  infections  to  which  workmen  in  certain  industries 
are  specially  subjected.  Of  these  the  best  known  are :  anthraX,  or  wool- 
sorter's  disease  from  hides  and  hair;  and  hookworm  disease,  or  miner's 
anemia,  from  polluted  soil.  Also  glanders  from  horses.  Tuberculosis 
sometimes  results  directly,  but  more  often  indirectly,  from  occupation. 

Wool-sorter's  disease  is  an  infection  with  Bacillus  anfhracis.  The 
spores  cling  to  the  hides  of  animals  that  have  died  from  the  disease 
or  have  been  slaughtered  on  account  of  it.  Spores  also  remain  attached 
to  wool  and  horsehair  and  to  pig's  bristles  used  in  brush-making.  The 
infection  may  be  taken  in  through  the  slightest  scratch  or  any  open 
wound  or  through  inhalation  of  dust  containing  the  spores,  or  may  be 
ingested  in  the  food.  Wool-sorter's  disease  most  often  appears  in  the 
wool-sorting,  wool-combing,  and  spinning  industries,  in  the  manipula- 
tion of  horsehair  for  stuffing  chairs  and  mattresses,  and  the  prepara- 
tion of  bristles  for  brush-making.  Anthrax  has  also  been  met  with  in 
persons  employed  in  tanyards  and  in  warehouses  that  connect  with  docks. 
The  subject  is  fully  discussed  by  Legge  in  his  Milroy  lectures.^" 

The  prevention  of  anthrax  is  first  and  foremost  a  problem  in  animal 
husbandry  which,  in  this  country,  comes  under  the  purview  of  the  Bureau 
of  Animal  Industry.  Animals  having  anthrax  should  be  killed  and  all 
anthrax  carcasses  should  be  buried,  incinerated,  or  tanked  in  such  a 
manner  as  to  destroy  the  infection  and  prevent  its  dissemination.  This 
is  one  of  the  questions  for  international  sanitary  agreement,  for  the  wool 
from  Prussia,  the  hair  and  mohair  from  Asiatic  Turkey,  the  horse- 
hair from  China,  the  bristles  from  Siberia,  and  the  hides  from  India 
may  carry  the  anthrax  spores  from  these  far-off  lands  and  cause  in- 
fection among  our  workmen.  It  is  exceedingly  difficult  to  disinfect  hides 
so  as  to  kill  the  anthrax  spores  without  damaging  the  hides  for  com- 
mercial use.  The  methods  of  disinfecting  hides,  as  well  as  wool,  bristles, 
hair,  etc.,  are  discussed  on  page  403. 

^^  Lancet,  March  IS,  1905. 


DISEASES  OF  OCCUPATIOX  1323 

Glanders. — See  page  396. 

Hookworm  Disease. — ^Finors  are  specially  siibjeft  to  hookworm  dis- 
ease. 'I'lu'  ]);irnsil('  enters  tlirough  tlie  skin  from  the  polluted  soil  of 
the  mines.  The  outhreak  which  called  attention  to  this  danger  was 
the  e])idemic  wliicli  occurred  among  the  workmen  on  St.  Oothard's 
tunnel  in  1802,  Since  then  the  disease  has  been  called  "miner's  ane- 
mia." (Junn  •■'•'  found  that  from  50  to  SO  per  cent,  of  those  working  in 
the  mines  of  California  and  the  neiglihoring  state  of  Xevada  were  in- 
fected with  hookworms.  For  a  full  discussion  of  hookworm  disease  see 
page  153. 

Mouse  Favus. — blouse  favus,  or  Favus  herpeiicus,  in  man  has  re- 
cently assumed  significance  in  the  United  States  because  of  the  pos- 
sibility of  those  who  handle  Australian  wheat,  or  who  are  engaged  in 
milling  it^  may  become  infected  from  the  bags,  dead  mice,  or  possibly 
from  the  wheat  itself.  Men  employed  in  resacking  the  grain  and  women 
employed  in  mending  the  torn  and  gnawed  bags  have  developed  many 
cases  of  favus  of  the  glabrous  skin.  This  is  the  Favus  lierpeiicus  of 
Quincke,  caused  by  the  dermatophyte  Aclior'wn  quincl-eniuin,  wdiich  is 
quite  distinct  from  the  typical  human  favus  due  to  the  Acliorion  Schoen- 
leinii. The  disease  in  man  develops  clinically  much  as  herpes  tonsurans. 
The  infection  is  usually  not  serious,  yielding  readily  to  treatment,  and 
is  far  more  readily  cured  than  favus  vulgaris  of  the  scalp. 

Tuberculosis. — Tuberculosis  is  often  spoken  of  as  the  most  important 
disease  of  occupation.  There  is  no  doubt  that  it  is  the  niost  important 
single  problem  in  industrial  hygiene,  but  whether  it  is  commonly  con- 
tracted as  a  result  of  occupation  is  a  question.  It  is  certain  that  dusty 
trades,  poorly  ventilated  workrooms,  sedentary  occupation,  fatigue,  irri- 
tating fumes,  long  hours  and  the  grind  of  routine,  as  w^ell  as  other  fac- 
tors found  in  industries,  predispose  to  the  disease. 

The  view  generally  accepted  now  is  that  the  infection  is  usually  con- 
tracted in  infancy  or  early  childhood,  but  manifests  itself  clinically  later 
in  life.  The  problem  of  tuberculosis  is  intimately  bound  up  with  per- 
sonal habits  and  home  life.  Therefore,  it  is  quite  as  proper  to  consider 
it  a  house  disease  as  an  occupational  disease.  Bad  sanitary  and  hygienic 
conditions  light  up  latent  infections,  and  it  is  hopeless  to  expect  arrest 
or  cure  of  the  process  so  long  as  the  victim  continues  to  work  under 
unfavorable  conditions.  The  problem  of  what  to  do  for  the  tuberculous 
workman  and  his  family,  with  the  "cured"  and  arrested  cases,  as  well 
as  to  find  suitable  occupation  for  the  pretubercular  types,  is  often  a  diffi- 
cult puzzle  for  the  social  worker. 

Statistics  plainly  show  that  tuberculosis,  as  well  as  bronchitis,  em- 
pyema, and  other  diseases  of  the  respiratory  tract,  is  unusually  prevalent 
among  grinders,  engravers,  compositors,  stone  workers,  millers,  bakers, 

"J.  A.  M.  A.,  Jan.  28,  1911,  Vol.  LYl,  Xo.  4,  p.  259. 


1324   IXDUSTEIAL  HYGIENE— DISEASES  OF  OCCUPATION 

plasterers,  brass  workers,  glass  cutters,  furriers,  weavers,  and  other  trades 
in  which  there  is  undue  exposure  to  dust  and  irritating  vapors. 
The  subject  of  tuberculosis  is  discussed  in  full  on  page  163. 
■  Other  occupations  in  which  there  is  a  special  exposure  to  the  risk 
of  various  infections  are:  physicians,  nurses,  ward-tenders,  pathologists, 
experimental  investigators,  etc. 

THE  CAISSON  DISEASE 

The  effects  of  compressed  air  and  the  effects  of  rarefied  air  are  dis- 
cussed on  pages  887  and  890. 

REFERENCES 

Oliver,  Thomas  :  "Diseases  of  Occupation,  from  the  Legislative,  Social, 
and  Medical  Points  of  View."     New  York,  1909. 

Weyl,  Theodor:  "Handbuch  der  Hygiene."  Gewerbehyg.,  Vol.  VIII, 
Jena,  1897. 

Various  authors :  "Risks  in  Modern  Industry."  Published  by  the  Ameri- 
can Academy  of  Political  and  Social  Science,  Phila.,  Pa.,  1912. 

GoLDMARK,  Josephine,  and  Brandeis,  L.  D.  :  "Fatigue  and  Efficiency." 
Charities  Publication  Committee,  105  E.  22d  St.,  New  York,  1912. 

Rambousek,  J. :  "Industrial  Poisoning."  Longmans,  Green  and  Co.,  New 
York,  1913. 

KoBER,  G.  M;,  and  Haxsox,  W.  C.  :  "Diseases  of  Occupation  and  Voca- 
tional Hygiene."    P.  Blakiston's  Son  and  Co.,  Philadelphia,  1916. 

Bulletins  of  the  U.  S.  Bureau  of  Mines  and  the  H.  S.  Labor  Bureau. 

Thompson,  W.  G.  :  "The  Occupational  Diseases."  D.  Appleton  &  Co., 
1914. 

Price,  G.  M.  :     "The  Modern  Factory."     1914. 

Legge  and  Goodby  :  "Lead  Poisoning  and  Lead  Absorption."  London, 
1912. 

Glaister  and  Logan  :  "Gas  Poisoning  in  Mines  and  Other  Industries." 
Journal  of  Industrial  Hygiene,  Harvard  University  Press,  Cambridge, 
Mass. 

"Occupational  Hazards  and  Diagnostic  Signs" — a  guide  for  Medical  Ex- 
aminers published  by  the  Metropolitan  Life  Insurance  Company,  1918. 


SECT  1  ox  XIII 
SCHOOL  SAXITATIOX  AXI)  I'ERSOXAL  HYGIENE 

It  took  a  long  time  to  realize  that  the  whole  child  goes  to  school — 
his  body,  mind,  and  soul :  that  education  of  the  mind  alone  is  one- 
sided and  may  be  hurtful ;  finally,  that  the  hygiene  of  the  child  and  his 
teacher,  as  well  as  the  sanitation  of  school  buildings  and  their  equip- 
ment, is  of  fundamental  importance.  The  combination  of  compulsory 
education  and  schools  having  an  unbalanced  curriculum  or  impure 
water  or  vitiated  air  or  improper  sanitation,  is  nothing  short  of  a  crime 
by  the  state  against  the  state.  The  child  profits  directly  from  attendance 
upon  a  school  which  has  due  regard  for  the  child's  physical  well  being 
and  the  development  of  his  character;  the  state  profits  indirectly  from 
the  lessons  in  sanitation  and  h3'giene  which  are  carried  into  the  child's 
home,  and  are  applied  as  a  matter  of  course  in  the  home  of  the  future 
citizen.  Thus  the  principles  of  personal  hygiene  and  sanitation  become 
second  nature,  and  in  this  way  the  conquest  of  the  preventable  diseases 
may  be  materially  hastened.  It  is  an  economic  waste  to  educate  children 
and  then  permit  them  to  die  of  some  preventable  infection  before  they 
have  reached  the  period  of  maturity  and  productivity. 

The  schooj  furnishes  abundajit  material  for  the  physiologist  and  the 
psychologist  to  study  growth  and  development.  The  effect  of  the  nature 
and  order  of  the  studies  for  each  school  year;  the  hours  of  work,  rest, 
and  play;  the  direction  of  physical  exercise  should  all  be  regulated  ac- 
cording to  the  average  requirements  and  capacities  of  each  school  period, 
and  should  be  based  upon  accurate  observations  extending  over  long 
periods  of  time.  Both  the  immediate  effects  and  the  remote  influences 
upon  adult  life  should  be  taken  into  consideration.  Youth  is  the  time 
of  unrest  and  activity,  and  it  is  part  of  the  school  work  to  direct  these 
energies  so  as  to  obtain  the  best  development ;  youth  also  requires  gener- 
ous nourishment  and  sufficient  sleep.  A  child  who  comes  to  school  tired 
and  worn  from  disturbed  slumber  cannot  profit  in  body  or  mind.  The 
child  who  comes  to  school  hungry  or  who  does  not  have  a  judicious  lunch- 
eon at  the  recess  period  is  seriously  handicapped  physically  and  mentally. 
The  quality  of  the  food  offered  for  sale  at  recess  should  be  under  close 
scrutiny.  The  hot  lunches  and  nutritious  food  furnished  some  of  the 
school  children  in  Boston,  Xew  York  and  other  cities  at  a  reasonable 
price  is  a  practical  and  wise  movement.     See  pages  674-676. 

1325 


1326    SCHOOL  SANITATION  AND  PERSONAL  HYGIENE 

One  of  the  duties  of  the  school  is  to  teach  and  to  require  at  all 
times  cleanliness  of  person  and  clothing.  The  example  of  clean  school- 
rooms, corridors,  lockers,  toilets,  basement,  and  grounds  will,  in  time, 
influence  the  young  citizen.  Floors  especially  should  be  kept  clean  and 
the  child  be  required  to  use  the  door  mats  before  entering  the  building. 
Dust  must  be  discouraged  in  all  ways.  In  some  schools  in  poor  districts 
it  is  a  good  plan  to  have  shower  baths  for  those  pupils  who  do  not 
enjoy  good  bathing  facilities  at  home.  A  toothbrush  drill  is  the  means 
of  teaching  many  a  child  the  first  principles  in  dental  prophylaxis.  The. 
teacher  should  be  constantly  on  the  lookout  to  impress  upon  the  pupils 
the  elementary  facts  in  hygiene,  such  as  turning  aside  the  head  and 
holding  the  handkerchief  before  the  mouth  and  nose  when  coughing  or 
sneezing.  The  teacher  should  discourage  the  habit  children  have  of 
carrying  their  fingers  to  their  mouths  and  noses.  The  anti-spitting  rules 
should  be  reiterated  and  strictly  enforced.  The  danger  of  mouthing 
toys  and  pencils  and  the  habit  generally  of  placing  things  in  the  mouth 
should  be  discouraged ;  "swapping"  partl;f  eaten  articles  of  food  should 
be  prohibited,  and  the  reasons  explained.  Cleanliness  is  not  instinctive 
in  children;  it  must  be  learned.  The  significance  of  modern  biological 
cleanliness  can  come  only  through  education  and  example.  Progress 
in  these  matters  cannot  be  made  without  an  intelligent  understanding 
on  the  part  of  the  teacher.  It  is  therefore  important  to  teach  the 
teacher. 

Eatigue,  prolonged  and  oft  repeated,  may  injure  the  development 
and  health  of  the  child.  Fatigue  is  favored  by  poor  ventilation,  com- 
pulsory sitting  upon  hard  and  ill  fitting  seats  at  improperly  constructed 
desks,  prolonged  tension  of  a  strict  discipline,  studies  that  are  too  in- 
tensive, and  insufficient  relaxation  or  inconsiderate  treatment  of  the 
little  ones.  Discipline,  obedience,  and  regard  for  the  human  rights  of 
others  are  among  the  most  important  things  learned  at  school. 

Many  a  child  is  unjustly  disciplined  and  his  little  soul  harassed 
through  no  fault  of  his  own,  but  perhaps  on  account  of  defective  eye- 
sight or  hearing,  or  some  other  physical  handicap,  or  as  a  result  of 
mental  deficiency,  or  even  an  unusual  mental  proficiency. 

The  question  of  home  work  should  be  carefully  regulated  in  accord- 
ance with  the  capacity  and  age  of  the  child.  Children  should  not  be 
kept  busy  at  prescribed  work  most  of  the  hours  of  the  day.  Some  time 
should  be  left  for  quiet  play  and  the  encouragement  of  personal  inclina- 
tions during  which  time  the  best  development  unconsciously  occurs. 
Initiative,  self-reliance,  and  self-help  are  submerged  by  lack  of  free  time. 
The  amount  and  nature  of  the  work,  both  in  and  out  of  school,  must  be 
judiciously  considered  and  should  be  based  upon  long  years  of  careful 
study  and  observation.  The  immediate  as  well  as  the  remote  effects 
should  be  taken  into  consideration.    Many  an  ill-tempered  child  is  simply 


SCHOOL  SANITATION   AND   I'KRSONAL  HYGIENE     1327 

t)vor\vroii^iili(  and  I'hroiiii'ally  lired  out  lliroiiiili  cxccssiNc  ii|>iili(;it  ion  of  a 
conscientious  and  studious  nature  to  tasks  licyoiid  tlic  |)liysiolo<^ical  ca- 
])aeity  of  his  little  brain   and   l)ody. 

'riu>  child  should  not  he  sent  to  school  too  youn^^  Cliildrcii  nnist 
iirst  learn  to  walk,  iiin,  talk,  and  coordinate  muscles  hefore  they  under- 
take readinii\  \\iilin,<:\  and  arithmetic.  Children  should  rarely  he  per- 
mitted to  start  scliool  life  until  they  have  passed  their  sixth  hirlhday. 
Few  are  sutliciently  develojied  or  sturdy  en()U<;h  properly  to  endure,  either 
mentally  or  ]ihysically,  the  discipline  and  exactions  of  application  and 
study  hefore  that  age. 

l\ipils  should  not  he  "graded  accordinfx  to  their  af^es,  hut  according 
to  their  ca[)acity  and  physical  development.  Individual  aptitudes  should 
be  encouraged.  The  work  should  be  as  individual  as  practicable,  and 
special  classes  made  of  backward  as  well  as  of  forward  minds.  Special 
facilities  should  be  afforded  for  the  progress  through  school  of  those 
showing  unusual  ability. 

For  the  elementary  schools  one  short  morning  session  is  enough,  but 
city  circumstances  often  demand  two  sessions.  The  general  tendency  is 
to  reduce  the  hours  of  compulsory  school  attendance  and  increase  the 
optional  time  through  elective  systems  which  encourage  and  foster  native 
talents. 

Primary  pupils  should  not  spend  more  than  one-third  of  their  school 
time  in  their  seats.  Exercises  of  various  kinds  that  call  into  play  mus- 
cular activity  are  most  important  at  this  age,  not  only  for  mental 
growth,  but  for  physical  growth,  as  well  as  for  relief  from  the  fatigue 
occasioned  by  sitting  at  desks. 

The  child  on  beginning  school  life  enters  an  environment  radically 
different  from  the  free  and  active  life  which  was  his  before  school  days 
began.  The  effect  may  be  seen  by  the  fact  that  children  usually  lose 
weight  and  the  nervous  system  becomes  affected  during  the  first  weeks 
of  school. 

The  rural  school  is  a  problem  of  magnitude,  for  60.7  per  cent,  of 
the  children  of  the  country  are  in  hamlets  and  towns  of  2,500  and 
less.  Only  18.3  per  cent,  live  in  cities  of  100,000  and  over.  The  dif- 
ficulties of  the  "little  red  schoolhouse"  require  special  considera- 
tion. 

Ungraded  or  special  schools  should  be  provided  for  backward  and 
defective  children  (page  134:9)  and  for  those  having  f a vus,. ringworm, 
rachitis,  or  other  conditions  requiring  either  special  pedagogical  methods 
or  particular  metlical  treatment.  Open-air  or  fresh-air  schools  for  chil- 
dren who  have  or  are  threatened  with  tuberculosis  serve  a  very  useful 
purpose.  Ungraded  schools  for  backward  and  defective  children  should 
emphasize  vocational  training.  These  children  present  a  serious  probleni 
for  society.     See  page  G08. 


1328    SCHOOL  SANITATION  AND  PEESONAL  HYGIENE 

College  life  is  beset  with  the  problems  of  adolescence — Venus,  Bac- 
chus and  Mars.  The  dangers  of  this  age  are  the  venereal  peril,  tuber- 
culosis, intemperance  and  drug  addiction.  The  sudden  freedom  of 
university  life  after  the  strict  restrainments  of  preparatory  schools  is 
sometimes  more  than  youth  is  able  to  withstand. 

Finally,  the  whole  school  program  should  demonstrate  that  the  object 
is  not  to  teach  the  child  to  be  a  child,  but  to  direct  his  development  so 
as  to  become  a  useful  man  or  woman.  The  school  system  should  there- 
fore be  carried  out  with  due  regard  for  future  events  and  should  be 
correlated  with  the  adult  life  of  the  child. 

Health  Education. — Health  education  is  fundamental  and  should  be 
included  as  part  of  the  required  work  of  all  grades.  It  is  comparatively 
easy  to  teach  and  influence  children,  very  difficult  to  change  the  habits 
of  adults.  All  children  should  learn  something  about  the  structure  and 
functions  of  the  body  in  addition  to  the  principles  of  hygiene  and  sani- 
tation. The  program  of  health  should  make  the  teaching  of  health  and 
the  prevention  of  disease  an  essential  part  of  the  education  in  all  schools. 
It  should  furthermore  seek  to  improve  health  and  efficiency  by  practic- 
ing the  art  of  hygienic  living.  It  requires  constant  instruction  by  ex- 
ample on  the  part  of  the  teacher  in  personal  hygienic  habits  and  cleanli- 
ness. It  is  necessary  to  teach  the  teacher  in  order  that  children  may 
receive  sound  instruction.  Teachers,  nurses,  parents  and  the  children 
themselves  need  education  concerning  adequate  nutrition  and  especially 
the  importance  of  rest  and  the  evil  of  chronic  fatigue  for  growing  chil- 
dren. The  program  for  health  education  should  cooperate  with  medical 
school  inspection.  Defects  which  interfere  with  growth  or  otherwise 
handicap  children  should  be  removed  or  corrected. 

The  best  methods  are  simple  and  direct.  A  graded  series  of  text- 
books should  be  used.  Interest  may  be  aroused  by  the  picture  man,  the 
health  fairy,  attractive  literature,  group  competition,  classroom  drills, 
and  above  all  by  the  example  of  the  teacher  in  health  habits.  In  this 
way  advantage  is  taken  of  the  imitative  tendency  of  children — good 
example  is  contagious.  _ 

School  Building. — The  school  must  be  centrally  located,  so  as  to  be 
convenient  especially  for  the  primary  and  grammar  grades,  and  the 
school  building  should  be  modern,  artistic,  clean,  and  sanitary  in  all  its 
appointments.  Every  school  building  should  have  playgrounds  con- 
nected with  it.  Playgrounds  should  be  level  and  located  on  the  sunny 
side  of  buildings;  about  30  square  feet  for  each  pupil  is  necessary  to 
meet  the  demands  of  play.  Thus  1,000  pupils  require  300  x.lOO  square 
feet  for  playgrounds  alone.  In  cities,  roofs  may  be  utilized  for  play. 
A  limited  play  area  is  best  utilized  by  organizing  recess  play  by  sex  and 
grades.  School-houses  should  be  built  in  places  that  are  quiet  and 
free  from  traffic  and  nuisances,  dangers  of  various  kinds,  and  on  ground 


SCHOOL  SANITATION'  AND  PERSONAL  HYGIENE      i;{v*9 

that  is  either  iiaturallv  drv  or  made  so  by  sul)s<til  draiiianc.  The  l)uild- 
ing  should  1)0  solidly  constructed  and  should  stand  apart,  so  that  sun 
and  air  may  reach  it  from  all  sides.  A  substantial  and  artistic  structure 
well  |ilace<l  has  an  iiii|ini-laiit  iiilluciicc  u])(iii  ihc  vouul;'  mind  and 
character.  Trees  and  judicious  landscape  gardeninji:  should  ])rovide  shel- 
ter and  shade  and  add  to  the  attractiveness.  The  foliage,  however,  must 
not  interfere  with  the  light  -and  ventilation  of  the  school-rooms.  If  the 
building  faces  north,  with  corridors  and  stairs  on  this  side,  all  the  rooms 
Avill  have  sunlight  at  some  time  during  the  day.  The  best  general  ar- 
rangement of  the  plan  of  the  ])uilding  is  that  in  which  the  school-rooms 
are  all  placed  on  one  side  of  the  Ijuilding,  with  the  corridors,  halls,  stair- 
ways, and  wardrobes  on  the  other.  Built  in  the  old  way,  with  rooms 
around  a  central  well,  school-houses  have  dark  central  halls  and  stair- 
cases, and  favorable  lighting  cannot  be  had  in  some  of  the  school- 
rooms. 

The  basement  should  be  under  the  whole  building  and  carefully  pro- 
tected against  dampness.  Further,  the  basement  should  be  well  lighted, 
sunny,  and  kept  clean. 

School  buildings  should  have  at  least  two  entrances,  with  doors 
opening  outward;  the  halls  and  corridors  should  be  generous  and  well 
lighted,  and  the  stairs  have  easy  risers  and  treads  for  children.  The 
risers  should  be  about  6  inches  and  the  treads  no  greater  than  12  inches. 
Inclines  may  be  substituted  for  stairs. 

The  School-room. — The  school-room  is  the  unit  in  planning  a  school 
building;  that  is,  the  building  should  be  a  number  of  school-rooms 
properly  disposed,  and  not  a  building  cut  into  school-rooms  whose  size 
and  arrangements  are  dependent  upon  the  size  and  shape  of  the  build- 
ing. 

Some  of  the  important  considerations  in  the  school-room  are  the 
number  of  pupils  to  be  accommodated,  its  size  and  shape,  the  amount 
and  direction  of  the  light,  the  ventilation  and  heating.  The  three 
special  requisites  necessary  in  all  school-rooms  are :  adequate  air  and 
li^gliting,  proper  seating  facilities,  and  suitable  books. 

The  minimum  floor  space  for  each  pupil  should  be  15  square  feet. 
If  18  square  feet  arc  alloAved  all  exercises  are  made  easier  both  for 
pupil  and  teacher.  Two  hundred  cubic  feet  of  air  space  is  the  minimum 
commonly  allowed;  therefore  a  standard  school-room  designed  to  accom- 
modate 30  pupils  should  be  20  feet  wide  by  24  feet  long,  with  a  ceiling 
13  feet  high.  The  best  shape  for  a  sclx)ol-room  is  that  of  an  oblong, 
the  width  being  to  the  length  about  as  3  to  -4.  vNo  teacher  should  be  re- 
quired to  have  classes  exceeding  30  pupils.  The  rcjoms,  floor  space,  and 
air  space  should  be  at  least  as  capacious  for  the  primary  as  for  the  gram- 
mar a-rades. 


1330    SCHOOL  SANITATION  AND  PERSONAL  HYGIENE 

BOSTON  STANDARD ELEMENTARY  GRADES 

Size:     20  ft.  by  28  ft.  elementary  grades. 

20  ft.  by  30  ft.  for  upper  elementary  grades. 
12  ft.  high  in  clear. 

About  ten  or  twenty  per  cent,  of  rooms  should  be  of  a  size  to  seat 
50  pupils. 

KINDERGARTEN 

800  to  900  sq.  ft.  and  capable  of  having  a  circle  16  feet  in  diameter 
painted  on  floor  with  at  least  4  ft.  all  around  it. 

HIGH  SCHOOL 

36  ft.  by  32  ft.  for  42  pupils. 
33  ft.  8  in.  by  43  ft.  for  60  to  80  pupils. 
16  ft.  by  26  ft.  for  recitation  rooms. 

3,750  to  4,000  sq.  ft.  with  a  height  of  not  less  than  24  ft.  for  high 
school  gymnasium. 

The  color  of  the  walls  should  be  such  as  to  absorb  the  least  light  and 
prove  least  taxing  to  the  eyes.  A  light  green-gray  is  favored  for  the 
walls,  and  white  or  cream  for  ceilings.  The  surface  should  not  be  glossy 
and  should  either  be  coated  with  an  oil  paint,  so  that  the  walls  may  be 
washed,  or,  better,  calcimined  with  a  water  paint  that  may  be  readily 
renewed.     The  ceiling  should  be  white,  so  as  to  reflect  the  light. 

The  School  Furniture. — The  most  important  articles  of  school  furni- 
ture, considered  from  the  view  of  hygiene,  are  desks  and  desk  chairs, 
for  the  reason  that  the  pupil  spends  during  school  hours  so  much  time  at 
work  at  his  desk.  Unless,  therefore,  desks  and  chairs  are  constructed 
with  full  regard  for  certain  well-known  laws  of  hygiene  they  produce 
defects  of  eyesight,  injurious  effects  as  to  posture,  and  wrong  habits  of 
carriage  which  are  borne  through  life  and,  sadly  enough,  become  more 
pronounced  a«  the  years  increase.^ 

Professor  Bowditch  ^  of  Harvard  University  carefully  measured  and 
weighed  25,000  school  boys  and  girls  of  Boston  and  found  surprising 
variations.  Taking  ages  on  their  last  birthdays  Professor  Bowditch  found 
the  variations  in  height  indicated  in  the  table  on  the  following  page. 

Besides  the  variations  in  height  there  is  also  variation  in  growth,  and 
provision  for  this  difference  must  therefore  be  made  in  the  construction 
and  adjustment  of  the  desk  and  seat.  The  growth  of  girls  is  more 
rapid  from  12  to  14  years  of  age,  while  boys  grow  most  rapidly  from 
14  to  16  years  of  age.     The  annual  growth  during  the  maximum  period 

'  Shaw,  Edward  R. :     "School  Hygiene."    The  Macmillan  Co.,  N.  Y.,  1902. 
^Twenty-second    Annual    Report,    State    Board    of    Health    of    Mass.,    1890, 
pp.  479-522. 


SniOOL  S.WnWTlON  .\\D  personal  TTYniENE     1331 


Variations  in  Height  of  Boys  and  Girls 


Boys 

Girls 

6  years  of  age 

47.13* 
40.66 

47  36 

40.57 

Diflference •. 

6.47 

6.79 

11  years  of  age 

57.50 
40.47 

57.06 

40.33 

l^iflVrcnce 

8.03 

8.63 

15  years  of  age     

67.00 
56.55 

65.00 

57.30 

Diflference 

11.35 

7.61 

*  All  figures  are  inches. 


is  often  an  inch  more  than  the  annual  growth  at  other  periods.  Fur- 
ther, there  exist  certain  anatomical  differences  of  proportion  between 
boys  and  girls.  The  sitting  height  of  girls  is  greater  proportionately 
than  their  standing  height  in  comparison  witlj  'boys. 

The  Desk  and  Seat. — The  desk  and  seat  must  therefore  be  adjusted 
so  as  to  provide  for  differences  of  height  and  differences  of  growth. 
The  desk  must  not  be  a  prison  stall,  but  should  be  comfortable  and 
roomy.  It  must  not  favor  the  development  of  myopia  and  must  not 
force  a  pupil  into  wrong  postures.  The  matter  is  of  greater  importance 
than  school  men  generally  recognize. 

The  chair  and  seat  should  be  of  such  a-  height  that  the  thigh  of  the 
pupil  when  seated  will  be  perfectly  level,  the  lower  leg  being  in  an 
exactly  vertical  position,  with  the  foot  resting  wholly  upon  the  floor; 
that  is,  the  thigh  and  the  lower  leg  will,  when  the  chair  is  of  a  proper 
lieight,  form  a  right  angle  with  each  other.  The  seat  must  therefore 
be  adjusted  accordingly.  The  seat  itself  should  not  be  flat,  but  somewhat 
concave,  the  lowest  part  of  the  concavity  being  where  the  tuberosities 
of  the  ischium  rest.  The  concavity  has  the  additional  advantage  of 
counteracting  the  tendency  to  slide  forward  on  the  seat  when  the 
pupil  leans  back.  The  seat  should  have  a  back  rest  that  will  support 
the  small  of  the  back  properly  without  leaning  1)ack  excessively.  Whether 
or  not  it  supports  the  rest  of  the  back  is  of  small  consequence.  Support 
of  the  back  carried  to  the  level  of  the  shoulder  blades  is  likely  to  do 
more  harm  than  good. 

The  distance  between  the  seat  and  the  desk  should  be  such  that  the 
scholar  may  read  at  the  desk  and  write  on  it  without  leaning  forward 
more  than  a  little  and  without  entirely  losing  the  support  of  the  back 
rest.  The  desk  should  not  be  so  close  as  to  press  against  the  abdomen, 
nor  near  cnousjh   to   interfere  with   easv^  rising  from   the   scat.      This 


1332    SCHOOL  SANITATION  AND  PEESONAL  HYGIENE 

means  a  distance  of  lOVo  to  14i/o  inches  from  the  edge  of  the  desk  to 
the  seat  back.  It  also  means  that  the  seat  must  not  project  under  the 
desk  more  than  an  inch  at  most.  The  desk  should  be  high  enough  for 
the  arm  to  rest  comfortably  without  much  resting  on  the  elbow;  not, 
however,  so  low  that  the  pupil  must  bend  down  to  write  on  it. 

If  the  desk  top  is  made  to  slide  backward  and  forward  it  will  give 
the  pupil  more  freedom  of  movement  while  at  the  desk  and  will  also  per- 
mit him  to  sit  down  at  the  desk  and  rise  from  it  Avith  greater  ease. 


Fig.    161. — Faulti-   Posture.      (Shaw's   "School   H^'giene,"   Macmillan   Co.) 

One  of  the  important  considerations  of  a  school  desk  is  the  proper  slope 
of  the  top.  It  is  well  known  that  the  line  of  light  which  least  taxes 
the  eyes  should  fall  upon  the  printed  page  perpendicularly  to  its  plane. 
To  accomplish  this  some  writers  recommend  a  slope  of  45°  for  the  desk 
top,  others  30°.  These  angles,  however,  are  not  practicable.  The  Vienna 
Expert  School  Desk  Commission  recommends  an  angle  of  15°  for  the 
desk  top,  which  is  also  approved  by  the  experiments  of  Shaw.  Such 
a  slope  permits  a  correct  posture  in  vertical  writing. 

A  foot  rest  is  sometimes  attached  to  desks.  The  weight  of  opinion 
is  now  against  foot  rests,  as  they  restrict  the  free  movement  of  the 
pupil's  feet  while  at  the  desk  ar.d  interfere  with  opportunity  to  shift 
his  feet  and  legs  for  relief  from  inactivity,  and  further  interfere  with 


SCHOOL  SANITATION  AND  PEKSOXAL  IIYCIHNK      i;3;):J 

the  thorough  cleansing  of  the  floor  under  the  desk.  Shaw  recommends 
the  Heusinger  desk,  Fig.  102,  and  also  the  Ideal  desk.  The  desk  and 
seat  shown  in  the  accompanying  photograph,  Fig.  1()3,  are  known  as 
the  Boston  school  desk  and  chair.  There  are  now  many  thousands  in 
use  in  the  Boston  schools,  and  they  arc  being  adopted  elsewhere. 


Fig.   162. — The  Heusixgee  Desk.      (Shaw's  "School  Hygiene,"  Macmillan  Co.) 

The  seat  and  chair  should  be  adjusted  for  each  pupil  when  he  enters 
school  or  is  transferred  to  another  room.  Desks  and  seats  should  be 
adjusted  at  least  twice  a  year :  at  the  opening  of  school  in  September 
and  again  in  February  or  March. 

The  Blackboard. — The  blackboard  should  be  placed  upon  the  wall 
opposite  the  principal  light.  The  board  should  not  have  a  shiny,  reflect- 
ing surface,  and  should  never  be  placed  between  windows  or  near  them. 

The  best  blackboards  are  made  of  slate,  as  thev  can  be  washed,  which 


1334    SCHOOL  SANITATION  AND  PERSONAL  HYGIENE 


lessens  the  dust  nuisance.  The  best  slate  for  this  purpose  is  a  greenish 
or  strong  black  color,  which  is  to  be  preferred  to  the  grays  and  brown- 
ish-blacks. The  loss  of  light  by  absorption  can  be  reduced  greatly  by 
reducing  the  blackboard  area,  and  also  by  covering  the  blackboard  with 
adjustable  curtains.  Colored  crayons  made  with  arsenic  or  sulphid  of 
mercury  carry  danger  and  should  be  prohibited.  Dustless  crayons  may 
now  be  found  on  the  market. 

Posture. — Every  condition  must  be  eliminated  and  every  care  exer- 
cised to  prevent  the  acquiring  of 
physical  defects  in  school,  as  well  as 
to  prevent  the  accentuation  of  those 
physical  defects  which  the  child  may 
have  possessed  before  entering  school. 
Posture  during  sitting  is  of  greater 
consequence  than  posture  during 
standing,  on  account  of  the  longer 
time  the  child  sits  and  the  muscular 
fatigue  caused  by  the  inactivity  of  a 
great  number  of  muscles  of  the  body 
for  a  long  period.  Stooping  over  the 
desk  leads  to  myopia ;  it  also .  con- 
tracts the  chest  and  interferes  with 
free  respiration,  and  puts  additional 
labor  on  the  heart ;  it  leads  to  round 
shoulders  and  curving  of  the  spine 
backward  and  a  carriage  in  which 
the  head  is  pitched  forward ;  it  also 
tends  to  displacement  of  the  internal  organs,  both  of  the  abdomen  and 
pelvis. 

In  order  that  the  pupil  may  be  in  a  proper  physical  condition  to 
maintain  an  erect  posture  while  in  his  seat,  and  thus  form  correct  habits 
which  he  will  carry  through  life,  he  must  be  given  periods  of  relief 
from  sitting  at  the  desk  and  corrective  exercises  at  different  times  dur- 
ing the  day.  In  the  first  year  the  child  should  not  be  confined  at  his 
desk  more  than  one-third  of  the  time.  In  the  succeeding  years  the  total 
amount  of  time  occupied  at  the  desk  may  be  gradually  lengthened.  In 
addition  to  the  regular  recesses  there  should  be  frequent  short  intervals 
of  respite  from  sitting  at  the  desk  devoted  mostly  to  some  form  of  physi- 
cal exercise.  Vertical  writing  is  conducive  to  a  better  position  of  body 
and  consequent  proper  separation  of  eyes  from  objects  regarded  than  the 
slanting  variety. 

A  recess  of  not  less  than  20  minutes  during  the  morning  session  and 
again  during  the  afternoon  session,  when  all  pupils,  if  the  weather  and 
climate  permit,  go  out  of  doors  and  engage  in  some  form  of  active  play, 


Fig.  163. — Boston  School  Desk  and 
Chair. 


SCHOOL  SAMTTATION  AND  PERSONAL  TIYGTK.XK     1335 

is  of  iiifiilculahK'  value  in  its  rcsiills  upon  pliysical  licaltli  ami  mental 
development.  In  addition  there  should  he  uiveii  1o  eaeh  lii'ade  every 
school  day  at  least  two  short  i)erio(ls  ol'  systematie  jihysieal  di'ills  for 
pu])ils  and  teacher  with  the  windows  open. 

Lighting. — 'Die  li^ht  nnist  he  of  ])roper  intensity,  equally  difTused, 
and  come  from  the  i)i'oper  direction.  So  far  as  intensity  is  concerned 
the  liiiiit  must  he  neither  too  dim  nor  too  strong-,  both  extremes  being 
harmful.  The  general  rule  is  that  the  amount  of  transparent  glass  sur- 
face admitting  light  should  be  from  one-sixth  to  one-fourth  of  the  floor 
space.  The  correct  amount  of  window  space  will  depend  on  the  loca- 
tion of  the  building,  direction  from  which  the  light  is  admitted,  size  and 
shape  of  tlie  room,  and  the  proximity  of  other  buildings  or  objects 
which  might  obstruct  the  light. 

The  amount  of  transparent  glass  surface  required  for  proper  illu- 
mination must  be  great  enough  to  afford  sufficient  light  on  rainy,  over- 
cast, and  cloudy  days.  Excessive  window  space  is  scarcely  possible,,  for 
the  excess  illumination  on  bright  days  may  be  regulated  and  softened 
wdth  shades  and  awnings. 

The  amount  of  illumination  is  measured  by  candle  meters  or  candle 
feet ;  that  is,  the  illumination  afforded  by  a  standard  candle  at  a  distance 
of  one  meter  or  one  foot.  Shaw  ^  believes  that  the  illumination  should 
provide  at  least  50  candle  meters  in  the  most  unfavorable  part  of  the 
room. 

Factory-ribbed  glass  or  Luxfer  prisms  disperse  the  light  into  the 
parts  of  the  room  where  the  light  is  needed,  but  diminish  its  total 
amoiint;  they  are  of  advantage,  especially  where  schools  have  a  small 
amount  of  free  space  in  crowded  city  districts. 

The  principal  light  should  come  from  the  pupil's  left,  so  as  not  to 
throw  annoying  shadows  while  writing.  Window^s  may  also  be  placed 
in  the  rear  of  the  pupils.  When  practicable  a  skylight  furnishes  the 
best  direction  for  illumination.  Windows  may  also  be  placed  at  the 
right  for  ventilating  purposes  or  for  admitting  direct  sunlight  while 
the  pupils  are  not  engaged  in  study.  The  window^  sash  should  be 
oYo  or  4  feet  from  the  floor  and  should  reach  as  near  the  ceiling  as  the 
construction  of  the  building  will  permit,  for  the  higher  the  windows 
reach,  the  deeper  the  light  penetrates  into  the  room.  Light  should  never 
enter  from  the  front  and  shine  in  the  pupil's  eyes.  Window  curtains 
should  be  "opaque"  and  of  a  greenish  cast.  The  upper  fourth  of  the 
wdndow  furnishes  one-third  of  the  light,  also  the  best  light,  hence  it  is 
obvious  that  curtains  should  not  be  hung  from  the  top,  but  from  the 
bottom,  and  should  roll  upw^ard.  Artists  have  long  learned  the  lesson 
that  light  from  above  follows  the  direction  of  nature  and  is  most  agree- 
able and  best.     See  Ocular  Hygiene,  page  916. 

^Shaw.  Edward  R.:     "School  Hvgiene."     The  Macmillan  Co.,  X.  Y..  1902. 


1330    SCHOOL  SAX  I  TAT  I  OX  AXI)  PEESOXAL  HYGIEXE 

Ventilati&n  and  Heating. — Ventilation  of  the  school-room  is  of  para- 
mount importance.  There  is  a  great  waste  of  time  and  energy  of  both 
the  teacher  and  pupil  Avorking  in  a  vitiated  atmosphere,  for  pure  air 
properly  conditioned  is  favorable  for  good  mental  work.  Bad  air  mean.s 
sluggishness,  headache,  listlessness,  inattention,  lack  of  energj^,  and  a  de- 
pression of  mental  vigor ;  further,  bad  air  lowers  resistance  to  certain  dis- 
eases.    In  cold  climates  ventilation  and  heating  go  hand  in  hand. 

The  first  responsibility  in  a  poorly  ventilated  school  room  lies  with 
the  building  committees  because  of  their  failure  to  see  that  the  sum 
allowed  for  the  ventilating  plant  is  sufficient  to  give  the  best  that  science 
can  devise.  The  architect  often  skimps  the  ventilating  sy.stem  in  order 
to  provide  a  larger  and  more  ornate  building. 

In  favorable  climates  and  during  mild  weather  the  windows  should 
be  kept  open.  Even  during  cold  weather  the  windows  should  be  opened 
periodically  and  the  room  thoroughly  flushed  out  with  fresh'  air.  The 
windows  should  always  be  thrown  open  at  recess  and  also  during  calis- 
thenic  drills  and  physical  exercises  and  also  at  the  close  of  sessions.  The 
experience  of  the  open-air  and  fresh-air  schools  teaches  that  cold  is  a 
fine  tonic  for  mind  and  body. 

Satisfactory  ventilation  by  means  of  windows  at  all  times  is  im- 
possible on  account  of  varying  winds,  weather  conditions,  but  more 
especially  on  account  of  the  impossibility  of  securing  proper  attention 
on  the  part  of  the  average  teacher  to  the  matter  of  ventilation  in  addi- 
tion to  other  duties.  Window  ventilation  is  simplest,  cheapest,  and  all 
tilings  considered,  frequently  the  best.  The  Fairdiild  system  of  window 
ventilation  is  described  on  page  983. 

Every  school-room  with  a  proper  equipment  and  a  good  janitor  may 
be  kept  well  ventilated  at  all  times.  Many  good  ventilating  systems 
are  rendered  inefficient  through  the  employment  of  cheap  janitors.  A 
good  janitor  not  only  means  greater  efficiency,  but  a  saving  in  fuel 
cost. 

Direct  radiation  from  stoves  or  steam  coils  or  hot-water  pipes  is 
inadvisable  for  school-rooms.  The  hot-air  furnace  may  be  used,  pro- 
vided the  air  is  sufficiently  moistened,  but  the  direct-indirect  system 
with  steam  or  hot-water  pipes  is  to  be  preferred.  Two  thousand  cubic 
feet  of  air  should  be  provided  for  each  pupil  hourly.  The  Massachu- 
setts law  requires  30  cubic  feet  of  pure  air  every  minute  per  pupil 
(1,800  cubic  feet  per  hour).  The  fresh-air  inlet  should  be  capacious 
and  separate  outlets  for  the  foul  air  should  be  provided.  The  cross- 
section  of  inlets  and  outlets  should  equal  from  16  to  20  square  inches 
for  each  pupil.  Ordinarily  it  is  preferable  to  place  both  inlets  and 
outlets  on  the  same  side  of  the  room,  viz.,  upon  the  inner  wall  or  warm 
side.  When  so  placed  the  warm  air  should  be  admitted  about  7  feet 
above  the  floor  and  the  foul  air  should  pass  out  close  to  the  floor. 


SCHOOT.  S.WITATIOX   AND  I'FJfSON'AL  TlVrJIKXK      1:337 

Special  attention  should  be  given  to  the  question  of  humidity,  so 
that  the  warmed  fresh  air  shall  not  be  excessively  dry. 

The  temperature  commonly  accepted  as  proper  for  a  school-room  is 
between  00°  and  ()8°  F.  The  children  would  probably  work  to  l)etter 
advantafre  if  the  temperature  were  kept  a  few  degrees  lower  and  the 
humidity  kept  so  that  the  wet  bulb  never  goes  above  70°  F.  (see  page 
904.  A  thermometer  should  hang  at  about  the  breathing  line  in  every 
school-room  and  the  teacher  should  take  hourly  readings  and  keep  a 
record.  Tlie  temperature  of  school-rooms  is  usually  too  high,  and  those 
heated  with  the  hot-air  furnace  are  usually  also  too  dry.  Both  ex- 
tremes are  prejudicial.  If  the  air  of  the  neighborhood  is  smoky  and 
dusty  it  may  readily  be  filtered  before  it  is  pumped  into  the  school-room. 
The  combination  of  the  plenum  and  vacuum  systems,  the  air  being  driven 
by  rotary  fans,  is  one  of  the  best  methods  of  artificially  ventilating 
school-rooms.      (See  chapter  on  Ventilation.) 

Open  Air  Schools. — ^lost  children  in  open  air  classes  gain  in  weight, 
color,  appetite,  attendance,  deportment  and  scholarship.  The  results 
are  uniformly  good  and  progress  in  grades  is  often  remarkable,  even 
though  the  children  work  little  more  than  half  the  time.  Open  air 
schools  must  give  particular  attention  to  clothing  and  diet,  and  also  to 
recreation  and  rest.  The  benefits  t-o  the  subnormal  and  pretubercular 
child  are  proved,  and  it  is  difficult  to  understand  why  it  should  not  be 
more  widely  adapted  to  the  average  child.     See  page  187. 

"Water-closets  and  Urinals. — Separate  accommodations  must  be  pro- 
vided for  the  sexes;  privies  in  country  districts  should  be  in  entirely 
separate  buildings.  The  urinals  should  be  constantly  and  automatically 
flushed  and  water-closets  and  urinals  should  be  made  to  allow  complete 
inspection  and  use  of  the  scrubbing  brush.  Thorough  ventilation  of 
the  toilet-rooms  should  be  planned  for  and  they  should  be  kept  clean 
and  sweet  at  all  times.     See  page  69. 

The  water-closets  may  be  in  the  basement  if  properly  constructed 
and  independently  ventilated.  The  floors  should  be  asphalted  to  facili- 
tate cleaning  and  flushing,  and  should  be  hosed  daily,  and  scrubbed  at 
least  once  a  week.  The  toilet-room  should  be  well  lighted.  Deodorizers 
should  not  be  used,  for  if  toilet-rooms  are  kept  clean  and  water- 
closets  well  flushed  they  will  not  be  necessary.  Urinals  should  be 
made  of  slate  or  hard  asphalt  or  other  non-absorptive  material,  and 
one  urinal  should  be  provided  for  each  fifteen  boys.  The  out-liouses  in 
country  schools  should  be  properly  constructed  and  under  supervision. 
In  fact,  a  matron  should  be  in  attendance  to  assist  the  little  tots  in  the 
kindergarten  and  lower  elementary  grades,  and  a  watchful  eye  on  the 
part  of  the  master  of  the  school  and  those  he  delegates  for  this  duty 
should  be  kept  to  prevent  misbehavior  in  toilet-rooms. 


L338    SCHOOL  SAXITATIOX  AXD  PEKSOXAL  HYGIEXE 

Cloak-rooms. — There  should  be  one  cloak-room  for  each  class-room, 
and  it  should  connect  both  with  the  hall  and  the  class-room.  Cloak- 
rooms should  be  lighted  from  the  outside,  heated,  and  thoroughly  ven- 
tilated to  carry  off  odors  and  to  dry  the  clothing.  Hanging  the  clothing 
in  the  halls  is  undesirable,  for  obvious  reasons.  Each  pupil  should  have 
a  shelf  on  which  to  lay  hats  and  small  articles,  hooks  upon  which  to  hang 
overcoats,  and  a  space  for  rubber  shoes  and  umbrella. 

Teachers  should  see  to  it  that  the  pupils  do  not  sit  in  wet  shoes  and 
stockings  or  in  wet  clothes.  Each  school  should  have  some  provision 
for  drying  wearing  apparel,  such  as  a  drying  chamber  which  may  be 
in  charge  of  the  janitor,  to  dry  the  wet  clothing  during  school  hours. 

Dressing-rooms  should  also  l)e  provided  for  the  teachers.  All  such 
rooms  and  lockers  should  be  kept  scrupulously  clean. 

Cleanliness. — Schools  should  be  kept  scrupulously  clean  and  every 
precaution  should  be  taken  to  prevent  dust.  Cleanliness  of  person  and 
surroundings  should  be  one  of  the  most  important  lessons  which  the 
pupil  learns  at  school.  Through  example  and  discipline  pupils  should  be 
taught  to  love  order  and  neatness  and  to  abhor  untidiness  and  slovenli- 
ness.   Cleanliness  is  the  keynote  of  sanitation. 

Some  of  the  requirements  for  schools  are :  clean  drinking  water ; 
bubbling  fountains  and  the  abolitioji  of  the  common  drinking  cup;  dis- 
continuance of  the  roller  towel,  cake  of  soap,  brush,  comb,  or  other 
toilet  articles  used  in  common;  cleanliness  of  floors,  desks,  corridors, 
cloak-rooms,  toilet-rooms,  basement,  and  grounds;  the  prohibition  of 
dry  sweeping  or  dusting.  Blackboards  should  be  washed  frequently  to 
avoid  the  dust  nuisance,  and  the  floors  may  be  treated  with  one  of 
the  dustless  floor  oils.  The  windows  should  be  kept  clean,  and  each 
child  should  have  his  individual  books,  pencils,  and  other  accessories. 
Health  Day.  observed  annually,  gives  a  special  opportunity  to  emphasize 
the  importance  of  hygiene  and  cleanliness. 

Medical  Inspection  of  Schools. — The  medical  inspection  of  schools 
is  no  longer  an  experiinent.  but  a  pressing  necessity.  It  is  founded  on 
a  recognition  of  the  close  connection  which  exists  between  the  physical 
and  mental  condition  of  children  in  the  whole  process  of  education.  It 
seeks  to  secure  ultimately  for  every  child,  normal  or  defective,  con- 
ditions of  life  compatible  with  that  full  and  effective  development  of  its 
organic  functions,  its  special  senses,  and  its  mental  and  spiritual  powers 
which  constitute  a  true  education. 

The  object  of  a  medical  inspection  of  schools  is  not  primarily  the 
treatment  of  diseases,  but  rather  their  prevention.  One  of  the  principal 
objects  is  the  early  recognition  of  physical  defects  such  as  errors  of  re- 
fraction, imperfect  hearing,  malformations  of  the  body  from  abnormal 
positions,  adenoids,  enlarged  tonsils,  and  other  obstructions  of  breath- 
ing, and  sources  of  inflammation,  etc.    An  important  object  of  the  med- 


SCHOOL  SANITATION  AND  PERSONAL  HYGIENE     1339 

ical  inspection  of  sc-hool  children  is  to  determine  their  fitness  to  enter 
school  and  to  reeo<:^nize  mental  ami  nervous  disorders;  also  the  early 
recognition  of  the  communicable  diseases  and  measures  to  prevent  their 
spread;  the  supervision  of  vaccination,  and  disinfection;  the  teaching  of 
personal  hygiene  to  pupils  and  teachers,  and  the  sanitation  and  clean- 
liness of  the  school  building  and  its  surroundings;  the  adjustment  of 
the  seat  and  desk,  and  the  medical  supervision  of  the  mental  and  physical 
work  ol'  the  child.  One  of  the  important  functions  of  medical  inspectors 
of  schools  is  to  determine  and  diagnose  the  causes  of  undernutiition. 
See  pages  (574-()T(i. 

Medical  inspection  of  schools  is  making  slow  progress.  It  is  no- 
where carried  out  with  the  thoroughness  and  completeness  that  the  sub- 
ject demands.  A  systematic  school  inspection  was  started  in  Brussels 
in  1874  and  in  Paris  in  1884,  since  which  time  the  movement  has  become 
world-wide.  In  America  the  first  systematic  inspection  of  school  children 
was  begun  in  1894,  after  four  years'  effort  by  Dr.  Samuel  H.  Durgin, 
Commissioner  of  Health  of  Boston,  who  is  regarded  as  the  father  of 
the  system  throughout  America.  The  first  scientific  and  extensive  ex- 
amination of  school  children  was  made  by  Dr.  Henry  P.  Bowditch,* 
whose  essay  upon  "The  Growth  of  Children  Studied  by  Galton's  Method 
of  Percentile  Grades"  has  become  a  classic  in  the  subject.  In  1908  there 
were  only  seventy  cities  outside  of  Massachusetts  having  medical  in- 
spection of  schools.  Massachusetts  has  a  compulsory  medical  inspection 
law;  New  Jersey  has  a  permissive  one;  Vermont  lias  a  law  requiring  an 
annual  testing  of  the  vision  and  hearing  of  all  school  children,  and 
Connecticut  one  providing  for  such  tests  triennially. 

Physical  defects  are  not  equally  significant  either  from  the  medical 
or  from  the  pedagogical  standpoint.  Each  kind  of  defect  should  be  sep- 
arately studied,  and  classification  should  not  include  pediculosis  with  de- 
fective vision;  club-foot  with  defective  hearing;  adenoids  with  ringworm. 

The  objects  of  the  medical  inspection  of  schools  may  be  greatly  as- 
sisted by  teaching  the  teachers  the  elementary  facts  concerned. 

Medical  inspection  of  schools  was  organized  in  this  country  for  the 
purpose  of  controlling  the  communicable  diseases  of  childhood.  It  must 
at  once  be  admitted  that  it  has  been  a  failure  so  far  as  this  object 
is  concerned,  for  it  has  had  very  slight  influence  upon  the  prevalence 
of  measles,  scarlet  fever,  diphtheria,  whooping-cough,  mumps,  etc.  Theo- 
retically we  would  expect  a  good  system  of  medical  inspection  of  school 
children  to  check  the  prevalence  of  these  diseases.  Perhaps  it  does 
so  to  a  limited  extent.  With  improvements  in  the  system,  correlated 
with  child  life  outside  the  school,  much  may  still  be  accomplished  along 
these  lines. 

*  Twenty-second  Anntml  Report.  >State  Board  of  Health  of  Mass.,  1S90,  pp. 
479-522. 


1340    SCHOOL  SANITATION  AND  PERSONAL  HYGIENE 

There  has  been  much  discussion  concerning  who  shall  conduct  the 
medical  inspection.  It  is  plain  that  in  any  system  the  teacher  must  be 
the  ultimate  inspector,  and  teachers  are  quite  competent  to  carry  out  sim- 
ple tests  for  determining  the  acuteness  of  vision  and  hearing.  In  one 
sense  the  teacher  is  the  foster  mother  of  the  child  and  frequently  knows 
the  child  better  than  its  own  mother.  The  teacher  should  report  to 
the  medical  inspector  children  who  show  any  of  the  following  symptoms : 
loss  of  weight,  pallor,  puffiness  of  the  face,  shortness  of  breath,  swellings 
in  the  neck,  general  lassitude,  growing  pains,  rheumatism,  flushing  of 
the  face,  eruptions  of  any  sort,  cold  in  the  head,  especially  running  eyes, 
irritating  discharge  from  the  nose,  evidence  of  sore  throat,  cough,  vomit- 
ing, fever  or  frequent  requests  to  go  to  the  toilet. 

The  next  most  important  link  in  the  chain  of  a  good  system  of 
medical  inspection  is  the  nurse.  She  is  able  to  detect  the  beginning 
symptoms  of  disease  and  can  be  trusted  to  care  for  simple  troubles.  The 
chief  value  of  the  school  nurse,  perhaps,  is  in  establishing  communica- 
tion with  the  home  and  securing  friendly  cooperation  with  the  parents. 
Parental  neglect  is  rarely  due  to  the  lack  of  parental  affection,  but  to 
ignorance.  The  nurse  is  frequently  able  to  gain  the  confidence  of  both 
child  and  parent  when  the  medical  inspector  fails.  The  nurse,  further, 
will  assist  the  medical  staff  in  carrying  out  treatment.  One  of  the  chief 
duties  of  the  school  nurse  is  '^'follow  up"  social  service  work. 

It  is  because  of  the  nurse's  important  place  in  public  health  work 
that  it  is  better  to  have  medical  school-inspection,  together  with  its  valu- 
able follow-up  work,  lodged  with  the  health  authorities  rather  than  with 
the  educational  authorities. 

It  is  the  duty  of  the  medical  inspector  to  detect  defects,  not  to  treat 
them.  Who  shall  treat  the  child  is  a  matter  for  the  parents  or  guardian 
to  decide.  It  is  not  sufficient  merely  to  notify  parents  that  the  child 
needs  treatment,  for  frequently  no  attention  is  paid  to  the  notices.  The 
child  may  be  referred  to  or  taken  by  the  school  nurse  to  the  hospital  or 
outclinic.  In  some  districts  school  clinics  have  been  instituted  with 
success. 

Duties  of  the  Medical  Inspectors. — An  ideal  system  of  medical  in- 
spection of  schools  would  consist  of  a  corps  of  trained  and  competent 
physicians  and  sanitarians  who  would  devote  their  entire  time  to  this 
special  work.  The  staff  should  have  the  assistance  of  experts  in  ven- 
tilation and  heating,  experts  in  sanitary  architecture,  experts  in  sanitary 
engineering,  and  experts  in  the  various  medical  specialties. 

Specialists  should  visit  all  school  buildings  no  less  than  three  times 
each  year  in  order  to  investigate  all  matters  of  heating,  lighting,  and 
ventilation,  cleanliness,  gymnasiums,  bath,  and  toilets,  and  the  seat- 
ing arrangements  with  reference  to  the  size  of  the  pupils;  the  purity  of 
the  drinking  water,  the  quality  of  the  food  purchased  by  the  children  at 


SCHOOL  SANITATION  AND  PERSONAL  HYGIENE     1.141 

the  recess  period,  and  the  general  conditions  of  the  neighborhood  that 
may  affect  the  health  of  the  pupils. 

Furthermore,  cooperation  between  the  medical  and  pedagogical  de- 
partments should  be  helpful  in  solving  the  many  ditlicult  problems  con- 
cerning the  curriculum. 

In  addition  to  these  general  inspections  all  children  entering  school 
should  be  examined  medically  at  least  once  during  each  school  year.  'I'he 
first  examination  is  for  the  purpose  of  establishing  whether  the  child 
is  fit  for  school  and  can  do  the  work  without  injury  either  to  its  mental 
or  physical  well-being.  The  second  should  be  a  physical  examination, 
which  may  be  made  more  thorough  if  the  child  is  required  to  strip. 
This,  however,  should  not  be  done  unless  the  parents  of  the  child  are 
present  or  give  their  consent.  The  third  examination  consists  of  special 
tests  of  the  eyes,  ears,  nose,  throat,  teeth,  heart,  and  lungs,  weight, 
growth,  nutrition,  etc. 

Aside  from  these  regular  examinations,  the  school  physician  must 
respond  to  every  call  when  a  pupil  comes  to  school  having  an  eruption, 
fever,  or  other  symptoms  indicating  a  communicable  disease.  The  med- 
ical inspectors  should  also  oversee  disinfection,  vaccination,  and  certify 
the  return  to  school  of  any  child  who  has  been  out  of  school  by  reason 
of  a  communicable  disease. 

On  account  of  the  tendency  for  tuberculosis  to  develop  in  children 
who  have  just  suffered  from  measles,  scarlet  fever  or  whooping-cough, 
as  well  as  to  prevent  other  sequelae  of  the  acute  infectious  troubles,  med- 
ical inspectors  should  be  detailed  to  visit  and  keep  in  close  touch  with 
such  children  for  from  three  to  six  months,  or  for  as  long  as  may  be 
necessary.- 

The  Communicable  Diseases  of  Childhood. — Parents  naturally  come 
to  regard  the  school  as  a  veritable  pesthouse  for  the  spread  of  the  com- 
municable diseases  of  childhood — especially  measles,  whooping-cough, 
mumps,  diphtheria,  scarlet  fever,  chicken-pox,  common  colds,  etc.  Many 
of  these  diseases  prevail  in  epidemic  form  during  the  summer  time, 
when  school  is  closed,  and  under  other  circumstances  which  show  that 
epidemics  may  be  independent  of  school  attendance.  It  is  difficult  to 
determine  just  what  part  is  played  by  the  commingling  of  the  pupils 
in  school  in  the  spread  of  such  diseases  and  what  part  is  due  to  other 
factors.  Some  diseases  take  a  sudden  jump  in  the  autumn  with  the 
opening  of  school.  Further,  these  diseases  are  not  contracted  by  the 
school  children  alone,  but  are  carried  home  to  the  other  members  of 
the  household,  and  thereby  create  secondary  foci.  This  problem-  of  the 
communicable  diseases  and  the  schools  is  far  from  solution;  the  spread 
of  these  diseases  has  not  been  conquered  by  medical  inspection,  and  their 
relation  to  school  attendance  is  one  that  needs  careful  observation  and 
studv. 


1342    SCHOOL  SANITATIOTST  AND  PERSONAL  HYGIENE 

A  difference  is  made  between  exclusion  on  account  of  disease  and 
that  due  to  exposure.  In  the  latter  case  the  period  of  exclusion  is  based 
upon  the  period  of  incubation  of  the  disease.  Immunes  are  not  excluded. 
Carriers  should  be  looked  for. 

Closing  Schools  on  Account  of  Epidemics. — The  question  of  closing 
the  schools  when  some  one  of  these  diseases  breaks  out  is  often  a  difficult 
one  to  decide.  If  the  children  commingle  out  of  school,  upon  the  streets 
and  playgrounds,  no  useful  purpose  is  accomplished  by  closing  the 
schools.  Hence  closing  schools  is  usually  more  effective  in  sparsely 
settled  country  districts  than  in  cities.  Closing  schools  is  economically 
wasteful  and  usually  has  no  influence  on  the  course  of  an  outbreak. 
Children  are  less  apt  to  infect  each  other  in  the  class-room  than  in 
the  home  or  on  the  playground.  As  a  rule  better  results  will  be 
achieved  by  daily  inspection  of  all  school  children  than  by  closing  the 
schools.  At  the  beginning  of  an  outbreak  the  schools  may  be  closed  for  the 
period  of  incubation  and  then  opened,  but  careful  guard  must  be  exer- 
cised to  discover  new  cases  and  a  wafch  kept  over  the  return  of  con- 
valescents. Under  these,  circumstances  a  daily  inspection  should  be 
conducted  before,  and  not  after,  the  children  enter  school.  If  closing 
the  schools  during  the  period  of  incubation  is  not  effective  nothing  will 
be  gained  by  prolonging  the  period. 

The  consensus  of  opinion  now  is  that  the  successful  control  of  epi- 
demic disease  in  school  children  requires  keeping  the  schools  open,  with 
careful  daily  and  frequent  periodic  inspections;  the  exclusion  of  cases 
and  contacts;  and  home  visitation. 

A  special  lookout  must  be  kept  for  carriers,  and  laboratory  facilities 
provided  to  detect  the  same. 

The  diseases  for  which  children  should  be  excluded  from  school  are: 
smallpox,  scarlet  fever,  measles,  German  measles,  chicken-pox,  diph- 
theria, tonsillitis,  whooping-cough,  pediculosis,  mumps,  scabies,  tra- 
choma, ringworm,  impetigo  contagiosa,  venereal  disease,  pulmonary 
tuberculosis,  influenza. 

Tlie  Eyes. — Errors  of  refraction  are  exceedingly  common,  and  if  not 
corrected  may  be  the  cause  of  headache,  nervousness,  reflex  pains,  and  a 
great  variety  of  symptoms.  They  are  also  a  great  handicap  to  the 
mental  and  physical  development  of  the  child.  The  vision  of  all  chil- 
dren should  be  tested  annually,  and  at  least  once  for  color-blindness. 
It  is  believed  that  the  unnatural  strain  of  accommodating  the  eyes 
to  close  work  (for  which  they  were  not  intended)  leads  to  myopia  in  a 
large  proportion  of  growing  children.  Thus  the  percentage  of  myopia 
increases  markedly  from  the  primary  classes  through  the  grammar 
grades,  and  is  highest  in  the  high-schools.  The  eyes  should  therefore 
be  tested  and  errors  of  refraction  corrected  at  least  once  a  year.  There 
are  certain  children  who  show  normal  vision  by  the  ordinary  tests  (Snel- 


SCHOOL  s.wnwrioN'  .wd  pkijsonwl  iiv(;ii:\i-:    ]:u3 

leii  test  ty|)(').  yet  whoso  eves  sliduld  he  e.xaiiiimd  hy  an  cxiuTt  it'  they 
hahitually  hold  the  head  too  near  the  hook  (less  than  1'.'  to  1  I  inches); 
or  if  they  frequently  coniiihiin  of  headaeiie,  especially  in  the  latter  por- 
tion of  school  hours;  or  if  one  eye  deviates  even  temporarily  from  the 
normal  ])osition.  The  following  symptoms  also  indicate  trouble  with 
the  eyes,  viz.,  scowling  and  wrinkling  of  the  forehead  when  reading  or 
writing,  watery  eyes,  reddened  or  granular  lids,  twitching  of  the  face, 
inattention,  and  slowness  in  book  studies  in  a  child  otherwise  bright. 

The  conditions  which  are  especially  hard  upon  the  eyes  are  dim  light, 
improper  angle  of  vision,  small  print,  and  prolonged  focusing  at  close 
range.     Type  for  books  should  not  be  .smaller  than  the  following: 


Type 

Width  of  Leading 

First  vear ...      .                  

2.6  mm. 
2.0  mm. 
1.8  mm. 
1.6  mm. 

Second  and  tliird  vear.s 

4  0  mm 

Fourth   vear 

3.6  mm.   - 

Above  this  grade 

3.0  mm. 

In  addition  to  the  size  the  characters  should  be  simple,  the  ink 
black,  and  printed  upon  paper  with  unreflecting  surface  that  is  free 
from  gloss.  Paj^er  of  a  grayish  tone  is  to  be  avoided  and  the  paper 
should  be  thick  enough  or  of  such  quality  that  the  print  does  not  show 
through  from  the  back.  Pupils  should  be  taught  that  it  is  advisable 
while  reading  or  during  other  close  focusing  of  the  eyes  occasionally  to 
look  away  and  accommodate  for  distance  to  relieve  the  tension  and 
c^ounteract  the  tendency  to  myopia.     See  Ocular  Hygiene,  page  916. 

The  Ears. — It  has  been  found  that  approximately  15  per  cent,  of 
school  children  possess  some  defect  of  hearing  either  in  one  or  both 
ears.  Defective  hearing  is  frequently  mistaken  for  inattention  upon  the 
part  of  the  pupil,  for  which  he  may  be  unjustly  punished.  Practical 
tests  to  determine  the  acuteness  of  hearing  should  be  made  separately 
with  each  ear  by  the  use  of  a  watch  or  by  the  whisper  voice.  Dis- 
charges from  the  ears,  known  as  abscesses  in  the  ears,  or  earache  should 
at  once  be  reported  to  the  proper  medical  attendant. 

Oral  Prophylaxis. — The  essential  features  of  oral  prophylaxis  are  (1) 
normal  mucous  membranes  and  associated  structures,  and  (2)  clean- 
liness. The  health  of  the  mucous  membranes  of  the  mouth  and'  throat, 
including  the  closely  associated  glands  and  lymphoid  tissues  and  the 
teeth,  depends  upon  the  general  health  of  the  body.  Cleanliness  helps 
avoid  the  immediate  causes  of  caries  and  inflammation. 

The  ieeili  are  living  sensitive  structures,  lying  in  sockets  which 
resemble  a  bony  joint.  The  teeth  almost  always  decay  from  without, 
as  a  result  of  acid  formed  by  bacterial  fermentation.     Strono-  teeth  in 


1344    SCHOOL  SANITATIOX  AND  PP:KS0NAL  HYGIENE 

a  healthy  body  have  a  much  greater  power  of  resisting  caries  than  other- 
wise. Tlie  teeth  can  even  sj)arkle  with  the  glow  of  good  health.  Teeth 
need  exercise  by  eating  the  right  kind  of  food  in  the  proper  way.  A 
diet  of  soft,  pulpy  food  weakens  the  teeth  and  invites  trouble.  On  the 
other  hand,  the  public  must  be  taught  to  have  a  respect  for  the  teeth, 
and  should  kiiow  that  it  is  hazardous  to  use  them  to  take  the  place 
of  nut  crackers  or  gas  pliers. 

Caries  of  the  teeth  is  a  disease  of  civilization.  Savages  in  vigorous 
health  and  with  nutritious  diet  do  not  have  decayed  teeth,  even  though 
they  do  not  use  a  tooth  brush  or  practice  oral  prophylaxis.  Tooth  decay 
is  often  an  expression  of  general  malnutrition  and  is  frequently  associ- 
ated with  enlarged  tonsils,  adenoids,  and  other  signs  of  disease  or  de- 
generation. In  the  same  sense,  "rheumatism"'  of  the  joints  may  not 
be  due  to  trouble  in  and  about  the  teeth,  for  it  is  often  due  to  the  same 
cause  that  affects  the  teeth. 

Caries  is  a  decalcification.  The  common  explanation  is  that  the 
calcium  is  dissolved  by  the  lactic  acid'  formed  by  the  fermenting  food 
in  contact  with  the  teeth.  This,  however,  is  not  the  whole  story.  It 
is  probable  that  sound,  vigorous  teeth  have  a  definite  power  of  resistance 
and  it  is  now  believed  that  structural  changes  within  the  tooth  render 
it  susceptible  to  outside  influences.  It  is  quite  clear  that  calcification, 
as  well  as  decalcification  of  the  tooth,  is  mainly  dependent  upon  the  gen- 
eral nutrition  of  the  body.  The  ductless  glands  also  influence  calcium 
metabolism.  Children  need  about  five  times  as  much  calcium  in  their 
diet  as  adults.  It  would  therefore  appear  that  a  well  balanced  diet,  rich 
in  vitamins,  including  whole  grains,  fresh  dairy  products  and  green 
vegetahles,  is  one  of  the  best  preventives  against  tooth  decay.  Unbalanced 
diets,  deficient  in  vitamins,  also  give  rise  to  conditions  of  the  teeth  and 
gums  resembling  pyorrhea.  "Pyorrhea"  may  not  always  be  primarily 
a  local  infection,  but  rather  the  expression  of  a  general  condition  of 
malnutrition.  One  of  the  early  symptoms  of  scurvy  is  swelling  of  the 
gums,  loosening  of  the  teeth  and  gradual  absorption  of  the  cement  mem- 
brane of  the  alveolar  sockets ;  in  fact,  the  teeth  are  among  the  parts 
first  affected  in  scurvy.  ' 

Some  of  the  accessory  causes  of  dental  decay  are:  low  resistance  of 
the  teeth  because  of  developmental  defects,  both  antenatal  and  post- 
natal; faulty  diet  both  of  mother  during  pregnancy  and  of  the  child; 
neglect  of  dental  attention  through  ignorance  of  parents;  cost  of  dental 
service;  lack  of  dental  facilities,  especially  in  rural  sections;  failure  of 
the  child  to  call  attention  to  the  condition  of  the  teeth,  either  because 
it  is  too  young  or  because  of  fear. 

Dental  defects  influence  growth,  resistance  to  communicable  infec- 
tions, preservation  of  facial  symmetry,  and  degenerative  diseases. 

From  the  standpoint  of  bacteria,  the  mouth  is  one  of  the  "filthiest" 


SCHOOL  SAMTA'I'loN    AM)   rKl.'SONAL  11  VC  1 1:.\  K     134.") 

|i:irts  (if  the  IkkIv.  .iiul  ciiii  l)o  kept  clean  only  hv  s])('(iiil  means.  l*'<)r 
the  cleanliness  of  the  teeth,  we  can  well  ctuitent  onrselves  with  a  tooth 
hrnsh.  some  silk  Ihtss  ami  clean  watt  r.  In  youn-j;  children,  silk  floss 
is  not  advisable  il'  the  space  between  the  teeth  is  tilled  with  soft  tissue. 
In  using  silk  floss,  a  rubber  band  or  metal  strip,  care  must  be  taken 
not  to  injure  the  sfunis.  The  teeth  can  also  be  polished  with  a  piece 
of  gau/.e  or  i  iihher  wiapi)e(l  about  the  forefinger.  .A  little  soap  or  some 
dental  ])owder.  free  of  grittiness,  helps  to  clean  the  surface  of  the  teeth, 
and  will  to  some  extent  help  to  prevent  the  accumulation  of  tartar. 
Children  should  be  taught  the  necessity  of  cleansing  all  the  surfaces 
of  the  teeth,  and  the  importance  of  keeping  the  tooth  brush  itself  clean 
by  occasional  boiling  ami  sunning.  A  mucin  film  collects  on  the  teeth 
which  may  be  precijutated  by  eating  acid  fruits.  Alkaline  mouth 
washes  containing  a  little  bicarbonate  of  soda,  lime  water,  or  magnesium 
oxid  help  correct  acid  mouths  and  check  the  development  of  "acid 
spots,"'  discoloration  and  tartar  formation. 

Flushing  and  rinsing  the  mouth  with  pure  warm  water  helps  me- 
chanically to  cleanse  the  surfaces.  Antiseptic  mouth  washes  are  a  snare 
and  a  delusion.  It  is  not  possible  to  add  any  known  germicidal  sub- 
stance to  the  mouth  rinse  tluit  will  sterilize  or  disinfect  the  buccal 
cavity.  The  germs  are  so  protected  that  no  disinfectant  can  reach 
them,  even  when  applied  directly  to  the  infected  mucous  membrane  or 
gums.  Furthermore,  any  known  disinfectant  sufficiently  powerful  to 
kill  bacteria  would  injure  or  destroy  the  delicate  tissues  and  thereby 
do  more  harm  than  good.  Many  of  the  mouth  washes  on  the  market 
vary  but  slightly  in  their  composition  from  those  described  in  either 
the  Pharmacopeia  or  the  Xational  Formulary. 

The  teeth  should  be  examined  and  cleansed  by  a  competent  dentist 
at  least  once,  and  preferably  twice,  a  year.  In  the  light  of  our  present 
knowledge  it  is  an  outrage  to  allow  caries  <?f  the  teeth  to  develop  into 
toothache  before  children  are  taken  to  a  dentist.  Irregularities  of 
the  teeth,  especially  those  which  make  it  impossible  to  close  the  mouth 
properly,  lead  to  faulty  digestion,  to  mouth  breathing,  and  other  defects. 
The  first  permanent  molars  (6-year  molars)  are  perhaps  the  most 
important  teeth  in  the  mouth,  and  are  the  most  frequently  neglected 
because  they  are  so  often  mistaken  for  temporary  teeth.  It  should  be 
known  that  decay  of  the  teeth  is  favored  by  the  fermentation  of  starchy 
foods  and  sugars,  so  that  an  important  factor  in  preventing  dental 
caries  is  the  removal  of  food  particles  by  frequent  brushing  and  the 
use  of  the  silk  floss.  Children  should  be  discouraged  from  eating 
crackers  and  candy  between  meals  and  the  teeth  should  be  cleaned  after 
each  meal. 

To  provide  expert  dental  attention  for  all  carious  teeth,  including 
the   temporary    set,    would    overtax    the    facilities    of    any    community. 


1340    SCHOOL  SANITATION  AND  PERSONAL  HYGIENE 

Dental  hygienists  can  do  much  of  the  cleansing  and  simpler  mechanical 
work.  Dental  clinics  should  be  proA'ided  in  whicli  caries  of  the  tem- 
porary teeth  should  have  at  least  temporary  treatment.  It  should  be 
remembered  that  one  infected  tooth  is  like  a  rotten  apple  in  a  barrel 
in  that  it  is  apt  to  involve  the  others. 

Streptococcal  infections  are  common  about  the  roots  of  teeth,  espe- 
cially those  that  are  devitalized  or  injured.  Perhaps  the  most  important 
structures  to  maintain  the  vitality  and  immunity  of  the  teeth  are  the 
pulp  cavity  and  the  pericemental  membrane.  It  is  also  important  not 
to  injure  the  margin  of  the  gums  where  they  join  the  teeth.  Strepto- 
coccal inflammations  and  abscesses'  frequently  form  about  the  roots  of 
such  teeth,  and  sometimes  give  rise  to  secondary  foci,  causing  neuralgia, 
stiff  neck,  rheumatic  inflammation  of  the  joints,  sciatica,  endocarditis, 
appendicitis,  inflammation  of  the  gall  bladder,  and  other  serious  com- 
plications. These  blind  abscesses  about  the  teeth  should  be'sought  for 
by  radiography  and  corrected  before  secondary  complications  ensue. 

All  ulcerated,  inflamed  or  diseased  conditions  in  the  mouth,  includ- 
ing the  tonsils,  throat,  and  nose,  should  be  treated  without  delay  and 
measures  taken  to  prevent  their  recurrence.  Healthy  mucous  mem- 
branes, sound  teeth,  and  normal  tissues,  are  our  best  protection  against 
infection. 

Nose  and  Throat. — The  noses  and  throats  of  all  pupils  should  be 
examined  for  any  cause  of  obstruction  to  respiration,  particularly  ade- 
noids, polypi,  deviation  of  the  septum,  etc.  Nosebleed  should  always  be 
reported  and  inquiry  should  be  made  as  to  mouth-breathing  during 
sleep.  In  all  cases  of  acute  illness  the  throat  and  mouth  should  be 
examined  for  indications  of  scarlet  fever  or  measles  and  for  the  signs 
of  tonsillitis  or  diphtheria,  and  a  culture  should  be  taken  in  any  sus- 
pected case  of  diphtheria.  The  presence  of  a  discharge  from  the  nose 
should  be  noted,  and  if  it  "is  thick  and  creamy  a  culture  should  always 
be  taken.  If  the  discharge  from  the  nose  is  only  from  one  nostril  a 
foreign  body  or  local  cause  should  be  looked  for.  Adenoids  may  be  in- 
ferred from  mouth-breathing,  snoring,  chronic  post-nasal  catarrh,  or 
recurring  ear  trouble.  Pupils  with  obviously  large  tonsils,  recurring 
tonsillitis,  and  enlargement  of  the  glands  of  the  neck  should  be  referred 
to  a  physician  for  treatment. 

Personal  hygiene  deals  with  much  more  than  the  prevention  of  the 
communicable  diseases.  Personal  habits  may  protect  the  individual 
against  infection,  but  the  problem  of  preventing  the  spread  of  infectious 
and  contagious  diseases  is  largely  one  of  public  hygiene.  Personal  pro- 
phylaxis is  discussed  in  detail  under  each  communicable  disease  in  other 
parts  of  this  book. 

The  chief  object  of  personal  hygiene  is  to  live  efficiently.  The  stu- 
dent of  preventive  medicine  is  more  interested  in  living  well  than  in 


SCHOOL  SANITATION'   AND   TKh'SONAT.  inCIKXE     1:517 

living  long.  The  physical  and  inciilal  haii(licai)s  of  life  sliouhl  ho  cor- 
rected; if  they  are  not  anieiiahie  to  treatment,  the  individual  must  learn 
to  adjust  his  activities  within  the  jjower  of  his  physical  machine.  This 
is  a  |)r()hlem  of  compensation.  To  (h'i\t'  at  iiigh  sj)ced  a  machine  that 
is  built  to  go  tiiirty  miles  an  hour  invites  disaster.  This  is  a  i)rohlem 
of  personal  hygiene — it  is  individual.  It  depends  first  upon  a  diagnosis 
of  the  defect,  its  nature,  its-  course  and  its  effects;  then,  an  intelligent 
adjustment  to  make  life  satisfactory  within  the  limitations  of  the 
liody. 

Those  who  are  endowed  with  a  robust  frame,  sturdy  physique,  sound 
functions  and  good  constitution  must  also  learn  the  limits  to  which  the 
human  machine  may  be  driven  without  permanent  barm.  One  of  the 
important  lessons  of  persoiuil  hygiene  is  to  develop  good  iidiiljitions, 
which  are  fundamental  for  a  temperate,  normal  life.  This  is  a  problem 
which  each  person  must  learn  for  himself. 

Personal  hygiene  with  reference  to  clothing  and  exercise  will  be 
found  in  the  section  on  Military  Hygiene.  Other  topics  dealing  with 
the  subject  of  personal  hj^giene  are  scattered  throughout  the  volume. 
See  Index. 

Diseases  of  the  Skin. — Apart  from  the  exanthemata  the  diseases  of 
the  skin  of  school  children  which  are  of  importance  because  communi- 
cable are :  scabies,  pediculosis,  ring"worm,  and  impetigo. 

Scabies. — All  children  wdio  are  scratching  or  have  an  irritation  on 
the  skin  should  be  examined  for  scabies  (the  itchmite).  It  is  important 
that  all  infected  members  of  the  family  be  treated  until  cured,  else  the 
disease  is  passed  back  and  forth  from  one  to  another.  It  is  also  im- 
portant that  all  clothing,  bedding,  towels,  etc.,  and  similar  things  that 
come  in  contact  with  the  body  be  boiled  each  time  they  are  washed.  All 
cases  of  scabies  should  be  excluded  from  school  until  cured.  Sulphur 
ointment  is  usually  efficacious. 

PedicuU  Capitis. — Pediculi  capitis  (head  lice)  are  extremely  com- 
mon among  children,  and  are  communicated  directly  and  also  by  wearing 
each  other's  hats  or  hanging  them  on  each  other's  pegs,  or  from  combs 
and  brushes.  Every  child  should  have  its  own  brush  and  comb.  These 
should  be  cleaned  by  immersion  in  boiling  water.  Xo  person  should  be 
blamed  for  having  lice,  only  for  keeping  them.  The  condition  may  be 
suspected  by  the  teacher  in  children  who  show  indications  of  irritation 
of  the  scalp,  and  the  condition  is  easily  detected  by  looking  for  the 
eggs  (nits),  which  are  small  white  objects  adhering  to  the  hair.  Head 
lice  are  best  treated  by  killing  the  living  parasites  with  crude  petroleum 
and  then  getting  rid  of  the  nits.  With  boys  this  is  easy ;  a  close  haircut  is 
all  that  is  needed.  "With  girls  a  fine-tooth  comb  wet  in  alcohol  or  vinegar, 
which  dissolves  the  attachment  of  the  eggs  to  the  hair,  may  be  used. 
All  combs  and  brushes  used  should  be  carefullv  washed  and  disinfected. 


1348    SCHOOL  SAXITATIOX  AXD  PEESOXAL  HYGIEXE 

Children  with  pediculi  should  be  excluded  from  school  until  their  heads 
are  clean.     See  also  page  362. 

Bin g worm. — Eingworm  of  the  skin  yields  readily  to  treatment,  but 
upon  the  scalp  is  usually  chronic.  When  the  disease  attacks  the  scalp 
the  hair  falls  off  or  breaks  off  near  the  scalp,  leaving  areas  the  size  of 
a  dime  or  dollar  nearly  bald.  The  scalp  in  these  areas  is  usually  dry 
and  somewhat  scaly,  but  may  be  swollen  and  crusted.  The  disease 
spreads  at  the  circumference  of  the  area  and  new  areas  arise  from 
scratching,  etc.     The  diagnosis  is  made  by  looking  for  the  fungus. 

Favus. — Favus  is  a  disease  somewhat  allied  to  ringworm,  more  com- 
mon in  Europe  than  in  America.  In  this  disease  quite  abundant  crusts 
of  a  yellowish  color  are  present  when  the  process  is  active.  The  roots 
of  the  hair  are  killed  by  the  Aclwrion  sclwnleitm,  so  that  loss  of  hair 
from  this  disease  is  permanent,  a  scar  remaining  when  the  condition 
is  cured. 

Children  with  ringworm  or  favus  should  not  be  allowed  to  attend 
school  unless  the  lesions  are  properly  dressed  and  covered  with  collodion. 
Children  should  be  taught  to  use  their  own  brushes  and  combs  and  not 
to  wear  each  other's  hats,  caps,  etc.  In  some  districts  special  schools  are 
maintained  for  favus  and  for  ringworm  of  the  scalp,  where  the  pupils 
receive  treatment. 

Impetigo. — Impetigo  is  a  disease  characterized  by  pustules  which 
appear  on  the  face,  neck,  and  hands,  less  often  upon  the  body  and  scalp. 
The  size  of  the  pustules  varies  very  much  and  they  often  run  together  to 
form  on  the  face  large  superficial  sores  covered  with  thick,  dirty,  yellow- 
ish, or  brownish  crusts.  The  disease  is  contagious  and  spreads  by  scratch- 
ing as  well  as  by  using  common  towels  and  other  things.  Children  hav- 
ing impetigo  should  not  be  allowed  to  attend  school  until  all  the  sores 
are  healed  and  the  skin  smooth. 

Nervous  Diseases  and  Mental  Defects. — A  sharp  lookout  for  indica- 
tions of  diseases  of  the  nerves  and  of  mental  defects  should  be  kept  and 
especial  notice  taken  of  suggestive  symptoms  in  a  child  who  did  not 
formerly  show  them.  The  teacher  should  be  taught  to  report  instances 
of  restlessness  or  inability  to  stand  or  sit  quietly  in  a  previously  quiet 
child,  especially  if  to  this  are  added  irritability  of  temper  and  loss  of 
self-control,  such  as  crying  for  trifles  or  inability  to  keep  the  attention 
fixed. 

Chorea. — Twitching  of  the  muscles,  the  result  of  disease,  may  cause 
the  child  to  drop  things,  render  his  work  awkward,  or  interfere  with 
writing  or  drawing.  Such  children  are  too  often  scolded  for  being  in- 
attentive or  careless.  The  indications  of  chorea  (St.  Yitus's  dance) 
should  not  be  confounded  with  habit-spasms  such  as  blinking  of  the 
eyelids  or  the  slower  twitching  movements  of  the  face  or  shoulders  or 
other  parts  of  the  body,  which  may  be  due  to  defects  of  vision,  adenoid 


SCHOOL  SAXITA'I'ION    WD   I'EI^SOXAL  TTYrilEXK     134!) 

Errowtlis,  or  oihcv  reflex  causes.  Cases  of  chorea  should  he  removed 
from  school  at  once,  hoth  for  the  child's  safety  and  to  i)revent  an  epi- 
demic of  imitative  movements  such  as  sometimes  occurs.  Children  with 
habit-spasms  need  not  he  withdrawn  from  school  work,  although  these 
conditions  often  require  treatment. 

Ei)ilej)fii/. —  Mild  epileptic  attacks  (pelil  inal)  are  frequently  over- 
looked or  misunderstood  by  the  teacher.  They  may  be  mistaken  f(jr 
faintinor.  I'sually  these  attacks  are  only  momentary,  in  which  the  child 
stares  fixedly  and  does  not  reply  to  questions  or  in  which  he  suddenly 
stops  speaking  or  whatever  he  is  doing  and  is  unaware  of  what  is 
going  on  about  him.  "^rhe  lapse  of  consciousness  is  one  of  the  charac- 
teristic features  of  epilepsy.  The  attack  may  be  accompanied  by  rolling 
up  of  the  eyes,  drooling,  or  unusual  movements  of  the  Hps;  an  epileptic- 
fit  often  appears  like  a  choking  attack.  Teachers  very  frequently  mis- 
understand epileptic  attacks  and  cannot  be  expected  to  distinguish  them 
from  hysterical  convulsions  and  other  diseases.  It  does  not  necessarily 
follow  that  cases  of  epileps)'  should  be  withdrawn  from  tlie  school,  but 
medical  advice  should  always  be  had. 

Xeurasthenia. — Xeurasthenia  or  nerve  fatigue  may  be  shown  by 
irritability  or  sleeplessness  and  other  indications  threatening  a  nervous 
breakdown.  This  may  be  due  to  irregular  habits,  want  of  proper  sleep, 
lack  of  suitable  food,  poor  hygienic  conditions,  or  simply  from  the  child 
being  pushed  in  school  beyond  his  physical  or  mental  capacity.  Exces- 
sive fear  or  morbid  ideas,  bashfnlness,  undue  sensitiveness,  causeless  fits 
of  crying,  morbid  introspection,  and  self-consciousness  may  also  be  symp- 
toms of  a  neurasthenic  condition,  and  call  for  investigation  and  for  the 
teacher's  sympathy  and  winning  of  the  child's  confidence  to  prevent 
developments  of  a  more  serious  nature.  Excitability  is  often  the  first 
stage  of  fatigue  and  is  frequently  mistaken  for  brightness  and  therefore 
encouraged. 

The  teacher  should  know  that  forgetfulness,  loss  of  interest  in  work 
and  play,  desire  for  solitude,  untidiness  in  dress  or  person,  and  like 
changes  of  character  are  sometimes  incidental  to  the  period  of  puberty. 

Defectives. — ^lentally  defective  children  in  the  public  schools  ex- 
hibit certain  common  characteristics  which  soon  become  evident.  The 
typical  incorrigible  child  of  the  primary  grades  often  is  a  mentally  de- 
fective child  of  the  excitable  type.  They  are  destructive,  cruel  to  smaller 
children,  and  often  precocious  sexually.  Certain  cases  show  marked 
moral  deficiency.  Mentally  defective  children  must  be  distinguished 
from  those  who  are  only  temporarily  backward  as  a  result  of  some  re- 
movable cause  such  as  defective  vision,  impaired  hearing,  adenoid 
growths,  or  as  a  result  of  unhappy  home  conditions,  irregular  habits, 
want  of  proper  sleep,  lack  of  suitable  food,  bad  hygienic  conditions,  etc. 
Teachers  should  refer  to  the  medical  inspectors  for  examination  children 


1350    SCHOOL  SAXITATTOX  AXD  PEESOXAL  HYGIEX"E 

who,  without  obvious  cause,  such  as  absence  or  ill  health,  show  them- 
selves unable  to  keep  up  in  their  school  work,  who  are  unable  to  fix 
their  attention,  or  are  incorrigible. 

A  careful  lookout  should  be  kept  for  children  showing  sexual  per- 
version, for  one  sexual  pervert  may  demoralize  a  whole  school. 

Vaccination. — Vaccination  should  be  required  of  all  children  before 
they  are  permitted  to  attend  school.  The  evidence  of  a  successful 
vaccination  usually  accepted  is  a  physician's  certificate  or  a  characteris- 
tic scar.  For  the  indices  of  a  successful  take  see  page  12.  School 
children  should  be  vaccinated  before  entering  school  and  again  before 
entering  high  school. 

REFERENCES 

The  following  references  have  been  used  in  the  preparation  of  this  chapter, 
especially  the  books  of  Shaw  and  Hogarth. 

Shaw,  Edward  E.  :     "School  Hygiene."     The  Maemillan  Co.,  IST.  Y.,  1902. 

Hogarth,  A.  H. :  "Medical  Inspection  of  Schools."  Oxford  Medical  Pub- 
lications, London,  1909. 

GuLiCK,  L.  H.,  and  Ayres,  L.  P. :  "Medical  Inspection  of  Schools."  New 
York  Charities  Publication  Committee,  MCMVIII. 

Stevens,  E.  M.  :  "Medical  Supervision  in  Schools."  Bailliere,  Tindall, 
and  Cox,  London,  1910. 

Dressler,  Fletcher  B.  :     "School  Hygiene."     Maemillan,  1913. 

Cornell  :  "Health  and  Medical  Inspection  of  School  Children."  "Medical 
Inspection  of  School  Children."  A  Summary  of  Existing  Legislation, 
Issued  by  Council  on  Health  and  Public  Instructions  of  the  Amer. 
Med.  Assn.,  1912. 

Baginsky,  Adolf:  "Handbuch  der  Schulhygiene."  Bd.  I,  1898;  Bd.  II, 
1900.    Ferdinand  Enke,  Stuttgart. 

Transactions  of  the  International  Congress  on  School  Hygiene. 

Zeitschrift  f.  SchulgesundJieitspflege. 

Bowditch,  H.  p.:  "The  Growth  of  Children  Studied  by  Galton's  Method 
of  Percentile  Grades."  Twenty-second  Annual  Eeport  of  the  State 
Board  of  Health  of  Mass.,  1890,  pp.  479-522. 

Weyl,  Theodor:  "Handbuch  der  Hygiene."  Vol.  VII,  Erste  Abt,  Schul- 
hygiene, Jena,  1895. 

"Code  of  Lighting  of  School  Buildings,"  Illuminating  Engineering  So- 
ciety, 29  West  39th  Street,  New  York  City. 


SECTION  XIV 
DISINFECTION 

CHAPTER  I 
GENERAL  CONSIDERATIONS 

Disinfection. — Disinfection  means  the  destruction  of  the  agents  caus- 
ing infection.  An  object  is  said  to  be  infected  when  contaminated  with 
pathogenic  microorganisms.  It  is  disinfected  by  destroying  these  or- 
ganisms, whether  they  are  in  the  substance  or  on  the  surface  of  that 
object.  Disinfection,  then,  deals  only  with  destroying  the  vitality  of 
those  minute  forms  of  life  which  cause  disease.  It  does  not  mean  the 
destruction  of  all  the  lower  forms  of  animal  and  vegetable  life  that  may 
be  in  or  upon  an  object — this  is  sterilization.  See  Concurrent  and  Ter- 
minal Disinfection,  page   1357. 

Disinfecting  procedures  properly  applied  have  an  important  part  in 
the  prevention  of  communicable  diseases.  Their  efficiency  decreases  as 
the  distance  between  the  place  of  origin  of  the  infection  (the  patient) 
and  the  point  of  their  application  is  increased. 

Sterilization. — Sterilization  means  the  destruction  of  all  microbial 
life  on  or  in  an  object.  A  sterile  object  is  a  lifeless  object.  All  processes 
which  sterilize  necessarily  disinfect,  but  all  disinfecting  processes  by 
no  means  sterilize.  The  distinction  between  disinfection  and  steriliza- 
tion arises  principally  from  the  fact  that  spores  have  a  much  greater 
resistance  to  all  influences  which  destroy  the  vegetative  cells.  Fortu- 
nately, none  of  the  pestilential  diseases  of  man  which  occur  in  wide- 
spread epidemics,  so  far  as  known,  are  caused  by  microorganisms  with 
resistant  spores ;  therefore  the  usual  processes  of  disinfection  may  be 
thoroughly  efficient,  yet  leave  many  harmless  and  hardy  forms  of  micro- 
scopic life  alive.  In  other  words,  sterilization  is  rarely  necessary  in 
public  health  work,  except  in  the  case  of  anthrax,  tetanus  and  other 
spore-bearing  infections  such  as  malignant  edema  and  the  gas  bacillus 
group. 

Antiseptics. — Antiseptic  substances  prevent  deconiposition  and  de- 
cay. Such  substances  retard  or  prevent  the  growth  and  activity  of  micro- 
organisms, but  do  not  necessarily  destroy  them :  that  is,  antiseptics  delay 
or  prevent  fermentation  and  putrefaction  without  destroying  the  micro- 

1351 


1352  GENERAL  CONSIDERATIONS 

organisms  which  cause  the  processes.  There  is  a  great  difference  be- 
tween the  antiseptic  and  the  disinfecting  power  of  most  substances.  For 
instance,  a  solution  of  formalin  will  restrain  the  development  of  most 
bacteria  in  the  proportion  of  1  to  50,000,  but  it  requires  a  3  to  10  per 
cent,  solution  of  this  liquid  to  kill  the  bacteria  in  a  reasonably  short  time. 
As  weak  a  solution  of  bichlorid  of  mercury  as  1  to  300,000  will  sometimes 
prevent  the  germination  of  anthrax  spores,  whereas  it  requires  a  1  to 
1,000  solution  to  destroy  them.  Saturated  solutions  of  salt  or  sugar 
will  preserve  meat,  vegetables,  and  other  organic  substances ;  that  is,  they 
are  antiseptic  in  their  action  but  not  germicidal,  as  they  have  small 
powers  of  destroying  microorganisms.  Cold  is  also  antiseptic  or  pre- 
servative in  action,  not  germicidal. 

Asepsis. — Asepsis  means  freedom  from  or  absence  of  living  patho- 
genic microorganisms.  Surgical  asepsis  may  be  achieved  through  physi- 
cal cleanliness  without  the  use  of  active  germicidal  substances. 

Germicide, — A  germicide  is  a  substance  or  agent  ivliicli  destroys 
germs.  Germicides  and  disinfectants  -  are  interchangeable  terms,  as 
both  are  used  to  indicate  the  destruction  of  microorganisms.  Many 
germicides  used  in  public  health  work  are  potent  enough  to  sterilize 
objects  with  which  they  come  in  contact. 

Deodorant. — A  deodorant  is  a  substance  tvhich  has  the  poiver  to 
destroy  or  to  neutralize  unpleasant  odors,  such  as  those  arising  from 
organic  matter  undergoing  fermentation  or  putrefaction.  Such  sub- 
stances must  be  distinguished  carefully  from  disinfectants.  Deodorants 
destroy  smells;  disinfectants  destroy  germs.  Many  of  the  disinfecting 
agents  are  also  deodorants,  but  all  deodorizing  substances  are  by  no 
means  disinfectants.  For  example,  charcoal  will  absorb  the  malodorous 
gases  arising  from  putrefying  and  fermenting  materials,  but  it  is  inert 
so  far  as  its  power  to  destroy  the  cause  of  these  processes  is  concerned. 
Formalin  and  ozone,  on  the  other  hand,  are  true  deodorants  and  disin- 
fectants, as  they  combine  with  the  organic  matter  to  form  new  com- 
pounds which  are  both  odorless  and  sterile.  Bichlorid  of  mercury,  while 
a  very  potent  germicide,  has  practically  no  immediate  effect  upon  odors. 
The  volatile  oils  and  other  substances  having  a  pungent  odor  are  not 
deodorants,  they  simply  cover  up  one  smell  with  another. 

Fumigation. — Fumigation  consists  in  liberating  fumes  or  gases  with 
the  object  of  destroying  germs,  vermin,  insects,  rats,  mice  and  other 
small  animals  acting  as  carriers  of  infection.  The  chief  fumigants  used 
in  public  health  work  are  formaldehyd  and  sulphur  dioxid;  to  a  less  ex- 
tent carbon  monoxid,  funnel  gases,  hydrocyanic  acid,  pyrethrum,  carbon 
bisulphid,  chlorin,  etc.  Most  of  these  are  very  poisonous  to  higher  forms 
of  life,  but  have  little  or  no  germicidal  power — excepting  formaldehyd 
which  is  a  good  germicide,  but  feeble  insecticide.  Fumigation  cannot 
take  the  place  of  disinfection;  gases  at  best  have  but  the  merest  surface 


OENEKAL  CONSTDERATTONS  1353 

action.  As  thoy  lack  tlic  power  of  pcnctralion  they  cannot  be  depended 
upon  to  disinfect  even  thin  t'al)rics,  or  surfaces  soiled  with  sputum  or 
similar  dischartres  in  which  the  virus  is  protected  against  the  fiimiiratin},' 
gas. 

Fumigation  is  chiefly  useful  in  ])rcventing  the  spread  of  insect-borne 
diseases. 

The  terms  fumi,s:ation  and  disinfection  have  been  much  confused. 
Because  fumigation  is  not  necessary  or  ineffective  after  some  of  the  com- 
municable diseases — the  word  has  gone  forth  that  disiufrciion  is  unnec- 
essary and  useless.  No  mistake  could  be  greater.  Fumigation  has  its 
place  and  its  limitations  in  ]niblic  health  work — so  also  disinfection. 

Nature's  Disinfecting  Agencies. — Tn  nature  many  forces  are  con- 
stantly at  work  to  destroy  infection  and  thereby  limit  the  spread  of 
the  communicable  diseases.  It  is  the  duty  of  the  sanitarian  to  encourage 
the  use  of  these  natural  disinfecting  processes;  they  are  dilution,  sun- 
light, dryness,  time  and  antibiosis.  Sunlight  is  a  great  destroyer  of  germ 
life.  Few  microbes,  especially  the  pathogenic  ones,  can  live  in  the  direct 
bright  sunlight  many  hours.  Dryness  is  another  natural  condition  that 
is  destructive  to  many  of  the  minute  forms  of  life  with  which  we  have 
to  contend.  The  combination  of  dryness  and  sunlight  is  quite  as  good, 
if  not  better,  than  the  ordinary  fumigating  processes  which  are  com- 
monly used  in  practical  disinfection  against  surface  contamination. 
Dryness,  sunlight,  and  cleanliness  are  the  keynotes  of  sanitation  in  the 
modern  acceptation  of  the  term. 

We  now  know  that  most  of  the  pathogenic  microorganisms  do  not 
grow^  and  multiply  in  our  environment.  For  the  most  part  they  soon  die 
when  wafted  into  the  air,  deposited  on  surfaces,  conveyed  in  water  or 
placed  in  the  soil.  It  is  only  occasionally  that  some  of  them  find  condi- 
tions favorable  for  development  in  foods  such  as  milk  and  meat,  and  ex- 
ceptionally in  water.  Further,  it  is  to  be  noted  that  ordinarily  it  requires 
a  certain  number  of  microorganisms  to  produce  infection.  It  is  quite 
likely  that  a  single  typhoid  bacillus  or  a  single  tetanus  spore  may  "kindle 
a  conflagration,"  but  experimental  evidence  with  the  infections  upon 
laboratory  animals  teaches  the  lesson  that  ordinarily  an  animal  is  capable 
of  taking  care  of  minute  amounts  of  infection,  particularly  if  attenuated. 
It  requires  at  least  ten  tubercle  bacilli  to  cause  tuberculosis  in  a  guinea- 
pig.  Dilution,  attenuation,  and  the  conditions  of  our  environment,  un- 
favorable to  most  germs  harmful  to  man,  therefore  protect  us  in  no  small 
measure  against  the  communicable  diseases.  This  is  one  reason  why  so 
many  of  the  communicable  infections  are  contracted  largely  throujh  close 
personal  association. 

Cleanliness. — Cleanliness  is  a  very  important  adjunct  to  the  work  of 
disinfection.  In  fact,  cleanliness  lies  at  the  base  of  all  our  sanitary  meas- 
ures.    The  mere  act  of  cleaning  removes  some  of  the  adherent  microbes 


1354  GENERAL  rOXSIDEEATTOXS 

from  the  surface  and  the  ordinary  scrubbing-  and  washing  result  in  the 
final  destruction  of  many  more.  Dry  dusting  and  sweeping  serve  only 
to  stir  up  dust  and  infection,  which  settle  down  again  upon  the  same 
or  other  surfaces.  Cleanliness  serves  another  important  purpose,  so 
far  as  infection  is  concerned;  it  removes  the  organic  matter  on  which 
and  in  which  bacteria  may  find  favorable  conditions  for  prolonging  life 
and  virulence.  The  modern  conception  of  cleanliness  has  expanded  with 
the  growth  of  the  sanitary  sciences.  We  now  aim  at  biological  cleanliness 
as  well  as  esthetic  cleanliness.  This  includes  not  only  the  removal  of 
organic  matter,  but  the  destruction  of  insects  and  vermin,  and  their 
feeding  and  breeding  places  (see  page  1006).  So  far  as  personal  clean- 
liness is  concerned,  the  two  important  acts  to  prevent  infection  are:  (1) 
Washing  the  hands  before  eating,  before  handling  food  and  after  leav- 
ing the  toilet;  and  (8)  keeping  the  fingers  away  from  the  mouth  and 
nose. 

The  surfaces  frequently  used  or  handled  by  the  public,  such  as  wood- 
work, seats,  floors,  desks,  door  handles  and  the  like  in  schools,  stores, 
factories,  shops  and  public  conveyances  and  assembly  places  should, 
when  practicable,  be  frequently  scrubbed  with  hot  soap-suds  and  strong 
soda  solution.  This  also  includes  the  seats  of  water-closets  and  privies, 
wash-basins,  and  other  objects  used  in  common. 

In  the  wholesale  disinfection  which  must  be  practiced  to  check  wide- 
spread epidemic  diseases  due  to  bacterial  infection  we  are  largely  limited 
to  the  use  of  the  agents  which  nature  has  constantly  at  work  to  destroy 
such  infection.  Against  a  single  case  of  communicable  disease  or  against 
a  limited  infected  area  we  may  employ  aggressive  measures  such  as 
steam  and  strong  chemicals;  but  when  a  disease,  due  to  bacterial  infec- 
tion, has  spread  over  an  extensive  district  these  methods  must  be  sup- 
plemented by  all  the  resources  of  nature.  The  people  must  be  educated 
so  as  individually  to  employ  intelligent  measures  to  avoid  the  infection. 
Cleanliness  must  be  more  scrupulously  practiced  than  ever,  sunlight  and 
dryness  must  be  given  their  fullest  opportunity  to  operate  even  at  the 
expense  of  a  few  faded  carpets  or  colors. 

Antibiosis  and  Symbiosis. — Many  pathogenic  microorganisms  are 
.destroyed  in  the  process  of  putrefaction  and  fermentation.  They  die 
in  the  fierce  struggle  for  existence  going  on  in  the  process  of  decom- 
position. For  the  most  part  the  hardier  saprophytic  forms  of  life  over- 
power and  kill  the  disease-producing  microorganisms  which  have  com- 
paratively feeble  powers  of  resistance.  The  fact  that  infected  carcasses, 
sewage,  and  putrid  organic  matter  generally  purify  themselves  by  the 
very  processes  that  destroy  them  is  a  fortunate  provision  of  nature. 

Ordinarily,  only  one  major  infection  is  active  in  the  same  individual 
at  one  time.  Symbiosis  is  noted  in  the  case  of  tetanus,  which  is  favored 
by  other  microorganisms.     Influenza  and  measles  invite  infection  with 


GENERAL  CONSIDERATIONS  1355 

the  pneiimocoecus  and  predispose  to  tuberculosis.  On  the  other  hand, 
there  are  curious  instances  of  antibiosis,  thus  sarcoma  may  disappear 
after  erysipelas. 

When  and  Where  to  Disinfect. — It  naturally  suggests  itself  that  it 
is  much  better  to  prevent  infection  than  to  be  compelled  to  destroy  it 
after  it  has  become  disseminated  through  ignorance,  carelessness,  or  neg- 
ligence. It  is  the  duty  of  the  disinfector  to  destroy  infection  wherever 
it  is  found ;  it  is  the  ideal  of  the  sanitarian  to  prevent  the  spread  of 
infection  so  as  to  render  broadcast  disinfection  unnecessary. 

The  best  place  to  apply  disinfection  is  at  the  seat  of  origin  of  the 
infection.  Man  is  the  fountain-head  of  most  of  the  infections  to  which 
he  is  heir;  hence  the  most  effective  place  to  practice  disinfection  is  at 
the  bedside.  The  excretions,  especially  those  from  the  mouth,  nose,  and 
bowels,  as  well  as  discharges  from  eruptions  and  wounds  most  frequently 
need  attention.  "When  proper  precautionary  measures  have  been  taken  at 
the  bedside  with  a  case  of  cholera,  typhoid  fever,  or  diphtheria  there  is 
little  need  of  subsequently  disinfecting  the  sickroom,  but  when  a  dif- 
fusion of  the  infection  results  then  a  general  disinfection  becomes  neces- 
sary. 

Qualifications  of  the  Disinfector. — The  disinfection  of  any  given 
place  is  a  complex  operation,  and  should  not  be  attempted  by  anyone  not 
familiar  with  the  peculiarities  of  the  particular  infection  with  which 
he  has  to  deal  and  a  thorough  knowledge  of  the  disinfecting  agents  em- 
plo3'ed.  In  other  words,  it  is  quite  as  important  to  know  what  to  disin- 
fect as  how  to  disinfect  and  when  to  disinfect.  A  thorough  understand- 
ing of  the  causes  and  modes  of  transmission  of  the  communicable  dis- 
eases is  the  most  useful  weapon  the  disinfector  has  in  his  fight  against 
the  spread  of  infection. 

The  success  of  the  disinfector  lies  in  personal  attention  to  minute 
details.  Germs  are  little  things,  and  it  is  little  things  that  count  in  this 
kind  of  work.  The  disinfector  who  is  satisfied  to  leave  the  process  in 
the  hands  of  an  inexperienced  person  with  a  few  words  of  instruction 
cannot  expect  to  obtain  trustworthy  results.  The  disinfector  must  give 
personal  surveillance  to  the  whole  process — the  materials,  the  strength  of 
solutions,  modes  of  application — and  must  be  present  to  guide  and  direct 
every  step  of  the  operation  with  the  same  conscientiousness  and  thor- 
oughness with  which  the  surgeon  assures  himself  of  every  detail  of 
asepsis  in  his  operating  clinic. 

Much  of  the  routine  disinfection  done  by  departments  of  health  is 
probably  ineffective,  although  the  procedure  is  faithfully  carried  out 
as  a  routine.  The  average  fumigating  squad  does  not  understand  the 
effect  of  temperature,  humidity,  outside  winds,  porosity  of  walls,  shape 
and  size  of  enclosures,  and  the  rate  of  application  and  other  factors  of 
the  gases  employed. 


1356  GEXEHAl.  COXSIDERATIOXS 

Controls.— Disinfecting  processes  should  be  controlled  by  exposing 
cultures  upon  paper  slips  or  threads  as  a  guide  and  check  to  the  thor- 
oughness of  the  process.  To  control  gaseous  disinfection,  saturate 
threads  with  an  active  culture  of  B.  prodigiosus.  These  threads  are 
attached  to  little  slips  of  paper  which  are  then  exposed  in  various  por- 
tions of  the  room  to  be  treated.  After  the  completion  of  the  operation 
the  threads  are  inoculated  into  Dunham's  peptone  medium.  If  the  B. 
prodigiosus  has  survived  the  characteristic  red  color  appears  in  the  cul- 
ture medium.  Suitable  control  exposures  should  also  be  used  from  time 
to  time  with  steam  disinfectors  and  other  apparatus. 

Disinfection  Must  Be  in  Excess  of  Requirements. — The  disinfection 
of  rooms,  bedding,  ships,  and  objects  that  have  been  exposed  to  infection 
must  of  necessity  be  greatly  in  excess  of  the  actual  requirements.  This 
is  one  of  the  diflficulties  met  with  in  attacking  an  invisible  foe.  A  sick- 
room might  readily  be  disinfected  and  rendered  safe  by  appljang  a  few 
gills  of  one  of  the  germicidal  solutions  to  a  small  spot  or  a  limited 
area.  But,  as  we  cannot  see  the  germs,  it  is  necessary  to  apply  our 
disinfecting  agents  to  every  inch  of  surface  of  the  room  and  all  its  eon- 
tents  in  order  not  to  miss  that  particular  spot.  At  first  disinfection  was 
directed  by  a  shotgun  process  in  a  general  sort  of  blunderbuss  way 
against  everything,  but  now  that  we  know  more  about  the  habits  and 
habitat  of  each  one  of  the  particular  microorganisms  we  can  concen- 
trate our  efforts  with  some  exactness  upon  the  particular  objects  liable 
to  transmit  infection,  and  with  greater  assurance  of  eradicating  danger. 

Specificity  of  Germicides. — There  are  few  universal  poisons  and  few 
if  any  general  germicides.  Most  disinfecting  substances  are  more  or  less 
specific  in  action.  Germicidal  agents  often  show  marked  selective  action 
towards  bacteria,  spirochetes,  protozoa,  algae  or  the  "ultra  microscopic" 
viruses.  Thus,  phenol  and  the  cresols  have  comparatively  feeble  action 
against  the  virus  of  smallpox,  vaccinia,  and  other  filterable  viruses. 
Copper  sulphate  is  a  specific  poison  against  algae.  Sodium  oleate  favors 
the  growth  of  gram  negative  cocci  of  the  Micrococcus  catarrhalis  group 
and  of  staphylococci,  while  pneumococci  and  streptococci  of  the  hemo- 
lytic and  S.  viridans  variety  fail  to  develop.^  Fuchsin  (Endo's  medium) 
suppresses  B.  coli,  but  does  not  inhibit  B.  typhosus.  Glycerin  kills  non- 
spore-bearing  bacteria,  but  preserves  filterable  viruses.  Gentian  violet 
and  other  para-rosanilin  dyes  kill  gram  positive,  but  not  gram  negative 
microorganisms.  Bile  salts  dissolve  pneumococci  and  restrain  the  growth 
of  staphylococci  and  streptococci,  but  favor  the  growth  of  typhoid  and 
colon  bacilli.  Ethylhydrocuprein  is  specific  for  the  pneumococcus.  Acri- 
din  with  mercuric  chlorid  has  remarkable  properties  of  penetrating  tis- 
sues. There  are  many  other  examples  of  selective  action.  Hence,  the 
killing  of  B.  typhosus  or  any  other  test  organism  is  not  a  proof  of  gen- 
W.  A.  M.  A.,  Dec.  21,  1918,  Vol.  LXXI,  p.  1050. 


(;K.\I:K'.\I.  CONSIDKK'A'rioXS  i;).-,r 

eral  (lisinfVctini,'  jtowcr.  'I'licre  is  a  tciHk'iicy  towards  tlio  (Icvclopinent 
of  specific  <;ernii(i(lal  a^j^ciits. 

Chemotherapy. —  Most  cells  of  the  luxly  are  more  easily  killed  than 
bacteria.  All  the  ordinary  germicides  used  in  ])ul)lic  health  work  are 
quite  destructive,  even  corrosive  to  the  tissues  of  the  body.  Since  Ehrlich 
found  that  "tlOt;"  (salvarsan)  will  kill  spirochetes  without  serious  in- 
jury to  the  body,  the  search  has  heen  to  find  specific  substances  that 
will  kill  the  parasites  without  harmiii^f  the  host. 

The  Ideal  Disinfectant. — The  ideal  disinfectant  must  fir.st  and  fore- 
most possess  a  high  germicidal  power.  Tt  must  not  be  rendered  ineffec- 
tive by  the  presence  of  organic  matter;  it  must  be  reasonably  stable,  so 
as  not  to  deteriorate  under  ordinary  conditions;  it  must  be  soluble  or 
readily  miscible  in  water;  if  it  forms  an  emulsion  the  emulsion  should  be 
permanent:  it  should  be  harmless  to  man  and  the  higher  animals;  it 
should  have  the  power  of  penetration :  it  should  not  corrode  metals, 
bleach,  rot  or  stain  fabrics,  and,  finally,  it  should  be  reasonable  in  price. 

The  stress  of  modern  activities  demands  disinfecting  processes  that 
are  instantaneous  in  their  action,  all-pervading  in  their  effects,  cheap, 
harmless,  and  free  from  unpleasant  odors  that  might  be  offensive  to 
the  fastidious.  Such  perfect  disinfectants  are  not  known.  It  requires 
money  and  the  expenditure  of  well-directed  and  intelligent  energ}-  to 
accomplish  satisfactory  disinfection.  No  one  suhstance  is  applicable  to 
all  diseases  or  to  all  substances,  or  even  to  the  same  disease  or  the  same 
substance  wider  different  conditions. 

Concurrent  disinfection  signifies  the  immediate  disinfection  and 
disposal  of  all  infected  material  during  the  course  of  the  illness.  It 
implies  the  prompt  disinfection  or  destruction  of  all  infected  discharges 
and  of  all  p.rticles  soiled  by  them.  Furthermore,  it  includes  the  puri- 
fication and  cleanliness  of  the  immediate  environment  of  the  patient 
so  as  to  check  the  spread  of  infection. 

Terminal  disinfection  signifies  the  precautions  taken  to  destroy  or 
purify  infectious  material  after  the  removal  of  the  patient  or  the  termi- 
nation of  isolation  or  quarantine,  the  object  being  to  destroy  infection 
or  to  kill  the  insects  or  animal  carriers  of  disease.  Terminal  fumigation 
finds  its  chief  usefulness  in  fighting  the  insect-borne  diseases. 

The  distinction  between  fumigation  and  disinfection  must  be  kept 
clearly  in  mind  (page  1352).  Terminal  fumigation  for  measles  and 
certain  frail  and  short-lived  viruses  is  not  necessary.  Furthermore, 
gases  such  as  formaldehyd  are  uncertain  in  practice,  and  have  the 
merest  surface  action.  Both  concurrent  and  terminal  disinfection  of 
discharges  and  objects  likely  to  convey  infection  will  always  remain  an 
important  measure  of  prevention. 

Terminal  fumigation  during  recent  years  has  been  disparaged  as  a 
public  health  measure  because  it  has  little  effect  upon  the  control  of  the 


1358  GEKEEAL  COXSIDEEATIOXS 

conimnni cable  diseases  and  tlie  cost  of  such  "disinfection"  appears  to  l)e 
disproportionately  large  to  the  benefits.  The  evident  limitations  of 
terminal  fumigation  have  cast  doubt  in  the  minds  of  some  health  officers 
upon  the  value  of  disinfection  in  general.  This  is  an  unfortunate  at- 
titude. No  one  can  question  the  great  value  of  disinfection  properly 
applied.  It  is,  of  course,  much  more  important  to  destroy  the  infective 
discharges  throughout  the  course  of  a  case  of  typhoid  fever  than  to 
trust  to  one  tinal  disinfection  of  the  sick-room  and  its  contents.  The 
same  holds  with  about  equal  force  for  most  of  the  communicable  diseases. 
We  now  know  that  fomites  play  a  comparatively  minor  role  in  the 
transmission  of  disease.  The  disinfection  of  rooms  and  objects  does 
not  now,  therefore,  hold  the  importance  in  the  minds  of  sanitarians  that 
it  once  did.  However,  if  terminal  disinfection  prevents  the  occurrence 
of  only  a  small  number  of  cases  it  would  still  seem  to  be  worth  while. 
Moreover,  what  health  officer  would  willingly  allow  his  child  to  occupy 
the  bed  or  handle  the  objects  in  a  room  soon  after  a  case  of  typhoid, 
scarlet  fever,  tuberculosis,  or  diphtheria  without  first  applying  some 
effective  method  of  purification?  The  greater  the  care  and  cleanliness 
exercised  during  the  progress  of  the  disease  the  less  the  need  of  terminal 
disinfection.  A  good  cleansing  of  surfaces  with  soap  and  w^ater,  fol- 
lowed by  an  application  of  bichlorid,  carbolic  acid,  or  one  of  the  cre- 
sol  preparations  is  a  more  effective  method  of  disinfection  than  formalde- 
hyd  gas,  which  is  the  best  of  the  gaseous  agents.  Cleansing,  renovating, 
airing  and  sunning  of  the  room  should  always  be  the  final  process. 

The  principal  oojects  that  need  disinfection  are  the  discharges  from 
the  body;  towels,  bedding,  handkerchiefs  and  fabrics;  food,  tableware 
and  other  objects  that  have  been  mouthed,  and  finally  the  hands  of  the 
nurse,  physician  and  others  who  come  in  contact  with  the  infection. 

Penetration. — In  practical  disinfection  a  certain  amount  of  penetra- 
tion is  almost  always  called  for.  Most  germicides  penetrate  poorly  and 
slowly.  As  a  rule,  substances  in  solution  penetrate  better  than  substances 
in  emulsion.  Gaseous  substances  cannot  be  depended  upon  to  penetrate 
at  all.  They  have  only  the  merest  surface  action.  Feces  and  sputum 
are  not  only  the  most  difficult  to  penetrate,  but  also  the  most  important 
because  so  apt  to  contain  virulent  pathogenic  microorganisms  through- 
out their  mass.  No  germicidal  agent  can  be  depended  upon  to  permeate 
a  fecal  mass  under  ordinary  conditions  in  a  reasonable  time.  It  is, 
therefore,  most  important  that  such  substances  be  thoroughly  disinte- 
grated and  the  germicide  incorporated  through  the  mass.  Bacteria 
in  nature  are  usually  imbedded  in  various  substances  which  differ 
greatly  in  consistency  and  composition,  and  therefore  practical  disinfec- 
tion calls  for  stronger  solutions  and  longer  time  than  indicated  by  labora- 
tory tests  upon  the  naked  germ  cells.  In  certain  instances,  where  pene- 
tration is  required,  trust  should  only  be  placed  in  steam,  dry  heat,  or 


GEXFT^AL  rOXSTDERATIOXS  1359 

boilinfi:.  Dry  heat  has  poor  powers  of  penetration  compared  with  steam. 
Tlie  penetration  of  steam  and  of  gases  is  facilitated  by  a  prior  vacuum. 
None  of  the  ordinary  chemicals  can  be  trusted  to  penetrate  upholstered 
furniture,  mattresses,  pillows,  thick  blankets  and  the  like. 

Organic  Matter. — Or^^anic  matter  seriously  interferes  with  the  effi- 
ciency of  almost  all  ^^ermicidal  agents.  Chlorinated  lime,  ozone,  hydro- 
gen peroxid,  potassium  permanganate,  and  other  active  oxidizing  agents 
attack  organic  matter  with  avidity  and  are  thus  soon  used  up.  The  metal- 
lic salts  coagulate  organic  matter,  thus  automatically  impeding  further 
ingress.  Formaldehyd  and  phenol  show  less  reduction  of  power  in  the 
presence  of  organic  matter  than  perhaps  any  of  the  otlier  germicides. 

In  nature,  bacteria  are  usually  imbedded  in  organic  matter.  The 
way  in  which  organic  matter  handicaps  germicidal  action  has  been  shown 
by  many  investigators.  Behring  found,  for  example,  that  anthrax  bacilli 
suspended  in  water  are  killed  in  a  few  minutes  with  bichlorid  of  mercury 
1-500,000 ;  in  bouillon  it  required  1-40,000 ;  while  in  blood  serum  1-2,000 
was  not  always  effective. 

Time. — Time  is  an  essential  factor  too  frequently  disregarded  in  dis- 
infecting with  liquids — suspension  or  solution.  Very  few  chemical  dis- 
infectants act  instantly,  even  in  strong  solutions,  and  under  favorable 
conditions.  The  microorganisms  are  so  often  in  clusters  or  are  sur- 
rounded by  mucoid  films  or  are  so  imbedded  in  organic  matter  that  a 
considerable  time  is  required  for  the  disinfecting  solution  to  penetrate  to 
the  germ.  If  the  microbes  are  dry  it  takes  a  certain  time  to  wet  them 
before  the  chemical  can  act.  These  and  other  factors  must  be  added  to 
the  time  actually  necessary  for  the  substance  to  destroy  the  life  of  the 
germ  after  it  comes  in  direct  contact  with  it. 

It  is  well-known  that  some  germicides,  particularly  the  metallic  salts, 
if  given  sufficient  time,  will  eventually  kill  in  exceedingly  weak  dilu- 
tions. Mercuric  chlorid,  according  to  Chick  and  Martin,  will  act  as  a 
germicide  in  a  dilution  of  1  to  1,000,000  if  given  sufficient  time.  The 
action  of  copper  sulphate  in  exceedingly  weak  dilutions  on  algae  is  also 
of  interest  in  this  connection.  Some  disinfectants,  on  the  other  hand, 
exert  their  most  useful  action  promptly,  and  are  then  rapidly  used  up 
by  being  oxidized  or  neutralized  and  thus  lose  their  power. 

Chick  found  a  logarithmic  ratio  between  concentration  of  disinfect- 
ant and  the  time  taken  to  disinfect.  She  found,  furthermore,  that  the 
phenol  coefficient  of  mercuric  chlorid  with  B.  iypliosus  varies  greatly 
with  the  prolongation  of  exposure.     Thus : 

Phenol  coefficient  of  HgCL    2.5  minutes  exposure  =    13.5  coefficient. 

This  is  an  interesting  side  light  on  the  Kideal- Walker  technic  which, 
until  recently,  permitted  a  latitude  of  time  of  comparison  varying  from 


1360 


GENERAL  CONSIDERATIONS 


23/>  to  15  minutes.  This  wide  variation  of  the  coefficient,  however,  is 
found  mainly  in  the  ease  of  the  metallic  salts. 

Time  is  an  exceedingly  important  element  in'  disinfection.  It  is  not 
sufficient  simply  to  dip  the  hands  in  and  out  of  a  bichlorid  solution, 
to  rinse  fabrics  in  carbolic  acid  solution,  or  to  pour  formalin  over  feces. 
It  takes  time  to  penetrate  and  then  to  kill.  Further,  the  speed  of  the 
reaction  varies  with  each  substance,  and  depends  upon  the  concentra- 
tion and  also  the  temperature. 

Speed  of  Bisinfection  and  Stability  of  Disinfectants. — A  knowledge 
of  the  speed  with  which  a  disinfectant  acts  is  essential  to  an  understand- 
ing of  the  conditions  under  which  it  may  be  used  to  best  advantage. 
The  speed  of  disinfection  is  an  important  factor,  for  it  varies  enor- 
mously with  different  types  of  substances.  Germicides  of  the  chlorin 
group  and  iodin  are  among  the  most  rapid,  while  dyes  and  some  metal- 
lic salts  are  relatively  slow.  As  a  general  rule,  germicides  that  act 
promptly  are  quickly  decomposed  or  neutralized.  Stable  germicides  act 
slowly,  unstable  germicides  act  quickly.-  A  list  of  germicides  with  ref- 
erence to  these  factors  follows : 


INORGANTC   DISINFECTANTS 


Hydrogen  peroxid 

derivatives. 
Chlorin, 


and  some  of  its 


Hypochlorous  acid  and  its  salts, 
salts 


Bromin  and  iodin. 
Boric  acid  and  its 
Mercury  salts. 


Bismuth  salts. 
Zinc  salts. 


Unstable,  easily  decomposed  during 

disinfection. 
Unstable,  easily  decomposed  during 

disinfection. 
Unstable,  easily  decomposed  during 

disinfection,. 
Less  unstable  than  chlorin. 
Stable. 
Often    inactivated   by   precipitation 

or  otherwise. 
Often    inactivated    by   precipitation 

or  otherwise. 
Often    inactivated   by   precipitation 

or  otherwise. 


ORGANIC   DISINFECTANTS 


Alcohol,  ether,  etc. 
Iodoform 
Formaldehyd 

Hexamethylenetetramin  and  its  de- 
rivatives. 
Aromatic  chloramins. 

Phenols,  naphthols  and  derivatives. 
Dyes,  such  as  malachite  green,  acri- 
flavine,  etc. 


Stable. 

Fairly  stable. 
Unstable. 
Mostly  stable. 

Unstable,  easily  decomposed  during 
disinfection. 

Mostly  stable.' 

Mostly  stable,  thougli  sometimes  re- 
duced to  leuko-fdrms  and  often 
adsorbed  by  tissues. 


Temperature. — There  is  a  complete  analogy  existing  between  a  chem- 
ical reaction  and  disinfection,  one  reagent  being  represented  by  the  dis- 
infectant and  the  other  by  the  protoplasm  of  the  bacterium.    Chick  states 


GENERAL  CONSIDERATIONS  13G1 

that  llio  velocity  of  disinfection  increases  with  the  rise  in  Icinpcrature  in 
a  manner  similar  to  that  of  a  chemical  reaction,  in  fact,  the  tempera- 
ture so  greatly  inlluences  the  disinfecting  i)()\vcr  of  liciuids  that  it  is 
strongly  recommended  always  to  use  w^arm  solutions  in  actual  practice. 
Even  slight  changes  of  temperature  may  make  a  great  difference.  Feeble 
antiseptic  solutions  become  strong  germicides  when  warmed.  Phelps 
claims  that  as  the  temperature  increases  arithmetically,  the  velocity  of 
rftaction  increases  geometrically.  This  is  not  a  general  rule  applicable 
for  all  disinfectants,  for  Chick  showed  that  the  germicidal  power  of  the 
metallic  salts  increases  2  to  4  fold  for  each  rise  of  10°  C.,  while  phenol 
usually  rises  7  to  8  fold  for- each  similar  change  in  temperature. 

A  good  instance  of  the  effect  of  temperature  is  given  by  Heiden,  who 
found,  that  anthrax  spores  which  survived  the  effects  of  a  5  per  cent, 
carbolic  solution  for  3G  days  at  room  temperature  were  destroyed  in 
half  an  hour  in  the  same  solution  at  55°  C.  At  75°  C.  it  took  only  3 
minutes  to  kill  them.  A  3  per  cent,  carbolic  acid  solution  killed  the 
same  spores  at  this  temperature  in  15  minutes  and  a  1  per  cent,  solu- 
tion in  from  2  to  2i/)  hours. 

It  is  important  to  remember  that  the  temperature  registered  hy  the 
thermometer  of  the  apparatus  is  rarely  a  true  index  of  the  temperature 
of  the  things  to  be  disinfected.  This  is  a  common  source  of  error  in 
the  use  of  autoclaves  and  sterilizers  where  large  objects  or  masses  are 
heated,  such  as  cans  of  food,"  bundles  of  bandage,  bales  of  fabric,  or 
quantities  of  clothing.  The  temperature  recorded  on  the  thermometer 
of  the  sterilizer  is  usually  higher  than  the  actual  temperature  within  the 
apparatus.  Good  sterilizing  technic  is  essential  and  a  factor  of  safety 
desirable.  The  time  necessary  for  penetration  must  be  taken  into  ac- 
count. 

The  critical  temperature  in  the  center  of  bales,  bags,  cans,  etc., 
can  be  determined  with  the  thermo-couple  or  special  recording  ther- 
mometers. In  the  use  of  steam  under  pressure,  the  temperature  is  a 
more  reliable  guide  than  the  pressure. 

Emulsions  and  Solutions. — As  a  rule  an  emulsion  has  greater  germi- 
cidal power  than  a  solution.  Thus  soapy  and  resinous  emulsions  of  the 
phenols  may  accentuate  the  germicidal  power  of  these  substances.  Chick 
and  Martin  have  observed  that  the  particles  of  an  emulsion  or  soapy 
preparation  of  the  coal-tar  acids  exhibit  active  Brownian  motion.  The 
bacteria  are  considerably  larger  than  the  mean  diameter  of  the  emulsi- 
fied particles.  The  bacteria  may  plainly  be  seen  to  be  bombarded  by 
these  particles.  In  this  way  the  bacteria  are  frequently  brought,  into 
intimate  contact  with  the  undiluted  particles  of  pure  coal-tar  acids. 
The  maximum  effect  may  therefore  be  obtained  and  the  death  of  the  bac- 
teria is  inevitable.  Such  concentration  about  the  bacteria  is  not  likely 
to  occur  with  substances  in  solution.    The  coal-tar  acids  in  suspension  act 


1362  GENERAL  CONSIDERATIONS 

upon  the  bacteria  first  through  adsorption,  and  then  through  chemical 
combination.  The  bacteria  rapidly  become  surrounded  by  the  disin- 
fectant in  a  much  greater  concentration  than  actually  exists  within  the 
liquid.  Other  particular  matters  present  have  the  same  power  of  adsorp- 
tion, and  their  presence  therefore  interferes  with  the  germicidal  value 
of  substances  in  emulsion.  Thus  the  value  of  phenol  in  solution  is  barely 
impaired  by  the  presence  of  organic  matter  while  emulsified  disin- 
fectants are  reduced  to  one-third  or  one-half  their  original  value.  That 
germicidal  substances  in  emulsion  fail  to  penetrate  may  be  demonstrated 
by  pouring  one  of  the  coal-tar  emulsions  upon  a  fecal  mass;  a  layer  of 
the  coal-tar  creosotes  soon  collects  upon  the  surface,  plainly  visible  as 
a  film. 

Dilution. — There  must  be  a  sufficient  amount  of  the  substance  used 
so  that  it  shall  be  present  throughout  the  whole  mass  in  the  proportion 
required.  Thus  an  agent  that  is  effective  in  a  2  per  cent,  solution  cannot 
be  used  in  that  strength  to  disinfect  an  equal  volume  of  an  infected 
liquid,  since  the  mixture  would  then  contain  but  1  per  cent.  This  is 
particularly  important  in  the  disinfection  of  urine,  feces,  sputum,  vom- 
itus  and  the  like. 

Reaction. — Some  germicides  are  acid,  others  alkaline ;  the  substances 
to  be  disinfected  also  vary  in  reaction.  Thus  lime  .is  an  alkali,  and 
if  used  to  disinfect  an  acid  substance  enough  must  first  be  added  to 
neutralize  the  medium  and  then  an  additional  amount  of  lime  must  be 
added  necessary  to  accomplish  the  disinfection.  In  the  same  way,  if 
mercuric  chlorid  is  added  to  solutions  containing  sulphids,  caustic 
alkalies,  or  certain  metallic  salts,  sufficient  must  be  added  in  order  to 
first  precipitate  these  substances  and  then  enough  more  added  to  exert 
its  disinfecting  action.  Likewise,  the  greater  the  number  of  germs  to 
be  destroyed  the  greater  the  amount  of  the  disinfectant  required  to  ac- 
complish the  purpose. 

The  Mechanism  of  Bactericidal  Action. — Chemical  substances  and 
physical  agents  act  in  a  great  variety  of  ways  to  bring  about  the  destruc- 
tion of  bacteria.  Just  how  the  microbes  are  poisoned  is,  in  many  in- 
stances, an  unsolved  problem  in  toxicology.  It  must  be  self-evident  that 
disinfectants  act  in  different  ways,  especially  when  we  consider  such 
widely  diverse  substances  as  acids,  metallic  salts,  phenols,  ozone,  bleach- 
ing powder,  and  chloroform. 

Kronig  and  Paul,^  as  early  as  1897,  established  the  important  known 
facts  in  a  classic  contribution.  They  showed  that  the  toxicity  of  the 
metallic  salts  depends  upon: 

(1)  The  concentration  of  the  metallic  salt. 

(2)  The  specific  property  of  the  salt. 

^Zeitschr.  f.  Eyg.,  25,  p.  1,  1897. 


ORXEIJAL  CONSIDEHATIONS  13G3 

(0)  'I'ho  type  (if  .<(il\ciit. 

(1)  'I'lie  (li'<;r('e  of  disMxiiition   of  the  salt. 

(5)  The  effect  of  the  cation. 

(6)  The  effect  of  the  anion. 

(7)  The  effect  of  the  nndissociated  salt. 

Witli  regard  to  the  acids,  the  toxicity  depends  upon : 

(S)  The  electrolytic  dissociation,  that  is,  the  concentration  of 
hydrogen  ions  in  solutidii.  Tn  a  few  instances,  the  anions  have  a 
specific  loxic  effect. 

The  toxicity  of  the  bases  is  in  accordance  with: 

(9)  Tiieir  dissociation  power,  tliat  is,  with  the  concentration  of 
hydrogen   ions   in   sohition. 

The  disinfecting  power  of  the  halogens : 

(10)  Increase  with  their  atomic  weight. 

The  oxidizing  chemicals  are  toxic: 

(11)  In  proportion  to  their  oxidizing  power. 

With  regard  to  negative  and  positive  catalysis,  they  foimd  that: 

(12)  Anything  that  will  increase  the  dissociation  will  increase  the 
toxicity. 

(13)  The  alcohols  are  positive  catalyzers  when  acting  on  the  metal- 
lic salts,  and  negative  catalyzers  when  in  solution  of  phenol  and  for- 
maldehyd. 

(14)  Bouillon,  gelatine  and  the  body  fluids  are  negative  catalyzers 
in  metallic  salt  solutions. 

Kronig  and  Paul  recognized  the  probability  of  the  existence  of  cer- 
tain general  arbitrary  laws  between  the  concentration  and  toxicity  of  the 
metallic  salts. 

In  1908,  Chick,^  using  the  figures  obtained  by  Kronig  and  Paul 
in  1897,  and  those  later  obtained  by  Madsen  and  Nyman  *  in  1907,  and 
supplementing  these  results  with  a  number  of  her  own  obtained  with 
anthrax  spores,  was  able  to  show  a  close  similarity  between  the  process 
of  killing  and  the  equation  for  a  unimolecular  reaction  embodying  Guld- 
berg  and  Waage's  law.  Her  experiments  with  B.  paratypliosus  showed  a 
departure  from  this  simple  law  which  she  explained  as  due  to  permanent 
differences  in  resistance  to  disinfectants  among  individual  organisms. 

In  1918,  Brooks,^  using  the  rate  of  hemolysis  of  blood  cells,  con- 

^Journ.  of  Hyg.,  8,  p.  92,  1008;   also  10,  p.  2.38.  1010. 

*Zeiischr.  f.  Hifcj.,  57,  p..  388,  1907. 

'Jourti.  Gen.  Physiologif,  ^cpi-  20,  1918,  I,  Xo.  1.  p.  01. 


13G4  GENERAL  CONSIDERATIONS 

eluded  that  disinfectants  do  not  follow  the  unimolecular  law.  He  be- 
lieves that  the  fundamental  reaction  may  be  either  a  simple  process  or  the 
expression  of  a  complex  scries  of  changes,  whose  rate  is  at  all  times 
governed  by  that  of  the  slowest  of  the  series. 

The  conception  that  disinfection  resembles  a  chemical  reaction,  the 
disinfectant  representing  one  reagent  and  the  bacterium  the  other,  is  of 
great  importance  since  the  cardinal  points  of  efficient  disinfection, 
namely,  adequate  active  mass,  or  concentration  of  the  germicide,  time  of 
action,  and  perfect  contact  are  thereby  experimentally  established. 

The  Choice  of  Grermicide. — The  choice  of  tlie  germicide  depends  some- 
what on  the  nature  of  the  substance  to  be  disinfected,  as  well  as  upon 
the  resistance  of  the  virus.  Ordinarily  germicidal  solutions,  such  as 
bichlorid  of  mercury,  1-1,000,  or  carbolic  acid.  21/0  per  cent.,  cannot  be 
trusted  to  kill  tetanus  spores;  emulsions  are  not  serviceable  for  the 
disinfection  of  feces;  a  weak  chlorinated  lime  will  disinfect  water, 
but  a  strong  solution  is  necessary  to  disinfect  fabrics,  but  the  strong 
solution  bleaches  and  rots  the  fiber.  "  Certain  chemicals  have  a  se- 
lective action  and  appear  to  l)e  specific  poisons  for  some  organisms  as, 
for  example,  copper  sulphate  for  algae.  On  the  other  hand,  carbolic 
acid  is  particularly  ineffective  against  the  virus  of  smallpox.  Taken 
altogether,  therefore,  the  choice  of  the  chemical,  its  strength,  and  time 
of  application,  the  temperature  of  the  solution,  and  its  method  of  em- 
ployment, are  all  problems  wliich  must  be  solved  for  each  particular  class 
of  infection,  and  each  particular  group  of  substances. 


THE  STANDARDIZATION  OF  DISINFECTANTS 

There  is  no  accurate  standard  by  which  the  power  of  disinfecting 
agents  may  be  measured.  There  are  conditions  influencing  the  life  of 
the  bacterial  cell  which  we  are  unable  to  control.  It  is  for  this  reason 
that  the  strengths  of  solutions  necessary  to  disinfect  are  variously  stated 
by  different  authorities,  and  the  time  of  exposure  is  for  the  same  reason 
not  always  definitely  decided.  The  difficulty  in  this  connection  is  to  de- 
termine the  minimum  conditions  which  will  furni'^h  trustworthy  results 
and  still  provide  a  coefficient  of  safety  necessary  for  general  practice.  Of 
still  greater  importance  is  the  fact  that  our  laboratory  tests  do  not  imi- 
tate the  natural  conditions  under  which  bacteria  are  commonly  found  in 
nature.  The  requirements  of  practical  disinfection  are  therefore  usually 
much  more  severe  than  the  conditions  of  our  laboratory  tests. 

While  the  results  of  scientific  work  in  the  laboratory  must  be  our 
guide  as  to  the  value  and  efficiency  of  any  disinfecting  process  we  can- 
not ignore  the  results  of  experience  gained  in  actual  practice  in  combat- 
ing the  communicable  diseases.     This  is  .especially  triie  of  disinfectants 


THE  STANDARDIZATION  OF  DISINFECTANTS       13Go 

used  aiitiiiist  a  disi'iisc  the  cause  of  which  is  only  surmised  or  the  mode  of 
transmission  not  definitely  known.  We  have  had  a  lesson  on  this  point 
in  the  case  of  snl]ihur.  This  substance  had  long  been  used  as  a  disin- 
fectant for  yellow  fe\'cr,  and  jn'actical  experience  had  justified  the  con- 
fidence placed  ill  sulpliiir  fumiiration  to  check  the  spread  of  this  disease, 
but  when  the  scientific  tests  made  in  the  laboratory  showed  that  sulphur 
dioxid  is  a  very  poor  germicide,  discredit  was  thrown  upon  it;  now  that 
we  know  that  sulphur  dioxid  is  one  of  the  best  insecticides,  confidence  has 
been  restored  both  as  to  the  scientific  and  practical  value  of  this  substance. 

On  the  other  hand,  laboratory  experiments  have  established  with 
great  accuracy  the  value  and  reliability  of  certain  disinfectants  which 
otherwise  would  have  been  overlooked.  Thus  the  value  of  corrosive  sub- 
limate, chlorinated  lime  and  formaldehyd  was  established,  while  on  the 
other  hand  some  substances,  such  as  zinc  chlorid  and  sulphate  of  iron, 
have  been  robbed  of  the  high  place  in  which  they  were  formerly  held, 
and  placed  near  the  bottom  of  the  list  of  disinfectants.  Even  car- 
bolic acid  has  been  shown  to  have  less  germicidal  power  than  was 
formerly  supposed. 

Methods  of  Standardizing  Disinfectants. — Pringle  ^  as  early  as  1750 
attempted  to  standardize  the  then  knowTi  antiseptics  by  determining 
their  power  to  preserve  (i.  e.,  prevent  decomposition  in)  a  mixture 
consisting  of  2  grains  of  meat  and  60  grains  of  sea  salt  in  2  ounces  of 
water.  Following  Pringle's  work  little  ^vas  accomplished  for  over  100 
years  in  standardizing  disinfectants  until  Koch  started  a  new  era  by  the 
use  of  pure  cultures  and  the  "thread  method." 

The  Thread  Method. — Koch  ^  in  1881  used  pure  cultures  of  B. 
prodigiomis,  B.  pyocyaneiis,  and  B.  anthracis,  both  with  and  without 
spores.  He  soaked  threads  in  a  culture  of  the  test  organism  and  after- 
ward dried  them  for  various  periods  and  then  exposed  these  infected 
threads  to  the  action  of  the  disinfectant  to  be  tested.  The  threads  were 
then  washed  and  laid  on  the  surface  of  a  solid  nutrient  medium  and 
incubated  for  growth.  This  method,  although  characterized  by  greater 
scientific  accuracy  than  the  methods  previously  used,  lacked  perhaps 
those  broader  features  of  the  older,  rougher  experiments;  that  is,  the 
method  did  not  approximate  the  conditions  met  with  in  practical  disin- 
fection closely  enough.  Koch's  reports,  so  favorable  to  bichlorid  of  mer- 
cury, gave  a  great  impetus  to  its  use.  Geppert,^  however,  soon  made  it 
plain  that  Koch's  high  regard  for  bichlorid  of  mercury  was  partly  due 
to  an  overestimate  of  its  destroying  power,  inasmuch  as  the  thread  may 

^Phil.  Trans,  of  the  Roy.  Soc.  of  London.  XLVI,  525. 

'  Berl.  klin.  Wchnschr..  1889,  XXVI,  789;  also  Deuisch.  med.  Wchnschr.. 
1891,  XVII,  797. 

*  "Mitteilungen  aus  dem  kaiserlichen  Gesundheitsamte,"  I,  1881,  p.  324, 
abstracted  bv  \Miitelegge,  in  "Recent  Essays,"  New  Sydenham  Society,  London, 
1886,  CXV,  p.  493. 


1366  GENERAL  CONSIDEEATIONS 

carry  over  a  sufficient  amount  of  the  chemical  to  inhibit  growth.  Gep- 
pert  used  ammonium  sulphid  to  precipitate  the  mercury  and  thereby 
demonstrated  a  lower  figure  as  to  its  germicidal  power. 

Sternberg's  Method.^ — As  early  as  1881  Sternberg  described  a 
method  that  is  evidently  the  precursor  of  the  "carbolic  coefficient"  and 
its  various  modifications.  He  mixed  5  c.  c.  of  a  young  culture  with 
equal  quantities  of  a  solution  of  the  germicidal  agent.  Thus  5  c.  c.  of 
a  1  to  200  solution  of  carbolic  acid  would  be  added  to  5  c.  c.  of  a  recent 
culture  of  typhoid,  and  after  stated  intervals  1  or  3  loopfuls  would 
be  transferred  to  a  nutrient  medium. 

The  Garnet  Method. — The  Garnet  method  proposed  by  Kronig  and 
Paul  ^**  in  1897  was  an  attempt  at  a  more  precise  method.  Small  garnets 
of  uniform  size  are  coated  with  an  emulsion  containing  sporulating  an- 
thrax bacilli.  These  are  dried  and  then  dropped  into  the  disinfecting 
solution.  After  exposure  for  stated  intervals  the  garnets  aye  removed, 
rinsed,  and  the  organisms  washed  off  in  sterile  water,  plated,  and  counted. 
Kronig  and  Paul  emphasized  the  necessity  of  the  disinfectant  reaching 
each  organism,  the  subsequent  washing  of  the  disinfectant  from  each, 
organism,  and  the  performance  of  the  test  with  a  constant  number  of 
organisms,  since  the  time  required  for  disinfection  is  dependent  upon 
the  number  of  microorganisms  present.  This  method,  along  with  the 
thread  method  of  Koch,  has  been  supplanted  by  the  "carbolic  coefficient" 
of  Eideal  and  Walker  and  modifications  thereof. 

Carbolic  Coefficient. — Eideal  and  Walker"  in  1903  introduced  a 
method  by  which  they  proposed  to  determine  and  state  in  definite  numer- 
ical terms  the  value  of  any  disinfectant.  This  they  called  the  "carbolic 
coefficient,"  for  the  reason  that  carbolic  acid  is  taken  as  the  unit  of 
measurement  against  which  the  germicidal  power  of  all  other  substances 
is  compared.  It  is  often  spoken  of  as  the  "Eideal-Walker"  method  or 
the  "drop"  method,  because  one  drop  of  the  culture  of  B.  typhosus  was 
used  for  each  c.  c.  of  disinfectant  tested. 

Eideal  and  Walker  opened  a  new  era  in  the  standardization  of  dis- 
infectants. They  prepared  a  number  of  standard  conditions  for  the 
test,  without  which  comparable  results  are  not  possible.  The  most  im- 
portant conditions  are  temperature,  media,  nature  and  age  of  the  test 
microorganisms,  time  of  exposure,  degree  of  dilution,  etc.  The  Lancet 
Commission  ^^  in  1908  recommended  several  modifications  of  the  Eideal- 

^Bull.  of  Natl.  Bd.  of  Health,  U.  8.  A.,  1879,  I,  219,  227,  237  and  265, 
and  1881,  III,  23.     Sternberg's  "Manual  of  Bacteriology,"  K  Y.,  1873,  p.  186. 

^"  "Die  chemischen  Grundlagen  der  Lehre  von  der  Giftwirkung  und  Disin- 
fektion,"  Zeit.  f.  Hyg.,  Leipzig,  1897,  XXV,  1. 

"  "The  Standardization  of  Disinfectants,"  Jour,  of  Roy.  San.  Inst.,  1903, 
XXIV,  424;  also  Jowr.  of  Infect.  Dis.,  1912,  X,  254,  and  Am.  Jour.  Pub.  Health, 
913,  III,  575. 

""The  Standardization  of  Disinfectants,"  Lancet,  1909,  II,  1454,  1516,  and 
1612. 


THE  STAXDAUDI/ATIOX   ()F   DISINFECTANTS       IfiOr 

Walker  Icclinic  ami  this  iii<'tli(M]  was  fui'llici-  iiKMlillcd  Kv  Amlcrsdii  nii<l 
Mc'Ciiutic  ^^  wild,  ill  i:i|  l,  |)i-(i|iiiscil  cci-tain  cliaiiLics  in  Icclinic.  ainl  a  dif- 
ferent ni<>tlu)(l  t)!"  talciilatin^'  ilu;  {•oollicioiil,  which  Ihcy  termed  the 
"phenol  coefficient."  Stinison  '*  described  a  machine  by  Avhicli  the  test- 
ing may  be  facilitated. 

Kendall  and  Edwards'"  in  1911  described  an  infected  agar  plug, 
designed  to  test  the  penetrating  power  of  a  disinfectant. 

PJnjsicnl-Chcmical  Methoih. — It  remains  to  cite  the  admiralde 
work  of  Chick  and  Martin  ^^  upon  the  laws  of  disinfection.  They  pro- 
posed in  1908  that  the  time  element  be  established  arbitrarily  and  with 
this  called  for  tw'O  other  constants,  namely,  the  number  of  bacteria  ini- 
tially present,  and  the  temperature.  They  believed  that  the  killing  of 
bacteria  simulates  a  monomolecular  reaction  in  which  the  bacteria  take 
the  place  of  one  of  the  reacting  substances.  Phelps  ^'^  in  1911  made  the 
interesting  proposal  to  determine  the  germicidal  value  of  a  disinfectant 
at  any  temperature  and  concentration  by  a  mathematical  formula  which 
would  use  the  findings  of  a  single  experiment  of  comj^aratively  easy 
technic. 

Carbolic  CoeiScient  Method. — This  test,  sometimes  known  as  the 
Rideal-Walker  method  of  standardizing  disinfectants,  has  been  vari- 
ously modified  and  improved.'^  As  modified  it  is  at  present  the  best 
method  we  have  for  comparing  the  strengths  of  germicidal  substances  in 
solution  or  suspension.  The  method,  however,  has  distinct  limitations, 
as  it  only  gives  information  concerning  the  relative  value  of  germicides 
npon  the  naked  germ  cells  imder  comparatively  favorable  conditions  of 
action. 

In  order  to  obtain  results  that  may  have  comparative  value  and  to 
avoid  discrepancies  it  is  of  the  greatest  importance  to  keep  all  the  factors 
of  the  test  uniform  and  to  give  attention  to  every  detail.  The  following 
are  the  more  important  factors  and  principles  upon  which  this  test  is 
based : 

Time. — The  time  is  taken  as  the  constant  and  the  strength  of  the 
disinfectant  as  the  variant.  It  is  easy  to  demonstrate  that,  if  reversed, 
totally  erroneous  results  will  be  obtained. 

^^Hyg.  Lai.  Bull.,  P.  H.  &  M.  H.  S.,  Xo.  82. 

^^Eeprint  Xo.  462,  U.  S.  Pub.  Health  Rpts..  Apr.   12,   191S. 

"^Jour.  of  Infect.  Dis.,  1911,  VIII,  2.50. 

'"Chick,  Harriet:  Jonr.  of  Hyg.,  1911,  VIII.  1.32;  also  Chick  aiul  Martin, 
Jotir.  of  Hyq..  1908,  VIII,  644,  698. 

"■'Jour,  of  Infect.  Dis.,  1911,  VIII,  27. 

'^Rideal,  S.,  and  Walker,  J.  S.  A.:  Jour.  Roy.  San.  Inst.,  London,  1903,  Vol. 
XXIV,  p.  424.  "The  Standardization  of  Disinfectants,"  The  Lancet  Commission 
Vol.  CLXX^'II,  Xos.  4498,  4499.  4.500.  Anderson  and  McClintic:  Jour.  Infect. 
Dis.,  Vol.  VIII,  Xo.  1,  Jan.,  1911,  pp.  1-26.  Hygienic  Lahoratorif  Bulletht  No. 
82.     Public  Health  Reports,  April  12,   1918  and  October   17,  1919." 

The  carbolic  coefficient  above  described  is  not  the  Rideal-Walker  Technic 
but  modified  in  part  from  the  Hygienic  Laboratory  Phenol  Coefficient,  and  in 
part  from  the  Lancet  Commission  Method. 


1308 


GENERAL  CONSIDERATIONS 


Test  Organism. — The  coefficient  will  vary  with  different  microorgan- 
isms. The  culture  recommended  is  a  24-hour-old  B.  typhosus  grown  in 
bouillon.    It  is  important  always  to  use  the  same  strain  of  typhoid,  as 


Fig.  164. — Device  fob  Determining  Carbolic  Coefficients. 
Consists  of  a  wooden  box  14"  long  by  14"  wide  by  15"  high,  containing  a  metal 
pail  (A)  10"  in  diameter,  and  8%"  deep.  A  shelf  made  of  wire  mesh  (B)  is 
inserted  2"  from  the  top  of  the  pail,  which  is  iilled  with  water.  A  pipe  with  a 
faucet  (C)  from  the  bottom  of  the  pail  will  be  found  very  convenient  to  draw 
off  the  water  and  regulate  its  temperature.  Asbestos  packing  (E)  completely 
surrounds  the  pail  in  order  to  insulate  it.  The  lid  of  the  box  (F),  which  is 
raised  in  the  drawing,  contains  openings  for  the  five  test-tubes,  and  three  other 
openings  for  cultures  and  thermometer.  When  the  lid  is  in  place  the  test-tubes 
rest  upon  the  shelf  ( B ) .  A  drawer  ( D )  in  the  bottom  of  the  box  is  convenient 
to  keep  test-tubes,  inoculating  needles,  thermometer,  and  other  parts  of  the 
apparatus. 


different  races  vary  in  resistance.  Further,  the  culture  should  be  car- 
ried over  every  twenty-four  hours  on  at  least  three,  preferably  seven  suc- 
cessive days  before  using  it  in  a  test.    It,  is  advisable  to  filter  the  culture 


THE  STANDAKDIZATIOX  OF  DISINFECTANTS       1369 

thrt)Uirh  filtor-paper  in  order  to  remove  clumps  just  before  beginning  ;i 
test.  The  culture  should  always  be  grown  under  the  same  conditions, 
upon  the  same  medium,  so  as  to  insure  uniformity. 

Medium. — The  standard  beef-extract  broth  (reaction  -|-  1.0)  recom- 
mended by  the  Committee  on  Standards  of  the  American  Public  Health 
Association  for  Water  Analysis,  is  used  both  to  grow  the  test  typhoid 
organism  and  also  for  the  sub-cultures  made  after  exposure  to  the  dis- 
infectant. Ten  c.  c.  of  this  broth  are  placed  in  each  test-tube  for  the 
sub-cultures,  as  this  amount  is  sufficient  to  avoid  any  antiseptic  activity 
of  the  disinfectant  carried  over.^^ 

Phenol,  first  proposed  by  Rideal  ami  Walker,  and  now  adopted  by 
common  consent,  is  the  standard  of  comparison.  Phenol  may  readily 
be  obtained  chemically  pure,  and  exact  solutions  may  be  prepared  by 
titration  with  bromin.  A  o  per  cent,  stock  solution  is  usually  made 
and  this  is  diluted  for  the  purpose  of  the  test.  Another  advantage  of 
phenol  is  that  it  is  relatively  unaffected  by  the  presence  of  organic 
matter.    Only  formalin  perhaps  is  superior  to  it  in  this  regard. 

Temperature  of  Exposure. — This  is  one  of  the  most  important  fac- 
tors. The  germicidal  activity  of  substances  increases  with  the  tempera- 
ture. In  this  respect  germicidal  reactions  resemble  chemical  reactions. 
It  is  therefore  of  the  utmost  importance  that  the  solutions  tested  should 
be  always  at  the  same  temperature,  and  for  this  purpose  20°  C.  has  been 
selected  as  most  convenient.  The  solutions  to  be  tested  and  the  typhoid 
culture  itself  must  be  brought  to  this  temperature  before  they  are  mixed, 
and  then  maintained  at  this  temperature  iu  a  water-bath. 

Proportian  of  Culture  to  Disinfectant. — Eideal  and  Walker  first  pro- 
posed to  use  one  drop  of  the  typhoid  culture  to  each  cubic  centimeter  of 
germicidal  solution.  It  is  more  accurate  to  use  a  measured  amount,  say 
0.1  c.  c.  of  the  2-1-hour-old  bouillon  culture  of  typhoid  to  5  c.  c.  of  solu- 
tion. These  are  convenient  amounts  easily  and  accurately  measured  with 
standardized  delivery  pipets.  It  should  be  kept  in  mind  that  the  addi- 
tion of  the  bouillon  culture  dilutes  the  germicidal  solutions,  but  as  this 
is  a  constant  factor  it  does  not  affect  the  comparative  values  as  expressed 
by  the  carbolic  coefhcient,  but  may  be  taken  into  consideration  in  Judg- 
ing the  germicidal  values  for  practical  work. 

Inoculation  Loops. — Precisely  the  same  quantity  of  fluid  from  the 
mixture  should  be  removed  each  time  for  the  transplants.  This  is  done 
most  readil}'  with  platinum  loops  made  of  23  T'.  S.  standard  gauge  wire 
and  a  loop  4  millimeters  in  diameter  inside  measurement.  This  may  be 
made  over  a  No.  14  wire  U.  S.  gauge.  Several  of  these  loops  should  be 
on  hand.  They  are  sterilized  and  placed  upon  a  rack.  As  one  is  used 
it  is  flamed  and  returned  to  the  rack,  so  that  it  will  be  cool  when  taken 
in  its  turn. 

"See  Modification  of  Media.     U.  S.  Pub.  Huallh  Epts..  Oct.  17,  I'Jl'J.  p.  2297. 


1370 


GENERAL  CONSIDEEATIONS 


Dilutions. — A  standard  series  of  dilutions  should  be  made  of  the 
phenol  standard  and  also  of  the  germicide  to  be  tested — in  accordance 
with  the  tables  in  Hygienic  Laboratory  Bulletin  No.  82. 

Technic. — The  following  method  is  the  one  used  in  my  laljoratory  for 
carrying  out  the  carbolic  coefficient : 

A  solution  of  5  per  cent,  phenol  c.  p.  is  made  and  standardized  chem- 
ically.^" The  usual  dilutions  of  1  to  90,  1  to  100,  and  1  to  110,  etc.,  are 
made  from  this  stock  solution  as  desired. 

The  solutions  of  the  germicidal  substances  to  be  tested  must  be  made 
accurately,  according  to  volumetric  or  gravimetric  methods. 

The  tests  are  carried  out  in  test-tubes  one  inch  in  diameter  and  three 
inches  long.    These  are  placed  in  a  row  in  a  water-bath.    The  test-tubes 


0  minute 


14  minut?^^ 


1  miBute 


114  minutes 


2  minutes 


2 


See.  phenol  1:90      5  c.c.  phenol  1: 100        5  c  c.  solution  x 

•       and  and  1;900 

0.1  ce.  eulture  0.1  cc.  cultxire  and 

0.1  C.C-  culture 


0.5  c.c.  solution  x 
1:1000 

and 
0.1  c.c.  culture 


0.5  c.c.  solution  x 
1: 1200 

and 
0  !  CO.  culture 


Fig.  165. — Arrangement  of  Tubes  in  Water-bath  and  Their  Contents. 


rest  upon  a  bed  of  sand  and  are  held  in  place  by  a  wire  rack  or  simply 
by  a  board  perforated  with  holes  of  suitable  size.  If  the  water-bath  is 
sufficiently  large  and  the  water  brought  to  just  20°  C.  it  may  be  main- 
tained at  this  temperature  with  but  slight  attention. 

Each  test-tube  receives  5  c.  c.  of  the  solution  to  be  tested.  Time  is 
allowed  for  the  solutions  to  reach  the  temperature  of  20°  C,  then  the 
culture  which  has  previously  been  brought  to  20°  C.  is  added  and  mixed 
with  the  solution  in  each  test  tube  in  turn.  The  culture  is  added  to 
each  tube  at  intervals  of  just  30  seconds.  With  a  row  of  five  tubes  this 
will  make  a  2%-minute  interval  for  each  tube  as  the  subsequent  sub-in- 
oculations are  made. 

Two  and  one-half  minutes  after  the  phenol  and  the  culture  have 
been  mixed  together  in  tube  No.  1  a  loopful  of  the  mixture  is  removed 
and  planted  in  broth ;  30  seconds  later  a  loopful  of  the  mixture  is  taken 
from  tube  No,  2,  and  so  on  throughout  the  series  at  intervals  of  30 
seconds.  The  entire  procedure  of  removing  the  loopful  of  mixture  and 
planting  it  into  one  of  the  test-tubes  containing  10  c.  c.  of  broth  requires 
only  about  15  seconds,  allowing  plenty  of  time  to  flame  the  loop,  replace 
it  in  the  rack,  and  pick  up  another  loop  which  had  previously  been  flamed 

^  By  bromin  titration.      (See  description  in  Sutton's  "Volumetric  Analysis.") 


THE  STAXDAKDIZATTOX  OF  DISINFECTANTS       1:^71 

and  lias  coolod  sutricicntly  for  the  next  ()]KM-atioii.  'I'lio  iest-tuix'S  hold- 
ing the  niixturo  of  germicidal  solution  ami  culture  need  not  be  removed 
from  the  water-bath,  and  it  is  not  necessary  to  keep  them  jjhigged  with 
cotton.  The  loop  should  always  be  plunged  to  the  bottom  and  care  taken 
not  to  touch  the  sides  of  the  test-tube  and  always  to  carry  away  a  loopful 
of  the  fluid  to  be  transplanted.  The  test-tubes  holding  the  medium  for 
the  transplants  are  conveniently  placed  in  Avooden  racks  and  are  incu- 
bated at  37°  C.  for  forty-eight  hours,  when  the  readings  as  to  growth 
(  +  )  or  no  growth  ( — )  are  tabulated. 

An  example  of  a  carbolic  coethcient  test  follows : 


Phenol  1  :  90    .  . 

Phenol  1  :  100    . 

Solution  X  1  :  900   . 

Solution  X  1  :  1.000 

Solution  X  1  :  1,200 


21/a 
Minutes 

5 
Minutes 

7  '{. 
Minutes 

10 
Minutes 

+ 

— 

— 

— 

+ 

+ 

+ 

+ 

+ 

12 1/2 
Minutes 


+ 


The  carbolic  coefficient  of  solution  X  is  therefore  \"oo    =10. 

The  carbolic  coefficient  is  determined  by  comparing  the  strengths 
of  the  unknown  disinfectant  with  phenol  that  "show-  life"  in  2i/^  min- 
utes— or  practically  the  strengths  that  kill  in  5  minutes.  Previously 
it  was  permissible  to  compute  the  coefficient  upon  any  of  the  periods 
of  the  test  up  to  30  minutes.  However,  it  was  found  possible  in  this 
way,  either  by  chance  or  intent,  to  obtain  an  extravagantly  high  co- 
efficient. Thus  Chick  and  Martin  showed  that  the  phenol  coefficient  of 
certain  metallic  salts  varies  from  13.8  to  550,  depending  on  whether  the 
period  of  comparison  is  21^4  or  30  minutes. 

Anderson  and  McClintic  ^^  have  modified  the  procedure  employed  by 
the  Lancet  Commission  to  determine  the  coefficient  to  be  the  mean 
between  the  strength  and  the  time  coefficient;  that  is,  the  figure  repre- 
senting the  degree  of  dilution  of  the  w^eakest  strength  of  the  disinfectant 
that  kills  within  2i/o  minutes  is  divided  by  the  figure  representing  the 
degree  of  dilution  of  the  w'eakest  strength  of  the  phenol  control  that 
kills  within  the  same  time.  The  same  calculation  is  done  for  the  weakest 
strength  that  kills  in  15  minutes.    The  mean  of  the  two  is  the  coefficient. 

An  example  of  the  "phenol  coefficient"  as  determined  by 'the  Hy- 
gienic Laboratory  method  is  given  on  the  next  page. 

Kendall  and  Edwards  --  have  devised  an  ingenious  method  to  deter- 
mine the  penetrating  power  of  germicides  in  the  presence  of  organic 
matter.     The  method  consists  essentiallv  of  cvlindrical  molds  of  agar 


'Hygienic  Lahorntory  Bulletin,  U.  S.  P.  H.  and  M.  H.  S..  No.  S2.  1012. 
'Jattr.  Infect.  Dis.,  Vol.  VITl.  No.  2,  March.  1911.  pp.  2r)0-2.>7. 


1372  GENEl^AL  CONSIDERATION'S 

PHENOL  COEFFICIENT:  HYGIENIC  LABORATORY  METHOD 


Time  Culture  Exposed  to  Action  of 

Sample 

Dilution 

Disinfectant  for  Minutes 

Phenol 

21/2 

+ 

5 

TVo 

10 

10 

15 

Phenol   

1:80 
1:90 

— 

•• 

375         650 

+  

1:100 

+ 

+ 

+ 

— 

— 

— 

80          110 

1:110 

+ 

+ 

+ 

.+ 

+ 

' 

2 

Disinfectant  "A" 

1:350 
1:375 
1:400 

— 

— 

— 

4.69  +  5.91 

+ 

_ 

— 

, . 

2 

1:425 

+ 

+ 

■ — 

— 

— 

— 

1:450 

+ 

+ 

— 

— 

— 

— 

=  5.30 

1:500 

+ 

+ 

— 

— 

— 

— 

1:550 

+ 

+ 

+ 

— 

— 

— 

1:600 

+ 

+ 

+ 

+ 

— 

— 

' 

1:650 

+ 

+ 

+ 

+ 

+ 

— 

1:700 

+ 

+ 

+ 

+ 

+ 

+ 

1:750 

+ 

+ 

"+ 

+ 

+ 

-h 

Temperature  of  medication,  20°  C. 

Culture  used,  B.  typlwsus,  24-hour,  extract  broth  filtered. 

Proportion  of  culture  and  disinfectant,  0.1  c.  c.  +  5  c.  c. 

impregnated  with  the  test  organism.  Sections  of  these  cylindrical  mold- 
or  "artificial  feces"  are  exposed  to  the  germicide  solutions  and  plants 
made  after  proper  intervals  of  time  from  a  core  taken  from  the  center  of 
the  cylinder. 

The  carbolic  coefficient  of  any  substance  should  be  based  upon  the 
average  of  a  large  number  of  tests. 

Interpretation  of  Results. — A  low  carbolic  coefficient  usually  means 
a  useless  disinfectant.  Formalin  has  a  low  coefficient,  although  for- 
maldehyd  is  one  of  our  potent  and  serviceable  germicides.  The  reason 
for  this  discrepancy  consists  in  the  fact  that  the  coefficient  is  based  upon 
formalin  which  contains  only  40  per  cent,  or  less  of  formaldehyd.  On 
the  other  hand  it  should  be  remembered  that  because  a  germicide  has  a 
high  coefficient  is  no  true  indication  that  it  is  a  favorable  agent  in  prac- 
tical work.  There  are  many  factors  still  to  be  considered.  Thus  a  use- 
ful disinfectant  should  not  be  very  poisonous  to  higher  animals;  should 
not  corrode  metals  or  rot  fabrics;  should  not  stain  or  bleach;  should 
not  have  an  unpleasant  smell;  should  be  reasonably  cheap;  should  be 
readily  miscible  with  water  and  not  deposit  from  solution  or  suspension ; 
should  be  reasonably  stable ;  should  act  both  in  alkaline  and  acid  media ; 
should  not  be  greatly  influenced  by  the  presence  of  organic  matter,  and 
should  possess  a  fair  power  of  penetration.  Further,  it  should  not  be 
specific,  but  be  a  general  poison  for  all  microscopic  plant  and  animal 
life.     It  must  at  once  be  evident  that  no  one  test  can  determine  all 


THE  STAXDAL'DIZATIOX   OK   DISI  X  FECTANTS       1373 

The  Puk.vol  Coefficient  of  Some  Commercial  Germicides 
Dftorininod  hv  Thomas  B.  McClintic  * 


Bactorol 

Bi'iietol 

Calx^fs  Siilplioiiiiptliol    

Carlioh'iu'    

Carholozoiu'    

Car-Sul 

Cliloro-NapllKilciim     

Crenidlinc 

Creo-Carlioliiic    

Creolin-lVai  son    

Cresoleuin 

Crude  Carbolic  Ac-id 

Dusenberry's  Liquid  Cicoleum 

Gerniol   

Hycol    

Hygeno  A 

Kreosota 

Kreotas    

Kreso 

Kresolig    

Lincoln   Disinfectant , 

Liquor  cresolis  comnositus   (U.  S.  P. )    

Lysol    \ 

"Xapthalene  Disinfectant''  , 

Phenoco , 

Phenol  liquid  (U.  S.  P.,  1890)    

Phenosote    

Phinotas   

R.  R.  Rogers  Disinfectant 

Rudisch's  Creolol 

Saponified  Cresol 

Tarola   

Trikresol 

Zenoleum   

Zodone    

Zonol    

Antozone  f   

Creola  Disinfectant 

Dioxygen   

Electrozone    

Formacone  Liquid 

Killitol 

Kretol   

Listerine   

Phenol  Disinfectant  and  Cleansing  Liquid 

Phenol  Sodique   

Pino-lvptol    

Piatt's  Chlorides '.[ 

Public  Health  Liquid  Disinfectant 

Sanitas   

The  Twentieth  Century  Disinfectant   

Veroform  Germicide 

Worrell's  In.sect  Exterminator  and  Disinfectant 
Zodane  No.  3 


Without  Or- 
ganic Matter 


With  Organic 
Matter 


i.r,,s 

1.34 

1.23 

0.92 

3.,S7 

2.33 

1.30 

0.65 

1.4S 

0.48 

2.00 

1.75 

6.0G 

3.21 

L26 

0.69 

4.03 

2.26 

3.25 

2.52 

2.90 

1.75 

2.75 

2.63 

1.00 

0.40 

2.12 

1.79 

12.30 

9.37 

3.56 

1.81 

L2r) 

0.65 

1.10 

0.30 

3.92 

2.32 

2.1S 

1.48 

1.48 

1.10 

3.00 

1.87 

2.12 

1.57 

2.50 

1.36 

L5.00 

9.86 

L77 

1.76 

3.43 

2.31 

L37 

0.53 

3.03 

2.05 

L24 

0.75 

L03 

0.57 

3.12 

1.93 

2.62 

2.50 

2.25 

1.64 

L62 

0.51 

2.37 

1.57 

nil 

0.52 

weak 

0.90 

weak 

\veak 

0.92 

weak 

0.61 

weak 

0.27 

weak 

0.48 

• 

0.30 

0.13 

0.43 

weak 

weak 

*  Hyg.    Lab.  Bull.  No.  82,  U.  S.  P.  H.  &   M.  H.  S. 
t  The   following  disinfectants  have  a  coefficient  of  less  than   1. 
weak  that  it  was  impracticable  to  determine  the  coefficient. 


Most  of  them  are  so 


1374  GENERAL  CONSIDERATIONS 

of  these  factors,  so  that  a  thorough  and  comprehensive  study  of  the 
substance  to  be  used  should  be  made  upon  many  different  parasites 
under  many  different  conditions  before  we  can  have  a  satisfactory 
knowledge  of  its  power  and  limitations.  This  is  one  of  the  reasons 
that  makes  ns  conservative  about  taking  up  new  germicidal  substances 
until  thoroughly  tested  under  different  conditions,  and  inclines  us  to 
adhere  to  luell-known  chemicals  such  as  hichlorid  of  mercury,  carholic 
acid,  the  coal-tar  creosotes,  lime,  the  hypochlorites,  and  formalin,  th.e 
advantages  and  limitations  of  which  have  been  thoroughly  established. 


CHAPTER  II 
PHYSICAL  AGENTS  OF  DISINFECTION 

Sunlig'ht. — Sunlight  is  an  active  germicide.  It  destroys  spores  as 
^ell  as  bacteria.  Unfortunately,  the  sunlight  is  so  uncertain  and  the 
force  of  the  sun's  rays  so  variable  and  their  disinfecting  powers  so  super- 
ficial that  it  cannot  be  depended  upon  as  an  aggressive  measure  in  attack- 
ing infection.  In  rooms,  ships,  and  confined  spaces  sunshine  comes 
more  under  the  purview  of  the  sanitarian  than  under  that  of  the  disin- 
fector,  but  the  latter  can  always  use  it  to  advantage  in  supplementing 
his  other  methods.  Eooms  and  objects  should  always  be  sunned  and 
aired  after  disinfection. 

The  different  rays  of  light  have  very  different  effect  upon  germ  life. 
The  blue-violet  and  ultraviolets,  that  is,  the  more  refrangible  chemical 
rays  of  short  wave  length,  are  the  only  ones  possessing  germicidal  power. 
The  red  and  yellow  rays  are  practically  inert  in  this  regard.  The  source 
of  Hght  seems  to  have  little  influence  upon  the  result ;  it  is  more  a  ques- 
tion of  intensity  and  nature  of  the  rays.  Even  diffused  light  retards 
growth  and  development  of  bacteria,  and  if  strong  enough  will  finally 
kill  them.  Electric  light  containing  the  proper  rays  is  efficient.  The 
Eontgen  rays  have  no  bactericidal  properties.  The  sun  is  the  natural 
generator  of  ultraviolet  rays. 

The  time  required  for  sunlight  to  destroy  bacteria  varies  with  its 
brightness  and  with  conditions  such  as  moisture,  temperature,  trans- 
parency, and  composition  of  the  media,  which  aid  or  hinder  the  effect 
of  the  rays.  The  time  also  varies  with  the  different  microorganisms; 
plague  bacilli  and  cholera  vibrio  usually  die  more  quickly  than  tubercle 
bacilli.  Spores  are  much  more  resistant  to  the  influence  of  the  chemical 
rays  than  the  bacterial  cells  themselves.  Thus  it  usually  requires  about 
thirty  hours'  sunning  to  kill  an  anthrax  spore,  while  the  anthrax  ba- 
cillus is  killed  in  one  or  two  hours  when  subjected  to  the  same  con- 
ditions. 

Ultraviolet  Rays. — Ultraviolet  rays  are  invisible  rays  which  lie  be- 
yond the  violet  end  of  the  spectrum.  In  general  it  may  be  said  that  they 
include  those  rays  of  short  wave  lengths  between  3,900  and  2,250  Ang- 
strom.^ 

The  wave  lengths  of  the  visible  spectrum  are  from  about  7,610  Ang- 

'  One  Angstrom  unit  is  1/10,000,000  of  a  centimeter. 

1375 


1376  PHYSICAL  AGENTS  OF  DISmFECTIO¥ 

strom  units  (red)  to  about  3,970  (violet).  According  to  ISTogier  -  the 
ordinary  ultraviolet  rays  extend  from  3,920,  to  3,000  units,  the  average 
rays  from  3,000  to  2,200,  and  the  extreme  ultraviolet  rays  from  2,200 
to  1,000  units.  He  states  that  rays  from  3,920  to  3,000  are  not  bactericidal 
to  any  extent  but  produce  sunburn  after  long  exposure.  Eays  between 
3,000  to  2,200  have  a  strong  action  on  bacteria  while  those  from  2,200 
to  1,000  are  still  more  powerful  but  are  of  little  value  since  they  are 
easily  absorbed  by  air  and  other  substances. 

"Tltraviolet  rays  from  the  Cooper  Hewitt  lamp,  produced  by  an  elec- 
tric discharge  through  mercury  vapor  contained  in  a  quartz  lamp  in 
vacuo,  have  an  exceedingly  powerful  germicidal  action,  killing  spores  as 
well  as  bacterial  cells.  Glass  is  opaque  to  these  rays  of  short  wave  lengths 
and  it  is  therefore  necessary  to  use  quartz  globes. 

Cernovodeanu  and  Henri  ^  have  shown  that  the  action  of  ultraviolet 
light  is  greater  near  the  lamp  and  decreases  as  the  square  of  the  distance 
from  the  source  of  the  rays.  Ultraviolet  rays  act  just  as  well  at  0° 
C.  as  at  55°  C.  They  also  act  equally  quickly  in  the  presence  or  absence 
of  oxygen.  Pure  cultures  of  non-spore-bearing  microorganisms  are 
killed  in  from  5  to  60  seconds.  Molds,  however,  are  only  partially  de- 
stroyed. 

Ultraviolet  light  does  not  act  indirectly  through  production  of  hydro- 
gen peroxid  or  ozone,  but  kills  bacteria  by  some  direct  action  upon  the 
protein  which  it  seems  to  coagulate  and  decompose. 

On  the  whole,  very  satisfactory  results  have  been  obtained  in  disin- 
fecting clear  water  with  ultraviolet  rays,  and  in  several  cities  in  France 
and  elsewhere  the  municipal  water  supply  is  treated  by  this  process. 
See  pages  916  and  1141:.  Proteins  and  other  bodies  of  high  molecu- 
lar weight  interfere  with  the  action  of  the  rays.  Turbidity,  both 
organic  and  inorganic,  has  a  similar  action.  Color,  within  certain  limits, 
seems  to  have  no  influence  whatsoever. 

TJltraviolet  rays  cannot  be  used  successfully  to  pasteurize  milk  for 
the  reason  that  milk  is  opaque,  and  furthermore  the  rays  act  upon  the 
protein,  causing  unpleasant  odors  and  tastes  to  develop.  Attempts  to  kill 
the  bacteria  in  turbid  water,  beer,  wine,  and  vinegar  have  been  only  par- 
tially successful,  because  the  organic  matter  interferes  with  the  pene- 
tration of  the  rays. 

TJltraviolet  light  possesses  no  therapeutic  value  so  far  as  direct  de- 
struction of  bacteria  within  any  of  the  tissues  of  the  body  is  concerned. 
Verhoeff*  has  shown  that  ultraviolet  light   will   not   destroy  bacteria 

^Nogier,  T. :  "Les  Rayons  ultraviolets  et  leur  application  a  la  sterilisation 
des  liquides,"  Rev.  d'Hyg.  "et  de  Police  Sanit,,  T.  32,  1910,  pp.  421-431. 

^  Cernovodeanu,  P.,  et  Henri,  Victor :  "Ktude  de  Taction  des  rayons  ultra- 
violets sur  les  microbes,"  Compt.  rend.  hehd.  de  Seane.  d.  I'Acad.  des  Scienc., 
T.  150,  1910,  pp.  52-,54;  also  Zeitschr.  f.  Eyg.,  Feb.,  1916. 

*VerhoeflF,  F.  H.:  "Ultraviolet  Light  as  a  Germicidal  Agent,"  J.  A.  M.  A., 
March  7,  1914,  LXII,  10,  p.  762. 


PHYSICAL  AGENTS  OF  DISINFECTION  1377 

within  the  cornea,  even  when  the  latter  is  perfectly  transparent,  with- 
out at  the  same  time  severely  injuring  the  corneal  tissues.  See  also 
page  9 IS. 

Electricity. — It  appears  that  electric  currents  have  little  germicidal 
action  in  themselves  and  that  the  apparent  effects  noted  by  some  investi- 
gators are  due  either  to  the  heat  generated  by  the  current  or  to  elec- 
trolytic action.  Electricity  has  very  little  use  in  practice  as  a  disin- 
fectant. Hermite  used  the  products  of  electrolysis  for  the  sterilization 
of  sewage.  He  added  sea-water  to  the  sewage  and  the  electrolytic  action 
caused  the  formation  of  hypochlorite,  which  has  well-known  germicidal 
action.  The  effect  of  electrical  currents  upon  bacteria  seems  to  be  a 
purely  chemical  one  in  the  case  of  germicidal  substances  being  formed 
by  electrolytic  decomposition ;  or  a  thermal  one  in  the  case  of  the  pro- 
duction of  heat,  which  so  frequently  attends  the  discharge  of  electric 
currents. 

Pressure. — Hite  ^  finds  that  a  pressure  of  100,000  pounds  per  square 
inch,  at  room  temperature,  destroys  most  non-spore-bearing  bacteria. 
Under  these  conditions,,  milk  containing  from  30  to  40  million  per  c.  c, 
may  be  reduced  to  a  few  hundred  by  the  application  of  100,000  pounds 
for  10  minutes.  The  pressure  does  not  affect  the  enzymes.  Forty-five 
thousand  pounds  pressure  is  sufficient  to  kill  B.  typhosus  in  beef  broth 
in  10  minutes.  B.  diphtheriae  in  beef  broth  are  killed  at  40,000  pounds 
pressure  in  10  minutes. 

Larson,  Hartzell  and  Diehl  ^  found  that  a  direct  pressure  of  6,000 
atmospheres  kills  non-spore-forming  bacteria  in  14  hours.  A  pressure 
of  about  12,000  atmospheres  for  the  same  length  of  time  is  required 
to  kill  spores.  Non-spore-bearing  bacteria  are  killed  by  COg  of  50  atmos- 
pheres pressure  in  about  1%  hours.  Yeast  cells  withstand  the  action  of 
CO2  for  more  than  24  hours,  probably  because  of  their  ability  to  trans- 
mit the  CO2  molecule  through  the  membrane  promptly.  Nitrogen  under 
a  pressure  of  120  atmospheres  has  no  effect  on  bacteria. 

Burning. — Fire  is  the  great  purifier.  Burning  has,  however,  a  very 
limited  range  of  usefulness  in  practical  disinfection.  The  disinfector 
is  seldom  justified  in  burning  an  article  against  the  wish  of  its  owner, 
for  we  now  possess  methods  by  which  any  object  may  be  rendered  safe 
so  far  as  its  power  of  conveying  disease  is  concerned.  In  actual  prac- 
tice, however,  the  disinfector  often  comes  across  a  great  amount  of  rub- 
bish and  articles  of  little  value  that  he  will  find  easier  and  cheaper  to 
burn  than  to  disinfect.  The  burning  of  garbage  and  refuse  is  the  safest 
means  of  disposing  of  such  organic  substances  from  a  sanitary  stand- 
point, especially  in  districts  where  pestilential  disease  prevails.  From 
the  same  standpoint  the  cremation  of  all  bodies  dead  of  a  communicable 

'Bull.  U6,  W.  Va.  Agricul.  Exp.  Sta.,  October,  1914. 
'Joum.  Infect.  Dis.,  March,  1918.  p.  271. 


1378  PHYSICAL  AGENTS  OF  DISINFECTION 

disease  is  the  safest  method  of  preventing  possible  spread  of  infection 
from  this  source.  Burning  is  the  most  satisfactory  method  of  disinfect- 
ing and  disposing  of  small  amounts  of  sputum  and  other  infected  dis- 
charges. Burning  of  the  surface  of  the  ground  by  means  of  gasoline 
torches  and  petroleum  is  sometimes  used  to  destroy  animal  parasites  and 
other  infections  which  find  lodgment  on  the  soil.  The  gasoline  torch  is 
also  used  to  fight  insect  pests  of  trees  and  plants. 

Dry  Heat. — A  temperature  of  150°  C.  continued  for  one  hour  will 
destroy  all  forms  of  life,  even  the  most  resistant  spores.  It  .is  easy 
to  maintain  this  temperature  in  an  apparatus  of  special  construction 
known  as  a  hot-air  or  dry-wall  sterilizer.  Dry  heat  penetrates  slowly, 
especially  through  fabrics.  Air  is  also  a  poor  conductor.  It  must 
therefore  be  remembered  that  the  temperature  as  registered  on  the 
thermometer  does  not  necessarily  indicate  the  temperature  at  the  critical 
place  within  the  sterilizer.  A  liberal  factor  of  safety  is  therefore  neces- 
sary, especially  in  large  scale  operations.  In  the  sterilization  of  glass- 
ware and  other  objects  in  laboratories  'making  biologic  products,  it  is 
customary  to  expose  them  for  at  least  two  hours  to  not  less  than  170° 
C.  to  insure  penetration  and  heating  of  all  surfaces.  Glassware  and 
many  other  objects  will  stand  this  degree  of  heat  and  are  sterilized  in 
an  oven  of  this  kind  in  bacteriological  laboratories  and  in  surgical 
clinics. 

Dry  heat  is  not  as  satisfactory  a  disinfectant  as  moist  heat,  as  it 
lacks  the  power  of  penetration  and  is  injurious  to  fabrics.  Most  ma- 
terials will  bear  a  temperature  of  110°  C.  without  much  injury,  but 
when  this  temperature  is  exceeded  signs  of  damage  soon  begin  to  show. 

Scorching  occurs  sooner  with  woolen  materials,  such  as  flannels  and 
blankets,  than  with  cotton  and  linen.  Over-drying  renders  most  fab- 
rics very  brittle,  but  this  injury  may  be  lessened  by  allowing  the  ma- 
terials which  have  been  subjected  to  dry  heat  to  remain  in  the  air  long 
enough  to  regain  their  natural  degree  of  moisture  and  pliability  before 
manipulating  them. 

The  ordinary  household  cooking  oven  is  as  good  as  any  specially 
contrived  apparatus  for  the  disinfection  of  small  objects  by  dry  heat. 
In  the  absence  of  a  thermometer  it  is  usual  to  heat  the  oven  to  a  point 
necessary  to  brown  cotton  and  expose  the  objects  no  less  than  one  hour. 

Boiling. — Boiling  is  such  a  commonplace,  every-day  procedure  that 
it  is  often  neglected  in  practical  disinfection  despite  the  fact  that  it 
is  one  of  the  readiest  and  most  effective  methods  of  destroying  infections 
of  all  kinds.  An  exposure  to  boiling  water  at  100°  C.  continued  for  an 
hour  will  destroy  the  living  principles  of  practically  all  the  infectious 
diseases  with  which  we  have  to  deal  in  public  health  work.  To  be  sure, 
there  are  a  few  spores  that  have  shown  a  remarkable  resistance  to  boiling 
water  and  streaming  steam  in  laboratory  experiments.     Boiling,  there- 


PHYSICAL  AGENTS  OF  DISINFECTION  1379 

fore,  cannot  bo  cntirt'ly  (U'ponded  upon  where  tetanus,  anthrax,  or  re- 
sisting spores  are  in  (piestion.  As  a  matter  of  fact,  a  degree  of  moist 
heat  nnich  lower  llian  tlie  l)oilin<2!'  point  of  water  is  effective  against  the 
great  majority  of  the  known  viruses.  Thus  a  temperature  of  C0°  C. 
for  20  minutes  will  destroy  the  microorganisms  of  cholera,  typhoid,  dys- 
entery, dipiitheria.  ])laguo,  tuberculosis,  pneumonia,  erysipelas,  and 
practically  all  non-spore-bcaring  bacteria.  Boiling  kills  them  at 
once. 

Boiling  is  especially  applicable  to  the  disinfection  of  bedding,  body 
linen,  towels,  and  fabrics  of  many  kinds;  also  kitchen  and  tableware, 
cuspidors,  urinals,  and  a  great  variety  of  objects.  Surfaces,  such  as 
floors,  w^alls,  beds,  metal  works,  etc.,  may  be  effectively  disinfected  by 
mechanically  cleansing  them  with  boiling  water.  The  efficacy  of  boiling 
water,  especially  when  used  in  such  circumstances,  is  greatly  increased 
by  the  addition  of  corrosive  sublimate,  carbolic  acid,  or  one  of  the  alka- 
line coal-tar  creosotes.  The  addition  of  lye,  borax,  or  a  strong  alkaline 
soap  also  increases  the  penetrating  and  detergent  power  of  boiling  water 
when  applied  to  surfaces  soiled  with  organic  or  oily  matters. 

Boiling  in  3  to  5  per  cent,  phenol  or  some  similar  disinfectant  will 
kill  tetanus  and  other  spores.  This  method  is  applicable  to  rubber  goods 
and  other  articles. 

In  using  boiling  water  for  the  disinfection  of  bright  steel  objects 
or  cutting  instruments  the  addition  of  1  per  cent,  of  an  alkaline  sub- 
stance such  as  carbonate  of  soda  will  prevent  rusting  and  injury  to  the 
cutting  edge.  The  method  advocated  by  Eebula  ^  is  as  follows :  Two 
and  one-half  grams  of  sodium  hydroxid  (NaOH)  should  be  added  to 
1,000  grams  of  water.  The  sodium  hydroxid  should  be  allowed  two 
minutes  in  which  to  dissolve  and  to  combine  with  the  CO2  of  the  water 
before  the  instruments  are  put  in  the  solution  and  boiled. 

Steam. — Steam  is  one  of  the  most  satisfactory  disinfecting  agents  we 
possess.  It  is  reliable,  quick,  and  may  be  depended  upon  to  penetrate 
deeply.  Further,  it  does  more  than  disinfect;  it  sterilizes.  Vegetating 
bacteria  are  killed  instantly  and  most  spores  in  a  short  time.  It  may 
therefore  be  used  to  destroy  the  infection  of  any  of  the  communicable 
diseases. 

Either  streaming  steam  or  steam  under  pressure  is  used  in  practical 
disinfection. 

Streaming  steam  has  the  same  disinfecting  power  as  boililig  water, 
and  an  exposure  of  half  an  hour  to  an  hour  is  sufficient.  Steam  under 
pressure  is  a  more  powerful  germicide  than  streaming  steam.  At  a  pres- 
sure of  15  pounds  *  to  the  square  inch  steam  has  a  temperature  of  approx- 

^  Centralblatt  f.  Chirurgie,  Oct.   16,   1920,  47,  Xo.  42,  p.   1297. 
'  That  is,    15   pounds  above  atmospheric   pressure.      Barometric   pressure  is 
zero.    Throughout  this  book,  "pounds  pressure"  means  "gauge  pressure." 


1380 


PHYSICAL  AGEXTS  OF  DISINFECTION 


imately  120°  C.  and  may  be  depended  upon  to  sterilize  in  20  minutes. 
At'  20  pounds  pressure  it  has  a  temperature  of  approximately  125°  C. 
and  will  sterilize  in  15  minutes.  The  following  table  gives  the  tempera- 
ture at  various  pressures  and  vice  versa. 


Temperature 

Pressure 

Degrees  C. 

Degrees  F. 

Mm.  of  Mercury 

Pounds  per 
Square  Inch 

Gauge 
Pressure  * 

100 
105 
110 
115 
120 
125 

212 
221 
230 
239 
248 
257 

760.00 
906.41 
1075.37 
1269.41 
1491.28 
1743.88 

14.70 
17.53 
20.80 
24.55 
28.85 
33.72 

0.0 
2.83 
6.10 
9.85 
14.15 
19.02 

*  That  is,  pounds  per  square  inch  above  atmospheric  pressure. 


The  temperature  is  a  much  more  reliable  guide  than  the  pressure. 
The  temperature  of  the  ohject  to  be  disinfected,  rather  than  the  tempera- 
ture of  the  apparatus  is  the  critical  factor.  Many  failures  are  due  to 
neglect  of  this  simple  point  in  physics. 

Penetration  may  be  greatly  facilitated  by  a  partial  vacuum  before 
introducing  the  steam. 

Steam  is  applicable  to  the  disinfection  of  bedding,  clothing,  fabrics 
of  all  kinds,  and  a  great  variety  of  other  objects,  provided  certain  pre- 
cautions are  taken  to  prevent  shrinking,  staining,  running  of  colors,  etc. 
Steam  shrinks  woolens  and  injures  silk  fabrics;  it  ruins  leather,  fur, 
skins  of  all  kinds,  rubber  shoes,  oilcloth,  and  articles  made  of  impure 
rubber  or  containing  glue,  varnish,  or  wood. 

Food  of  all  kinds  is  sterilized  by  steam  in  the  process  of  canning. 

It  is  important  in  disinfecting  with  steam,  whether  with  streaming 
steam  or  steam  under  pressure,  to  expel  tJie  air  from  the  apparatus. 
The  air,  being  a  poor  conductor  of  heat,  forms  dead  spaces  and  prevents 
the  steam  coming  in  direct  contact  with  the  articles  to  be  disinfected, 
thereby  defeating  the  object  to  be  attained.  As  steam  is  lighter  than 
air  the  latter  can  best  be  expelled  from-  the  apparatus  by  admitting 
the  steam  from  above,  in  which  case  the  descending  column  of  steam 
forces  the  air  out  at  the  bottom.  If  the  steam  is  admitted  at  the  bottom 
it  swirls  up,  making  a  nearly  uniform  mixture  with  the  air,  and  while 
the  temperature  quickly  rises  in  the  apparatus  the  air  escapes  mixed 
with  the  steam,  so  that  it  takes  a  long  time  and  an  unnecessary  waste  of 
steam  to  drive  out  the  contained  air. 

Disinfection  with  streaming  steam  may  be  accomplished  in  many 
ways  without  the  use  of  special  apparatus.  For  rough  and  ready  work 
on  the  railroad  the  objects  to  be  disinfected  may  be  hung  in  a  freight- 


PHYSICAL  AGENTS  OF  DISTNFI-XJTION' 


1381 


car  and  the  steam  l)rought  from  the  hjeomotive.  On  hoard  a  vessel  one 
of  the  compartments  ahove  the  water-line  may  he  filled  with  steam 
from  the  boiler.  Objects  may  be  steanu'd  in  any  rough  structure  wherever 
a  boiler  is  found  to  furnish  the  steam.  Such  a  structure  need  not  be 
tight,  for  the  streaming  steam  escaping  from  the  cracks  produces  a  circu- 
lation and  favors  penetration. 

In  the  laboratory  small  objects 
are  disinfected  in  streaming  steam 
in  the  Arnold  steam  sterilizer  or  the 
Koch  steamer. 

On  account  of  the  great  cer- 
tainty with  which  steam  under  pres- 
sure acts  it  is  the  favorite  method 
in  practical  disinfection,  especially 
where  sterilization  is  required,  and 
devices  for  applying  this  process  on 
a  large  scale  have  reached  a  high  de- 
gree of  perfection.  The  smaller 
forms  of  steam  sterilizers  nnder 
pressure  are  known  as  digestors  or 
autoclaves  and  the  larger  ones  as 
steam  disinfecting  chambers. 

The  Autoclave. — The  autoclave, 
digestor,  or  steam  sterilizer  consists  of 
a  closed  kettle  usually  made  of  copper 
and  sufficiently  strong  to  withstand 
the  pressure.  Water  is  placed  in  the 
kettle  and  the  heat  is  applied  to  the 

bottom,  usually  by  means  of  several  Bunsen  gas  jets.  The  ap- 
paratus is  surrounded  as  high  as  the  shoulder,  where  the  lid  is 
attached,  with  a  metal  jacket  which  serves  the  purpose  of  bringing  the 
heat  of  the  flame  in  contact  with  the  entire  surface  of  the  kettle.  The 
lid  is  made  to  fit  tightly  by  means  of  screw  bolts  and  a  rubber  gasket. 
A  thermometer,  pressure  gauge,  safety  valve  and  a  small  opening  with  a 
stopcock  for  the  purpose  of  allowing  the  escape  of  the  air  are  provided. 
If  all  the  air  is  not  expelled  from  the  apparatus  the  dead  spaces  will 
have  a  much  lower  temperature  than  that  registered  on  the  thermometer. 
•For  instance,  the  steam  itself  may  register  a  temperature  of  130°  C, 
while  test  fluids  exposed  may  only  reach  70°  to  80°  C.  Therefore, 
in  using  this  form  of  sterilizer  it  is  customary  to  allow  the  steam  to 
escape  in  full  force  for  several  minutes  before  permitting  the  pressure 
to  rise. 

In  the  sterilization  of  liquids,  for  w'hich  this  apparatus  is  frequently 
used,  it  is  important,  at  the  conclusion  of  the  process,  not  to  take  off 


Fig.    166. — Sectiox  through 
Abnold  Steam  Sterilizeb. 


1382 


PHYSICAL  AGEXTS  OF  DlSINFECTIOISr 


SECUO.N       IHKCJlCH 

Autoclave. 


the  lid  or  open  the  valves,  or  in  any  other  way  release  the  pressure  until 
the  apparatus  has  cooled ;  otherwise  the  condensed  steam  causes  a  dimin- 
ished pressure,  in  which  the  heated  liquids 
will  boil  energetically,  resulting  in  a  bub- 
bling over,  a  blowing  out  of  stoppers,  or  a 
bursting  of  the  flasks.  It  is  therefore  nec- 
essary to  wait  until  the  pressure  is  zero, 
as  registered  on  the  gauge ;  or,  better,  un- 
til the  condensing  steam  produces  a  partial 
vacuum  and  the  air  is  automatically  sucked 
in  through  the  vacuum  valve,  vv'hich  is 
sometimes  fitted  in  the  lid  of  the  apparatus 
for  this  very  purpose. 

The  federal  regulations^  require  121° 
C.   (15  pounds)   for  30  minutes  for  steam 
sterilization  of  glassware  and  rubber  tub- 
ing.    Glassware  and  rubber  tubing  must  be 
moistened  immediately  before  steam  steri- 
lization and  each  flask  or  hollow  apparatus 
should  contain  one-eighth  of  its  volume  of 
water  when  put  in  the  autoclave.     This  is 
for  the  purpose  of  insuring  that  steam  will 
be  in  contact  with  all  surfaces. 

The  Steam  Chamber. — The  steam  dis- 
infecting chamber  has  reached  a  high'  de- 
gree of  usefulness  through  the  gradual 
perfection  of  the  details  of  its  working 
parts.  These  chambers  are  somewhat  com- 
plicated and  their  mechanical  construction 
must  be  mastered  in  order  to  insure  reli- 
able results.  Steam  disinfecting  chamber; 
may  be  used  with  streaming  steam  or  wilh 
steam  under  pressure;  with  formaldehyd 
gas  alone,  or  with  this  gas  in  combination 
with  dry  heat;  and,  finally,  with  various 
combinations  of  these  methods  with  or 
without  a  vacuum. 

The  disinfecting  chamber  itself  may  le 
rectangular  or  cylindrical  in  shape,  the 
former  giving  more  effective  space,  the 
latter  being  a  stronger  and  cheaper  method 
of  construction.     The  chamber  is  built  of 

an  inner  and  outer  shell  forming  a  steam  jacket,  as  shown  in  Figs 
'Regulations  U    S.  Public  Health  Service,  October  1,  1919. 


Fig.   168. — Bramhall-Deane 
Steam  Sterilizer. 


169 


PHYSICAL  AGENTS  OF  DISINFECTIOX 


1383 


aiifl  no.  Tlio  stoam  jacket  sorves  several  purposes.  By  hoatinf^  the 
contents  of  the  disinfecting  eyliiidcr  hefore  the  steam  is  turned  in  it 
avoids  condensation.  During  the  j)rocess  of  (h'siiifection  it  helps  keep 
the  steam  in  the  chamber  "live,"  thereby  preventing  the  Avetting  of  the 
objects  exposed.  After  the  disinfection  is  finished  and  the  chamber 
opened  the  heat  from  the  steam  in  the  jacket  may  be  used  to  dry  the 
objects  wliich  have  just  been  steamed.    Therefore,  in  using  this  apparatus 


PIPE 


Fig.  169. — Cross  Section  through  Steam  Disi>rFECTi>"G  Chamber. 


for  disinfecting  with  steam,  either  with  or  without  pressure,  the  steam 
is  kept  circulating  in  the  jacket  from  the  beginning  to  the  end  of  the 
process. 

In  the  jacket  the  steam  has  a  perfectly  free  circulation,  so  that  the 
entire  disinfecting  cylinder,  with  the  exception  of  the  doors,  is  sur- 
rounded by  live  steam.  The  outer  shell  of  the  jacket  is  insulated  with 
a  covering  of  sectional  magnesia,  asbestos,  or  some  other  non-conduct- 
ing substance. 

The  steam  from  the  boiler  passes  through  the  main  steam  pipe  A 
(Fig.  171)  to  the  pressure-reducing  valve  (2),  and  thence  to  the  bottom 
of  the  jacket  at  B,  B. 

Into   the   disinfecting   chamber  itself  the   steam   can   be   admitted 


1384 


PHYSICAL  AGENTS  OF  DISINFECTION 


only  from  the  jacket,  through  the  circulating  pipes,  A,  C,  B  (Fig. 
169),  and  after  circulating  through  the  disinfecting  chamber  in  the  di- 
rection as  shown  by  the  arrows  is  allowed  to  pass  out  with  the  drip 
through  the  drain  D   (Fig.  170).     Upon  the  completion  of  the  process 

-J- 


the  steam  may  be  blown  off  through  the  vacuum  pipe  F,  but  this  outlet 
should  not  be  used  during  the  steaming  because  the  desired  circulation 
would  not  be  obtained. 

It  will  be  noticed  that  the  steam  is  admitted  at  the  bottom  of  the 


PHYSICAL  AGENTS  OF  DISINFECTION 


1385 


■jacki't.  and  at  llir  lo/)  of  llir  (lisiiifoctiiiL!:  chaniher,  as  .shown  in  Fig.  169. 
The  ohject  of  admitting  the  steam  at  the  top  of  the  disinfecting  chamber 
is  to  favor  the  expulsion  of  the  air  through  its  outlet  at  the  bottom  by 
means  of  the  descending  column  of  steam.    Therefore;,  in  order  to  expel 


fe 


all  the  air  and  fill  the  chamber  with  steam  it  is  essential  to  open  the 
drain  D  (Fig.  170)  while  the  steam  is  entering  through  B,  B,  and 
this  outlet  D  should  not  be  closed  until  steam  escapes  freely.  In  using 
the  vacuum  attachment  to  expel  the  air  contained  in  the  apparatus  the 
modus   operandi   is   somewhat   different. 

To  determine  whether  all  the  air  has  been  expelled,   lead  a  pipe 


13^86  PHYSICAL  AGENTS  OF  DISINFECTION 

from  the  exhaust  to  a  bucket  of  water.  Air  reveals  itself  as  bubbles; 
steam  gives  the  well  known  hammer  effect, 

A  partial  vacuum  may  be  obtained  in  steam  chambers  of  this  type 
with  the  ejector  (4,  Fig.  l71).  The  object  of  the  vacuum  is  to  facilitate 
the  penetration  of  the  steam,  which  rushes  into  all  the  interstices  of 
fabrics  and  inaccessible  places,  to  take  the  place  of  the  air  which  has  been 
withdrawn.  The  ejector  works  upon  the  familiar  principle  of  the  water 
vacuum  pump,  the  air  being  draWn  or  sucked  along  with  the  current. 
With  a  pressure  of  80  pounds  in  the  boiler  and  the  valve  J  (Fig.  171) 
wide  open,  the  ejector  will  produce  a  partial  vacuum  of  15  inches  in  one 
of  the  largest  sized  chambers  in  one  minute,  which  is  very  much  quicker 
than  can  be  accomplished  with  the  ordinary  forms  of  piston  pumps. 

Any  steam"*^  disinfecting  chamber  may  have  attached  to  it  an  appa- 
ratus for -generating  formal dehyd  gas,  so  that  objects  that  are  injured 
by  exposure  to  steam  may  be  disinfected  with  formaldehyd",  plus  dry 
heat.  Before  the  formaldehyd  is  admitted  into  the  chamber  a  partial 
vacuum  may  be  established  by  means  of  the  ejector.  In  this  way  the 
penetriation  of  the  gas  is  very  much  facilitated. 

In'  the  best  patterns  the  steam  disinfecting  cylinders  are  open  at 
both  ejnds,  so  that  the  infected  objects  may  be  introduced  from  one  end 
and  taken  out  fn?m  the  other,  which  diminishes  the  risk  of  reinfecting 
them.  The  joint  between  the  door  and  the  chamber  is  made  tight  by 
means  of  a  heavy  rubber  gasket.  The  door  should  not  be  pressed  against 
this  gasket  more  firmly  than  is  found  necessary  to  retain  the  steam, 
otherwise  the  rubber  will  soon  be  rendered  useless.  When  not  in  use  the 
door  should  be  kept  open;  otherwise,  on  cooling,  the  metal  will  adhere 
to  the  rubber  gasket.  This  may  be  prevented  to  a  certain  extent  by 
keeping  the  rubber  gasket  covered  with  graphite. 

In  addition  to  the  above-mentioned  attachments  the  disinfecting 
chambers'  are  also  supplied  with  a  thermometer  (7,  Fig.  171).  The 
thermometer,  however,  may  be  so  close  to  the  jacket  that  it  is  influenced 
by  the  heat  in  the  jacket,  which  is  usually  higher  than  the  temperature 
of  the  interior  of  the  chamber.  The  thermometer  should  be  in  the  door,  or 
arranged  to  give  trustworthy  results.  In  disinfecting  v/ith  steam  under 
pressure  ithe  temperature  is  a  more  reliable  guide  than  the  pressure. 
There  are  forms  of  mercurial  and  metallic  thermometers  that  make  an 
electric  contact  when  a  certain  temperature  is  reached,  and  which  may 
be  connected  to  ring  a  bell.  They  have  a  decided  advantage  in  that 
they  may  be  placed  anywhere  within  the  chamber,  even  in  the  center 
of  bundles,  etc.,  and  are  more  trustworthy  than  any  form  of  mercurial 
instrument  fastened  through  the  heavy  metallic  walls  of  the  apparatus. 

An  ingenious  form  of  thermometer,  made  to  register  when  the  tem- 
perature reaches  100°  C,  has  been  designed  by  Merk,  and  is  shown  in 
the  accompanying-  illustration    (Fig.   172).     A  small  stick  of  the  me- 


PHYSICAL  AGENTS  OF  DISINFECTION  1387 

tallic  substance  whicli  is  supplied  with  the  instrument  and  whicli  melts 
at  exactly  100°  C,  fastened  at  A.  keeps  the  electrodes  at  B  and  C  apart 
The  entire  thermometer  D  is  then  placed  in  the  box  E  for  protection,  and 
this  is  placed  in  the  chamber  or  in  the  inside  of  bundles  to  be  disin- 
fected. The  insulated  wires  from  F  and  G  are  connected  with  a  battery 
and  bell.  As  soon  as  the  temperature  reaches  100°  C.  the  little  metal 
stick  melts,  the  contact  is  made  between  B  and  C,  and  the  bell  rings. 
This  form  of  thermometer  is  more  accurate  than  the  pyrometers,  which 
depend  upon  the  contact  being  made  by  the  unequal  expansion  of  a  com- 
pound metal  bar,  for  the  reason  that  moisture  collects  upon  the  electrodes 
and  an  electric  contact  is  sometimes  made  before  the  metal  parts  actually 
touch,  thereby  giving  false  readings. 

The  most  accurate  instrument  for  this  purpose  is  the  thermo-couple. 
Very  satisfactory  self-recording  thermometers  based  upon  the  principle 
of  expanding  gases  are  made  by  the 
Taylor  Instrument  Company  (page 
790). 

■  Steam  chambers  must  always  be 
provided  with  galvanized  or  copper 
hoods  to  prevent  rust-stained  drip 
from  soiling  the  clothing  and  other 

objects  exposed  to  the  steam ;  gauges 

,.,./,,,  T      ,  Fig.  172. — Automatic  Thermometeb. 

to  indicate  both  vacuum  and   steam 

pressure,  and  a  safety  valve  to  prevent  over-pressure  in  the  chamber. 

The  amount  of  pressure  from  the  boiler  is  regulated  by  a  reducing  valve 

in  the  main  steam  pipe. 

For  convenience  in  handling  the  goods  cars  are  provided,  of  light 
wTought-iron  construction,  with  movable  trays  made  of  galvanized 
screens ;  also  bronze  hooks  at  the  top  of  the  car,  permitting  the  articles 
to  be  laid  upon  the  trays  or  to  be  hung  up  on  the  hooks. 

In  the  accompanying  diagram  (Fig.  173)  the  method  of  installing 
the  steam  chambers  in  the  disinfecting  shed  of  a  quarantine  station  is 
shown.  It  will  be  noted  that  the  cylinders  are  open  on  both  ends,  and 
that  a  dividing  wall  running  across  the  building  separates  the  receiving 
end,  where  the  infected  objects  arrive  and  are  prepared  for  disinfection, 
from  the  discharging  end,  where  the  contents  of  the  chamber  are  aired, 
dried,  and  repacked  after  disinfection. 

This  separation  is  essential  where  a  large  amount  of  disinfection  is 
done  for  a  variety  of  diseases,  as,  for  example,  in  a  municipal  disinfect- 
ing establishment  or  at  the  quarantine  station  of  a  busy  port.  It  is 
true  that  the  virus  of  certain  diseases  is  not  apt  to  contaminate  the 
surroundings,  and  in  such  cases  there  would  be  little  risk  in  taking  the 
disinfected  articles  out  of  the  same  end  of  the  chamber  from  which  they 
are  put  in,  especially  if  the  exposed  surfaces  are  mopped  w^ith  a  disin- 


1388 


PHYSICAL  AGEXTS  OF  DISIXFECTIOX 


fectant  in  the  interim.     But  this  is  a  risk  that  need  not  be  taken; 
in  fact,  all  well-regulated  disinfecting  plants  maintain  a  rigid  separa- 


tion between  the  two  sides,  never  allowing  both  doors  of  the  chamber 
to  be  open  at  the  same  time,  and  providing  two  sets  of  workmen,  one 
for  the  "infected"  and  one  for  the  "disinfected"  side. 

The  chambers  must  be  loaded  with  care  in  order  to  obtain  reliable 


PHYSICAL  AGEXTS  OF  DISINFECTION  1389 

results  and  to  avoid  injuring  the  articles  exposed  to  the  process.  The 
packages  must  not  be  too  large  or  crowded  t(X)  closely,  for,  although  the 
vacuum  facilitates  the  penetration  of  the  steam,  there  is  a  limit  in  this 
regard;  it  takes  so  much  longer  for  disinfecting  agents  to  penetrate 
dense  packages  and  bundles  that  there  is  little  saving  of  time  and  a  dis- 
tinct loss  in  trustworthiness.  Steam  cannot  penetrate  compressed  bun- 
dles of  rags,  bales  of  cotton,  feathers,  hair,  or  other  packages  of  mer- 
chandise which  are  often  presented  for  disinfection,  except  by  aid  of 
the  vacuum. 


CHAPTEE  III 
CHEMICAL  AGENTS  OF  DISINFECTION 

GASEOUS  DISINFECTANTS— FUMIGATION 

A  germicidal  gas  would  be  an  ideal  weapon  for  destroying  such  in- 
visible foes  as  we  have  to  deal  with  in  public  health  work,  especially 
for  terminal  disinfection.  By  reaching  all  portions  of  a  room  jor  confined 
space  a  gas  lessens  the  risk  of  overlooking  any  surface  upon  which  the 
infective  agent  may  be  lodged,  but  an  efficient  gas  for  this  purpose  is  still 
to  be  discovered. 

There  is  practically  only  one  gas  suitable  for  general  application, 
viz.,  formaldehyd.  It  is  not  poisonous,  does  not  injure  fabrics,  colors, 
metals,  or  objects  of  art  and  value.  Formaldehyd,  however,  has  distinct 
limitations,  which  are  dealt  with  more  in  detail  under  the  description 
of  the  gas. 

Sulphur  dioxid  is  too  destructive  for  fabrics,  colors,  and  metals  for 
general  use.  It  is  a  better  insecticide  than  germicide.  It  is  very  poison- 
ous to  all  forms  of  animal  life,  which  makes  it  valuable  in  fumigating 
against  insect  and  animal-borne  diseases.  It  is  used  for  the  fumigation 
of  the  holds  of  ships,  cellars,  sewers,  stables,  and  other  rough  structures 
infested  with  vermin. 

Hydrocyanic  acid  gas  is  too  poisonous  to  use  in  the  household,  and 
is  limited  in  practice  to  the  destruction  of  infection  and  vermin  on 
board  ships,  in  warehouses,  greenhouses,  granaries,  railroad  cars,  and 
other  uninhabited  or  isolated  structures. 

The  very  poisonous  and  destructive  nature  of  chlorin  gas  contracts 
its  usefulness  to  narrow  limits. 

None  of  the  gaseous  agents  can  he  depended  upon  for  more  than  a 
surface  disinfection.  They  all.  lack  the  poiver  of  penetration.  Practically 
ail  tbe  gaseous  agents  are  not  disinfectants  but  fumigants.    See  page  266. 

Preparation  of  the  Room. — The  preparation  of  a  room  or  space  to  be 
fumigated  with  a  gas  is  a  matter  of  some  importance.  A  larger  amount 
of  gas  than  is  thought  possible  is  lost  through  leaks,  by  diffusion,  by 
absorption  and  in  other  ways;  therefore  the  room  should  be  made  tight, 
all  cracks  and  crevices  should  be  well  closed  by  pasting  paper  over  them 
or  by  caulking  with  suitable  material  of  some  kind.  Do  not  forget  to 
close  the  registers,  flues,  hearths,  and  ventilators,  and  look  carefully  for 

1390 


GASEOUS  DISINFECTANTS— FUMIGATION  1391 

openings  in  out-of-tlie-M;iy  })lat'es.  Tlicn  expose  the  objects  in  tlie  room 
so  that  the  gas  may  have  ready  access  to  all  the  surfaces.  ]\[ove  bureaus, 
beds,  and  furniture  away  from  the  walls;  open  doors  of  closets,  drawers 
of  Jbureaus,  lids  of  boxes,  and  the  like  so  that  the  gas  may  freely  enter 
and  diffuse  to  all  corners.  None  of  the  gases  can  he  depended  upon  to 
disinfect  clothing,  bedding  and  fahrics. 

"While  the  articles  in  the  room  nmst  be  arranged  so  that  the  gas  may 
freely  gain  access  to  all  surfaces  possible,  the  mistake  must  not  be  made 
of  going  to  the  opposite  extreme  of  disarranging  the  contents  of  the 
room  too  much,  for  the  same  surfaces  should  be  exposed  to  the  gas  that 
were  exposed  to  the  infection. 

The  strength  of  the  gas  and  time  of  the  exposure  necessary  to  insure 
disinfection  have  been  determined  by  exact  laboratory  experiments,  but 
the  conditions  found  in  actual  practice  are  so  variable  that  we  must 
allow  for  a  liberal  excess  to  make  up  for  inevitable  wastage.  Wind  pres- 
sure also  seriously  influences  the  efficiency  of  gaseous  disinfectants  in 
a  confined  space.  Much  more  air  than  is  commonly  thought  possible 
forces  its  w-ay  through  cracks  and  through  the  walls  themselves.  The 
wind  pressure  may  thus  drive  the  fumigating  gas  entirely  away  from 
one  side  of  the  room.  It  is  only  necessary  to  stand  upon  the  leeward  side 
of  a  structure  being  disinfected  with  sulphur  dioxid  or  formaldehyd  to 
realize  the  great  quantity  of  gas  blown  from  the  enclosure.    See  page  2G(). 

Formaldehyd  Gas. — Formaldehyd  ^  is  the  most  generally  useful  and 
one  of  the  best  disinfecting  gases  that  we  possess.  Its  superiority  de- 
pends upon  its  high  value  as  a  germicide,  its  non-poisonous  nature,  and 
upon  the  fact  that  it  is  not  destructive.  The  secret  of  successful  disin- 
fection with  this  substance  is  to  obtain  a  large  volume  of  the  gas  in  a 
short  time. 

Formaldehyd  (HCHO)  exists  in  at  least  three  w^ell-recognized  iso- 
meric states :  -  - 

(1)  Formaldehyd  (formic  aldehyd)  is  a  gas  at  ordinary  tempera- 
tures, colorless,  and  possessing  slight  odor,  but  having  an  extremely  irri- 
tating effect  upon  the  mucous  membranes.  At  a  temperature  of  about 
— 20°  C.  the  gas  polymerizes  into  paraformaldehyd,  known  commercially 
as  paraform. 

(2)  Paraform  is  a  white  substance,  unctuous  to  the  touch,  soluble 
in  both  water  and  alcohol.  It  consists  chemically  of  tw^o  molecules 
of  formaldehyd.  It  is  this  substance  which  is  supposed  to  compose  the 
commercial  solutions  of  formaldehyd  known  as  formalin,  formol,  etc. 

(3)  Trioxymethylene  is  formed  by  the  union  of  three  molecules  of 
formaldehyd.  It  is  a  white  powder  giving  off  a  strong  odor  of  the  gas. 
It  is  but  slightly  soluble  in  alcohol  and  water. 

Formaldehyd  gas  possesses  about  the  same  specific  gravity  as  air; 

^Formaldehyd  is  the  gas,  formalin   is  tlie  aqueous  solution  of  the  gas. 


1393  CHEMICAL  AGENTS  OF  DISmFECTION 

it  diffuses  slowly,  although  somewhat  better  than  sulphur  dioxid.  Form- 
aldehyd  combines  with  nitrogenous  organic  matter.  A  few  drops  added 
to  the  white  of  an  egg  will  prevent  its  coagulation  by  heat.  The  form- 
aldehyd  unites  with  the  albumin  to  form  a  totally  new  compound. 
Combined  with  gelatin  it  keeps  that  substance  from  liquefying.  It  is 
from  this  property  of  combining  directly  with  the  albumins  forming  the 
protoplasm  of  the  microorganisms  that  formaldehyd  is  supposed  to  de- 
rive its  power  as  a  germicide.  It  is  perfectly  plain,  therefore,  why  there 
must  be  direct  contact  between  the  gas  and  the  germ  in  order  to  accom- 
plish disinfection, 

Formaldehyd  also  unites  readily  with  the  nitrogenous  products  of  de- 
composition, forming  new  chemical  compounds  which  are  both  odorless 
and  sterile.  It  is  thus  a  true  deodorizer  in  that  it  does  not  mask  one 
odor  by  another  still  more  powerful,  but  forms  new  chemical  bodies 
which  possesa  no  odor. 

Formaldehyd  apparently  has  no  detrimental  effects  upon  silks,  wool- 
ens, cotton  and  linen.  It  does  not  change  colors,  with  the  exception 
possibly  of  a  slight  effect  upon  some  of  the  delicate  aniline  lavenders.  An 
oil  painting  is  not  perceptibly  altered  after  prolonged  exposure  to  the 
gas.  The  metals  are  not  attacked.  It  is  this  non-destructive  property 
of  the  gas  that  renders  it  generally  applicable.  It  is  practically  the  only 
gaseous  germicide  which  can  be  used  in  the  richest  apartments,  contain- 
ing objects  of  art  and  value,  without  fear  of  damage. 

The  commercial  solutions  known  as  formalin  are  said  to  contain  40 
per  cent,  of  formaldehyd  gas.  They  are  not  always  up  to  standard  (aver- 
age 36  per  cent.),  and,  being  volatile,  there  is  a  certain  loss  if  not  well 
kept.  In  winter  there  is  a  decided  deterioration,  owing  to  the  polymeri- 
zation and  precipitation  of  trioxymethylene.  This  substance  is  often 
found  in  abundance  at  the  bottom  of  the  bottle  or  carboy  as  a  white  pre- 
cipitate. For  these  reasons  it  is  well  to  use  an  excess  of  the  liquid  in 
practical  work  if  the  exact  strength  of  the  formalin  has  not  recently  been 
determined. 

Formalin  solutions  of  commerce  are  almost  all  acid  in  reaction,  due 
in  part  to  formic  acid.  Some  of  the  commercial  solutions  also  contain 
a  certain  amount  of  wood  alcohol  (about  10  per  cent.)  which  is  added 
to  increase  their  solubility  and  stability. 

A  certain  amount  of  heat  and  moisture  is  necessary  to  obtain  suc- 
cessful disinfection  with  formaldehyd  gas.  The  exact  amount  of  mois- 
ture necessary  depends  somewhat  upon  the  temperature.  As  a  general 
working  rule  it  mav  be  stated  that  if  the  temperature  is  below  65°  F. 
or  if  the  relative  humidity  is  heJow  60  per  cent,  the  results  become  irregu- 
lar; much  below  these  figures  the  results  are  unreliable,  especially  if  the 
space  is  both  cold  and  dry.  Formaldehyd  polymerizes  at  low  tempera- 
tures, therefore  in  cold  weather  it  may  be  necessary  artificially  to  warm 


GASEOUS  DISINFECTANTS— rilMTGATTON  1393 

the  room  to  be  disiiilVi'ted.  Jii  dry  weatlusr  moisture  slioidd  he  iKidcd  to 
the  room. 

Formaldehyd  gas  cannot  be  depended  upon  to  accomplish  more  than 
a  surface  disinfection.  Under  ordinary  circumstances  it  possesses  small 
powers  of  penetration.  The  gas  polymerizes  in  the  meshes  of  the  fabric 
and  is  deposited  as  paraform  upon  surfaces.  Large  quantities  of  formal- 
dehyd are  lost  by  uniting  chemically  with  the  organic  matter  of  fabrics, 
especially  woolens,  which  further  hinders  its  penetration.  Therefore, 
formaldehyd  gas  cannot  be  relied  upon  to  disinfect  fabrics,  especially 
quilted  goods  and  materials  requiring  deep  penetration. 

Formaldehyd  gas  has  the  power  of  killing  spores,  although  not  with 
sufficient  certainty  to  render  it  a  trustworthy  agent  for  infections  such 
as  anthrax  and  tetanus.  It  has  the  great  advantage  of  killing  dry  micro- 
organisms, although  not  quite  so  readily  as  when  they  .are  moist. 

Bacteria  exposed  directly  to  the  action  of  a  concentrated  volume  of 
formaldehyd  gas  are  killed  almost  instantly,  but  in  practical  work  it  is 
necessary  to  prolong  the  time  of  exposure  to  6  or  12  hours,  as  it  takes 
considerable  time  for  the  gas  to  permeate  to  all  the  corners  and  dead 
spaces  of  a  room.  Bacteria  are  not  always  directly  exposed  upon  the  sur- 
face of  objects,  as  they  are  in  laboratory  experiments,  and,  furthermore, 
they  are  frequently  imbedded  in  albuminous  matter  or  in  dust,  both  of 
which  retard  the  action  of  the  gas. 

Formaldehyd  gas  is  not  very  toxic  to  the  higher  forms  of  animal  life, 
although  it  stands  at  the  head  of  the  list  of  germicides.  Long  exposure 
to  weak  atmospheres  of  the  gas  sufficient  to  kill  germs  has  but  slight 
effect  upon  animals.  Guinea-pigs,  rats,  mice,  and  rabbits  exposed  to 
concentrated  atmospheres  are  not  killed  after  half  an  hour's  exposure. 
The  only  effect  produced  is  a  violent  irritation  of  the  mucous  membranes 
of  the  respiratory  tract,  from  which  the  animals  may  subsequently  die. 
Microorganisms  exposed  to  this  same  concentration  of  the  gas  are  killed 
almost  instantly. 

Formaldehyd  is  rapidly  absorbed  from  all  parts  of  the  gastro-intes- 
tinal  tract  and  lungs,  and  may  be  excreted  again  by  them.  It  is  rapidly 
oxidized  in  the  body  to  formic  acid  and  carbonates.  There  is  also  a  small 
amount  of  a  dialyzable  compound  formed  in  the  blood  which  is  most 
probably  hexamethylenamin  since  the  latter  is  found  in  the  urine.  Small 
amounts  of  formaldehyd  may  pass  through  the  body  without  causing  ap- 
parent inflammation,  while  large  amounts  always  cause  some. 

Formaldehyd  is  not  an  insecticide.  In  the  strongest  concentrations 
of  the  gas  obtainable  it  seems  to  have  practically  no  effect  upon  roaches, 
bedbugs,  and  insects  having  strong  chitinous  coverings.  It  may  kill  the 
frailer  insects,  but  its  action  is  uncertain ;  thus  mosquitoes  may  live  in  a 
weak  atmosphere  of  the  gas  over  night. 

Upon  the  completion  of  the  time  required  to  disinfect  a  room  it  is 


1394 


CHEMICAL  AGENTS  OF  DISINFECTION 


best  to  open  all  the  doors  and  windows  and  let  the  gas  blow  away.  This 
may  be  a  troublesome  procedure.  If  the  windows  can  be  reached  from 
the  outside  it  is  easy  enough,  but  if  the  room  must  be  entered  it  is  ad- 
visable for  the  operator  to  cover  his  mouth  and  nose  with  a  moist  towel 
and  act  quickly.  It  was  formerly  the  custom  to  neutralize  the  gas  with 
ammonia,  but  this  is  little  practiced  now.  The  ammonia  neutralizes  the 
formaldehyd  by  the  production  of  hexamethylenetetramin. 

Formaldehyd  may  be  released  from  its  watery  solution  by  any  actively 
oxidizing  agent.  Potassium  permanganate  is  the  best,  for  it  liberates 
the  largest  volume  of  gas,  and  in  the  shortest  time;  but,  on  account  of 
the  high  cost  of  this  chemical  during  the  war,  the  following  may  be 

substituted :  bleaching  powder,  un- 
slacked  lime,  sodium  dichromate, 
barium  oxid.  Permanganate  liber- 
ates about  60  per  cent,  of  the  gas; 
dichromate,  about  30  per  cent.,  and 
bleaching  powder  about  25  per 
cent.  In  the  case  of  bleaching 
powder  only  about  3  per  cent,  of 
the  total  gas  set  free  is  chlorin. 

The  Permanganate  -  Formalin 
Method. — Use  500  c.  c.  of  forma- 
lin and  250  grams  of  potassium 
permanganate  for  each  thousand 
cubic  feet  of  air  space.  The  per- 
manganate is  first  placed  in  a 
bucket  or  basin  and  the  formalin 
poured,  upon  it.  An  active  efEer- 
vescence  takes  place  and  consider- 
able heat  is  evolved;  therefore  a 
pail  of  sufficient  capacity,  and  espe- 
cially of  sufficient  height,  should  be 
used  to  prevent  splashing  or  boiling  over.  In  Board  of  Health  work 
it  is  advisable  to  have  galvanized  iron  pails  made  for  this  purpose  with  a 
flaring  top.  The  floor  should  be  protected  against  the  heat  by  placing 
the  bucket  upon  a  brick,  board,  or  other  suitable  device. 

When  the  permanganate  of  potassium  and  formalin  are  brought  in 
contact  very  active  oxidation  takes  place,  with  the  production  of  formic 
acid  and  heat.  It  is  the  heat  that  liberates  the  formaldehyd  gas.  Chem- 
ically, therefore,  the  method  is  a  wasteful  one,  but  practically  a  very 
serviceable  one.  It  was  first  described  by  Johnson  of  Sioux  City,  Iowa, 
in  1904.  In  the  same  year  Evans  and  Eussell  of  Augusta,  Maine,  used 
the  method.^ 

"  14th  Ann.  Rep.,  State  Board  of  Health  of  Maine,  1906, 


Fig.  174. — Flaring  Top  Tin  Bucket 

FOB   GeNEKATING   FORMALDEHYD   BY   THE 

Permanganate  Method.  Height  15 
inches,  diameter  10  inches  at  base,  15 
inches  at  top  of  flare. 


GASEOUS  DTSTXFKCTAXTS— FUMIGATION"  1395 

The  formula  recommended  b^^  the  Pennsylvania  Department  of 
Health  is : 

Sodium  dichromate 10       ounces 

Formalin   16  " 

Commercial  sulphuric  acid  IV2        " 

The  sulphuric  acid  can  he  added  to  the  formalin  and  the  mixture 
kept  on  hand  for  use;  polymerization  in  cold  weather  can  be  avoided  by 
the  addition  of  glycerin,  li/o  ounces.  The  acid  formalin  is  poured  on 
the  crystals  of  sodium  dichromate  and  formaldehyd  gas  is  at  once  liber- 
ated. 

The  Formalin-Lime  and  Aluminium-Sulphate  Method.  —  This 
method  was  first  described  by  "Walker  of  the  Department  of  Health, 
Brooklyn,  N.  Y.  It  is  somewhat  slower  than  the  potassium  permanga- 
nate method,  but  otherwise  appears  to  be  just  as  efficient. 

The  proportions  for  each  1,000  cubic  feet  are  as  follows: 

Sol.  A. — Aluminium  sulphate 150  grams 

Dissolved  in  hot  water 300  c.  c. 

Sol.  5.— Formalin  (40  per  cent.  CHOH)   600  c.  c. 

Lime. — Unslaked  lime 2,000  grams 

Mix  solutions  A  and  B  and  pour  upon  the  lime. 

In  practical  work  20  to  25  pounds  of  the  commercial  aluminium  sul- 
phate is  dissolved  in  5  gallons  of  hot  water.  This  is  sufficient  to  mix  with 
15  gallons  of  a  40  per  cent,  formaldehyd  solution  and  then  used  in  the 
proportions  as  stated  above.  The  lime  should  be  freshly  burned,  broken 
into  small  particles,  and  should  slake  rapidly  in  cold  water.  The  lime  is 
placed  in  a  large  bucket.  The  formalin  and  aluminium  sulphate  solu- 
tions should  be  mixed  and  poured  over  the  lime.  In  a  few  minutes 
the  lime  begins  to  slake  and  the  heat  evolved  drives  off  the  formaldehyd 
gas. 

The  banum-formalin  method  was  developed  by  Candall,^  and  consists 
of  one  pint  of  formalin  (solution  of  formaldehyd  U.  S.  P.)  and  one  and 
one-half  pounds  barium  oxid  containing  not  less  than  78  per  cent,  barium 
diosid  for  each  1,000  cubic  feet  to  be  disinfected. 

Bleaching-Powder  Method. — Place  in  a  mixing  pan  12  ounces  of 
chlorinated  lime,  4  ounces  of  water ;  stir  to  a  paste.  Then  pour  1  pound 
formalin  over  the  moistened  lime.  This  is  sufficient  for  1,000  cubic 
feet. 

The  Spraying  Method. — Spraying  formalin  is  a  satisfactory  and 
simple  method  of  disinfecting  small  inclosures,  such  as  wardrobes, 
closets,  and  cabinets.  It  is  not  practical  for  larger  rooms.  If  the  for- 
malin is  sprayed  directly  upon  the  objects  to  be  disinfected  they  enjoy 

^U.  8.  Naval  Medical  Bull,  Oct.,  1917,  p.  519. 


1396  CHEMICAL  AGENTS  OF  DISINFECTION 

the  direct  germicidal  action  of  the  substance  in  solution  and,  further,  are 
bathed  in  the  gas  which  is  slowly  evolved.  The  method  is  particularly- 
serviceable  for  the  disinfection  of  bureau  drawers,  closets,  valuable  books 
and  manuscripts,  jewelry,  objects  of  art,  etc.  When  used  to  disinfect 
small  rooms  suspend  a  bed  sheet  from  a  line  stretched  across  the  middle 
of  the  room.  An  ordinary  bed  sheet  presenting  a  surface  of  about  2  by 
2%  yards  is  required  for  every  1.000  cubic  feet  of  space  of  the  room. 
Properly  sprinkled  this  will  carry,  without  dipping,  8  ounces  of  formalin. 
The  ordinary  sprinkling  pot  used  by  florists  can  be  used  to  spray  the 
sheets  and  a  liberal  excess  should  be  used.  The  room  should  remain 
closed  not  less  than  eight  hours. 

The  other  methods  for  disinfecting  with  formaldehyd  gas  are  not 
described  because  most  of  them  are  unreliable,  and  none  of  them  is 
as  serviceable  in  practical  work  as  the  formalin-permanganate  method 
or  the  formalin -lime  method. 

Sulphur  Dioxid. — Sulphur  dioxid  (SOo)  is  not  an  efficient  germi- 
cide, but  is  exceedingly  poisonous  to  mammalian  and  insect  life.  It 
is  this  property  which  makes  it  of  especial  value  as  a  fumigant  against 
diseases  spread  by  rats,  mice,  flies,  fleas,  mosquitoes,  etc. 

The  action  of  sulphur  dioxid  as  a  germicide  depends  upon  the  pres- 
ence of  moisture.  The  dry  gas  is  practically  inert  against  bacteria.  Sul- 
phur dioxid  cannot  be  depended  upon  where  penetration  is  required.  Its 
action  is  merely  upon  the  surface.     It  does  not  kill  spores. 

Sulphur  dioxid  possesses  the  advantage  of  being  cheap  and  readily 
procurable.  There  is  hardly  a  crossroad  store  in  the  country  where  a 
reasonable  quantity  of  sulphur,  either  in  the  form  of  flowers  or  in  rolls 
or  sticks  under  the  name  of  brimstone,  cannot  be  obtained.  Sulphur 
dioxid  is  especially  applicable  to  the  holds  of  ships,  freight-cars,  gran- 
aries, stables,  out-houses,  and  similar  rough  structures — particularly  if 
infested  with  vermin. 

The  disadvantages  of  sulphur  dioxid  as  a  disinfecting  agent  are  such 
as  to  contract  its  application  to  rather  narrow  limits.  It  bleaches  all 
coloring  matter  of  vegetable  origin  and  many  anilin  dyes.  It  attacks 
almost  all  metals ;  it  acts  upon  cotton  and  linen  fabrics  so  as  seriously  to 
weaken  their  tensile  strength,  especially  if  starched. 

Sulphur  dioxid  is  a  heavy,  colorless,  irrespirable  gas  with  a  peculiar 
suffocating  odor  and  irritating  properties.  It  has  a  density  of  2.4.  On 
account  of  the  heavy  specific  gravity  as  compared  with  air  it  diffuses 
slowly  and  then  settles  toward  the  bottom  of  the  compartment. 

Cold  water  takes  up  more  than  30  times  its  volume  of  sulphur  dioxid. 
The  solution  contains  sulphurous  acid  (H^SOg),  and  it  is  in  reality 
this  acid  that  is  the  disinfecting  agent.  The  dry  gas  is  therefore  inert 
and  moisture  is  essential  in  order  to  obtain  any  germicidal  effect.  It  is 
also  this  acid  and  some  sulphuric  acid  which  has  such  a  destructive  effect 


GASEOUS  DISIXFKCTAXTS— FUMICxATION"  1397 

upon  fibers,  colors,  and  iiu'tals.  'Vho  corrnsivp  aftion  of  Ihcse  acids  upon 
fabrics  takes  place  slowly,  and  \\\o  daniai:!'  may  lar<,fely  be  obviated  if 
tbey  are  M'asbed  at  once.  Metal  \vori<  may  \)o  prntcclcd  l)y  coatin^i;  it  with 
a  thin  layer  of  vaselin  or  heavy-l)odied  oil. 

Sulphur  dioxid  may  readily  be  condensed  into  a  clear  liquid  by  either 
cold  or  pressure  or  a  combiiuition  of  both.  At  ordinary  atmospheric 
pressure  it  coiulenses  if  the  temperature  is  reduced  to  — 18°  C,  which 
is  about  the  temperature  of  a  mixture  of  ice  and  salt.  At  ordinary  tem- 
})eratures  it  liquefies  if  the  pressure  is  raised  to  about  four  atmospheres, 
that  is,  60  pounds.  This  liquid  is  a  stable  substance  when  kept  well 
sealed  and  protected  from  the  action  of  the  air.  It  rapidly  volatilizes 
when  poured  into  an  open  vessel.  It  is  now  found  in  commerce  and  is 
one  of  the  methods  used  for  producing  the  gas  for  fumigating  purposes. 

The  complete  combustion  of  1  pound  of  sulphur  in  a  space  of  1,000 
cubic  feet  will  theoretically  produce  1.115  per  cent,  of  sulphur  dioxid, 
but  this  amount  cannot  be  obtained  in  practice  because  the  sulphur  of 
commerce  contains  impurities  such  as  sulphate  of  lime  and  sand,  and  a 
portion  of  the  burning  sulphur  is  always  oxidized  to  the  formation  of  ill- 
defined  compounds.  Therefore  one  pound  may  be  considered  as  pro- 
ducing approximately  1  per  cent,  of  the  gas  by  being  burned  in  1,000 
cubic  feet  of  space,  and  five  pounds  will  generate  approximately  5  per 
cent.,  which  is  the  maximum  theoretical  amount  obtainable  by  burning 
sulphur  in  a  confined  space.  Five  pounds  per  1,000  cubic  feet  is  the 
amount  generally  used  when  a  germicidal  action  is  desired.  Somewhat 
less,  two  to  four  pounds,  is  sufficient  to  destroy  insects  and  rats.  See 
pages  517  and  269. 

The  amount  of  moisture  necessary  to  convert  sulphur  dioxid  into 
sulphurous  acid  is  readily  computed.  It  will  be  found  that  one-fifth  of 
one  pound  of  water  should  be  volatilized  for  each  pound  of  sulphur 
burned.  The  water  may  be  added  in  the  form  of  steam  or  in  the  form 
of  a  finely  divided  spray,  or  it  may  be  vaporized  by  the  heat  generated 
by  the  combustion  of  the  sulphur  itself.  The  latter  method  is  the  one 
that  commends  itself  in  practical  use,  and  is  described  under  the  "pot 
method." 

While  moisture  is  essential  for  the  germicidal  action  of  sulphur 
dioxid,  it  is  not  necessary  in  order  to  kill  insects  and  small  mammals. 
Dry  sulphur  dioxid  is  quite  as  efficacious  against  rats,  mice,  fleas,  flies, 
mosquitoes,  bedbugs,  roaches,  etc.,  as  the  moist  gas. 

In  disinfecting  with  sulphur  dioxid  it  is  necessary  to  seal  the  com- 
partment tightly.  The  gas  is  disengaged  so  slowly  that  it  may  escape 
through  cracks  and  crevices  almost  as  fast  as  it  is  formed.  In  cold 
weather  the  heating  of  the  room  to  be  disinfected  will  greatly  aid  in 
the  disinfecting  action  of  the  gas. 

There  are  three  well-recognized  methods  of  fumigating  with  sulphur 


1398 


CHEMICAL  AGENTS  OF  DISINFECTION 


dioxid,  viz.,  (1)  the  pot  method,  (2)  liquid  sulphur  dioxid,  (3)  sulphur 
furnace. 

The  Pot  Method. — The  pot  method  is  at  once  the  easiest,  cheapest, 
and  probably  most  efficient  method  of  using  sulphur  dioxid.  The  only 
materials  required  are  iron  pots  and  some  sulphur.  The  best  way  to 
apply  the  method  is  by  placing  the  sulphur  in  large,  flat,  iron  pots  known 
as  Dutch  ovens.  Not  more  than  30  pounds  of  sulphur  should  be  placed 
in  each  pot.  The  sulphur  is  preferably  used  in  the  form  of  flowers  of  sul- 
phur. If  it  is  in  sticks  or  rolls  it  should  be  crushed  into  a  powder,  which 
may  conveniently  be  done  by  placing  the  sulphur  in  a  stout  box  and 
pounding  the  lumps  with  a  heavy  timber.  The  pot  holding  the  sulphur 
should  be  placed  in  a  tub  of  water,  as  shown  in  Fig.  175.  The  water  not 
only  diminishes  the  danger  from  fire  and  protects  the  floor,  but  by  its 
evaporation  furnishes  the  moisture  necessary  to  hydrate  the  sulphur 
dioxid,  upon  which  the  disinfecting  power  of  the  gas  depends..  Thus  the 
moisture  is  furnished  automatically  and  does  away  with  the  necessity 

^     for  its  introduction  by  means 


of  steam  or  a  spray.  Although 
the  specific  gravity  of  sulphur 
dioxid  is  greater  than  that  of 
air,  when  hot  it  rises,  aided 
by  the  upward  current  pro- 
duced by  the  burning  sul- 
phur. '  Hence  the  pots  should 
of   the   hold   in   the    case   of 


Fig.  175. — The  Pot  Method  of  Burning  Sul- 
phur. 


not  be  on  the  floor,  or  at  the  bottom 
vessels,  lest  the  cold  gas  settle  and  the  flame,  being  deprived  of 
oxygen,  be  extinguished  before  all  the  sulphur  is  burned.  The  pots 
may  therefore  be  placed  upon  a  table  or  box  or,  in  the  holds  of  ships, 
upon  piles  of  ballast  or  on  the  "  'tween  decks." 

Roberts  and  McDermott  *  suggest  that  the  sulphur  be  burned  upon 
pans  arranged  upon  a  rack,  as  shown  in  Fig.  176,  instead  of  pots.  The 
advantages  of  this  stack  burner  are  that  a  large  amount  of  sulphur  may 
be  more  quickly  burned  in  less  time  than  is  possible  with  the  pot  method. 
Further,  the  intense  heat  below  each  pan  in  the  stack  burner  aids  the 
complete  and  rapid  burning  of  sulphur  in  the  pans  above  it.  A  stack 
burner  will  burn  sulphur  of  too  poor  a  quality  to  give  any  satisfaction  in 
the  pots.  The  ground  sulphur  is  placed  in  the  pans,  the  surface  of  the 
sulphur  is  moistened  with  alcohol,  and  ignited.  Each  shelf  should  be 
lighted  separately  to  save  time.  The  upper  pan  or  pans  may  be  filled 
with  water  to  hydrate  the  sulphur  dioxid  necessary  for  its  germicidal 
action. 

The  sulphur  may  be  lighted  by  means  of  hot  coals  or  a  wood  fire, 

"^  Public  Health  Reports,  U.  S.  P.  H.  and  M.  H.  S.,  March  31,  1911,  Vol. 
XXVI,  13,  p.  403. 


GASEOUS  DTSIXFECTAXTS— FUMICIATIOX  1399 

but  the  most  reliable  way  to  get  it  well  lighted  is  by  alcohol,  turpentine, 
or  kerosene  on  a  pledget  of  waste.  Make  a  little  crater  of  the  sulphur, 
soak  liberally  with  alcohol,  and  ignite.  The  sulphur  then  burns  in  the 
center,  and  as  it  melts  runs  down  from  the  sides  and  forms  a  little  lake 
at  the  bottom  of  the  crater.  If  the  sulphur  is  heaped  up  in  a  mound 
in  the  pot  the  flame  is  liable  to  go  out. 

Upon  the  principle  of  hot  putting  all  our  eggs  in  one  basket,  it  is 
best  to  have  a  number  of  pots  when  a  large  compartment  is  to  be  fumi- 
gated. A  pot  should  contain  not  more  than  30  pounds  of  sulphur,  and 
the  pots  should  be  well  distributed  in  various  portions  of  the  place  to 
be  disinfected. 

Use  5  pounds  per  1.000  cubic  feet  where  a  germicidal  action   is 


Fig.  176. — Labge  Stack  Burxee  for  Sulphur,  with  1.5  of  the  18  Pa^s  Re- 
MO\'ED  TO  Show  Coxstkuctiox. 


desired,  and  at  least  2  pounds  per  1,000  cubic  feet  for  insecticidal  pur- 
poses. For  the  destruction  of  bacteria  an  exposure  of  from  6  to  24 
hours  is  necessarv',  while  for  the  destruction  of  vermin  from  2  to  12 
hours  is  sufficient,  depending  upon  the  size  and  shape  of  the  compart- 
ment to  be  treated^ 

Liquid  Sulphur  Dioxid. — Liquid  sulphur  dioxid,  commonly  known 
as  sulphurous  acid  gas,  while  efficient,  is  about  ten  times  as  expensive 
as  burning  sulphur  by  the  pot  method.  It  has  the  advantage  of  liber- 
ating a  large  volume  of  the  gas  rapidly,  thereby  facilitating  its  dispersion. 
Further,  the  use  of  liquefied  sulphur  dioxid  has  the  advantage  of  avoid- 
ing the  danger  of  accidental  fire. 

One  pound  of  burning  sulphur  will  produce  about  2  pounds  of  sul- 
phur dioxid:  S(32)  +  0,(32)  =  SO^CGi).  Therefore  2  pounds  of  the 
liquid  sulphur  dioxid  is  necessary  to  produce  the  same  volume  of  sulphur 
dioxid  as  is  generated  from  one  pound  of  the  burning  sulphur. 


1400 


CHEMICAL  AGENTS  OF  DISINFECTION 


The  method  of  using  the  liquid  sulphur  dioxid  is  very  simple.  If 
the  substance  is  bought  in  small  tins  it  is  only  necessary  to  cut  the 
lead  pipes  in  the  tops  of  the  necessary  number  of  cans  and  invert  the 
latter  in  an  ordinary  washbowl  or  iron  pot,  when  volatilization  rapidly 
occurs.  All  the  cans  must  be  cut  simultaneously  and  the  operator  must 
act  quickly  and  be  prepared  immediately  to  leave  the  room  and  shut 
the  door.  If  the  substance  is  contained  in  glass  or  metallic  siphons 
the  necessary  amount  of  liquid  sulphur  dioxid  can  be  projected  from 
the  outside  through  a  pipe  passed  through  the  keyhole  or  other  aperture. 
A  suitable  receptacle  should  be  arranged  on  the  inside  to  catch  the  drip 
and  frozen  mass  which  forms  as  a  result  of  the  expansion.  In  order  to 
obtain  the  maximum  disinfecting  power  with  this  method  it  is  necessary 
to  introduce  moisture.  This  may  be  done  by  placing  open  pans  of  boil- 
ing water  in  the  room,  by  injecting  steam,  or  by  a  fine  spray  of  water. 

The  Sulphur  Furnace- — The  sulphur  may  be  burned  ^ in  an  ap- 
paratus of  special  construction  known  as  a  sulphur  furnace,  from  which 


^^^ 


Sulphur  Dioxide  (SOz) 

_       A    Safi   liiui  ICffeClivc    Disni/echuit. 

Th.s  Cylir.d,;r  contains   about    20    oun.-.-s    of    Sulphur    Dioxid 
coinmoniy  known  as    Sulphurovis  Acid   Gas,    c-.indcr.ied    intu 
liquid  by  pressure  ;    and  is  equal,  in  c!k 
weight   of  Sulphur   as  orrtis.-jrily  burnt  f. 


about  double  it 


=lVc-ci!vc-Iy  disinfi-ol 


FiG.  177. — Liquefied  Sulphuk  Dioxid  in  Tin  Can. 


the  resulting  fumes  are  blown  through  a  system  of  pipes  into  the  room 
or  hold  of  a  vessel  to  be  disinfected.  Two  forms  of  sulphur  furnace  are 
used:     (1)  the  Kinyoun-Francis  furnace,  and  (2)  the  Clayton  furnace. 

This  method  requires  expensive  and  cumbersome  machinery  and 
has  little  to  recommend  it  over  the  simpler  pot  method  except  that  a 
large  percentage  of  the  gas  may  be  blown  into  a  given  space.  The  pot 
method  at  best  cannot  produce  an  atmosphere  containing  more  than  4 
per  cent,  of  sulphur  dioxid,  whereas  it  is  theoretically  possible  to  charge 
a  confined  space  with  a  higher  percentage  of  the  gas  by  means  of  the 
furnace.  In  practice  this  is  not  possible  without  humming  a  great  excess 
of  sulphur  and  by  expending  a  very  long  time,  for  the  reason  that  the 
fumes  first  entering  mix  with  the  air  and  as  the  gas  continues  to  flow 
into  the  space  it  displaces  about  an  equal  quantity  of  this  mixture  of 
sulphur  dioxid  and  air,  so  that,  as  a  matter. of  fact,  in  actual  practice 
only  about  21/0  to  6  per  cent,  of  the  gas  is  usually  obtained  in  the  holds 
of  vessels  by  the  sulphur  furnace. 

It  is  advisable  in  using  the  sulphur  furnace  to  arrange  the  pipe  ad- 
mitting the  gas  into  the  room  as  near  the  floor  as  possible.  In  disinfect- 
ing the  holds  of  vessels  the  pipe  is  usually  let  down  the  hatchway  until 


GASEOTTS  DTSTNFECrAX'rS— KC.MKIA'IIOX  1  101 

it  is  near  the  liili;i'.  'Flic  licm  v  .u;is  collects  at  the  bottom  and  <rra(lually 
ascends,  displaein<i-  the  air,  so  that  it  is  iiii|iortaiit  to  allow  an  opening 
of  some  sort  for  the  exit  of  the  air  near  the  top  of  the  compartment  that 
is  being  disinfected.  This  o))ening  sliould  not  be  closed  until  the  gas 
escapes  freely. 

The  Kini/oiin-Fnincis  fiiniticc  consists  of  an  iron  pan  upon  which 
the  sulphur  is  burned.  Tender  this  pan  is  a  firebox  with  ashpit  and  nec- 
essary drafts.  The  firebox  is  designed  to  lioM  a  light  fire  of  wood  or 
shavings  and  is  intended  to  heat  the  sulphur  pan  sufficiently  to  ignite 
the  sulphur  when  thrown  upon  it  at  the  beginning  of  the  operation.  This 
part  of  the  apparatus  is  unnecessary,  as  the  sulphur  may  be  ignited 
more  simply  by  means  of  some  alcohol,  turpentine,  or  kerosene  on  waste, 
or  a  few  live  coals.  When  once  lighted  there  is  no  trouble  in  keeping 
the  sulphur  burning. 

The  air  enters  at  A,  Fig.  178,  through  a  valve  arranged  to  regulate 
the  amount  of  flow.  It  then  passes  over  the  burning  sulphur  in  the 
direction  shown  by  the  course  of  the  arrows  to  the  fan.  Fumes  are 
compelled  to  take  a  devious  course  around  the  baffle  plates  and  angle 
irons,  as  shown  in  the  drawing,  in  order  to  insure  complete  combustion 
and  to  arrest  sparks.  From  B  the  fumes  are  sucked  to  the  fan,  which 
is  actuated  by  a  steam  engine  or  electric  motor,  and  which  forces  the 
gas  through  the  pipes  to  the  place  to  be  disinfected. 

Eunning  the  fan  at  too  high  a  speed  may  cause  overheating  of  the 
pipes  or  the  carrying  over  of  sparks  of  burning  sulphur.  The  proper 
amount  of  air  should  be  carefully  regulated  so  as  to  obtain  complete 
combustion  and  the  maximum  amount  of  sulphur  dioxid  gas. 

The  pipe  conducting  the  fumes  from  the  sulphur  furnace  to  the 
compartment  to  be  disinfected  gives  a  certain  amount  of  trouble.  It  is 
apt  to  become  clogged  with  sulphur  which  sublimes  in  the  cooler  parts. 
Ordinarily  this  pipe  must  be  from  6  to  8  inches  in  diameter  and  may 
be  made  of  smooth  galvanized  iron  and  the  joints  made  tight  with  sev- 
eral layers  of  canvas  saturated  and  coated  with  some  fireproof  paint. 
Eubber  hose  of  this  size  is  very  expensive  and  soon  vulcanizes. 

ISTo  arrangement  is  made  in  this  form  of  apparatus  for  adding  water 
vapor  to  the  sulphur  fumes,  which  is  necessary  to  obtain  germicidal 
action.  As  a  rule  the  holds  of  wooden  vessels,  in  which  sulphur  fumiga- 
tion is  so  much  used,  are  usually  so  damp  that  the  addition  of  more 
moisture  is  not  necessary. 

The  Clayton  furnace  is  a  more  compact  apparatus  than  that  just 
described.  The  sulphur  dioxid  is  passed  through  a  series  of  tubes  sur- 
rounded by  water,  an  arrangement  corresponding  in  all  respects  to  the 
tubular  condenser  of  a  low-pressure  steam  engine.  The  Clayton  furnace 
is  furnished  with  a  Eoot  blower,  and  has  the  advantage  that  a  compara- 
tively large  volume  of  sulphur  dioxid  may  be  pumped  rapidly  through 


1402 


CHEMICAL  AGENTS  OF  DISINFECTION 


pipes  of  small  caliber  without  fear  of  overheating  or  fire.  These  fur- 
naces are  being  installed  upon  ships  for  the  purpose  of  fumigation  at 
port  and  during  the  vo3^age  for  the  destruction  of  rats,  mice,  and  vermin. 
It  is  also  an  efficient  fire  extinguisher. 


,c- 


I         I 


r^ 


'^ 


\J 


\ 


-^^ 


fi' 


/^ 


^N 


I 


/7      6      ^ 


i 


1 


oouBLa    euLPHu;^  ifurnace 

Fig.  178. — Section  through  Double  Sulphue  Fuexace. 


A  portable  sulphur  furnace  is  a  useful  apparatus  in  municipal  work, 
particularly  in  the  fumigation  of  sewers,  warehouses,  stables,  barns, 
and  similar  large,  rough  structures  infested  with  vermin.  This  form 
of  furnace  was  used  in  the  fight  against  rats  in  the  sewers  of  San  Fran- 
cisco in  the  anti-plague  campaign.  For  the  practical  uses  of  sulphur 
in  maritime  quarantine,  see  page  514. 

Hydrocyanic  Acid  Gas. — Hydrocyanic  acid  gas  has  practically  no 
germicidal  action,  but  is  a  very  powerful  insecticide.  It  is  exceedingly 
poisonous  to  mammals,  and  will  kill  rats  and  mice  with  certainty.  On 
account  of  its  poisonous  nature,  it  must  be  used  with  great  care.  It  is 
so  much  easier  to  use  than  sulphur  dioxid  that  it  is  finding  favor  in 
maritime  quarantine  work.  Hydrocyanic  acid  gas  is  useful  in  the 
treatment  of  stables,  granaries,  outhouses,  compartments  of  ships,  sleep- 
ing-cars, day  coaches,  and  similar  isolated  or  uninhabited  places  for  the 
destruction  of  vermin. 

Creel  ^  found  that  powdered  potassium  cyanid  facilitates  the  evolu- 
tion of  the  gas,  which  is  lighter  than  air  and  rises;  it,  therefore,  per- 
meates a  space  more  quickly  than  SOg.  Creel  also  found  that  hydro- 
cyanic acid  gas  does  not  destroy  bacteria.  Creel  and  Faget  ^  found  that 
four    ounces    of    potassium    cyanid    per    1,000    cubic    feet   is    sufiicient 

» Creel,  R.  H.,  Public  Health  Reports,  Vol.  XXX,  No.  49,  Dec.  3,  1915,  p.  3537. 
« Creel,  R.  H.,  and  Faget,  F.  M.,  Public  Health  Reports,  Vol.  XXXI,  No.  23, 
June  9,  1916,  p.  1463. 


GASKOITS  DTSINFErTAXTS— FiniTOATTOy  1403 

to  kill  mosquitoes  in  IT)  minutes;  five  ounces  per  1.000  cubic  feet 
kills  bedbugs  and  roaches  in  1  hour,  lice  in  2  hours;  two  and  one- 
half  ounces  per  1,000  c.  c.  kills  fleas  in  1.")  minutes.  See  pages  273  and 
515. 

Chlorin. — ("hlorin  is  a  germicide  of  consideral)le  but  uncertain  power. 
It  has  little  practical  usefulness  owing  to  its  poisonous  and  destructive 
action.  Both  in  its  free  state  and  its  water}^  solution  it  has  active 
deodorizing  properties.  Moisture  is  necessary  for  the  disinfecting  action 
of  chlorin  gas.  At  best  chlorin,  like  all  ,<yflses,  is  but  a  surface  disin- 
fectant. 

Chlorin  is  an  extremely  irritating  gas,  and  great  care  must  be  ob- 
served in  its  employment,  for  the  inhalation  of  very  weak  proportions 
of  the  gas  produces  serious  irritation,  resulting  in  spasm  of  the  larynx, 
bronchitis,  and  even  in  death.  Chlorin  is  heavier  than  air  (sp.  gr.  2.47) 
and  tends  to  fall.  Therefore  the  vessel  generating  the  gas  should  be 
placed  in  an  elevated  position  in  order  to  obtain  anything  like  effective 
diffusion.  Carpets,  curtains,  and  fabrics  generally  are  injured  by  its 
action,  and  the  element  is  a  very  active  bleaching  agent. 

The  germicidal  action  of  chlorin  depends  upon  its  great  affinity  for 
hydrogen.  So  strong  is  this  affinity  that  it  combines  with  the  hydrogen 
of  water  in  the  presence  of  light,  liberating  the  oxygen  in  its  nascent 
state,  thereby  enabling  the  oxygen  to  exert  its  power  upon  organic  mat- 
ter. The  value  of  chlorin  as  a  deodorant  depends  upon  its  power  of 
decomposing  the  offensive  gases  of  decomposition  such  as  sulphurated 
hydrogen  and  volatile  ammoniacal  compounds. 

The  most  convenient  method  of  generating  chlorin  gas  is  by  decom- 
posing li/o  pounds  of  calcium  hypochlorite  with  6  ounces  of  strong  sul- 
phuric acid.  This  produces  sufficient  gas  for  the  disinfection  of  1,000 
cubic  feet  of  air  space,  or  the  gas  may  be  generated  from: 

Common  salt  8  ounces  (240  grams) 

Manganese  dioxid 2        "        (60       "      ) 

Sulphuric  acid 2        "        (60       "      ) 

Water    2        "        (60       "      ) 

The  following  reaction  takes  place : 

2XaCl+Mn02+3H2S04=2XaHS04+MnS04+2H20+Cl2 

Mix  the  water  and  the  acid  together  and  then  pour  the  mixture  over 
the  salt  and  manganese  dioxid  in  a  glazed  earthenware  basin.  The 
basin  should  rest  on  sand  or  in  water. 

Fisher  and  Proskauer  have  shown  that  in  ordinary  dry  air  5.38  parts 
of  free  chlorin  per  1,000  cubic  feet  of  air  space  appear  to  be  necessary 
to  kill  microorganisms.  If  the  air  is  moist  only  0.3  per  cent,  by  volume 
in  each  1,000  cubic  feet  of  air  is  sufficient,  disinfection  being  completed 
in  5  to  8  hours. 


1404  CHEMICAL  AGENTS  OF  DISINFECTION 

Free  clilorin  is  much  less  useful  than  sulphur  dioxid,  since  it  is  more 
difficult  to  control,  more  dangerous  to  manipulate,  and  more  destructive 
in  its  effects. 

Chlorin  gas  liberated  from  a  compressed  liquid  state  is  used  for  the 
disinfection  of  water.     See  page  1139. 

Oxygen. — The  disinfecting  power  of  oxygen  depends  largely  upon  the 
physical  state  in  which  it  exists.  For  instance,  oxygen  in  the,  air  has 
comparatively  feeble  germicidal  properties  when  compared  with  nascent 
oxygen  or  ozone.  The  germicidal  action  of  oxygen  depends  upon  its 
very  active  property  of  combining  chemically  with  the  albuminous  mat- 
ter of  the  cell  protoplasm.  The  oxidizing  properties  of  this  element 
partly  explain  the  purifying  action  of  fresh  air.  The  germicidal  prop- 
erty of  oxygen  is  greatly  aided  by  the  actinic  rays  in  sunlight.  While 
most  bacteria  require  the  free  oxygen  of  the  air  for  their  growth  and 
multiplication,  there  is  a  large  class  of  organisms  (the  anaerobes)  to 
which  the  oxygen  of  the  air  acts  like  a  poison  or  strong  antiseptic. 

Ozone. — Ozone  is  an  allotropic  form  of  oxygen  containing  three  atoms 
of  that  element  instead  of  two.  In  sufficient  concentration  it  is  a  pow- 
erful germicide  and  has  lately  been  found  of  practical  use  in  the  steriliza- 
tion of  water  on  a  large  scale  for  the  use  of  cities  and  towns.  It  has 
also  been  used  for  the  sterilization  of  bandages  and  other  objects.  There 
is  not  sufficient  ozone  in  the  air  normally  to  exert  any  appreciable  oxidiz- 
ing  or  disinfecting  properties.  It  requires  at  least  13  parts  per  million 
in  the  atmosphere  to  exert  a  definite  effect  upon  bacteria;  even  then  the 
action  is  not  penetrating.  Such  quantities  are  harmful  to  man.  See 
pages  869  and  1129. 

Ozone  may  be  used  to  destroy  odors  of  organic  origin  due  to  sub- 
stances that  may  be  oxidized,  such  as  the  odors  in  dissecting  rooms, 
animal  pens,  and  like  places. 

The  New  York  State  Commission  on  Ventilation  found  that  ozone 
failed  to  remove  body  odors  from  the  recirculated  air  of  a  school-room. 

For  the  use  of  pyrethrum  and  other  fumigants,  see  Insecticides, 
page  266. 


LIQUID  DISINFECTANTS 

These  consist  of  substances  either  in  solution  or  suspension.  An 
enormous  number  of  such  disinfectants  have  been  exploited,  but  to  be 
of  practical  value  they  must  not  only  be  strongly  germicidal,  but  must 
also  meet  the  many  exacting  requirements  of  general  practice.  Such  sub- 
stances are  few  in  number. 

Almost  any  chemical  substance  under  one  condition  or  another  has 
the  power  to  retard  the  development  or  destroy  the  activity  of  microbial 


LTQTTII)   1)1S1.\KK('TANT8  llOo 

life.  We  need  only  inciilion  tlic  well-known  power  of  eommon  salt  or 
of  sugar,  both  of  \\lii(  li  in  snlliricnl  concenlration  prevent  the  processes 
of  fermentation  and  ])iitrerii(lion.  In  weaker  dilutions  these  same  sub- 
stances, on  the  eontrary,  favor  ii,rowth  of  almost  all  the  known  bacteria. 

The  undeserved  reputation  of  many  chemical  substances  depends 
more  upon  tiu>ir  vile  odor  or  judicious  advertising?  tlian  upon  actual 
efficiency.  Only  those  substances  that  have  proved  their  worth  by  scien- 
tific tests  and  shown  themselves  to  be  trustworthy  in  actual  practice 
will  be  discussed.     See  page  1374. 

Methods  of  TTsing  Chemical  Solutions. — There  are  various  ways  of 
applying  chemical  solutions  for  disinfecting  purposes.  No  method  is 
trustworthy  that  does  not  thoroughly  wet  the  object  with  the  solution, 
so  that  there  may  be  direct  contact  between  the  germ  and  the  germicide. 

As  a  rule  this  may  best  be  accomplished  by  immersing  the  infected 
object  in  the  solution.  When  this  is  not  practicable  the  solution  must 
be  applied  to  the  object.  A  favorite  way  of  applying  disinfecting  solu- 
tions to  surfaces,  such  as  walls,  ceilings,  the  holds  of  ships  and  other 
rough  structures,  is  by  means  of  a  hose^  The  pressure  is  supplied  either 
by  elevating  the  tank  containing  the  solution  or  by  means  of  a  pressure 
pump.  As  bichlorid  of  mercury  is  practically  the  only  disinfectant  used 
in  this  way,  the  pump  should  be  made  of  iron  and  have  no  copper,  brass, 
or  steel  parts  exposed  to  the  corroding  action  of  the  bichlorid  of  mercury. 

In  applying  the  disinfecting  solution  to  the  surfaces  of  a  room  or  the 
hold  of  a  ship  the  operator  should  begin  at  one  corner  of  the  ceiling, 
■wetting  that  first,  and  then  go  over  every  portion  of  the  walls  system- 
atically, from  above  downward.     The  floor  comes  last. 

Solutions  thus  applied  remain  but  a  short  time  in  contact  with  the 
surfaces  to  be  disinfected.  It  is  therefore  an  advantage  to  have  the  solu- 
tion hot  and  strong  and  to  have  sufficient  pressure,  in  order  to  obtain  the 
mechanical  cleansing  effect  produced  by  a  vigorous  stream. 

Another  method  of  applying  disinfecting  solutions  to  surfaces  is  by 
means  of  mops,  brooms,  and  the  like. 

The  pulverizer  is  very  popular  in  France  for  the  disinfection  of  walls 
and  other  surfaces  with  liquid  disinfectants.  The  apparatus  for  this  pur- 
pose consists  of  a  metal  cylinder  fitted  with  a  simple  force  pump  which 
compresses  the  air  in  the  reservoir.  The  solution  does  not  come  in  con- 
tact wdth  the  pump.  The  current  of  air  driven  through  one  tube  sucks 
the  solution  through  the  other  and  sprays  it  from  the  nozzle  in  a  nebulous 
cloud,  similar  in  principle  to  the  well-kno^^Ti  hand  atomizers.  It  is  easy 
to  demonstrate,  by  using  a  colored  solution  upon  a  white  wall  or  sheet, 
that  a  liquid  sprayed  in  this  way  does  not  wet  the  entire  surface.  The 
method  is  therefore  an  unscientific  and  unreliable  one  when  used  with 
a  non-volatile  chemical. 

Germicidal  solutions  are  much  more  potent  when  used  hot. 


1406  CHEMICAL  AGENTS  OF  DISINFECTIOK 

Metallic  Salts. — The  metallic  salts  which  are  used  are  mainly  those 
of  silver,  mercury,  bismuth,  zinc  and  copper.  The  germicidal  activity 
of  many  of  these  metallic  salts  when  acting  upon  bacteria  suspended 
in  pure  water  is  extraordinarily  high,  but  this  powerful  action  is  enor- 
mously reduced  in  the  presence  of  organic  matter. 

There  is  good  evidence  pointing  to  the  belief  that  the  metallic  ions 
in  aqueous  solutions,  owing  to  electrolytic  dissociation,  are  the  chief 
disinfecting  agents.'' 

Bichlorid  of  Mercury.® — HgClg,  bichlorid  of  mercury  or  mercuric 
chlorid,  commonly  called  corrosive  sublimate,  is  one  of  our  most  valu- 
able and  potent  germicides.  It  destroys  all  forms  of  microbial  life  in 
relatively  weak  solutions.  It  kills  both  germs  and  their  spores.  It  is 
not  a  deodorant. 

The  disadvantages  of  bichlorid  of  mercury  are  that  it  corrodes  metals, 
forms  insoluble  and  inert  compounds  with  albuminous  matter,  and  is 
very  poisonous.  These  disadvantages  place  distinct  limitations  upon  its 
use. 

Bichlorid  of  mercury  will  dissolve  in  16  parts  of  cold  water  and  3 
parts  of  boiling  water.  As  it  is  not  readily  soluble  in  water,  it  is  con- 
venient to  keep  a  saturated  alcoholic  solution  on  hand  and  use  this  to 
make  the  watery  solution.  A  35  per  cent,  solution  may  readily  be  made 
in  alcohol,  and  by  the  addition  of  hydrochloric  acid  or  ammonium  chlorid 
this  solution  keeps  well  without  precipitation. 

The  solution  of  bichlorid  of  mercury  is  rendered  more  stable  by  the 
presence  of  hydrochloric  acid  or  a  chlorid  such  as  ammonium  chlorid  or 
common  salt.  Twice  the  weight  of  these  substances  should  be  added  to 
the  quantity  of  bichlorid  used.  If  the  solution  is  to  be  pumped  or  other- 
wise come  in  contact  with  metals  it  is  better  to  use  the  salt  than  the  acid, 
because  the  acid  solution  of  bichlorid  is  very  destructive  to  the  metal 
parts  of  the  pump  and  to  the  couplings  and  nozzle  of  the  hose,  particu- 
larly if  made  of  copper  or  brass.  Sea-water  contains  about  4  per  cent, 
of  salt,  and  is  well  suited  for  making  bichlorid  solutions.  It  is  ex- 
tensively used  at  seaport  quarantine  stations  for  this  purpose. 

The  germicidal  action  of  bichlorid  solution  seems  to  depend  upon 
the  reaction  which  takes  place  between  the  mercury  and  the  protein  of 
the  germ.  Geppert  has  shown  that  in  the  reaction  which  takes  place 
between  the  bichlorid  of  mercury  and  the  spores  of  anthrax  the  vitality 
of  the  latter  may  seem  to  be  lost,  but  that  the  bichlorid  may  be  pre- 
cipitated from  its  combination  by  the  action  of  ammonium  sulphid,  thus 
restoring  the  viability  of  the  spore.     The  sulphur  acts  as  an  antidote. 

Bichlorid  of  mercury  is  decomposed  by  lead,  tin,  copper,  and  other 

''Arch.  f.  Exp.  Path,  and  Pharm.,  32,  p.  456,  1893. 

*  The  use  of  bichlorid  of  mercury  as  a  disinfectant  dates  from  Koch's  experi- 
ments in  1881.     Kaisl.  Gestmdg.,  Vol.  I. 


LTQTJTD  DISINFECTANTS  1107 

metals,  and  therefore  should  not  be  made  or  kept  in  metal  receptacles. 
T.ead  pipes  are  rendered  brittle  and  worthless.  Care  must  therefore  be 
exercised  in  using  this  solution  about  water-closets  and  house  plumbing. 

Corrosive  sublimate  is  precipitated  in  alkaline  fluids  containing  albu- 
minous substances.  The  precijutate  consists  of  insoluble  and  inert  com- 
pounds; therefore  corrosive  suhliniate  should  not  be  used  for  the  disin- 
fection of  media  containing  much  organic  matter,  particularly  when 
the  reaction  is  alkaline.  It  is  not  well  suited  to  the  disinfection  of 
sputum  and  feces,  for  it  forms  an  albuminate  which  retards  penetration. 
It  also  unites  chemically  with  sulphids  and  the  caustic  alkalies,  so  that 
it  should  not  be  employed  as  a  disinfectant  when  these  substances  are 
present  in  any  considerable  amount. 

To  diminish  the  danger  from  accidents  in  households  and  hospitals 
bichlorid  solutions  should  be  colored  with  permanganate  of  potash  or 
indigo  or  one  of  the  aniline  dyes. 

Bichlorid  of  mercury  is  usually  used  in  the  proportion  of  1  to  500  or 
1  to  1,000.  A  solution  of  1  to  1,000  is  ample  for  the  destruction  of 
all  the  non-spore-bearing  bacteria,  provided  the  exposure  is  continued 
not  less  than  half  an  hour  and  direct  contact  is  assured.^  To  assure  this 
contact  a  longer  time  should  be  allowed  in  practice.  Many  bacterial 
cells  are  killed  almost  at  once  when  brought  into  direct  contact  with  a 
solution  of  this  strength,  and  the  great  majority  perish  within  15  min- 
utes. The  extra  time  allows  for  penetration  and  provides  a  factor  of 
safety.  Warm  solutions  are  much  more  potent  than  cold.  For  spores  a 
solution  of  1  to  500  is  necessary  and  an  exposure  of  not  less  than  one 
hour. 

For  practical  work  the  solution  may  be  made  as  follows : 


Corrosive    sublimate 1  dram 

Water    1  gallon 

Mix  and  dissolve. 


1  gram 
1  liter 


This  is  approximately  a  1  to  1,000  solution.  One  ounce  of  this 
solution  contains  very  nearly  half  a  grain  of  corrosive  sublimate. 

Silver  Salts. — The  germicidal  action  of  most  silver  salts  closely 
resembles  that  of  the  corresponding  mercuric  compounds.  Silver  chlorid 
is  insoluble  and  hence  ineffective,  but  silver  nitrate  appears  to  resemble 
mercuric  chlorid  fairly  closely.  Silver  cyanids,  colloidal  silver,  and  va- 
rious organic  compounds  which  yield  free  silver  ions  on  solution  in 
water,  all  appear  to  have  inferior  germicidal  properties,  although  some 
of  them  find  useful  application  in  medical  practice. 

'  The  action  of  mercuric  chlorid  upon  spores  has  been  most  carefully  studied 
bv  Kronig  and  Paul  {Zeifschr.  f.  Hyq.,  25,  p.  1,  1897)  ;  by  Madson  and  Nyman 
(Zeitschr.  f.  Eyg.,  57,  p.  388,  1907)  ;'and  by  Miss  Chick  (Journ.  of  Hyg.,  8,  p.  92, 
1908). 


1408  CHEMICAL  AGEXTS  OF  DISINFECTION 

For  the  prevention  of  ophthalmia  neonatorum,  silver  nitrate  (1  per 
cent.)  is  used  in  Crede's  method;  also  argyrol  (25  per  cent.),  which  is 
a  colloidal  silver;  or  protargol  (3  per  cent,),  which  is  a  silver  protein. 

Zinc  Salts. — Zinc  salts  have  long  been  known  to  have  antiseptic 
properties,  and  the  chlorid  especially  has  been  used  by  Lister  and  others. 
Its  germicidal  action  is  far  inferior  to  that  of  most  mercury  and  silver 
salts.  Chlorid  of  zinc  (ZnCL)  was  at  one  time  highly  valued  as  a  dis- 
infectant and  is  still  extensively  used  despite  the  fact  that  it  stands 
rather  low  in  the  list  of  germicidal  agents.  It  has  even  weaker  power 
as  a  disinfectant  than  ferrous  sulphate.  Five  per  cent,  solutions  are 
effective  against  anthrax  spores,  but  a  2  per  cent,  solution  is  effective 
against  most  vegetative  forms  in  a  reasonably  short  time  when  acting 
in  an  aqueous  medium.  This  activity  is,  however,  much  influenced  by 
the  medium  in  which  it  acts,  since  it  is  very  rapidly  precipitated  by 
proteins,  phosphates,  etc.,  and  therefore  cannot  be  recommended  as  trust- 
worthy.    It  has  some  power  as  a  deodorant. 

Ferrous  Sulphate. — Ferrous  sulphate  has  long  been  valued  as  a  disin- 
fectant on  account  of  its  property  as  a  deodorant,  and  has  been  used  ex- 
tensively, being  a  comparatively  cheap  substance.  Its  germicidal  power 
has  been  shown  by  laboratory  tests  to  be  rather  feeble,  so  that  it  cannot 
be  depended  upon  as  a  trustworthy  disinfectant. 

Ferrous  sulphate  (FeS04),  commonly  called  green  vitriol,  iron  vit- 
riol, or  copperas,  consists  of  large  bluish-green  crystals  which  slowly 
effervesce  and  oxidize  in  the  air.  It  is  soluble  in  about  twice  its  weight 
of  cold  water,  forming  a  greenish  solution.  It  is  a  much  less  powerful 
germicide  than  the  sulphate  of  copper,  and  is  limited  in  use  to  the  de- 
struction of  odors,  and  even  for  this  purpose  is  not  always  successful. 
It  is  still  used  with  lime  for  the  clarification  of  turbid  waters. 

Sulphate  of  Copper. — Sulphate  of  copper  (CuSO^)  is  about  half  as 
strong  as  bichlorid  of  mercury.  It  has  a  peculiar  selective  action  in  that 
it  has  a  remarkable  affinity  for  many  species  of  algae  which  are  killed 
in  the  proportion  of  1  to  1,000,000.  Algae  are  the  most  common  cause 
of  unpleasant  odors  and  tastes  in  drinking  water,  and  sulphate  of  cop- 
per may  therefore  be  used  to  check  or  destroy  their  growth.  See  page 
1143.  In  these  great  dilutions  sulphate  of  copper  will  not  kill  the 
typhoid  bacillus,  so  that  it  is  not  practical  to  use  it  as  a  disinfectant 
in  water. 

COAL-TAR  AND  ITS  PRODUCTS 

Coal-tar  Creosote. — Creosote  is  a  highly  complex  refractile  liquid 
obtained  from  the  destructive  distillation  of  wood  or  coal.  Wood-tar 
creosote  for  medicinal  use  is  obtained  from  beechwood;  it  is  a  complex 
mixture  of  phenoloid  bodies,  the  proportions  of  which  differ  according  to 


COAL-TAT?  AXD  ITS  PKODUCTS  1409 

the  motles  of  distiriatioii  and  j)urification.  It  contains  phenols,  cresols, 
and  hii^lior  honiolo^jues.  C'ual-tar  creo-sote,  sometimes  called  creosote  oil, 
contains  that  portion  of  the  distillate  from  coal-tar  intermediate  between 
crude  naplitha  on  the  one  hand  and  pitch  on  the  other.  Coal-tar  creosote 
contains  j)henols,  cresols,  and  higher  phenoloid  bodies,  also  naphthalene 
and  other  solid  hydrocarbons,  as  well  as  pyridin  and  other  bodies  of  basic 
character.  Creosotes  vary  in  composition,  and  owe  their  germicidal 
properties  to  the  ])hcn()l  and  cresols  which  they  contain.  They  are  sel- 
dom used  as  such,  but  form  bases  of  many  commercial  disinfectants  after 
purification  or  tlie  addition  of  alkalies  or  soaps.  It  is  the  creosote  from 
ooal-tar,  and  not  wood-tar,  that  is  used  as  a  germicide  in  public  health 
work. 

Hale  ^°  has  shown  that  the  coal-tar  disinfectants  of  the  phenoloid 
group  are  considerably  less  toxic  than  either  phenol  or  the  cresols,  but 
they  are  not  harmless,  nonpoisonous  substances  as  sometimes  indicated 
by  the  commercial  labels.  On  an  average  the  disinfectants  of  the  pheno- 
loid group  have  a  toxicity  equal  to  about  15  or  20  per  cent,  of  that  of 
phenol. 

There  appears  to  be  an  intimate  relation  between  the  germicidal 
powers  of  phenol  and  its  derivatives  and  their  protein  precipitating  ca- 
pacity. Many  of  the  various  halogen  derivatives  of  phenol  are  highly 
germicidal  against  bacteria  suspended  in  water,  but  are  not  particularly 
active  in  the  presence  of  blood  serum  or  other  protein  matter. 

Carbolic  Acid. — Carbolic  acid  is  a  very  useful  disinfecting  substance 
with  a  wide  range  of  application.  It  should  not  be  depended  upon  to  kill 
spores.  As  it  does  not  coagulate  albuminous  matter  as  actively  as 
corrosive  sublimate  it  may  be  used  for  the  disinfection  of  soiled  clothing 
and  bedding,  as  well  as  for  excreta  and  sputum. 

Carbolic  acid  is  a  popular  term  for  an  ill-defined  mixture  consisting 
largely  of  phenol  and  phenolic  bodies.  Crude  carbolic  acid  was  discov- 
ered by  Eunge  (1834)  in  coal-tar.  It  is  a  nearly  colorless,  or  reddish  to 
reddish-brown  liquid,  turning  darker  on  exposure  to  air  and  light.  It 
has  a  strong  creosote-like  odor,  with  benumbing,  blanching,  and  caustic 
effects  upon  the  skin  and  mucous  membrane.  Crude  carbolic  acid  is  a 
mixture  of  phenols  and  cresols,  with  coloring  matter  and  impurities. 
Carbolic  acid  is  often  used  as  a  sjTionjTii  for  phenol ;  in  fact,  the  British 
Pharmacopeia  recognizes  the  name  "Aciduni  carbolicum,"  but  uses 
"phenoF  as  the  English  name  for  this  substance.  In  America  the  term 
"carbolic  acid^'  should  be  restricted  to  the  crude  mixture  of  phenols  and 
cresols;  whereas  phenol  is  a  definite  chemical  substance  CsHjOH.  See 
Phenol. 

Crude  carbolic  acid  is  soluble  in  15  parts  of  water  at  15°  C,  making 
about  a  6  per  cent,  solution.     The  undissolved  portion  should  not  ex- 

^"Hijg.  Lab.  Bull.  No.  88.— U.  S.  P.  H.  S.,  1913. 


1410  CHEMICAL  AGEXTS  OF  DISINFECTION 

eeed  10  per  cent,  of  the  volume  of  the  carbolic  acid.  '  Carbolic  acid  is  a 
very  useful  disinfecting  substance  with  a  wide  range  of  applicability. 
The  cresols  contained  in  carbolic  acid  have  a  higher  germicidal  value 
than  pure  phenol  itself.  The  commercial  carbolic  acid  also  contains 
hydrocarbons,  and  other  impurities  of  tar  oil  which  are  totally  lacking 
in  bactericidal  properties. 

Crude  carbolic  acid  dissolves  in  water  with  some  difficulty  and  should 
therefore  be  thoroughly  mixed.  It  is  used  in  solutions  of  2.5  to  5  per 
cent.,  in  which  strength  it  may  be  used  for  the  destruction  of  non-spore- 
bearing  bacteria.  A  5  per  cent,  solution  is  not  dependable  against  spores. 
Warm  or  hot  solutions  are  much  more  effective  than  cold.  It  should  be 
remembered  that  crude  carbolic  acid  (coefficient  2.75)  has  a  higher 
germicidal  potency  than  pure  phenol  (coefficient  1.0).  Crude  carbolic 
acid  is  commonly  used  for  rough  disinfecting  purposes,  such  as  floors, 
stables,  barns,  outhouses,  animal  pens,  etc. 

Phenol. — Phenol,  CgH. OH,  has  the  chemical  structure  of  an  alcohol, 
and  is  the  chief  constituent  of  carbolic  acid.  Pure  phenol  crystallizes 
in  long  colorless  needles;  commercial  phenol  forms  a  crystalline  mass 
which  turns  reddish  in  time,  and  in  contact  with  moist  air  deliquesces 
to  a  brown  liquid.  It  has  a  penetrating  odor  and  strong  burning  taste, 
and  is  a  corrosive  poison.  It  is  soluble  in  10.6  parts  of  water  at  25°  C, 
very  soluble  in  ether,  alcohol,  chloroform,  benzin,  carbon  disulphid, 
glycerin,  fixed  and  volatile  oils. 

Phenol  when  dissolved  in  alcohol  or  ether  loses  in  germicidal  value; 
the  addition  of  0,5  per  cent,  of  hydrochloric  acid  aids  its  activity, 

i\IcClintock  and  Ferry  ^^  have  shown  that  the  large  majority  of  the 
coal-tar  disinfectants  (carbolic  acid,  cresols,  and  the  like)  do  not  destroy 
the  virulence  of  vaccine  virus  in  one-half  per  cent,  solutions  at  five  hours' 
exposure,  while  with  this  strength  and  length  of  time  these  disinfectants 
would  destroy  practically  all  non-spore-bearing  bacteria.  The  inference, 
therefore,  is  allowable  that  this  class  of  disinfectants  is  not  safe  to  use 
for  such  diseases  as  smallpox  or  any  other,  the  cause  of  which  is  not 
known. 

The  fact  that  carbolic  acid  and  phenol  do  not  actively  coagulate 
albuminous  matter  renders  them  suitable  to  the  disinfection  of  excreta 
and  organic  matters  generally.  They  are  not  destructive  to  fabrics,  colors, 
metals,  or  wood  in  the  strengths  used,  and  therefore  may  be  employed 
for  the  disinfection  of  a  great  variety  of  objects.  Crude  carbolic  acid, 
although  it  has  a  stronger  germicidal  power  than  pure  phenol,  has  the 
disadvantage  of  having  a  more  pungent  and  penetrating  odor  and  leaves 
a  deposit  of  coal-tar  oils  and  other  impurities. 

"McClintock.  Chas.  T.,  and  Ferry,  X.  S.:  "The  Resistance  of  Smallpox 
Vaccine  to  the  Coal  Tar  Disinfectants,"  Jour,  of  the  Am.  Pub.  Health  Assn., 
Vol.  I,  Xo.  6,  June,  1911,  pp.  418-420. 


COAL-TAR  AND  ITS  PHODUCTS  1411 

There  has  been  much  (lisparafjoinent  of  phenol  because  laboratory 
tests  have  clearly  demonstrated  thai  it  cannot  always  be  depended  upon 
to  kill  spores.*^  This  limits  hut  docs  not  destroy  its  usefulness,  espe- 
cially as  the  trreat  majority  of  the  cpidi'mic  diseases  of  man  are  due  to 
non-spore-bearing  bacteria. 

Spores  are  killed  with  certainty  t)y  lioiling  for  thirty  minutes  in 
three  to  five  per  cent.  ])henol  or  some  similar  disinfectant. 

The  time  of  exposure  to  a  three  or  five  per  cent,  solution  should  be 
not  less  than  one-half  hour.  Fabrics  are  usually  immersed  for  one 
hour. 

The  introduction  of  a  halogen  atom  into  the  benzol  ring  greatly  in- 
creases the  germicidal  power  of  the  phenols,  cresols  and  naphthols,  while 
at  the  same  time  the  toxicity  of  these  substances  is  diminished.  Thus 
Bechhold  and  Ehrlich  ^^  have  shown  that  tri-brom-/?-naphthol  and  tri- 
ehlor-y8-naphthol  are  very  powerful  germicides,  but  practically  odorless, 
and  not  very  poisonous. 

The  Cresols. — By  far  the  majority  of  the  disinfectants  sold  to  the 
public  are  mixtures  of  varying  quantities  of  phenolic  bodies,  especially 
the  cresols,  with  inert  tar  oils  and  an  emulsifying  agent  such  as  soap 
or  tar,  and  sometimes  rosin,  gelatin,  or  dextrin.  These  substances  all 
possess  a  smell  distinctive  of  carbolic  acid  and  are  effective  germicides. 
The  cresols,  CeH4(CH3)0H,  have  the  advantage  over  carbolic  acid  or 
pure  phenol  in  that  they  readily  form  beautiful  emulsions,  have  a  higher 
germicidal  value,  and  are  less  poisonous.  It  has  already  been  pointed 
out  that  while  emulsions  may  be  more  potent  germicides  than  solutions, 
on  the  other  hand  they  lack  the  power  of  penetration. 

Cresol  is  prepared  from  coal-tar  by  collecting  the  distillates  coming 
over  between  140°  C.  and  220°  C,  and  then  purifying  these  distillates 
by  treatment  with  solution  of  sodium  hydroxid  and  hydrochloric  acid. 
Cresol  is  a  mixture  of  the  three  isomeric  cresols  obtained  from  coal- 
tar  and  freed  from  phenol,  hydrocarbons,  and  water.  It  is  also  known 
as  cresylic  acid. 

Cresol  ^*  consists  of  a  mixture  of  ortho-,  meta-.  and  para-cresols.  Meta- 
cresol  is  a  liquid;  the  other  two  are  solid  crystalline  bodies  having  a 
low  melting  point.  These  cresols  are  found  in  commercial  carbolic  acid. 
The  cresol  group  forms  the  next  higher  homologue  to  phenol,  one  atom 
of  hydrogen  being  replaced  in  the  latter  by  the  methyl  radical,  CH3.  The 
cresols  are  very  insoluble  in  water.  Their  solution  may  be  facilitated 
by  the  use  of  alcohol  or  glycerin.     Cresol  is  a  clear  or  pink-colored 

"  Anthrax  spores  are  remarkably  resistant  to  phenol  solutions,  and  may  be 
viable  after  four  davs'  immersion  in  a  five  per  cent,  solution. 

"Bechhold,  H. :"  Ztschr.  f.  Hyg.  u.  Infektionskrankh.,  1909,  Bd.  64,  p.  113. 
Bechhold,  H.  and  Ehrlich,  P.:  Hoppe-Sevler's  Ztschr.  f.  physiol.  Chetn..  1906, 
Bd.  XLVII,  Hefte  2  und  3,  p.  173.  "^ 

"  Trikresol  is  a  trade  name.  It  is  the  same  substance  as  "Cresol"  of  the 
U.  S.  Pharmacopeia. 


1413  CHEMICAL  AGENTS  OF  DISINFECTIOK 

syrupy  liquid.  It  is  soluble  to  the  extent  of  about  2%  per  cent,  in  water. 
It  is  somewhat  less  poisonous  than  carbolic  acid;  its  uses  are  the  same. 
It  is  an  effective  germicide  in  a  1  per  cent,  solution,  which  is  as  active 
as  3  per  cent,  phenol. 

Liquor  Cresolis  Compositus. — Liquor  cresolis  conipositus  of  the 
U.  S.  Pharmacopeia  is  a  substitution  compound  for  lysol  and  consists  of 
cresol,  500  gm. ;  linseed  oil,  350  gm. ;  potassium  hydroxid,  80  gm. ;  and 
water  sufficient  to  make  1,000  gm.  This  official  mixture  makes  a  clear 
solution  in  water.  The  solution  is  intended  as  a  substitute  for  the  many 
commercial  preparations  of  cresol  on  the  market.  It  has  practically  the 
same  uses  as  lysol. 

Lysol. — Lysol  is  a  brown,  oily-looking,  clear  liquid  with  a  creosote- 
like odor.  It  is  made  by  dissolving  a  fraction  of  tar  oil  which  boils  between 
190°  and  200°  C.  in  fat,  and  subsequently  saponifying  by  the  addition 
of  alkali  in  the  presence  of  alcohol.  It  contains  50  per  cent,  cresols,  espe- 
cially meta-  and  para-cresols,  and  50  per  cent,  of  a  strong  concentrated 
potassium  soap  made  with  linseed  oil.  The  soap  contains  68  per  cent,  of 
fatty  acids.  Lysol  is  miscible  with  water,  forming  a  clean  saponaceous, 
frothy  liquid.  It  is  more  powerful  as  a  germicide  than  phenol,  and  is 
usually  used  in  1  per  cent,  solution.  It  has  a  carbolic  coefficient  of  2.12 
without  organic  matter  and  1.87  with  organic  matter. 

Pyxol  is  a  preparation  of  cresol  and  soft  soap  analogous  to  lysol. 

Creolin. — Creolin  is  a  preparation  similar  to  lysol.  It  is  a  propri- 
etary preparation  patented  by  Pearson  and  consists  of  an  emulsion  of 
cresols  and  certain  other  products  contained  in  tar  oil,  with  rosin  soap. 
Many  other  similar  preparations  are  on  the  market,  such  as  cresolin, 
cyllin,  disinfectol,  sanatol,  izal,  creosapol,  sylphonathol,  etc.  The  tar 
oil  is  brought  into  solution  either  with  rosin  soap  or  by  means  of  con- 
centrated sulphuric  acid.  Creolin  forms  a  milky  emulsion  when  mixed 
with  water.  It  is  used  in  1  or  2  per  cent,  solution.  The  phenol 
coefficient  is  3.25  without  organic  matter  and  2.52  with  organic 
matter. 

Aseptol. — Aseptol  is  a  33  1-3  per  cent,  watery  solution  of  orthophenol- 
sulphonic  acid,  C6H4(S03H)0II.  It  is  made  by  mixing  equal  parts  of 
phenol  and  concentrated  sulphuric  acid  in  the  cold;  if  warmed,  para- 
sulphonic  acid  is  formed,  which  is  a  much  feebler  germicide  than  ortho- 
sulphonic  acid.  The  acidity  of  the  orthophenolsulphonic  acid  is  neutral- 
ized with  barium  carbonate. 

Aseptol  is  a  colorless  liquid  which  gradually  turns  yellowish  when 
exposed  to  the  light,  with  a  weak  odor  of  phenol,  and  a  feeble  acid  reac- 
tion. It  is  miscible,  in  all  proportions,  with  water,  alcohol  and  glycerin. 
Orthophenolsulphonic  acid  gradually  changes  to  paraphenolsulphuric 
acid  in  watery  solution.  Aseptol  is  much  used  in  Germany  for  the  dis- 
infection of  barns,  outhouses,  stables,  and  woodwork,  soil,  and  the  purifi- 


rOAL-TAR  AND  ITS  PROmiOTS  1 113 

cation  of  rough  substances  generally.  It  is  usually  used  in  5  per  cent, 
solution.     In  this  strength  i(  will  kill  anthrax  spores  in  24  hours, 

Asaprol. — Asa])r()l  is  the  (allium  salt  of  /3-naphtliol  sulphoiiic  acid. 
It  is  nia(l<'  by  warming  10  ])arts  of  ^-naphthol  with  8  parts  of  con- 
centrated sulphuric  acid  in  a  watcrhath  until  a  clear  solution  is  obtained. 
It  is  then  diluted  with  water,  neutralized  wdth  calcium  carbonate,  filtered, 
and  the  filtrate  dried  to  a  reddish  powder.  This  powder  is  soluble  in  IV2 
parts  of  water  and  3  parts  of  alcohol.  It  turns  blue  upon  the  addition 
of  ferric  chlorid. 

SanatoL — Sanatol  is  a  dark  fluid,  readily  niisciblc  with  water^  form- 
ing a  slight  turbidity.  It  is  made  from  20  parts  of  tar  oil,  containing 
phenols,  and  10  parts  of  90  per  cent,  sulphuric  acid,  and  diluted  with 
water  sufficient  to  malce  100  parts. 

Solveol  and  Solutol. — Solveol  is  a  solution  of  sodium  cresolate  in 
excess  of  cresol.  Solutol  is  a  solution  of  cresol  in  excess  of  sodium 
cresolate. 

There  are  a  vast  number  of  other  commercial  disinfectants  of  similar 
nature  consisting  of  coal-tar  creosotes  in  combination  with  alkalies,  soaps, 
resins,  etc.,  such  as  chloronaphtholeum,  sylphonathol,  bacillol,  saprol, 
paracresol,  and  other  trade  names. 

Naphthols. — N'aphthols  are  found  in  coal  tar  though  in  small  amount. 
They  have  a  high  germicidal  value  about  the  equal  of  phenols.  Naph- 
thol,  CioH-OH,  is  a  hydroxyl  derivative  of  naphthalene ;  a  and  ^  modi- 
fications are  known.  The  latter  is  of  especial  interest  as  a  germicide. 
Naphthol  itself  is  insoluble  in  water,  but  may  be  rendered  soluble  as  a 
sodium  salt,  or  may  be  emulsified  with  soaps  or  resin.  Naphthol  is  used 
more  as  a  medicinal  germicide  than  in  public  health  work.  Tri-chlor- 
y8-naphthol  is  much  more  germicidal,  but  less  toxic  than  phenol.^^ 

Ambrine. — x4.mbrine  is  a  mixture  used  in  the  treatment  of  burns. 
It  is  a  proprietary  preparation,  and  similar  to  a  product  made  accord- 
ing to  the  following  formula:  yS-naphthol,  0.25  per  cent.;  eucalyptus  oil, 
3  per  cent.;  olive  oil,  5  per  cent.;  hard  paraffin,  25  per  cent.;  and  soft 
paraffin,  67.75  per  cent. 

Naphthalene. — Naphthalene,  C^oHg,  is  a  hydrocarbon  obtained  from 
coal  tar  and  purified -by  crystallization.  It  is  a  white,  shining  crystal- 
line substance,  having  a  strong  characteristic  odor  resembling  coal  tar, 
and  a  burning  aromatic  taste.  It  slowly  volatilizes  on  exposure  to  air. 
Naphthalene  is  insoluble  in  water,  but  soluble  ip,  alcohol.  It  burns  with 
a  smoky  flame. 

Naphthalene  has  antiseptic  properties  but  is  much  less  active  than 
either  the  cresols  or  the  phenols.  It  is  poisonous  to  most  fungi  and  prob- 
ably to  most  insects.    Under  the  name  "^tar  camphor"  it  has  largely  sup- 

"  See  "Phenol  und  seine  Derivate  als  Desinfektionsraittel,"  by  Kurt  Lauben- 
heimer.     Urban  and  Schwarzenberg,  Berlin,  1909, 


1414  CHEMICAL  AGENTS  OF  DISINEECTION" 

planted  true  camphor  as  a  means  of  preventing  tlie  deposition  by  moths 
of  eggs  in  woolen  clothing. 


FORMALIN 

Formalin. — Formaldehyd  in  solution  is  known  as  formalin.  This  is 
a  very  valuable  disinfectant  with  a  wide  range  of  usefulness  in  general 
practice.  It  is  superior  to  bichlorid  of  mercury  for  many  purposes, 
especially  as  its  action  is  not  seriously  retarded  by.  the  presence  of  albu- 
minous matter.  Formalin  is  not  injurious  to  most  articles,  and  it  is 
not  very  poisonous.    It  is  a  true  deodorant. 

Formalin  consists  of  a  40  per  cent,  solution  of  the  gas  formaldehyd 
(HCHO)  dissolved  in  water.  The  liquid  is  a  clear  solution,  giving  oS 
an  appreciable  odor  of  the  gas.  It  is  exceedingly  irritating,  but  not  espe- 
cially toxic.  Formalin  solutions  are  rather  unstable.  There  is  a  con- 
stant loss  by  evaporation  if  the  liquid  is  not  kept  well  corked,  and  in 
cold  weather  the  formaldehyd  polymerizes  and  precipitates  in  one  of 
its  polymeric  forms — trioxymethylene.  For  the  description  and  discus- 
sion of  formaldehyd  see  page  1391. 

Hot  formalin  attacks  iron  and  steel,  but  in  the  cold  has  no  appreciable 
effect.  It  does  not  attack  copper,  brass,  nickel,  zinc,  and  other  metal  sub- 
stances. It  causes  no  diminution  in  strength  of  textile  fabrics  and  has 
no  bleaching  or  other  deleterious  effects  upon  colors.  Formalin  renders 
leather,  furs,  and  skins  brittle  as  a  result  of  the  union  that  takes  place 
between  the  formaldehyd  and  the  organic  matter  of  these  articles,  and 
they  should  therefore  be  disinfected  by  another  process. 

A  10  per  cent,  solution  of  formalin  in  water  is  about  the  equivalent 
of  a  1  to  500  solution  of  bichlorid  of  mercury,  or  superior  to  a  5  per 
cent,  solution  of  carbolic  acid.  It  must  be  borne  in  mind  that  in  speak- 
ing of  a  solution  of  formalin  a  solution  is  meant  of  the  liquid  containing 
40  per  cent,  formaldehyd;  that  is,  a  1  per  cent,  solution  of  formalin 
would  contain  that  liquid  in  proportion  to  1  to  100,  but  would  contain 
the  substance  formaldehyd  in  the  proportion  of  1  to  250. 

Fecal  masses  are  deodorized  almost  instantly  by  a  small  quantity  of 
formalin,  and  are  disinfected  in  a  short  time  when  intimately  and  thor- 
oughly mixed  with  a  10  per  cent,  solution.  It  is  advisable  to  continue  the 
contact  one  hour  to  insure  complete  action. 

There  is  some  discrepancy  as  to  the  percentage  of  formalin  solution 
necessary  to  accomplish  trustworthy  disinfection  in  general  practice. 
Taking  into  account  the  deterioration  of  the  solution  with  age  and  allow- 
ing an  excess  as  an  element  of  safety,  a  10  per  cent,  solution  is  recom- 
mended. It  may  be  used  to  disinfect  urine,  excreta,  sputum,  and  other 
similar  substances. 


OXIDIZING  AGENTS  1415 


OXIDIZING  AGENTS 

Potassium  Permang^anate. —  rotassium  i)('riMiiii<^anate  is  a  germicide 
of  undoubted  value,  but  of  very  limited  application  in  general  practice 
on  account  of  the  readiness  with  which  it  is  reduced  and  rendered  inert 
by  organic  matter.  Despite  its  limitations  it  ranks  high  on  the  list  of 
germicides  for  certain  definite  purposes,  more  particularly  in  surgical 
practice.  It  has  been  much  used  in  India  and  other  places  for  the  puri- 
fication of  water. 

All  the  permanganates  are  strong  oxidizing  agents,  but  as  soon  as 
they  are  reduced  to  manganese  salts  their  disinfecting  action  ceases,  so 
that  their  maximum  germicidal  effects  are  transitory. 

Potassium  permanganate  (K^InO^)  is  a  dark  purple,  crystalline 
substance  with  a  sweet,  astringent  taste.  A  few  crystals  impart  to  a 
large  quantity  of  water  a  rich  purple  tint  which  is  destroyed  by  organic 
matter  and  deoxidizing  agents.  It  is  soluble  in  16  parts  of  cold  and  2 
parts  of  boiling  water.  The  stain  produced  by  potassium  permanganate 
may  be  removed  by  a  solution  of  oxalic  acid,  muriatic  acid,  or  simple 
lemon  juice. 

Potassium  permanganate  readily  gives  up  its  available  oxygen,  and 
it  is  the  free  nascent  oxygen  that  is  the  true  disinfecting  agent.  Stern- 
berg found  a  solution  of  1  to  833  sufficient  to  kill  pus  cocci  in  two  hours. 
Koch  found  that  a  5  per  cent,  solution  killed  spores  in  one  day.  Loef- 
fler  found  that  the  bacillus  of  glanders  is  destroyed  in  two  minutes  by  a 
1  per  cent,  solution. 

Water  containing  organic  matter  may  be  purified  to  a  certain  extent 
and  rendered  palatable  by  adding,  drop  by  drop,  a  solution  of  perman- 
ganate until  the  pink  color  of  the  water  ceases  to  be  destroyed  after 
the  lapse  of  24  hours.  The  clear  liquid  may  then  be  decanted  and  used. 
Permanganate  used  in  this  way  does  not  reach  sufficient  concentration 
to  be  a  trustworthy  germicide. 

Hydrogfen  Peroxid  and  Other  Peroxids. — Hydrogen  peroxid  is  a 
rather  feeble  germicide,  but  has  certain  other  qualities  which  render 
it  useful  in  surgical  practice.  Blood,  pus  and  muscle  juice  contain  an 
enzyme  "catalase"  which  rapidly  brings  about  the  decomposition  of 
hydrogen  peroxid  with  the  liberation  of  gaseous  oxygen.  This  action 
rapidly  decomposes  all  the  peroxid  and  its  disinfecting  action  comes  to 
a  speedy  end.  The  mechanical  effect  of  the  disengaged  gas  is  often  a 
valuable  property,  and  is  made  use  of  in  loosening  sticky  secretions, 
washing  away  pus,  or  loosening  adherent  dressings. 

Other  very  active  oxidizing  agents  used  as  germicidal  agents  are 
ozone  (page  869)  and  hypochlorites  (page  1132). 


1416  CHEMICAL  AGENTS  OF  DISINFECTION 


LIME 

Lime  is  one  of  the  best  and  cheapest  disinfecting  substances  we  have. 
It  is  usually  used  either  as  lime  or  chlorinated  lime. 

Lime,  or  quicklime,  is  a  very  caustic  substance  used  for  the  destruc- 
tion of  organic  matter  as  well  as  germ  life.  On  account  of  its  effi- 
ciency and  cheapness  it  is  a  valuable  addition  to  the  list  of  practical 
disinfectants.  Lime  or  calcium  oxid  (CaO)  is  one  of  the  alkaline 
earths.  It  is  not  so  caustic  as  the  alkalies,  having  less  affinity  for  water. 
It  is  obtained  by  calcining  native  calcium  carbonate  (CaCOg),  such  as 
chalk,  limestone,  or  marble,  by  which  the  carbon  dioxid  is  driven  off  and 
the  calcium  oxid  remains  behind.  Lime  as  such  requires  the  addition 
of  water  for  germicidal  purposes. 

Slaked  Lime. — Slaked  lime  or  calcium  hydroxid,  Ca(0ir)2,  is  pre- 
pared by  adding  one  pint  of  water  to  two  pounds  of  lime.  The  lime 
absorbs  about  half  its  weight  of  water.  The  mass  becomes  heated  and 
the  air  escapes  from  the  pores  of  the  lime  with  a  hissing  noise.  The  result 
is  calcium  hydroxid  or  slaked  lime.  LTpon  exposure  to  the  air  the  slaked 
lime  will  absorb  still  more  water  and  also  carbon  dioxid,  converting  it 
into  calcium  carbonate,  which  is  inert  so  far  as  its  disinfecting  power  is 
concerned.     Freshly  slaked  lime  should  therefore  always  be  used. 

Whitewash  is  slaked  lime  mixed  with  water.  It  is  commonly  used 
for  the  disinfection,  sweetening,  and  brightening  of  the  walls  of  cellars, 
rooms,  barracks,  barns,  stables,  poultry-houses,  and  out-buildings  gen- 
erally. Whitewash  is  a  very  satisfactory  method  of  destroying  spore-free 
bacteria  that  may  have  lodged  upon  such  surfaces.  It  improves  illumi- 
nation and  is  an  incentive  to  keep  things  clean.  A  mordant  such  as  glue 
is  usually  added  to  whitewash  to  make  it  adhere ;  also  a  little  bluing. 

MilJc  of  lime  is  slaked  lime  mixed  with  four  to  eight  times  its  volume 
of  water  to  the  consistency  of  a  thick  cream.  It  is  useful  for  the  disin- 
fection of  excreta  and  privy  vaults.  Air-slaked  lime  containing  the  inert 
carbonate  must  not  be  used  in  the  preparation  of  whitewash  or  milk  of 
lime,  freshly  slaked  lime  containing  calcium  hydroxid  being  _  necessary 
to  accomplish  disinfection.  Calcium  hydrate  is  mostly  insoluble  and  set- 
tles to  the  bottom ;  the  milk  of  lime  must  therefore  be  agitated  to  restore 
its  homogeneous  character  before  it  is  used.  Milk  of  lime  is  most  pow- 
erful when  freshly  prepared.  It  soon  changes  to  the  inert  carbonate, 
and  therefore  should  not  be  used  if  more  than  a  few  days  old  unless  care- 
fully protected  from  contact  with  the  air. 

Almost  all  laboratory  experiments,  while  differing  somewhat  in  cer- 
tain unimportant  particulars,  confirm  the  conclusions  of  the  early  in- 
vestigators as  to  the  great  practical  value  of  lime  as  a  germicide.  A  1 
per  cent,  watery  solution  of  the  hydroxid  kills  non-spore-bearing  bac- 


LIME  1417 

teria  within  a  few  hours.  A  3  per  cent,  solution  kills  typhoid  bacilli  in 
one  hour.  A  20  per  cent,  solution  added  to  equal  parts  of  feces  or  other 
filth  and  mixed  with  them  will  disinfect  them  within  one  hour. 

Lime  is  pariicularly  \alual>l('  in  the  disinfection  of  excreta.  The 
lime  in  one  form  or  another  must  be  well  incorj)orated  with  the  mass 
and  enough  must  always  be  added  in  order  to  make  the  reaction  of  the 
mixture  distinctly  alkaline.  Sternberg  recommends  that  freshly  pre- 
pared milk  of  lime  should  contain  about  one  part  by  weight  of  hydrate 
of  lime  to  eight  parts  of  water.  This  should  be  used  freshly  prepared 
and  added  in  quantity  equal  in  amount  to  the  material  to  be  disinfected. 
The  mixture  sliould  be  allowed  to  stand  at  least  two  hours  before  final 
disposal.  Fortunately,  this  valuable  disinfecting  agent  is  very  cheap, 
so  that  it  can  be  used  with  a  liberal  band  in  excess  of  the  amount  which 
scientific  tests  find  necessary.     See  page  14:32. 

Lime  has  been  used  since  very  early  times  in  connection  with  the  dis- 
posal of  the  dead.  The  method  is  an  admirable  one  for  the  burial  and 
disinfection  of  bodies  dead  from  a  communicable  disease.  The  body 
should  be  placed  in  a  tight  coffin  with  twice  its  weight  of  fresh,  unslaked 
lime,  without  the  addition  of  water  or  moisture  in  any  form. ' 

The  Chlorin  Group. — The  chlorin  group  of  disinfectants  includes 
a  number  of  important  substances  such  as  chlorin  itself,  hypochlorous 
acid  and  its  sodium  and  calcium  salts,  and  organic  "chloramins,"  that  is, 
substances  containing  chlorin  attached  to  nitrogen  in  the  form  of  NCI 
groups.  They  are  all  characterized  by  marked  instability,  since  in  disin- 
fection they  react  not  only  wdth  the  cell  constitutents  of  microorganisms, 
but  also  with  most  other  substances  which  are  apt  to  accompany  bacteria. 
In  so  reacting,  the  active  chlorin  of  the  antiseptic  is  eventually  con- 
verted either  into  inert  chlorids  or  into  inert  organic  substances  in 
which  the  chlorin  has  become  united  to  carbon.  Thus,  in  using  the 
chlorin  germicides,  as  with  hydrogen  peroxid,  the  process  of  disinfec- 
tion will  only  go  on  so  long  as  some  of  the  active  substance  remains 
undecomposed.     The  action  is  rapid  and  transitory. 

Bromin  and  lodin. — Bromin  and  iodin  are  very  potent  germicides. 
They  have  about  the  same  value  as  chlorin,  both  in  their  gaseous  state 
and  in  solution.  The  tincture  of  iodin  is  now  much  used  in  surgery  for 
the  disinfection  of  the  skin.  The  use  of  iodin  as  a  skin  disinfectant 
introduced  by  Stretton,^**  in  1909,  has  great  value  for  this  purpose.  A 
2%  per  cent,  solution  is  usually  strong  enough  and  alcohol  is  the  best 
solvent.  Seventy  per  cent,  alcohol  is  preferable  to  stronger  spirit,  and 
it  is  important  to  use  pure  alcohol,  as  otherwise  iodo-acetone  and  other 
products  are  apt  to  be  formed,  which  are  very  irritating. 

Chlorinated  Lime  (Chlorid  of  Lime). — Chlorinated  lime  was 
used  as  a  disinfectant  and  deodorant  long  before  bacteriology  was  a 

^^Brit.  Med.  Journ.,  Aug.  14,  1909;  also  May  22,  1915. 


1418  CHEMICAL  AGENTS  OF  DISINFECTION 

science.  The  early  work  of  Sternberg  demonstrated  that  the  confidence 
placed  in  this  substance  from  an  empiric  standpoint  is  justified  by  scien- 
tific tests.  Chlorinated  lime  under  certain  circumstances,  in  fact,  is 
one  of  the  most  powerful  germicides  we  possess,  and  has  been  used 
particularly  for  the  disinfection  of  water  and  sewage.  See  page 
1209. 

Chlorinated  lime,  popularly  miscalled  chlorid  of  lime,  is  a  soft, 
white,  friable  substance,  and  is  known  also  as  bleaching  powder.  It 
has  a  peculiar  chemical  composition  and  is  somewhat  unstable.  It  is 
made  by  passing  chlorin  gas  through  lime.  Owing  to  its  affinity  for 
moisture,  which  it  slowly  absorbs  from  the  air,  it  soon  becomes  pasty 
and  loses  some  of  its  chlorin;  the  hypochlorites  are  reduced  to  chlorids, 
which  are  inert  as  germicides.  Freshly  prepared  chlorinated  lime 
should  have  a  very  slight  odor  of  free  chlorin.  A  strong  odor  of  this 
gas  indicates  that  deterioration  of  the  substance  is  taking  place.  It 
should  therefore  be  kept  in  air-tight  receptacles. 

Chlorinated  lime  is  made  by  passing  nascent  chlorin  gas  over  very 
slightly  moist  calcium  hydroxid.  Concerning  its  exact  chemical  com- 
position tliere  is  some  disagreement.  It  is  represented  by  the  formula 
CaOClg  or  ClCaOCl  or  Ca(C10)Cl.  The  dry  powder  contains  calcium 
oxy chlorid  (CaOClg),  which  is  at  once  converted  into  calcium  hypo- 
chlorite (Ca(0Cl)2)  and  calcium  chlorid  (CaCL)  in  watery  solution; 
thus :  2CaOCl2  =  Ca (OCl) ^  -f  CaCl^. 

According  to  the  U.  S.  Pharmacopeia  it  should  contain  not  less  than 
35  per  cent,  of  available  chlorin.  The  British  standard  is  33  per  cent, 
and  the  German  2.5  per  cent.  CMorinated  soda  has  almost  the  same 
germicidal  value  as  chlorinated  lime.  Chlorinated  soda  is  sold  in  solu- 
tion, and  is  prepared  by  mixing  a  solution  of  chlorinated  lime  and 
sodium  carbonate. 

Chlorinated  lime  is  only  partially  soluble  in  water  or  in  alcohol. 
A  solution  in  water  of  0.5  to  1  per  cent,  will  kill  most  bacteria  in  from 
one  to  five  minutes.  A  5  per  cent,  solution  usually  destroys  spores  within 
an  hour. 

The  action  of  bleaching  powder  depends  upon  at  least  three  factors : 

(1)  Nascent  oxygen,  which  is  formed  by  the  breaking  down  of 
hypochlorous  acid,  is  a  very  potent  germicide : 

2H0C1  =  2HC1  +  20 
This  is  perhaps  one  of  the  chief  efl'ects,  and  therefore  the  action  of 
bleaching  powder  is  not  so  much  a  process  of  chlorination  as  one  of 
oxidation. 

(2)  Chlorin  gas,  which  is  a  very  powerful  germicide.  Some  of 
it  exists  free  in  the  bleaching  powder  and  some  of  it  is  formed  by  the 
decomposition  of  hypochlorous  acid  and  also  of  hypochlorites  in  acid 
solution :  thus,  2H0C1  =  H2O  -f  CI  +  0. 


LIME  1419 

(3)  Chloramins  contain  the  radical  NCI,  and  are  formed  by  the 
union  of  ohlorin  and  its  compounds  with  aminonia  and  amino-acids. 
Most  chloramins  are  strong  germicides;  some  of  them  have  extraordinary 
activity.     See  page  li;U. 

In  addition,  the  hypochlorites  themselves  arc  probably  directly  pois- 
onous to  bacteria  without  intermediate  chemical  action. 

Chlorinated  lime  not  only  bleaches  but  is  destructive  to  fabrics.  If 
the  solution  is  employed  for  the  disinfection  of  body  linen  and  washable 
clothing  these  articles  must,  after  a  not  too  long  immersion,  be  thor- 
oughly washed  in  plenty  of  fresh  water. 

It  should  be  remembered  that  the  hypochlorites  are  decomposed  and 
practically  rendered  inert  by  organic  matter.  They  should  therefore  be 
used  largely  in  excess.  Thus  a  preparation  containing  10  per  cent,  of 
available  chlorin  has  the  high  carbolic  coefficient  of  21.0,  but  on  mixing 
an  equal  amount  of  this  preparation  with  urine  and  allowing  the  mixture 
to  stand  one  hour  the  coefficient  falls  to  0.8  per  cent.  (Klein  ^'').  Gruber 
points  out  that  the  efficiency  of  chlorinated  lime,  when  used  to  disinfect 
cattle  wagons,  is  greatly  increased  by  first  thoroughly  washing  away  the 
organic  matter. 

Chlorinated  lime  may  be  used  either  as  a  dry  powder  or  in  solution. 
As  a  dry  powder  it  is  very  generally  used  by  strewing  it  into  damp 
corners  of  cellars,  privies,  and  similar  places,  where  it  acts  as  a  deodor- 
ant and  desiccant  and  retards  the  growth  of  mold.  The  dry  substance 
may  also  be  used  to  disinfect  excreta.  For  this  purpose  enough  of  the 
chlorinated  lime  must  be  added  and  well  incorporated  with  the  mass  and 
sufficient  water  added  to  make  a  4  or  5  per  cent,  solution.  Much  more 
chlorinated  lime  is  necessary  to  disinfect  feces  in  a  bed-pan  than  for 
sewage. 

In  the  U.  S.  Army  a  4  per  cent,  strength  of  chlorinated  lime  in  solu- 
tion is  officially  prescribed  for  use  in  the  disinfection  of  the  excreta  of 
the  sick,  it  being  specifically  stated  that  the  chlorinated  lime  so. used 
shall  be  of  good  quality  and  not  have  undergone  decomposition.  A  solu- 
tion known  as  the  "American  standard,"  containing  6  ounces  of  the 
powder  to  the  gallon,  is  largely  used  for  the  disinfection  of  discharges 
and  for  the  scrubbing  of  floors  and  other  surfaces. 

In  recent  years  chlorinated  lime  or  chlorinated  soda  has  come  into 
special  prominence  on  account  of  its  use  for  the  disinfection  of  drinking 
water.  A  surprisingly  minute  amount  will  disinfect  a  large  volume  of 
water.  The  amount  required  depends  upon  the  quantity  of  organic  mat- 
ter contained  in  the  water.  A  clean  water  may  be  rendered  safe  by 
the  addition  of  0.1  of  a  part  of  chlorinated  lime  (estimated  as  available 
chlorin)   to  1,000,000  parts  of  water.     For  waters  containing  organic 

"Public  Health,  Oct.,  1906.  Confirmed  by  Rideal,  Sommerville,  Moorej  and 
others. 


1420  CHEMICAL  AGENTS  OF  DISINFECTION 

matter  as  much  as  1  to  5  parts  per  1,000,000  may  be  required.  See 
page  1132, 

Chlorinated  lime  may  also  be  used  to  advantage  to  disinfect  the 
bath  water  in  cases  of  typhoid  fever,  dysentery,  cholera,  or  other  com- 
municable diseases.  It  may  also  be  used  for  the  disinfection  of  springs, 
wells,  cisterns,  tanks,  and  many  other  purposes.     See  page  1138. 

For  campers  and  travelers  a  convenient  method  for  using  chlorinated 
lime  to  disinfect  drinking  water  is  to  add  1  gram  of  chlorinated  lime 
containing  approximately  30  per  cent,  of  available  chlorin  to  1  liter  .of 
w^ater.  This  should  be  mixed  thoroughly  and  enough  of  the  mixture 
added  to  the  water  in  question  to  make  1  part  of  chlorinated  lime  to 
200,000  parts  of  water,  and  then  allowed  to  stand  at  least  20  minutes 
after  having  been  thoroughly  shaken.  The  water  may  then  be  regarded 
as  safe,  so  far  as  typhoid,  cholera,  and  similar  infections  are  concerned. 
A  solution  may  be  prepared  by  adding  half  a  teaspoonful  of*  chlorinated 
lime  to  a  pint  of  water.  Use  a  teaspoonful  of  this  to  10  gallons;  36 
drops  to  1  gallon;  or  9  drops  to  1  quart.  Let  stand  at  least  15  minutes. 
Halozone  tablets  may  be  used  (if  fresh).     See  page  1131. 

Javelle  water  consists  of  chlorinated  potash,  65  grams;  chlorinated 
lime,  90  grams;  water  sufficient  to  make  1,000  grams.  It  is  used  as  a 
medicinal  wash. 

Laharraques  Solution. — Labarraque's  solution  is  an  aqueous  solu- 
tion of  several  chlorin  compounds,  chiefly  sodium  hypochlorite  (NaClO) 
and  sodium  chlorid  (NaCl),  and  should  contain  at  least  2.6  per  cent,  by 
weight  of  available  chlorin  as  determined  by  titration  with  thiosulphate. 
The  solution  is  clear  and  colorless  when  pure.  If  prepared  with  an  excess 
of  chlorin  it  is  yellowish  in  color.  It  has  a  feeble  odor  of  chlorin  and 
bleaches  indigo,  litmus,  and  vegetable  dyes.  In  practice  this  solution 
diluted  with  water  1  to  4  is  mainly  used  for  the  disinfection  of  the  per- 
son, and  in  surgery,  but  as  it  is  more  expensive  and  somewhat  less  effi- 
cient, than  chlorinated  lime  it  has  no  advantages  over  that  substance. 

DaJcins  Solution. — Dakin's  solution  came  to  notice  during  the 
World  War  in  the  Carrell  method  of  treating  wounds.  It  may  be  looked 
upon  as  an  improved  Labarraque's  solution.  The  active  ingredient  of 
Dakin's  solution  is  sodium  hypochlorite.  It  must  be  freshly  prepared; 
must  have  an  entire  absence  of  caustic  alkali;  the  concentration  must 
be  exactly  between  0.4  and  0.5  per  cent.  Below  0.4  per  cent,  of  hypo- 
chlorite, the  solution  is  not  sufficiently  active,  and  above  0.5  per  cent, 
it.  becomes  irritating. 

Dakin's  solution  is  made  from  chlorinated  lime,  anhydrous  sodium 
carbonate  and  sodium  bicarbonate.  The  method  of  preparation  and 
testing  is  given  by  Dakin  and  Dunham,^^  and  also  by  Carrell.^® 

"  "Handbook  of  Antiseptics,"  Dakin  and  Dunham. 
"J.  A.  M.  A.,  LXVII,  24,  Dec.  9,  1916,  p.  1777. 


LTMPJ  1421 

For  (lull  lorn  III  i/i-'l\  lialnzuiir  ami  other  chlorin  cumpoiiiKls,  see 
paijjo  1 1.'!  i. 

Antiformin. — Antil'onnin  is  the  patented  name  of  a  disinfectant 
wliicii  Avas  introduced  in  1900  by  Victor  Tornell  and  Axel  Sjoo  of 
Stockholm  as  a  cleansing  material  for  fermenting  vats  in  breweries,  but 
it  is  only  since  the  investigations  of  Uidenluith  and  Xylander  -^  in  1908 
that  it  has  come  into  prominence  in  bacteriological  and  sanitary  work. 

Antiformin  consists  of  equal  parts  of  liquor  sodae  chlorinatae  of  the 
British  Pharmaco])eia  and  a  15  per  cent,  solution  of  caustic  soda.  The 
formula  for  the  liquor  sodae  chlorinatae  is  as  follows: 

Sodium  earbonate GOO 

Chlorinated  lime 400 

Distilled  water 4,000 

Dissolve  the  sodium  carbonate  in  1,000  c,  e.  of  the  distilled  water; 
triturate  thoroughly  the  chlorinated  lime  in  the  remainder  of  the  water; 
filter;  mix  the  two  and  filter  again. 

Antiformin  has  a  strong  germicidal  action  in  weak  solutions  (2  to 
5  per  cent.),  killing  ordinary  cocci  and  some  bacilli  rapidly,  five  minutes 
at  most  being  sufficient.  In  this  respect  antiformin  acts  more  rapidly 
and  surely  than  either  of  its  component  parts  used  alone.  It  has,  how- 
ever, very  slight  action  upon  the  tubercle  bacillus,  the  smegma  bacillus, 
and  other  organisms  belonging  to  the  acid-fast  group. 

Antiformin  is  an  almost  colorless  liquid,  with  a  strong  odor  of 
chlorin,  and  is  strongly  alkaline.  It  keeps  fairly  well  without  particular 
precautions  being  taken.  It  has  deep  powers  of  penetration,  owing  to 
its  ability  to  dissolve  and  render  homogeneous  the  various  substances  in 
which  bacteria  are  often  found,  such  as  sputum,  feces,  pus,  urinary  sedi- 
ment, and  even  small  pieces  of  tissue. 

The  germicidal  action  of  antiformin  is  doubtless  due  to  the  energetic 
oxidizing  properties  of  the  chlorinated  lime.  The  fact  that  it  does  not 
kill  the  tubercle  bacillus  and  other  acid-fast  organisms  seems  to  be  due 
to  the  biochemical  nature  of  these  bacilli.  The  fatty  or  waxy  capsule 
which  is  present  and  which  gives  them  their  acid-fast  property  acts  as 
an  impervious  coat,  resisting  the  dissolving  action  of  the  antiformin, 
and  so  protects  the  protoplasm  of  the  bacilli  from  its  germicidal  action. 
The  tubercle  bacillus  may  be  isolated  in  pure  culture  by  exposing-tuber- 
culous  sputum  to  a  20  per  cent,  solution  of  antiformin  for  24  hours 
at  room  temperature  or  4  to  6  hours  at  incubator  temperature.  The 
bacilli  may  then  be  thrown  down  by  centrifugalization,  washed  free  of 
alkali,  and  then  planted  upon  solidified  egg  or  other  suitable  culture 
medium,  or  injected  into  susceptible  animals. 

^Berl.  klin.  Wochenschr.,  LXV,  No.  29,  July  20,  1908. 


1422  CHEMICAL  AGENTS  OF  DISINFECTION 

While  antiformin  is  therefore  a  very  active  germicide  for  the  ordi- 
nary bacteria  it  cannot  be  depended  upon  for  the  acid-fast  group.^^ 

Dyestuffs. — A  large  number  of  dyestuffs  possess  germicidal  proper- 
ties, although  until  recently  they  have  been  employed  for  the  destruc- 
tion of  blood  parasites,  such  as  trypanosomes,  rather  than  bacteria. 
Many  germicidal  dyes  are  selective  or  specific  in  action. 

Malachite  green,  used  in  conjunction  with  mercuric  chlorid,  is  used 
extensively,  especially  in  naval  service.  Certain  other  dyes  chemically 
related  to  malachite  green  (triphenylmethanes)  possess  definite  bacteri- 
cidal action,  as  hexamethyl  violet — also  known  as  crystal  violet — hexethyl 
violet  and  brilliant  green. 

Acrifavine,  trypcufia/oinej,  or  fiavine,  was  first  prepared  by  Benda  ^^ 
at  Ehrlich's  instigation  in  1911,  and  was  found  to  have  marked  germi- 
cidal action  on  trypanosomes.  Acriflavine  has  been  claimed  by  Brown- 
ing and  his  associates  "^  to  be  a  most  powerful  germicide.  It  is  used  in 
surgery  and  has  also  been  employed  in  the  disinfection  of  the  naso- 
pharynx of  carriers  of  the  meningococcus.  Dakin  and  Dunham  -*  regard 
acriflavine  as  distinctly  more  active  under  most  conditions  than  either 
malachite  green  or  brilliant  green,  though  its  rate  of  disinfection  is  de- 
cidedly slow.  One  of  the  most  remarkable  properties  of  acriflavine  is 
that  its  germicidal  action  is  apparently  enhanced  by  admixture  with 
serum,  though  greatly  diminished  by  pus. 

ACIDS 

Acids  in  sufficient  concentration  are  very  effective  germicides.  An 
am,ount  of  acid  which  equals  4  per  cent,  of  normal  hydrochloric  acid  is 
sufficient  to  prevent  the  growth  of  all  kinds  of  bacteria  and  to  kill  many. 

The  germicidal  power  of  an  acid  depends  upon  the  free  hydrogen 
ion  in  solution.  The  disinfecting  power  of  an  acid  is  therefore  propor- 
tional to  the  hydrogen  ion  concentration,  and  this  in  turn  is  propor- 
tional to  the  dissociation  of  the  acid.  Thus,  when  we  speak  of  a  strong 
acid,  we  mean  one  that  is  highly  dissociated,  and,  conversely,  a  weak 
acid  one  which  is  slightly  dissociated.  The  mineral  acids  are  more  cor- 
rosive and  also  more  germicidal  than  the  organic  acids  because  they  have 
higher  hydrogen  ion  concentrations.  A  1  to  500  solution  of  sulphuric 
acid  kills  typhoid  bacilli  within  one  hour.  Hydrochloric  acid  is  about 
one-third  weaker,  and  acetic  acid  weaker  still.  Citric,  tartaric,  malic, 
formic,  and  salicylic  acids  are  about  equal  to  acetic  acid.     Boric  acid 

"  Paterson,  R.  C. :  "A  Report  on  the  Use  of  'Antiformin'  for  the  Detection 
of  Tubercle  Bacilli  in  Sputum,  etc.,"  Jour,  of  Med.  Research,  Vol.  XXII,  No.  2, 
April,  1910,  p.  315. 

^^Berl.  Deutsch.  Chem.  Gesell.  45,  p.  1787,  1912. 

"^Brit.  Med.  Journ.,  Jan.  20,  1917,  p.  73. 

^  "Handbook  of  Antiseptics,"  p.  64. 


ALCOHOL  1423 

is  very  feeble;  it  destroys  the  less  resistant  bacteria  in  2  per  cent,  solu- 
tion and  inhibits  the  others. 


ALCOHOL 

Alcohol  has  both  antiseptic  and  germicidal  properties.  In  solutions 
of  1-1.000  the  growth  of  some  bacteria  is  somewhat  delayed.  Many 
microorganisms  grow  abundantly  in  40  per  cent,  alcohol  and  some  in 
stronger  solutions.  Dry  bacteria  may  be  exposed  to  absolute  alcohol  for 
24  hours  without  losing  their  vitality,  while  60  to  70  per  cent,  alcohol 
has  definite  germicidal  power  to  both  dry  and  moist  microorganisms. 
The  explanation  of  this  curious  phenomenon  seems  to  be  that  alcohol 
fails  to  penetrate  the  microbe  unless  in  the  presence  of  water.  Under 
40  per  cent,  the  germicidal  action  is  very  slow  so  that  the  limits  of  alcohol 
as  a  disinfectant  may  be  placed  between  50  and  70  per  cent.  In  this 
strength  it  is  equivalent  to  about  3  per  cent,  carbolic  acid  provided  there 
is  little  or  no  albuminous  matter  present. 

Dakin  and  Dunham  found  that  most  vegetative  forms  of  bacteria  may 
be  killed  fairly  readily  by  50  per  cent,  alcohol,  but  that  much  higher 
or  lower  strengths  are  less  effective,  while  most  spores  are  unaffected 
by  alcohol  of  any  strength. 

Alcohol  precipitates  protein  which  therefore  seriously  interferes  with 
its  germicidal  property.  Many  germicidal  substances  which  are  potent 
when  dissolved  in  water,  have  comparatively  little  effect  when  dissolved 
in  strong  alcohol. 

Kronig  and  Paul  found  that  phenol  dissolved  in  98  per  cent,  alcohol 
was  devoid  of  bactericidal  action  when  tested  against  spores.  It  is  there- 
fore clear  that  alcohol  is  not  a  desirable  solvent  for  phenoKc  disin- 
fectants. 

Borates^  Perboeates  axd  Boric  Acid 

These  substances  possess  almost  negligible  germicidal  properties,  and 
are  used  as  mild  disinfectants  in  medicinal  washes,  and  as  antiseptics  for 
preserving  foods. 

Ether  and  Chlorofor:m 

The  vapors  of  both  ether  and  chloroform  possess  slight  but  definite 
action.  An  exposure  to  ether  vapors  of  one  to  forty-eight  hours  was 
necessary  to  sterilize  agar  slants  on  which  pyogenic  organisms  were  grow- 
ing.25  Ether  is  irregular  in  its  action,  for  good  contact  with  the  organ- 
isms is  difficult  to  secure.  Chloroform  is  sometimes  used  as  an  anti- 
septic to  preserve  antitoxic  serums. 

"  Topley,  Brit.  Med.  Journ.,  Feb.  6,  1915. 


1434  CHEMICAL  AGENTS  OF  DISINFECTIOISr 


SOAPS 

Ordinary  soaps  have  but  limited  disinfecting  power.  According  to 
Behring  the  germicidal  power  of  soaps  depends  upon  their  alkalinity, 
but  Serafini  more  correctly  points  out  that  the  free  alkali  present^  even 
in  concentrated  soap  solutions,  is  so  small  in  amount  that  it  can  exert 
no  disinfecting  action  whatever,  and  that  neither  the  alkali  nor  the 
fatty  acid,  nor  the  combination  of  the  two  is  the  efEective  agent. 

Unfortunately,  the  disinfecting  power  of  soap  solutions  is  not 
marked  enough  to  make  them  trustworthy  disinfectants  despite  their 
great  value  as  detergents.  The  common  commercial  soaps,  especially 
the  colored  soaps,  are  frequently  of  very  poor  quality,  containing  rosin 
instead  of  fat,  and  are  not  to  be  depended  upon.  The  soft  soaps  should 
also  be  avoided  on  account  of  the  presence  of  all  the  impurities  of  the 
fat  and  alkali  from  which  they  are  made.  There  are  other  conditions 
which  render  the  use  of  soaps  uncertain,  the  chief  of  which  is  the  hard- 
ness of  the  water. 

The  action  of  soap  solutions  is  mucTi  influenced  by  the  temperature, 
which  is  easy  to  understand  when  we  recall  the  powerful  germicidal 
action  of  hot  water  alone.  It  has  been  shown  that  soap,  even  in  strong 
solution  and  with  prolonged  exposure,  cannot  be  trusted  to  destroy  the 
infection  of  typhoid,  cholera,  or  the  micrococci  of  suppuration.  There- 
fore soaps  alone  cannot  be  depended  upon  for  the  disinfection  of  ob- 
jects and  clothing,  but  in  conjunction  with  certain  compatible  chem- 
icals, and  also  with  the  mechanical  cleansing  which  always  accom- 
panies their  application,  soaps  have  a  wide  and  varied  usefulness  in 
sanitation. 

Soap  solutions  should  always  be  made  with  soft  water.  The  addi- 
tion of  one  of  the  caustic  alkalies,  as  lye,  increases  their  germicidal  and 
detergent  value.  The  solution  should  be  strong,  containing  not  less 
than  10  per  cent,  of  soap,  and  the  water  should  be  as  hot  as  possible 
and  applied  with  mops  or  brushes. 

Medicated  soaps  are  for  the  most  part  a  snare  and  delusion  so  far 
as  any  increased  germicidal  action  is  concerned.  In  fact,  the  addition 
of  carbolic  acid,  bichlorid  of  mercury,  and  other  substances  which  have 
the  property  of  combining  chemically  with  the  soap  seems  actually  to 
diminish  the  disinfecting  value  of  the  substance.  As  a  rule  a  very  small 
quantity  of  the  disinfecting  substance  is  added  to  the  soap,  and  when  we 
call  to  mind  what  an  exceedingly  small  quantity  of  soap  is  generally 
used  for  the  ordinary  washing  of  the  skin  and  the  further  dilution  of 
this  small  amount  by  the  water  used  it  is  easy  fo  understand  that  medi- 
cated soaps  as  ordinarily  applied  cannot  have  an  energetic  disinfecting 
action. 


SOAPS 


1425 


An  exception  seems  to  bo  the  soap  devised  b}^  j\IcClintock,  in  which 
a  mercury  salt  exists  unchanged  and  active.  He  found  that  double 
iodid  of  mercury  answers  this  purpose  in  the  proportion  of  0.05  to  2 
per  cent.  A  solution  containing  1  per  cent,  of  the  soap  was  found 
by  him  to  be  fatal  to  pus  cocci,  cholera,  diphtheria,  and  typhoid  bacilli 
in  one  minute.  This  soap  does  not  attack  nickel,  silver,  aluminium,  steel 
instruments,  or  lead  pipes,  and  does  not  coagulate  albumin. 

The  value  of  soap  consists  in  the  removal  rather  than  the  milling  of 
germs;  that  is,  the  cleansing  properties  are  more  important  than  the 
germicidal  action.  In  hand  washing,  all  the  bacteria  are  not  removed 
by  soap  and  water.  Therefore,  an  active  germicide  must  be  used  in 
addition  in  order  to  render  infected  hands  safe. 

Comparative  Germicidal  Values. — The  following  is  a  table  of  com- 
parative germicidal  values  taken  from  Park : 

Tables  of  Germicidal  Values 


Alum    

Aluminium  acetate.  . 
Ammonium  chloric! .  . 

Boric   acid 

Calcium  chlorid 

Calcium  hypochlorite 

Carbolic  acid 

Chloral  hydrate 

Cupric  sulphate 

Ferrous  sulphate. .  .  . 
Formaldehyd  {4:0%) 
Hydrogen  peroxid .  .  . 


6,000 
9 

143 
25 

1.000 

333 

107 

2,000 

200 

10.000 

20.000 


Mercuric  chlorid 

Mercuric  iodid 

Potassium  bromid . 

Potassium  iodid 

Potassium   permanganate 

Pure  formaldehyd. 

Quinin  sulphate 

Silver  nitrate 

Sodium  borate 

Sodium  chlorid 

Zinc  chlorid 

Zinc  sulphate.  . 


14.300 

40,000 

10 

10 

300 

25.000 

800 

12.500 

14 

6 

500 

20 


CONVENIENT  FORMULAE  FOR  DISINFECTING  SOLUTIONS 


Bichlorid  of  Mercury — Corrosive  Sublimate. 

Bichlorid  of  mercury 1  dram 

Water    1  gallon 


1  gram 
1  liter 


Mix  and  dissolve.  Label  "Poison !"  This  is  approximately  a  1  to 
1,000  solution.  One  ounce  of  this  solution  contains  very  nearly  half  a 
grain  of  corrosive  sublimate.  Useful  for  disinfecting  clothing,  the  hands, 
the  surfaces  of  walls,  floors,  furniture,  etc.  Not  serviceable  for  feces 
or  material  containing  much  organic  matter. 

Formalin. 

Formalin    13  ounces     ;      100  c.  c. 

.  Water    1  gallon      I  1  liter 


Formalin  is  a  watery  solution  containing  40  per  cent,  formaldehyd. 
The  above  solution  contains  approximately  10  per  cent,  of  formalin  and 
is  useful  for  the  disinfection  of  clothing  and  a  great  variety  of  objects. 


1436  CHEMICAL  AGENTS  OF  DISINFECTION 

As  it  has  no  corrosive  action  it  does  not  bleach  pigments  or  rot  fabrics. 
When  used  to  disinfect  feces  a  stronger  solution  may  be  used. 

Milk  of  Lime. — Slake  a  quart  of  freshly  burnt  lime,  in  small  pieces, 
with  three-fourths  of  a  quart  of  water,  or,  more  exactly,  50  parts  of 
water  by  weight  with  100  parts  of  lime.  A  dry  powder  of  slaked  lime 
(calcium  hydroxid)  results.  Prepare  the  milk  of  lime  shortly  before 
it  is  to  be  used  by  mixing  1  quart  of  this  dry  calcium  hydroxid  with  4 
quarts  of  water.  Air-slaked  lime  is  worthless.  Slaked  lime  may  be 
preserved  some  time  if  inclosed  in  an  air-tight  container.  Milk  of  lime- 
is  especially  useful  for  the  disinfection  of  feces;  an  equal  quantity 
should  be  added  to  the  mass  and  thoroughly  mixed. 

Caxbolic  Acid- 
Crude  carbolic  acid  (or  phenol) ...      7  ounces    |     50  c.  c. 
Water    1  gallon    |        1  liter 

The  solution  is  facilitated  by  dissolving  in  hot  water.  This  makes 
approximately  a  5  per  cent,  solution.  The  addition  of  from  12  to  14 
ounces  of  common  salt  to  each  gallon  increases  its  germicidal  power, 
especially  when  aised  for  the  disinfection  of  excreta.  The  crude  carbolic 
acid  is  more  powerful  than  pure  phenol,  but  can  only  be  used  for  rough 
work,  such  as  floors,  feces,  sputum,  etc.  For  the  disinfection  of  cloth- 
ing phenol  should  be  used  and  the  solution  may  be  mixed  half  and  half 
with  water,  making  approximately  a  2^  per  cent,  solution. 

Chlorinated  Lime  ("Chlorid  of  Lime"). 

Chlorinated  lime    3  ounces     |     30  grams 

Water    1  gallon     |        1  liter 

Mix.  This  is  about  a  3  per  cent,  solution.  It  is  exceedingly  power- 
ful and  is  useful  for  the  disinfection  of  excreta,  privy  vaults,  cesspools, 
and  many  other  purposes.  It  is  an  active  bleaching  agent  and  destroys 
fabrics  in  this  concentration. 


CHAPTER  IV 
METHODS  OF  DISINFECTION 

A  feAv  instances  are  given  upon  the  following  pages  of  the  best  meth- 
ods of  disinfecting  rooms,  excreta,  and  fomites.  The  examples  selected 
have  been  taken  as  types  of  a  class.  In  public  health  work  the  things 
most  frequently  needing  disinfection  are  feces,  sputum,  and  other  dis- 
charges from  the  body;  bed  and  body  linen,  and  other  fabrics;  and  bed- 
rooms. The  disinfection  of  water  and  the  pasteurization  of  milk  have 
already  been  considered.  The  disinfection  of  ships  is  described  under 
Quarantine. 

Air. — It  is  quite  impossible  to  disinfect  the  air  of  a  room  during  its 
occupancy.  In  fact,  ordinarily  little  heed  need  be  given  to  the  air  itself. 
Any  of  the  known  volatile  substances  in  sufficient  concentration  to  kill 
microorganisms  would  render  the  air  unendurable.  It  is  absurd  to  place 
such  substances  as  carbolic  acid,  formalin,  or  chlorinated  lime  in  an 
open  pan  in  the  sickroom  or  in  the  bathroom  with  the  idea  that  they  are 
serving  a  useful  purpose  in  disinfecting  the  atmosphere  or  in  preventing 
the  spread  of  infection.  Occasionally  a  deodorant,  such  as  formalin, 
may  be  used  with  advantage  about  the  room,  but  where  proper  cleanli- 
ness and  ventilation  are  observed  such  substances  are  rarely  called  for. 

It  is  of  first  importance  to  prevent  the  infection  of  the  air  of  the 
room  by  taking  precautions  applicable  to  the  particular  infection  in 
question.  Thorough  ventilation  should  be  maintained,  and  in  this  way 
any  chance  infection  is  soon  lost  by  dilution  or  killed  by  the  sun.  An 
open  fireplace  is  admirable  for  the  ventilation  and  purification  of  the 
air  of  sickrooms,  for  by  this  method  the  infection  is  not  only  carried 
away,  but  is  destroyed  by  the  heat  of  the  fire  in  exit.  The  hanging  of 
sheets  wet  with  bichlorid  of  mercury  or  some  other  germicidal  solution 
at  the  doorway  serves  no  useful  purpose  except  as  a  reminder  to  those 
passing  in  and  out. 

When  a  room  has  become  badly  infected,  say  from  a  case  of  pul- 
monary tuberculosis,  and  there  is  danger  of  infection  through  the  dust, 
it  should  be  given  a  preliminary  fumigation  with  formaldehyd,  which 
will  partly  protect  the  operators  who  have  to  take  up  the  carpets  or  re- 
move the  bedding  and  other  articles  to  the  steam  sterilizer. 

Rooms. — The  disinfection  of  a  living-room  calls  for  all  the  resources 
of  the  disinfector's  art.    The  fact  that  it  is  necessary  to  bring  the  appa- 

1427 


1428  METHODS  OF  DISINFECTION" 

ratus  and  materials  to  the  room  in  order  to  disinfect  it  and  its  contents 
is  one  of  the  main  difficulties  and  will  often  require  the  ingenuity  and 
always  the  vigilance  of  the  operator. 

The  method  to  be  employed  for  the  disinfection  of  a  room  will  vary 
somewhat  with  the  infection  for  which  the  disinfection  is  done.  In 
routine  work  in  the  treatment  of  rooms  liable  to  be  infected  with  a 
variety  of  bacterial  viruses  formaldehyd  gas  is  the  most  generally  useful 
agent  we  possess.  In  the  case  of  yellow  fever  or  malaria  insecticides  must 
be  selected;  in  the  case  of  plague  our  efforts  must  be  directed  against 
rats,  mice,  fleas,  as  well  as  the  destruction  of  the  plague  bacillus.  In 
cholera  and  typhoid  fever  we  must  pay  particular  attention  to  the  feces, 
urine  and  the  objects  soiled  by  them,  etc. 

Certain  articles  commonly  found  in  living-rooms,  such  as  bedding, 
carpets,  rugs,  cuspidors,  upholstered  furniture,  and  other  objects  liable 
to  become  infected  must  be  treated  separately  by  some  process  applicable 
to  each  article.  None  of  the  gaseous  disinfectants  can  be  trusted  to 
penetrate  enough  to  render  articles  of  this  class  safe.  The  surest  method 
of  disinfecting  a  room  is  to  remove  fabrics  and  articles  for  special  treat- 
ment, and  to  wash  the  floor  and  other  surfaces  with  a  strong  hot  germi- 
cidal solution.  Finally,  give  the  room  a  house-cleaning,  sunning  and  air- 
ing.   It  may  then  be  renovated  with  paper  and  paint. 

Ordinarily  carpets  and  rugs  should  be  left  in  place  until  a  pre- 
liminary gaseous  disinfection  is  accomplished.  They  may  then  be  taken 
up  and  removed  for  steam  sterilization,  after  which  they  should  be  gone 
over  with  a  vacuum  cleaner  and  finally  hung  in  the  sun  for  a  day  or  two. 
If  carpets,  rugs,  upholstered  furniture,  mattresses,  pillows,  quilts,  or 
other  articles  have  become  badly  contaminated  with  infected  discharges 
the  soiled  areas  should  be  thoroughly  saturated  with  a  strong  solution  of 
formalin.  Bedding,  towels,  curtains,  clothing,  and  other  articles  of  like 
nature  may  be  left  in  the  room  exposed  to  the  action  of  the  gas,  but 
should  afterwards  be  removed  for  boiling,  steaming,  or  immersion  in 
one  of  the  germicidal  solutions,  as  none  of  the  gases  can  be  relied  upon 
for  the  disinfection  of  fabrics.  Articles  removed  from  the  room  for  dis- 
infection should  be  placed  in  a  bag  or  wrapped  in  a  sheet  wet  with 
bichlorid  6f  mercury.  Eubbish  that  has  collected  in  the  room  should 
be  gathered  and  burned.  The  cuspidors  and  their  contents  require  spe- 
cial treatment.  Door  knobs,  bed  rails  and  other  surfaces  handled  by  the 
patient  or  soiled  with  discharges  should  be  wiped  with  bichlorid  or  car- 
bolic solution.  For  the  preparation  of  a  room  for  fumigation,  see 
pages  266  and  1390. 

Stables. — The  disinfection  of  a  stable  requires  a  particularly  thorough 
application  of  all  the  resources  at  the  hand  of  the  disinfector.  The 
conditions  met  with  in  a  stable  render  its  disinfection  doubly  hard,  not 
only  on  account  of  the  accumulation  of  organic  filth  which  has  worked 


METHODS  OF  DISINFECTTOX  1429 

into  the  many  crevices  and  saturated  the  woodwork,  but  on  account  of 
the  high  resistance  of  anthrax  and  tetanus  spores,  for  which  stables  are 
sometimes  disinfected.  In  addition  to  these  diseases  stables  require 
disinfection  on  account  of  tuberculosis,  glanders,  pleuropneumonia,  foot- 
and-mouth  disease,  and  various  diseases  of  man  as  well  as  those  of  the 
domestic  animals. 

It  is  advisable  to  give  the  stable  a  preliminary  fumigation,  preferably 
with  sulphur,  in  order  to  destroy  surface  infection  and  the  vermin  which 
always  infest  these  places.  The  preliminary  fumigation  is  especially 
important  in  the  case  of  plague  and  glanders,  not  only  to  prevent  the 
spread  of  the  infection,  but  as  a  safegiiard  for.  the  disinfectors.  Then 
remove  all  small  articles  that  need  disinfection.  The  blankets  should 
be  wrapped  in  moist  bichlorid  sheets  and  boiled,  steamed,  or  immersed 
in  a  strong  germicidal  solution.  Buckets,  currycombs,  brushes,  stall  tools, 
and  other  equipments  that  have  been  in  contact  with  the  sick  animals  or 
with  infectious  materials  should  be  mechanically  cleaned  with  a  hot 
carbolic  solution  in  which  they  may  be  allowed  to  soak  over  night.  Me- 
tallic and  wooden  objects  or  utensils  should  be  given  a  thorough  prelim- 
inary cleansing  with  a  stiff  brush  and  hot  water  and  soap,  and  then 
boiled  or  immersed  in  a  5  per  cent,  solution  of  carbolic  acid  or  2  per 
cent,  solution  of  cresol  for  several  hours.  Leather  articles,  as  harness 
or  equipment,  should  receive  a  similar  preliminary  cleansing  and  be 
scrubbed  with  either  a  strong  solution  of  bichlorid  of  mercury  or  car- 
bolic acid. 

All  hay  and  grain  should  be  removed  from  the  racks  and  mangers 
and  all  bedding  from  the  floors.  After  its  careful  collection  at  some 
designated  point  this  refuse  should  be  saturated  with  petroleum  and 
destroyed  by  fire. 

The  stable  must  now  be  soaked  with  a  strong  antiseptic  solution  ap- 
plied with  a  hose  or  splashed  on  all  surfaces  by  means  of  mops.  The 
floors,  corners,  and  stalls  must  be  saturated  with  the  solution.  On 
account  of  the  presence  of  so  much  albuminous  matter  carbolic  acid  or 
one  of  its  derivatives  is  preferred  for  this  purpose  to  chlorinated  lime  or 
sublimate  solutions.  Chlorinated  lime  is  useful  if  used  in  suSicient  con- 
centration and  generous  amounts.  Xow  scrape  out  the  debris  from  all 
the  cracks  in  the  floors  and  walls;  collect  it  for  burning.  Then  clean 
the  woodwork  with  hot  lye  or  a  strong  alkaline  soap  solution  and  fol- 
low with  another  general  hosing  with  the  antiseptic  liquid. 

After  several  days'  exposure  to  air  and  sunshine  the  interior  of  the 
stable  should  receive  a  fresh  coat  of  whitewash,  applied  quickly,  and 
prepared  from  freshly  burnt  lime. 

The  watering  troughs  are  very  apt  to  Idc  infected,  especially  in  deal- 
ing with  glanders.  In  all  instances  not  only  the  troughs  and  watering 
buckets   should  be   disinfected  but  the  water   remaining-  in   them,   for 


1430  METHODS  OF  DISINFECTION 

often  there  is  no  drain  or  sewer,  and  this  water  poured  on  the  ground 
may  be  a  source  of  subsequent  infection.  The  water  may  first  be  disin- 
fected by  the  addition  of  a  suitable  amount  of  chlorinated  lime  or  any 
of  the  standard  germicides.  The  troughs  are  then  to  be  mechanically 
cleaned,  thoroughly  removing  all  organic  matter,  and  then  applying  a 
strong  germicidal  solution  to  both  the  inside  and  outside.  For  metal- 
lined  troughs  the  use  of  bichlorid  of  mercury  is,  of  course,  inapplicable, 
and  for  such  carbolic  acid,  alkaline  creosotes,  bleaching  powder  or  forma- 
lin is  recommended.  Most  germicides  are  poisonous,  and  must  there- 
fore be  finally  washed  out  of  the  troughs  or  buckets  by  flushing  with 
fresh  water  and  then  airing  in  the  sunlight  before  they  are  again  used. 
A  strong  carbolic,  formalin,  or  chlorinated  lime  solution  should  be  poured 
down  all  pipes  and  drains. 

Sometimes  the  ground  in  the  immediate  vicinity  of  the  stable  will 
need  attention.  Lime  or  the  gasoline  torch  will  generally  be  found  most 
useful  for  this  purpose.  Carcasses  and  excreta  are  to  be  disinfected  and 
disposed  of  according  to  the  methods  given  under  these  titles. 

Railroad  Cars. — Eailroad  cars  are  rooms  on  wheels.  The  principles 
of  their  disinfection  present  nothing  novel,  but  the  application  presents 
practical  difficulties. 

Flat  cars  or  open  cars  seldom  need  disinfection,  for,  even  should 
they  become  infected,  the  exposure  to  the  sun  and  weather  is  sufficient  to 
render  them  safe  from  the  danger  of  conveying  disease.  They  may 
readily  be  disinfected  whenever  that  may  be  necessary  by  scrubbing  or 
flushing  them  with  carbolic  acid  or  bichlorid  of  mercury  solutions. 

Freight  cars  or  box  cars  seldom  need  disinfection.  They  sometimes 
require  fumigation  on  account  of  mosquitoes,  fleas,  or  rats  and,  mice, 
which  such  cars  may  carry.  Freight  cars  are  best  treated  for  this  pur- 
pose with  sulphur  dioxid.  In  actual  practice  it  will  sometimes  be  found 
useful  to  steam  them  with  steam  from  the  locomotive. 

Cattle  cars  and  cars  used  to  transport  live  stock  need  special  atten- 
tion, particularly  if  anthrax,  tetanus,  glanders,  foot-and-mouth  disease, 
or  tuberculosis  is  the  infection  with  which  they  are  contaminated.  The 
disinfection  of  cars  of  this  type  is  so  much  like  the  disinfection  of  a 
stable  that  it  is  unnecessary  to  repeat  the  description  here.  Cars  of  this 
type,  as  well  as  all  cars,  should  be  kept  scrupulously  and  constantly  clean. 

Day  Coaches  and  Parlor  Cars. — If  the  disinfection  is  done  as  a  pre- 
cautionary measure  it  is  sufficient  to  fill  the  coach  with  formaldehyd 
gas, -which  should  be  followed  by  a  thorough  mechanical  cleansing. 
The  carpets  and  rugs  and  all  similar  articles,  including  the  upholstered 
seats  and  backrests,  if  removable,  should  be  taken  from  the  car  for 
vacuum  treatment  and  then  exposed  several  hours  to  the  sunshine.  The 
floors  should  be  mopped  or  scrubbed  with  one  of  the  germicidal  solutions 
and  the  spittoons  should  be  well  rinsed  in  a  warm  carbolic  bath  and  the 


METHODS  OF  DISINFECTION  1431 

contents  disposed  of  in  one  of  the  ways  mentioned  under  the  heading 
Sputum. 

If  the  disinfection  is  done  on  account  of  known  contamination  with 
one  of  the  communicable  diseases  the  car  is  treated  exactly  as  a  room 
would  be  under  like  conditions. 

A  railroad  coach  is  likely  to  harbor  mosquitoes,  flies,  and  other 
insect  pests  that  may  carry  disease;  therefore  precautions  will  have  to 
be  taken  to  keep  these  insects  out  of  cars  leaving  districts  infected  with 
yellow  fever,  typhus  fever,  malaria,  plague,  etc.,  or  measures  will  have 
to  be  taken  to  destroy  them  after  they  get  on  board.  As  both  these 
requirements  are  difficult,  if  not  impracticable,  it  will  usually  be  found 
best  to  provide  relays  at  a  convenient  point  and  require  the  passengers 
to  change  cars  upon  leaving  an  infected  for  an  infectible  area. 

Sleeping  cars  present  a  greater  difficulty  than  any  other  rolling 
stock.  The  berths  are  apt  to  become  infected  and  the  infective  agent  may 
live  there  a  very  long  time,  especially  as  they  are  kept  closed — almost 
hermetically  sealed,  against  fresh  air  and  sunshine  during  the  daytime. 
Much  of  the  difficulty  encountered  in  the  disinfection  of  the  sleeping  car 
is  due  to  peculiarities  in  construction,  such  as  the  compact  manner  in 
which  the  bedding  is  stowed  away,  the  heavy  and  unnecessary  carpets 
and  hangings,  the  excessive  molding  and  ornamentation  of  the  older  type 
of  cars,  the  use  of  such  materials  as  plush  for  upholstering,  etc.  The 
wash  basins  and  other  objects  in  the  toilet-rooms  are  liable  to  contamina- 
tion with  infected  discharges  from  the  mouth  and  nose.  The  faucets 
should  be  so  arranged  as  to  permit  washing  with  running  water,  thus 
eliminating  danger  from  the  bowl. 

Before  attempting  to  fumigate  the  interior  of  a  sleeping  car  or  a 
passenger  coach  with  one  of  the  disinfectants  it  is  important  to  close  the 
sashes  and  all  the  ventilator  openings  for  the  Pintsch  gas  flames.  Much 
gas  will  be  lost  through  the  open  hopper  of  the  water-closet  unless  that  is 
tamponed.  Some  cars  have  a  system  of  ventilating  ducts  of  fresh  air 
entering  under  the  seat  or  somewhere  near  the  bottom  of  the  car.  This 
must  be  closed.  Formaldehyd  gas  and  hydrocyanic  acid  gas  are  practi- 
cally the  only  gases  which  may  be  used  for  the  treatment  of  the  sleeping 
car.  As  these  gases  lack  the  power  of  penetration,  all  the  berths  must  be 
opened  and  all  the  bedding  and  other  fabric  should  be  removed  for 
steaming  or  other  treatment.  Hydrocyanic  acid  is  especially  serviceable 
for  the  destruction  of  bedbugs  and  vermin  which  frequently  infest  sleep- 
ing cars. 

After  the  bedding,  hangings,  carpets,  and  other  fabrics  have  been 
removed  from  the  car  the  toilet-room  should  be  given  special  attention. 
The  drinking  glasses,  the  wash  basins  and  slabs  of  the  washstands,  the 
brushes  and  combs,  the  seat  of  the  water-closet,  and  other  objects  liable 
to  infection  should  be  washed  or  immersed  in  one  of  the  standard  germi- 


1432  METHODS  OF  DISINFECTION 

cidal  solutions.  An  apparatus  for  disinfecting  sewage  on  railway  washes 
and  vessels  is  described  by  Frank. ^ 

Feces. — The  disinfection  of  feces  is  most  important  because  these  dis- 
charges are  most  dangerous  and  at  the  same  time  most  difficult  to 
render  safe.  Fecal  discharges  may  be  disinfected  with  carbolic  acid, 
cresols,  lime,  chlorinated  lime,  or  formalin,  as  described  below.  In  hos- 
pitals the  infected  discharges  are  sometimes  boiled  or  charged  with 
steam  in  an  appropriate  apparatus  with  the  addition  of  a  deodorizing 
substance,  as  potassium  permanganate  or  formalin. 

From  patients  the  discharges  should  be  received  in  a  glass,  or  im- 
pervious vessel  containing  some  of  the  germicidal  substance,  more  of 
which  is  added  afterwards,  and  the  mass  thoroughly  disintegrated  and 
mixed.  The  breaking  up  of  the  masses  and  mixing  is  best  done  with  a 
little  stick  which  is  then  dropped  into  the  mess.  The  mixture  should 
stand  at  least  two  hours  before  the  contents  are  disposed  of,  kept  well 
covered  meanwhile,  and  the  vessel  given  a  thorough  cleansing  and  disin- 
fection before  it  is  again  used.  At  least  .an  equal  quantity  of  the  germi- 
cidal solution  should  be  used  to  the  mass  disinfected  and  enough  should 
always  be  added  entirely  to  submerge  all  particles.  Excreta  must  always 
be  protected  from  flies  and  other  insects,  even  while  undergoing  disin- 
fection. 

It  is  necessary  to  emphasize  the  importance  of  breaking  up  all  masses 
until  they  are  completely  disintegrated,  and  mixing  thoroughly  with  the 
germicide.  It  is  almost  impossible  for  any  of  the  ordinary  germicides 
to  penetrate  particles  of  even  moderate  size,  within  a  reasonable  time; 
emulsions  do  not  penetrate  at  all,  and  therefore  should  not  be  used  to 
disinfect  feces. 

It  is  always  desirable  to  use  a  generous  excess  of  germicidal  agent, 
both  as  to  strength  and  amount,  in  disinfecting  feces.  The  following 
substances  and  methods  are  recommended : 

Lime  and  Hot  Water. — A  simple  and  effective  method  for  the  dis- 
infection of  feces,  such  as  typhoid  stools,  consists  in  adding  enough  hot 
water  to  cover  the  mass  in  the  receptacle,  and  then  adding  about  14  0^ 
the  entire  bulk  of  quicklime.^  A  large  cup  of  lime  is  about  enough  for 
an  average  stool.  The  receptacle  should  then  be  covered  and  allowed 
to  stand  for  two  hours.  In  addition  to  the  germicidal  action  of  the  lime 
there  is  enough  heat  generated  by  the  hydration  of  the  lime  to  destroy 
typhoid  and  similar  microorganisms.  It  is  important  to  start  with  hot 
water  from  50°  to  60°  C.  and  the  mass  will  then  be  heated  throughout 
to  80°  or  90°  C. 

A  bucket  of  boiling  water  (about  1  gallon)   will  disinfect  a  single 

^  P.  H.  Epts.,  Jan.  1,  1918,  Reprint  No.  247. 

^Linenthal.  H.,  and  Jones,  H.  JST.:  Monthly  Bull.,  State  Bd.  of  Health  of 
Mass.,  Jan.,  1914,  Vol.  IX,  No.  1,  p.  50.  Boston  Med.  and  Surg.  Jour.,  Jan.  8, 
1914. 


METHODS  OF  DISINFECTION  1433 

stool  wlien  otlior  <;('rini('i(lal  afjjciits  are  not  ohtaiiiaMo.  Tlic  vessel 
should  bo  covered  and  allowed  to  stand  until  cool.  SuHicicnt  heat  is 
thus  had  to  destroy  ])rai'tiea]ly  all  bacteria  except,  the  spore  bearers. 

mUh  of  Ijinic- — Tse  freshly  ])repared  milk  of  lime  contiiinini^-  1  jjart 
by  weight  of  tlu-  freshly  slaked  lime  to  I  ])arts  of  water.  Add  at  least  an 
equal  quantity  to  the  amount  of  material  to  be  disinfected  and  allow  the 
mixture  to  stand  no  less  than  two  hours  before  final  disposal.  The 
perfunctory  sprinkling  of  fecal  matter  with  lime  or  milk  of  lime,  as  is 
often  done,  is  not  effective.  Lime  should  not  be  thrown  into  the  hoppers 
of  water-closets  for  the  disinfection  of  dejecta,  for  otherwise  a  thick 
mass  may  accumulate  and  obstruct  the  pipes.  In  disinfecting  excreta 
with  lime  the  reaction  of  the  resulting  mixture  must  be  alkaline  else 
the  object  will  not  be  attained. 

Lime  or  milk  of  lime  is  useful  for  the  disinfection  of  privies,  or 
trenches  in  camp,  or  in  country  practice.  For  its  use  under  these 
circumstances  the  amount  required  may  be  arrived  at  as  follows :  The 
amount  of  fecal  matter  per  person  is  reckoned  at  400  grams  a  day.  If 
the  urine  is  also  to  be  disinfected  this  may  be  counted  as  1,500  to  2,000 
c.  c.  per  person  daily.  For  the  disinfection  of  the  solid  excrement  alone 
50  grams  of  lime,  or  400  c.  c.  of  the  milk  of  lime  (1  to  8),  must  be  reck- 
oned for  each  person  per  day.  If  the  urine  is  included  it  will  take 
four  to  five  times  as  much.  The  mixture  must  have  an  alkaline  reaction. 
Attention  is  again  called  to  the  fact  that  air  slaked  lime  is  inert. 

Chlorinated  Lime. — This  is  one  of  the  most  useful  and  potent 
germicidal  substances  for  the  disinfection  of  feces.  Use  at  least  a  3  per 
cent.,  better  5  per  cent.,  solution  and  an  amount  at  least  equal  to  the 
mass  to  be  disinfected.  Thoroughly  mix  and  allow  to  stand  at  least  8 
hours.  Chlorinated  lime  is  rendered  inert  by  organic  matter;  therefore 
an  excess  should  always  be  used.  It  is  also  converted  to  the  inert 
carbonate  upon  exposure  to  the  air  (see  page  1132).  Chlorinated  lime 
may  be  liberally  sprinkled  on  the  fecal  mass,  water  added,  and  the  mix- 
ture then  stirred. 

Formalin. — A  10  per  cent,  solution  of  formalin  may  be  depended 
upon  to  disinfect  feces  if  thoroughly  incorporated  with  the  mass  and 
allowed  to  stand  at  least  two  hours.  As  a  deodorant  it  acts  almost  in- 
stantly. 

Carbolic  Acid. — A  5  per  cent,  solution  of  crude  carbolic  acid  added 
to  an  equal  bulk  of  excreta  may  be  depended  upon  to  disinfect  in  two 
hours,  provided  the  germicide  is  thoroughly  incorporated  throughout 
the  mass. 

The  cresols  as  "tricresol"  and  liquor  cresolis  compositus  or  lysol  (1 
or  2  per  cent.)  are  valuable  agents  for  the  disinfection  of  fecal  matter  in 
small  amounts  on  account  of  their  energetic  action  and  because  their 
efficiency  is  not  greatly  impaired  by  the  presence  of  albuminous  matter. 


1434 


METHODS  OF  DISINFECTION 


Dry  earth  promotes  the  dehydration  of  excreta,  thus  delaying  putre- 
factive changes  while  absorbing  the  odors.  It  has  no  inherent  germi- 
cidal qualities. 

Corrosive  sublimate  is  not  well  suited  for  the  disinfection  of  feces 
and  sputum. 

Steam. — In  hospital  practice,  bed  pans  and  their  contents  are  steamed 
and  cleaned  in  special  apparatus.     See  Fig.  179. 

Sputum. — The  discharges  from  the  mouth  and  nose  not  alone  of  the 
sick,  but  of  well  persons,  are  often  laden  with  infection.    This  is  one  of 

the  frequent  means  by  which  dis- 
ease is  transferred.  The  proper 
disposal  of  sputum  and  its  effi- 
cient disinfection  are  therefore 
important  public  health  measures 
to  check  the  spread  of  tuberculo- 
sis, diphtheria,  scarlet  fever, 
measles,  whooping-cough,  influ- 
enza, tonsillitis,  common  colds, 
mumps,  chickenpox,  cerebrospinal 
fever,  poliomyelitis,  sore  throat, 
smallpox,  pneumonia,  the  pneu- 
monic form  of  plague,  etc.  It  is  a 
good  rule  to  require  the  discharges 
from  the  mouth  and  nose  of  all 
patients  to  be  received  upon  small 
pieces  of  gauze  or  in  individual 
cups  which  may  subsequently  be 
burned. 

Sputum,  when  in  consider- 
able quantities,  should  be  received  in  paper  cups,  which,  with  their 
contents,  may  be  burned.  If  this  is  not  practical,  it  may  be  received 
in  ordinary  cups  containing  5  per  cent,  carbolic  solution.  When  not 
in  large  quantities  sputum  and  other  infective  discharges  should  be 
received  on  cheap  cloths  or  soft  paper  and  promptly  burned.  If  hand- 
kerchiefs are  used  they  should  be  immersed  in  carbolic  solution  5  per 
cent,  for  one  hour  before  they  are  laundered. 

The  most  trustworthy  chemical  disinfectants  for  sputum  are  carbolic 
acid,  5  per  cent.;  formalin,  10  per  cent,  or  stronger;  chlorinated  lime,  5 
per  cent.  The  methods  for  the  disinfection  of  sputum  correspond  to 
those  described  for  feces.  Sputum  offers  special  difficulties  on  account 
of  the  mucus  which  is  readily  coagulated  and  hard  to  penetrate. 

Sputum  should  be  kept  well  covered  in  suitable  receptacles  until  it 
is  disposed  of.  Antiseptic  solutions  may  be  used  in  bedside  cups  or  in 
cuspidors,  but  are  not  necessary. 


Fig.  179. — Steam  Sterilizer  for  Bed 
Pans. 


METHODS  OF  DISIXFFX'TIOX  1435 

The  disinfection  of  the  large  amounts  of  sputum  such  as  that  col- 
lected in  hospitals,  public  buildings,  and  other  places  is  a  difficult  and 
disagreeable  task.  On  account  of  its  dense  consistency  it  prevents  the 
penetration  of  chemical  solutions.  A  very  good  apparatus  for  the  disin- 
fection and  disposal  of  sputum  in  hospitals,  sanatoria,  etc.,  consists  of  an 
autoclave  in  which  the  material  is  steamed  under  pressure  and  at  a  tem- 
perature of  120°  C. ;  after  the  completion  of  the  process  the  disinfected 
mass  is  washed  through  the  drain  into  the  sewer  by  water  entering  the 
autoclave.  The  entire  operation  can  thus  be  conducted  under  cover.  Dr. 
Wm.  J.  Manning^  describes  an  ingenious  and  efficient  method  of  han- 
dling spittoons  and  disposing  of  the  sputum  at  the  Government  Printing 
Office  in  Washington.  The  cuspidors  are  self-draining.  They  are  col- 
lected and  handled  by  devices  so  that  the  attendants  do  not  have  to 
handle  them  directly. 

Bed  and  Body  Linen. — Fabrics,  such  as  towels,  napkins,  handker- 
chiefs, sheets,  pillowslips,  underwear  and  similar  articles,  should  always 
be  disinfected  after  contact  with  any  of  the  communicable  diseases,  for 
they  are  very  apt  to  become  infected.  They  may  be  steamed  or  boiled  or 
immersed  in  a  germicidal  solution  such  as  carbolic  acid,  5  per  cent. ; 
formalin,  10  per  cent. ;  or  bichlorid  of  mercury,  1  to  1,000. 

Special  care  is  necessary  in  washing  or  disinfecting  towels,  sheets, 
underwear,  and  other  fabrics  soiled  with  such  discharges  as  pus,  blood, 
or  excreta.  If  they  are  heated  or  boiled  without  special  precautions  they 
will  become  indelibly  stained  by  the  coagulation  of  the  albuminous  mat- 
ter which  becomes  fixed  in  the  fiber. 

Soiled  wash  may  be  treated  as  follows :  It  is  vrrapped  in  a  sheet  wet 
"with  sublimate  solution,  and  this  is  placed  in  a  sack  likewise  moistened 
with  a  germicidal  liquid.  The  sack  is  placed  unopened  in  a  solution 
containing  3  per  cent,  of  soft  soap  and  heated  to  50°  C.  for  three  hours 
and  left  in  the  same  solution  for  forty-eight  hours  after  it  cools.  If  not 
soiled  with  albuminous  matter  the  wash  may  be  immersed  in  a  solution 
of  bichlorid  of  mercury  1  to  1,000,  with  the  addition  of  common  salt. 
After  this  preliminary  disinfection  the  articles  are  boiled  half  an  hour 
in  a  water  containing: 

Petroleum    10  grams 

Soft  soap 250       " 

Water 30  liters 

Books.  — With  the  exception  of  their  exposed  surface,  books  cannot  be 
disinfected  in  the  bookcase  or  on  the  shelves  of  houses  and  libraries. 
However,  if  the  books  have  not  been  handled  or  exposed  to  infection  in 
any  way  except  by  their  presence  in  the  sickroom  there  is  no  reason  for 
considering  any  part  of  the  book,  except  the  exposed  surface,  as  infected. 
'  J  A.  Jtf,  A.,  Sept.  11,  1909,  Vol.  LII,  pp.  829-832. 


1436  METHOD>S  OF  DtSINFECTtOM 

Such  books  may  be  disinfected  with  formaldehyd  gas  without  first  dis- 
turbing them  in  any  way. 

Books  which  have  been  handled  by  the  patient  or  which  have  been 
otherwise  exposed  to  infection  require  particular  care  in  their  disinfec- 
tion on  account  of  the  difficulty  of  penetrating  between  the  leaves.  Books 
used  in  public  libraries  are  often  regarded  with  suspicion,  and  many 
librarians  require  that  they  should  be  sunned,  aired,  or  disinfected  be- 
fore they  are  again  issued.  The  danger  from  this  source  has  doubtless 
been  exaggerated.  Books,  however,  which  have  been  handled  by  persons 
suffering  with  one  of  the  readily  communicable  diseases  should  always 
be  disinfected  before  they  are  again  used. 

Books  may  be  disinfected  in  a  specially  constructed  chamber  by  means 
of  heat  and  formaldehyd  gas.  They  must  be  arranged  to  stand  as  widely 
open  as  possible  upon  perforated  wire  trays.  Under  these  conditions  the 
exposure  should  be  continued  twelve  hours  with  high  percentage  of  for- 
maldehyd and  a  temperature  of  80°  C,  a  partial  vacuum  having  first 
been  introduced.  The  binding,  illustrations,  and  print  of  books  are  not 
injured  by  this  process. 

When  only  a  few  books  are  to  be  treated  in  the  absence  of  a  special 
apparatus  they  may  be  disinfected  by  placing  2  or  3  drops  of  a  40  per 
cent,  formalin  solution  on  every  second  page,  taking  care  to  distribute 
the  drops  well.  The  book  is  then  laid  in  a  close  box  or  drawer  in  which 
more  formalin  has  been  sprinkled,  and  left  in  a  warm  place  for  not 
less  than  twenty-four  hours. 

Pamphlets  and  unbound  volumes  may  be  steamed  without  serious 
harm.  Steam  is  not  applicable  to  the  disinfection  of  bound  books  on 
account  of  the  glue  and  leather. 

Beebe  *  recommends  dipping  the  books  in  a  solution  of  carbolic  acid 
and  gasoline.  After  immersion  the  books  should  be  placed  before  an 
electric  fan,  which  rapidly  drives  off  the  gasoline. 

Mce^  recommends  the  use  of  moist,  hot  air  at  80°  C,  and  30  or 
40  per  cent,  humidity  for  thirty-two  hours  for  the  disinfection  of  books. 
This  is  said  to  destroy  all  non-spore-bearing  bacteria  in  closed  books, 
even  tubercle  bacilli  in  thick  layers,  without  injuring  the  most  delicate 
bindings. 

Cadavers. — Dead  bodies  are  seldom  the  cause  of  spreading  commu- 
nicable diseases.  The  body  without  previous  washing  should  be  wrapped 
in  a  sheet  wet  with  a  strong  germicidal  solution,  such  as  bichlorid  of 
mercury,  1  to  500,  carbolic  acid,  5  per  cent.,  or  cresol,  1  per  cent., 
until  it  is  disposed  of.  Should  it  be  desirable  to  wash  the  body  it 
should  be  done  with  formalin  (10  per  cent.)  or  Labarraque's  solution, 
or  one  of  the  germicidal  solutions  above  mentioned. 

*Jour.  Am.  Public  Health  Assn.,  Vol.  I,  No.  1,  p.  54,  Jan.,  1911. 
V.  A.  M.  A.,  April  20,  1912,  Vol.  LVIII,  No.  16,  p.  1201. 


METHODS  OF  DISINFECTIOX  1437 

From  a  sanitary  stand])()i]it  hodit's  dead  of  one  (if  llic  coinmunicahlo 
diseases  are  best  disposed  of  by  burning.  When  cremation  is  not  prac- 
ticaldo  tho  body  may  bo  surroimdfd  l)v  twice  its  wcj^rlif  of  fposbly  burnt 
lime  ill  an  lirniu't ically  scaliMl  collin  and  Iniricd  at  least  (i  foet  under- 
ground. There  is  much  less  danger  from  the  spread  of  disease  from 
bodies  buried  in  the  ordinary  way  than  is  commonly  supposed. 

Eml)almini^-  witli  strong  solutions  of  formalin  and  arsenic  that  are 
commonly  used  for  this  ))urj)osc  is  effective  in  destroying  all  but  the 
surface  infection. 

The  disposal  of  bodies  dead  of  anthrax  is  an  important  and  difficult 
matter  and  has  been  discussed  on  page  402. 

Thermometers. — A  thermometer  may  be  the  source  of  conveying  dis- 
ease from  one  person  to  another,  and  it  behooves  the  physician  to  exer- 
cise special  care  concerning  its  cleanliness  and  disinfection^.  The  best 
practice  is  to  keep  a  pure  formalin  or  70  per  cent,  alcohol  in  the  thermom- 
eter case  in  which  the  instrument  is  kept  constantly  bathed. 

Wells  and  Cisterns. — The  disinfection  of  a  well  may  be  accomplished 
by  the  use  of  freshly  burnt  lime.  About  half  a  barrel  is  thrown  into  the 
well,  stirred  up  with  the  Avater,  and  the  walls  are  scrubbed  down  with 
the  resulting  milk  of  lime.  The  well  is  then  pumped  out,  cleaned, 
allowed  to  refill,  and  a  second  supply  of  lime  added,  after  which  the  well 
is  allowed  to  stand  twenty-four  hours.  After  a  thorough  stirring  the  so- 
lution is  then  pumped  out  and  the  well  is  allowed  to  refill  and  is  re- 
emptied  until  the  water  is  practically  free  from  lime.  Instead  of  lime 
chlorinated  lime  may  be  used  for  this  purpose,  sufficient  being  added  to 
make  approximately  a  1  per  cent,  solution. 


SECTION   XV 
MILITARY  HYGIENE 

Military  efficiency  depends  upon  the  health  of  the  command.  Many 
military  disasters  have  been  due  to  disease.  Valor  and  patriotism  are 
seriously  handicapped  by  typhoid  fever,  dysentery,  malaria  and  other 
infections  which  in  years  past  have  sapped  the  strength  of  armies.  More 
soldiers  in  the  world's  history  have  succumbed  to  bacteria  than  to  bullets. 
Until  recently,  the  high  morbidity  and  mortality  rates  among  troops  have 
been  notorious.  It  is  only  in  recent  years  that  the  results  of  sanitary 
science  have  been  able  to  safeguard  the  soldier  and  sailor  against  many 
infections  that  formerly  decimated  the  ranks.^  In  fact,  the  fruits  of  pre- 
ventive medicine  are  most  conspicuous,  picturesque  and  convincing  in 
armies  and  navies.  Formerly  the  medical  service  dealt  principally  with 
the  surgery  of  wounds  and  the  treatment  of  fevers;  now,  however,  the 
larger  part  of  the  energy  and  skill  of  the  medical  corps  is  directed  toward 
their  prevention.  Therefore,  the  medical  officer  must  be  a  sanitarian  as 
well  as  a  physician  and  surgeon. 

The  first  successful  use  of  preventive  measures  dates  from  the  efforts 
of  Florence  Xightingale  in  the  Crimean  Campaign  (185J:),  and  on  a 
larger  scale  to  the  methods  employed  by  the  Germans  in  the  Franco- 
Prussian  War  of  1870-1871. 

The  subject  of  camp  sanitation,  however,  is  not  new.  Thus  we 
read  in  Deuteronomy,  "Thou  shalt  have  a  place  also  without  the  camp, 
whither  thou  shalt  go  forth  abroad :  And  thou  shalt  have  a  paddle  upon 
thy  weapon;  and  it  shall  be,  when  thou  wilt  ease  thyself  abroad,  thou 
shalt  dig  therewith,  and  shalt  turn  back  and  cover  that  which  cometh 
from  thee."     If  the  above  primitive  injunction  had  been  followed  by 

*  The  conditions  during  our  Civil  War  are  thus  described  by  Charles  Francis 
Adams: 

"The  trouble,  however,  was  that  we  were  all  so  inexperienced,  and  knew 
nothing  of  the  laws  of  health  and  self-preservation,  and  we  thought  those  laws 
not  worth  knowing.  Why  any  of  us  survived  I  cannot  now  see,  but  we  were 
young  and  robust  as  a  rule,  we  lived  in  the  open  air  and  we  were  at  least  tem- 
perate. On  the  other  hand,  we  had  no  schools  of  instruction.  .  .  .  We  were,  too, 
encamped  in  low  lands  for  convenience  of  access  to  water  on  account  of  the 
horses.  .  .  .  With  a  suggestively  growing  sick  list,  it  never  occurred  to  me  to 
change  my  camp  to  higher  ground  or  drier  soil,  to  put  my  men  in  motion  on  some 
pretext,  or  to  alter  my  own  diet.  I  stupidly  blundered  along,  myself  sickening 
day  by  day.  .  .  .  These  simple  precautions  never  seemed  to  suggest  themselves  to 
our  armv" medical  men."  "Autobiographv  of  Charles  Francis  Adams,"  pp.  146, 
162,  and' 163. 

1439 


1440  MILITARY  HYGIENE 

our  troops  in  the  Spanish-American  War  it  would  have  saved  thousands 
of  cases  of  sickness  and  death  from  typhoid  fever.- 

Soldiers  are  notoriously  improvident,  indifferent  and  uninformed 
concerning  questions  of  health.  Constant  and  skilled  supervision  is 
necessary  over  food,  water,  clothing,  ammunition,  personal  hygiene  and 
safety.  Hence  instruction  in  the  essentials  of  military  hygiene  and  first 
aid  becomes  one  of  the  prime  duties  of  the  medical  corps. 

Military  hygiene  is  only  a  special  application  of  the  facts  and  prin- 
ciples of  general  hygiene,  applied  to  the  particular  conditions  of  camp, 
barrack,  field  and  march.  The  efficient  medical  officer  must  be  ac- 
quainted with  these  particular  conditions,  else  incompetency  is  bound  to 
result.  Training  of  the  medical  officer  for  military  service  is  therefore 
an  important  part  of  preparedness. 

In  campaigns  the  objects  of  medical  administration  are  first  and 
foremost  the  preservation  of  the  strength  of  the  army  in  the  field,  and 
secondarily  the  care  and  treatment  of  the  sick  and  injured  at  the  front, 
in  the  line  of  communications  and  in  the  home  territory.  The  first 
object  is  obtained  by  an  application  of  all  sanitary  measures;  by  the  re- 
tention of  effectives  at  the  front  and  the  movement  of  non-effectives  to 
the  rear  without  obstructing  military  operations;  and  finally  by  the 
prompt  succor  of  wounded  on  the  battlefield  and  their  removal  to  the 
rear,  thus  preventing  the  unnecessary  withdrawal  of  combatants  from 
the  firing  line  to  accompany  the  wounded,  and  promoting  the  general 
morale  of  the  troops. 

The  diseases  of  the  civil  population  are  reflected  in  the  soldier  and 
sailor.  It  is  therefore  impossible  to  obtain  a  satisfactory  health  record 
in  large  bodies  of  troops,  if  the  public  health  of  the  civil  population 
receives  imperfect  attention.  A  nation  at  war  naturally  focuses  its 
attention  upoji  the  health  of  the  military  forces,  but  it  cannot  afford  to 
ignore  the  civil  population.  It  should  always  be  remembered  that  only 
about  10  per  cent,  of  the  population  is  available  for  active  service  in  the 
field,  leaving  90  per  cent,  of  the  entire  population  to  be  cared  for  at 
home.  In  previous  wars,  and  to  a  certain  extent  in  the  World  War, 
this  phase  of  the  question  was  not  given  the  consideration  it  deserves. 

Sanitary  isolation  between  the  military  forces  and  the  civil  popu- 
lation is  neither  possible  nor  desirable.  If  measles,  tuberculosis,  plague, 
syphilis,  gonorrhea,  or  other  infections  prevail  among  the  civil  popula- 
tion, these  same  infections  will  soon  find  their  way  into  the  troops.  The 
commerce  is  reciprocal,  for  the  troops  return  the  infection  into  the 
homes. 

The  diseases  of  the  World  War  differed  somewhat  from  those  of  pre- 
vious wars,  for  the  reason  that  never  before  in  the  history  of  the  world 

^  One-third  of  our  entire  command  had  typhoid  fever.  There  were  about 
20,000  cases  and  3,000  deaths  in  a  total  of  about  107,000  officers  and  enlisted  men. 


MirJTAIJV    IIVCIENE  1441 

have  armies  of  sudi  vast  size  Ix-on  iiidhilizcil,  ami  tlic  {Diiilitiiins  of 
actual  warfare  have  changed,  so  as  to  si  rain  tlu'  ludsi  rohiisl  const  it  utioii. 
Prolonged  trench  warfare  dcprcsse,'-^  vitality  in  a  way  uid<nowii  to  cam- 
paigning in  the  open.  This  favored  the  development  of  tnlicrculosis; 
and  the  necessity  for  frequent  leaves  of  ahsenee  fostered  the  spread  of 
venereal  diseases. 

Several  "new"  diseases,  such  as  "trench  fever'"  and  "war  nephritis," 
were  described.  Tlie  conditions  of  trench  fighting  have  brought  out 
many  cases  of  "trench  foot,"  a  serious  and  disal)ling  condition.  Weil's 
disease,  influenza,  pneumonia,  measles,  and  other  infections  were  prev- 
alent. 

Against  this  record,  we  have  triumphs  of  sanitary  science  in  con- 
trolling typhoid  fever,  cholera,  dysentery,  and  other  diarrheal  diseases, 
and  satisfactory  control  of  typhus,  plague,  smallpox,  and  other  serious 
insect-borne  infections. 

Comparative  Loss  in  Campaign  from  Sickness  and  Wounds. — From 
the  records  of  past  campaigns  many  valuable  lessons  may  be  drawn.  In 
1809.  during  the  Walcheren  expedition  the  mortality  in  the  British  army 
from  disease  was  346.9  per  1,000  effectives,  while  only  16.7  per  1,000 
were  killed  by  the  enemy.  In  the  Eussian  campaign  against  Turkey,  in 
1828,  it  was  estimated  that  80,000  men  died  of  disease  and  20,000  in 
consequence  of  wounds.  During  General  Scott's  campaign  in  Mexico 
the  losses  from  disease  alone  exceeded  33  per  cent,  of  the  effective 
strength  of  the  forces  under  his  command;  and  of  a  single  regiment 
of  Indiana  volunteers,  which  entered  the  service  1,000  strong,  only  400 
returned  to  the  State  for  muster  out.  Laveran  states  that  in  the 
Crimean  War  the  allies  Jost  52,000  men  in  six  months,  of  which  number 
50,000  men  were  unharmed  by  the  Russians.  During  the  entire  war, 
according  to  Viry,  the  French  lost  no  less  than  95,000,  of  whom  75,000 
died  of  disease. 

The  mortality  among  the  United  States  forces  in  the  Civil  War  was 
divided  as  follows : 

Mortality  White  Colored  Total 

Killed  in  battle 42,724  1,514  44,238 

Died  of  wounds   47,914  1,817  49,731 

Died  of  disease   157,004  29,212  186,216 

Died,  cause  unknown   23,347  837  24,184 

Total   270,989         33,380      '  304.369 

From  the  most  reliable  data  available,  the  deaths  in  the  armies  of 
the  Confederate  States  during  this  struggle  did  not  fall  short  of  200,000, 
three-fourths  of  which  number  were  due  to  disease  and  one-fourth  to 
the  casualties  of  battle. 

In  the  War   of   1866   against  Austria,   out   of   a   total   strength   of 


1443  MILITARY  HYGIENE 

437,260,  the  Prussians  lost  in  an  unusually  brief  and  decisive  campaign 
6,247  men  by  sickness  and  4,450  at  the  hands  of  the  enemy.  The 
Franco-Prussian  War  of  1870-1871  furnishes  the  only  exception  to  the 
general  rule  that  more  men  are  killed  by  disease  than  by  the  weapons 
of  the  eneiny,  since  of  the  German  army  33.7  per  1,000  strength  fell 
in  battle,  while  only  18.6  per  1,000  died  of  disease.  This  result  was 
largely  due  to  the  observance  of  sanitary  precautions,  assisted,  no  doubt, 
by  the  brevity  of  the  campaign,  the  rapidity  of  the  movements  and 
the  fact  that  active  operations  were  conducted  during  the  most  health- 
ful season  of  the  year.  In  the  Eusso-Turkish  War  of  1878,  according 
to  Viry,  the  Russians  lost  102,799  men,  of  whom  only  16,578  were  killed 
by  the  enemy.  During  the  Spanish-American  War  of  1898,  for  the 
five  months  which  included  the  total  period  of  hostilities,  of  the  274,717 
officers  and  men  enrolled  in  the  United  States  forces  there  were  only 
345  men  killed  by  the  enemy,  while  about  3,000  died  of  typhoid  fever. 
It  is  said  that  of  the  old  soldiers  carried  on  the  United  States  pension 
rolls,  those  disabled  by  disease  are  more  than  four  times  greater  in 
number  than  those  pensioned  for  wounds. 

In  the  World  AVar,  for  the  first  time  in  history,  we  lost  fewer  men 
from  disease  than  from  wounds. 

Killed  in  action 33,123 

Lost  at  sea  733 

Died  of  wounds   13,555 

Died  of  accident 4,887 

Died  of  disease  23,375 

Total  75,673 


RECRUITS  AND  RECRUITING 

Nothing  is  more  mistaken  than  the  lay  idea  that  any  man  with  cour- 
age would  make  a  good  soldier.  A  suitable  recruit  must  not  only  be  able- 
bodied,  but  he  must  have  good  character,  mentality,  habits,  and  tem- 
perament. A  minor  physical  defect  may,  under  the  strain  and  privations 
of  a  campaign,  not  only  incapacitate  him,  but  require  the  attention  of 
several  useful  soldiers  in  taking  care  of  him.  Nor  does  the  story  end 
here,  for  later  he  may  secure  a  pension  from  a  government  which  he 
never  usefully  served.  This  is  too  commonly  the  case  with  volunteer 
troops  whose  standards  of  recruiting  are  below  that  of  regular  troops. 

In  1900  the  admissions  for  disease  in  the  United  States  Army  per 
1,000  strength  were  1,821  regulars,  against  2,762  volunteers;  while  the 
mortality  was  12  and  25,  respectively.^ 

^  "Military  Hygiene,"  by  Valery  Havard,  2d  ed.,  p.  172.  Wm.  Wood  &  Co., 
1914, 


EECRUITS  AM)  HKCRUITING  1443 

I)iiriiig  tlu'  war  witli  Mexico  the  regular  troops,  who  lM)re  the  brunt 
of  the  campaign,  lost  about  two-thirds  as  many  from  disease  and  by 
discharge  for  disability  as  did  the  volunteer  troops,  the  former  having 
been  physically  examined,  whereas  the  latter  had  not.  In  the  Civil 
War  the  annual  mortality  from  disease  was  3*^  j)er  1,(»00  in  the  case  of 
the  regular  army,  and  55  per  1,000  from  the  less  carefully  examined 
volunteers.  At  the  same  time  the  annual  loss  by  discharge  on  certificate 
of  disability  was  68  per  1,000  for  the  regulars  and  91  per  1,000  for  the 
volunteers. 

During  the  World  War  there  were  examined  physically  at  local 
boards  about  2.510,000  men  between  the  ages  of  21  and  30  years.  Of 
these  46.8  per  cent,  were  found  to  have  defects  and  730,000,  or  29.1 
per  cent.,  were  rejected  on  physical  grounds.  Additional  physical  de- 
fects discovered  or  emphasized  in  mobilization  camps,  resulting  in  the 
discharge  of  the  men,  would  perhaps  increase  this  to  nearly  35  per  cent. 
— a  rejection  of  more  than  one  man  out  of  every  three. 

The  effectiveness  of  a  force  depends  upon  its  vigor  rather  than 
upon  its  size.  The  strength  and  health  of  a  military  organization  is 
based  upon  the  physical  character  of  the  individuals  composing  it,  and 
celerity  of  movement  and  the  ability  to  bear  hardship  are  imperatively 
demanded  in  the  successful  manipulation  of  armies.  Eecruits  must  be 
of  trustworthy  physique  and  sound  constitution  before  military  character 
can  be  developed,  and  the  physically,  mentally,  and  morally  defective 
are  hence  to  be  uniformly  rejected  as  unfit  for  service.  The  ^Medical 
Corps  has,  therefore,  an  important  responsibility  in  examining  recruits 
for  enlistment  in  the  various  services ;  not  alone  the  health  of  the  army, 
but  military  efficiency  depends  upon  the  care  with  which  candidates 
are  selected  and  assigned.  The  recruiting  depot  further  acts  as  a 
quarantine  to  keep  communicable  diseases  out  of  the  army. 

The  recruit  is  surrounded  by  temptations — especially  alcohol  and 
prostitution — and  a  policy  of  timely  restraint,  education,  and  pro- 
phylaxis in  connection  with  mobilization  is  imperative.  The  recruit 
is  suddenly  removed  from  the  restraining  and  supporting  influence  of 
the  home  and  home  society.  He  is  in  the  adolescent  years  when  desire 
is  strong  and  the  will  weak. 

It  is  an  interesting  but  readily  understandable  fact  that,  whereas 
voluntary  applicants  for  enlistment  endeavor  to  conceal  defects,  con- 
scripts try  to  escape  service  by  magnifying  existing  defects  or'  feigning 
nonexistent  ones.  In  the  examination  of  conscripts,  therefore,  a  skep- 
tical attitude  of  mind  should  be  maintained  toward  alleged  disabilities. 

It  must  also  be  kept  in  mind  that  there  are  numerous  corps  and 
departments  in  the  various  armies  of  the  service.  The  requirements  for 
recruits  in  each  of  these  differ  somewhat.  Thus,  the  requirements  of 
height  and  weight  are  different  for  infantry,   cavalry,   and   artillery; 


1444  MILITAEY  HYGIENE 

vision  is  especialh'  important  in  the  signal  corps;  the  requirements  for 
the  medical  corps,  the  paymaster's  corps,  the  commissary  corps,  the 
ordnance  department,  the  engineering  corps,  the  aviation  service,  etc., 
vary,  and  each  has  its  own  special  qualifications.  Especially  in  examin- 
ing for  an  officer's  commission,  it  is  important  that  the  medical  exam- 
iner be  acquainted  with  the  particular  service  in  which  the  candidate 
intends  to  enlist. 

City  bred  men  make  better  soldiers  for  immediate  service  than  coun- 
try lads;  however,  the  latter  outstrip  the  former  after  a  year  or  two  of 
training.  Town  bred  men  are  quicker  to  imderstand  what  is  required 
and  hence  are  sooner  trained.  •  They  are  usually  immune  to  measles, 
whooping-cough,  mumps,  and  other  diseases  of  childhood,  which  often 
prevail  in  recruiting  camps,  and  are  apt  to  lower  the  standard  of  health 
and  vigor  of  country  youths.  Eecruits  from  cities  are  more  likely  to 
be  familiar  with  some  technical  trade  which  is  of  value  in  -nlar. 

THE  PHYSICAL  EXAMIXATIOX 

When  a  recruit  arrives  at  a  recruit  depot  he  immediately  receives 
his  physical  examination.  This  is  completed  by  medical  oSicers  detailed 
for  the  purpose,  and  is  particularly  thorough.  Under  the  volunteer 
system  of  recruiting,  pressure  is  at  times  brought  to  bear  on  the  examin- 
ing surgeon  to  accept  men  who  are  subnormal.  This  pressure  may  be 
from  the  man  personally,  or  from  some  one  else  who  is  interested  in  him. 
This  naturally  adds  to  the  difficulties  of  the  situation,  but  it  is  always 
the  wisest  course  for  the  examining  surgeon  to  reject  all  those  candi- 
dates who  do  not  come  up  to  the  standard  provided  in  the  recruiting 
regulations. 

Eules  for  the  examination  of  recruits  are  issued  in  pamphlet  form 
from  the  War  Department  under  the  title  of  Special  Eegulations  65, 
Xov.  8,  1918,  and  they  set  forth  the  defects  which  call  for  the  rejection 
of  candidates.  These  are  all  pathologic  defects,  and  these  specifications 
should  be  carefully  followed  by  all  officers  performing  this  work. 

An  applicant  for  first  enlistment  to  the  Eegular  Army  must  be  a 
citizen  of  the  United  States,  between  the  ages  of  18  and  35  years,  of 
good  character,  temperate  habits,  able-bodied,  free  from  disease,  and 
must  be  abe  to  speak,  read  and  write  the  English  language.  For  the 
Conscript  Army  authorized  by  Congress  the  age  limits  were  21  to  30. 

Age. — It  is  generally  recognized  that  youths  under  22  cannot  stand 
the  strain  and  privations  of  war.  Up  to  the  twenty-fifth  year  growth 
and  development  are  taking  place,  the  bones  are  not  fully  formed,  nor 
have  they  reached  their  final  hardness;  the  epiphyses  have  not  become 
incorporated  with  the  shafts  of  the  long  bones;  the  joints  are  not  fully 
developed;  the  chest  has  by  no  means  attained  its  full  capacity;  the 


RECEUTTS  AND  REClUTITTXa  11 15 

organs  of  the  liody  in  irciuTiil  arc  iiiimaturc.  The  hoart  is  unduly 
suscoptiltlo  to  overstrain,  and  tlie  nniseles  lack  endurance.  Xapoleon 
said  that  "boys  only  serve  to  fill  the  hospitals  and  encumber  the  road- 
side." Further,  young  men  are  more  susceptible  to  many  infections, 
both  on  account  of  youth  and  because  they  are  more  careless,  reckless 
and  inexperienced.  On  the  other  hand,  young  men  are  quick  to  learn, 
ready  to  act,  brave,  and  amenable  to  discipline.  Under  eighteen  years 
of  age  the  candidate  for  enlistment  must  have  ihe  consent  of  parent  or 
guardian. 

The  so-called  'Seterans"  of  Xapoleon  were  men  of  2G  to  28  years, 
and  his  "old  guard"  consisted  of  men  from  28  to  29;  at  Austerlitz  the 
oldest  soldiers  were  33  and  at  Friedland  3G  years  old  (Houget  et 
Dopter).  It  will  seldom  be  in  the  interest  of  the  service  to  enlist  men 
over  30  years  old,  and  the  legal  limit  of  35  is  only  intended  to  be  used 
in  times  of  emergency.  After  20  years  in  the  ranks,  and  when  past 
40  years  of  age.  the  soldier  soon  becomes  unequal  to  the  arduous  duties 
of  field  service.  During  the  World  War  the  age  limits  were  stretched 
to  the  utmost  by  all  the  nations  actively  engaged. 

Strong,  well  developed  boys,  with  a  burning  desire  to  enter  the 
service,  but  under  the  legal  years,  sometimes  try  to  deceive  the  recruit- 
ing officer  as  to  their  correct  age.  According  to  Greenleaf,  there  are 
certain  evidences  of  maturity  which  usually  accompany  the  period  of 
legal  majority,  and  with  which  the  recruiting  officer  should  familiarize 
himself.  "At  21  years  of  age,  the  wisdom  teeth  are  usually  cut,  and 
on  each  side  of  both  jaws  there  should  be  found  five  grinders,  viz.,  three 
large  double  or  molar  teeth,  and  two  smaller  double  or  bicuspid  teeth. 
In  case  of  the  loss  of  teeth,  the  spaces  originally  occupied  by  them  may 
be  seen."  Further,  the  color  of  the  scrotum,  and  the  development  of 
hair  under  the  axillae  and  about  the  genitals  help  to  determine  correct 
age. 

Character  and  Mental  Condition. — These  are  determined  by  the  re- 
cruiting officer  so  far  as  possible  by  demeanor,  expression,  manner  of 
answering  questions,  absence  of  obscene  tattooing,  nature  of  glance,  etc. 
It  is  exceedingly  difficult  in  a  brief  examination  to  appraise  character. 
It  is  also  difficult,  but  very  important,  to  discover  degeneracy  or  mental 
unfitness.  The  medical  examiner  must  be  familiar  with  psychiatry, 
^fental  unfitness  is  often  more  disqualifying  than  physical  defects.* 
Dementia  precox  is  the  most  important  mental  disease  from  the  stand- 
point of  military  service — feeble-mindedness  in  itself  is  not  so  serious 
a  factor.  Syphilis  and  heredity  are  the  underlying  causes  of  most  mental 
diseases.  Every  effort  should  be  made  to  detect  psychoneuroses,  epi- 
leptics, alcoholics,  and  drug  addicts. 

*  "Exclusion  of  the  Mentallv  Unfit  from  Military  Service,"  Sheehan.  U.  S. 
Naval  Med.  Bull,  vol.  X,  No.  2,'  April,  1916,  p.  213. 


1446 


MiLlTAEY  HYGIEl^E 


In  the  United  States  Army  during  the  year  1913  the  discharge  rate 
for  mental  disease  was  higher  than  that  from  any  other  cause. 

Height,  weight  and  chest  measurements  are  recorded.  They  should 
conform  to  established  standards  and  bear  certain  definite  proportions 
one  to  another. 

TABLE  OF  PHYSICAL  PROPORTION  FOR  HEIGHT,  WEIGHT,  AND   CHEST  MEASUREMENT 
ACCEPTED    STANDARD    MEASUREMENTS 


Height 

Chest  Measurement 

Weight, 

Feet 

Inches 

Pounds 

At  Expiration  : 
Inches 

Mobility  : 
Inches 

5      1/12 

61 

120 

31 

2 

5     2/12 

62 

120 

31 

2 

5     3/12 

63 

124 

31 

2  • 

5     4/12 

64 

128 

32 

2 

5     5/12 

65 

130 

32 

,   2 

5     6/12 

66 

132 

32% 

2 

5     7/12 

67 

134 

33 

2 

5     8/12 

68 

141 

3314 

2% 

5     9/12 

69 

148 

33V> 

21/0 

5  10/12 

70 

155 

34 

21/2 

5  11/12 

71 

162 

34i/> 

21/2 

6 

72 

169 

343/1 

3 

6     1/12       • 

73 

176 

351/4 

3 

6     2/12 

74 

183 

361/4 

3 

6     3/12 

75 

190 

363/4 

31^ 

6     4/12 

76 

197 

3714 

31/2 

6     5/12 

77 

204 

371/2 

3% 

6     6/12 

78 

211 

381/4 

4 

Variations  from  this  standard  are  permitted  if  the  applicant  is  active, 
has  firm  muscles  and  is  evidently  vigorous  and  healthy. 

The  requirements  of  the  War  Department  (Circular  IsTo.  1,  August  5, 
1913)  specify  the  minimum  height  for  infantry,  coast  artillery  and 
engineers  at  64  inches;  for  cavalry  and  field  artillery  between  64  and  72 
inches;  for  mountain  batteries  between  68  and  72  inches.  Foreign  coun- 
tries have  a  minimum  standard  of  less  than  62  inches,  save  Germany,  62 
and  England,  64  inches. 

The  minimum  weight  for  all  branches  of  our  service  is  128  pounds, 
as  stated  in  the  "Eules  for  Examining  Eecruits,"  General  Orders,  No. 
66,  "War  Department,  1910,  Circular  Xo.  1,  1915.  An  otherwise  de- 
sirable candidate  as  light  as  120  pounds  may  be  accepted.  But  no  can- 
didate who  weighs  less  than  120  pounds  will  be  accepted  without  special 
authority  from  the  Adjutant  General  of  the  Army.  The  maximum 
for  infantry,  coast  artillery  and  engineers  is  190  pounds;  for  cavalry 
and  field  artillery,  165  pounds. 

Chest  measurements  are  obtained  at  the  end  of  forced  inspiration  and 
forced  expiration.  The  chest  girth  is  taken  by  means  of  a  tape  measure 
passed  around  on  a  line  including  the  lower  portions  of  the  scapulae,  and 


RECRUITS  AND  RECRUITING  1447 

on  a  level  with,  or  just  below,  tiie  nipple.  Chest  measurements  do  not 
give  as  good  an  idea  of  the  respiratory  capacity  as  tiie  spirometer,  the 
use  of  which  has  not  yet  become  general  in  recruiting  ofTices.  The  rule 
in  the  United  States  Service  is  to  reject  men  wiio  measure  less  tiian  3"-3 
inches  about  the  ciiest,  unless  specially  qualified  and  (h'sirable.  For  men 
under  fi7  inclies  in  height  the  difTerence  between  insj)iration  and  ex{)ira- 
tion  should  be  not  less  than  2  inclies;  between  (i7  and  7"^  inches,  not  less 
than  2.5  inches;  72  inches  and  above,  not  less  than  3  inclies.  The  chest 
capacity  or  "mobility,"  well  called  "vital  capacity,"  is  one  of  the  best 
indexes  of  vigor  and  endurance. 

As  a  general  rule,  the  higher  the  social  class  to  which  the  recruit 
belongs,  the  better  he  will  be  physically  as  well  as  mentally,  lor  it  is 
notorious  that  in  European  armies,  where  military  service  is  obligatory, 
the  officers  are  usually  taller  and  heavier  than  the  enlisted  men.  Vision 
is  an  exception  to  this  rule,  for  it  grows  more  imperfect  as  we  ascend 
the  social  scale,  so  that  perfect  eyesight  is  oftener  found  in  the  middle 
and  lower  than  in  the  higher  and  better  educated  classes. 

Vision. — Good  vision  is  of  greatpr  importance  for  the  soldier  than 
formerly,  because  of  the  conditions  of  modern  warfare :  the  distant  and 
hidden  enemy,  often  with  only  the  head  showing  if  anything,  and  the 
inconspicuous  color  of  the  uniform,  blending  with  the  background. 
Binocular  vision  is  important  in  estimating  distance.  A  higher  degree  of 
impairment  of  vision  is  more  permissible  in  the  left  eye  than  the  right — 
the  eye  used  in  shooting.  It  has  been  found  that  a  visual  acuity  of  20/40, 
or  even  20/70,  in  the  aiming  eye  is  consistent  with  good  shooting,  pro- 
vided the  soldier  is  able  accurately  to  focus  both  sights  of  the  rifle. 
The  prescribed  visual  requirements  in  the  United  States  Army  are 
as  follows: 

1.  For  the  line  of  the  Army :  20/40  for  the  better  eye,  and  20/100  for 
the  poorer  eye,  provided  no  organic  disease  exists  in  either  eye. 

Recruits  may  be  accepted  for  the  line  of  the  Army  when  unable  with  the 
better  eye  correctly  to  read  all  of  the  letters  on  the  20/40  line,  provided  they 
are  able  to  read  some  of  the  letters  on  the  20/30  line. 

2.  I^or  the  Ordnance  Department  and  for  the  Medical  Department : 
20/70  in  each  eye,  correctible  to  20/40  with  glasses,  provided  no  organic 
disease  exists  in  either  eye. 

Candidates  for  a  commission,  and  candidates  for  the  United  States 
Military  Academy,  must  have  vision  that  does  not  fall  below  20/40  in 
either  eye,  and  not  below  20/20  unless  the  defect  is  a  simple  refraction 
error,  not  hyperopia,  is  not  due  to  ocular  disease,  and  is  entirely  cor- 
rected by  proper  glasses.  Hyperopia  requiring  any  spherical  correction, 
anisometropia,  squint,  or  muscular  insufficiency,  if  marked,  are  causes 
for  rejection. 


1448  MILITARY  HYGIENE 

Color  sense  is  tested  with  the  usual  skeins.  Color  blindness  is  a 
cause  for  rejection  in  the  signal  corps  and  the  air  service, — also  to  the 
United  States  Military  Academy,  and  for  commissioned  officers.  By 
color  blindness  is  meant  red,  green,  or  violet  blindness,  and  not  confusion 
of  the  delicate  shades  of  blues,  greens  and  purples. 

To  test  for  color  blindness,  the  colored  skeins  should  be  mixed  in  a 
pile,  and  test  colors  (primary  red,  green,  etc.)  placed  apart  and  the 
applicant  told  to  select  all  the  skeins  that  resemble  the  test  colors.  The 
namcvS  of  the  colors  should  not  be  used  in  making  the  test.  Each  eye 
is  tested  separately.     See  page  923. 

Teeth. — The  teeth  must  be  serviceable  and  should  be  reasonably  free 
from  peridental  trouble  which  may  lead  to  secondary  and  serious  infec- 
tions. The  actual  number  of  teeth  is  less  important  than  good  occlu- 
sion. Unless  four  pairs  of  teeth  oppose,  it  is  a  cause  for  rejection.  It 
must  be  remembered  that  the  field  service  ration  is  apt  to  be  not  well 
cooked.  False  teeth  may  be  lost  or  broken.  Caries  should  be  cor- 
rected before  enlistment,  for  the  Army  dental  surgeons  are  overworked. 

Vaccination. — All  recruits  are  -vaccinated  against  smallpox  and  are 
required  to  take  the  typhoid  prophylactic  inoculations.  A  record  is  made 
of  this  work,  so  that  it  is  always  known  at  what  time  such  vaccinations 
have  been  given. 

Under  special  circumstances  prophylactic  vaccines  against  cholera, 
plague,  paratyphoid,  dysentery  and  other  infections  are  used.  Poly- 
valent vaccines  may  be  used — that  is,  three,  four,  or  more  bacterial  vac- 
cines may  be  mixed  and  injected  at  the  same  time.  Thus  in  the  Serbian 
campaign  a  tetravaccine  was  used  consisting  of  typhoid,  paratyphoid  A 
and  B  and  cholera. 

General. — The  recruiting  officer  takes  into  account  the  cleanliness  of 
person  and  clothing.  The  examination  should  be  made  stripped.  The 
applicant  is  observed  while  walking,  running,  and  jumping.  Special 
examinations  are  made  of  the  lungs,  heart,  teeth,  skin,  joints,  and  feet; 
for  the  presence  of  hernia,  varicocele,  and  other  disqualifications.  Par- 
ticular attention  is  paid  to  the  condition  of  the  legs,  ankles  and  feet. 
Varicose  veins,  large  or  recent  bunions,  corns  on  the  sole,  flat  foot,  and 
"hammer  toe"  disqualify  the  applicant  for  marching  and  are  causes 
for  rejection. 

When  accepted,  recruits  receive  preliminary  training  in  tactics  and 
barrack  life.  A  soldiers'  handbook  is  issued  to  them  in  which  are  dis- 
cussed the  articles  of  war,  guard  duty,  rations,  clothing,  arms  and  equip- 
ment, codes  for  signaling  and  an  outline  of  first  aid  and  care  of  health. 


EECRUITS  AND  RECRUITING  U49 

7'AM/A7.V(; 

Training  consists  partly  of  drills  and  physical  exercises,  given  pri- 
marily to  develop  the  soldier,  and  discipline  and  instruction  in  mili- 
tary organization  and  tactics.  The  medical  officer  gives  instructions  in 
personal  hygiene,  including  talks  on  venereal  diseases,  the  latter  being 
considered  from  both  the  moral  and  the  physical  standpoints. 

As  soon  as  his  training  has  progressed  sufficiently  to  justify  his 
assignment  to  a  permanent  company,  the  recruit  is  sent  to  some  regi- 
ment. There  his  military  training  progresses  in  the  company  of  his 
fellows,  and  after  six  or  twelve  months'  service  he  is  classed  as  a 
trained  soldier. 

The  object  sought  in  physical  training  for  military  purposes  is  not 
strength,  but  rather  agility,  endurance,  and  coordination.  In  addition 
to  marching  and  setting-up  drills,  boxing,  fencing,  wrestling,  skating, 
swimming  and  games  are  useful.  Exhaustion  or  overstraining  must  be 
avoided.  It  is  a  mistake  to  try  to  make  the  soldier  too  quickly.  ^lany 
cannot  stand  the  pace. 

Marching  should  be  the  principal  outdoor  exercise  of  the  soldier. 
It  is  also  the  most  exhausting,  owing  to  the  weight  of  equipment  carried. 
Good  marching  is  obtained  only  by  careful  preparation,  strict  discipline, 
and  regard  for  sanitation.  Marches,  at  first  short,  are  gradually  length- 
ened until  the  soldier  can  cover  15  or  20  miles  a  day  Ijearincr  his  full 
equipment  without  marked  fatigue  and  with  feet  in  good  condition. 

Napoleon  is  credited  with  the  remark  that  battles  are  won  with  legs 
rather  than  with  arms.  Success  in  war  depends  largely  upon  getting 
there  first  with  the  most  men.  Transportation  by  motor  trucks  and 
other  modern  means  has  not  diminished  the  importance  of  marching. 

Young  soldiers  and  young  recruits  unaccustomed  to  active  muscular 
exercise  soon  tire  out.  The  exercises,  therefore,  should  be  simple  at  first 
with  gradually  increasing  severity.  All  nations  realize  that  on  the 
soldier's  endurance  may  depend  success  or  failure :  therefore,  soldiers  of 
all  countries  are  given  systematic  exercise  in  garrison  and  encouraged  in 
athletics  so  far  as  possible.  ^lanuals  are  issued  for  both  gA-mnasium  and 
outdoor  work.  For  our  soldiers,  advantage  is  usually  taken  of  the  ma- 
terial at  hand,  and  the  exercises  favored  are:  1.  Setting-up  exercises, 
largely  limb  and  body  movements.  2.  ^larching,  double  time  and  running. 
3.  Eifle  and  saber  exercises.  4.  Climbing,  jumping  and  vaulting.  5.  Gym- 
nastic contests.   6.  Athletic  contests,  wrestling  and  boxing.   7.  Swimming. 

The  beneficial  effects  of  these  exercises  soon  manifest  themselves  in 
stronger  muscles  and  increased  endurance. 

In  military  training  there  is  usually  an  initial  loss  in  weight,  but 
owing  to  the  healthful  regime,  good  food,  and  regular  habits,  the  recruit 
soon  puts  on  weight. 


1450  MILITARY  HYGIENE 

Training  should  include  personal  hygiene  and  the  recruit  should  be 
required  to  follow  certain  general  rules: 

The  body  must  be  kept  clean  and  free  of  vermin;  a  daily  bath  not 
only  cleanses  but  refreshes  the  body. 

The  hair  of  the  head  should  be  trimmed  close. 

The  tooth  brush  should  be  used  daily  or  oftener. 

The  hands  should  be  washed  before  eating  and  after  leaving  the  sink. 

The  feet  of  dismounted  soldiers  should  be  cleaned  daily  on  arrival 
in  camp  and  clean  socks  put  on  to  replace  the  ones  used  on  the  march. 

The  soldier  should  not  drink  or  eat  food  prepared  or  sold  from  an 
unauthorized  source. 

Duties. — The  duties  of  the  medical  officer  are  varied  and  often  exact- 
ing. They  include  both  preventive  and  curative  medicine.  In  general, 
the  duties  are :  to  look  after  the  health  of  troops  in  camp,  barracks,  and 
on  the  march;  attend  to  the  wounded  on  the  battlefield;  organize  and 
administer  hospitals,  ambulance  and  transport  service,  quarantine  sta- 
tions, medical  supply  depots  and  laboratories;  to  inspect  and  supervise 
the  quality  of  the  food  and  water;  to  instruct  officers  and  men  in  mili- 
tary hygiene  and  first  aid;  to  examine  recruits;  and  to  assist  both  staff 
and  line  in  all  questions  involving  medicine,  surgery,  hygiene  or  sani- 
tation. 

An  Army  Medical  School  is  maintained  at  Washington  for  the  pur- 
pose of  instructing  the  officers  of  the  Medical  Corps,  and  in  turn  the 
members  of  the  Medical  Corps  give  general  instruction  in  military  hy- 
giene, first  aid,  etc.,  to  officers  and  men  of  the  staff  and  line. 

The  duties  of  the  medical  officer  are  specified  in  regulations  which 
should  be  carefully  studied  and  followed.  The  regulations  in  the  Manual 
for  the  Medical  Department  are  only  part  of  the  general  body  of  reg- 
ulations with  which  the  medical  officer  must  acquaint  himself.  Obe- 
dience, uniformity,  and  discipline  are  essential  qualities  for  military 
efficiency. 

The  medical  officer  of  the  army  is  not  only  a  physician,  but  also  a 
soldier,  and  as  such  must  be  a  component  part  of  a  disciplined  machine. 
Whether  in  the  field,  on  the  march,  or  in  camp,  he  has  his  position  and 
must  fit  into  it,  or  there  will  be  friction.  All  medical  officers  are 
mounted,  and  it  is  therefore  important  to  know  how  to  ride  a  horse 
and  manage  it  in  maneuvers.  Again,  emergencies  arise  when  it  is  neces- 
sary for  the  medical  officer  to  become  an  active  combatant.  He  must 
know  the  routine  of  getting  supplies,  the  position  of  the  sanitary  per- 
sonnel on  the  field  in  time  of  war,  the  disposition  of  the  property  of 
the  wounded,  and  the  method  of  reporting  various  activities.  There- 
fore, it  is  important  for  the  medical  officer  to  spend  two  to  four  months 
in  a  training  camp.  It  is  also  important  that  he  be  familiar  with  mili- 
tarv  law. 


EQUIPMENT  1451 

Military  law  is  provided  for  the  government  of  armies  in  peace  and 
war.  There  are  two  divisions  of  military  law:  One  is  called  international 
law  and  treats  particularly  of  the  action  of  armies  and  individuals  of 
those  armies  in  time  of  war,  or  at  any  time  when  they  come  in  contact 
with  foreign  nations.  That  part  of  international  law  which  is  of  in- 
terest to  our  armies  in  time  of  war  is  laid  down  in  a  small  hook  published 
by  the  War  Department  called  "The  Rules  of  Land  Warfare,"  and  can 
be  obtained  by  application  to  the  Adjutant  General,  Washington,  D.  C. 
These  rules  are  of  decided  interest  to  the  medical  officer,  for  his  actions 
when  captured  by  the  enemy,  or  in  other  contingencies,  are  laid  down 
carefully  and  must  be  obeyed  to  the  letter. 

The  other  division  of  military  law  is  for  the  internal  government 
of  the  army  and  is  covered  by  the  "Articles  of  War."  which  form  the 
common  law  for  the  army.  Offenses  are  classified  and  punishments  pro- 
vided in  the  same  way  that  the  civil  law  is  written. 

The  educational  duties  of  the  Medical  Department  are  of  a  twofold 
nature,  to  the  public,  and  to  the  military  service.  The  Surgeon  Gen- 
eral's Library  at  Washington  is  "the  great,  central  medical  library  of 
reference  of  the  Xation."  The  Medical  Department  also  maintains  the 
Army  Medical  Museum  and  an  Army  Medical  School  in  Washington, 
at  which  regular  courses  of  instruction  are  given  to  medical  officers ;  and 
the  Medical  Department  Field  Service  School  at  Carlisle,  Pennsylvania ; 
the  Medical  Research  Laboratory  and  School  for  Flight  Surgeons  at 
Mineola,  Long  Island,  for  training  medical  officers  in  the  examination 
and  care  of  the  personnel  of  the  air  service. 

The  objects  of  medical  administration  in  campaign.  ,are :  "First,  pres- 
ervation of  the  strength  of  the  army  in  the  field — (a)  by  the  necessary 
sanitary  measures;  (b)  by  the  retention  of  effectives  at  the  front  and  the 
movements  of  non-effectives  to  the  rear  without  obstructing  military 
operations;  and  (c)  by  the  prompt  succor  of  wounded  on  the  battlefield 
and  their  removal  to  the  rear,  thus  preventing  the  unnecessary  with- 
drawal of  combatants  from  the  firing  line  to  accompany  the  wounded, 
and  promoting  the  general  morale  of  the  troops. 

"Second,  the  care  and  treatment  of  sick  and  injured  at  the  front,  in 
the  line  of  communications,  and  in  the  home  territory."  ^ 


EQUIPMENT 

The  soldier's  equipment  includes  his  arms  and  accouterments,  cloth- 
ing, and  all  other  things  necessary  for  his  comfort  and  health.  All 
articles  of  equipment  must  be  of  good  quality,  of  greatest  strength  and 
best  wearing  power,  with  the  least  possible  weight.    There  then  remains 

^Manual  of  the  Medical  Department, 


1453 


MILITARY  HYGIENE 


the  very  important  problem  of  distribution  on  his  person  so  as  to  be 
carried  with  the  minimum  muscular  exertion  and  fatigue.  In  all  armies 
this  problem  is  given  much  attention. 

German  experiments  applied  to  the  respiratory  capacity  of  soldiers 
have  shown  that  their  loads,  including  overcoats,  should  seldom  exceed  55 
pounds.    The  weight  of  the  equipment  of  various  nations  is  as  follows: 

United  States  of  America,  new  equipment 48  pounds 

"  "         old  "  56 

Italy 58 

France    57 

England 52 

Germany   59 

Austria 61 

Russia    60 

Japan    55 

The  above  weights  are  approximate,  varying  according  as  the  over- 
coats, trenching  tools,  shelter  tents,  etc.,  may  be  temporarily"  discarded. 
It  is  important  that  the  weight  be  divided  so  that  unnecessary  articles 
can  readily  be  detached  before  going  into  battle,  or  where  transportation 


-y  —  y 

Fig.  180. — Pbopek  and  Improper  Methods  of  Distributing  the  Equipment. 
(Havard's  "Military  Hygiene,"  Wm.  Wood  &  Co.) 

is  available.  The  haversack  has  been  discarded  in  our  army  and  its  place 
taken  by  a  pack  arrangement,  wherein  weight  is  distributed  over  the 
soldier's  back  with  the  least  disturbance  to  center  of  gravity,  thereby 
saving  extra  muscular  exertion. 


EQUIPMENT  1453 

The  weight  of  llie  United  States  equipment  is  divided  as  follows: 

TABLE   OF  ARTICLES   OF  EQUIPMENT,    WITH    WKICIIT   ()!•'    K.\(  II     (Kccfl'l) 


Pounds 

Ounces 

Clothing  (with  extra  pair  socks) 

7 
9 
5 

1 
2 

1 

3 
1 

3 

2 
3 

1 

4 

13 

Rifle  and  sling 

.92 

100  cartridges 

15.88 

Cartridge   belt 

G.l 

Trench ine:   tool 

2.04 

Bayonet   and   scabbard 

First  aid  pack  and  poiuli 

Canteen  filled  with  cup  and  cover 

5.48 

5.59 

10.03 

Haversack   

9.85 

Pack   carrier 

7.32 

Blanket    

1 

Shelter  tent  half  with  5  pins 

Poncho    

11.68 

Meat  can,  knife,  fork  and  spoon 

Rations    (2  reserve)    with  containers,   1  bacon  can,   1 

1.21 

1.72 

Toilet  articles:  towel,  soap,  comb,  tooth  brush 

7 

48 

2.83 

This  equipment  is  so  divided  that  shelter  halves,  etc.,  can  be  dis- 
carded before  going  into  battle,  thus  reducing  the  total  weight,  which, 
with  two  extra  bandoleers  of  cartridges,  brings  the  Aveight  to  39  pounds. 

In  wagon  trains,  there  are  carried  for  each  man  an  undershirt,  a  pair 
of  drawers,  two  pairs  of  woolen  socks,  a  pair  of  shoes  with  extra  laces, 
sweater  and  mosquito  bar. 

The  First-aid  Packet. — The  first-aid  packet  has  done  much  to  reduce 
mortality  from  wounc]  infections.  When  a  ball  enters  or  goes  through 
the  muscles  or  soft  parts  of  the  bodj^  alone,  generally  nothing  need  be 
done  except  to  protect  the  wound  or  wounds  with  the  contents  of  the 
first-aid  packet. 

Each  packet  contains: 

(1)  Two  bandages  of  absorbent  sublimated  (1:1000)  gauze,  4  by 
S4  inches. 

(2)  Two  compresses  of  absorbent  sublimated  (1:1000)  gauze,  each 
composed  of  i/o  square  yard  of  gauze,  folded  so  as  to  make  a  compress 
314  by  7  inches. 

(3)  Two  iSTo.  3  safety  pins  wrapped  in  waxed  paper. 

The  packet  thus  prepared  is  placed  in  an  hermetically  seal'ed  metal 
case  with  a  suitable  arrangement  for  easy  opening.  All  contents  of  the 
case  must  be  sterile.  Dimensions  of  the  case  should  not  exceed  4  by  2^4 
by  16  inches. 

The  shell-wound  dressing  consists  of: 

(1)  One  compress  composed  of  1  square  yard  of  absorbent  sub- 
limated (1:1000)  gauze,  so  folded  as'to  make  a  pad  6  by  9  inches. 


1454  MILITARY  HYGIENE 

(2)  One  bandage,  3  inches  wide  by  5  yards  long,  of  absorbent  sub- 
limated (1:1000)  gauze,  loosely  rolled  and  wrapped  in  parchment  or 
waxed  paper. 

(3)  Two  No.  3  safety  pins  wrapped  in  waxed  paper. 

The  whole  dressing  is  wrapped  in  tough  paper,  with  directions  for 
'application  printed  thereon.*'' 

Clothing. — The  things  sought  for  in  the  soldiers'  clothing  are  uni- 
formity and  neatness  in  appearance,  maintenance  of  body  temperature, 
and  protection  from  wet  and  traumatism.  It  must  allow  full  freedom 
of  muscular  action,  avoid  constriction  of  any  vital  part  of  the  body,  and 
must  not  interfere  with  physiological  function.  The  chief  function  of 
clothing  is  to  assist  in  the  maintenance  of  an  equable  body  temperature. 
Further,  there  are  military  reasons  for  the  adoption  of  the  fabric,  color 
and  style  of  clothes.  Wearing  quality  and  protection  not  only  against  the 
elements  but  the  enemy  must  be  considered.  In  modern  warfare  showy 
uniforms,  such  as  worn  by  the  British  "red-coats"  and  the  French  red- 
trousered  Zouaves,  have  given  way  to  colors  which  make  less  conspicuous 
targets.  The  colors  now  preferred  are  brown,  olive-drab,  olive-green, 
green-gray,  and  similar  shades  that  blend  with  the  landscape.  It  is  also 
now  customary  to  have  little  difference  between  the  uniforms  of  officers 
and  men.  The  great  loss  of  officers  in  the  British  Army  in  the  early 
part  of  the  World  War  was  due  partly  to  their  distinctive  dress  and 
conspicuous  station  in  front  of  the  command. 

Uniforms  made  of  a  heavy,  feltlike  material  will  absorb  rain  and 
perspiration,  gather  dirt,  and  when  driven  into  the  body  in  shell  wounds 
are  very  apt  to  give  rise  to  serious  infections. 

Allowances  are  usually  made  for  the  dress  of  native  troops.  For 
instance,  the  Cossacks  habitually  wear  their  sheepskin  coats;  the  Philip- 
pine Constabulary  have  a  distinctive  uniform;  the  Sikhs  wear  their  tur- 
bans, etc.  Other  reasons  such  as  climate  and  occupation  govern  the 
type  of  uniforms.  For  instance,  our  troops  in  Arctic  posts  are  supplied 
with  mackinaws,  fur  caps  and  gloves;  aviators  affect  a  tight-fitting, 
closely  woven  uniform,  with  cap  and  mask  designed  to  offer  but  little 
resistance  to  the  wind  and  to  prevent  the  radiation  of  body  heat. 

The  materials  used  for  clothing  for  military  purposes  are :  wool,  cot- 
ton, linen,  paper,  leather,  fur,  rubber,  etc. ;  also  such  mixtures  as  shoddy, 
merino,  etc. 

Of  these  substances,  u'ool  is  perhaps  the  most  valuable.  It  is  a  poor 
conductor  of  heat,  absorbs  water,  but  gives  it  up  slowly;  whereas,  cotton 
becomes  wet,  dries  quickly,  and  therefore  feels  damp  and  chilly  when 
moist.  Wool,  however,  has  the  disadvantage  of  shrinking  on  washing. 
Cotton,  besides  being  cheap,  wears  well,  is  cool,  and  does  not  shrink. 

'Drill  Regulations  and  Service  Manual  for  Sanitary  Troops,  U.  S.  A.,  1914, 
p.  143. 


EQUIPMENT  1455 

Merino,  a  mixture  of  cotton  and  wool,  is  niiuli  used  for  underwear. 
Linen  conducts  heat  more  readily  than  cotton,  but  absorbs  moisture 
poorly;  furthermore,  it  is  more  expensive  than  cotton.  Paper  conserves 
warmth  and  was  used  by  the  Japanese  for  this  purpose.  A  paper  vest 
makes  an  excellent  protection  against  cold  winds,  and  a  newspaper  be- 
tween blankets  on  a  cold  night  lielps  to  keep  the  body  snug  and  warm 
and  takes  the  place  of  extra  covering.  The  uscl'uhiess  of  clotliing  de- 
pends not  alone  on  the  material,  but  on  the  weave,  texture  and  color  of 
the  fabric.  White  is  the  coolest  and  i)lack  the  warmest,  with  blue  a 
close  second.  Olive-drab  is  somewhat  warmer  than  khaki,  which  is  a 
closely  woven,  hard   finished,  cotton  cloth. 

Waterproof  Nf/  may  be  accomplished  oitlier  by  coating  the  cloth  with 
an  impervious  substance,  as  rubber,  or  by  impregnating  the  fibers  them- 
selves. The  former  is  completely  impervious,  the  latter  partially.  The 
fibers  may  be  waterproofed  by  spraying  the  cloth  with  a  solution  of 
varnish  or  similar  substance;  it  may  be  done  in  the  field  by  meansof  an 
aluminium  acetate  solution.  Woolen  fabrics  may  be  treated  with  lanolin 
dissolved  in  benzene,  thus  replacing  the  fat  which  made  it  waterproof 
for  its  original  owner.  Waterproofed  fibers  are  intended  to  protect 
against  inclement  weather,  not  against  cold,  for  obviously  they  are  pervi- 
ous to  body  heat  and  partially  to  moisture.  On  the  other  hand,  rubber 
and  fur  retain  both  moisture  and  heat.  The  new  infantry  poncho  is  of 
waterproof  olive-drab  cotton,  substituted  for  the  former  heavier  one  of 
rubber  surfaced  cloth.  Slickers  for  mounted  troops  are  merely  longer 
ponchos  designed  to  cover  the  saddle  and  equipment. 

Leather  is  largely  <?onfined  for  military  purposes  to  trappings,  belts, 
shoes,  coats,  etc.  For  men  who  handle  heavy  guns,  however,  leather  gloves 
are  furnished.  Fur  is  used  almost  exclusively  for  mittens  and  caps,  both 
of  which  may  be  wool  lined  and  are  designed  solely  for  service  at  cold 
posts. 

The  total  weight  of  a  soldier's  uniform  varies  from  six  and.  one-half 
to  twelve  pounds,  depending  upon  the  climate.  The  styles,  colors, 
weights,  and  other  qualities  of  soldiers'  clothes  are  changing  continually. 

Headgear. — An  ideal  headdress  should  be  light  in  weight  and  color, 
well  ventilated,  flexible  enough  to  take  the  shape  of  the  head,  and  de- 
signed to  protect  both  the  neck  and  head  from  sun  and  cold ;  further,  it 
should  shield  the  eyes,  be  comfortable,  and  not  readily  dislodged.  Our 
new  service  hat,  the  "Montana  Peak,''  is  perhaps  the  best  adapted  of  all 
in  use,  although  it  has  certain  disadvantages.  The  pith  helmet  has  been 
found  by  actual  experience  as  well  as  experiment  to  be  better  adapted  than 
any  other  style  of  headdress  for  tropical  use.  For  cold  posts  fur  and  can- 
vas caps  with  ear  flaps  are  issued  to  our  troops.  Pressed  steel  helmets 
were  supplied  the  troops  engaged  in  trench  fighting  in  the  late  war. 
These  are  designed  to  protect  the  head  against  shrapnel  and  grenade 


1456  MILITAEY  HYGIENE 

fragmeiits.  Masks  designed  to  hold  chemicals  to  protect  against  the 
so-called  "gas  curtains"  were  used  abroad,  in  order  to  neutralize  chlorin 
and  bromin  fumes. 

Coats. — Coats  are  designed  to  fit  fairly  snugly.  The  service  coat 
should  have  five  inches  excess  across  the  chest.  The  roll  collar  and  lapel 
are  preferable  to  the  standing  collar,  for  the  hard,  rough  use  of  actual 
warfare.  The  former  leaning  toward  bizarre  designs  and  colors,  is  giv- 
ing way  to  the  practical  ideas  of  service,  utility  and  warmth.  Overcoats 
no  longer  have  a  hood;  mackinaws  are  furnished  for  service  in  Alaskan 
posts.  Ponchos  are  issued  to  foot  soldiers,  the  idea  being  borrowed  from 
Central  America,  where  they  are  much  in  use.  Slickers  are  regularly 
issued  to  mounted  troops. 

Leggings. — Leggings,  or  articles  serving  their  purpose,  are  of  many 
kinds  and  designs.  Some  armies,  as  the  German,  are  supplied  with  high- 
topped  boots,  which  serve  both  as  shoes  and  leggings.  Leggings  or  gaiters 
may  be  of  leather,  duck  or  woolen  strips,  arranged  so  as  to  protect  the 
entire  shin  or  only  the  lower  part.  The  ITnited  States  Army  legging  con- 
sists of  heavy  canvas  with  reinforced  straight  edges  with  a  lacing  on  the 
side  and  a  stirrup  strap  under  the  instep.  Putties  are  used,  but  have 
obvious  disadvantages. 

Gloves. — Gloves  are  designed  and  issued  in  many  materials  and 
styles.  Mention  has  been  made  of  leather  ones  provided  handlers  of  big 
guns.  Leather  gauntlets  are  also  issued  to  the  cavalry.  Fur  mittens, 
wool  lined,  are  provided  for  northern  posts. 

Undenv^ear. — From  the  standpoint  of  hygiene,  perhaps  the  most 
important  part  of  the  fighting  man's  dress  is  the  underwear.  It  is  sup- 
plied our  troops  in  merino,  light  and  heavy  wool.  An  apronlike  woolen 
abdominal  protector  is  recommended  for  those  in  whom  exposure  to  cold 
causes  diarrheal  disturbances,  but  its  use  has  not  been  regarded  favorably 
by  our  troops.  Underdrawers  are  furnished  full  length  to  protect  the 
lower  legs  against  dirt.  Socks  issued  to  United  States  troops  are  made 
of  cotton,  half-cotton,  and  wool,  the  light  woolen  ones  being  preferred. 
The  English  have  estimated  the  life  of  socks  similar  to  our  light  wool  as 
being  sixty  to  seventy  road  miles. 

Shoes. — While  it  has  long  been  known  that  proper  footgear  is  indis- 
pensable to  an  army,  it  is  only  within  recent  years  that  the  subject  has 
been  studied  scientifically.  Disability  from  poorly  fitting  shoes  is  found 
both  in  military  and  civil  life,  and  forms  a  large  percentage  of  those  who 
fall  out  during  the  first  few  days  of  maneuvers  or  the  march.  Some 
native  troops,  as,  for  example,  African  native  soldiery  or  our  Philippine 
Constabulary,  may  wear  no  shoes  at  all,  while,  on  the  other  hand,  the 
clumsy  high-topped  boots  of  the  Eussians  and  of  the  Germans  as  they 
entered  the  late  conflict  were  very  heavy.  Our  men  probably  have 
better  shoes,  better  shaped  and  better  fitted  than  those  of  any  other 


EQUIPMENT 


1457 


Fig.  181.  —  The 
Normal  Foot. 
Meyer's    line. 


nation.  A  board  of  officers  of  the  Ignited  States  Army  in  1912  made 
a  report  on  shoes  and  the  soldier^s  foot,  as  a  result  of  which  the  so-called 
Munson  composite  last  was  adopted.  The  recommendations  of  the  board 
were:  (1)  that  shoes  made  over  the  Board  last  be 
adopted;  (2)  careful  fitting,  personally  by  company 
officers;  (3)  full  series  of  sizes  carried  by  posts; 
(4)  frequent  inspection  of  feet  by  commanding  and 
medical  officers.  These  recommendations  were 
adopted  with  the  statement  that  "hereafter  any  un- 
due amount  of  injury  and  disability  from  shoes  will 
be  regarded  as  evidence  of  inefficiency  on  the  part 
of  the  officers  concerned  and  as  a  cause  for  investi- 
gation." 

In  persons  who  wear  ho  shoes,  the  axial  line 
of  the  big  toe,  if  continued,  will  pass  through 
the  center  of  the  heel  (Meyer's  line).  This  fact  forms  the  basis  of  the 
Munson  last.  A  foot  soldier's  pack  weighs  about  40  pounds,  and  with 
this  weight  his  feet  tend  to  flatten  and  spread  in  both  dimensions.  In 
fitting  them,  he  is  required  to  stand  and  support  a  40-pound  weight  while 
his  foot  measure  in  length  and  breadth  is  being  taken 
and  recorded.  Shoes  are  then  selected  from  the 
ninety  sizes  required  to  be  kept  in  all  posts.  The 
fit  should  be  verified  by  making  sure  that  there  is  a 
free  space  in  front  of. the  toes  and  sufficient  width. 
It  has  been  found  that  shoes  a  trifle  loose  will  cause 
little  inconvenience,  whereas  those  that  are  tight 
surely  lead  to  trouble.  A  figure-of-eight  strap  pass- 
ing under  the  arch  above  the  heel  and  crossing 
over  the  instep  tends  to  prevent  chafing  of  loose 
shoes  for  those  whose  foot  peculiarities  require  them. 
A  recruit's  foot,  fitted  in  the  manner  outlined 
above,  will  so  develop  as  a  result  of  military  life 
that  another  fitting  and  size  may  be  necessary  some 
months  later,  after  which  the  foot  ceases  to  spread. 
Munson  recommends  the  following  method  of 
breaking  shoes  in  quickly:  Have  the  men  stand 
in  water  for  a  few  minutes  so  that  the  lower 
parts  of  the  shoes  become  wet  and  pliable ;  next  have  the  men  walk 
on  level  ground  until  the  shoes  dry  on  their  feet.  Afterwards,  the  shoes 
may  be  waterproofed  by  rubljing  with  neat's-foot  oil.  The  disadvantage 
of  thorough  waterproofing  is  that  it  prevents  ventilation,  and  the  re- 
tained warmth  and  ])erspiration  have  a  tendency  to  soften  and  macerate 
the  skin.  Hence,  it  is  usually  l)etter  to  allow  the  feet  to  get  wet  occa- 
sionally. 


Fig.  182.  — Shape 
OF  U.  S.  Mili- 
tary Shoe.  Mey- 
er's line.  The 
dotted  line  shows 
slight  deviation 
outward  so  as  to 
fit  the  average 
foot  accustomed 
to  shoes. 


1458  MILITARY  HYGIENE 

The  Canteen,'. — The  canteen  should  be  scalded  inside  and  out  when 
new,  and  from  time  to  time  afterwards.  The  scalding  water  removes 
the  sizing  from  the  cloth  covering  of  a  new  canteen,  making  it  more 
absorbent.  To  cool  the  contents,  wet  the  outside  covering  and  hang  in 
the  breeze.  It  is  usually  best  to  fill  the  canteen  at  night.  The  men 
should  be  taught  to  conserve  the  supply  and  not  drink  too  much  water 
on  the  march.  The  man  who  empties  his  canteen  early  in  the  day  is 
likely  to  drink  from  unauthorized  sources  on  the  march.  The  habit  of 
indiscriminate  drinking  from  another  man's  canteen  should  be  dis- 
couraged. 

On  the  march,  water  is  carried  in  the  canteen  and  in  the  water  keg 
on  the  company  wagon.  A  water  wagon  is  furnished  as  a  part  of  the 
equipment  of  the  modern  army. 


DISEASES  OF  THE  SOLDIER 

The  diseases  of  the  soldier  do  not  differ  from  those  of  the  civil  popu- 
lation, but  military  conditions  favor  the  spread  of  many  infections. 
There  are  but  few  infections  peculiar  to  camp  and  field  life.  Most  of  the 
epidemics  of  camps  and  barracks  are  preventable.  In  former  days,  sol- 
diers and  sailors  suffered  severely  from  the  results  of  overcrowding  in 
unsanitary  camps  and  barracks,  which  favored  the  spread  of  all  com- 
municable infections,  especially  those  of  the  respiratory  tract,  the  intes- 
tinal tube  and  the  skin. 

The  most  frequent  diseases  of  soldiers  and  sailors  are  typhoid,  dysen- 
tery, diarrheal  diseases  and  other  gastro-intestinal  infections ;  pneumonia, 
tuberculosis,  influenza,  common  colds,  sore  throat,  and  other  inflamma- 
tions of  the  respiratory  tract;  measles,  mumps,  cerebrospinal  menin- 
gitis, scarlet  fever,  smallpox  and  other  infections.  At  times  the  army 
may  suffer  from  hookworm  disease,  especially  in  prison  camps  in  south- 
ern zones,  where  proper  disposal  of  feces  is  not  practiced.  Dengue, 
meningitis,  cholera,  plague  and  typhus  fever  may  occur  as  epidemic 
outbreaks  among  the  troops.  Improper  rations  may  lead  to  beriberi  or 
scurvy;  campaigning  in  hot  weather  will  result  in  a  number  of  heat 
prostrations  or  even  in  sunstroke.  Soldiers  and  sailors  are  also  apt  to  be 
troubled  with  lice,  fleas  and  ticks ;  skin  diseases  are  common  and  trouble- 
some. Conditions  affecting  the  feet  incident  to  marching  are  frequent 
and  important  (pages  1456  and  1463). 

All  the  preventable  diseases  above  mentioned  are  fully  treated  in 
other  portions  of  this  volume,  and  need  therefore  not  be  repeated  here, 
for  their  prevention  is  the  same  with  the  soldier  as  with  the  civilian. 
In  fact,  the  problem  of  preventing  these  infections  in  a  well-organized 
force  under  good  discipline  is  simpler  than  among  the  civil  population. 


RANITATIO.V  IN  OA^rP  AND  ON  MllE  MAKCIT       1150 

The  diseases  (hat  allVct  the  soldier  and  saih)r  arc  simply  a  rcneetion  of 
the  same  diseases  (hat  ])rt'vail  in  (he  ciNil  it(i[)iihiti(iii.  Sanitary  isohi- 
lion  to  <i:iiard  the  sailor  and  s(ddi('r  against  infection  is,  therefore,  of 
prime  im])or(an(e. 

The  diseases  (rnnsmi((i'd  mainly  ])y  contact  find  favorahlc  conditions 
for  spread  in  camps,  harracks,  iiiili(ary  j)risons,  and  on  hoard  shijis. 
Therefore,  one  of  the  first  indications  in  preventing  as  well  as  checking 
an  epidemic  is  to  scatter  the  command  in  many  small  sanitary  units  and 
over  as  wide  a  territory  as  practicahle.  ^feasles,  mumps,  scarlet  fever 
and  other  diseases  common  to  childhood  are  very  apt  to  hreak  out,  espe- 
cially in  camps  recruited  from  country  districts.  When  introduced,  these 
diseases  spread  like  wild  fire  among  the  susceptible. 

Mental  and  nervous  breakdowns  often  develop,  owing  to  the  strain 
and  unusual  conditions.  This  happens  in  persons  who  otherwise  might 
go  through  life  without  showing  signs  of  mental  derangement. 

"War  Gases. — The  most  important  members  of  the  group  of  lethal 
gases  are  chlorin,  phosgen  and  chlorpicrin.  These  substances  are  alike 
in  that  they  act  on  the  respiratory  tract,  producing  edema  and  conges- 
tion. Chlorin  acts  with  extreme  rapidity.  The  toxic  action  of  phosgen 
is  slower  probably  because,  to  produce  its  effects,  it  must  undergo 
chemical  change.  This  fact  has  earned  for  phosgen  tlie  name  of  having 
a  delayed  action.  Chlorpicrin  appears  to  stand  somewhere  between 
chlorin  and  phosgen,  both  in  regard  to  the  type  of  influence  provoked 
and  in  the  rate  of  production  of  intensive  edema. 


SANITATION  IN  CAMP  AND  ON  THE  MARCH 

PERSONAL  HYGIENE  OF  TEE  SOLDIER 

The  March. — Troops  marching  in  close  formation  suffer  from  so- 
called  ''crowd  poisoning" — ^believed  to  be  due  mainly  to  heat  and  hu- 
midity, aggravated  by  dust  (see  page  904).  It  is  now  customary  in 
nearly  all  armies  to  present  as  wide  a  front  as  possible  while  on  the 
road;  usually  two  columns  march  along  the  sides  of  the  road,  leaving  a 
ventilating  aisle  down  the  middle.  Much  of  the  fatigue  and  hardships 
of  marching  have  in  recent  times  been  relieved  by  the  use  of  auto  trucks 
and  troop  trains. 

The  "route  step"  is  used  on  the  march — that  is,  each  man  uses  the 
step  to  which  he  is  accustomed,  but  distance  in  rank  must  be  preserved. 
For  ordinary  marching,  the  step,  according  to  the  United  States  Eegu- 
lations,  is  at  the  rate  of  90  per  minute,  each  30  inches  long,  or  2.5  miles 
per  hour.  Quick  time  moves  at  the  rate  of  120  such  steps,  or  3.4  miles 
per  hour;  doiibU  time  is  180  steps,  each  35  inches  long,  or  G  miles  per 


14G0  MILITAEY  HYGIENE 

hour.  The  figures  for  other  countries  are  in  general  similar  to  our 
own.  The  rate  of  march  is  influenced  by  the  character  of  the  roads 
or  ground  covered,  as  well  as  by  head  winds,  storms,  great  heat  or  snow, 
sizes  of  command,  the  burden  carried,  the  discipline,  character  of  the 
troops,  etc.   - 

Marching  at  night,  save  for  tactical  reasons,  and  marching  in  the 
hottest  part  of  the  day  should  be  avoided.  The  command  should  have  a 
light  breakfast  before  starting.  Halts  should  be  arranged  by  hours 
rather  than  by  bugle,  since  the  difl^erent  rates  of  travel  frequently  allow 
the  head  of  the  column  to  finish  its  rest  before  the  rear  has  caught  up. 
The  head  of  the  column  should  be  taken  in  turn  by  the  various  com- 
panies. The  first  halt  usually  occurs  during  the  last  fifteen  minutes  of 
the  first  hour,  to  give  the  men  a  chance  to  relieve  themselves,  readjust 
clothing,  cinches,  etc.  All  other  halts  during  the  day  are  usually  about 
ten  minutes  for  infantry,  five  minutes  for  cavalry,  and  five  to  ten  minutes 
for  artillery,  except  the  noon  rest,  which  should  be  at  least  an  hour. 
During  halts,  the  men  should  be  encouraged  to  lie  at  full  length  on  the 
ground,  utilizing  such  shelter  as  the  place  affords,  and  in  the  case  of 
foot  soldiers,  to  knead  the  buttocks  and  thighs  to  assist  in  muscular 
recuperation. 

When  a  "halt  order"  is  given,  proper  officers  of  the  quartermaster's 
and  medical  corps  should  accompany  the  officer  detailed  to  go  ahead  to 
select  a  camp  site,  procure  supplies  and  forage,  investigate  the  water, 
etc.  The  medical  officer  carries  his  notebook,  in  which  is  recorded 
the  choice  of  camp  sites,  with  a  sanitary  survey  embracing  observed 
data  of  importance,  as  well  as  all  other  items  of  medical  interest  from 
day  to  day.  Seasoned  troops  can  cover  20  miles  day  after  day,  with 
one  day's  rest  a  week.  Over  20  miles  a  day  for  infantry  is  regarded  as 
a  forced  march. 

The  character  of  the  march  is  a  factor  which  must  be  taken  into 
consideration.  It  must  not  be  imprudently  designed,  in  length,  or  de- 
tail, so  that  the  strength  and  spirits  of  the  soldier  will  break  down;  in 
this  case,  the  more  he  marches,  and  the  nearer  the  enemy  he  gets,  the 
less  fit  will  he  be  for  the  encounter.  In  a  hostile  country,  it  is  always 
advisable  to  keep  troops  fresh  and  make  only  short  marches,  for  fatigue 
and  exhaustion  are  as  inimical  to  courage  and  initiative  of  action  as 
they  are  to  physical  endurance.  Military  restrictions  of  an  unnecessary 
nature  should  be  avoided  as  far  as  possible,  since  in  marching  at  ease  the 
ordinary  journey  is  relieved  of  much  of  its  harassing  character  and  be- 
comes a  salutary  and  stimulating  exercise.  The  movements  of  the  in- 
dividual soldier  should  not  be  restrained  by  precise  military  rules,  but 
should  occur  more  easily  in  the  better  maintenance  of  equilibrium. 

The  march  should  be  considered  as  labor  performed  in  addition  to 
the  daily  routine  of  camp  or  garrison  and  not  at  all  as  the  only  drain 


SANITATION  IN  CAMT  AXl)  ON   TIIK   MAIfCIl        1  Icl 

iipon  the  energies  of  the  soldier.  According  to  Notter  and  Firtli,  Cous- 
tan  and  others,  the  average  daily  work  of  the  ordinary  lahorer  is  from 
350  to  400  foot-tons,  or  ahout  !/(>  or  1/7  the  force  theoretically  ohtain- 
able  from  the  food  taken  by  the  individual.  For  a  soldier  weighing 
IGO  pounds,  a  march  of  10  miles  over  flat  country  amounts  to  250.30 
foot-tons,  or  what  woidd  be  a  rather  small  daily  expenditure  of  energy 
for  the  civilian  laborer.  On  the  other  hand,  a  march  of  20  miles  with 
a  weight  of  60  pounds  is  alone  a  very  hard  day's  work  for  the  soldier, 
\vithout  taking  into  consideration  the  labor  necessarily  involved  in  mak- 
ing and  breaking  camp,  and  the  other  laborious  duties  incident  to  the 
field,  and  such  severe  labor  could  not  long  be  continued  without  injurious 
effects.  If  the  weight  be  badly  adjusted  or  the  ground  not  level,  the 
expenditure  of  energy  becomes  greater,  as  is  also  the  case  if  it  be 
done  in  a  shorter  time.  Velocity  is  also  an  important  factor  in  deter- 
mining the  strain  on  heart  and  lungs.  As  a  matter  of  fact,  however, 
if  very  rapid  or  very  long  marches  are  required,  the  troops  are  usually 
sent  out  in  light  marching  order,  with  the  equipment  reduced  to  the 
minimum ;  or  they  may  later  bring  the  labor  within  their  powers  of 
endurance  by  discarding  portions  of  their  equipment  en  route. 

Forced  Marches. — Forced  marches  are,  fortunately,  but  rarely  re- 
quired. Anything  above  18  or  20  miles  is  practically  a  forced  march, 
unless  the  conditions  of  the  w^eather,  temperature  and  terrain  are  ex- 
tremely favorable.  In  Mexico,  a  French  column  is  said  to  have  traveled 
30  miles  in  5  hours  at  night,  rested  1  hour,  and  then  marched  9  miles 
further.  According  to  Thomas,  the  grenadiers  of  Oudinot,  in  1805, 
pursued  the  corps  of  Werneck  for  three  consecutive  days,  the  daily 
marches  being  30,  40  and  50  miles,  respectively. 

Three  regiments  of  British  infantry,  in  July,  1809,  marched  62 
miles  in  26  consecutive  hours,  carrying  arms,  ammunition  and  packs — in 
all,  a  weight  of  betw^een  50  and  60  pounds.  This  march  implied  an 
expenditure  of  energy  equal  to  about  600  foot-tons.  One  of  these  same 
regiments,  during  the  Indian  mutiny,  marched  42  miles  in  20  hours, 
and  on  the  following  morning  marched  10  miles  and"  engaged  the  muti- 
neers. But  marches  of  such  character  may  be  said  practically  to  exceed 
the  powers  of  any  large  military  force  under  normal  conditions. 

In  a  forced  march,  after  four  hours,  the  column  should  be  halted 
for  an  hour,  during  which  time  the  men  should,  if  water  be  at  hand, 
and  the  weather  permit,  wash  the  face,  hands,  neck  and  feet;  but  dis- 
crimination as  to  the  duration  of  the  halt  must  be  employed  since  the 
men  stiffen  up  if  prolonged  rests  are  permitted.  A  light  lunch  should 
preferably  be  issued  at  such  a  halt.  Following  a  forced  march  a  rest 
of  a  day  will  usually  be  necessary.  Hence  such  a  special  effort,  besides 
impairing  the  eflficiency  of  the  force,  actually  gains  nothing  in  distance 
on  a  long  journey. 


1463  MILITAEY  HYGIENE 

One  of  the  most  notable  instances  of  long  distance  marching  in  a 
few  hours  in  recent  time  is  that  of  the  City  of  London  Imperial  Vol- 
unteers who,  in  South  Africa,  in  August,  1900,  covered  30  miles  in  10 
hours  hoping,  according  to  a  dispatch  of  Lord  Eoherts,  to  prevent  Gen- 
eral DeWet  from  crossing  the  Krugersdorp-Potchef stroom  railway.  The 
celebrated  march  of  Lord  Eoberts  from  Kabul  to  Kandahar,  in  1880,  over 
very  rough  country,  was  performed  in  23  days.  The  longest  day's 
marches  were  20  and  21  miles,  and  the  average  distance  covered  was 
nearly  17  miles. 

Among  the  best  known  long  marches  are  several  by  United  States 
troops,  who  hold  the  record  for  long  distance  continuous  marching  from 
Fort  Leavenworth,  Kansas,  to  a  point  in  California,  a  distance  of  1,800 
miles,  in  190  days,  28  of  which  were  given  up  to  resting,  so  that  in  162 
days  of  actual  marching,  an  average  distance  of  a  little  more  than  11 
miles  was  traversed.  In  I860,  a  portion  of  another  regiment  went  from 
Camp  Floyd,  Utah,  to  Fort  Buchanan,  New  Mexico,  a  distance  of  1,000 
miles,  in  140  days. 

In  the  Franco-Prussian  War  of  1870,  a  company  of  French  chasseurs 
marched,  in  very  inclement  weather,  over  an  exceedingly  difficult  road, 
for  41  hours,  with  one  rest  of  an  hour,  another  of  21/^  hours,  and  halts 
of  8  minutes  in  each  of  the  marching  hours.  The  exact  distance  marched 
is  not  known,  but  the  instance  is  cited  as  one  of  exceptional  endurance 
and  hardship. 

Discipline  and  Sanitation, — The  two  essentials  of  good  marching 
are  discipline  and  sanitation.  Troopers  should  not  be  allowed  to  leave 
the  column  without  permission.  Those  who  fall  out,  or  desire  to,  should 
be  examined  by  a  medical  officer  and  a  sympathetic  watch  kept  to  prevent 
malingering.  Places  for  latrines  at  halts  are  designated  where  the  shal- 
low ^^straddle  trenches"  are  required  to  be  used,  covered  with  earth  and 
marked  on  leaving.  Water  for  daily  use  should  be  boiled,  filtered  or 
treated  with  "bleach"  the  night  before.  In  the  tropics  each  man  should 
be  supplied  two  canteens,  on  account  of  increased  loss  through  per- 
spiration. Soldiers  should  be  encouraged  to  drink  as  little  water  as 
possible  while  on  the  road.  A  seasoned  soldier  conserves  the  supply  in 
his  water  bottle.  The  men  should  be  instructed  in  the  advantages  of 
using  a  little  water  as  a  mouth-wash,  followed  by  a  few  swallows;  also 
in  the  use  of  pebbles  and  chewing  grass  to  prevent  the  sensation  of  thirst. 
The  canteen  should  be  filled  only  at  authorized  places,  with  safe  water. 

Bathing  is  very  important,  especially  for  foot  soldiers.  All  troops 
should  wash  the  face,  neck  and  feet  as  well  as  the  genital  and  axillary 
regions  with  a  damp  towel  and  soap,  each  morning,  and  evening.  Daily 
baths  are  advisable  in  permanent  camps;  tubs  and  showers  can  be  ar- 
ranged with  pails  and  makeshifts  with  very  little  trouble  and  are  much 
appreciated  by  the  men. 


SANITATION  IN  CAMT  AND  ().\   'I'lIK   MAI.'Cll         1  Hio 

An  army  litri-ally  iiianlu's  on  ils  tV<'t.  as  well  as  "on  its  Ix'lly"';  there- 
fore, the  care  of  the  feet  should  he  a  matter  of  gravest  concern  to  officers 
and  men.  For  slioos  and  their  selection  see  page  145(5.  Regulations 
require  that  foot  soldiers  bathe  the  feet  daily  at  the  end  of  the  march 
in  cold  water,  ])iit  only  long  enougli  to  cleanse  the  skin  and  set  up  an 
invigorating  reaction.  Clean  socks  should  be  donned  daily  and  those 
removed  washed  out  to  dry  over  night.  Extra  socks  are  carried  as  part 
of  every  man's  ('(luijJnHMit.  If  possible,  the  shoes  should  be  changed 
every  few  days  for  the  extra  pair  in  the  wagon  train.  If  rul)bing  or 
creases  have  been  felt,  the  socks  should  be  turned  inside  out  or  changed 
to  the  other  foot  during  the  halts.  If  blisters  or  excoriations  occur  the 
serum  may  be  squeezed  out  and  the  area  protected  with  adhesive  plaster. 
Abraded  areas  may  be  greased.  As  a  rule,  practice  marches  will  have 
been  given  raw  troops  to  toughen  the  feet,  which  may  be  fortified  by  a 
daily  soaking  in  an  alum  bath  or  in  dilute  alcohol.  Often,  however, 
foot  troubles  will  arise  in  experienced  troops;  when  this  happens,  they 
should  be  treated  as  above  outlined.  Sometimes  the  feet  are  soaped  in 
the  morning  to  lessen  friction.  A  dusting  powder  composed  of  talcum 
87  per  cent.,  starch  10  per  cent.,  and  salicylic  acid  3  per  cent,  is  supplied 
and  may  l)e  shaken  into  the  socks  and  shoes.  The  use  of  a  dusting 
powder  is  usually  preferred  to  that  of  other  expedients.  In  some  coun- 
tries socks,  which  are  not  issued  to  the  troops,  are  substituted  wholly  by 
grease,  or  by  bandages,  or  strips  wound  around  the  feet,  either  greased, 
dry  or  dusted  with  powder.  The  men  should  be  taught  to  cut  tlieir  toe 
nails  across  squarely,  as  this  tends  to  prevent  ingrown  toe  nails  and  other 
troubles. 

The  care  of  the  teeth  is  important.  The  soldier  should  be  required 
to  give  them  daily  attention  with  brush  and  powder. 

Wbile  in  camp  the  soldier  must  look  to  his  own  laundry.  If  a  stream 
is  not  available  the  clothes  may  be  boiled  in  camp.  Only  within  recent 
years  have  places  for  laundering  been  provided  in  garrisons.  Before 
1908,  our  soldiers  were  required  to  have  their  laundry  done  outside  of 
the  post,  or  do  it  themselves — a  measure  which  was  anything  but  sat- 
isfactory. 

Moving  columns  bury  or  bum  their  excreta  and  garbage.  In 
camp  each  company  has  its  own  latrines  for  excreta  and  garbage, 
sometimes  two  of  the  former,  which  should  be  covered  and  marked  on 
leaving. 

The  general  plan  of  a  camp  is  sho-vni  in  Fig.  183.  The  kitchens 
are  placed  as  far  as  possible  from  the  latrines,  and  the  latrines  are  placed 
at  least  50  yards  from  the  men. 

Sanitary  Police. — Each  company  commander  in  turn  is  "officer  of 
the  day,'^  and  as  such  is  responsible  for  camp  sanitation.  The  effective- 
ness with  which  policing  is  done  depends  largely  on  discipline.     The 


1464  MILITARY  HYGIENE 

officer  of  the  day  and  his  detail  look  aft^r  tlie  proper  use  of  latrines, 
the  proper  care  of  night  nrine  tubs  and  their  lanterns,  their  proper 
cleaning  and  storage  during  the  day,  the  proper  disposal  of  all  refuse, 
paper,  and  in  general  the  cleanliness  and.  orderliness  of  the  camp.  It 
is  evidence  of  poor  discipline  as  well  as  a  danger  and  disgrace  when  a 
camp  is  fringed,  with  fecal  deposits  and  trash.  The  sanitary  inspection 
should  be  thorough  and.  complete.  The  surgeon  makes  a  daily  inspection 
of  the  camp,  usually  at  9  a.  m.,  accompanied  by  the  camp  sanitary  police. 
Often  it  becomes  advisable  to  have  the  entire  sanitary  police  under  the 
control  of  the  chief  surgeon  in  order  to  abolish  nuisances. 

Sick  call  is  usually  sounded  after  arriving  in  camps,  and  in  fixed 
camps  usually  at  5  p.  m. 

In  permanent  camps,  manure  produced  by  the  many  animals  should 
be  disposed  of  so  as  not  to  breed  flies  or  be  a  nuisance.  The  picket 
lines  should  be  thoroughly  raked  at  frequent  intervals,  and  the  manure 
removed  daily  to  a  spot  several  miles  from  camp.  It  should  then  be 
burned  with  oil  or  disposed  of  to  farmers.  The  picket  line  should  be 
thoroughly  burned  over  with  straw  and  coal  oil  to  diminish  odors  and 
prevent  fly  breeding. 

Field  bakeries  and  eating  places  should  be  screened  and  flies  com- 
bated with  traps,  poisons,  sticky  paper,  etc. 

The  medical  officer  should  be  authorized  to  issue  orders  in  the  name 
of  the  commanding  officer  for  the  immediate  remedying  of  all  sanitary 
defects.  He  should  then  be  held  accountable  for  results.  The  mere 
issuance  of  orders  is  not  sufficient;  success  in  camp  sanitation  depends 
upon  enthusiasm, -cooperation,  and  incessant  vigilance. 

Transportation. — Prior  to  embarking  on  transports,  all  troops  should 
be  carefully  examined  to  remove  those  suffering  from  communicable 
diseases,  and  to  eliminate  any  who  seem  unfit  for  foreign  service.  All 
transports  should  have  an  isolation  hospital  for  cases  of  infection  that 
may  break  out. 

In  moving  troops  by  rail,  certain  sanitary  precautions  need  to  be 
observed.  Troop  trains  travel  slowly,  because  the  animals  must  be  un- 
loaded for  exercise  at  intervals,  and  for  the  further  reason  that  freight 
cars  are  used  for  baggage.  Three  enlisted  men  occupy  each  double  seat 
or  section  of  a  sleeper.  This  allows  the  normal  accommodation  of  one 
person  for  storage  of  the  equipment  of  the  three  soldiers.  Inspections 
of  the  train  must  be  made  at  frequent  intervals  to  insure  cleanliness, 
particularly  all  toilet  rooms.  A  regiment  usually  travels  in  three  train 
sections,  one  for  each  battalion.  The  wagons,  animals,  forage,  ration, 
and  baggage  of  the  battalion  go  with  it  in  the  section,  so  that  the  troops 
are  ready  for  independent  movement  promptly  upon  entraining.  The 
sanitary  personnel  is  divided  among  each,  and  if  possible  a  medical 
officer  should  accompany  each  train. 


CAMr  SITES  1465 


CAMP  SITES 

Sanitary  prfeference,  in  the  selection  of  the  camp  site,  must  often 
yield  to  military  necessity.  The  proper  location  of  the  camp  is  a  matter 
of  the  greatest  importance  in  maintaining  the  health  and  efficiency  of 
troops,  and  demands  intelligent  and  careful  consideration.  The  site 
should  be  chosen  with  a  view  to  the  convenience  of  the  command,  should 
permit  of  ready  internal  communication,  and  should  be  located,  if  at 
all  of  a  permanent  character,  near  a  road  practicable  for  wheeled  vehicles. 
Possible  meteorological  conditions  should  always  be  taken  into  considera- 
tion, and  the  locality  should  never  be  such  as  could  receive  the  over- 
flow of  a  watercourse  or  the  surface  drainage  from  high  ground  during 
rainstorms. 

The  desiderata  in  the  selection  of  the  camp  site,  from  the  standpoint 
of  the  line  officer,  are  wood,  water  and  grass — in  abundance  and  of  good 
quality.  To  these  the  sanitary  officer  will  add  dryness  of  soil  and  sur- 
roundings, elevation  of  site  and  protection  from  winds.  Xo  sanitary 
precautions  can  fully  atone  for  the  selection  of  an  unhealthful  camp 
site,  even  though  they  will  do  much  toward  the  diminution  of  sickness, 
and  hence  the  prompt  reestablishment  of  a  badly  located  camp  in  a 
more  desirable  locality  is  imperative.  On  the  other  hand,  the  best  of 
natural  sites  will  soon  be  defiled  by  lack  of  sanitary  care,  often  resulting 
from  inefficient  policing.  With  the  observance  of  proper  sanitary  regu- 
lations and  a  careful  police,  an  originally  good  camping  ground  will  con- 
tinue to  be  healthful  for  a  proportionately  longer  time. 

Munson  formulated  the  maxim  that  '^'if  excreta  are  not  moved  or 
destroyed,  the  soldier  must  move,  or  he  will  be  destroyed.'^  In  the  un- 
sanitary ages,  a  moving  command  had  better  health  than  troops  in  per- 
manent camps — because  they  left  their  excreta  behind. 

An  abandoned  camp  site  should  never  be  utilized  by  another  com- 
mand, for  the  slightly  greater  labor  involved  in  the  clearing  or  arrange- 
ment of  a  new  camp  area  is  more  than  counterbalanced  by  the  increased 
safety  of  the  troops. 

Topography. — While  many  factors  combine  to  determine  the  health- 
fulness  of  localities,  there  are  certain  physical  features  of  the  surface 
of  the  earth,  which,  as  shown  by  experience,  may  be  accepted  as  fair  in- 
dications of  the  salubrity  of  the  location  in  which  they  occur.  '  High 
ground  should  always  be  selected  for  the  camp  site ;  since  not  only  is 
the  surface  drainage  Ijetter.  but  exposure  to  air  currents,  as  well  as  les- 
sened atmospheric  pressure,  increases  the  rapidity  of  evaporation.  Camps 
should  never  be  located  in  ravines  or  the  dry  beds  of  water  courses. 
Xarrow,  circumscribed  valleys  and  punch-bowl  depressions  are,  during 
warm  weather,  excessively  hot  during  the  night  as  well  as  by  day.    Ex- 


1466 


MILITARY  HYGIENE 


posed  ridges  should  be  avoided  in  cool  weather  since  they  are  con- 
stantly swept  by  chilling  winds^  but  for  that  very  reason  they  afford  an 
excellent  location  for  summer  encampments. 

An  abundance  of  good  water  is  of  the  first  importance  for  troops, 


^9.8  Acres] 


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Fig.  183. — Camp  of  a  Regiment  of  Infantry,  War  Strength.     (Field  Service 
Regulations,  U.   S.   A.,   1914.) 


and  encampment  in  its  vicinity  is  a  necessity  for  a  marching  command, 
irrespective  of  the  nature  of  the  camp  site  and  a  possible  exposure  to 
malarial  infection.  Still,  proximity  to  bodies  of  water  does  not  nec- 
essarily render  a  locality  unhealthful,  and  the  bank  of  a  lake  or  river, 
if  not  marshy,  may  make  an  excellent  camp  site.    A  guard  should  be  set 


CAMP  SITES  1407 

over  the  water  supply  to  ])i'ev('iit  its  contamination  and  improper  use. 
All  water  si;pplies  about  the  camp  considered  Itjul  or  doiihll'id  should 
be  labeled  and  a  little  methylene  blue  thro\yn  into  them.  The  soil 
should  be  porous  and  permeable,  the  ground  water  not  Jiearer  than  six 
to  eight  feet  from  (be  surface. 

Newly  ploughed  ground  is  not  desirable  for  camping  purposes,  al- 
though a  site  which  has  long  been  umler  cultivation  is  usually  healthful. 
All  soil  upon  wliicli  the  covering  of  turf  has  l)een  destroyed  is  dusty  in 
dry  weatlier.  Dusty  camp  sites  are  a  nuisance  and  a  menace  to  health. 
Camp  grounds  should  l)e  large  enough  to  accommodate  the  command 
without  crowding.  The  different  organizations  should  be  separated  as 
far  as  military  considerations  and  the  availaljle  land  permit,  so  as  to 
discourage  the  spread  of  communicable  disease,  which  is  always  to  he 
guarded  against.  A  brigade  of  4,000  to  5,000  men  is  as  large  a  force 
as  it  is  desirable  to  put  into  one  camp. 

Tentag^e. — Tents  are  of  many  shapes  and  sizes^  according  to  the.  use 
for  which  they  are  intended.  The  tent  now  most  in  favor  with  our  army 
for  commissioned  officers  is  an  oblong  A-wall  tent.  For  the  men  the 
pyramidal  tent  accommodates  8  men,  or  in  emergency  12  men.  It  has 
arrangements  for  a  tent  stove  and  top  ventilation.  Modified  designs  are 
furnished  for  the  mess  tents,  hospital  tents,  and  also  for  use  in  the 
tropics.  Tent  flies  make  the  tent  cooler  in  summer  and  protect  against 
rain  and  storms. 

In  general,  the  requirements  of  a  good  military  tent  are  that  it 
should  not  be  of  too  great  weight,  should  be  quickly  and  securely 
pitched,  and  capable  of  being  promptly  taken  down  and  packed  for  trans- 
portation. It  should  not  be  too  large,  yet,  at  the  same  time,  must  be 
of  sufficient  size  to  afford  adequate  air  space;  it  should  be  durable, 
easily  ventilated  and  aired,  and  possess  stability  in  high  winds.  It 
should  thoroughly  protect  the  inmates  from  the  inclemencies  of  the 
weather,  and  should  be  so  shaped  as  to  make  all  portions  of  the  inclosed 
area  of  practical  availability. 

The  material  of  which  tents  are  made  for  the  military  service  of  the 
United  States  is  8,  10,  and  12  ounce  cotton  duck.  This  is  less  costly 
than  canvas,  and  is  also  less  permeable  to  water  and  less  liable  to  shrink 
in  the  presence  of  moisture.  Linen  tents,  used  in  times  past,  have  failed 
to  give  satisfaction.  In  European  armies,  however,  hempen  or  linen 
canvas  is  usually  preferred.  In  the  German  and  other  foreign  services 
the  material  used  for  shelter  is  often  artificially  rendered  waterproof, 
usually  by  treatment  with  acetate  of  aluminium. 

The  color  of  the  10  and  15  ounce  duck  tentage  is  of  light  drab  or 
dusty  brown,  the  glare  of  bright  sunlight  being  thus  greatly  reduced 
and  rendered  much  less  trying  to  the  eyes  than  in  tents  made  of  white 
canvas.     Tents  should  be  ditched.     It  is  important  to  air  and  sun  the 


1468  MILTTATJY  TTYnTE>^"E 

tents  daily  by  raising  the  walls;  it  is  also  useful  to  move  them  a  few  feet 
to  a  new  site  so  that  the  sunshine  may  dry  and  purify  the  old  site;  it  is 
desirable  while  on  the  march  to  avoid  recently  used  sites,  since  old 
latrines  may  be  opened  up. 

In  all  armies  the  tent  space  afforded  each  man  is  very  limited,  and 
in  our  service  the  official  tentage  is  not  sufficient  to  meet  the  demands 
of  hygiene.  Hence  it  is  fortunate  that  about  ^  of  the  authorized  oc- 
cupants of  a  tent  are,  in  practice,  constantly  absent.  In  France,  the 
tent  space  is  calculated  at  the  rate  of  11  square  feet  for  each  foot  soldier 
and  28  square  feet  for  each  cavalryman.  In  our  army,  the  allowance  has 
varied  with  the  tent  employed,  as  well  as  with  the  conditions  of  climate 
and  service.  The  United  States  infantryman,  in  the  common  wall  tent, 
is  entitled  to  17  square  feet  upon  which  to  dispose  his  person  and 
equipment.  Ground  and  air  space  being  equal,  the  use  of  small  tents 
is  preferable  to  the  employment  of  larger  canvas;  since,  by. the  former, 
the  danger  of  "crowd-poisoning"  is  much  diminished  by  scattering  the 
men,  in  smaller  groups,  more  equally-  over  the  company  area.  Canvas 
tents  are  fairly  permeable  to  air,  except  when  wet,  when  ventilation 
becomes  extremely  faulty  unless  inlets  and  outlets  are  opened. 

C(we  of  Tents. — Tents  should  be  ditched  at  once  on  pitching,  else 
the  tioor  may  become  flooded  and  bedding  wet  without  a  chance  of  dry- 
ing for  several  days.  The  groimd  covered  by  the  tent  should  be  aired 
daily  and  the  walls  raised  to  let  in  the  sun.  In  a  permanent  camp, 
tents  are  usually  moved  a  short  distance  once  a  week,  to  a  new  site. 
Every  day  the  bed  sacks  and  blankets  should  be  aired  on  the  guy  ropes 
and  not  on  the  ground.  To  insure  ventilation,  the  tent  door  should  not 
be  closed  entirely  at  night;  canvas  made. damp  by  the  dew  at  night  is 
almost  air-tight,  and  will  interfere  with  ventilation. 

Temporary  camps  are  those  designed  for  use  over  one  night,  or  at 
most  a  short  time.  Permanent  camps  are  used  for  ten  days  or  more,  A 
bivouac,  or  camp  without  shelter,  diminishes  the  physical  efficiency  of 
troops,  except  for  a  few  nights  in  fine  weather.  The  sheltered  tent 
is  the  only  protection  for  soldiers  on  the  march  in  campaign.  Each 
soldier  then  carries  a  piece  of  canvas,  a  pole,  and  pins,  which,  when 
joined  to  a  corresponding  piece  and  pole  from  another  soldier,  makes  an 
A-shaped  tent,  84  inches  long  and  64  inches  wide,  sufficient  for  two 
men.  One  poncho  is  laid  on  the  ground,  and  the  other  poncho  and 
blankets  are  used  for  covers. 

Latrines  are  placed  on  opposite  sides  of  the  camp  from  company 
kitchens,  at  a  minimum  distance  of  50  yards  from  the  company''  tents.'^ 

Mess,  store  tents,  and  kitchen  pits  are  located  near  the  officers'  line, 
and  about  20  yards  away.  .  Hence,  the  mess  tents  and  kitchen  pits  are 
at  the  opposite  extremes  of  the  encampment  from  the  latrines. 

^Appendix  I,     Field  Service  Eegulations,  U.  S.  A.,  1914,  p.  173. 


SANITATION  OF  BAK'h'ACKS  AM)  ('AMI'S  14G9 


SANITATION  OF  BARRACKS  AND  CAMPS 

Sanitation  of  barracks  and  permanent  camps  deals  with  sites,  build- 
ings, ventilation,  lighting,  heating  and  many  other  factors  which  have 
been  discussed  in  other  ])ages  of  this  book.  A  camp  or  permanent  garri- 
son is  a  small  compressed  city,  with  a  i)cciiliar  population  constitution, 
consisting  mostly  of  young  adult  males  selected  on  account  of  health  and 
])iiysical  fitness.  Hence,  a  permanent  army  post  should  have  an  excep- 
tional health  record.  The  main  factor  to  guard  against  is  overcrowding. 
The  principles  of  camp,  post  and  barrack  sanitation  are  the  same  as  for 
other  habitations. 

Permanent  garrisons  should  have  complete  water  and  sewage  sys- 
tems, either  independent  or  connected  with  the  neighboring  city.  Gar- 
bage and  wastes  are  either  burned  or  disposed  of  by  the  city  authorities. 
Crude  coal  oil  is  used  more  and  more  for  burning  wastes,  as  well  as  for 
mosquito  and   vermin  destruction. 

Quarters  and  grounds  must  be  kept  clean  and  orderly  at  all  times. 
This  requires  military  policing.  Careful  watchfulness  must  be  kept  over 
the  guardhouse,  kitchen,  mess  halls,  latrines,  storage  rooms,  basements, 
picket  lines,  stables  and  other  places  to  keep  them  from  becoming  dirty 
or  infested  with  vermin. 

Perhaps  the  most  important  room  in  the  barracks  is  the  general 
sleeping  room,  or  squad  room,  as  it  is  known.  In  this  the  soldier  spends 
at  least  one-third  of  his  time.  Most  of  our  barracks  are  now  built  to 
provide  a  floor  space  of  60  square  feet  and  720  cubic  feet  of  air  space 
per  man.  Foreign  allowances  are  less.  Thus,  in  Australia,  it  is  540 
cubic  feet;  in  Germany,  560  for  cavalry,  and  450  for  infantry;  English 
home  station  standards  are  500  cubic  feet. 

There  are  three  other  buildings  on  a  military  reservation  in  which 
the  sanitary  officer  is  intimately  concerned;  namely,  the  hospital,  the 
guardhouse,  and  the  stable,  also  the  kitchen,  stores,  latrines,  etc.  A 
regimental  post  with  a  population  of  about  1.200  persons  has  a  hospital 
with  a  capacity  of  about  36  beds.  Some  of  the  things  that  the  sanitary 
officer  should  inspect  are  the  disposal  of  wastes,  dust,  cleaning  of  walks, 
elimination  of  weeds,  privies  and  dumps,  and  inspection  of  the  guard- 
house, supervision  of  the  mess  and  bakery,  as  well  as  of  the  hospital  and 
the  general  health  of  the  command. 

The  regulations  prescribe  bi-monthly  examination  for  venereal  dis- 
eases, and  special  reports  of  any  outbreak  of  disease  or  other  unusual 
incident  likely  to  affect  the  health  of  the  command.  If  an  epidemic 
occurs  he  must  notify  the  commanding  officer  in  writing  and  forward 
one  copy  to  the  Surgeon  General  and  another  to  the  corps  area  or  de- 
partment surgeon.    The  local  health  authorities  should  also  be  notified. 


1470 


MILITAEY  HYGIENE 


Progress  reports  of  the  epidemic  are  included  in  the  monthly  sanitary 
report,  which  is  made  out  in  duplicate.  The  original  copy,  signed  by 
the  commanding  officer,  finally  rests  in  the  Surgeon  General's  office,  the 
duplicate  remaining  on  file  as  part  of  the  medical  history  of  the  post. 

Water.— ^Drinking  water  for  the  soldier  needs  the  same  supervision 
and  purification  as  that  for  the  civilian  (see  Chapter  on  Water).  Per- 
manent camps  have  a  system  of  waterworks  corresponding  to  towns. 


"&>• 


Fig.    184. — Ishiji   Filter    (Japanese  Model).      (Reefer's   "Military  Hygiene," 

W.  B.  Saunders  Co.) 


Supplies  for  armies  on  the  march  and  temporary  encampments  some- 
times present  unusual  difficulties. 

A  soldier  needs  at  least  three  quarts  daily  for  drinking  and  cooking, 
and  another  three  quarts  for  washing.  These  are  minimum  amounts. 
This  must  be  increased  by  one-third  or  one-half  in  the  tropics.  In  per- 
manent garrisons  at  least  thirty  gallons  per  capita  per  day  should  be 
provided.  Ten  gallons  of  water  per  capita  per  day  without  sewers  pre- 
sents a  serious  problem  in  disposal. 

While  on  the  march  it  is  important  that  a  medical  officer,  well  in 
the  van,  make  a  sanitary  survey  of  all  available  water  supplies,  which 
may  be  supplemented  by  a  few  simple  field  tests.  All  wells,  springs, 
streams,  etc.,  should  be  plainly  labeled  before  the  command  arrives. 
When  a  stream  is  reached  it  is  usually  crossed,  for  tactical  reasons,  if  a 


SAXITATIOX  OF  BAKRACKS  AND  CAMPS 


1471 


halt  is  desired  at  tliat  pdint.  When  the  encaiiipinciit  is  on  the  ))ank  of  a 
stream  it  should  at  once  be  polieed  in  sueii  a  way  that  water  lor  drinking 
and  cooking  is  drawn  farthest  up  stream,  that  for  bathing  and  launder- 
ing farthest  down  stream,  while  animals  are  watered  between.  If  it  is 
desired  to  fill  canteens  it  is  best  to  provide  small  excavations  for  that 
purpose,  otherwise  the  water  will  soon  be  rendered  niuddv,  making  it 
undesirable  for  those  farthest  down  the  bank. 

Boiling. — The  supply  for  tlie  day  may  be  boiled  in  covered  kettles  at 
night,  so  that  it  may  be  cool  by  morning.    Or  each  soldier  may  boil  his 


^ 


li=! 


iLJ-^ 


—  Darnall    Siphon  Filter  — 


(? 

2 

1  Sip/icn    With  cloth 

z    »     yyahoutcitth 


Fig.  185. — 1.  The  filter  cage  with  the  cloth  covering.  2.  The  filter  cage  without 
the  cloth  covering.  All  the  parts  of  the  apparatus  "rest"  in  the  largest  can, 
and  this  is  transported  in  the  crate.  (Wilson's  "Field  Sanitation,"  George 
Banta  Pub.  Co.  | 


individual  supply  in  the  canteen.  Boiling  is  a  safe  and  satisfactory 
method  of  rendering  water  safe.  In  the  exigencies  of  military  service 
boiling  is  not  always  practical,  and  when  resorted  to  must  be  carefully 
supervised. 

The  Forbes- Waterhouse  Sterilizer  is  based  upon  the  heat  exchange 
principle.  Crude  oil  or  solid  fuel,  however,  is  necessary  to  supply  the 
heat.  ^loreover,  the  outfit  when  packed  is  heavy  and  bulky  and  not 
always  reliable,  and  has  therefore  been  discontinued  in  our  army. 

Distillation. — Distillation  is  mostly  confined  to  marine  use. 

Filtration. — Filtration  is  often  necessary  to  clarify  a  water,  but 
except  under  unusually  favorable  circumstances  cannot  be  depended  upon 
under  military  conditions  to  render  a  water  safe.  The  British  and 
French  troops  both  use  water  carts  holding  one  hundred  gallons,  fur- 
nished with  a  Pasteur  filter.  The  filters  clog  readily,  break  often,  and  the 


147-2  MTLTTARY  HYGIENE 

arrangement  is  not  wholly  satisfactory.  The  Japanese  made  use  oi  the 
Ishiji  filter  in  the  war  with  Kussia^  based  on  the  principle  of  mechanical 
filtration  (page  1122).  It  consists  of  a  conical  canvas  reservoir  sup- 
ported from  a  tripod,  and  having  two  canvas  lugs  near  the  bottom  which 
hold  charcoal  and  sponge.    Alum  is  used  as  the  coagulant. 

The  Darnall  filter  used  in  our  army  is  also  based  upon  the  principle 
of  mechanical  filtration.  It  consists  primarily  of  a  reservoir  and  a 
siphon,  the  immersed  end  of  which  is  armed  with  a  wire  cage  over  which 
Canton  flannel  is  wrapped  as  a  filtering  material.  This  siphon  is  cleansed 
with  boiling  water  and  primed  with  a  small  pump.  The  water  to  be 
filtered  is  first  treated  with  the  coagulant — alum  and  sodium  carbonate 
in  the  ratio  of  one  pound  per  five  hundred  gallons.  The  bacterial  effi- 
ciency is  about  ninety  to  ninety-five  per  cent.  The  Darnall  filter  can 
filter  two  hundred  gallons  every  four  hours;  it  weighs  fifty-two  pounds. 
It  should  not  be  depended  upon  to  do  more  than  clarify  the  water,  which 
may  then  be  purified  with  chlorinated  lime. 

The  Darnall  filter  has  been  extensively  used  throughout  the  United 
States  Army.  It  is  the  most  easily  managed  and  transported  of  any  of 
the  modern  field  appliances  for  clarifying  turbid  water,  for  which  it  is 
especially  applicable.  Fig.  185  shows  the  construction  and  operation  of 
this  filter. 

Chemical.  Disinfection. — The  best  chemical  with  which  to  purify 
water  is  bleaching  powder — chlorinated  lime  (page  1132) .  A  very  muddy 
water  may  first  be  filtered.  The  manner  of  "chlorinating"  water  in  our 
army  is  by  the  use  of  the  Lyster  bag.  This  consists  of  a  waterproof 
canvas  bag  holding  forty  gallons,  with  five  faucets  near  the  bottom,  so 
that  the  entrained  sediment  will  not  be  drawn  off.  A  glass  ampule  holding 
one  gram  of  chlorinated  lime  is  broken  into  a  little  water  and  this  poured 
into  the  bag.  This  is  in  the  proportion  of  one  part  of  chlorinated  lime 
to  150,000  parts  of  water;  in  terms  of  available  chlorin,  one  part  to 
300,000 — otherwise  expressed  as  3.3  parts  per  million.  At  least  half  an 
hour  should  elapse  before  canteens  are  filled  from  the  faucets. 

The  British  in  the  World  War  used  a  100-gallon  metal  tank  on  two 
wheels,  to  which  twenty-five  grams  of  hypochlorite  were  added.  Water 
is  collected  from  indicated  sources,  and  allowed  to  stand  over  night 
with  its  charge  of  "bleach."  The  French  water  cart  is  made  up  of 
two  barrels  on  a  pushcart,  or  may  be  horse  drawn.  The  water  is  also 
disinfected  with  bleach.  In  addition  both  forces  analyzed  the  water  of 
springs,  wells,  streams,  etc.,  which  were  then  labeled  as  potable  or  non- 
potable.  The  sanitary  analysis  consists  chiefly  of  determining  the  chlo- 
rids  and  intestinal  bacteria.  The  United  States  water  wagon  holds  two 
hundred  and  twenty-five  gallons  and  has  a  pump  for  filling. 

For  water-borne  diseases  and  other  considerations  concerning  drink- 
ing water  see  Section  VIII. 


SANITATION   OK   liAUKACKS  AND  CAMPS 


1173 


Disposal  of  Excreta. —  l-'oi'  llic  iircNciitiuii  n\'  typlioid  lexer,  dysciilei-v, 
hookworip.  iin<l  otlior  iiifeclions  it  is  (if  pi'inie  iiii|i()i'liiiice  lliai.  the  urine 
and  feces  l)e  disjjosed  o['  in  a  safe  and  sati>fa(l(»r\  manner.  Of  all  canii) 
wastes  the  diseharucs  from  the  hody  h;i\c  the  ;^reatest  sanitary  si^^nifi- 
eaiiee.  For  pcnnaneiit  <>arrisons,  sewerage  systems  witli  water  carriage 
are  possihle  and  desirahle.  Fur  temporary  encami)mcnt,  hurial  or  Ijurn- 
iiig  ai'o  the  mo,st  satisfactory  methods. 

Various  types  of  incinerators  for  this  purpo.se  have  been  designed, 
such  as  tlie  Lewis  and  Kitclien,  and  the  ]\Ic('all  incinerators,  but  they 
aie  clumsy,  heavy,  and,  unless  (;arefully  teiuled,  prone  to  become  nuis- 
ances. 


Fig.  186. — Coxstructiox  of  Pit  Latrine.      (Munson'.s  "Military  Hygiene," 

Wm.  Wood  &  Co.) 


The  best  method  is  to  burn  the  material  with  crude  coal  oil,  which 
is  simply  poured  into  the  pit  and  lighted.  This  should  be  done  daily. 
In  firing,  some  straw  or  other  light  combustible  stufE  should  first  be 
thrown  in. 

Latrines. — The  best  design  is  the  Havard  latrine  box.  The  seats 
are  arranged  so  that  they  are  always  closed  save  when  in  use,  and  are 
in  pairs,  back  to  back.  The  box  should  be  lightproof  and  fly-tight,  and 
should  completely  cover  the  pit,  which  is  ten  feet  deep  by  six  feet  wide ; 
the  length  depends  upon  the  number  of  seats.  The  pit  is  edged  with  a 
board  frame  on  which  the  latrine  box  rests.  It  is  preferable  to  dig  the 
pits  in  pairs,  so  that  the  latrine  box  can  be  in  use  while  the  other  pit 
is  being  burnt  out.  The  pit  is  so  deep  that  the  board  frame  is  not  af- 
fected by  the  fire,  and  the  flame  is  hot  enough  to  consume  the  material 
with  little  or  no  odor.  After  the  burning,  lime  may  be  sprinkled  into 
the  pit,  depending  upon  circumstances. 

Latrines  should  be  ditched  to  prevent  flooding  and  screened  for  pri- 
vacy; also  roofed  against  rain.      Separate   urinals   should   be  provided 


1474 


MILITARY  HYGIENE 


in  order  to  prevent  soiling  the  seats  and  also  for  the  purpose  of  reclaim- 
ing the  ammonia. 

The  urinal  can  is  an  ordinary  galvanized  iron  can  issued  by  the 
Quartermaster's  Department.  If  such  a  can  is  not  available,  ordinary 
coal  oil  tins  will  suffice.    The  cans  are  placed  in  the  company  streets  at 


Fig.    187. — Straddle  Pit  Cover.    (Wilson's   "Field   Sanitation,"    George    Banta 

Pub.  Co.) 

retreat.  They  should  be  emptied  each  morning  at  reveille  into  the  sink 
or  the  incinerator  and  then  thoroughly  cleaned  and  put  in  the  sun  dur- 
ing the  day.  Two  or  three  times  each  week  the  cans  should  be  burned 
out  with  a  handful  of  straw  and  some  coal  oil.  The  position  of  the 
cans  should  be  marked  at  night,  with  a  lantern,  and  the  ground  where 


Fig.  188. — Pit  Crematory.    (Wilson's  "Field  Sanitation,"  George  Banta  Pub.  Co.) 


the  cans  stand  should  be  burned  over  each  day.  It  is  good  practice  to 
spread  latrines  once  daily  with  a  mixture  of  kerosene  and  lamp  black. 
In  the  absence  of  oil,  and  especially  on  the  march,  the  "^straddle  pit" 
is  used.  This  is  simply  a  narrow  deep  trench,  which  should  be  covered 
and  marked  on  leaving.     The  straddle  pits  are  recommended  for  camps 


SANITATION  OF  BARRACKS  AND  CAMPS 


1475 


of  one  night.  The  straddle  pit  is  simply  a  shallow  Iicik  li  less  llian  two 
feet  deep  and  is  used  by  the  men  astride.  It  is  easily  and  quickly  made, 
and  by  reason  of  its  slight  depth  ^lormits  more  rapid  disintegration  of 
the  excreta  and  is  easily  iilK'd  on  breaking  canij).  Accommodations 
should  be  provided  for  5  per  cent,  of  the  command. 

A  cover  for  the  straddle  pit,  devised  by  Major  R.  U.  Patterson,  of 
the  United  States  Army,  is  shown  in  Fig.  187.  It  is  arranged  for  two. 
The  lid  for  each  opening  falls  unless  held  open.  This  cover  only  requires 
a  little  lumber  and  four  straj)  hinges. 

All  camps,  both  temporary  and  permanent,  must  be  policed  to  prevent 


Fig.  189. — Pit  for  Kitchen  Refuse.     (Wilson's  "Field  Sanitation,"  George  Banta 

Pub.  Co.) 


nuisances.  Discipline  concerning  latrines  and  their  use  is  a  very  impor- 
tant factor  in  camp  sanitation.     See  also  Section  IX. 

The  following  rules  should  be  enforced  for  the  care  of  the  "sink" : 
it  should  be  screened  with  brush;  it  should  be  covered  with  a  tent  fly; 
it  should  have  a  light  at  night;  each  man  should  cover  his  deposit  with 
earth  by  means  of  a  scoop;  it  should  be  burned  out  daily  with  straw  and 
coal  oil;  it  should  have  a  comfortable  seat  and  a  good  receptacle  for 
toilet  paper;  the  ground  in  front  should  be  attended  to,  as  it  is  apt  to 
be  fouled  with  urine;  the  sink  should  be  ditched;  a  man  should  be 
detailed  to  see  to  it  that  these  measures  are  carried  out. 

Disposal  of  Garbage. — The  only  satisfactory  method  of  disposing  of 
garbage  under  camp  conditions  is  by  burning;  if  this  is  not  practical  it 
may  be  buried  and  well  covered.  No  other  method  should  be  coun- 
tenanced. Expensive  crematories  are  unnecessary,  for  simple  devices 
serve  every  purpose.     Each   mess  should   incinerate   its   own   garbage 


1476 


MILITAEY  HYGIENE 


promptly.    Garbage  burns  more  readily  if  the  solids  are  separated  from 
the  liquid,  which  may  be  done  by  a  sieve-covered  can. 

Wastes  from  the  kitchen  are  both  liquid  and  solid  and  are  often 
disposed  of  separately.  On  the  march  and  in  a  temporary  camp,  liquid 
waste,  such  as  dish  water,  is  best  disposed  of  by  digging  a  pit  in  the 
ground  near  the  kitchen,  and  when  possible  filling  it  half  full  of  stone. 
A  cover  should  be  placed  over  the  pit  to  prevent  accidents,  and  further, 
it  should  be  screened  against  flies.     The  cover  should  he  made  so  that 

one  portion  can  be  removed 
and  the  kitchen  slop  poured 
into  the  pit  through  a  strainer 
or  screen  of  wire.  The  dimen- 
sions are  about  4x4x6  feet 
deep.  Only  liquid  waste  should 
be  poured  into  this  pit.  The 
solid  matter  should  be  burned 
in  the  kitchen  fire. 

Another  arrangement  for  a 
pit  to  dispose  of  kitchen  refuse 
is  shown  in  Fig.  189.  This  is 
particularly  useful  in  sandy 
soil.  The  garbage  is  poured 
into  the  inner  can,  the  bottom 
of  which  is  a  strainer.  From 
time  to  time  the  solid  portion 
of  the  garbage  remaining  in 
the  inner  can  should  be  burned 
in  the  kitchen  fire. 

The  garbage  can  requires 
especial  attention.  The  cover 
must  fit  properly  and  always 
be  in  place  except  when  it  is 
being  filled  or  cleaned.  The 
outside  of  the  can  must  be  clean  at  all  times,  and  it  is  best  to  have 
it  stand  on  a  platform,  in  order  to  facilitate  emptying  and  to  prevent  a 
nuisance  under  the  can.  The  inside  of  the  can  may  be  purified  by 
burning  it  out  with  coal  oil,  straw  or  paper.  The  ground  around  the 
can  or  barrel  often  becomes  polluted,  and  hence  an  excellent  place  for 
the  breeding  of  flies  and  the  production  of  disagreeable  odors.  To 
remedy  this  condition,  scrape  the  ground  around  and  under  the  can, 
spread  hot  ashes  over  the  area  scraped,  and  occasionally  burn  over  the 
area  with  coal  oil.  On  no  account  should  cooks  be  allowed  to  sprinkle 
lime  on  the  ground  around  the  camp  to  take  the  place  of  cleanliness  and 
save  the  labor  of  policing. 


Whitened  stones 


''lug  o1  grass. 


'Mdiing  or5tra\N. 


Broken  Stones 


UeihE  50AKAGE  P/T 
Fig.  190. 


SANITATTOX  OF  BARRACKS  AND  CAMPS 


14'; 


The  rock  pile  cremalorics  are  tlie  best  garbage  incinerators  for  camps. 
They  are  all  basinl  u])on  the  same  principle,  but  it  is  unusual  to  find  any 
two  quite  alike.  Ksscntially,  they  consist  of  a  pile  of  embers  for  cre- 
mating the  heavier  ])ortions  of  the  garbage,  and  the  fire  is  placed  against 
a  pile  of  rocks  which,  when  hot.  volatilize  and  con.«ume  the  liquid  por- 


I-  IC.    I'.M. A    INx  K    I'lI.K    ('KKMAIORy. 

tion.     The  designs  vary  from  circular  as  shown  in  Fig.  191.  to  horse- 
shoe-shaped, with  or  without  a  stone  bottom. 

In  the  circular  rock  pile  crematory  the  fire  is  built  in  one  quadrant, 
into  which  solid  wastes  are  thrown.  The  central  pile  of  rocks  helps  in 
creating  a  draft  and  also  offers  a  larger  surface  for  evaporating  liquids. 


-^-^ 


-flr/Zef/ 


^/7?erqe/?c  y 


Ca/bac/^y    3G0 ^a//onS 
f-O  ^erye    2.5G man  A/'fcffen. 

Fig.  192. — U.  S.  Army  Grease  Trap. 


which  are  thrown  into  neighboring  quadrants.  Garbage  will  burn  itself, 
once  the  fire  is  well  started,  or  it  may  be  assisted  with  coal  oil  or  other 
inflammable  material.  Unconsumed  particles  together  with  the  ash 
should  be  scraped  up  and  burned  every  morning  by  the  kitchen  detail. 
When  fuel  is  scarce  and  stones  few,  probably  no  device  for  the 
destruction  of  garbage  and  refuse  is  more  readily  improvised  than  the 


1478  MILITARY  HYGIENE 

Caldwell  or  English  crematory.  It  consists  of  a  trench  ten  feet  long  and 
one  foot  wide  and  about  fifteen  inches  deep  at  the  middle  and  thence 
gradually  shallowing  up  at  each  end  to  the  surface  level.  Over  the  deep 
part  a  barrel  is  placed  and  around  it  is  constructed  a  chimney  five  feet 
high,  of  clay,  earth  ov.  sod,  sprinkled  with  water  and  packed  tightly.  Two 
openings  at  the  bottom  are  provided  for  draft.  A  fire  is  made  in  the 
interior  and  the  barrel  burned  out,  after  which  there  remains  a  solid 
cone  of  earth.  Fuel  and  garbage  are  dropped  down  the  chimney.  Of  the 
two  openings  the  one  to  leeward  is  closed.  A  bed  of  tin  cans  is  a  fair 
substitute  for  a  grate.    See  also  Section  X. 


SANITATION  OF  TRENCHES 

The  sanitation  of  trenches,  such  as  are  used  in  modern  warfare,  pre- 
sents unusual  difficulties.  Owing  to  the  extended  use  of  hand  grenades, 
trenches  are  dug  deep  enough  so  that  the  soldier's  head  is  several  feet 
below  the  surface.  Parts  of  trenches  may  be  40  feet  below  the  surface. 
Trenches  are  usually  one  to  two  meters  wide  and  often  contain  dugouts 
for  shelter,  protection  and  other  purposes.  Connecting  laterals  com- 
municate with  the  reserve  trenches  in  the  rear.  Ordinarily  one  man 
per  square  meter  is  stationed  in  the  first  line  trench,  which  is  increased 
to  four  or  five  in  time  of  attack. 

In  low  wet  ground,  or  in  rainy  weather,  water  collects  and  must  be 
pumped  out  or  drained.  The  trenches  may  be  floored  or  lined  with  wood, 
cement,  or  other  available  material. 

Eats  are  a  particular  nuisance  in  trenches  used  for  any  length  of 
time;  for  their  suppression  see  page  338.  Flies  abound,  owing  to  dead 
bodies  in  "no  man's  land"  between  the  opposing  lines,  and  also  from 
horse  manure.  Flies  were  held  to  be  responsible  for  much  of  the  gastro- 
intestinal disorders  among  the  troops  in  the  World  War.  Lice  and 
other  vermin  may  infest  the  trenches. 

Latrines  are  placed  in  covered  recesses  or  in  dugouts  a  short  distance 
to  the  rear  of  the  trenches,  and  connected  by  a  narrow  passage.  Lime 
and  sulphate  of  iron  are  used  plentifully  to  cover  excreta,  the  latter  if 
it  is  to  be  used  as  fertilizer;  it  is  better,  however,  systematically  to  col- 
lect, burn  or  bury  such  material.  All  forms  of  trench  trash  and  debris 
are  collected  in  sacks  and  carried  to  the  rear  frequently. 

Provisions  are  made  all  along  the  line  for  daily  baths  so  far  as  possi- 
ble, and  tubs,  improvised  showers  or  designated  streams  are  used  for  this 
purpose. 

Commands  are  relieved  from  trench  duty  as  frequently  as  exigencies 
permit.  The  usual  tour  of  duty  is  48  hours.  Despite  the  unfavorable 
conditions  there  has  been  surprisingly  little  sickness.     Epidemics  have 


HYGIENE  LN  Till':  TK'OIMCS  1479 

been  rare  and  mild.  An  unusual  lunnhcr  of  cases  of  psychoses  developed 
in  the  first  part  of  the  troni'h  war,  hut  the  nieiitaliy  unfit  were  soon 
weeded  out. 

Many  trenches,  especially  in  France,  are  du^^  in  land  that  has  been 
intensively  cultivated  for  centuries,  hence  infections  such  as  tetanus  and 
the  gas  bacillus  {B.  welchii)  frequently  c()nii)licate  wounds. 


HYGIENE  IN  THE  TROPICS 

The  chief  characteristics  of  tropical  climates  which  adversely  atfect 
military  service  are  the  constant  warm  temperature,  great  relative  hu- 
midity, high  degree  of  insolation,  close  contact  with  populations  having 
low  sanitary  standards,  and  prevalence  of  unusual  preventable  infections. 
Our  own  tropical  possessions,  such  as  the  Philippines,  Porto  Rico,  Hono- 


FiG.  193. — Improvised  Ice-box.     (Wilson's  "Field  Sanitation,"  George  Banta 

Pub.  Co.) 

lulu,  and  the  Canal  Zone,  have  better  climatic  conditions  than  continental 
regions  like  India,  South  America,  and  northern  Australia,  In  Manila 
the  mean  temperature  for  May,  the  hottest  month,  is  84.5°  F.;  in  the 
Philippines  92°  F.  in  the  shade  represents  a  hot  day.  The  discomforts, 
in  Cuba,  Porto  Rico,  and  the  Philippines,  of  the  constant  warmth  and. 
humidity  are  greatly  alleviated  by  the  almost  incessant  blowing  of  trade 
winds  or  monsoons.  In  these  parts  heat  exhaustion  is  rare;  sunstroke 
is  practically  unknown.  While  the  heat  and  high  humidity  of  our 
tropical  possessions  exert  an  enervating  influence,  it  is  believed  that  the 


1480 


MILITAKY  HYGIENE 


ill  effects  have  been  greatly  exaggerated.  Psychological  influences,  such 
as  fear  of  disease,  dislike  of  the  service,  homesickness,  monotony  of  life, 
enormous  distance  from  home  and  friends,  and  lack  of  social  oppor- 
tunity, rather  than  the  climate,  favor  mental  deterioration  and  recourse 
to  liquor  and  prostitutes. 

If  proper  care  is  taken,  with  sufficient  exercise  and  good  habits,  it  is 
as  easy  to  remain  in  good  health  in  the  tropics  as  in  temperate  regions. 
A   few   special    precautions    are    necessary    to    avoid    endemic    disease. 

I  can  vouch  for  the  fact  that  it  is  quite  prac- 
tical to  do  hard  mental  work  in  the  tropics 
for  a  year  or  more.  However,  prolonged 
residence  seems  to  bring  on  lassitude  and 
a  disinclination  for  both  mental  and  physical 
exertion.  Hence,  it  is  customary  in  our 
Government  Service  to  limit  tours  of  duty 
in  the  tropics  to  a  period  not  exceeding  three 
years  at  a  time. 

When  a  choice  is  possible,  residence  or 
camp  site  in  the  tropics  should  always  face 
the  trade  winds.  The  site  should  be  high 
and  dry  and  removed  from  native  quarters 
in  order  to  avoid  infections.  Houses  and 
tents  must  be  screened,  and  in  addition  a 
mosquito  bar  for  the  bed  is  advisable.  Houses 
should  be  built  on  piers  or  piles  well  above 
the  ground.  Where  ants  abound,  the  legs 
of  beds  and  food  chests  should  stand  in 
water,  but  care  must  be  taken  that  this 
water  does  not  become  a  breeding  place  for 
mosquitoes.  Special  care  should  be  taken 
to  remain  in  the  security  of  a  well-screened 
abode  from  before  sunset  until  after  sunrise. 
It  is  advantageous  to  avoid  the  direct  sun  at 
noon ;  otherwise  it  is  best  to  wear  a  pith  helmet  or  carry  a  green  parasol. 
Colored  glasses  against  the  glare  of  the  sun  are  a  comfort.  The  clothes 
should  be  white  or  khaki  color,  light  and  airy,  and  of  the  best  of  linen. 
The  diet  in  the  tropics  should  not  differ  materially  from  that  in  tem- 
perate climates — about  the  same  number  of  calories  are  required,  and  it 
is  not  possible  to  regulate  heat  production  and  heat  loss  through  diet. 
Overeating  is  more  apt  to  bring  on  gastro-intestinal  troubles  in  hot 
weather  than  in  cold.  Special  care  must  be  taken  to  see  that  the  diet 
is  well  balanced  and  contains  sufficient  vitamins. 

It  is  safest  to  eat  only  well-cooked  food  and  to  drink  only  boiled 
water,  unless  assured  of  their  quality.     More  water  should  be  drunk  in 


Fig.  194. — ^YATEK  Bag  to 
Cool  Water  in  Hot  Coun- 
tries. The  bag  should  be 
hung  in  the  breeze;  the 
cooling  depends  upon 
evaporation.  (Wilson's 

"Field  Sanitation,"  George 
Banta  Pub.  Co.) 


COLD  CLIMATES  1  ISl 

hot  cliiniitcs  to  make  u])  for  llic  umisiial  cNaporal  idii.  Alcolio]  csiicciallv 
imist  he  avoided   in  the  tropics. 

The  skin  shouhl  l)e  kept  dean,  and  eare  taki'n  to  ))re\ent  tlie  ell'eeL 
of  prickly  heat. 

It  is  a  (jroat  mistake  to  avoid  exercise  in  the  tropics.  Tennis,  jrolf, 
horsehack  ridin«i^  or  walking  in  the  cool  of  the  evening  or  morning  are 
helpful.  Swimming  is  an  nnusually  good  loim  of  exercise  in  the 
tropics,  provided  the  waters  are  clean  and   safe. 

It  will  he  necessary  to  have  an  ice-hox,  not  alone  for  food,  but  for 
serums,  vaccines,  and  other  supplies  which  are  ruined  by  heat. 

A  temporary  ice-box  on  the  march  and  in  temporary  camps  may 
be  made  simply  by  digging  a  hole  in  the  ground  and  wrapping  the  meat 
and  ice  in  a  shelter  tent  or  poncho — obviously  not  a  very  satisfactory 
arrangement.  In  1892,  Avhile  in  Camp  Jenner,  I  succeeded  in  keeping 
supplies  cold  and  clean  during  the  hot  summer  on  the  Rio  Grande  by 
sinking  boxes  in  the  ground  with  an  air  space  between.  This  ar- 
rangement is  shown  in  Fig.  193,  taken  from  Wilson's  "Field  Sanita- 
tion." This  ice-box  should  have  a  double  lid.  The  air  space  between 
the  two  boxes  may  be  packed  with  hay  or  sawdust.  Drain  holes  should 
be  placed  in  the  bottom. 

COLD  CLIMATES 

Ordinarily,  troops  stationed  in  Arctic  regions  maintain  a  higher 
average  of  health  tlian  those  remaining  in  the  temperate  zone.  Great 
cold  at  many  times  has  been  a  big  .factor  in  military  operations.  Per- 
haps the  most  notable  example  is  the  celebrated  retreat  from  Moscow. 
On  the  march  in  cold  weather  straggling  must  never  be  permitted. 
Tight  shoes,  or  anything  which  slightly  restricts  the  circulation,  greatly 
increases  the  liability  of  frost-bite.  Snow-blindness  is  common  among 
soldiers  in  the  northwestern  part  of  the  States  as  well  as  in  Alaska. 
It  may  be  prevented  by  wearing  colored  goggles,  with  a  felt  border  to 
prevent  freezing  to  the  face.  The  so-called  "snow  eyes"  of  the  Eskimo 
are  even  better.  They  consist  of  a  light  wooden  spectacle  with  a  narrow 
slit  to  look  through.  i\.nything  which  constricts  the  circulation  must 
be  avoided,  especially  in  cold  climates.  In  our  army,  woolen  outer  and 
under  garments  are  supplied  for  service  in  the  north  and  cotton  for  the 
south  and  the  tropics.  In  very  cold  weathet-  the  canteen,  filled  with  boil- 
ing water,  makes  a  very  fair  hot-water  bag. 


1482  MILITARY  HYGIENE 

REFERENCES 

General  Suhject 

Havard,   Valery:      "Military    Hygiene."      Wm.    Wood    and    Co.,    1914. 
Keeper,  Frank  R.  :    "Military  Hygiene  and  Sanitation."    W.  B.  Saunders 

Co.,  1914. 
Munson:     "Military  Hygiene."    Wm.  Wood  &  Co. 
WoODHULL :     "Military  Hygiene."     John  Wiley  &  Sons,  1909. 
Gatewood,  James  D.  :    "Naval  Hygiene."    P.  Blakiston's  Son  &  Co.,  1909. 
U.  8.  Nav.  M.  Bull.     Pub.  by  Bureau  of  Medicine  and  Surgery,  United 

S'tates  Navy. 
Mil.  Surgeon.     Pub.  by  Association  of  Military  Surgeons  of  the  United 

States,  Army  Medical  Museum,  Washington,  D.  C. 
"Ashburn's  Military  Hygiene."    Houghton,  Mifflin  Co.,  Cambridge,  Mass. 
"Military  Hygiene  for  Officers  of  the  Line."     John  Wiley  &  Sons,  New 

York. 


SECTION  XVI 

A  LABORATORY  COURSE  IN  PREVENTIVE  MEDICINE  AND 

HYGIENE 


Following  is  a  schedule  of  the  laboratory  course  used  in  the  Depart- 
ment of  Preventive  Medicine  and  ITygiene  of  the  Harvard  Medical 
School.  The  course  must  coordinate  with  other  Departments,  and  will 
therefore  vary  in  different  Medical  Schools. 

The  required  exercises  and  approximately  the  time  for  each  are  as 
follows : 

Time 
Subject  Period 

Vaccination  1 

Phenol  coefficient  1 

Water,  chemical  2 

Milk,  bacteriological  1 

''      chemical  1 

Bacterial  vaccine  1 

Vital  statistics  1 

Schick  test  and  diphtheria  diagnosis  1 

Pneumococcus  typing  1 

Meningococcus  carriers  1 

(A  period  is  from  3  to  5  p.  m.) 

The  following  optional  exercises  are  offered : 

Air  analysis 

Eoom  fumigation 

Water,  bacteriological 

Examination  sputum  for  tubercle  bacilli 

"  smears  for  gonococci 

"  feces  for  typhoid  bacilli 

Blood  grouping  on  basis  of  iso-agglutinins. 
Sanitary  Excursions 

Each  laboratory  exercise  must  be  written  up,  showing  how  the  re- 
sults were  obtained,  with  an  interpretation. 

Students  may  supply  their  own  sample  of  milk,  water,  etc.,  for  sani- 
tary analysis. 

1483 


1484     COUESE  IN  PREVENTIVE  MEDICINE  AND  HYGIENE 

The  laboratory  is  open  for  any  student  who  wishes  to  repeat  an  exer- 
cise, or  do  additional  work  connected  with  his  sanitary  survey,  or  other 
problem  in  Preventive  Medicine.  Assistance  will  be  given.  Apply  to 
the  Instructor. 

I 

Vaccination 

(Vaccinia — Cow  pox) 

Students  will  vaccinate  each  other,  and  each  student  will  keep  a 
careful  clinical  record  of  his  own  local  and  general  reactions. 

Keep  a  daily  record  of  temperature,  pulse,  etc.,  on  the  enclosed  chart. 
Fill  in  blank  below  and  make  a  daily  record  of  (1)  local  eruption, 
with  sketches  showing  size,  number,  color,  appearance,  and  development 
of  papules,  vesicles,  pustules  and  areola;  (2)  constitutional  symptoms, 
enlargement  of  lymph  nodes,  etc.  Students  are  advised  to  make  blood 
counts,  urine  examinations,  and  other  laboratory  tests. 

Indicate  in  conclusion  the  type  of  reaction,  whether  primary,  accel- 
erated, immediate,  or  negative. 

VACCINATION    RECORD 

Name  Age  Sex 

Operator  Date  Hour         M. 

Vaccine :  Produced  by  TJ.  S.  License  No.     Lot  No. 

History  of  Previous  Vaccinations: 

1st  2nd  3rd 

(1)  Age 

(2)  Method 

(3)  Eesult 

(4)  Sketch  of  previous  scars 

Clinical  Study  of  Present  Vaccination:  (a)  Daily  record  local  erup- 
tion, etc. 

(b)  Constitutional  symptoms.  Eecord  temperature,  pulse,  etc. 
on  enclosed  chart. 

(Use  extra  sheets  if  necessary) 
Summary  and  Diagnosis : 

Other  Tests 

Immunity  or  susceptibility  to  diphtheria  as  determined  by  the  Schick 
test  will  be  given  in  a  separate  exercise. 

Students  are  also  offered  opportunity  to  immunize  each  other  with 
the  triple  typhoid  vaccine. 


COUESE  IN  PREVENTIVE  MEDICINE  AND  HYGIENE     1485 

Opportunity  will  be  given  to  test  sensitiveness  to  various  foorl  pro- 
teins, pollens  and  other  antigens. 

Accurate  clinical  records  must  be  made  in  detail  of  the  course  of 
events  of  each  test  made.  These  records  should  be  inserted  in  the 
notebook. 

II 

Standardization  of  Disinfectants 

Phenol  {Carbolic)  Coefficient 

Object. — To  compare  the  germicidal  power  of  an  unknown  disin- 
fectant against  that  of  a  1  per  cent,  solution  of  phenol. 

IMake  up,  according  to  directions,  two  dilutions  of  phenol,  and 
three  of  the  unknown  disinfectant,  from  the  following  table : 

From  a  5  per  cent,  solution  of  phenol 

10  c.  c.  plus  35  c.  c.  water  =  1 :90 

10  c.  c.     "      40  c.  c.       "     =  1 :100 
From  a  1  per  cent,  solution  of  the  unknown  disinfectant 

10  c.  c.  plus  12%  c.  c.  water  =  1 :225 

10  c.  c.     "      15       c.  c.       "     =1 :250 

10  c.  c.     "      171/2  c.  c.       "     =  1 :275 

Bring  the  water  bath  to  20°  C.  The  thermometer  should  be  in  a 
test  tube,  partly  filled  with  water,  in  the  bath.  Place  the  suspension  of 
B.  typhosus  in  the  bath  to  allow  the  clumps  to  settle  and  the  tempera- 
ture to  reach  20°  C.  Place  the  5  large  sterile  test  tubes  in  their  places 
in  the  water  bath. 

Transfer  5  c.  c.  of  the  phenol  dilution  (1-90)  to  the  first  large  test 
tube  on  the  left  of  the  water  bath.  Einse  the  pipet  in  the  next  dilu- 
tion (1-100)  and  transfer  5  c.  c.  of  it  to  the  next  tube  in  the  water 
bath.  With  another  pipet,  transfer  5  c.  c.  of  the  dilutions  of  the  un- 
known disinfectant  to  the  remaining  three  large  test  tubes,  working 
from  left  to  right. 

Flame  both  platinum  loops.  Add  0.1  c.  c.  of  the  culture  to  each 
of  the  5  large  tubes  at  exactly  30-second  intervals,  beginning  at  the  left, 
and  taking  care  that  the  culture  does  not  get  on  the  walls  of  the  tube. 
Mix  contents  of  tubes  after  adding  cultures. 

Thirty  seconds  after  inoculating  the  last  large  tube,  start  to  trans- 
fer a  loopful  from  each  large  tube  in  the  water  bath  to  culture  tubes 
in  the  rack,  and  continue  without  interruption  at  intervals  of  30  seconds 
until  all  the  transfers  have  been  made.  The  platinum  loops  are  flamed 
and  used  alternately.  Label  the  first  tube  of  each  row  with  the  dis- 
infectant and  dilution.     Incubate  for  48  hours  and  tabulate  results. 


1486     COURSE  IX  PEEVENTITE  MEDICIXE  AXD  HYGIENE 


KJT  AMPLE 

Time  in  Minutes 

21/2 

5 

71/2 

10 

121/2 

15 

Phenol        1-90     

Phenol        1-100   

UnknowTi  1-225   

Unknown  1-250 

Unknown  1-275   

+ 
+ 

+ 

+ 
+ 

+ 
■        + 

+ 

+ 

+ 

— 

— 

The  carbolic  coefficient  is  therefore  ^  =2.50. 

Eecord  results  and  state  the  limitations  of  the  test  as  applied  to 
the  value  of  a  germicide  in  practical  application. 


Ill 

Water- 


exercise  1 

Object. — To  determine  various  kinds  and  degrees  of  pollution. 

Free  and  Albuminoid  Ammonia. — Wash  flasks  and  Xessler  jars  with 
distilled  and  ammonia-free  water.  Measure  out  500  c.  c.  of  the  sample 
and  pour  into  flask. 

Connect  flask  to  condenser  and  light  burner,  adjusting  so  that  the 
Xessler  jars  fill  in  from  5  to  8  minutes. 

Distill  over  three  jars  of  50  c.  c.  each. 

Turn  out  flame  and  disconnect  flask.  Add  40  c.  c.  alkaline  per- 
manganate solution  (hot)  and  continue  distillation  until  5  more  jars 
are  collected.  Measure  into  Xessler  jars  from  buret  the  following 
amounts  of  ammonium  chlorid  standard  :  0.3,  0.5,  0.7,  1.0,  1.5,  2.0,  2.5, 
3.0,  3.5,  4.0,  4.5,  5  c.  c,  and  dilute  with  ammonia-free  water  to  the 
50  c.  c.  mark.  To  each  of  the  eight  jars  collected,  and  to  each  standard 
jar,  add  2  c.  c.  of  Xessler  solution.  DO  XOT  MIX.  Allow  to  stand 
ten  minutes.  Compare  each  jar  distilled  over  with  the  standard.s,  and 
record  the  number  of  c.  c.  of  ammonia  in  the  standard  which  it  matches. 
For  example,  if  jar  Xo.  1  matches  the  jar  containing  1.5  c.  c.  of  the 
standard,  record  it  as  1.5.  Add  together  the  results  from  the  three  jars 
for  free  ammonia  and  multiply  by  0.02  to  get  part  per  million  of  X 
as  free  ammonia.  Do  the  same  for  the  five  jars  distilled  for  albuminoid 
ammonia. 


COURSE  IN  PREVENTIVE  MEDICINE  AND  HYGIENE     1487 


EXAMPLE 


N  as  Free  NHj 

N  as 

Albuminoid  NH, 

Jar  1  —  1.5 

Jar 

4  —  1.7 

"     2  —  0.3 

(( 

5  —  0.8 

"     3  —  0.0 

(( 

6  —  0.5 

(( 

7  —  0.3 

1.8  X  0.02 

« 

8  —  0.3 

^  0.036  part  per  million 

3.6  X  0.02 

=  0.072 

part  per  million 

Record  results  and  give  interpretation. 


EXERCISE    2 

1.  Nitrate  Determination. — Measure  exactly  20  c.  c.  of  the  sample 
into  a  small  evaporating  dish.  Put  on  the  water-bath  and  evaporate 
nearly  to  dryness.  Allow  the  last  few  drops  to  evaporate  at  room  tem- 
perature. Add  1  c.  c.  of  phenol  di-sulphonic  acid  from  the  buret  and 
rub  up  thoroughly  with  a  rod.  Add  about  10  c.  c.  of  distilled  water  and 
make  alkaline  to  litmus  paper  with  ammonium  or  potassium  hydrate. 
Wash  into  a  Nessler  jar  and  dilute  to  the  50  c.  c.  mark  with  distilled 
water.  Compare  with  standard  nitrate  solution  as  follows :  Fill  a  50 
c.  c.  graduate  with  the  standard  nitrate  solution  and  pour  into  a  clean 
100  c.  c.  Nessler  jar  until  the  color  matches  the  sample.  Note  amount 
of  standard  used  and  record.     (Or  compare  with  a  series  of  standards.) 

To  find  parts  of  N  as  nitrates  per  million,  divide  the  number  of  c.  c. 
of  standard  by  the  number  of  c.  c.  of  sample  used. 
Record  results  and  give  interpretation. 

2.  Determination  of  Nitrites. — Fill  a  Nessler  jar  up  to  the  50  c.  c. 
mark  with  the  sample.  To  the  sample  add  1  c.  c.  of  sulphanilic  acid 
and  1  c.  c.  of  alphanaphthylamin.  solution  from  the  burets.  MIX 
THOROUGHLY.  Allow  to  stand  not  less  than  10  minutes  nor  more 
than  30.  Compare  sample  with  standards  and  record  in  terms  of  c.  c. 
of  standard  nitrite  solution.  To  get  parts  of  N  as  nitrites  per  million, 
multiply  the  number  of  c.  c.  of  the  standard  by  0.01.  The  color  is  due 
to  the  formation  of  azobenzolnaphthalaminsulphonic  acid. 

Record  results  and  give  interpretation. 

3.  Determination  of  Chlorids. — ]\Ieasure  out  50  c.  c.  of  the  sample 
into  the  evaporating  dish.  Into  another  measure  50  c.  c.  of  distilled 
water.  Add  to  each  1  c.  c.  of  the  potassium  chromate  indicator.  To 
the  .^^ample  add  carefully  from  the  buret  standard  AgNO.,  until  the 
red  of  the  silver  chromate  persists,  using  the  distilled  water  for  com- 
parison of  colors.  Record  number  of  c.  c.  of  the  standard  AgNO.5  solu- 
tion used.     Each  c.  c.  of  the  standard  equals  0.0005  gram  of  CI,  or 


1488     COUESE  m  PEEVENTIVE  MEDICINE  AND  HYGIENE 

0.5  mg.  of  chlorid.  The  number  of  c.  c.  of  the  standard  used  times 
0.5  equals  mg.  of  chlorid  in  50  c,  c.  of  the  sample.  This  result  times 
20  equals  mg.  per  liter  or  parts  per  million. 

Eecord  results  and  give  interpretation. 

4.  Determination  of  Hardness. — Into  the  glass  stoppered  bottle 
measure  50  c.  c.  of  the  sample.  From  the  buret  add  standard  soap 
solution  0.3  c.  c.  at  a  time.  After  each  addition  shake  thoroughly,  and 
lay  the  bottle  on  its  side.  When  the  latter  covers  the  entire  surface 
and  persists  for  live  minutes,  read  the  buret  and  record.  Now  add 
0.5  c.  c.  of  the  soap  solution.  Shake,  and  if  the  lather  disappears  add 
more  soap  as  before  uEttil  a  lather  is  obtained  which  persists  for  five 
minutes.  The  magnesium  salts  are  precipitated  first,  then  the  calcium 
salts;  hence  the  second  addition  of  soap  solution  after  five  minutes, 
which  will  indicate  the  presence  or  absence  of  calcium  hardness.  If 
the  lather  does  not  disappear  on  the  addition  of  the  0.5  c.  c.  of  soap 
solution,  the  first  reading  is  the  end  point.  Eead  the  parts  per  million 
from  the  table  of  hardness  and  convert  into  degrees  of  hardness  Clark's 
scale  from  the  conversion  table. 

Eecord  results  and  give  interpretation. 

TABLE  OF  HARDNESS  SHOAVING  THE  PARTS  PER  MILLION  OF  CALCIUM  CARBONATE  FOB 
EACH  0.1  C.  C.  SOAP  SOLUTION  WHEN  50  C.  C.  OF  SAMPLE  ARE  USED 


C.  c.  of  Soap 

0.0 

0.1 

0.2 

0.3 

0.4 

0.5 

0.6 

0.7 

0.8 

0.9 

Solution 

c.  c. 

c.  c. 

c.  c. 

c.  c. 

c.  c. 

C.  C. 

c.  c. 

c.  c. 

c.  c. 

C.  c. 

0.0 

0.0 

1.6 

3.2 

1.0 

4.8 

6.3 

7.9 

9.5 

11.1 

12.7 

14.3 

15.6 

16.9 

18.2 

2.0 

19.5 

20.8 

22.1 

23.4 

24.7 

26.0 

27.3 

28.6 

29.9 

31.2 

3.0 

32.5 

33.8 

35.1 

36.4 

37.7 

38.0 

40.3 

41.6 

42.9 

44.3 

4.0 

45.7 

47.1 

48.6 

50.0 

51.4 

52.9 

54.3 

55.7 

57.1 

58.6 

5.0 

60,0 

61.4 

62.9 

64.3 

65.7 

67.1 

68.6 

70.0 

71.4 

72.9 

6.0 

74.3 

75.7 

77.1 

78.6 

80.0 

82.4 

82.9 

84.3 

85.7 

87.1 

7.0 

,88.6 

90.0 

91.4 

92.9 

94.3 

95.7 

97.1 

98.6 

100.0 

101.5 

CONVERSION    TABLE   OF   HARDNESS 


Parts  per 
Million 

Clark 
Degrees 

French 
Degrees 

German 
Degrees 

Parts  per  million 

1.00 
14.3 
10.0 

17.8 

0.07 
1.00 
0.70 
1.24 

0.10 
1.4.3 
1.00 
1.78 

0.056 

Clark  degrees 

0.80 

French  degrees 

0.56 

German  degrees 

1.00 

English  degrees  of  hardness  (Clark's  scale)  represent  grains  of 
calcium  carbonate  per  imperial  gallon. 

French  degrees  of  hardness  represent  parts  per  100,000  of  calcium 
carbonate. 

German  degrees  of  hardness  represent  parts  per  100,000  of  cal- 
cium oxid. 


COURSE  IN  PREVENTIVE  MEDICINE  AND  HYGIENE     1489 

To  convert  hardness  from  one  scale  to  another,, multiply  by  the  factor 
opposite  the  scale  in  which  it  is  expressed  and  under  the  scale  to  wliich 
it  is  to  be  converted. 

The  temporary  hardness  is  due  usually  to  l)icarbonates  of  calcium 
and  magnesium;  the  permanent  hardness  is  due  to  sulphates  and  chlo- 
rids  of  these  elements. 


IV 

Milk 

Bacteriology  of  Milk— Object. — To  determine  the  sanitary  charac- 
ter of  a  milk. 

1.  Mix  milk  by  shaking  the  bottle. 

2.  Flame  lip  of  bottle  and  pour  a  sterile  test  tube  about  half  full 
of  milk  for  B.  Welchii  test.  Put  test  tube  into  water-bath  at  80°  C. 
for  an  hour.    Incubate  this  for  24  to  48  hours  at  37°  C. 

3.  Pour  about  50  c.  c.  milk  into  sterile  bottle  for  bacteriological 
work. 

4.  Put  agar  on  to  melt. 

5.  Label  Petri  dishes:  1/100,  1/1,000,  1/10,000  in  duplicate,  to- 
gether with  name  and  date, 

6.  With  first  1  c.  c.  pipet: 

(a)  Put  1  c.  c.  milk  into  99  c.  c.  water  blank;  shake  25  times  = 
1/100  dilution. 

With  second  pipet,  put: 

(a)  1  c.  c.  of  1/100  dil.  into  9  c.  c.  water  blank  =  1/1,000  dilu- 
tion. 

(b)  1  c.  c.  1/100  dil.  into  99  c.  c.  water  blank  =  1/10,000  dilu- 
tion. 

(c)  and  (d)   1  c.  c.  1/100  dil.  into  2  Petri  dishes. 
With  third  pipet,  put : 

(a)     and  (b)  1  c.  c.  1/1,000  dil.  into  2  Petri  dishes. 
With  fourth  pipet,  put : 

(a)     and  (b)  1  c.  c.  1/10,000  dil.  into  2  Petri  dishes. 
Before  plating  each  dilution,  rinse  pipet  by  drawing  dilution  to  be 
plated  back  and  forth  in  the  pipet  several  times. 

7.  Cool  agar  slightly  by  adding  cold  water  to  cup.  Cool  each  tube 
to  about  45°  C;  test  by  placing  tube  against  cheek;  flame  lip  of  tube 
and  pour.  Revolve  plate.  Allow  to  cool  while  doing  other  tests.  When 
hard  place  upside  down  in  incubator.  Plates  should  be  read  in  24  to 
48  hours. 

8.  Empty  dilution  bottles  and  put  pipets  in  pan. 


1490     COUESE  IN  PEEVENTIVE  MEDICINE  AND  HYGIENE 

MICROSCOPIC    EXAMINATION    OF   BACTERIA   IN    MILK 

Breed  Method. — 1/100  c.  c.  milk  or  cream  is  spread  with  needle  over 
area  of  a  square  centimeter.  Film  allowed  to  dry.  Fix  in  methyl  alco- 
hol, extract  fat  in  ether.  Stain  in  Loeffler's  methylene  blue  to  desired 
intensity.  Extract  any  excess  stain  in  the  preparation  by  dipping  in 
95  per  cent,  alcohol.  It  is  necessary  to  know  the  area  of  microscopic 
field  at  any  given  tube  length,  and  this  may  be  determined  by  a  stage 
micrometer.  Using  oil  immersion  lens,  count  organisms  in  field  of 
known  area.  To  make  this  comparable  to  agar  plate  count,  groups  of 
organisms  of  same  kind  are  counted  as  one.  Count  from  ten  to  fifty 
fields  in  this  manner  and  determine  average.  Then  if  the  area  of  each 
field  counted  is,  for  example,  1 :4,000  of  a  square  centimeter,  then 
the  final  count  in  1  c.  c.  would  be  X  (the  average  for  each  field)  multi- 
plied by  4,000,  multiplied  by  100  (the  amount  of  milk  taken).  This 
method  is  very  valuable  in  determining  the  condition  of  milk  previous 
to  pasteurization,  Eesults  may  be  obtained  in  two  or  three  hours,  and  in 
raw  milk  they  agree  closely  with  plate  count. 

Slack's  Method  (demonstrated). — A  definite  volume  of  milk  is 
sedimented.  This  sediment  is  spread  on  a  slide,  stained  as  described 
under  the  Breed  Method,  and  examined.  A  total  count  is  obtained  which 
is  approximately  quantitative.  This  method  is  valuable  in  classification 
of  milks  on  basis  of  presence  or  absence  of  streptococci  or  other  organ- 
isms of  characteristic  morphology, 

BACTERIOLOGICAL  MILK   STANDARDS 

Certified,  or  Grade  A  (raw  milk). — Not  over  10,000  per  c.  c. 

Grade  A  (pasteurized  milk). — Not  over  200,000  per  c.  c.  before  pas- 
teurization, and  not  over  10,000  per  c.  c,  after  pasteurization. 

Grade  B. — :Not  over  1,000,000  per  c.  c.  before  pasteurization  and 
less  than  50,000  per  c,  c,  after  pasteurization. 

Cream. — In  20  per  cent,  cream  the  count  shall  not  be  more  than  five 
times  the  limit  for  the  same  grade  of  milk, 

1,.  Fat  Test. — Milk  should  be  well  mixed  by  pouring  (not  shaking) 
immediately  before  each  of  the  following  tests: 

Pipet  into  the  Babcock  flask  17.6  c.  c.  of  the  sample  of  milk. 
Pipet  17.6  c.  c.  of  H2SO4  (sp.  gr.  1.82)  into  the  flask  (properly  bal- 
anced) and  revolve  on  centrifuge  for  five  minutes.  Eemove  flask  and 
add  hot  water  up  to  the  mark  at  the  bottom  of  the  neck  and  whirl  for 
three  minutes.  Eemove  again  and  add  hot  water  up  to  the  8  mark  in  the 
heck.  Whirl  again  for  one  minute.  Eemove  and,  with  the  calipers, 
immediately  read  the  percentage  of  fat.  Empty  the  flask  and  rinse 
with  hot  water  before  the  contents  get  cold. 

2.  Specific  Gravity. — Mix  the  milk  thoroughly  by  pouring  and 
fill  the  cylinder.     Take  the  specific  gravity  with  the  Quevenne  and  New 


COURSE  IN  PREVENTIVE  MEDICINE  AND  IIVCIKXE     1101 

York  Board  of  Health  lactodciisinu'tcrs.  Hccdiil  Iciiipcrature  and  spo- 
cific  gravity.  Correcl  r;\r\\  (Icti'iniinnt  imi  lur  triiipi'ratuic  liy  tin'  lahlc. 
(Accoptod  toin]M'i-atiiri'  for  sj).  ^i-.  is  (in  '   |'\  or  about  .1.')"  (!.) 

3.  Total  Solids. —  liiclniioiid  Slide  U'ulc  Bring  the  observed  lac- 
tometer ivadiui;-  opposite  the  (iO  '  mark  and  road  the  correct  specific 
gravity  opposite  tlie  observed  teni})erature.  The  arrow  of  the  slide  is 
then  sot  opposite  the  observed  percentage  of  fat  and  the  total  solids 
are  read  opposite  the  corrected  specific  gravity  on  tlie  scale  marked 
"specific  gravity.'' 

TABLE  FOR  CORRECTING  THE  SPECIFIC  GRAVITY  OF  MILK  ACCORDING  TO  TEMPERATURE. 

(Adapted  from  Table  of  Vielh.) 


Specific  Gravity 

10° 

11° 

12° 

13° 

14° 

15° 
26.9 

16° 
27.1 

17° 

27.4 

18° 
27.5 

19° 

20" 

1.027 

26.1 

26.2 

26.4 

26.5 

26.7 

27.7 

28.0 

28 

27.0 

27.2 

27.4 

27.5 

27.7 

27.9 

28.1 

28.4 

28.5 

28.7 

29.0 

29 

2S.0 

28.2 

28.4 

28.5 

28.7 

28.9 

29.1 

29.4 

29.5 

29.8 

30.1 

30 

29.0 

29.1 

29.3 

29.5 

29.7 

29.9 

30.1  :  30.4 

30.5 

30.8 

31.1 

31 

29.9 

30.1 

30.3 

30.4 

30.6 

30.9 

31.2 

31.4 

31.5 

31.8 

32.2 

32 

30.9 

31.1 

31.3 

31.4 

31.6 

31.9 

32.2 

32.4 

32.6 

32.9 

33.2 

33 

31.8 

32.0 

32.3 

32.4 

32.6 

32.9 

33.2 

33.4 

33.6 

33.9 

34.2 

Directions  :     Find  the  observed  gravity   in  the  left-hand  column.     Then,  in  the  same 
line  and  under  the  observed  temperature  will  be  found  the  corrected  reading. 

TEMPERATURE  CONVERSION  TABLE 


c. 

F. 

C. 

F. 

9° 

48.2° 

15° 

59.0° 

10° 

50.0° 

16° 

60.8° 

11° 

51.8° 

17° 

62.6° 

12° 

53.6° 

18° 

64.4° 

13° 

55.4° 

19° 

66.2° 

14° 

57.2° 

20° 

68.0° 

To  change  degrees  C.  to  degrees  F.  =   (C.°    X    915)    +   32 
«         "  "        F.    "  "       C.  =   (F.°  —     32)    X  5/9 

4.     Milk  Standards. — 


Butter  Fat 

Solids  Not  Fat 

Total  Solids 

U.  S.  Government. 
Boston,  Mass 

3.35 
3.25 

8.5 

12.0 

In  general,  the  following  may  be  applied  to  the  interpretation  of 
results  of  chemical  examination  of  milk : 

Normal  Milli. — Eatio  of  fat  to  total  solids  about  as  indicated  in 
Standards  : 

3.25    :  13  ==  1   :  4  (approximately) 

Skim  Milk. — Eatio  of  fats  to  total  usually  more  than  1  :  4. 
0.8  per  cent,  (fat)    :  9.3  per  cent  (total  solids)  =  1   :  11 


1492     COTJESE  m  PEEVENTIVE  MEDICINE  AND  HYGIENE 

Watered  Milk. — Eatio  of  fat  to  total  solids  about  as  in  normal  milk, 
but  actual  amount  of  each  low.     Solids  not  fat  usually  below  8.0. 
2.1  per  cent,  (fat)    :  9  per  cent,  (total  solids)  =1:4  (approximately) 

Shimmed  and  Watered  Milk. — Low  fat,  low  solids  not  fat,  and  ratio 
of  fat  to  solids  usually  greater  than  1  :  4. 

1.2  per  cent,  (fat)    :  8.5  per  cent,   (total  solids)   =:  1   :  7 

In  the  last  tM'o  types  of  adulteration  a  determination  of  refractive 
index  is  valuable  in  drawing  conclusions. 


V    . 

Bacterial  Vaccine 

Alternative  Methods  Will  Be  Demonstrated 

1.  Set  up  water  bath  to  each  2  -men  and  accurately  regulate  to 
53"  C. 

2.  Clean  slides  for  smears. 

3.  Make  bacterial  suspension  with  1  c.  c.  ungraduated  pipet 
using  about  1  to  2  c.  c.  salt  solution  and  reserve  drop  in  pipet  for 
Par.  4.  Heat  suspension  for  one-half  hour  in  water  bath.  Boil  large 
rubber  nipple  ten  minutes. 

4.  Put  grease  pencil  mark  on  capillary  pipet  about  one  inch  from 
end.  Draw  citrate  solution  to  the  mark,  allow  a  small  bubble  of  air  to 
enter,  draw  up  a  measure  of  blood  from  finger,  allow  bubble  to  enter, 
and  finally  draw  up  a  measure  of  bacterial  suspension.  Force  out  pipet 
contents  on  a  clean  slide,  mix,  withdraw  a  small  drop  to  another  slide, 
and  with  the  edge  of  a  clean  slide  make'  a  smear. 

5.  Fix  in  alcohol,  allow  to  evaporate,  stain  with  eosin  two  minutes, 
and  wash.  Stain  with  methylene  blue  30  seconds  and  wash  until  the 
eosin  color  reappears. 

6.  Count,  using  oil  immersion  lens.  Count  both  r.  b.  c.  and  bac- 
teria in  each  field  until  1,000  r.  b.  c.'s  are  counted. 

7.  Compare  suspension  to  turbidity  standards,  and  estimate  num- 
ber of  organisms  present. 

8.  Make  up  vaccine  to  contain  1,000,000,000  bacteria  per  c.  c. 

CALCTJLATION 

•    Lot  X  =  No.  bact.  in  suspension  per  cu.  mm. 

Lot  Y  =  No.  bact.  counted,  in  this  case  3,760.  •     • 

5,000,000  =  r.  b.  c.  per   cu.   mm. 
1,000  :=  r.  b.  c.  counted. 
1,000  :  3,760  : :  5,000,000  :  X 


COURSE  IN  rREVFATIVK  MKDICINE  AND  nVOTENE     1103 

1    f.    f.    coiitiiiiis    1S,S()(),000.(»()()    hiutiTia.      Tlirn-fnic.    jidil    17.8    c.    c. 
sterile  solution  to  cncli  c.  c.  of  hactfiial  suspension  ;  for,  if 

18.8  c.  0.  =  18.S()0.0()0,000  bacteria, 
thenlc.  c.  =    1,000,000,000       " 

n.     'Make  transjilant  usin^  O.;")  c.  c.  to  bouillon   lultr. 

10.  Add  tricresol  to  vaccino  sufficient  to  nnikc  0."j;?  jkt  cent. 

11.  Stopper  vaccine  with   inverted  sterile  nij)ple. 

VI 

Vital  Statistics 

Estimate  of  Population. — Example  of  arithmetical  method. 

Population  of  a  city  June  1,  1900,  census  50,000 

Population  of  same  city  April  lo,  1910.  census  61,850 

Period  between  =  9  years  lOi/o  months  =  9.875  years. 

Annual  increase  by  arithmetical  calculation : 

61,850  —  50,000 

=  1,200  per  year. 

Estimated  for  July  1,  1906 :  Period  from  6—1—00  to  7—1—06  = 
6  years,  1  month  =  6.083  years  =  50,000  +  (6,083  X  1,200)  =:  57,300. 

As  a  rule,  population  is  estimated  to  July  1st  for  the  year  in  which 
the  statistics  are  being  compiled. 

Formulae. — General  (crude)  death  rate  =  t — '. _  ^  i  qOG 

Population         ' 
Corrected  for  non-residents: 

No.  deaths   (residents) 

Resident  death  rate  =  — =, t—. X  1.000 

Population 

Specific  death  rate  for  a  disease: 

No.  deaths  from  a  specific  disease 

——, r— X  100,000 

Total  population 

Fatality  rates  in  per  cent. : 

No.  deaths  from  a  specific  disease 

^ JT^ XlOO 

No.  cases  ol  the  same 

Morbidity  rate,  or  incidence : 

No.  cases  of  a  specific  disease 

r,     \   ,■ X  1,000 

Population 
Infant  mortality : 

No.  deaths  of  children  under  1  year 

: — X  1,000 

No.  births  for  year 

(Still-births  not  included) 


1494     COUESE  IN  PEEYENTIVE  MEDICINE  AND  HYGIENE 


General  (crude)  birth  rate: 
No,  births  per  year 


X  1,000 


Population 

Problems. — Data  are  given  below  for  Pittsburgh,  Pennsylvania.  From 
them,  calculate: 


(1 
(3 
(3 
(4 
(5 
(6 

(8 


General   (crude)    death  rate. 

Death  rate  corrected  to  exclude  non-residents. 

The  specific  death  rate  of  white  and  colored  people. 

Specific  death   rate  for  tuberculosis  and  typhoid. 

Fatality  rate  for  typhoid,  etc. 

Incidence  of  measles,  typhoid,  etc. 

Infant  mortality,  general,  white  and  colored. 

The  birth  rate,  general,  white  and  colored. 

STATISTICS   FOR  PITTSBURGH,   PENNSYLVANIA 


Population 


Year 

Total 

VThlte 

Colored 

1880 

156,381 
238,617 
451.512 
533,905 

588,193 

430,973 

508,008 

1890    

1900  (as  of  June    1st) 

1910  (  "    "  '    "     15th) 

1920  (est      July     1st) 

20,355 
25,623 

Statistics 

for  1911 

Deaths 

Deaths  From 

Total    10,645 

White  9,472 

Colored 903* 

Non-Resident 1,278 

Tuberculosis    (Pulmonary)  : 

Total    753 

White   670 

Colored    83 

Typhoid : 

Total    70 

Measles : 

Total    63 

No.  of  Cases  of 

Typhoid   234 

Measles   4,031 

Tuberculosis    (Pulmonary) 6,024 

Births 

Deaths  Under  1  Year 

Total    16,543 

White                                   15,889 

Total   1,983 

Wliite 1,846 

Colored 655* 

Colored  137 

*  It  will  be  noted  the  deaths  colored  exceed  births, 
following  statistics  show  : 


That  this  is  not  uncommon  the 


COTJESE  IN  PREVENTIVE  MEDICINE  AND  HYGIENE     1495 


1919 


Deaths   (colored) 
Births 


788 
703 


1920    (1st  half  year) 


Deaths  (colored)    474 

Births  "  332 


Number  of  cases  estimated  from  total  number  of  deaths  from  each 
disease  and  expected  case  fatality  rates:  Typhoid,  700;  measles,  11,000; 
tuberculosis  (pulmonary),  G,0^1.  Incomplete  reporting  probably  ac- 
counts for  the  difference  between  estimated  number  of  cases  and  those 
actually  reported.  Use  the  estimated  number  of  cases  to  compute  case 
fatality  rate. 

(9)  Fill  out  the  enclosed  death  certificate  with  a  primary  and 
contributing  cause  of  death. 

(10)  Fill  out  the  enclosed  birth  certificate. 

(11)  Criticize  the  following  causes  of  death: 

Typhomalarial  fever 

Influenza 

Fracture  of  skull 

Eheumatism 

Ptomaiu  poisoning 

Uremia 

Gangrene 

Cardiac  dilatation 

Cancer 

Apoplexy 

Paralysis 

Convulsions 

Hemorrhage 

Peritonitis 

Senility 

Cerebrospinal  meningitis 

Appendectomy 

Septicemia 

Beference : — Physicians'  pocket  manual  to  the  International  List  of 
Causes  of  Death.  Bureau  of  the  Census,  Government  Printing  Office, 
"Washington,  D.  C. 


SIX  KULES  OF  BEBTILLON  FOR  PROPER  CLASSIFICATION   OF   CAUSES   OF  DEATH 

1.  If  one  of  the  two  diseases  is  an  immediate  and  frequent  com- 
plication of  the  other,  the  death  should  be  classified  under  the  head  of 
the  primary  disease.     Example: — 


1496     COUESE  IX  PEEVEXTIVE  MEDICINE  AXD  HYGIENE 

Scarlet  fever  and  diphtheria,  classify  as  scarlet  fever. 

2.  If  the  preceding  rule  is  not  applicable  the  following  should  be 
used.  If  one  of  the  diseases  is  surely  fatal  and  the  other  is  not  of  such 
gravity,  the  former  should  be  selected  as  the  cause  of  death.    Example : — 

Pulmonary  tuberculosis  and  puerperal  septicemia,  classify  as  tuber- 
culosis. 

3.  If  neither  of  the  above  rules  is  applicable,  then  the  following: 
If  one  of  the  diseases  is  epidemic  and  the  other  is  not,  choose  the  epi- 
demic disease.     Example : — 

Measles  and  biliary  calculi,  classify  as  measles. 

4.  If  none  of  the  three  preceding  rules  is  applicable,  the  following 
may  be  used :  If  one  of  the  diseases  is  much  more  frequently  fatal  than 
the  other,  then  it  should  be  selected  as  the  cause  of  death.    Example : — 

Pericarditis  and  appendicitis,  classify  as  pericarditis. 

5.  If  none  of  the  four  preceding  rules  applies,  then  the-  following : 
If  one  of  the  diseases  is  of  rapid  development  and  the  other  is  of  slow 
development,  the  disease  of  rapid  development  should  be  taken.  Ex- 
ample : — 

Cirrhosis  and  angina  pectoris,  classify  as  angina  pectoris. 

6.  If  none  of  the  above  rules  applies,  then  the  diagnosis  should  be 
selected  that  best  characterizes  the  case.    Example : — 

Saturnism  and  peritonitis,  classify  as  saturnism. 

VII 

Diphtheria  Diagnosis 

COLLECTIOlSr    OF   SPECHVIEN" 

Material  Necessary. —  (1)  Sterile  swabs — iron  wire  is  better  than 
wooden  sticks.  The  latter  may  break,  or  if  heavy  enough,  may  be  too 
thick  to  use  in  the  nose. 

(2)  Clean  slides. 

(3)  Tubes  of  Loeffler's  serum  medium. 

Method  of  Collection. — The  swab  is  rubbed  gently  but  firmly  against 
any  visible  membrane  on  the  tonsils  or  pharynx,  a  rotary  motion  being 
given  to  the  swab  at  the  same  time.  The  swab  is  immediately  inserted 
in  the  blood  serum  tube  and  rubbed  back  and  forth  several  times  over 
the  whole  surface  of  the  medium,  again  rotating  the  swab.  Care  should 
be  taken  not  to  break  the  surface  of  the  blood  serum.  Then,  from  the 
same  swab  or  from  a  fresh  swab,  make  smears  on  a  slide  for  direct 
examination.     Eeturn  the  swab  to  its  tube  and  sterilize  the  whole. 

It  is  advisable  to  take  a  culture  from  the  nasal  cavities  after  first 
cleansing  them  with  a  spray  of  sterile  normal  salt  solution.    It  is  well 


COURSE  IN  PREVENTIVE  MEDICINE  AND  HYGIENE     1497 

to  keep  in  mind  that  B.  diphtheriae  may  cause  infections  of  any  of  the 
mucous  membranes,  the  order  of  incidence  being  pharynx,  larynx,  nasal 
cavities,  conjunctiva,  middle  ear,  and  genital  organs. 

Treat  iitciit  of  Specitnen.  Collected — Direct  Smear. — Make  three 
smears  directly  from  the  swab,  dry  them  in  air,  fix  and  stain  with  Loef- 
fler's  methylene  blue  stain,  Neisser's  stain,  gram  stain.  The  absence  of 
diphtheria  bacilli  must  not  be  assumed  if  negative  results  are  obtained, 
as  they  often  pass  unrecognized  if  mixed  with  a  number  of  other 
organisms.  Only  if  numerous  gram  positive  bacilli,  staining  irregularly 
with  Loeffler's  methylene  blue  and  showing  typical  granules  with  Neis- 
ser's stain,  are  obtained  is  one  Justified  in  making  a  diagnosis  from 
direct  smear.  In  all  cases,  culture  should  be  resorted  to  for  confirma- 
tion. 

Culture. — Place  the  culture,  made  as  above,  at  37°  C.  as  quickly  as 
possible.  If  no  incubator  is  available,  an  inside  vest  pocket  will  serve. 
On  Locffler's  serum  diphtheria  bacilli  usually  outgrow  all  other  throat 
forms  (except  staphylococci)  within  18  hours. 

Examination  of  Culture. — B.  diphtheriae  grows  on  Loeffler's  serum 
media  in  large,  round,  elevated,  yellowish  or  grayish-white  colonies,  with 
opaque  center  and  an  irregular  periphery;  the  surface  is  moist.  Re- 
move some  of  the  growth  with  a  sterile  platinum  loop,  and  make  a  smear, 
dry,  fix  and  stain  with  Loeffler's  methylene  blue.  Neisser's  stain  and 
Gram  stain.  Animal  inoculation  may  be  resorted  to  to  prove  the  pres- 
ence of  virulent  diphtheria  bacilli.     This  will  be  demonstrated. 


THE    SCHICK   TEST 

Object. — To  determine  the  presence  or  absence  of  diphtheria  anti- 
toxin in  the  blood  of  the  subject  under  test. 

A  minute  quantity  of  toxin  (1/50  M.  L.  D.)  is  injected  tn/racutane- 
ously  and  a  local  reaction  follows  if  there  is  less  than  1/30  of  a  unit 
of  antitoxin  per  c.  c.  of  blood.  The  explanation  of  the  test  is  that  when 
antitoxin  is  present,  the  toxin  is  neutralized  and  no  injury  to  the  tis- 
sues occurs.  A  negative  reaction  therefore  indicates  the  presence  of  anti- 
toxin (immunity).  A  positive  reaction  indicates  the  absence  of  anti- 
toxin {susceptibility). 

Diphtheria  toxin  is  diluted  so  that  0.1  c.  c.  equals  1/50  of  .the  M. 
L.  D.  for  a  250-gram  guinea-pig.  This  amount  (0.1  c.  c.)  is  injected 
with  alec,  syringe  and  fine  needle  t/«fracutaneously  on  the  flexor  sur- 
face of  the  forearm  or  arm.  A  good  guide  for  the  insertion  of  the 
needle  into  the  proper  layer  of  the  skin  is  to  be  able  to  see  the  oval  open- 
ing of  the  needle  through  the  superficial  layers  of  the  epidermis. 
A  properly  made  injection  is  recognized  by  a  distinct  wheal-like  eleva- 
tion^  which  moves  with  the  skin,  and  shows  the  prominent  openings  of 


1498     COURSE  IX  PKEYEXTIYE  MEDICIXE  AND  HYGIENE 

the  hair  follicles.     The  results  of  the  test  should  be  read  and  noted 
daily. 

The  reaction  that  results  at  site  of  injection  may  be  either  positive, 
negative,  pseudo,  or  combined  positive  and  pseudo. 

(1)  Positive. — Trace  of  redness  in  12  to  2-4  hours.  Distinct  in 
24  to  48  hours.  Eeaches  height  on  3rd  to  4th  day.  Leaves  circumscribed 
scaling  area  of  brownish  pigmentation  which  persists  for  3  to  6  weeks. 

(2)  Negative. — No  reaction  at  site  of  inoculation. 

(3)  Pseudo. — Local  anaphylactic  response  of  the  tissue  cells  due 
to  the  protein  substances  ^^hich  are  present  in  the  toxic  broth  used  for 
the  test.  Reaction  appears  early — in  from  6  to  18  hours — reaches  its 
height  in  36  to  48  hours,  disappears  on  the  3rd  or  4th  day.  There 
is  generally  no  scaling.  At  its  height,  the  pseudo  reaction  shows  vary- 
ing degrees  of  infiltration  and  appears  as  a  small  central  area  of  dusky 
redness  with  a  secondary  areola,  which  gradually  shades  off  into  the 
surrounding  skin.  The  reaction  may  also  have  a  rather  uniform  appear- 
ance and  be  two  to  three  times  the  size  of  a  true  reaction.  Compare 
with  control. 

(4)  Comhined. — Positive  and  pseudo  reaction  in  the  same  indi- 
vidual. The  central  area  of  redness  is  larger  and  better  defined,  the 
amount  of  infiltration  is  also  more  marked,  a  definite  area  of  scaling 
brovmish  pigmentation  is  observed  after  the  pseudo  element  has  disap- 
peared in  the  test. 

Pseudo,  combined  and  doubtful  reactions,  in  the  absence  of  suitable 
controls  should  be  regarded  as  positive  to  be  on  the  safe  side. 

Control. — With  toxin  heated  to  80°  C.  for  30  minutes,  or  with 
toxin  neutralized  with  antitoxin,  to  help  interpretation. 


VIII 

Classification  of  Pneumococci 

Make  smear  preparations  of  pneumonia  sputum.     Stain  for  capsule 
by  Hiss  Method  and  Gram  Method. 

Hiss  Method. — Preparations  are  made  by  mixing  suspected  material 
with  a  drop  of  animal  serum,  preferably  beef  blood  serum,  on  a  cover 
slip.     Dry  in  air  and  fix  by  heat.     Stain  for  a  few  seconds  with  fuchsin : 
Saturated  alcoholic  fuchsin  (or  gentian  violet)  5  c.  c. 
Distilled  water  95     " 

The  cover  slip  is  flooded  with  the  dye  and  the  preparation  held  over  a 
Bunsen  flame  for  a  second  until  it  steams.  Wash  off  dye  with  20  per 
cent,  aqueous  copper  sulphate  solution.  Blot  (do  not  wash),  dry  and 
mount. 


COURSE  TN  PREVENTIVE  MEDICINE  AND  HYGIENE     1409 

Isolation  of  the  Pneumococcus— .1  / v/-// ">•  .]ff(Uuni. — Meat  infusion 
broth  0.3  to  0.5  per  tent,  acid  to  plicnolplithalein  containing  1  per  cent. 
glucose  and  5  per  cent,  defibrinatcd  ral)l)it  blood,  'i'bis  is  distributed 
into  test  tubes  in  5  c.  c,  quantities.  A  tube  of  this  medium,  or  a  mouse, 
is  inoculated  Avitb  washed  sputum.  The  Avery's  medium  should  be 
incubated  6  to  8  hours  and  the  tube  centrifuged  at  low  speed  to  throw 
out  blood  rells.  The  supernatant  fluid  is  tested  in  the  same  manner  as 
described  for  peritoneal  washings  from  the  mouse.  The  Avery  method 
is  applicable  only  when  mice  are  not  obtainable. 

Each  group  will  autopsy  the  mouse  inoculated  the  previous  day 
with  pneumonia  sputum.  The  peritoneal  cavity  should  be  opened  and 
the  free  fluid,  if  any,  pipetted  into  a  small  test  tube.  The  peritoneal 
cavity  should  then  be  washed  with  about  3  c.  c.  of  sterile  saline  and 
the  washings  added  to  the  peritoneal  fluid.  This  gives  a  suspension 
of  the  organisms  present  in  the  peritoneal  cavity.  Plant  cultures  on 
blood  serum  from  the  hearts'  blood  and  incubate.  Make  smear  prep- 
arations from  hearts'  blood  and  stain  as  above. 

Centrifuge  the  peritoneal  washings  for  five  to  ten  minutes  at  high 
speed.  Pipet  olf  (using  capillary  pipet)  the  clear  supernatant  fluid 
for  use  in  the  precipitin  test.  Resuspend  the  sediment  in  3  c.  c.  salt 
solution  for  use  in  the  agglutination  test. 

Ag'glutination  Test. — Into  five  small  tubes  in  a  rack  add  as  follows : 

1/30  dilution  of  Type  I  serum 
undiluted  Type  II  serum 
1/10  dilution  Type  II  serum 
1/10  dilution  Type  III  serum 
sterile  ox  bile 

Add  0.5  c.  c.  of  the  bacterial  suspension  obtained  from  the  peritoneal 
washing  to  each  tube. .  Incubate  at  37.5°  C.  for  one  hour.    Note  t^-pe  of 
pneumococcus  present  and  lysis  in  the  bile  tube.    Record  result. 
Precipitin  Test. — Into  four  small  tubes  in  a  rack  add  as  follows: 
Tube  No.  1 — .5  c.  c.  1/15  dilution  of  Type  I  serum 
"       '•     2 — .5  c.  c.  undiluted  Type  II  serum 
"       "     3 — .5  c.  c.  1/5  dilution  Type  II  serum 
"       "     4— .5  c.  c.  1/10  dilution  Type  III  serum 

IX  . 

Meningococcus  Isol-a.tiox  axd  Carrier  Detection 

Obtain  material  on  a  swab  from  the  posterior  nasopharynx  (adenoid 
region)  ;  plate  directly  from  the  swab,  and  after  24  hours'  incubation  of 
the  inverted  plate,  make  presumptive  slide  agglutination  tests  with  spe- 
cific sera  and  suitable  controls,  using  colonies  fished  directly  from  the 


Tube 

No. 

1— 

.5 

c. 

c. 

(( 

u 

0 

.5 

c. 

c. 

(( 

a 

3— 

.5 

c. 

c. 

(C 

a 

4— 

.5 

c. 

c. 

a 

u 

5 — 

.5 

c. 

c. 

1500     COURSE  IN  PEEVENTIVE  MEDICINE  AND  HYGIENE 

plates.  The  dried  drops  are  later  fixed  and  stained  to  determine  whether 
the  org-anism  is  a  gram  negative  diplococcns.  Wliere  time  and  ma- 
terial are  available,  this  technique  is  elaborated. 

Swabbing. — In  skilled  hands  the  "open"  swab  may  be  successfully 
employed,  but  the  use  of  the  West  tube  is  recommended.  The  swab  must 
not  touch  lips,  tongne,  tonsils,  etc.  The  mucous  material  on  the  tip 
of  the  swab  is  inoculated  by  touching  the  surface  of  the  special  medium 
in  a  Petri  dish.  The  material  is  then  spread  over  the  surface  with  a 
platinum  wire  or  it  may  be  spread  directly  with  the  swab.  The  plates 
•should  be  immediately  incubated  in  the  inverted  position.  Cooling  of 
the  plates  and  delay  in  incubation  diminishes  the  number  of  successful 
isolations  of  the  meningococcus. 

Examination  of  Plate  Cultures. — The  colonies  of  the  meningococcus 
are  small  and  delicate.  They  are  convex,  glistening,  translucent,  and 
as  they  grow  older  tend  to  become  opaque  in  the  center.  The  young  colo- 
nies may  be  confused  with  those  of  Diplococcus  crassus,  Micrococcus 
catarrhalis,  Diplococcus  pharyngis  flavus,  Diplococcus  pharyngis  siccus, 
and  some  Streptococci.- 

Presumptive  Slide  Ag-g-lutination  Test. — Drop  A  is  a  1/10  dilution 
of  polyvalent  meningococcus  serum.  Drop  B  is  a  1/10 
dilution  of  normal  horse  serum  (control).  Drop  C  is 
0.85  per  cent,  salt  solution  (control). 

Three  drops  are  placed  on  a  microscopic  slide  as 
shown.  The  suspected  colony  is  fished  and  the  plat- 
inum wire  is  dipped  into  each  drop  to  permit  part  of 
the  colony  to  wash  off  into  it.  In  doing  this,  dip  first 
into  drop  C,  then  into  drop  B,  and  finally  into  drop 
A.  Burn  the  wire  and  after  it  has  cooled,  emulsify 
the  material  in  each  drop  thoroughly  working  in  the 
same  direction.  Agglutination  in  A  and  none  in  B  and 
C  is  presumptive  for  meningococcus.  Any  other  reac- 
tions are  negative  and  indicate  one  of  the  other  organ- 
isms. The  slide  can  be  stained  by  gram  to  verify  the 
morphology  and  staining  characteristics  of  the  organism  present. 

Macroscopic  Ag-glutination. — To  1  c.  c.  quantities  of  the  emulsion 
in  five  tubes  add: 

(1)  To  the  first  tube,  1  c.  c.  of  a  1/100  dilution  of  normal  type 
meningococcus  serum, 

(2)  To  the  second  tube,  1  c.  c.  of  a  1/100  dilution  of  paramen- 
ingococcus serum. 

(3)  To  the  third  tube,  1  c.  c.  of  a  1/50  dilution  of  Rockefeller 
polyvalent  antimeningococcic  serum. 

(4)  To  the  fourth  tube,  1  c.  c.  of  a  1/10  dilution  of  normal  horse 
serum  (control). 


COURSE  IN  PREVENTIVE  MEDICINE  AND  HYGIENE     15U1 

(5)      To  the  fifth  tuho,  1  c.  c.  salt  solution  (control). 
Incubate  at  37°  C.  for  3  hours. 

Interpretation. — Agglutination  in  tul)os  1  and  3  =  meningococcus 
(normal). 

Agglutination  in  tubes  2  and  )>  =  ])ara meningococcus. 

Agglutination  in  tube  3  =  meningococcus    (intermediary). 

Agglutination  in  all  tubes,  in  none,  or  in  either  of  the  two  controls 
is  negative  for  meningococcus. 

A.  Each  student  will  take  a  West  swab,  and  after  swabbing  the 
nasopharynx  of  his  neighbor,  plate  the  material  as  directed,  and  after 
marking  the  plate  for  identification,  will  put  it  in  the  incubator  in  the 
inverted  position. 

B.  The  student  will  at  this  point  acquaint  himself  with  the  char- 
acter of  the  meningococcus  colonies  by  studying  the  plates  of  pure  cul- 
tures of  meningococci  and  plates  containing  mixed  cultures. 

C.  Students  will  at  this  point  make  a  series  of  macroscopic  slide 
agglutination  tests  to  acquaint  themselves  with  the  technique  of  the 
procedure,  using  colonies  from  the  plates  containing  pure  cultures  of 
meningococci.  They  will  then  proceed  to  make  fishings  of  suspicious 
colonies  from  the  mixed  plates,  and  having  identified  a  colony  by  the 
presumptive  test,  they  will  fish  it  to  a  blood  agar  slant.  Mark  for  iden- 
tification and  incubate. 

D.  Students  will  set  up  three  sets  of  five  tubes  as  directed  and 
using  the  meningococcus  emulsions  marked  X,  Y,  and  Z,  will  determine 
to  which  group  they  correspond. 

E.  Study  plates  put  in  incubator  at  the  previous  period. 


Sanitary  Survey  of  a  City  or  Town 

Each  student  is  required  to  make  a  sanitary  survey  of  a  city  or  town, 
based  on  the  following  outline,  and  submit  a  written  report  of  the  same. 
The  report  should  consist  of:  (a)  data,  (b)  interpretation  of  the  facts, 
and  (c)  criticisms  and  recommendations.  In  order  to  receive  credit 
this  year,  the  sanitary  survey  must  be  handed  in  not  later  than  May 
15th. 


Introduction — General 

description 

of  the  town 

including 

(a) 

History 

(b) 

Geographical 

position 

(c) 

Topography 

(d) 

Climate 

1502     COUESE  IN  PEEVENTIVE  MEDICINE  AND  HYGIENE 

(e)  Geology 

(f)  Population   (number  and  constitution) 

(g)  Urban,  suburban  or  rural 

(h)      Organization  of  the  board  of  health 
(i)     Other  information  about  the  town. 

Water. — 

(a)  The  water  shed — sources  of  pollution,  methods  of  collection, 

storage,  purification 

(b)  An  analysis  of  the  water  and  its  interpretation. 

(c)  Public  or  private  wells 

(d)  Examine  a  sample  of  the  water  in  the  laboratory. 

Sewage. — 

(a)  System  of  disposal — if  purified  or  treated,  how?. 

(b)  Efficiency 

(c)  Eelation  to  health  of  this  and- other  towns 

(d)  Criticism  of  system. 

Garbage,  Refuse,  Ashes. — 

(a)  Method  of  collection 

(b)  Disposal 

(c)  Eelation  to  health 

(d)  Criticism  of  methods. 

Vital  Statistics. — 

(a)  Death  rate 

(b)  Infant  mortality 

(c)  Specific  rates  for: 

(1)  Typhoid 

(2)  Tuberculosis 

(3)  Measles 

(4)  Scarlet  fever 

(d)  Submit  samples  of  blanks  used  by  the  department  of  health, 
especially  those  for  deaths,  births,  marriages,  and  notifiable 
diseases.  Fill  out  a  death  certificate.  State  opinion  as  to 
thoroughness  of  reporting  morbidity,  mortality  and  other  vital 
statistics. 

Milk.— 

(a)  Report  on  the  sanitary  conditions  of  one  farm  and  one  city 
dairy,  using  score  cards 

(b)  Amount  of  milk  pasteurized  and  by  what  method 
Criticism 

(c)  Amount  of  milk  '^certified."  If  possible,  visit  and  report  on 
farm  producing  it. 


COURSE  IN  PREVENTIVE  MEDICINE  AND  HYGIENE     1503 

(d)     Examine  a  sample  of  milk  in  the  laboratory 
Interpret  result. 

Saniiary  Nuisances. — 

(a)  Source  of  odors 

(b)  Dust — causes  and  method  of  prevention 

(c)  Rubbish  and  general  cleanliness.     Empty  lots.     Dumps 

(d)  Flies  and  mosquitoes 

(e)  Rats  and  vermin 

(f)  Stables  and  manure 

(g)  Breeding  places  of  mosquitoes 
(h)  Smoke 

(i)     Unnecessary  noises 

(j)     Piggeries,  etc. 

(k)     Legal  definition  of  "nuisance"  and  method  of  abatement. 

Industrial  Hygiene. — 

(a)     Report  upon  one  industry  based  upon  a  visit  to  a  factory  or 
workshop. 

Housing. — 

(a)  Sanitary  condition  of  one  tenement 

(b)  Ventilation  of  one  large  building. 

Communicable  Diseases. — 

(a)  Give  a  list  of  the  diseases  notification  of  which  is  required 
by  the  board  of  health 

(b)  Quarantine  regulations 

(c)  Methods  of  disinfection  and  fumigation 

(d)  What  measures  are  taken  to  prevent  the  spread  of  tuberculosis? 

(e)  Should  some  other  disease  be  prevalent,  what  measures  are 
taken  to  control  it? 

(f)  Venereal  diseases,  reporting  and  control. 

Schools.^ 

(a)  Visit  and  report  on  one  school — ventilation,  lighting,  tempera- 
ture, playgrounds,  etc. 

(b)  Medical  inspection  of  school  children.     How  conducted? 

(c)  Diseases  for  which  children  are  excluded  from  school.  ' 

Miscellaneous. — 

(a)  Markets 

(b)  Provision  stores  and  soda  fountains 

(c)  Slaughter  houses  and  meat  inspection 

(d)  Cold  storage  plants 


1504     COITESE  IN  PEEVE^^TIVE  MEDICINE  AND  HYGIENE 

(e)  Kitchens  of  hotels  and  restaurants 

(f)  Wharves 

(g)  Barber  shops 

(h)     Distribution   of  educational  and  other  pamphlets 

(i)  Other  activities  of  the  board  of  health,  as  maintenance  of  diag- 
nostic laboratory,  meat  inspection,  etc. 

(j)      District  nursing  and  social  service 

(k)  Charitable  institutions  or  organizations  of  importance  to  pub- 
lie  health  such  as  Antituberculosis  Association,  Red  Cross, 
Baby  Hygiene,  Milk  Stations,  Public  Health  Nursing,  Health 
Center,  Prenatal  or  Maternity  Work,  Hospitals  for  Com- 
municable Diseases,  and  other  health  activities 

(1)      City  planning 

(m)     Food  and  drug  administration. 

General  Summary  of. —  '      • 

(a)  Conditions  found 

(b)  Criticisms 

(c)  Eecommendations. 


INDEX 


Abattoir,  819 
Abba,  995 
Abbott,   491,  950 
Abbott,  E.  S.,  455,  456 
Abderhalden,   492 
Abortion,  477 

lead  poisoning,   1296 
Abrin,  554 

Acanthocephala,  in  soil,  1013 
Accidents,  alcohol  and,  491 

blindness,  94 

industrial,    1290 

sewer  gas,  949,  954 
Acetone,   268 
Acetyleholin,    724 
Acevodo,  66 
Acharde,   137,   702 
Achorion   quincker.ium,    1323 
Achorion  schonleinii,  1323 
Acidosis,   759,   875 
Acids,  disinfection,  1422 
Aeidum   earbolicum,   1409 
Aekermann,  856 
Acland,  T.  D.,  22,  38 
Acriflavine,    1422 
Actinomycosis,  828 
Acute  coryza,  246 
Acute    infectious   jaundice,    335 

prevention,   337 

relation  to  rat,  336 

spirochete,   336 

transmission,   336 
Adams,  411 
Adams,  C.   F.,  1439 
Adaptation,  mental,  440 
Addiction,   drug,  486 
Adeps  lanae  hydrosus,  82 
Adjustments,  mental,  440 

in  civil  life,  441 
Adulteration,   foods,  725 
definitions,   725 
examples,    725 

milk,   810 
Aedes  calopus,  295 
Agaricug  campestris,  858 
Agaricus  muscarius,  860 
Agglutination,    589 

in  cerebrospinal  fever,  257 

in  glanders,  398 


Agglutination,    Micrococcus    melitensis 
and,  410 
milk,    776 
pneumococci,  1499 
Agglutinins,  589 

Agramont*,  A.,  259,  264,  296,  304 
Air,  865 

alveolar,  867 
ammoniacal  vapors,  946 
bacteria,  936 

methods  for  determining,  938 
carbon  disulphid,  947 
carbon   monoxid,  941 
coal  gas,  944 
cold,  effects  of,  911 
composition,   865 

ammonia,  872 

argon,   869 

carbon   dioxid,  872 

hydrogen  peroxid,  871 

mineral  acids,  872 

nitrogen,    869 

oxygen,  867 

ozone,   869 
cool,  effects  of,  913 
currents,   893 
damp,  effects  of,  911 
dead-space,  970 
disinfection,   1427 
dry,  effects  of,  912,  913 
filtration,  Petri  method,  938 
fresh,  955 
functions,   866 
Haldane  apparatus,  878 
humidity,  896 

hydrochloric  acid  vapors,  946 
hydrogen  sulphid,  947 
illuminating  gas,  944 
infection,   939 
methane,   946 
moist,  effects  of,  910 
movements,   891 
physical   changes,   960 
poisonous  gases,  941,  960 
Eettger's  method,  939 
samplers,  878 
sevrer,  950 
soil,   996 
sulphur  dioxid,  949 


1505 


1506 


INDEX 


Air,  supplemental,  970 

temperature,  893 

tidal,  970 

warm,  effects  of,  910,  912 

water    gas,    944 

See  also  Ventilation;    Vitiated  air 
Air-borne  infections,  infantile  paralysis, 
392 

measles,  216 
Air   ducts,   977 
Air   washing,   968 
Aitken,  930 
Aitken,  J.,  935 
Alanin,  720 
Alastrim,  25 
Albert,   113 
Albinism,  649 
Alcohol,    486,   487 

accidents  and,  491 

blindness,  94 

crime  and,  492 

disinfection,    1423 

effect,  on  digestion,  487 
on  nervous  system,  488 
on   pulse,   490 
on   reflex,   490 
on   temperature,   490 

efficiency   and,   489 

ethyl,   268,  487 

as  a  food,  487 

heredity  and,  492 

idiots  and,  431 

immunity  and,  546 

infant  mortality  and,  481 

local  irritating  action,  487 

in  medicine,  492 

mental  deficiency  and,  430 

and  mental  diseases,  429 

methyl,  94,  268 

pneumonia  and,  235 

poverty  and,  492 

psychoses  and,  429,  437,  439 

references,    492 

resistance  to  disease  and,  491 

as  a  stimulant,  489 

summary,   492 

uses,   492 

venereal  disease  and,  94,  491 

wood,  94 

See  also  Alcoholism 
Alcoholic  deterioration,  429 
Alcoholic  hallucinosis,  429,  489 
Alcoholism,  conception  and,  431 

epilepsy  and,   655 

hereditary  transmission,  654 

prevalence  of  psychoses  and,  429 

prohibition  and,  433 

psycho-analysis,  432 

treatment,  432 


Aleppo  boil,  381 
Algae,  1051,  1054 

in  water,  1144 
Allan,  1180 
Allantiasis,   706 
Allbutt,  38 

Alleghany  typhoid  epidemic,  1178 
Allen,  K.,  1217 
Allergie,  definition,  523 
Allergy,   593 
Altitude,  888 

Alum,  water  purification,  1141 
Aluminium  sulphate,  1141 

disinfection,  1395 
Alveolar  air,  867 

carbon  dioxid,  874 
Amanita  muscaria,  858 
Amanita  phalloides,  858,  859 
Amanitotoxin,  858 
Amboceptor,   551,  577 
Ambrine,  1413 
Aniebiasis,   150 
Amebic  dysentery,  150 
Amebic  hepatitis,  150 
Amino-acids,  719 
Ammonia,  268,  872 
Ammoniacal  vapors,  946 
Amoss,   H.  L.,  391,  393,  394,  600,  960 
Amylase,   761 
Anaboena,  1051 
Anaphylactoid  reactions,  605 
Anaphylaxis,  593 

anaphylactoid  reactions,  605 

Arthus  phenomenon,  596 

bacterial  proteins,  601 

definition,    523 

diphtheria  antitoxin  and,  208 

drugs,   605 

eczema,  604 

endotoxins,  602 

examples,  594 

experimental,  594 

food  idiosyncrasies,  604 

hay  fever,  605 

hereditary  transmission,  654 

plant  foods,  854 

protein  metabolism,  601 

rose  colds,  605 

sensitization,  feeding,  598 
manner,  599 

serum,  594,  598 

specificity  of  reaction,  596 

transmission,  maternal,  598 

tuberculosis  and,  178,  602 

vaccination,  603 
Ancylostoma  ceylanicum,  154 
Ancylostoma  duodenale,  154 
Ancylostomiasis,  153 
Anderson,  778 


INDEX 


i5or 


Anderson,  J.  F.,  22,  100,  174,  178,  208, 
212,  215,  26;-),  372,  373,  390,  392, 
561,  600,  1367,  1371 
Anderson,  W.  G.,  876 
Anderson    process,    water    purification, 

1143 
Andrejew,  597 
Andrews,  J.  B.,  1303,  1304 
Andrews,  .1.  M.,  1282,  1283. 
Andrews,   V.   L.,   1265 
Anoniomctcrs,  893 
Anpelioi,  962 
Angstrom  unit,  1375 
Anilin  oil,  268 
Anilin  poisoning,  1310 
Animal  antitoxins,  560 
Animal  foods,  753 
Animal  parasites,  525,  1181 
Animals,  goiter,  1153 

as  sources  of  infection,  459 
Annette,  H.  E.,  746 
Annoto,  727 

Anopheles  albimanus,  288 
Anopheles  albipes,  288 
Anopheles  argjTotarsus,  288 
Anopheles  costalis,  288 
Anopheles  cruciens,  288 
Anopheles  maculipennis,  288 
Anopheles  mosquito,  288 

flight,  290 

habits,  289 

suppression,  291 

temperature  relation,  289 
Anopheles  nigerrinus,  306 
Anopheles  pseudopunctipennis,  288 
Anopheles  punctipennis,  288 
Anopheles  quadrimaculatus,  288 
Anopheles  sinensis,  288 
Anophelinae,  287,  288 
Anoplura,  362 

Anthracosis,  927,  931,  1314,  13,19 
Anthrax,  401,  1322 

carcasses,  disposal  of,  402 

disinfection,  403 
bristles,  404 
hair,    403,    404 
hides,  404 
pigs'  wool,  404 
wool,  403,  404 

flies  and,  402 

immunity,  529 

malignant  pustule,  401 

meat  and,  827 

prevention,  402 

resistance  of  spore,  402 

Sevmour-Jones   method,   403,   404 

shaving  brushes   and,   402-404 

soil,  1008 

wool-sorters'  disease,  401 


Antianaphylaxis,  603 
Antibiosis,  525 

disinfection,  1354 

water   purification,   1110 
Antibodies,  524 
Antiformin,  1421 
Antigen,  521,  580 

in   glanders,   399 
Antiscorbutics,  685 
Antiseptics,  definition,  1351 
Antitoxic  immunity,  553 
Antitoxins,  557 

animal,  560 

bacterial,  560 

botulinus,   715 

diphtheria.    See  Diphtheria  antitoxin 

ferment,  560 

mode  of  action,  563 

plant,  560 

preparation,  561 

standardization,    565 

tetanus.     See  Tetanus  antitoxin 
Anti-tuberculosis  associations,   183 
Aphthous  fever,  405 
Appert,   738 
Apples,  evaporated,  734 
Aquaphones,  1020 
Aquasphere,   865 
Aqueous  vapor,  896 
Aragao,  320 
Arbenz,   853 

Arctomvs  bobac,  326,  344 
Areola,   in   vaccination,   12 
Argon,  869 
Argj-rol,   82 
Aristotle,   1015 
Arms,  196,  398 
Armstrong,  707 
Armstrong,  D.  B.,  164 
Arm-to-arm  vaccination,  5 
Arning,    414 

Arnold  steam  sterilizer,  1381 
Aron,  680 
Aronovitch,  703 
Aronson,  914 
Arrhenius,   563,  564 
Arsenate  of   lead,   276,   277 
Arsenate  of  lime,  277 
Arsenic,  276,  341,  749,  1305 

in  beer,  1306 

dips,   355 

in   fur,   1305 

in  glucose,  1306 

sprays,  279 
Arsenical  poisoning,   1305 
Arsenious  oxid,  276 
Arseniuretted  hydrogen,  1306 
Artesian  wells,  1037 
Arthus   phenomenon,   596 


1508 


INDEX 


Asaprol,   1413 

Ascaris,   159 

Ascaris    lumbricoides,    1012,    1181 

Asehaffenberg,  G.,  431 

Aschenheim,  E.,  917,  918 

Aseoli,  587 

Asepsis,   definition,   1352 

Aseptol,  1412 

Ash,  867 

Ashburn,  264,  304,  1482 

Ashes,  1219 

amount,  1219 
Ashford,  156,  160 
Ashland  tj'phoiS  epidemic,   1175 
Asiatic  cholera,  139 
Asitia,  674 
Asopia  farinalis,  265 
Aspartic  acid,   720 
Asterionella,  1051 
Asthma,  600 
Astigmatism,  922 
Atavism,  628 
Atchinson,   562 
Atmosphere,  865 
Atmospheric    pressure.      See    Pressure, 

atmospheric. 
Atoxyl,   319 

Attitude,  emotional,   448 
of  children,  448 

typhoid  fever,  105 
Atwater,   664,   667 
Atwood,  C.  E.,  436 
Auer,  596 
Austin,  236 
Australene,   268 
Autoclave,    1381 
Autohemolysins,  585 
Autovaccination,  21 
Auzinger,  808 
Avery,  0.  T.,  239 
Avery's  medium,  1499 
Axtell,   W.   H.,   150 
Ayres,  L.  P.,  1350 
Azobacter,  1001 

Babcock,  687,   755,   760 
Babcock  method,  799,  800 
Babes,  47,  49,  50,  54 
Babesia  bigemina,  356 
Babinski,  443 
Baby  week,  476 
Bachhuber,  1296 
Bacillary  dysentery,  148 
Bacilli : 

B.  abortus,  410 

B.  aerogenes,  in  water,- 1091 

B.  aerogenes  capsulatus,  1009 

B.  aertrycke,  702 

B.  anthracis,  314 


Bacilli : 

B.  Bordet-Gengou,   225,   227 
B.   botulinus,   710 

antitoxin,  715 

differentiation  B.  sporogenes,  711 

in  fish,  8.39 

habitat,  711 

thermal  death  point  of  spore,  712 

toxin,    712,   .553 
B.   bronchiseptieus,   220,   225 
B.  bulgaricus,  769 
B.  cholera  suis,  701 
B.   coli,   841 

in  water,  1091 
B.  diphtheriae,  193,  196 

resistance,  198 
B.  dysenteriae,  148 

resistance,  149 
B.  enteritidis,  701,  703,,  704,  862 
B.  enteritidis  of  Gaertner,  139 
B.   ichthyismi,   839 
-  B.  icteroides,  702 
B.  influenzae,  240 
B.  leprae,  413,  416 
B.  mallei,  .396,  .398 
B.  morbificans  bovis,  701 
B.  paratyphosus  a,   137 
B.  paratyphosus      ,  702 
B.  perfringens,  96,  1009 
B.  pestis,  345,  348 

recognition,  348 
B.  psittacosis,  702 
B.  pyocyaneus,   198 
B.  radicicola,    1001 
B.  rhinitis,   247 
B.  scarlatinae,  220 
B.  sporogenes,    711 
B.  suipestifer,  138,  701,  702,  704 
B.   tuberculosis,   180 
B.  typhi  murium,  343,  702 
B.  typhosus,  109,  116,  314 

in  the  blood,   111 

in  the  feces.  111 

in  ice,  120 

in  nature,  117 

in  the  urine,   111 

in  water,  1094 
B.  welchii,  96,   1009 

in   milk,   797 
proteus-like,  373 
Bacillol,  1413 

Bacillus  carriers.     See  Carriers 
Bacot,    314,   326-328 
Bacteremia,   525 
Bacteria,  air,  936,  938 
cold,   730 

freezing,   730,  1185 
in  milk,  774.  794,  796 
nitrate,    1000 


INDEX 


1509 


Bacteria,  rain  water,  1026 

in  sewer  air,  950 

soil,    1003 

in  vaccine  virus,   7 

in  water,  1087 
Bacterial  antitoxins,  560 
Bacterial  proteins,  601 
Bacterial   vaccines,   535,    1492 

lipovaccines,  536 

polyvalent,  536 

sensitized,   535 

standardization,  536 
Bacteriolysins,  575 
Bacterium  tularense,  321 
Baetjer,  151,  376 
Baginsky,  A.,  1350 
Bailey,  638 
Bailey,  P.,  456 
Bailey,  W.  B.,  1278 
Baillarger,   1010 
Bainbridge,  138,  702 
Baker,  211 
Baker,   J.,   895 
Baker,  M.  K,  1015 
Baldwin,  H.,  748 
Bailey,  117 
Balwin,   602 
Bancroft,  305 
Band  screen,  1200 
Bandi,  349 
Bang,  189 
Bang  method,  189 
Banks,  75,  345 
Barber,  348 
Barbiero  fever,  320 
Barger,  856 
Bargilli,  414 
Barium,  316 
Barium  carbonate,  340 
Barium-formalin  disinfection,  1395 
Barker,  L.  F.,  456,  457 
Barlow's  disease,  683 
Baron,   John,   38 
Barracks,  sanitation,  1469 
Barreto,  296 
Bartel,  173,  174 
Barthel,  C,  813 
Basenon,  701 
Bass,   290,   294,   682 
Bates,  L.  W.,  1307 
Bateson,  622,  626 
Bateson,  W.,   659 
Bats,  mosquitoes  and,  291 
Baumann,  684 
Baumert,  871 
Baume's  law,  646 
Baummann,  724 
Bayliss,  W.  M.,  863,  917 
Beach,  436 


Beaugency  strain,  5 

Beaunian,  724 

Bechamp,  761 

Bechhold,  1411 

Becker,  751 

Beckwith,  395 

Beckwith,  H.  L.,  871 

Bed  linen,  disinfection,   1435 

Bedbugs,   268,   378 

hydrocyanic   acid   gas,   515 

leishmaniasis  and,  382 

life   history,  378 

petroleum  and,  275 

suppression,    379 

table,  264 
Beebe,   1436 
Beef  extracts,  816 
Beef  juice,  816 
Beef   tapeworm,   835,  836 
Beer,  arsenic  in,   1306 
Beers,  C.  W.,  457 
Behavior,  in  mental  diseases,  441 
Behring,    96,    172-174,    200,    210,    558, 

724,  747 
Beitzke,  163 
Bejerinck,   1001 
Bellei  test,  810 
Benda,  1422 
Bendick,  145 
Bendig,  Paul,  69 
Bends,  891 
Benedict,  488,  876 
Benedict,  F.  G.,  873 
Bengston,   I.   A.,   22 
Bensaude,   137,  702 
Benzaldehyd,   268 
Benzidin  test,  810 
Benzin,  276,  1310 
Benzoate  of  soda,  744 
Benzoic  acid,  744,  812 
Benzol,  1310 
Bergenholtz,  386 
Bergey,  491,  959 
Beriberi,    678 

prevention,  682 

rice  and,  681 
Berkefeld  filter,  1127 
Bernard,  971 
Bernard,  C,  957 
Bernouille,  28 
Bernstein,  195 
Bernstein,  C,  456 
Bert,  889 

Bert,   P.,   891,   957 
Bertarelli,  312,  420 
Bertillon's    rules,    1494 
Besredka,  107,  132 
Beu,  959 
Beyer,  296 


1510 


INDEX 


Bezzola,  431 

Bichlorid      of      mercury,      disinfection, 

1406,  1425 
Bienstock,   718 
Biggs,   55,   75 
Biggs,  H.  M.,  526 
Bignami,  287 
Bill,  J.  P.,  934,  1019 
Bill  of  Health,  509 
Billings,  959 
Bine,  R.,  707 
Binet,  Alfred,  610 
Binet's  formula,  610 
Bingham,  A.   T.,  456 
Binnie,   606 
Binot,  936 
Binz,  489,  490 
Bircher,  1155 
Birdseye,  359 
Birth  certificate,  1237 
Birth  rates,  1226,   1238 

crude  formula,  1494 

and  death  rate,  1271 

error,  sources  of,  1239 

factors  influencing,   1241 
Birth  registration,  1235 

area,  U.  S.,  1236 

data,  source,  1236 

information  secured,  1236 

in  the  U.  S.,  1235 

uses,   1240 
Birth  statistics,  1235 

uses,   1240 

See  also  Birth  registration 
Bishopp,  F.  C,  360 
Biskra  button,  381 
Bisulphid   of   carbon,   274 
Bites,  rat,  332 
Bivouac,  1468 
Black  death,  345 
Black  Hole  of  Calcutta,  956 
Blackwater  fever,  294 
Blair,  486 

Blaisdell,  J.   H.,  455 
Blake,   215,   235,  333 
Blanchard,   196,   416 
Blatta  germanica,  383 
Blatta  orientalis,  383 
Blattidae,  383 

Bleaching    powder,    water    purification, 
1132.     See  also  Chlorinated  lime 

disinfection,  1395 
Blindness,  accidents,  94 

preventable,  87 

war  gases,  95 
Bliss,  746 

Blood,  immunity  and,  530 
Blood  tests,  587 
Bob-veal,  846 


Body  linen,  disinfection,  1435 

Boeck,  416 

Bogliolo,  418 

Bohr,  870 

Boiled  water,  1112 

Boiling,    disinfection,    1378 

Boldman,   116,   209,  606,   780 

Bolduan,  C.  F.,  1255 

Bollinger,  846 

Bolton,  98,  195 

Bond,   52,   53 

Boobyer,  1191 

Books,  disinfection,  1435 

Boophilus  bovis,   356 

Borates,  disinfection,  1423 

Borax,   316,   745 

Bordeaux  mixture,  278 

Bordet,  J.,  224,  564,  565,  573,  576,  580, 

581,  591,  606' 
Bordet-Gengou  bacillus,  225,  227 
Bordet-Gengou  phenomenon,  580 
Boric   acid,    745,   812 

disinfection,   1423 
Bosworth,   755 
Botulism,   706 

antitoxin,  715 

cooking,  717 

food  involved,   715 

mortality,   710 

pathology,  710 

prevalence,   706 

prevention,   716 

symptoms,  708 

See  also  Bacillus  botulinus 
Bouley,    50 
Bouton  d 'Orient,  380 
Bovie,  918,  920 
Bovine  malaria,  356 
Bovine    tuberculosis,    Bang    method    of 
suppression,  189 

prevention,  188 
Bowditch,   1330,   1350 
Bowditch,  H.  I.,  911 
Bowditch,  H.  P.,  1339 
Bowley,  A.  L.,  1278 
Boyce,  840 
Boycott,  907,  909 
Boylston,  Zabdiel,  27 
Brachydactylism,  652 
Bradfort,  320 
Bradley,  304 
Brainard,  A.  M.,  483 
Bramhall-Deane  steam  sterilizer,   1382 
Brandeis,  L.  D.,  1288,  1324 
Brandt,  1303 
Branham,  S.   E.,   240 
Brass  founder's  ague,  1311 
Brazilian  trypanosomiasis,  321 
Break  bone  fever,  303 


INDEX 


1511 


Breaudat,  680 

Brehmer,  183,  478 

Bretonneau,  107,  209 

Brieger,  721-723,   725,  844,  958 

Brill,   372 

Brill's  disease,  372 

Brinckerhoff,  31,  345,  412,  413,  417 

Brion,  137,  702,  703 

British  thermal  unit,  984    • 

Broad  street  pump  epidemic,  1161 

Broggi,  1288 

Bromin,  in  disinfection,  1417 

Bronchocele,  1151 

Bronfenbrenner,  J.,  62,  208,  604 

Brooks,  467,  920,  1363 

Brown,  937 

Bro\vn,  J.  H.,  781 

Brown,  Lawrason,  179 

Brown,  W.  H.,  472 

Browu-Sequard,   655,  958,  959 

Browning,   1422 

Brownlee,   242 

Bruce,  264,  320,  407 

Bruck,  57,  123 

Brues,  310,  391 

Bruns,  101 

Bryant,  786 

Bubonic  plague.     See  Plague 

Buchanan,   654 

Buchner,  551,  573,  575 

Buckmaster,   874 

Buckwheat  poisoning,  688 

Budd,  W.,  107,  915 

Biirker,   888 

Buffard,  320 

Buhach  insect  powder,  271 

Bulkley,  61 

BuU,  C.  G.,  103,  593,  1009 

Bullock,   167 

Bulstrode,  842,  845 

Bunge,  489 

Burckhard,   14 

Burdon-Sanderson,  730 

Burke,  711 

Burmeister,  320 

Burnham,  W.  H.,  456 

Butter,  785 

score  card,  786 

test,  787 

and  typhoid  fever,   123 
Buttermilk,    and    typhoid    fever,    123, 

769 
Buxton,  578 
Byam,  376 
Byssinosis,   932,   1314 

Cabot,    43 

Cabot,  R.  C,  1264 

Cadaverin,  723 


Cadavers,  disinfection,  1436 
Cadman,  9()7,  909 
Cicsar,   Julius,   427 
Cagnina,  414 
Cahan,  1303 
Caisson  disease,  890 

prevention,  891 
Calcium  hydroxid,  1416 
Caldwell  crematory,   1478 
Calmette,   45,   173,    177,   179,   180 
Calomel  ointment,  in  syphilis,  65 

venereal  prophylaxis,  82 
Calorie,  664,  985 
Calvert,  H.  T.,  1216 
Camp  sites,  1465 

topography,   1465 
Campaign,    management    of    epidemic. 

See  Epidemics 
Campbell,  211 

Campbell,  C.  M.,  447,  455,  456 
Campers,  disinfection  water,  1420 
Camphor,  268 
Camps,  1465 

bivouac,  1468 

permanent,   1468 

sanitation,    1469 

temporary,  1468 
Camus,  852 
Can  ice,  1187 
Cancer,  1321 

buyo   cheek,   647 

cancerous-like  growth  in   rats,   385 

chimney-sweep  's,  647 

hereditary  transmission,  646 

occupational  disease,  1321 

paraffin   makers,    647 

X-ray  epitheliomas,  647 
Candall,  1395 
Candle  feet,  921 
Candle  meters,  92r 
Canning,  737 

flat  sours,  738 

leaks,    738 

spoilage,  738 

swells,   738 

vitamins  and,  739 
Canteen,   1458 
Carbohydrates,  668 
Carbolic   acid,   268 

disinfection,  1409,  1426,  1433 
Carbolic  coefficient,  1366 

device,   1368 

hygienic  laboratory  method,  1372 

interpretation  of  results,  1372 

table  of  germicides,   1373 

technic,  1370 
Carbon  bisulphid,  274,  947 

in  plague,  275 
Carbon  cycle,  1002 


1512 


INDEX 


Carbon  dioxid,  872 
alveolar  air,  873 
amount  in  air,  873 
effects  of  increased,  957 
Fitz  tester,  885 
Haldane  apparatus,  878 
index  of  vitiation,  876,  877 
lime  water  test,  883 
methods  for  determining,  877 
Petterson-Palmquist  method,  880 
water  siphon  method,  877 
Wolpert  tester,  884 
significance,  877,  957 
soil,  996 
Carbon  disulphid,  268,   1311 
Carbon  monoxid,  941,  1308 
acute  poisoning,  943 
rats   and,   342 
tests,  944 
Carbon  tetrachlorid,  268,  275 
Carey,  472 
Cargo,   518 
Caries,  1344 
Carini,  23 
Carle,  95 
Carlson,  870,  871 
Carmelia,  841 
Carnelly,  876,  950 
Carotin,  853 
Carotinemia,  853 
Carpenter,  304 
Carpenter,  E.   C,  989 
Carrasquillo,  416 
Carrell,   1420 

Carriage,  water,  system  of  sewage  dis- 
posal,  1192 
Carriers,  462,  540 
active,  540 
acute,  540 

cerebrospinal  fever,  254 
cholera,  144 

detection,  145 
chronic,  540 
control,  541 
convalescent,   540 
cure,  462 
diphtheria,  195,  203 

cure,  197 
dysentery,  149 
food  infections,  704 
infantile  paralysis,  391 
intermittent,  540 
intestinal,  540 
isolation,  462 
malaria,   289 
meningococcus,  254 

detection,   1499 
oral,   540 
passive,  540 


Carriers,  pneumonia,  233 
protozoon,  462 
temporary,  540 
tetanus,  97 
transitory,  540 
typhoid,  113 
chronic,   113 
control,  115 
convalescent,   113 
passive,  113 
prevalence,   113 
recognition,  111 
"Typhoid  Mary,"  114 
urinary,  540 
Carroll,  702 

Carroll,  J.,  259,  264,  296 
Cars,  railroad,  disinfection,  1430 
Carter,  265,  294,  301    302,  361 
Casein,  667 
milk,  756 
Castellani,  288,  317,  320,  382,  385,  410, 

411,  536,  592 
Castle,  607,  622,  628,  642 
Castle,  W.  E.,  659 
Castor  bean,  554 
Catalase,  761 
Catalase  test,  808 
Cataract,  653 

Catchment  areas,  care,  1046 
Cathcart,  703 
Cather,  D.  C,  84 
Catlin,  29,  198 
Cattani,  47,  312 
Causes  of  death,  1265 
international  list,  1272 
rules  of  Bertillon,  1494 
Cavendish,  1015 
Caverley,  386 
Cecil,  235,  236 
Cedar   oil,    268 
Celli,  287,  290,  294,  311 
Cellia,  287 

Cellular  immunity,  529 
Ceni,  688 
Census,  989 

data,   sources,   1228 
errors,  sources,  1229 
information,  nature,   1229 
Ceratophyllus  acutus,  325,  344 
Ceratophyllus   fasciatus,   324 
Cerebrospinal  fever,  250 
agglutination  test,  257 
carriers,  254 
causes,  predisposing,  251 
cerebrospinal   meningitis,   differential 

diagnosis,  250 
epidemiology,  251 
fatigue  and,  251 
immunity,  252 


INDEX 


ir.m 


Cerebrospinal  fever,  modes  of  transmis- 
sion, 252 

prevention,  257 

references,  258 

seasonal  prevalence,  251 
Cerebrospinal   nieninfiitis,   cerebrospinal 
fever,  (iitferential  diagnosis,  250 

mortality,  212 
Cernovodeanu,  1376 
Certificates,  birth,   1237 

death,   12G2 

vaccination,   14 
Cesspools.   1191,   1214 
Cestoda,  in  soil,  1013 
Ceylon  hookworm,  154 
Chagas,  264 
Chagas'  disease,  321 
Chalieosis,  932,  1314 
Chalmers,  776 
Chalmers,  A.  J.,  288,  385 
Chamberlain,  680 
Chamberland,  44,  54 
Chambers,  grit,  1201 
Chancre,  58,  61 

extragenital,  60 

Hunterian,  58 

soft,  72 
Chancroid,  72 

complications,  73 
Chapin,    127,    193,    216,    217,   264,   321, 
350,  415,  466,  521,  723,  940,  941 
Chapman,  29 

Characters,   unit,  heredity,   627 
Charbon,  401 
Charcot,  443 
Charrin,  589 

Chaulmoogra  oil,  in  leprosy,  419 
Chaussat,  320 
Chauveau,  172,  528 
Chauvenet,  635 

Cheese,  and  typhoid  fever,  123 
Chemotayis,  571 
Chemotherapy,  1357 
Chenopodium,  hookworm  disease,  159 
Chesbrough,  1192 
Chest  measurements,  recruits,  1446 
Chestnut,  852,  853 

Chick,  685,  1360,  1361,  1363,  1367,  1371 
Chickenpox,  395 

smallpox,    differential    diagnosis,    18, 
395 

vaccination,  396 
Chickering,  H.  T.,  239 
Chick-pea,  857 
Children,   emotional  attitude,  448 

mental  age,  447 
Chilling,  colds  and,  248 

of  the  skin,  colds,  249 
Chisholm,  J.,  1189 


Chiswell,    Sarah,    27 
Chittenden,   667,   744,   746 
Chloramins,  1134,  1417 
Chloramin-T,  1134 
Chloretone,  26S 
Chlorid  of  lime,  1417 

water    purification,    1132.      See    also 
Chlorinated  lime 
Clilorin,  disinfection,  1403 

liqui<l,  1139 

in  water,  1076 

water  purification,  1139 
Chlorin  gas,  1139 
Chlorin  group,  disinfection,  1417 
Chlorinated  lime,  composition,  1133 

disinfection,   1417,    1426,   1433 

to  dissolve,  1135 

modes  of  action,  1133 

properties,  1133 

sewage,  1209 

strength,    1135 

water,  disinfection,  1420 

water  purification,  1132 
amount  used,  1136 
method   of   dosing,   1135 
summary,  1138 
Chloroform,  268,  325 

disinfection,  1423 
Chloronaphtholeum,  1413 
Chlorophyll,  919 
Chlorops  leprae,  416 
Chlorops  vomitoria,  416 
Chlorpicrin,  369 
Cholera,  139 

Asiatic,   139 

bacillus  carriers,   144 
detection,   145 

Broad  Street  epidemic,  1161 

cause,  139 

comma  bacillus,  139 

contact  infection,  143 

contributing  causes,  139 

diagnosis,  140 

Dieudonne  's  medium,  140 

and   flies,   144 

Hamburg  epidemic,  1165 

immunity,   145 

in  London,   1161 

milk-borne,  144 

modes  of  transmission,  142     • 

personal  prophylaxis,  147 

Pf eiffer  's  phenomenon,   142 

soil  and,  1010 

summary,  147 

vaccines,   145 

vibrio   cholerae,   139 

water-borne,   143,  1161 

winter,   139,   1181 

X,  Y,  Z  theory,  140 


1514 


INDEX 


Cholera  morbus,   139 
Cholera  nostras,  139 
Cholera  vibrio,  in  water,  1095 
Cholin,  724 
Chorea,  1348 
Chowning,  357 
Chromosomes,   630 
Chrysanthemum  carneum,  271 
Chrysanthemum  flowers,  268 
Chrysanthemum  roseum,  271 
Chrysops,   308 
Church,   1024 
Cicuta  maculata,  852 
Cimex  lectularius,   328,   378 
Cinnamon,  745 
Cisterns,   disinfection,    1437 
Citellus  beecheyi,  326,  344 
Citronella  oil,  268 
Claims,  for  vaccination,  20 
Clarifiers,  773 
Clark,  859,  1137,  1140 
Clarke,   1152,   1190 
Clay,  478,  992 
Clayton  furnace,   1401 
Cleanliness,  1006 
disinfection,  1353 
hookworm   disease,   160 
insects   and,   263 
lead  poisoning,  1301 
roaches   and,   384 
schools,  1338 
Clean-up  week,  476 
Clegg,  264,  413,  414,  1180 
Cleland,   304 
Cleveland,  H.  B.,  1217 
Clonorchis  endemicus,  265 
Clothing,  of  the  soldier,  1454 

coats,  1456 

cotton,   1454 

fur,   1455 

gloves,  1456 

headgear,   1455 

leather,  1455 

leggings,  1456 

linen,    1455 

merino,  1455 

paper,   1455 

shoes,    1456 

underwear,  1456 

waterproofing,   1455 

wool,  1455 
Clouston,   654 
Cloves,  745 
Cloves  oil,  268 
Clurman,    111 
Coal  gas,  904 
Coal  mining,   1071 
Coal  oil.    See  Petroleum 
Coal  tar,  1408 


Coa!l-tar  creosote,  1408 
Coal-tar  dyes,  727 
Coats,  of  the  soldier,  1456 
Cobalt,  316 
Cobbett,  173 
Cobbold,   264 
Cobwell,  process,  1223 
Cocain,  486 

Cochin-China   diarrhea,   155 
Cockburn,  862 
Codein,  486 
Codling  moth,  277 
Cohen,  92,  926,  1134 
Cohnheim,  J.,  191,  889 
Coit,  H.  L.,  767 
Cold,   bacteria,    730 

food   preservation,   730 
Cold  climates,   military  hygiene,   1481 
Cold  storage,  foods,  732 
Colds,  246 

causes,  predisposing,  248 
.    chilling  and,  248 

chilling  of  the  skin,  249 

drafts  and,  248 

prevention,   247 
Cole,  233,  720,  1296 
Coleman,  578,  934 
Colemanite,  316 
Coles-Finch,  1024 
Collateral  benefits,  hookworm  campaign, 

161 
Colle's  law,  646 
Collins,  G.  L.,  923 
Colon  bacillus,   1091 
Colon-typhoid  group,  699,  700 

differentiation,  699 
Color-blindness,  650,  922 

Holmgren  test,  923 

tests,  923 
Columbella,  287 
Columbian  spirits,  94 
Columbus,   57,  689 
Comandon,  62 
Comfort  zone,  905 
Comma  bacillus,  139 
Common  colds,  246.     See  also  Colds 
Communicability,  526 
Communicable  disease,  463 
Compensation  laws,  1290 
Complement  fixation,   580 

in   glanders,  399 
Complications,   chancroid,   73 

gonorrhea,  67 

vulvovaginitis,   70 
Complications  and  dangers,  vaccination, 

21,  24 
Compte,  373 

Compulsory  vaccination,  25 
Conception,  alcoholism  and,  431 


INDEX 


1515 


Condensation,  water  puiification,   1109 
Condiments,  669 
Condom,  84 
Conduction,  985 
Conflicts,  mental,  439 
in   civil   life,   441 
Congenital   debility,  481 
Congenital  transmission,  644 
Conn,  124 

Conorhinus  megistus,  820 
Conrad,  653 
Conradi,  111,  138 
Conseil,  214,  215,  229,  373 
Contact  beds,  1205 
Contact   infection,   461 

cholera,  143 

tulierculosis,   176 

typhoid  fever,  126 
Contagious  disease,  463 
Continence,   79 
Convection,  985 
Cook,  683 
Cooking,   695,  749 

botulism  and,  717 

broiling,  751,  752 

tireless,    751 

frying,  752 

methods,  751 

mussel  poisoning  and,  845 

roasting,   751 

stewing,  752 
Cooks,    1289 
Cooling  of  rooms,  988 
Cooper,  57 

Cooper-Hewitt  lamp,  1376 
Cooperative   sanitation,   1212 
Copeman,  M.,  5,  6,  38 
Copper,    sprays,    279 
Copper  sulphate,  disinfection,  1408 

water  purification,  1143 
Copperas,   1408 
Coquillett,  295 
Corbus,  211 
Corn,  pellagra  and,  687,  689 

tests  for,   690 
Cornell,   1350 
Cornet,   170,  171,   191 
Cornet-Koch  theory,  170 
Corrodor,  416 
Corrosive  sublimate,  disinfection^  1407, 

1434 
Coryza,  acute,  246 
Cotton,   777,   787 

clothing,  of  the  soldier,  1454 
Cotton,  H.  A.,  425 
Councilman,  W.   T.,   30 
Course,     laboratory,     1483.       See    also 

Laboratory  course. 
Coustan,  1461 


Cowjier,  1,  3,  4,  7.  See  also  Vaccination. 

and   smallpox,   unity,  25 
Crab,  fresh-water,  265 
C;raig,  288,  293,  295,  304 
Crampton   value,   906 
Cream,  758 

and  typhoid  fever,  123 
Cred6,  89,  90 
CJredo  's    method,   89 
Creel,  125,  345,  1402 
Crematories,  Caldwell,  1478 

English,  1478 

pit,   1474 

rock  pile,  1477 
Crenothrix  kuehniana,  1080 
Creolin,   1412 
Creosapol,  1412 
Creosote  oil,  268 
Cresol,  1411 

disinfection,   1433 
Cresolin,  1412 
Cretinism,   1151 
Crime,  alcohol  and,  492 
Cross-infections,  216,  941 
Croton  bug,  383 
Croupous   pneumonia,  230 
Crowder,  963 
Crowell,  679 
Crum,  F.  S.,  213 
Cruz,  O.,  302 
Cry  sops,  321 
Ctenocephalus  canis,  324 
Ctenocephalus  felis,  325 
Culex  fasciatus,  295 
Culex  fatigans,  306 
Culicides,  268 
Gumming,  42,  47,  123 
Gumming,  J.  G.,  238,  241 
Gummings,  638 
Cunningham,  74 
Currie,  413,  414,  925 
Gushny,  741 
Cyanid,  515.    See  also  Hydrocyanic  acid 

gas 
Cyclops  coronatus,  265 
Cylindrical  screen,  1201 
Gyllin,  1412 

Cysticercus  bovis,  828,  836 
Gysticercus  cellulosae,  834 
Cystin,  720 
Cytolysins,  575 
Cytotoxins,  579 
C'zapek,  720 
Czerny,  759 

Dakin,  1134,  1139,  1420,  1422,  1423 
Dakin's  solution,  1420 
Dale,  856 
Dalton,  922 


1516 


IXDEX 


Daltonism,  650 
Damien,  418 
Dandy  fever,  303 

Dangers  and  complications,  in  vaccina- 
tion, 21,  24 
Daniels,  287 
Danielson,  414 
Danysz  virus,  343,  702 
Darling,  159 
Darling,  S.  T.,  288 
Damall  syphon  filter,   1471,   1472 
da  Eocha,  407 
da  Eocha  Lima,  372,  374 
D'Arsonval,   958,  959 
Dar^vin,  618,  621,  622,  628,  658,  991 
Darwin's  theory,  621 
Davaine,  401 
Davenport,   C.   B.,   638,   644,   649,   658, 

656,  658,  659 
Davies,  1018 

Davis,  460,  670,  739,  758,  959,  1185 
Day,  198 
Deadrick,  295 
Deaf -mutism,  648 
Dean,  195,  209,  414,  415,  419 
Death  certificate,  1262 
Death  rates,  1267 

and  birth  rates,   1271 

corrected   formula,   1493 

crude,   1267 
formula,   1493 

factors  affecting,  1270 

marital  conditions,  1271 

migration,  1270 

non-residents,   1270 

for  short  periods,  1267 

specific,    1267 
formula,   1493 

standardized,  1269 

tuberculosis,   182 
de  Barros,  296 
Debridement,  102 
Dechambre,  60 
De  Chaumont,  876,  914 
Decomposition  of  food,  717 
Decompression,   891 
De  Crocq,  1320 
Deer-fly  fever,  321 
Defectives,    608 

Binet's  formula,  610 

degenerate  families,  615 

education,  611 

Edwards  family,  617 

idiots,   609 

imbeciles,  609 

intelligence   quotient,   610 

Jukes  family,  615 

Kallikak  family,  616 

Mongolianism,  608 


Defectives,  morons,  609 

number,  422,  610 

prevention  of  propagation,  422,  611, 

recognition,  608 

school  children,  1349 

segregation,  611 

statistics,  613 

sterilization,  612 

zero  family,   615 
Deficiency  diseases,  677..    See  also  Beri- 
beri;  Pellagra;   Eickets;   Scurvy 
Defoe,   345 
Degenerates,  615 
De  Graef,  788 
Dehaan,  680 
De  Jong,  788 
de  la  Cloture,  L.,  394 
de  la  Condamine,  28 
de  la  Paz,.G.,  852 
Delepine,  S.,  680,  695,  778,  950 
Delhi   boil,   381 
Delirium  tremens,  429,  489 
Delousing,  366 

clothing,  368 

heat,  366 

plant,  371 

Serbian  barrel,   367 
Delphinium,  852 
Del  Pont,  242 
Demarquay,   264 
Dembo,  824 
Dengue,  303 
Dennis,  944 
Denno,  W.  J.,  521 
De  Xobele,  7D2 
Deodorants,  definition,   1352 

zinc  chlorid,  1408 
Departments,  public  health,  cost,  471 

organization,  470 
Dermacentor  andersoni,  357 
Dermacentor   marginatus,   357 
Dermacentor  modestus,  357 
Dermacentor   occidentalis,  357 
Dermacentor  venustus,  357,  358 
Dermatitis  venenata,  854 
De  Schweinitz,  1321 
Desensitization,    diphtheria,    209 
Determiner,   625 
De  Vries,  622 
De  Vries,   H.,   659 
Dewpoint  apparatus,  903 
Deycke,  419 
Diabetes  mellitus,   653 
Diagnosis.      See  under   each   disease 
Diamond  polishing,  1300 
Diarrhea,  epidemics,  1181 

water  and,   1180 
Diastase,  761 
Diatom,   1054 


Index 


1517 


t)iatomaeeae,   1051 
Dibothrioeephalus  latus,  265,  839 
Dickson,  70(5,  710,  71.S,  714 
Diehl,   1377 

Diets,  unbalanced,  676 
Dieuilonne,  862 
Dieudonne 's  medium,  140 
Differential  diagnosis,  cerebrospinal  fe- 
ver and  cerebrospinal 'meningitis, 
250 

chickenpox  and  smallpox,  18,.  395 

dysentery,  amebic  and  bacillary,  151, 
152' 

smallpox  and  chickenpox,  18,  395 

typhoid  and  paratyphoid,  137 
Digestion   tanks,   1202 
Dilution,  sewage  disposal,  1196 
Diphtheria,  191 

administrative  measures,   206 

animals,  domestic,  194 

antitoxin.     See  Diphtheria  antitoxin 

bacillus,  193,  196 
resistance,  198 

bacillus  carriers,  195,  203 
cure,  197 

control  of  outbreaks,  202 

desensitization,  209 

diagnosis,   198,   1496 

disinfection,   205 

domestic  animals,  194 

dust  and,   193 

epidemics,  192 

fumigation,  terminal,  205 

historical  note,  209 

immunity,   199 
active,  200,  204 
antitoxic,  205 
passive,  200,  205 

milk-borne,  195,  780 

modes  of  transmission,  193 

mortality,   212 
cause,  207 

responsibility    medical    profession, 
207 

Neisser  's  method,  196 

personal  prophylaxis,   206 

quarantining  cases,  203 

recognition   cases,   203 

references,  209 

responsibility  medical  profession,  206 

Schick  reaction.     See  Schick  reaction 

schools,  closing,  206 

seasonal  prevalence,  192 

serum   sickness,   208 

sewer  gas  and,   193 

susceptibility,   199 

terminal  fumigation,  205 

toxin,   553 

toxin-antitoxin  mixture,  200,  204 


Diphtheria.    See  also  Schick  reaction 
Diphtheria  antitoxin,  197,  198,  208,  209 

anaphylaxis  and,  208 

concentration,  562 

paralysis,  postdiphtheritic,  207 

stanilardization,  566 

test  for,  567 

unit,  5<57 
Diplococcus    intracellular    meningitidis, 

250 
Dips,  arsenical,  355 

cattle,   355 
Diptera,  307,  322 
Dirt,  1005,  1006 
Diseases,  from  animals,  lower,  459 

communicable,  463 

contagious,  463 

deficiency,  677 

endemic,  464 

epidemic,  464 

filth,  1006 

gastro-intestinal    and    infant    mortal- 
ity, 480 

hereditary  transmission,  640 

ice   and,   1188 

infections,   463,  525 

insect-borne,  259 

miasmatic,  464 

notifiable,    1244 

occupational,  1279 

pandemic,  465 

prosodemic,  465 

rat-borne,  335 

respiratory,  163 

skin,  1347 

soil,  1003,  1007 

of  the   soldier,   1458 

sporadic,  464 

venereal,  54 

water  and,  1147 
Disinfectants,  acids,  1422 

acriflavine,  1422 

alcohol,  1423 

ambrine,  1413 

antiformin,   1421 

asaprol,  1412 

aseptol,  1412 

bichlorid  of  mercury,  1406,  1425 

borates,    1423 

bromin,  1417 

carbolic   acid,   1409,  1426,   1433 

chlorin,  1403 

chlorin  group,  1417 

chlorinated  lime,  1417,  1426,  1433 

chloroform,   1423 

choice,  1362 

coal-tar  products,  1408 

copper  sulphate,  1408 

creolin,    1412 


1518 


INDEX 


Disinfectants,  eresol,  1411,  1433 

Dakin's  solution,  1420 

dilution,  1362 

dyes,  1422 

emulsions,   1361 

ether,  1423 

ferrous  sulphate,  1408 

flavine,  1422 

formalin,  1414,  1425,  1433 

formulae,  1425 

gaseous,   1390 

halazone,  1420 

hydrocyanic  acid  gas,  1402 

hydrogen  peroxid,  1415 

ideal,   1357 

inorganic,  1360 

iodin,   1417 

Javelle  water,  1420 

Labarraque's  solution,  1420 

lime,  1416,  1426,  1432 

liquid,  1404 

liquor  eresolis  compositus,  1412 

lysol,  1412 

malachite  green,  1422 

metallic  salts,  1406 

naphthols,  1413 

organic,   1360 

oxygen,  1404 

ozone,  1404 

perborates,  1423 

peroxids,   1415 

phenol,   1410 

potassium  permanganate,  1415 

pyxol,  1412 

reaction,  1362 

silver  salts,  1407 

soaps,  1424 

solutions,  1361 

solutol,  1413 

solveol,  1413 

stability,  1360 

sulphur  dioxid,  1396 

table  of  values,  1373,  1425 

Tri-brom-j3-naphthol,  1411 

Tri-chlor-|3-naphthol,  1411 

trypaflavine,    1422 

zinc  chlorid,  1408 

zinc  salts,  1408 
Disinfectant      standardization,      1364, 
1485 

drop  method,   1366 

Garnet  method,   1366 

Hygienic  Laboratory  method,  1367 

Lancet  Commission  method,   1367 

physical-chemical  method,  1367 

Eideal-Walker  method,  1366 

Sternberg's  method,  1366 

thread  method,  1365 

See  also  Carbolic  coefficient 


Disinfection,  1351 

air,  1427 

aluminum-sulphate  method,  1395 

amount  necessary,  1356 

anthrax,  403,  404 

antibiosis,   1354 

antiseptics,   1351 

Arnold  steam  sterilizer,  1381 

asepsis,  1352 

autoclave,   1381 

barium-formalin  method,  1395 

bed  and  body  linen,  1435 

bleaching-powder  method,  1395 

boiling,  1378 

books,  1435 

Bramhall-Deane       steam       sterilizer, 
1382 

bristles,  404 

burning,  1377 

chemical  agents,  1390 

chemotherapy,  1357 
,   cholera,  504 

cisterns,  1437 

Clayton  furnace,   1401 

cleanliness,   1353 

concurrent,  1357 

controls,  1356 

Cooper-Hewitt  lamp,  1376 

corrosive  sublimate,  1407 

definition,  1351 

deodorant,   1352 

diphtheria,  1205 

dry  heat,  1378 

electricity,  1377 

feces,   1432 

fire,  1377 

fomites,  1357 

formaldehyd  gas,  1391 

formalin-lime  method,  1395 

fumigation,  1352 

general  considerations,  1351 

germicide,  1352 
specificity,  1356 

glassware,  1382 

Kinyoun-Francis   furnace,    1401 

mechanism,   1362 

method   of   using   chemical  solutions, 
1405 

methods,   1427 

nature's    agencies,    1353 

organic  matter,  1359 

oxidizing  agents,  1415 

penetration,  1358 

permanganate-formalin        method, 
1394 

physical  agents,  1375 

place,  1355 

pressure,    1377 

pulverizer,  1405 


INDEX 


1519 


Disinfection,  railroad  cars,  14;50 

rooms,  1427 

rubber  tubing,  1382 

sewage,  1209 

ships,  511 

smallpox,  35 

speeifieity,  1356 

speed,  1360 

spraying  method,  1395 

sputum,  143-4 

stables,  1428 

steam,   1379 

steam  chamber,  1382,  1383 

sterilization,  1351 

sulphur  dioxid,   1396 
furnace,   1400 
liquid,   1399 
pot  method,  1398 

sunlight,  1375 

symbiosis,    1354 

temperature,  1360,  1380 

terminal,   1357 

thermometers,  1437 

time,    1355 
value,  1359 

tuberculosis.  186 

typhoid,  133 

ultraviolet  rays,  1375 

water,  1420 

wells,  1041,  1437 
Disinfeetol,    1412 
Disinfeetors,   qualifications,  1355 
Dispensaries,  tuberculosis,   183 
Disposal,  sewage,  1191.     See  also  Sew- 
age disposal 
Distilled  water,  1112 
District  sewers,  1193 
Diver's  palsy,  891 
Doane,  746,  779 
Doane-Buckley  method,  798 
Dochez,  592 
Dochez,  A.  K.,  239 
Dock,  L.  L.,  483 
Dodge,  488 
Doerr,   264,   322,   595 
Doflein,   320 
Dogs,  and  rabies,  42 
Domestic  employees,  1289 
Dominance,  625 
Don,  J.,  1189 
Donnelly,   372 
Donovan,  381 
Dopter,   253,   256,   1445 
Dorange,  1188 
Dornbleuth,  20 
Dothienenteritis,  107 
Douglas,  817,  875,  889,  970 
Dourine,  54,  320 
Doust,  486 


Dracuncukis  medinensis,  265,  1181 
Drafts,  cohls  and,  248 
Drainage,  subsoil,  997 
Dressing,  vaccination,  11 
Dressier,  F.  B.,  1350 
Drigalski,    111 
Drinker,  C.  K.,  1282 
Drinking  fountains,   1184 
Droplet  infection,  461,  940 

measles,  216 

tuberculosis,  172 
Drugs,  addiction,  486 

anaphylaxis,  605 

habit-forming,  486 

Harrison  law  and,  486 

immunity  and,  546 

in  milk,   763 
Drum  screen,  1201 
Drummond,  670,  672,  837 
Dry  earth    system   of   sewage   disposal, 

1192 
Dry  points,  vaccination,  6 
Dubois,  443 
Ducrey,   72 
Duffield,  138 
Duflies,  219 
Dugdale,  615 
Duke's  disease,  219 
Dum-dum  fever,  380 
Dunbar,   333,   1216 
Dunham,   536,    1134,   1139,   1420,   1422, 

1423 
Dupetit,   1001 
Dupony,  808 
Durand,  P.,  738 
Durgin,  S.   H.,   1339 
Durham,  589,  700 
Durig,  489 
Dust,  929,    1313 

anthracosis,  1314 

byssinosis,  1314 

chalicosis,   1314 

diphtheria,  193 

and  disease,  931 

dusty  trades,  1313 

house,  932 

infantile    paralysis,    392 

koniscope,  935 

lead  poisoning,  1294 

Malta  fever,  408 

methods  for  examining,  933 
condensation,  935 
electrostatic,  933 
filtration,  934 
impaction,  933 

Palmer  water-spray  apparatus,  934 

pneumokoniosis,  1314 

prevention,  1316 

removing  system,  1315 


1520 


INDEX 


Dust,  siderosis,  1314 

textile  industries,  1316 

tuberculosis,   171 

typhoid  fever,  126 

wood,  1319 

wool-sorter's   pneumonia,    1315 
Button,  264,  317,  318,  320,  361 
Duval,  413,  414 
Dyas,  211 

Dyes,  disinfection,  1422 
Dypilidium  caninum,  265 
Dysentery,   148 

amebic,  150 

bacillary,  148 

bacillary     and     amebic,     differential 
diagnosis,  151,  152 

bacillus  carriers,  149 

B.  dysenteriae,  148 

emetin,   150,   151 

Entameba  coli,  150 

Entameba  histolytica,  150,   151 

epidemics,  1180 

immunity,    149 

in  infants,   150 

infant  mortality  and,  481 

ipecac,  150 

in  Japan,  1180 

modes  of  spread,  149 

prevention,  149 

resistance,  149 

tropical,  150 

vaccines,   150 

water  and,  1179 

Ears,  school  children,  1343 

Earth,  dry,  system  of  sewage  disposal, 

1192 
Earthenware,  lead  poisoning,  1299 
Eastwood,  167,  168 
Eberth,  107,  700 
Ebstein,  749 
Echeherria,  655 
Echinococcus    disease,    836 
Echinococcus  granulosus,  265 
Ecker,  703 
Eckles,  C.  H.,  854 
Economic   factors,    in   mental   diseases, 

449 
Ectoparasites,  261,  524 
Eczema,  604 
Eczema  contagiosa,  405 
Eddy,  1217 
Edelmann,  E.,  863 
Edgar,  90 
Edlemann,  818,  845 
Edmonson,  707,  713 
Edsall,  D.  L.,  1282,  1294,  1297,  1307 
Education,  defectives,  611 
epidemic  campaign  and,  497 


Education,  hookworm  disease,  160 

mental  hygiene,  452 

public  health,  476 

sex  hygiene,  76 

tuberculosis,  185 
Edwards,  1367,  1371 
Edwards,  J.,  617 
Edwards  family,  617 
Efficiency,  alcohol  and,  489 
Eggs,  847 

bacteria   and,   849 

classification,  848 

disease  and,  849 

dried,  734 

nutritive  value,  847 

rots,  848 

spots,  848 
Ehrlich,    57,    210,    528,    540,    547-551, 
554,    558,    563,    564,    573,    577, 
606,  731,   1357,  1411,  1422 
Eichhorn,  400,  818,  845 
Eichhorn,  A.,  863 
Eijkman,  678 
Elderton,  638 
Eldridge,  1180 
Electric  fans,  892 
Electric  heating,  988 
Electricity,  925 

disinfection,   1377 
Ellis,  875 
Elmassian,  320 
Elm-leaf  beetle,  277 
Elser,  253,  254,  258 
Eisner,   A.,   1217 
Elster,  925 

Emergency  slaughter,  703 
Emerling,  720 
Emery,  539,  586,  587,  606 
Emetin,  in   dysentery,   150,  151 
Emmerich,  140,  198 
Empusa  muscse,  309 
Emscher  tank,  1202 
Encephalitis  lethargica,  394 
Endemic  diseases,  260 

definition,  464 
Endemic  index,  median,  472 
Endoparasites,  261,  524 
Endotoxins,   149,  553,  565 
English  crematory,  1478 
Entameba  coli,  150 
Entameba  histolytica,  150,  151,  1180 
Enteritidis  group,  701 
Enumerators,  1225 

Environment,  effect,  on  mental  diseases, 
425 

vs.  heredity,  425,  638 
Enzymes,  760 

in  milk,  808 

thermal  death  point,  761 


INDEX 


1521 


Epidemics,  cholera,  1161 

Broad  Street  pump,  1161 
Hamburg,  116;) 
London,  1161 
definition,  464 
diarrhea,  1181 
diphtlieria,  control,  202 
dysentery,   1180 
foot-and-mouth  disease,  405 
infantile  paralysis,  387 
influenza,  240 

management  of  campaign,  495 
authority,  496 
education,  497 
organization,  497 
police  powers,  496 
ways  and  means,  497 
milk-borne,  783 
schools  closed,  1342 
typhoid,  1168,  1188 
Albany,  N.  Y.,  1169 
Allegheny,  Pa.,  1178 
Ashland,  Wisconsin,  1175 
Binghamton,  N.  Y.,  1169 
Butler,  Pa.,  1178 
Chicago,  111.,  1179 
Ithaca,  N.  Y.,  1177 
Jersey  City,  N.  J.,  1169 
Lausen,   1168 

Lawrence,  Mass.,  1169,  1178 
Lowell,  Mass.,  1169,  1178 
Mankato,  Minn.,  1176 
Newark,  N.  J.,  1169 
New  Haven,  Conn.,  1174 
Ogdensburg,  N.  Y.,  1188 
Paterson,  N.  J.,  1169 
Pittsburgh,  Pa.,  1178 
Plymouth,  Pa.,  1173 
oysters,  842 
Epidemic  catarrhal  jaundice,  335 
Epidemic   encephalitis,  394 
Epidemic  parotitis,  228 
Epidemic  vaginitis,  69 
Epidemiology,  of  smallpox,  29 
Epilepsy,  655 

alcoholism  and,  655 
in  school  children,  1349 
Epizootic  catarrh,  405 
Equipment,  of  the  soldier,  1451 
Erclentz,  891,  961 
Ergotism,  856 
Erlandsen,  871 
Escherich,  700 
Espundia,  381 
Esten,  313 
Ether,  268,  325 

disinfection,   1423 
Ethylhydroeuprein,   234 
Etiology.    See  under  each  disease 


Kugenics,  607,  619 

mental  deficiency  and,  428 
Evans,  320,  745,  1394 
Evaporation,  905 

water  purification,  1109 
EwaM,  1155 
Kxcreta,  disposal,  1473 
E.xotuxin,  148,  .553 
ExjKisure,  imnuinity  and,  543 
Eyckman,  669 
Eyes,  care,  923 

as  portal  of  entry  of  infections,  924 
school  children,  1342 
Eye  strain,  923 

Faber,  49 

Face  masks.    See  masks 

Factory  inspection,  1289 

Faget,  F.  M.,  1402 

Fagopyrismus,  688,  919 

Faichnie,  311,  314 

Fairfield  system  of  ventilation,  983 

Falcioni,  101 

Falkao,  417 

Famine,  675 

immunity  and,  545 
Famine  fever,  361 
Fans,  electric,  892 
Fantham,  318 
Fantham,  H.  B.,  264,  385 
Farcy,  396 
Farrj  W.,  1278 
Farrington,  813 
Fan's  law,  228 
Far-sightedness,  922 
Fasciola  hepatica,  265 
Fatality  rates,  formula,  1493 
Fatigue,  1284 

cerebrospinal  fever  and,  251 

immunity  and,  532,  544 

pneumonia  and,  231,  235 

toxin,  960 
Fats,  668 

milk,  756,  800 

in  soil,   1002 

vitamins,  670 
Faust,  723 
Favism,  857 
Favus,  1348 
Favus  herpeticus,  1323 
Feces,  diseases  spread  by,  105  ' 

disinfection,  1432 
carbolic  acid,  1433 
chlorinated  lime,  1433 
corrosive  sublimate,  1430 
cresols,  1433 
dry  earth,  1434 
formalin,  1433 
lime  and  hot  water,  1432 . 


1522 


INDEX 


Feces,  disinfection,  milk  of  lime,  1433 
steam,  1434 

removal,  1191 

typhoid  bacillus  in,  111 

in  water,  1043 
Feeble-mindedness,  609 

heredity  and,  427 

prevention,  447 

syphilis  and,  437 

See     also     Defectives;     Mental     de- 
ficiency 
Fehling  method,  802 
Feletti,  264,  286 
Ferenbaugh,  407 
Ferment  antitoxins,  560 
Fermentation,  of  'food,  718 
Fermi,  857 
Fernald,  W.  E.,  456 
Fernard,   611 
Ferran,  45,  47,  145 
Ferrous  sulphate,  disinfection,  1408 
Ferry,  31,  225 
Ferry,  N.  S.,  1410 
Fibiger,  J.,  384 
Fibrinous  pneumonia,  230 
Ficker,  311 
Fiedler,  48 
Field,  117 

Filaria  bancrofti,  305,  306 
Filaria  loa,  306 
Filaria  nocturna,  306 
Filariasis,  305 
File  cutting,  1300 
Filter  galleries,   1035 
Filters,  1113 

Berkefeld,  1127 

household,  1127 

Handler,  1127 

mechanical,   1122 
cities  using,  1126 
coagulants,  1123 

Pasteur-Chamberland,   1127 

percolating,  1207 

roughing,  1128 

scrubbing,    1128 

slow  sand,  1113 
construction,  1115 
control,  1115 
eflSciency,  1115 
loss  of  head,  1115 
operation,  1115 

sprinkling,  1207 

trickling,    1207 
Filtration,   1471 

American  method,  1114 

English  method,  1113 

intermittent  sand,  1205 

mechanical,  1123,  1125 
cities  uging,  1126 


Filtration,  slow  sand,  1113,  1125 
cities  using,  1121 
vs.  mechanical,  1125 
results,   1120 
Findel,  171 
Finger,  64 

Finlay,  C.  J.,  259,  302,  304 
Fire,  disinfection,  1377 
Fireplace,   986 
First-aid  packet,  1453 
Firth,  117,  1461 
Fisch,  98 
Fischer,  75 
Fischer,  E.,  667,  719 
Fish,  837 

B.  botulinus  in,  839 

fugu,  837 

goiter  in,  1154 

mosquitoes  and,  282 

sewage  and,  1198 

shell.     See  Shellfish 

tapeworm,  839 
Fish  poisoning,  837 

bacterial,  838 
Fitz,  884 

Fitz  air  tester,  885 
Fixed  virus,  44 
Flachs,  11 
Flack,  870,  871,  908 
Flanagan,  K.,  1176 
Flavine,  1422 
Fleas,  322 

description,  323 

dog,  265 

hydrocyanic  acid  gas,  515 

Indian  rat,  323,  327 

life  history,  323 

petroleum  and,  275 

pulicides,  325 

squirrel,  327 

sulphur  and,  269 

sulphur   dioxid,   517 

table  of,  265 
Fleming,  889 
Fletcher,  680 
Flexner,  700 
Flexner,    S.,    148,    252,    258,    386,    390, 

391,   393,   394 
Flies,  268,  307 

anthrax  and,  402 

borax  and,  316 

carriers  of  infection,  310 

cholera  and,  144 

colemanite  and,  316 

destruction  of  larvae,  316 

formalin  and,  271 

garbage  and,  315 

Hodge  traps,  315 

hpuge,  307 


INDEX 


1523 


Flies,  larvicides,  316 

leprosy  and,  416 

manure  and,  ;U5 

Musca     doniestica.     See     Musca     do- 
mestiea 

musc'ifidos,  ;{16 

sodium  salicylate,  316 

sticky  fly  paper,  272 

Stomoxys   ealcitrans.      See  Stomoxya 
calcitrans 

suppression,   315 

table  of,  264 

tsetse,  317 

and  tuberculosis,  175 

and  typhoid  fever,  125,  312 
Flour,  727 

bleached,  743 
Fliigge,  868,  891,  936,  961,  964,  965 
Flugge,  C.  G.,  191,  521 
Flukes,  in  soil,  1012 
Fluorescence,  919 
Fluorescin,  1044 
Flux,  148 
Fly  paper,  272 
Fog,  929 
Foley,  265 

Follicular  conjunctivitis,  93 
Follwell,  A.  P.,  1217 
Fomites,  465 

disinfection,  1357 

typhoid  fever,  126 
Fontaine,  B.  W.,  707 
Food  infections,  696 

carriers,  704 

colon-typhoid  group,  699 

contamination    with    fecal    bacteria, 
704 

diagnosis,  698 

food  responsible,  698 

Gaertner  group,  701 

incubation  period,  696 

mice  and,  704 

milk  and,  783 

non-specific  bacterial  origin,  704 

prevention,  705 

rats  and,  337,  704 

rat  viruses,  704 

seasonal  prevalence,  697 

symptoms,  696 

taste,   odor  and  appearance  of  food, 
698 

See  also  Gaertner  group 
Food  poisoning,  692 

cooking,  695 

general  considerations,  692 

and  paratyphoid,  138 

prevention,  695 
Food  preservation,  728 

canning,  737 


Food  preservation,  chemicals,  741 
cold,  730 
desiccation,  733 
drying,   733 
evaporation,  733 
jellying,  736 
pickling,  735 
preserving,   736 
salting,  735 
smoking,  737 
Food  preservatives,  arsenic,  749 
benzoate  of  soda,  744 
benzoic  acid,  744 
borax,  745 
boric  acid,  745 
chemical,   741 
formaldehyd,  746 
hydrofluoric  acid,  748 
hydrogen  peroxid,   749 
potassium  permanganate,  747 
salicylic  acid,  747 
sodium  bicarbonate,   749 
sodium  fluorid,  747 
sodium  nitrate,  747 
sulphites,  748 
Foods,   661 

adulteration,  725 

definitions,  726 

examples,  725 
alcohol  as  a,  487 
amount,  673 

excessive,  673 

insufficient,  674 
anaphylaxis,  604 
animal,  753 
antiscorbutics,  685 
caloric  value,  664 
canned.     See  Food  preservation 
carbohydrates,  668 
casein,    667 

chemical  composition,  666 
classification,    666 
cold  storage,  732 
coloring,  727 
composition,  667 
condiments,  669 
cooking.    See  Cooking 
corn,  689 
decomposed,  717 
deficiency     diseases,     677.     See    alsa 

Deficiency  diseases 
diets,  unbalanced,  676 
effect  on  health.  662 
famine,  675 
fats,  668 

fermentation,  718 
flour,  727 
foot  pound,  663 
fuel  value.  664 


1524 


INDEX 


Foods,  function,  667 

general  considerations,  661 

infections.     See  Food  infection 

inorganic  salts,  669 

insufficient,  and  immunity,  544 

labeling,  728 

milk.     See  Milk 

misbranding,  728 

pestilence,  675 

plant,  849 

poisoning.     See  Food  poisoning 

preparation,  749 

preservation.    See  Food  preservation 

preservatives.     See     Food     preserva- 
tives 

protective,  677 

proteins,  667 

putrefactive  changes,  719 

ptomain  poisoning,  721 

ptomains,  721 

putrefaction,  718 

references,  682 

rice,  681 

undernourishment,  674_,  676 

uses,  663 

vitamins,  669 

See    also    Beriberi;     Botulism;     Pel- 
lagra;    Eickets;     Scurvy;     War 
edema 
Foot-and-mouth  disease,  405 

epidemics,  405 

milk  and,  782 

prevention,  407 

and  vaccination,  24,  406 
Foot  pound,  663 

Forbes-Waterhouse    sterilizer,    1471 
Force,  395 

Ford,  852,  858,  859,  861 
Foreign  inspection  service,  518 
Formaldehyd,  268,  270 

disinfection,   1391 

food  preservation,  746 

as  an  insecticide,  1393 
Formaldehyd  gas,  disinfection,  1391 
Formalin,   316,   1391 

disinfection,  1414,  1425,  1433 

flies  and,  271 
Formalin-lime  disinfection,   1395 
Fornet,  703 

Foster,  213,  253,  258,  746,  868 
Foster,  G.  D.,  247 
Foulerton,  337 
Fountains,  drinking,  1184 
Fournier,  61,  64,  75,  80 
Fox,  C,  471 
Fracastor,  57 
Fraenkel,   173,  225 
Fragilitas  ossium,  653,  1305 
Framboesia  tropica,  410 


Framingham  demonstration,  164 

Francis,  E.,  22,  23,  264,  296,  306,  321 

Frankel,  L.  K.,  237 

Frankland,  950 

Franklin,  Benjamin,  79 

Franklin  stoves,  986 

Frantzer,  47 

Franz,  322 

Frapolli,  687 

Fraser,  167,  669,  679,  680 

Freeman,  127,  388 

Freeman   pasteurizer,   791 

Freezing,  effect  on  bacteria,  1185 

Freibank  system,  740,  819 

French  pox,  57 

Freud,  S.,  440,  441 

Friedberger,  E.,  209 

Friedemann,  586 

Friedreich,  657 

Friedreich's  disease,  656 

Froelich,  684 

Frosch,  406,  782 

Frost,  388,  390,  392,  591,  786 

Frost,  W.  H.,  237 

Frothingham,   43,   52 

Fruits,  851 

dried,  734 

and  typhoid  fever,  124 
Fuertes,  J.  K.,  1170 
Fugu,  837 
Fuller,  842 
Fuller,  G.  W.,  1217 
Fumigation,  1352,  1390 

aluminum-sulphate  method,  1395 

barium-formalin  method,  1395 

bleaching-powder  method,  1395 

chlorin,  1403 

cholera,  504 

Clayton  furnace,  1401 

cyanid,  of  ships,  514 

definition,  1352 

diphtheria,  205 

formaldehyd,  1391 

formaldehyd  gas,  1391 

formalin,  1391 

formalin-lime  method,  1395 

hydrocyanic  acid  gas,  514,  1402 

insect-borne  diseases,  266 

Kinyoun-Francis  furnace,  1401 

lice,  369 

measles,  218 

oxygen,  1404 

ozone,  1404 

paraform,  1391 

permanganate-formalin  method,   1394 

preparation  of  room,  266,  1390 

rats,  342,  516 

ships,  513 

precautions,  518 


IXDKX 


1525 


Fumigation,  spraying  method,  1395 

sulphur,  of  ships,  517 

sulphur  and  cyanid  contrasted,  516 

sulphur  dioxid,  1396 
liquid,   1399 

sulphur  furnace,  1400 

terminal,   1357 

trioxymethylenc,  1391 
Funk,  669,  679,  680 
Funnel  gas,  506 
Furbush,  E.  M.,  422 
Furnace,  Clayton,  1401 

hot-air,  986 

Kinyoun-Francis,  1401 
Furnatt,  388 
Furs,  arsenic  in,  1305 


Gabritschewsky,  224 
Gaertner,  693,  700,  701 
Gaertner  group,  701 

sources  of  infection,  703 

toxin  production,  703 
Gaertner 's  bacillus,  139 
Gaflfky,  107,  1008 
Gage,'  1137,  1140 
Galactase,  760 
Galeoti,  349 
Gall  sickness,  320 
Galleries,  filter,  1035 
G^lli-Valerio,   314 
Galton,  F.,  618,  619,  631,  633,  658 
Galton's  law,  629 
Garbage,  1219 

can  for,  1476 

Cobwell  's  reduction,  1223 

collection,  1224 

digestion  process,  1220 

disposal  plants,  1224 

flies  and,  315 

hogs,  feeding,  1224 

military  hygiene,   1475 

pit,  1475 

reduction,  1220 
plants,  1223 
Gardener,  157 
Gardner,  M.  S.,  483 
Garget,  781 
Garrison,  688,  692 
Gas,  986 

coal,  904 

illuminating,  944 

water,  944 
Gas  bacillus,  96 
Gasbarrini,   857 
Gases,  and  blindness,  95 

war,  1459 
Gaskell,  253,  258 
Gasoline,  276 


Gastou,  62 

Gates,  F.  L.,  240,  241 

Gatewood,  J.  D.,  1482. 

Gautier,  722 

Gay,  606 

Gayon,  1001 

Gegenbauer,  403 

Geiger,  290 

Geitel,  925 

Gelien,  196 

General  paresis,  434 

Generalized  vaccination,  21 

Gengou,  224,  580 

Gentry,  407 

Geppert,   1365 

Gerard,  William,  107 

Gerber,  417 

Gerhard,  370 

German  measles,  219 

Germi,  857 

Germicides,  choice,  1364 

definition,  1352 

specificity,  1356 

table  of  values,  1373 

See  also  Disinfection 
Gerrish,  75 
Ghon,  170 
Gibson,  562 

Giemsa,  342  ' 

Gillet,  760,  761 
Gillette,  H.  F.,  599 
Giltner,  707,  713 
Ginger,   745 
Ginsberg,  199 
Glaisher,  James,  898 
Glaister,  1324 
Glanders,  396 

agglutination,  398 

antigen,  399 

bacillus  mallei,  396,  398 

complement  fixation,  399 

diagnosis,  397 

immunity,  531 

mallein  test,  397 

ophthalmic  test,  398 

prevention,  400 
Glossina  fusca,  320 
Glossina  morsitans,  318,  320 
Glossina  palpalis,  317,  318,  320 
Glossina  palpides,  320 
Glover,  J.  W.,  1277 
Gloves,  of  the  soldier,  1456 
Glucose,  arsenic  iii,  1306 
Glueck,  B.,  457 
Glutamic   acid,   720 
Glycerin,  rabic  virus,  45 

tetanus,  23 

vaccine  virus,  5,  6 
Goats,  Malta  fever  and,  408,  409 


1526 


INDEX 


Goddard,  425-427,   431,   438,   610,   614, 

616,  617,  657,  658 
Gohoe,  B.  A.,  933 
Goiter,  1150 

in  animals,  1153 

cause,  1154 

endemic,  1151 

in  fish,  1154 

iodin,  1151 

prevalence,  1152 

prevention,  1154 

relation  to  water,  1150,  1154 

simple,  1151 

soil  and,  1010 

thyroid  gland,  1150 
Goldberger,    142,    196,    212,    215,    241, 
265,  296,  365,  372,  373,  434,  687, 
688,   690-692 
Goldberger,  I.  H.,  11 
Goldman,  1320 
Goldmark,  J.,  1288,  1324 
Goler,  778 
Gonococcus,  67 

and  ophthalmia  neonatorum,  87 

and  vulvovaginitis,  69 
Gonorrhea,  67 

and  blindness,  87 

complications,  67 

diagnosis,  68 

prevention,  69 

standards  of  cure,  68 

sterility,  68 

summary,  72 

transmission,  68 
Goodby,  1324 
Goodrich,  97 
Goodwin,  H.  W.,  638 
Gordon,  253-255 
Gordon,  J.  L.,  436 
Gorgas,  238,  301 
Gorham,  841 
Gotchlich,  142 
Gould,  110 
Gout,  651 
Government   control    of    vaccine    virus, 

24 
Graef,  199 

Graham,  264,  304,  711 
Graham-Smith,  195,  20*9,  312,  314 
Granata,  229 
Grancher,  216,  941 
Grant,  249 

Grassi,  259,  264,  286,  287 
Gray,  687 
Grease   trap,    1477 
Greeley,  S.  A.,  1225 
Green,  87 

Green  vitriol,  1408 
Greenberg,  950 


Greenberg,  D.,  1314 

Greenburg,  L.,  1314 

Greenish,  682 

Gregg,  116,  888 

Grehant,  942 

Griffith,  908 

Griffith,   Fred,   167-169 

Griffith,  Stanley,  167 

Grip,  239 

Grit  chambers,  1201 

Grossman,  707 

Ground  water,  997,  1032 

amount,  1033 

filter  galleries,  1035 

gravel  deposits,  1034 

limestone  formations,  1035 

movement,  1033 

sand  deposits,  1034 

sandstone  rock,  1035  , 

temperature,   1034 
Ground-itch,    156 
Grove,  751 
Gruber,  576,  589 
Gruber  reaction,  589 
Grijns,  679 
Guerin,  179,  180 
Guerrero,  852 
Guilfoy,  W.  H.,  1277 
Guinea  worm,  265 
Guiteras,  296,  304 
Guiterrez,  156,  160 
Guldberg,  1363 
Gulick,  L.  H.,  1350 
Gurjun,  balsam,  in  leprosy,  419 
Guriey,  C.  E.,  240 
Guthrie,   196 
Gwens,  685 

Gymnochladus  dioica,  852 
Gynocardate    of    sodium,     in     leprosy, 
419 


Haab,  90 

Haass,  F.  W.,  707 
Habits,  sanitary,  463 
Hfematobia,  308 
Haematopinus  spinulosus,  320 
Haffkine,  145,  146,  349 
Hafifkine's  prophylactic,  349 
Hagenback,  388 
Hagler,  1168,  1172 
Haines,  T.  H.,  436,  456 
Hair  hygrometer,  903 
Halazone,  1134 

disinfection,  1420 
Halberstadter,   92 
Haldane,  735,  867,  874,  875,  877,  889, 

905,  937,  942,  944,  946,  950,  959, 

970,  971,  975,  1308 


INDEX 


1527 


Haldane  apparatus,  878 

Hale,  1409 

Hall,  159,  1153 

Hall,  I.  C,  240 

Halle,  478 

Halliliurton,  720,  746 

Halteiidum,  287 

llaniburfj  cholera  epidemic,  1165 

Hamilton,  267,  1300,   1310 

Hamilton,  Alice,  125,  311 

Hammond,  958,  959 

Hand-to-mouth     infection,     pneumonia, 

238 
Hanks,  N.,  782 
Hanna,  21 

Hansen,  Armauer,  413,  416,  420 
Hanson,  1289 
Hanson,  W.  C,  1324 
Haptophore  group,  549 
Harbitz,  386 
Harden,  20,  685 
Hardy,  992 
Harmscn,  859 
Harries,  1131 

Harrington,  749,  977,  1175 
Harrington,  M.  A.,  455 
Harriot,  760 
Harris,  41,  47,  48,  211,  290,  554,  782, 

862 
Harris,  L.  I.,  1282 
Harrison  law,  4S6 
Hart,  685,  724 
Hart,  B.,  441,  455 
Hartsock,  129 
Hartzell,  1377 
Hassell,  162 
Hasseltine,  H.  E.,  48 
Hastings,  796 
Hausmann,  920 
Havard,  V.,  1442,  1452,  1482 
Havard  latrine,  1473 
Hay  fever,  605 

hereditary  transmission,  655 
Haygarth,  28 
Hayhurst,  E.  E.,  1282 
Haythorn,  S.  E.,  933 
Hazen,    1019,    1029-1031,    1082,    1124, 

1126,  1144,  1148,  1189 
Headgear,  of  the  soldier,  1455 
Health  education,  1328 
Health  insurance,  1291 

tuberculosis,  190 
Health  week,  476 
Heat,  delousing,  366 

dry,  disinfection,  1378 

effects,  in  industry,  1321 

infant  mortality  and,  480 
Heat  loss,  905 
Heat  stroke,  906 


Heat  transfer,  905 
Heaters,  oil,  986 
Heating,  984 

British  thermal  unit,  984 

Calorie,  9,S5 

conduction,  985 

convection,  985 

electric,  988 

fireplace,  986 

Franklin  stoves,  986 

gas,  986 

hot-air  furnaces,  986 

hot-water,  987 

oil,  986 

open  fires,  986 

radiation,  985 

steam,  987 

See  also  Ventilation 
Heberden,  W.,  907 
Heim,   117 
Heine,  386 

Heine-Afedin  disease,  386 
Heinemann,  P.  G.,  813 
Heise,  179 

Heiser,  351,  419,  680 
Hektoen,  L.,  116,  197,  212,  215 
Hellebore,   852 
Heller,   54,   173 
Helvellic   acid,   861 
Hemenway,  H.  B.,  521 
Hemlock,  852 
Hemoglobinuria,  356 
Hemolysins,  575,  860 
Hemolysis,  578 
Hemophilia,   651 

Henderson,   203,   868,  875,   889,  1130 
Henri,    1376 
Henrijean,   102 
Henshaw,  359 
Henson,  295 
Heardman,  840 
Hereditary  ataxia,  656 
Hereditary  transmission,  640 

albinism,  649 

alcoholism,   654 

anaphylaxis,   654 

Baume's  law,  646 

brachydactylism,  652 

cancer,  646 

cataract,   653 

Colle's  law,  646 

color  blindness,  650 

daltonism,  650 

deaf-mutism,  648 

diabetes  mellitus,  653 

epilepsy,   655 

fragilitas  ossium,  653 

Friedreich's  disease,  656 

gout,  651 


1528 


INDEX 


Hereditary  transmission,  hay  fever,  655 

hemophilia,    651 

hereditary  ataxia,  656 

Huntington's   chorea,   655 

inbreeding,   642 

insanity,   658 

in  insects,  260 

leprosy,  418,  648 

marriage,  642 

mental   deficiency,  658 

mental  disease,  424 

mierobic   diseases,   642 

migraine,  654 

myopia,  653 

orthostatic    albuminuria,    654 

polydactylism,  653 

Prof  eta's  law,  646 

retinitis  pigmentosa,   653 

syphilis,  645 

of  a  tendency,  644 

in  ticks,  355,  362 

tuberculosis,    179,-  645 
Heredity,  607 

alcohol,  492 

atavism,  628 

cell,  629 

characters  in  man,   643 

congenital  transmission,  644 

Darwin 's  theory,  621 

determiner,  625  ;. 

dominance,  625 

vs.    environment,   425,   638 

feeble-mindedness,  427 

Galton's  law,  629 

hypersusceptibility,  598 

immunity,  639 

law  of  probability  or  chance,  632 

lead  poisoning,  1296 

Mendel's  law,  624 

mental  deficiency,  425,  426,  437 

mental   disease,  424 

mutation,  622 

neuropathic,  427 

principles,  620 

psychoses,  424 

references,  658 

regression,  629 

reversion,  628 

segregation,  625 

sex-linked,    640 

statistical  methods,  631 

unit  characters,  627 

variation,   621 

vital  statistics,  631 

Weismann's  views,  623 

See  also  Alcohol;  Defectives;  Heredi- 
tary transmission ;  Mental  ■  defi- 
ciency; Mental  diseases;  Mental 
hygiene 


Hering,  E.,   1225 

Herman,   217 

Hermann,  960 

Hermans,  958 

Herms,  W.  B.,  385 

Heroin,   486 

Herter,   744,  770 

Hertmanni,  63 

Hess,  Alfred  F.,  70,  227,  229,  396,  683, 

685,  739,  778,  853 
Hesse,  1314 
Heterozygotes,  627 
Heubner,   759 
Heusinger  desk,  1333 
Hewlett,  198 
Heymann,  891,  961-963 
Hickey,  C.  H.,  748 
Highet,  680 
Hill,  870,  871,  895,  907,  908,  916,  1006, 

1189 
Hill,  L.,  888,  891,  892,  962 
Hilliard,  1185 
Hindley,   315 
Hinds,   274 
Hinton,  W.  A.,  581 
Hippelates,  311 
Hippobosea  rufipes,  320 
Hippocrates,  95 
Hirsch,  683 
Hirschfelder,  366 
Hirt,  948 

Hiss  method,   1498 
Histamin,  856 
Histidin,   720 

History.     See  under  each  disease 
Hitchcock,  472 
Hite,   1377 
Hodge,  C.  F.,  314 
Hodge  fly  trap,  315 
Hoffman,   745 

Hoffman,  F.  L.,  648,  933,  1314 
Hoffman,   J.  D.,  989 
Hofmeister,  719 
Hog  cholera,   meat   and,   828 
Hog  cholera  group,  701 
Hogarth,  A.  H.,  1350 
Hogs,  garbage,  feeding,  1224 
Holcomb,  E.  C,  84 
Holdy,  345 

Hollmann,  413,  415,  417 
Holmgren   test,   923 
Hoist,  684 
Holt,   70 

Holt,  L.  E.,  482 
Homozygotes,  627 
Hookworms,   154,   155,  314 

mode  of  entrance,  156 

resistance,  157 

species,  154 


INDEX 


1529 


Hookworm  disease,  153 

campaign,    collateral    benefits,    161 

plan,  160 
chenopoilium,  159 
cleanliness,    160 
distribution,  153 
education,  160 
eradication,  158 
ground-itch,   156 
immigration,   161 
immunity,  157 
in  miners,  1323 
miner's  anemia,  153 
modes  of  transmission,   154 
parasite,  154,  155 

mode  of  entrance,  156 
resistance,  157 
personal  prophylaxis,  160 
prevalence,  153 
prevention,  158 
references,   162 
soil  pollution,  158,  1011 
thymol,   158 
Hope,  480 

Hopkins,  5S7,  670,  720 
Hopkins,  J.  G.,  62 
Hoplopsyllus  anomalus,  327 
Horner,  225,  650 
Horrocks,  408,  409 
Horse  meat,  589,  817 
Horsley,  50 

Hospitals,  mental  diseases,  451 
statistics,  1255 
venereal  diseases,  85 
Host,  524,  546 
Hot-air  furnaces,  986 
Hot-water  heat,  987 
Hougardy,    760 
House  sewers,  1193     , 
Household  filters,  1127 
Housing,   473 
crowding,  474 
tuberculosis,   186 
types  of  dwellings,  474 
Houston,   1003,  1132 
Howard,  307 

Howard,  L.  0.,  291,  312,  385 
Howarth,  695 
Hoyges,   45,   47,   54 
Huisbard,  311 
Hueppe,  526,   769 
Huggard,  899 
Hume,  411 
Humidity,    896 
climate  and,  898 
Crampton  value,  906 
importance  wet-bulb  temperature,  907 
influence,  905 
Kata- thermometer,  907 


Humidity,  methods  of  determining,  900 
dewpoint,  903 
hair  hygrometer,  903 
psychrometer,  901 
wcigliing,  9uO 
relation  to  health,  904 
textile  mills,  13j.7 
Humoral  theory,  529 
Humus,  992 
Hunger,    674 
Hunt,   724 
Hunter,   575 
Hunter,   W.   D.,   360 
Hunterian  chancre,  58 
Huntington,  655 
Huntington's  chorea,  655 
Huntoon,  253,  254,  258 
Huppe,  700 
Husk,  372 
Hutchins,  120 
Hutching,  K.  H.,  1188 
Hutchinson,  65,  940 
Hutchinson,  Jonathan,  415 
Huxley,  76 
Huxley,  T.  H.,  658 
Hyatt,  J.  W.,  1122 
Hydatid  disease,  265 
Hydrochloric  acid  vapors,  946 
Hydrocyanic  acid,  268,  325 
Hydrocyanic  acid  gas,  273,  505 
bedbugs,   515 
disinfection,   1402 
fleas,   515 
lice,  515 
mosquitoes,  515 
rats,  515 
roaches,  384 
ships,  514 

and  sulphur  contrasted,  516 
Hydrofluoric   acid,    748 
Hydrogen  peroxid,   749,  871 

disinfection,  1415 
Hydrogen  sulphid,  947,  1309 

in  sewers,  948 
Hydrophobia,  38 
Hygiene,  definition,  523 

See   Industrial   hygiene;    Mental   hy- 
giene;   Military  hygiene;   Ocular 
hygiene;   Oral  hygiene;  Personal 
hygiene;   Sex  hygiene, 
Hymenolepis  diminuta,  265,   338 
Hymenolepis  nana,  265,  338 
Hypermetropia,  922 
Hypersensitiveness,  593 
Hypersusceptibility,  593 

definition,    523 
Hyperthyroidism,   1151 
Hypochlorites,  1133 
Hysteria,  442 


1530 


INDEX 


Ice,  1184 

bacteria  and,  1185 

can,  1187 

and  disease,  1188 

manufactured,  1186,  1187 

natural,  1186 

plate,  1187 

and  typhoid  fever,  120,  1188 
Ice  box,  1479 

temperature,    731 
Ice  cream,  and  typhoid  fever,  123 
Ichthyotoxismus,  837 
Idiopathic  tetanus,  99 
Idiots,  609 

alcohol  and,  431 
Igal,   1412 

Illicium  anisatum,  852 
Illicium  religiosum,  852 
Illuminating  gas,  944 
Illumination,  921 
Imbeciles,  609 
Imhoff   tank,   1202 
Immigration,  hookworm  disease,  161 

mental  diseases,  450 

See  also  Vital  statistics 
Immune  bodies,  524 
Immunity,  523 

acquired,  532 

active,  532 

addiment,  577 

agglutination,  589 
methods,  590 

agglutinins,  589 
group,   592 
specific,  592 

alcohol  and,  546 

alexin,  551,  577 

allergy,  593 

amboceptor,  551,  577 

anthrax,  529 

antibiosis,  525 

antibodies,  524 

antigens,  524,  580 

antitoxic,  553 

antitoxins,  557 

approach,  571 

atreptic,  528 

autohemolysins,   585 

bacteriolysins,  575 

blood,  530 
tests,  587 

Bordet-Gengou  phenomenon,  580 

carriers,  540 

cellular,   529 

cerebrospinal  fever,  252 

chemotaxis,  571 

cholera,  145 

communicability,    526 

complement,  551,  552,  577 


Immunity,  complement  fixation,  580 
copula,   577 
cytase,  551,  577 
cytolysins,  575 
cytotoxin,  579 
definition,  523 
degree,  524 
desmon,  551,  577 
deviation  of  complement,  583 
digestion,   571 

diphtheria,  199,  200,  204,  205 
drugs,  546 
dysentery,  149 
endotoxins,   565 
engulfment,  571 
exhaustion  theory,  528 
exposure,  543 
famine,  545 
fasting,  532 
fatigue,  532,  544 
fixative,  551,  577 
.  gastrotoxin,  579 
general,  538 
glanders,    531 
haptophore  group,  549 
hemolysins,  575 
hemolysis,  578 
hepato toxin,    579 
heredity,  639 
hookworm  disease,  157 
host  and  parasite,  546 
how  acquired,  533 
humoral  theory,  529 
hypersensitiveness,  593 
hypersusceptibility,  593 
immune  body,  524,  551,  577 
immunism,  577 
infantile  paralysis,  390 
influenza,  244 
inheritance,  526 
insufiicient  food,  544 
interbody,  577 
intermediary  body,  551,  577 
invasive  power,  525 
isohemolysins,  585 
Koch's  laws,  526 
latency,  542 
leprosy,  413 
leukociden,  579 
local,  538 
lysins,  575 

nature,  576 
macrocytase,  573 
macrophages,  572 
malaria,   289 
measles,  213 
mechanism,  527 
microcytase,  573 
microphages,  572 


INDEX 


1531 


Immunity,  mixed,  533 

natural,  530 

Neisser-Wcehsborg  phenomenon,  583 

nephrotoxin,  579 

non-specific,  532 

opsonic  index,  574 

opsonins,  574 

overexertion  and,  544 

paratyphoid  fever,  138 

passive,  532 

Pasteur  treatment,  49 

Pfeiffer's  phenomenon,  576 

phagocytosis  and,  570 

philacytase,  577 

plague,  348 

pneumonia,  234 

precipitinogen,  585 

precipitins,  585 
specificity,  587 

precipitum,  585 

preparative,  551,  577 

receptors,  549,  550 
orders,  552 

references,  606 

resistance,  524 
lowered,  542 

retention  theory,  528 

scarlet  fever,  223 

sensitizer,  551,  577 

side-chain  theory,  547 

smallpox,   14 

specificity,  537 

spermotoxin,  579 

symbiosis,  525 

syncytiolysin,  580 

syphilis,  63 

theories,  528 

tolerance,  524 

toxicity,  525 

toxin,  549 

toxon,  557 

toxophore  group,  549 

tropin,  574 

tuberculosis,  177,  545 

unit,  567 

virulence,  525,  527 

virus,  534 

Wassermann  reaction,  58] 

whooping-cough,  226 

yellow  fever,  296 

zwischenkorper,  531 
Impetigo,  1348 

Impetigo  contagiosa,  vaccination,  22 
Impounding  reservoirs,  1030 

stagnation,  1030 
Inabo,  225 
Inada,  335 
Inanition,   481 
Inbreeding,  642 


Incinerators,  1473 
Inclined  disc  screen,  1201 
Incubation  period,  extrinsic,  259 

rabies,  39 

syphilis,  55 

tetanus,  100 

typhoid  fever,  106 
Index,  median  endemic,  472 
Indian  kala-azar,  380 
Indices    of     a     successful    vaccination, 

12 
Indirect  infection,  460 
Industrial  accidents,  1290 

Case  Vennes   vs.   New  Dells  Lumber 
Company,  1291 
Industrial  conditions,  and  tuberculosis, 

187 
Industrial  hygiene,  1279 

accidents,  preventable,  1290 

anilin  poisoning,  1310 

arsenic,  1305 

benzol  poisoning,  1310 

brass  founders '  ague,  1311 

carbon  disulphid,  1311 

communicable  infections,  1322 

compensation  laws,  1290 

cooks,  1289 

domestic  employees,  1289 

efficiency,   1285 

employer 's  liability,  1290 

factory  inspection,  1289 

fatigue,  1284 

fundamental    considerations    in    pre- 
vention, 1283 

heat,  effects,  1321 

hours  of  work,  1284 

housewives,  1289 

infant  mortality,  1288 

insurance,  1291 

manganese  poisoning,   1311 

mining,  1319 

minors,  1286 

Monday  effect,  1285 

noise,  effects,  131 

saleswomen,  1289 

sedentary  occupations,  1291 

textile  industries,  1316 

women,  1287 

wood  alcohol  poisoning,  1312 

See  also  Arsenic ;  Carbon  •  monoxid ; 
Child  labor;  Dust;  Fumes;  Lead 
poisoning;  Mercurial  poisoning; 
Mining;  Occupational  diseases; 
Phosphorus  poisoning 
Inebriety,  432 
Infant  mortality,  477,  1275 

alcohol,  481 

cause,  479 

dysentery,  481 


1532 


INDEX 


Infant  mortality,  feeding,  480 
artificial,  481 
breast,  481 

formula,  1493 

gastro-intestinal  diseases  and,  480 

heat,  480 

industrial  hygiene,  1288 

pneumonia,  481 

prenatal  care,  482 

prevention,  482 

social  conditions,  478 

syphilis,  481 

temperature,  894 

tuberculosis,  481 
Infantile  paralysis,  386 

air-borne  theory,  392 

carriers,  391 

deformities,  prevention,  393 

dust,  392 

epidemics,  387 

epidemiology,  388 

immunity,  390 

insect-borne  theory,  391 

mortality,  212 

prevention,  392 

transmission,  390 

virus,  389 

resistance,  389 
Infection,  air-borne,  939 

channels,  460,  463 

contact,  460 

cross,  941 

definition,  523 

droplet,  460,  940 

food,  696.     See  also  Food  infection 

indirect,  460 

ingestion,  tuberculosis,  172 

personal  prophylaxis  and,  463 

sources,  459 

animals,  lower,  459 

See  also  Carriers 
Infectious  disease,  463,  525 
Infectious  ophthalmoplegia,  394 
Influenza,  239 

administrative    measures,    245 

closing  schools,  245 

epidemics,  240 

epidemiology,   241 

etiology,  241 

immunity,  244 

incubation  period,  244 

isolation,  245 

masks,  245 

mode  of  infection,  241 

mortality,  240 

personal  prophylaxis,  245 

vaccines,  244 
Infusoria,  1051 
Ingestion  infection,  in  tuberculosis,  172 


Inheritance,  immunity,  526 
Inoculation,  smallpox,  26 

typhoid,   128 
Inorganic  salts,  669 
Insane,  definition,  423 

number,  422 
Insanity,  alcoholic,  489 

cost,  422 

definition,  423 

forms,  423 

hereditary  transmission,  658 

morphinism,  433 
Insect-borne  diseases,  259 

deer-fly  fever,  321 

dengue,  303 

ectoparasites,   261 

endoparasites,  261 

extrinsic  period  of  incubation,  259 

filariasis,  305 

fumigation,   266 

general  considerations,  259 

-host,  definitive,  259 
intermediate,  259 

infantile  paralysis,  391 

Japanese  river  fever,  361 

leishmaniasis,  380 

malaria,  286 

pappataci  fever,  322 

personal  prophylaxis,  263 

plague,  345 

references,  385 

relapsing  fevers,  361 

Rocky  Mountain  spotted  fever,  356 

sleeping  sickness,  317 

table,  264 

Texas  fever,  356 

transmission,  biological,  259 
fomites,  261 
mechanical,  259 

trench  fever,  376 

typhus  fever,  370 

yellow  fever,  295 
Insecticides,  266 

arsenate  of  lead,  276,  277 

arsenate  of  lime,  277 

arsenic,  276 

arsenious  oxid,  276 

Bordeaux  mixture,  278 

carbon  bisulphid,  274 

carbon  tetrachlorid,  275 

classification,  266 

coal  oil,  275 

formaldehyd,  270,  1393 

hydrocyanic  acid  gas,  273 

kerosene,  275 
emulsion,  278 

lime  dips,  270 

Mim's  culicide,  272 

Paris  green,  276 


INDEX 


1533 


Insecticides,  petroleum,  275 

phenol-camphor,  272 

pyrethrum,  271 

relative  cftii'ioncy,  267 

rcsin-limp  inixtiire,  278 

Scheolc  's  green,  276 

specificity,  266 

sulphur,  269 
flowers  of,  269 

sulpliur  dioxid,  269 

sulphur  (lips,  270 

table,  268 

tobacco,  271 
Insects,  259 

cleanliness,  263 

hereditary  transmission,  260 

leprosy,  415 

smallpox,  31,  313 

specificity,  260 

suppression,  263 

See    also    Insecticides;     Insect-borne 
diseases 
Inspection  of  factories,  1289 
Inspection  service,  foreign,  518 
Insurance,  health,  1291 

sickness,  1291 
Insurance  records,  1255  , 

Intelligence  quotient,  610 
Intercepting  sewers,  1193 
Intermediate  grouj),  701 
International  Health  Board,  160,  162 
International     list,     causes     of     death, 

1272 
Interstate  quarantine,  519,  520 
Invasive  power,  525 
lodin,   disinfection,  1417 

goiter,  1151 
Ipecac,  dysentery,  150 
Ireland,  W.  W.,  431 
Iron  pipes,  1081 

Iron  sulphate,  water  purification,   1142 
Iron  vitriol,  1408 
Ishiji  filter,  1470 
Isohemolysins,  585 
Isolation,  498,  499,  501 

carriers,  462 

influenza,  245 

measles,  217 

pneumonia,  237 

smallpox,  35 

tuberculosis,  182 
Issaeff,  589 
Itch-mite,  269 

Ithaca  typhoid  epidemic,   1177 . 
Ixodidae,  354 

Jackson,  684 
Jackson,  James,  250 
Jacoby,  856 


Jahn,  225 

James,  293,  306 

.lanct,  443 

Japanese  river  fever,  361 

Javello  water,  disinfection,  1420 

Jeanselme,  417 

Jefferson,  Thomas,  3 

Jellies,  736 

Jelmoni,  852 

Jenner,  Edward,  1,  2,  3,  5,  9,  11,  12,  16, 

20,  25,  34,  38,  528 
Jennerian  vesicle,  12 
Jenner 's  claim  for  vaccination,  20 
Jenner  's  golden  rule,  9 
Jennings,  A.  F.,  707 
Jennings,   C.   A.,  707 
Jensen,  813 
Jequirity  bean,  554 
Jessen,  959 
Jesty,  Benjamin,  1 
Joehmann,  372 
Jodlbauer,  A.,  919 
Jorger,   615 
Jogichess,  388 
Johannessen,  599 
Johnson,  1394 
Johnson,  G.  A.,  1132,  1189 
Jolles,  761 
Joly,  416 
Jones,  48,  49,  57 
Jones,  H.  N.,  1432 
Jordan,    595,    596,    600,    639,   700,    722, 

782,  852,  853,  858,  870,  871 
Jordan,  E.  0.,  237,  863 
Joslin,  Allen,  187 
Joule,  988 
Journet,  889 
Jukes  family,  615 

Kaffirpox,  25 

Kaiser,   137 

Kakke,  678 

Kala-azar,  321,  380 

Kalbrunner,  271 

Kallikak  family,  616  • 

Kalmia  latifolia,  830,  852 

Karsner,    867 

Kastle,  117,  312,  761,  762 

Kata-thermometer,  907 

Katayama  disease,  265 

Kayser,  111,  117,  127,  702,  703 

Kedrowski,  W.  J.,  420 

Keefer,  F.  E.,  1470,  1482 

Kefir,  771 

Keith,  S.  C,  1185 

Keller,  759 

Kellicott,  616,  618,  626 

Kellogg,  W.  H.,  344 

Kempner,  320,  715 


1534 


INDEX 


Kendall,  112,  770,  1367,  1371 
Kennedy,  27,  409. 
Kenotoxin,  960 
Kensett,  Thomas,  738 
Kent,  320 

Kent,  A.  F.  S.,  1285 
Kenwood,  975,  980,  986 
Kerner,  710 
Kerosene,  268-275 
emulsion,  278 
lice,  368 
Kerr,  J.  W.,  25,  88,  91,  345,  1153 
Kershaw,  G.  B.,  1217 
Keyes,  72 

Kilborne,  264,  355,  356 
Kimball,  1152 
Kimball,  D.  D.,  971 
Kimberley,  E.,  1217 
Kinderblattern,  28 
King,  156,  160,  287,  289,  359,  638 
King,  W.  I.,  1278 
King  system  of  ventilation,  983 
Kinghorn,   318 
Kinnicutt,  942,  1217 
Kinyoun,  235 

Kinyoun-Francis  furnace,  1401 
Kionka,  749 
Kirkwood,  J.  P.,  1114 
Kister,  333 
Kitasato,  16,  95,  96,  101,  210,  265,  325, 

414,  417 
Kitashima,  558 
Kitchen  incinerator,   1473 
Kjeldahl  method,  804 
Klebbs,  651 

Klein,  126,  220,  311,  840 
Kleine,  318 
Kligler,  148,  553 
Klimenco,  225 
Kline,  248 
Kling,  390,  391,  396 
Klinger,  113,  932 
Klotz,  O.,  927,  933 
Knab,  288 
■  Knight,  A.  S.,  237 
Knopf,   185 
Knorr,  558 
Kober,    74,    119,    311,    746,    1168-1170, 

1324 
Kobert,  856,  859,  860 
Kobrak,  222 
Koch,  526,  780,  1003,  1008,  1088,  1365, 

1406 
Koch,  Joseph,  39 
Koch,  Eobert,  127,  128,   139,  143,  144, 

164,  166,  191,  287,  290,  293,  318, 

319,  350,  361,  401 
Kocher,  1155 
Koch's  laws,  526 


Kolle,  107,  128,  130,  142,  146,  149,  349, 

576,  589,  606 
Kolle 's  method,  348 
Kolloy,  486 
Kolmer,  234 
Koniscope,  935 
Konrich,  870,  871 
Konstansoff,   839 
Koplik   spots,   217 
Koppe,  724 
Korn,  786 

Korsakoff's  disease,  489 
Korsakow  's  disease,  429 
Kossel,  168 
Kraepelin,  431,  490 
Kraus,  606 
Kraus,  E.,  585,  586 
Krause,    176-178,    388,    602 
Kronecker,  889 

Kronig,  1362,  1363,  1407,  1423 
Krumwiede,  Charles,  111,  117,  138,  167, 

247,   257,  592 
Kruse,  247,  320,  769 
Kiichenmeister,  695 
Kumyss,  771 
Kurrimoto,  49 
Kurth,  220 
Kutcher,  703,  856 
Kyers,  V.  C,  853 

Labarraque  's  solution,  1420 
Labeling,  foods,  728 
Laboratory  course,  1483 

bacterial   vaccine,    1492 

diphtheria  diagnosis,  1496 

meningococcus  carrier  detection,  1499 

meningococcus  isolation,  1499 

milk,  1489 

pneumoccccus,  classification,  1498 

Schick  test,  1497 

standardization  of  disinfectants,  1485 

vital  statistics,  1493 

water,  1486 
Lactalbumin,  milk,  756 
Lactic  acid,  milk,  769 
Lactoglobulin,   milk,   756 
Lactokinase,  760 
Lactose,  milk,  759 
La  grippe,  239 
Lakes,  1028 

purification,  1111 

stagnation,  1030 
Lamarck,   622 
Lamarck,  J.  B.,  658 
Lamb,  322 

Lamblia  intestinalis,  265,  338 
La  Motte,  E.,  483 
Lampson,  H.  G.,  176 
i   Lancerau,  335 


INDEX 


1535 


Landouzy,  335 

Landsteiner,  219,  386,  389 

Landtshcer,  761 

Langworthy,  C.  F.,  665 

Lanolin,  66,  82 

Lantz,  345 

Lanus  magistus,  321 

Lapage,  426 

La  rage,  38 

Larkspur,  852 

Larson,  1377 

Larvicides,  283,  316 

Latency,  542 

Latent  malaria,  290 

Lateral  sewers,  1193 

Lathyrism,  857 

Lathyrus  cicera,  857 

Lathyrus  satirus,  857 

Latrines,   1473 

Laubenheimer,  K.,  1413 

Laurans,  417 

Laurels,  852 

Lausen  epidemic,  1168 

Laveran,   A.,   264,   286,  287,    295,   320, 

335,  380,  1441 
Lavinder,  388,  687 
Lavoisier,  866 

Lawrence  typhoid  epidemic,  1169,  1178 
Layet,  14,  1300 
Lazear,  J.  W.,  259,  264,  296 
Leach,  682 
Lead,  1082 

mining,  1300 

oxid,   1297 

red,  1294,  1295,  1297 

refining,  1300 

smelting,  1300 

sprays,  279 

white,  1298 
Lead  poisoning,  1155,  1293 

abortion,  1296 

cases,  1158 

chronic,  1296 

cleanliness,  1301 

cumulative  action,  1293 

diagnosis,  1296 

diamond  polishing,  1300 

dust,  1294 

earthenware,  1299 

effect  on  offspring,  1296 

file  cutting,  1300 

industries,  1300 

mining,  1300 

mode  of   contraction,   1294 

painters,  1297 

palsy,   1295 

personal  prophylaxis,   1301 

pottery,  1299 

prevention,  1301 


Lead  poisoning,  red,  1297 

refining,  1300 

smelting,   1300 

susceptibility,  1293 

symptoms,  1157 

water,  1155 

white,  1298 
Leake,  125 

Leather,  clothing  of  the  soldier,  1455 
Leaves,  850 

rhubarb,  853 
Le  Bailly,  240 
Leblane,  41,  777 
Leboeuf,  414 
Lecky,  86 
Le  Dantic,  97 
Ledbetter,  Kobert  E.,  83 
Lederer,  A.,  1149 
Leeds,  A.  E.,  1122 
Legge,   T.   M.,   1294,   1296,   1297,   1299, 

1307,  1322,  1324 
Leggings,  1456 

Legislation,  ophthalmia  neonatorum,  91 
Lehmann,  948,  958,  959,  963 
Leidy,  310,   730,  832 
Leighton,  817 
Leighton,  Marshall  0.,  119 
Leiper,  1183 
Leishman,   W.   B.,    128,    130,   362,   381, 

574 
Leishman-Donovan  body,  381 
Leishmania  donovani,  380 
Leishmania  infantum,  380 
Leishmania  tropica,  381 
Leishmaniasis,  380 

bedbug,  382 

prevention,    382 

transmission,  382 
Lemblee,  700 
Lemke,  117 
Lenhart,  1153 
Lentz,  137 
Lenz,  59 
Le  Pileur,  84 
Le  Prince,  279,  281,  290 
Leprolin,  419 
Leprosaria,  418 
Leprosy,  411 

bacillus  leprae,  413,  416 

chaulmoogra  oil,  419 

flies,  416 

Gurjun  balsam,  419 

gynocardate  of  soda,  419 

hereditary  transmission,  418,  648 

immunity,  413 

insects,  415 

leprolin,  419 

leprosaria,  418 

lice,  416 


1536 


'INDEX 


Leprosy,  modes  of  transmission,  415 

mosquitoes,  416 

nasal  secretions,  416 

nastin,  419 

personal  prophylaxis,  418 

prevalence,  412 

prevention,  418 
specific,  419 

quarantine,  508 

in  rats,  337,  414 

references,  420 

sarcoptes  scabei,  416 

segregation,  418 

sexual  contact,  417 

symbiosis,  413 

tuberculin,  419 

vaccination,   22 

Wassermann  reaction,  419 

X-ray,  419 
Leptospira  icterohemorrhagiae,  335 
Leptospira  icteroides,  264,  296 
Leptus  akamushi,  361 
Leredde,  59 
Leslie,  290 
Leucin,   720 

Leukocytes,  in  milk,  762 
Leukomains,  721,  722 
Levaditi,  219,  389,  390,  606 
Levin,  648,  780 
Levy,  101,  117,  213,  234,  703 
Levy,  L.,  707 
Lewaschew,  910,  912 
Lewes,  G.  H.,  957 
Lewes,  V.,  948 
Lewis,  320,  386 
Lewis  incinerator,  1473 
Lice,  362 

body,  363 

clothes,  363 

crab,  363,  365 

delousing,  366 

dog,  265 

fumigation,  369 

head,  1347 

hydrocyanic  acid  gas,  515 

kerosene,  368 

leprosy,  416 

licicides,   368 

life  history,  363 

as  a  military  problem,  369 

N.  C.  I.  powder,  368 

nits,  1347 

petroleum,  275 

species,  362 

sulphur,  269 

sulphur  dioxid,  517 

table,  265 

transmission  of  disease,  365 

Trench  fever,  376 


Lice,  typhus  fever,  373 

See  also  Delousing 
Liceaga,  301 
Licicides,  368 
Lieb,  179 
Liebig,  666,  816 
Liebreich,  746 
Lies,  417 

Life  insurance  and  syphilis,  63 
Life  tables,  1276 
Light,  916 

fluorescence  9,19 

fluorescent  substances,  919 

method  for  measuring,  921 
photometers,   921 

phosphorescence,  919 

photodynamic  action,  919 

physiologic  action,  917 

snow  blindness,  918 

sunlight,  917  • 

ultraviolet  light,  918 

-ultraviolet  rays,  918 
Lighting,  920 

Luxfer  prisms,  1335 

schools,  1335 
Lime,      chlorinated.      See     Chlorinated 
lime 

dips,  270 

disinfection,  1416,  1426,  1432 

milk  of,  1416,  1426,  1433 

slaked,  1416 
Limneeus,  265 
Lincoln,  A.,  782 
Lindner,   388 

Linen,  clothing,  of  the  soldier,  1455 
Linenthal,  H.,  1432 
Linhard,  888 
Linnaeus,  416 
Lipardi,   248 
Lipase,  760 
Lipovaccines,  536 

typhoid,  128 
Liquid  chlorin,  1139 
Liquor  cresolis  compositus,  1412 
Lisboa,  407 
Lister,  236,  939 
Litharge,   1294,  1295,  1297 
Little,  682 
Liver  fluke,  265 
Loam,  992 

Lobar  pneumonia,  230 
Lock,  623 
Lock,   E.   H.,   658 
Lockhart,  J.  G.,  387 
Lockjaw,  95 
Locomotor  ataxia,  435 
Lode,  248 

Loeffler,  343,  700,  702,  782 
Loffler,  209,  219,  406 


INDEX 


1537 


Loewe,  394 

Logan,  1324 

Loiiihioso,  608,  687,  691 

London  purple,  277 

Londonderry,  iS".  .S'.,  957 

Lt)ng,  744 

Longfellow,  K.  C,  385 

Looss,   156 

Lorenz,  198,  434 

Lorinsor,  1304 

Losch,  150 

Louis,  107,  370 

Lovett,  E.  W.,  391 

Low,  287 

Lowe,  267 

Lowell  typhoid  epidemic,  1169,  1178 

Lowered  resistance,  542 

Lubarsch,  575 

Lucas,  215,  390 

Luce,  1310 

Liibberd,   959 

Lunisden,  117,  123,  135,  312 

Lung  fluke,  265 

Lungs,  vital  capacity,  969 

Lupines,  852 

Lusk,  G.,  863 

Lustig,   349 

Luttinger,  225,  226 

Lutz,  888 

Luxfer  prisms,  1335 

Lyle,  J.  I.,  971 

Lrmph,  vaccine,  5 

Lynch,  338 

L}Tieh,  C.  C,  238,  241 

Lyons,  57,  486 

Lysins,  575 

nature,  576 
Lysol,  1412 
Lyssa,   38 
Lyster  bag,  1472 

Maar,  870 

Maasen,  1001 

McCall  incinerator,  1473 

MacCallum,  287 

McCarrison,  1155 

McCaskey,  707 

McClintic,  360 

McClintie,  T.  B.,  1367,  1371,  1373 

McClintick,   31,  358,  359 

McClintoek,  267,  1425 

McClintock,  C.  T.,  1410 

McCollum,   E.   v.,   221,    670,   672,   684, 

739,  753,  758,  770,  815,  848,  850, 

851,  863 
McCormack,  354 
McCoy,  G.  W.,  22,  195,  237,  241,  264, 

321,  322,  327,  333,  344-346,  350, 

413,  414 


McCulloch,  814 

MacCurdy,  J.  T.,  456 

McDermott,  1398 

McDonald,  304,  419 

Macfadyen,  408,  731,  1184 

McFarland,  536 

Macfie,  893,  899,  916,  955,  989 

Mack,  C,  490 

McKeever,  D.,  1176 

McLaughlin,  1148 

McLaughlin,  A.  J.,  1265 

McLouglilin,  144 

MacMillan,  486 

McNair,  .1.  B.,  855,  856 

MacXeaJ,   688,   692 

MacNeal,  W.  J.,  :\7r,,  DHl 

McNeal,  317 

MacXutt,  1148 

MacXutt,  J.  S.,  521,  813 

McPherson,   1130 

Macrocytase,  573 

Macrophages,  572 

McVail,    218 

McYail,  J.  C,  38 

:Madsen,  563,  716,  1363,  1407 

Magruder,   372 

Mair,  843 

Mair,  L.  W.  D.,  124 

Maisonneuve,  66 

Maize,  689 

Mai  de  Caderas,  320 

Malachite  green,  1422 

Malaria,  286 

carriers,  289 

estivo-autumnal,  287 

immunity,  289 

latent,  290 

mosquito,  297 

personal  prophylaxis,  291 

prevention,  290 

contrasted  with  yellow  fever,  303 

quinin  prophylaxis,  292 

quinin  treatment,  295 

references,  295 

tropical,  287 

transmission,  287 
Malignant  edema,  soil,  1008 
Malignant  purpuric  fever,  250 
Malignant  pustule,  401 
Mallein  test,  397 
Mallon,  Mary,  114,  115 
Mallophaga,  362 
Mallory,  209,  220,  225,  537 
Mallu,  388 
Malta  fever,   407 

dust,  408 

goats,  408,  409 

Micrococcus  melitensis,  407,  410 

milk,  782 


1538 


INDEX 


Malta    fever,    modes    of    transmission, 
407 

mosquitoes,  408 

prevention,  410 
Management    epidemic    campaign.     See 

Epidemics 
Handler  filter,   1127 
Manganese  poisoning,  1311 
Mankato  typhoid  epidemic,  1176 
Mann,  52,  53,  707 
Manneberg,  287 
Manning,  988 

Manson,  259,  264,  287,  306,  362 
Manson,  P.  T.,  288 
Manteufe,  362 
Mantoux,  971 
Manufactured  ice,  1187 
Manure,  flies  and,  315 
Marasmus,  481 
March,  L.,  1271 
Marching,  1459 

bathing,  1462 

discipline,  1462 

double  time,  1459 

feet,  care,  1463 

forced,  1461 

quick  time,  1459 
Marchoux,  296,  414,  420 
Marcus,  615 
Marfan,  760 

Margaropus  annulatus,  356,  357 
Marie,  43,  54,  443 
Marine,  1152,  1153 
Marital  conditions,  death  rates,  1271 
Maritime  quarantine,  bill  of  health,  509 

cholera,  503 

detention  period,  502 

disinfection  of  ships,  511 

equipment,  510 

foreign  inspection  service,  518 

fumigation  of  ships,  513 

leprosy,  508 

national  vs.  state,  519 

plague,  505 

procedures,  509 

qualifications  of  officer,  511 

smallpox,  504 

typhus   fever,   507 

vessels,  502 

yellow  fever,  507 

See  also  Quarantine 
Marker,  981 
Marlatt,  276,  378 
Marmots,  326,  344 
Marriage,  consanguineous,  642 

hereditary    transmission    of    disease, 
642 

mental  deficiency,  428 

syphilis  and,  64,  436 


Marriage,    and    the    Wassermann    reac- 
tion, 65 
Marriage  rates,  1234 

factors  influencing,  1234 
Marriage  registration,  uses,  1234 
Marriage  statistics,  1233 
Martin,  326,  327,  655,  1361,  1367,  1371 
Martin,  C.  J.,  349 
Marx,  592 
Marx,  E.,  54 
Marzari,  687 
Masks,  485 

in  influenza,  245,  485 
Mason,  313 
Mason,  W.  P.,  1189 
Mason's  phthisis,  932 
Matches,   1303 
Mathieu,   335 
Mattauschek,  59,  435 
Maver,  358,  359 
Maxcy,  K.  F.,  925 
Mayer,  320,  710 
Mayet,  1153 
Mayow,  J.,  866 
Mayr,  P.,  215 
Meader,  116 
Measles,  212 

air-borne,  216 

cross-infections,   216 

desquamating  epithelium,  215 

droplet  infection,  216 

epidemiology,  213 

in  the  Faroe  Islands,  214 

"fourth  disease,"  219 

German,  219 

immunity,  213 

isolation,  217 

koplik  spots,  217 

modes  of  transmission,  215 

mortality,  212 

prevention,  217 

resistance  of  virus,  214 

in  the  Sandwich  Islands,  214 

schools  closed,  218 

terminal  fumigation,  218 

and  tuberculosis,  178 
Measly  tapeworm,  834 
Meat,  814 

actinomycosis,  828 

abattoir,  819 

animal  parasites,  830 

anthrax,  827 

beef  extracts,  816 

beef  juice,  816 

beef  tapeworm,  835,  836 

bob-veal,  846 

composition,  814 

dried,  733 

echinococcus  disease,  836 


INDEX 


i,j;39 


Moat,  emergency  slau^rliter,  823 

Freihniik  system,  822 

liofr  eliolera,  828 

horse,   589,   817 

inspection,  818 
ante  mortem,  825 
law,   825 
post  mortem,  826 

inspector,  822 

kinds,  816 

measly  tapeworm,  834 

metliods  of  slaugliter,  824 

Nothschlachtung,  823 

nutritive  value,  815 

partridge  poisoning,  829 

pickled,  736 

poisoning,  828 

pork  tapeworm,   834 

powdered,  734 

preservatives,   818 

prevention  infections,  818 

pyemic  conditions,  828 

septic   conditions,   828 

sources,  816 

spoiled,  recognition,  817 

structure,   814 

swine  plague,  828 

taenia  saginata,  835 

tapeworm,  828 

three-class  system,  822 

trichinosis.     See  Trichinosis 

tuberculosis,  826 
Mechanical  filtration,  1122,  1125 
Median   endemic  index,  472 
Medical    inspection,    of    schools,    1338, 

1340 
Medical  officer,  military,  1450 
Medin,  386 

Mediterranean  kala-azar,  380 
Medlar,  220 
Meinicke,  703 
Melick,  J.,  124 
Melier,  300 
Meltzer,  235,  971 
Melville,  73 
Melzel,  A.,  944 
Mendel,   554,   607,   620,   624,   625,   670, 

672,  676,  685,  758 
Mendel's  law,  624 

mental  diseases,  424,  427 
Mendelson,  536 

Meningitis,  mental  deficiency,  438 
Meningococcus,  250,  253 

carriers,  254 
detection,  1499 

habitat  in  carriers,  255 

isolation,  1499 

parameningococcus,  253 

recognition,  1501 


Meningococcus,   resistance,  253 

strains,  253 
Mental  age,  447 
IVFontal  conflicts,  439 
Mental  defectives.     Sec  Defectives 
Mental  deficiency,  424 

alcohol,  430 

eugenics,  4"!!8 

head  injuries,  439 

hereditary  transmission,  658 

heredity,  425,  426,  437 

marriage,  428 

meningitis,  438 

prevention,  428 

school   children,   1348 

syphilis,  436,  437 

Wassermann  reaction,  436 
Mental  diseases,  adaptation,  440 

adjustments,  440 
in  civil  life,  441 

alcohol,  429 

behavior,  441 

causes,  439 

conflicts,  439 
in  civil  life,  441 

definitions,  423 

economic   factors,   449 

endogenous  poisons,  434 

environment,  425 

exogenous  poisons,  433 

experience  in  World  War,  442 

hospitals,  451 

immigration,  450 

Mendel's  law,  424,  427 

neuropathic  constitution,  424 

pellagra,  434 

prevention,  438 
agencies,  451 

recruits,  1445 

sex  instinct,  441 

syphilis,  434 
prevention,  436 

See  also  Defectives;   Insanity;    Men- 
tal  hygiene;    Neuroses;    Psycho- 
neuroses;        Psychoses;        Shell 
shock 
Mental  hygiene,  421 

authorities,  educational,  452 
public  health,  452 

departments,  449 

educational  measures,  452 

problems,  422 

scope  of  subject,  423 

societies,  local,  452 

See   also    Mental    age;    Mental    defi- 
ciency;  Mental  diseases 
Merck,  389* 
Mercurial  poisoning,  1307 

prevention,  1308 


1540 


INDEX 


Mercurial  poisoning-,  symptoms,  1307 
Mercury,  1037 

bichlorid,  1406 
Merk,  1386 
Merkel,  959 
Merriman,  315 

Metallic  salts,  disinfection,  1406 
Metcalf,  1217 

Metchnikoff,  57,  60,  65,  66,  81,  107,  132, 
539,  551,  558,  570,  572-574,  589, 
592,  606,  750,  769 
Methane,  946 
Methods,  statistical,  631 
Methyl  alcohol,  94,  268 
Methyl  red  test,  1093 
Methylamin,  723 
Metz,  290 
Meyer,  862 

Meyer,  A.,  410,  428,  451,  455 
Meyer,  K.  F.,  712 
Meyer's  line,  1457 
Mezincescu,  415 
Miasmatic  disease,  464 
Mice,  328 

food  infections,  704 
Michaelis,  564 
Micrococcus  catarrhalis,  257 
Micrococcus  crassus,  257 
Micrococcus  flavus,  257 
Micrococcus  melitensis,  407,  410 
Micrococcus  pharyngis  siccus,  257 
Microcytase,  573 
Microfilaria  diurna,  306 
Microfilaria  perstans,  306 
Microorganisms,  non-pathogenic,  525 

pathogenic,  525 
Microphages,  572 
Migraine,  654 

Migration,  death  rates  and,  1270 
Miles,  80,  674 
Miles  process,  1204 
Military  hygiene,  1439 

barracks,  1469 

Caldwell  crematory,  1478 

camps,  1465.     See  also  Camps 

camp    sites,    1465.     See    also    Camp 
sites 

canteen,  1458 

clothing,  1454.    See  also  Clothing 

cold  climates,  1481 

comparative   loss   from   sickness   and 
wounds,   1441 

diseases  of  the  soldier,  1458 

disposal  of  excreta,  1473 

English  crematory,  1478 

equipment,  1451 

first-aid  packet,  1453 

garbage  disposal,  1475 

general  considerations,  1439 


Military  hygiene,  grease  trap,  1477 

headgear,  1455 

incinerators,  1473 

latrines,  1473 

marching,  1459.     See  also  iMarching 

medical  officer,  duties,  1450 

physical  examination,  1442 

pit  crematory,  1474 

recruits    and    recruiting,     1442.    See 
also  Recruiting 

rock  pile  crematory,  1477 

sanitary  police,  1463 

sanitation,  in  camps,  1459 
on  the  march,  1459,  1462 

straddle-pit  cover,  1474 

tents,    1467 

training,  1449 

transportation,   1464 

trenches,    1478 

in  the  tropics,  1479 

urine  soakage  pit,  1476 

war  gases,  1459 

water,  1470.     See  also  Water 

water  bag,  1480 
Military  population  statistics,  1257 
Milk,  753,  1489 

acidity,  806 

adjusted,  768 

adulteration,  772 

adulteration  tests,  810 

agglutination  of  bacteria,  776 

alcoholic  fermentation,  771 

alkaline  putrefaction,  770 

amylase,  761 

Babeock  method,  799,  800 

bacteria,  774,  794,  796 

bacteriological  examination,  794 

bellei  test,  810 

benzidin  test,  810 

benzoic  acid  test,  812 

bitter,  771 

boric  acid  test,  812 

B.  welchii  in,  797 

cane  sugar  test,  812 

carbonate  test,  811 

casein,  756 

catalase,  761,  808 

certified,  767 

chemical  analysis,   798 

chemical  preservatives,  772 

clarification,  773 

colored,  772 

coloring  matter,  810 

composition,  754 

condensed,  784 

cow 's  vs.  woman 's,  763 

decomposition,   768 
diastase,  761 
dirt  test,   772 


INDEX 


1541 


Milk,  diseases  spread  by,  777 
Doane-Buckley  method,  798 
dried,  735,  784 
drugs,  76o 
effect  of  heat,  792 
enzymes,  760,  808 

thermal  death  point,  761 
evaporated,  784 
fat,  756,  800 
Fehling  method,  802 
ferments,  760 
field  tests,  808 
formaldehyd  test,  810 
j^alaetase,  760 
germicidal  property,  776 
of  goats  and  Malta  fever,  409 
grades,  765 
heated,  808 
inspection,  788 
Kjeldahl  method,  804 
lactalbumin,  756 
lactic  acid  fermentation,  769 
lactoglobulin,  756 
lactokinase,  760 
lactose,  759 
leukocytes,  762 
life,  760 
lipase,  760 

method  detecting  tubercle  bacilli,  779 
microscopic  examination,  797 
pasteurization,    788.    See    also    Pas- 
teurization 
peroxidase,  761 
peroxidase  reaction,  810 
polariscope  method,  803 
powder,  735,  784 
Preseott-Breed  method,  798 
production,  754 
products,  785 
proteins,  756 

determination,  804 
putrid,  770 

Quevenne  lactodensimeter,  807 
reaction,  806 
reconstructed,  768 
reductase,  761 
reductase  test,  809 
refractometer  reading,  805 
remade,  768 

requirements  for  safe  supply,  793 
ropy,   771 

Eothenfusser 's  test,  810 
salicylic  acid  test,  812 
scarlet  fever  and,  222 
score  card,  788 
skimming,  772 
slimy,  771 
sour, .  769 

and  intestinal  flora,  769 


Milk,       Soxhlet       extraction       method, 
801 

specific  gravity,  807 

standardized,  768 

standards,  764 

starch  test,  812 

Stewart-Slack  method,  797 

Storch  test,  810 

straining,  774 

streptococci,  781 

strippings,  758 

sugar,  759 

determination,  802 

synthetic,  768 

tests  for  acidity,  806 

thickening  agents,  772 

total  solids,  798,  799 

viscosity,  758 

vitamins,   759 

water,  805 

watering,  772 

Werner-Schmidt  method,  800 

Westphal  balance,  807 

woman's  vs.  cow's,  763 
Milk-borne  diseases,  cholera,  144 

diphtheria,  195,  780 

food  infections,  783 

foot-and-mouth  disease,  782 

Malta  fever,  782 

scarlet  fever,  222,  780 

septic   sore  throat,   780 

tuberculosis,   777 

typhoid  fever,  108,  121,  780 
Milk-borne  epidemics,  783 
Milk  of  lime,  1416 
Milk  sickness,  782 
Milkpox,  25 
Miller,  248 
IMiller,  F.  G.,  1314 
Mills,  338 
Mills,  H.  F.,  1148 
Mills,  H.  O.,  1181 
Mills-Reincke  phenomenon,  1148 
Mini's  culicide,  272 
Minchim,  319 
Mineral  acids,  872 
Mineral  dyes,  727 
Miner 's  anemia,  153 

hookworm  disease,  1323     , 

tuberculosis,  1320 
Mining,  1071 

beat  hand,  1320 

coal,   1071 

moisture,  1319 
Minors,  industrial  hygiene,  1286 
Minot,  630 

Miquel,  936,  950,  1026 
Misbranding,  foods,  728 
Miscarriage,  477 


1543 


INDEX 


Missed  cases,  463 
Mita,  S.,  209 
Mitchell,  117,  167 
Mitchell,  Charles,  738 
Mitchell,  W.,  959 
Mites,  sulphur  and,  269 
:Matzmain,  288,  327 
Mocezuelo,  99 
Moezutkowski,  361 
Modes  of  transference,  460 

See  also  under  each  disease 
Mohler,   J.  E.,   24,  400,   406,   779,  818, 

845,  863 
Moizard,  216,  941 
Mongolianisni,   608 
Monneret,  335 
Montagu,  Mary  Worthy,  27 
Montgomery,  330 
Moon,  41 

Moore,  366,  368,  369,  417,  435,  1419 
Moore,  G.  T.,  1143 
Moore,  W.  L.,  989 
Mora,  761 

Morbidity,  tuberculosis,  164 
:\torbidity  rates,  1226,  1254 

case  fatality  rates,  1254 

crude,  1254 

factors  influencing,  1255 

fatality  rate,  1254 

hospital  statistics,  1255 

sickness  insurance  records,  1255 

specific,  1254 
Morbidity  statistics,  1242 

error,  sources,  1262 

military,  1257 

admission  rate,  1258 
non-effective  rate,  1258 

model  state  law,  1245 

nature  of  information  secured,  1251 

notifiable  diseases,  1244 

notification,  results,  1246 

source  of  data,  1247 

standard  notification  blank,  1251 

in  the  U.  S.,  1243 

uses,  1253 
Morbille,  212 
Morbus  Gallieus,  57 
Morgagni,  248 
Morgenroth,  234,  550,  787 
Morner,  861 
Morons,  609 
Morphin,    433,    486 
Morphinism,  433 
Morrow,  68,  75 
Morse,  125 
Morse,  W.   F.,   1225 
Mortality,  infant,  477.     See  also  Infant 
mortality 

rabies,  39 


Mortality,  tuberculosis,  164 

See  also  under  each  disease 
Mortality  statistics,  1259 

in  health  administration,  1259 

infant,   1275.     See  also  Infant  mor- 
tality 

source  of  data,  1261 

sources  of  error,  1262 

standard  death  certificate,  1262 

U.  S.  area  for  registration,  1260 

in  the  U.  S.,  1260 

uses,  1266 

See     also     Death     rates;     Mortality 
rates;  Eegistration 
Moser,  224 
Mosquitoes,  268,   279 

Anopheles.    See  Anopheles 
■     Anophelinse,  287,  288 

bats  and,  291 

breeding  places,  artificial,  283 
natural,   282 

c\ilicides,  268 

cyanid,  515 

destruction,  281 

fish  and,  282 

flights,  279 

hibernation,   288 

larvicides,  283 

leprosy  and,  416 

life  history  and  habits,  280 

malarial,  297 

Malta  fever  and,  408 

Panama  larvicide,  283 

petroleum,  275,  282 

screening,  285 

sulphur  dioxid,  517 

table,  264 

transmission  by,  of  malaria,  287 

volatile  substances,  286 

in  winter,  281 

yellow  fever,  297.   See  also  Stegomyia 
calopus 
Moss,  196 
Mosso,  889 
Moth,   clothes,   268 
Mountain  laurel,  830 
Mountain   sickness,   889 
Mouse  favus,  1323 
Mudd,  S.,  249 
Muecke,  895 
Mueller,  366 
Miiller,  49 
Miiller,  F.,  944 
Munch,  361 
Mumps,  228 
Munchheimer,  61 
Munsen,    1152 
Munson,  1465,  1482 
Munson  last,  1457 


INDEX 


1543 


Murchinson,   107,   1006 

Murex  uradatus,  846 

Mu8,  329 

Mus  alexandrinus,  329 

Mus  museulus,  329 

Mus  norvegicus,  329 

Mus  rattus,  329 

Musca  brava,  320 

Musca  domestica,  125,  268,  307,  416 

breeding  places,  309 

life  history,  308 
Muscarin,  724,  725,  858,  860 
Muscarin  poisoning,  860 
Muscicides,  316 
Musgrave,  1180 
Mushroom  poisoning,  858 

symptoms,  859 
Mushrooms,  Agaricus  eampestris,  858 

Agaricus  muscarius,  860 

Amanita  muscaria,  858 

Amanita  phalloides,  858,  859 

amanitotoxin,   858 

helvellic   acid,    861 

hemolysin,  860 

muscarin,   858,    860 

phallin,  859,  860 
Mussel  poisoning,  843 

mytilotoxin,   725,   844 

prevention,  845 
Mussels,  and  typhoid  fever,  124 
Mustard,  745 
Mutation,  heredity,  622 
Myopia,  653,  922 ' 
Mytilotoxin,  725,  844 
Mytilus  edulis,  843 
Myzomyia,  287 
Myzorhynchus,   287 

Nacht,  320 
Nacke,  P.,  431 
Naegeli,   163 
Nageli,  950 
Nagana,  264,  320 
Nagel,  907 
Xagier,  1145 
Xakagawa,  840 
Xankivell,  198 
Xaphtha,   276 

Xaphthalene,  268,  276,  325,  1413 
Xaphthols,  1413 
Xapoleon,  427,  1445,  1449 
Xash,  J.  T.   C,   124 
Xastin,  419 

Xational    Comm.ittee    for    Mental    Hy- 
giene, 453,  454 
Xatural  ice,  1186 
Xaunyn,  654 
X.  C.  I.  powder,  lice,  368 
Xeapolitan  disease,  57 


Near-sightedness,  922 

Xecator  americanus,  154 

Neech,  221 

Negri  bodies,  51 

Neil,  335 

Neisser,  57,  63,  75,  583,  584,  588 

Xeisser-Wechsberg  phenomenon,  583 

Xeisser's  method,  196 

Xelis,  53 

Xelms,  Sarah,  2 

Xelson,  Y,,  385 

Xematoda,  soil,  1013 

Nernst,  564 

Nervous  breakdown,  442 

school  ehililren,  1348 
Nervous  prostration,  442 
Xessler's  reagent,  1066 
Xetter,  233,  388,  842 
X^euman,  174,  296 
Neurasthenia,  442 

school  children,  1349 
Neurin,  725 

Neuropathic  heredity,  427 
Neuroses,  war,  444 

hypnotism  and,  445 

management,  446 

prevalence,  445 

theory,  446 

treatment,  445 
Neurotoxin,  553 
Xeustaedter,  392 
Xevin,  707 
Xevin,   M.,   240 

Xew  Haven  typhoid  epidemic,  1174 
Xewman,  217,  780 
Xewman,  G..  521,  813 
X^ewsholme,  A.,  191,  192,  209,  480,  638, 

842,  843 
Newton,  478 
Nice,  1436 
Nichols,  116 
Nichols,  A.  H.,  1188 
Nicolaier.  95 
Nicolle,   103,   214,   215,   229,   240,   265, 

325,  373,  381 
Nicotin,  268 
Xightingale,  R,  1439 
Xijhoflf,    G.   C,   1296 
Xitrate  bacteria,  1000 
Xitre  cake,  283 
Xitrites,  in  water,  1071,  1072 
Xitrobacter,  1000 
Xitrobenzol,  268 
Xitrogen,  869 
Xitrogen  cycle,   998 
Xitromonas,  1002 
Nits,  1347 
Nitsch,  45 
N.  N.  N.  medium,  381 


1544 


INDEX 


Noble,  116,  117,  225,  248 
Nocard,  40,  700,  702 
Nocht,  342 
Nogier,  1376 

Noguchi,  H.,  7,  31,  40,  57,  62,  90,  211, 
264,  296,  297,  303,  335,  336,  435 
Noise,  effects  of,  in  industry,  1321 
Nona,   394 
Nordlinger,  1044 
North,  C.  E.,  813 
Nose,  school  children,  1346 
Nothschlachtung,  823 
Notifiable  diseases,  1244 

standard  notification  blank,  1251 
Notification,  blank,  1251 

occupational  diseases,  1255 

results,  1246 

tuberculosis,   185 

venereal  diseases,  78 
Nott,  287     • 
Notter,  1461 
Novy,  317,  319,  381,  522,  722,  723,  746, 

856 
Nuisances,  483 

sewage  treatment  plants,  1211 

trade  wastes,  1212 
Nursing,  piiblic  health,  483 
Nutmeg,  745 

Nuttall,  209,  328,  416,  575,  587 
Nutting,  M.,  483 
Nyman,  1363,  1407 
Nyssorhynchus,  287 

Obermeier,  264,  265,  361 

O'Brien,  702 

Occupational  diseases,  1279,  1292 

anilin  poisoning,  1310 

anthrax,  1322 

benzol  poisoning,  1310 

brass-founders'  ague,  1311 

cancer,  1321 

classification,  1292 

injurious  substances,  1293 

lead  poisoning,  1293 

manganese  poisoning,  1311 

match-making,  1303 

mouse  favus,  1323 

notification,  1255 

tuberculosis,   1323 

wood  alcohol  poisoning,  1312 

wool-sorter's  disease,   1322 

See  also  Arsenical  poisoning;  Carbon 
monoxid;  Child  labor;  Dust; 
Industrial  hygiene;  Lead  poison- 
ing; Mercurial  poisoning;  Min- 
ing; Phosphorus  poisoning 
Occupations,  sedentary,  1291 
Ocular  hygiene,  916 

accidents,  94 


Ocular  hygiene,  alcohol,  94 

astigmatism,  922 

cataract,  653 

color  blindness,   922 

errors  of  refraction,  922 

eye  strain,  923 

eyes,  care,  923 

far-sightedness,  922 

hypermetropia,  922 

lighting,  920 

myopia,  653,  922 

near-sightedness,  922 

ophthalmia  neonatorum,  87 

presbyopia,  922 

retinitis  pigmentosa,  653 

school  children,  1342 

tobacco,  94 

toxic   amblyopia,  94 

trachoma,  92 

vision  of  recruits,  1447 

vision  tests,  924 
Odors,  914 

body,  968 

sources,  914 

water,  1050 

prevention,  1054 
Ogden,  H.  N.,  1217 
Ogdensburg  typhoid  epidemic,  1188 
Ohlmiiller,  870 
Ohmes,  A.  K.,  971 
Oil  heaters,  986 
Oil  pinus  palustris,  268 
Oil  turpentine,  268 
Oils,  in  plants,  853 
Oleomargarine,  787 

Criitsky,  P.  K.,  148,  240,  241,  257,  553 
Oliver,  158,  932,  942,  1288,  1292,  1294, 

1309,  1319,  1320,  1324 
Olson,  468 

Open  air  schools,  1337 
Open  fires,  986 
Ophthalmia  neonatorum,  87 
Crede's  method,  89 
gonococcus,  87 
legislation,  91 
prevalence,  88 
prevention,  89 
silver  nitrate,  89 
Ophthalmic  test,  glanders,  398 
Ophthalmoplegia,  709 
Ophuls,  710 
Opie,  E.  L.,  376 
Opium,  486 
Opsonic  index,  574 
Opsonins,  574 
Oral  prophylaxis,  1343 
caries,   1344 
pyorrhea,  1344 
school  children,  1343 


INDEX 


1545 


Oral    iiropliylaxis,    streptococcal    infec- 
tions, 1346 

Vincent 's  angina,  211 
Orchitis,  228 
Orenstein,  281 
Oriental  sore,  380,  381 
Orlandi,   995 

Ornithoilorus  moubata,  361 
Orr,  366 
Orr,  F.  I.,  424 
Orr,  P.  F.,  713,  715 
Orthostatic  albuminuria,  G54 
Orton,  S.  T.,  455 
Osborne,   554,  597,  598,   G67,   670,   672, 

676,  758,  876,  975 
Osgood,  390 

Osier,  William,  59,  64,  231,  491,  843 
Ostertag,  694,  778,  818,  835,  846 
Otto,  296 

Outbreaks.    See  Epidemics 
Overexertion^  immunity,  544 
Overton,  F.,  521 
Overturn,  1031 
Owen,  E.,  832 
Oxalic  acid,  853 
Oxalic  acid  poisoning,  853 
Oxygen,   867 

disinfection,  1404 

effect,  diminished,  957 

sewage  disposal,  1197 

in  water,  1077 
Oxyuris  vermicularis,  1181 
Oysters,  840 

fattening,  841 

floating,  841 

plumping,  841 

score  card,  841 

typhoid  fever,  124,  842 
Ozanann,  394 
Ozenani,  335 
Ozone,  869 

deodorizing  properties,  871 

disinfection,  1404 

effect,  870 

ozonizers,  871 

tests,  871 

water  purification,  1129 
Ozonizers,  871,  1130 

Package  K,  82 

Packard,  A.  S.,  307 

Page,  198 

Pahvent  Valley  plague,  321 

Pail  system,  sewage  disposal,  1192 

Painters,  lead  poisoning,  1297 

Palmer,  916,  934 

Palmer,  L.  S.,  854 

Palmer  water  spray  apparatus,  934 

Paltauf,  41 


Pammel,  857 

Panama  larvicide,  283 

Pandemic,  definition,  465 

Panpoukis,  49 

Panu-m,  214 

Paper,  clothing,  of  the  soldier,  1455 

fly,  sticky,  272 
Pappataci,  322 
Pappenheinier,  A.  M.,  376 
Papule,  vaccination,  12 
Paracresol,  1413 
Paraform,  268,  1391 
Paragonimus  westernianii,  265,  840 
Paralysis,  infantile,  386,     See  also  In- 
fantile paralysis 

Pasteur  treatment,  48 

postdiphtheritic,  207 

tick  bites,   354 
Parameningococcus,  253 
Parasites,  524,  546 

animal,  525 
Paratyphoid  fever,  136 

and  food  poisoning,  138 

historical  note,  137 

immunity,   138 

prevalence,  136 

prevention,  138 

typhoid,  differential  diagnosis,  137 
Paratj-phoid  group,  701 
Parinaud's  conjunctivitis,  93 
Paris  green,  276,  1305 
Par,  W.  H.,  97,  101,  167,  199,  200,  202, 

204,  209,  237,  247,  1188 
Parker,  296 
Parker,  W.  N.,  658 
Parkes,  975,   986,   1018 
Parkes,  L.  C,  980 
Parry,  682 

Parsons,  H.  De  B.,  1225 
Partridge  poisoning,  829 
Passy,  914 
Pasteur,  44-47,  54,  146,  248,  401,  402, 

528,  718,  937,  939,  1008 
Pasteur-Chamberland  filter,   1127 
Pasteur  treatment,  44 

care  during,  48 

complications,  48 

contraindications,  50 

fixed  virus,  44 

immunity,  49 

paralysis,  48 

results,  49 

schemes  of  treatment,  46 

street  virus,  44 

when  to  give,  50 
Pasteurization,  788 

advantages,  789 

Freeman  pasteurizer,  791 

methods,  791 


1546 


INDEX 


Pasteurization,  Straus  pasteurizer,  792 

Pasti,  390 

Paterson,  R.  C,  1422 

Pathogenic  microorganism,  525 

Paton,  S.,  457 

Patterson,  R.  N.,  1475 

Patton,  356,  382 

Paul,  891,  961,  1296,  1362,  1363,  1407, 

1423 
Paulet,  411 
Peacock,  A.  D.,  376 
Pearce,  Louise,  70 
Pearson,  1412 
Pearson,  K.,  629,  631,  659 
Peat,  994 

Pectase  bodies,  737 
Pediculi.    See  Lice 
Pediculi  capitis,  school  children,  1347 
Pediculus  capitis,  361,  363,  365,  373 
Pediculus  corporis,  363,  376 
Pediculus  humanus,  363,  376 
Pediculus   vestimenti,    361,    363,    373 
Pellagra,  686 

causative  agent,  688 
corn,  687,  689 
mental  diseases,  434 
prevention,  690 

Thompson-McFadden         Commission, 
688 
Pelletier,  151 
Pembrey,  907 
Pennington,  842,  847 
Pennyroyal  oil,  268 
Penrose,  G.  A.,  642 
Pepper,  745 
Peppermint  oil,  268 
Perborates,  1423 
Percolating  filters,  1207 
Periplaneta  americana,  383 
Periplaneta  australasise,  383 
Perl,  110 
Permanganate-formalin,       disinfection, 

1394 
Permutit,  1063 
Peroxidase,  761 
Perroncito,  695 
Persian  insect  powder,  271 
Personal  hygiene,  1325,  1346 
latent  malaria,  290 
school  children,  1343 
of  the  soldier,  1449,  1454,  1459 
See  also  Personal  prophylaxis 
Personal  prophylaxis,  1346 
in  cholera,  147 
diphtheria,  206 
hookworm  disease,  160 
infection,  463 
influenza,  245 
insect-borne  diseases,  263 


Personal    prophylaxis,    lead    poisoning, 
1301 
leprosy,  418 
malaria,  291 
plague,  353 

tuberculosis,  176,  177,  184 
typhoid,   135 
typhus  fever,  375 
venereal  diseases,  79 
Persons,  304 
Perspiration,  905 
Pertussis,  224 
Peste,  345 
Pestilence,  675 
Petechial  fever,  250 
Peters,  959 
Petri,  786 
Petrofle,  57,  179 
Petroleum,  275,  1044 
bedbugs,  275 
fleas,  275 
lice,  275 

mosquitoes,  275,  282 
pulicide,  325 
roaches,  275 
Petruschky,  116,  198,  700 
Pettenkoffer,    126,   140,   141,   876,   940, 

957,  996 
Petterson,  390,  391 
Petterson-Palmquist  method,  880 
Pfeiffer,   107,   128,   130,   240,  589,  592, 

595 
Pfeiffer,  R.,  575,  576 
Pfeiffer 's  phenomenon,  142,  576 
Pfuhl,  861 
Phagocytosis,  570 
Phallin,  859,  860 
Phelps,  841,  1216,  1361,  1367 
Phelps,  E.  B.,  909 
Phenol,  1369,  1409 

disinfection,  1410 
Phenol  coefficient,  1367.     See  also  Car- 
bolic coefficient 
Phenol-camphor,  272 
Phenoloid  group,  1409 
Philip,  164 
Phipps,  James,  2 
Phlebotomus  fever,  322 
Phlebotomus  pappatasii,  322 
Phosphorescence,  919 
Phosphorus,  341,  1303 
amorphous,  1303 
red,  1303 
white,  1303 
yellow,  1303 
Phosphorus  poisoning,  1303 
fragilitas  ossium,  1305 
match-making,  1303 
prevention,   1305 


INDEX 


1547 


Phossy  jaw,  1304 
Photoflicmii'al  reactions,  919 
Pliotodynaniie  action,  919 
Pliotosonsitization,  9l'() 
Plitliirius  pubis,  363,  .365 
Plitliisiopliobia,  185 
Phtliisis,  172 

conjugal,  177 
Piaiiese,  265 
Pickard,  117 
Picklci  meats,  736 
Pickling,   735 
Pictet,  730 
Pilcz,   59,  435 
Pintseh  gas,  343 
Piroplasma,  356 
Piroplasniosis,  287 
Pit  crematory,  1474 
Pitometers,   io20 

Pittsburgh  typhoid  epidemic,  1178 
Pitz,  684,  739 
"Place   diseases,"  261 
Plague,  345 

bubonic,  346 

carbon  bisulphid,  275 

endemic  foci,  350 

epidemiology,  345 

fleas,  325 

Haft'kine's  prophylactic,   349 

immunity,   348 

management  of  an  epidemic,  350 

personal  prophylaxis,   353 

pneumonic,  346 

prevention,   352 

quarantine,  352,  505 

rats,  333 

chronic,  334 
diagnosis,   333 
resistance,  334 

relation  to  rats  and  fleas,  325 

septicemic,  346 

squirrels,  275,  344 

Yersin's  serum,  350 
Plankton,   1084 
Plant  foods,   849 

ergotism,   856 

favism,   857 

lathyrism,  857 

leaves,  850 

nutritive  value,  850 

poisoning,  856 

roots,   851 

seeds,  850 

tubers,  851 

vitamins,    850 
Plants,  acids,  853 

anaphylaxis,   854 

antitoxins,  560 

carotin,  853 


Plants,  injurious,  851 

mineral  substances,  852 

oils,  853 

oxalic  acid,  853 

parasites,  854 

poisonous,  851 

toxins,  854 
Plasmodium  falcip;num,  286 
Plasmodium  malaria^,  286 
Plasmodium  vivax,  286 
Plate  ice,  1187 
Playgrounds,    1328 
Plehn,  27,  293 

Plenum    system  of   ventilation,   984 
Plett,  1 
Plimmer,  320 
Plotz,   H.,   364,   367,   370 
Plowright,    859 
Plumbing,   sewage  and,   1196 
Plumbism,  1294 
Plumert,  417 

Plymouth  typhoid  epidemic,  1173 
Pneumococci,         agglutination         test, 
1499 

classification,   1498 
Hiss  method,   1498 

isolation,  1499 

Avery's  medium,  1499 

precipitin  test,  1499 

resistance,    232 

types,  231 
Pneumococcus  mucosus,  232 
Pneumokoniosis,  1314 
Pneumonia,  230 

alcohol,  235 

carriers,   233 

climates,  230 

crowding,  238 

epidemiology,  230 

fatigue,  231,  235 

hand-to-mouth   infection,   238 

immunity,   234 

infant  mortality,  481 

isolation,  237 

modes  of  transmission,   232 

mortality,  230 

prevention,   236 

preventive  measures,  237 

references,   239 

resistance  of  the  virus,  232 

seasonal  prevalence,  231 

vaccines,  236 

wool-sorter's,  1315 
Pneumonokoniosis,  931 
Poellmann,  616 
Poison  ivy,  854 
Poison  oak,  854 
Pol,  H.,  679 
Polariscope  method,  803 


1548 


INDEX 


Poliomyelitis,  acute  anterior,  386.     See 

also  Infantile  paralysis 
Pollack,  69,  176,  430,  432 
Pollender,  401 
Pollock,  H.,  422 

Polluted  water,  international  boundary, 
1045 

interstate  pollution  of  streams,  1044 

nature,  1043 

sources,    1043 

tests  to  determine  sources,  1043 
Pollution,     stream,     1198.       See     also 

Stream  pollution 
Polydactylism,   653 
Polyneuritis,   678 
Polypeptids,   719 
Polyvalent  vaccines,  132 
Ponder,  255 
Ponds,    1028 

purification,  1111 
Poor,  44 
Popper,   386 
Population,  1228 

arithmetical  method,  1231 

estimates,  1230 

fluctuation,  1230 

geometrical  method,  1232 

military,  1257 

nature  of  census  information,  1229 

source  of  data,  1228 

sources  of  error  in  census,  1229 

See  also  Birth  rates;  Census;  Infant 
mortality;     Marriage    statistics; 
Morbidity  rates;  Mortality  rates; 
Eegistration 
Pork  tapeworm,  834 
Porter,  1191 
Porto  Eican  Anemia  Commission,   157, 

160,  162 
Postdiphtheritic  paralysis,  207 
Posture,  school  children,  1332,  1334 
Potassium    permanganate,    disinfection, 
1415 

food  preservation,  747 

water  purification,  1140 
Potato  poisoning,  861 
Pothier,  296 
Potpeschnigg,   388 
Potter's  rot,  932 
Pottery,  lead  poisoning,  1299 
Potts,  426 

Poultry,  cold  storage,  732 
Poverty,  alcohol  and,  492 
Powder,     bleaching,     1132,       See     also 

Bleaching  powder 
Powell,  146 
Pozzi-Escot,  838 
Practique,  509 
Prasek,  219 


Precipitin  test,  pneumococci,  1499 
Precipitins,  585 
Premature  births,  477,  481 
Presbyopia,  922 
Prescott-Breed  method,  798 
Prescott,  S.  C,  1189 
Preservation,  foods.     See  Food  preser- 
vation 
Preservatives,  meat,  818.    See  also  Food 

preservatives 
Preserves,  736 
Pressure,  atmospheric,  887 
altitude,  888 
caisson  disease,  890 
diminished,  887 
increased,  890 
efPects,  890 

disinfection,   1377 
Prevalence.     See  under   each   disease 
Preventable  blindness,  87 
Prevention.     See  under  each  disease 
Pride,  746 
Price,  G.  M.,  1324 
Priestley,    866,    874,    875,   971 
Pringle,   1365 
Pritchett,  1009 
Pritchett,  I.  W.,  103 
Privies,  1191,  1213 

typhoid  fever,   1191 
Prizer,  215 

Problems  in  vital  statistics,  1494 
Proescher,  45,  47 
Profeta,  414 
Prof  eta's  law,  646 
Program,  public  health,  468 
Prohibition,  alcoholism  and,  433 
Propagation,   vaccine   virus,   8 
Prophylaxis,  oral,  1343.     See  also  Oral 
prophylaxis 

rabies,   42 

syphilis,   65 

venereal,  73,  81 
Propustule,  smallpox,  30 
Prosodemic,   definition,  465 
Prostitute,  80,   86 
Prostitution,  80,  86,  437 
Protargol,  82 
Proteins,   67 

composition,  719 

milk,   756 

determination,  804 

putrefactive  changes,  719 
Protein  metabolism,  601 
Proteosoma,  287 
Protozoa,  in  soil,  1012 
Protozoon  carriers,  462 
Prowazek,  92,  320,  372,  374 
Psychoneuroses,  424 

war,  446 


INDEX 


1549 


Psychoneuroses,  World  War,  442 
Psychopathic  inferiority,  609 
Psychoses,  422 

alcohol,   429,   437,.  439 
alcoholic,  489 

prevention,  432 
definition,   423 
head  injuries,  438 
heredity,   424 
infectious  diseases,   437 
prevalence,   429 
syphilis,  434 
traumatic,  439 
war,  446 
Psychrometers,  901 
Ptomain  poisoning,  721 
Ptomains,   721 

Public    health,    activities,    score    card, 
467,  468 
centers,  471,  473 
cooperative  organization,  471 
departments,  cost,  471 

organization,  470 
education,  475 
measures,  459 
median  endemic  index,  472 
methods,  459 
nursing,    482 
officers,   score   card,   468 
program,  470 
\\ork,  relative  values,  466 
Puerperal  tetanus,  99 
Pulex,   324 

Pulex  irritans,  324,  325 
Pulex  serraticeps,  324 
Pulicid8e,-324 
Pulicides,   325 

hydrocyanic  acid,  325 
petroleum,  325 
Pulp,  vaccine,  5 
Pulverizer,   1405 
Pumpelly,  950 
Punnett,  653 
Punnett,  E.  C,  624,  659 
Purification,  of  water,  1108 
alum,  1141 

aluminum  sulphate,  1141 
Anderson  process,  1143 
antibiosis,  1110 
biological  factors,  1110 
boiling,  1471 
chemical  methods,   1129 
chloramin-T,   1134 
chlorin,  1139 
chlorinated  lime,   1132 
condensation,    1109 
copper  sulphate,  1143 
dilution,  1112 
evaporation,   1109 


Purification,  of  water,  filtration,  1113 

halazone,   1134 

iron  sulphate,   1142 

lime,  1142 

metallic   iron,  1143 

nature's  methods,   1108 

oxidation,  1110 

ozone,  1129 

potassium    permanganate,    1140 

recent   tendencies,    1125 

screening,  1128 

sedimentation,   1112,   1129 

self -purification,  1109 

storage,  1111,  1128 

sunlight,  1112 

time,   1110 

ultraviolet  rays,    1144 
Purjesz,  110 
Putrefaction,  food,  718 

proteins,   719 
Putrescin,   723 
Pylarini,   27 
Pyocyanase,   198 
Pyorrhea,  1344 
Pyrethrum,  271 
Pyretophorus,  28T 
Pyridin,  268 

Pyrosoma  bigeminum,  356 
Pythogenic  theory,  1006 
Pyxol,  1412 

Quales,  110 
Quarantine,  498 

bill  of  health,  509 

in  cholera,  146,  503 

free  practique,  520 

government,    powers,    520 

interstate,    519 

interstate  sanitary  regulation,  520 

interstate  travel,   520 

leprosy,   508 

nation  vs.  state,  518 

plague,   352 

procedures,  509 

smallpox,  504 

vessels,   502 

yellow   fever,   507 

See  also  Maritime  quarantine 
Quartan  fever,  286 
Quevenne  lactodensinieter,  807 
Quicklime,    1416 
Quincke,  1323 

Quinin  prophylaxis,  malaria,  292 
Quinin   treatment,    malaria,   295 
Quinolin,  268 
Quint,  1321 

Eaab,  918,  920 
Raber,  B.  P.,  989 


1550 


INDEX 


Eabies,   38 

diagnosis  in  dogs,  51 

dogs,  42 

exit  and  entrance  of  virus,  40 

mortality,  39 

Xegri  bodies,   51 

Pasteur  treatment,   45 

period  of  incubation,  39,  40 

prevalence,  39 

prophylaxis,    42 

references,   54 

relative   danger   of   bites,   41 

treatment  of  wounds,  42,  43 

viability  of  virus,  41 

virus,  fixed,   44 
preparation,  45 
street,  44 

See  also  Pasteur  treatment 
Eabinowitsch,  320,  414 
Eace,  J.,  813 
Rachitis,  685 
Radiation,  985 
Radioactivity,  925 
Railroad  cars,  disinfection,  1430 
Rain  water,   1022 

amount,  1023 

bacteria,  1026 

collection,  1025 

composition,   1025 

storage,  1025 
Rambousek,  1324 
Ramsey,  869 
Rankine,  1018 
Ransom,  833-835 
Rappaport,   197 
Rappoport,  D.,  376 
Rats,  326,  328 

acute   infectious   jaundice,    336 

animals,  domestic,  342 

bacterial  viruses,  343 

bites,  332 

breeding,   329 

brown,  329 

cancerous-like  growth,  385 

carbon  monoxid,  342 

diseases  spread,  335 

economic  importance,  338 

Egyptian,   329 

English  black,  329 

ferocity,  332 

fever,  rat-bite,  332 

food,   331 

food  infections,  337,  704 

fumigation,    342 
on   ships,   516 

habits,  332 

hydrocyanic   acid  gas,   515 

keeping  food  from,  340 

leprosy,  337,  414 


Rats,  migration,  330 

natural   enemies,   340 

plague,  333 

poisons,   340 

prevalence,   329 

rat-bite  fever,  332 

rat-proof  buildings,  339 

roof,  329 

shooting,  342 

sulphur  dioxid,  517 

suppression,  338 

traps,  340 

trichinosis,  337,  830 

on  vessels,  331,  505 

viruses,  bacterial,  343 

white,  329 
Rat-bite  fever,   332 
Rat  viruses,  food  and,  704 
Rattine,    95 
Raubitsehek,  688 
Rauer,  959 
Ravenel,  173,  198 
Rawlins  strain,  129 
Rayband,   327 
Raver,  401 
Rayleigh,  869 
Receptors,  549,  550 

orders,   552 
Recirculation,  968 
Reckford,  211 
Reckzek,   388 

Records,  sickness  insurance,  1255 
Recruiting,   1442 

age,  1444 

character,  1445 

chest  measurements,   1446  . 

general  considerations,   1448 

height,  1446 

mental  condition,  1445 

physical  examination,  1442 

teeth,   1448 

vaccination,  1448 

vision,  1447 

weight,   1446 
Red  lead,  1294,  1295,  1297 
Reductase,  761 
Reductase  test,  809 
Reduction,   garbage,   1220 
Reed,  125,  126,  259,  264,  296,  702 
Reed,  Mary,  418 
Refrigerators,  temperature,  731 
Refuse,  1219 

constituents,    1219 

See  also  Garbage 
Refuse  disposal,  1219 
Registration,  1226 

deaths  in  U.  S.,  1260 

U.  S.  area  for  deaths,  1260 
Regression,  629 


INDEX 


1551 


Reioho,   199 

Keic-lienbach,  962 

Reiiu'k'o,  ,F.  J.,   1148 

Keiiisi'li-Wurl  screen,  1201 

Reinspiration,  963 

Relapsing  fevers,  361 

Relative  values,  jiublic  health  work,  466 

Relief  sewers,  1193 

Remlinger,  48 

Renisen,   744 

Resin-lime  mixture,  278 

Resistance,  524 

alcohol  and,  491 

See  also  under  each  disease 
Resistance,  lowered,  immunity  and,  542 
Respiratory  diseases,  163 
Retinitis  pigmentosa,  653 
Retrovaceination,  8 
Rettger,  718 
Revaecination,  18 
Reversion,  628 
Rhubarb  leaves,  853 
Rhumbler,  574 
Rhus  dermatitis,   854 
Rhus  diversiloba,  854 
Rhus  poisoning,  854 
Rhus  toxicodendron,  854 
Ribos,   296 
Rice,  beriberi,  681 

pericarp,  681 
Richards,  682 
Richards,  E.  H.,  989 
Richardson,  128,  957 
Richardson,   Mark,  391,  392 
Richet,  595 
Ricin,  554 
Rickets,  685 
Ricketts,   264,   265,   357-359,   372,   373, 

606 
Rickettsia,   359,   372 
Rickettsia  pediculi,  373,  377 
Rickettsia  proAvazeki,  373 
Rideal,  1134,  1366,  1369,  1419 
Riggs,  83,  84 
Rimpler,  90 

Ringelmann  smoke  chart,  928 
Ringworm,  1348 
Rivers,  651,  1026 

composition,  1027 
Roaches,    268,   383 

cancerous-like  growth  in   rats,  385 

cleanliness,   384 

enemies,  natural,  384 

habits,  383 

hydrocyanic   acid   gas,   384 

petroleum,   275 

sodium  fluorid,  384 

structure,  383 

sulphur  dioxid,   384 


Roaches,  suppression,  384 

Robb,  853 

Roberto,  852 

Roberts,  1398 

Rock  pile  crematory,  1477 

Rockefeller  Sanitary  Commission,  162 

Rocky  Mountain  spotted  fever,  356 

prevention,  359 

Rickettsia  prowazeki,  373 
Rodents,  328 
Rodrigues,  296 
Ronnfeld,  H.,  658 
Roentgen  ray.     See  X-ray 
Rotheln,  219 
Roger,   589 
Rogers,  151,  382,  419 
Rolander,  416 
Rolfe,  843,  845 
RoUeston,  38 
Romer,  177,  711,  918 
Rommeler,  138 
Rondelli,  995 
Rooms,  cooling,  988 

disinfection,  1427 

fumigation,  266,  1390 
Roosevelt,  744 
Roots,  851 
Ropke,  1321 
Rosanoff,  A.  J.,  424 
Rose,  W.,  291 
Rose  colds,  605 
Rosen,   700 

Rosenau,  M.  J.,  24,  100,  117,  174,  178, 
180,  208,  210,  235,  237,  240,  241, 
296,  312,  343,  345,  390,  392,  406, 
412,  561,  600,  782,  786,  813,  960 
Rosenow,  E.  C,  244 
Ross,  259,  286,  287,  290,  295,  296 
Rost,   419 
Rotch,    763 
Rothe,  862 

Rothenf usser 's  test,  810 
Rouget,  320,  1445 
Roundworms,  in  soil,  1013 
Roux,  40,  44,  45,  54,  57,  65,  66,  81 
Rowland,  R.  A.,  962 
Ruata,  1184 
Rubbish,   1219 
Rubella,  219 
Rubeola,   212 
Rubin,   491 

Rubner,  664,  905,  907,  909,  910,  912 
Rubner,   M.,   521 
Rucker,   345 
Rudin,  E.,  424,  425 
Ruediger,  118,  796 
Riihm,  806 
RuUman,   788 
Runge,  1409 


1552 


INDEX 


Kupprecht,  695 

Rural  sanitation,  475 

Rural  sewage  disposal,  1192,  1213 

Rush,  235 

Russ,    322 

Russell,  760,  875,  1394 

Russell,  E.  J.,   1002 

Russell,  F.  F.,  Ill,  129,  130 

Russell,  H.  L.,  1189 

Russell,  W.  L.,  455 

Sabadilla  seeds,  268 

Saccharin,  726 

Sacco,  14 

Sachs,  550,  588 

St.  Paul,  427 

St.  Vitus 's  dance,  1348 

Saleswomen,   1289 

Salicylic  acid,   747,  812 

Salimbeni,  296 

Salkowski,  844 

Salmon,  T.  W.,  455-457,  611,  613,  700, 

701 
Salmonella  group,  701 
Salting,  735 

Salts,  metallic,  disfection,  1406 
Salrarsan,  syphilis,  85 
Sambon,  688 
Sanarelli,   700,   702 
Sanatol,  1412,  1413 
Sanatoria,  tuberculosis,  182 
Sanchez,  97 
Sand,  417 
Sandfly  fever,  322 
Sanitary  habits,  463 
Sanitary  police,   1463 
Sanitary  surveys,  492,   1501 
Sanitation,   498 

cooperative,    1212 

definition,   523 

rural,  475 
Sanitube,  82 
Sanki,  852 
Sapremia,  525 
Saprol,  1413 
Saprophytes,  524 
Saraat,  411 
Sarcone,   28 

Sarcoptes  scabiei,  270,  416 
Savage,    138,    194,   697,   702,   722,   843, 

845 
Savage,  W.  G.,  813,  863,  1189 
Sawtschence,  41 
Sawyer,  115,  134,  695,  871 
Scabies,   1347 
Scar,  in  vaccination,  13 
Scarlet  fever,  219 

desquamation,  221 

detention  period,  221 


Scarlet   fever,   epidemiology,    219 
immunity,   223 
milk-borne,  222,  780 
modes  of  transmission,  220 
mortality,  212 
prophylaxis,   223 

return  cases,  221 

streptococcus  vaccines,  224 
Schamberg,  J.  F.,  38,  61 
Schapiro,  L.,  161 
Schardinger,   761,   809 
Schaudinn,  57,  287 
Scheel,   386 
Scheele's  green,  276 
Scheuer,  61 
Schick,  598 
Schick  reaction,  198,  200,  204,  210,  1497 

combined,   202 

control   tests,   202 

negative,  201 

positive,  201 

psBudo,   201 

See  also  Diphtheria 
Schiotz,  198 

Schistosomum  japonicum,  265 
Schittenhelm,  595,  1153 
Schizotrypanum  cruzi,  320 
Schlenker,   746 
Schmeitzner,  R.,  1217 
Schmidt,  90 
Schmidt-Muller,   809 
Schmiedeberg,  489,  723,  724,  861 
Schmitt,  415 
Schmutzdecke,   1114 
Schneider,  320,  467,  888,  946 
Schonbein,  869,  1129 
Schoenberg,  1313 
Scholley,  196 
School  building,  1328 
School  children,  1325 

books,  1343 

chorea,  1348 

defectives,  1349 

ears,  1343 

epilepsy,   1349 

eyes,   1342 

favus,  1348 

general    considerations,    1325 

impetigo,  1348 

lice,  head,  1347 

mental  defects,  1348 

nervous   diseases,  1348 

neurasthenia,  1349 

nose,  1346 

Pediculi   capitis,   1347 

personal  hygiene,  1343 

posture,  1332,  1334 

ringworm,  1348 

scabies,    1347 


INDEX 


1553 


School  children,  skin  diseases,  1347 

teeth,  1343 

throat,  1346 

vaccination,   1350 
School-houses,  1328 
Schoolrooms,   1329 
Schools.   1325 

blackboard,  1333 

chair,  1331 

cleanliness,   1338 

cloak-rooms,  1337 

closed  by  epidemics,  1342 

closed  on  account  of,  diphtheria,  206 
influenza,  245 
measles,  218 
whooping-cough,  227 

communicable   diseases,   1341 

desks,  1331 

floor  space,  1329 

furniture,   1330 

health  education,  1328 

Heusinger  desk,  1333 

lighting,  1335 
amount,  1335 

medical  inspection,  1338,  1340 

open  air,  1337 

for  tuberculosis,  188 

playgrounds,  1328 

recess,  1334 

rural,  1327 

sanitation,  1325 

seats,  1331 

urinals,  1337 

ventilation,  1336 

water-closets,  1337 
Schorer,  770,  775 
Schottmuller,  137,  333,  700,  702 
Schroeder,  777,  787 
Schroeder,  R.  W.,  890 
Schroter,    1303 
Schryver,  741 
Schuberg,  362 
Schubert,  399 
Schiiflfler,  157 
Schiitz,  399 

Schultz,   595,   596,   600,  992 
Schultz,  K.,  748 
Sehultze,  981 
Schwab,  S.  I.,  446,  457 
Schwartz,  832,  833 
Schwarz,   871 
Scorbutus,  683 
Score  card,  butter,  786 

health  officers,  468 

milk,  788 

oysters,  841 

public  health  activities,  467,  468 
Scott,  198,  1441 
Scott,  Walter,  387 


Screening,    band   screen,    1200 

cylindrical  screen,   1201 

drum  screen,  1201 

inclined  disc  screen,  1201 

mosquitoes,    285 

Eeinsch-Wurl   screen,    1201 

sewage,  1200 

shovel-vane  screen,  1200 

water  purification,  1128 

wing  screen,  1200 
Scurvy,   683 

antiscorbutics,  685 

experimental,   684 

infantile,   683 

prevention,    685 
Scutigera,  317 
S«arcy,    687 

Sedentary  occupations,  1291 
Sedgwick-Rafter  method,  1084 
Sedgwick,  W.  T.,  109,  127,  465,  521,  915, 
946,  991,  1148,  1168,  1173,  1178, 
1181,   1185,  1216 
Sedimentation,  sewage,  1201 

water  purification,  1129 
Seed  virus,  7 
Seeds,  850 
Segregation,    defectives,   611 

heredity,  625 

lepers,  418 

tuberculosis,  182 

venereal  diseases,  81 
Seippel,  69 

Self -purification,  of  streams,  1109 
Sellards,   151,  215,  918,  920 
Selmi,  721,  722 
Semple,  41 

Sensitization,  598,  599 
Sepsin,    723 

Septic  sore  throat,  220,  780 
Septic  tanks,  1202 
Septicemia,  525 
Serbian  barrel,  367 
Sergent,  265,  373 
Serum   anaphylaxis,   594,  598 
Serum  sickness,  598 

diphtheria,  208 
Settling  tanks,  1202 
Seven-day  fever,  361 
Sevene,  1303 
Sewage,  1191 

composition,  1194 

dilution  in  streams,  1197 

disinfection,   1209 

fish  and,  1198 

grease,  1204,  1477 

manurial  value,  1209 

plumbing  and,   1196 

quantity,  1194 

streptococci,  1094 


1554 


INDEX 


Sewage  disposal,  1191 

combined  systems,  1193 

cooperative   sanitation,   1212 

dUution,  1196,  1198 

dissolved  oxygen,  1197 

dry-earth  system,  1192 

pail  system,  1192 

removal  fecal  matter,  1191 

rural,  1192,  1213 

separate  systems,  1193 

storm  water,  1194 

streams,  1196 

towns,  1192 

urban,  1192 

water-carriage  system,  1192 

See  also  Cesspools;   Privies;    Stream 
pollution 
Sewage  treatment,  1199 

activated  sludge  tanks,  1208 

bacterial  efficiency  of  processes,  1210 

band  screen,  1200 

broad  irrigation,  1205 

chemical  precipitation,  1203 

choice  of  methods,  1209 

cylindrical    screen,    1201 

contact  beds,  1206 

digestion  tank,  1202 

disinfection,   1209 

drum  screen,  1201 

efficiency,  bacterial,  of  processes,  1210 

Emscher  tank,  1202 

filters,  trickling,  1207 

filtration,  intermittent  sand,  1205 

fundamental  treatment,  1200 

grease,  recovery,  1204 

grit  chambers,  1201 

Imhoff   tank,   1202 

inclined  disc  screen,  1201 

intermittent  sand  filtration,  1205 

management  of  works,   1210 

Miles  process,  1204 

plants  as  nuisances,  1211 

preparatory  processes,  1200 

purification  processes,  1204 

Eeinseh-Wurl  screen,  1201 

screening,   1200 

sedimentation,   1201 

septic  tanks,   1202 

'settling  tanks,  1202 

shovel-vane  screens,  1200 

sludge  disposal,   1208 

subsurface    irrigation,    1204 

trickling  filters,  1207 

vs.   water  filtration,   1199 

wing  screen,   1200 
Sewall,  965 
Sewer  gas,  948,  1195 

accidents,  951 

bacteria,  950 


Sewer  gas,  cases  of  death,  952 

diphtheria,  193 

explosions  due  to,  952 

in  settling  tanks,  952 
Sewage  systems,  1193 
Sewers,   accidents,  951 
prevention,  954 

air,  950 

district,  1193 

fiushing,  1195 

house,  1193 

intercepting,  1193 

lateral,  1193 

relief,   1193 

storm,  1193 

streams,  dilution,  1197 

trunk,   1193 

underdrains,  1193 

ventilation,  954,  1195 
Sex  hygiene,  73,  448 

continence,  79 

See  also  Venereal  prophylaxis 
Sex  instinct,   and  mental   diseases,  441 
Seymour-Jones  method,  403,  404 
Shakes,  1312 

Shakespeare,  125,  126,  311 
Shakespeare,  William,  346,  491 
Sharp,  612 
Shattenfroh,  403 
Shattenfroh  method,  404 
Shaving  brushes,  anthrax,  402-404 
Shaw,  408,  410,  921 
Shaw,  E.  E.,  1330,  1332,  1335,  1350 
Shaw,  W.  N.,  893,  927 
Sheehau,  1445 
Sheele,  866 
Shell  shock,  442 

malingering,  444 

among  officers,  443 

among  prisoners,  444 

treatment,  445 

in  World  War,  442 
Shellfish,   840.     See  also  Oysters 
Shennan,  172 
Sheppard,  391 
Sheroux,  417 
Shibayama,  702 

Shiga,  148,  149,  349,  700,  1180 
Ships,  cargo,  518 
disinfection,  511 
fumigation,   513 
precautions,  518 
Shirata,  319 

Shock,   shell.      See  Shell   shock 
Shoes,  of  the  soldier,  1456 
Shovel-vane  screen,  1200 
Shuey,  P.,  933 
Sickness  insurance,  1291 
records,   1255 


INDEX 


1555 


Siderosis,  932,  1314 

Siebenmann,  1321 

Siebold,  852 

Sibcr,  688,  692 

Silicosis,  932 

Silver  salts,  disinfection,  1407 

Simmonds,  739 

Simmons,   116,   195 

Simon,  48 

Simond,  296,  326 

Simonds,  313 

Simonds,  J.  P.,  1009 

Simpson,  146 

Sisco,  D.  L.,  760,  707 

Sites,  camp,  1465 

Sjoo,  A.,  1421 

Skin  diseases,  1347 

Skofield,  E.  M.,  871 

Slack,  196 

Slaked  lime,  1416 

Slatineau,  415 

Sleeping  sickness,  317 

prevention,  319 
Slichter,  1033 
Sling  psvchrometer,  901 
Slow  sand  filtration,  1113,  1125 
Slows,  782 
Sludge,  activated  tanks,  1208 

disposal,   1208 
Slye,  AI.,  647 
Smallpox,  1 

chickenpox,  differential  diagnosis.  18, 
295 

and  cowpox,  unity,  25 

disinfection,  35 

epidemiology,  29 

immunity,  14 

vaccination   scars  and,  17 

inoculation,  26 

insects,  31,  313 

isolation,  35 

kinderblattern,  28 

modes  of  infection,  30 

mortality,  34,  36,  37 

prevalence,  28 

propustule,  30 

quarantine,  504 

references,  38 

resistance  of  the  virus,  31 

in  the  vaccinated  and  unvaccinated, 
31-33,  36,  37 

virus,   30,  31 
Smillie,  W.  G.,  781 
Smirnoff,  224 

Smith,  264,  355,  356,  959,  1153 
Smith,  A.,  431,  926 
Smith,  A.  H.,  685 
Smith,  B.  H.,   749 
Smith,  C.  S.,  731 


Smith,  Claude,  156 

Smith,  G.,  937 

Smith,  H.  K.,  1174,  1175 

Smith,  H.  ¥.,  1314 

Smith,    Theobald,    101,    165,    200,    220, 

259,  589,  684,  700,  701,  781 
Smoke,  926 

Eingclmann  chart,  929 
Smoking,  737 
Snails,  265 

fresh  water,  265 
Snail  poisoning,  846 
Snow,  57 

Snow,  John,  143,  1161,  1164 
Snow  blindness,  918 
Soaps,   disinfection,    1424 

iodid  of   mercury,   1425 

medicated,  1424 
Sobel,  365 
Sociology,  620 
Sodium  bicarbonate,  749 
Sodium  fluorid,  747 

roaches,  384 
Sodium  nitrate,  747 
Sodium  salicylate,  316 
Soil,  991 

acanthocephala,  1013 

adsorption,   995 

air,   996 

animal  matter,  994 

anthrax,  1008 

Asearis  lumbricoides,  1012 

azobacter,  1001 

bacteria,  1003 

carbon  cycle,   1002 

carbon  dioxid,  996 

cestoda,  1013 

cholera,  1010 

classification,  992 

clay,  992 

composition,   993 

denitrification,   1001 

dirt,   1005 

diseases,  1007 

fats,  1002 

flukes,  1012 

general  considerations,  991 

goit«r,  1010 

hookworm   disease,   1011 

humus,  992 

influence  on  health,  1007 

loam,  992 

malignant  edema,  1008 

mineral  matters,  994 

moisture,  997 

muck,  994 

nematoda,  1013 

uitrobacter,  1000 
I        nitrogen  cycle,  998 


1556 


IN^DEX 


Soil,  nitromonas,  1002 

peat,  994 

permeability,   995 

physical  properties,  994 

pollution,  1004 

porosity,  995 

protozoa,  1012 

relation  to  disease,  1003 

roundworms,  1013 

subsoil  drainage,  997 

surface  configuration,  993 

Taenia  saginata,  1012 

Taenia  solium,  1012 

tapeworms,   1013 

temperature,  995 

tetanus,  1007 

thorn-headed  worms,  1013 

trematoda,  1012 

Trichuris   trichiura,    1012 

tuberculosis,  1011 

typhoid  fever,  126,  1009 

vegetable  matter,  994 

water,  996 

water  capacity,  995 
Soil  pollution,  hookworm,  158 
Solanin,  861 
Solanin  poisoning,  861 
Soldiers,  personal  hygiene,   1449,   1454, 
1459 

training,    1449 

See  also  Military  hygiene 
Soletsky,  196 
Solutol,  1413 
Solveol,  1413 
Sommer,  416 
Sommerfeld,  1294,  1314 
Sommerfeld,  P.,  813 
Sommerville,   1419 
Soper,  G.  A.,  114,  842,  1177 
Sorel,  414,  420 
Sour  milk,  769 
Southard,  E.  E.,  432,  452 
Soxhlet  method,  801 
Spaeth,  1285 

Species,  of  hookworm,  154 
Specificity,  537 

anaphylactic  reaction,  596 

germicides,   1356 

insecticides,  266 

insects,  260 
Spencer,  H.,  639 
Sphacelinic  acid,  856 
Spieler,  174 

Spirillum    obermeieri,    361 
Spirochaeta,  361 
Spirochaeta  carteri,  361 
Spirochaeta  duttoni,  361 
Spirochaeta  icterohemorrhagia,  335 
Spirochaeta  morsus  muris,  332 


Spirochaeta  pallida,  55,  57,  62 

Spirochaeta  recurrentis,  361 

Spiroschaudinniae,  361 

Splenic  anemia,  380 

Splenic  fever,  401 

Spooner,  132 

Sporadic,  definition,  464 

Spotted  fever,   250 

Spraying  method  of  disinfection,  1395 

Sprays,  arsenic,  279 

copper,  279 

lead,   279 
Springs,   1041 
Sprinkling  filters,  1207 
Sputum,  disinfection,  1434 
Squirrels,  328 

ground,  326 

plague,  344 
Squirrel  flea,  327 
S.  S.  Joshua  Nicholson,  409 
S.  S.  Minnehaha,  342 
Stables,  disinfection,  1428 
Stanton,  669,  679 
Starvation,  674 
Statistical  methods,  631 

average,  632 

character,  634 

classes,  634 

coefficient  of  variability,  636 

definitions,  634 

deviation,  634,  636 

groups,  634 

mean,  634 

median,   635 

mode,   635 

normal   curve,   633 

quartile,   635 

references,  638 

variable,  634 

variate,  634 

See  also  Vital  statistics 
Statistics,  birth,  1235.     See  also  Birth 
statistics 

defectives,  613 

hospital,  1255 

marriage,    1233.     See   also   Marriage 
statistics 

mortality,   1259.     See  also  Mortality 
statistics 

morbidity,  1242.     See  also  Morbidity 
statistics 

vital,  1225.     See  also  Vital  statistics 
Steam,  disinfection,  1379 
Steam   heat,   987 
Stedman,  H.  E.,  457 
Steel,   264,   320 
Steel   grinder's  phthisis,  932 
Steenbock,  685 
Stefansky,  414 


INDEX 


1557 


Stegomyia  argentens,  29o 
Stegomyia   calopus,   295,   297 

description,   298 

flight,  300 

habits,  298 
Stegomyia  fasciatus,  295 
Steincrt,  396 
Steinfield,  234 
Stephens,  318,  388 
Stephens,  J.  W.  W.,  264,  385 
Stephenson,   90 
Sterility,  and  gonorrhea,  68 
Sterilization,  defectives,  612 

definition,  1351 

glassware,   1382 

rubber  tubing,  1382 

shaving  brushes,  404 

tetanus  spore,  102 
Stern,  587 

Sternberg,  233,  302,  1366,  1415 
Stevens,  E.  M.,  1350 
Stewart-Slack  method,  797 
Stewart,  W.  J.,   100 
Steyer,  889 
Sticker,  417 
Sticky  fly  paper,  272 
Stiles,    153,    154,    157,    158,    162,    345, 

842,  1014 
Still,  172 
Stillbirths,  477 
Stillman,  233 
StimmeU,  116 
Stimson,  54,  344,  1367 
Stitt,  305 
Stokes,  85 

Stomoxys  calcitrans,  308,  310,  320,  391 
Stomoxys  nigra,  320 
Storage,  water  purification,  1112,   1128 
Storch  test,  810 
Storm  sewers,  1193 
Storm  water,  1194 
Stoves,  Franklin,  986 
Straddle  pit  cover,  1474 
Stramonium  leaves,  268 
Straus,  43 
Straus,  I.,  191 
Straus  pasteurizer,  792 
Strauss,   391,   394 
Strauss,  X.,  791 
Strauss  reaction,  glanders,  398 
Stream  pollution,  1196 

biological  equilibrium,  1198 

hygienic  aspects,  1198 

protection  against,  1199 
Streams,  self -purification,   1109 
Street  virus,  44 
Streptococci,  in  milk,  781 
Streptococcus   coBglomeratus,   220 
Streptococcus  equinus  fecalis,  313 


Streptococcus  mucosus,   230 

Streptococcus  salivarius,  313 

Streptococcus  scarietina-,  220 

Streptococcus  vaccine,  224- 

Streptothrix  muris  ratti,  333 

Stripping,  1031 

Strong,   148,   349,   679,  682,   700 

Strong,  R.  P.,  376 

Strongyloides  stercoralis,  155 

Struma,  1151 

Struthers,  L.,  483 

Strychnin,  340 

Stiller,  1297 

Subsoil  drainage,  997 

Sugai,  414 

Sugar,  milk,   759 

Sulphur,  269 

Sulphur,   dips,   270 

fleas,  269 

flowers,  269 

fumigation  of  ships,  517 

lice  and,  269 

mites  and,  269 
Sulphur  dioxid,  269,  505,  949,  1396 

and  cyanid  contrasted,  516 

rats,  516 

roaches  and,  384 

for   ships,    514 

See  also  Disinfection,  sulphur  dioxid 
Sulphur  furnace,  1400 
Sunburn,   918 
Sunlight,  917 

disinfection,  1375 

fluorescent  dyes,  918 

water  purification,  1112 
Surface  waters,  1026 
Surra,   264,   320 
Surveys,   sanitary,  492 
Susceptibility,   definition,  523 
Sutton,  304,'  1066,  1370 
Swift,  H.,  376 
Swimming  pools,  1182 

disinfection,   1183 

sanitation,  1182 
Swine  plague,  828 
Swithinbank,  780 
Swithinbank,  H.,  813 
Sydenham,  240 
Sylphonathol,  1412 
Symbiosis,  525 

disinfection,  1354 

leprosy,  413 

tetanus,  96 
Symmers,  173 
Syphilis,  55 

Baume  's  law,   646 

calomel  ointment,  65 

chancre,  58,  61 

Colle's  law,  646 


1558 


INDEX 


Syphilis,    congenital    transmission,    60, 

644 
d'emblee,  645 
diagnosis,  59 
extragenital  chancres,  60 
fatality,  59 

feeble-mindedness  and,  437 
general  paresis,  434 
hereditary   transmission,   645 
historical  note,  56 
Hunterian  chancre,  58 
immunity,  63 
infant  mortality,  481 
infectiousness  of  lesions  and  tissues, 

61 
and  kissing,   61 
and  life  insurance,  63 
locomotor  ataxia  and,  435 
marital,  60 
marriage  and,  64,  436 
mental  deficiency  and,  436,  437 
mental  diseases  and,  434 
methods  of  transmission,   60,  645 
period  of  incubation,  55 
prevalence,   57 
Prof  eta's  law,  646 
prophylaxis,  65 
salvarsan,  85 

Spirochaeta  pallida,  55,  57,  62 
stages  of  disease,  58 
standard  of  cure,  65 
summary,  67 
treatment,  85 
Treponema  pallidum,  55 
tuberculosis  and,   178 
vaccination  and,  22 
Wassermann   reaction,   59.     See  also 

Wassermann  reaction 
yaws  and,  411 

Tabanus,  308 

Tabanus  lineola,  320 

Tabanus  tropicus,  320 

Tabardillo,  372 

Taenia  echinococcus,  836 

Taenia  saginata,  265,  835,  1012 

Taenia  solium,  265,  834,  1012 

Talbot,  604 

Tanks,  activated  sludge,  1208 

digestion,  1203 

Emscher,  1202 

Imhofif,  1202 

septic,  1202 
Tapeworm,  828 

beef,  265,  835,  836 

dog,  265 

dwarf,   265 

fish,  265,  839 

measly,  834 


Tapeworm,  pork,  265,  834 
rat,  265 

soil,  1013 
Tar  camphor,  1413 
Tarbagan,    326 
Tardieu,   50,   1296 
Tarozzi,  711 
Tartar  emetic,  382 
Taste,  water,  1050,  1054 
Taussig,  69,  322 
Taute,  318 
Taylor,  391,  744 
Teague,  111,  348 
Teeth,  1343 

school  children,  1343 

recruits,  1448 

See  also  Oral  prophylaxis 
Teleky,  1296 
Temperature,  air,   895 

ground  water,  1034 

importance  of  wet-bulb,  907 

infant  mortality  and,  894 

methods  of  recording,   895 

relation  to  health,  904 

soil,  995,  1007 
Tentage,  for  soldiers,  1467 
Tents,  1467 

care,  1468 
Terminal  fumigation.     See  Fumigation 
Terni,  349 
Tertian  fever,  286 
Terzi,  287 
Tetanus,   95 

carriers,  97 

debridement,  102 

etiology,  95 

glycerin,  23 

historical  note,  95 

idiopathic,  99 

incubation  period,  100 

mocezuelo,   99 

of  the  newborn,  99 

occurrence  of  spores,  97 

puerperal,  99 

resistance  of   spores,  97,   100 

sterilization,    102 

symbiosis,  96 

tests  for,  in  vaccine  virus,  22 

toxin,  553 

treatment  of  wounds,  102 

trismus  neonatorum,-  99 

vaccination    and,    22 

in  vaccine,  98 

wound  complication,  96,  98,  103 

tetanus  antitoxin,  1U3,  568 

standardization,  568 

test,  569 
Texas  fever,  259,  356 
Textile  industries,  1316 


INDEX 


1559 


Textile  mills,  humidity  in,  1817 

Thackrah,  948 

Thaiiiehayn,  50 

Theiler,    320 

Theobald,  F.  V.,  287,  385 

Thermometers,  bimetallic,  895 

disinfection,    1437 

mercurial,  895 

registering,  895 
Thesen,  843,  844 
Theze,   680 
Thiem,  1033 
Tliom,  655,  707,  713 
Thomas,  1461 

Thompson,  20,  629,  651,  682,  814 
Thompson,  J.  A.,  326,  659 
Thompson,  W.  G.,  1324 
Thomson,  John,  608 
Thorn-headed  worms,   1013 
Three-day  fever,  322 
Thresh,  842 
Thresh,  J.   C,   1189 
Thro,  392 

Throat,   school   children,   1346 
Tlirushfield,  192 
Thuillier,  54 
Thwait^s,  W.,  949 
Thymol,  hookworm  disease,  158 
Thyroid  gland,  1150 
Tibbies,  682 
Ticks,  354 

arsenical   dips,   355 

bites,  354 

cattle,  356 

cattle    dips,    355 

eradication,  360 

hereditary    transmission    of    disease, 
355 
.     hereditary  transmission   of   relapsing 
fevers,  362 

life  cycle,  354 

relapsing  fevers,  361 

Rocky  Mountain  spotted  fever,  358 

table,  264 

Texas  fever,  356 
Tick  fever,  356,  361 
Tidswell,  414 
Tileston,   333 
Timoni,  27 
Tin,  741 
Tizzoni,  47,  312 
Tobacco,  94 

as  an   insecticide,   271 
Todd,  195,  264,  317,  318,  320,  321,  362 
Toledo,  97 
Tolerance,  524 
Tollwut,   38 
Tonney,   778 
Topley,  1423 


Topography,  camp  sites,  1465 

Tornell,  V.,  1421 

Torrey,  313,  314,  770 

Towle,  604 

Towns,  sewage  disposal,  1192 

Toxemia,  525 

Toxic  amblyopia,  94 

Toxicity,  525 

Toxin-antitoxin  mixture,  200,  204 

Toxins,  549,  553 

B.  botulinus,  553,  712 

definition,  553 

diphtheria,  553 

endo-,  553 

exo-,  553 

fatigue,  960 

Gaertner  group,  703 

incubation  period,  555 

neuro-,  553 

plant,  854 

tetanus,  553 
Toxoids,  549 
Toxon,  557 

Toxophore  group,  549 
Trachoma,  92 

diagnosis,  93 

mode  of  infection,  93 

prevalence,  93 

treatment,  93 

virus,  92 
Trades,  dusty,  1313 
Training,  the  soldier,  1449 
Transfer,  modes  of,  460 
Transportation,  troops,  1434 
Trask,  121,  195,  215,  222 
Trask,  J,  W.,  1225 
Travelers,  disinfection  of  "water,  1420 
Tredgold,  426,  430,  436 
Trematoda,  soil,  1012 
Trembles,  782 
Trench  fever,  376 

lice,  376 

riekettsia    pedieuli,    377 

transmission,  376 
Trenches,  1478 

Treponema  pallidum,   55,   435 
Treponema  pertenue,  410,  411 
Triatoma  magista,  321 
Tri-brom-/3-naphthol,   1411 
Trichina,  pickling,  736 
Trichinella  spiralis,  265,  337,  831 

life  cycle,  831 
Trichinosis,   265,   830 

prevention,  833 

rats,  337,  830 

refrigeration  of  meat,  834 

Trichinella   spiralis,    831 
Tri-chlor-/3-naphtho],   1411 
Trichuris  trichiura,    1012,   1181 


1560 


INDEX 


Trickling  filters,  1207 

Trikresol,  1411.     See  also  Cresol 

Trillat,  1044 

Trilier,  687 

Trioxy-methylene,  1391 

Trismus  neonatorum,  99 

Tropical  dysentery,  150 

Tropical  ulcer,  381 

Tropics,  military  hygiene,  1479 

Tropins,  574 

Trouessart,  329 

Trudeau,  E.  C,  179,  183 

Trunk  sewers,  1193 

Trypaflavine,   1422 

Trypanosoma  brucei,  320 

Trypanosoma  castellani,  320 

Trypanosoma  cruzi,   321 

Trypanosoma  dimorphon,  320 

Trypanosoma  equinum,  320 

Trypanosoma  equiperdum,  320 

Trypanosoma  evansi,  320 

Trypanosoma  gambiense,  317,  320,  338 

Trypanosoma   grussei,   317 

Trypanosoma  lewisi,   317,  320 

Trypanosoma  rhodiense,  318 

Trypanosoma  theileri,  320 

Trypanosoma   fevers,   317 

Trypanosomes,  table,  320 

Trypanosomiasis,    317 

Trytophan,  720 

Tsetse  fly,  317 

Tsistowitch,  586 

Tsutsugamushi  disease,  361 

Tubercle   bacilli,   avian,   165,   166 

bovine,  165 

dose,  177 

human,   165 

in  milk,   777,  779 

resistance,  180 

sunlight,  181 

thermal  death  point,  180 
Tubercular,   165 
Tuberculin,   188,   603 

leprosy,  419 
Tuberculosis,  163 

aerogenic  infection,   170 

anaphylaxis,  178,  602 

anti-tuberculosis  associations,   183 

avian,   165,   166 

bovine,   165,   166 

Bang  method  of  suppression,  189 
prevention,    188 
testing  of   cattle,    ]89 

care  in  the  home,  187 

childhood   infection,    175 

in  children,  187 

clinics,   preventive,   186 

contact   infection,   176 

Cornet-Koch  theory,   170 


Tuberculosis,  death-rate,  decline,  182   . 

decline,  181 

disinfection,   186 

dispensaries,  188 

disposal  of  sputum,  185 

droplet  infection,  172 

dust,   171 

early  diagnosis,  186 

education,  185 

flies,  175 

hand-to-mouth  infection,  176 

health  insurance,   190 

hereditary  tendency,  179 

hereditary  transmission,  179,  645 

housing  conditions,   186 

immunity,  177,  545 

immunization  of  cattle,  1 79 

industrial  conditions,  187 

in  industry,  1323 

infant  mortality,  481 

infection  in  childhood,  175 

ingestion  infection,  172 

isolation,  182 

local  campaign,  190 
collateral  benefits,   190 

measles  and,  178 

meat,  826 

milk,    777 

miners,  1320 

modes  of  infection,  170 

morbidity,  164 

mortality,   164 

notification,    185 

open-air   schools,   188 

outlook,  191 

personal      prophylaxis,       176,      177, 
184 

prevalence,  163 

prevention,  181 

preventive  clinics,  186 

references,  191 

resistance   of   virus,   180 

sanatoria,   182 

school-hospitals,  188 

segregation,  182 

social  aspect,  164 

soil,  1011 

superinfections,   177 

susceptibility,  177 

syphilis  and,  178 

vaccination  and,  22 

von  Pirquet  test,  175 

Wassermann  reaction,  178 

water  and,  175 
Tuberculous,  165 
Tubers,  851 
TuUoch,  96 
TunnicliflE,  746 
Tunniclifif,  K.,  210,   247,  333 


INDEX 


1561 


Turneaure,  F.  E.,  1189 
Turner,  84 
Turner,  George,  418 
Turpentine,   Mich,  wood,   268 

Oregon  fir,  268 
Tyler,  687 
Tyndali,  987,  9.19 

Typhoiil-colon    group.      See    Colon-ty- 
phoid group 
Typhoid  fever,  105 
attitude,  105 
bacillus  carriers,  113 
chronic,   113 
convalescent,  113 
control,   115 
passive,  113 
prevalence,  113 
recognition.  111 
blood  cultures.  111 
butter,  123 
buttermilk,  123 

channels  of  entrance  and  exit  of  ba- 
cillus, 109 
cheese,  123 
contact  infection,  126 
cream,  123 
diagnosis,  110 

disinfection   of   excreta,   133 
dust,  126 

epidemic,  1168,  1188 
Albany,  N.  Y.,  1169 
Alleghany,  Pa.,  1178 
Ashland,  Wis.,  1175 
Binghamton,  N.  Y.,  1169 
Butler,   Pa.,   1178 
Chicago,  111.,   1179 
Ithaca,  ]S".  Y.,  1177 
Jersey  City,  N.  J.,  1169 
Lausen,  1168 

Lawrence,  Mass.,  1169,  1178 
Lowell,  Mass.,  1169,  1178 
Mankato,  Minn.,  1176 
New  Haven;  Conn.,  1174 
Newark,  N.  J.,  1169 
Ogdensburg,  N.  Y.,  1188 
Paterson,  N.  J.,  1169 
Pittsburgh,  Pa.,  1178 
Plymouth,  Pa.,  1173 
epidemics  due  to  oysters,  842 
feces.  111 
flies,  125,  312 
fomites,  126 
fruits,  124 
historical  note,  106 
ice,  120,  1188 
ice  cream,  123 
incubation  period,  106 
lipovaceines,  128 
management  of  case,  133 


Typhoid  fever,  niili<,   108,   121,  780 

modes  of  spread,  118 

mussels,  124 

oysters,   124,  842 

paratyphoid,     differential     diagnosis, 
137 

personal  prophylaxis,  135 

polyvalent  vaccine,  132 

jirevalence,   107 

preventive  inoculations,  128 

privies,  1191 

residual,   108 

resistance  of  the  virus,   116 

salad  dressing,  125 

soil,   126,  1009 

summary,    135 

"Typhoid  Mary,"   114 

urine.   111 

vaccination,  130,  132 

vegetables,  124 

water,  1167 

water-borne,   118 

Widal  reaction,  115 
"Typhoid  Mary,"  114 
Typhoid  vaccine,  128 

Eawlins  strain,  129 
Typhus  abdominalis,  105 
Typhus  exanthematicus,  370 
Typhus  fever,  370 

bacillus,   proteus-like,   373 

etiology,  372 

lice,  373 

personal  prophylaxis,  375 

prevention,  374 

quarantine,  507 

rickettsia,   372 

transmission,  373 

Weil-Felix  reaction,  373 
Tyrosin,   720 
Tyson,  1313 
Tyzzer,   31 


Udranszky,    724 

Uhlenhuth,  587,  597,  703,  1421 

Ultraviolet  light,  918 

Ultraviolet  rays,  disinfection,  1375 

water  purification,  1144 
Uncinariasis,  153 
Underdrains,  in  sewers,  1193 
Undernourishment,  674,  676 
Underwear,  of  the  soldier,  1456 
L^nderwood,  W.,  738 
Unger,  396 

Urban  sewage  disposal,  1192 
Urine  soakage  pit,  1476 
Urizio,  366 
Uroglena,  1051 
Urtica  doica,  855 


1562 


INDEX 


Vacca,  4 
Vaccination,  1,  3 

accelerated  reaction,   18,  19 

anaphylaxis,  603 

areola,  12 

arm-to-arm,  5 

autovaccination,    21 

certificates,  14 

chickenpox,  396 

claims,  20 

compulsory,  25 

course  of  eruption,  12,  14,  15 

dangers  and  complications,  21,  24 

definition,    3 

dressing,  11 

dry  points,  6 

exposed  persons,  20 

foot-and-mouth  disease,  24,  406 

generalized,  21 

historical  note,  1 

immediate  reaction,  18,  19 

impetigo    contagiosa,   22 

incision,  10,   11 

indices  of  a  successful  take,  12 

Jenner's  claim,  20 

leprosy,  22 

methods,  9 

operation,  11 

papule,  12 

primary  take,  18,  19 

puncture,  9 

recruits,  1448 

revaccination,  18,  19 

scar,  13 

scarification,  10 

school  children,  1350 

site,  10 

spurious  takes,  9 

symptoms,  13 

syphilis,  22 

tetanus,  22 

time,  17 

tuberculosis,   22 

typhoid,  129,  130 

vesicle,  12 

wound  infections,  21 
Vaccine  virus,  4,  5 

bacteria,  7 

Beaugency  strain,  5 

bovine,  5 

definition,  4 

dry,   5 

forms,  5 

fresh,  5 

government  control,  24 

glycerinated,  5,   6 

green,  6 

human,  4 

propagation,  8 


Vaccine  virus,  ripe,  6 

seed,  7 

tests  for  tetanus,  22 

vaccine  lymph,  5 

vaccine  pulp,  5 
Vaccines,  bacterial.     See  Bacterial  vac- 
cines, 

cholera,  145 

dysentery,  150 

influenza,  244 

lipovaecines,  536 

pneumonia,  236 

polyvalent,  132,  536 

sensitized,   535 

streptococcus,  224 

tetanus,  98 

typhoid,  128 

whooping-cough,  227 
Vaccinia,   3,  4,  26 

course  of  eruption,  12,  14,  15 
Vacuum  system  of  ventilation,  984 
Vaillard,   101 
Valentin,  957 
Vallee,  173 
Values,  relative,  of  public  health  work, 

466 
Varicella,  395 
Variola,  4 

Variola  inoculata,  26 
Variola  vera,  26 
Variolation,  26 
Varioloid,   20 
Varro,   287 
Van  Beneden,  630 
Van  De  Velde,  761 
Van  Ermengem,  698,  706,  708,  710,  711, 

713,  714,  716 
Van  Gehuchten,  53 
Van  Giesen,  52 
Van  Leen,  680 

Van  Slyke,  L.  L.,  724,  755,  808 
Vapor  tension,  898 
Variation,  heredity,  621 
Vaughan,   125,  126,  236,  381,  412,  552, 

703,  721,  723 
Vaughan,  V.  C,  1250 
Vedder,  57,  64,  66,  678 
Veenboer,  746 
Vegetable  dyes,  727 
Vegetables,   typhoid   fever,   124 
Veillon,  97 
Venable,  W.  M.,  1225 
Venereal  diseases,  54 

alcohol,  80,  491 

attitude,  75 

calomel  ointment,  81 

continence,  79 

dourine,  54 

education,  76 


INDEX 


1503 


Venereal   diseases,  "fourth,"  211 

liosi)itals   and   clinics,   85 

notification,  78 

personal  prophyljixis,  79 

prevalence,  7.'? 

prophylaxis,  81,  84 

prostitution,  SO,  86 

segregation,  81 

IT.  S.  Army  and  Navy,  74 

See      also      Chancroid;      Gonorrhea; 
Ophthalmia  neonatorum;    Syphi- 
lis 
Venereal  projihylaxis,  73 

argyrol,  82 

condom,  84 

lanolin,  06,  82 

mechanical  methods,  84 

method  of  using  prophylactic,  82 

package  K,  82 

protargol,  82 

Sanitube,  82 

summary,  86 

See      also      Chancroid;      Gonorrhea; 
Ophthalmia   neonatorum ;    Syphi- 
lis; Venereal  diseases 
Vennen  vs.  New  Dells  Lumber  Company, 

1291 
Ventilation,  966 

air  ducts,  977 

air  washing,  968 

amount  of  air  required,  971 

aspiration,  980 

cooling,  988 

dead-space  air,  970 

efficiency,  973 

external,   979 

factor  of  safety,  971 

Fairfield  system,  983 

general  considerations,  966 

inlets,  977 

King  system,  983 

mechanical,  984 

natural,  979 

odors,  body,  968 

outlets,  977 

perflation,  980 

plenum   system,  984 

purpose,  966 

recirculation,  968 

respiratory  vitiation,  969 

rooms,  size  and  shape,  975 

schools,  1336 

sewers,  954 

standards  of  purity,  973 

thermal  circulation,  980 

vacuum  system,  9S4 

vital  capacity  of  lungs,  969 

window,  979 

See  also  Air;  Heating 


Ventilators,  Ellison  's  bricks,  980,  982 

Fairfiehl,  983 

Grid,  980 

Hinckes-Bird,  980,  982 

Hopper,  980 

King,  983 

Louvred  outlets,  980 

McKinnell,  980 

Sheringham's  valve,  980,  982 

Stevens,  982 

Tobin  's  tube,  980,  982 

window,  979,  983 
\'eratrum  viride,  852 
Verhoeff,    1376 
Vernal  catarrh,  93 
Vesicle,  Jennerian,  12 

vaccination,  12 
Vessels,  in  quarantine,  502 
A'etch  poisoning,  857 
Vetch  seeds,  857 
A^ianna,  382 
Mazemsky,  492 
Vibrio   cholerae,  139 
A'ibrion  septique,  96,  1008 
Villeman,  J.  A.,  164,  191 
Vincent,  101,  210,  211 
Vincent's  angina,  210 

oral  prophylaxis  and,  211 
Virulence,  525,  527 
Virus,  Danysz,  343,  702 

fixed,  44 

immunity,  534 

infantile  paralysis,  389 

measles,  214 

rabies,  40,  41,  44 

rat,  343,  704 

smallpox,  30,  31 

street,  44 

trachoma,   92 

tuberculosis,  180 

typhoid,   116 
Vital  capacity  of  lungs,  969 
Vital  statistics,  1225,  1493 

causes  of  death,  1265,  1494 

constituents,   1225 

definition,  1227 

derivation,    1225 

development,  1227 

enumerators,  1225 

life  tables,  1276 

population,  based  on,  1228 

problems,  1494 

registration,  1226 

See  also  Birth  rates;  Census;  Death 
rates;  Infant  mortality;  Mar- 
riage; Morbidity;  Mortality 
rates;  Notifiable  diseases;  Popu- 
lation ;  Kegistration ;  Statistical 
methods 


1564 


INDEX 


Vitamins,  669 

antiscorbutic,  672 

fats,  670 

fat-soluble  A,  670 

food  preservation,  739 

milk,  759 

plant  foods,  850 

polyneuritic,  678 

table,  671 

watei;-sclub]e  B,  671 

water-soluble  C,  672 
Vitiated   air,   Black   Hole   of    Calcutta, 
956 

effect  of  diminished  oxygen,  957 

effect  of  increased  CO.,  957 

effects,  955 

poisons  in  expired  breath,  958 

reinspiration  of  inspired,  963 

by  respiration,  969 

S.  S.  Londonderry,  957 

summary,  964 
Vivosphere,  865 
Voges,   320 

Voges-Proskauer  reaction,  1091,  1093 
Volland,  176 
Ton  Behring,  177 
von  Bergen,  181 
von  Drigalski,  149 
von  Economo,  394 
von  Frisch,  730 
von  Hibler,  711 
von  Hoffman-Wellenhof,  959 
von  Pirquet,  C,   18,  19,   164,   191,  593, 

598 
von  Pirquet  tuberculin  test,  175 
A^orderman,  680 
Vulcanstein,  173 
Vulvovaginitis,  69 

complications,  70 

gonococcus,  69 

prevalence,  69 

prevention,  70 

transmission,  69 

Waage,  1363 

Wade,  196 

Wagener,  213 

Walden,  98 

Walker,  328,  1366,  1369,  1395 

Walker,  H.  E.,  962 

Wallgren,  176 

Wang,  167 

War  edema,  675 

War  gases,  1459 

blindness,  95 
War  neuroses,  444 
Ward,  203,  618,  934 
Ward,  R.  De  C,  450,  989 
Warren,  .1.  C,  250 


Vv^arthin,  62,  648 
Washburn,  779 
Washburn,   E.,   1283 
Washington,  G.,  30,  192 
Wassermann,  57,  587,  606 
Wassermann  reaction,  581 
antigen,  582 
complement,  582 
leprosy,   419 
marriage,  65 
mental  deficiency,  436 
syphilis,  59 
the  test,  583 
tuberculosis,  178 
Wasserscheu,  38 
Water,   1015-1486 
algae,  1051,  1054 

allowable  limits  of  impurities,  1097 
ammonia  albuminoid,   1069 
free,  1066 

significance,  1068 
analysis,  sanitary,  1048 
animal  parasites,  1181 
aquaphones,    1020 
B.  aerogenes,  1091 
B.  coli,  differentiation,  1093 
fecal,  1091 
non-fecal,  1091 
tests,   1092 

confirmation,  1093 
methyl  red,  1093 
presumptive,  1092 
types,  1091 
B.  typhosus,  1094 

bacteria,  determination  number,  1089 
kinds,  1090 
number,   1087 
bacteriological  examination,   1087 
boiled,  1112 
capacity  of  soil,  995 
catchment  areas,  1046 
chemical   analysis,    expression    of    re- 
sults, 1083 
chemical  disinfection,  1472 
chlorids,   1074 

determination,  1075 
chlorin,  1076 

determination,  1076 
cholera,   143,  461,   1095 
classification,  1016 
colon  bacillus,  1091.     See  also  B.  col 
color,  1055 

to  estimate,  1056 
platinum-cobalt  standard,  1056 
composition,  1015 
Darnall  filter,   1471,   1472 
diarrhea,  1180.    See  also  Diarrhea 
distilled,  1112 
drinking  fountain,  1184 


INDEX 


loGO 


Water,  dual  supply,  1021 
dysentery,  1179.     Src  also  Dysentery 
feces,  1043 

filters,  lli;{.     Sea  also  Filters 
general  considerations,   101") 
goiter,  1150.     Sec  also  Goiter 
ground,  997.     See  also  U round  water 
hardness,  1061 

Clark 's  scale,  1064  . 

degrees,  1064 

to  estimate,  1063 

permanent,  1061 

table,  1064 

temporary,  1061 
infected,  1043  » 

inorganic  impurities,  1150 
iron,  1080 
iron  pipes,  1081 
Ishiji  filter,  1470 
lead,  1082 
lead  poisoning,  1155.     See  also  Lead 

poisoning 
limits,  allowable,  of  impurity,  1097 
Lyster  bag,  1472 
meter,  1021 

methods  of  analysis,  1048 
microscopical  examination,  1084 
military  hygiene,  1470 
Mills-Eeincke  phenomenon,  1148 
Nessler's  reagent,  1066 
nitrates,    1072 

to  estimate,  1073 
nitrites,  1071 

to  estimate,  1071 
non-potable,  1016 
non-specific  diseases,  1149 
odors,   1050 

determination,  1055 

prevention,  1054 

removal,  1054 
organic  matter,   1065 
overturn,   1031 
oxygen,  1077 

absorbed,  1077 

consumed,   1077 

determination,  1078 

dissolved,  1079 

required,  1077 
pipes,  iron,  1081 
pitometers,  1020 
plankton,   1084 
plumbisolvent,  1156 
pollution,    1043.      See    also   Polluted 

water 
potable,  1016 
properties,   1017 

purification.  See  Purification  of  water 
rain.     See  Eain  water 
reaction,  1059 


Water,  references,    1189 

relation  to  disease,   1147 

sample,    collection,    1049 

sanitary  analysis,  1048 
examples,  1099 
interpretation,    1096 

Sedgwick-Rafter   method,   1084 

sewage  streptococci,  1094 

soft,   1062 

softening,  Clark  method,  1062 
jxTMUitit,   1063 
zeolite,  1063 

soil,  996 

solvent  power,  1156 

sources,  1022 

specific  diseases,   1159 

spring,  1041 

stagnation,    1030 

storage,  1128 

storm,  1194 

stripping,  1031 

surface,   1026.     See  also  Impounding 
reservoirs;   Lakes;   Pond;  Rivers 

swimming  pools,  1182.  See  also  Swim- 
ming pools 

taste,  1050,  1054 

total  solids,  1060 

tuberculosis,   175 

turbidity,  1057 
to  estimate,  1058 

typhoid    fever,    118,    1167.     See   also 
Typhoid  fever 

used,  amount,  1018 

uses,  in  body,  1017 

Voges-Proskauer  reaction,  1091,  1093 

waste,  causes,  1020 
amount,   1018 

wells.     See  Wells 

winter  cholera,  1181 
Water  bag,  1480 
Water   filtration,   1199 
Water  gas,  944 
Water  vapor,  896 
Water-borne  cholera,  143,  1161 
Water-borne  typhoid,  118 
Water-carriage  system,  of   sewage  dis- 
posal, 1192 
Water-closets,  seats,  69 
Waterhouse,  B.,  2,  3 
Waterhouse,  Daniel  O.,  3 
Waterproofing,  clothing  of  the  soldier, 

1455 
Watson,  1194 
Weaver,  486 
Webb,.  179 

Wechsberg,   583,   584 
Wedgwood,  618 
Weichardt,  595,  960,  1153 
Weichel,  703,  704 


1566 


INDEX 


Weichselbaum,   174,   250 
Weigert,  547 
Weigmann,  771 
Weil,  16,  325,  862 
Weil-Felix  reaction,  373 
Weil's  disease,  335 
Weinberg,  96 
Weisman,  960 
Weismann,  608,  623 
Weismann,  A.,  658 
Weiss,  138 
Weiss,  H.,  712 
Welch,  264,  287,  552 
Welch,  Thomas,  250 
Welch's  gas  bacillus,  1009 
Weller,  1296 
AVellmann,  682 
Wells,  98 
Wells,   725,  1037 

artesian,  1037 

construction,  1038 

disinfection,  1041,  1437 

pollution,  1037 
Wells,  F.  L.,  455 
Wells,  L.,  448 
Wentworth,  215 
Werner,  417 

Werner-Schmidt  method,  800 
Wernstedt,  390,  391 
West  swab,  256 
Westphal  balance,  807 
Weyl,  1294 

Wejl,  T.,  521,  1324,  1350 
Wheeler,  120 
Wheeler,   A.  W.,   1188 
AVheeler,  S.  H.,  983 
Whentham,  618 
Wherry,  322,  344,  414,  416 
Whipple,    118,    930,    937,    1020,    1175, 

1178,  1179,  1181,  1219 
Whipple,  G.   C,   638,  1084,  1189,  1191, 

1278 
White,  73,  301,  412 
White,  W.  A.,  423,  455,  456 
White,  W.  C,  933 
White  lead,  1298 
Whitelegge,  1365 
Whitewash,  1416 
Whitla,  173 
Whittaker,  1180 
Whooping-cough,  224 

Bordet-Gengou  bacillus,   225,   227 

immunity,  226 

mode  of  transmission,  225 

mortality,  212,  228 

prevention,  226 

schools  closed,  227 

vaccines,  227 
Wickman,  386,  390 


Widal,  576 

Widal  reaction,  115,  589 

Wilbur,  710 

Wilbur,  Cressy  L.,  119 

Wilder,  93,  265,  373 

Wiley,  682,  740,  744,  816 

Wiley,  H.  W.,  730 

Williams,  90,  179,  196,  832 

Williams,  A.  W.,  40,  240,  247 

Williams,  F.  E.,  455,  456 

Williams,  H.  S.,  457 

Williams,  L.  L.,  457 

Willis,  240 

Willis,  Thomas,  106 

Wilson,  357,  536,  623,  1474,  1475,  1479, 

1481 
Wilson,  E.  B.,  630,  631,  659 
Wing  screen,  1200 
Winogradsky,  1000,  1001 
Winship,  617 
Winslow,   780,  932,  937,  950,  960,  968, 

1165,  1217,  1290, 1296,  1314 
Winslow,  C.  E.  A.,  127,  183,  908,  911, 

916,  1189 
Winter  cholera,  139,  1181 
Winternitz,  248 
Wintgen,  862 

Wolbach,  264,  321,  359,  373,  374 
Wolfe,  Edwin  P.,  66 
Wolfson,  J.  M.,  427 
Won,  784,  813 
WoUstein,  M.,  229 
Wolpert,  884 
Wolpert  air  tester,  884 
Women  in  industry,  1287 
Wood,  687,  842 
Wood  alcohol,  94 
Wood  alcohol  poisoning,   1312 
Wood  dust,  1319 
Woodhull,  1482 
Woodman,  682 
Woodman,   A.  G.,  989 
Woodward,    169,   172 
Wool,  clothing,  of  the  soldier,  1454 
Wool-sorter's  disease,  402,  1321 
Wool-sorter's  pneumonia,  1315 
World   War,    experience   of,   in    mental 

diseases,  442 
shell  shock,  442 
Wosnitza,  710 

Wound  infections  and  vaccination,  21 
Wounds,  tetanus,  96,  98,  102 
Wright,  146,  236,  536,  537,  574 
Wright,  A.  E.,  107,  128,  130,  574 
Wright,  F.  S.,  483 
Wright,   J.    H.,    381 
Wut,  38 

Wyrsykowski,  42 
Wysokowiez,  45 


INDEX 


1567 


Xonopsylla  cheopis,  324 
X-ray,  in  leprosy,  419 
vVZ  theory,  140 
,  Cy lander,    1421 

1 

Vaws,  410 
Yellow  fever,  295 

aerial  conveyance,  300 

ininiunity,  296 

mosquito,   297.      See   also   Stegomyia 
calopus 

period  of  incubation,  extrinsic,  295 
intrinsic,  295 

prevention,  301 

contrasted   with   malaria,  303 

quarantine,  507 

references,  302 

Stegomyia  calopus.    See  Stegomyia 
Yersin,  265,  328,  348 
Y'ersin  's  serum,  350 


Yolfert,  20 

York,  318 

York,  J.,   1161,   1164 

Young,  499,  731,  1073,  1319 

Yule,  638 

Yule,  G.  U.,  1278 

Zammit,  409 

Zappert,   388 

Zeolite,    1063 

Zero   family,   615 

Ziemann,  293 

Zienka,  587 

Zinc   chlorid,   disinfection,    1408 

Zinc    salts,    disinfection,    1408 

Zingher,   196,   200,   204 

Zinsser,  Hans,  62,  75,  606 

Zweifel,   90 

Zurek,   703,   704 

Zygadnus,  852 


(10) 


Wickman, 


